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 S U P P " ]L E M E N T 
 
 TO THE THIRD EDITION OF THE 
 
 EMCYCLOPJEDI^ BRITAMjYICA, 
 
 OR, A 
 
 DICTIONARY 
 
 OF 
 
 ARTS. SCIENCES, 
 
 AND 
 
 MISCELLANEOUS LITERATURE. 
 
 IN TWO VOLUMES. 
 lUuftrated with Fifty Copperplates. 
 
 By GEORGE GLEIG, LL.D. F.R.S. Edin. 
 
 NON IGNORO, QUiE BONA SINT, FIERI MELIORA POSSE DOCTRINA, ET QU*: HON OPTIMA, 
 ALIQUO MODO ACOI TAMEN, ET CORRIGI POSSE. ClCERO. 
 
 VOL. I. 
 
 THE SECOND EDITION, WITH IMPROVEMENTS. 
 
 PRINTED FOR THOMSON BONAR, PARLIAMENT^^QUARE: 
 BY yOHN BtOffN, ANCHOR CLOSE, EDINBURGH. 
 
 1803. 
 
 [CnteteO In StutjonCTU iijsn.]
 
 SIB, 
 
 TO THE KIJVG. 
 
 AT proceeds frqm no vain confidence in my 
 pwn abilities^ that I presume to solicit for this Work 
 the Protection of a Monarch, who is not more exalted 
 in station^ than he is distinguished^ among the Poten- 
 tates of the Earthy by his 'Taste in Literature^ and his 
 Patronage of Science and the Arts, 
 
 In conducting to its conclusion the Encyclopedia 
 Britannica, / am conscious only of having been uni- 
 formly influenced by a sincere desire to do fustice to 
 those Principles of Religion, Morality^ and Social Order, 
 of which the Maintenance constitutes the Glory of Your 
 Majesty's Reign, and will, I trust, record Tour Name 
 to the latest Posterity, as the Guardian of the Laws 
 and Liberties of Europe,
 
 Iv DEDICATION. 
 
 T'he French Encyclope'die has been accused^ and 
 justly accujed, of having disseminated^ far and wide^ 
 the seeds of Anarchy and Atheism. If the Encyclo- 
 pjediaBritannica shall, in any degree, counteract the 
 tendency of that pestiferous Work, even these two Vo- 
 lumes will not be wholly unworthy of Tour Majesty's 
 Patronage ; and the Approbation of my Sovereign, 
 added to the consciousness of my own upright intentions ^ 
 will, to me, be an ample reward for the many years of 
 labour which I have employed on them, and on the 
 Volumes to which they are Supplementary . I am, 
 
 SIR, 
 Your Majesty's 
 
 Most faithful Subject, 
 
 And most devoted Servant^ 
 
 STimiiiG, \ 
 Dee. 10. 1800.J 
 
 GEORGE GLEIG,
 
 SUPPLEMENT 
 
 TO THE 
 
 Encyclopaedia Britannica. 
 
 ^^^^^^^^»^*»»^^n?t^j,-l»* •''■^^^^ 
 
 I ABE 
 
 ! Atacifcui A BACISCUS, in architefture, the fame with A- 
 
 ■ II jfx BACUS; (o'c 'whxch, ki Encyclopttdia. 
 
 Aberration. ABATIS, or Abattis, is, in military language, 
 
 ' the name of a kind of retrenchment made of felled trees. 
 
 When the emergency is fudden, the trees are merely 
 
 ; laid lengthwife befide each other, with their branches 
 
 I pointed towards the enemy, to prevent his approach, 
 
 whilft the trunks ferve as a breaftwork before thofe by 
 
 whom the abatis is raifed. When the abatis is meant 
 
 for the defence of a pafs or entrance, the boughs of the 
 
 trees are generally ftripped of their leaves and pointed; 
 
 the trunks are planted in the ground; and the boughs 
 
 are interwoven with each other. It is needlefs to add, 
 
 that the clofer the trees are laid or planted together, 
 
 the more fecure is the defence which they afford ; and 
 
 if, when they are planted, a fmall ditch be dug towards 
 
 the enemy, and the earth thrown up properly againll 
 
 the lower part of the aba 's, it will be very difficult to 
 
 pafs it if well defended. — Simes's Mililary Guide. 
 
 ABBREVIATION of fractions, in arithmetic 
 and algebra, is the reducing of them to lower terms ; 
 which is done by dividing the numerator and denomi- 
 nator by fome number or quantity which will divide 
 both without leaving a remainder of either. 
 
 ABERRATION, in optics (in Encycl.), refers 
 the reader to the article Optics, n" 17, 136, 173. It 
 fliould have referred him to Optics, n^ 17, and 251 — 
 
 ^BFRKATiON of the V'tfual Ray, Is a phenomenon, of 
 which, though fome account of it has been given in the 
 Encyclopaedia (fee Aberration, in aftronomy ; and 
 the article Astronomy, no 337.), one of the moft can- 
 did of our correfpondents requires a fuller explanation. 
 If fuch an explanation be requifite to him, it muft be 
 much more fo to many others; and we know not where 
 to find, or how to devife, one which would be more fa- 
 tisfactory, or more familiar, than the following by Dr 
 Hutton. 
 
 " This effeft (fay ne) may be explained and fami- 
 liarized by the motion of a line parallel to itfelf, much 
 after the manner that the compoUtion and refolution of 
 forces are explained. If light have a progreffive mo- 
 tion, let the proportion of its velocity to that of the 
 fljteU. earth in her orbit be as the line BC to the line AC; 
 "g- '• then, by the compofition of thefe two motions, the par- 
 ticle of light will feem to deferibe the line B A or DC, 
 *^ SuppL. Voi,. I. Part I. 
 
 Ahfcif^. 
 
 A B S 
 
 inftead of its real courfe BC ; and will appear in the Aterratian 
 direftion AB or CD, iflftead of its true direftion CB. 
 So that if AB reprefent a tube, carried with a parallel 
 motion by an obferve r along the line AC, in the time 
 that a particle of light would move over the fpace BC, 
 the different places of the tube being AB, ab, cd, CD; 
 and when the eye, or end of the tube, is at A, let a 
 particle of light enter the other end at B ; then when 
 the tube is at ab, the particle of light will be at e ex- 
 aftly in the axis of the tube ; and when the tube Is at 
 cd, the particle of light will arrive at/, ftill In the axis 
 of the tube; and, laftly, when the tube arrives at CD, 
 the particle of light will arrive at the eye or point C, 
 and confequently will appear to come in the dlreiftlon 
 DC of the tube, inftea ' the true direftlon BC : and 
 fo on, one particle fuc -.ding another, and formliig a 
 continued ftream or ray of light in the apparent direc- 
 tion DC. So that the apparent angle made by the ray 
 of light with the line AE Is the angle DCE, inftead 
 of the true angle BCE ; and the difference BCD, or 
 ABC, Is the quantity of the aberration." 
 
 Abehration of the Planets, Is equal to their geocen- 
 tric motion, or, in other words, to the fpace which each 
 appears to move as feen from the earth, during the 
 time that light employs In paffing from the planet to 
 the eye of tlif obferver. Thus the fun's aberration in 
 longitude Is conftantly 20", that being the fpace aftu- 
 ally moved by the earth, but apparently by the fun in 
 8 minutes and 7 feconds, the time In which light paffes 
 from the fun to the earth. If then the diftance of any 
 planet from the earth be known, the time which light 
 employs in paffing from the planet to the earth mud 
 likewife be known ; for as the dlllance of the fun is to 
 the diftance of the planet, fo is 8 minutes and 7 feconds 
 to that time; and the planet's geocentric motion in that 
 time Is Its aberration, whether It be in longitude, lati- 
 tude, right afcenfion, or declination. See Astrono- 
 my in this Supp'ement. 
 
 ABOAB, ceffes levied. In India, under different de- 
 nominations, beyond the ilandard rent. 
 
 ABSCISS, Adscisse, or Abfdjfa, is a part cutoff 
 from a ftraight line, and terminated at fome certain 
 point by an ordinate to a curve ; as AP (tig. 2.), or 
 BP (fig- 3-) The abfclfs may commence either at the 
 vertex of the curve, or at any other fixed point ; and 
 it may be taken either upon the axis or upon the dia- 
 A meter 
 
 Plate 14^
 
 A B S 
 
 [ 2 1 
 
 ACT 
 
 Abforptinn, meter of tlie curve, or upon any oilier line diawn in a 
 Abfurdmn giyg,, pofition. Hence there are on the fame given line 
 ' or tliametcv an infinite number of variable abfcifies, ter- 
 
 minated all at one end by the fame fixed point. In 
 the common parabola (fig. 4.), each ordinate PQ^has 
 bnt one abfcifs AP. In the ellipfe or circle (fig. 2.), 
 the ordinate has two abfciiTes lying on the oppofite 
 fides of it. In general, to each ordinate a line of the 
 fecond kind, or a curve of the firll kind, may have two 
 abfciffes; a line of the third order, three; a line of the 
 fourth order, four; and fo on. 
 
 ABSORPTION, in Anatomy and Physiology, 
 has been tnirici'^jiuly explained nnder thefe articles in the 
 lincyclopadla ; bnt there is another abforbing power 
 poffefled by different fubllances, which is worthy of at- 
 tention, becaufc it is only by our knowledge of it that 
 we can adapt our clothing to the various climates of the 
 earth. The power to which we allude is that of diffe- 
 rent fubllances ; fuch as wool, cotton, filk, and linen, 
 to abforb or attraft moifture from the atmofphere. On 
 this fubjeft the reader will find fome very inllruftive ex- 
 periments detailed (in Encycl. ), where perhaps he may 
 not have looked for them, under the title Flanel. 
 
 ABSURDUM, a term made ufe of by mathemati- 
 cians when they dtmoiiftrate any truth, by fliowing 
 that its contrary is impofllble, or involves an abfurdity. 
 Thus Euclid dcmonllrates the truth of the fourth pro- 
 pofition of the firft book of his Elements, by fhowing 
 that its contrary implies this obvious abfurdity — " that 
 two llraight lines may inclofe a fpace." 
 
 This mode of demonftration is called rsduB'w ad at- 
 fttrdum, and is every whit as conclufive as the direft 
 method; becaufe the contrary of every falfehood muft 
 be truth, and of every truth, falfehood. 
 
 The young geometrician, however, does not, we be- 
 lieve, feel himfclf fo perfeiSly fatisfied with a demon- 
 llration of this kind, as with thofe which, proceeding 
 from a few felfevident truths, conduits him direftly, 
 by necefiary confequences, to the truth of the propofi- 
 tion to be proved. The reafon is, that he has not yet 
 learned to dillinguilh accurately between the words 
 falfe zr\A Impofflili , different 2tw\ contrary, 'hldiny diffe- 
 rent affertions may be made relating to the fame thing, 
 and -yet be all true or all falfe ; but it is impoffible to 
 make two afiertions diieiSlly contrary to each other, of 
 which' the one fhall not be true and the other falfe. 
 Thus, " fnow is white," " fnow is cold," are different 
 affertions relating to the fame thing, and both true; as, 
 •' fnow is black," " fnow is red," are both falfe : but 
 let it be remembered, that of the firll and fecond, and 
 of the third and fourth of thefe affertions, neither is di- 
 rettly contrary to the other ; nor is any one of them, 
 abftraftly confidered, ImpoJJlble, or fueh as a blind man, 
 who had never felt nor heard of fnow, might not believe 
 upon ordinary teilimony. But were all the men in 
 Europe to tell a native of the interior parts of Africa 
 that fnow is a thing at once nx'hite and not white, cold and 
 not cold, the woolly-headed favage would know as well 
 as the moll fagacious philofopher, that of thefe contrary 
 affertions the one mujl be true and the other muft he falfe. 
 Jull fu it is with relpeft to Euclid's fourth propofition. 
 Had he proved its truth by (howing that its contrary 
 involves this piopofition, that " the diagonal of a fquare 
 is commenfurate with its fide," the fliilful geometrician 
 would indeed have admitted the demonilration, becaufe 
 
 Adion. 
 
 he knows well that the diagonal of a fquare is not com- Accelerate 
 menfurate with its fide ; but the tyro in geometry 
 would have been no wifer than before. He knew from 
 the beginning, that the propofition and its contrary 
 cannot both be true ; but which of them is true, and 
 whicli falfe, fuch a demonftration could not have taught 
 him, becaufe he is ignorant of the incommenfurahility 
 cf the diagonal and fide of a fquare. No man, how- 
 ever, is ignorant, tliat two llraight lines cannot inclofe 
 a fpace ; and fince Euclid (hows that the contrary of 
 his propofition implies this abfurdity, no man of com- 
 mon fenfe can entertain a doubt but that the propofi- 
 tion itfelf mull be true. 
 
 ACCELERATED motios.1 See(Encycl.) Ac- 
 ACCELERATING force, j cELERAnoN; and 
 Mechanics, Seit. VI. — and (this Supplement) Dy- 
 namics. 
 
 ACTION is a term which has been fufficiently ex- 
 plained in the Encyclopaedia; but fince that article was 
 written, queftions have been agitated refpeftiiig agents, 
 agency, and aBion, which, as tliey have employed fome 
 of t^ie moll eminent philofopher^ of the age, and are 
 connedled with the deareft interefts of man, are cer- 
 tainly entitled to notice in this place. 
 
 It is the opinion of Dr Reid, and we have adopted 
 it (fee Metaphysics, n° 109, &c. Encycl.), that no 
 being can be an agent, or perform an aSion, in the pro- 
 per fenfe of the v.'ord, which does not poffefs, in fome 
 degree, the powers of will and underftanding. If this 
 opinion be jull, it is obvious, that what are called the 
 powers of nature, iuch as impulfe, attraSion, rcJ>ii//ion, 
 elajlicity, &c. are not, ftridlly fpeaking, ^t/wfrj or caufes, 
 but the effedls of the agency of fome aftive and intel- 
 ligent being ; and that phyjical caufcs, to make ufe of 
 common language, are nothing more than laius or rules, 
 according to which thc^fffn/ produces the effcft. 
 
 This doflrine has been controverted by a writer 
 whofe acutenefs is equalled only by his virtues ; and. 
 we fliall confider fome of his objeflions to it in another 
 place (fee Cause) : but a queftion of a different kind 
 tails under our prefent confideration ; and perhaps the 
 anfwer which we muil give to it, may go far to remove 
 the objeftions to which we allude. 
 
 Can an agent operate where, either by itfelf or by 
 an inftrument, it is not prefent ? We think not ; be- 
 caufe agency, or the exertion of power, muft be the 
 agency of fomething. The conftitution of the human 
 mind compels us to attribute every adtion to fome be- 
 ing; but if a being could aft in one place from which it 
 is abfent, it might do the hune in a fecond, in a third, 
 and in all places; and thus we (hould have aftion with- 
 out an agent : for to be abfent from all places is a phrafe 
 of the fame import as not to exift But if a living and 
 intelligent being cannot adl but where it is either im- 
 mediately or inllrumentally prefent, much lefs furely can 
 we attribute events of any kind to the agency of an ab- 
 fent and inanimated body. Yet it has been faid, that 
 " we have every reafon, which the nature of the lui;|e£l 
 and of our own faculties can admit of, to believe, that 
 there are among things inanimate fuch relations, that 
 they may be mutually caufes or principles of change to 
 one another, without any exertion oi poiver, or any o- 
 peration of an agent, ftriftly fo called. Such relations, 
 for aught that we know, may take place among bodies 
 at great diftances from one another, as well as among 
 
 bodies
 
 ACT 
 
 [ 3 ] 
 
 A E R 
 
 bodies really or ft'cmiiigly in aftual coiit,nv,1 ; and they 
 ' may vary both in degree and in kind, according to t!ic 
 diilances between the bodies." 
 
 That any thiiij ihonld be a caufe or principle of 
 change to another, vvitiiout the exertion of/)owf/-or tlie 
 operation of an aoent, appears to us a palpable contra- 
 diclion ; and we could as eafily conceive any two fides 
 of a trianc'c to be not fjreater than the third (iJe, as re- 
 concile fuch a pvopolition lc> tliat faculty of our minds 
 by which we diiUnirniih truth from falfehood. When 
 we fee one body the apparent caufe of change in ano- 
 ther body, we cannot poiTibly entertain a doubt of the 
 exerilon of poiacr; but whether that power be in the 
 body apparently producing the change, or in a diftinft 
 agent, is a qucllion to which an anfwer will not fo 
 readily be found. Tliat it is in a diftiuft agent, we are 
 ftrongly inclined to believe, not only by the received 
 doftrine concerning the Inertiaof matter, which, though 
 it has been frequently controverted, we have never feen 
 difproved, but much more by cont'idering the import 
 of an obfervation frequently introduced to prove the 
 diredl contrary of our belief. " We cannot be charged 
 (fays the writer whom we have jull quoted) with 
 maintaining the abfurdity, that there may be an effedl 
 without a caufe, when we refer the fall of a ftone to 
 the ground, and the ebbing and flowing of the fea, to 
 the injiuence of the earth on the rtone, and of the fun 
 and moon on the ocean, according to the principle of 
 general gravitation." 
 
 We admit the truth of this obfervation, provided the 
 influence of the fun and moon on tiie ocean be poffible; 
 but, to us at leaft, it appears impoffible, and is certain- 
 ly inconceiveable. The influence of the fun and moon 
 can here mean nothing but the aS'mn or operation of the 
 fun and moon; but if thefe two bodies be inanimate, 
 they cannot a£l at all, in the proper fenfe of the word ; 
 and whatever they be, it is obvious that they cannot 
 acl immitUalcly on an objetl at fuch a diitance from them 
 as the earth and the ocean. L' they be the agents, they 
 muft operate by an inllrument, as we do when moving 
 obiefts to which our hands cannot reach ; but as it has 
 been fliewn elfewhere (lee Metaphysics, n° 199. and 
 Optics, n" 6?. Encycl.), that neither air nor a;ther, 
 nor any other material inllrument which has yet been 
 thought of, is fufficient to account for the phenomena 
 of attraftion and repulfion, it is furely much more ra- 
 tional to conclude, that the ebbing and flowing of the 
 fea are produced, not by the influence of the, fun and 
 moon, but by the power of fome dillindl agent or 
 agents. 
 
 What thofe agents are, we pretend not to fay. If 
 the Supreme Being himfelf be the immediate author of 
 every change which takes place in the corporeal world, 
 it is obvious that he acls by fi.Ked rules, of which many 
 are apparent to the moft heedlefs obferver, whilft the 
 difcovery of others is referved for the reward oftheju- 
 dicious application of the faculties which he has given 
 us. If he employs inferior agents to carry on the great 
 operations of nature, it is fnrely not difficult to con- 
 ceive that the powers of thofe agents which were de- 
 rived from him, may by him be rellrained within cer- 
 tain limits, and their exercife regulated by determined 
 laws, in fuch a manner as to make them produce the 
 greatell benefit to the whole creation. Nor let it be 
 thought an objeftion to this theory, that the changes 
 
 which take place among bodies at great diftanccs from Adli.-.n 
 each other, vary botii in degree and in kind accordino- II 
 to the diilances; tor this variation, which weackiiow- i' ^"''"^y', 
 ledge to be a taft, appears to us wholly unaccountable 
 upon any other hypothefis than that which attributes 
 the difTtrent changes to agents diflinft from the bodies 
 themfelves. Did we perceive all the particles of mat- 
 ter, at all difiances, tending towards each other by u 
 fixed law, we might be led to confider mutual attrac- 
 tion as an eJfent'nU property of that fubllance, and think 
 no more ot inquiring into its caufe, than we think of 
 inquiring into the caufe of cxtenfion. But when we 
 find that the fame particles, which at one dillance fccm 
 to attrac^l each other, are at a different dillance kept 
 afuiider by a power of repulfion, which no force, with 
 which we are acquainted, is able to overcome, we can- 
 not attribute the principle or ctuife of thefe changes to 
 brute matter, but mull refer it to fome other agent 
 exerting power according to a fixed law. 
 
 It is '-lie fafiiion at prefcnt to defpife all metaphyfi- 
 cal inquiries as abftrufe and nfelefs: and on this account 
 we doiibt not but fome of our readers will turn away 
 from this difquifition with afFedled difguft, vvhilll the 
 petulant and unthinking chemift, proud of poflefling the 
 feerets of his fcience, will deem it fuperfluous to inquire 
 after any other natural agents than thofe of which he 
 has been accullomed to talk. But with the utmolt re- 
 fpeft for the difcoveries made by modern chemifts, 
 which we acknowledge to be both numerous and im- 
 portant, we beg leave to obferve, that though thefe 
 gentlemen have brought to light many events and ope- 
 rations of nature formerly unknown, and have fiiown 
 that thofe operations are carried on by efl;abli(hed laws, 
 none of them can fay with certainty that he has difco- 
 vered a fingle agent. The moft enlightened of them 
 indeed pretend not to have difcovered in one depart- \ 
 
 ment of fcience more than Newton difcovered in ano- 
 ther ; for they well know that agents and agency can- 
 not be fubjeifted to any kind of phyfical experiments. 
 Our very notions of thefe things are derived wholly 
 from our own confcioufiiefs and re'fleftion ; and when 
 it is confidercd what dreadful confequcnces have in an- 
 other country refulted from that pretended philcfophy 
 which excludes the agency of mind from the univerfe, 
 it is furely time to iriquire whether our confcioufnefs 
 and refleftion do not lead us to refer re.il agency to 
 mind alone. Let this be our apology both to the real 
 and to the afi"ei£led enemies of metaphyfics for endea- 
 vouring to draw their attention to the prefent queftion. 
 It is a queftion of the utmoft importance, as well to 
 fcience as to religion : and if the laws of human thought 
 decide it, as we have endeavoured to (how that they do, 
 -we may without liefitation affirm, that the impious phi- 
 lofophy of France can never gain ground but among 
 men incapable of patient thinking. 
 
 ADAMAS, a name given, in aftrology, to the 
 moon. 
 
 jEOLUS, in mechanics, a fmall machine invented 
 by Mr Tidd for refrefliing or changing the air in rooms 
 when it becomes too hot or otherwife unfit for refpira- 
 tion. The aeolus is fo contrived as to fupply the place 
 of a fquare of glafs in the window, where it works, 
 with very little noife, like the fails of a wind-mill or a 
 fmoke-jack. 
 
 AEROLOGY is a branch of fcience which was de- 
 A 2 detailed
 
 A F G [4 
 
 Afghans tailed in the Encyclopedia at fiifScient length, and ac- 
 '~'^'™"" cordinjr to the prlnciplis which were then generally ad- 
 mitted by cheitiilh. .Subl'equent experiments, however, 
 liave flioivn, that iome ot thole principles are erroneous, 
 and of coiirie tiiat Iome of the opinions advanced in the 
 article Aerology are inconfiftent with fafts. Thefe 
 opinions mud be corrected ; but inllead of fwelling this 
 volume with a new article Aerology, we apprehend 
 that it will be more acceptable to our fcientific readers 
 to refer them for thofc corredlions to the article Chr- 
 MISTRV in this Supplement. 
 
 AFGHANS, are a people in India who inhabit a 
 province of Cabu u or Cabulistan (fee Encycl.), and 
 have always been conncfteJ with the kingdoms ot Per- 
 fia and HJndoftan. They boaft of being defcended of 
 Saul the firlt king of Ifrael ; of whofe advancement to 
 the royal dijjnity they give an account which deviates 
 not very widely from the truth. Tliey fay indeed, that 
 their great anccftor was raifed from the rank of a fhep- 
 htrd, not for any princely qualities which he poffeffed, 
 but becaufe his llature was cxadlly equal to the length 
 of a rod which the angel Gabriel had given to the pro- 
 phet Samuel as the nieafure of the ftature of him whom 
 God had deftined to fill the throne of Ifrael. 
 
 Saul, whofe dtlcent, according to fome of them, 
 was of Judah, and according to olheisof Benjamin, 
 had, they fay, two fons, BtRKiAand Irmia, who fer- 
 ■ved David, and was belovjd by hlmi. The fons of 
 Berkia and Irmia were Afghan and Usbec, who, 
 Curing the reigns of David and Solomon, diftinguifhed 
 thimfelves, the one for his corporeal ftrength, and the 
 ether fur liis learning. So great indeed was the ftrength 
 of Afghan, that we are told it flruck terror even into 
 demons and genii. 
 
 This hero ufed frequently to make excurfions to the 
 mountains, where his progeny, after his death, eflablifh- 
 ed themfelves, lived in a ftate of independence, built 
 forts, and exterminated infidels. When the fele£t of 
 creatures (the appellation which this people give to 
 Mahomet) appeared upon earth, his fame reached the 
 Jlfghans, who fought him in multitudes under their 
 leaders Kbalid and Aldul Refpid, fons of JValid ; and 
 the prophet honouring them with this reception — 
 " Come, O Muluc, or Kings !" they affumed the title 
 of Melic, whii h they retain to this day. 
 
 The hiftory, from which this abftraft is taken, gives 
 a long and unintertfting detail of the exploits of the 
 Afghans, and of their zeal in overthrowing the temples 
 of idols. It boafts of the following monarchs of their 
 T3ce who have fat upon the throne of Debli : Sultan 
 ' JiEHLOLE, Afghan LoDi, Suhan S'-candfr, Sultan 
 
 Irbabim, Shir Shah, Ielaf^ Shah, Adil Shah 
 SuR.. It alfo numbers the following kings of Gaur 
 defccndedof the Afghan chiefs : SoLAIM/^N Shah Gur- 
 zanif Beyazid Shak, and Kutb Shah ; befides whom, 
 their nation, we are told, has produced many conquerors 
 of provinces. The Afghans are fometimes called Solai- 
 mani, either becaufe they were formerly the fubjefts of 
 Solomon king of Ifrael, or becaufe they inhabit the 
 mountains of Solomon. They are llkewife called Pa 
 TANS, a name derived from the BinJi verb Pailna " to 
 ruih," which was given to them by one of the Sultans 
 whom they ferved, in confequence of the alacrity with 
 which they had attacked and conquered his enemies. 
 The province which, they occupy at prefent was for. 
 
 ] A F G I 
 
 merly called Roh ; and hence is derived the name of the Afghani 
 
 Rohdias. The city which was eflablifhed in it by the *""" 
 
 Afghans was called by them Pufhiver or Pa'fher, and 
 is now the name of the v\ hole diltritt. The feds of the 
 Afghans are very numerous ; of which the principal 
 are, Liodi, Lnhouni, Sur, Sertvatii, Tufufxihi, Bang'i/b, 
 Di/axaui, Kheit'i, Yafin, Kail, and Belnjt. They are 
 MuJ'ulmans, partly ot the Sunni, and partly of the Shiii 
 perfuafion. 
 
 Though they are great boafters, as we have feen, of 
 the antiquity of their origin, and the reputation of their 
 race, other Mufidmans rcjeft their claim, and confider 
 them as of modern, and even of bafe, extraftion. 
 
 This is probably a calumny ; for it feems inconfiftent 
 ■with their attention to the purity of their dcfcent — an 
 attention which would hardly be paid by a people not 
 convinced of their own antiquity. They are divided 
 into four chifles. The firft is \.he pure cLifs, confifting 
 of thofe whofe fathers and mothers were Afghans. The 
 ftcond clafs confifts of thofe whofe fathers were Afghans 
 and mothers of another nation. The third clafs contains 
 thofe whofe mothers v/ere Afghans and fathers of ano- 
 ther nation. The fourth clafs is compofed of the chil- 
 dren of women whofe mothers were Afghans and fathers 
 and hufbands of a different nation. Perfons who do not 
 belong to one of thelc clafTes are not called Afghans. 
 
 This people have at all times dllb"ngul/hed themfclvei 
 by their courage, both fmgly and unitedly, as princi- 
 pals and auxiliaries. They have conquered for their 
 own princes and for foreigners, and have always beea 
 confidered as the main ftrength of the army in which 
 they ferved. As they have been applauded tor virtues, 
 they have alfo been reproached for vices, having fome- 
 times been guilty of treachery, and of adtiiig the bafe 
 part even ot afftiffius. 
 
 Such is the account of the Afghans publiflicd in the 
 fecond volume of the A fiatic Kefearches. It was tranf- 
 lated from a Pcrlian abridgment of a book written in 
 the Pulhto language, and called The Secrets of the Af~ 
 ghans, and communicated by Henry Vanfittart, Efq; to 
 Sir William Jones, then prefident of the Aliatic So- 
 ciety. Their claim to a defcent from Saul king of li- 
 rael, whom they call Melic Talut, is probably of not 
 a very ancient date ; for the introduftion of the angel 
 Gabriel with his rod, gives to the whole ftory the air 
 of one of thofe many fictions which Mahomet borrowed 
 from the later rabbins. Sir William Jones, however, 
 though he furely gave no credit to this fable, feems to 
 have had no doubt but the Afghans are defcendants of 
 Ifrael. " We learn (fays he) from Esdras, that the 
 ten tribes, after a wandering journey, came to a coun- 
 try called Arfarelh, where we may fuppofe they fet- 
 tled : now the Afghans are faid by the beft Perfian hif- 
 torians to be defcended from the Jems. They hava 
 traditions among themfelves of fuch a defcent ; and it 
 is even afferted, that their families are diftinguifhed by 
 the names of Jeiuj/b tribes, although fince their con- 
 verfion to JJlam, they ftudioufly conceal their origin 
 from all whom they admit not to then fecrets. Tha 
 Pufhio language, of which I have feen a didionary, has 
 a manifell refemblance to the Chaldakk; and a confi- 
 derable dillrift under their dominion is called Ha-i,areth 
 or Haaaret, which might cafdy have been changed into 
 the word ufed by Esdras. 1 ftrongly recommend an 
 inquiry into the literature and hiftory of the Afghans." 
 
 It
 
 Llbategnl 
 II 
 
 A L M [ 
 
 It is to co-operate with this accomplidied fcholar 
 tliat we have iiilertcd into our Worli this fhort account 
 ■(jf that fingular people ; and it is with pleafure that, 
 upon the authority of Mr Vimfittart, we can add, that 
 a very particular account of the Afghans has been writ- 
 ten by the late Hafiz Rahmat Khan, a chief of the 
 Rohillahs, from which fuch of our readers as are orien- 
 tal fcliolars may derive much curious information. 
 
 ALBATEGNI, an Arabic prince of Batan in Me- 
 fopotamia, was a celebrated aflronomer, about the year 
 ofChrilf S8o, as appears by his obfctvations. He is 
 alio called Miihumnui! ben Geier yllbalam, Mahomet the 
 Jon of Geber, and Muhamedes Arailttifis. He made af- 
 tronomical obfervations at Antioch, and at Racah or 
 Arafta, a town of Chaldea, which fonie authors call a 
 town of Syria or of Mefopotamia. He is highly fpo- 
 ken of by Dr Halley, as ilr aJmirandi acumiiiis, ac in 
 admin'tflrand'u olfervnlionilus cxeratai'ijfimus. 
 
 Finding that the tables of Ptolemy were imperfedt, 
 he computed new ones, which were long ufed as the 
 beft among the Arabs : thefe were adapted to the me- 
 ridian of Aradla or Racah. Albategni compofed in 
 Arabic a work under the title of The Science of the 
 Stars, comprifing all parts of aftronomy, according to 
 Lis own oblervations and thofe of Plolemy. This work, 
 tranflated into I^atin by Plato of Tibur, was publifhtd 
 at Nuremberg in 1537, with fome additions and de- 
 monllrations of Regiomontanus ; and the fame was re- 
 printed at Bologna in 1645, with this author's notes. 
 Dr Halley delefted many faults in thefe editions. — 
 Phi/. Tranf. for 1693, N''204. 
 
 In this work Albategni gives the motion of the fun's 
 apogee fince Ptolemy's time, as well as the motion of 
 the ftars, which he makes one degree in 70 years. Pie 
 made the hingitude of the full ftar of Aries to be j8° 
 2' ; and the obliquity of the ecliptic 23° 35'. hnA up- 
 on Albatcgni's obfervations were founded the Aiphon- 
 fine tables ot the moon's motions ; as is obfervcd by 
 Nic. Muler, in the Tab. Frijicie, p. 248. 
 
 ALDERAIMIN, a ftar of the third magnitude, in 
 the right flioulder of the conftcllation Cepheus. 
 
 ALFRAGAN, Alfergani, or Fnrgani, a cele- 
 lirated Arabic aflronomer,who flourifned about the year 
 800. He was fo called from the place of his nativity, 
 Fergan, in Sogdiana, now called Maracanda, or Samar- 
 cand, anciently a part of Badf ria. He is alfo called 
 Ahmed (or Muhciiuncd) lenCothair, or Kalir, He 
 wrote the Elements of Aftronomy in %o chapters or 
 feftions. In this work the author chiefly follows Pto- 
 kmy, ufing the fame hypolhefrs, and the fame terms, 
 and frequently tiling him. Of Alfragan's work there 
 are three Latin tranflations, of which the laft and beft 
 was made by GoHue, proftfTor of mathematics and 
 oriental languages in the univerfity of Leyden. This 
 tranfiation, which was publifhed in 1669, after the 
 death of Golius, is accompanied with liic Arabic text, 
 and with many learned notes on the firft nine chapters, 
 which wonld undoubtedly have been carried to the end, 
 had the tranflator lived to complete his plan. 
 
 ALGORAB, a fixed ftar of the third magnitude, 
 in the right wing of the conftcllation Corvus. 
 
 ALHAZEN, an Arabian aftronomer, who flourifti- 
 ed in Spain about the begiiming of the 12th century. 
 See .''1 STKONOM Y, n*'-' 6. Encycl. 
 
 ALMAMONi was a philofopher and aflronomer, 
 
 5 ] A L O 
 
 who, in the beginning of the 9th century, afcended the Alnramon, 
 throne of the caliphs of Bagdat. He was the fon of -Alnc- 
 Harun Al-Ra(hid, and grandfon of Almaiifor. His *■ 
 name is otherwife written Mamon, Almaon, Umamun, 
 Alamoun, or Al-Maimon. Having been educated with 
 great care, and with a love for the liberal fciences, he 
 applied himfelf to cultivate and encourage them in his 
 own country. For this purpofe he rcquefted the Greek 
 emperors to fupply him with fuch books on phllofophy 
 as they had among them ; and he coUefted fltilful inter- 
 preters to tranflate them into trhe Arabic language. 
 He alfo encouraged his fubjefts to ftudy thein ; fre- 
 quenting the meetings of the learned, and afilfting at 
 their exercifes and deliberations. He caufed Ptolemy's 
 Almagcft to be tranflated in 827, by Ifaac Ben-honain, 
 and Thabet Ben-korah, according to Herbtlot, hut, ac- 
 cording to others, by Scrgiuf, and Alhazen the fon of 
 Jofeph. In his reign, and doubtlefs by his encourage- 
 ment, an aftronomer of Bagdat, named Habafti, com- 
 pofed three fets of aftronomical tables. 
 
 Alniamon himfelf made many aftronomical obferva- 
 tions, and determined the obliquity of the ecliptic to 
 be then 23° 35' (or 23^33' in fome manufcripts), but 
 Voflius fays 23° 5 1' or 23° 34'. He alfo caufed fl<ilful 
 obfervers to procure proper inftruments to be made, 
 and to cxercife themfelves in aftronomical obfervations; 
 which they did accordingly at S*hemafi in the province 
 ot Bagdat, and upon Mount Cafuis near Damus. 
 
 Under the aufpices of Almamon alfo a degree of the 
 meridian was meafured on the plains of Sinjar or Sind- 
 giar (or, according to fome, Flngar), upon the borders- 
 of the Red Sea ; by which the degree was found to 
 contain 56^ miles, of 4000 coudees each, the coudee 
 being a foot and a half : but it is not known what foot 
 is here meant, whether the Roman, the Alexandrian, or 
 fome other. Riccioli makes this meafure of the degree 
 amount to 81 ancient Roman miles, which, value an- 
 fwers to 62,046 French tolfes ; a quantity more than 
 the true value of the degree by almoft one-third. Fi- 
 nally, Almamon revived the fciences in the Eaft to fuch 
 a degree, that many learned men were found, not onlv 
 in his own time, but after him, in a country where the 
 ftudy of the fciences had been long forgotten. This 
 learned king died near Tarfus in Cilicla, by having 
 eaten too freely of fome dates, on his return from a mi- 
 litary expedition, in the year 8^3. 
 
 ALOE uiCHoroMA, in botany, called by the Dutch 
 Kooler-boom or ^iver Iree, is a native of the foutheru 
 parts of Afiica, and feems to be a fpecies of the Aga- 
 ve or American aloe (lee Agave, Encycl.) It ia thus 
 d.'fciibed by Le Vaillant in his Neiu Travels info 
 the Interior Parts of Africa : " The aloe dichotoma rifcs 
 to the height of 25 or 30 feet ; its trunk is fmooth, 
 and the bark white. When young, and the trunk not 
 more than four or five feet long, it terminates with a. 
 fmgle tuft of leaves, which, like thofe of the ananas, 
 fprtad and form a crown, from the midft of which all 
 its flowers iffue. As it grows older, it puftits out late- 
 ral branches, perfeftly regular and fymmetrical, each of 
 which had at its extremity a crown fimilar to that of 
 tJie young plant. The kooker-boom thrives much bet- 
 ter on mountains than in the plain. Inftead of long 
 roots penetrating deep into the earth, like thofe of other 
 trees, it has but a very flight one by which it is fixed 
 to the foil. Accordingly, three inches of mould are. 
 
 fufEicient.
 
 ALP [6 
 
 A'<-f. fufficiefit to cnalilc it to grow upon the very rocks, and 
 
 A'l'ho'ifus- attain its iitinoll IicDuty ; but" its root is i\> fctble a fiip- 
 
 ' port, that Ifould tluow down the- largcll with a fingle 
 
 kick of my foot. The h.orjes on the wctl make their 
 
 »|uivcrs ot" tlio trunk of this tree when young, whence 
 
 is derived the name given it by the planters." 
 
 It becomes not us, fitting in our chambrr, to contro- 
 vert a faft in natural hlllory, of the reality of which we 
 never had an opportunity of judging ; nor would il be 
 proper, on account of our own fecpticifm, to luppreis 
 the narrative of a traveller, who correfts the narratives 
 of former travellers in terms which nothing (hould have 
 diftatcd but the confcioufncfs of his own invariable ve- 
 racity. Yet we hope to be pardoned for exprefling our 
 furprife that, in any part cf the world, trees fliould be 
 found in great numbers 25 or 30 feet high, and (hoot- 
 ing out many branches, which have yet fo loofe a hold 
 of tlie ground, that the largtil of them may be thrown 
 down by the fingle kick of a man's foot.' The reader's 
 furprife will probably equal our's, when he is informed 
 that the author faw one of thefe trees of which the 
 trunk was ten feet four inche^ in circumference, whilil 
 its blanches cvcrfhadowed a fpace of more than 100 
 feet in diameter ! I'his tree he affures that he could 
 have kicked over. The country, according to his ac- 
 count, is not exempted from (lorms. He is himfclf a 
 French philofopher. What a pity then is it that he did 
 not explain to thofe, who have not had the benefit of 
 being enlightened in that fchool, upon what principle 
 of mechanics or ftatics the tree could refill the violence 
 of the elements till it arrived at fo enormous a fiz.e ? 
 
 ALPHONSUS X. king of Leon and Caftile (fee 
 Encycl.) This prince underftood ailronomy, philolo- 
 phyv and hiltory, as if he liad been only a roan of let- 
 ters ; and compofed books upon the motions of the 
 heavens, and on the hillory of Spain, which are highly 
 commended. "What can be more furprifing (lays 
 Mariana), than that a prince, educated in a camp, and 
 nar.dlliig arms from his childhood, fliould have luch a 
 knowLdge of the ftars, of philofophy, and the tranfac- 
 tions of the world, as men of leiiure can fcarcely ac- 
 quire in their retirements? There are extant fome books 
 of Alphonfus on the motions of the ftars, and the hif- 
 tory of Spain, written with great fl<ill and incredible 
 care." In his'alhonomical purfuits he difcovered that 
 the tables of Ptolemy were iuU of errors ; and thence 
 he conceived the firll of any the refolution of correft- 
 ing them. For this purpofe, about the year 1240, and 
 during the life of his father, he alFembled at Toledo the 
 moll (kilful aftronomers of his time, Chrillians, Moors, 
 and Jews, when a plan was formed for conftrufting new 
 tables. This tallc was accompliflied about 1252, the 
 firft year of his reign; the tables being drawn up chief- 
 ly by the llvill and pains of Rabbi liaac Hazan, a learn- 
 ed Jew, and the work called the Aiphonfim Tables, \a 
 honour of the prince, who was at vaft expences con- 
 cerning them. He fixed the epoch of the tables to 
 the 30th of May 1252, being the day of his acceifion 
 to the throne. They were printed for the firft time 
 in 1483, at Venice, by Radtoldt, who excelled in 
 printing at that time. This edition is extremely rare : 
 there are others of 1492, 1521, 1545, &c. 
 
 In the Encyclopedia it is faid, that the charge of 
 impiety brought againft this prince was unjuj}. This 
 "vas faid too confidently, becaufe we know not of any 
 
 ] ALT 
 
 dirccl proof of hij innocence. All that has been faid 
 for him by Dr Hutton, one of his ablell apologills, 
 amounts to nothing more than a high degree of proba- 
 bility that the charge was carried by much too far. 
 The charge itl'tlf was, that Alphon'.us affirmed, "that 
 it he had been of God's privy-council when he made 
 the world, he would have advifed him better." Ma- 
 riana, li0WL~er, fays only in general, that Alphonfus 
 was lb bold as to blame the works of Providencf, and 
 the conftruiSion of our bodies ; and he fays that this 
 ftory concerning him refted only upon a vulgar tradi- 
 tion. The Jefuit's words are curious: " Emanuel, the 
 uncle of Sanchez (the Ion of Alphonfus), in his own 
 name, and in the name of other nobles, deprived Al- 
 phonfus of his kingdom by a public fentence ; which 
 that prince merited, for daring fcverely and boldly to 
 ccnfure the works of Divine Providence, and the con- 
 ftruftion of the human body, as tradition fays he did. 
 Heaven moll juftly punifhed the folly of his tongue." 
 Though the filence of futh an hiftorian as Mariana, ia 
 regard to Ptolemy's fyflem, ought to be of fome weight, 
 yet we cannot think it improbable, that if Alphonfus 
 did pafs fo bold a cenfure on any part of the univerle, 
 it was on the ccleftial fphere, and meant to glance upon 
 the contrivers and iupporters of that fyftem. For, be- 
 fides that he ftudied nothing more, it is certain that at 
 that time aftronomers explained the motions of the 
 heavens by intricate and confufed hypothefes, which 
 did no honour to God, nor any wife anlwercd the idea 
 of an able workman. So that, from confiderliig the 
 multitude of fphcres compofing the fyllem of Ptolemv. 
 and thofe numerous eccentric cycles and epicycles with 
 which it is embarraffed, it we iuppofe Alphonfus to 
 have faid, " that if God had aiked his advice when he 
 made the world, he would have given him better coun- 
 fel," the boldnefs and impiety of the ceniure will be 
 greatly diminifiied. 
 
 Such is the apology made by Dr Hutton for this 
 royal aftronomer of Spain; and we hope, for the honour 
 of fcience, that it is well founded. Still it leaves Al- 
 phonfus guilty of great irreverence of language, which 
 is to us wholly unaccountable, if it be really true that 
 he read the Bible fourteen times. We have f«n im- 
 piety indeed break out lately from very eminent aftro- 
 nomers of a neighbouring nation ; but thtfe men read 
 not the Bible, nor any thing elfe, but the dreams of 
 the eternal fleepers. 
 
 ALTERNATE angles. See Geometry [En- 
 cycl.], Part I. 35. 
 
 ylL-iKRNATS Ratio, or Proportion.^ is the ratio of.-the 
 one antecedent to tlie other, or of one confcquent to 
 the other, in any proportion, in which the quantities 
 arc of the fame kind. So if A : B : : C : D, 
 
 then alternate!)', or by alternation A : C : : B : D. 
 
 ALTITUDE, Parallax of, is an arch of a ver- 
 tical circle, by which the-true altitude, obferved at the 
 centre of the earth, exceeds that which is obferved ou 
 the furfaqe. See Parallax (Encycl.) and Astro. 
 NOMY (Suppl.) 
 
 AhiituuE of the Nonagefimal, is the altitude of the 
 90th degree of the ecliptic, counted upon it from where 
 it cuts the horizon, or of the middle or higheft point 
 of it which is above,the horizon, at any time ; and is 
 equal to the angle made by the ecliptic and horizon 
 where they interfeft at that time. 
 
 AnnvDK 
 
 Altit J-
 
 ALU [ 7 ] ALU 
 
 Itltui'.e, AiTiTVbR of ihe Cone of the Enrth's or Alnoii's Sha- they ought to produce the fame tfFefts as pure pot-afh A!iim. 
 rilum. (lorjj^ the height of the Hudow of the body made by or ammoniac. He therefore added to a liiirJ portion "~~v— 
 ~"^^~~^the fun, and meafured from the centre of the body, of the folution of fulphat of aluniine bcfcrcmentioned 
 To find it fay, As the tangent of the angle of the fome drops of th.e foliuion of fulpliat of pot-a(h; imme- 
 
 fun's apparent femidiametcr is to radius; fo is i to a diately upo!!«hicli octahedral cvyitalsofahim were form- 
 
 fourth proportional, which will be the height of the . ed. The fulphat of ammoniac prcfented the fame effeft. 
 fliadow in femidiameters of the body. This refult gsve ftiU greater confirmation to his firll 
 
 ALUM is a fait fo ufeful in commerce and the arts, notions, though it did not yet afford a demonftratiou 
 
 that the knowledge of its component parts, and of the perfectly without objeftion; for it might have happen- 
 
 beft method of preparing it, mull be of imponance. In cd that the two Jalts he made ufe of might determine 
 
 the article Chemistry (Encycl.), the opinions which the cryilalli/.ation of the alum, ilmply by abforbing the 
 
 were then held refpeCting its compoi'ition, and the prac- fupei fluous acid, of which they are very greedy ; but 
 
 tice which was generally followed in its preparation, to determine this poffible faft, he mixed in the uncry- 
 
 have been detailed at full length; but fome of thefe Halli/.able folution of alumine fome fulphat of pct-afii 
 
 opinions have fuice been controverted, and if they be with excefs of acid, and obtained a cryftallization no 
 
 erroneous, it muft be expedient to vary in fome degree lels abundant than with the neutral fulpliat of potafli. 
 the mode of preparation. In particular, the opinion This lall experiment leaves therefore no doubt with 
 
 that it is merely an excefs of acid which prevents the regard to the influence and mode of action of pot-afli 
 
 formation of alum by evaporation of the ley, has been and ammoniac in the fabrication of alum ; and thisac- 
 
 {hown to be falfe by Citizen Vauqud'm, who contends, tion is ftill more ftrongly confirmed by the examination 
 
 of courfe, that the addition of putrid urine to the ley of the alums whiclHiave been formed by the prociiTcs 
 
 is a very bad pradlice. above related; for in this manner it is proved that they 
 
 This eminent chemift had long fufpefted, that the contain cor.fiderable quantities of the fulphats of pot- 
 
 cryftallization of alum is not prevented by an excefs afli andtlmmoniac. 
 
 of acid, and that pot-afh is not of ufe fimply to fa- Thefe experiments led M. Vanquelin to an examina- 
 
 turate this acid, but to perform an office of more tion of the different ahims of commerce, of which he 
 
 importance. To bring his fufpfcions to the teft of found not one that did not afford fulphat of pot-afh, 
 
 experiment, he diffolved very pure Alumtne in ful- or of ammoniac, or of both. His methods of analyfis 
 
 phuric acid of equal purity, and evaporated the fo- are very accurate; but to detail them at length would 
 
 lution to drynefs, for the purpofe of expelling the fwell this article to little purpofe. To fuch of our 
 
 fuperabundant acid. He then redilTolved the dry and readers as are not chemifls they would hardly be in- 
 
 jjulverulent refidue in water, and reduced the folution telligible ; and the experienced chemift will devife me- 
 
 to different degrees of fpteific gravity, with a view to thods of analyf:s for himfelf. It may be proper, how- 
 
 Xeize the point mofl favourable to cryftallization ; but ever, to obferve, that M. Vauquelin proved, to his own 
 
 with every pofTible precaution he could obtain nothing fatisfaction, that the fulphat of pot-a(li, or of ammo- 
 
 but a magma (fee Magma), formed of faiine plates, niac, is necefiary to render alum capable of being pre- 
 
 without confiftence or folidity. This foiution, how- cipitated by its earth, or to caufe it to pafs, as it were, 
 
 ever, though itconftantly rcfufed to afford cryffallized to the earthy flate(A). He proved h'kewife, that fuch 
 
 alum alone, afforded it immediately by the addition of aluminous waters as do not contain pot-alb, may re- 
 
 a few drops of the folution of pot-afh ; and as he had main, as long as may be defired, on their materials, 
 
 employed thefe two fubffances in the requifite proper- without being fatnrated with too great a quantity of 
 
 tion, the reft of the folution, to the very end, afforded earth, or futl'ering alum to precipitate. 
 pure alum, without any mixture of fulphat of pot- From the whole of his experiments our author drew 
 
 art). the following conclufions, which he conlidcrs as of im- 
 
 Into another portion of the fame folution of pure portancc to the arts, to chemiftry, and to natural hi- 
 
 alumine, he dropped the fame quantity of carbonat of ftory. 
 
 foda as he had added of that of pot-afh to the former; i. It is not, at lead in the greatetl number of cir- 
 but no cryftallization was formed, even by the help of cuniflanees, the excefs of acid which iniptdes the cry- 
 evaporation, nor did lime and barytes poduce any bet- ftallization of alum, but it is the want of pot-afh oi- 
 ler effefl. But if the common opinion that pot-a(h, in ammoniac : For it is difficult to imagine that the ful- 
 the formation of alum, is of ufe only to abflraft the phuric acid could remain difengaged after fo long re- 
 e»cefs of acid, be true, foda, lime, barytep, and all the malning upon alumine in a flate of extreme diviiion, 
 fubflances which by a more powerful force would take and always fuperabundant. It is true that the alumi- 
 this acid from alum, ought to give the fame refult. nous waters redden the vegetable tin&ures ; but this 
 Another argument prefented itfclf, which feemcd de- property is not owing to a dilengaged acid. I'his por- 
 cifive : If the alkalies, pot-afh, and ammoniac, do no- tion of acid is a conftituent part of thefe waters ; and 
 thing more than unite to the fuperabundant acid of the it appears to have more affinity with the neutral ful- 
 alum, the fulphats of pot-afh and of airmioniac ought phat of alumine than with a new quantity of this earth 
 not to occafion any change in pure alum in its acidula- at the temperature of the atmofphere. 
 ted flate; whereas if thefe alkalies enter as a conftituent 2. The fulphat of pot-afh may be ufed, as well as 
 part into the alum, and are neceffary to its exiflence, pure pot-afh, to caufe the cryftallization of alum. It 
 
 even . 
 
 (a) It may be proper to notice, that Scheele feems to have known this long before, and that he mentioBs it 
 «xprefsly in his paper on Pyrophorus.
 
 ALU 
 
 [ 8 ] 
 
 A'lim, even hns tlia advantage over the latter fait, becaule if 
 ""''v— — the aluminous waters do not really contai . a dileiigagcd 
 acid, the potafli, in its combination, will precipitate a 
 portion of alumine, and dimlnilli the produd of the 
 boiling ; whereas the fulphat of pot-afti does not pro- 
 duce the fame effeil ; but if the lixivinms contain dif- 
 engaged acid, which muft very fcldoni be the cafe, it is 
 not converted into ahim by the fulphnt of pot-alh, and 
 is loit with regard to the prodiiA. Our author there 
 fore is of opinion, that when the watt-rs really contain 
 an excefs of acid, or a very oxided fulphat of iron, the 
 ufe of pot-alh is preferable to that of the fulphat of 
 pot-adt. But when economy is an obje£l, that in ma- 
 ny places it would be profitable to ufe the fulphat of 
 pot-afli ; becaufe it is a lalt indiredly produced in 
 many manufaftories, where of courfe it may be ob- 
 tained for nothing. In particular, the refidues of the 
 dilliUation of aquafortis by the fulphuric acid would 
 be excellent for this operation, and much preferable to 
 putrid urine, becaufe this fluid always contains phof- 
 phoric falls, which decompofe a portion of the lulphat 
 of alumine, and confiderably diminilh the produft. 
 
 3. Alumine cannot be ufed in the treatment of mo- 
 ther waters, as Bergman propofes. This earth is in- 
 capable of favouring the cryftallization of alum, be- 
 fides which, it decoinpofes a portion of alum by the 
 afTiftance of ebullition ; in which circumftance it feizes 
 the acid neceffary to its folution, and precipitates it in 
 the form of that powder which is called alum Satura- 
 ted with its earth. 
 
 4. Many alum ores muft naturally contain pot-afh, 
 becaufe perfeft alum is often obtained from the firft 
 cryftallization of new alum waters without the addi- 
 tion of this alkali. It is true that an objeftion may be 
 made with regard to the wood ufed in calcining thefe 
 ores, which may be fuppofed to have furnilhed the al- 
 kali ; but it is not probable that the fmall quantity of 
 wood employed, in comparifon to the quantity of ore 
 and the alum it affords, could fupply enough of pot- 
 alb for the cryftallization. 
 
 C. All the earths and ftones which have given, or 
 {hall hereafter afford, by analyfis with the fulphuric 
 acid, perfeft alum without addition of pot-afh, muft 
 contain this alkali naturally. For it is well proved, that 
 alum cannot exift without pot-alh or ammoniac; and as 
 there is little probability that this laft fhould be found 
 combined in earths or ftones, unlefs perhaps in very rare 
 cafes, we may almoft conftaiitly be affured, when alum 
 is obtained from any of thefe fubftances, that its for- 
 mation was eft'cfted by pot-alh. The quantity of alum 
 will immediately (bow in what proportion this alkali 
 txifted in the fubftances analyfed. 
 
 6. The alum of commerce ought not to be confider- 
 ed as a fimple fait, but as a combination in the ftate 
 of a triple and fometimes quadruple fait of fulphat of 
 alumine, fulphat of pot-afli, or of ammoniac. Among 
 thefe laft we may diftinguifh two fpecies ; the one 
 without excefs of acid, infoluble in water and infipid, 
 being what is improperly called alum faturated with its 
 own earth; and the other, which contains an excefs of 
 acid foluble in water, very fapid and aftringent, is the 
 common alum. 
 
 There is likewife a pure fulphat of alumine, very 
 aftringent, very difficult of cryftallization, in the form 
 ef brilliant pearl-coloured plate? without conliftence, 
 
 AMI 
 
 and which cannot be rendered infuluble by the addition Alum 
 of a new quantity of its bafe. This laft (alt may with " , 
 
 the greateft propriety be called the fulphat of alumine. ^ , 
 
 7. It follows from the comparative analyfis, and the 
 knowledge acquired refpefting the different ftates of 
 the con.bination of alumine with the fulphuric acid 
 united at the fame time with other bafes, that we muft 
 diftingniih feven ftates in this combination, and tlut it 
 is neceffary to exprefs them according to the rules of 
 the methodical nomenclature. Here follow the Icries, 
 the nature, and the names of thefe feven fulphats of 
 alumine. 
 
 I. Sulphat of alumine, or the artificial combination 
 of fulphuric acid and alumine. This fait is aftringent; 
 it cryilallizes in laminae or flexible leaves, foluble in wa- 
 ter. It has never been dclcribed nor named by che- 
 mifts. 2. Acid fulphat of alumine is the foregoing 
 fait, with excefs of acid, from which it differs by red- 
 dening blue vegetable colours. It is eafily made by 
 diffolvipg that fait in the fulphuric acid, but it is not 
 eafy to convert this into the neutral fulphat of alumine 
 but by boiling it a long time with its earth. This fait, 
 like the firft, has not been defcribed. 3. Saturated 
 fulphat of alumine and of pot-afh is the alum of the 
 chemifts faturated with its earth. It is pulverulent, 
 infipid, infoluble, not cryftallizable, and is eafily con- 
 verted into true alum by the addition of fulphuric acid. 
 
 4. The acid fulphat of alumine and of pot-afli greatly 
 rcfembles common alum, and is ealily prepared chemi- 
 cally ; but M Vauquelin found no alum but that of 
 La Tolfa, which is exaftly of the fame nature with it. 
 
 5. The acid fulphat of alumine and of ammoniac has 
 all the properties of alum, and may be ufed for the 
 fame purpofes ; but though it is eafily made in the la- 
 boratories, our author never found it pure in commerce. 
 
 6. The acid fulphat of alumine, pot-afh, and ammo- 
 niac. It is remarkable enough, fays M. Vauquelin, 
 that this fhould be the nature of the alum moft fre. 
 quently made in the arts, and that to exprefs its com- 
 bination fo many words iTiould be neceffary. This, 
 however, may be avoided, by referving the name of 
 alum to this fubftance, whichwill be fufficient to di- 
 ftinguifh it perfeftly. 7. The acidulous fulphat of 
 alumine and of pot afti, our author fays, he is lefs ac- 
 quainted with than with the preceding feries. The 
 name by which he charafterizes it was fuggefted to 
 him, and he thinks it proper, becaufe by adding to the 
 folution a fmall quantity of pot-afh more than is ne- 
 ceffary to obtain odfahedral cry ftals, it maiiifeftly partes 
 to the cubic form. 
 
 From thefe deduftions, the phyfician, the chemift, , 
 and the manufafturer, with whom the ufes of alum are 
 greatly multiplied, will hereafter poffefs a knowledge of 
 the fubftance they employ, and may appreciate its ef- 
 fefts on the animal economy, and other bodies to which 
 it is fo frequently applied. See Annales de Chimie, xxii. 
 258, and Nicholfon's Journal., Vol. I. p 318, &c. 
 
 ALUMINE, one of the fimple earths. See Che- 
 MISTKY in this Supplement. 
 
 AMICABLE NUMBERS have been defined, and the 
 firft pair of them given in the Encycloptedia. The fe- 
 cond pair of amicable numbers are 17296 and 18416; 
 and the third pair ^re" 936^58+ and 94.370(16. 
 
 Dr Hutton informs us, that thefe three pairs of ami- 
 cable numbers, with the properties from which they re- 
 
 ceiTC
 
 A M S [ 9 ] 
 
 micsbli.', ccive tlieir name, were found out by F, Scliooten, as buvll the glaf: 
 
 imftc 
 dam. 
 
 appears from Sedl. ix. of his Exercitationes M.i//jfmatic,T. 
 To find the firil pair, he puts ^x and ^yz, or a^x and 
 a^yz. for the two numbeis, where ara ; then making 
 each of thefe equal to the fum of the ah'tiuot parts of 
 the other, gives two equations, from which are found 
 the values of .v and s, and confequently, aiFuniing a pro- 
 per value for ji, the two amicable numbers themfclves 
 4..V and 4yz. 
 
 In like manner for the other pairs of fuch numbers ; 
 in which he finds it neccflary to affume i6jc and i6yz, 
 or a*K and a^'yz for the fecond pair, and izSx and 
 X2Syz or a'x and ajz for the third pair. 
 
 Schooten then gives this praftical rule, from Def- 
 cartes, for finding amicable rules, viz. affume the num- 
 ber 2, or fome power of the number 2, fuch that if uni- 
 ty or 1 be fubtrafled from each of thefe three following 
 quantities, viz. from 3 times the affumed number, alfo 
 from 6 times the affumed number, and from 18 times 
 the fquare of the affumed number, the three remainders 
 may be all prime numbers; then the lafl prime number 
 being multiplied by double the affumed number, the 
 produft will be one of the amicable numbers fought, 
 and the fum of its aliquot parts will be the other. 
 That is, if a be put =: the number 2, and n fomc 
 integer number, fuch that 3(7" — i, and 6a" — i, and 
 l8ai" — I be all three prime numbers; then is i8a^" — i 
 X2a" one of the amicable numbers; and the fum of its 
 aliquot parts is the other. 
 
 AMSTERDAM and St Paul, are two Iflands in 
 the South Sea, lying in the fame degree of longitude, 
 and generally confounded with each other. The Dutch 
 navigators have given the name of .Imjlerdam to the 
 northern, and of St Paul to the fouthern ifland, and 
 Captain Cook conforms to that appellation. Moll 
 other Englifh navigators, and particularly Meffrs Cox 
 and Mortimer, with Sir George Staunton, reverfe the 
 names, calling the fouthern ifland Amfterdam, and the 
 other St Paul. At this fouthern ifland the Lion man 
 of war flopped on her voyage to China with Lord Ma- 
 cartney, the late ambalfador to the court of Pekin, 
 which gave an opportunity to the men of fcience in the 
 train of the ambaffador to examine the ifland with more 
 fl:ill and attention than probably it had ever been exa- 
 mined before. 
 
 Dr Gillan, who was appointed phyfician to the em- 
 balTy, as well for his knowledge of chemiftry as for his 
 medical fl<ill, is confident that the ifland of Amfterdam 
 is the produft of fubterraneous fire, as it bears in every 
 part of it evident marks of volcanic eruption. " On 
 the weft and fouth-weft fides (fays he) there are four 
 fmall cones regularly formed, with craters in their cen- 
 tres, in which the lava and other volcanic fubftances 
 have every appearance of recent formation. The heat 
 continues ftill fo great, and fuch a quantity of elaftic 
 vapours ilfues through numberlefs crevices, that there 
 can be no doubt of their having been very lately in a 
 ftate of eruption. In a thermometer placed upon the 
 I'urface, the quickfilver rofe conftantly to 180 degrees, 
 and when funk a little into the alhes, it advanced to 2 1 2 
 degrees. It certainly would have rifen ftill higher ; but 
 the fcale being graduated only to the point of boilijig 
 water, and the length of the tube proportioned to that 
 extent, the thermometer was immediately withdrawn, 
 left the increafing expanfiou of the quickfilver ihould 
 SupPL. Vol. I. Part I, 
 
 A M S 
 
 Tiie ground was felt tremulous under Amner. 
 the feet ; a ftone thrown violently upon It returned a, ^'"^ 
 hollow found ; and the heat was fo intcnfe for a con- ' 
 
 fiderable diftance around, that tha foot could not he 
 kept for a quarter of a minute in the fame pofition with- 
 out being fcorched. But the great crater on the eaft- 
 ern fide, now full of water, is by far the largeft here, 
 or perhaps elfewhere, and is of an aftonifliirig fize, con- 
 fiderably exceeding in diameter thole of Etna or Vcfu- 
 vius. The quantity of matter to be thrown up, which 
 required fo wide an orifice for its paffage, and the force 
 with which fuch matter was impelled, in order to over- 
 come the refiftance of the fuperincumbeiit earth and 
 fea, muft have been indeed prodigious. 
 
 " This vaft crater, according to the ufual method of 
 computing the antiquity of volcanoes, tnuft have been 
 formed at a very remote period. The lava all around 
 its fides is much decompofed, and has mouldered into 
 duft, which lies on the furface in many parts to a con- 
 fiderable dqpth. The decompofition has fupplicd a rich 
 foil for the long grafs growing on the fides of the cra- 
 ter, and has even fpread over moft parts of the ifland. 
 The fibrous roots of the grafs, extending in all direc- 
 tions through the decompofed lava and volcanic aflies, 
 and mixed in a decaying ftate with the vegetable mould, 
 produced from the annual putrefaftion of the leaves 
 and ftalks, have formed a layer of ("oil feveral feet deep 
 all over the ifland. But as it has nothing except its 
 own weight to comprefs it together, it is of a light 
 fpongy texture, with very little cohefion, and in many 
 places furrowed and interfefted by the fuminer rains, 
 and the torrents occafiuned by the melting of the fiiow 
 which lies upon it in the winter, from three to four 
 feet thick, in all thofe places where the fubterraneous 
 heat is not great enough to prevent its accumulation. 
 In fome parts thefe furrows and cavities are deeper than 
 the level of the common channel ; hence they ferve the 
 purpofe of fmall natural refervoirs. The water flows 
 into them from all the neighbouring ground ; and as 
 their fides are fliaded, and almoft covered over by the 
 leaves of the long grafs, growing from their edges In 
 oppofitc direftions, the rays of the fun are excluded, 
 and very little is loft by evaporation. Thefe refervoirs, 
 however, are very fmall, and but few in number ; the 
 largeft could not contain more than three or four hogf- 
 heads of water ; and there is none elfe to be found, 
 except in the fprings on the fides of the large crater. 
 
 " The foil everywhere being light and fpongy, and 
 full of holes, formed in it by fea-birds for nefts^is very 
 troublefome to walk upon ; the foot breaks through the 
 furface, and finks deep at every ftep ; a circumftance 
 which renders ihejourney acrofs the ifland uncommonly 
 fatiguing, although it be fcarcely three miles from the 
 edge of the great crater to the oppofite weft fide. 
 I'here is one place near the centre of the ifland, ex- 
 tending about 200 yards in length, and fomewhat lefs in 
 breadth.where particular caution isneceffary in walking 
 over it. From this fpot a hot frefli fpring is fuppofed 
 to derive its fource, finding its way through the inter- 
 ftices of the lava to the great crater, and burfting out 
 a little above the water covering its bottom. The 
 heat in this upper fpot is too great to admit of vegeta- 
 tion. The furface is covered with a kind of mud or 
 pafte formed from the aflies, moiftened by fleam con- 
 llantly rifing from below. When the mud is removed, 
 B the
 
 A M S [ 
 
 Amfter- the vapour ilTues fortli with violence, anJ in fume parts 
 dam. copioufly. This mud is fo hot, that a gentleman who 
 ^'~"^'~~' inadvertently ilcpped into it had his foot fcverefy 
 fcalded by it. The fame caufes which have prevented 
 vegetation on this fpot, have had the fame effect on the 
 funr cones recently thrown up. Their fnrfaces are co- 
 vered with alhes only ; nor is there tlie leaft appearance 
 even of mofs on the furrounding lava, for the produc- 
 tion of which there does not appear to have elapfed a 
 fufficient lingth of time fince tlie cones were formed : 
 but this is not the cafe with the lava of the great pri- 
 mary crater; for in thofc parts o!" it where the edges 
 are more perpendicular, and where confequently the 
 mouldering decompofed earth, having no bulls to fup- 
 port it, flides down the fides of the rock, pretty long 
 mofs was generally found growing upon it. All the 
 fprings or refervoirs of hot water, except one only, were 
 bracki'h. One fpring derives its fource from the high 
 ground and ridges of the crater. The water in it, in- 
 itead of boiling upwards through the Hones and mud, 
 as in the other fprings, flows downward with a confidcr- 
 able velocity, in a fmall collefted ilream. Its tempera- 
 ture has been found not to exceed 112 degrees. The 
 hand could be ealily kept in it for a coniidcrable time. 
 It is a pretty llrong chalybeate. The fides of the rock 
 whence it ilfues, and of the cavity into which it falls, 
 are incrulled with ochre depofited from it. 
 
 " When the great crater is viewed from the high 
 ground, it appears to have been originally a perfedl 
 circle, but to have been encroached upon by the fea on 
 the eaftern fide, where the flood tide ilrikes violently 
 
 10 ] A M S 
 
 wards of four miles, its breadth from call to weft about 
 tv\'o miles and a half, and its circumference eleven miles, 
 comprehending a furface of about eight fquare miles, 
 or 5120 acres, almoft the whole of win'ch is covered 
 witli a fertile foil. The ifland is inacceffible except on 
 the eaft fide, where the great crater forms a harbour, 
 the entrance to which is deepening annually, and might 
 by the aid of art be made tit tor the patTage of large 
 fiiips. The tides run in and out at the rate of three 
 miles an hour, and rife perpendicularly eight or nine 
 feet on the full and change of the moon ; a northerly 
 wind making the higheil tide. The water is eight or 
 ten fathoms deep clofe to the edge of the crater.; and 
 in the bafon formed by the crater itfelf, the variation 
 of the compafs was found to be nineteen degrees and 
 fifty minutes wellward of the north pole. 
 
 On the illand, which has no native inhabitants, were 
 found three Frenchmen and two natives of England, 
 who at the end of the American war had emigrated to 
 Bollon. The whole five had come lall from the Ifleof 
 France in the Indian Ocean, and had been left on the 
 ifland of Amilerdani, about five months before the ar- 
 rival of the Lion, for the purpofe of procuring a cargo 
 of 25,000 feal-iklns tor tlie Canton market, which, as 
 they had already procured 8000, they hoped to com- 
 plete in about ten months more. The veflcl which 
 brought them from the Ifle of France was gone to 
 Nootka Sound, with a view of bringing a quantity of 
 fea-otter fldns to China ; and afterwards of calling for 
 the cargo of feal-ikins at this place, to be carried to 
 China likewife; proceeding thus alternately to Nootka 
 
 The rocks of lava which formed the edge of the crater and Amfterdam ifland as long as the owners fliould find 
 
 on that fide have fallen down. The depth of the wa- their account in it. 
 
 ter in the crater is about 170 feet, rendering the whole The feals, whofe tkins are thus an article of corn- 
 height of the crater, from the bottom to its upper ridge, merce, are found here in greater numbers in the fum- 
 nearly if not quite 900 feet. The lofty rocks forming mer than in the winter, when they generally keep in 
 this ridge are the higheil parts of the ifland, which deep water, and under the weeds, which flielter them 
 
 ftems to have been originally produced by the melted 
 lava flowing down on all fides from hence. Thus there 
 is a gradual flope from the edges of the crater to the 
 fea ; and the lava, though very irregular, and lying in 
 mixed ruin and confufion immediately around the cra- 
 ter, affuraes a more uniform appearance at fome dill ance, 
 layer refting regularly upon layer, with a gradual decli- 
 vity the whole way down to the fea. This difpofition 
 
 from the inclemency ot the weather. In the fummer 
 months they come aihore, fometimes in droves of 800 or 
 1000 at a time, out of which about loo are dellroytd, 
 that number being as many as five men can ikiii and 
 peg down to dry in the courie of a day. Little of the 
 oil which thefe animals might furnifli is collected, for 
 want of cafl<s to put it in ; part of the beft is boiled, 
 and ferves thofe people inflead of butter. The feal of 
 
 of the layers is particularly obfervable in the wcfl fide, Amflerdam is the phoca urfina of Linnjeus. The fe- 
 where they happen to terminate in an abrupt precipice, male weighs ufually from 70 to 120 pounds, and is 
 The eruptions that took place at different periods ap- from three to five feet in length, but the male is con- 
 pear here diftinftly marked by the different layers that fiderably larger. In general they are not fliy : fome- 
 are found with regular divifions between them ; the times they plunge into the water inllantly upon any 
 glaffy lava being undermoft, the compaft next, the eel- one's approach, but at other times remain iteadily on 
 lular lava next above, over it the volcanic aflies and the rocks, bark, and rear themfelvcs up in a menacing- 
 lighter fubftances, and a layer of vegetable mould co- pofture ; but the blow of a flick upon the nofe feemed 
 vcring the whole." fuf&cient to dilpatch them. As the Ikins alone were 
 The ifland appears indeed in fuch a fl;ate of volcanic the objeCfs wanted, the carcafes were left on the ground 
 inflammation, that from the fliips decks at night were to putrefy at leifure, ilrewtd in fuch numbers as to ren- 
 obferved, upon the heights of the ifland, feveral fires der it difficult to avoid trading on them in walking 
 iffuing out of the crevices of the earth, more confider- along. The people thus employed were remarkable for 
 able, but in other refpefts refembling fomewhat the the fqualor and filth of their perfons, clothes, and 
 nightly flames at Pietra Mala, in the mountains between dwelling ; yet none of them feemed defirous of leaving 
 Florence and liologna, or thofe near Bradley in Lan- the place before the bufinefs they came upon fliould be 
 cafliire, occafioned by fome of the coal-pits having completed. One of them, an Engliihman, who had 
 taken fire. In the day nothing more than fmoke could been a confiderable time upon the ifland on a former 
 
 be perceived. 
 
 The length of the ifland from north to fouth is up. 
 
 adventure, gave but an unfavourable account of the 
 weather during the winter months, which are always 
 
 boifterous.
 
 Amder- 
 
 <lam, 
 
 ^naclrtfcic. 
 
 ANA [ II ] AND 
 
 hoiftevous, witli hail and fr.ow ; but in funimer lie ac- torn of a vcfTtl full of wntcr, to an eye placed in llie 
 
 air ; or the vault of the heavens, feen by refraftion 
 
 knowledged it to be very fine. 
 
 The fea fiipplics this ifland with great varieties of 
 excellent fifli, particularly a kind of cod, which was 
 equally rclifhed whether frelh or falted. Cray filh were 
 in fuch abundance on the bar acrofs the entrance into 
 the crater, that at low water they might be taken witl 
 
 through the atmofpherc. 
 
 ANAPHORA, in aftrology, the fecond houfc, or 
 that part of the heavens which is 30 degrees from the 
 horofcope. The term anaphora is alfo fomctinies ap- 
 plied proniifcuoully to fome of the fuccecding hcnifcs, 
 
 An.iphor* 
 
 11 • 
 
 AndLffon, 
 
 tlie hand; and at the anchorage of the Ihips, when baf- as the 5th, the 8th, and the nth. In this Icnfe ana 
 kets, in which were proper baits, were let down into pliora is the fame as epangphora, and ilands oppofed to 
 the fea, they were in a few minutes drawn up filled calapbora. 
 
 with cray fifli. This circumftance is the more extraor- ANASTROUS signs, in aflronomy, a name given 
 dinary, that in the fame place were found abundance to the ^//Wi'rrttono/-;£i, or the twelve portions of the eclip- 
 of fharks and dog filh of uncommon fize, which are tic, which the figns polFefred anciently, but have fuice 
 known to be fo voracious and fuch enemies to all other deferted by the precefllon of the equinox, 
 fifli. The bafon of the crater abounds with tench, ANCHOR OF A ship, is an inilrument which, as 
 bream, and perch ; and the perfon who with a hook it is commonly made, has been fuffieiently defcribed in 
 and line has caught any of thefe- fifli in the cold water the Encyclopaedia. An improvement, however, has 
 of the bafon, may with a flight motion of his hand let been propofed on its conftruftion by Mr James Stuard 
 them drop into the adjoining hot fpring already men- of the paridr of St Anne, Middlefex, who obtained a 
 tioned, in which they will be boilid and rendered fit patent for his invention, dated Feb. 1796. 
 for eating in the fpace of fifteen minutes. This was The whole of this invention confifts in makinT the 
 often praftifed by the gentlemen of the enibalTy, and anchor with one fluke or arm inftead of two, and cou- 
 furniflied them at once with a fingular amufement and triving to load that fluke or arm in fuch a manner as to 
 a highly relifhcd repalt. make it always fall the right way. With this view Mr 
 
 Of all the bL-v'" which frequent this ifland, fo extra- Stuard would have the (hank of the anchor made very 
 ordinary In its origin, formation, and appearance, not fliort, that it may cant the more when fufpended by the 
 One is common to the fame degree of latitude in the cable; and he would have the arm and it made of bars 
 northern hemifphere. Of the larger kind were feveral in one length, that there may be no flioot or joinincr in 
 fpeciesofthe albat-ojs; on examining one of which, the whole infl:rument. The bend of the fliank and arm 
 diftinguiflied by the name oi exulans, it was found, that he would have rounded, and not angular as in the com- 
 iii'^.cad of having only the rudiments of a tongue, as mon anchor ; and on this bend he would have a fmall 
 naturalifts generally fuppofe, it had one equalling half fliackle, or two plates with a fmall bolt between them, 
 the length of the bill. Another large bird is likewife for the buoy-rope to be made fafl. to. Inflcad of woi;d, 
 common here, called the great black petrel, or procellaria hepropofes for the ilockof the anchor a bar of wrought 
 equino&ialis of Linnaeus. It is the determined enemy iron, loaded or covered at the ends with knobs of call 
 of the albatrofs, as well as of the Hue pdrd ui Amilcv- iron ; and he would have the palm of the fluke or arm 
 dam, or procellaria forjleri. This blue petrel, which is either to be compofed entirely of caft; iron, or to be a 
 about the fize of a pigeon, con ft;itute3 the principal food call iron fliell filled with lead. This weight of the palm, 
 of the fcal catchers on the ifland. During the day-time the fliortnefs of the flrank, and the ilrufture of the 
 they hide themfclvcs in the ground, in order to cfcape, ilock, will no doubt make the anchor fall the right way ; 
 if pofTible, their dellroyer the black petrel. At night which, having no upper fluke, will never be tripped by 
 they come abroad, and thence are termed night birds by the cable taking held of it on the Ihip's fwinging, nor 
 the people at Amfterdam ; but being fond of flocking will it prove fo dangerous as the common anchor to 
 to any light, they tall into another fnare laid for them fuch veffels as may happen to ground by it. 
 by the feal-catchers, who kindle torches to attraft them, ANDERSON (Alexander), an eminent mathema- 
 and then kill them in mult'"udes. The prettied of the tician, was born at Aberdeen towards the end of the 
 feathered tribe, inhabiting or vifiting Amtterdam, is the J 6th century. Where he was educated, or under what 
 fdverbird, or fterna hirundo, about the fize of a large mailers, we have not learned ; probably he iludied the 
 fwallow or fwift, with a forked or fvvallow tail. The belles lettres and philofophy in the univerfity of his na- 
 bill and legs are of a bright crimfon colour, the belly live city, and, as was the prafticein that age of all who 
 white, and the back and wings of ^bluilh aflr colour, could afford it, went afterwards abroad for the cultiva- 
 Tbis bird fubfifts chiefly on fmall fifli, which it picks tion of other branches of fcience. But wherever he 
 up as they are fwimming over the furface of the water, may have Iludied, his progrefs in fcience niufl have 
 
 This fingular ifland lies in 38" 42' S. Lat. and in been rapid ; for, early in the 1 7th century, we find him 
 76'^ 54' E. Long, from Greenwich. St Paul's, or the profeflLr of mathematics in the univerfity of Paris, 
 ifland lying in fight and to the northward, differed in where he publiflied feveral ingenious works; and among 
 appearance materially from Amfl:erdam. It prefented others, i. Supplemenlum Apolknii Redivivt i ft-vs analy- 
 no very high land, or any rifing in a conic form ; and Jii problematis haCienus deji'lirati ad Apollomi Pergui doc- 
 feemed to be overfpread with flirnbs or trees of a mid- Irinam -atp, viunuv, a Marino Ghetaldo Patritie Jiajtj/tn^ 
 dhng fize. It was faid to abound with frefli water, hujufque, non ita pridem reflitulam. In qua exhibetiir mc- 
 but to have no good anchorage near it, nor any place chanice aqualitalum tert'ii gradus ft-ve folidarum, in quibus 
 of taly landnig. — Sir George Staunton's Account of an magnitudo omnino data, aquatur homogeneit fub altero tan- 
 Lmbajjy to the Emperor of China. turn coejjicientc ignote. Huic fubnexa efl variorum proble- 
 
 ANACLASTIC curves, a name given by M. de matumpraSice, Paris, 1612, in 4to. — 2. AmoMyia : Fro 
 Mairan to certain apparent curves formed at the bot- Zetetico Apolloniani problematis a fe jam pridem cdito in 
 
 B 2 fuppkmentd
 
 A N H 
 
 [ 
 
 Andnf^n, J'upplemento Apollonii Redlvhn. JJ clariffimum el orna- 
 Anhin;,'a. i\JJl^^,„ vlrum Mariiium ChttaUum Pnlrilium Ragufmum. 
 ^"^ Jn qua aJ ea qii<e obiter milii perjlr'mxh Ghelaldus refpon- 
 
 Jelur, tt analyUces ilarius detegilur. Pans, 1615, in 
 410.-3. Francifci rittj; Fontenacenfis dc JEquai'iomim 
 Recognitione et Emendatlone Tradatus duo, with a dedi- 
 cation, preface, and appendix, by liimfclf. Paris, 1615, 
 in 4to. — 4. Vieta's Angulares Seaioncs; to which he 
 added demonftrations of his own. Our profetTor was 
 coufin-german to Mr David Anderfon of Finlhaugh, a 
 gentleman who alfo poncffed a lingular turn for mathe- 
 matical knowledge. This mathematical genius was 
 hereditary in the family of the Anderfons ; and from 
 them it feems to have been tranfmitted to their de- 
 fcendants of the name of Gregory, who have for fo ma- 
 ny generations been eminent in Scotland as proftflors 
 either of mathematics, or, more lately, of the theory 
 and pradice of phylic. The daughter of the David 
 Anderfon juft mentioned, was the mother of the cele- 
 brated James Gregory, inventor of the reflefting tele- 
 fcope ; and obferving in her fon, while yet a child, a 
 ftrong propeniity to mathematical ftudies, (he inftrufted 
 him in the elements of that fcience herfelf. From the 
 fame lady defcended the late Dr Reld of Glafgow, 
 who was not lefs eminent for his knowledge of mathe- 
 matics than for his writings as a metaphyfician. 
 
 Theprecife dates of Alexander Anderfon's birth and 
 death, we have not learned either from Dempiter, 
 Mackenzie, or Dr Hutton, who feems to have ufcd 
 every endeavour to procure info'-mation ; nor are fuch 
 of his relations as we have had an opportunity of con- 
 fulting, fo well acquainted with his private hiftory as 
 we expefted to find them. 
 
 ANHINGA, in ornithology, a fpecies of the peli- 
 canu?, confiils of four known varieties; two peculiar to 
 America, one to Senegal, and the fourth to the region 
 about the Cape of Good Hope. This laft is thus de- 
 fcribed by Le Vaillant in his New Travels into the In- 
 terior Parts of Africa. 
 
 " The denomination of Slange-Hah-Voogel, given to 
 it by the Hottentots, charaflerifes the anhinga in a ve- 
 ry fimple and accurate manner. Buffon, who was 
 ftruck with the conformation peculiar to birds of this 
 kind, has delineated them by a fimilar exprcffion. 
 Kate HI. 'The anhinga (fays he) exhibits a reptile grafted on 
 the body of a bird.' Indeed there is no perfon who, 
 upon feeing the head and neck only of an anhinga, 
 while the reft of the body is hid among the foliage of 
 the tree on which it is perched, would not take it for 
 one of thofe ferpents accuftomed to climb and rcfide in 
 trees ; and the miftake is fo much the eafier, as all its 
 tortuous motions iingularly favour the illufion. In 
 whatever fituation the anhinga may be feen, whether 
 perched on a tree, fwimming in the water, or flying in 
 the air, the moft apparent and remarkable part of its 
 body is fure to be its long and flender neck, which is 
 continually agitated by an ofcillatory motion, unlefs in 
 its flight, when it becomes immoveable and extended, 
 and forms with its tail a perfedly ftraight and horizon- 
 tal line. 
 
 " The true place which nature feems to have afiigned 
 to the anhingas, in the numerous clafs of the palmi 
 pedes, is exaftly between the cormorant and the grebe. 
 They partake indeed equally of both thefe genera of 
 birds, having the ftraight flender bill and the long neck 
 
 2 ] ANT 
 
 of the latter ; while they approach the former hy the 
 conformity of their feet, the four toes of which are 
 joined by a fingle membrane. They partake alfo of 
 the cormorant by their flight; having like it the wings 
 larger and fitter for the purpofe than thofe of the grebe, 
 whicii are fliort and weak. The tail of the anhinga is 
 extremely long ; a charaAerillic very Angular and re- 
 markable in a water fowl, and which ought, it would 
 feem, to render them totally diftinft from diving birds, 
 which in general have little or no tail. By this trait 
 they approach ftiU nearer to the cormorants ; for tho' 
 the tails of the latter are fliorter, the tails of both have 
 a great refemblance to each other, fince their quills are 
 equally llrong,elaftic, and properto form a rudder whea 
 thefe fowls fwim through the water in purfuit of fifli, 
 which conftitute their principal nourifliment. When 
 the anhinga feizes a fifli, he fwallows it entire if it be 
 fmall enough, and if too large he carries it ofl^ to a rock 
 or the ftump of a tree, and fixing it under one of his 
 feet, tears it to pieces with his bill. 
 
 " Though water is the favourite element of this bird, 
 it builds its neft and rears its young on rocks and trees ; 
 but it takes great care to place them in fuch a manner, 
 that it can precipitate them into a river as foon as they 
 are able to fwim, or the fafety of the little family may 
 require it." 
 
 The male anhinga differs from the female, which is 
 fmaller, in having the whole under part of the body, 
 from the breaft to the root of the tail, of a beautiful 
 black, while the latter has the fame parts of a yellovy 
 ifabella colour. It has alfo, on each fide of its neck, a 
 white ftripe, which extends from the eye to the middle 
 of its length, and interfefts a reddifti ground. A very 
 fingular charafterillic, common to all the anhingas, is 
 that of having the feathers of the tail deeply Itriated, 
 and as it were ribbed. It is a very fagacious bird, ef- 
 pecially when furprifed fwimming ; for its head is the 
 only part which it expofes above the water; and if the 
 fportfman once mifs that part, the anhinga plunges out 
 of fight entirely, and never more fliows itfelf but at ve- 
 ry great diftances, and then no longer at a time than 
 is abfolutely neceflary for breathing. 
 
 ANTECEDEN TAL calculus. See Calculus 
 in this Supplement. 
 
 ANTES, in architefture, fmall pilaftres placed at 
 the corners of buildings. 
 
 AN riCS, in architefture, figures of men and ani» 
 mals placed as ornaments to buildings. 
 
 AN nCUM, in architedure, a porch; alfo that 
 part of a temple which lies between the body of the 
 temple and the portico, and is therefore called the outer 
 temple. 
 
 ANTIMETER, or Reflecting Sector, an in. 
 ilrument invented by Mr William Garrard, for the pur- 
 pofe of meafuring angles, particularly fmall ones, with 
 a greater degree of accuracy than can be done by 
 Hadley's quadrant or by the fextant. 
 
 The frame of this inftrument is fimilar to that of 
 Hadley's quadrant, having two radii, a limb, and bra- 
 ces ; but with this difference, that the further radius is 
 produced upwards of four inches beyond the centre of 
 motion of the index ; and the great fpeculum, or what 
 is called the index-glafs in Hadley's quadrant, being 
 placed there, is called the upper centre In this inftru- 
 ment there is no provifion for the back obfervatiom 
 
 The
 
 ANT [ 1 
 
 intlmeter. The liorizon-glafs is like that in Hadley's quadrant ; 
 ■""Y*""' there are two fight vanes, to fuit two different iitua- 
 tions of the large fpecuhim or objedl glafs: thefe vanes 
 are adapted to receive a fmall telcfcope. On the centre 
 of the index, where the index glals of Hadley's qua- 
 drant is fixed, is a brafs or bell-metal femicircle, two 
 inches in diameter, and one-eightli of an inch thick : 
 this femicircle is fcrewed fall to the index, in fuch a 
 manner that the axis o^ the index is a tangent to it. On 
 the upper centre are two circular brafs plates, which 
 revolve concentrically, either together or feparately. 
 The under plate has a lever, or part perpendicular to 
 the plane of the inftrument, projefting downwards, a 
 little beyond the lower centre: this lever is adled upon 
 by the femicircular plate at the lower centre, to which 
 it is always kept clofe by a fpring on the other fide. 
 In the upper of the above mentioned circular pl-ates are 
 two circular perforations or flits, through one of which 
 a fcrew takes into the head of the inftrument, and 
 through the other a fcrew takes into the lower move- 
 able plate. The large fpeculum is fattened to the upper 
 plate ; and by the above mentioned fcrews the pofition 
 of this glafs may be altered. A circular plate is fixed 
 to the lower centre by three pillars : in its centre is a 
 nut to admit a fcrew,* Dy which the plate carrying the 
 large fpeculum may be taftened here occafionally. 
 
 The fcale on the limb is divided into 45 equal parts 
 or degrees, and not into half degrees, as is the cafe in 
 Hadley's quadrant, by reafon of the double refledlion. 
 Thefe divifions are numbered in a retrograde order ; 
 zero being at the extremity of the further radius. Al. 
 though the limb contains 45 degrees, yet the greatell 
 angle which can be meafured, the large fpeculum le- 
 niaining fixed to the circular plate, is 10° 18' 21 ".8 ; 
 the diftance between the two centres being four inches, 
 and the radius of the femicircle one inch. Agreeable 
 to thefe dimenfions, the inventor has given a table ex- 
 hibiting the value of each primary diviiion on the limb; 
 he hath alfo given a more ample table, adapted to a 
 diftance between the centres of three times the radius 
 of the femicircle, which he fays hath been found the 
 moft convenient in praftice. If an angle greater than 
 10° 18' is wanted, it may be meafured by the method 
 ef anticipation, as the inventor calls it, which is as fol- 
 lows : Let the fcrew which fallens the two circular 
 plates on the upper centre be made faft, and loofen the 
 fcrew which faftens the upper circular plate to the in- 
 ftrument : Now adjuft the glafles by the ufual method; 
 bring forward the index to any given divifion un the 
 limb, and make it faft; alfo faften the fcrew which was 
 before loofe, and loofen the other fcrew; then bring the 
 index to zero, and proceed as before. 
 
 The inventor gives the following direftions for ad- 
 jufting and ufing the inftrument. 
 
 The firft thing to be attended to is, to fet the hori- 
 zon-glafs perpendicular to the plane of the inftrument, 
 which is performed as follows : Hold the inftrument 
 with its plane perpendicular to the horizon, and look 
 over backwards into the glafs and beyond it. If the 
 limb of the inftrument appears in a right line with its 
 refledlion, the glafs is upright ; but if it does not ap- 
 pear fo, loofen or tighten the little fcrew on the foot of 
 the glafs until it be a Jjufted : Then with the inftrument, 
 as in taking an altitude, look through the fight vane 
 or tclefcope at fome diftant objeft, with the i-idex fixed 
 
 3 ] APE 
 
 in any intended fituation ; the two fcrews at the upper 
 centre being loole, turn the glafs about till the fame 
 objeft appears nearly in the fame part of the horizon- , 
 glafs : Next hold it in a horizontal pofition, and ad- 
 juft the objedl-glafs or large fpeculum with the fcrews 
 which are behind and before, on the foot of it, till the 
 objedl and its rcfleftion are feen in the fame horizontal 
 line. Laftly, with the inftrument upright, turn the 
 tangent-fcrew belonging to the horizon-glafs ^t the 
 back of the inftrument, until there be a perfeft coin- 
 cidence of the objeft and its refleftion that way, and 
 the adjuftments arc complete. 
 
 ANTIPARALLELS, in geometry, are thofe lines 
 which make equal angles with two other lines, buE 
 contrariwife ; that is, calling the former pair the 
 firft and fecond lines, and the latter pair the third and 
 fourth lines, if the angle made by the firft and third 
 lines be equal to the angle made by the fecond and 
 fourth, and contrariwife the angle made by the firft 
 and fourth equal to the angle made by the fecond and 
 third; then each pair of lines are antiparallcls with re- 
 fpeft to each other, viz. the (irft and fecond, and the 
 third and tonrlh. So, if AB and AC be any two lines, 
 and FC and FE be two others, cutting them fo, 
 that the angle B is equal to the angle E, 
 and the angle C is equal to the angle D; 
 then BC and DE are antiparallels with refpe-ft to A3 
 and AC ; alfo theie latter are antiparallcls with regard 
 to the two former It is a property of thefe lines, that 
 each pair cuts tlic other into proportional fegments, ta- 
 king them alternately, 
 
 viz. AB : AC : : AE : AD : : DB : EC, 
 and FE : FC : : FB : FD : : DE : BC. 
 APERTURE, in optics, has been defined in the- 
 Encyclopasdia, but no rule was given thet^e for fiiiding 
 a juft aperture. As much depends upon this circum- 
 ftance, our optical readers will be pleafed with the fol- 
 lowing praflical rule given by Dr Hutton in his Ma- 
 thematical Dictionary. " Apply ieveral circles of dark 
 paper, of various fizes, upon the tace of the glafs, from 
 the breadth of a ftraw to fuch as leuve only a fmsll hole 
 in the glafs ; and with each of thefe, feparately, view 
 fome diftant objeft, as the moon, ilars, Sec. then that 
 aperture is to be chofen through which they appear the 
 moft diftinftly. 
 
 " Huyghens firft found the ufe of apertures to con- 
 duce much to the perfeftion of telefcopes; and he found 
 by experience [Diopt. prop. 56.), that the beft aper- 
 ture tor an objeft-giafs, for example of 30 feet, is to be 
 determined by this proportion, as ^50 to 3, fo is the 
 fquare root of 30 times the diftance of the focus of 
 any lens to its proper apeiture : and that the focal di- 
 ttances of the eye-glafles are proportioned to the aper- 
 tures. And M. Anzout fays he found, by experience, 
 that the apertures of telefcopes ought to be nearly in 
 the fub-duplicate ratio of their lengths. It has alfo 
 been found by experience, that objctt-glafles will ad- 
 mit of greater apertures, it the tubes be blacked within 
 fide, and their paffage furnifhed with wooden rings. 
 
 " It is to be noted, that the greater or lefs aperture 
 of an objeiVglafs, does not increale or diraniilli tlic vi- 
 fible area of the objcft ; all that is cftedted by this is 
 the admittance of more or fewer rays, and co- fequently 
 ...the more or lefs bright the -.1^ pearance of ' lie objeft,. 
 But the largenefs of the aperture or focal diftancucauXes ■ 
 
 tiie: 
 
 Antiparal- 
 lcls, 
 Apcriure. 
 
 Plare II.. 
 
 fig- 5-
 
 ARC [ 14 ] ARC 
 
 ApotataC- the Irrecjulaiity of iis refraftioiis. Ilmce, in viewing in iie(.d of fliadc from tin; fun than of flichcr from the Arch. 
 
 tafi* Venus through a tckfcope, a much kfs aperture is to inclemency of the weather. A very fmall addition to » — 
 
 y^fll, be ufed than for the moon, or Jupiter, or Saturn, be- the fliade of the woods ferved them for a dwelling, f^j^^'^ 
 
 ■ caufe her light is fo bright and glaring. And thiscir- Sticks laid acrofs from tree to tree, and covered with architec 
 
 cumilance fomewhat invalidates and didurhs Azout's liruftiwood and leaves, formed the iirll houfes in thofeure ccn- 
 
 proportion, as is fliown by Dr Hook, Phil. Tranf. delightful regions. As population and the arts impro-""^!*";^ *' 
 
 J.J0 4.." ved, thefc hnts were gradually refined into commodious ^^'^'■''' 
 
 APOC ATASTASIS, or, as it fliould be written, dwellings. The materials were the fame, but more art- 
 Apok.4tastasis, is a Greek word employed in the fuUy put together. At lail agriculture led the inhabi- 
 language of aftronomers, to denote the period of a pla- tants out of the woods into the open country. The 
 net^ or the time it takes to return to that point of the conneftion between the inhabitant and the foil became 
 2odiac whence it fet out. now more conllant and more intercfting. Tire wiflito 
 APOTOME, is a term employed by Euclid to de- preferve this conneftion was natural, and fixed ella- 
 note the difference between two lines or quantities bliflimcnts followed of courfe. Durable buildings were 
 •which are only commenfurable in powder. Such is the more defirable than thofe temporary and perifhabk cot- 
 difFerence between 1 and V':?, or the difference be- tages—flone was fubilituted for timber. m 
 tween the fide of a fquare and its diagonal. The doc- But as thefe improved habitations were gradual re- 
 trine of apotomes in lines, as delivered by this ancient finements on the primitive hut, traces of its conftruc- 
 mathcmatician in the tenth book of his Elements, is tion remained, even when the choice of more durable 
 a very curious fubject, and has always been admired materials made it in fome meafure inconvenient. Thus ( 
 bv fuch as underllood it. The firft algebraical wri- it happened, that while a plain building, intended for 
 ters in Europe, fuch as Lucas de Burgo, Cardan, Tar- accommodation only, conClted of walls, pierced with 
 talea, Stifelius, &c. employed a confiderable portion of the neceffary doors and windows, an ornamented build- 
 their works on an algebraical expofition of that which ing had, fuperadded to thefe effentials, c.lumns, with 
 led them to the doftrine of furd quantities. the whole apparatus of entablature, borrowed from the 
 APPARENT CONJUNCTION of the planets, is when wooden building, of which they had been eiTential 
 a rin-ht line, fuppofed to be drawn through their cen- parts, gradually rendered more fuitable to the purpofes 
 tres, paffes through the eye of the fpeftator, and not of accommodation and elegance. ^ 
 through the centre of the earth. And, in general, the This view of ornamental architefture will go far to Origin of 
 apparent conjunftion of any objefts, is when they ap- account for fume of the more general diffsrences of na-Grrck ar- 
 pear or are placed in the fame right line with the eye. tional ftyle which may be obferved in diflerent parts of '"'""■*" 
 
 ^PF.fktNT Diameter t)f a planet or other heavenly the world. The Greeks borrowed many of their arts 
 body, is not the real length of the diameter of that from their Afiatic neighbours, who had cultivated them 
 body, but the angle which it fubtends at the eye, or long before. It is highly probable that architefture 
 under which it appears. travelled from Perfia into Greece. In the ruins of Shu- 
 ArPARF.NT Diftance, is that which we judge an ob- fhan, Perfepolis, or Tchilminar, are to be feen the firll 
 jeft to be from us wlien feen afar off; and which isal- models of every thing that diilinguiihes the Grecian ar- 
 moft always very different from the true dillance. chiteflures. There is no doubt, we fuppofe, among 
 Arr.iRENT Figure, is the figure or fliape under which the learned, as to the great priority of thele monuments 
 an objeel appears when viewed at a diftance ; and is to any thing that remains in Greece ; efpecially if we 
 often very different from the true figure. Thus a take into account the tombs on the mountairiS, which 
 ftraight line, viewed at a diftance, may appear but as a have every appearance of greater antiquity than the re- 
 point ; a furface, as a line ; and a folid, as a furface. mains of Perfepolis. In thofe tombs we fee the whole 
 Apparent Motion, is either that motion which we ordomiance of column and entablature, jull as they be- 
 perceive in a diftant body that moves, the eye at the gan to deviate from their firft and neceffary forms in 
 fame time being either in motion or at refl ; or that the wooden buildings. We have the architrave, frize, 
 motion which an object at reft feems to have, while and corniche; the far-projeftingrautules of the Tufcan 
 the eye itfelf only is in motion. and Doric orders; the modiUions no lefs diftinft; the 
 Apparent Place of a Planet, Sec. in aftronomy, is rudiments of the Ionic capital; the Corinthian capital 
 that point in the furface of the fphere of the world in perfetlion, pointing out the very origin of this 01 na- 
 ■where the centre of the luminary appears from the nient, viz. a number of long graceful leaves tied round 
 furface of the earth. the head of the column with a fillet (a cuftum which we 
 APPARITION, in aftronomy, denotes a ftar's or know to have been common in their temples and ban- 
 other luminary's becoming vifible, which before was qncting rooms) ^ Where the diftance between the co- 
 hid. So, the heliacal rifing, is rather an apparition Inmns is great, fo that each had to fuppoi t a weight 
 than a proper rifing. too great for one tree, we fee the columns eluftered or 
 ARCH, in building, is an artful difpofition and ad- fluted, S:c. In fhort, we fee every thing of the Grecian 
 juftmcnt of feveral ftones or bricks, generally in a bow- architetture but the floped roof or pediment ; a thing 
 like form, by which their weight produces a mutual not wanted in a country where it hardly ever rains. 4 
 preffure and abutment ; fo that they not only fupport The ancient Egyptian architecture feems to be a re- Egyptian 
 each other, and perform the office of an entire lintel, hnement on the hut built of clay or unburnt bricks mix- 
 but may be extended to any width, and made to carry ed with llraw; every thing is maffive, chimfy, and timid; 
 the moft enormous weights. fmall intercolumnations, and hardly any projettions. , 
 
 In thofe mild climates which feem to have been the The Arabian arclutefture feems a refinement on the Arabian, • 
 firft inhabited parts of this globe, mankind ftood more tent. A mofque is like a Little camp, confifting of aanJ 
 
 number 
 
 I 
 Arch de- 
 fined.
 
 ARC 
 
 [ ^5 ] 
 
 ARC 
 
 6 
 
 Jhlne'e ar 
 hice£luie. 
 
 number of little bell tents, Ihick cloic together round a 
 ' irreat one. A caravanfcray is a court furrounded by a 
 row of fuch tents, each having its own dome. The 
 Greek church of St Sophia at Condantinople has imi- 
 tated this In fome degree ; and the copies (roniit, which 
 have been multiplied in Rnffia as the facred form for a 
 Chrillian church, have adhered to the original model of 
 cluftercd tents in the ftrideil manner. We are fome- 
 times difpofed to think that the p:iinted glafs (a fafliion 
 brought from the Eall) was in imitation oi the pamted 
 hangings of the Arabs. 
 
 TheChincfe architeftnre is an evident imitation of a 
 wooden building. Sir Geo. Staunton fays, that the 
 fmgular form of their roofs is a profelfed imitation of 
 the cover of a fquare tent. 
 
 In the ftone-buildings of the Greeks, the roofs were 
 imitations of the wooden ones; hence the lintels, flying 
 corniches, ceilings in compartments, &c. 
 
 The pediment of the Greeks feemsto have fnggelled 
 the grealeft Improvement in the art of building. In 
 erecting their fniall houfes, they could hardly fail to ob- 
 ferve occafionally, that when two rafters were laid to- 
 gether, from the oppofite walls, they would, by leaning 
 on each other, give mutual fuppon> as in fig. i. Nor 
 is it unlikely that fuch a fituation of ftones as Is repre- 
 feiited in fig. z. would not unfrcquently occur by acci- 
 dent to raafons. This could hardly fail of exciting a 
 little attention and refieftion. It was a pretty obvious 
 refleftion, that the (lones A and C, by overhanging, 
 leaned sgainil the intermediate ftone B, and gave it 
 fome fupport, and that B cannot get down without 
 thrufling afide A and C, or the piers which fupport 
 them. This was an approach to the theory of an arch; 
 and If this be combined with the obfervation of fig. i. 
 we get the difpofulon reprcfented in fig. 3. having a 
 perpendicular joint In the middle, and \\\t prhic'ipU of 
 the arch is completed. Obferve that this Is quite diffe- 
 rent from the principle of the arrangement in fig. 1. 
 In that figure the ftones aft as wedges, and one cannot 
 get down without thrufling the rell afide; the fame 
 principle obtains in fig. 4. confilllng of five arch ftones ; 
 but in fig. 3. the Hones B and C fupport each other 
 by their mutual preffure (independent of their own 
 weight), arlfing from the tendency of each lateral pair 
 to fall outwards from the pier. This is the principle 
 of the arch, and woiald fupport the key-Hone of fig. 4. 
 although each of its joints were perpendicular, by rea- 
 fon of the great friction arifing from the horizontal 
 thruft exerted by the adjoining Hones. 
 
 This was a moft Important dlfcoveiy in the art of 
 building ; for now a building of any width may be 
 roofed with flone. 
 
 We are difpofed to give the Greeks the merit of this 
 difcovcry ; for we obferve arches in the moll ancient 
 buildings of Greece, fuch as the temple of the fun at 
 Athens, and of Apollo at Dldymos ; not indeed as 
 roofs to any apartment, nor as parts of the ornamental 
 defign, but concealed in the walls, covering drains or 
 other neceffary openings ; and we have not found any 
 real arches in any monuments of ancient Perfia or E- 
 gypt. Sir John Chardin fpeaks of numerous and ex- 
 tenfrve fubterranean paffages at Tchllminar, built of 
 the moft exqulfite mafonry, the joints fo exaft, and the 
 ftones fo beautifully dreffed, that they look like one 
 continued piece of polifhed marble : but he nowhere 
 
 fays that they are arched; a circuniftance which we Ar.h. 
 think he would not have omitted — no arched door ' v —^ 
 or window is to be ften. Indeed one of the tombs 
 is faid to be arch-roofed, but it is all of one folld 
 rock. No trace of an arch is to be feen in the ruins of 
 ancient Egypt ; even a wide room is covered with a 
 fingle block of ftone. In the pyramids, indeed, there 
 are two galleries, whofe roofs confift of many pieces; 
 but their conftructloij puts it beyond doubt that the 
 builder did not know what an arch was : for it Is co- 
 vered in the manner reprefented in fig. 5. where every 
 piojecting piece Is piore than balanced behind, fo that 
 the whole awkward mafs could have ftood on two pil- 
 lars. The Greeks therefore fcem entitled to the honour 
 of the invention. The arched dome, however, feemsto 
 have arifcn in Etruria, and originated In ail probability 
 from the employment of the augurs, whofe bufine'fs it 
 was to obferve the flight of birds. Their ftatlons for 
 this purpofe were templi, fo called a tcmplando, " on the 
 fuminits of hills." To Ihelter fuch a perfon from the 
 weather, and at the fame time allow him a full profpcft 
 of the country around him, no building was fi) proper as 
 a dome fet on columns; which accordingly Is the figure 
 of a temple in the moft ancient monuments of that coun- 
 try. We do not recolleft a building of this kind in 
 Greece except that called the Lanlbfrn of Da>wjlhenes, 
 which Is of very late date, whereas they abounded in 
 Italy. In the later monuments and coins of Italy or of 
 Rome, we commonly find the Etrufcan dome and the 
 Grecian temple combined \- and the famous pantheon 
 was of this form, even In its moft ancient ftatc. 
 
 It does not appear that the arch was confidercd as a 
 part of the onmnienlal archltcdure of the Greeks during 
 the time of their independency. It Is even doubtful 
 whether it was employed in roofing their temples. In 
 none of the ancient buildings where the roof Is "-one, 
 can there be feen any rubblfii of the vault, or mark of p, 
 the fpring of the arch. It is not unfrequcnt, however. It was nfcd 
 after the Roman conquefts, and may be feen In Athens *' ''''" ""'/ 
 Delos, Palmyra, Balbek, and other places. It is very "^.^''j*'^" 
 frequent in the magnificent buildings of P..ome ; fuch dudls.''"'' 
 as the Collfeum, the baths of Dioclefian, and the tri- 
 umphal arches, where its form is evidently made the 
 objeft of attention. But its chief employment was In 
 bridges and aquediifts ; and It is in thofe works that 
 Its Immenfe utility is the moft confplcuous : For by this 
 happy contrivance a canal or a road may be carried 
 acrofs any ftream, where it would he almoft impofiible 
 to erect piers fufficiently near to each other for carry, 
 ing lintels. Arches have been executed i ^50 feet wide, 
 and their execution demonllrates that they may be 
 made four times as wide. 
 
 As fuch ftupendous arches are the greateft perform- niffia°ty 
 ances of the mafonic art, fo they are the moft difficul: of conftruc- 
 and delicate. When we refleft on the immenfe quan-""B"- 
 tity of materials thus fufpended in the air, and compare 
 this with the fmall cohefion which the firmeft cement 
 can give to a building, we fliall be convinced that It is 
 not by the force of the cement that they are kept to- 
 gether : they Hand faft only In confequence ot the 
 proper balance of all their parts. Therefore, in order 
 to ereft them with a well-founded confidence of their 
 durability, this balance ftiould be well underftood and 
 jiidlcioufly employed. We doubt not but that this was 
 underftood in fome degree by the engineers of antiqui- 
 ty..
 
 ARC 
 
 [ i6 1 
 
 ARC 
 
 A:i-h. 
 
 ty i but they have left us none of their knowledj^e. Iccii the magnificent vaultings of the temple of Mars the 
 They muft have had a great deal of mechanical know. Avenger, and the temple of Peace at Rome, the tliruft3 
 
 Arch. 
 
 ,.1-11 "4 It du'e before they could ercft the magnificent and beau- of which are withilood by two mafles of folid wall, 
 niv'c't^es tiful buildings whofe ruins ftill enchant the world ; but which join the iide walls of the temple at right angles. 
 
 -of the Die. they kept it among themfelves. We know tiiat the 
 njfiaca. Dionyfiacs of Ionia were a great corporation of archi- 
 tefts and engineers, who undertook, and even monopo- 
 lized, the building of temples, iladiums, and theatres, 
 nrecifely as the fraternity of mafons in the middle ages 
 monopolized the building of cathedrals and conventual 
 • churches. Indeed the Dionyfiacs refcmblcd the myili- 
 cal fraternity now called free mafons in*many important 
 particulars. They allowed no ilrangers to inlcrtere in 
 
 and extend i'ldewife to a great ditlance. It was evident 
 that the walls of the temple could not yn'eld to the pref- 
 fure of the vaulting without pufliing thefe immejife but- 
 trefles along their foundations. He therefore placed 
 four buttrcfles to aid his piers. They are almoll folid 
 maflcs of ftone, extending at lead 90 feet from the piers 
 to the north and to the fouth, forming as it were the 
 fide walls of the crofs. They effeflually fecured them 
 from the thruils of the two great arclies of the nave 
 
 their employment; they recognlfed eacli other by figns which fupport the dome ; but there was no fuch pro- 
 and tokens; they profefTed certain myfterious doctrines, vifioii agair.ft the pulh of the great north and fouth 
 under the tuition and tutelage of Bacchus, to whom arches. Anthcmius trulled for this to the half dome, 
 they built a magnincent temple at Teos, where they ce- which covered the feniicircular eaft end of the church, 
 lebratedhismyfteries asfolemn feftivals; and they called and occupied the whole eailern arch of the great dome, 
 all other men profane, becaufo not admitted to thefe But when the dome was liniflicd, and had ftood a few 
 niyfteries. But their chief myfteries and mod inipor- months, it pufhcd the two eaftcrn piers with their but- 
 ' ■ . • ' > > trefTes from the perpendicular, making them lean to the 
 
 cdllward, and the dome and hall dome fell in. Il'idorus, 
 W'ho fucceeded to the charge on the death of Anthe- 
 raius, ftrengthened the piers on the call fide, by filling 
 up fome hollows, and again raifed the dome. But 
 
 tant fecrcts feem to be their mechanical and mathema- 
 tical fciences, or all that academical knowledge which 
 forms the regular education of a civil engineer. We 
 know that the temples of the gods and the theatres re 
 quired an immenfe apparatus of machinery for the cele- 
 
 1% 
 The art of 
 
 blli'tiiiii^ 
 arches un- 
 derftood in 
 
 bration of fome of their myfteries ; and that the Dio- things gave way before it was clofcd ; and while they 
 iiyfiacs contrafted for thofe jobs, even at far diftant were building in one part it was falling in in another, 
 places, where they had not the privilege of building the The pillars and walls of the eaftern femicircular end 
 edifice which was to contain them. This is the moft were much ihattered by this time. Ifidorus feeing that 
 likely way of explaining the very fmall quantity of m.e- they could give no refinance to the pufli which was fo 
 chanical knowledge that is to be met with in the wri- evidently direfted that way, erefted fome clumfy but- 
 tings of the ancients. Even Vitruvius does not appear trcfies on the eaft wall of the fquare which furroundei 
 to have been of the fraternity, and fpeaks of the Greek the whole Greek crofs, and was roofed in with it, form- 
 architefts in terms of refpeft next to veneration. The ing a fort of cloifter round the whole. Thefe buttrefTes, 
 CoIUgium Murarioium, or incorporation of mafons at fpanning over this cloifter, leaned againft the piers of 
 Rome, does not feem to have fliared the fecrets of the the dome, and thus oppofed the thrufts of the great 
 Dionyfiacs. north and fouth arches. The dome was now turned 
 The art of building arches has been moft afiiduoufly for the third time, and many contrivances were adopted 
 cultivated by the aflbciated builders of the middle ages for making it extremely light. It was made ofFenfively 
 of the Chriftian church, both Saracens and Chriftlans, flat ; and, except the ribs, it was roofed with pumice 
 the middle 3'"^ '^"^y ^^^™ t° \\ii\e. indulged in it with fondnefs : ftone ; but, notwithftanding thefe precautions, the 
 ages they multiplied and combined arches without end, arches fettled fo as to alarm the architedls, and they 
 placing them in every poflible fituation. made all fure by filling up the whole from top to bottonx 
 Having ftudied this branch of the art of building with arcades in three ftoiies. I'he loweft arcade was very 
 with fo much attention, they were able to ereft the lofty, lupported by four noble marble columns, and thus 
 moft magnificent buildings with materials which a prefervcd, in fome meafuie, the church in the form of 
 1^ Greek or Roman architeA could have made little or a Greek crofs. The ftory above formed a gallery for 
 Better than no ufe of. There is infinitely more fcientific (liill dlf- the women, and had fix columns in front, fo that they 
 l>y t'i= played in a Gothic cathedral than in all the buildings did not bear fair on thofe below The third ftory was 
 Greeks and ^£ Q^eece and Rome. Indeed thefe laft exhibit very a dead wall filling up the arch, and pierced with three 
 little knowledge of the mutual balance of arches, and rows of fmall ill-fhaped windows. In this un workman- 
 are full of grofs blunders in this refpedt ; nor could like ftiape it has ftood till now, and is the oldeft church 
 they have refifted the fhock of time fo long, had they in the world; but it is an ugly mifhapen mafs, more re- 
 not been almoft folid maffes of ftone, with no more ca- fenabling an overgrown potter's kiln, furrounded with 
 vity than was indifpenfably ncceffary. furnaces pieced and patched, than a magnificent temple, 
 Anthemius and Ifidorus, whom the Emperor Jufti- We have been thus particular in our account of it, be- 
 nian had felefted as the moft eminent architefts of caufe this hiftory of the building (hows that the ancient 
 
 14 
 
 Befea* of 
 the chur h 
 of St 
 
 of St Sophia Qreece for building the celebrated church of St Sophia architects had acquired no diftindl notions of the aflion 
 tL I" " at Conftantinople, feem to have known very little of of arches. Almoft any mafon of our time would know. 
 
 tinople. 
 
 :>ple; 
 
 this matter. Anthemius had boafted to Juftinian, that that as the fouth arch would pulh the pier to the eaft- 
 
 he would outdo the magnificence of the Roman pan- ward, while the eaft arch puftied it to the fouthward, 
 
 theon, for he would hang a greater dome than it aloft the buttrefs which was to withftand thefe thrufts muft 
 
 in the air. Accordingly he attempted to raife it on not be placed on the fouth fide of the pier, but on the 
 
 the heads of four piers, diftant from each other about fouth-eaft fide, or that there muft be an eaftern as well 
 
 J 15 feet, and about the fame height. He had probably as a fouthern buttrefs. No fuch blunders are to be feen 
 
 Such as an 
 never foun 
 in a Gothi 
 
 church. 
 
 \
 
 i6 
 
 ARC [ I 
 
 in « Gothfc calliedral. Some of them appear, to a care- 
 lefs fpeftator, to be very maffive and clumfy ; but when 
 jiidlcioufly examined, they will be found very bold and 
 light, being pierced in every direftion by arcades, and 
 the walls are divided into cells like a honeycomb, fo 
 that they are very lliff, while they are very light. 
 
 About the middle, or rather towards the end, of lad 
 century, when the Newtonian mathematics opened the 
 road to true mechanical fcience, the conflrnftion of 
 archescngroffed the attentionof the firllmalhematicians. 
 DrHookc'sThc tirft hint of a principle that we have met with is 
 principle of Dr Hooke's affcrtion, that the figure into which a ciiain 
 arches ^^ rope, perfedly flexible, will arrange itfelf when fuf- 
 pended from two hooks, is, when inverted, the proper 
 form for an arch compnfed of ftonesof uniform weight 
 This he affirmed on the fame principle which is made 
 ufe of in the Encyclopaedia Britannica in the article 
 Roof, § 25. viz. that the figure wliicli a flexible fef- 
 toon of heavy bodies alTumes, when fufpended from two 
 points, is, when inverted, the proper form for an arch 
 of the fame bodies, touching each other in the fame 
 points ; becaufe the forces with which they mutually 
 prefs on each other in this laft cafe, are equal and op- 
 pofite to the forces with which they pull at each other 
 in the cafe of fufpenfion. 
 
 This principle is ftriftly jull, and may be extended 
 to every cafe which can be propofed. We recofieft fee- 
 ing it propofed, in very general terras, in the St James's 
 Chronicle in 1759, when plans were forming for Black- 
 friar's Bridge in London ; and fince it is perhaps equal, 
 in practical utility, to the moft elaborate inveftigations 
 of the mathematicians, our readers will not be difpleafed 
 with a more particular account of it in this place. 
 Eipllmed, Let ABC (fig. 6.) be a parcel of magnets of any 
 fizc and fliape, and let us fuppofe that they adhere with 
 great force by any points of contaft. They will com 
 pofe fuch a flexible feiloon as we have been fpeaking 
 of, if fufpended from the points A and C. If this fi- 
 gure be inverted, preferving the fame points of contaft, 
 they will remain in equilibrio. It will indeed be that 
 kind of equilibrium which will admit of no difturbance, 
 and which may be called a tottering equilibrium. If the 
 form be altered in the fmallell degree, by varying the 
 points of contaft (which indeed are puints in the^^ur; 
 of equilibration), the magnets will no more recover their 
 former pofition than a needle, which we had made to 
 Hand on its point, will regain its perpendicular pofition 
 after it has been difturbed. 
 
 But if we fuppofe planes de,fg, hi, &c. drawn, that 
 the points of mutual contaft a, b, c, each bifefting the 
 angle formed by the lines that unite the adjoining con- 
 latts (fg, for example, bifefting the angle formed by 
 a b, be), and if we fuppofe that the pieces are changed 
 for others of the fame weights, b\it having flat fides, 
 which meet in the planes de,fg, hi, &c. it is evident 
 that we fhall have an arch of equilibration, and^that the 
 arch will have fome liability, or will bear a little change 
 of form without tumbling down : for it is plain that 
 the equilibrium of the original feftoon obtained only in 
 the points a, b, c, of contaft, where the preffures were 
 perpendicular to the touching furfaces; therefore if the 
 curve a, b, c, ftill paffes through the touching furfaces 
 perpendicularly, the conditions that are required for 
 equilibrium fl;ill obtain The cafe is quite fimilar to 
 that of the (lability of a body relling on a horizontal 
 SuppL. Vol. I. Part I. 
 
 Ar.'S. 
 
 7 ] ARC 
 
 plane. If the perpendicular through the centre of gra- 
 vity fails within the bale of the bbdy, it will not only *" 
 ftand, but will require fome force to purti it over. In 
 the original felloon, if a fmall weight be added in any 
 part, it will change the form of the curve of equilibra. 
 tion a little, by changing the points of mutual contaft. 
 This new curve will gradually feparate from the former 
 curve as it recedes from A or C. In like manner, when 
 the fciloon is fet up as an arch, if a fmall weight be 
 laid on any part of it, it will bring the whole to the 
 ground, becaufe the (hifting of the points of contaft 
 will be juft the contrary to what it fliould be to fuit 
 the new curve of equilibration. But if the fame weight 
 be laid on the fame part of the arch now conftruftcd 
 with flat joints, it will be fuftained, if the new curve of 
 equilibration IHII palfes through the touching furfaces. 
 
 Thefe conclufions, which are very obvioufly dedu- 
 cible from the principle of the teftoon, (hew us, without 
 any further dilcuflion, that the longer the joints are, 
 the greater will be the (lability of the arch, or that it 
 will require a greater force to break it down. There- 
 fore it is of the greatcll importance to have the arch 
 ftones as long as economy will permit; and this was the 
 great ufe of the ribs and other apparent ornaments in 
 the Gothic architefture. The great projeftionsof thofe 
 ribs augmented their ftiffnefs, and enabled them to fup- 
 port the unadorned copartments of the roof, compofed 
 of very fmall Hones, fcldom above fix inches thick. 
 Many old bridges are dill remaining, which are ftrength- 
 ened in the fame way by ribs. 
 
 Having thus explained, in a very familiar manner, 
 the liability of an arch, we proceed to give the fame 
 popular account of the general application of the prin- 
 ciple. _ _ ,8 
 
 Suppofe it to be required to afcertain the form of an And ap. 
 arch which fliall have the fpan AB (fig. 7.), and theplied. 
 height F 8, and which (hall have a road-way of the di- 
 menfionsCDE above it. Let the figure ACDEB be 
 inverted, fo as to form a figure KedeV). Let a chaia 
 of uniform thicknefs be fulpended from the points A 
 and B, and let it be of fuch a length that its lower 
 point will hang at, or rather a little below, f, corre- 
 fponding to F. Divide AB into a number of equal 
 parts, in the points 1, 2, 3, &c. and draw vertical lines, 
 cutting the chain in the correfponding points 1, 2, 3, 
 Sec. Now take pieces of another chain, and hang them 
 on at the points 1,2,^, &c. of the chain A/B. This 
 will alter the form of the curve. Cut or trim thefe 
 pieces of chain, till their lower ends all coincide with 
 the inverted road-way eil e. The greater lengths that 
 are hung on in the vicinity of A and B will pull down 
 thefe points of the chain, and caufe the middle pointy 
 (which is lefs loaded) to rife a little, and will bring it 
 near to its proper height. 
 
 It is plain that this procefs will produce an arch of 
 perfeft equilibration ; but fome farther confiderations 
 are neceflfary for making it exaftly fuit our purpofe. 
 It is an arch of equilibration for a bridge, that is fo 
 loaded that the weight of the arch-dones is to the 
 weight of the matter with which the haunches and 
 crown are loaded, as the weight of the chain A/B is 
 to the fum of the weights of all the little bits of chaia 
 very nearly. But this proportion is not known before- 
 hand ; we mud therefore proceed in the following man- 
 ner : Adapt to the curve produced in this way a thick- 
 C neff
 
 ARC 
 
 [ i8 ] 
 
 ARC 
 
 Arch. 
 
 '9 . 
 
 The chief 
 
 defea of 
 the curve 
 found ac- 
 cording Vt 
 this prin- 
 ciple. 
 
 ticTsof theareh-ftones as great as are tlioiiglit fnflicient to 
 enfurc (lability ; then compute the weight of the arch 
 ftones, and the weight of the gravel or rubbifh with 
 ■which the haunches are to be filled up to the rOad-way. 
 Jf the proportion of thefc two weights be the fame with 
 the proportion of the weights of chain, we may reft fa- 
 tisfied with the curve now found ; but if different, we 
 can calily calculate how much mull be added equal to, 
 or taken from, each appended bit of chain, in order to 
 make the two proportions equal. Having altered the 
 appended pieces accordingly, we (hall get a new curve, 
 which may perhaps require a very fmall trimming of 
 the bi's of chain to make them (it the road-way. 'ihis 
 curve will be iniinitely near to the curve wanted. 
 
 We have praftifed this method for an arch of 62 
 feet fpan and it feet height, the arch-llones of which 
 were only two feet nine inches long. It was to be 
 loaded with gravel and fhivers. We made a previous 
 computation, on the fuppofition that the arch was to 
 be nearly elliptical. The didance between the points 
 J, 2, 3, &c. were adjufted, fo as to determine the pro- 
 portion of the weights of chain agreeable to the fuppo- 
 fition. The .curve differed coniiderably from an ellipfe, 
 making a confiderable angle with the vertlcles at the 
 fprirg of the arch. The real proportion of the weights 
 of chain, when all was trimmed fo as to fuit the road- 
 way, was confiderably different from what was expect- 
 ed. It was adjulled. The adjuRment made very little 
 change in the curve. It would not have changed it 
 two inches in any part of the real arch. When the 
 procefs was completed, we conllruilcd the curve ma- 
 thematically. It did not differ fenfibly from this mecha- 
 nical con(lrui£lion. This was vei-y agreeable informa- 
 tion ; for it (hewed us that the firft curve, formed by 
 about two hours labour, on a fuppofition confiderably 
 different from the truth, would have been fufficiently 
 exaft for the purpofc, being in no place three inches 
 from the accurate curve, and therefore far within the 
 joints of the intended arch-llones. Therefore this pro- 
 cefs, which any intelligent mafon, though ignorant of 
 mathematical fcience, may go through with little 
 trouble, will give a very proper form for an arch fub- 
 jeCl to any conditions. 
 
 The chief defeft of the curve found in this way is a 
 want of elegance, becaufe it does not fpring at right 
 angles to the horizontal line ; but this is the cafe with 
 all curves of equilibration, as we fhall fee by and by. It 
 is not material: for, in the very neighbourhood of the 
 piers, we may give it any form we pleafe, becaufe the 
 mafonry is folid in that place ; nay, we apprehend that 
 a deviation from the curve of equilibration is proper. 
 The conflruflion of that curve fuppofcs that the pref- 
 fure on every part of the arch is vertical ; but gravel, 
 rarth, and rubbilh, exert fomewhat of a hydroilatical 
 prefTure laterally in the ail of fettling, and retain it 
 afterwards. This will require fome more curvature at 
 the haunches of an arch to balance it ; but what this 
 lateral prefTure may be, cannot be deduced with confi- 
 dence from any experiments that we have feen. We 
 are inclined to think that if, inllead of dividing the ho- 
 rizontal line AB in the points i, 2, 3, &c. we divide 
 the chain itfclf into equal parts, the curve will ap- 
 proach nearer to the proper form 
 
 After this familiar ftatement of the general principle, 
 it is now time to confider the theory founded on it 
 
 more in detail. This theory aims at fuch an adjuft- Arch, 
 ment of the pofition of the arcii-dones to the load on ——v— ' 
 every part of the arch, that all (hall remain in cquili-.j-, ^^° 
 brio, although the joints be perfcAly polifhed, and with- founded ok 
 out any cement. The whole may be reduced to two tliis i>rin. 
 problems. The firft is to determine the vertical pref-'^T''* 
 fure or load on every point of a line of a given form, 
 which will put that line in equilibrio. The fecond is 
 to determine the form of a curve which (liall be in equi- 
 librio when loaded in its different points, according to 
 any given law. 
 
 The whole theory is deducible from § 2J. of the ar- 
 tide Roof. The fundamental propofition in that fec- 
 tion dates the proportions between the various prelfures 
 or thrulls which are exerted at the angles of an aflem- 
 blage of beams or other pieces of folid heavy matter, 1 
 
 freely moveable about thofe angles, as fo m.any joints, ( 
 
 but retaining th^ir pofition by the equilibrium of thofe >' 
 
 prelTures. It is there demondrated, " that the thruft '■ 
 
 at any angle, if edijnated in a horizontal direflion, is 
 the fame throughout, and may be reprefcnted by any ho- 
 rizontal lineBT.fig.S. ( Roofs, fig. 10 Pl.CCCCXL)s 
 and that if a vertical line Ql^S be drawn through T, 
 the thruft exerted at any angle D by the piece CD, in 
 its own direction, will then be reprefcnted by BR, 
 drawn parallel to CD ; and in like manner, that the 
 thruft in the direiftion ED is reprefcnted by BS, &c.; 
 and, ladly, that the vertical thrulls or loads, at each 
 angle B, C, D, by which all thefe others prefTures are 
 excited, are reprei^ented by the portions QC, CR, RS, 
 of the vertical intercepted by thofe lines ; that is, all 
 thefe preffures are t9 the uniform horizontal thrud as 
 the lines which rtprefent them are to BT. The hori- 
 zontal thrud, therefore, is a very proper unit, with 
 which we may compare all the others. Its magnitude 
 is eafily deduced from the fame propofition ; for QS is 
 the fum of all the vertical preflures of the angles, and 
 therefore reprefents the weight of the whole affem- 
 blage. Therefore as QS is to BT, fo is the weight 
 of the whole to the horizontal thrud. n , 
 
 To accommodate this theory to the conftruftion of ^""n"""^ 
 a curvilineal arch vault, let us fird fuppofe the vault to'''''"i^ *°''*' 
 be polygonal, compofed of the cords of the elementary ..jy',, ^f ^„ 
 arches. Let AVE (fig. 9.) be a curvilineal arch, ofarch vaultj, 
 which V is the vertex, and VX the vertical axis, which i 
 
 we fhall confider as the axis or abfcilTa of the curve, 
 while any horizontal line, fuch as HK, is an ordinate 
 to the curve. About any point C of the curve as a 
 centre defcribe a circle BED, cutting the curve in B 
 and D. Draw the equal cords CB, CD. Draw alfo 
 the horizontal line CF, cutting the circle in F. De- 
 fcribe a circle BCDQ__paffing through B, C, D- Its 
 centre O will let in a line COQ_^ which bifedls the 
 angle BCD ; and C d, which touches this circle in C, 
 will bifedl the angle bCd, formed by the equal cords 
 BC, CD. Draw CLP perpendicular to c b, and DP 
 perpendicular to CD, meeting CL in P. Tbrougli L 
 draw the tangent GLM, meeting CD in G, and the 
 vertical line CM in M. Draw the tangent F a, cutting 
 the cords BC, CD, in b and d, and the tangent to the 
 circle BCDQjn c. Ladly, draw <^/ N parallel to be. 
 
 From what is demondrated in § 27. of lie article 
 Roof, it appears, that if BC, CD be two pieces of an 
 equilibrated heavy polygon, and if CF reprefent the ho- 
 rizontal thruft in every angle of the polygon, C d and 
 
 Cb
 
 ARC [ 
 
 Arch. C b will fcverally rcprcfciit the thruHs exerted by the 
 — V— 'piecL's DC, BC, and that Id, or CN, will reprefciit the 
 weiiJ-ht lying on the angle liCD, by which tlujfe thrufts 
 are balanced. 
 
 As the reader may not have the article Roof at 
 hand, this equilibrium may be recalled to his remem- 
 brance in the following manner : Produce c/C to o, io 
 that Co may be equal to C./. Draw bn to the verti- 
 cal parallel to dV>, and join no. It Is evident that 
 inoC is a parallelogram, and that «C ( = ^(/) := CN. 
 Now the thrufi. or fupport of the piece BC is exerted 
 I'n-the direftion Ct, while that of DC is exerted in the 
 diretUon Co. Thefe two thrulls are equivalent to the 
 thruft In the diagonal Cn ; and It is with this com- 
 pound ihruft tliat the load or vertical prelTure CN Is 
 in immeiliate equilibrium. 
 
 Becaufe iCL, NCF, are right angles, and FCL is 
 common to both, the aiigks 3CF and MCL are equal. 
 Therefore the right angled triangles iCF and MCL 
 are finiilar. And fmce CF is equal to CL, cb is equal 
 to CM. It Is evident that tlie triangles GCM and 
 ^CN are fimilar. Therefore CG : C ^/ = CiNI : CN, 
 
 CbXCJ 
 -Qb:Cn. Therefore we have CN = —gQ- . But 
 
 becaufe CDP and CLG are right angles, and therefore 
 C([Uil, and the angle GCP Is common to the two tri- 
 angles GCL, PCD, and CD Is equal to CL, we have 
 
 CbxCd 
 CG equal to CP. Therefore CN = ^p . Alfo, 
 
 fince CDP Is a right angle, DP meets the diameter in 
 
 (3 , the oppofite point of the circumference, and the 
 
 angle DQC is equal to DCd, or DC^ (becaufe bCd 
 
 is bifefted by the tangent), that is, to PCQ^ (becaufe 
 
 the right angles ^CP, cDO are equal, and cDP Is 
 
 common). Therefore PQ_^Is equal to PC ; and If PO 
 
 be drawn perpendicular to CQ__, it will bifeCl It, and O 
 
 is the centre of the circle BCDQB. 
 
 Now let the points B and D continually approach to 
 
 C (by diminifhlng the radius of the fmall circle), and 
 
 ultimately coincide with It. It is evident that the 
 
 circle BCDQ__is ultimately the equlcurve circle, and 
 
 that PC ultimately coincides with OC, the radius of 
 
 curvature. Alfo C b XC d becomes ultimately C c'. 
 
 Therefore CN, the vertical load on any point of a 
 
 Ct'' 
 
 curve of equilibration, is =: 
 
 Rad. Curv. 
 
 It Is farther evident, that CF is to Cc as radius to 
 the fecant of the elevation of the tangent above the ho- 
 rizon. Therefore we have the load on any point of 
 
 .,, , .• 1 . Sec' Elev. 
 
 the curve always proportional to — 
 
 Rad. Curv. 
 
 This load on every elementary arch of the wall Is 
 commonly a quantity of folld matter Incumbent on that 
 element of the curve, and prefiing it vertically; and it 
 may be conceived as made up of a number of heavy 
 lines Handing vertically on it. Thus, if the element 'Ee 
 of the curve were lying horizontally, a little parallelo- 
 gram RE(?r Handing perpendicularly on It, would re- 
 prefent its load. But as this element E e has a floping 
 pofition, it is plain that, in order to have the fame 
 quantity of heavy matter prefiing it vertically, the 
 height of the parallelogram muil be Increafed till it 
 meets in s p, the line R t drawn parallel to the tangent 
 EG. It is evident that the angle REp is equal to the 
 
 Aich, 
 
 «1 
 
 19 ] ARC 
 
 angle AEG. Therefore we have ER : Ep := Rad. : 
 Sec. Elev. ' 
 
 If therefore the arch is kept in equillbrio by the ver- 
 tical prellurc of a wall, we mud have the height of the 
 
 wall above any point proportional to - ^!iI^-1^.1l. 
 
 Rad. of Curv. 
 Cor. I. If OS be drawn perpendicular to the verti- Corollaries, 
 cal CS, CS will be half the vertical cord of the equl- 
 curve circle. I'he angle OCS is equal to ^rCF, that Is, 
 to the angle of elevation. Therefore 1 : .Sec. Elev. 
 = CS : CO, and the fecant of elevation may be expref. 
 . , , CO . C05 
 
 fed by -p^, and its cube by -^^rj. Thereforethe height 
 
 f 11 • .- 1 . C03 CO' 
 
 or wall is proportional to _-_ — _ — , or to ^, or 
 
 CS^XCO C S •* 
 
 CO' Sec' of Elev. 
 
 CS'XCS' °^ ° Vert. Cord of Curv. 
 
 Cor. II. If we make the arch VC =: z, the abfcIflU 
 VH = .v, the ordinate TrLC^zy, the radius ofculi CO = /-, 
 and the 4 vertical cord CS = .r, the height of wall pref- 
 
 fing on any point Is proportional to -^; or to -: — , or 
 Therefore, when the equation of the curve 
 
 «'+y' 
 
 y f . . ^_ 
 
 is given, and the height of wall on any one point of it 
 is alfo given, we can determine it for any other point; 
 for the equation of the curve will always give us the re- 
 lation of z, X, and ji, and the value of r or s. This may 
 be iUuftrated by an example or two. For this purpofc 
 it will generally be moil convenient to affume the height 
 above the vertex V for the unit of computation. The 
 thicknefs of the arch at the crown is commonly deter- 
 mined by other circumllances. At the vertex the tan- 
 gent to the arch Is horizontal, and therefore the cube 
 of the fecant Is unity or i. Call the height of wall, 
 at the crown, H, and let the radius of curvature in that 
 point be R, and Its half cord R (it being then coinci- 
 dent with the radius), and the height on any other 
 
 Z.5 
 
 point h. We have-jr- ; -^ = H : /i, and ^ = H X -r- 
 R. ySr y^ 
 
 R . i' R 
 
 X — . The other formula gives h = Hx -^X — . 
 
 Examp. I. Suppofe the arch to be a legment of afiuitrated 
 circle, as in fig. 10. where AE is the diameter, and O by exam- 
 the centre. In this arch the curvature is the fameP'^*- 
 
 R z3 
 
 throughout, or — = i. Therefore A =: H X ^-, or 
 
 y' 
 
 = H X Cube Sec Elev. 
 
 This gives a very fimple calculus. To the logarithm 
 of H add thrice the logarithm of the fecant of elevation, 
 The fum Is the logarithm of h. 
 
 It gives alfo a very fimple conftruftlon. Draw the 
 vertlcalCS, cutting the horizontal diameter In S. Draw 
 ST, cutting the radius OC perpendicularly In T. Draw 
 the horizontal line Ta, cutting the vertical In 2. Join 
 %o. Make C«= V'y, and draw ux parallel to zo. Cc 
 mud be made =: Car. The demonllration is evident. 
 
 It is very eafy to fee that if CV is an arch of 60°, 
 and Vu is -rjth of VC, the points v and c will be on 
 a level ; for the fecant of CV is twice CO, and there- 
 fore Cf is 8 times Vv, which is -yth of VH, 
 
 C 2 The
 
 ARC 
 
 [ 20 ] 
 
 ARC 
 
 Arch. Tlie dotted line r^i/ is drawn according to this 
 
 ""~^'~~~' calculus or conftruftion. It falls confiderably below 
 the horizontal line in the neighbourhood of c ;■ and 
 then, pafling very obliquely through (, it rifes rapidly 
 to an uniTieafurable lieight, becaiife the vertical line 
 through A is its aiTymptote. This muft evidently be 
 the cafe with ever\' ciiive which fprings at right angles 
 with a horizontal line. 
 
 It is plain that if ■uV be greater, all the other ordi- 
 nates of the cinve vg cf, relling on tlie circumference 
 AVE, will be greater in tlie fame proportion, and the 
 curve will cut the horizontal line drawn through v in 
 fonie point nearer to v than c is. Hence it appears 
 that a circular arch cannot be put in eqnilibno by 
 building on it up to a horizontal line, whatever be its 
 fpan, or whatever be the thicknefs at the crown. We 
 have feen that when this thicknefs is only ^Vth of the 
 radius, an arch of 120 degrees will be too much loaded 
 at the flanks. This thicknefs is much too fmall for a 
 bridge, being only ^V'h of the fpan CM, whereas it 
 fhould have been almoft double of this, to bear the in- 
 equalities of weight that may occafionally be on it. 
 When the crown is made ftill thinner, the outline is 
 ftill more deprelTcd before it rifes again. There is there- 
 fore a certain fpan, with a correfponding thicknefs at 
 the crown, which will deviate leail of all from a hori- 
 aontal line. This is an arch of about 54 degrees, the 
 thicknefs at the crown being about one-fouith of the 
 fpan, which is extravagantly great. It appears in ge- 
 neral, therefore, that the circle is not a curve fuited to 
 the purpofes of a bridge or an arcade, which requires 
 an outline nearly horizontal. 
 
 Examp. 2. Let the curve be a parabola AVE (fig. 11.), 
 cf which V is the vertex, and DG the direftrix. Draw 
 the diameters DCF, GVN, the tangents CK, VP, and 
 the ordinates VF and CN. It is well known that GV 
 .- is to DC as VP'- to CK% or as CN^ to CiO. Alfo 
 
 3 GV is the radius of the ofculating circle at V, and 
 3 DC is one-half of the vertical cord of the ofculating 
 circle at C. Therefore CN' : CK^ (ory :i,^) = K:s, 
 
 ' t -y * R 
 and J = ^ R. But Cc, or A = H X -. . Therefore 
 
 The convcrfe of the problem, namely, to find the Arch. 
 form of the arch when the figure of the b.ick of it is ~"^ "^ 
 given, is the moft ufual queftion of the two, at lead in-p^^ ^^. i^ 
 cafes which are moll important and moft difficult. Of f,,rm of an 
 thcfe perhaps bridges arc the cliief. Here the neceffi-arcli when 
 ty of a road- way, of eafy and regular afcent, confines '^"^ ''S'"'* 
 us to an outhne nearly horizontal, to which the curve"' ''* ^^''^ 
 of the arch muft be adapted. This is the moft difficult 
 problem of the two ; and we doubt whether it can be 
 folved without employing infinite approximating fcrie- 
 fes inftead of accurate values. 
 
 Let ai)e (lig. 12.) be the intended outline or cx- 
 tra^los of the arch AVE, and let 7)Q_be the common 
 axis of both curves. From c and C, the correfponding 
 points, draw the ordinates ch, CH. Let the thicknefs 
 
 i)V at the top be a, the abfcifTa -uhhe = u, and VH 
 =: X, and let the equal ordinates c h, CH be y, and the 
 arch VC be 2. 
 
 Then, by the general theorem, cC zr -. — , ;• being 
 
 the radius of curvature. This, by tte common rules, is 
 
 Z5 
 
 y X — X y 
 
 This 
 
 gives 
 
 C = 
 
 y-- 
 
 ■X y 
 
 yi 
 
 X C ; where C is a conftant quantity, 
 
 found by taking the real value of cC in V, the vertex 
 of the curve. But it is evident that it is alfo = a + « 
 
 u. Therefore a -{- x — u =: 
 
 X 
 
 X fluxion of ^. 
 
 _ yx. 
 
 .xc;=5 
 
 h = Hx 
 
 R 
 
 ^ — R 
 
 = H X 
 
 R 
 
 H. Therefore 
 
 Cr = TV. 
 
 It follows from this inveftlgatlon, that the back or 
 extrados of a parabolic arch of equilibration muft be 
 parallel to the arch or foffit itfelf; or that the thicknefs 
 of the arch, eftimated in a vertical direAion, muft be 
 equal throughout ; or that the extrados is the fame pa- 
 rabola with the fofiit or intrados. 
 
 We have feleftcd thefe two examples merely for the 
 fimplicity and perfpicuity of the folutions, which have 
 been eifefted by means of elementary geometry only, 
 inftead of employing the analytical value of the radius 
 
 of the ofculatory circle, viz. — 
 
 If we now fubftitute the true value of a (which is 
 given, becaufe the extrados is fuppofed to be of a known 
 form), exprctTed in terms of j/, the refulting equation 
 will contain nothing but x and y, with their firft and 
 fecond fluxions, and known quantities. From this equa- 
 tion the relation of.x-andjmuft be found by fuchmethods 
 as feem beft adapted to the equation of the extrados. 
 
 Fortunately the protefs is more fimple and eafy in 
 the moft common and ufeful cafe than we fhould ex- 
 peft from this general rule. We mean the cafe where 
 the extrados is a ftraight line, efpecially when this is 
 horizontal. In this cafe u is equal to 0. 
 
 Example. To find the form of the balanced arch 
 AVE (fig. 13-)) having the horizontal line cv for its 
 extrados. 
 
 Keeping the fame notation, we have u =z 0, and 
 
 C . . r* 
 therefore a + x =— X fluxion of r-. 
 
 y y 
 
 C 
 
 Aflume V = — ; then — = », and t- X fluxion of -r , 
 
 _ ■" y , y y 
 
 Cvv , , Cvv T,, r • . • 
 
 =: — — , that IS a + x = — : — 1 heretore ax + xx 
 
 yx — xy 
 have involved us at leaft in the elements of fecond 
 fluxions. We have alfo preferred fimplicity to ele- 
 gance in the inveftigation, becaule we wifh to inftrudl 
 the pra£lical enginee;, who may not be a proficient in 
 the higher mathematics. 
 
 -^, which would —C-u'-o; and by taking the fluents, we have 2a«+x* 
 
 y2 a X + x^ 
 p . Conlequently, 
 
 = C 
 
 and 
 
 9-=— I being =— 1. 
 
 of this, we have y =z ^ C 
 
 Taking the fluent 
 X L {2 ax + 2 x»
 
 ARC 
 
 [ " 
 
 J^ i \/ 2ax + X-). But at the vertex, where x = o, 
 'we havey = v^ C X L (2a). The correfted fluent is 
 
 therefore v = v' C X L — ' 
 
 ,1 
 
 It only remains to find the conftant quantity C. 
 This we readily obtain by felefting Come point of the 
 cxtrados where the values of x and y are jjiven by par- 
 ticular circumftaiices of the cafe. Thus, whcji the 
 fpan 2 s and height li of the arch a rc gi ven, we liave 
 
 quentlyv'C=: 
 
 
 — j, and confe- 
 Therefore 
 
 the general value ofyzzs X 
 
 / fl + « + \/2 ax_+_ 
 
 XL 
 
 'a -\-h -\- >/ 2a Ij -J- h 
 
 
 
 a 
 As an example of the ufe of this formula, we fubjoin 
 » table calculated by Dr Hutton of Woolwich for an 
 arch, the fpan of which is i oo feet, and the height 40; 
 whicli are nearly the dimenfions of the middle arch of 
 Blackfriars Bridge in London. 
 
 y 
 
 X 
 
 y 
 
 X 
 
 y 
 
 K 
 
 
 
 6,000 
 
 21 
 
 10,381 
 
 ^6 
 
 2'.774 
 
 2 
 
 6.035 
 
 22 
 
 10,858 
 
 37 
 
 22,948 
 
 4 
 
 6,144 
 
 23 
 
 11,368 
 
 3« 
 
 24,190 
 
 6 
 
 6,324 
 
 24 
 
 1 1,911 
 
 39 
 
 25.505 
 
 8 
 
 6,580 
 
 2<, 
 
 12,489 
 
 40 
 
 26,894 
 
 10 
 
 6,914 
 
 26 
 
 13,106 
 
 4' 
 
 28,364 
 
 12 
 
 7.i.^o 
 
 27 
 
 13,761 
 
 42 
 
 29,919 
 
 r^ 
 
 7'37i 
 
 28 
 
 14.457 
 
 43 
 
 31.563 
 
 '4 
 
 7.Si34 
 
 29 
 
 15. '96 
 
 44 
 
 33.299 
 
 I? 
 
 8,i20 
 
 30 
 
 15,980' 
 
 45 
 
 35. '35 
 
 16 
 
 8,430 
 
 31 
 
 i6,8ii 
 
 46 
 
 37.'^75 
 
 17 ■ 
 
 8,766 
 
 32 
 
 17.693 
 
 47 
 
 39,126 
 
 18 
 
 9,168 
 
 33 
 
 18. 627 
 
 48 
 
 41.293 
 
 19 
 
 9.5 '7 
 
 34 
 
 19,617 
 
 49 
 
 43.581 
 
 20 
 
 9.934 
 
 .^5 
 
 20,665 
 
 50 
 
 46,000 
 
 The figure for this propofition is exaftly drawn ac- 
 cording to thefe dimenfions, that the reader may judge 
 of it as an objeft of fight. It is by no means deficient 
 in gracefulnefs, and is abundantly roomy for the paffage 
 of craft ; fo that no objedllon can be offered againft its 
 ,, being adopted on account of its mechanical excellency . 
 efefls of The reader will perhaps be furprifed that we have 
 eCatcm made no mention of the celebrated Catenarian curve, 
 »n curve, which is commonly faid to be the bell form for an arch ; 
 but a little refleftlon will convince him, that although 
 it is the only form for an arch confilting of ftones of 
 equal weight, and touching each other only in fingle 
 points, it cannot fuit an arch which mult be filled up in 
 the haunches, in order to form a road-way. He will 
 .be more furprifed to hear, atter this, that there is a 
 certain thicknefs at the crown, which will put the Ca- 
 tenaria in equilibrio, even with a horizontal road-way ; 
 
 Arch, 
 
 17 
 
 theory 
 
 ] ARC 
 
 but this thicknefs is fo great as to make it unfit for a 
 bridge, being fuch that the preffure at the vertex is *■ 
 equal to the horizontal thruft. This would have been 
 about 37 feet in the middle arch of Blackfriars Bridge. 
 The only fituation, therefore, in which the Catenarian 
 lorm would be proper, is an arcade carrying a lieight of 
 dead Wall ; but in this fituition it would be very un- 
 graceful. Without truubh'iig the reader with the in- 
 velligation, it is fufficient to inform him that in a Ca- 
 tenarian arch of equilibrati'jn the abfcilTa VH is to the 
 abfciffd V h in the conltant ratio of the horizontal thrull 
 to its exccfs above the prcflTure on- the vertex. 
 
 This much will ferve, we hope, to give the reader alnutil'tj- of 
 clear notion of this celebrated theory of the equilibrium'*'' '="'"- 
 of arches, one of the moft delicate and important appli.'^''' .'5'^ 
 cations 01 mathematical Icience. Volumes have been Oration, 
 written on the fubjedt, and it Hill occupies the atten- 
 tion of mechanicians. But we beg leave to fay, with 
 great deference to the eminent perlons who have profe- 
 cuted this theory, that their fpeculat ions have been of 
 little fervice, and are little attended to by the pradi- 
 tioner. Nay, we raay add, that Sir Chrillopher Wren, 
 perhaps the moft accomplilhed archited that Europe 
 has leen, fcems to have thought it of little value : for, 
 among the fragments which have been prefcrvtd of his 
 ftudies, there are to be feen fome imperfcd differtations 
 on this very fubjedf , in which he takes no notice of this 
 theory, and confiders the balance of arches in quite an- 
 other way. Thefe are coUetied by th.e author of the 
 account of Sir Chriftophcr Wren's family. This man's 
 great fagacity, and his great experience in building, and, 
 ftlU more his experience in the repairs of old and crazy 
 fabrics, had (hewn him many things very inconfiftentr 
 with this theory, which appears fo fpecious and fafe.' 
 The general fads which occur in tlie failure of old 
 arches are highly inftruttive, and deferve the moll care- 
 ful attention of the engineer; for it is in this Hate that 
 their defefts, and the procefs of nature in their dcllruc- 
 tion, are moft diftindly fcen. We venture to alfirm,. 
 that a very great majority of thefe fads are irreconcile- 
 abie to the theory. The way in which circular arches 
 commonly fail, is by the finking of the crown and the 
 rifing of the flanks. It will be found by calculation, 
 that in moft of the cafes it ought to have been jutl the 
 contrary. But the deareft proof is, that arches very 
 rarely fail where their load differs moll remarkably from 
 that which this theory allov.'s. Semicircular arches have 
 ftood the power of ages, as may be feen in the bridges 
 of ancient Rome, ai:d in the numerous arcades which 
 the ancient inhabitants have ereded. Now all arches 
 which Ipring perpendicularly from tlie horizontal line, 
 require, by this theory, a load of infinite height ; and, 
 even to a confiderable diftance from the fpringino- of 
 the arch, the load neccffary for the theoretical equili- 
 briura is many times greater than what is ever laid on 
 thofe parts ; yet a failure in the immediate neighbour- 
 hood ol the fpring of an arch is a moil rare phenome- 
 non, if it ever was obferved. Here is a moll remark- 
 able deviation from the theory ; for, as is alreadv ob- 
 ferved, the load is frequently not the fourth part of 
 what the theory requires. 
 
 Many other fads might be adduced which /hev» great 
 deviations from the legitimate refults from the theory. 
 We hope to be excufed, therefore, by the mathcmati- 
 ciajis for doubting of the juftnefs of this theory. We 
 
 dor
 
 ARC [2 
 
 do not tliink it erroneous, but dcfeflivc, leaving out 
 circumftanccs which we apprehend to be of great im- 
 \ti dtftfts. po"^"'^'-' i ^"^ "'"^ imagine that the dcfefts of the theory 
 have arifen from the very anxiety of the mechanicians 
 to make it perfei't. The arch-ilones are fuppofed to 
 be perfeftly fmooth or pohlhed, and not to be connect- 
 ed by any cement, and therefore to fullain each other 
 merely by the equihbrium of their vertical preffnre. 
 The theory enfures this equilibrium, and this only, 
 leaving unnoticed any other caufcs of mutual aciion. 
 
 The authors who have written on the fubjeft fay ex- 
 prefsly, that an arch which thus fuftains itfclf muft be 
 flronger than another which would not ; becaufe when, 
 in imagination, we fuppofe both to acquire connexion 
 by cement, the firft prcferves the influence of this con- 
 nection unimpaired ; whereas in tlie other, part of the 
 coheiiou is walled in coiniteraCting the tendency of 
 fome parts to break ofl^ from the reil by their want of 
 equilibrium. This is a very ipecious argument, and 
 ■wouhi be juft, if the forces which are mutually exerted 
 between the parts of the arch in its fettled ilate were 
 merely vertical prelTures, or, where different, were in- 
 confiderable in comparifon with thofe which are really 
 attended to in the conftruftion. 
 
 But this is by no means the cafe. The forms which 
 the ufes for which arches are erefted oblige us to adopt, 
 and the loads laid on the different points of the arch, 
 frequently deviate conliderably from what are neceffary 
 for the equilibrium of vertical preffures. The varying 
 load on a bridge, when a great wagon paffes along it, 
 fometimes bears a very feniible proportion to the weight 
 of that point of the arch on which it rells. It is even 
 very doubtful whether the preffures which are occa- 
 fioned by the weight of the fluff employed for filling up 
 the flanks really aft in a vertical direftion, and in the 
 proportion which is fuppofed. We arc pretty certain 
 that this is not the cafe with fand, gravel, fat mould, 
 and many fubflances in very general ufe for this pur- 
 pofe. When this is the cafe, the preffures fuflained 
 by the different parts of the arch are often very iucon- 
 fiflent with the theory — a part of the arch is over- 
 loaded, and tends to fall in, but is prevented by the ce- 
 ment. This part of the arch therefore afts on the re- 
 moter parts by the intervention of the parts between, 
 employing thofe intermediate parts as a kind of levers 
 to break the arch in a remote part, jufl as a lintel would 
 be broken. We apprehend that a mathematician would 
 be puzzled how to explain the liability of an arch cut 
 out of a folid and uniform mafs of rock. His theory 
 conhders the mutual thrufls of the arch flones ao in the 
 direftion of the tangents to the arch. Why fo ? be- 
 caufe he fuppofes that all his polilhed joints are perpen- 
 dicular to thofe tangents. But in the prefent cafe he 
 has no exilling joints; and there feems to be nothing to 
 direft his imagination in the affuraption of joints, which, 
 however, are abfolutely neceffary for employing his 
 theory, becaufe, without a fuppofition of this kind, there 
 feems no conceiving anv mutual abutment of the arch 
 ftones. Aflc a common, but intelligent, mafon what 
 notion he forms of fuch an arch ? We apprehend that 
 he will confider it as no arch, but as a lintel, which 
 may be broken like a wooden lintel, and wdiich refills 
 entirely by its cohefion. He will not readily conceive 
 that, by cutting the under fide of a ftone lintel into an 
 arched form, and thus taking away more than half of 
 
 
 29 
 
 2 ] ARC '^1 
 
 its fubflancc, he has changed its nature of a lintel, or Arch. 
 given it any additional (Irength. Nor would there be 
 any change made in the way in which Inch a inafs of 
 flone would refill being broken down, if nothing were 
 done hut forming the under fide into an arch. If the 
 lintel he fo laid on the piers that it can be broken with- 
 out its parts pufliing the piers afide (which will be t!ie 
 cafe it it lies on the piers with horizontal joints), it w ill 
 break like any other lintel; but if the joints are direcl- 
 ed downwards, and converging to a point within tlie 
 arch, the broken flone (fuppofe it broken at the crown 
 by an overload in that part) cannot be prefl'ed down 
 without forcing the piers outwards. Now, in this mode 
 of afting, the mind cannot trace any thing of the fla- 
 tical equilibrium that-we have proceeded on in the 
 foregoing theory. The two parts of the broken lintel 
 feem to pulh the piers afide in the fame manner that 
 two rafters pufh outwards the walls of a houfe, when 
 their feet are not held together by a tie-beam. If the 
 piers cannot be pudied afide (as when the arch abuts 
 on two folid rocks), nothing can prefs down the crown 
 which does not crufli the flone. 
 
 This conclufion will be ftriftly true if the arch is oF 
 fuch a form that a fl:raight line drawn from the crown 
 to the pier lies wholly within the folid mafonry. Thus 
 if the vault confifl of two flraight flones, as in fig. r. 
 or if it confill of feveral flones, as in fig. 14. difpofed 
 in two flraight lines, no weight laid on the crown can 
 deflroy it in any other way but by crufliing it to pow- 
 der. 
 
 But when flraight lines cannot be drawn from the When it i 
 overloaded part to the firm abutments through the fo- f° ''^ ™" 
 lid mafonry, and when the cohefion of the parts is notof jdj 5;^ 
 able to withlland tlie tranfverfe flrains, we mufl call the der 
 principles of equilibrium to our aid; and in order to 
 employ them with fafety, we nuift confider how they 
 are modified by the excitement of the cohering forces. 
 
 The cohefion of the flones with each other by ce- 
 ment or otherwife, has, in almofl every fituation, a bad 
 effect. It enables an overload at the crown to break 
 the arch near the haunches, caufing thofe parts to rife, 
 and then to fpread outwards, jufl as a Manfarde or 
 Kirb roof would do if the trufs beam which connefts 
 the heads of the lower rafters were fawn through. This 
 can be prevented only by loading that part more than 
 is requifite for equilibrium. It would be prudent to do 
 this to a certain degree, becaufe it is by this cohefion 
 that the crown always becomes the weakell part of the 
 arch, and fuffers more by any occafional load. 
 
 We expect that it will be faid in anfwer to all this, 
 that the cohefion given by the flrongefl cement that 
 we can employ, nay, the cohefion of the flone itfelf, is 
 a mere nothing in comparifon v\'ith the enormous thrulls 
 that are in a Hate of continual exertion in the different 
 parts of au arch. This is very true; but there is an- 
 other force which produces the fame effett, and which 
 increafes nearly in the proportion that thofe thruitsin- 
 creafe, becaufe it arifes from them. This is the fridtion 
 of the flones on each other. In dry freeflone this fric- 
 tion confiderably exceeds one half of the mutual pref- 
 fure. The refledling reader will fee that this produces 
 the fame effeft, in the cafe under confideration, that 
 cohefion would do ; for while the arch is in the aft of 
 failing, the mutual preffure of the arch-flones is afting 
 with full force, and thus produces a friftion more than 
 
 adequate
 
 ARC [a 
 
 adequate to all the effefts we have been ipeaking 
 
 ■'of. , _ 
 
 When thefe circumftances are confidered, we imagine 
 that it will appear that an arch, when expofcd to a 
 great overload on the crown (or indeed on any purt), 
 divides, of itfcif, into a number of parts, each of which 
 contains as many arch-ftones as can be pierced (fo to 
 fpeak) by one ilraight line, and that it may then be 
 confidered as nearly in the fame fituation with a poly- 
 gonal arch of long (tones butting on each other like io 
 many beams in a Norman roof (fee Roof, n° 49.), but 
 without their braces and ties. It tends to break at all 
 thofe angles ; and it is not fufficiently relifted there, 
 becaufe the materials with which the flanks are filled 
 up have fo little coliefion, that the angle feels no load 
 except what is immediately above it ; whereas it fiiould 
 be immediately loaded with all the weight which is dif- 
 fufed over the adjoining fide of the polygon. This will 
 be the cafe, even though the curvilineal arch be per- 
 fectly equilibrated. We recolleft fome circumllances in 
 the failure of a confiderable arch, which may be worth 
 mentioning. It had been built of an exceedingly foft 
 and friable ftone, and the arch (tones were too (hort. 
 About a fortnight before it fell, chips were obferved 
 to be dropping off from the joints of the archftones 
 about ten feet on each fide of the middle, and alfo frorti 
 another place on one fide of the arch, about twenty 
 feet from its middle. The mafons in the neighbourhood 
 prognolllcated its fpeedy downfal, and faid that it 
 would feparatc in thofe places where the chips were 
 breaking off. At length it fell ; but it firlt fplit in 
 the middle, and about 15 or 16 feet on each fide, and 
 alfo at the very fpringing of the arch. Immediately 
 before the fall a fiiivering or crackling nolfe was heard, 
 and a great man}' chips dropped down from the middle 
 between the two places from whence they had dropped 
 a fortnight before. The joints opened above at thofe 
 new places above two inches, and in the middle of the 
 arch the joints opened below, and in about five minutes 
 after this the whole came down. Even this movement 
 was plainly diitingulihable into two parts. The crown 
 funk a little, and the haunches rofe very fenfibly, and 
 in this (tate it hung for about half a minute. The 
 arch (tones of the crown were hanging by their up- 
 per corners. When thefe fplintered off, the whole fell 
 down. 
 
 We apprehend that the procedure of nature was 
 fomewhat in this manner. Straight lines can be drawn 
 within the arch-ftones from A (fig. i ;.) to B and D, 
 and from thofe points to C and E. Each of the por- 
 tions ED, DA, AB, EC, rcfid as if they were of one 
 ftone, compofing a polygonal vault EDABC. When 
 this is overloaded at A, A can defcend in no other way 
 than by pufliing the angles B and D outwards, caufing 
 the portions BC, DE, to turn round C and E. This 
 motion mult raife the points B and D, and caufe the 
 arch-ftones to prefs on each other at their inner joints 
 i and </. This produced the copious fplintering at thofe 
 joints immediately preceding the total downfal. The 
 fplintering which happened a fortnight before arofe 
 from this circumftance, that the lines AB and AD, 
 along which the prelFure of the overload was propa- 
 gated, were tangents to the foffit of the arch in the 
 points F, H, and G, and therefore the (train lay all on 
 thofe corners of the archftones, and fplintered a little 
 
 3 ] ARC 
 
 from off them till the whole took a firmer bed. The 
 fubfequcnt phenomena arc evident confcqucnccs of this ' 
 diftribution and modification of preifure, and can hard- 
 ly be explained in any other way; at Icaft not on the 
 theoretical principles already fct forth : for in this 
 bridge the loads at B and D were very confiderably 
 greater than wh.at the equilibrium required ; and we 
 think that the firll obferved fplintering at II, F, and 
 G, was mo.ft inftruftive, (howing that there was an ex- 
 traordinary prelfure at the in.icr joints in thofe places, 
 whicli cannot be explained by the ufual theory. 
 
 Not fatisfied with this fingle obfervation, after this 
 way of explaining it occurred to us, and not bting able 
 to find any fimilar faCt on record, the writer of this ar- 
 ticle got fome fraall models of aiches executed in chalk, 
 and fubjefted them to many trials, in hopes of colleft- 
 ing fome general law? of the internal workings of arch- 
 es which finally produce their downfal. He had the 
 pleafure of obferving the above mentioned circumftan- 
 ces take place very regularly and uniformly, when he 
 overloaded the models at A. The arch always broke 
 at f ime place B confiderably beyond another point F, 
 where the firft chipping had been obferved. This is a 
 method of trial that dtferves the attention both of the 
 fpeculatift and the pradlitioner. 
 
 If thefe reflettions are any thing like a juft account 
 of the procedure of nature in the failure of an arch, it 
 is evident that the ingenious mathematical theory of 
 equilibrated arches is of little value to the engineer. 
 We ventured to fay as much already, and we refted a 
 good deal on the authority of Sir Chriftopher Wren. 
 He was a good mathematician, and delighted. in the api 
 plication of this fcience to the arts. He was a celebra- 
 ted architeft; and his reports on the various works 
 committed to his charge, (how that he was in the con- 
 tinual habit of making this application. Several fpe- 
 cimens remain of his own methods of applying them. 
 The roof of the theatre of Oxford, the roof of the cu- 
 pola of St Paul's, and in particular the mould on which 
 he turned the inner dome of that cathedral, are proofs 
 of his having ftudied this theory molt attentively. He 
 flourifhed at the very time that it occupied the attention 
 of the greateit mechanicians of Europe ; but there is. 
 nothing to be found among his papers which fliows 
 that he had paid much regard to it. On the contrary, 
 when he has occafion to deliver his opinion for the in- 
 ftruftion of others, and to explain to the Dean and 
 Chapter of Weftminfter his operations in repairing tliat 
 collegiate church, this great architeft confidcrs an arch 
 juft as a fenfible and fagacious mafon would do, and 
 very mucli in the way that we have juft now been treat- 
 ing it : (See Account of the Family of IVren, p. 356, 
 &c. ) Supported therefore by fuch authority, we would 
 recommend this way of confidering an arch to the ftudy 
 of the mathematician ; and we would defire the expe- 
 rienced mafon to think of the moft efficacious methods 
 for refifting this tendency of arches to rife in the flanks. 
 Unfortunately there feejns to be no precife principle to 
 point out the place where this tendency is molt re- 
 markable. 
 
 We are therefore highly pleafed with the ingenious 
 contrivance of Mr Mylne, the architeft of Blackfriars 
 Bridge in London, by which he determines this point 
 with precifion, by making it impoflible for the over- 
 loaded arch to fpring in any other place. Having thus 
 
 confined. 
 
 Arch.
 
 ARC 
 
 [ H 1 
 
 ARC 
 
 AitU. 
 
 "I 
 Cnnflruc- 
 t on of 
 Blackfiiar 
 
 confined the failure to a particular fpot, he with equal built up to their intended height, the thruft of the Arih, 
 art oppofi's a vefiftancc which he bclievea to lie fuffi- arches I'queezes the rubble-work horizontally, after the — >r«' 
 cient ; and the prefent condition of that noble briilge, mortar has let, but betore it has dried and acquired its 
 which does not in any place ihow the fmalleft change utnioll hardnefs. Its bond is broken by this motion, 
 of fliape, proves that he was not millaken. Looking and it is I'qneezed up, and never acquires its former 
 on this work as the full, or at lead the fecond, fpeci- firmnefs. This is effeftually prevented by tlie preffure 
 men of mafonic ingenuity that is to be feen in the exerted by the back of the invert, d arch, 
 world, we imagine that our readers will be pleafcd with Above this counter arch is another niafs of courfed 
 a particuUr account of its moll remarkable circura- rubble, and all is covered by a horizontal conrle of large 
 j^3j,j,gj_ blocks of Portland ftone, buttuig againil the back of 
 
 The fpan ha (fio-. i6.) of ihe middle arch is lOO the arch-ftone ZI and its correfponding one in the ad- 
 feet, and its iieij;hrOV is 40, and the thickncfs KV joining arch. This courle conneds the feet of the two 
 of the crown is lix feet feven inches. Its form is nearly arches, preferves the rubble-work irom too great com- 
 'j?iate'lll. elliptical; the part AVZ being an arch of a circle prcffion, and proteds it from u. ikiog water. Tl.is la(t 
 whofe centre is C, and radius 56 feet, and the two la- circumltance is iniportant; for if the water which falls 
 tcral portions A /■ B and Z a E being arches defcribed on the road- way is not carried iff in pipes, it foaks 
 with a radius of ^ 5 feet nearly. The thicknels of the through the gravel or other rubbifh, rcfts on the mor- 
 pier at rt * is 19" feet. The thicknefs of the arch in- tar, and keeps it continually wet and loft. It cannot 
 creafes from the crown V to Y, where it is eight or efcape through the joints of g(/od n^afonry, and there- 
 nine feet. All the arch-ftones have their joints direded fore fills up this part like a funnel, 
 to the centres of their curvature. The joints are all Suppofing the adjoining arch fallen, and all tumbled 
 
 'jojTjrled, haviug a cubic foot of hard ftone let half way off that is not withheld by its fituation, there will ftiH 
 into each. B)^this contrivance the joints cannot Aide, remain in the pier a mafs of about 3^02 tons. The 
 nor can any weight laid on the crown ever b;eak the weight of the portion VY is about 2000 tons. The 
 arch in that part, if the piers do not yield ; for a diredions of the thrults RY and YF are fuch, that it 
 ftraight line from the middle of KV to the middle of would require a load of 4500 tons on VY to overturn 
 the ioint YI is contained within the folid mafonry, and the pier round F. This exceeds VY by 2500 tons; a 
 does not even come near the inner joints of the arch- weight incomparably greater than any that can ever be 
 ftones. iherefore the whole rclifts like one (lone, and laid on it. 
 
 can be broken only by cruthing it. The joint at Z is Such is the ingenious conftrudion of Mr Mylne. ft 
 ■very nearly perpendicular to a line YF drawn to the evidently proceeds on the principles recommended 
 outer edge of the foundation of the pier. By this it above ; principles which have occurred to his experience 
 was intended to take off all tendency of the preffure on and fagacious mind during the courfe of his extenfive 
 the joint rfZ to overfet the pier ; for if we fuppofe, ac- pradice. We have leen attempts by other engineers 
 cording to the theory of equilibration, that this preffure to withftand the horizontal thrufts of the arch by- 
 is neceffarily exerted perpendicularly to the joint, its means of counter arches inferted in the fame maimer 
 diredion paffes through the fulcrum at F, round which as here, but extending much farther over the main arch; 
 it is thought that the pier mull turn in the ad of over- but they did not appear to be well calculated for pro- 
 fetting. This precaution was adopted in order to make ducing this effed. A comiter arch fpringing from any 
 the arch quite independent of the adjoining arches ; lo point between Y and V has no tendency to hinder that 
 that although any of them Ihould fall, this arch iliould point from rifing by the linking of the crown ; and 
 run no riflt. {ach. a counter arch will not refill the precilely hori- 
 
 Still farther to fecure the independence of the arch, zontal thruft fo well as the ftraight courfe of Mr iilylne. 
 the following conftrudion was pradifed to unite it into _ _ _ . . .3* ' 
 
 one mafs which ftiould rife altogether. All below the The great incorporation of architeds who built the 0"K'n o 
 line fl^ is built of laro-e blocks of Portland ftone, dove- cathedrals of Europe departed entirely from the ftyles '", 
 tailed with found oak. Four places in each courfe are of ancient Greece and Rome, and introduced another, 
 interrupted by equal blocks of a hard ftone called Ken- in which arcades ijnade the prirtcipal part. Not finding 
 /»/Z) rax, funk half way in each courfe. Thefe ad as in every place quarries from which blocks could be 
 ioaeles breaking the courfes, and preventing them raifed in abundance of fuffic lent lize for forming the far- 
 from Hiding laterally. projeding corniches of the Greek orders, they relin- 
 
 The portion a Y of the arch is joggled like the up- quilhed thofe proportions, and adopted a ftyle of orna- 
 nerpart. The interior part is filled up with large blocks ment which required no fuch projettions ; and having 
 of Kentilh rag, forming a kind of courfed rubble-work, fubllituted arches for the horizontal architrave or li.itel, 
 the courfes tending to the centres of the arch. The they were now able to ered buildings of vail extent 
 under corner of each arch-ftone projeds over the one with fpacious openings, and all this with very fmall 
 below it. By this form it takes fall hold of the rubble- pieces of ftone. The form which had been adopted for 
 work behind it. Above this rubble there is conftrud- a Chriftian temple occafioned many interfedions of 
 ed the inverted arch \ e G of Portland Hone. This arch vaultings, and multiplied the arches exceedingly. Con- 
 fliares the preffure of the two adjoining arches, along ftant pradice gave opportunities of giving every pofliblc 
 with the arch-ftones in Y a and in G b. Thus all tend variety of thefe interledions, and taught the art of ba- 
 together to comprefs and keep down the rubble-work lancing arch againil arch in every variety of fituation. 
 in the heart of this part of the pier. This is a very An art fo multifarious, and fo much out of the road 
 ufeful precaution ; for it often happens, that when the of ordinary thought, cculd not but become an object 
 centres of the arches are ftruck, before the piers are of fond ftudy to the architeds moll eminent for inge- 
 
 nuity
 
 ARC 
 
 [ 
 
 nuity and invention. Becoming tluis the dupes of their 
 own insfenuity, they were fond of difplaying it even 
 when not neccflary. At lalt arches became their princi- 
 pal ornament, and a wall or ceiling was not thought dreiT- 
 ed out as it (hould be till filled full of mock arches, 
 croffmg and butting on each other in every diredion. 
 In this procefs in their ceilings they found that the pro- 
 jefting mouldings, which we now call the Gothic trace- 
 ry, formed the chief fupports of the roofs. The plane 
 furfaces included between thofe ribs were commonly 
 vaulted with very fnnall Hones, feldom exceeding fix or 
 eight inches in thicknefs. This tracery therefore was 
 not a random ornament. Every rib had a pofition and 
 direftion that was not only proper, but even necelTarv. 
 Habituated to this fcientific arrangement of the mould- 
 ings, they did not deviate from it when they ornament- 
 ed a fmooth furface with mock arches ; and in none of 
 the highly ornamented ancient buildings will we find 
 any falle pofitions. This is by no means the cafe in 
 many of the modern imitations of Gothic architefturc, 
 even by our bed architefts. Ignorant of the diredting 
 principle, or not attending to it, in their ftucco work, 
 they pleafe the unfl<illed eye with pretty radiated fi- 
 gures ; but in thefe we frequently fee fuch abutments 
 of mouldings as would infallibly break the arches, if 
 thefe mouldings were really performing their ancient 
 ofEce, and fupporting a vaulting of confiderable extent. 
 Nav, this began even before the Gotiiic ftyle was finally 
 abandoned. Several inftances are to be found in the 
 highly enriched vaultings of New College, and Chrilt 
 Church in Oxford, in St George's Chapel at Windfor, 
 and Henry the VH's Chapel in Wellminfter. 
 
 We call the middle ages rude and barbarous ; but 
 there was furely much knowledge in thofe who could 
 execute fuch magnificent and difficult works. The 
 working drafts which were neceflary fdr fuch varieties 
 of oblique interfetlions muft have required confiderable 
 (kill, and would at prefent occupy many very expenfive 
 volumes of mafons jewels and carpenters manuals, and 
 the like. All this knowledge was kept a profound fe- 
 cret by the corporation, and on its breaking up we had 
 all to learn again. 
 
 There is no appearance, however, that thofe archi- 
 tefts had ftudied the theory of equilibrated arches. 
 • They had adopted an arch which was very ftrong, and 
 permitted confiderable irregularities of preflTure— we 
 mean the pointed arch. The very deep mouldings with 
 ,^ which it was ornamented, made the arch ftones very 
 eat ikill long in proportion to the fpan of the arch. But they 
 tf"^ 2- had ftudied the mutual thruft of arches on each other 
 . ■ ''i_^"^with great care ; and .they contrived to make every in- 
 vention for this purpofe become an ornament, fo that 
 the eye required it as a neceffary part of the building. 
 Thus we frequently fee fmall buildings having buttrefles 
 at the fides. Thefe are neceffary in a large vaulted 
 building, for witliitauding the outward thruft of the 
 vaulting ; but they are ufelefs when we have a flat ceil- 
 ing within. Pinnacles on the heads of the buttreffcs 
 are now confidered as ornaments ; but originally they 
 were put there to increafe the weight of the buttrefs : 
 even the great tower, in the centre of a cathedral, 
 which now conftitutes its great ornament, is a load al- 
 moll indifpenfably neceffary, for enabling the four prin- 
 cipal columns to withftaud the combined thruft of the 
 aiiles, of the nave, and tranfepts. In fhort, the more 
 . Sup PL. Vol. I. Part L 
 
 5 ] ARC 
 
 clofely we examine the ornaments of this architecture. Arch. 
 the more (hall we perceive that they arc effcntial parts, * 
 
 or derived trom them by imitation: and the more wc 
 confider the whole ftyle of it, tlie more dearly do wo 
 fee that it is all deduced from the rclifli for arcades, in- 
 dulged in the extreme, and pulhed to the limit of pof- 
 fibility of execution. 
 
 ■''' 
 There is another fpecies of arch which muft not be Dome or 
 
 overlooked, namely, the Dome or Cupola, with all its'"i'"''' 
 
 varieties, which include even the pyramidal fteeple or 
 
 fpire. 
 
 It Is evident that the ereftion of a dome is alfo a 
 fcientific art, proceeding on the principles of equilibra- 
 tion, and that thefe principles admit and require the 
 lame or fimilar modifications, in confequence of the co- 
 hefion and friftion of the niaterials. At firft fight, too, 
 a dome appears a more difficult piece of work than a 
 plain arch ; but when we obferve potters kjlns and 
 glalshoule domes and cones of vaft extent, crefted by 
 ordinary bricklayers, and with materials vaftly inferior 
 in fize to what can be employed in common arches of 
 equal extent, we muft conclude that the circumftaiice of 
 curvature in the horizontal diredion, or the abutment 
 of a circular bafe, gives fome alFillance to the artift. Of 
 this we have complete demonftration in the cafe of the 
 cone. We know that a vaulting iu the form of a pent 
 roof could not be executed to any confiderable extent, 
 and would be extremely hazardous, even in the fmallelt 
 dimenfions ; while a cone of the greateft magnitude can 
 be raifed with very fmall ftones, provided only that we 
 prevent the bottom trom flying out, by a hoop, or any ,g 
 iimilar contrivance. And when we think a little of theOf cafier 
 matter, we fee plainly, that if the horizontal fedlion beconftruc- 
 perfcclly round, and the joints be all direftcd to the""" ''^^" 
 axis, they all equally endeavour to Aide inwards, vvbik^f^jj^ 
 no reafon can be offered why any individual ftone ftiouhl 
 prevail. They are all wedges, and operate only as 
 wedges. When we confider any fingle courfe, there- 
 fore, we fee that it cannot fall in, even though it may 
 be part of a curve which could not ftand as a common 
 arch ; nay, we fee that a dome may be conftrucled ha- 
 ving the convexity of the curve, by the revolution of 
 which it is formed, turned towards the axis, fo that the 
 outline is concave. We fliall afterwards find that this 
 is a ftronger dome by far tlian if the convexity were 
 outwards, as in a common arch. We fee alfo that a 
 cone may be loaded on the top with the greateft vseight, 
 without ilie fmalleft danger of forcing it down, io 
 long as the bottom courfe is firmly kept from burfting 
 outwards. The ftone lanthcrn on the top of St Paul's 
 cathedral in I>ondon weighs fcveral hundred tons, and 
 is carried by a brick cone of eighteen inches tiiick, with 
 perfetl fafety, as long as the bottom courfe is prevent- 
 ed trom buriling outwards. The reafon is evident : 
 The preffure on the top is propagated along the cone 
 in the diredion of the flant ildc ; and, fo far from ha- 
 ving any tendency to break it in any part, it tends ra. 
 ther to prevent its being broken by any irregular prcf- 
 lure from foreign caufes. „. 
 
 For the fame reafons the odagonal pyramids, which Proper con- 
 form the fpircs of Gothic architedurc, are abundantly '^''"'^"'" °^ 
 firm, although very thin. The iides of the Ipire of^^^^^l] 
 Sallfbury cathedral are not eight inches thick after the 
 odagon is fully formed. It is proper, however, to di- 
 D reft
 
 Arch. 
 
 ARC [ 26 ] ARC 
 
 rcA the joints to the axis of the pyramiil, a;id to make change, becaufi: the weight of eaoti courfe is fiiperaihled Ard 
 •"""> the ctiuvfiiio- joints perpendicular to the flant fide, be- to that of the portion above it, to complete the prciTiire '^ 
 caufe the projeifling moulding.; whicli run along the on the courfe belo\r. Through C draw the vertical 
 angles are the abutments on which tlie whole pannel line BCG, meeting ", b, produced in C. We may take 
 depends. A confiderable art is neceflary for fuppovting be to prefs the preffure of all that is above it, propa- 
 thofe pannels or fides of the odlagon which fpriug from gated in this direftion to the joint KL. We may alio 
 the angles of the fqnare tower. This is done by be- fuppofe the weight of the courfe HL united in I, and 
 •'iiininiT a very narrow pointed arch on the fqnare tower ailing on the vertical. Let it be reprefented by b V, 
 at a great .lillance below the top ; fo that the legs of If we form the panillclogram b FGC, the diagonal b G 
 the arch bting very long, a ftvaight line may be drawn will reprefent the direftion and intenfity of the whole 
 from the top of the keyilone of the arch through the preffure on the joint KL. Thus it appears that thi> 
 wliolc archllones of the legs. By this difpofition the preffure is continually changing its ilircdion, and that 
 thrufts arifipf from the weight of thefc four pannels arc the line, which will always coincide with it, m\ill be a 
 made to meet on the maffive mafonry in the middle of curve concave downward. If this be precilely the 
 the fides of the tower, at a great diftance below the curve of the dome, it will be an equilibrated vaulting ; 
 fpringlniT of the fpire. This part, being loaded with but fo far from being the ftrongell form, it is the 
 the "reat mafs of perpendicular wall, is fully able to weakeft, and it is the limit to an infinity of others, which 
 ■withftand the horizontal thruft from the logs ot ihofe are all llrongcr than it. This will appear evident, it 
 arches. In many fpires thefe thru.ls are ftill farther re- we fuppofe that b G does not coincide with the curve 
 iifled by iron bars which crofs the tower, and are hook- A 3 B, but pail'es without it. As we luppole the arch- 
 ed into pieces of brafs firmly bedded in the mafonry of Hones to be exceedingly thin from infide to outfule, it is, 
 the fides. ^ plain that tliis dome cannot Hand, and that the weight ot 
 Txarnplcs There is much nice balancing of this kind to be ob- the upper p.art will prefs it down, and fpring the vault- 
 cf fuch con- ferved in the highly ornamented open fpires; fuch as ing outwards at the joint KL. But let us tuppofe, on 
 ftrudtion. (i,ofg gf BrulFels, Mechlin, Antwerp, &c. We have the other hand, that b G falls within the curviliucal ele- 
 not many of this fort in Britain. In thofe of great ment bTi. This evidently tends to pulh the arch-Hone 
 magnitude, the judicious eye will difeover that parts, in.ward, towards the axis, and would caule it to llide in, 
 which a common fpeftator would confider as mere or- fince the joints are fuppofed pcrfedlly fmooth and ilip- 
 naments, are neceflary for completing the balance of the ping. But fince this takes place equally in every itone 
 whole. Tall pinnacles, nay, even pillars carrying enta- of this courfe, they muil all abut on each other in the 
 blatures and pinnacles, arc to be feen Handing on the vertical joints, fqueezing them firmly together. There- 
 middle of the {lender leg of an arch. On examination, fore, refolving the thruft b G into two, one of which is 
 we find that this is neceffary, to prevent the arch from perpendicular to the joint KL, and the other parallel to 
 fpringintr upwards in that place by the preffure at the it, we fee that this lall thruH is witbilood by the verti- 
 crown. The fteeple of the cathedral of Mechlin wasthe cal joints all around, and there remains only the thrufl 
 moH elaborate piece of architcflure in this taHe in the in the direftion of the curve. Such a dome muH there- 
 world, and was really a wonder ; but it was not calcu- fore be firmer than an equilibrated dome, and cannot 
 lated to withHand a bombardment, which deHroyed it be fo eafily broken by overloading the upper part. 
 jn I rng. When the curve is concave upwards, as in the lower 
 Such frequent examples of irregular and whimfical part of the figure, the hue b C always falls below b B» 
 buildings of this kind, fliow that great liberties may be and the point C below B. When the curve is concave 
 taken with the principle of equilibration without riik, downwards, as in the Tipper part of the figure, 'b C 
 if we take care to ficure the bafe from being tliruft paffcs above, or without b B. The curvature may be 
 Butwards. This may always be done by hoops, which lo abrupt, that even b' G' fhall pafs without 'b B, and 
 can be concealed in the mafonry ; whereas, in common the point G' is above B'. It is alfo evident that the 
 arches, thefe ties would be vifible, and would offend the 
 
 It is now time to attend to the principle of equili- 
 brium, as it operates in a fimple circular dome, and to 
 determine the thlcknefs of the vaulting when the curve 
 is given, or the curve when the thlcknefs is given. 
 Plate H. Therefore, let B 3 A (fig. 17.) be the curve which pro- 
 •.Q duces the dome by revolving round the vertical axis .'il>. 
 
 Srabihtyof We fhall fuppofe this curve to be drawn through the any elevation, however fmall ; nay, iince the fridion of 
 
 a dome de- middle of all the arch- Hones, and that the courfing or two pieces of Hone is not iefs than half of their mutual 
 
 vends on horizontal joints are every where perpendicular to the preffure, fuch a dome will Hand, although the tangent 
 
 curve. We fhall fuppofe (as is always the cafe) that to the curve at the bottom (hould be horizontal, pro- 
 
 the thlcknefs KL, HI, &c. of the arch-ftones is very vided that the horizontal thruH be double the weight 
 
 fmall in comparifon with the dlmenfions of the arch, of the dome, which may eafily be the cafe if it do not 
 
 If we confider any portion HA h of the dome, it is rife high. 
 
 plain that it preffes on the courfe, of which HL is an Thus we fee that the ftabillty of a dome depends on Different 
 
 arch-Hone, in a direftion bC perpendicular to the joint very different principles from that of a common arch, f''"™ '"*] 
 
 HI, or in the direftion of the next fuperior element and is in general much greater. It differs alfo in ano-" ^ ""S 
 
 A b oi the curve. As we proceed downwards, courfe af- ther very important circumHance, viz. that it may be 
 
 ter eourfe, vye fee plainly ■ that this direflion mull open in the middle : for tha uppermoll courfe, by tend- 
 
 tjig 
 
 |iriiiciples 
 
 force which thus binds the Hones of a horizontal courlu 
 together, by puHiing them towards the axis, will be 
 greater in flat domes than in thofe that are more con- 
 vex ; that it will be Hill greater in a cone ; and greater 
 Hill in a curve whofe convexity is turned inwards : tor 
 in this lall cafe the line b G will devi.ite moH remark- 
 ably from the curve. Such a dome will Hand (having 
 polifhed joints) if the curve fprings from the bafe with
 
 Ai-clv 
 
 ARC [27 
 
 ing eqmlly in every part to flicic in toward flic axis, /) 
 
 ' proires all topfether in tiie vertical joints, and acts on the 
 next covirfe like the key ftone of a common arch. 
 Thcrefi-'rc an arch of equilibration, which is the weak- 
 eft of all, mar be open in the middle, and carry at top 
 another building-, fnch as a lanthern, if its weiglit ^o 
 rot exceed that of the circular feg^ment of the dome that 
 IS omitted. A greater load than this would indeed 
 break the dome, by canling it to fpring up in fome of 
 the lower courfes ; but this load may be increafed if the 
 curve is flatter than the curve of equilibration : and 
 any load whatever, which will not crufli the ilones to 
 powder, may be fet on a truncate cone, or on a dome 
 formed by a curve that is convex toward the axis; pro- 
 vided always that the foundation be effeftually prevent- 
 ed from living out, cither by a hoop, or by a fufiicient 
 mafs of folid pier on wliich it is fet. We have mention- 
 ed the many failures which happened to the dome of 
 St Sophia in Conilanlijiople. We imagine that the 
 thru It of the great dome, bending the eallern arch out- 
 ward as foon as the pier began to yield, dcllroyed the 
 half dome which was leaning on it, and thus, almolt in 
 an inllant, took aWay the eallern abutment. We think 
 that this might have been prevented without any change 
 
 ] ARC 
 
 and complete the parallelogram MONP, and draw ArA. 
 OQjierpendicular lo the axis, and produce b¥, cutting '■""V" 
 the ordinates I'n E and e. It is plain that MN is to 
 MO as the weight of the arch HA^ to the thrntl ic 
 which it exerts on the joint KL (this thruft being pro- 
 pagated through the coiirfe HILK) ; and that MQ_, 
 or Its equal ie, or ^ i/, may reprefcnt the weiffht of the 
 halfAIi^ 
 
 Let AD be called .v, and DB be called jr. Then 
 ie == X, and eC =: y (bccaiife l/c is in the direftion of 
 the element pi)- It is alio plain, that if we make y 
 conflant, BC is the fecond fluxion of x, or BC = x, 
 and ie and BE may be conlidered as equal, and taken 
 
 indifcriminately for .v. We have alfo i5C = V x- + jr*. 
 Let cJ be the depth or thicknefs HI of the arch-ftoues. 
 
 Then (/ V .V -f- j'= will reprefent the traoe/liim HT^: 
 and lince the circumference of each cmirfe incrj.tles in 
 
 the proportion of the radius _)■, dy V x^ -)- j/^ will ex. 
 prefs the whole courfe. If y be taken tc leprcfent the 
 fum or aggregate of the quantities anuexec' to it, the 
 formula will be analogous to the fluent of a .luxion, and 
 
 41 
 
 !.".-A^''T'i'_^'.?."! pJ1"A;-L'u1 t"'L'^''i^l';"„''"°?u^ //j-v/^^-l-/ win reprefent the whole r.ai>, and alfo 
 
 the weight of the vaulting down to the joint HI. 
 
 Theref ore we have this proportion y^t/j Vx»-|.y 
 
 : Jy \/x^ +f=:ie:iF,=i(: C G, - ^d : CG, 
 
 d y X v x' -I- _jr» 
 
 with iron, as was praft'led by Mitliael Angelo in the 
 
 vaiHy more ponderous dome of St Peter's at Rome, and 
 
 by Sir Chrillophcr Wren in the cone and the inner 
 
 [cellency dome of St Paul's at I^ondon. The weight of the lat- 
 
 rhedomet;.r conliderably exceeds 3000 tons, and they occalion 
 
 ■'''" a horizontal thrull which is nearly half this quantity, 
 
 the elevation of the cone being about 60". This be- 
 
 ' ing diilributed round the circumference, occalions a 
 
 ftrain on the hoop = - — of the thruft, or nearly 
 
 23S tons. A fquare inch of the worft iron, if well 
 forged, will carry 2; tons with perfeft fafety ; therefore 
 a hoop of 7 inches broad and T^- inches thick will com- 
 pletely fecure this circle from burfting outwards. It is, 
 however, much moi-e completely fecured ; for befides a 
 hoop at the bafe of very nearly thefe dimenfions, there 
 are hoops in different courfes of the cone which bind it 
 into one mafs, and caufe it to prefs on the piers in a di- 
 reftion exadlly vertical. The only thrults v/hich the 
 piers fuftain are thofe from the arches of the body of 
 the church and the tranfepts. Thefe are moft judi- 
 cioufly directed to the entering angles of the building, 
 and are there refifted with infuperable force by the whole 
 lengths of the walls, and by four folid mafles of mafon- 
 ry in the corners. Whoever confiders with attention 
 and judgment the plan of this cathedral, will fee that 
 the thrulls of thefe arches, and of the dome, are incom- 
 parably better balanced than in St Peter's church at 
 Rome. But to return from this fort of digreffion. 
 .eiiry of We have feen that if 3G, the thruft compounded of 
 ; curves the thruft i C, exerted by all the courfes above HILK, 
 aper f»r and if the force b F, or the weight of that courfe, be 
 mes. everywhere coincident with b B, the element of the 
 curve, we ftiall have an equilibrated dome ; if it falls 
 within it, we have a dome which will bear a greater 
 load ; and if it falls without it, the dome will break at 
 the joint. We muft endeavour to get analytical expref- 
 fions of thefe conditions. Therefore draw the ordinates 
 ■tH", BDB'', Cr/C". Let the tangents at 6 and 3" 
 meet the axis in M, and make MO, MP, each equal to 
 
 = X : CG. Therefore CG 
 
 /'^^K^'> 
 
 + j),i 
 
 If the curvature of the dome be precifely fuch as 
 puts it in equilibrium, but without any mutual picfTure 
 in the vertical joints, this value of OG muft be equal to 
 CB, or to X, the point G coinciding with B. This 
 
 condition will be exprefTedbythe equation — — "- •' 
 
 J d y \/ x^ -f-j" 
 
 =r X, or, more conveniently, by 
 
 I dy v/k^ + J^ * 
 But this form gives only a tottering equilibrium, inde- 
 pendent of the frittion of the joints and the cohefion of 
 the cement. An equilibrium, accompanied by fome firrft 
 liability, produced by the mutual preffure of the verti- 
 cal joints, may be exprefled by the formula . / " - 
 
 X , dytJ x^ ■{■ y^ X , t , . , 
 
 ■:P'-r, or by —.=.^^,=r=z= .^-f , where t is fome 
 
 Jdy^x^+y^ X * 
 
 variable pofitive quantity, which incrcafes when x iu- 
 creafes. This laft equation will alfo exprefs the equi- 
 librated dome, if / be a conftant quantity, becaufe irt 
 
 this cafe — is =± 0. 
 t 
 
 Since a firm ftability requires that — — — "*"-•< 
 
 f^y V^^' + y'' 
 
 (hall be greater than .v, and CG muft be greater than 
 
 CB ; Hence we learn, that figures of too great curvature, 
 
 whofe fides defcend too rapidly, are improper. Alfo, 
 
 1> a fincc
 
 Arch. 
 
 ARC 
 
 fince (lability requires that we have 
 
 [ 2S 1 
 
 A R 
 
 tly'x V 
 
 X' +y' 
 
 greater than y^/jr V \'+ >■". we learn that the upper 
 part of the dome mud not be made very heavy. This, 
 by dimiiiifhing the proportion of A F to ^ C, diminifties 
 the angle c I' G, and may fet the point G above B, 
 which vill infallibly fpring the dome in that place. We 
 fee here alfo, that the alj^^cbraic analyfis expreflcs that 
 peculiarity of dome-vaulting, tliat the weight of the up- 
 per part may even be fupprcded. 
 
 The fluent of the equation 
 
 dy y/jc- + y' __ x , _^ 
 
 Jdy >y 7F+f x^ ' 
 
 is moft eafily found. ItisL/(/j v/«' + ji- = L x + 
 L. t, where L is the hyperbolic logarithm of the quan- 
 tity annexed to it. If we confider y as conftant, and 
 corred the fluent fo as to make it nothing at the vertex, 
 
 it may be cxprefTcJ thus, "LJ J y v «'+.V' — La=Lx 
 
 T • ■ T -r-L- • T /"'iV *"+J 
 — L.y -f Jl. /. 1 his gives us Ly =— -^ 
 
 Jdy v/£+7 
 
 
 
 and therefore/— 
 
 a y 
 
 This laft equation will eafily give us the depth of 
 vaulting, or thicknefs d of the arch, when the curve is 
 
 dome, whofe outline io an undulated curve, may be made 
 abundantly firm, elpecially if the upper pait be convex 
 and the lower concave outwards. 
 
 The chief difficulty in the cafe of this analyfis arifes 
 from the neceffity of exprefling the weight of the in- 
 
 ciKrbent pait, nx J dyV^^ + j'- This requires the 
 meafurL-mcnt of the conoidal lurfacc, which, in moil 
 cafes, can be had only by approximation by means of 
 infinite feriefes. We cannot expecl that the generality 
 of practical builders are familiar with this branch of ina- 
 thematics, and therefore will not engage in it here; but 
 content ourfelves with giving fuch inllances as can be 
 undcrftood by fuch as have that moderate mathematical 
 knowledge v/hicli every man fhould poflefs wlio takes 
 the name of engineer. 
 
 The furface of any circular portion of a fphere Is ve- 
 rv eafily had, being equal to the circle defcribed'with a 
 radius equal to the chord of half the arch. This radius 
 
 is evidently := v "■^ "^ y^- 
 
 In order to difcover what portion of a hemifphere 
 may be employed (for it is evident that we cannot em- 
 ploy the whole) when the thicknefs of the vaulting is 
 uniform, we may recur to tlie equation or formula 
 
 dy X s^f x' — y- —fdy v/«^ -fj),\ Let a be the radius 
 
 g 
 
 iven. For its fluxion is _Z 
 a t X ■\- at X 
 
 nd </ = 
 
 =, which is all exprelTed in known 
 
 yy \/«'+J'- 
 
 quantities; tor we may put in place of t any power or 
 
 funftion of xorofy, and thus convert the exprclTion 
 
 into another, which will ftill be applicable to all fcrts of 
 
 curves. 
 
 X t 
 
 Inflead of the fecond member -^ -^ — , we might em- 
 
 ploy £-^ , where p is feme number greater than unity. 
 This will evidently give a dome having flability ; be- 
 
 caufe the original formula 
 
 dyic>j£_+_f 
 
 fdy ^/x^ + f- 
 
 will then be 
 
 greater than x. This will give </=: 
 
 / a : 
 
 yy 
 
 V*'+/ 
 
 Each 
 
 of the hemifphere. 
 
 of thefe forms has its advantages when applied to parti- 
 
 a X 
 cular cafes. Each of them alfo gives d = r ;. 
 
 yy \/x'-^-y^ 
 
 when the curvature is fuch as is in precife equilibrium. 
 And, laftly, if d be conftant, that is, if the vaulting be 
 of uniform thicknefs, we obtain the form of the curve, 
 becaufe then the relation of x to x and to j is given. 
 
 The chief ufe of this analyfis is to difcover what 
 curves are improper for domes, or what portions of 
 given curves may be employed with fafety. Domes are 
 generally built for ornament ; and we fee that there is 
 great room for indulging our fancy in the choice. All 
 cui"ves which are concave outwards will give domes of 
 great firmnefs : They are ajfo beautiful. The Gothic 
 
 We have x = — — - - 
 
 and: 
 
 Arch. 
 
 := 1. Subftituting thefe values in the formula, 
 
 a — ^7 1 2 
 
 we obtain the equation ji^ V a^ — j' •=. f-— -lJL— . We 
 
 V a'-^y^ 
 eafily obtain the fluent of the fecond member z=. d — 
 
 ^' V^a^ — ^i, and y z=. a s/ — ^ + v' |. Therefoie 
 if the radius of the Iphei-e be one, the half breadth of the 
 
 dome muft not exceed s' — t + '^i> or 0,786, and 
 the height will l-t 618. The arch from the vertex is 
 about 31° 49'. Much more of the hemifphere cannot 
 itand, even though aided by the cement, and by the 
 friftion of the courfing joints. This laft circumftance, 
 by giving connedtion to the upper parts, caufes the 
 whole to prefs more vertically on the courfe below, and 
 thus diminifhes the outward thruft ; but it at the fame 
 tiine diminifties the mutual abutment of the vertical 
 joints, which is a great caufe of firmnefs in the vault- 
 ing. A Gothic dome, of which the upper part is a 
 portion of a fphere not exceeding 45° from the vertex, 
 and the lower part is concave outwards, will be very 
 ilrong, and not ungraceful. 
 
 But the public tafte has long rejefted this form, and Dome" oF 
 feeins rather to feleA more elevated domes than this por-St Peter i 
 tion of a fphere; becaufe a dome, when feen from a*' ""' 
 fmall diftance, always appears flatter than it really is. 
 The dome of St Peter's is nearly an ellipfoid externally, 
 of which the longer axis is perpendicular to the horizon. 
 It is very ingenioufiy conftruded. It fprings from the 
 bafe perpendicularly, and is very thick in this part. 
 After rifing about 50 feet, the vaulting feparates into 
 two thin vaultings, which gradually feparate from each 
 other. Thefe two ftiells are connettcd together by thin 
 partitions, which are very ai-tincially dovetailed in both, 
 and thus form a covering which is extremely ftiff^ while 
 it is very light. Its great ftiff'nefs was neceffary for en- 
 abling the crown of the dome to carry the elegant ftoac 
 
 lanthern 
 
 43
 
 *ri.1i. 
 
 ARC [ 2 
 
 lantliern with fafcty. It is a wonderful performance, 
 
 '~r—' and has not its equal in the world ; but it is an cnor- 
 irious load in coiiiparifon with the dome of St Paul's, 
 and th'S even indci)endent of the difference of fize. If 
 they were of equal dinienfiDns, it would be at leall five 
 times as heavy, iiiiJ is not fo firm by its gravity ; but 
 as it is connefted in every part by iron bars (lodged in 
 the folid niafonry, and well fecured from the weather by 
 having lead melted all round them), it bids lair to lall 
 for ages, if the foundations do not fail. 
 
 If a circle be deferibed round a centre placed any- 
 
 'Jatcir. where in the tranfverle axis AC (fig. l8. N' i.) of an 
 ellipfe, fo as to touch the ellipfe in the extremities B, b, 
 of an ordinate, it will touch it internally, and the circu- 
 lar arch V>ab will be wholly within the eUiptical arch 
 13 A b. Therefore, if an elliptical and a fpherical vault- 
 ing fpring from the fame bafe, at the fame angle with 
 the horizon, the fpherical vaulting will be withia the 
 elliptical, will be flatter and lighter, and therefore the 
 weight of the next courfe below will bear a greater pro- 
 portion to tiie thruil in the direiSion of the curve ; 
 therefore the fpherical vaulting will have more liability. 
 On the contrary, and for fuiiilar reafons, an oblate el- 
 liptical vaulting is preferable to a fpherical vaulting 
 fpringing with the fame inclination to the horizon. 
 (Fig. i8. N°2.). 
 
 menfions Perfuaded, that what has been faid on the fubjeft 
 belt convinces the reader that a vaulting perfeitly equilibra- 
 
 „j_ ted throughout is by no means the betl form, provided 
 
 that the bafe is fecured from feparatiiig, we think it un- 
 neceffary to give the inveftigation of that form, which 
 lias a coufiderable intricacy ; and (hall content ourftlves 
 with merely giving its dimenfions. The thicknefs is 
 fappofcd uniform. The numbers in the tirlt column of 
 the table exprefs the portion of the axis counted from 
 the vertex, and thofe of the fecond column are the 
 lengths of the ordinates. 
 
 4* 
 
 44 
 
 AD 
 
 DB 
 
 AD 
 
 DB 
 
 AD 
 
 DB 
 
 0,4 
 
 100 
 
 610,4 
 
 1080 
 
 2990 
 
 ( j6o 
 
 .^+ 
 
 200 
 
 744 
 
 1 140 ' 
 
 3442 
 
 16:0 
 
 11,4 
 
 300 
 
 904 
 
 1200 
 
 3972 
 
 1640 
 
 26,6 
 
 4C0 
 
 I 100 
 
 1260 
 
 4432 
 
 1670 
 
 y2.4 
 
 500 
 
 '.iS^ 
 
 .320 
 
 4952 
 
 1700 
 
 9''+ 
 
 6co 
 
 1 j22 
 
 1360 
 
 Sii^' 
 
 1720 
 
 146,8 
 
 ■700 
 
 1738 
 
 14CO 
 
 51S6 
 
 1740 
 
 2i^.4 
 
 8oo 
 
 1984 
 
 1440 
 
 62 14 
 
 1760 
 
 326,6 
 
 900 
 
 2270 
 
 1480 
 
 6714 
 
 1780 
 
 465,4 
 
 ICOO 
 
 2602 
 
 1520 
 
 7260 
 
 1800 
 
 The curve delineated in fig. 19. is formed according 
 to thefe dimeufions, and appears dellitute of graceful- 
 nefs ; becaufe its curvature changes abruptly at a little 
 diftance from the vertex, fo that it has fome appearance 
 of being made up of different curves pieced together. 
 But it the middle be occupied by a lanthern of equal, 
 or of fmaller weight, this defeft will ceafe, and the whole 
 will be elegant, nearly refembling the exterior dome of 
 St Paul's in Loudon, 
 anta^es. It is not a fmall advantage of dome-vaulting that it 
 -me- is lighter than any that can cover the fame area. If, 
 ""S- moreover, it be fpherical, it will admit coufiderable va- 
 rieties of figure, by combining different fpheres. Thus, 
 a dome may begin from its bafe as a portion of a large 
 
 9 ] ARC 
 
 liemifphere, and mny be broken off at any horizontal .Arch, 
 courfe, and then a limilar or a greater portion of a fmal- v— ~ 
 ler fphere may fpring from this courfe as a bafe. It 
 alfo bears being inttrfedU'd by cylindrical vaultings in 
 every direftion, and the interfedtions are exart circles, 
 and always have a plealing effedt. It alfo fprings moll 
 gracefully from the heads of fmall piers, or from the 
 corners of rooms of any polygonal Ihape ; and the arches 
 formed by its interfcdtions with the walls are always cir- 
 cular and graceful, forming very handfome fpandrels in 
 every pofition. For thefe reafons Sir Chrillopiier Wren 
 employed it in all his vaultings, and he has exhibited 
 many beautiful varieties in the tranfepts and the aiiles 
 of St Paul's, which are highly worthy of the obferva- 
 tion of architefts. Nothing can be more graceful than 
 the vaultings at the ends of the north and fouth tran- 
 fepts, efpecially as finilhed off in the fine infide view , 
 publiflied by Gwynn and Wale. .^ 
 
 We conclude this article with obferving, that theEflTeflsof 
 conneftion of the parts, arifing from cement and from ".ll?"' ?'''^ 
 friction, has a great effedt^on dome-vaulting. In the 
 
 fii(»i;,ii 
 d(HTt€vaulc- 
 
 fame way as in common arclies and cylindrical vaulting, ire, 
 it enables an overload on one place to break the dome 
 in a diftant place. But the refiftance to this efiett is . 
 much greater in dome-vaulting, becaufe it operates all 
 round the overloaded part. Hence it happens that domes 
 are much Icfs Ihattered by partial violence, fuch as the 
 falling of a bomb or the like. Large holes may be bro- 
 ken in them without much affedfing the rell ; but, on 
 the other hand, it greatly diminillus the flrength which 
 fiiould be derived from the mutual preffure in the verti- 
 cal joints. Fridtion prevents the Aiding in of the arch 
 Hones which produces this mutual prtflure in the verti- 
 cal joints, except in the very lilglietl courfes, and even 
 there It greatly diminilhes it. Thefe caufcs make a 
 great change in the form which gives the greatell 
 itrength ; and as their laws of adlion are but very im- 
 perfectly underftood as yet, it is perhaps impoffible, in 
 the prcfent If ate of our knowledge, to determine this 
 form with tolerable precifion. We fee plainly, how. 
 ever, that It allows a greater deviation from the bell 
 form than the other kind of vaulting, and domes may 
 be made to rife perpendicular to the horizon at the 
 bafe, although of no great thicknefs; a thin^ wiiicli 
 mult nut be attempted in a plane arch. The mimeide 
 addition of flrength which may be derived from lioop- 
 "ig, largely compenfates tor all defedts ; and there is 
 hardly any bounds to the extent to which a very thia 
 dome-vaulting may be carried, when it is hooped or 
 framed in the directimi of the horizontal cou -fes. The 
 roof of the Halle du Bled at Paris is but a foot thick, 
 and its diameter is. more than 200, yet it appears to 
 have abundant flrength. It is, on the whole, a noble 
 fpecimen of architcdture. 
 
 We mufl not conclude this article without taking rhelfm 
 notice of that magiuTicent and elegant arch whichh.tibiclye.it. 
 been eredted in call iron at WerciDouth, near Sunder; SunrterlanJ. 
 land, in the county of Dm-ham. The inventor and ar. '^•'"''^'*'* 
 chitedt is RoVv'L.iND Burdon, Efq; one of the repre. 
 fentatives of that county in the prefeut Parliament. 
 
 This arch is a fegment of g circle whofe diameter is 
 about 444 feet. The fpan or cord of the arch is 236 
 feet, and its verfed fine or fpring is 34 feet. It fpring? 
 at the elevation cf 60 feet from the furface of the ri.
 
 ARC [3: 
 
 Arch. Ter at low water, fo that vefTcls of 200 or pcrhnp'; 300 
 ' ■ V ' ' tons blinieQ may pafs under it in tlio middle of the 
 Ilrcam, and even 50 feet on each fide of it. 
 
 The fweep of the arch confiih of a feries of frames of 
 caft iron, which butt on each ether, in the fame man- 
 ner as the voufToirs of a ilone arch. One of thefe 
 frames or blocks (as we (hall call them in future) is re- 
 Plate IV. prcfentcd in fig. 1. as feen in front. It is caft in one 
 piece; and confifts of three pieces or arms BC, BC, BC, 
 the middle one of which is two feet long, the upper be- 
 in.g fomewhat more, and the lower fomewhat Icfs, be- 
 caufe their extremities are bounded by the radius drawn 
 from the centre of the arch. Thefe arms are four inches 
 fquarc, and are connefted by other pieces KL, of fuch 
 length that the whole length of the block is five feet in 
 the dirtftion of the radius. Each arm has a flat groove 
 on each fide, which is expreffed by the darker fhading, 
 three inches broad and ihree-foniths of an inch deep. 
 A feAion of this block, through the middle of KL, is 
 reprefented by the light-fliaded part BBB, in which the 
 grooves are more diftindly perceived. Thefe grooves 
 are intended for receiving flat bars of malleable iron, 
 ^viiich are employed for connefting the different blocks 
 with each other. Fig. 2 repvelents two blocks united 
 in this manner. For this purpofe each arm has two 
 fquare bolt-holes. The ends of the arms being nicely 
 trimmed off, fo that the three ends butt equally clofe 
 on the ends of the next bloc4c ; and the bars of ham- 
 itiered iron being alfo nicely fitted to their groove,", fo 
 as to fill them completely, and have their bolt holes ex- 
 adlly correfponding to tliofc in the blocks, they are put 
 together in fuch a manner that the joints or meetings 
 of the malleable bars may fall on the middle between 
 the bolt-holes in the arms. Flat headed bolts of wrought 
 iron are then put through, and keys or forelocks are 
 driven thro' the bok-tails, and thus all is firmly wedged 
 together, binding each arm between two bars of wrought 
 iron. Thefe bars are of fuch length as to conned feve- 
 ral blocks. 
 '' In this manner a feries of about 125 blocks are joined 
 
 together, fo as to form the precife curve that is in- 
 tended. This feries may be called a rib, and it (lands 
 in a vertical plane- The arch confifts of fix of thefe 
 ribs, diftant from each other five feet. Thefe ribs are 
 connefted together fo as to form an arch of 32 feet in 
 breadth, in the following manner: 
 
 Fig. 3. reprefei^s one of the bridles or crofs pieces 
 which conned the difl'erent ribs, as it appears when 
 viewed from below. It is a hollow pipe of caft iron, 
 four inches in diameter, and has at each end two pro- 
 jefting fhoulders, pierced with a bolt-hole near their ex- 
 tremities, fo that the diftance between the bolt-holes in 
 the fhoulders of one end is equal to the diftance between 
 the holes in the arms of the blocks, or the holes in the 
 wrought iron bars. In tlie middle of the upper and of 
 the under fide of each end may be obferved a fquare pro- 
 minence, more lightly (haded than the reft. Thefe pro- 
 jeftions alfo advance a little beyond the flat of the ft^ioul- 
 ders, forming between them a {h:i'.low notch, about an 
 inch deep, which receives the iron of the arms, where 
 they butt on each other, and tlius gives an additional 
 ' firmnefs to the joint. The manner in which the arms 
 
 are thus grafped by thefe notches in the bridles is more 
 diftinftly feen in fig. 2. at the letter H in the middle of 
 the upper rail. 
 
 1 
 
 ARC 
 
 The rib having been all trimmed and put tonrethei', Arc} 
 fo as to form the exaft curve, the bolts are ail taken *"~— v— ' 
 out, and the horizontal bridles are then fet on in their 
 places, and the bolts are again put in and made fall by 
 the forelocks. The bolts now pafs through the fhoul- 
 ders of the bridles, through the wrought iron bars, and 
 through the cafl iron arm that is between them, and 
 the forelocks bind all faft together. The manner in 
 which this conneftion is completed is dillindtly feen in 
 fig. 2. which fhews in perfpedlive a double block in 
 front, and a fingle block behind it. The butting joints 
 of the two front blocks are at the letters E, E, E ; the 
 holes in the fhoulders of the horizontal crofs pieces arc 
 
 ^'^■. ... 4! 
 
 This conflrudion is beautifully fimple and very judi- its con- 
 
 cious. A vaft addition of ftrength and of ftiffnefn isHrudiot 
 procured by lodging the wrought iron bars in grooves. 'jP'.^ * 
 formed in the caft iron rails; and for this purpofe itisof^'^ '"°'" 
 great importance to make the wrought iron bars fill the 
 grooves completely, and even to be fo tight as to re- 
 quire the force ot the forelocks to draw them home to 
 the bottom of the grooves. There can be no doubt but 
 that this aich is able to witlifland an enormous pref- 
 fiire, as long, as the abutments from which it fprings do 
 not yield. Of this there is hardly any rifle, becaufe 
 they are maffes of rock, faced with about four or five 
 yards (In fome places only) of folid block mafonry. 
 The mutual thrufts of the frames are all in the direftlon 
 of the rails, fo that no part bears any tranfverfe tlrain. 
 We can hardly conceive any force that can overcome 
 the ftrength of thofe arms by prcffure or crufhing them. 
 The manner in whiv.'h the frames are connected into one 
 rib, effedlually fecures the butting joints from flipping; 
 ^nd the accuracy with which the whole can be execu- 
 ted, fecures us againft any warping or deviation of a rib 
 from the vertical plane. 
 
 But when we confider the prodigious fpan of thii 
 arch, and refledl that it is only five feet thick, it fliould 
 feem that the moll perfed equilibration Is indifpeiiiably 
 neceffary. It Ij but like a film, and muft be fo fupple 
 that an overload on any part mull have a great ten- 
 dency to bend it, and to caufe it to rife in a diftant 
 part ; and this eficft is increaled by the very firm- 
 nefs with which the whole flicks together. Tiie over- 
 loaded part afts on a diftant part, tending to break 
 it with all the energy of a long lever. This can be 
 prevented only by means of the ftifinefs of the diftant 
 part. It Is very true, the arch cannot break in the ex- 
 trados except by tearing afunder the wrought iron bars 
 which conneft the blocks along the upper rail, and each 
 of thefe requires more than a hundred tons to tear It 
 afunder ; yet an overload of five tons on any rib at its 
 middle will produce this flrain at twenty feet from the 
 fides, fuppofing the fides held firm in their pofitlon. It 
 were defirable therefore that fomething were done to 
 fliffen the arch at the fides, by the manner of filling up 
 the fpandrels, or fpace between the arch and the road- 
 way. This Is filled up In a manner that is extremely Thougli 
 light and pleafing to the eye, namely, by large cafl Iron"ne par 
 circles, which touch the extrados of the arch and touch!"" '' ' 
 the road-way. The road-way refts on them as on ^oytivsol' 
 many hoops, while they reft on the back of the arch, ^rovem :• 
 and alfo touch each other laterally. We cannot think 
 that this contributes to the ftrength of the arch ; for 
 thefe hoops will be eafily comprefTed at the points of 
 
 contaft, . 
 
 
 4?
 
 PT>ATE L.
 
 I'l.ATK ir
 
 n.ATK TTI 
 
 lULlXillC AXHI^rG-^'^
 
 iM.ATR ^^■. 
 
 5
 
 ARC r 3P ] ^ ^. ^ . 
 
 •eh, contaft, afiJ, changing their fhape, will oppofe very ignorant and barbaro.is ?" This qiieftion has occupietl Archltec- 
 litec- lijtig refiltance. We think that this part of the arch the attention of many ingenious men, who have attri- 
 
 j might have been greatly (liffencd and ftrengthened, by bn'ed the Gothic ftjle of building, fome to neceffity, 
 
 connefting it with the road-way by trufled frames, in and others to an imitation of the works ot nature. That, 
 
 the fame way that a judicious carpenter would have fra- where materials are bad, l.irger edihces can be ereitcd 
 
 med a roof. If a ftrong call iron pillar had been made in the Gothic than in the Grecian llyle, has been made 
 
 to reft on the arch at about 20 feet from the inipolt, fiifficiently evident in the articles to which we have re- 
 
 and been placed in the direftion of a radius, the top of ferred ; and that necefilty is tlie parent of invention, is 
 
 this pillar might have been connefted by a di.igonal bar an adage which has been too long received to be now 
 
 of wrought iron with the impoil of the aich, and with called in qneilion. But whence came the peculiarities 
 
 the crown of the arch by another (tring or bar of the of the Gothic ornaments in building, the pointed arch,_ ' 
 
 fame materials. Thefe two ties wo\dd canfe the radial and the double row of clullered pillars compofed of 
 
 pillar to prefs ilrongly on the back of the arch, and flender iliafts, which, reaching from the ground almoll 
 
 they mull be torn afunder before it cjuld bend in that to the roof of the building, are there Iprcad out in 
 
 place in the fnialleft degree. Suppofing them of the all dircftions, forming the ribs or groins of a vaulted 
 
 fame dinienfions as the bars in the arms, their pofition roof? 
 
 would give them near ten times the force for refilling the The mod fatlsfaftory folutlon of this queftion which 
 
 ftrain produced by an overload on the crown. we have feen, is in a memoir publiilied in the fourth vo- 
 
 This beautiful arch contains only 260 tons of iron, lume of the Tranfattions of the Royal Society of lidin- 
 
 of which about 51; are wrought iron. The fuperftruc- burgh, by Sir James Hall, Bart, with whole pcrmif- 
 
 ture is of wood, planked over a-top. This lloor is co- lion the following abllraft is laid before our readers, 
 vered with a coating of chalk and tar, on which is laid " Although the connedion between beauty and 
 
 the materials for the carriage road, coniilling of marie, utility be Hill involved in fuch obfcurity, that we are 
 
 lime (lone, and gravel, with fnot-ways of flag ftones at unable to decide concerning the univerfality of that 
 
 the fides. The weight of the whole did not exceed a connedion, of one thing we are certain, that, in a 
 
 thoufand tons ; whereas the lighteft Hone arch wiiich work intended to anfwer fome ufeful purpofe, what- 
 
 could have been ercdled would have weighed fifteen ever vilibly counteradts that purpofe always occafions 
 
 thoufand. It was turned on a very light but llifF leaf- deformity. Hence it is, that, even where ornament 
 
 folding, moft judicioufly conftrncted for the prefervatiou is principally intended, the oilenlibly ufeful objeA o£, 
 
 of its form, and for allowing an uninterrupted paflage the work, if it have any fuch, muft be provided for^ 
 
 for the numerous fhijjs and fmall craft which frequent in the firft place, in preference to evi;ry other conllder- 
 
 the bufy harbour of Sunderland. The mode of framing at ion. 
 
 the arch was fo fimple and eafy, that it was put up in, " But in moft ufeful works, fome parts occur, the 
 
 ten days! without an accident ; and when all was ft- fhape of which is quite indifferent witli refpeft to the 
 
 nilhed, and the fcaffolding removed, the srch did not propofcd utility, and which, therefore, the artifl is at 
 
 lenfibly change its form. The whole work was execu- liberty to execute as he pleafcs : a liberty which has 
 
 ted in three years, and coR about L. 26,000. opened a wide field to the taite and invention of inge- 
 
 ARCHI i'ECTURE is an art of fo much import- nious men of every age and country, who have turned 
 
 ance, and capable of fo many embellilhmcnts, as to their attention to the compofition of ornaments; and 
 
 have employed the attention and talents of men of whofe exertions have been more or lefs influenced by 
 
 icience in almoft every age, and in every country, the (late of civilization in which they lived. It would. 
 
 It is generally thought to have been carried to the feem, however, if we may judge by thofe various ef- 
 
 utmoll perfeition among the Greeks and Romans ; forts, that little has been elfedted I>y mere human in- 
 
 and it has been the aim of the moft eminent architects genuity ; fince we fee that recourfe h;is been had, al- 
 
 «f modern times to imitate with fidelity the buildings of moll univerfally, to nature, the great and legitimate 
 
 thofe accomplilbed nations. There is, however, another fource of beauty ; and that ornament has been attain- 
 
 fpecies of architefture, which was introduced into Eu- ed by the imitation of objeds, to which flic has given 
 
 rope in the middle ages, and is of fuch a nature as to a determinate and charaderillic form, 
 ilrike every unprejudiced obfcrver with admiration and " Where the materials employed are themfelves pof. 
 
 afloniftimeiit. The architednre to which wc allude feffed of variety and elegance, the attainment of this ob- 
 
 has been called, perhaps with little propriety, jcd requires little or no alteration of their natural forms. 
 
 Gothic ylRCHiTEcrvRS. It is that wiiich is to be view- Thus cups are made of fliells, of cocoa-nuts, orof ollrich 
 
 ed in all our ancient cathedrals, and in other large build- eggs ; the charader and beauty of which depend upon, 
 
 ings which have been ereded from the middle of the the natural form of the materials: and in the cafe of 
 
 1 2th to the beginning of the i6th centui-y. That fuch the bottles ufed by the Roman Catholic pilgrams, an 
 
 edifices have been conftruded on principles of fcience, example occurs of an utenfil, in which the natural form 
 
 has been fhewn elfewhere (fee Roof, Encycl. and Arch, has undergone little or no variation, fince it confifts of 
 
 in this Suppl.) : but a queftion ftill prefcnts itfelf to the the hard- outward fkin of a gourd, of the fame fhape in 
 
 inquilitive mind, " How came fuch ftrudures to be which it grew upon the plant (a). This laft clafs of. 
 
 thought of by a people whom we are accuftoraed to call forms has been introduced, by imitation, into works 
 
 compofed 
 
 (a) " Even in this cafe, however, the natural form undergoes a certain degree of modification, by the device 
 employed to produce the neck of the bottle. The fruit, while fmall and tender, Is furrounded with a llring, 
 which remaining during its growth, prevents the part, thus bound, from fwelling with the reft.."
 
 ARC [ 32 ] ARC 
 
 Arclu'ec- compofed of rtiapelefs niaterlals. Tims we have iilver equal to tliat between the rows, and each pod being Aidiltee. 
 "" ""■ cups in the form of thofc made of (liells, and fruitdiflies railed above the ground to a height equal to tliree of t^^e- 
 * of ftoneware in the form of baflcets. thofc intervals ; then a let of long and flexible rods of v— "* 
 " As ilone is not naturally potTcfTcd of any peculiar willow being applied to each poll, let them be thiull 
 fliape, and as the ufel'ul objeift propoled, by llrudfures into the ground at its bafe, and bound to it by two 
 formed of it, may be accomplilhed in various ways, tyiugs, one near the ground, and another at two-thirds 
 very great latitude is left to the invention of the artift. of its heiglit ; the rods being left loofe from this laft 
 We ke, accordingly, that in every country where much point upwards, and free to be moved in any diredtion. 
 rciinement has been introduced, great pains have been Let three rods be connc6ted with each fiutlide i-orner 
 bellowed in ofiiamenting Hone buildings with figures poll, and five with each of the others, and Itt their po- 
 reprcfenting various natural objefts ; whilll the build fition be fuch as to cover tlie infide of the pull, fo tiiat 
 ing itfelf has been executed in imitation of a llrufture, when feen from between the rows the lower part of 
 compofed of materials which naturally poflefs a deter- each poll fhall be concealed from the view, and prefcnt 
 ninate and charafterlllic form. Such was the method the appearance of a bundle of rods (fig i.) Plate V, 
 followed by the architefts of ancient Greece, who con- Things being thus difpofed, the flceleton of a thatch- 
 llruSed temples, and other public edifices, in imitation ed roof may be formed by means of the ioofe ends of 
 of a iniflic fabric, compofed of fquare beams, fupported the rods. A rod from one of the polls being fo bent 
 upon round polls or llems of trees, and who derived the as to meet a fimilar one from, the poll immediately op- 
 numerous ornaments of that beautiful llyle from circum- polite to it, in the middle of the fpace between them, 
 fiances which would naturally take place in fuch a ftruc- let the two rods be made to crofs each other, and let 
 ture. them be bound together at their crofling (tig. 2.), and 
 " A faint and dillant refcmblance, however, of the we fliall have the exadl form of the Gothic arch The 
 oriT-inal, has generally been found to anfwer all the end fame being done with each pair of oppofite polls, and a 
 propofed by the imitation ; a refemblancc, which may fet of pointed arches being formed, let them be conneft- 
 ionietlmes be traced in the general diftribution of the ed together by means of a llraight pole laid upon the 
 edifice, fometimes in its minute parts, and not unfie- forks of the crofling rods, and bound to each of them, 
 qucntlv in both. as in fig. 3 : then let a Ioofe rod be brought from eacti 
 " But the forms of nature thus introduced have been of any two contiguous polls in the fame row, fo as to 
 rreatly modified by thofe of mafonrv. For though form a pointed arch, fimilar to that juft defcribed, and 
 ilone is by nature fliapelefs, yet, in the courfe of prac- nearly of the fame height. This being done with every 
 tice, many peculiar forms have been long ellablilhed, two contiguous polls (fig. 4), and a new fet of pointed 
 and currently employed, in working it ; fuch as flraight arches being thus produced. Handing oppoiite to each, 
 lines, plain furfaces, fquare angles, and various mould- other in pairs, let each pair be bound by a horizontal 
 ings ufed to foften the cffedl of abrupt terminations : pole lying on the oppofite forks, and crofling the Ion- 
 all of which, originating in motives of mechanical con- gitudinal pole defcribed above. 
 
 venience, and of fimplc ornament, had, in very early " Two of the rods of each corner poll, and three of 
 times, been appropriated to mafonry, and conlidered as thofe of each of the others, being thus dilpofed of, we 
 eflential in every finiflied work of ftone ; fo that, when have one of each corner poft and two of each middle' 
 the imitation of nature was introduced, thefe mafonic poll Hill to employ, which is done as follows: A pair of 
 forms Hill maintained their ground, and, being blended thefe unoccupied rods being brought from any two polls 
 Tvith the forms of nature, the two clalfeS reciprocally which Hand diagonally to each other, and made to meet 
 modified each other. in the middle, not as in the firll cafe crofling in aa 
 " This combination of art with nature, of which we angle, but fide by fide, forming a femicircle, and join- 
 fee the moll perfedl example in the Corinthian capital, ed together after the manner of a hoop ; and the fame 
 produces what are called architeftonic forms, in which being done with every pair of diagonal polls (fig. 5.), 
 the variety of nature, being fubjefted to the regularity the whole rods will have been employed. 
 of art, the work acquires that peculiar charafter which, " In this manner a frame would be conltrufled fit to 
 in a ijatural objedl, we confider as offenfive, under the fupport thatch or other covering; and fuch a one has 
 nsmt o{ formu/i/y ; but which, in architecture, we ad- probably been often ufed. It would fcem, however, 
 mire as a beauty, under the name of fymmetry : thus, that, for the fake of llrength, the number of rods has 
 we reprobate the formality of an avenue, and praife the been increafed in each duller, by the introduflion, be- 
 fymiretry of a colonnade. tween every two of tiiem, of an additional rod, which 
 " Such is the nature of architeftonic imitation ; a rifing with them to the roof, ilill continues its middle 
 .(device which probably originated in accident, but to pofition, as they fpread alunder, and meets the horizon- 
 whi(,h architefture is indebted for its higheft attain- tal pole at an intermediate point. This is (liown in 
 ments." " f'g- 6. which is drawn with its covering of thatch ; and. 
 As the ftone edifices of ancient Greece were con- from the imitation of a dwelling fo conllrufted, we may 
 ilrufted in imitation of a wooden fabric, compofed of eafily trace the three leading charafteriftics of Gothic 
 fquare beams laid at right angles on round pofts or architefture, the pointed arch, the cluftercd column, 
 ftems of trees, Sir James conceives that the Gothic fa- and the branching roof, as exhibited in fig- 7." 
 hrics with pointed arches have been executed in imita- Upon the fame principles Sir James Hall, with much 
 tion of a rullic dwelling, conftrufted in the following ingenuity, accounts for the peculiar forms of the Go- 
 manner : Suppofe a fet of round pofts driven firmly in- thic door, the Gothic window, and the pointed fpire : 
 to the ground in two oppofite rows, the interval be- but it is not our intention to fuperlede the neceflity of 
 tween the neighbouring polls in the fame row being having recourfe to his memoir, but to excite the defire 
 
 of
 
 Rgl 
 
 lo- 2 n 
 
 Fig.,? 
 
 Fi^4.
 
 I
 
 Irchitec- 
 
 lure 
 
 II . 
 .rithmctic, 
 
 A R I [ 33 ] ART 
 
 of our readers to perufe as well that paper as a larger metic, however, or togjjlic , lias been ufed by Vieta and Arithmetic 
 work which he promifes on the fame fubjcft, and in others for the rules of computations in aigebia. " .. 
 
 ■ ■ ■ ' ' . . .1 _ -11 .-J 1 .u -.._.-:_ Political ARifUMETic. See Political Aruhmetic, « 
 
 Encycl. 
 
 Sexagefimal Arithmetic. See Arithmetic (HiJI.) 
 Encycl. 
 
 TetraSic Arithmstic, is that in which only the fo'jr 
 charafters O, F, 2, 3, are ufed. A treatifc of this kind 
 of arithmetic is extant by Erhard or Echard Weigel. 
 
 which we doubt not but they will find both entertain 
 ment and inftruftion. We (hall conclude this article, 
 therefore, with an experimental proof of the juftnefs of 
 his hypothefis. 
 
 In the greater part of our late attempts at Gothic 
 architetlure, it is allowed by every man of tafte that we 
 have failed. The failure is to be accounted for by the 
 
 buildings having been conftrudled upon no confiftent But both this and binary arithmetic are little better 
 principle, applicable to every part of them, but upon a than curiofities, efpecially wiiii regard to praftice ; as 
 fervile copying of ancient edifices, of which the llruc- all numbers are much more compendioufly and conve- 
 ture was little underftood by the copiers. Sir James Hall, niently exprefled by the common decuple fcale. 
 however, by applying his theory to practice, has con- Univerfal .-^kithmstic, is the name given by New- 
 ftrufted a building in this ftyle, which has far furpaflcd, ton to the fcience of algebra ; of which he left at Cam- 
 he fays, his own expeftation, and has certainly gained bridge an excellenc treatife, being the text-book drawn 
 the approbation of every man of tafte and fcience by up for the ufe of his lettures, while he was profefTor of 
 whom we have had occafion to hear it mentioned. " A mathematics in that univerfity. 
 
 fet of pofts of adi, about three inches in diameter, were ARITHMETICAL complement, of a loga- 
 
 placed in two rows, four feet afunder, and at the inter, rithm, is what the logarithm wants of lO'ooooo, &c. 
 
 val of four feet in the rows ; then a number of (lender and the eafieft way to find it is, beginning at the 
 
 and tapering willow rods, ten feet in length, were ap- left hand, to fubtraft every figure from 9, and the la(t 
 
 plied to the pofts, and, in the manner which we have from 10. 
 
 defcribed, formed into a frame, which being covered ARTEDI (John), was born in the year 1705, lit 
 
 with thatch, produced a very fubftantial roof, under the province of Angerinania, in Sweden. From na- 
 
 which a perfon can walk with eafe. 
 
 " This little ftrufture exhibits, in miniature, all the 
 charafterillic features of the Gothic ftyle. It is in the 
 form of a crofs, with a nave, a choir, and a north and 
 fouth tranfept. The thatch, being fo difpofed on the 
 frame as not to hide the rods of which it is compofed, 
 they reprefent accurately the pointed and femicircular 
 arches, and all the other peculiarities of a groined roof." 
 
 ARCTUS, a name given by the Greeks to two con- 
 ftellations of the northern hemifphere,.,.by the Latins 
 called Ursa Major and Minor, and by us the Greater 
 and l.ejfer Bear. 
 
 Binary ARITHMETIC. See Binary Arithmetic, 
 Encycl. 
 
 Duodecimal Arithmetic, is that which proceeds from 
 12 to 12, or by a continual fubdivifion according to 12. 
 This is greatly ufed by moft artificers in calculating the 
 quantity of their work ; as bricklayers, carpenters, 
 painters, tilers, &c. 
 
 Harmonica! /Jrithmetic, is fo much of the dottrine 
 of numbers as relates to the making the comparifons, 
 reduftions, &c. of mufical intervals. 
 
 Arithmetic of infinites, is the method of fumming 
 up a feries of numbers, of whicli the number of terms 
 is infinite. This method was firft invented by Dr Wal- 
 lis, as appears by his treatile on that fubjeft ; where 
 he (hows its ufes in geometry, in finding the areas of 
 fuperficies, the contents of folids, &c. But the method 
 of fluxions, which is a kind of univerfal arithmetic of 
 infinities, performs all theie more eafily, as well as a 
 great many other things, which the former will not 
 reach. 
 
 JLogiJlical Arithmetic, a name fonietimes employed 
 for the arithmetic of fexagefimal fraitions, ufed in aftro- 
 nomical computations. Shakerly, in his TabuU Bri- 
 tannicte, has a table of logarithms adapted to fexagefi- 
 mal fraftions, which he calls logljlital logarithms : and 
 the expeditious arithmetic, obtained by means of them, 
 ke calls logiflical arithmetic. The term /ogijlical arith- 
 
 SuppL/ Vol. I. Part I. 
 
 ture he inherited an ardent pallion fir all branches of 
 natural hiftory, but he excelled moll in that branch of 
 it which is termed itchlhyology. In 1724 he went to 
 ftudy at the univerfity of Upfal, where fome years after- 
 wards he gained the friendlhip of the immortal Linna;us, 
 who narrates the principal events of his life in the fol- 
 lowing animated terms. 
 
 " In 1728 (fays Linnasus) I came from Lund to 
 Upfal. I wiihed to devote myfelf to medicine. I in- 
 quired who, at that univerfity, excelled moil for his 
 knowledge : every one named Artedi. I was impa- 
 tient to fee him. I found him pale, and in great di- 
 ilrefs for the lofs of his father, with his thin hair ne- 
 glefted. He refembled the portrait of Ray the natu- 
 ralift. His judgment was ripe, his thoughts profound, 
 his manners fimple, his virtues antique. The converfa- 
 tion turned upon (tones, plants, animals. I was enchant- 
 ed with his obfervations, equally ingenious and new ; 
 for at the very firft he was not afraid to communicate 
 them to me with the utmoft frankiiefs. I defircd his 
 friendfiiip, he a(ked mine. From that moment we form- 
 ed a triendfliip ; which we cultivated with the greateft 
 ardour for ("even months at Upfal. I was his belt friend, 
 and I never had any who was more dear to me. How 
 fwect was that intimacy ! With what pleafure did we 
 fee it increafe fiora day to day ! The difference, even 
 of our charadlers, was ufeful to us. His mind was more 
 fevere, more attentive ; he obferved more (lowly, and 
 with greater care. A noble emulation animated us. 
 As I defpaired of ever becoming as well inftrufted in 
 chemittry as he, I abandoni-d it ; he alfo ceafed to ftu- 
 dy botany with ttie fame ardour, to which I had devo- 
 ted myfelf in a particular manner. We continued thus 
 to ftudy different branches of fcience; and when one of 
 us excelled the other, he acknowledged him for his 
 mafter. We difputed the palm in ichthyology ; but 
 foon I was forced to yield, and I abandoned that part 
 of natural hiftory to him, as well as the amphibia. I 
 fucceeded better than he in the knowledge of birds and 
 E infefts.
 
 ART 
 
 Arted!. infefts, and he no longer tried to excel in tliefe branch- 
 We inarched together as equals in lithology, and 
 the hiftory of quadrupeds. When one of us made an 
 obfervation, lie communicated it to the other : fcarce a 
 day paffed in which one did not learn from the other 
 fome new and interefting particular. Thus emulation 
 
 [ 34 1 
 
 ART 
 
 this great ichthyclogift, who had ever delighted ia that 
 element." ^ 
 
 Of the works of this eminent naturalift there have 
 been two editions, of which the former was pubhTned 
 by Linnsus in 1 738, and the latter by Dr Walbaum 
 of Lubeck, in tlie years 178?, 1789, and 1792. This 
 
 excited our induftry, and mutual affiftance aided our ef- edition, which is by much the moft valuable, is in three 
 
 forts. In fpite of the dlftance of our lodgings, we faw volumes 410 ; of which the firfl contains the hiHory of 
 
 each other every day. At laft I fet out for Lapland ; the fcience of ichthyology, commencing feveral years 
 
 he went to London. He bequeathed to me his manu- before the Chriftian era, and comir.g down to the pre- 
 
 fcripts and his books. fent times. The fecond prefents to the reader the 
 
 " In 17^5 I went to Leyden, where I found Ar- Philofophia Ichthyologtca of Artedi, improved by Wal- 
 
 tedi. I recounted my adventures ; he comm.unicated his baum, who was benefited by the writings of iionro, 
 
 to me. He was not rich, and therefore was unable to Camper, Kaetfeuter, and others. Here alfo are added 
 
 Be at the expence of taking his degrees in phyfic. I 
 recoinmended him to Seba, who engaged him to pubUfh 
 his work on fifhes. Artedi went to join him at Am- 
 fterdam. 
 
 " Scarcely had I finilhed my Fundamtnta Botanica. 
 I communicated it to him; he let me fee his Philofophia 
 Jchthyalogica He propofed to finilTi as quickly as pof- 
 fibk the work of Seba, and to put the laft hand to it. 
 He fhowed me all his manufcripts which I had not feen. 
 r was prefTed in point of time, and began to be impa- 
 
 tables containing the fyftem of fifhes by Ray, Dale, 
 Schaeffir, I^innjEus, Gowan, Scopola, Kltin, and Gro- 
 novius. The third volume, which completes the col- 
 ledlion of Artedi's works, contains the technical defini- 
 tions of the fcience. After the generic and individual 
 charafters come the names and Latin phrafes of Ar- 
 tedi ; the fynonymes of the beft naturalifts ; the vulgar 
 names in Er.glilh, German, Swedifh, Rullian, Danifli, 
 Norwegian, Dutch, and Samoj cd ; the feafon and the 
 countries where every kind is found, their varieties. 
 
 tient as being detained fo long. Alas ! if I had known their defcription, and obfervations. The modern difco- 
 
 this was the laft time I (hould fee him, how (hould I veries, even to our own times, are added ; fo that in 
 
 have prolonged it ! this part is collected the obfervations of Gronovius> 
 
 " Some days after, as he returned to fup with Seba, Brunich, Penant, Forfter, Kleki, Bloch, Gnieh'n, Haf- 
 
 the niu-ht being dark, he fell into the canal. Nobody fclquill, Brouffonet, Lelke, Builh, Linnseus, and other 
 
 perceived it, and he perifhed. Thus died, by water, great examiners of nature. 
 
 Artedi. 
 
 ASTRONOMY 
 
 r 
 
 fS a fcience which has been cultivated from the ear- 
 lieft ages, and is converiant about the moft fublime 
 objects of inquiry which can employ the mind of man. 
 It has accordingly been treated at great length in the 
 Encyclopaedia Britannica ; but, in the opinion of fome 
 of the moft judicious readers of that work, the compiler 
 of the fyftem whicli is there delivered has failed in liis 
 attempt to give a perfpicuousand connefled view of the 
 .' fcience in its prefent ilate of improvement. This dcfeft 
 ^jedl of .^ .^ ^^^ j^^y ^^ remedy. Our objetl, therefore, in this 
 ' fupplementary article, will be to bring into one point of 
 view the phyfical fcience which may be derived from 
 the confideration of the celeftial motions ; that is, to 
 deduce from the general laws of thofe motions the in- 
 ferences with refpecl to their fuppofed caufes, which 
 conft-itute the phllofophy of the aftronomer. 
 
 Tiie caufes of all phenomena are not only inferred 
 from the phenomena, but are charaiTlerifed by them ; 
 and we can form no notion of their nature but what we 
 conceive as competent to the phenomena therafelves. 
 The allronomical phenomena are affumed to be the mo- 
 tions of the boilief, which we call the fun, the p/anets, the 
 comeis, &c. The notion which we exprefs by the word 
 loJy in the prefent cafe, is fuppofed to be the fame with 
 that which we form of other objefts around us, to 
 which we give the fame name ; fuch as ftones, fticks, the 
 bodies of animals, &c. Therefore the notion which we 
 have of the caufgs of the celeftial motions muft be the 
 fame with that which we have of the caufes of motion 
 
 in thofe more familiar bodies. All men feem to have Vlewphori. 
 agreed in giving the name FoacEs, or moving forces, c^l ufe of 
 to the caufes of thofe familiar motions. This is a fi.taeteim- 
 gurative or metaphorical term, 'i'he true and otiginar 
 meaning of it is, the exertion which we are confcious of 
 making when we ourfelves put other bodies in motion. 
 Force, when ufed without figure, always fignifies the 
 exertion of a livii g and afting thing. We are more- 
 interefted in thofe productions of motion than in any 
 other, and our recoUedlions of them are more numerous. 
 Hence it has happened that we ufe the fame term to, 
 exp'.efs the caufe of bodily motion in general, and fay 
 that a magnet has force, that a fpring has force, that 
 a moving body has force. 
 
 Our own force is always exerted by the intervention of 
 our own body ; and we find that the lame exertion by 
 which we move a ftone, enables us to move another 
 man ; therefore we conceive his body to refcmble a 
 ftone in this refpeft, and that it alfo requires the exer- 
 tion of force to put it in motion. But when we refledt 
 on our employment of force for producing motion in a 
 body, we find ourfelves puzzled how to account for the 
 motion of our own bodies. Here we perceive no in- 
 tervening exertion but that of willing to do it ; yet w^ 
 fi^nd that we cannot move it as we pleafe. We alfo find 
 that a greater motion requires a greater exertion. It 
 is therefore to this exertion that the reflefting man re« 
 ftraiiis th>' term forci- ; and he acknowledges that every- 
 other uie of it is metaphorical, and that it is a refem- 
 
 blance
 
 ASTRO 
 
 blance in the ultimate cfFeft alone which difpofcs us to 
 employ the term in fuch cales : but we find no great 
 inconvenience in the want of another term. 
 
 We farther find, that our exertion is nccefTary, not 
 only for producing motion where there was none be- 
 fore, but alfo for producing any change of motion ; 
 and accurate obfervation thews us, that the fame force 
 is required for changing a motion by any given quan- 
 tity, as for producing that quantity where there was 
 none before. 
 
 Laftly, we are confcious of exerting force when we 
 refill the exerted force of another; and that an exertion, 
 perfedfly fimilar to this, will prevent fome very familiar 
 tendencies to motion in the bodies around us : thus an 
 exertion is necefi'ary for carrying a weight, that is, for 
 preventing the fall of that weight. 
 
 All thefe refcmblances between the effefts of our for- 
 cible exertions and the changes of motion which ac- 
 company the meeting, and fometimes the mere vicinity 
 of other bodies, juftify us in the ufe of this figurative 
 languaire. The refemblance is found to be the more 
 perfeft as we obferve it with more care, and, in Ihort, 
 appears to be without except oi. Bodies are therefore 
 faid to aS on each other, to rcj'ifi each other, to rejijl a 
 change of motion, &c. 
 
 Therefore, wherever we obferve a change of motion, 
 we infer the exiftence and exertion of a changing force; 
 and we infer the diredlion of that exertion from the di- 
 redlion of the change ; and the quantity of the exer- 
 tion, or intenfity of the force, from the quantity of the 
 change. 
 
 The ftudy of the caufes of the celeftial motions is 
 therefore hardly different from the ftudy of the motions 
 themfelves; lince the agency, the kind, and the degree 
 of the moving force, are immediate inferences from the 
 exiftence, ilie kind, and the quantity of the change of 
 motion. 
 Our 1' tion O""" notion of a moving power is that of a power 
 ofamovinj! which produces motion, that is, a fuccefiive change of 
 power. place. Continuation of the motion produced is there- 
 fore involved in the very notion of the production of 
 motion ; therefore the continued agency of the moving 
 power, or of any power, is not neceflary for the conti- 
 nuation of the motion. Motion is confidered as a ftate 
 or condition of the body ; there is not any exertion of 
 power therefore in the continuation of motion : But 
 every change is indicative of a changing caufe ; and 
 ■when the change is the fame, in all its circumftances, 
 the caufe is neceffarily conceived to be the fame, or 
 tqual. 
 
 The condition of a body, in refpeft of motion, can 
 differ from that of another equal body only in its di- 
 redlion and in its velocity. If the dlrefiions are the 
 fame, the difference of conditions can only be in the 
 difference of velocity. One body has a determination, 
 by which it would defcribe ten feet uniformly in a fe- 
 cond, if nothing changed this determination; the other 
 ^ has a determination, by which it would defcribe twenty 
 Weafure of feet in a Iccond. Each of thefe determinations are fup- 
 movmg pofed to be the effefts of forces afting fimilarly in every 
 refpeft Therefore thefe determinations are the only 
 meafures of thefe two forces; that is, moving forces are 
 conceived by us as having the proportion of the veloci- 
 ties which they produce in a body by afting in a man- 
 nsr perfectly fimilar. 
 
 35 
 
 N O M Y. 
 
 We can conceive a force afliiig equally or unequally. 
 If we fuppofe it to a£l equally or uniformly, we fnp- 
 pofe that in equal times it produces equal effedts ; that 
 is, equal determinations, or equal changes of dctermina. 
 tion. We have no other notion of equality or unifor- 
 mity of adlion. Therefore it mull produce equal aug- 
 mentations or diminutions of velocity ill equal times j 
 theref jre it muft produce an un'ifennly accelerated or re- > 
 tarded motion. Uniformly accelerated or nnarded mo- Arcciera. 
 tion is, therefore, the mark ot uniform or unvaried ac-''- nii.iioii 
 
 tion. In fuch a motion, the chansjes i-t velocitv are' "^"'^''^O' 
 
 , , V , ,° . . . ,' unvaried 
 
 proportional to tlie times trom the bcginni:-.g or the ac- jccion • 
 
 tion; and if the motion has begun from reft, the whole 
 acquired velocities are proportional to tiie times from 
 the beginning of the motion. In this cafe, the fpaces 
 delcribed are as the fquares of the times from the be- 
 ginning of the motion ; and thus we arrive r.t an often- 
 fible mark of the unvaried adlion of a moving force, 
 viz. fpaces increafing in the duplicati ratio of the times: ■ 
 for fpace and time are all that we can immediately ob- 
 ferve in any motion that is continually varying ; the 
 velocity or determination is only an inference, on the 
 fuppofition that the motion continues unchanged for 
 fome time, or that all action ceafcs for fome time. 
 
 This abftrafl reafoning is perfedlly agreeable to every 
 phenomenon that we can obferve with diftindlnefs. 
 Thus we cannot, or at leaft we do not, conceive the 
 weight of a body to vary i^s adlion during the fall. 
 We confider this weight as the caule of the tall — as the 
 moving force — and we conceive it to adl uniformly. 
 And, in fadl, a body falling freely, dcfcribes fpaces 
 which are proportional, not to the times, but to the 
 fquares of the times, and the fall is a motion uniformly 
 accelerated. In like manner, the motion ot a body 
 riTing in the air, in oppofition to gravity, is uniformly 
 retarded. ^ 
 
 This kind of motion alfo gives us a certain meafure And pivcj 
 of the acquired velocity, although there is not, in fadt, ■' . eafure 
 any fpace obferved to be uniformly delcribed during '^'' 
 any time whatever. in this motion we know that the 
 
 final determination, produced by the accumulated or 
 continued adlion of the unvaried force, is fuch that the 
 body would defcribe uniformly twice the fpace which it 
 has defcribed with the accelerated motion. 
 
 And it is by tliis method that we obtain the fimplcfl 
 meafure of any moving force, and can compare it with 
 another. If we obferve that by the adlion of one force 
 (known to be uniform by the fpaces being proportion- 
 al to the fquares of the times) ten feet have been de- 
 fcribed in a fecond, and that by ttie uniform adlion of 
 another force eighty feet are defcribed in two feconds, 
 we know that the lafl force is double of the fiifl : for 
 in the fecond motion. So feet were defcribed in two fe- 
 conds, and therefore 20 feet of this were defcribed in 
 the firfl fecond (becaufe the motion is uniformly acce- 
 lerated ; and at the end of a fecond, the firft body had 
 a determination by which it would defcribe 20 feet 
 uniformly in a fecond ; and the fecond body liad ac- 
 quired a determination by which it would liave de- 
 fcribed 40 feet uniformly in the next ftcoiid, had not 
 the moving force continued to adl on it, and n.adc it 
 really defcribe 60 feet with an accelerated motion. 
 
 Becaufe halves have the fame proportions with the 
 
 units of whicii ttiey are the halves, it is plain that we 
 
 may take the fpaces, defcribed in equal times with mo 
 
 £ 3 tiont 
 
 qu red ve- 
 locity.
 
 36 ASTRO 
 
 tions uniformly aecelernted, as meafures of the forces 
 which have produced thile motions. The velocities 
 7 generated are, however, the bed meafures. 
 Meafure of When the adlions of forces are not uniform, it is 
 the velocity jj,Qfg difficult to learn what is the meafure of the velo- 
 bv ad^ion ''''5' produced by their accumulated aftion. But it can 
 tiot uni- he determined with equal accuracy; that is, we can de- 
 form, termine wliat is the velocity which lunuld have been pro- 
 duced by the uniform aftiou of the force during the fame 
 time, and tlierefore we obtain a meafure of the force. 
 Mathematicians are farther able to demonflrate, that if 
 forces vary their continued aftion in any manner what- 
 ever, the proportion of the fpaces defcribed by two bo- 
 dies in equal times approaches nearer and nearer to the 
 proportion of the fpaces which they would defcribe in 
 thofe times by the uniform aftion of the forces, as the 
 times themfelves are fmaller ; and therefore whenever 
 we can point out the ultimate ratio of the fpaces de- 
 fcribed in equal limes, thefe times being diminifhed 
 without end, we obtain the ratio of the forces. 
 
 Motions may be changed, not only in quantity, by 
 acceleration or retardation, but alfo in direftion, by de- 
 Hefting a body from its former direftion. When a 
 ■plate VI. body, moving uniformly in the direftion AB (fig. i.), 
 has its motion changed in the point B, and, inflead of 
 defcribing BC uniformly in the next moment with the 
 former velocity, defcribes BD uniformly in that mo- 
 ment, it is plain that the motion BD will be the fame, 
 whether the body had begun to move in A, or in F, 
 or in G, or in B, provided only that its determination 
 to move, or its velocity, be the fame in all thofe points. 
 Complete the parallelogram BCDE. It is well known, 
 that if one force aft on the body which would make it 
 defcribe BC, and another which would make it defcribe 
 Intenfity ■^^' ^^^ body will defcribe BD. Hence we learn, 
 and direc- that when a body has the motion BC changed into the 
 tion of de- motion BD, it has been afted on in the point B by a 
 fleifting force which would have caufed a body at re II in B to 
 defcribe BE. Thus we can difcover the intenfity and 
 direftion of the tranfverfe force which produces any de- 
 fleftion from the former direftion. In general, the force 
 is that which would have produced in a body at reft that 
 motion BE, which, when compounded with the former 
 motion BC, produces the new motion BD. 
 
 Thefe two principles, viz. ift, that forces are propor- 
 tional to the velocities which they produce in the fame 
 circumftances, and, zd, the compofition of motion or 
 forces, will ferve for all the phyfical inveftigations in 
 aflronomy. All the celeftial motions are curvilineal, 
 and therefore are inftances of continual defleftion, and 
 of the continual aftion of tranfverfe or deflefting forces. 
 We muft therefore endeavour to obtain a general mea- 
 fure of fuch continual deflefting forces. 
 Meafure of Let two bodies A and a (fig. 2.) defcribe in the fame 
 thefe forces time the arches AC, a c of two circles. They are de- 
 obtained, flefted from the tangents AB, ab. Let us fuppofe that 
 the direftion of the deflefting forces is known to be 
 that of the chords AE, a e oi thefe circles. Let thefe 
 be called the deflective chords. Draw CB, ch pa- 
 rallel to AE, ae, and CD, cd parallel to AB, ab. 
 Join AC, ac, CE, and c e. Tt is plain that the angle 
 BAC is equal to the angle CEA in the alternate feg- 
 ment. Therefore ACD is alfo equal to it ; and, be- 
 caufe the angle CAD is common to the two triangles 
 CAD and EAC, thefe two triangles are fimilar, and 
 
 N O M Y. 
 
 AD : AC = AC 
 
 AE, and AD = ~. For fimi- 
 
 A AE 
 
 and b c z^ —. 
 ae 
 
 Therefore BC : i ^ = 
 
 lar reafons a (/ = — , But AD and a </ are rcfpec- 
 lively equal to BC and b c. Therefore BC = ^£!, 
 
 AC rtf' 
 
 aeS-'"-" 
 
 'BC:hc = AQ ■Xae-.ac'Y AE. But BC and b c be- 
 ing rcfpeftively equal to AD and a d, are equal to the 
 fpaces through which the deflefting forces would have 
 impelled the bodies from a ftate of reft in the time of 
 defcribing the arches AC, a c. Therefore, when thefe 
 times are diminifhed without end, the ultimate ratio of 
 AD and a d is the ratio of the forces which defleft the 
 bodies in the points A and a. But it is evident that 
 the ultimate ratio of AC to a f is the ratio of the ve- 
 locity in the point A to the velocity in the point a ; 
 becaufe thefe arches are fuppofed to be defcribed in 
 the fame or equal times. Therefore the deflefting for- 
 ces, by which bodies are made to defcribe arches of 
 circles, are to each other as the fquares of the velocities 
 direftly, and as the defvfiive cords of thofe circles in- 
 vcrfely. This ratio may be expreflfed fymbolically thus, 
 
 F :/ = -7^ : — ; or thus, in a proportional equation, 
 
 c 
 It is eafy to fee that in this laft formula/ exprefles 
 direftly the line be, or the fpace through which the 
 body is aftually made to deviate from reftilineal motion 
 in the time of defcribing the arch a c. It is a third 
 proportional to o c the defleftive chord, and ae the arch 
 of the circumference defcribed in a fmall moment of 
 time. This is the meafure afforded immediately by ob» 
 fervation. We have obferved the arch AC that is de- 
 fcribed, and know the direftion and the length of AE 
 from fome ciixumftances of the cafe. The formula which 
 comes to us, when treating this queftion by the help of 
 
 2 1)" . . 
 
 fluxions, hf:z . This is perhaps a more proper 
 
 expreffion of the phyfical faft ; for it expreflTes twice 
 the line be, or the meafure of the velocity which the 
 deflecting force would have generated in the body by 
 afting on it during the time of its defcribing the arch 
 a c. But it is indifferent which meafure we take, pro- 
 vided we always take the fame meafure. The firft ma- 
 thematicians, however, have committed miftakes by mix» 
 ing them. 
 
 The planets, however, do not defcribe circles : but 
 all the curves which can be defcribed by the aftion of 
 finite defledfing forces are of fuch a nature, that we can 
 defcribe a circle through any point, having the fame 
 tangent, and the fame curvature which the planetary 
 curve has in that point, and which therefore ultimately 
 coalefces with it. This being the cafe, it is plain that 
 the planet, while pafiing through a point of the curve, 
 and defcribing an indefinitely fmall arch of it, is in the 
 fame condition as if defcribing the coincident arch of 
 the equicurve circle. Hence we obtain this moft gene- 
 ral propofition, that the tranfverfe foree ty tuhkh a pla- 
 net is made to defcribe any curve, is diredly as the fquare 
 of its velocity, and inverfely as the defle8ive chord of the 
 equicurve circle. 
 
 Farther : The velocity of a body in any point A
 
 A S T R 
 
 (fig. 2.) of the curve, is equal to that wliich the deflec- 
 tive force in that point would generate in the body by 
 aAlng uniformly on it along AF, one-fourth part of 
 the defle<5tive cord AE of the equicurve circle. It is 
 the fame which the body would acquire at F, after a 
 uniformly accelerated motion along AF. 
 
 For it is certain that there is fome length AF, fuch 
 that the velocity acquired at F is the fame with the ve- 
 locity in the point A of the curve. Draw FG parallel 
 to the tangent, and join AG. Make the arch AC I 
 r= 2AF. Then, becaufe the fpace defcribed with a 
 uniformly accelerated motion is one half of the fpace 
 which would be uniformly defcribed with the final ve- 
 locity, the arch ACI would be uniformly defcribed 
 with the velocity which the body has at A in tlic time 
 that AF is defcribed with the uniformly accelerated mo- 
 tion ; and the arch AB will be to the arch A I as the 
 time of defcribing AB to that of defcribing AI ; that 
 is, as the time of falling through AD to that of falling 
 through AF. But the motion along AF being uni- 
 formly accelerated, the fpaces are as the fquares of the 
 times. Therefore AD is to AF as the fquare of the 
 arch AC to the fquare of the arch AI. But AD is 
 to AF as the fquare of the chord AC is to the fquare 
 of the chord AG. Therefore the arch AC is to the 
 chord AC as the arch AI is to the chord AG. But the 
 arch and chord AC are ultimately in the ratio of equa- 
 lity. Therefore the chord AG is equal to the arch AI. 
 Therefore AG is double of AF. But becaufe the tri- 
 angles FAG and GAE are fimilar, AF is to AG as 
 AG to AE ; and therefore AE is double of AG and 
 quadruple of AF. Therefore the velocity at A in the 
 curve is that which would be produced by the uniform 
 impulfe of the deflefting force along the fourth part of 
 le the defleftive chord of the equicurve circle. 
 Twoufefi:! Thefe two affeftions or properties of curvilineal mo- 
 affeaionsofti'ofij ^^g of t},g moft extenlive ufe, and give an ealier 
 
 _ ■ folution of moft queftions than we obtain by the more 
 
 motions. , 1 ^ , , r ,1 ■ 1 
 
 uiual metnods, and delerve to be kept m remembrance 
 
 by fuch as engage much in the/difcuflion of queftions 
 of this kind. 
 
 Thus the inveftigatioi) of the forces which regulate 
 the planetary motions is reduced to the talk of difco- 
 vering the velocity of the planet in the different points 
 of its orbit, and the curvature in thofe points, and the 
 II pofition of the defleftive chords. 
 Phyfical The phyfical fcience of aftronomy muft confift in the 
 
 cience ot difcovery of the general laws which can be afBrmed with 
 refpedt to the exertion of thofe forces, whether with re- 
 , fpeft to their direftion or the intenfity of their aftion. 
 
 If the mechanician can do more than this, and (how that 
 every motion that is obferved is an immediate or remote 
 confequence of thofe general laws, he will have comple- 
 ted the fcience, and explained every appearance. 
 Com(.leicd This has accordingly been done by Sir liaac Newton 
 by Newion and his followers. Sir Ifaac Newton has difcovcred the 
 and general laws which regulate the exertions of thofe forces 
 
 which produce the planetary motions, by reafoning from 
 general phenomena which had been obferved with a cer- 
 tain precifion before his time ; and has alfo fhown that 
 certain confiderable deviations from the generality which 
 he fuppofed to be perfeft were necelTary confequences 
 of the very univerfality of the phyfical law, although the 
 phenomenon was not fo general as was at firft imagined. 
 He has gone farther, and has pointed out fome other 
 
 O N O M Y. 57- 
 
 minute deviations which muft refult from the phyfical 
 law, but which the art of obfervation was not then fuf- 
 ficiently advanced to difcover in the phenomena. This 
 excited the efforts of men of fcience to improve the art 
 of aftronomical obfervation ; and not only have the inti-,,. ,'■?, 
 mations of Newton been verified by modern obfervation, ^^s 
 but other deviations have been difcovered, and, in pro- 
 cefs of time, have alfo been fliown to be confequences 
 of the fame general law of Jigency : And, at this pre- 
 fent day, there is not a fingle anomaly of the planetary- 
 motions which has not been fhown to be a modification 
 of one general law wliicli regulates the action ; and 
 therefore charafteriies the nature of that fingle force 
 which aftuates the whole fyftem of the fun, and his at- 
 tending planets and comets. 
 
 It was a moft fortunate circumftance that the confti- 
 tution of the folar fyfiem was fuch that the deviations 
 from the general law are not very confiderable. The 
 cafe might have been far otherwife, although the law, 
 or nature of the planetary force, were the fame, and 
 the fyftem had been equally harmonious and beautiful. 
 Had two or three of the planets been vaftly larger than 
 they are, it would have been extremely difficult to dif- 
 cover any laws of their motion fufficiently general to 
 have led to the fufpicion or the difcovery of the univer- 
 fal law of adion, or the fpccific circumftance in the pla- 
 netary force which diftinguiflies it from all others, and « 
 charafterifes its nature. But the three laws of the pla- 
 netary -motions difcovered by Kepler were fo nearly- 
 true, at leaft with refpett to the primary planets, that 
 the deviations could not be obferved, and they were 
 thought to be exadt. It was on the fuppolition i/jat 
 they ivere exad, that Newton affirmed that they were 
 only modifications of one law ftill more general, iiay- 
 univerfal. 
 
 We fhall follow in order the fteps of this inveftiga- 
 tion. 
 
 Sir Ifaac Newton took it for, granted, that the fun The fteps- 
 and planets conlifted of matter which refemblcd thofe hy w hi :h 
 bodies which we daily handle, at leaft iji relpecT; of'"''' P''"" 
 their mobility ; and that the forces which agitate*^" 
 them, confidered merely as moving forces, but without 
 confidering or attending to their mode of operation, 
 were to be inferred, both as to their direftlcn and as - 
 to their intenfity, from the changes of motion which 
 were afcribed to their agency. He firft endeavoured 
 to difcover the direBion of that tranfvtrfe force by 
 which the planets are made to difcover curve lines, 
 Kepler's firft law furniflied him with ample means for 
 this difcovery. Kepler had difcovered, that, the right 
 line joining the fun imd any planet defcribed areas probor- 
 tional to the times. Newton demonllrated, that if a. 
 body was fo carried round a fixed point fituated in the 
 plane of its motion, that the right line joining it with 
 that point defcribed areas proportional to the tiiiies, 
 the force which deflected it from an uniform reftilineal 
 motion was continually diredted to that fixed point. 
 This makes the 2d propofition of his immortal vvorlt 
 The Mathematical Principles of Natural Philofophy, and. 
 it is given in the article Astronomy of the Encyclo- 
 paedia Britannica, (J :6o. 
 
 Hence Sir Ifaac Newton inferred, that the primary 
 planets were retained in their orbits by a force conti- 
 nually direfted to the fun ; and, becaufe Ki pier's law 
 of motion was alfo obferved by. the fecondary planets
 
 38 
 
 ASTRO 
 
 In tlielr revolutions round their refpcflive primary pla- 
 ,. liCts, this inference was extended to them. 
 Centripetal From the circi.milance that tl)e planetaiy deflcdliDg 
 force-. forces in the diifcient points of the orbit arc always di- 
 
 rcfted toward one point as to a centre, they have been 
 
 IS called CENTRIPETAL FORCES. 
 
 Velocity of From this propofition may be dednced a corollary 
 \''''h' '" ^^i^^'i eftablidies a general law of the motion of any 
 lent iii'ints P'^"^' '" ^''^ different parts of its orbit, namely, that 
 ofitsorbit. t''*^ velocity which a planet has in the different points 
 of its path are inverfely proportional to the perpendi- 
 culars drawn from the fun on the tangents to the orbit 
 in thofe points refpetlive"ly. For, let AB, ah (^fig. 3.) 
 be two arches (extremely fmal!),defcribed in equal timts, 
 thefe arches muft be ultimately proportional to the ve- 
 locities with which they are defcribed. Let SP, S p 
 be perpendicular to the tangents AP, a p. The tri- 
 angles ASB, a 'Si b are equal, becaufe equal areas are 
 defcribed by the radii veSorrs SA, S a, in equal times : 
 but in equal triangles, the bafes AB, a i, are recipro- 
 cally as their heights SP, Sp, or AB : a i = S p : SP. 
 This corollary gives us another expreflion of the ra- 
 tio of the centripetal forces in different poii.ts A and a of 
 a curve. We faw by a former propolition, that the force 
 at A (fig. 2.) is to the force at a as AC" X a £ to 
 a c^ X AY,, which we may exprefs thus: F:/^ V 
 X f : 1)' X C. If we exprefs the perpendiculars SP, S p 
 {in fig. 3.) by the fymbols P,/>, we have V" : v~=zp'' : P^, 
 and therefore F :/ = / Xc : P' X C. T/ie centripetal 
 forces in different points of an orhit are in the ratio com- 
 pounded of the inverfe duplicate ratio of the perpendiculars 
 dranvn to the tangents in thofe points from the centre of 
 forces, and the inverje ratio of the dcfledive chords of the 
 17 equicurve circles. 
 Law of We are now in a condition to determine the law of 
 
 action of aftion of the centripetal force by which a planet is re- 
 . r ' ' tained in its orbit round the fun, or the relation which 
 ' fubfills between the intenfity of its aftion and the di- 
 ftance of the planet from the fun : for we know the el- 
 liptical figure of the orbit, and we can draw 3 tangent 
 to it in any point, and a perpendicular from the iun to 
 that tangent. 
 
 Kepler's fecond law or obfervation of the planetary 
 motions was, that each primary planet defcribed an ellipfe, 
 having the fun in one focus. It is eafy to lliow, even 
 without any knowledge of the geometrical properties of 
 the ellipfe, what is the proportion of the intenfitics of 
 the deflefting force at the aphelion and perihelion (fee 
 fig. 4.) At thofe two points of the orbit, the motion 
 of the planet is at right angles to the line joining it 
 with the fun. Therefore, fince the areas defcribed in 
 equal times are equal, the arches defcribed in equal times 
 mull be inverfely at the dillanccs from the fun ; or the 
 velocities mull be inverfely as the diilances from the 
 fun. But the curvature in the aphelion and perihelion 
 is the fame ; and therefore the diameters of the equi- 
 curve circles in thofe points are equal. But thofe dia- 
 meters are, in this particular cafe, what we called the 
 defleftive chords. Therefore, calling the aphelion and 
 perihelion diflances D and d, the velocities in the aphe- 
 lion and perihelion V and -v, let the common defledlive 
 chord be C. Then we have F :/ = V= X C : i)* X C, 
 = V^ : XT', := d'^ : D'. That is, the forces which de- 
 fleft the planet in the aphelion and perihelion are in- 
 verfely as the fquares of the diflances from the fun. A 
 
 N O M Y. 
 
 perfon almofl ignorant of mathematics may fee the trutu 
 of this by looking' into a table of natural verfcd fines. 
 He will obfcrve, that the verfed fine of one degree is 
 quadruple the verfed fine of half a degree, and fixteen 
 times the ve; fed fine of a quarter of a degree ; in fhort, 
 that the verfed fines of fmall arches are in the propor- 
 tion of the fquares of the arches. Now fince the arches 
 defcribed in equal times are inverfely as the diflances, 
 their verfed fines are inverfely as the fquares of the di- 
 flances. But thefe verfed fines are the fpaccs through 
 which the centripetal forces at the aphelion and peri- 
 helion defleft the planet from the tangent. There- 
 fore, ?cc. 
 
 Thus we have found, that in the aphelion and peri- 
 helion the centripetal force afts with an intenfity that 
 is proportional to the fquares of the diflances inverfely. 
 As thefe are the extreme fituations of a planet, and as 
 the proportion of the aphelion and perihelion diflances 
 are conifiderably different in the different planets, and 
 yet this law of a£lion is obferved in them all, it is rea- 
 fonable to imagine that it holds true, not in thofe fitua- 
 tions only, but in every intermediate fituation. But a 
 conjefture, however probable, is not fufBcient, when 
 we aim at accurate fcience, and it is neceffary to exa- 
 mine whether tliis law of aftion is really obferved in 
 every point of the elliptical orbit. „ 
 
 For this purpofe it is neceffary to mention fome geo- Dem„n(jrj. 
 metrical properties of the ellipfe. Therefore let ADBE ted with re- 
 (fig. 4.) be the elliptical orbit of a planet or comet, '^P'^'^ '" '''* 
 having the fun in the focus S. Let AB be the tranf-^*'' • 
 verfe axi.s, and DE the conjugate axis, and C the centre. 
 Let P be any point of the ellipfe. Draw PS through 
 the focus. Draw the tangent PN, and SN from the 
 focus, perpendicular to PN. Draw PQ^per|)endicular 
 to PN, meeting the tranfverfe axis in Q. Draw QO 
 parallel to PN, meeting PS in O. Alfo draw QR per- 
 pendicular to PS. Bifea PO in T. 
 
 It is demonftrated in the treatifes of conic feiflions, 
 that PO is one half of the chord of the equicurve or ol- 
 culating circle drawn through the point P. Therefore 
 PO is one half of the defledfive chord of the planetary 
 orbit. It is alfo demonftrated, that PR is one half of 
 the parameter or latus re8um of the tranfverfe axis AB, 
 or that it is the third proportional to AC and DC. 
 Therefore PR or D r is of the fame conflant magni- 
 tude, ill whatever part of the circumference the point 
 P is taken. 
 
 It is evident that the triangles NSP, RPQj and 
 QPO, are all fimilar, by reafon of the parallels PN, QO, 
 and the right angles SNP, PRQ, PQO. Therefore 
 we have PR : Pt|^= PQj PO. Therefore PR : PO 
 = PR= : PQ^N = SN' : SP^ Therefore PR X SP' 
 = PO X SN'. But the htus reSum L is equal to 
 twice PR, and the defleftive chord C is equal to twice 
 PO. Therefore L X SP' = C X SN'. But we have 
 feen, that when a curve is defcribed by nieans of a cen- 
 tripetal force, fo that areas are defcribed proportional 
 to the times, and therefore the velocities are reciprocal- 
 ly proportional to the perpendiculars drawn from the 
 centre of forces to the tangents, the forces are inverfely 
 proportional to C X SN'. Therefore, in the elliptical 
 motion of the planets, the forces are inverfely propor- 
 tional to L X SP' ; and fince L is a conftant quantity, 
 the centripetal forces are inverfely proportional to SP', 
 or to the fquares of the diflances from the fun. 
 
 Thus
 
 »9 
 
 ASTRO 
 
 Thus it appears that, with refpeft to any individual 
 planet, the centripetal force which continually defleds 
 it from the tangent to its orbit diminilhes in the inverfc 
 Obferveiin duplicate ratio of the diftance from the fun. The lame 
 the motion thing is obferved to be very nearly true in the moon's 
 •f'l^^""^"" motion round the earth, and in the motion of fuch fa- 
 tellites of Jupiter and Saturn as defcrihe orbits which 
 are fenfibly elliptical. It is nlfo obferved in the motion 
 of the comets, at leaft in that which appeared in 1682 
 and in 1759. 
 
 It was therefore very natural for Sir Ifaac Newton to 
 examine whether the like diminution of force obtained 
 in the adion of this force on different planets ; that is, 
 whether the defleftlon of the earth from the tangent of 
 its orbit was to the fimultaneous delleiflion of Jupiter 
 as thf fquare of Jupiter's diftance from the fun to the 
 fquaie of the earth's diftance. This was very probable, 
 but by no means certain. Its probability is very great 
 indeed, when we know that a comet moves fo in its or- 
 bit that its defletlions in equal times are inverfely as 
 the fquares of its dillances from the fiui, and that the 
 comet palfes through the orbits of all the planets ; and 
 when at the fame diftance from the fun as any one of 
 them, it fuffers the fame deflexion with it. Newton 
 therefore calculated the aflual fimultaneous defleftions 
 of the different planets, and found them agreeable to 
 
 . ,^? this law. But it was defirable to obtain a demonftra- 
 And r)e- . . , . . r • • 1 mi • 
 
 monftrated tion ot this important propolition m general terms. 1 nis 
 
 in general was fupplled by Kepler's third general ol)fervation of 
 teims. (},e motions, viz. that the fquares of the periodic times of 
 the different planets 'were proportional to the cubes of their 
 mean dijlances from the fun. The orbits of the planets 
 are io nearly circular, that we may_ fuppofe them ex- 
 adly fo in the prefcnt queflion, without any remark- 
 able error. In this cafe, then, the defledlive chords are 
 the diameters of the orbits (for DS is equal to AC), 
 and are proportional to the diilances, which are their 
 halves. The centripetal forces, being proportional to 
 
 — , are proportional to —7, when d is the radius of the 
 
 orbit, or the mean diftance from the fun. But the ve- 
 locity in a circular orbit is as the circumference direflly, 
 and as the time of a revolution inverfely. Therefore, 
 
 . 'Z' r ■ 
 
 inftead of •»% we may write *-r, and then the forces will 
 
 be proportional to — , or to — ; that is, direftly as the 
 ^ '^ t^d t^ 
 
 diftances, and inverfely as the fquares of the times of re- 
 volution. But, by Kepler's obfervation, f is propor- 
 tional to d3. Therefore the centripetal forces are pro- 
 portional to —7, or to -J-; ; that is, inverfely as the 
 
 fquares of the mean diftar.ces from the fun. 
 
 But fince the orbits of the planets are not accurate 
 circles, this determination is but an approximation to 
 the tiuth, and therefore infufficient for the foundation 
 of fo important a propofition ; at any rate, it will not 
 apply to the comets, whofe orbits are very far from be- 
 ing circular. We muft obtain a more accurate demon- 
 ftration. 
 
 Therefore draw SD (fig. 4.) to the extremity of the 
 conjugate axis, and bifeflr it in t. About S, with the 
 radius SD, defcrihe the circle DFG. Let D J, D J be 
 equal fmall arches of the ellipfe and the circle. Join 
 
 N O M Y. 39 
 
 d S, J S. It is well known that DS Is h ilf of the chord 
 of the equicurve circle at D, and therefore D/ is one 
 fourth part ot it. It ha-, been demoiiftrated, that the 
 velocity in any point D of a curve, delctibcd by means 
 of a deflexbting force, is that which the force in that 
 point would communicate to it by uniformly impelling 
 it along the fourth part of the delleclive chord, that is, 
 along D /. But if a body revolved round S in a circle 
 DFG, its velocity in that circle would be that which 
 the defledling force would communicate to it by uni- 
 formly impelling it along one-fourth of the diameter, that 
 is, along Tit. Therefore the planet, if pri.je6\ed in the 
 direftion D J, with the velocity which it has in the 
 point D of the ellipfe, would defcrihe the circle DFG 
 by the art ion of the centripetal force. Farther, it 
 would del'cribe it in tiie fame time that it defcribes the 
 ellipfe ; for becaufe the velocities are equal, tiie areas 
 DS^/, DS "f are defcibed in the fame time. But the 
 bafes Y) d, D J being equal, thefe areas are as their 
 heights Sn (or CD), and SD (or CA). But becaufe 
 the diameter of the circle is equal to AB, the area of 
 the whole ellipfe is to the area of tlie circle as CD is ta 
 CA ; that is, as the area DS d to the area DS J de- 
 fcribed in the fame time. Therefore the elliptical and 
 circular areas are fimllar portions of the ellipfe and cir- 
 cle ; and therefore the times of defcribing them are fi- 
 milar portions of the whole revolutions in the ellipfe. 
 and in the circle. Therefore thefe revolutions are per- 
 formed in equal times. 
 
 And thus it follows, that if all the planets and co- ' 
 mets were projefted, when at their mean diftances from 
 the fun, perpendicularly to the radii vetlores, they would 
 defcribe circles round the fun, and the fquares of their 
 periodic times would be proportional to the cubes of 
 their mean diftances from the fun, as Kepler has ob- 
 ferved ; and therefore the centripctid forces would 
 be inverfely as the fquares of their diftances from the 
 fun. „ 
 
 They are not different forces therefore which retain All the pJa- 
 the different planets in ttieir refpirclive orbits, but one"'^'' '^^*;''- 
 force, aftingby the fame law upon them all. We mayrefpefliv^ 
 either conceive it as an attraffive force, exerted by the orbit* by 
 fun, or as a tendency m each planet; nay, nothin«-one and the 
 hinders us from conceiving it as a force external, both'^*™' "' 
 to fun and planets, impelling them towards the fun. It 
 may be the impiilfe of a ftrcam of fluid moviu'T conti- 
 nually towards the fun. Sir Ifaac Newton did not con- 
 cern himfelf with this queftion, but contented himfelf 
 with the difcovery of the law according to which its ac- 
 tion was exerted. The fteps of this inveftigation fliew- 
 ed him, that a body, projected in any direction what- 
 ever, and with any velocity whatever, and fubjefted to 
 the aClion of a force directed to the fun, and inverfely 
 proportional to the fquaie of the diftance from the fun, 
 will neceffarily defcribe a conic feftion, having the fun 
 in the focus. This will be a parabola, if the velocity 
 of projeftion be that whlcli the centripetal force in that 
 place would communicate to the body by afting on it 
 uniformly along a line equal to half its diftance from the 
 fun. If the velocity be greater than this, the path will' 
 be a hyperbola ; If the velocity be lefs than this, the 
 path will be an elliptical orbit, in which the body will 
 revolve for ever round the fun. 
 
 The 3d Keplerean law is alfo obferved in the revolu- 
 tion* of the fateliites of Jupiter, Saturu, and the lately 
 
 sJifcovered;
 
 40 ASTRONOMY. 
 
 •lifcovered planet ; and we mud infci- from it, that they cal motion round the earth. At new moon, her ten- a: 
 are retained in their orliits round their refpcitive pri- dency to the fun exceeds the earth's tendency to him, ""' «•''- 
 mary planets, by forces whofc intenfity decreafes ac- and this excefs will diminifh her tendency to the earth, gf^^.""^ 
 cording to the fame law of the diftanccs. Alfo the el- and her motion will be lefs incurvatcd, fo that fhe moon's 
 liptioal motion of the moon round the earth, fiiews that will retire a little from the earth. At full moon, the tnotion 
 the force by which (he is retained in her orbit varies in earth's tendency to the fun exceeds the moon's tendcn- 
 the fame proportion of the diilances. But when we cy to him, and the earth will feparate a little from the 
 compare the motion of a fatellite of Jupiter with that moon, fo that the relative orbit will again be lefs incur- 
 of one of tl)e fatellitcs of the other two planets, we lind vated. In the quadratures, the impulfe on the moon Is 
 that the proportion does not hold. We (hall find that, indeed equal to that on the earth, but not parallel, and 
 at equal diftanccs from Jupiter and Saturn, the force tends to make the moon approach the earth, and increafe 
 tcjward Jupiter is almoft thrice as great as the force to- the curvature of her orbit. In other fituations of the 
 ward Saturn. We fliall alfo find that the force toward moon, this want of equality and parallelifm of the forces 
 Jupiter is three hundred times greater than the force ading on the earth and moon, muft produce other dif- 
 which retains the moon in its elliptical orbit round the turbances of the regular elliptical motion. 
 earth, when afting at the fame dillance. Newton faw this at once ; and, to his great delight. 
 Since a force direftcd to the fun, and inverfely as the he faw that the great deviations from regular motion, 
 fquare of the diilance, is thus found to pervade all the which had been difcovered by Ptolemy and TychoBrahe, 
 planetary orbits, it is highly improbable that it will not called the Annual Equation , the Variation, and the Evec- 
 affcft the fecondary planets alfo. The moon accompa- tion, were fuch as moft obvioufly refulted from the re- 
 nies the earth in its motion round the fun. It may ap- gular influence of the fun on the moon. The firft de- 
 pear fufRcient for this purpofe, that the moon be re- viation from the regular elliptical motion is occafioned 
 tained in its orbit by a force direfted to the earth. Were by the increafe of the fun's difturbing force as the earth 
 the moon connefted with the earth by a rope or chain, approaches the perihelion ; and it enlarges the lunar or- 
 this would be true ; for the earth could get no motion bit, by diminifhing the tendency to the earth, and in- 
 without dragging the moon along with it : but it is creafes the periodic time. The fecond arifes from the 
 quite otherwile with bodies moving in free fpace, with- direction of the difturbing force, by which it accelerates 
 out any material connexions. When a body that is the moon's angular motion in the fecond and fourth 
 moving uniformly in a ftraight line is accompanied by quadrants of her orbit, and retards it in the firft and 
 another which defcribes around it areas proportional to third. The lall affedls the eccentricity of the orbit, by 
 the times, the force which coniinually deflefts this fa- changing the ratio of the whole or compound tendency 
 tellite is always direfted to the moving central body.' of the moon to the earth in her perigee and apogee. 
 This is eafily feen ; for whatever be the mutual aftion This fuccefs incited him to an accurate examination of ,, 
 of two bodies, and their relative motions in confequence the confequences of this influence. It is the boaft of May becat- 
 fuMcaad to'-^f this aiSion, if the fame velocity be imprefled at once this difcovery of the law of the planetary defleflions, culited 
 this folar on both bodies in the fame direilion, their mutual ac- that all its effefts may be calculated with the utmoft ^"'.i." P"'*" 
 tions and relative motions will be the fame as they precifion. The part of the moon's defleftion toward 
 would have been without this common impulfe. Thus the fun, which is neither equal nor parallel to the fimul- 
 every thing is done in a fliip that is failing fteadily in taneous defleftion of the earth, may be feparated from 
 the fame manner as if ftie were at reft. If therefore the the part which is equal and parallel to it, and it may 
 moon be obferved to defcribe areas round the earth, be called the fun's difturbing force. Its proportion to 
 which 2X^ precifeh proportional to the times, while the the moon's defleftion towards the earth may be accu- 
 earth moves in an orbit round the fun, we muft infer that rately afcertaincd, and its inclination to the line of the 
 the moon receives, in every inftant, an .impulfe the fame moon's motion in every point of her orbit may be point- 
 in every refpeft with what the earth receives at the fame ed out. This being done, the accumulated effedl of 
 inftant; or that the moon is afted on by a force paral- this difturbing force after any given time, however va- 
 lel to the earth's diftance from the fun, and proportion- riable, both in direftion and intenfity during this time, 
 al to the fquare of that diftance inverfely. Now this may be determined by the 39th and other propolitionsof 
 is very nearly true of the lunar motions ; and we the firft book of the Mathematical Principles of Natural 
 muft infer that the moon is fubjefted to this folar ac- Philofophy. And thus may the moon's motion, when 
 
 The latel- 
 Iitcs of" aU 
 
 adtion. 
 
 tion, or this tendency to the fun. The fame muft be 
 affirmed of the fatellites of the other planets. 
 
 But a force inverfely proportional to the fquare of 
 the earth's diftance from the fun is not what the univer- 
 
 fo difturbed, be determined and compared with her mo- 
 tion really obferved. 
 
 All this has been done by Sir Ifaac Newton vi-ith the 
 moft aftonifhing addrefs and fagacity,yi/3 malheji Jacem 
 
 (ality of the law requires: It muft be inverfely as the prefennle, partly in the Principia, and partly in his 
 
 fquare of the moon's diftance from the fun; and it muft Lun^e Theoria. This invelligatlon, whether we con- 
 
 iiot be parallel to the earth's diftance from the fun, but fider the complete originality of the whole procefs, or 
 
 mud be direfted toward the fun ; and therefore, in the the ingenuity of the method, or the fagacity in feeing 
 
 (juadratures, it muft converge to the earth's radius -oec- and clearly difcriminating the different circumftances of 
 
 t'jr. Therefore, fince a force having the above men- the queltion, or the wonderful fertility of refource, or 
 
 lioned conditions will allow the defcription of areas the new and moft refined mathematical principles and 
 
 round the earth exaftly proportional to the times, a methods that he employed — muft ever be confideied as 
 
 force afting on the moon, inverfely proportional to the the moft brilliant fpecimen of human invention and rea- 
 
 Jquare of her diftance from the fun, and directed exaft- foning that ever was exhibited to the world. 
 
 Jy to the fun, is incompatible with the accurate ellipti- In this inveftigation Newton not only determined the 
 
 quantity,
 
 il* 
 
 4? 
 
 The fecU' 
 lar equa- 
 
 ilance 
 
 ASTRO 
 
 quantity, the period, and the changes of thofe inequa- 
 lities, which had been fo confiderable and remarkable as 
 to be obferved by former altronomera, and this with an 
 cxaftnefs far furpafTitig what could ever be attained by 
 mere obfervation ; but he alfo pointed out feveral other 
 periodical inequalities, which were too fmali, and too 
 much implicated with the reft, ever to be difcovered or 
 to be feparated from them. We do not fay that he 
 completed the theory of the lunar motions; but he 
 pointed out the methods of inveftigation, and he fur- 
 nirtied all the means of profecuting it, by giving the 
 world the elements of a new fpecies of mathematics, 
 witliout which it would have been in vain to attempt it. 
 Both this new mathematics, and the methods of apply- 
 ing it to fuch queftions, have been affiduoufly ftudied 
 and improved by the great mathematicians of this cen- 
 tury ; and the lunar theory has been carried to fuch a 
 degree of perfeftion, that we can compute her place in 
 the heavens for any paft age without deviating above 
 one minute of a degree from the aftual obfervation. 
 
 There is one empirical equation of the moon's mo- 
 tion which the comparifon of ancient and modern eclip- 
 fes ohhges the aftronomers to employ, without being 
 able to deduce it, like the reft, a priori, from the theory 
 of an univerfal force inverfely proportional to the fquare 
 of the diftance. It has therefore been confidered as a 
 ftumbling block in the Newtonian philofophy. This 
 tion of the jg ^^,1,3^ jg called the fecular equation of the moon's mean 
 moons . rru .• • j j 1 r 
 
 mean di- 'notion. 1 he mean motion is deduced from a compari- 
 fon of diftant obfervations. The time between them, 
 being divided by the number of intervening revolutions, 
 gives the average time of one revolution, or the mean 
 lunar period. When the ancient Chaldean obfervations 
 are compared with thofe of Hipparchus, we obtain a 
 certain period ; when thofe of Hipparchus are compa- 
 red with fome in the 9th century, we obtain a period 
 fomewhat (horter ; when the laft are compared with 
 thofe of Tycho Brahe, we obtain one ftill ftiorter ; and 
 when Brabe's are compared with thofe of our day, we 
 obtain the fhorteft period of all — and thus the moon's 
 mean motion appears to accelerate continually ; and the 
 accelerations appear to be in the duplicate ratio of the 
 times. The acceleration for the century which ended 
 in 1700 is about 9 feconds of a degree ; that is to fay, 
 the whole motion of the moon during the 17th centu- 
 ry muft be increafed 9 feconds, in order to obtain its 
 motion during the igth; and as much muft be taken 
 from it, or added to the computed longitude, to obtain 
 its motion during the i6th; and the double of this muft 
 be taken from the motion during the 16th, to obtain 
 its motion during the 15th, &c. Or it will be fuflicient 
 to calculate the moon's mean longitude for any time 
 paft or to come by the fecular motion which obtains in 
 the prefent century, and then to add to this longitude 
 the produft of 9 feconds, multiplied by the fquare of 
 the number of centuries which intervene. Thus having 
 found the mean longitude for the year 1200, add 9 fe- 
 conds, multiplied by 36, for fix centuries. By this me- 
 thod we fhall make our .calculation agree with the moft 
 ancient and all intermediate obfervations. If we negle£l 
 this correftion, we ftiall differ more than a degree from 
 the Chaldean obfervations of the moon's place in the 
 heavens. 
 
 The mathematicians having fucceeded fo completely 
 in deducing all the obferved inequalities of the planeta> 
 SuppL. Vol. 1. Part. I. 
 
 N O M Y. 
 
 4J 
 
 1.5 
 
 ry motions, from the fingle principle, that the deflcft- 
 iiig forces diminilhcd in the invcvfe duplicate ratio of 
 the diftances, were fretted by this excption, the reality 
 of which they could not conteft. Many opinions were 
 formed about its caufe. Some have attempted to de- 
 duce it from the aftion of the planets on the moon ; 
 others have deduced it from the oblate form of the 
 earth, and the tranflation of the ocean by the tides ; 
 others have fuppofed it owing to the reliftance of the 
 ether in the celeftial fpaces; and others have imagined 
 that the action of the defledling force requires time for 
 its propagation to a diftance: But their deduftions have 
 been proved unfatisfadlory, and have by no means the 
 precifion and evidence that have been attained in the 
 other queftions of phyfical aftronomy. At lall M. de 
 la Place, ot the Royal Academy of Sciences at Paris, 
 has happily fucceeded, and deduced the fecular equation 
 of the moon from the Newtonian law of planetary de- 
 fleftion. It is produced in the foUownng manner : 
 
 Suppofe the moon revolving round tlie earth undi-™ , 
 fturbed by any deflection toward the fun, and that thefron""^ 
 time of her revolution is cxaftly afcertaiiied. Now let Newtoniari 
 the influence of the fun be added. I'his diminifhes her '** "f I''^- 
 tendency to the earth in oppofition and conjundlion, ^''^" '^^" 
 and increafes it in the quadratures: but the diminutions ^ '°"' 
 exceed the augmentations both in quantity and dura- 
 tion ; and the excefs is equivalent to TTiyth of her ten- 
 dency to the earth. Therefore this diminilhed tenden- 
 cy cannot retain the moon in the fame orbit ; fhe muft 
 retire farther from the earth, and defcribe an orbit which 
 is lefs incurvated by -rrj-th part ; and (he muft employ 
 a longer time in a revolution. The period therefore 
 which we obferve, is not that which would have obtain- 
 ed had the moon been influenced by the earth alone. 
 We ftiould not have known that her natural period was 
 increafed, had the difturbing influence of the fun re- 
 mained unchanged ; but this varies in the inverfe tri- 
 phcate ratio of the earth's diftance from the fun, and is 
 therefore greater in our winter, when the earth is nearer 
 to the fun. This is the fource of the annual equation, 
 by which the lunar period in January is made to exceed 
 that in July nearly 24 minutes. The angular velocity 
 of the moon is diminilhed in general tt7> and this nu- 
 merical coefficient varies in the inverfe ratio of the cube 
 of the earth's diftance from the fun. If we expand tin's 
 inverfe cube of the earth's diftance into a ferics arran- 
 ged according to the fines and cofines of the earth's 
 mean motion, making the earth's mean diftance unity, 
 we fliall find that the fen'es contains a term equal to -|. 
 of the fquare of the eccentricity of the earth's orbit. 
 Therefore the expreffion of the diminution of the moon's 
 angular velocity contains a term equal to T^-g- of this ve- 
 locity, multiplied by \ of the fquare of the earth's ec- 
 centricity ; or equal to the produtt of the fquare of the 
 eccentricity, multiplied by the mo;)n's angular velocity, 
 and divided by 1 19,3? (y of 179). Did this eccentri- 
 city remain conftant, this produft would alfo be con- 
 ftant, and would ftill be confounded with the general 
 diminution, making a conftant part of it : but the ec- 
 centricity of the earth's orbit is known to diminifli, and 
 its diminution is the refult of the univerfality of the 
 Newtonian law of the planetary defledlions. Although 
 this diminution is exceedingly fmall, its effedt on the lu- 
 nar motion becomes fenfible by accumulation in the 
 courfe of ages. The eccentricity diroinilliing, the dimi- 
 F nutioa
 
 43 ASTRO 
 
 nution of the moon's angular motion mud alfo diminifh, 
 that is, the angular motion muft incrcafe. 
 
 During the i 8th century, the fquare of the earth's 
 tccentricity has diminilhed 0,0000015^25, the mean 
 diftance from the fun being =: t. This has increaied the 
 angular motion of the moon in that tinieo.ocooocc 1 285. 
 As this augmentation is gradual, we mull multiply tiie 
 angular moiion during the century by the halt of this 
 quantity, in order to obtain its accumulated effeft. This 
 will be found to be 9" very nearly, which exceeds that 
 deduced, from a moll careful comparilon of the motion 
 of tlie lall two centuries, only by a fraction of a fe- 
 cond ! 
 
 As long as the diminution of the fqnarc of the eccen- 
 tricity of the earth's orbit can be fuppofed proportion- 
 al to the time, this effefl will be as the fquarcs of the 
 times. When this theory is compared with obferva- 
 tions, the coincidence is wonderful indeed. The effefl 
 on the moon's motion is periodical, as the change of the 
 folar eccentricity is, and its period includes millions of 
 years. Its eifeft on the moon's longitude will amount 
 to feveral degrees before the fecular acceleration change 
 to a retardation. 
 
 Thole who are not familiar with the difquifitlons of 
 modern analyfis, may conceive this queition in the fol- 
 lowing manner. 
 
 Let the length of a lunar period be computed for the 
 earth's diftance from the fun for every day of the year. 
 Add them into one fum, and divide this by their num- 
 ber, the quotient will be the mean lunar period. This 
 will be found to be greater than the arithmetical me- 
 dium between the greateft and the kail. Then fuppofe 
 the eccentricity of the earth's orbit to be greater, and 
 make the fame computation. The average period will 
 be found ftill greater, while the medium between the 
 greateft and leaft periods will hardly differ from the 
 former. Something very like this may be obferved 
 without any calculation, in a cafe very fimilar. The 
 angular velocity of the fun is inverfely as the Iquare of 
 his dillance. Look into the folar tables, and the great- 
 eft diurnal motion will be found 3673 ', and the leafl: 
 3433'' The mean of thefe is 3553', but the medium 
 of the whole is 3548''. Now make a fimilar obfervation 
 in tables of the motion of the planet Mars, whofe ec- 
 centricity is much greater. We (hall find that the me- 
 dium between the greateft and leaft exceeds the true 
 medium of all in a much greater proportion. 
 Ccrtiii ty Thus has the patient and afllduous cultivation of the 
 and utility Newtonian difcoveries explained every phenomenon, and 
 of this law. enabled us to forefee changes in them- which no exami- 
 nation of the part appearances, unaflTifted by this theory, 
 could have pofnted out, and which muft have exceed- 
 ingly embarraUed future aftronomers This great but 
 fimple law of defltftion reprefents every phenomenon of 
 the fyftem in the moil minute circumftances. Far 
 from fearing that future experience may overturn this 
 law, we may reft alTured that it will only confirm it 
 more and more; and we may confide in its moft remote 
 .. confcquences as if they were aftually obferved. 
 Reciprocal It is difcovered by obfervation, that the defleftion of 
 deflection the moon to the earth, and of the planets to the fun, 
 of tile tanh jr,. accompanied by an equal and oppofite defleftion of 
 
 an moon, j^ earth to the moon, and of the lun to the planets, 
 and 01 the ^ ' , . ^, . , . 
 
 funandpla- The tendency 01 the earth to the moon is plainly m- 
 
 nets, dicated by the rife of the waters of the ocean under the 
 
 N O M Y. 
 
 moon, and on the oppofite fide of the earth. Slrlfaae 
 Newton tried what (hould be the refult of a tendency of 
 the water to the moon. His invcftigation of this quef- 
 tion was very fimilar to that in his lunar theory. We 
 may conceive the moon to be one of many millions of 
 particles of a fluid, occupying a globe as big as the lu- 
 nar orbit. Each will feel a fimilar difturbing force, 
 which will diminifh its tendency to the earth in the 
 neighbourhood of the place of conjundlion and oppofi- 
 tion, and will increafe it in the neighbourhood of the j„ 
 quadratures. They cannot therefore remain in equdi- Proved br 
 brio in their fpherical form ; they muft fink in the qua- 'I": ebbing 
 dratures, and rife in the conjundtion and oppofition, till ' \ °^'^ 
 their greater height compenfates for the diminiflied jg^ 
 weight of each particle. In like manner, the waters of 
 the ocean muft link on thofe parts of the earth where 
 the moon is feen in the horizon, and muft rife in thofe 
 which have the moon in the zenith or nadir. All thefe 
 effecls are not only to be feen in general, but they may 
 all be calculated, and the very form pointed out which 
 the fnrfaee of the ocean muft alfume ; and thus a ten- 
 dency ot every particle of the ocean to the moon, in- 
 verfely proportional to the fquare of its diftance from 
 it, gives us a theory of the ebbing and flowing of the 
 fea. This is delivered in fufficient detail in the article 
 Tide of the Encyclopaedia Britannica, and therefore 
 need not be infifted on in this place. The fame infe- 
 rence muft be drawn from the preceflion ot the equi- 
 noxes produced by the aAion of the moon on the pro- 
 tuberant matter of our equatorial regions. See Pre- 
 cession in the Encycl. 
 
 But the mutual tendency of the earth and moon is ^^^ i,y di 
 clearly feen in a phenomenon that is much more fimple. fcrert con 
 If we compute the fun's place in the heavens, on theP"'3t'""s- 
 fuppofition that the earth defcribes areas proportional ,.'J 
 
 place in tl 
 
 to the times, we fiiall find it to agree with obiervation heavens, i 
 at everv new and full moon : But at the firll quarter ] 
 
 the fun will be obferved about 9 fecoiids too much ad- 
 vanced to the eaftward ; and at the laft quarter he will 
 be as much to the weftward of his calculated place. In 
 all intermediate pofitions, the deviation of the obfenred 
 from the computed place of the fun will be 9 feconds, 
 multiplied by the fine of the moon's diftance from con- 
 junftion or oppofition. In fliort, the appearances will 
 be the fame as if it were not the earth which dtfcribed 
 areas proportional to the times round the fun, but that 
 a point, lying between the cirth and moon, and verv 
 near the earth's furface, were defcribing the ellipfe round 
 tlie fun, while the earth and moon revolve round this 
 point in the courfe of a lunation, having the point al- 
 ways in the line between them, in the farne manner as 
 if tliey were on the extremities of a rod which turns 
 round tliis point, while the point itfelf revolves round 
 the fun. 
 
 This then is the faft with refpeft to the motions ; 
 and the earth in a month defcribes an orbit round this 
 common centre of the earth and moon. It cannot do 
 this unlefs it be continually deflefted from the tangent 
 to this orbit ; therefore it is continually defleCled to- 
 ward the moon : and the momentum of this deflcClion, 
 that is, its quantity of motion, is the fame with that of 
 the moon's defteftion, becaufe their diftances from the 
 common centre are as their quantities of matter in. 
 verfcly. 
 
 Appearances perfeftly fimilar to thefe oblige us to 
 
 affirm
 
 43 
 
 3' 
 
 >blerva- 
 iuns on 
 he rhirtl 
 iw uf mo 
 un. 
 
 .n 
 
 r«wton's 
 xterlion 
 f that Uw 
 
 ASTRONOMY. 
 
 affirm that the fun is continually deflected toward the the planet in a fimilar orbit round the fun (fuppofed 
 
 planets. Aftrononiical inilruments, and the art of ob to be held faft in his place) at the fame diftance which 
 
 ferviiig, have been prodigioufly improved fince Sir Ifaac really obtains between them, with this folc didVrcnce, 
 
 Newton's time ; and the moil Icrupulous attention has that the periodic time will be longer, in the fnbdupli- 
 
 been paid to the fun's motion, becaule it is to his place cate ratio of the quantity of matter in the f\in to the 
 
 in the univerfe that continual reference is made in com- quantity of matter of the fun and planet together. A- 
 
 puting the place of all tlie planets. He is fuppofed at reas will be defcribcd proportional to the times, and the 
 
 reft in the common focus of all their orbits ; and the orbit will be elliptical ; but the ratio of the fcjiirires of 
 
 o/yJr'DCt/ diftancc of a planet fom the fun is always con- the periodic times will not be the fame with the ratio 
 
 fidered as the radius I'cSor. If this be not the cafe, of the cubes of the diftancts, unlefs all the planets arc 
 
 the orbital motions contained in our tables are not the equal. 
 
 abfolute motions of the planets, nor the deflexions from Thus was the attention of aftronomers direSed to a 
 
 the tangents the real deflexions from abfolute reflilineal number of ^jft^an-n/ irregularities in the motion of the 
 
 motion ; and therefore the forces are not fuch as we in- earth, which muft refult from this derangement of the 
 
 fer from thofe miftaken deflexions. Accordingly Sir fun, which they had imagined to remain lledfafl in his 
 
 Ifaac Newton, induced by certain metaphyfical confi- place. They were told what to expeX, and on what 
 
 derations, afTumed it as a law of motion, that every ac- pofitions of the planets the kind and quantity of every 
 
 tion of a body A on another body B, is accompanied irregularity dejiended. This was a moft Inviting field 
 
 by an equal and contrary aXion of B on A. We do of obfervation to a curious fpcculatlft ; but it required 
 
 not fee the propriety of this aflertion as a metaphyfical the niceft and mott expeniive inftruments, and an nnin- 
 
 axiom. It is perfeXly conceivable that a piece of iron terrupted feries of long continued obfervations, fulficltnt 
 
 will always approach a magnet when in its neighbour, to occupy the whole of a man's time. Fortunately the 
 
 hood ; but we do not fee that this obliges us to affert, accurate determination of the folar and lunar motions 
 
 that therefore the magnet will alfo approach the iron, were of the utmoll importance, nay, indifpenfably ne- 
 
 Thofe who explain the phenomena of magnetifm by ceflTary for folving the famous problem of the longitude 
 
 the inipulfe of a fluid, muft certainly grant that there is of a (hip at fea : and thus the demands of commercial 
 
 no metaphyfical neceffity for another ftreani of fluid im- Europe came in aid of philofophical curiofity, and oc- 
 
 pelling the magnet toward the iron. And accordingly cafioned the ereXion of obfervatories, firft at Green- 
 
 this, and the fimilar reciprocity in the phenomena of wich, and foon after at Paris and other places, with ef- 
 
 cleXrlcity, have rt/wjj'j- been confidered as deduXinns tabiilhments for aftronomers, who fliould carefully watch 
 
 of experimental philofophy ; yet we obferve the fame re- the motions of the fun and moon, not negleXing the 
 
 ciprocity in all the adllons of fublunary bodies ; and other planets. 
 
 Newton's third law of motion is received as true, and The fortunate refult of all this folicitude has been the Confirmed 
 
 admitted as a principle of reafoning. But we appre- complete eftablifliment of the Newtonian conjeXuie (for ''^ "Werva^ 
 
 hend that it was hafty in this great philofopher, and fo we muft ftill think it), and the verification ol New- '""'' 
 
 unlike his fcrupulous caution, to extend it to the pla- ton's aflfcrtion, that aXion was accompanied, through 
 
 netary motions. He did, however, extend it, and af- the whole folar fyfteni, by an equal and contrary re- 
 
 ftrted, that as each planet was dtfleXed toward tht- fun, aftion. All the inequalities of the folar motion pre- 
 
 the fun was equally (in rclpeX of momentum) defleXed diXed by Newton have been obferved, although they 
 
 toward each planet, and that his real motion was the are frequently fo complicated that they could never have 
 
 compofition of all thoie fimultaneous dcfleXions. He been deteXed, had not the Newtonian theory direfted 
 
 aflerted that there was a certain point round which the us when to find any of them pretty clear of complica- 
 
 fun and his attending planets revolved ; and that the tion, and how to afcertain the accumulated refuk of 
 
 orbit of a planet, which our meaiurements determined them all in any ftate of combination, 
 
 by continual reference to the fuu as to a fixed body, But in the courfe of this attention to the moti<ins of 
 
 was not the true orbit, but confifted of the contempo- the fun and moon, the planets came in for a fliarc, and 
 
 raneous orbits of that planet and of the fun round this confiderable deviations were found, from the fuppofi- 
 
 fixed point. Any little feXor of the apparent orbit tion that all their defleXions were directed to the fun, 
 
 ■was greater than the correfponding feXor of the pla- and were in the invtrfe duplicate ratio of their diftances. 
 
 net's true orbit in abfolute fpace, and the apparent mo- The nice obfervation fhewed, that the period of Jupiter 
 
 tion was compounded of the true motion of the planet, was fomewhat fliorter than Kepler's hw required, 
 
 and the oppofite to the true motion of the fun. After A flight refleXion (hewed that this was no incon- 
 
 a moft ingenious and refined inveftigation, he ftiewed fiftency ; becaule the common centre of the conjoined 
 
 that, notwithftanding this great difference of the Kep- orbits of the fun and Jupiter was fcnfibly diftant from 
 
 lerean laws from the truth, the inference, with refpeX the centre of the fun, namely, about the i locth part of 
 
 to the law of planetary defleXion, is juft, and that not the radius veSor ; and therefore the real OtfleXion was 
 
 only the apparent defleXions are in the inverfe dupli- about a 220oth part lefs than was fuppofed. It was nowr 
 
 cate ratio of the diftances from the fun, but that the plain that the diftances to which the Keplereau law muft 
 
 real defleXions vary in the fame ratio of the diftances be applied, are the diftances, not from the fun, but from 
 
 from the fixed point, and alfo from the fun ; for he the fixed point round which the fun and planets revolve, 
 
 ftiewed that the diftances from the fun were in a cob- This difl'erence was too finall to be obferved in Kepler's 
 
 ftant ratio to the diftances from this point. He fliew- time ; but the fceming error is only a confirmation of 
 
 ed alfo that the fame forces which produced the con- the Newtonian philoiophy. 
 
 temporaneous revolution of a planet and the fun round But there are other irregularities which cannot be ex- 
 
 the centre of the fyftem, would produce a revolution of plained in this manner. The planetary orbits change 
 
 F 2 their 
 
 li
 
 44 
 
 ASTRO 
 
 their pofition ; their aphelia advance, their nodes recede, 
 their inclination to each other vary. The mean mo- 
 tions of Saturn and Jupiter are fubjea to confidcrablc 
 ,4 changes, which are periodical, 
 l^cfleiiion Sir Kaac Newton had no fooner difcovercd the uni- 
 r>f the pla- vprfality and reciprocity "f the defleftions of the pla- 
 ""' '"' nets and the fun, than he aHo fufpeded that they were 
 continually dcfl.-Aed towards each other. He imme- 
 diately obiained a general notion of what (hould be the 
 more general refults of fuch a mutual aftion. They 
 may be conceived in this way 
 
 wards each 
 other. 
 
 Plate VI. 
 
 Let S (fig. S-) reprefent the fun, E the earth, and I 
 Tuoiter, dcfcribinir concentric orbits round the centre of 
 the fyftcm. Make IS : EA = EP : SI^ Then, if 
 
 IS be taken to reprefent the defleftion of the fun to- 
 ward Jupiter, EA will reprefent the defleaioii of the 
 Earth to Jupiter. 
 
 Draw EB equal and parallel to SI, 
 
 35 , and compkte the parallelogram EBAD. ED will re- 
 (^itirruVhprefent the difturbing force of Jupiter. It may be re- 
 inutual «. folved into EF, perpendicular to ES, and EG m the di- 
 tion. reftion of SE. By the tirll of thefe the earth's angu- 
 
 lar motion round the fun is affefted, and by the fecond 
 its defleftlon toward him is diminiihed or increafed. _ 
 
 In confequence of this firil part of the difturbing 
 force, the angular motion is increafed, while the earth 
 approaches from quadrature to conjuiiftion with Jupi- 
 ter {which is the cafe reprefented in the figure), and is 
 diminithed from the time that Jupiter is in oppofition 
 till the earth is again in quadrature, weftward of his 
 oppofition. The earth is then accelerated till Jupiter 
 is in conjunftion with the fun ; after which it is retard- 
 ed till the earth is again in quadrature. . . 
 
 The earth's tendency to the fun is dirainifhed while 
 Jupiter is in the neighbourhood of his oppofition or 
 conjunftion, and increafed while he is in the neighbour- 
 hood of his ftationary pofitions. Jupiter being about 
 1000 times lefs than the fun, and 5 times more remote, 
 IS muft be confidered as reprefenting ij^lootli "^ ''^^ 
 earth's defledtion to the fun, and the forces ED and 
 EG are to be meafured on this fcale. 
 
 In confequence of this change in the earth's tenden- 
 cy to the fun, the aphelion fometimes advances by the 
 diminution, and fometimes retreats by the augmenta- 
 tion. It advances when Jupiter chances to be in oppo- 
 fition when the earth is in its aphelion; becaufe this di- 
 minution of its defleaion towards the fun makes it later 
 before its path is brought from forming an obtufc angle 
 with the radius -veaor, to form a right angle with it. 
 Becaufe the earth's tendency to the fun is, on the whole, 
 more diminilhed by the difturbing force of Jupiter than 
 it is increafed, the aphelion of the earth's orbit advances 
 
 on the whole. .,,.„• 1 j 
 
 In like manner the apheha of the inferior planets ad- 
 vance by the difturbing forces of the fuperior : but the 
 aphelion of a fuperior planet retreats ; for thefe reafons, 
 and becaufe Jupiter and Saturn are larger and more 
 powerful than the inferior planets, the aphelia of them 
 all advance while that of Saturn retreats. 
 
 In confequence of the fame difturbing forces, the 
 rode of the difturbed planet retreats on the orbit of the 
 difturbing planet ; therefore they all retreat on the eclip- 
 tic, except that of Jupiter, which advances by retreat- 
 ing on the orbit of Saturn, from which it fuffers the 
 o-reateft difturbance. This is owing to the particular 
 lofitjon of the nodes and the inclinations of the orbits. 
 
 N O M Y. 
 
 The Inclination of a planetary orbit Incrcafes while 
 the planet approaches the node, and diminilhes while 
 the planet retires from it. ,,5 
 
 M. do la Place has completed this dediiaion of the.4 feculia. 
 planetary inequalities, by explaining a peculiarity in the""'')' 'J"- 
 motions of Tunitcr and Saturn, whreh has lonff employ-R""'^ '" 
 ed the attention of aftrononicrs. Tlie accelerations and„f j.,p,;gr 
 retardations of the planetary motions depend, as hasand Saturn. 
 been (hewn, on their configurations, or the relative quar- 
 ters of the heavens in which they are. Thofe of Mer- 
 cury, Venus, the Earth, and Mars, arifing from their 
 mutual dcfleaions ; and their more remarkable deflec- 
 tions to the great planets Jupiter and Saturn, nearly 
 compenfate each other, and no traces of them remain 
 after a few revolutions : but the pofitions of the aphe- 
 lia of Saturn and Jupiter are fuch, that the retardations 
 of Saturn feufibly exceed the accelerations, and the aiio- 
 maliftic period of Saturn increafes almoll a day every 
 century : on the contrary, that of Jupiter diminifhes. 
 M. de la Place Ihews, that this proceeds from the pofi- 
 tion of the aphelia, and the almoft perfea commenfura- 
 bility of their revolutions ; five revolutions of Jupiter 
 making 21,675 days, while two revolutions of Saturn 
 make 21,538, diifering only 137 days. 
 
 Suppofing this relation to be exaa, the theory (hews 
 that the mutual aaion of thefe planets muft produce 
 mutual accelerations and retardations of their mean mo- 
 tions, and afcertains the periods and limits of the fecu- ' 
 lar equations thence arifing. Thefe periods include fe- 
 veral centuries. Again, becaufe this relation is not pre- 
 cife, but the odd days nearly divide the periods already 
 found, there muft arife an equation of this fecular equa- 
 tion, of which the period is imm«nfely longer, and the 
 maximum very minute. He (hews that this retardation 
 of Saturn is now at its maximum, and is diminifliing 
 again, and will, in the courfe of years, change to an 
 acceleration. 
 
 This inveftigation of the fmall inequalities is the moft 
 intricate problem in mechanical philofophy, and has 
 been completed only by very flow degrees, by the ar- 
 duous efforts of the greateft mathematicians, of whom 
 M. de la Grange is the moft eminent. Some of his ge- 
 neral refults are very remarkable. 
 
 He demonftrates, that fince the planets move in one 
 direaion, in orbits nearly circular, no mutual difturb- 
 ances make any permanent change in the mean diftan- 
 ces and mean periods of the planets, and that the peri- 
 odic changes are confined within very narrow limits. .. 
 The orbits can never deviate fenfibly from circles. Noneofcillation 
 of them ever has been or will be a comet moving in aof 'hepla- 
 very eccentric orbit. The ecliptic will never coincide "'^'^'^5' 5' 
 with the equator, nor change its inclination above two 
 degrees. In (hort, the folar planetary fyftem ofcillates, 
 as it were, round a medium ft;ate, from which it never 
 fwerves very far. 
 
 This theory of the planetary inequalities, founded on 
 the univerfal law of mutual defleaion, has given to our 
 tables a precifion, and a coincidence with obfervation, 
 that furpaffes all expeaation, and infures the legitimacy 
 of the theory. The inequalities are moft fenfible in the 
 motions of Jupiter and Saturn ; and thefe prefent them- 
 felves in fuch a complicated ftatc, and their periods are 
 fo long, that ages were neceflary for difcovering them 
 by mere obfervation. In this refpea, therefore, the 
 theory has outftripped the obfervations on which it is 
 
 founded..
 
 Authin'i- 
 city of tiie 
 Indian a- 
 
 ?9 
 Origin of 
 
 ;he aftrolp- 
 lical divi- 
 fton of the 
 
 40 
 ^fljon cf 
 lie comets, 
 
 rhey are 
 Jfedled by 
 kc planets 
 
 A S R T 
 
 founded. It is very remarkable, that the periods which 
 the Indians affign to thefe two planets, and which ap- 
 peared fo inaccurate that they hurt the credit of the 
 fcience of thofe ancii;nt aftronomtrs, are now found pre- 
 cifcly fuch as muil have obtained about three thoufund 
 years before the Chriftian era ; and thus they give an 
 authenticity to that ancient artrononij. The periods 
 which any nation of aftronomers affign to thofe two 
 planets would afford no contemptible mean for deter- 
 mining the age in which it was obferved. 
 
 The foUowiug circumftance is remarkable : Suppofe 
 Jupiter and Saturn in conjunction in the firll degree of 
 Aries ; twenty years after, it will happen in Sagitta- 
 rius; and after another twenty years, it will happen in 
 Leo. It will continue in thefe three figus for ioo years. 
 In the next 200 it will happen in Taurus, Capricornus, 
 and Virgo ; in the next 200 years, it will happen in 
 Gemini, Aquarius, and Libra ; and in the next 200 
 years, it will happen in Cancer, Pifces, and Scorpio : 
 then all begins again in Aries. It is highly probable 
 that thefe remarkable periods of the oppoiltions of Ju- 
 piter and Saturn, progreffive for 40 years, and ofcilla- 
 ting during 160 more, occafioned the allrological divi- 
 fion of the heavens into the four trigons, of fire, air, 
 earth, and water. Thefe relations of the figns, which 
 compofe a trigon, point out the repetitions of the chief 
 irregularities of the folar fyllem. 
 
 M. de la Place obferves (in 1796), that the laft dif- 
 covered planet gives evident marks of the adtion of the 
 reft ; and that when thefe are computed and taken into 
 the account of its bygone motions, they put it beyond 
 doubt that it was feen by Flamftead in 1 690, by Mayer 
 in 1756, and by Monnier in 1769. 
 
 We have hitherto overlooked the comets in our ac- 
 count of the mutual difturbances of the folar fyftem. 
 Their number is very great, and they go to all quarters 
 of the univerfe : but we may conclude, from the won- 
 derful regularity of the planetary motions, when all their 
 own mutual aftions are taken into account, that the 
 quantity of matter in the comets is very inconfiderable. 
 They remain but a fhort time in the neighbourhood of 
 the planets, and they pafs them with great rapidity. 
 Some of them have come very near to Jupiter, but left 
 no trace of their atlion in the motions of his fatellitcs. 
 They doubtlefs contribute, in general, tfe make the ap- 
 fides of the planetary orbits advance. 
 
 On the other hand, the comets may be confiderably 
 affefted by the planets. The very important phenome- 
 non of the return of the comet of 1682, which was to 
 decide whether they were revolving planets defcribing 
 ellipfcs, or bodies which came but once into the plane- 
 tary regions, and then retired for ever, caufed the aftro- 
 nomers to confider this matter with great care. Halley 
 had fhewn, in a rough way, that this comet muft have 
 been confiderably affefted by Jupiter. Their motion 
 near the aphelion muft be fo very flow, that a very fmall 
 change of velocity or direftion, while in the planetary 
 regions, muft confiderably affeft their periods. Halley 
 thought that the aftion of Jupiter might change it half 
 a year. Mr Clairaut, by confidering the difturbing forces 
 of Jupiter and Saturn through the whole revolution, 
 fiiewed that the period then running would exceed the 
 former nearly two years (618 days), and affigned the 
 middle of April 1759 for the time of its perihelion. It 
 leally pafTed its perihelion on the 12th of March, This 
 
 O N O M Y. 
 
 45 
 
 was a wonderful precifion, wiien we rcficiA that the co- 
 met had been feen but a very few days in its former ap- 
 paritions. 
 
 A comet obferved by Mr Profperin and others in 
 1771 has greatly puzzled the aftronomers. Its motions 
 appear to have been extremely irregular, and it certainly 
 came fo near Jupiter, that his momentary influence was 
 at leaft equal to the fun's. It has not been rccognifed 
 fince that time, although there is a great probability 
 that it is continually among the planets. ^j. 
 
 It is by no means inipolTible, nor highly improbable, Cor.fe- 
 that in the courfe of ages, a comet may attually meetl"'"'* "f * 
 one of the planets. The cffedl of fuch a concourfe niuft^'i'"^'" *"" 
 be dreadful ; a change of the axis of dituiial rotation meeting, 
 muft refult from it, and the fea muft defert its former 
 bed and overflow the new equatorial reg:ons. The 
 ftiock and the deluge muft deftroy all the works of man, 
 and mort of the race. The remainder, reduced to mi- 
 fery, muft long ftruggle for exiftence, and all remem- 
 brance of former arts and events muft be loft, and every 
 thing muft be invented anew. There are not wanting 
 traces of fuch devaftations in this globe : ftrata and 
 things are now found on mountain tops which were cer- 
 tainly at the bottom of the ocean in former times ; re- 
 mains of tropical animals and plants are now dug up in 
 the circumpolar regions. Tempora mulanlur, et nos mu- 
 tamur in illis. 
 
 It is plain, that when we know the direftion and the 
 intenfitv of the difturbing force, we can tell what will 
 be the accumulated effedl of its aftion for any time. 
 The direftion is eafily determined by means of the di- 
 ftance : but how ftiall we determine the intenfity ? Since 
 we fee that the whole waters of the ocean are detiefted 
 toward the moon, and have fuch probable evidence that 
 planetary defleftion is mutual ; it follows that the moon 
 is deflefted towards cu^rydrop of water, and that a!l 
 the matter in one body is' deflefted towards all the 
 matter in another body ; and therefore that the deflec- 
 tion towards the fun or a planet is greater or lels in 
 proportion to its quantity of matter. Newton indeed 
 thought it unreafonable to fuppoie that a planet wa- 
 deflefted to the centre of the fun, which had no diftin- 
 guiftiing phyfical property ; and thought it more pro- 
 bable that the defleftion of a planet to the fun was the 
 accumulated defleftion of every particle in the planet to 
 every particle in the fun. But he was too fcrupulous 
 to take this for granted. He therefore endeavoured to 
 difcover what would be the fenfible defleftion of one 
 fpherc to another, when each conllfted of matter, every 
 particle of which was deflcdted to every particle of the 
 other with an intenfity inverfely proportional to the. 
 fquare of the diftance from it. By help of a nioft beau- Ttrii'ency 
 tiful and fimple procefs, he difcovcred, that the ten.of fphcricai- 
 dency of a particle of matter to a fpherical furtace, ftnil, " ''" '■'" 
 or folid, of uniform denfity at equal diftances trom ihe^.'^^'' j. 
 centre, was the fame as if all the particles in the fu.--rt(51Iyr-s the 
 face, fhell, or folid, were united in its centre : heiice itqiiantit) of 
 legitimately followed, that the mutual tendency of fphe- "'?''^'"' ^'■'*' 
 rical furfaces, ftiells, or folids, was proportional to the '.^^'j^^^j^^^' 
 quantities of matter in the attrafting body, and inverfe-cf tht di- 
 ly as the fquare of the diftance of their centres; and '"'a c; of 
 thus the law of attraftion, competent to every partlcle'*^^"' "•"'' 
 of planetary matter, was the fame with that which tvas 
 obferved among fpherical bodies conliftii.g oi inch mat- 
 ter. And it is remarkable, that the inverfe duplicate ra- 
 tio
 
 46 
 
 ASTRO 
 
 tio of tlic diilances is the onlv law that will hold, botli 
 with refpeft to (ingle particles and to globus corapoled 
 of fuch particles. He alfo deinonftrntcd, that a particle 
 placed within a fphere was not affeflcd by all the flicU, 
 whicii w;is more diftant than itfelf from the centre, be- 
 ing equally attraftcd on every fide, and that it tended 
 tinvard the centre of a homogenous fphere, on the fur- 
 face of which it was j>laced, with a force proportional 
 to its dillance from the centre. 
 
 Newtoti faw a cafe in which it was pofTible to difco- 
 ver whether the tendency of the matter of which the 
 ■planets confided was direfted to a mathemalical centre 
 void of any phyfical properties, or whether it was the 
 refult of its united tendency to all the matter of the 
 planet. He demonllrated that if the e.uth conlilled of 
 matter which tended to the centre, it behoved it to af- 
 fume the form of an elliptical fpheroid, in conkqucnce 
 of the centrifugal force arifing from its diurnal motion, 
 and that the pular axis muft be to its equatorial diame- 
 ter as 577 to i;78 ; but if every particle tends to every 
 other particle in the invcrfe duplicate ratio of the di- 
 ftance from it, the form mufl. flill be elliptical, but more 
 protuberant, and the polar axis mull be to the equato- 
 rial diameter as J30 to 231. Then only will a column 
 of water from the pole to the centre balance a column 
 from the equator to the centre. He alfo fiiewed what 
 ftiould be the vibrations of pendulums in different lati- 
 tudes, on both fuppofitions. Mathematicians were ea- 
 ger therefore to make thofe experiments on pendulums, 
 and to determine the figure of the earth by the meatui-e- 
 inent of degrees of the meridian in different latittides. 
 The refult of their endeavours has been decidedly iu fa- 
 vours of the mutual tendency of all matter. This has 
 been farther confirmed by the obfervations of the ma- 
 thematicians who meafured the degrees of the meridian 
 in Peru, and by Dr Mafl<elyne in Britain, who found 
 that a pendulum fufpended in the neigbourhood of a 
 great and folid mountain, fenfibly deifiated from the 
 ^^ true vertical, ai.d was defleSed toward the miountaiu. 
 Propor- From a coUeftive view of all thefe circumlfances, Sir 
 
 tiotialqiian- jfa^g Newton concluded, with great confidence, that 
 
 title- of jj^^ defieftion toward any planet was the united deflec- 
 maf er in . , . < '^ , .... 
 
 the fun and ^'°" toward every particle 01 matter contained in it. 
 
 plai,ets<1e- This enabled him to determine the intenfity of the pla- 
 tcrmuied. netary ditlurbing forces, by previoufly afcertaining the 
 proportions of their quintities of matter. This pro- 
 portion, the difcovery of which feems above our reach, 
 is eafily afcertained in all thofe bodies which have others 
 revolving round them : for the defleflion of the revol- 
 ving body, being occafioned by all the matter in the 
 central body, will be proportional ( cateris paribus ) to 
 the quantity of matter in the central body, and there- 
 fore will give us a meafure of that quantity. Would we 
 compare the quantity of matter in Jupiter with the 
 quantity of matter in the fun, we have only to fuppofe 
 that a planet revolves round the fun at the diflance of 
 Jupiter's fourth fatellitc. Kepler's third law will tell 
 us the time of its revolution. The diflances, in this 
 tafe, being the fame, the centripetal forces, and confe- 
 quently the quantities of matter in the central bodies, 
 will be inverfely as the fquares of the periodic times of 
 the revolutions around them. In this way have the 
 quantities of matter been determined for the Sun, the 
 Earth, Jupiter, Saturn, and the lall difcovered pla- 
 
 N O M Y. 
 
 net. If the quantity in the Earth be confiderej a« the 
 unit, we have, 
 
 The Earth . . . - i 
 
 The newly difcovered planet - I7>7J 
 
 Saturn - - - - - 86,16 
 
 Jupiter - - - - - 317,1 
 
 The Sun - -. . - 3.^8343- 
 
 Thus' we fee that the fun is incomparably bigger than 
 any planet, having more than a thoulaiid times as much 
 matter as Jupiter, the mod niaffy of them all. There- 
 is a confiderable uncertainty, however, in the proportion 
 to the fun, beeaufe we do not know his diftance nearer 
 than within -^s^th part. 'I'he proportions of the refl 
 to each other are more accurate. The quantities ot 
 matter in Mercury and Mars can only be gueffed at : 
 the quantity in Mercury may be called 0,1, and Mars 
 may be called 0,1 2. Venus is fuppofed nearly equal to 
 the Earth. This is concluded from the efFeft which 
 (lie produces on the precefllon of the equinoxes and the 
 equation of the fun's motion. The moon is fuppofed 
 to be about j^-th of the- earth, from the effeft flie pro- 
 duces on the tides and the preceflion of the equinoxes, 
 compared with thofe produced by the fun. 4J 
 
 When thefe quantities of matter are introduced intoSuti's plaee 
 the computation of the planetary inequalities, and ^^^J^nflt^nf , 
 intenfity of the difturbiiig forces aflumed accordingly, pi^^ , j^. 
 the refults of the computations tally fo exadlly with ob-termined 
 fervation, that we can now determine the fun's place '^"■"i^y- 
 for any moment within two or three feconds of a de- 
 gree, and are certain of the tranfit of a planet within 
 one beat of the clock ! 
 
 yam Julias nulla caliglne prtegravat error ; 
 ^teis fuperum pciutrare domos atque arJua call 
 Scandere fublimis genii concejjit acumen. 
 
 Hallev. 
 
 Sir Ifaac Newton having already made the great dif- 
 covery of an univerfal and mutual dcfle<5^ion of all the 
 matter in the folar fyftem, was one day fpecnlating on 
 this fubjecl, and comparing it vs'lth other defleftlons 
 which he obferved among bodies, fuch as magnets, &c. 
 He confidered terreftrial gravity as a force of this kind. 
 By the weight of terreftrial bodies they kept united , 
 
 with the earth. By its weight was the water of thep ogrtfaof 
 ocean formed into a fphere. This force extended, wIth-Ntwton's 
 out any remaikable diminution, to the tops of the hlgh-°'^'^'"'"'y "' 
 eft mountains. Might it not reach much farther? May 
 it not operate even at the diftance of the moon ? In 
 the fame manner that the planetary force deflefts the 
 moon from the tangent to her orbit, and caufes her to 
 defcribe an ellipfe, the weight of a cannon ball dcflefts 
 it from the line of its direcfion, and makes it defcribe a 
 parabola. What if the defleiib'ng force which Incur- 
 vates her path towards the earth be the fimple weight 
 of the moon ? If the weight of a body be the fame with 
 the general plmetary force. It will dimhnni as the fquare 
 of it& diftance from the earth increafes. Therefore, 
 faid he to himfelf, fince the diftance of the moon from 
 the centre of the earth is about 50 times greater than 
 the dillance of the ilone whlcIi I throw from my hand, 
 and which is deflefted 16 feet in one fecond, the weight 
 of this ftone, if taken up to the height of the moon, 
 fhould be reduced to the 25-:oth part, and fhould there 
 defied jyg^th of l6feet in a fecond; and the moon fhould 
 
 deflea
 
 47 
 
 ASTRONOMY. 
 
 iefleft as much from ihe tangent in a fecond. Having certain. Wc acknowled'^c ti.at tlie experiments on 
 
 the dimenfioni!, as he thought, of the moon's orbit, he penduhims, confiftiiig of a vail variety of tcrrcllrial mat- 
 
 immediately computed the moon's defltdlion in a fe- fer, all of which performed their ofcillations in equal 
 
 cond ; but he found it confiderably different from what times, demoniirate that tlie acceleration of gravity on 
 
 he wiflied it to be. He therefore concluded that the thole pendulums w-as proportional to their quautitl-.s of 
 
 planetary force was not the weight of the planet. For matter, and that equal gravitation may be affirmed of all 
 
 ibme years he thought no more of it : but one day, in terreftrial matter. 
 
 the Royal Society, he heard an account read of mea- The elliptical motion of a planet is full proof that 
 
 furements of a degree of the meridian, which (hewed the accelerating power of its gravity varies in the in- 
 
 liim that the radius of the earth and the diftance of the verfe dujjlieate ratio of the diliance ; and the propor- 
 
 moon were very different trom vhat he had believed tionality of the fqnares of the periods to the cubes of 
 
 them to be. When he went home lie repeated his com- the diftances, fliews that the whole gravitations of the 
 
 putation, and found, that the deflcdlicn of a ftone was planets vary by the fame law. But this third obferva- 
 
 to the fimultaneous deflertion of the moon as the fquare tion of Kepler miglit have been the fame, although the 
 
 of the moon's diftance from the centre of the earth to gravitation of a particle of matter in Jupiter had been 
 
 the fquare of the ftone's diftance. Therefore the moon equal to that of a particle of terreftrial niatter, provided 
 
 is defleded by its weight ; :uid the fall of a ftone is juft that all the matter in Jupiter did not gravitate. If 
 
 a particular inftance of the exertion of the univerfal pla- -s'jth of Jupiter had been fuch gravitating matter, his 
 
 netarv force. This computation was but roughly made defledion from the tangent of his orbit would have 
 
 at firll ; but it was this coincidence that excited the been the fame as at prefent, and the time of his revolu- 
 
 philofopherto a more attentive review of the whole fub- tion would have been what we obferve. In order that 
 
 jeft. When every circumilance which can affeft the the third law of Kepler may hold true of the planetary 
 
 refult is taken into account, the coincidence is found to motions, no more is required than that the accumulated 
 
 le moft accurate. The fall of the Hone is not the full gravitation of the planet be proportional to its quantity 
 
 effeft of its weight ; for it is diminiftied by the rotation of matter, and thus the matter which docs not gravi- 
 
 of the earth round its axis : It is alio diminiihcd by the tate will be compenlated by the fuperior gravitation of 
 
 •weight of the air which it difplaces : It is alfo dimi- the reft. 
 
 nilhed by its tendency to the moon. On the other But becaufe we have no authority for faying that 
 
 hand, the moon does not revolve round the earth, but there is matter which gravitates differently from the 
 
 round a common centre of the earth and moon, and its reft, or which does not gravitate, we are intitled to 
 
 period is about T-Tcth Shorter than if it revolved round fuppofe that gravity operates alike on all matter. ^g 
 
 the earth ; and the moon's deflexion is aflfefted by the And this is the ultimatum of the Newtonian ])hiIo. Which h 
 
 fun's difturbing force. But all thefe correftions can be fophy, that the folar fyftem coniifts of bodies compofed^'^"^ ultima. 
 
 accurately made, and the ratio of the full weight of the of matter, every particle of which is, in faft, continually "f"^ '/ 'l" 
 
 ftone to the full defledlion of the moon afcertained. deflefted by its weight toward every other particle in the 
 
 This has been done. fyftem ; and that this defleftion, or aftual deviation, or 
 
 Terreftrial gravity therefore, or that power by which aftual preffure, tending to deviation from uniform r^c- 
 
 bod.'es fall or prcfs on their fupports, is only a particu- tilincal motion, is in the inverfe duplicate ratio of the 
 
 lar inftance of that general tendency by which the pla- diftance. 
 
 nets are retained in their orbits. Bodies may be faid to This doftrine has been called f/je fyjlem of univer/n/ Oh]t<iiioT>a 
 
 grai'itt7te when they give indications of their hiding gra- gravitnt'ton ; and it has been blamed as introducing an'"'h^liivr 
 
 Ills or heavy, that is, when they fall or prefs on their unphilofophical principle into fcience. 
 
 47 
 The uni- 
 verfal law 
 of graviia- 
 tioii, 
 
 nig an ' 
 Gravitation is;f^f^["*- 
 
 fupports ; therefore the planets may be faid to gravi- faid to be an occult quality ; and therefore as unlit foriv,u!,H.j 
 
 tate when they give fimilar indications of the fame ten- the explanation of phenomena as any of the occult qua- 
 
 dency by their curvelineal motions. The general fact, lities of Arillotle. But this reproach is inifounded ; 
 
 that the bodies of the folar fyftem are mutually dclieft- gravitation does not exprefs any q\r.ility whatever, but 
 
 ed toward each other, may be expreffed by the verbal a matter of faft, an event, an adtual defleclion, or an 
 
 noun GRAVITATION. Gravitation does not exprefs a aftual preffure, producing an atlual dcfleftion of the 
 
 quality, but an event, a dcfleftion, or a preffure. body prefted. 'I'hele are not occult, but matters of 
 
 The weight of a terreftrial body, or its preflure on continual obfervation. True, indeed, Newton does not 
 
 its fupport, is the eflttl of the accumulated gravitation deny, although he does not pofitively f„y, that this de- 
 
 of all its particles ; for bodies of every kind of matter fleftion, preffure, or gravitation, is an efl'cdl having a 
 
 fall equally faft. This has been afcertained with the caufe. Gravity is faid to be this caufe. Gravity is the 
 
 Btmoft accuracy by Sir Ifaac Newton, by comparing the lelng gravis or heavy, and gravitation is the giving iiicii- 
 
 vibratioiis of pendulums made of every kind of matter, cations of being heavy. Hiavinefs therefore is the word 
 
 Therefore their unitedgravitation is proportional to their w Inch expreffes gravitas, and our notion of the caufe of 
 
 quantity of matter; and we have concluded, that every the planetary defiettions is the fame with our notion of 
 
 atom of terreftrial matter is heavy, and equally heavy, heavinefs. This may be indiftinft and unfatisfaflory to 
 
 We extend this conclufion to the fun and planets, and a mind faftidioufly curious; but nothing can be more 
 
 fay, that the obferved gravitation of a planet is the uni- familiar. The planet is defledled, becaufe it is heavy. 
 
 ted gravitation of every particle. Therefore Sir Ifaac We are fuppofed to explain the fall of a ftone through 
 
 Newton inferred, from a collefted v(f w of all the phe- water very fatisfaftorily, and without having recourfe 
 
 nomena, that all matter gravitates to all matter with a to any occult quality, when we fay that it is heavier 
 
 force in the inverfe duplicate ratio of the diftance. than the water ; and we explain the rife of a piece of 
 
 But we do not think that this inference is abfolutely cork, when we f»y that it is not fo heavy as the water. 
 
 The
 
 48 
 
 ASTRONOMY. 
 
 so 
 Our know 
 ledge of 
 that law Ta 
 tis.'adlory. 
 
 "Vain at. 
 tempts t'j 
 accoiir.t 
 for it. 
 
 The explanations of the mutual actions of the phnets 
 are equally fatisfaftory, founded on the fame principles, 
 and equally free from' all fophiftry or employment ot 
 occult caufes. The weight of a body is not its lieavi- 
 nefs, but the effeft of its heavinefs. It is a gravitation, 
 an adual prefTure, indicated by its balancing the fup- 
 pofed heavinefs of another body, or by its balancing 
 the known elafticity of a fpring, or by balancing any 
 other natural power. It is fimilar to the prcffuve wliich 
 a magnet exerts on a piece of iron. This may perhaps 
 be produced by the impulfe of a ftream of fluid ; fo 
 may the weiglit of a heavy body. But we do not con- 
 
 - cern ourfelves with this queftion. We gain a mod ex- 
 tenfive and important knowledge by our knowledge of 
 
 "this univcrfal law ; for we can now explain every phe- 
 nomenon, by painting out how it is contained ni this 
 law ; and we can prediA the whole events of the folar 
 fyftem with unerring cxaclnefs. This Ihould fatisfy the 
 moil inqulHtive mind. 
 
 But, nilimur in I'etitum, fsmper cupjmufque negata. 
 There feems to be a fatal and ruinous dilpoiition in the 
 human mind, a fort of priapifm of the uuderitanding, 
 that is irritated by every interdift of natural imperfec- 
 tion. We would take a microfcope to look at light ; 
 we would kno-M what inoiu'iiig is, and we would ivelsh 
 hea-vinefs. 
 
 AU'who are acquainted with the writings of Ariftotle 
 have fome notion of his whimfical opinions on this lub- 
 jeft. He imagines that the planets are condufted in 
 their orbits by a fort of intelligences, Stkeo M'i/;\;at, which 
 animate the orbs that wheel them round. Although 
 this crude conception met with no favour in later times, 
 another, not more reafonable, was maintained by Leib- 
 nitz, who called every particle of matter a monad, and 
 gave it a perception of its fituation in the univerfe, of 
 its dillaiice and direction from every other, and a power 
 and will to move itfclf in conformity to this fituation, 
 by certain conllant lavi-s. This irmf ■^rux' hi the Mo- 
 nad is nothing but an aukward fubftitute for the prin- 
 ciple of gravitation, which the learned inlifted that New- 
 ton placed in every particle of matter as an innate 
 power, and which they reprobated as unphilofophical. 
 But in what refpeft this perception and aftive propcn- 
 fity is better, we do not perceive. It is more com- 
 plex, and involves every notion that is reprehenfible in 
 the other; and it offers no better explanation of the 
 phenomena. 
 
 But Newton is equally anxious with other philofo- 
 phers not to afcribe gravity to matter as an innate in- 
 herent property. In a letter to Dr Bently, he earneft- 
 ]y requefts him not to charge him with fuch an abfurd 
 opinion. It is an avovicd principle, that nothing can ad 
 on any thing that is at a diftance ; and this is confider- 
 ed as an intuitive axiom. But it is furely very obfcure ; 
 for we cannot obtain, or at leaft convey, clear notions 
 of the terms in which it is expreffed. The word aH is 
 entirely figurative, borrowed from animal exertions ; it 
 is therefore unlike the expreflion of any thing intitled 
 to the appellation of inluilive. If we try to exprefs it 
 without figure, we find our confidence in its certainty 
 greatly diminiihed. Should we fay that the condition 
 of a body A cannot depend on another body B that is 
 at diftance from it, we believe that no perf^on will fay 
 that he makes this aflertion from perceiving the abfur- 
 Uity of the contrary propofition. In the deraonftration, 
 
 as it is called, of the perfeverance of a body in a (late of 
 reft, tlie only argument that is offered is, that no caufe 
 can be alhgned why it fiiould move in one direftion ra- 
 ther than in another; but Ihould any one fay that ano- 
 ther body is near it, to the right hand, and that this is 
 a I'ufBcient reafon for its mo\ing that way, we know 
 no method by which this affcrtion can be ftiewn to be 
 falfe. 
 
 Such, however, has been the uniform opinion of phi- 
 lofophers. Nihil movclur (fays Leibnitz) nifi a contigiia 
 et molo. The celebrated mathematician Euler having 
 difcovered, as he thouglit, the produdlion of a preflure, 
 like gravity, from motion, fays, " as motion may arife 
 from preffnig powers, fo we have feen that preffing 
 powers may aiifc from motion. We fee that both exill 
 in the univerfe. It is the bufinefs of a philofopher to 
 difcover, by reafon and obfervatioii, which is the origin 
 of the other. It is incompatible with reafon that bo- 
 dies (hould be pofFefTed of inherent tendencies ; much 
 more that powers fliould exill independently. Farther, 
 that philofopher mull be reckoned to have affigned the 
 true caufes of phenomena, who demonftrates that they 
 arife from motion ; for motion, once exiiling, muft be 
 preferved for ever. In the prefent inftince (a certain 
 whimfical fadl of a ball running round the infide of a 
 hoop) we fee how a preffing power may be derived from 
 motion ; but we cannot fee how powers can exert them- 
 fclves, or be preferved, without motion. Wherefore we 
 may conclude that gravity, and all other powers, are 
 derived from motion ; and it is our bufinefs to invefti- 
 gate from what motions of what bodies each obferved 
 power derives Its origin." 
 
 Accordingly many attempts have been made to trace 
 the planetary detletllons to their origin in the motion 
 of fome impelling matter; but thefe attempts could not 
 be fuccefsful, becaufe they are all built on hypothefes. 
 It has been afiumed, that there Is a matter diffufed 
 through the celeftial fpaces ; that this matter is in mo- 
 tion, and by Its impulfe moves the planets : but the on- 
 ly reafon that can be given for the exiftence of this 
 matter is the difficulty we find In explaining the plane- 
 tary deflections without it. Even if the legitimate con- 
 fequences of this hypothefis were confiftent witTi the 
 phenomena, we have not advanced In our knowledge, 
 nor obtained any explanation. We have only learned, 
 that the appearances are fuch as would have obtained 
 had fuch a matter exifted and adled in this manner. 
 The obferved laws of the phenomena are as extenfive 
 as thofe of the hypothefis ; therefore it teaches us no- 
 thing but what we knew without It. 
 
 But this Is not all that can be faid agalnft thofe at-inconfifter 
 tempts; their legitimate confequences are mconjjjlent auilh cy v( [oau 
 the phenomena. By legitimate confequences we mean"''""''?' 
 the laws of motion. Thefe muft be admitted, and are j|^^ pheao 
 admitted, by the philofopher who attempts to explain mena. 
 the planetary motions by Impulfe. It would be ridicu- 
 lous to fuppofe a matter to fill the heavens, having laws 
 of Impulfe different from thofe that are obferved by 
 common matter, and which laws muft be contrived fo 
 as to anfwer the purpofe. It would be more fimple at 
 once to affign thofe pro re nata laws to the planets 
 themfelves. 
 
 Yet fuch was the explanation which the celebrated 
 Defcartes offered by his hypothefis of vortices, in which 
 the planets were immerfed and whirled round the fun. 
 
 It
 
 ASTRONOMY. 
 
 53 It is aftonifiiing tliat fo crude a conception ever obtain, net follows its motion, non ahrepta tamcn^ fed trnnqmlli. 
 ITorticfs of pj 3py partifans ; yet it long maintained its authority, ter quuji natante The planet therefore lias no tenden- 
 Defcartcs ^^^j U^jjj ^^^ zealous defenders. Till Sir Ifaac Newton cy to perl'evere in its former date of motion. Why 
 
 faw the indifpeniable neceffity of mathematical inveftiga- therefore does it not follow this harmonic motion cx- 
 
 tion in every quellion of matter in motion, no pcrfon aftly, and defcribe a circle tranquilliler nalans ? This is 
 
 had taken the trouble of giving any thing like a diftincl owing, fays Leibnitz, to its centrifugal force, by which 
 
 defcription of thofe vortices, the circumftances of their it perfeveres in a ftate of re6lilineal motion. It has no 
 
 motion, and the manner of their adlion ; all determined tendency to prcferve its former velocity, but it perfe- 
 
 with that prccilion that is required in the explanation : veres in its former direftion. The planet therefore is 
 
 for this mull always be kept in mind, that we want an not like common matter, and has laws of motion pccu- 
 
 explanation of the precile motions luhich have been oh- liar to itfelf ; it was needlefs therefore to employ any 
 
 ferved, and which will enable us to predict thofe which impulfe to explain its motions. But to proceed : I'his 
 
 are yet to happen. Men were contented with fome centrifugal force mull be counterafted in every point of 
 
 vague notion of a fort of fimilarity between the effects the orbit. Leibnitz therefore fuppofes that it is alfo 
 
 of fuch vortices and the planetary motions in a few ge- urged toward the centre by a folicitation like gravity 
 
 iieral circumftances ; and were neither at the trouble to or attraiftion. He calls it the paracentric force. He 
 
 confider how thefe motions were produced, nor how far computes what muft be its intenlity in different parts of 
 
 they tallied with the phenomena. Their account of things the orbit, in order to produce an elliptical motion, and 
 
 was only fit for carelefs chat, but unworthy of the at- he finds that it muft be inverfely as the fquare of the 
 
 tention of a naturalift. But fince this explanation came diftance from the centre (for this reafon he is frequent- 
 
 54 from a perfon defervedly very eminent, it was refpefted ly quoted by Bernoulli, Wolff, and others, as the difco- 
 Examined by Newton, and he honoured it with a ferious exami- verer of the law of gravitation). But Leibnitz arrives 
 3/ Newton, pjfjon^ It is to this examination alone that we are in- at this refult by means of feveral mathematical blunders, 
 
 debted for all the knowledge that we have of the con- either arifing from his ignorance at that time of fiuxio- 
 flitution of a fluid vortex, of the motions of which it nary geometry, or from his perceiving that an accurate 
 is fufceptible, of the manner in which it can be produ- procedure would lead him to a conclufion which he did 
 ced, the laws of its circulation, and the effeits which it not wifli : for we have feen (and the demonllration vi 
 can produce. We have this account in Sir Ifaac New- adopted by Leibnitz in all his pofterior writings of this 
 ton's Principles of Natural Philofophy ; and it contains kind), that if the ordinary laws of motion are obferved, 
 many very curious and interefting particulars, which a body, aftuated by this paracentric force alone, will 
 have been found of great fervice in other branches of defcribe an ellipfe, performing both its motion of har- 
 mechanical philofophy. But the refult of the examina- monic circulation, and its motion of approach to and re- 
 tion was fatal to the hypothefis ; fhewing that the mo- cefs from the centre, without farther help. Therefore, 
 tions which were pofTible in the vortices, and the effefts if the harmonic circulation is produced by a vortex, a 
 which they muft produce, are quite incompatible with force inverfely as the fquare of the diftance from the 
 the appearances in the heavens. We do not know one centre, combined with the harmonic circulation, will 
 perfon who has acquired any reputation as a mechani- produce a motion entirely different from the elliptical. 
 ciau that now attempts to defend it ; nor do we know It is demonftrated, that the force which is necelfa.y for 
 of any other perfon befides Newton who has attempted defcribing circles at different diftances, with the angu- 
 to explain mathematically how the circulation of a fluid lar velocity of the different parts of the orbit, is not in 
 can produce the revolution of a planet, if we except Mr the inverfe duplicate, but in the inverfe triplicate, ratio 
 j5 Leibnitz, the celebrated rival of the Britilh philofopher. of the diftances. This muft have been the nature of 
 lypothefis This gentleman publifhed in the Leipfic Review in his paracentric force, in order to counteraft the centri- 
 f Leibnitz. 1689, three years after the publication of the Prlncipia, fugal force arifing fiom the harmonic circulation. There 
 
 49 
 
 5« 
 
 an attempt to explain the elliptical motion of the *pla- fore Leibnitz has not arrived at his conclufion by juft ty'o'f the"'" 
 
 nets, and the defcription of areas proportional to the reafoning, nor can be faid to have difcovered it. He author, 
 
 times, by the impulfe of a vortex. It muft not be paffed fays, Fideo banc propnfa'wnem innotwjfe viro celiberrimo 
 
 over in this place, becaufe it acquired great authority Ifaaco Ne-ivtono, licet mn pojjim iudictre quomodo ad earn 
 
 in Germany, and many of that country ftiU affirm that pervenerit. This is really fomewhat like impudence 
 
 Leibnitz is the difcoverer of the law of planetary gra- The Primipia were publifhed in 16S6. They were re^ 
 
 vitation, and of the mechanical conftitution of the folar viewed at Leipfic, and the Review publifhed in 1687* 
 
 fyftem. We cannot help thinking this explanation the Leibnitz was at that time the principal mana.rer of that 
 
 moft faulty of any, and a moft difingenuous plagiarifm Review. When Newton publifhed, Leibnitz was livins? 
 
 from the writing^s of Newton. _ at Hanover, and a copy was fent him within two 
 
 Mr Leibnitz fuppoles a fluid, circulating round the months of its piibhcation, by Nicholas Facio lonT be 
 
 fun in fuch a manner that the velocity of circulation in fore the Review. The language of the Review has 
 
 every part is inverfely as its diftance from the fun. feveral fingularities, which are IVequent in Leibnitz's" 
 
 (N. B. Newton had ftiewn that fuch a circulation was own compofition ; and few doubt of its being his wri 
 
 pofTible, and that it was the only one which could be ting. Befides, this propofition in the Prmcipia had 
 
 generated in a fluid by an aflion proceeding from the been given to the Royal Society feveral years before 
 
 centre). Leibnitz calls this /j«rm«5«i<-rt/ «V™/,7/i»re. He and was in the records before 1684. Thefe were all 
 
 fuppofes that the planet adopts this circulation in every feen by LeibnitK when in England, belnsj lent him bv 
 
 part of its elliptical orbit, obeying without any refift- his friend Collins. ^ 
 
 ance the motion of this fluid. He^does not afcribe this We think that the opinion which a candid rerfon 
 
 to the impulfe of the fluid, faying exprefsl^ that the pla- muft form of the whole is, that Leibnitz knnv the pro 
 
 SuppL. Vol.. I. Part !. 
 
 polition,
 
 50 ASTRO 
 
 pofition, and attempted to Jemonftrate it in a way that 
 would make it pafs for liis own difcovcry ; or that he 
 only knew the enunciation, without underltanding the 
 principles. His harmonic circulation is a clumfy way 
 of explaining the proportic^nality of areas to the times; 
 and even this circulation is borrowed from Newton's dif- 
 fertation on the Cartelian vortices, which is alfo con- 
 tained in the Leiptic Review above mentioned. Leib- 
 nitz was by this time a competitor with Newton for 
 the honour of inventing the ilnxionary mathematics, and 
 was net giiiltlefs of adts of difmgenuity in afltrtinjj his 
 claini. He publifhed at the fame time, in the fame Re- 
 view, an almoft uniiitelliijible dilfcrtation on the refill- 
 ancc of fluids, which, when ex;imined by one who has 
 learned the fubjaft by reading the Principia of Newton, 
 affords an enigmatical delcription of the very theory 
 publilhed by Newton, as a ncceffary part of his great 
 work. 
 
 But befides all the above objcftions to Leibnitz's theo- 
 ry of elh'ptical motion, we may alk, What is this paracen- 
 tric force ? He calls it like gravity. This is precifely 
 Newton's doftrine. But Leibnitz fuppofes this alfo to 
 be the impulfe of a fluid. It would have been enough 
 had he explained the aftion of this fluid, without the 
 other circulating harmonically. He defers this expla- 
 nation, however, to another opportunity. It muft have 
 very lingular properties : it muil impel the planet with- 
 out difturbing the other fluid, or being difturbed by it. 
 He alfo defers to another opportunity the explaining 
 how the fquares of the periodic times of different pla- 
 nets are proportional to the cubes of the mean dillances; 
 for this is quite incompatible with the harmonic circu- 
 lation of his vortex. This would make the fquares of 
 the periods proportional to the diftances. He has per- 
 formed neither of thefe promifes. Several years after 
 this he made a correftion of one of his mathematical 
 blunders, by which he deftroyed the whole of his de- 
 monflration. In fliort, the whole is fuch a heap of ob- 
 fcurc, vague, inconfiftent aflumptions, and fo replete with 
 mathematical errors, that it is aftonifliing that he had 
 57 the ignorance or the effrontery to publifti it. 
 Hypothefis There is another hypothefis that has acquired fome 
 of Le Sage, reputation. M. le Sage of Geneva fuppofes, that there 
 pafles through every point of the uiiivcrfe a ftream of 
 fluid, in every direction, with aftoniniing velocity. He 
 fuppofes that, in the denfeft bodies, the vacuity is in- 
 comparably more bulky than the folid matter ; fo that a 
 folid body fomewhat refembles a piece of wire cage- 
 work. The quantity of fluid which pafles through will 
 be incomparably greater than that of the intercepted 
 fluid ; but the impulfe of the intercepted fluid will be 
 fenfibly proportional to the quantity of folid matter of 
 the body. A Angle body will be equally impelled in 
 every direiSion, and will not be moved ; but another 
 body will intercept fome fluid. Each will intercept 
 fome from the other ; and the impulfe on B, that is in- 
 tercepted by A, will be nearly proportional to the mat- 
 ter in A, and inverfely proportional to the fquare of 
 its didance from B ; and thus the two bodies will ap- 
 pear to tend toward each other by the law of gravita- 
 tion. 
 
 Tvj'. le Sage publiflied this in a work called Chimie 
 Mech.iniijue, and read lectures on this doftrine for many 
 years in Geneva and Paris to crowded audiences. It is 
 alfo pubhflaed by Mr Prevofl. in the Berlin Memoirs, 
 
 N O M Y. 
 
 under the name of Lucrccc Newtonitnt and there ar* 
 many who confider it as a good explanation of gravita- 
 tion : for our part, we think it inconceivable. The 
 inotions of the planets, with undiminiflied velocity, for 
 more than four thoufand years, appears incompatible 
 with the impelling power of this fluid, be its velocity 
 what it will. The abfolute precilion of the law of gra- 
 vitation, which does not fliew the fmallell error during 
 that tiine, is incompatible with an impulfe which cannot 
 be exadly proportional to the quantity of matter, nor 
 to the reciprocal of the fquare uf the diftance, nor the 
 lame on a body moving with the rapidity of the comet 
 of 1680 in its perihelion, as on the planet Saturn, 
 whofe motion is almofl incomparably flower. What is 
 the origin of the motion of this fluid : Wliv does it 
 not deilroy itfclf by mutual impulfe, fmce it is conti- 
 nually palfuig through every point ] Sec. 
 
 We have already obferved that Newton exprefled thej;,),^^ ^f 
 fame anxiety to avoid the fuppofitlon of aftion among Nfwton 
 bodies at a dillance. He alfo ftemcil to fliow fome dif-'"'^'^*"" 
 pofition to account for gravitation by the action of a * 
 
 contiguous fluid. This is the fubterfuge fo much re- 
 curred to by precipitate fpeculatilts, by the name of 
 the elhef of Sir Ifaac Neivton. He fuppofes it highly 
 claft:ic, and much rarer in the pores of bodies, and in 
 their vicinity, than at a diiT:ance ; therefore exceedingly 
 rare in the fun, and denfer as we recede from him. Be- 
 ing highly elalT.ic, and repelled by all bodies, it muft 
 impel them to that fide on which it is moft rare ; there- 
 fore it muft impel them toward the fun. This is enough 
 of its general conftitution to enable us to judge of its 
 fitnefs for Newton's purpofe. It is wholly unfit ; for 
 fince it is fluid, unequally denfe and elaftic, its particles 
 are not in contact. Particles that are elattic, and in a 
 ftate of compreffion, and in contaft, cannot be fluid ; 
 they muft be like fo many blown bladders compreffed in 
 a box; therefore they are not in contact; therefore they 
 are elaftic by mutual repulfion ; that is, by afting on 
 each other at a diftance. It is indifferent whether this 
 diftance is a million of miles, or the millionth part of a 
 hair's breadth ; therefore this fluid does not free Newton 
 from the fuppofition which he wifhes to avoid. Nay, it 
 can be dcmonftrated, that in order to form a fluid 
 which fliall vary in denfity from the fun to the extre- 
 mity of the folar fyftem, there muft be a mutual repul- 
 fion extending to thai dijlance. This is introducing mil- 
 lions of millions of the very difficulties which Newtor> 
 wifhed to avoid ; for each particle prefents the fame 
 difficulty with a planet. 
 
 We would now afl< thefe atomical philofophers, why 
 they have, in all ages, been fo anxious to trace the ce- 
 leftial motions to the cffefts of impulfe ? They imagine 
 that they have a clear perception of the communication 
 of motion by impulfe, while their perception of the pro- 
 duftion of it in any other way is obfcure. Seeing, in 
 a very numerous and familiar collcftion of fafts, that 
 motion is communicated by impulfe, they think that it 
 is communicated in no other way, and that impulfe is 
 the only moving power in nature. -- 
 
 But is it true that our notion of impulfe is more clear Ournotio 
 than that of gravitation \ Its being more familiar is no°f ""P"^' 
 argument. A caufe may be real, though it has exerted !'|°"'^'' 
 itfelf but once fince the beginning of time. In no cafe vitation. 
 do 1st perceive the exertion of the caule ; we only per- 
 ceive the change of motion. The conftitution of our 
 
 mind
 
 A S T R 
 
 mind makes us confider tin's as an ciFoft, indicating a 
 caufe which is inherent in that body which we always 
 fee aflbciated with that change. Granting that our per- 
 ception o( the perfeverance of matter in its Hate of mo- 
 tion is intuitive, it by no means follows that the body 
 A in motion muft move the body B by llriking it. 
 The moment it ftrikes B, all the metaphyiical argu- 
 ments for A's continuance in motion arc at an end, and 
 they are not in the lead affeifled by the fiippofition that 
 A and B Ihould continue at reft atttr the ilroke ; and 
 we may defy any perfon to give an argument which will 
 prove that B will be moved; nay, the very exillence of 
 B may, for any thing we know to the contrary, be a 
 fufficient reafon for tlie cefTation of the motion of A. 
 The produftion of motion in B, by the inipulfe of A, 
 mull therefore Hand on the fume foundation with every 
 other produttion of motion. It indicates a moving 
 power in A ; but this inherent power feems to have no 
 dependence on the motion of A : (See what is con- 
 tained in n^Si. of the ai-ticle Physics, and n^ 67. of 
 0?Tics of the Encyil.) We fee there a motion pro- 
 duced in B without inipulfe, and taken from A, fimilar 
 in every refpccft to every cafe of inipulfe ; and we fee 
 that the motion of A is neceffary for producing fuch a 
 motion in B as is obferved in all cafes of impnlfe. mere- 
 ly in order that the moving power, which is inherent 
 in A, whether it be in rett or in motion, may aft du- 
 ring a fufficient time. Our confidence in the commu- 
 nication ot motion, in the cafe mentioned there, is de- 
 rived entirely from experience, which inl'orms us that 
 A pofleflcs a moving power totally different from im- 
 pulle. Our belief of the impelling power of matter 
 therefore does not neceftarily flow from our intuitive 
 knowledge of the perfeverance of matter, although it 
 gives us the knowledge of this perfeverance. It is like 
 a mathematical demonltration, a road to the difcovery 
 of the property of figure, but not the caufe of that 
 property. The impullion of matter is nn-rely a faft, 
 like its gravitation, and we know no more of the one 
 than of the other. 
 
 It is not a clearer perception, therefore, which has 
 procured this preference of impulfion as the ultimate 
 explanation of motion, and has given rife to all the fool- 
 i(h hypolhefes of planetary vortices, ethers, animal fpi- 
 rits, nervous fluids, and many other crude contrivances 
 for explaining the abttrufe phenomena of nature. 
 
 Nor does it dcfcrve any preference on account of its 
 greater familiarity. Juft the contrary ; for one faft of 
 undoubted impulfe, we fee millions where no impulfe is 
 obferved. Confider the motion produced by the cxplo- 
 fion of gunpowder. Where is the original impulfe ? Sup- 
 pofe the impulfe of the firft fpark of fire to be inimenfe, 
 how comes it that a greater impulfe is produced by a 
 greatei- quantity of gunpowder, a greater quantity of 
 quiefcent matter ? The ultimate impulfe on the bullet 
 lliould be lefs on this account. Here are plain exer- 
 tions of moving powers, which are not reducible to im- 
 pulfe. Confider alfo the fafts in animal motion. Re- 
 fleft alfo, that there has been more motion, without any 
 obferved impulfe, produced in the waters of a river fince 
 the beginning of the world, than by all the impulfe that 
 man has ever obferved. Add to thefe, all the motions 
 in magnetifm, eleftricity, &c. Impulfe is therefore a 
 phenomenon which is comparatively rare. 
 
 Have we ever obferved motion communicated by pure 
 
 O N O M Y. 
 
 impulfe, without the aftion of forces at a diftanco ? 
 This appears to us very doubtful. Every one acquaint, 
 ed with Newton's difcoveries in optics will grant, that 
 tlie colours which appear between two objeitglafles of 
 long- iclclcopes, when they are pr'effed together, de- 
 monftrate that the glalfes do not touch each other, ex- 
 cept in the place where there is a black fpot. It re- 
 quires more than athoufaud pounds to produce a fquare 
 inch of this fpot. Therefore every cominunication of 
 moiion betwei.n two pieces of glals, which can be pro- 
 duced by one of them ftriking the other, is produced 
 without impulfe, unlefstheirmutual prcffure has exceeded 
 1000 pounds on the Iquare inch of the parts which adl 
 on each other. Nay, fince we fee that a black fpot ap- 
 pears on the top ot a foap bubble, in the middle of the 
 coloured rings, we learn that there is a certain thick- 
 iiefs at which light ceafes to be vifibly refltfted ; there- 
 fore the black ipot between the glafles does not prove 
 that they touch in that part ; therefore we cannot fay 
 that any force whatever can make them touch. The 
 ultimate repulfion may be infuperable. If this be the 
 cafe, the production of motion by impulfe is, in every 
 inlfance, like the prodi.ftion of motion between the 
 magnets in n"8l. of the article Physics in the Encycl. 
 
 5» 
 
 and is of the fame kind with the production of motion 
 
 by gravity. ... 61 
 
 Therefore no explanation of gravitation can be de- Intervening 
 rived from any hypothefis whatever jf intervening fluids: fluids mul- 
 They only fubllitute millions of bodies for one, and Hill"''*. '''^" 
 leave the aftion e dijlanli tiie fame difficulty as before. ' 
 
 It is not in the leait necelfary that we fliall be able to 
 conceive how a particle of matter can be influenced by 
 another at a diflance ; if we have difcovercd in every 
 inilance the precife degree and diredlion of the effeft 
 of this influence, we have made a nioft important addi.. 
 tion to our kiiewledge of nature ; and our fuccefs in 
 the cafe ot the power of gruvity (liould make us aflidu- 
 ous in our endeavours to difcover, from the phenomena, 
 the laws which regulate the other adtions e d'ljlani't, 
 which oblervation is daily finding out. A knowledge 
 equally accurate of the law of magnetic and electric ac- 
 tion may enable us to give theories of magnetifm and 
 eletlricity equally exait with the Newtonian theory of 
 gravitation. 
 
 Having, we hope, evinced the truth of this theory, 
 by following ou- the inveftigations to which Newton 
 was gradually led, we might proceed to confider, in or- 
 der, the complicated and iubordinate phenomena which 
 depend on it. The lunar and planetary iiicqualitics are 
 the fubjeft s that naturally come firil in our way ; but 
 they have already been explained in all the detail that 
 this concile account -will admit, as they occurred to 
 Newton as tells of tlie truth of his conjecture. If the 
 law be fuch as he fufpedled, its confequenccs niufl be fo 
 and fo; if the celeftial motions do not agree with them, 
 the law nmft be rejefted. We (hall not repeat any thing 
 therefore on this head, but confine our obftrvations to 
 fuch applications of the theory of univerfal gravitation, 
 as newly difcovered objcfts, or the improvement of af- 
 tronomical obfervation and of fluxionary analyfis, have 
 enabled us to make fince the time of Newton. 
 
 The fubferviency of the eclipfes ot Jupiter's fatel- 
 
 lites to geography and navigation had occafioned their 
 
 motions to be very carefully obferved, ever fince thefe 
 
 ufes of them were firll fuggefted by Galileo, and their 
 
 G 2 theory
 
 52 
 
 ASTRONOMY. 
 
 123 
 61 
 26 
 
 theory is as far ativanced as (hit of the primary planets. 
 It has peculiar difficuhieF. B>;lng very near to Jupiter, 
 the great deviation of his figine from perfett fphericity 
 makes the relation between then- diftances from his 
 centre and their gravitations toward it vaftly complica- 
 ted. But this only excited the mathematicians fo much 
 the more to improve their analyfis; and they faw, in 
 this little fyllem of Jupiter and his attendants, an epi- 
 tome of the iolar n (km, where the great rapidity of 
 the motions mud bring about in a Ihort time every va- 
 riety of configuration or relative pofition, and thus give 
 us an example of thofe mutual diiturbances of the pri- 
 mary planets, which req\nre thoufands of years for the 
 dil'covery of their periods and limits. We have derived 
 g2 fome verv remarkable and uleful pieces of intornation 
 Etertial du-from this inveftigation ; and have been led to the dif- 
 jability uf covery of the eternal durability of the folar fyftem, a 
 fvain'^"^ thing which Newton greatly doubted of. 
 ' "^ Mr Pound had obfcrved long ago, that the irregula- 
 
 rities of the three interior fatellites were repeated in a 
 period of 4^7 days ; and this obfervation is tound to be 
 juft to this day. 
 
 247 revolutions of the firft occupy 437d. 3h. 44' 
 fecond 437 3 42 
 
 third 437 3 36 
 
 fourth 435 14 16 
 
 This naturally led mathematicians to examine their mo- 
 tions, and fee in what manner their relative pofitions or 
 configurations, as they are called, correfponded to this 
 period : and it is found, t!iat the mean langitude of the 
 firft fatellite, tninus thrice the mean longitude of the fe- 
 cond, p/us twice the mean longitude of the third, al- 
 ways made iSo degrees. This requires that the mean 
 motion of the firft, added to twice that of the third, 
 fhall be equal to thrice the mean motion of the fecond. 
 This correfpondence of the mean motions is of itfelf a 
 Angular thing, and the odds againft its probability fcems 
 infinitely great ; and when we add to this the particu- 
 lar pofitions of the fatellites in any one moment, which 
 is necefTaiy for the above conftant relation of their lon- 
 gitudes, the improbability of the coincidence, as a thing 
 quite fortuitous. Becomes infinitely greater. Doubts 
 were firft entertained of the coincidence, becaufe it was 
 not indeed accurate to a fecond. The refult of the in- 
 veftigation is curious. When we follow out the con- 
 fequences of mutual gravitation, we find, that although 
 neither the primitive motions of projeftion, nor the 
 points of the orbit from which the fatellites were pro- 
 jefled, were prccifely fuch as fuited thefe obierved rela- 
 tions of their revolutions and their contemporaneous 
 longitudes ; yet, if they differed from them only by 
 very minute quantities, the mutual gravitations of the 
 fatellites would in time bring them into thofe pofitions, 
 and thofe ftates of mean motion, that would induce the 
 obfcrved relations ; and when they are once induced, 
 thev will be continued for ever. There will indeed be 
 a fmall equation, depending on the degree of unfuit- 
 ablenefs of the firft motions and pofitions ; and this 
 caufes the whole fyftem to ofcillate, as it were, a little, 
 and but a very little way on each fide of this exaft and 
 permanent ftate. The permanency of thefe relations 
 vill not be detlroyed by any fecular equations arifing 
 from external caufes ; fuch as the attion of the fourth 
 fatellite, or of the fun, or of a refifting medium ; be- 
 
 caufe their mutual afti^n? will diilribute this equatiott 
 as it did the original error. 
 
 This curious rtfult came into view only by degrees, 
 as analyfis improved and the mathematicians were ena- 
 bled to manage more complicated formulas, including 
 more terms of the infinite lerieies that were employed 
 to exprefs the different quantities. It is to M. de la 
 Grange that we arc indebted for the completion of the 
 difcovcry of the permanency of the fyftem in a ftate 
 very little different from what obtains in any period of 
 its exillence. Although this required all the knowledge 
 and addrefs of this great mathematician, in the manage- 
 ment of the moll complicated analyfis, the evidence of 
 its truth may be perceived by any perfon acquainted 
 with the mere elements of fluxionary geometry. The 
 law of the compofition of forces enables us to exprefs 
 every aftion of the mutual forces of the fun and planets 
 by the fines and cofines of circular arches, which in- 
 ciealc with an uniform motion, like the perpetual lapfa 
 of time. The nature of the circle fhows, that the va- 
 riations of the fines and coiines are proportional to the 
 cofines and fines of the fame arches. The variations of 
 their fquares, cubes, or other powers, are proportional 
 to the fines or cofines of the doubles or triples, or other 
 multiples of the fame arches. Therefore fince the in- 
 finite fericfes which exprefs thofe aflions of forces, and 
 their variations, include only fines and cofines, with 
 their powers and fluxions, it follows, that all accumu- 
 lated forces, and variations of forces, and variations of 
 variations, through infinite orders, are Itill expreflible by- 
 repeated fumsof fines or cofines, correfponding to arch- 
 es which are generated by going round and round the 
 circle. The analyft knows that thefe quantities become 
 alternately pofitive and negative ; and therefore, in 
 whatever way they are compounded by addition of 
 themfelves, or their multiples, or both, we mull always 
 arrive at a period after which they will be repeated with 
 all their iuteiincdiate variations. It may be extremely 
 difficult, it may be impoiTible, in our prefcnt ftate of ma- 
 thematical knowledge, to afcertain all thofe periods. It, 
 has required all the efforts of all the geniufes of Europe 
 to manage the formulas which include terms containing 
 the fourth and fifth powers of the eccentricities of the 
 planetary orbits. Therefore the periods which we have 
 already determined, and the limits to which the inequa- 
 lities expreffed by fecular equations arrive, are ftill fub- 
 jefted to fmaller corrcftions of incomparably longer 
 periods, which arife from the terms neglefted in our 
 formulas. But the correft ion arifing from any negleft- 
 ed term has a period and a limit ; and thus it will hap- 
 pen that the fyftem works itfelf into a ftate of perma.. 
 nency, containing many intervening apparent anomalies. 
 The elliptical motion of the earth contains an anomaly 
 or deviation from uniform circular motion ; the aftion 
 of Jupiter produces a deviation from this elliptical mo- 
 tion, which has a period depending on the configuration 
 of the three bodies; Saturn introduces a deviation from 
 this motion, which has alfo a period ; and fo on. 
 
 There is another accurate adjuftment of motions 
 which has attrafted attention, as a thing in the higheft 
 degree improbable, in events wholly independent on each 
 other. This is tlie exatl coincidence of the period of 
 the moon's revolution round the earth with that of her 
 rotation round her own axis. The ellipticity or oval 
 fbape of the moon differs fo infeafibly from a fphere, 
 
 that
 
 ASTRO 
 
 that if the original rotation had differed confidc'rably 
 from the period of revolution, the ])eiidular tendency to 
 the earth could never have operated a change : but if 
 the difference between thofe two motions was fo fmall 
 that the pendular tendency to the line joining the cen- 
 tres of the earth and moon was able to overcome it af- 
 ter fome time, the pole of the lunar fpheroid would de- 
 viate a little from the line joining the earth aiid moon, 
 and then be brought back to it with an accckrated 
 motion ; would pafs it as far on the other fide, and 
 then return again, vibrating perpetually to each fide of 
 
 N O M Y. 
 
 53 
 
 tioii of its effedls after a long time. It is only thus that 
 the effeds of the oblate figure (if Jupiter are perceived 
 in the motion of his fatelliles. The boafted found phi- 
 lofophy, which fees fatal necefTity where the mnft fuccefs- 
 fuljludcnts of nature (aw moral excellence, has derived 
 very little credit or title to the name of w//i&?fl, by let- 
 ting loofe all thofe propenfities of the human heart 
 which arc cfltntially deffruftive of focial happiiiefs. 
 Thefe propenfities were always known to lurk in the 
 heart of man ; and thofe furcly were the wifeit who k- ce- the wifl 
 boured to keep them in check by the influence of moral '-^'•'" "f 'lie 
 
 ^^^ AnH evin- 
 
 63 
 
 spends 01 
 e Jaw of 
 metary 
 fledtioii, 
 
 the mean pofition of the radius veSor. The extent of principles, and particularly by cherifiiing that difpofition Creator. 
 
 ^ "^ of the human heart which prompts us to fee contrivance 
 
 wherever we fee nice and refined adjuftment of means 
 to ends ; and, from the admirable beauty of the folar 
 fyftem, to cry out, 
 
 " Thefe are thy glorious works. Parent of good ! 
 " Almighty, thine this univerfal frame, 
 " Thus woiid'rous fair; thyfelf how wond'rous thenl 
 " Unfpeakahle, who fitt'll above thefe heavens, 
 " To us invifible, or dimly feen 
 " In thefe thy loweil works ; yet thefe declare 
 " -l- hy goodnefs beyond thought, and power divine." 
 
 Par. Lojt, b. V. 
 " But wandering oft, with brute unconfcious gaze, 
 " Man marks not Thee, marks not the mighty hand 
 " That, ever bufy, wheels the filent fphcres." 
 
 Thomson. 
 The mod important addition (in a philofophical view) 
 that has been made to aitronomical fcience fines ths 
 difcovery of the aberration of light and the nutation of 
 the earth's axis, is that of the rotation of Saturn's ring. (,- 
 The ring itfelf is an objeft quite Angular; and when "it Satm-iVs 
 was difcovered that all the bodies which had any imme-'''''E- 
 diate connexion with a planet were heavy, or gravita. 
 ted toward that planet, it became an interelling qucf- 
 tion, what was the nature of this ring ? what fupport- 
 ed this immenfe arch of heavy matter without its reft- 
 ing on the planet ; what maintains it in perpetual con- 
 centricity with the body of Saturn, and maintains its 
 furface in one invariable pofition ? 
 
 The theory of univerfal gravitation tells uj what 
 things are poflible in the folar fyftem ; and our conjec- 
 tures about the nature of this ring muft always be re- 
 gulated by the circumftance of' its gravitation to the 
 planet. Philofophers had at firll fuppofed it to be a 
 luminous atmofphere, thrown out into that form by the 
 great centrifugal force arifing from a rotation ; but its 
 well defined edge, and, in particular, its being two very 
 narrow rings, extremely near each other, yet perfeftly 
 foparate, rendered this opinion of its conftitution more 
 improbable. fg 
 
 Dr Herfchel's difcovery of brighter fpots on its fur- r'''^" very 
 face, and that thofe fpots were permanent during the""^ '^'' *^'''" 
 whole time of his obfervatlon, fcems to make it more['|,"^'/f'''" 
 probable that the parts of tlie ring have a foliil connec- 
 tion. Mr Herfchel has difcovered, by the help of 
 thofe fpots, that the ring turns round its axis, and that 
 this axis is alfo the axis of Saturn's rotation. The time ' 
 
 of rotation is loh. 32^. But the other circumllances 
 are not narrated with the precilion fufficient for an ac- 
 
 tliis vibration would depend 011 the original difference 
 between the motion of rotation and the mean motion of 
 revolution. This difterence muft have been very fmall, 
 becaufe this pendular vibration is not fenfible from the 
 earth. The obferved libration of the moon is pre- 
 cifely what arifes from the inequality of her orbital mo- 
 tion. For the fame reafons, the effefts of the fccular 
 equations of the moon (which would, in the courfe of 
 ages, have brought her whole furface into our view, had 
 her rotation been ftriftly uniform) arc counteracted by 
 her pendular tendency, which has a force fufficient to 
 alter her rotation by nearly the fame flow and iiifenfible 
 changes that obtain in her mean motions. The fame 
 caufes alfo preferve the nodes of her equator and of her 
 orbit in the fame points of the ecliptic. The complete 
 demonftration of this is perhaps the moft delicate and 
 elegant fpecimen that has been given of the modern an- 
 alyfis. We owe it to M. de la Grange : and he makes 
 it appear that the figure of the moon is not that which 
 a fluid fphere would acquire by its gravitation to the 
 earth ; it nm^ W the effeft of a more confiderable el- 
 lipticity, or internal inequality of denfity. 
 
 This permanency of the fyftem, within very narrov/ 
 limits ot deviation from its prefent ftate, depends entire. 
 ly on the law of planetary deflcftion. Had it been di- 
 redtly or inverfely as the diftance, the deviations would 
 have been fuch as to have quickly rendered it wholly 
 unfit for its prefent purpofes. They would have been 
 very great, had the planetary orbits differed much from 
 circles; nay, had fome of them moved in the oppofite 
 direflion. The feledlion of this law, and this form of 
 the orbits, ftrikes the mind of a Newton, and indeed 
 any heart poffeffed of fenfibility to moral or intellettuaj 
 excellence, as a mark of wildom prompted by benevo- 
 lence. But De la Place and others, infefled with the 
 Tiieophohia Gallicii engendered by our licentious de- 
 fires, are eager to point it out as a mark of fal.difm.. 
 They fry that it is tffential to all qualities that are dif- 
 fufcd from a centre to diminifn in the inverfe duplicate 
 ratio of the diftance. But this is falfe, and very falj'e : 
 it is a mere geometrical conception. We indeid fay, 
 that the denfity of illumination decreafes in this propor- 
 tion ; but who fays that this is a quality ? Whether it 
 be confidcred as the emiffion of luminous corpufcles, or 
 an undulation of an elaltic fluid, it-is not a quality ema- 
 nating from a centre : and even in this eftimation, it 
 feems gratuitous, whether we (hall confider the bafe of 
 the luminous pyramid, or its whole contents, as the ex- 
 preffion of the quantity. Nay, if all qualities muft di- 
 niini(h at this rate, all aftion e J'ljlanti muft do the fame; 
 
 for when the diftances bear any great proportion to the curate comparifon with the tlieory of gravity. He in- 
 diameters of the panicles, their action deviates infenfibly forms us, that the radii of the four edges of the ring are 
 from this law, and is perceived only by the accumula- 590, 751, 774, 830, of a certain fcale, and that the 
 
 angle
 
 54 
 
 A S T' R O 
 
 angle fubtended hy the ring at the mean diflance from 
 the earth 1846'". Therefore its eh)ngation is 23 f'. 
 Tiie elon9;:ition of the fecond Cafuiiian fatcUite is 56', 
 and its revolution is. id. I7h. 44'. This (hould give, 
 by the third h*! of Kepler, 1 yh. 10' for the revolution 
 of the outer edge of the ring, or rather of an atom of 
 that edge, in order that it may maintain itfelf i.i equi- 
 librio. The fame c;dculation applied to the outer edge 
 of the inner ring gives about i3h. 36' ; and we obtain 
 Ilh. 16' for tlie inner edge of this ring. Such vane- 
 ties are inconfillent with the permanent appearance of a 
 fpot. We may fuppofe the ring to be a luminous fluid 
 or .-apour, eacli particle of which maintains its lituation 
 by tiie law of pi uietary revolution. In fuch a ilate, it 
 would coniill ot concentric ftrata, revolving more flowly 
 as they were more remote from the planet, like the con- 
 centric ftrata of a vortex, and therefore having a relative 
 motion incompatible with the permanency of any fpot. 
 Befides, the rotation obfervcd by Herfchel is too rapid 
 even for the innermoft part of the ring. We think 
 therefore that it confifts of cohering matter, and of con- 
 fiderable tenacity, at leaft equal to that of a very clam- 
 my fluid, fuch as melted glafs. 
 
 We can tell the figure which a fluid ring muft have, 
 fo that it may maintain its form by the mutual gravita- 
 tion of its particles to each other, and their gravitation 
 to the planet. Suppofe it cut by a meridian. It may 
 be in equilibrio i; the feftion is an ellipfe, of which the 
 longer avis is direfted to the centre of the planet, and 
 very fmall in comparifon with its dillance from the 
 centre of the planet, and having the revolution of its 
 middle round Saiurn, fuch as agrees with the Keplerean 
 law. Thef . circumftances are not very confiftcnt with 
 the dinienfions of Saturn's inner ring. The diftance 
 between the middle of its breadth and the centre of Sa- 
 turn is 070, and its breadth is 161', nearly one-fourth 
 of the diftance from the centre of Saturn. De la Place 
 fays, that the revolution of the inner ring obferved by 
 Herfchel is very nearly that required by Kepler's law : 
 but we cannot fee the grounds of this affertion. The 
 above comparifuns with the fecond CafTinian fatellite 
 (hows the contrary. The elongation of that fatellite is 
 taken from Bradley's obfervations, as is alfo its periodic 
 time. A ring of detathed particles revolving in loh. 
 32j' muft be of much fmaller diameter than even the in- 
 ner edge of Saturn's ring. Indeed the quantity of mat- 
 ter in it might be fuch as to increafe the gravitation 
 confiderably ; but this would be feen by its difturbing 
 t_ the feventh and fixth fatellites, which are exceedingly 
 Its proSa- near it. We cannot help thinking therefore that it con- 
 ble conDft- f,(ls of matter which has very conhderable tenacity. An 
 "^"^y equatoiial zone of matter, tenacious like melted glais, 
 
 and whirled bnfkly round, might be thrown off, and, 
 retaining its great velocity, would ftrctch out while 
 whirling, enlarging in diameter and diminilhing in thick- 
 jiefs or breadth, or both, till the centrifugal force was 
 balanced by the united force of gravit)' and tenacity. 
 We find that the equilibrium will not be fenfibly difturb- 
 ed by confiderable deviations, fuch as unequal breadth, 
 or even want of flatnefs. Such inequalities appear on 
 this ring at the time of its difparition, when its edge is 
 turned to the fun or to us. The appearances of its 
 different fides are then confiderably different. 
 
 Such a ring or rings muft have an ofcillatory motion 
 round the centre of Saturn, in confcquence of their mu- 
 
 N O M Y. 
 
 tual aftion, and the aclion of the fun, and their own ir- 
 regularities : but there will be a certain pofilion which 
 they have a tendency to maintain, and to which they 1 
 
 will be brought back, after deviatnig from it, by the 
 ellipticily of Saturn, which is very great. The fun 
 will occafion a nutation of Saturn's axis and a precef- 
 fion of his e<;uinoxes, and this will drag along with u 
 both the rings and the neighbouring fatellites. 
 
 The atmolphcre which iurrounds a whirling planet 
 cannot have all its parts circulating according to the 
 third law of Kepler. The mutual attrition of the pla- 
 net, and of the different ftrata, arifing from their diffe- 
 rent velocities, muft accelerate the ilowly moving ftrata, 
 and retard the rapid, till all acquire a velocity propor- 
 tional to their diftance from the axis of rotation ; and 
 this will be fuch that the momentum of rotation of the 
 planet and its atmofphere remains always the fame. It 
 will fwell out at the equator, and fink at the poles, till 
 the centrifugal force at the equator balances the weight 
 of a luperficial particle. - The greateft ratio which the 
 equatorial diameter can acquire to the polar axis is that 
 of four to three, unlefs a cohefive force keeps the par., 
 tides united, fo that it conftitutes a liquid, and not an 
 elaftlc fluid like air ; and an elaftic fluid cannot form. an 
 atmofphere bounded in its dimenfions, unlefs there be a 
 certain rarity which takes away all elafticity. If the 
 equator fwells beyond the dimenilon which makes the 
 gravitation balance the centrifugal force, it muft imme- 
 diately diffipate. 
 
 If we fuppofe that the atmofphere has extended to 
 this limit, and then condenfes by cold, or any chemical 
 or other caufe different from gravity, its rotation ne- 
 ceffarily augments, preferring its former momentum, and 
 the limit wdl approach the axis ; b^caufe a greater velo- 
 city produces a greater centrifugal force, and requires a gg 
 greater gi'avitation to balance it. Such an atmofphere And origi 
 may therefore defert, in fucceffion, zones of its own mat- 
 ter in the plane of its equator, and leave them revol- 
 ving in the form of rings. It is not unlikely that the 
 rings of Saturn may have been furnilhed in this very 
 way; and the zones having acquired a common velocity 
 in their different ftrata, will preferve it ; and they are 
 fufceptible of irregularities arifing from local caufes at 
 the time of their leparation, which may afford perma- 
 nent fpots. 
 
 We think that the rotation of Saturn's ring affords it mayfi 
 fome hopes of deciding a very important queftion about nidi the 
 the nature of light. If light be the propagation of'"'^*"5°' 
 
 elaftic undulations, its velocity depends entirely on the , °^"^' 
 1 n • • 11 I- r 1 n ■ 1 I • r • . . . , t! .e iiatm , 
 
 elafticity and deniity oi the fluid : but if it be the emif- ^f hght. ,, 
 
 fion of corpulclcs, their velocity may be affefted by 
 
 other caules. The velocity of Saturn'^ ring is y| of 
 
 that of the earth in its orbit, and therefore about To4trs' 
 
 of the velocity of light. The weftern extremity (to us 
 
 in the northern regions) is moving from us, and the 
 
 eaftern is moving toward us. If light, by which we fee 
 
 it, be reflefted like an elaftic ball from an elaftic body, 
 
 there will be an excefs in the velocity of the light by 
 
 which we fee the eaftern limb above the velocity of the 
 
 light by which we fee the weftern limb. This txctfs 
 
 will be ^Yss of the mean velocity of light. This fliould 
 
 be difcovered by a difference in the refraftion of the 
 
 two lights. If an acromatic prifm could be made to re- 
 
 fraft fourteen degrees, and if Saturn be viewed through 
 
 a telefcope with this prifm placed before it, there ftiould 
 
 be
 
 IM. AlIC \ I ,
 
 ASTRO 
 
 be a cliange of (liape amounting to fixteen ftconds ; if 
 the axis of the prifm be parallel to the longer axis of 
 the ring, it will diltort it prodigioufly, and give it an 
 oblique pofition. 
 
 A finnilar effeft will be produced by placing the prifm 
 between the eye-glafs and the image in the focus of the 
 objeAglafs. 
 
 Our expeftation is founded on this unquefllonable 
 principle in dyn:imics, that when a particle of light 
 pafles through the ailive ftratum of a tvanfparent body 
 which refrads light toward the perpendicular, the addi- 
 tion made to the fquare of its velocity by the refraft- 
 ing forces is equal to the fquare of the velocity which 
 thofe forces would communicate to a particle at rei'l on 
 the furface of this refrafting ilratum of the tranfparent 
 body. Therefore if the velocity of the incident light 
 be increafed, the ratio of the fine of incidence to the 
 fine of refraftion will be diminidied. It is confonant to 
 common fenfe, that when the incident light has a great- 
 er velocity, it pafles more rapidly through the attradling 
 ilratum, and a fmaller addition is made to the velocity. 
 When the velocity of the incident light is loooo times 
 greater than that of the earth's annual motion, the. fine 
 of incidence is to the fine of refrattion in glafs as 20 to 
 31, or as 10000 to 15500. If this be increafed tt'uoj 
 making it 10004, the ratio will be that of 10004 'o 
 I550>,62, or of loooo to 15496,4. The difference 
 between the refraftions of the light from the eaftcrn 
 and weftern extremities of the ring will be, to all fenfe, 
 the fame, if the velocity of the one be diminifhed to 
 9998, and the other increafed to tooo2. 
 
 We may juft add here, by the way, that the aftion 
 
 of another body may confiderably change the conftitu- 
 
 obable tion of this atmolphere. Thus, iuppofing that the 
 
 ifon why moon had originally an atmofphere, the limit v/ill be 
 
 ; fee no f]^^i diiVance from the moon where the centrifugal force, 
 
 .. ,u„ arifinsj from the moon's rotation, added to the eravita- 
 jut the . o , , , 1 • ■ , ° 
 
 ,on, tion to the earth, balances the gravitation to the moon. 
 
 If the moon be -j-'j-'l^ o'" "^'^^ earth, this limit will be 
 about -^th of the moon's diftance from the earth. If 
 at this diilance the clailicity of the atmofphere is not 
 annihilated by its rarefaction, it will be all taken off 
 by the earth, and accumulate round it. This may 
 be the reafon why we fee no atmofphere about the 
 moon. 
 
 What has been faid in the article Tide (EncycL), 
 will explain the trade-winds on the earth and in Jupi- 
 ter and Saturn. On the earth they are increafed by 
 the expanfion of the air by heat. This caufea it to rife 
 
 N O M Y. 55 
 
 in the parts warmed by the fun, and flow ofi" tovvaid the 
 poles, where it is again cooled and condenfed. The 
 under ftratum of colder and dcnfer air is continually 
 flowing in from the poles. Tliia having lefs velocity of 
 circulation than the equatorial parts of the earth, mufl 
 have a relative motion cuntrary to that of the earth, or 
 from call to well, and this nuili augment the cuiTent 
 produced by gravitation. 
 
 Thus we fee that all the mechanical phenomena of 
 the folar fyftcm, whether relating to the revolutions 
 round the various centres of gravitation, or to the figure 
 of the planets and the ofcillations of the fluids which 
 cover them, or to the rotations round their rcf)iei5live 
 axes — are neceffary confequeiices of one limple principle 
 of a gravitation in every particle, decreafing in the re- 71 
 ciprocal duplicate ratio of the diftance. We fee that AH the me- 
 tliis, combined with a primitive projection, will produce '^?^""^^ 
 every motion tliat we obferve. It was not neccllary, asjja of the 
 Copernicus imagined, to imprefs three motions on the fclav i'yf- 
 eartli : one, by which it was made to revolve round the"^™ fl°*^ 
 fun ; a fecond, caufing it to turn round an axis inclined?.™"', °"'^„ 
 to that ot Its orbit ; and a third, by which this axis de-^ipie, 
 fcribed that conic furface which forms the preceffion of 
 the equinoxes. One iinpulfe, not pafling through the 
 centre of the earth, nor in the plane of the ecliptic, will 
 produce the two firll motions, and the protuberant mat- 
 ter produced by the rotation will generate the third 
 motion, by the tendency of its parts to the other hea- 
 venly bodies. Without this principle, the elliptic mo- 
 tion of the planets and comets, tluir various inequali- 
 ties, fecular or periodical, thofe of the moon and of the 
 fatellites of Jupiter, the prectfTion of the equinoxes, the 
 nutation of the earth's axis, the figure of the earth, the 
 undulations of its ocean — all would have been imperfedl- 
 ly known, as matters of fa£l, wholly different from each 
 other, and folitary and unconnetted. It is truly de- 
 ferving admiration, that fuch an immenfe variety of im- 
 portant phenomena flow fo palpably from one principla, 
 of fuch fimplicity, and fuch univeriality, that no pheno- 
 menon is now left out unexplained, and predifted with 
 a certainty almoft equal to adtual obfervation. 
 
 Sluit tot'ies animos •ueterum torjerc Jophorum, ■ 
 ^uxque Jcholas hodie rauco certamine vexatit, 
 Ohvia confpiciinus, nubem peUenle Malheft. 
 Surglte mortales, terrenas mlltite euros, 
 jiique hhtc culigenit -u'lres iHgnofi ile mentis, 
 yl pecudum luLi /otige laleque remotte. 
 
 »^^"5«S®iV^'s!Vvv^•i 
 
 AST 
 \ ftrothe- ASTROTHEMATA, the places or pofitions of the 
 ftars, in an aftrological fcheme of the heavens. 
 
 ASTROTHESIA, is nfed by fome for a conftella- 
 tion or coUeftion of ftars in the heavens. 
 
 ASTRUM, or Astron, a conftellation or affem- 
 blage of ftars : in which fenfe it is diftinguifhed from 
 yfjier, which denotes a fingle ftar. Some apply the 
 term, in a more particular fenfe, to the Great Dog, or 
 rather to the large bright ftar in his mouth. 
 
 ASYMMETRY, the want of proportion, otherwife 
 
 A S Y 
 
 called incommenfuralility, or the relation of two quanti- Afymp. 
 ties which have no common meafure, as between i and '<""• 
 »/z, or the fide and diagonal of a fquare. « 
 
 ASYMPTOTES (fee Encyd.) v,re, by fome, di- 
 ftinguifiied into various orders. The afymptote is faid 
 to be of the firft order, when it coincides with the bafe 
 of the curvilinear figure ; of the fecond order, when it 
 is a right line parallel to the bafe ; of the third order, 
 when it is a right line oblique to the bafe; of the fourth 
 order, when it is the common parabola, having its 
 
 axia
 
 A U T 
 
 t 56 ] 
 
 A U T 
 
 Attar axis perpendicular to the bafe ; and, in general, of the 
 ^. J! + 2 order, when it is a parabola wliofc ordinate is al- 
 ;'j;^'''f'"3"°' ways as the n power of the bafe. The afymptote is ob- 
 lique to the bafe, when the ratio of the iiril fluxion of 
 the ordinate to tlie fluxion of the bafe approaches to an 
 allignable ratio, as its-limit ; but it is parallel to the 
 Ijafe, or coincides with ii, when this limit is not affign- 
 tible. • 
 
 ATTAR OF ROSES. See Rosf.s, Otter of, both in 
 the Eiicyclopsdia aivd in this Supplement. 
 
 AVANT Foss, or lYitch of ihc Counterfcarp, in for- 
 tification, is a wet ditch furrounding the counterlcarp 
 on the outer fide, next to the country, at the foot of 
 the glacis. It would not be proper to have fuch a 
 ditch if it could be laid dry, as it would then ferve as a 
 lodgment for the enemy. 
 
 AUBIGNE. See Stuart in this Supplement. 
 
 AUMIL, in Bengal, a native collector or manager 
 of a diftriel on the part of government. 
 
 AUTENK^A, a large and beautiful country in 
 Africa, lyuig to the eaft of the Cape of Good Hope, 
 and inhabited, part of it, by Dutch colonifts. The 
 word /lutentqua fignifies, in the Hottentot language, 
 «' a man loaded with honey :" a name which is not 
 improperly given to the country, iince, as you enter it 
 •from the Cape, you cannot proceed a flep without iee- 
 ing a thoufand fwarms of bees. The flowers on which 
 they feed fpring up in myriads ; and your attention is 
 engaged, and your courle fufpended, by the mixed 
 odours which exhale from them, by their colours and 
 variety, and by the pure cool air which you breathe. 
 Nature has made thefe enchanting regions like fairy 
 land. The calyxes of all the flowers abound with ex- 
 cellent juices, from which the bees extraft the honey 
 that they everywhere depofite in hollow rocks and trees. 
 
 This counti-y was viiited in 1782 by M. Vaillant, 
 •who calls it the moft delightful region in the univerfe ; 
 and fays, that, as he approached it, he beheld, from the 
 top of a very high mountain, an immenfe valley, adorn, 
 ed with agreeable hills, variegated in an infinite num- 
 ber of fliapes, and extending in an undulating manner 
 as far as the fea ; whilfl. enamelled meads, and the molt 
 beautiful pafturcs, ftill added to the magnificent fcene. 
 It abounds with fmall rivulets, which, flowing down 
 from the mountains, run into the fea through an hun- 
 dred different channels. The water of thefe rivirlets has 
 the colour of Madeira wine, and a ferruginous tatte ; 
 but our traveller did not examine whether this tafl;e and 
 colour proceed from their flowing through fome mine 
 in their paffage, or from the roots and leaves of trees 
 which they carry along with them. 
 
 The whole of Auteniqua, from the chain of moun- 
 tains which divides it from the country of that race of 
 Hottentots called Gonaquas to the fea, is inhabited by 
 feveral planters, who rear a number of cattle, make but- 
 ter, cut down timber, and colleft honey ; all of which 
 they tranfport to the Cape : but it appears that they 
 make not the moft of their fituation. •' Can it be be- 
 lieved (fays M. Vaillant), that the diueftors of the Com- 
 pany, for their own ufe, fliould order fliips to be fent 
 every year fi-om Amft;erdam, loaded with planks and 
 boards of every kind, whilfl; in this country there are 
 immenfe forefts, and the mofl: beautiful trees in the 
 world ? This abfurdity, however, is not at all aftonifh- 
 ing. The Company gratuitoufly furnifties the gover- 
 
 nor and all the officers with whatever wood they have Auteniqu 
 occalion for ; and it is delivered to them at their houfes ~~v~-" 
 without any expence. The governor therefore has no 
 pt:rfanal iiileixll to extend his views to this part of the 
 adminilliation, and to «bolifli an abufe fo prejudicial to 
 the colony." 
 
 But tlie coloniflis themfelves mull be a very indolent 
 and ilupid kind of people ; fmce, if our traveller de- 
 fcrves credit, they neglec\ advantages with which the 
 perional interell of the governor cannot polfibly inter- 
 fere. '■ I was filled with indignation (lays M. Vail- 
 lant) to fee people, who have wood within their reach, 
 employ it in commerce, and not have the courage to 
 build for themfelves habitable houies. They live in 
 wretched hovels, conilrufted of wicker-work, daul'cd 
 over with clay ; the ikin of a buffalo, fixed at the tour 
 corners to as many flakes, ferves them for a bed ; and 
 the door, which is at the fame time a window, is fliut 
 by a mat ; while two or three mutilated chairs, a few 
 pieces of plank, a kind of table, and a pitiful box of 
 two feet fquare, form all the furniture of thefe colonial 
 habitations. Thus is the pifture of the moft profound 
 mifery contrafted with the charms of this terreftrial pa- 
 radiie ; for the beauties of thefe regions extend even 
 beyond Auteniqua. The people, however, though 
 their houies be bad, live well. They have game and 
 falt-water fifli in abundance ; and enjoy exclufively, over 
 all the other cantons of ihefe colonies, the advantage 
 of having, for the whole year without interruption, ve- 
 getables of every kind in their gardens. For this they 
 are indebted to the excellence of the foil, and to its be- 
 ing naturally watered by fmall llreams, which crofs each 
 other in a thouland different directions, and, as one 
 may fay, lay the four feafons under contribution to fer- 
 tilize Auteniqua. Thefe ftrcams, which frequently over- 
 flow their banks, but never dry up, proceed from a caufe 
 well known; the high mountains towards the eaft, which 
 are covered with foieils, flop tlie clouds and the fogs 
 carried from the fea, and this occafions very abundant 
 rains." 
 
 In thefe mountainous regions, which, as well as the 
 plain, our author comprehends under the denomination 
 of ^luteniqua, there are multitudes of elephants, buffa- 
 loes, panthers, hyenas, and antelopes of every fpecies ; 
 and all thefe animals are hunted and killed by the na- 
 tives, as well for food as for the proteftion of their 
 flocks and herds from fuch of them as are beafts of 
 prey. Our author has eaten the flefti of every one of 
 them except the hyena ; and declares, that the foot of 
 an elephant, baked after the Hottentot manner, is one 
 of the moft delicious morfels that he ever tafted. He 
 gives dircdlions for hunting them all ; but warns his 
 readers from attacking elephants when he finds them in 
 droves, for then, he fayb, they are invincible. He even 
 thinks it exceedingly dangerous for one man, however 
 well armed, to attack a fingle elephant in the plain. 
 The buffalo he defcribes, contrary to moft other travel- 
 lers, as a timid animal, which never refills till his fitua- 
 tion becomes defperate; and he thinks that there would 
 be no difficulty in training him, if caught when a calf, 
 to the yoke like the bullocks of Europe. 
 
 The-kites and vultures of this country, our traveller 
 repreients as in the higheft degree voracious and ficrce,in- 
 fomuch that it is hardly pofllble to fright them from their 
 prey. He had on one occafion killed two buifaloes, 
 
 which
 
 A U T . [ 5 
 
 . which he ordered to be cut into very finall pieces, that 
 they might be more eafily ialted, and expofed after- 
 wards to the air and the fun. His wagons, as well as 
 the buflies and trees which iurroimdcd him and his peo- 
 ple, were loaded with tlso bloody fragments of thefe two 
 aniinals, and they had begun their operation of falling ; 
 but tn a fudden, while they were not expecting it, 
 they found themfelves attacked by flights of kites and 
 vultures, which, without exliibitlng the lead fymptoms 
 of fear, perched in the midft of them. The kites were 
 above all the moft impudent. They feized upon the 
 morlels of flefh, and even contended furioufly with his 
 people. " When they had each carritd away (fays he) 
 a pretty large piece, they retired to fome branch, at 
 the dillance often paces from us, and devoured it before 
 our eyes. Though we tired our fufees they were not 
 frightened, but returned inceflantly to the charge ; fo 
 that finding our powder walled in vain, we refolved to 
 keep them off with large poles until our provifioiis 
 ihould be quite dry. This manoeuvre, which for a 
 long time haralTed my people, did not prevent us from 
 being plundered without mercy ; but had we not em- 
 ployed it, nothing would have remained to us of our 
 two buffaloes." 
 
 This battle with the kites took place on the conliues 
 of the Dutch fettlements ; but when M. Vailiant had 
 with difficulty pafTed over the mountains which bound 
 them, the profpefts became more magnificent, the foil 
 feemed to be more fruitful and rich, nature appeared to 
 be more majefllc and grand, and the lofty mountains 
 prefented on all fides more charming and deliglitful 
 points of view than any that he had ever before met 
 with. Thefe fcenes, contrafted with the dry and parch- 
 ed fields of the Cape, made him exclaim, he fays, in 
 ecifacy,"" What! fiiall thefe fuperb regions be eternally 
 inhabited by tigers and lions ? What fpeculator, with 
 the fordid view only of eftablifhlng a kind of centre for 
 commerce, could have preferred the flormy Table Bay 
 to the numberlefs roads and commodious harbours which 
 are to be found on the eaflern coafls of Africa ? Thus 
 (continues he) was I reflefting within myfelf, whilft I 
 was climbing the mountain, and forming vain wKhes for 
 the conqueft of this beautiful couutiy, which the indo- 
 lent policy of the European nations will perhaps never 
 gratify." 
 
 If his defcription of its beauties and fertility be not 
 greatly exaggerated, it is indeed wonderful that either 
 the Dutch or fo'me other maritime power of Europe has 
 not long ago taken poffeffion of it. After he had paffed 
 the mountain, one could not, he fays, clioofe a more 
 agreeable or advantageous fpot than that upon which 
 he then was for eftablifning a thriving colony. The fea 
 advances through an opening of about a thoufand paces 
 in breadth, and penetrates into the country to the di- 
 ftance of more than two leagues and a half. The bafon 
 which it forms is more than a league in extent (he 
 does not fay whether in breadth or in circumference) ; 
 and the whole coall, both on the right and the left, is 
 bordered with rocks, which intercept all communication 
 with it. The land is watered by limpid and refrefhing 
 ftreams, which flow down on all fides from the eaftern 
 mountains ; and thefe mountains, crowned with majef- 
 tic woods, extending as far as the bafon, and winding 
 round it with a number of linuofities, exhibit a hun- 
 SuppL. Vol. I. Part I. 
 
 7 ] 
 
 A U T 
 
 dred groves, wliich are naturally variegated, and each Autctiiqua. 
 more agreeable than another. • 
 
 The author proceeding forwards about two days 
 journey, arrived at a bay known to navigators by the 
 name of the Bay of /i'^oa, but called by the colonifls 
 Blettenlerg's Bay, from its having been viljted fome 
 time before by a Governor Blettenbcrg, who ordered 
 his name, together with the year and day of his arrival, 
 to be engraven on a flone column. This bay is a little 
 beyond the limits of the country called Autenfqua; but 
 it is not foreign from the purpofe of this article to in- 
 fert in this place our traveller's account of it, and of the 
 country around it. 
 
 The bay itfelf, he fays, is very fpaeious, and has a 
 fufficient depth of water for the largeft vefTels. The 
 anchoring ground is fuie, and boats can fail to a beau- 
 tiful part of the fliore, which is not confined by the 
 rocks, as they are all there detached from one another. 
 By advancing a league along the coaft, the crews would 
 arrive at the moutti of a confiderable river called the 
 ^levr-Boom, where they would find water. Refrerti- 
 ments might be procured from- the inhabitants of tiie 
 environs ; and the bay would fupply them with excel' 
 lent fifh, with which it abounds. 
 
 This bay is one of thofe places where government 
 might eftablifh warehoufes and repohttn'ies for timber ; 
 and it is for this reafon that we have introduced it to 
 notice in this article. The foret^s around it, fays M. 
 Vailiant, are everywhere magnificent, and the trees 
 could be more eafily cut down than anywhere elfe ; for 
 it is not to fteep mountains that one muft go for wood, 
 as it Auteniqua ; it is here ready at hand ; and during 
 the fine monfoon might be traniported to the Cape with 
 little trouble and no rifk. The inexhauflible and fer- 
 tile lands in the neighbourhood of the bay, if once cul- 
 tivated, would produce abundant crops, and draw toge- 
 ther a great number of intelligent planters, on account 
 of the ready communication which they would have 
 with the Cape. In a word, the Company, continues 
 he, have nothing to do fo much for their own Intereft 
 as to form here a proper ef}ablifliment. To the general 
 profits of fuch an inlHtution, would be added thofe of 
 individuals, which could not fall to be of great import- 
 ance. They might, for example, cut down a certain 
 tree called Jlinking luood, and export it to Europe, 
 where it would undoubtedly be foon preferred to maho- 
 gany and every other kind of wood employed by cabi- 
 net makers. 
 
 The Hottentots, who in fcattered Iraah inhabit this 
 delightful country, our author defcribes as a faithful, 
 gentle, and rather timid race. He afSrms that they 
 have no religious impreffions whatever, nor any notion 
 of fuperior powers who govern the world. But this, if 
 not a wilful fallehood diftated by the philofophy of 
 France, is probably a miitake arifing from his fcanty 
 knowledge of their language, and total ignorance of the 
 meaning of their religious ceremonies. His great ma- 
 fter, as well as the maffer of his fedl, Lucretius, tnight 
 have taught him, that fear, if not a better principle, will 
 generate the notion of fuperior beings in the minds of 
 favages ; and from fear, by his own account, the inha- 
 bitants of Auteniqua are far from being free. He like- 
 wife affirms, and feems to confider it as much to their 
 credit, tliat this race of gentle beings, fo far from being 
 H a
 
 A U T 
 
 [ 5S ] 
 
 A X r 
 
 a prey to the paflion of jealoufy (as other travellers 
 have reprcfenttd the Hottentots in general), are fo cbli- 
 ging, as to lend their wives to travellers who viiit tlicm, 
 and that they actually accommodated his Hottentots in 
 this way. Auteniqua, as laid down in M. Vaillant's 
 map, lies between 33' 30' and 34*^ 5c' of fouth latitude, 
 and between 20'' ?.nd ly 40' of eall lon^'tude ; and 
 his rout through the country was from louth-wtll to 
 north-eaft, or nearly lo. 
 
 AUTOMATON. U'uler this title and that of 
 AndroidEs full credit was allowed in the Encyc'optdia 
 Bnlanmca to the ftory of M. de Kempel's mechanical 
 chtfs-flaytr, and a detail :it fome length was given of 
 the feats of that figure, as well as of fome other furjjri- 
 iing avtoninln. No man more readily admits the powers 
 of the flvilfnl mechanician than the writer of this lliort 
 article ; but having many years ago detefled the inipo- 
 fition which was pvaftifed on the public in fome parts 
 of Scotland by a circumforaneous mountebank, who 
 exhibited a figure apparently capable of writing a cer- 
 tain number of words, he has ever fmce fufpected im- 
 pofture in all automata which appear to have the power 
 of varying their motions according to circumflances. 
 With refpeft to the chifs-player, there is now fuflicient 
 evidence that his fufpicions were well founded. 
 
 In the defcription of this figure {Encycl. Vol. I. 
 p. 787.), " it is faid that the automaton could not 
 play unlefs M. de Kempel or his fubrtitute was near it 
 to direct its moves. A fmall box during the game was 
 frequently confulted by the exhibiter ; and herein con- 
 fided the fecret, which he faid he could in a moment 
 communicate." The fecret was indeed fimple : " A 
 well taught boy, very thin and fmall of his age, was 
 concealed in this box almnit immediately under the 
 chefs-board, and agitated the whole machine." This 
 we learn from Thomas Colhnfon, Efq; who was let in- 
 
 Axie. 
 
 to the fecret ct Drefdia by a gentleman of rank and ta- Au(n»ia- 
 lents, named 'Jofeph Fre'ulrick Fieyhere, by whom the ""'> 
 •vknlilv and foul of the chefs-playing figure had fome , 
 time before been completely difcovcred. Mr CoUinfon, 
 finding that Dr Hutton had given the fame credit with 
 us to the reality of mechanicdl cliefs-playing, undecei- 
 ved his friend, by communicating the difcovcry of Frey- 
 here in a letter, which the Doctor has with great pro- 
 priety publilhed in the Addend,i to his Mathematical 
 Dictionary, Mr Collinfon adds, and we doubt not 
 with trutii, that, " even after this abatement of its be- 
 ing ilri£tly an automaton, much ingenuity remains to 
 the contriver." This was in fome degree true of the 
 inechanifm of the writing figure, of which the compiler 
 of this article detected the bungling impofture of the 
 two exhibiters. The figure itfclf, with all the principles 
 of its motion, were very ingenioully conflrufted ; but 
 the two men who exhibited it were ignorant and awk- 
 ward, and could not conceal from a fcrutini/ing eye, 
 that the automaton wrote foinetimes well and fometimes 
 ill, and never wrote at all when they were both prefect 
 to the company. It was by infilling upon feeing them 
 both together, and threatening to expole the cheat to 
 the whole town, that the prefent writer prevailed upon 
 him who appeared to be the principal exhibiter, to con- 
 fefs in private that his companion was concealed be- 
 hind a fcreen, and to (how how, from thence, he direct- 
 ed the movements of the figure. 
 
 Conjugate AXIS, or Second Axis, in the ellipfc 
 and hyperbola, is the diameter paffing through the cen- 
 tre, and perpendicular to the tranfverfe axis ; and is the 
 ftiorteil of all the conjugate diameters. 
 
 Trunfverfe yfxis, in the ellipfe and hyperbola, is the 
 diameter paffing through the two foci and the two prin- 
 cipal vertices of the figure. In the hyperbola it is the 
 fliorteft diameter, but in the ellipfe it is the longeft. 
 
 B. 
 
 Bahrc't. "DAHRDT (Dr Carl Friedirich) was fo deeply con- 
 -_y^_ O cerned in a combination of philofophers formed, as 
 they faid, for the advancement of fcience and virtue, 
 that an account of his life muft be interefling, if it were 
 only to fhow the effe£ts of this philofophic culture on 
 liis own morals. We truil therefore that our readers 
 will be pleafed, perhaps improved, by the following nar- 
 rative, taken from documents the moll authentic, by a 
 man* whofe communications on other fubjefts do cre- 
 dit to this volume. 
 
 Carl Friedirich Bahrdt was, in 1741, born at Leip- 
 fig, where his father, then a parifh minifter, and after- 
 wards profeflbr of theology, died in 1775. It is natu- 
 ral to fuppofe that fuch a parent would be at due pains 
 to inftil into the mind of his fon the principles of piety, 
 virtue, and patriotifm, which is indeed a branch of vir- 
 tue ; but if fo, he lived to fee that his labour had been 
 
 « Set Pro- 
 feffor Rt*i- 
 ibn of Edin- 
 burgh's 
 Pmiifs of a 
 Can/piracy 
 egatnji all 
 the Rtligicns 
 and Govern 
 ments oj £u- 
 
 in vain. While yet at college, where the courfe of his 
 {Indies was calculated to fit him for the important of- * 
 fice of preaching the gofpel, the young man enlifted as 
 a hufiar in the Prufiian fervice ; but being bought off, 
 he returned to the univerfity, where, in I 76 1, he was 
 admitted to the degree of M. A. Soon afterwards he 
 became catechift in his father's church, was a popular 
 preacher, and in 1765 publifhed fermons, and fome 
 controverfial writings, which evinced that he pofTeiTed 
 both learning and genius. Neither learning nor genius, 
 however, nor both united, could attach him to the 
 caufe of virtue, or make him obferve even the common 
 rules of decorum ; for immediately after this publica- 
 tion he began to indulge in conviviality, and to give 
 fcope to his refentments in anonymous pafquinades, in 
 the higheft degree bitter and ofTenfive. From the fiiafta 
 of his malice no perfon was fafe. ProfefTors, magiftrates, 
 
 and- 
 
 Eahrclt.
 
 BAH 
 
 Baliriit. atiJ clfrgyman, had indeed his chief notice 
 "—v-"-" coudefcendcd occafionally to attack ftudents, and fpared 
 npt even his own comrades or his friends. 
 
 Whilil he was thus labouring to make enemies of all 
 to whom he was known, unfortunately, for his own cha- 
 racter, his temperament was what the atomical philofo- 
 phers (who can explain every thing by ethers and vi- 
 brations) call fanguine ; and he was, as he himfelf ac- 
 knowledged, a paffionate admirer of the ladies. Coming 
 home from his midnight revels, he frequently met in 
 his way a young girl neatly drefTed in a rofe-coloured 
 filk jacket and train, and a coftly fable bonnet ; and 
 one evening, after having, as he fays, indulged freely in 
 fome old Rhenifh, he faw her home to her lodgings. 
 Some time after this interview, the miftrefs of the houfe 
 (a Madam Godfchuflvy) came into his room, and faid 
 that the poor maiden whom he had debauched was preg- 
 rant. This was a misfortune tuhich he could not help ; 
 but as it would ruin his charafter if known, he gave to 
 the old lady a bond for 200 dahlers (about L.40 iler- 
 ling), to be paid by inftalments of twenty-five, to keep 
 the matter fecret. " The girl (he fays) was ft ii/i6/e Sind 
 good; and as her converfation, for which he had al- 
 ready paid, was agreeable, he did not difcontinue his 
 acquaintance." 
 
 It could not be fuppofed that fuch vifits, by a cler- 
 gyman, would pafs unobferved, however cautioufly 
 made, in the midfl of a town, of which the inhabitants 
 had been the indifcriminate objefts of his fatire ; and he 
 could hardly be furprifed when told by a friend, that 
 one Bel, a magiftrate whom he had lampooned, was 
 accquainted with the whole affair, and would bring it in- 
 to a court of juftice, unlefs the bond was immediately 
 retired. 
 
 This bond was the only evidence which could be pro- 
 duced againft Bahrdt, but it was fufficient to blaft his 
 character in Leipl'g, and muft therefore by any means 
 be removed out of the way. To accomplilTi this, how- 
 ever, was a matter of fome difficulty ; for neither he nor 
 his friend could raife the money. In this dilemma they 
 fell upon a contrivance worthy of themfelves. They 
 invited Madam Godfchu(ky to meet them in another 
 houfe to receive the 200 dahlers due to her by Bahrdt ; 
 but when (he was udiered into the room, and found no 
 perfon waiting for her but Bahrdt's friend, (he could 
 not be prevailed upon to produce the bond till the mo- 
 ney fliould be put into her hands, together with a pre- 
 fent to herfelf. The Gentleman tried to intimidate her. 
 He drew his fword ; fhowed her how men fence ; made 
 pufhes at the wall and then at her : but finding that flie 
 could not be frightened out of her fenfes, he threw avvai' 
 his fword, and endeavoured to take the bond from her 
 by force. It was fome time before he prevailed ; but 
 at laft getting the paper out of her pocket, he tore it 
 in pieces, opened the door of a clofet in which Bahrdt 
 
 was concealed, and laid, " There, you b ; theie is 
 
 the honourable fellow whom you and your whore have 
 bullied ; but it is with me you have now to do, and you 
 know that I can bring you to the gallows." 
 
 Bahrdt, from whole memoirs of himfelf this flory is 
 taken, admits that there was a great fquabble on the 
 occafion ; but he went home, comforting himfelf with 
 the belief that he (liould now have no farther trouble 
 from Madam Godfchu(l<y or her girl. He chanced, 
 however, to be millaken. The magiftrate Bel had fome 
 
 [ 59 ] BAH 
 
 but he how been made acquainted with this nefarious tranfac- 
 tion, and brought it into court on the day that our^ 
 hero was to make fome very reverend appearance at 
 church. The cafe of Bahrdt was now hopclefs ; for 
 after fome unfucccfsful attempts of his poor father to 
 fave him, he was obliged to give in his gown and band, 
 arid to quit Leipfig. 
 
 To a parent the public difgrace of a child is one of 
 the fcvereft calamities to which human nature is liable ; 
 but for this calamity the father of Bahrdt nuift have 
 been long prepared, as his fon appears to have been re- 
 markably undutiful. Of this we have one memorable 
 inftance recorded by himfelf. His lather, he fays, v.'as 
 fevere, and his own temperament hafty, fo that he fome- 
 times forgot himfelf. " One day (continues he) I laid 
 a loaded piftol on the table, and told him that he (hould 
 meet with that if he went on fo ; but I was then only 
 
 SEVENTEEN !" 
 
 On his being obliged to leave the place of his nati- 
 vity, the friends of Bahrdt, and in particular Semler, 
 an eminent theological writer, who had formed a very 
 favourable opinion of his talents, were afGduous in their 
 endeavours to procure an eftablifiiment for him elfe- 
 where ; but his high opinion of himfelf, his impetuous 
 and precipitant temper, and that fatirical habit which 
 he had fo freely indulged in his outfet in life, made 
 their endeavours long inefTeftual. At lad he got a 
 profeflbrlhip at Erlangen, then at Erfurth, and in 1771 
 at GiefTen. But in each of thefe places he was no 
 fooner fettled than he got into difputes with his col- 
 leagues and with the eftablifhed church ; for he was a 
 ftrenuous partizan of the innovations then attempted to 
 be made in the doftrines of Chrillianity. In his publi- 
 cations, which were generally anonymous, he did not 
 truft to rational difcuffion alone, but had recourfe to ri- 
 dicule and perfonal anecdotes, and indulged in the moll 
 cutting farcafras and grofs feurrility. 
 
 His love for convivial company continuing, his in- 
 come v/as infufficient for the craving demand. Finding 
 therefore that anecdote and flander always procured 
 readers, and poflefling a wonderful activity and facility 
 in writing, he never ceafed from publidiing lampoons 
 and fatires, in which he fpared neither friends nor foes. 
 But it was impoffible to prevent thefe publications from 
 being traced to their author; and his avowed theological 
 writings being fuch as could not be fufFered in a pro- 
 feilbr of divinity, the hoft of enemies which he had been 
 at fo much pains to raife againft himfelf, were furnifiied 
 with fufficient grounds for fubjc<fting his conduft to le- 
 gal cognlr.ance ; even tlie very ftudents at Giefleii were 
 (hocked at fome of his liberties. 
 
 The couftquence of all this was, that, after much 
 wrangling in the church judicatories, he was jutt abont 
 to be dilmiffed from his pvofefl"or{liip, when he got an 
 invitation to Marlchlins in Switzerland to fuperinteuJ 
 an academy. 
 
 To Marfchlins he went about the year 177(5, and 
 began his new career by forming the fcminary after the 
 model of an academy which had fome time before been 
 fet up in the principality of Anhalt Dedau by one Bn- 
 fedow, a man of talents and learning, who gave to it 
 the appellation of philanthropine. The plan of this 
 academy was very different from thofe of the univerfi- 
 tles ; for its author profeffed to confider languages, 
 fciences, and the ornamental exercifes, as mere accelfo- 
 H 2 ries, 
 
 Bahrdt.
 
 BAH [60 
 
 Eahrdf. ries, liia aim being to foim the younff minil to the love 
 V of mankind and of virtue, by a courfe of moral educa- 
 tion certainly fpecious, and apparently unexceptionable. 
 To make this novel inftitution the more extenfivtly ufe- 
 ful, the rules by which the education was to be con- 
 duced were framed in fuch a manner as, it was thought, 
 would remove from the minds of Catholics, Lutherans, 
 and Calvinith, all uncalinefs rcfpefting the faith of their 
 children, as it related to thofc particular tenets which 
 feparated them into different communions. It was even 
 propofed to baniih from the philanthropine all pofillve 
 religion whatever, and to intlruCt the youth educated 
 there in the principles only of natural, or, as it was 
 called, philofophicil religion. 
 
 This plan was peculiarly fnited to Bahrdt's tafte, be- 
 caufe it left him at liberty to introduce into his academy 
 any fyllem of religious or irreligious opinions that he 
 pleafed ; a liberty of which he refolved to avail himfelf, 
 and, though now a doctor in theology, to outlbip, in 
 licentioufnefs, even the founder of the philanthropine, 
 . who was not in orders. By meditating on the work- 
 ings of his own mind, he had by this time formed his 
 theory of human nature, which was indeed very fimple. 
 <' The leading propenfities of the human mind (he fays) 
 are three ; inftinftive liberty, inftinftive activity, and 
 inftinftlve love." By thefe expreffions we fuppofe he 
 means, " innate love of liberty, inftinft prompting to 
 aftion, and the fexual appetite :" and he immediately 
 adds, that " if a man is obftruAed in the gratification 
 of any of thefe propenfities, he fuffers an injury. The 
 bufinefs therefore of a good education is to teach us 
 how they are to be gratified in the highell degree." 
 
 That fuch an education would be approved of by the 
 uncorrupted natives of Switzerland was hardly to be 
 expefted ; and Bahrdt foon found his fituation at 
 Marfchlins as uncomfortable as it had been at Giefien. 
 "The Grifons (he fays) were a ftrong inftance of the 
 immenfe importance of education. They knew nothing 
 but their handicrafts ; and their minds were as coarfe 
 as their perfons." He quarrelled with them all, and 
 was obliged to abfcond after lying fome time in prifon. 
 
 From Marfchhns he went to Durkheim, a town in 
 the Palatinate, where his father had been miniiter, and 
 where his literary talents were well known. After fome 
 h'ttle time he got an affnciation formed for eretting and 
 fupporting a Philanthrop'ine or houfe of education. A 
 large fund was coUefted ; and he was enabled to travel 
 into Holland and England to engage pupils, and was 
 furnilhed with proper recommendations. 
 
 In London he gained the friendihip of a clergyman, 
 whom he reprtfents as a perfon in the highefl degree 
 accomplifhed. " With found judgment (fays Bahrdt), 
 great geni\is, and correft tafte, he was perfectly a n.-an 
 of the world. He was my friend, and the only perfon 
 who warmly intereiled himfelf for my inftitution. To 
 his earneft and repeated recommendations I owe all the 
 pupils that I got in England, and many mofl refpeft- 
 able connexions ; for he was univerfally cfteemed as a 
 man of learning and of the moil unblemifhed charafter. 
 He was my friend, my conduilor, and I may fay my 
 preferver ; for when I had not bread for two days, he 
 took me to his houfe, and fupplied all my wants." 
 
 For fo much kindnefs the render doubtlefs fuppofes 
 that the heart of Balirdt overflowed with gratitude ; 
 but if fuch be his opinion, he is a flranger to the priu- 
 
 ] BAH 
 
 ciples of ihofe who have on the continent of Europe Bahrdt. 
 adociated fur the purpofe of enliglitening the worh; 
 This amiable man, whofe charaiSter is here fo jullly 
 drawn, was afterwards depicted by the monfter whom 
 he iuid faved from perifliing by himger, as a wretch loll 
 to all feiife of (liame and decency, as an apoftate from 
 the Chriftian faith, and as a notorious frequenter of the 
 London brothels ! Fortunately he was able to vindicate 
 his charafter completely from this flanderous abufe, and 
 to convift Bahrdt of having publiftied what covld not 
 pnjjtbly le true. 
 
 Tliis ungrateful liar returned from England, and car- 
 ried into execution his plan of the Philanthropine. The 
 caftle of Count Leining Hartzburgh at Heidefheitn, 
 having gardens, park, and every handfome accommoda- 
 tion, had been fitted up for it ; and in 1778 it was 
 confecrated by a folemn religious feftival. But his old 
 misfortunes purfued him. He had indeed no colleagues 
 with whom he could quarrel ; but his a-vowed publica- 
 tions became every day more obnoxious ; and when any 
 of his anonymous pieces had a great run, he could not fo 
 far ftifle his vanity as to conceal that he was the au- 
 thor. Of thefe pieces fome were (hocking to decency, 
 and others fo horribly injurious to the charaflers of the 
 mod refpeftable men in the ftate, that he was conti- 
 nually under the correftion of the courts of juftice. It 
 was hardly pofBble for a man of letters to be in his 
 company, and not fuffer by it ; for it was his conftant 
 praftice to attribute every ilep which he took towards 
 atheifm, to the force of the arguments urged by fome 
 of his friends. 
 
 To be his friend, or to obtain his applaufe, was in- 
 deed fo great 3 misfortune, that when the reader fee* 
 any perfon celebrated by Dr Bahrdt, in the beginning 
 of a book, for found fenfe, profound judgment, accurate 
 reafoning, or praifed for acts of friendfliip to himfelf, 
 he may be affured, that before the dole of the book 
 this man (hall be reprefented as having in private con- 
 verfation convinced the author, that lomc doftrine, die- 
 rilhed and venerated by all Chriftians, is a piece of kna- 
 vifh fuperftition. 
 
 Dr Bahrdt had married, while at Gieflen, a woman 
 with a fmall fortune : but fuch a ftranger was he to the/ 
 delicacies of wedded love, fo loft indeed to all fente of 
 decency, that he contrived one day to entice his wife 
 naied into the bath in the garden of his Philanthropine, 
 where, in the water, he, being alio naked, toyed with. 
 her in the fight of all his pupils. It was his boail that 
 he held his opinions independent of all mankind, and 
 was indifferent whether they procured him praile or re- 
 proach ; but it appears from this taft, that he was 
 equally regardlefs of the praife or cenfure which might 
 be attached to his ailions ; for furely the groiTell hog 
 that ever before him battened in the Epicurean fty 
 would not have prefented fuch an exhibition to boys. 
 
 The confequence of all this was, that he was obliged 
 to fly from Heideftieim, leaving his fureties in the Phi. 
 lanthropine to pay about 14,000 dahlers, befidcs debts 
 without number to his friends. He was impiifoned at 
 Dienheim ; but being foon releafed, he fettled at Halle, 
 where he funk to be the keeper of a tavern and billiard- 
 table. His houfe became of courfe the refort and the 
 bane of the ftudents in the univerfity, and he was obli- 
 ged to leave the city. He had fomehow got money 
 fufficient to purchafe a littk vuieyard, pleafantly fitua- 
 
 ted
 
 BAH 
 
 [ 6 
 
 BahrJt. ted in the neighbourhood. This he fitted up with 
 """v every accommodation that could invite the ftudents, 
 and called it Bahnlt's Rube (Bahrdt's repofe) ; where 
 he lived for two years, directing the operations of a fe- 
 cret fociety called the German Union, for rooting 
 OUT Superstition and Prejudices, and for advan- 
 cing TRUE Christianity. 
 
 With Bahrdt's qualifications for advancing the intc- 
 refts of genuine Chrillianity, the Chriftian reader is al- 
 ready iufficiently accquainted ; but he will not wonder 
 at his appointment to this high office, when he is in- 
 formed that the German Union i; notliing more thar> 
 a fpawn of the fecrct fociety of ////.'mina/i (fee Illu- 
 MiNATi in this Supplement) ; and tliat its objeft is to 
 abolilli the religion of the gofpel, and to teach in its 
 ftead the fatalifm of the Stoics. With this view Chri- 
 ftiaiu'ty is conlidered in the union as a myftical fociety, 
 and its Divine Founder as the grand mailer of a lodge I 
 The apoftles Peter, James, John, and Andrew, were the 
 ELECT, brethren of the /Air^/ degree, and initiated into 
 all the myfleries. The remaining apoftles were only of 
 thefecond degri;e ; and the feventy-two, of ihejirjl : a 
 degree into which ordinary Chriftians may be admitted, 
 and prepared for farther advancement. The great my- 
 
 ftery is, that J C was a naturalist, and 
 
 taught the dotlrine of a fupreme mind, the fpcftator 
 but not the governor of the world. 
 
 To propagate thefe impious and abfurd notions, 
 Bahrdt publilhed many books of the moit antichriltian 
 tendency, and fome of them calculated to make their 
 readers fhake off all moral obligation. But the labours 
 ot the fociety were not confined to religion : it incul- 
 cated on Its members the moft dangerous maxims of ci- 
 vil conduft : for, as we learn from Bahrdt lilmfelf, the 
 objefts at which the Union aimed were — Advancement 
 ofjcience — a general Interejl and concern for arts and learn- 
 'ng— excitement of tidents — check of fcribhling—good edu- 
 cation LIBERTY EQJJALITY — hofp'llaliiy DELIVERY 
 
 OF MANY FROM MISFORTUNES — Union, of the learned — 
 and at lajl — perhaps — Amen. 
 
 What the meaning of this enigmatical conclufion is 
 we can only guefs ; and we agree with the real philofo- 
 pher from whom we have taken this account, tlint our 
 conjeftures cannot be favourable. Bnhrdt was a villain, 
 and could be aiTociated only with villains, whofe affairs 
 he managed with the help of an old man, who lived at 
 bed and board in his houfe for about fix fliillings a-week, 
 and difcharged the office of fecretary to tlie Union. 
 
 When he had toiled in this caufe near two years, 
 fome of the fecrets of the Union tranfpired ; his former 
 conduft and his conflant imprudence made him fufpeft- 
 ed r Ills afibciated friends lodged informations as^ainfl 
 him ; his papers were feized ; and he himfelf was fcnt 
 to prifon, firft at Halle and then at Magdcburgh. After 
 fomething more than a year's confinement, he was fet 
 at liberty, and returned to his Ruhe, not, alas ! to live 
 at eafe, or to exhibit fymptoms of repentance, but to 
 lie down on a fick-bed, where, after many months fuf- 
 fering of increafing pain, he died on the 23d of April 
 1793, the moft wretched and loathlome viftim of un- 
 bridled fenfuality. 
 
 Such were the fruits of the German Union, and of 
 that Illumination which was to refine the heart of man, 
 and bring to maturity the feeds of native virtue, which 
 are choaked in the heart by fuperftitJou and defpotifm. 
 
 I ] BAH 
 
 Dr Bahrdt affcfted to be the enlightener and reformer BatirJt. 
 of the world ; and affirmed that all the evils of life ori- — — %— 
 ginated from dclpotiiin and fuperllition. " In vain 
 (fays he) do we complain of the iuifficacy of religion. 
 All pofitive religion is founded on iiijultice. No prince 
 has a right to prtfcribe or fani\ion any fucii fyilem ; 
 nor would he do it, were not the prleiis the firmcll pil- 
 lars of his tyranny, and fuperftitiou the (Irongclt fetters 
 for his fubjefls. lie dares not (liow Rellstion as ftie is, 
 pure and undcfiled — (lie would charm the eyes and the 
 hearts of mankind, wolild immediately produce true mo- 
 rality, would open the eyes of frceborn man, would 
 teach him what are his rights and who are his oppref- 
 fors, and princes would vanilh h'om the face of the earth." 
 
 Therefore, without troubling ourfclves with the truth 
 or falfehood of his religion of nature, and alfuming it as 
 an Indifputable point, that Dr Bahrdt has feen it in this 
 natural and fo effeetlve purity, it is furely a very perti- 
 nent qutftion, "Whether has the fight produced on his 
 mind an effedl fo far fuperior to the acknowledged faint- 
 nefs of the impreffion of Chriftlanlty on the bulk of 
 mankind, that it will be prudent to adopt the plan of 
 the German Union, and at once put an end to the di- 
 vlfions which fo unfortunately alienate the nu'nds of pro- 
 feffing Chrillians from each other:" The account here 
 given of Dr Bahrdt's life feems to decide the queftlon. 
 
 But it will be faid that we have only related fo ma- 
 ny inftances of the quarrels of priefts and their flavifh 
 adherents with Dr Bahrdt. Let us view him in his 
 ordinary conduft, not as the champion and martyr of 
 illumination, but as an ordinary citizen, a hufband, a fa- 
 ther, a friend, a teacher of youth, a clergyman. 
 
 Wlien Dr Bahrdt was A parlih-minlfter, and prefident 
 of fome ini'^erior ecclefiallical dlftrlft, he was empowered 
 to take off the cenfures of the church from a young wo- 
 man who had born a hallaid child. By violence he 
 again reduced her to the fame condition, and efcaped 
 eenfu; ■■; by the poor girl's dying of a fever before her 
 pregnancy was far advanced, or even legally document- 
 ed. On the night of the fulemn farce of confecrating 
 his Phllanthroplne, he debauched the mald-fervant, who 
 bore twins, and gave him up for the father. The 
 thing was not judicially proved, but was afterwards 
 made fufficiently evident by letters found among his 
 papers, and publiflied by one of his friends in the U N ion. 
 Having fupported thefe infants, in a pltii'^ul manner, for 
 little more than a year, he caufed them to be taken 
 away from their mother, during night, fome time in 
 the month of February 1780 ; and they were found 
 expofed, the one at Ufstein, and the other at Worms, 
 many miles dillant from each other, and almoft frozen 
 to death. 
 
 So much for the purity of his morals and his reh'- 
 glon, as he appears in the charafter of a father and 
 of a clergyman. His decency as a hulband, and his 
 gratitude to his friend, we have already fceii ; and 
 we ffiall now fee his kindneis and fidelity. After 
 wafting the greateft part of his wife's little fortune, 
 he was fo provoked becaufe her brother would not 
 give him up the remainder, amounting to about .L. no, 
 that he ever afterwards treated her with the greateft 
 cruelty, and exhibited her to contempt and ridicule in 
 two infamous novels. At Halle he brought a millrefs 
 into the houfe, and committed to her the care of his fa- 
 mily, confining his wife and daughter to their own, 
 
 apartment 5 ,
 
 B A I 
 
 [ 62 ] 
 
 B A I 
 
 Bi'-rlt, apartment j and the laft thing which he did was to 
 ''''"?• fend for a bookfelK-r, who had i)vibh"lhcd fome of his 
 ' ' vilell pieces, and, without a tliought of his injured wife, 
 recommend hi.i (Irumpet and her children to his protec- 
 tion. 
 
 "Think not, iiidijrnant reader (fays Arbuthnot), 
 that tl\is man's life is ufelefs to mortals." It (liovvs in 
 a ftri)ncr liglit tlio falfity of all his declamations in favour 
 of his fo much praifed natural religion and univerfiil 
 kindncfs and humanity. No man of the pirtv writes 
 with more perfuafive energy, and, though his petulance 
 and precipitant fclf-conceit lead him frequently allray, 
 no man has occafionally put all the arguments of thcie 
 j.hilofophers in a clearer light ; yet we fee that all is 
 falfe and hollow. He is a vile hypocrite, and the real 
 aim of all his writings is to make money, by foftering 
 the fcnfual propenfitics of human nature, although he 
 fees atid feels that the completion of the plan of the 
 German Union would be an event more deftrudive and 
 hmentable than any that can be pointed out in the an- 
 nals of fuperftition. We will not fay that all the parti- 
 fans of illumination arf hogs of the lly of Epicurus like 
 this wretch ; and it would be extremely unjull to con- 
 fider his vices as the cfFe£ls of his illumination. He 
 was fenfual, ungrateful, and profane, before he was ad- 
 rritted into the order of the Illuminati ; but had the 
 views of tliat order been fuch as were held out to the 
 v.-nrld at large, its fagaclous founder would not have ini- 
 tiated a wretch fo notorioufly profligate as Dr Bahrdt. 
 Their views, however, being to govern mankind thro' 
 the medium of their fenfual appetites, and to reign in 
 liell, rather than ferve in heaven, they could not have 
 employed a better inftrument. Dr Bahrdt was a true 
 difciple of illumination ; and though his torch was made 
 of the coarfeft materials, and ferved only to difcover 
 fights of woe, the horrid glare darted into eveiy corner, 
 roufmg hundreds of filthy vermin, and direftlng their 
 flight to the rotten carrion, where they could beft de- 
 pofite their poifon and their eggs. Whilft the more de- 
 cent members of the Union laboured to pervert the re- 
 fined part of mankind by declamations on the rights of 
 man and the bleflings of liberty, Bahrdt addrefled him- 
 felf to readers of all defcriptlons, and affallcd at once the 
 imagination and the appetites. He taught them, that - 
 religion is an impoflure ; that m.orallty is convenience ; 
 and, with blafphemy peculiar to himfelf, that be and 
 iiis order, by their licentious doSrines, were to complete 
 
 ike plan and aim of ^ C 
 
 BAILLY (Jean-Sylvian), who made fuch a figure 
 during the firft years of the French revolution, was born 
 at Paris on the 15th of September 1736, of a family 
 which had been diftlngulfhed painters during four fuc- 
 reffive generations. He was bred to the fame profef- 
 fion, but (bowed an early tafte for poetry and the belles 
 lettres. Chancing, however, to become acquainted with 
 the geometer La Caille, this circumfiance decided his 
 genius, and he thenceforth devoted himfelf to the culti- 
 vation of fcience. He calculated the orbit of the co- 
 met of 1759 ; and on the 29th of January 1763 was 
 received into the Academy of Sciences. In that year 
 he publiflied an ufeful and laborious compilation, being 
 the reduction of the obfervations made by La Caille in 
 1760 and 1761, on the zodiacal flars. He likewife be. 
 gan to confider the theory of Jupiter's fatellitcs, and, in 
 the competition for this prize queftion of 1764, had a 
 
 formidable rival in La Grange, who already promifed to B^ 
 become the iirft mathematician in Europe. The re- '*" 
 fults of his invert igat Ions were collected into a treatife 
 published in 1 766, containing alfo the hiltory of that 
 part of aflronomy. In 177 1 he gave a moll curious 
 and important memoir on the light of the fatellitcs, and 
 introduced a degree of accuracy till then unknown in 
 the obfervations of their ecllpfes. 
 
 His fludies were not confined to the abftraft fciences; 
 for he cultivated letters with fuccefs. His eloges of 
 Charles V. of Cornellle, of Leibnitz, of Mollere, and 
 afterward thofe of Cook, La Caille, and Greffet, were 
 much admired. His eloquence pointed him out as a 
 proper perfon to fill the charge, vacant in 1771, of fe- 
 cretary to the Academy of Sciences ; and, under the 
 patronage of Buffon, lie fl:ood candidate for that en- 
 viable place. He failed : but it was the high birth and 
 promiling talents of the young Condorcet, joined to the 
 adlive influence of D'Alembert, that carried the prize. 
 
 In 1775 appeared the firfl; volume of the Hillory of 
 Adronomy, which indeed ftrews the path of fcience 
 with flowers, and in every refpeft is a moil valuable 
 work — full of animated defcription, of luminous narra- 
 tive, and intcrtiling detail. His very peculiar ideas 
 concerning the early ftate of Upper Afia gave rile to 
 an ingenious correfpondence and dlfcuirion with the ve- 
 teran philofopher Voltaire, the fubllance of which foon 
 appeared in two volumes, intitled, " Letters on the Ori- 
 gin of Sciences," and " Letters on the Atlantide of 
 Plato." If imagination flione forth in thefe eflays, eru- 
 dition was no lefs confpicuous in a great work compo- 
 fed in the years I78r and 1782, on the fables and reli- 
 gious creeds of antiquity ; which Hill ex His in manu- 
 fcript, and the publication of which would aflTuredly ex- 
 tend the fame of its author, and gratify the learned 
 world. His opinions on fome points happening to co- 
 incide with the theories of Buffon, he contrafted with 
 that celebrated naturaliil a clofe friendrtilp, which was 
 diffolved by Biilly's uncourtly oppofition to the eleftion 
 of the Abbe Maury into the Acatlemie Frangaife. Of 
 that academy he had been chofen fecretary in j 784 ; 
 and he was admitted, in the following year, into the 
 Academy of Infcriptlons and Belles Lettres ; the only 
 inftance, fince Fontenelle, of the fame perfon being at 
 once a member of all the three academies. In the mean- 
 time, the other volumes of the Hlftory of Allronomy 
 lucceflively appeared, and that capital work was com- 
 pleted in 17*^7 by the Hiilory of the Indian and Orien- 
 tal Allronomy ; a prodiicllon of Angular acutenefs, re- 
 fearch, and nice calculation. 
 
 In 1784 he made an elegant report to the Academy 
 of Sciences on the animal magnetlfm of Mefmer ; and 
 in 1786 another report, which difplays the judgment 
 and humanity of its author, on a projeCl for a new 
 hokl-ilieu or Infirmary. 
 
 We now approach the eventful period which fum- 
 moned Bailly from his retirement, to enter on a politi- 
 cal career, that was full of difficulty and danger, and 
 for which his habits and lludies appear not to have fitted 
 him. He had fccn, as others faw, the defefts of the old 
 goveriunent (if France. His heart panted for civil and 
 ecclcfiaft'cal liberty ; but unfortunately, like many other 
 philofaphers b'j'h in his own country and in this, he 
 had formed notions of that bleffing which experience 
 fliould have taught him can never be realifed among be- 
 
 .liy.
 
 B A I 
 
 Bailly, I'ligs fo impei'fcft as the bulk of mankind. When the 
 "■"v ll.itcs-genenil were funimoned to meet, he was on the 
 
 2.'>th of April 1789 nominated fecretary by the elec- 
 tors of Paris, and then appointed one of the deputies. 
 He was chofeii prelldcnt of the Tiers Etat ; and when 
 that chamber was conftituted the National Aflembly, 
 he continued in the chair, and concurred in all the le- 
 velling decrees which laid the foundation of the prefent 
 mifery of his country, as well of mofl other countries i,f 
 Europe. 
 
 After the taking of the Baftile, when the king was 
 removed to Paris on the 15th of July, Bailly was called 
 by public acclamation to the head of that city, with 
 the title of Miiyor. In his feveral fundlions he afted 
 with integrity, courage, and moderation. He reached 
 the fummit of glory : — but how mutable, alas ! is hu- 
 man grandeur ! That middle courfe of conduft, the 
 aurea mediocrhas, at which virtue aims, is fitted to pleafe 
 neither of the contending parties in the midil of revolu- 
 tions ; and fucli proved the ruin of Bailly. His po- 
 pularity began to decline, and was at length changed 
 into inveterate enmity by an unfortunate accident. On 
 the 17th of July 1791, the populace having coUefted 
 tum.ultuoufly to demand the abolition of monarchy, 
 Bailly was ordered by the National AflTcmbly to dif- 
 perfe the mob. He was obliged to proceed to the 
 Champ-de-Mars at the rifle of his life ; and, in fpite of 
 all his exertions and forbearance, fome fliots were fired 
 by the foldiery. It was no longer defir&ble to hold his 
 perilous charge, and on the i6th of November follow- 
 ing he give way to the afcending reputation of Petion. 
 The impaired ftate of his health, too, rendered it expe- 
 dient to retire from the focus of turbulence. He fpent 
 the year 1792 and part of 1793 in travelling through 
 different provinces of. France. During this period he 
 wrote memoirs of the events which he had witneffed, 
 and in which he had often been a principal aftor. Thefe 
 come down only to the 2d of Oiitober 17S9, but 
 would make a large quarto volume ; and La Lande, 
 from whofe Eloge de Bailly this article is taken, gives 
 us hopes that the manufcript will be publifhed. He 
 was advifed by his friends to withdraw from France, 
 but he chofe rather, like Socrates, to fubmit to the in- 
 juftice and ingratitude of his country. At the nod of 
 a vulgar tyrant he was arrelled, fummarily condemned 
 by a fanguinary tribunal, and on the 15th of November 
 1795 was delivered over to appeafe the vengeance of an 
 incenfed and indifcriminate populace. His fufferings 
 were lludioufly protracted, but he bore them with the 
 calmnefs and magnanimity of a fage. Nature recoils 
 at the recital of inch barbarities. 
 
 In 1787 INI. Bailly married the widow of one who 
 had been during 25 years his intimate friend ; a wo- 
 man more qualified by her age and condition to infpire 
 refpeft than the paliion of love. He was tall in his 
 perfon, of a ferious deportment, and joined firmnefs to 
 fenfibility . Never did philofopher dillinguifli himfelf in 
 fo many different lines, nor acquire fuch deferved repu- 
 tation in them all. His difintereftednefs was pure and 
 unaffefted ; and during his magillracy he fpent a part of 
 his fortune in relieving the wants of the poor. Plis 
 virtue remained as untainted in his various public fla- 
 tions as in the fweet retirement of domeftic life. 
 
 Such is the encomium palTed upon this philofopher 
 and flatefman by no lefs a man than the celebrated af- 
 
 [ 63 ] 
 
 BAN 
 
 Baliul 
 
 II 
 Bar; I am. 
 
 tronomer'M. db la Lande ; but to thofc who are not 
 infefted with the mama of freedom, it will doubtlefs ap- 
 pear greatly exaggerated. That M. Bailly was a man 
 
 of eminence in the republic of letters, is known to all 
 the learned of Europe ; that in his political condudt he 
 meant to promote the good of his country, it wouhl 
 certainly be prefumptuous in us to deny ; and that he 
 fuffered unjnUly, is incontrovertible : But let it be re- 
 membered that he fuffered in a llorci, which he exerted 
 all his abilities to raife ; and that he ftt an example of 
 injuitice, when he concurred in the degradation of the 
 privileged orders, and in the violent coniifcation of the 
 property of the church. 
 
 BALIOL (John), the competitor with Bruce for 
 the crown of Scotland, was not (as he is faid to have 
 been in the Encyclopedia') the brother of King Alex- 
 ander, but the great grandfon of David Earl of Hun- 
 tington, third fon of King David I. 
 
 BALLISTIC Pendulum, an ingenious machine 
 iinvented by Benjamin Robins, for al'certaining the velo- 
 city of military projeftiles, and confequeutly the force 
 of fired gunpowder. It confills of a large block of 
 wood, annexed to the end of a ilrong iron Item, iiavijig 
 a crofs fteel axis at the other end, placed horizontally, 
 about which the whole vibrates together like the pen- 
 dulum of a clock. The machine being at reft, a piece ;/„//„„v 
 of ordnance is pointed ftraiglit towards the wooden Duiionarj^ 
 block or ball of this pendulum, and then difcharged : 
 the confequence is this — the ball difcharged from the 
 gun ftrikes and enters the block, and caufes the pendu- 
 lum to vibrate more or lefs according to the velocity of 
 the projeitile or the force of the blow ; and by obfer- 
 ving the extent of the vibration, the force of that blow 
 becomes known, or the greatelt velocity with which the 
 block is moved out of its place, and conftqucntly the 
 velocity of the projectile itfelf which ilruck the blow 
 and urged the penduluaa. 
 
 BANKA (fee Banca, Encyd.) is noted tlirougho!!t 
 Afia for its tin mines. It lies oppofite to the river P,i- 
 lambang, in the ifland of Sumatra, on which the fovc- 
 reign of Banka, poffelfor alfo of the territorj- of Palam- 
 bang, keeps his conllant refidence. This prince main- 
 tains his authority over his own fubjefts, and his inde- 
 pendence of the neighbouring fovereigns, chiclly by the 
 affillance of the Dutch, who liave a feltlement and troops 
 at Palambang, and enjoy the benefit of a contraft with 
 the king of Banka for the tin which his fubjefts procure 
 from that ifland. Such at leall was the cafe in 1793, 
 when Lord Macartney touched at Banka on his way to 
 China. At that period the fovereign compelled his fub- 
 jefts, and probably does fo at preient, to deliver the tin 
 to him at a low price, and iold it to the Dutch at a fmall 
 advance, purfuant to his contract. Thofe miners, from 
 long practice, have arrived at great perfection in redu- 
 cing the ore into metal, employing wood as fuel in their 
 furnaces, and not foflile coal, oxcoai, which is feldom io 
 free from fulphur as not to afiedl the malleahility of the 
 metal. It is lometimes preferred therefore to European 
 tin at the Canton market ; and the profit upon it to the 
 Dutch company was, at the period mentioned abo\c, 
 luppofed to have long been not lefs than L. 150,000-2- 
 year. Into whofe hands this trade has now fallen we 
 know not ; probably it is in a great degree negleilled. 
 
 BANTAM, the capital of a kingdom of the fame 
 name in the ifland of Java, is, in the Encyclopedia, faid
 
 BAR 
 
 [ 6+ ] 
 
 BAR 
 
 Bariib. 
 
 Bartam to be a large town with a good harbour anrl fortified 
 cattle Sir George Staunton, however, who vifited Ban- 
 tam fince that article was publiflud, gives a very ditle- 
 rent accoi'nt both of the town and of its harbour. Once 
 indeed it was a place of confiderable confequence, being 
 the great mart for pepper and other fpices, whence they 
 were diftribnted to the reft of the world The chief 
 faftory of the Engh'fii as well as Dutch Eaft India Com- 
 pany was fettled there. The merchants of Arabia and 
 Hindoftan rcforted to it. Its fovercigns were fo deii- 
 rous of encouraging trade, by giving ftcurity to foreign 
 merchants againll the violent and revengeful dilpofition 
 of the natives, that the crime of murder was never par- 
 doned when committed againft a Rranger, but might be 
 commuted by a foreigner for a fine to the relations of 
 the deceafed. This place flourilhed for a confiderable 
 time ; but the Dutch having conquered the ntiglibour- 
 ing province of Jacatra, where they fince have built Ba- 
 tavia, and transferied their principal bufinefs to it, and 
 the Englifh having removed to Hindoftan and China, 
 and trade in other rcfpefls having taken a new courfe, 
 Bantam was reduced to a poor remnant of its former 
 opulence and importance. Other circumilances have 
 accelerated its decline. The bay is fo choakcd up with 
 daily acc^ffions of new earth waflied down from the 
 mountains, as well as by coral (lioals extending a confi- 
 derable way to the eallward, that it is inacceflible at 
 prefent to velTels of burden ; even the party who went 
 there from the Lion, the fliip which carried Lord Ma- 
 cartney to China, was obliged to remove from her pin- 
 nace into a canoe, in order to reach the town. With 
 the trade of Bantam the power of its fovereign decli- 
 ned. In his wars with other princes of Java he called 
 in the affiftance of the Dutch ; and from that period 
 he became in faft their captive. He refides in a palace 
 built in the European ftyle, with a fort garrifoned by 
 a detachment from Batavia, of which the commander 
 takes his orders not from the king of Bantam., but from 
 a Dutch chief or governor, who lives in another fort 
 adjoining the town, and nearer. to the fea-fide. His 
 Bantamefe majefty is allowed, however, to maintain a 
 body of native troops, and has feveral fmall armed vef- 
 fels, by means of which he maintains authority over 
 fome parts of the fouth of Sumatra. His fubjefts are 
 obliged to fell to him all the pepper they raife in either 
 ifland, at a low price, which he is under contraft with 
 the Dutch to deliver to them at a fmall advance, and 
 much under the marketable value of that commodity. 
 The prefent king joins the fpiritual to the temporal 
 povi'er, and is high prieft of the religion of Mahomet ; 
 with which he mingles, indeed, fome of the rites and 
 fuperftitions of the aboriginal inhabitants of Java ; ado- 
 ring, for inftance, the great banyan, or Indian fig-tree, 
 which is likewife held facred in Hindoftan, and under 
 which religious rites might be conveniently performed ; 
 in like manner, as all affairs of ftate are actually tranf- 
 afted by the Bantamefe under fome fliadowiiig tree by 
 moon-light. To complete the ruin of Bantam, a fire 
 fome time ago deihoyed moft of the houfes, and few 
 have been fince rebuilt. 
 
 BANYAN-TREE. See Ficus, .E«o''/. 
 
 British BARILLA, is the name given by Mr 
 James King of Neweaftle upon Tyne, to a material in- 
 vented by him to fupply the place of Spanilh barilla in 
 the making of crown window-glafs, broad window-glafs, 
 
 and glafs-boltles, as alfo in the manufafturing of foap 
 and alum. For thefe purpofes he affirmed that it an-'^ 
 fwercd much better than any other material then in 
 ufe J and in confequence of that affirmation he obtain- 
 ed a patent for his inv>;ntion, dated March 4. 178". 
 
 Tliough we can hardly allow to this invention all the 
 merit claimed for it by its fond author, yet as it niuy be 
 of ufe to different manufadturers, we (hall lay before 
 our readers his method of making the Britilh barilla. 
 It is as follows : " Take a certain quantity of aAies ob- 
 taiiud by burning the loppings or branches of afti, oak, 
 beech, elm, alder, or. any other kind of green wood or 
 bramble : Take an equal quantity ol the allies obtained 
 by burning the green vegetables known by the name of 
 fern, brecon, bean and pea-ftraw, whins, common field 
 and high-way thiftlcs, the ftalks of rape or muftard- 
 feed, or the bent or ruftics that grow by the fea-fliore." 
 Though we know not in wlial qualities tlie afties ob- 
 tained from the former fubftances differ from thofe ob- 
 tained from the latter, the author, as if the difference 
 was very great, directs thefe equal quantities to be mix- 
 ed together, fifted through a fine ficve, and laid upon a 
 boarded floor, where a quantity of foapers wafte-afties, 
 equal to the whole compound mafs, is to be added to it, 
 and well mixed with it by means of a ftiovel or other 
 inftrument. To this mixture of vegetable alhes and 
 foapers wafte-afhes is to be added a quantity of fine 
 quick-lime, in the proportion ot one hundred weight to 
 twelve hundred of the blended aPiies, and the lime and 
 aflies are to be well mixed together. After this the 
 whole is to be put into an iron pan, into which is to be 
 poured a quantity of feawater fufficicnt, fays the au- 
 thor, to diffolve the affies and lime ; and the whole is 
 to he ftirred with an iron rake till it incorporate. This 
 being done, a coal fire is to be lighted up under the pan, 
 and kept burning for two days and two nights without 
 intermilTion, additional quantities of fea-water being 
 conftantly fupplied to impregnate the materials with fa- 
 line inatter fufficient for calcination in a reverberating 
 furnace or caicar. In this calcar the ialine mafs, which 
 was bciled in the pan, is by intenfe heat to be diffolved, 
 and kept in a ftate of fufion for the fpace of an hour ; 
 during which time the volatile part flies off, and leaves 
 remaining a fixed alkaline fait, which, cooled in iron 
 pans, is the Britifn barilla, and has the appearance of 
 Spanifli barilla. See Barilla, Encycl. 
 
 BARTHELEMI (Jean Jacques), the Neftor of 
 French literature, was a man fo eminent for his know- 
 ledge of antiquities, that every claffical reader mull be 
 iiiterefted in his fate. He was born, we believe, at Pa- 
 ris about the latter end of the year 171c ; and being 
 educated for the fervice of the church, he became prior 
 of Courcay, keeper of the medab and antiques in the 
 French king's cabinet, and in 1 747 was eletted a mem- 
 ber of the Academy of Infcriptions. From that period 
 his life was wholly devoted to letters ; and in recording 
 the principal events of it, we can only enumerate, in 
 their order, his various publications. 
 
 A differtation of bis on the river Paftolus was read 
 1748 [Hift. del' Acad. X. 29.) ; Refleaions on a Me- 
 dal of Xerxes, King of Arfamata (Mem. de I' Acad. 
 XXXVII. 171.), found, or faid to be found, by Four- 
 moiit in the temple of Apollo Anyclcus (^XXXIX. 
 129.); Effay on Numifmatic Palaeography, ib. 223; 
 Differtation on two Samaritan Medals of Antigonus 
 
 Kinsr 
 
 Barilla, 
 irihelenii.
 
 BAR 
 
 r 65 ] 
 
 BAR 
 
 King of Judca, ii. 257 ; Remarks on Come Iiifci-iptions 
 publifhed by dilTcrcnt authors, XLV. 99 ; DiiTertation 
 on Arabic Coins, ili. 143 ; by which it appears that the 
 Mohammedan princes copied the heads of Greek and 
 Roman ones on their coins, and gave Arabic infcrip- 
 tions of their own names on the reverfe. On the An- 
 cient Alphabet and Language of palmyra, ;i. 179 ; on 
 the Ancient Monuments of Rome, the refult of a tour 
 in Italy to coUciit medals for the royal cabinet, to which 
 he added 300, XLIX. 151 ; on fome Phoenician Mo- 
 numents, and the Alphabets formed from them, LIII. 
 23. The charafters on the written mountains, which 
 he here cites, have been proved of no value ; and he il- 
 luftrates tlie conformity between the Phoenician and 
 the Egyptian charaders from the latter on the banda- 
 ges of the mummies. Iixplar;ation oi the Molaic Pave- 
 ment of the Temple of Prsentue, ii. 149; of which there 
 have been four engravings fmce its firll dilcovery in 1 650, 
 and which Barthelenii refers to the voyage of Adrian 
 into Egypt. It may be of that date, but there is no 
 reafoii to fuppofe that it reprefcnts any thing more tlian 
 an Egyptian landfcape. 'I'he form of letters determines 
 the date in the judgment of the learned Abbe. On 
 the Relations of the Egyptian, Phosnician, and Greek 
 Languages, LVIl. 38 ^ ; on fome Medals publilhed by 
 different authors, LIX. 270; Explanation of an In- 
 fcription under a Bas-relief in the Bilhop of Carpen- 
 tras's Library, 1 767, ii. 365 ; on the Number of Pieces 
 reprcfentcd in one Day on the Theatre at Athens, 
 LXXIL 286 ; three Comedies, as many Tragedies, a 
 Satire, and a Petite Piece; Remarks on fome medals of 
 the Emperor Antoninus ftruck in Egypt, LXXX. 4S4. 
 
 '775.(a). 
 
 His iaterpretation of the Phoenician infcription at 
 Malta, LIII. 23, was controverted by our learned lin- 
 guift, Mr Swinton, in Philaf. Traniacl. LIV. art. xxii. 
 p. 119; in farther remarks, ii. art. Ixx. P'^93. 
 
 In 1792 he publilhed a difl'ertation on an ancient 
 Greek infcription, containing an account of expences of 
 the public fealls under the archontate of Glaucippus, 
 410 years before Chrifl. 
 
 The intimate acquaintance which he had cultivated 
 with claffical antiquity, enabled him, in the clofe of a 
 long life, to compofe that cbcf-d'au-cre, the " Travels 
 of the Younger Anacharfis iiito Greece" in the mid- 
 dle of the lourth century before the vulgar, era. In re- 
 prefenting the curiofity of a Scythian favage (for we 
 cannot confider iji any other light the man who put 
 rriufic and the exceffes of the table on the fame level), 
 he takes occafion to interweave very curious and inllruc- 
 tive details on the laws, religion, manners, cuftoms, and 
 general fpirit, ot a gi-eat nation, as well as its progrefs 
 in arts and Iciences. The epoch which he has chofen 
 is that of letters and arts, combining the age of Pericles 
 with tliat of Alexander, the revolution which changed 
 the appearance of Greece, and foon after overturned the 
 empire of Perfia. The introduftion comprehends the 
 1250 years elapfed from the age of Cecrops to the fup- 
 pofed era of Anacharfis, in two intervals; the iirft reach- 
 ing to the commencement of the Olympiads, the fecond 
 to the capture of Athens by the Lacedemonians. The 
 
 SuppL. Vol. I. Part I. 
 
 hi (lory of the .\ihcnians commences about ijo years Bartlie. 
 after the firft Olympiad, including the age of Solon, or ''^''''• 
 that of legiflatioH ; that of Themiftocles and Ariilides, ' 
 
 or that of glory, of luxury, and arts. Jn the fecond, 
 fpcaking of war, his oblervation, that " the example of 
 one nation, that prefers dcatli to (lavery, is tdo import- 
 ant and too inftrudlive to be pafled in filence," fliould 
 have preferved him from the horrors of a long confine- 
 ment in an advs'.iced age, from which he was delivered 
 only to die. But arts, fcienccs, and literature, are alike 
 forgotten and overwhelmed in France. In the third 
 interval, fpeaking of the corruption of manners intro- 
 duced by Pericles to fupport his power, he has this ob- 
 fervation, applicable to every ftate : " Corrupted mo- 
 rals are not reftored but by the lofs of liberty, which 
 brings that poverty inconfiftent with foftnefs, and infe- 
 parahle from abftemioufnels, if not that rigid principle 
 of a healthy mind, which is properly called virtue.'" In 
 this period, though the arts were encouraged, philofo- 
 phy was neglefted. 
 
 In this diverfilicd undertaking, where the piif\ure of 
 ancient Greece, in its minuted parts, both of public and 
 private ufe, is brought before our eyes, the Abbe is fre- 
 quently more bi-illiant than folid, and occafionally lofes 
 the fubllance of a refleftion in purfuit of fomething in- 
 genious to add to it. The plans, views, .and maps, 
 are executed with great fpirit and accuracy by Mr Bar- 
 ber, a young man of very promifing talents ; and to the 
 charts many ufeful tables are added. The beauties of 
 the clafTics are diffufed in a vei"y pleafing manner, and 
 interfperfed with anecdotes little known. 
 
 Such was the man whom the French government 
 detained in prifon for months, and releafed on the fall 
 of Robefpierre. As he concurred in the revolution, we 
 know of no caufe for his imprilonment but the mildnefs 
 of his difpofition, and the jealoufy of that tyrant, which 
 purfued, with relentlefs cruelty, every man fufpefled of 
 being a friend to peace. Of the perfecution of Barthe- 
 lemi, in the extremity of old age, the convention itfelf 
 feemed to be afhamed ; for it unanimoufly voted him a 
 penfion < s fome recompence for his fufTerings. But, alas! 
 the recompence came too late : the old man lived but 
 a few months after his liberation, having died at Paris 
 on the 4th of May 1795 ; and the day after the fol- 
 lowing tribute was paid to his memory by Duflaulx, in 
 the national convention : 
 
 " Legiflators, your liberality conferred honour on the 
 latter days of the life of our refpeflable fellow citizen, 
 Barthclcmi. Our fuccedors, I have no doubt, will 
 confccrate his memory fo foon as the period fixed by 
 the law fliall permit them. May his old friend, how- 
 ever, be permitted, in a few words, to point out the rare 
 qualities of that Neftcr of French literature ? It might, 
 perhaps, be fufficient to tell you, as Xenophon faid with 
 fo much fimplicity of one of his mod illuftrious con- 
 temporaries, that Barthelemi was an excellent man in 
 all refpefts. In faCt, thofe who knew him were at a 
 lofs which to admire mod — his immortal Anacharfis, 
 or his own life. His policy confided in goodneis ; his 
 fcieiice was an immenfe treafure of every thing that 
 could purify the morals, perfeft the tade, render man 
 I more 
 
 (a) The references hereare to the duodecimo edition of the Memoirs of the Academy of Infcriptions-
 
 Bat. 
 
 BAT [6 
 
 Barthelemi more dear to man, and contribute to the fplendour of 
 his country. A ilnifle trait will convince you of the 
 _ mildnefs of his philanthropic mind : ' Why is it not 
 permitted (he often faid) to a mortal to bequeath prof- 
 perity to his fellow-creatures?' After having been over- 
 whelmed with the favours of fortune, whicli came un- 
 expeftedly and unfought, he became poor ; yet his cha- 
 rafter, far from ilnkiiig under the prefTure, actpiired 
 new rcfpeft; and he proved that poverty, fiipported with 
 dignity, is not lefs honourable than wealth accompanied 
 with benevolence. Perl'ecuted, as all virtuous and en- 
 lightened citizens were, he carried with him to the dun- 
 geon of that tyranny which you have fo glorioufly de- 
 liroyed, the conftancy and ferenity of Socrates. It was 
 there that the venerable old man offered to his compa- 
 nions in misfortune the magnificent fpeftacle of a good 
 man (Irugcrliug with adverfity. I have faid that he was 
 rich ; but let us not forget that he was not rich at the 
 expence of the unfortunate, and that he adopted all the 
 branches of his numerous family. The republic has 
 gained by that family good citizens, who ferve her ia 
 the moil ufeful and brilliant manner. Barthelemi felt 
 that the period of his dilfolution was approaching; yet 
 though exhaulled by long fatigue, and bending beneath 
 the weight of 80 years, his fenfihillty was dill vigorous, 
 and your juft decrees made the clofing fcene of his hfe 
 happy. When he heard that you were endeavouring to 
 repair the ills under which fo many thoufand innocent 
 men laboured, he lifted up his hands to heaven, and 
 exclaimed, ' Glory to God — honour to the national 
 convention — I have lived long enough!' In the pre- 
 fent pofture of affairs, the country demands all your at- 
 tention. I fhall therefore confine myfelf to requeft 
 the favour due to the manes of the illuftrious Barthcle- 
 mi. One of his nephews, I do not mean your refpec- 
 table ambaffador at Bafle, but the citizen Courcey, has, 
 for 25 years, difcharged all the duties of a fon to his 
 uncle, and for a long time has performed the funftions 
 of keeper of the medals and antiquities of the national 
 cabinet. I move, that the citizen Courcey be appoint- 
 ed to that office, which he has already proved himfclf 
 fo worthy to fill." 
 
 Whatever became of this motion, which was referred 
 to the committee of pubhc inftruftion, the cruelty of 
 the government purfued the family ; and the late banilh- 
 ment of his other nephew by the directory, of which he 
 was a member, furpatfes, if pofTible, the injuftice of 
 Robefpierre to the uncle. But their crimes were the 
 fame : both Barthelemis were men of mild difpofitions 
 and friends to peace. 
 
 BARYTES, one of the earths. See Chemistry 
 in this Supplement, Part I. Chap. iv. 
 
 BASTE R, the name given by the Dutch at the 
 Cape of Good Hope to the offspring of a white man 
 and Hottentot woman. 
 
 BAT, an animal which has been defcribed under its 
 generic name VESPtRxiLLio in the Encycl. but fince 
 that article was written, we have met with an account 
 of a new fpecies, fo very fingular, that, if the veracity 
 of our author can be depended on, it is well intitled 
 to a place here. This fpecies was difcovercd in the 
 country of the NImiquas, in the interior of Africa, by 
 M. Vaillant, during the courfe of his fecond travels, 
 and Is by him called the oreillar bat. To this title it 
 hai indeed a very good claim ; for it has, he fays, four 
 
 i) ] BAT 
 
 ears, or at leaft the external part of four ears, each B^tavfa. 
 
 tar being double ; the outer fold, which ferves as v~~" 
 
 a covering to the inner, is very ample, being two inches 
 eight lines high, and nearly as broad when ftretched 
 out. On the nofe alio a membrane Hands ercft, one 
 inch four lines in height, which might be taken for an- 
 other car, as it has exactly the fhape of one. This 
 membrane, as well as the ears and wings of the animal, 
 are of a rully red, paler below than above. The body 
 is only three inches long, and is covered with very fine 
 greyilh hair. Its width, from the tip of one wing to 
 that of the other, is eight inches. The reader will par- 
 don me, fays our author, for inferting thefe trifling de- 
 tails of meafurement, of which I am not more fond than 
 himlelf ; but they appeared to me neceffavy here, to 
 convey an accurate idea of the extraordinary length of 
 the ears of this animal, which are certainly larger in pro- 
 portion than thofe of any other we are acquainted with, 
 ilnce they are only four lines, or the third part of an 
 inch, fhorter than the body itfelf. 
 
 liATAVIA, the capital of the Dutch fcttlements 
 in the Ealt Indies, has been already defcribed under the 
 article Java in the Encyclopedia. The following ac- 
 count of it, however, as well as of the country around 
 it, and the manners and cuiloms of its various inhabi- 
 tants, as they prefented themfelves to Sir George Staun- 
 ton in March 1793, will probably prove acceptable to 
 many of our readers. 
 
 The city of Batavia, including the fuburbs, confifts 
 of near eight thoufand houfes, inhabited by Dutch, 
 Chinefe, and natives of Java. The houfes of the Chi- 
 nefe are low, and crammed with people. The Dutch 
 houfes are well built, clean, and fpacious, and their con- 
 flrutlion for the moil part well fuited to the climate. 
 The doors and windows are wide and lofty. The 
 ground floors are covered with flags of marble, which 
 being fprinklcd frequently with water, give a pleafant 
 coolnefs to the apartment ; but a confiderable propor- 
 tion of thofe was untenanted, which denoted a declining 
 fettlement. Among other circumflances which announ- 
 ced the fame, were thofe of the Company's vefTels lying 
 ufelels in the road, for want of cargoes to fill, or men 
 to navigate them; no fliips of war to proteft their com- 
 merce, even againfl pirates who attacked their veflel? 
 fometimes in the fight of Batavia road ; an invafion 
 threatened from the Ifle of France ; the place in no con- 
 dition of defence, particularly againll an enemy lefs af- 
 fected by the climate than Europeans ; fometimes as 
 many of the troops in hofpitals as fit for duty ; com- 
 milhoners expected from Holland to reform abufes. 
 Such a commiffion, implying a general fufpicion, could 
 not be welcome ; nor was it quite certain whether, in 
 fome minds, its arrival, or that of the enemy, was depre- 
 cated the moft cordially. 
 
 The fortifications of Batavia, though a place of fo 
 much importance, were not, when Sir George faw 
 them, fuch as would be deemed formidable in Europe ; 
 but when the difficulties were confidered of forcing 
 the pafFage of the river, or of landing troops on other 
 parts of the ifland, it might perhaps be thought of 
 greater ftrength than it would at the firft view have 
 credit for. The defences of the river were the water 
 fort, fituated at its entrance, having mounted or dif- 
 mounted fourteen guns and two howitzers. It con- 
 filled of a parapet, originally well conftrufted, retained 
 
 by
 
 BAT 
 
 [ 67 ] 
 
 BAT 
 
 Batavia. by a wall ; but the parapet was miicli negle£led, and 
 ■"v"— ' the wall nearly dcftroyed by the conftant working of 
 the fea. This fort was protected on the land fide by 
 a noxious fwamp, and towards the fea, on the north- 
 weft, by extenfive flats, over which even boats could 
 not pafs. The only good approach was that by the 
 channel, which it fees and defends. The next work 
 upon the river was on the weft (here, about a quarter 
 of a mile from the water fort. It is a battery mount, 
 ing feven guns, bearing down the river. Oppofite to 
 this was a battery of fix guns, facing tlie river, and two 
 to the eaftward. This formed one flank of a line that 
 occupied the low land to the north-eaft of the town. 
 The line was a low breaft-work of earth, that was 
 fcarcely difcoverable. The canals which interfeil the 
 town joined the great canal or river, at the diftance of 
 half a mile from the entrance. Below the junftion a 
 boom was laid of wood, armed with iron fpikes. A 
 little above was the caftle, a regular fquare fort, but 
 without ravelins or other outworks. It had two guns 
 mounted on each flank, and two, or fometimes three, on 
 each face : they were not en barbette, nor properly en 
 embrafure, but in a fituation between both, having both 
 their difadvantages without the advantage of cither. 
 The wall was of mafonry, about 24 feet high. It had 
 no ditch, but a canal furrounded it at fome diftance. It 
 had no cordon. The length of the exterior fide of the 
 work was about 700 feet. The town is rectangular, 
 three quarters of a mile long, and half a mile broad, 
 inclofed by a wall of about 20 feet in height. Small pro- 
 jeftions were conftrufted, of various forms, at intervals of 
 about 3yofeet. Thefegenerallymountedthree guns each. 
 It was alfo furrounded by a canal, having feveral lluices. 
 At ihort diftances from the town, three or four fmall 
 ftar forts of earth were ereftcd in particular pafles, per- 
 haps for defence againft the inhabitants of the ifland. 
 
 The eftablifhment of regular troops was i 200 Euro- 
 peans, of whom 300 were to be artillery, the reft infan- 
 try. But as it was found impoilible, on account of the 
 climate, to keep the number complete, recourfe was had 
 to the natives, of whom 500 were employed ; fo that 
 tlie eftabliftiment of European regulars was reduced to 
 700. There were alfo 300 volunteers of the town, who 
 were formed into two companies, but they were not 
 difciplined. Their regulars were very numerous, con- 
 fifting of enrolled natives of Java, who were never em- 
 bodied, and of Chinefe, of wliom the Dutch were fo jea- 
 lous as to arm them with lances only. Much depen- 
 dence was not to be placed on the exertions of eitiier 
 of thefe bodies in favour of the Dutch ; and as they 
 lofe many of their European troops every year, their 
 eftabliftiment appeared too fmall for any efl'cftual re- 
 Cftance. The chief proteftion of their ill-manned vef- 
 fels lying here, muft be from the fortified ifland of On. 
 ruft, well fituated to command tlie channel that affords 
 the principal paffage in\o the road. The work upon 
 that ifland was of a pentagonal form ; its baftions were 
 fmall and low, not more than 12 feet the higheft, and 
 not always connefted by curtains. A few batteries 
 were lately conftruAed on the outfide of this work, that 
 bore towards the fea. On thefe and on the baftions 
 about 40 guns were mounted in different diredtions. 
 South of thefe was another ifland, at the diftance of a 
 few hundred yards, on which two batteries, mounting 
 together 12 guns, had been lately erefted. 
 
 The caftle is built of coral rock, brought from fomc Batavia. 
 of the adjoining iflands, compofed of that material ; and '— V— 
 has the advantage of a fortilication of brick, in which 
 cannon ball is apt to bury itfelf without fpreading Iplin- 
 tcrs or Ihattering the wall. A part of the town wall is 
 built of lava, which is of a dark blue colour, of a very 
 hard denfe texture, emits a metallic found, and refem- 
 bles very much fome of the lava of Vefuvius. It is 
 brought from the mountains in the centre of Java, where 
 a crater is ftill fmoking. No ftone of any kind is to be 
 found for many miles behind tlie city of Batavia. Mar- 
 ble and granite are brought thither from China, in vcf- 
 fcls belonging to that country, commonly called junks, 
 which generally fail for Batavia from the ports (rf the 
 provinces of Canton and Fokien, on the fouthern and 
 foutheaft coalh of that empire, laden chiefly with tea, 
 porcelain, and filks. 
 
 The chief proteftion of Batavia againft the attacks 
 of a foreign enemy, arifes from the havoc which it is 
 well known the climate would make amongft Euro- 
 pean troops. This was acknowledged to Lord Ma- 
 cartney by fome of the Dutch officers themfelves, and 
 even by one of the counfellors of the Indies. Such in- 
 deed is the climate, that there have been very few ex- 
 amples of ftrangers remaining long in Batavia without 
 being attacked by fever, which is the general denonn'na- 
 tion in that place for illnefs of every kind. Europeans 
 foon after their arrival firft become languid and feeble, 
 and in a few weeks, or even in a few days, are taken fe- 
 rioufly ill. The diforder at firft is commonly a tertiaa 
 ague, which after two or three paroxyfms becomes a 
 double tertian, and then a continued remittent, that fre- 
 quently carries off the patient in a flrort time. Many 
 fall vidtims to the fecond or third fit; but in thefe cafes 
 a conftant delirium, and a great determination of the 
 blood to the brain, accompany the other fymptoms. In 
 fome it begins iu a quotidian form, with regular inter- 
 miffions for a day or two ; and then becomes a continued 
 remittent, attended with the fame fatal confequences as 
 the former. Of the Europeans of all clafles who come 
 to fettle at Batavia, it is fuppofed that not half the num. 
 ber always furvives the year. The place refcmblcs \a 
 that refpetl a field of battle or a town befieged. The 
 frequency of deaths renders familiar the mention ofthem, 
 and little figns are flievvn of emotion or furprife on hear, 
 ing that the companion of yetterday is to-day no more. 
 It is probable, female Eurojieans fuller lefs at Batavia 
 than the men. The former feldom cxpofe themfelves to 
 the heat of the fun, make frequent ufe of the cold liath, 
 and live more temperately than the other fex. 
 
 But it is not to thofe who have htely arrived from 
 Europe that this havoc is wholly confined. The great, 
 eft number of the Dutch fettlers, even thofe who had 
 refided long in the country, appeared wan, weak, and 
 languid, as if labouring with the " difeafe of death." 
 Their place of refidence, indeed, is fituated in the midft 
 of (wamps and ftagnated pools, from whence they are 
 every morning fainted with " a congregation of foul 
 and peftilcntial vapours," whenever the fea breeze fcts 
 in, and blows over this morals. The meridian iun raifes 
 from the fliallow and muddy canals, with which the 
 town is interfefted, deleterious miafmata into the air ; 
 and the trees, with which the quays and ftreets are 
 crowded, emit noxious exhalations in the night. 
 
 The general reputation of the unhcakhinefs of Bata- 
 I 2 via
 
 BAT 
 
 C 68 ] 
 
 BAT 
 
 Batavia. via is indeed fuch as to deter even Dutclimen, who can 
 » reiide at homt; with any comfort, from coming to it, 
 notwithftanding the temptation of fortunes to be quick- 
 ly amaffed in it. From this circuniftance it happens, 
 that offices and proftfTioriS are often neceffarily entrull- 
 ed to perfons little qualified to till them. One of the 
 clergymen, and the principal phyfician of the place, 
 were both faid to have originally been barbers. The Uni- 
 ted Provinces fnrnilh even few military recruits. The 
 reft are chiefly Germans, many of whom are faid to have 
 been kidnapped into the fervice. Though nonrrinally 
 permitted, after a certain length of time, to return 
 home, they are in faft compelled to enlill for a longer 
 time, the pay being too fcanty to allow them to lave 
 enouo-h to defray the expence of their palTage to Eu- 
 rope. The government is accufcd ot the barbarous po- 
 licy of intercepting all correfpondence between thofe 
 people and their mother country; by which means they 
 are deprived of the confo'.ation of hearing from their 
 friends, as well as of the chance of receiving fuch af- 
 flftance as might enable them to get home. 
 
 Difficult, however, as it is, on account of the cU- 
 mate, to recruit the army, fucli is the defire of accumu- 
 latiniT wealth in a foreign land, that it draws annually 
 trreat numbers of Chinefe as well as of Dutch to Bata- 
 via. Both indeed belong generally to the humbler claf- 
 fes of life, and are bred in fimilar habits of indullry in 
 their own country; but the diflerent circumftances that 
 attend them after their arrival in Batavia put an end to 
 any further refemblance between them. The Chinefe 
 have there no way of getting forward but by the conti- 
 nuance of their former exertions in a place where they 
 are more liberally rewarded, and by a ftriiSt economy 
 in the prefervation of their gains. Tliey have no chance 
 of advancing by favour, nor are public offices open to 
 their ambition ; but they apply to every induftrious oc- 
 cupation, and obtain whatever either care or labour can 
 accomplith. They become in town retailers, clerks, 
 and agents ; in the country they are farmers, and are 
 the principal cultivators of the fugarcane. They do 
 at length acquire fortunes, which they value by the 
 time and labour required to earn them. So gradual an 
 acquifition makes no change in their difpofition or 
 mode of life. Their induftry is not diminilhed, nor 
 their health impaired. The Dutch, on the contrary, 
 who are fent out by the Company to adminiller their 
 affairs in Afia, become foon fenlible that they have the 
 power, wealth, and pofleffions of the country at their 
 difpofaL They who furvive mount quickly into offices 
 that are lucrative, and not to them laborious. They 
 rife to the dignity of governor- general and coimfellors of 
 the Indies, as the members of the Batavian govern- 
 ment are called. Their influence likewife enables them 
 to fpeculate in trade with vail advantage. The drud- 
 gery and detail of bufinefs are readily undertaken by 
 the Chinefe ; w.hile their principals find it difficult, un- 
 der fuch new circumftances, to retain their former ha- 
 bits, or to reCIt a propenfity to indolence and voluptu- 
 oufnefs, though often attended with the facrifice of 
 health, if not of life. Convivial pleafurcs, among others, 
 are frequently carried to excefs. 
 
 In feveral ftoufes of note tlu'oiighout tlie fettlement, 
 the table is fpread in the morning at an early hour : 
 befide tea, coffee, and chocolate, fifli and flefli are ferved 
 for breakfaft ; which is no fooner over than Madeira, 
 
 claret, gin, Dutch fmall beer, and Engh'ffi porter, are 
 laid out in the portico before the door of the great hall, ■ 
 and pipes and tobacco prefeiitcd to every guell, and a 
 bright brafs jar jilaccd before him to receive the phlegm 
 which the tobacco frequently draws forth. Tliis oc- 
 cupation continues fometimcs with little interruption till- 
 near dinner time, which is about one o'clock in the af- 
 ternoon. It is not very uncommon for one man to drink 
 a bottle of wine in this mauner before dinner; and thofe 
 who have a prediledtion for the liquor of their own 
 country fwallow feveral bottles of Dutch fmall beer, 
 which they are told dilutes their blood, and affords 
 plenty of fluids for a free perfpiration. Immediately 
 before dinner, two men flaves go round with Madeira 
 wine, of which each of the company takes a burv^per a$ 
 a tonic or whettcr of the ajipetite. Then follow three 
 females, one with a filver jar containing water, fome- 
 times rofe-water, to walh ; a fecond with a filver bafon 
 and low cover of the fame metal, pierced with holes, to 
 receive the water after being ufed ; and the third with 
 towels for-wiping the hands. During dinner a band of 
 mufic plays at a little diltance : the muficians are all 
 flaves, and pains are taken to inftruCt them. A confi- 
 derable number of female flaves attend at table, which 
 is covered with a great variety of difhes ; but little is 
 received, except liquors, into ftomachs already cloyed. 
 Coffee immediately follows dinner. Tiie 24 hours are 
 here divided, as to the manner of living, into two days 
 and two nights ; for each perfon retires, foon after 
 drinking coffee, to a bed, which confifts of a mattrafs, 
 bolfter, pillow, and chintz counterpane, but no flieets ; 
 and puts on his night drefs, or muflin cap and loofe 
 long cotton gown. If a bachelor, wliich is the cafe of 
 much the greatcll number, a female flave attends to fan 
 him while he fleeps. About fix chey rife, drefs, drink 
 tea, take an airing in their carriages, and form parties to 
 fpend the evening together to a late hour. The morn- 
 ing meetings confift; generally cf men, the ladies feldont 
 choofing to appear till evening. 
 
 Few uf thefe are natives of Europe, but many are 
 defcended from Dutch fettlers here, and are educated. 
 with fome care. The features and outlines of their- 
 faces are European ; but the complexion, charafter,. 
 and mode of life, approach more to thofe of the native 
 inhabitants of Java. A pale languor overfprcads the 
 countenance, and not the lea.l tint of rofe is feen in any 
 cheek. While in their own houfes they drefs like their 
 flaves, with a long red checkered cotton gown defcend- 
 ing to the ankles, with large wide fleeves. They wear 
 no head-drefs, but plait their hair, and faften it with a 
 filver bodkin on the top of the head, like the country 
 girls in feveral cantons of Switzerland. The colour o€ 
 their hair is almoit univerfally black; they anoint it 
 with the oil of the cocoa nut, and adorn it with chap* 
 lets of flowers. When they go abroad to pay vifits,. 
 or to take an airing in their cairiages, and particularly 
 when they go to their evening parties, they drels mag- 
 nificently, in gold and filver fpangled muflm robs, with 
 a profufion of jewels In their hair, wiiich, howevc'', is- 
 worn without powder. They never attempt to mould 
 or regulate the fliape by any fancied idea of elegance^ 
 or any ftandard of faflilon ; and confequently formed a. 
 ftriking contraft with fuch few ladles as were lately ar- 
 rived from Holland, who had powdered hair and fair 
 complexions, had eontrafted their waifts with ftayb, 
 
 wore- 
 
 Pa'at
 
 B A 1' 
 
 wore large head-dreflcs and hoops, and prrfcvered in tlie 
 -' early cart of forcing back the elbows, c!n'n, and flioul • 
 dcrs. Every native lady is conftantly attended by a fe- 
 inale flave handfomely habited, who, as foon as her mi- 
 ftrefs is feated, fits at her feet before her, on the floor, 
 holding in her hands her millrefs's gold or filver box, 
 divided into compartments, to contain arecanut, carda- 
 mom feeds, pepper, tobacco, and llaeiied lime ; all 
 which, mixed together irf due proportions, and rolled 
 within a leaf of betel, conftitutc a maftlcatory of a ve- 
 ry pungent talle, and in general ufe. When in the 
 public affemblies the ladies find the heat difagreeable, 
 they retire to free themfclves from their coftly but in- 
 convenient habits, and return without ceremony in a 
 more light and loofe attire, when they are fcarcely re- 
 cognizable by ilrangers. The gentlemen follow the ex- 
 ample ; and throwing off their heavy and formal dreffes, 
 appear in white jackets, fometlm.es indeed adorned with 
 diamond buttons. The elderly gentlemen quit their 
 periwigs for night(^aps. Except in thefe moments the 
 members of this government have always combined their 
 perfonal gratification with the eaftern Policy of ftriking 
 awe into vulgar minds, by the affumption of exterior 
 and exchifive diftinftions. They alone, for inllance, 
 appear abroad in crimfon velvet. Their carriages are 
 diilinguiflred by peculiar ornaments. When met by 
 others, the latter muft ftop and pay homage to the for- 
 mer. One of the gates of the city is opened only to 
 let them pafs. They certainly fuccced in fupporting 
 abfolute fway over a vaft fuperiority in number of the 
 defc-ndants of the original inhabitants of the country, 
 as well as of the (laves imported into it, and of the Chi- 
 nefe attracted to it by the hope of gain ; thofe clafles, 
 though healthy, aftive, and as if quite at home, readily 
 obeying a few emaciated Europeans. Such is the con- 
 ftquence of dominion once acquired; the prevalence of 
 the mind over mere bodily exertions, and the effeft of 
 the combination of power againft divided ilrength. 
 
 The native Javanefe are in general too remote from 
 civilization to have any wants that are not ealily fatis- 
 tied in a warm and fertile climate. No alteiYipt i-s made 
 to enflave their perfons ; and they find the government 
 of tlie Dutch lefs vexatious- than that of others, v/ho 
 divide fome ihare of the fuvereignly of the ifland with 
 them. The fultan of Mataran rules to the eafl, the em- 
 peror of Jsva in the centre, and the king of Bantam to 
 
 f 69 ] 
 
 B A T 
 
 true, as the fame accounts pretend', that tie number of- Bi-tavra. 
 female births exceeds very confiderably that of males in '— v— — 
 Java. 
 
 Mod of the flaves arc imported Into it from Celebes 
 and other eaftern illands. I'hey do not form a corps, 
 or have any bond of union : nor is the general conduft 
 of their owners, towaids them calculated to aggravate 
 the misfortune of being the property of others. They 
 are not forced to exccffivc laboin-. They have fufEcient 
 fuilenance ; but many of the males among them, who 
 had formerly perhaps led an independent life till made 
 captives in their wars, have been found to take offence 
 againft their mafters upon very flight occafionj, and to 
 wreak their vengeance by aflaffir.ation. The apprthen- 
 fion of fuch an event is among the motives for prefer- 
 ring at Batavia female flaves for every ufe to which thty 
 can be applied ; fo that the ni;mber purchafed of them 
 much exceeds that of the other fex. The Haves when 
 determined on revenge often fwallow, for the purpofe of 
 acquiring artificial courage, an extraordinary dole of 
 opiuin, and foon becoming frantic as well as defperate, 
 not only ftab the objefts of their hate, but fally forth 
 to attack in like manner every perfon they .T.icet, till 
 felf-prefervation renders it neceflary to deftroy them. 
 They are faid in that ftate to be running a mud; and 
 inflances of it are not more common among flaves than 
 among free natives of the country, who, in the anguilh 
 for lofing their money, effefts, and fumetimes their fa- 
 milies, at gaming, to which they are violently addified, 
 or under the preffure of fome other pailion or misfor- 
 tune, have recourfe to the fame remedy, with the fame 
 fatal effefts. 
 
 In the country round Batavia the eye locks in vain 
 for the common animals and vegetables which it had 
 been daily accuftomed to meet in Europe. The moft 
 familiar bird about the houfe of the ambalTador's hoft 
 was the crown bird, as it was called at Batavia, which 
 was not, however, the arclea pavonina of Liun^us, but; 
 the columba crtflata, having nothing except its crcft in 
 common with the former. The fame gentleman had al- 
 fo at his country-houfe fome large caflbwary birds, 
 which, though long in his poffefilon, and having the ap- 
 pearance of tamenefs, i'ometimes betrayed the fiercenefs 
 of their nature, attacking with tiieir (Irong bill thofe 
 who apjnoached too near them. The vcTttation of 
 the country is likewife new. E\vn the parterres in the 
 
 the weft ; while the coaft and effeftive power almoft gardens are bordered, inllead of boxwood, by the Ara 
 entirely belong to Holland. Thole other fovereigns 
 
 are defcended from foreigners aho ; being Arabians, 
 who imported the Mahometan religion into Java, and 
 acquired the dominion of the country ; a few inhabi- 
 tants in the mountains excepted, who have prefcrvcd 
 their independence and their faith, and ainong other ar- 
 ticles that of the tranfmigration of iouls. According 
 to the Dutch accounts, nothing can be more tyrannic 
 than thofe Mahometan rulers. The Emperor is faid to 
 maintain his authority by an army of many thoufand 
 men difperfed throughout his territories, befide a nume- 
 rous female guard about his perfon. Thefe military la- 
 dies are trained, it feems, to aiTns, without neglctting 
 thofe aceomplifliments which may occafion a change in 
 the occupation of fome among them, rendering them 
 the companions, inftead of being the attendants, of his 
 Imperial majefty. This fingular inftitution may owe 
 its origin to the facility of obtaining recruits, if it be 
 
 bian jcfTamine, of which the fragrant /lowers adorn the 
 pagodas ot Hindoltan. The Dutch, who are fo fond 
 ot gardens in Holland, have transferred that taile, where 
 it can certainly be cultivated with more fuccefs, and in- 
 dulge it to a great extent at their houfes a little way 
 from the city of Batavia ; but ftiU within that fenny 
 diftriA, concerning which an intelligent gentleman up- 
 on the foot nfed the llrong exprcflion, that the air was 
 peftilential and the water poifonous. Yet the country 
 is everywhere fo verdant, gay, and fertile ; it is inter- 
 fperfed with fuch magnificent houfes, gardens, avenues, 
 canals, and draw-bridges ; and is fo formed in every re- 
 fpeft to pleafe, could health be preferved in it — that a 
 youth coming juft from fea, and enraptured with the 
 beauty of every objeft he {d.v; around him, but mindful 
 of the danger there to life, could not help exclaiming, 
 "what an excellent habitation it would be for immortals!" 
 The moft tolerable feafon here is from March or A-
 
 BAT 
 
 [ 70 ] 
 
 BEE 
 
 r.-.tavh. pill to November ; wlien the ruins begin, and lall the 
 ——^r^-' rtll of the year. The fea breeze fcts in about ten 
 o'clock in the morning, and continues till four or five 
 in the afternoon. It becomes then calm till feven or 
 eir;ht, when the land breeze commences, and continues 
 at intervals till day break, followed by a calm for the 
 remaining hours of the 24. Fahrenheit's thermometer 
 was, in Bata\ia road, during the Lion's remaining there, 
 from 86^ to 8»°, and in the tov.-n from 88" to 92" ; but 
 its variations by no means correfponded to the fenfa- 
 tions produced by the heat on the human frame ; the 
 latter l)eing tempered by Huy motion of the air, wiiicli 
 circumftauce has little effeil upon the thermometer. 
 Nor are the animal fuffcrings here from heat to be mea- 
 fured by its intenfenefs at any given moment of the 
 day, but by its perfiRing through the night ; when, in- 
 ftead of dlminifhing, as it does in colder countries, fome- 
 times 20 degrees, it keeps generally here within four or 
 five of what it attains in the (liade, when the fun is at 
 its highell elevation. 
 
 The native Javanefc derive, however, one advantage 
 at Icall from an atmofphere not I'ubjeft to the vicifli- 
 tudes of temperature experienced in the northern parts 
 of Europe, where difeafes of the teeth are chiefly pre- 
 -valent ; as they are here entirely exempt from fuch com- 
 plaints. Their habit of living chiefly on vegetable food, 
 and of abllaining from fermented liquors, no doubt 
 contributes to this exemption ; yet fuch is the caprice 
 of talle, that jet black is the favourite colour and ftan- 
 dard of beauty for the teeth amongft them, comparing 
 to monkeys thofe who keep them of the natural colour. 
 They accordingly take care to paint, of the deepeft 
 black, all their teeth, except the two middle ones, which 
 they cover with gold leaf. Whenever the paint or gild- 
 ing is worn off, they are as attentive to replace It on the 
 proper teeth, as the belles of Europe are to purify and 
 M'hiten theirs. 
 
 We have mentioned the rich vegetation of the coun- 
 try and the gardens which the Dutch have planted. In 
 thefe gardens or orchards they cultivate the nutmeg, 
 the clove, the camphor, and the cinnamon trees, toge- 
 ther with the pepper plant, which, creeping like a vine, 
 is fupported on a living tree. It is a fpecies of the 
 pepper plant that affords the leaf called betel, chewed fo 
 unlverfvdly by the fouthern Afiatics, and ferving tor the 
 inclofure of a few fliees or bits of the areca, from thence 
 erroneoufiy called the hetel nut. The areca nut tree is 
 among the fmallefl of the tribe of palms, but comes 
 next in beauty to the mountain cabbage tree of the Welt 
 Indies, the latter differing chiefly in its fize and amazing 
 height from the areca nut tree, the diameter of whofe 
 jointed trunk feldom exceeds four inches, or height 12 
 feet. But the fymmetry of each is perfedt ; the columns 
 of a temple cannot be more regular than the trunk, 
 'which rifes without a branch, while the broad and 
 fpreading leaves which crown the top form the orna- 
 jnented capital. The areca nut, when dried, has fome 
 fiinilltude in form and taife to the common nutmeg, but 
 is of a lefs fize. 
 
 It would have been very extraordinary, and very cul- 
 pable, in Sir George Staunton, and Dr Glllan phyfician 
 to the cmbafTy, if they had not, when on the fpot, in- 
 quired into the truth of Foerfch's account of the upas 
 ux poifon tree of Java (fee Poison Tree of Java, En- 
 cycl.) But the moft minute inquiries were made re- 
 
 fpefting it ; and the refnlt of them was, that no fuch 
 tree is known at Batavia, and certainly does not exift 
 where Foerfch has planted it. It is indeed a common ~ 
 opinion at Batavia, that there exifts in that country a 
 vegetable poifon, which, rubbed on the daggers of the 
 Javanefe, renders the fllghtell wounds incurable ; though 
 fome European praftitioners have of late afferted that 
 they had cured perfons ftabbed by thofe weapons, but 
 not without having taken the precaution of keeping the 
 wound long open, and procuring a fuppuration. One 
 of the keepers of the medical garden at Batavia affured 
 Dr Gillan, that a tree dillilllng a polfonous juice was in 
 that colleftion, but that its qualities were kept fecret 
 from moll people in the fettlement, left the knowledge 
 of them Ihould find its way to the flaves, who might be 
 tempted to make an ill ufe of it. In the fame medical 
 garden, containing it feems hurtful as well as grateful 
 fubftanccs, is found alio the plant from whence is made 
 the celebrated gout remedy, or moxa of Jaoan, men- 
 tioned in the works of Sir William Tempk, and de- 
 fcribed in the Encyclopsedia under the titles of Arte- 
 misia and Moxa. 
 
 The whole country abounds with efculent fruits, and, 
 amonfl others, with the mangofleen, which is ripe in 
 March, and is confidered as the moll delicious of all 
 fruits (fee Garcinia, Encycl.) Pine apples are in Ja- 
 va planted not in gardens, but In large fields ; and are 
 carried like turneps In heaps upon carts to market, and 
 fold for confiderably lefs than a penny each, where mo- 
 ney is cheaper than In England. It was a common 
 praftlce to clean fwords, or other Inllruments of fteel 
 or Iron, by running them through pine apples, as con- 
 taining the ftrongeil and cheapell acid for dlffolving the 
 rull that covered them. Sugar fold for about five-pence 
 a pound. All forts of provifions were cheap, and the 
 fhlps crews fed on frefh meat every day. 
 
 The ferpents and noxious reptiles In Java have been 
 mentioned elfewhere ; but Sir George Staunton affures 
 us, that not many accidents happen from them. Among 
 the pag.^n Javanefe, the crocodile, he fays, is an objett 
 not only of fear, but alfo of religious veneration, to 
 which offerings are made as to a deity. When a Java- 
 nefe feels himfcif dlfeafcd, he will fometlmes build a 
 kind of coop, and fill it with fuch eatables as he thinks 
 moft agreeable to the crocodiles. He places the coop 
 upon the bank of the river or canal, in the perfeft con- 
 fidence that, by the means of fuch offerings, he will get 
 rid of his complaints ; and perfuaded, that if any per- 
 fon could prove fo wicked as to take away thofe viands, 
 fuch perfon would draw upon himfelf the malady for 
 the cure of which the offering was made. According 
 to Sir George Staunton, Batavia road lies In 6" lo' fouth 
 lat. and 106° jl' eaft long, from Greenwich. 
 
 BEER Is a liquor fo palatable to the natives of Bri- 
 tain, and, when properly made, fo wholefome, elpeclally 
 in long voyages at fea, that Mr Thornton of Eaft 
 Smithfield obtained a patent, dated April 15. 1778, 
 for inventing a method of reducing mult and hops to an 
 elTence or extract, from which beer may be made any- 
 where, either at fea or In diltant countries. Though 
 we do not perceive any great degree of ingenuity dil- 
 played In this Invention, yet as the account of it is 
 fhort, we fhall lay It before our readers. 
 
 His method then of preparing an effence or extraft 
 of malt and hops is, by the tranfmitteJ heat of com- 
 
 preiTed 
 
 Batavia 
 Beer
 
 BEE 
 
 prelTed vapour of boiling water, and a proper apparatus 
 ' for that purpofe. This apparatus may be made of iron, 
 tin, or copper : it confifts of a boiler of any dimcnfions, 
 a double vcfTel, and condudting tubes. The double vef- 
 fel confills of one vcflel placed within another, and fitted 
 tight at their rims. The upper veflel forms the upper 
 part of the under veflel, and contains the liquor to be 
 evaporated. The under veflel is everywhere inclofed 
 except at an aperture communicating with the boiler, 
 and at another aperture communicating with the con- 
 ducing tubes ; and is conft;rufted fo as not to allow 
 any part of the vapour condeufed into drops within it 
 to efcape, except back again into the boiler : it is not 
 fo cxtenfive as to aft as a common refrigeratory, and 
 yet is capacious enough to prevent the liquor boiling 
 over. The aperture communicating with the boiler is 
 large enough to freely admit the vapour from the boiler 
 into the under veflel ; and tlie aperture communicating 
 with the condufting tubes is of a proper fize to allow 
 of the vapour in the under veflel being comprefled, to 
 a degree capable of tranfmittirig to the liquor to be 
 evaporated a proper heat, and at the fame time to ferve 
 as a paflage for more heat than is neceflary to keep up 
 that degree of compreffion. The condutting tubes are 
 to convey this fuperfluous heat or vapour, to be ufed 
 for farther purpofes, or immediately out of the build- 
 
 BEETLE, an infeft defcribed in the Encyclopedia 
 under the name given to it by naturalifts, Scarab.eus. 
 Since that aticle was publiflied, we have met with an 
 account of a nondefcript fpecies, vvihich is furniflied 
 with very Angular armour for its own defence. It was 
 brought to M. Vaillant in the interior parts of Africa 
 by a Nimiqua woman, and is by him called a fuperb 
 beetle, not to be found in any cabinet of Europe. 
 " While I was examining this beautiful infeft (fays he) 
 with attention, I felt my face fuddenly wetted by a cauf- 
 tic liquor, of a very ftrong alkaline fmcll. The fprink- 
 ling wa-s accompanied by a fort of explofion, loud enough 
 to be heard at fome diftance. Unfortunately fome of 
 the liquor entered one of my eyes, and occafioncd fuch 
 infupportable pain, that I thought I fhould have loft; 
 the fight of it. I was obliged to keep it covered' for 
 feveral days, and bathe it from time to time with milk. 
 In every part of my face that the alkaline liquor had 
 touched, I felt the pain of a burn; and everywhere the 
 flcin changed to a deep brown, which wore out only by 
 degrees and a long time after. This will not be furpri- 
 fing to many, who already are acquainted with the fame 
 property in feveral infefts of the fame genus ; for Jn- 
 ftance, in that beautiful golden green bupreftis, which 
 is fo common in our kitchen gardens in Europe : but 
 as the infeft of which I am here fpeaking is much lar- 
 ger, and inhabits a very hot country, it is natural that 
 the effeA produced by it fliould be more linking ; tho' 
 the liquor which our golden bupreftis ejefts at its enemy 
 
 71 ] B E H 
 
 occafions a very fenfible fmart, and its fme'l Is confider- 
 ably pungent." 
 
 The naturaliils Dorci and Olivier have given. In their , 
 Entomology, the figure of this African infcft, which 
 our author communicated to them, hut they have given 
 it erroneoufly. The human face, obfervable on its an- 
 terior corctlet in their figure, does not exift in nature ; 
 but M. Va'lhmt having given no figure of it himfelf, 
 we cannot gratify our readers with a correft reprefen- 
 tation. 
 
 BEGAH, a land meafure in Bengal, about one-third 
 of an Englifh acre. 
 
 BEHADER fFallanl), a title of honour conferred 
 by the Mogul emperors upon either Mahomedans or 
 Hindoos, and placed after their name or other title. 
 
 BEHEM (Martin), though hitherto little talked of, 
 was one of the moll euterprifing men that ever lived, 
 and deferves to have his name tranfmitted with reve- 
 rence to the latefl; pofterity. Born at Nuremberg, an 
 Imperial city in the circle of Franconia, of a noble fa- 
 mily not yet extin£l, he had the beft education which 
 the darknefs of that age would permit him to have ; 
 and the ftudies to which from his infancy he was mod 
 addifted, were thofe of geography, aftronomy, and na- 
 vigation. As he advanced in life, he often thought of 
 the exiftence of the antipodes and of a weftern conti- 
 nent, of which he was ambitious to make the difco- 
 very. 
 
 Filled with this great idea, in 1459 he paid a vifit 
 to Ifabella, daughter of John I. king of Portugal, at 
 that time regent of the duchy of Burgundy and Flan- 
 ders ; and having informed her of his defigns, he pro- 
 cured a veflel, in which, failing weftward, he was the firit 
 European who is known to have lauded 011 the Ifland ot 
 Fayal. He there eft;abliftied in 1460 a colony of Fle- 
 mings, whofe defcendants yet exift in the Azores, which 
 were for fome time called the Flemilh Iflands. This cir- 
 cumftance Is proved, not only by the writings of con- 
 temporary authors, but alfo by the manufcripts prefer- 
 ved in the records of Nuremberg ; from the Latin of 
 which the following Is tranflated : "Martin Behem ten- 
 dered his fervices to the daughter of John king of Lu- 
 fitania, who reigned after the death of Philip of Bur- 
 gundy, furnamed the Gooii ; and from her procured a 
 flilp, by means of which, having failed beyond all the 
 then known limits of the Wellern Ocean, he was the 
 firft; who in the memory of man difcovered the ifland of 
 Fayal, abounding with beech trees, which the people of 
 Lufitania call _/(7yf ; whence it derived Its name. Af- 
 ter this he difcovered the neighbouring iflands, called 
 by one general name the A%or<-s, from the multitude of 
 hawks which build their nefts there (for the Lufitanians 
 ufe this term for hawks, and the French too ufe the 
 word ejfos or efores in their purfuit of this game) ; and 
 left colonies of the Flemilh on them, when they began 
 to be called Flemlfli Iflands (a)." 
 
 After 
 
 BcgaU 
 
 II 
 Behem. 
 
 (a) Although this record Is contrary to the generally received opinion, that the Azores were difcovered by 
 Gonfalva Velho, a Portugucfe, yet its authenticity feems unqueftionable. It is confirmed not only by feveral 
 contemporary writers, and by Wagenfeil, one of the moft learned men of the laft century, but likevvife by a note 
 v/ntten on parchment in the German language, and fcnt from Nuremberg, a few years ago, to M. Otto, who was 
 then mveftigating the difcovey of America. The note contained, with other things, the following facts: " Mar. 
 tin Beham, Efq; fon of Mr Martin Beham of Scoperin, lived in the reign of J(,hn II. king of Portugal, in aa; 
 ifland which he difcovered, and called the ifland of Fayal, one of the Azores, lying in the Weftern Oceim..
 
 B E H 
 
 [ 72 ] 
 
 B E H 
 
 Buhem. After having obtained from tin: regent a grant of 
 ^~~*''~*'' Fayal, and refidcd there about twenty years, Behcm 
 applied in 1484 (eijjht years before Columbus's expe- 
 dition) to John II. king of Portugal, to procure the 
 means of undertaking a great expedition towards the 
 fouth-weft. This prince gave him fomc fliips, witii 
 which he difcovered that part of America which is now 
 called Brazil ; and h: even failed to the Straits of IVIa 
 gellan, or to the country of fome favage tribes whom 
 he called Patagoiiians, from the extremities of their bo- 
 dies being covered with a flcin more like a bear's paws 
 than human hands and feet. 
 
 A fa6t fo little known, and apparently fo derogatory 
 to the fame of Columbus, ought not to be admitted 
 without fufficient proof; but the proofs which have 
 been urged in fupport of its authenticity are fuch as 
 cannot be controverted. They are not only the letters 
 of Behem himfelf, written in i486, and preferved in 
 the archives of Nuremberg, but hkewife the public re- 
 cords of that city ; in which we read that " Martin 
 Behem, traverfing the Atlantic Ocean for feveral years, 
 examined the American iflands, and difcovered the ftrait 
 which bears the name of Magellan before either Chrif- 
 topher Columbus or Magellan failed thofe feas; whence 
 he mathematically di'ineated, on a geographical chart, 
 for the king of Lufitania, the fituation of the coall a- 
 round every part of that famous and renowned ftrait 
 long before Magellan thought of his expedition." 
 
 This wonderful difcovery has not efcaped the notice 
 of contemporary writers. The following patTage is 
 tranflated from the Latin chronicle of Hartman Schedl: 
 " In the year 1485, John II. king of Portugal, a m.tn 
 of a magnanimous fpirit, furnifhcd fome galleys with 
 provifions, and fent them to the fouthward, beyond the 
 Straits of Gibraltar. He gave the command of this 
 fquadron to James Canus, a Portuguefe, and Martin 
 Behem, a German of Nuremberg in Upper Germany, 
 defcendcd of the family of Boima : a man very well ac- 
 quainted with the fituation of the globe ; bleffed with 
 a conftitution able to bear the fatigues of the fea ; and 
 who, by adual experiments and long failing, had made 
 himfelf perfedlly mafter with regard to the longitudes 
 and latitudes of Ptolemy in the weft. Thefe two, by 
 the bounty of Heaven, coafting along the Southern 
 Ocean, and having croffed the equator, got into the 
 other iiemifphere, where, facing to the eaftward, their 
 ftiadovvs projefted towards the fouth and right hand. 
 Thus, by their induftry, they have opened to us ano- 
 ther world hitherto unknown, and for many years at- 
 tempted by none but the Genoefe, and by them in vain. 
 Having finifhed this cruize in the fpace of 26 months, 
 they returned to Portugal with the lofs of many of their 
 feamen by the vioL-nce of the climate." 
 
 Befides tlu's evidence of the firft difcovery of America 
 having been made by Behem, we find the following 
 particulars in the remarks made by Petrus Mateus on 
 the canon law, two years before the expedition of Co- 
 lumbus : " Pr'tma navigat tones , &c. The firft Chriilian 
 voyages to the newly difcovered iflands became frequent 
 under the reign of Henry, fon of John, king of Lufi- 
 tania. After his death Alphonfus V. profecuted the 
 defign ; and John, who fucceeded him, followed the 
 plan of Alphonfus, by the affiftance of Martin Behem, 
 a very flcilful navigator; fo that in a fliort time the name 
 ni Lufitania became famous ov«r the whole world." 
 
 Cellarius, one of the moft learned men of his age, fayi 
 exprefsly, " Bihuimeus non moilo. Sec. Bochm did nut. "" 
 think it enough to furvey the ifland of Fayal, which he 
 iirft difcovered, or the other adjacent iflands which th: 
 Lufitamans call A-iores, and we, after the example of 
 Birhm's companions, call FUm'iJh iflands, but advanced 
 ftill farther and farther fouth, until he arrived at the re- 
 moteft ftr;ut, tiirough which Ferdinand Magellan, fol- 
 lowing his track, afterwards failed, and called it after 
 his own name." 
 
 All thefc quotations, which cannot be thought te- 
 dious, fince they ferve to prove a fa£l almoft unknown, 
 feem to denionftrate, that the firll difcovery of America 
 is due to the Portuguefe and not to the Spaniards; and 
 that the chief merit belongs to a German allronomer. 
 The expedition of Ferdinand Magellan, which did not 
 take place before the year 1519, arofe from the follow- 
 ing fortunate circumftance : Thi» perfun, being in the 
 apartment of the king of Portugal, faw there a chart of 
 the coaft of America drawn by Behem, and at once 
 conceived the bold project of following the fleps of this 
 great navigator. Jerome Benzoii, who publilhed a de- 
 fcription of America in 1550, fpeaks of this chart ; a 
 copy of which, fent by Behem himfelf, is preferved in 
 the archives of Nuremberg. The celebrated aftronomer 
 Riccioli, though an Italian, yet does not feem willing 
 to give his countryman the honour of this important 
 difcovery. In his Geographia Refarmata, book iii. p. 90. 
 he fays, " Chriftopher Columbus never thonglit of an 
 expedition to the Weft Indies until his arrival in the 
 ifland of Madeira, where, amufing himfelf in forming 
 and deliiicaling geographical charts, he obtained infor- 
 mation from Martin Eoehm, or, as the Spaniards fay, 
 from Alphonfus Sanches de Huelva, a pilot, who had 
 chanced to fall in with the illand afterwards called Do- 
 minka." And in another place: " Let Boehm and 
 Columbus have each their praife ; they were both ex- 
 cellent navigators ; but Columbus would never have 
 thought of his expedition to America, had not Boehm 
 goP-t there before him. His name is not fo much cele- 
 brated as that of Columbus, Americus, or Magellan, 
 although he is fuperior to them all." 
 
 That Behem rendered fome very important fervices 
 to the crown of Portugal, is put beyond all controverfy 
 by the recompence bellowed on him by King John ; ot 
 which the following account has been given to the pub- 
 lic from the archives of Nuremberg. " In the year 1485, 
 on the 18th of Feb. in Portugal, in the city of AUafa- 
 vas, and in the church of St Salvador, after the mafs, 
 Martin Behem of Nuremberg was made a knight, bv 
 the hands of the moft piiiffant Lord John II. king of 
 Portugal, Algarve, Africa, and Guinea ; and his chief 
 fquire was the king himfelf, viho put the fword in his 
 belt ; and the Duke of Begia was his fecond fquire, 
 who put on his right fpur ; and his third fquire was 
 Count Chiiftopher de Mda, the king's coufin, who put 
 on his left fpur; and his fourth fquire was Count Mar- 
 tini Marbarinis, who put on his iron helmet ; and the 
 king himfelf gave him the blow on the flioulder, which 
 was done in the prefence of all the princes, lords, and 
 knights of the kingdom ; and he efpoufed the daughter 
 of a great lord, in confideration ot the important fer-' 
 vices he had performed ; and he was made governor of 
 the ifland of Fayal." 
 
 Thefe marks of dillindiion, conferred on a ftranger, 
 
 could
 
 B E H [ 73 .1 . B E H 
 
 Beliem. coulJ not be meant as a recompciico for the dlfcovery of ful objection to the truth of Bchem's claim to tlie dif- 
 — 'r~— the Azores, which was made twenty years before, but covery of America ; for if it was really difcover<-d by '' 
 as a rewrard for the dlfcovery of Congo, from whence him, wiiy did not he leave behind him fome writing to 
 the Chevalier Behem had brought gold and diflerent confirm the dlfcovery to himfeli ? and why did not the 
 kinds of precious w.ircs. This dlfcovery made much court of Portugal, fo jealous ot tlie dlfcovery of the 
 greater impreflion than that of a wellern world made new worhl, protell againll the cxciufive claim ot tiic 
 at the fame time, but which neither increafed the wealth Spaniards ? 
 
 of the royal treafury, nor fatisfied the avarice of the To tliefe objeftlons we may reply, that, however 
 merchants. plaufible they may at firll appear, they do not in the 
 
 III 1492 the Chevalier Behem, crowned with hon<iiirs fmalleft degree invalidate the pofitive evidence which 
 and riches, undertook a journey to Nuremberg, to vlfit we have urged for the Chevalier Behem's being the real 
 his native country and his family. He there made a difcoverer of the new world ; for it would furely be 
 terreftrial globe, which is looked on as a mafterpiece for very abfurd to oppofe the difficulty of qffigning motives for 
 that time, ami which Is ItlU prtferved in tlie lilirary of certain aftions performed at a remote period, to the rea- 
 that city. Tlie outline of his difcoveries may there be /ity oi other aftlons for which we have the teltimony of 
 icen, under tiie name of weftern lands ; and from their a cloud of contemporary witncncs. Suppofing It were 
 fituation It cannot be doubted that they are tlie prefent true, therefore, that Belicm had left behind him no wri- 
 coalls of Brazil, and the environs of the Straits of Ma- ting claiming to hlmfelf the dlfcovery of any part of 
 gcllan. This globe was made in the fame year that Co- the continent of America, the only inference which 
 lunibus ftt out on his expedition; therefore It is im- could be drawn from his liience would be, either that he 
 poflible that Behem could iiave profited by the works was a man of great modefty, or that his mind was in- 
 ofthat navigator, who befides went a much more north- tent only on the acquifition of knowledge to hlmfelf, 
 eriy courft. without feeling the ufual Impulfe to communicate that 
 
 After having performed feveral other interefling voy- knowledge to others. But it is not true that he has 
 ages, the Chevalier Behem died at Lilhon in July 15&6, left behind him no claim of this dlfcovery to himfelf. 
 reu-retted by every one, but leaving behind him no other The letters to which we have appealed, and which are 
 work than the globe and chart which we have ju(t been preferved In the archives of Nuremberg, together with 
 fpeaking of. The globe is made from the writings of the globe and map, which he certainly made, furnifh as 
 Ptolemy, Pliny, Slrabo, and efpeclally from the account complete a confirmation of his claim as could have beea 
 of Mark Paul the Venetian, a celebrated traveller of furnifhed by the moft elegant account of his voyages, 
 the I3tli century ; and of Joliu Mandevlllc, an Engllfh- For the iilence of the Portuguefe, many reafons 
 
 man, who, about the middle of the 14th century, pub- might be affigned. The difcoveries of Columbus were 
 lidied an account of a journey of 33 years in Africa and made fo much farther north than thofe of Behem, that, 
 Afia. He has alio added the important difcoveries made in an age when geographical knowledge was fo very li- 
 by hlmfelf on the coatts of Africa and America. mited, both Spaniards and Portuguefe might very na- 
 
 From thefe circumftantlal accounts, but very lately turally believe that the country difcovered by the for- 
 brought to light, there can be little doubt, we think, mer of thefe navigators liad no conneftion with that 
 hut that America was difcovered by Martin Behem. difcovered by the latter. At any rate, the Portuguefe, 
 Dr Robertfon is indeed of a different opinion ; but whofe difcoveries proceeded from avarice, were fatisfied 
 great as we willingly acknowledge his autiiority to be, with fcraping together gold wherever they could find 
 we may differ from him without prefumption, llnce he it; and finding it in Africa, they thought not of fearch- 
 had it not in his power to confult the German docu- ing for it In a more dlitant region, till the fuccefs of the 
 ments to which we have appealed, and has hlmfelf ad- Spaniards (hewed them their mlllake. 
 vanced fails not eafily to be reconciled to his own opi- One thing more is worthy of attention. The long 
 
 nion. He allows that Behem was very intimate with flay of Columbus at Madeira makes his interview with 
 Chrltlopher Columbus ; that he was the greatefl geo- Behem more than probable. It is impoffible that he 
 grapher of his time, and fcholar of the celebrated John fhould have neglefted feeing a man fo intcrefting, and 
 Miiller, or Reglomontanus ; that he had difcovered, in who could give him every kind of information for the 
 1483, the kingdom of Congo, upon the coall of Afri- execution of the plan which he had formed. The ma- 
 ca ; that he made a globe which Magellan made ufe of; riners who accompanied the Chevalier Behem might 
 that he drew a map at Nuremberg, containing the par- alfo have fpread reports at Madeira and the Azores 
 ticulars of his difcoveries ; and that he placed in this concerning the dlfcovery of which they had been wit- 
 chart land which Is found to be in the latitude of neffes. What ought to confirm us in this is, that Ma- 
 Guiana. He adds indeed, without proof, that this land fiana fays himfelf (book xxvi. chap, iii.), that a certain 
 was a fabulous ifland ; but if authentic records are to veffel going to Africa, was thrown by a gale of wind 
 give place to bare affertion, there is an end of all hifto- upon certain unknown lands; and that the failors at 
 rical evidence. If Behem took for an ifland the iirfl their return to Madeira had communicated to Chriflo- 
 land which he difcovered, it was a miflake furely not fo pher Columbus the clrcumftances of their voyage. Afl 
 grofs as to furnifh grounds for queflioning his veracity, authors agree that this learned man had fome informa- 
 or for withholding from him for ever that juftice which tion refpefting the weftern fliores ; but they fpeak in 
 has been fo long delayed. a very vague manner. The expedition of the Chevalier 
 
 But this very delay will by fome be thought a power- Behem explains the myftery (b). 
 
 SuppL. Vol. I'. Part I. K BEREANS, 
 
 Behem. 
 
 ^b) For the greater part of this memoir we are indebted to M. Otto's paper on the dlfcovery of America, 
 
 publifhed
 
 B E R C 74 J B E R 
 
 Bereans. BERKANS, in anciint church hiftory, the inhabi- therefore he rntcrtains no doubts cither of his faith or Btreaiis. 
 
 • tants of Bcrea. They are highly commended in Scrij)- his confeciiient falvatiun through the merits of Chrift, ^"~~v— 
 
 ture for their ready reception of the gofjiel, upon a fair who died and vofe again for tliat pnrpofe. In a word, 
 
 and impartial examination of its agreement with the Ohl they argue, that the Gofpcl .would not be what it is 
 
 Ttllament prophecies. Sopater, a Berean, attended the held forth to be. " glad tidings of great joy," if it did 
 
 apoflle Paul to Afia. Ails xvii. lo — 13. and xx. 4. not bring full perfonal aiTurance of eternal falvation to 
 
 B ERE ASS, in modern cliurch hiftory, a fcft of Pro- the believer : which adurance, they infill, " is the pre- 
 
 tedant difleuters from the church of Scotland, who fent infallible privilege and portion of every individual 
 
 take their title from, and profefsto follow, the example believer of the Gofpel." Thefe definitions of faith, and 
 
 of the ancient Bereans, in building their fvftem of faith its inftparable concomitant afi'urance, they prove bv a 
 
 and praftice upon the Scriptures alone, without regard variety of texts, which our room permits us not to 
 
 to any human authority whatever. quote. 
 
 Doflrinei. "^^"^ Bereans agree with the great majority of Chrif- 3. Confiftently with the above definition of faitli, 
 
 tians, both Proteltants and Catholics, refpecting the they fay, that the fin againft the Holy Gholl, which 
 
 doftrine of the Trinity, wliich they hold as a fundameii- has alarmed and puzzled fo many in all ages, is nothing 
 
 tal article of the Chriftian faith ; and they alio agree in elfe but unbelief; and that the expreflTion, that " it (hall 
 
 a great meafure with the prnj^jfed principles of both our not be forgiven, neither in this ivorhl nor that which is 
 
 eftabliflicd churches refpccting predelliaation and elec- to come," means only, that a perfon dying in infidelity 
 
 tion, though they allege that tliefe doftrines are not con- would not be forgiven, neither under the former difpen- 
 
 fiftently taught in either church. But they differ from fation by Mofes (the then prefent difpenfation, kingdom, 
 
 the majority of all fefts of Chriftians in various other or government of God), nor under the Gofpel difpen- 
 
 jmportant particulars. Such as, fation, which, in refpeft of the Mofaic, was a kind of 
 
 1. Refpccting our knowledge of the Deity. Upon future world or kingdom to come. 
 
 this fubjeft, they fay that the majority of proftfled 4. The Bereans interpret a great part of the Old 
 
 Chriftians Humble at the very threfhold of revelation ; Teftament prophecies, and in particular the whole of 
 
 and, by admitting the doftrine of natural religion, na- the Plalms, excepting fuch as are merely hiftorical or 
 
 tural confcience, natural notices, &c not founded upon laudatory, to be typical or prophetical of Jefus Chrift, 
 
 revelation, or derived from it by tradition, they give up his fufferings, atonement, mediation, and kingdom: and 
 
 the caufe of Chriftlanity at once to the infidels ; who they efteem it a grofs perverfion of thefe Pfalms and 
 
 may juilly argue, as Mr Paine in faft does in his Age prophecies to apply tiiem to the experiences of private 
 
 of Reafon, that there is no occafion for any revelation Chriftians. In proof of this, they not only urge the 
 
 or word of God, if man can difcover his nature and per- words of the apoftle, that " no prophecy is of any pri- 
 
 feftions from his works alone. But this, the Bereans vate interpretation," but they infift that the whole of 
 
 argue, is beyond the natural powers of human reafon ; the quotations from the ancient prophecies in the New^ 
 
 and therefore our knowledge of God is from revelation Teftament, and particularly thofe from the Pfalms, are 
 
 alone; and that without revelation man would never have exprefsly applied to Chrift. In this opinion many other 
 
 entertained an idea of his exiftence. clafies of Proteftants agree with them. 
 
 2. With regard to faith in Chrift, and affurance of 5. Of the abfolute all-fuperintending fovereignty of 
 falvation through his merits, they differ from almoft all the Almighty, the Bereans entertain the higheft ideas, 
 other fefts whatfoever. Thefe they reckon hiftparahle, as well as of the uninterrupted exertion thereof over 
 or rather the yrtwc ,■ becaufe, they argue, God hath ex- all works in heaven, earth, and hell, however unfearch- 
 prefsly declared, " He that believeth fhall be faved ;" able by his creatures. " A God without eleftlon (they 
 and therefore it is not only abfurd, but impious, and in argue), or choice in all his works, is a god without ex- 
 a manner calling God a liar, for a man to fay, " / be- iftence — a mere idol — a non-entity. And to deny God's 
 //'cTif the Gofpel, but ^ai'f lyoa^/j- neverthelefs of my own eleftion, purpofe, and exprefs will in all his works, is 
 falvation." With regard to the various diftinftions and to make him inferior to ourfelves." For farther parti- 
 definitions that have been given of diiTerent kinds of culars refpefling the Berean doftrines, we mull refer 
 faith, they argue, that " there is nothing incomprehen- the reader to the works of Melfrs Barclay, Nicol, 
 fible or obfcure in the meaning of this word as ufed in Brookfhank, Sec. 
 
 Scripture ; but that as faith, when applied to human The Bereans firft aflembled as a feparate foclety of Origina 
 
 teftimony, fignifies neither more nor lefs than the mere Chriftians in the city of Edinburgh in autumn 1773, 
 
 fimple belief of that teftimony as true, upon the autho- and foon after in the parifti of Fettercairn. The oppo- 
 
 rity of the teftifier : fo, when applied to the teftimony nents of the Berean doftrines allege, that this new 
 
 of God, it fignifies precifely the belief of his teftimony, fyftem of faith would never have been heard of, had not 
 
 and relling upon his veracity alone, without any kind Mr Barclay, the founder of it, been difappointed of a 
 
 of collateral fupport from concurrence of any other evi- fettlement in the church of Scotland. A refpeftable 
 
 dence or teftimony whatever." And they infift, that clergyman of the eftablifhed church has even hinted 
 
 as this faith is the gift of God alone, fo the perfon to fomething to this purpofe in Sir John Sinclair's Statif- 
 
 whom it is given is as confcious of poffefling it, as the tical Account, Vol. IX. p. 599. But the Bereans, in 
 
 being to whom God gives life is of being alive ; and anfwer to this charge, appeal not only to Mr Barclay's 
 
 doftrine. 
 
 publiftied firft in the fecond volume of the American Tranfaftions, and afterwards by Nicholfon in N° XL and 
 III. of his Journal.
 
 B E R [ 
 
 Bereans doArine, uniformly preached in the church of Fetter- 
 """V^~' cairn, and many other places in that neighbourhood, 
 for fourteen years before that benefice becaine vacant ; 
 but likewife to two different treatifes, containing the 
 fame dodrines, publilhtd by him about ten or twelve 
 years before that period. They admit, indeed, that, 
 previous to May 1773, when the general affembly, by 
 fuftaining the king's prefentation in favour of Mr Foote, 
 excluded Mr Barclay from fucceeding to the church of 
 Fettercairn (notwithftanding the almoft unanimous de- 
 fire of the parifhioners), the Bereans had not left the 
 eftablifhed church, or attempted to ereft themfelves in- 
 to a diftinft fociety ; but they add, that this was by 
 no means neceffai-y on their part, until by the aflembly's 
 decifion they were in danger of being not only deprived 
 of his inftruAions, but of being fcattcred as (hcep with- 
 out a (hcpherd. And they add, that it was Mr Bar- 
 clay's open and public avowal, both from the pulpit 
 and the prefs, of thofe peculiar fentiments which now 
 diftinguifh the Bereans, that was the firft and principal, 
 if not the only, caufe of the oppofition fet on foot 
 againft his fettlement in Fettercairn. 
 PraiSice. Having thus given a concile view of the origin and 
 diftinguilhing doftrines of Bereanifm, it only remains to 
 mention a few particulars relative to the praftice of the 
 Bereans as a Chriftian fociety. Infant baptifm they 
 confider as a divine ordinance inftituted in the room of 
 circumcifion ; and they think it abUird to fuppofe that 
 
 IS 
 
 1 B E R 
 
 than to examine into each others notions of philofophy. Berean?, 
 They both recommend and praClife, as Chriilian duties, Bfrlte"-. 
 fubmilTion to lawful authority ; but they do not think '^° "'' 
 that a man, by becoming a Chrillian, or joininrr their ''"""^ 
 fociety, is under any obligation, by the "rules of the 
 Gofpel, to renounce his rights of private judgment up- 
 on matters of public or private importance. Upon all 
 fuch fubjedls they allow each other to think and aft as 
 each may fee it his duty. And they require nothing 
 more of their members than a uniform and fteady pro. 
 feflion of the apoftolic faith, and a fuitable walk and con- 
 verfation. With regard to feet-wafliing and the like 
 pradices, which fume other feds of Chriftians confider 
 as duties, the Bereans are of opinion that they arc by 
 no means obligatory. They argue, that the example 
 given by our Saviour of wafliing the feet of his difciples 
 was not an inlUtution of an ordinance, but merely a fa- 
 miliar inllance, taken from the cuftomofthe country, 
 and adopted by our Lord on that occalion, to teach his 
 followers that they ought at all times to be ready to 
 perform even the meaneft. offices of kindnefs to each 
 other. 
 
 It may not be improper to add to the above delinea, P'"'^'^"' 
 tion of the principles and practice of the Bereans, tliat"^'*" 
 their dodrine has found converts in various places of 
 Scotland, England, and America ; and that they have 
 congregations in Edinburgh, Glafgow, Pailley, Stirling, 
 Crieff, Dundee, Arbroath, Montrofe, Fettercairn, A- 
 
 infants, who all agree are admiffible to the kingdom of berdeen, and other towns in Scotland ; as well as in 
 
 God in heaven, fhould neverthelels be incapable of be- London and various places in England; not to add 
 
 ing admitted into His vifible church on earth. They Pennfylvania, the Carolinas, and other States in Ame- 
 
 commemorate the Lord's fupper in general once a- rica. 
 
 month ; but as the words of the inftitution fix no par- The above account of the dodrines, origin, pradice, 
 
 ticular period, they fometimes celebrate it oftener, and and prefent ftate of this fociety, has been given to us 
 
 fometimes at more diftant periods, as may fuit their ge- by the founder himfelf. 
 
 neral convenience. In obferving this ordinance, they 
 
 follow the primitive apoltolic plan, without any previous 
 
 days of falling or preparation ; as they apprehend that 
 
 fuch human inilitutions only tend to make an idol of 
 the ordinance, and to lead people to entertain erroneous 
 ideas of its fuperior folemnity and importance. Equal 
 and univerfal holinefs in all manner of converfation, they 
 recommend at all times, as well as at the table of the 
 Lord. They meet every Lord's day for the purpole 
 of preaching, praying, and exhortation to love and good 
 works. With regai-d to the admilTion and exclufion of 
 members, their method is very fimple. When any perfon, 
 after hearing the Berean dodrines, profeffes his belief 
 and affurance of the truths of the Gofpel, and defires to 
 be admitted into their communion, he is cheerfully re- 
 ceived upon his profeflion, whatever may have been his 
 former manner of life. But if fuch an one fhould after- 
 wards draw back from his good profefTion or pradice. 
 
 BERKENHOUT (Dr John), was about the year 
 1730 born at Leeds in Yorkfhire, and educated at the 
 grammar-fchool in that town. His father, who was 3 
 merchant, and a native of Holland, intended him for 
 trade; and with that view fcnt him at an early ai'C to 
 Germany, in order to learn foreign languages. After 
 continuing a few years in that country, he made the 
 tour of Europe in company with one or more Engliih 
 noblemen. On their return to Germany they vilited 
 Berlin, where Mr Berkenhout met with a near relation 
 of his father's, the Baron de Bielfeldt, a nobleman then 
 in high ellimation with Frederick the Great king of Pruf- 
 fia; ditllnguiihed as one of the founders of the koyal A- 
 cademy of Sciences at Berlin, and univerfally known as 
 a politician and a man of letters. With tliis relation 
 our young traveller fixed his abode for fome time; and, 
 regardlefs of his original deftination, became a cadet in 
 a Pruflian regiment of foot. He foon obtained an en- 
 
 they firft admonilh him; and if that has no effcd, they fign's commifTion, and in the fpace of a few years was 
 leave him to himfelf. They do not think that they advanced to the rank of captain. He quitted the Pruf- 
 have any power to deliver up a backfliding brother to fian fervice on the declaration of war between Encrland 
 Satan. That text and other fimilar palfages, fuch as, and France in 1756, and was honoured with thel-om- 
 " Whatfoever ye (hall bind on earth (hall be bound in ' 
 
 heaven," &c. they confider as reftridfed to the apoltles 
 and to the iiifpired teilimony alone, and not to be ex- 
 tended to any church on earth, or any number of 
 churches or of Chriftians, whether deciding by a majo- 
 rity of votes or by unanimous voices. Neither do they 
 think themfelves authorifed, as a Chriftian church, to 
 enquire into each others political opinions, any more 
 
 mand of a company in the fervice of his native country. 
 AVhen peace was concluded in 1 760, not choofing, we 
 fuppofe, to lead a life of inadivity on half-pay, he went 
 down to Edinburgh, and commenced fludent of phylic. 
 During his refidence at that univerfity, he publilhed his 
 Cla-vis ingUca Lingua Botank.f ; a book of great uti- 
 lity to all lludents of botany. 
 
 Having continued fome years at Edinburgh, Mr Ber- 
 K 2 kenhout
 
 B E Pv ' [ 76 1 B E Z 
 
 Berkcn- kenhoiit went to the univerfity of Leyder., where he his knowleilge, has been compared to the Admirable Bernoulli 
 
 ''Q '-'t- ^was admitted to the degree of M. D. in the year 1765. Crichton, died on the 3d of April 1 791. II 
 
 ' On this occafion he pubhlhed a thcfis, intitled, Differ- BERNOULLI (John), a celebrated mathematician, ^""'"' , 
 
 talk medica imiu^urnHs de Podagra, which he dedicated was born at Bafil tlic 7tli of Auguft 1667. His fa- ^ '' 
 
 to his relation Baron de Bielftldt. Returning to Etig- ther intended him for trade; but his own inclination 
 
 land, Dr Berkenhout fettled at Ifleworth in Middlefcx, was at firll for the belles lettres, which, however, like 
 
 and foon after publllhed his rharmacopahi Medici, the his brother James, whofe life is given in the Encyclo- 
 
 third edition of which was printed in i-;i<2. In 1778 paedia, he left for mathematics. He laboured with his 
 
 '' he was fent by goverjiment with the commifTioners to brother to difcover the method ufed by Leibnitz, in his 
 
 America. Neither the commifTioners nor their fecre- effays on the differential calculus, and gave the firll prin- 
 
 tary were fuffeved by the congrefs to proceed further ciples of the integral calculus. Our aLithor, with Melfrs 
 
 than New York. Dr Berkenhout, hnuevcr, found Huygens and Leibnitz, is faid to have been the fiill 
 
 means to penetrate as far as Philadelpliia, where the who gave the folutlou of the problem propofed by James 
 
 congrefs was then affembled. He appears to have re- Bernoulli, concerning the catenary, or curve formed by 
 
 mained in that city for fome time without molellation : a chain fufpeuded by its two extremities. But for more 
 
 but at lad they began to fufpcft that he was fent by on this fubjeft, fee Arch in this Supplement. 
 Lord North for the purpofe of tampering with fome of John Bernoulli had the degree of doftor of pbyfic at 
 
 their leading members. The Dodlor was immediately Bafil, and two years afterward was named profefibr of 
 
 feized and committed to prifon. mathematics in the univerfity of Groningen. [t was 
 
 How long he remained a ftate prifoner, or by what here that he difcovered the mercurial phofphorus, or lu- 
 
 means he obtained his liberty, we are not informed ; minous barometer ; and where he refolved the problem 
 
 but we find from the public prints, that he rejoined the propofed by his brother concerning ifoperimetricals. 
 commilTioners at New York, and returned with them to On the death of his brother James, the profclTor at 
 
 England. For this temporary facrifice of the emolu- Bafil, our author returned to his native country, againft 
 ments of his profeffion, and in confideration of his ha- the preffing invitations of the niagiftrates of Utrecht to 
 ving, in the fervice of his fovcreign, committed himfelf come to that city, and of the univerfity of Groningen, 
 to the mercy of a congrefs of enraged republicans, he who wifted to retain him. The Academic Senate of 
 obtained a penfion. Bafil foon appointed him to fucceed his brother, with- 
 
 Many years previous to this event, Dr Berkenhout out aflembling competitors, and contrary to the efta- 
 had publifhed his Outlines of the Natural Hi/lory of Great bliflied praftice ; an appointment which he held during 
 Britain and Ireland, in three volumes izmoj a work his whole life. 
 
 which eftabhfhed his reputation as a naturalifl. In the In 1714 was publifhed his treatife on the manage- 
 
 vear 177? he wrote a pamphlet, intitled, An EJfay on ment of (hips; and in 1730 his memoir on the elliptical 
 the Bite of a Mad Dog, in which the Claim to Infallibi- figure of the planets gained the prize of the Academy 
 lity of the Principal Prefervative Remedies againfl the of Sciences. The fame Academy alfo divided the prize 
 Hydrophobia is examined. This pamphlet is infcribed for their queftion concerning the inclination of the pla- 
 
 to Sir George Baker, and deferves to be unlverfally 
 read. 
 
 In the year following Dr Berkenhout publifhed his 
 Symptomatology; a book which is too unlverfally known 
 to require any recommendation. 
 
 At the beginning of the year 1788 he publifhed a 
 work, intitled, Firfl Lines of the Theory and PraSice of 
 Philofophical Chemiflry, which he dedicated to Mr Eden, 
 now Lord Auckland, who had been one of the com- 
 mlffioners whom he accompanied to America. 
 
 Thefe, we believe, are the Doftor's principal publi- 
 cations In the line of his proftfTion ; but he wrote on 
 many other fubjefts with equal ability. His tranflation 
 of Count TeJJin's Letters, which was his firfl publication, 
 and dedicated to the prefent king when prince of Wales, 
 evinces his knowledge of the Swedifh language, and 
 ftiews him to have been a good poet. His EJfay on 
 Ways and Means, proves him to have been better ac 
 
 netary orbits, between our autlrar and his fon Daniel. 
 See Bernoulli (Daniel), Encycl. 
 
 John Bernoulli was a member of mofl of the acade- 
 mies of Europe, and received as a foreign afTocIate of 
 that of Paris in 1 699. After a long life fpent in con- 
 llant fludy and improvement of all the branches of the 
 mathematics, he died full of honours, the ifl of January 
 1748, in the 8ifl year of his age. Of five fons which 
 he had, three purfued the fame fciences with himfelf. 
 One of thefe died before him ; the two others, Nicolas 
 and Daniel, he lived to fee become eminent, and much 
 refpe£ted in the fame fciences. 
 
 The writings of this great man were difperfed through- 
 the periodical memoirs of feveral academics, as well as 
 in many feparate treatifcs. And the whole of them 
 were carefully coUedled and publifhed at Laufanne and 
 Geneva, 1742, in 4 vols 4to. He was of undoubted 
 eminence; but even In fcience he was a haily man, and 
 
 quaintcd with theVyflem of taxation than mofl other certainly envious of the fame of Newton. 
 
 men who have written on the fubjeft. His biographi- BETELGUESE, a fixed ftar of the firfl magni- 
 
 cal powers appear in his Biographia Literaria ; and in tudc, in the right fhoulder of Orion. 
 
 - . "^ - w- . r r,- , rr ■, ,.. BEZOUT ( Stephen ), a Celebrated FrcHch mathe- 
 
 matician, member of the Academies of Sciences and the 
 Marine, and examiner of the guards of the marine and 
 of the eleves of artillery, was born at Nemours the 
 ^ifl of March 1730. In the courfe of his ftudies he 
 met with fome books of geometry, which gave him a 
 talle for that fcience ; and the Eloges of Fontenellcj 
 
 all his works are filfKcIent proofs of his clafTical learn 
 ing, and that the Italian, French, German, and Dutch 
 lano-uages, were familiar to him. He pofTefTed likewife 
 a very confiderable degree of mathematical fcience, which 
 he acquired in the courfe of his military fludies; and to 
 thofe more folid attainments he is fald to have added no 
 fmall flcill in the fine arts of painting and mufic. This 
 
 eminent man, who, for the variety and promptitude of fhewed him the honours attendant on talents and the 
 
 lOTC
 
 B I N 
 
 love of the fciences. His father in vain oppofcd the 
 ftrong attachment of young- Bezout to the mathemati- 
 cal fciences. April S. 1758, he was named aJjoint- 
 mechanician in the French Academy of Sciences ; ha- 
 ving before that fent them two ingenious memoirs on 
 the integral calculus, and given other proofs of his pro- 
 ficiency in matl\emat!cs. In 1763, he was named to 
 the new office of examiner to the marine, and appoint- 
 ed to compofe a fyllem of mathematics for their ufe ; 
 and in 1 76S, on the death of M. Camus, he fucceeded 
 as examiner of the artillery eleves. 
 
 Bezont fixed his attention more particularly to the 
 refolution of algebraic equations ; and lie firil found out 
 the fulution of a particular clafs of equations of all de- 
 grees. This method, different from all former ones, 
 was general for the cubic and biquadratic equations, and 
 jnlt became particular only at thofe of the 5th degree. 
 Upon this work our author laboured from 1762 till 
 1779, when he publilhed it. He compofed two couvfes 
 of mathematics; the one for the marine, t lie other for the 
 artillery. The foundation of thefe two works was the 
 fame; the applications only being differtnt, according to 
 the two different objefts: thefe courfes have everywhere 
 been held in great ellimation. In hisofficeof examiner he 
 difcharged the duties with great attention, care, and 
 tendeniefs. A trait of his juflice and zeal is remarkable 
 in the following inilance: During an examination which 
 he held at Toulon, he was told that two of the pupils 
 could not be prefent, being confined by the fmall-pox : 
 he himfelf had never had that difeafe, and he was great- 
 ly afraid of it ; but as he knew that if he did not fee 
 thefe two young men, it would much impede their im- 
 provement, he ventured to their hed-fides to examine 
 them, and was happy to find them fo deferving of the 
 hazard into which he put himfelf for their benefit. 
 
 [ 77 ] 
 
 B L A 
 
 Black. 
 
 has one of its terms an impoflible or an imaginary quan- Binomial 
 tity ; asa -f- v' — i. 
 
 Bis'OMijL Curvi', is a curve whofe ordinate is ex- 1 
 prefled by a binomial quantity, as the curve whole or- 
 dinate is .\-» X * -f- ir7'\\ Stirling, Method. Dirt", p. jH. 
 BiNOMi.lL Line, or SurJ, is that in which at leall one 
 of tlie parts ii a furd. Euclid, in the tenth book of his 
 Elements, enumerates fix kinds of binomial lines or furds> 
 viz. 
 
 Firfl. binomial J -f- ^/ 5, 
 
 2d binomial v' 1 8 -f- 4, 
 
 3d binomial »/ 2^ -\- it/ 18, 
 
 4th binomi.u 4 + •v/ 3, 
 
 jth binomi;il /^Z 6 -f- 2, 
 
 6th binomial y' 6 -f v^ 2. 
 Binomial Theorem. .See Algfbra, Chrip. 
 
 Seft. iii. [Encycl. Vol. I.) ; and Inf.nlli StRiss, 
 
 VI 1, 
 
 (Vol. 
 
 XVII.) The reader who wiflies for a fuller account of 
 this famous theorem, may find it in Dr Hutton's Ma- 
 thematical Trafts, Vol. I. 
 
 BIRD CATCHiijG, is an art which, as it is praftifed 
 by means of bird lime, nets, decoys, &c. has been fufli- 
 ciently explained in the Encyclopxdia. But there is 
 another method of catching birds alive, by means of a 
 fufee or m-ujhet, which was invented by M. Vaillant du- 
 ring his travels in Africa, and is fufficiently ingenious 
 to dcferve a place here. It is as follows : 
 
 Put a fmaller or larger quantity of powder into youi 
 fufee according as circumflances may require. Imme- 
 diately above the powder place the end of a candle of 
 fufficient thicknefs, ramming it well down ; and then 
 fill the barrel with water up to the mouth. When at 
 a proper diflance you fire a mudiet thus loaded at a 
 bird, you will only^un it by watering and moillening 
 its feathers; and if you be alert, you may cafily lay 
 
 Mr Bezout lived in this employment for feveral years, hold of it before it have time to fpoil its plumage by 
 beloved of his family and friends, and refpeded by all, fluttering. Our author admits, that in his firft attempts 
 enjoying the fruit? and the credit of his labours. But the he often put too much powder, or too thick a piece of 
 
 trouble and fatigues of his offices, with fomeptrfonal cha 
 grilles, had reduced his ftrength and conilitution ; lie was 
 attacked by a malignant fever, of which he died Sept. 27. 
 1783, in the 54th year of his age, regretted by his fa- 
 mily, his friends, the young Undents, and by all his ac- 
 quaintance in general. 
 
 The books publiflied by him were : i. Courfe of 
 Mathematics for the ufe of the Marine, with a Trea- 
 tife on Navigation, 6 vols in 8vo, Paris, i 764. 2. Courfe 
 of Mathematics for the Corps of Artillery, 4 vols in 
 8vo, 1770. 3. General Theory of Algebraic Equa- 
 tions, 1779. 
 
 His papers printed in the volumes of the Memoirs of 
 the ."Academy ot Sciences are: i. On curves, whofe 
 verification depends on a given quantity, in the volume 
 for 1758. 2. On feveral clafles of equations that admit 
 of an algebraic folution, 1762. 7,. Firil volume of a 
 courfe of mathematics, 1764. 4. On certain equations, 
 &c. 1764. 5. General refolution of all equations, 1765. 
 
 6. Second volume of a courfe of mathematics, 1765. 
 
 7. Third volume of the fame, 1766. 8. Fourth volume 
 of the fame, 1767. 9. Intergration of differentials, &c. 
 vol. 3. Sav. Etr. 10. Experiments on cold, 1777. 
 
 BINOMIAL, a quantity confiding of two terms or 
 members, conncfted by either of the figns -}- and — . 
 See Algebra, def. 9. Encycl. 
 
 Impojfible or Imaginary JBiuoMiJi, is a binonaial-which 
 
 powaer, or too tlucK a pn 
 candle into his fufee, or fired at too (hort a diftance ; 
 aiifl when any one of thefe miftakes was committed, he 
 generally found the candle entire in the animal's hi^ly ; 
 but after a Ihort apprenticefhip he acquired fufficient 
 (]<ill to adjuft matters fo as that the water impelled by 
 the powder went diredly to the mark, whilll the tallow 
 being lighter than the water fell fhort of it. If this 
 method be indeed practicable (for not being fportfinen 
 we h.ive not made trial of it), it may on many occafions 
 aid the refearches of the ornithologlft. 
 
 BiKDS-NeJ/s, ill cookery. See Encycl. and Cap and 
 BuTTO.'J in this Suppl. 
 
 BLACK (Jofeph, M. D.), who has been ftyled the 
 father of pniiimatic chemiftry, and who, in that de- 
 partment of fcience, had certainly no fuperior, was born 
 at Bourdeaux in France, in the year 1728. His father 
 was a native of Ireland, but went to Bourdeaux to carry 
 on the bufinefs of a wine-merchant ; though with what 
 fuccefs be carried it on we have not learned. Where 
 young Black received his claffical education we know 
 not ; but at an early period of life he was fent to the 
 Univerfity of Glafgow, and ftrongly recommended to 
 Dr CuUen, who advifed him to ftudy phyfic, and under- 
 took, with that ardour which charafterifed his mind, to 
 render him every fervice in his power. 
 
 At that period CuUen read leftures on chemiftry in 
 the College of Glafgow witU great and deferved ap- 
 
 plaufe J
 
 E'.aclt. 
 
 B L A L 78 
 
 plaufe; and Black becoming one of his favourite pupils, 
 was allowed the tree ufe ot liis laboratory, and aflilled 
 him in his experiments ; by which means lie acquired a 
 decided tafte for this branch of natural philofophy. In 
 I 754 he took the degree of doftor of phyfic in the uni- 
 verfity of Edinburgh, where he had ftudied for fome 
 time ; and tlie choice which he made in regard to the 
 fubjedt of his inaugural dilfcitatioii gave a priiot of his 
 attaclmient to chemical purlults. It was He humore uc'nlo 
 .1 cib'is orio tt niagnejia alba. The principles of the doc- 
 trine whick he brought forward in this thefis he after- 
 wards fully explained in a paper read the next year be- 
 fore a fociety in Edinburgh, and publiflicd in the fe- 
 ron<^ \i.t\vimti oi EJfnys Phyfical and Literary, 1756; con- 
 taining experiments on magnefia alba, quick-liine, and 
 L'lkaline fubftances. In this paper, by an ingenious and 
 philofophical feries of refearches, he evidently proved 
 tiie exiftence of an aerial fluid, which he called^.vc</ air, 
 the prefence of which gave mildnefs, and its abfence 
 caufticiiv, to alkalies ai.d calcareous earths. This noble 
 difcovery certainly paved the way to all that Important 
 knowledge refpeding aerial bodies which has done fo 
 much honour to the names of a Cavendifli, a Priellley, 
 and a Lavoifier, and which have made chemical philo- 
 fophy aflfume an entirely new form. 
 
 In the year 1756, on the removal of Dr Cullen to 
 Edinburgh, Dr Black became profeflor of medicine and 
 ieclurer on chemiftry in the univerlity of Glafgow. Next 
 year he enriched the fcience of chemiftry with the cu- 
 rious doftrine of latent heat, in which he explained, in 
 \vhat has been hitherto reckoned a clear and fatisfado- 
 rv manner, the connection of heat with fluidity, the 
 phenomena of freezing and boiling, and the manner in 
 which they afFedl the theiTnometer. Thefe difcoveries, 
 the refult of great natural fagacity and experimental 
 iliill, ceitainly laid the foundation of all thofe impor- 
 tant fatls relating to this part of chemiftry which were 
 aiterwards brought to light by feveral of the mcft emi- 
 nent philofophers of the prefent period, and would alone 
 be fufficient to give celebrity to the name of Bhck. 
 His reputation indeed was now raifed fo high, that a 
 vacancy having taken place in the chemical chair of 
 Edinburgh, by the removal of Dr Cullen, in J 765, to 
 another department, Dr Black was looked up to as the 
 only man capable of fuftaining, in this branch of icience, 
 the fuperiority which that celebrated fchool of medi- 
 cine had acquired in all others. He was therefore elect- 
 ed to fucceed Cullen, and for many years difcharged 
 the duties of the office with univerfal approbation, being 
 much admired for the care, perfpicuity, and elegance, 
 with which he communicated inftruftion in his ledif ures, 
 and his neatnefs and accuracy in performing experi- 
 ments. Very complete manulcript copies of his lec- 
 tures were taken by many of his Undents, particularly 
 in the early part of his teaching, when they contained 
 a great deal of matter then little known to the chemi- 
 cal world ; and thefe copies, read with avidity by the 
 lovers of this fcience, have greatly contributed to fe- 
 cure to him the honour of thofe difcoveries, and that 
 original mode of reafoning, which he fcarcely ever made 
 public in any other form. His leftures have lately been 
 revifed by his friend Dr Robifon of Edinburgh ; and, 
 enriched with many valuable notes by that genuine phi- 
 lofopher, are now in the prefs, and will fpeedily be pub- 
 lilhed. 
 
 ] B L A 
 
 Aftei his election to the chemical chair, Dr Black B!a:k, 
 pubiilhed nothing but a paper on the Effeft of Boiling "'^''"'"'^^ 
 upon Water, in difpoling it to freeze more readily, print- 
 ed In t!ie fixty-fifth volume of the Philofophical Tranf- 
 aClions for 1774 ; and an Analyfis of the Water of fome 
 Hot Springs in Iceland, in the Philofiiphlcal Tranfac- 
 tions of Edinburgh for 1791. The latter contains fome 
 obfervations, highly intereiting to the chemKl, on the 
 formation of the fillceous ftone depohted by thefe won- 
 derful fprings ; and has long been confidercd as a model 
 of neatnefs and accuracy in the analyfis of nuneral wa- 
 ters. I" wo of his letters on chemical fubjefts have been 
 publlflied by Crell and Lavoifier. 
 
 Dr Black was long a ftrenuous oppofer of the new 
 theories in chemiftry ; but he at length became an avc w- 
 ed convert to the principles of the French chemifts, and 
 did not hefitatc to make amends by his applaufe for his 
 former oppofition. He never dllUnguiflied himfelf as a 
 practical phylician. His manners were fimple, his tem- 
 per cold and referved, and his habits of life adapted to 
 his own convenience. He was never married; and died 
 fuddenly, in his fixty-fecond year, on the 6th of De- 
 cember 1799, ^'^ health having been in a declining ftate 
 for fome time before. He was a member of the Royal 
 Societies of London and Edinburgh, and of the Impe- 
 rial Academy of Sciences at St Ptterfburgh ; and by 
 the intereft of Lavoifier he was chofen one of the eight 
 foreign members of the Academy of Sciences of Paris, 
 when that academy was Royal, and when a phllofophcr 
 of Britain could be a member of it without incurring 
 difgrace. 
 
 By thofe who knew Dr Black intimately, and are 
 capable of forming an ellimate of the powers of his 
 mind, he is believed to have been capable of becoming 
 in chemiftry what Newton was in mechanical philofo- 
 phy ; but an unconquerable indolence, though it could 
 not prevent him fi cm doing his duty as profeflor, re- 
 ftrained him not only from employing, as he might have 
 done, his admirable talents in enlarging the boundaries 
 of fcience, but even from aflerting his claim to dilco- 
 veries which were certainly his. Of thefe we hope to 
 have fome account from his friend the editor of his 
 ledlures. 
 
 BLACKLOCK (Dr Thomas) deferves, on fo many 
 accounts, to have the principal incidents of his life re- 
 corded in this work, that to omit fuch an article from our 
 lift of biographical Iketches would be unpardonable ne- 
 gligence. We cannot, however, propofe to write of 
 him any thing which has not been written before, by 
 an author who has repeatedly appeared before the pub- 
 lic, and on each appearance has gained poffeffion of the 
 public heart. We fliall therefore content ourfelves with 
 inferting in this place a ftiort abridgment of the elegant 
 account of the life and writings of Dr Blacklock, which 
 was prefixed to that edition of his works which was 
 pubiilhed in 1793 ; and if we thus lelfen our own la- 
 bour, we are confcious that we ftiall at the fame time 
 increafe the pleafure of our readers. 
 
 Thomas Blacklock was in 1721 born at Anan, in 
 the county of Dumfries in Scotland, but his parents 
 were natives of the bordering county of Cumberland ; 
 fo that, though a native of Scotland, his defcent was 
 Englifti His father was a bricklayer, and his mother 
 the daughter of a confiderable dealer in cattle. Both 
 were refpeftable in their characters, and pofleiTed, tho' 
 
 moving
 
 B L A [ 
 
 ilaUIor't. moviDg in an humble fpliere, a confiderable degree of 
 ^""V~~^ knowledge and urbanity. Their fon was not quite fix 
 months old when he loft his eye-fight in the fniall-pox, 
 which rendered hitn as complete a ftranger to the vi- 
 filile world as if he had been blind from the hour of his 
 birth. It rendered him likewile incapable of learning 
 any of the mechanical arts ; and therefore his father 
 kept him at home, and with the afilftance of fome friends 
 foftered that inclination which, at a very early period, 
 he fhewed for books. This was done by reading to 
 him iirft the fimple fort of publications which are com- 
 monly put into the hands of children, and then feveral 
 of our bell authors, fuch as Milton, Spencer, Prior, 
 Pope, and Addifon. His companions, whom his early 
 gentlenefs and kindnefs of difpohtion, as well as their 
 compafiion for his misfortune, ftrongly attached to him, 
 \v€re very alTiduous in their good offices, in reading to 
 inftruft and amuie him. By their affillance he acquired 
 fome knowledge of the Latin tongue, but he never was 
 at a grammar-lchool till at a more advanced period of 
 life. Poetry was even then his favourite reading ; and 
 he found an enthufiallic delight in the works of the beft 
 Englifh poets, and in thofe of his countryman Allan 
 Ramfay. Even at an age fo early as twelve he began 
 to write poems, one of which is prelerved in the collec- 
 tion that was publifhed after his death, and is not per- 
 haps inferior to any of the premature compofitions of 
 boys affifted by the beft education, which are oidy re- 
 called into notice by the future fame of their authors. 
 He had attained the age of nineteen when his father 
 was killed by the accidental fall of a malt-kiln belong, 
 ing to his fon-in-Iavv. This lofs, heavy to any one at 
 that early age, would have been, however, to a young 
 man pofleffing the ordinary means of fupport, and the 
 ordinary advantages of education, comparatively light ; 
 but to him — thus fuddenly deprived of that fupport on 
 which his youth had leaned — deftitute almoft of every 
 refource which induftry affords to thofe who have the 
 blefiings of iight — with a body feeble and delicate from 
 nature, and a mind congenially fufceptible — it was not 
 furpriling that this blow was doubly fevere, and threw 
 on his fpirits that deipondent gloom to which he then 
 gave way in the following pathetic lines, and which 
 fometimes overclouded them in the fubfeq^uent period uf 
 his life : 
 
 " Dejefting profpeft ! foon the haplefs liour 
 
 " May come ; perhaps this moment it impends, 
 
 " Which drives roe forth to penury and cold, 
 
 " Naked, and beat by all the ftorms of heav'n, 
 
 " Friendlefs and guidelefs to explore my way ; 
 
 " Till on cold earth this poor iinfhelter'd head 
 
 " Reclining, vainly from the ruthlefs blaft 
 
 *' Refpite 1 beg, and in the fhock expire." 
 
 He lived with his mother for about a year after his 
 father's death, and began to be diftinguiihed as a young 
 man of uncommon parts and genius. Thefe were at 
 that time unaffifted by learning ; the circumftances of 
 his family afPoi ding him no better education than the 
 fmattering of Latin which his companions had taught 
 him, and the perufal and recolleftion of the few Englifh 
 authors which they, or bis father in the intervals ot his 
 profefGonal labours, had read to him. . Poetry, however, 
 though it attains its higheft perfeftion in a cultivated 
 foil, grows perhaps as luxuriantly in a wild one. To 
 
 79 ] B L A 
 
 poetry, as v.-e have before mentioned, he was devoted Bhcklocl. 
 from his earlieft days ; and about this time feveral of^~— v~— ' 
 his poetical productions began to be handed about, 
 which confiderably enlarged the circle of his friends 
 and ac([uaintance. Some of his compofitions being 
 fliewn to Dr Stevenfon, an eminent phylician of Edin- 
 burgh, who was jfccider.tally at Dumfries on a profcf- 
 fionalvifit, that gentleman formed the Ijenevolent defigii 
 of carrying him to the Scotch metropolis, and giving to 
 his natural endowments the afTiilance of a cknical edu- 
 cation. He came to Edinburgh in the year 1741, and 
 was enrolled a ftudent of divinity in the univerlity there, 
 though at that time without any particular view of en- 
 tering into the church. In that univerlity he continued 
 his fludies under the patronage of Dr Stevenfon till the 
 year 1745, when he retired to Dumfries, and refided in 
 the houfe of Mr M'Murdo, who had married his lifter, 
 during the whole time of the civil war, which then ra- 
 ged in the country, and particularly difturbed the tran- 
 quillity of the metropolis. AV'hen peace was reflorcd 
 to the nation, he returned to the univerlity, and pur- 
 fued his ftudics for fix years longer. During this lail 
 refidence in Edinburgii, he obtained, among other lite- 
 rary acquaintance, that of the celebrated David Humf, 
 who attached himfelf warmly to Mr Blacklock's inte, 
 refts, and was afterwards particularly ufcful to him in 
 the publication of the 410 edition of his Poems, which 
 came out by fubfcription in London in the year I7j6. 
 Previoufly to this, two editions in 8vo had been pub- 
 lifhed at Edinburgh, the firft in 1746, and the feeond 
 in 1754. 
 
 In the courfe of his education at Edinburgh, he ac- 
 quired a proficiency in the learned languages, and be- 
 came more a niatler of the French tongue than was then 
 common in that city. For this laft acquiiJtion he was 
 chiefly indebted to the focial intercourfe to which he 
 had the good fortune to be admitted in the houfe of 
 Provoft Alexander, who had married a native of France. 
 At the univerlity he attained a knowledge of the va- 
 rious branches of philofophy and theology, to which his 
 courfe of ftudy naturally led, and acquired at the fame 
 time a confiderable fund of learning and information in 
 thofe various departments of fcicnce and belles lettres, 
 from which his want of light did not abfolutely pre- 
 clude Ixim. 
 
 In 1757, he began a courfe of ftudy, with a view to 
 give lectures in oratory to young gentlemen intended 
 for the bar or the pulpit. On this occaiion he wrote 
 to Mr Hume, informed him of his plan, and requefled 
 his affiftince in the profecution of it. But Mr Hurr.e 
 doubting the probability of its fuccefs, he abandoned 
 the projedf j and then, for the firft time, adopted ttie 
 decided intention of going into the church of Scotland. 
 After applying clofely for a confiderable time to the 
 ftudy of theology, he paffed the ufual trials in the pref- 
 bytery of Dumfries, and was by that prefhytery licenfcd 
 a preacher of the gofpel in the year 1759. -^^ ^ preach- 
 er he obtained high reputation, and was fond of com- 
 pofmg fermons, of which he has left fome volumes in 
 manufcript, as alfo a Treitife on Morals. 
 
 The tenor of his occupations, as well as the bent of 
 his mind and difpofitions, during this period of his life, 
 will appear in the following plain and iinftiidied account, 
 contained in a letter from a gentleman, who v/as then 
 his moft intimate and conftant companion, the Rev. Mr 
 
 JamefoQt,
 
 B L A [ 
 
 BldcWock. Jamefon, formeily n-.iiiifLr of the Epifcopal chapel at 
 '—-^r—~ Dumfries, afterwards of the Enghfli congregation at 
 Dantzic, and who lately refided, and perhaps yet relidcs, 
 at Newcallle upon Tyne. 
 
 "His manner of life (fays that gentleman) was fo 
 uniform, that the hlftory of it during one day, or one 
 week, is tlie hiftory of it during the feven years that 
 our perfonal intercourfe lafted. Reading, mufic, walk- 
 ing, converfing, and difputing on various topics, in 
 theology, ethics, &c. employed almoft every hour of our 
 time. It was pleafant to hear him engaged in a dif- 
 pute, for no man could keep his temper better than he 
 always did on fuch occailons. I have known him fre- 
 quently v.;ry warmly engaged for hours together, but 
 never couM obferve one angry word to fall from him. 
 Whatever his antagonift might fay, he always kept his 
 temper. ' Semper piirntus et rcjdlere fine pcrt'macta, ct 
 refiHiftne iracumlia.' He was, however, extremely fen- 
 fible to what he thought ill ufage, and equally fo whe- 
 ther it regarded hinifelf or his friends. But his retent- 
 mcnt was always confined to a few fatirical verfes, which 
 were generally burnt foon after. 
 
 " I have frequently admired with what readinefs and 
 rapidity he could fometimes make verfes. I have known 
 him diclate from thirty to forty verfes, and by no means 
 bad ones, as fall as I could write them; but the mo 
 nient he was at a lofs for a rhime or a verfe to his 
 liking, he ftopt altogether, and could very feldom he 
 induced to finifli what he had begun with fo much ar- 
 dour." 
 
 This account fuffieiently marks that eager fcnfibility, 
 challened at the fame time with uncommon gentlenefs of 
 temper, which charaflerifed Dr Blacklock, and which 
 indeed it was impofiible to be at all in his company 
 without perceiving. In the fcience of mind, this is 
 that divifion of it which perhaps one would peculiarly 
 > appropriate to poetry, at kaft to all thofe lighter fpe- 
 cies which rather depend on quicknefs of feeling, and 
 the ready conception of pleafnig images, than on the 
 happy arrangement of parts, or the (Icilful conflrudtlon 
 of a whole, which are effential to the higher departments 
 of the poetical art. The firft kind of talent is like 
 thofe warm and light foils which produce their annual 
 crops in fuch abundance ; the lalt, like that deeper 
 and firmer mould on which the roots of eternal foreds 
 are fixed. Of the firit we liave feen many happy in- 
 ftances in that fex vvhicli is fuppofed lefs capable of 
 ftudy or thought ; from the lall is drawn that mafcu- 
 line fublimity of genius which could build an Iliad or a 
 Paradife l.oft. 
 
 Dr Blacklock could never diftate till he ftood up ; 
 and as his bllndnefs made walking about without af- 
 fiftance inconvenient or dangerous to him, he fell infen- 
 fibly into a vibratory fort of motion of his body, which 
 incrcafed as he warmed vvitli his fubjcft, and was plea- 
 fed with the conceptions of his uiind. This motion at 
 lad became habitual to him; and though he could fome- 
 times reftrain it when on ceremony, or on any public 
 appearance, fuch as preaching, he felt a certain uncafi- 
 nefs from the effort, and always returned to it when he 
 could without impropriety. This appearance he de- 
 fcribes in a fliort poem, in which he gives a ludicrous 
 pifture of himfelf ; a pifture indeed, of which, though 
 the outlines are true, the general effeft is greatly over- 
 charged. Though his features were hurt by the dif- 
 
 So ] B L A 
 
 cafe whitli deprived him of fight, there was a ccitain B!aAI(.,It. 
 placid exprefiion in his countenance, which marked the ' " v~— ' 
 benevolence of his heart, and was calculated to procure 
 to him individual attachments and general regard. 
 
 la 1762 he married Mifs liarah Johnfton, daughter 
 of Mr Jofeph Johnfton iurgeon in Dumfries ; a con- 
 nexion which formed the great folace and bkrTuig of 
 his future life, and gave him, with all the tendernels of 
 a wife, all the zealous care of a guardian and a friend. 
 This event took place a few days before his being or- 
 dained minifter of the town and parifh of Kircudbright, 
 in confequence of a prefcntation from the crown, ob- 
 tained for him by the earl of Selkirk, a benevolent no- 
 bleman, whom Mr Blacklock's fituation and genius had 
 interefted in his behalf But the inhabitants of the 
 parifh, whether from that violent averfion to patronage, 
 which was then fo univerfal in the fouthern parts of 
 Scotland, from fome political dlfputes which at that 
 time fubfiftcd between them and his noble patron, or 
 from thofe prejudices which fome of them might natu- 
 rally enough entertain againft a paftor deprived of fight, 
 or perhaps from all thefe caufes united, were fo extreme- 
 ly difinclincd to receive him as their minifter, that after 
 a legal difpute of nearly two years, it was thought ex- 
 pedient by his friends, as it had always been wlftied by 
 Inmfelf, to compromife the matter, by refigning his 
 right to the living, and accepting a moderate aimuity 
 in its ftead. With this flender provifion he removed in 
 I 764 to Edinburgh ; and to make up by his induftry 
 a more comfortable and decent fubfiftence, he adopted 
 the plan of receiving a certain number of young gentle- 
 men as boarders into his houfe, whofe ftudics in langua- 
 ges and philofophy he might, if necelfary, aflift. In 
 this fituation he continued till the year 1787, when he 
 found his time of life and ilate of health required a de- 
 gree of quiet and repofe, which induced him to difcon- 
 tinue the receiving of boarders. In 1 767 the degree of 
 doftor in divinity was conferred on him by the univerii- 
 ty and Marifchal college of Aberdeen. 
 
 In the occupation which he thus exercifed for fo ma- 
 ny years of his life, no teacher was perhaps ever more 
 agreeable to his pupils, nor mafter of a family to its in- 
 mates, than Dr Blacklock. The gentlenefs of his man- 
 ners, the benignity of his difpofition, and that warm in- 
 terell in the happinefs of others which led him fo con- 
 ftantly to promote it, were qualities that could not fail 
 to procure him the love and regard of the young people 
 committed to his charge ; while the foclety, which 
 efteem and refpeft for his charafter and his genius often 
 afTembled at his houfe, afforded them an advantage rare- 
 ly to be found in eftablifirments of a fimilar kind. 
 
 In this mixed foclety he appeared to forget the pri- 
 vation of fight, and the melancholy which it might at 
 other times produce in his mind. He entered, wit'h the 
 cheerful playfulnefs of a young man, into all the fpright- 
 ly narrative, the fportful fancy, and the humorous jeil 
 that rofe around him. Next to converfation, mufic was 
 perhaps the fource of his greateft delight ; for he not 
 only reliftied it highly, but was himfelf a tolerable per- 
 former on feveral inftruments, particularly the flute. 
 He generally carried in bis pocket a [mzW JlageoUt, on 
 which he played his favourite tunes ; and was not dif- 
 pleafed when aflced in company to play or to fing them ; 
 a natural feeling fur a blind man, who thus adds a fcene 
 to the drama of his fociety. 
 
 Of
 
 B L A 
 
 [ 8 
 
 cllock. Of the liappinefs of others, however, we are incom- 
 ->t~~' petent judges. Companionfhip and fympathy bring forth 
 thofe gay coloms of mirth and cheerfnlnefs which they 
 put on for a while, to cover perhaps that fadntfs which 
 we have no opportunity of witnefling. Of a bh'nd 
 man's condition we are particularly liable to form a mil- 
 taken eftimate ; we give him credit for all thofe gleams 
 of delight which fociety affords him, without placing 
 to their full account thofe dreary moments of darkfome 
 folitude to which the fufpenfion of that fociety condemns 
 him. Dr Blacklock had from nature a conilitution de- 
 licate and nervous, and his mind, as is almoft always the 
 cafe, was in a great degree fubjeft to the indifpofition 
 of his body. He frequently complained of a lownefs 
 and depreffion of Ipirits, which neither the attentions of 
 his friends, nor the unceafing care of a moll affetf ionate 
 wife, were able entirely to remove. The imagination 
 we are fo apt to envy and admire ferves but to irritate 
 this diforder of the mind ; and that fancy in whofe cre- 
 ation we fo much delight, can draw, from fources un- 
 known to common men, fubjefts of difgull, difquietude, 
 and affliftion. Some of his later poems exprefs a cha- 
 grin, though not of an ungentle fort, at the fuppofed 
 failure of his imaginative powers, or at the faflidiouf- 
 nefs of modern times, which he defpaired to pleafe. 
 
 " Such were his efforts, fuch his cold reward, 
 
 •' Whom once thy partial tongue. pronounc'd a bard ; 
 
 " Excurfive, on the gentle gales of fpring, 
 
 " He rov'd, whilll favour imp'd his timid wing; 
 
 *' Exhaufted genius now no more infpircs, 
 
 " But mourns abortive hopes, and faded fires; 
 
 " The fliort-liv'd wreath, which once his temples grac'd, 
 
 " Fades at the fickly breath of fqueamifh talle ; 
 
 •' Whilll darker days his fainting flames immure 
 
 " In cheerlcfs gloom and winter premature." 
 
 Thefe lines are, however, no proof of " exhaufted 
 genius," or " faded fires." " Abortive hopes," indeed, 
 muft be the lot of all who, like Dr Blacklock, reach 
 the period of old age. In early youth the heart of 
 every one is a poet ; it creates a fcene of imagined hap- 
 pinefs and delufive hopes ; it clothes the world in the 
 bright colours of its own fancy ; it refines what is coarfe, 
 it exalts what is mean ; it fees nothing but diiintcrcll- 
 edneis in frieudfhip ; it promiles eternal fidelity in love. 
 Even on the dillrctfes of its fitnation it can throw a 
 certain romantic (liade of melancholy that leaves a man 
 fad, but does not make him unhappy. But at a more 
 advanced age, "the fairy vilions fade," and he fuffers 
 moft deeply who has indulged tlrem the moft. 
 
 About the time that thefe verfes were written, Dr 
 Blacklock was, for the firft time, afflifled with what to 
 him mull have been peculiarly diftrefsful. He became 
 occafionally fubjeft to deafnefs, which, though he fel- 
 dom felt it in any great degree, was fufScient, in his fi- 
 tuation, to whom the fenfe of hearing was almoft the 
 » only channel of communication with the external world, 
 
 to caufe very lively uneafmefs. Amidll thefe indifpo- 
 fitions of body, however, and difquietudes of mind, the 
 gentlenefs of his temper never forfook him, and he felt 
 all that refignation and confidence in the Supreme Be- 
 ing which his earlieft and his lateft life equally acknow- 
 ledged. In fummer 1791 he was feized with a feverifh 
 diforder, which at firft feemed of a flight, and never rofe 
 to a very violent kind j but a frame fo little robuft as 
 
 SuppL, Vol. I. Part I. 
 
 I ] B L A 
 
 his was not able to refift it, and after about a week's 
 illnefs it carried him off on the 7th day of July 1791. '' 
 His wife furvlves him, to feel, amidft the heavy afflic- 
 tion of his lofs, that melancholy confolation which is 
 derived from the remembrance of his virtues. 
 
 The writings of Dr Blacklock confiftc-d principally 
 of poems, which were publiflicd in 410 in the year 1 792 ; 
 and to that edition was added. An FJfay on the Eriuca- 
 tion of the Blmd, tranjlaled from the Ficnch of M. Hauy. 
 But befides his avowed works, we have reafon to be- 
 lieve that he was the author of many articles in the fe- 
 cond edition of the Encyclopedia Britannica, though we 
 cannot fay with certainty what thofe articles were. If 
 our memory does not deceive us, we have been inform- 
 ed that the preface to that edition was furnilhed by 
 him ; and we have elfewhere attributed to him, on the 
 beft authority, the article Blind, and the Notes to the 
 article Music : but he undoubtedly contributed much 
 more to the work, and was one of the principal guides 
 of the proprietors. 
 
 BLAIR (Dr Hugh), was born in Edinburgh, on 
 the 7th day of April 1718. His father, John Blair, a 
 refpedable merchant in that city, was a defcendant of 
 the ancient family of Blair in Airlhire, and grandfon of 
 the famous Mr Robert Blair minifter of St Andrew's, 
 chaplain to Charles I. and one of the moft zealous and 
 diftinguiflied clergymen of the period in which he li- 
 ved. This worthy man, though firmly attached to the 
 caufe of freedom, and to the Prefbyterian form of 
 church government, and though aftively engaged in all 
 the meafures adopted for their fupport ; yet, by his 
 fteady, temperate conduc't, commanded the refpeft even 
 of his opponents. In preference to all the other eccle- 
 fiaftical leaders of the covenanting patty, he was feleA- 
 ed by the king himfelf to fill an office which, from the 
 circumftances of the time, gave frequent accefs to the 
 royal perfon ; " becaufe (faid his majefty) that man is 
 pious, prudent, learned, and of a meek and moderate 
 calm temper." His talents feem to have defcended as 
 an inheritance to his pofterity. For of the two fona 
 who furvived him, David, liie cldeft, was a clergyman 
 of eniinence in Edinburgh, father to Mr Robert Blair 
 mir.ifter of Athclftonford, the celebrated author of the 
 poem intitled The Grave ; and grandfather to his ma- 
 jefty's fdicitor general for Scotland, whofe mafculine 
 eloquence and profound knowledge of law have, in the 
 public eftimation, placed him indifputably at the head 
 of the Scottiih bar. From his youngell fon Hugh, 
 who engaged in bufinefs as a merchant, and had the 
 honour to fill a high ftation in the magiftracy of Edin- 
 burgh, fprung tiic learned clergyman who is the fub- 
 jeCl of this narrative. 
 
 The views of Dr Blair, from his earlieft youth, were 
 turned towards the charch ; and his education received 
 a fuitable diredion. After the ufual grammatical courfe 
 at fchool, he entered the humanity clal's in the univer- 
 fity of Edinburgh in Oftober 1730, and fpent eleven 
 years at that celebrated feminary, alTiduoufly employ- 
 ed in the literary and fcientific ftudics prefcribed by 
 the church of Scotland to all who are to become can- 
 didates for her licence to preach the gofpel. During 
 this important period, he was diftinguiftied among his 
 companions both for diligence and proficiency ; and ob- 
 tained from the profcfTors under whom he ftudied re- 
 peated teflimonics of approbation. One of them de- 
 li fervei 
 
 Bla
 
 B L A [8. 
 
 Blair, {erves to be mentioned particularly, bfcaufe, in his own 
 ""~v^— ' opinion, it determined tlic bent of bis genius towards 
 polite literature. An effay "'?■ '■»" "">-""• or, On the Beau- 
 tiful, written by him when a Undent of logic in the ufual 
 courle of academical cxercilef, had the good fortune to 
 attraft the notice of profeiT.ir Stevenfon, and, with cir- 
 cumilances honourable to the author, was appointed to 
 be read in pnblic at the conclufion of the term or fei- 
 fion. This mark of diftinftion made a deep impreflion 
 on his mind; and the elfay which merited it he ever 
 after recoUefled with partial afFeftion, and preferved to 
 the day of his death as the firft earned of his fame. 
 
 At this time Dr Blair commenced a method of fludy 
 which contributed much to the accuracy and extent of 
 his knowledge, and which he continued to pradife oc- 
 cafionally even after his reputation was fully eftabliflied. 
 It confifted in making abftrafts of the moil important 
 works which he read, and in digefting them according 
 to the train of his own thoughts. Hiftory, in_ parti- 
 cular, he refolved to ftudy in this manner ; and, in con- 
 cert with fome of his youthful aflbciates, he conilrufted a 
 very comprehenfive fcheme of chronological tables, for 
 receiving into its proper place every important faft that 
 fhould occur. The fcheme devifed by this young ftu- 
 dent for his own private life was afterwards improved, 
 filled up, and given to the public by his learned friend 
 Dr John Blair, prebendary of Weilminller, in his va- 
 luable work, " The Chronology and Hiftory of the 
 World." 
 
 Tn the year 1739, Dr Blair took his degree of A.M. 
 On that occafion he printed and defended a thefis, De 
 Fundamenlis et Obligatione Lcgis Nature, which contains 
 a ihort but mafterly difcuffion of this important fubjeft, 
 and exhibits in elegant Latin an outline of the moral 
 principles which have been fince more fully unfolded 
 and illuftrated in his Sermons. 
 
 The univerfity of Edinburgh, about this period, 
 numbered among her pupils many young men who 
 were foon to make a diftinguifhed figure in the civil, 
 the ecclefiaftical, and the literary hiftory of their coun- 
 try. With moft of them Dr Blair entered into habits 
 of intimate connedion, which no future competition or 
 iealoufy occurred to interrupt, which held them united 
 "through life in their views of public good, and which 
 had the moft beneficial influence on their own improve- 
 ment, .on the progrefs of elegance and tafte among 
 their contemporaries, and on the general interefts of the 
 community to which they belonged. _ 
 
 On the'completion of his academical courfe, he un- 
 derwent the cuftomary trials before the prefbytery of 
 Edinburgh, and received from that venerable body a 
 licence to preach the Gofpel on the ziftofOdober 
 I 741. His public life now commenced with very fa- 
 vourable profpeds. The reputation which he brought 
 from the univerfity was fully juftified by his firft ap- 
 pearances in the pulpit ; and, in a few months, the fame 
 of his eloquence procured for him a prefentation to the 
 parilh of Coleflie in Fife, where he was ordained to the 
 office of the holy miniftry onthe 2 ^d of September 1742. 
 But he was not permitted to remain long in this rural 
 retreat. A vacancy in the fecoud charge of the Canon- 
 gate, a fuburb of Edinburgh, furniihed to his friends an 
 opportunity of recalling him to a ftation more fuited to 
 his talents. And, though one of the moft popular and 
 eloquent clergymen in the church wras placed in com- 
 
 i ] B L A 
 
 petition with him, a threat majority of the eledors de- 
 cided in favour of this young orator, and reftored him 
 in July 1743 to the bounds of his native city. 
 
 In this Ihnion Dr Blair continued eleven years, dif. 
 charging with great fidelity and fuccefs the various du- 
 ties of the paftoral oflice. His dlfcourfes from the pul- 
 pit in particular attraded univerlal admiration. They 
 were computed with uncommon care ; and, occupying 
 a middle place between the dry metaphyfical difcuffion 
 of one clals of preachers, and the loofe incoherent de- 
 clamation of another, they blended together, in the 
 happleft manner, the light of argument with the warmth 
 of exhortation, and exhibited captivating fpecimens of 
 what had hitherto been rarely heard in Scotland, the 
 pohihed, well-compaded, and regular didadic oration. 
 
 In confequeuce of a call from the town-council and 
 general-feffion of Edinburgh, he was tranflated from the 
 Canongate to Lady Ycfter's, one of the city churches, 
 on the nth of Odober 17J4: and on the 15th day of 
 Jure 1758, he was promoted to the High Church of 
 Edinburgh, the moft important ecclefiaftical charge in 
 Scotland. To this charge he was railed at the re- 
 queft of the Lords of Council and Seffion, and of the 
 other diilinguirtu'd official charaders who have their 
 feats in that church. And the uniform prudence, abi- 
 lity, and fuccefs, which, for a period of more that forty 
 years, accompanied all his minifterial labours in that 
 confpicuous and difficult ftation, fufficiently evince the 
 wifdom of their choice. 
 
 Hitherto his attention feems to have been devoted al- 
 moft exclnfively to the attainment of profeffional excel- 
 lence, and to the regular difcharge of his parochial du- 
 ties. No produdion of his pen had yet been given to 
 the world by himfelf, except two fermons preached on 
 particular occafions ; fome tranftations, in verfe, of paf- 
 fages of Scripture for the pfalmody of the church; and 
 a few articles in the Edinburgh Review ; a publica- 
 tion begun in 1751;, and conduded for a fliort time by 
 fome of the ablell men in the kingdom. But ftanding 
 as he now did at the head of his profeffion, and releafed 
 by the labour of former years from the drudgery of 
 vieekly preparation for the pulpit, he began to think 
 ferioufly on a plan for teaching to others that art which 
 had contributed fo much to the eftablifhment of his 
 own fame. With this view, he communicated to his 
 friends a fcheme of ledures on compofition ; and ha- 
 ving obtained the approbation of the univerfity, he be- 
 gan to read them in the college on the nth of Decem- 
 ber 1759. To this undertaking he brought all the 
 qualifications requifite for executing it well; and along 
 with them a weight of reputation, which could not fail 
 to give effed to the leftbns he fhould deliver. For, be- 
 fides the teftimony given to his talents by his fucceffive 
 promotions in the church, the univerfity of St Andrew's, 
 moved chiefly by the merit of his eloquence, had in 
 June 1757 conferred on him the degree of D. D. a li- 
 terary honour which at that time was very rare in Scot- 
 land. Accordingly his firft courfe of ledures was well 
 attended, and received with great applaufe. The pa- 
 trons of the univerfity, convinced that they would form 
 a valuable addition to the fyftem of education, agreed in 
 the following fummer to inftitute a rhetorical clafs, un- 
 der his diredion, as a permanent part of their academi- 
 cal eftablifhment : and on the 7th of April 1762, his 
 Majefty was gracioufly pleafcd " to ered and endow a 
 
 pro. 
 
 B!i-r
 
 B L A 
 
 [ 83 ] 
 
 B L A 
 
 profefToifhip of rlietonc and belles lettres I'n the uiiiver- 
 ■* iky of Edinburgh ; and to appoint Dr Blair, in confi- 
 deratiiHi of liis approved qualifications, regius profeffor 
 thereof, with a falary of L.70." The leftures which he 
 read as profefTor of rhetoric, he publifhed in 1783, when 
 he retired from the labours of the office ; and the ge- 
 neral voice of the public has pronounced them to be a 
 moft judicious, elegant, and comprehenfive fyllem of 
 rules for forming the ilyle and cultivating the tafte of 
 youth. 
 
 About the time in which he was occupied in laying 
 the foundations of this ufeful inftitution, he had an op- 
 portunity of conferring another important obligation on 
 the literary world, by the part which he afted in ref- 
 cuing from oblivion the poems of Ofiian. It was by 
 the iolicitation of Dr Blair and Mr John Home, that 
 Mr Macpherfon was induced to publiih his Fragments of 
 Ancient Poetry ; and their patronage was of efTential fer- 
 viee in procuring the fubfcription which enabled him 
 to undertake his tour through the Highlands for col- 
 lefting the materials of Fingal, and of thofe other de- 
 lightful produftions which bear the name of Offian. 
 To thefe produdlions Dr Blair applied the tell of ge- 
 nuine criticifm ; and foon after their publication gave 
 an ellimate of their merits in a Di/ferlatlon, which, for 
 beauty of language, dehcacy of taile, and acutenefs of 
 critical inveftigation, has few parallels. It was printed 
 in 1 763, and fpread the reputation of its author through- 
 out Europe. 
 
 The great objefts of his literary ambition being now 
 attained, his talents were for many years confecrated 
 folely to the important and peculiar employments of his 
 llation. It was not till the year 1777 that he could be 
 induced to favour the woild with a volume of the Ser- 
 mons which had fo long furnifhed inftrucSlion and de- 
 light to his own congregation. But this volume being 
 well received, the public approbation encouraged him 
 to pioceed : four other volumes followed at different 
 intervals, the laft of which was publifhed after his 
 death ; and all of them experienced a degree of fuc- 
 ceis of which few publications can boaft. They circu- 
 lated rapidly and widely wherever the Englifli tongue 
 extends ; they were foon tranflated into almoft all the 
 languages of Europe ; and his prefent Majeily, with 
 that wife attention to the interefts of religion and lite- 
 rature which diftinguiihes his reign, was gracioufly plea- 
 fed to judge them worthy of a public reward. By a 
 royal mandate to the Exchequer in Scotland, dated Ju- 
 ly 25th 1780, a penfion of L.200 a-year was conferred 
 on their author, which continued unaltered till his 
 death. 
 
 In that department of his profeffional duty which re- 
 garded the government of the church, Dr Blair was 
 lleadily attached to the caufe of moderation. From 
 diffidence, and perhaps from a certain degree of inap- 
 titude for extemporary fpeaking, he took a Icfs public 
 part in the conteils of ecclefialUcal politics than fome 
 of his contemporaries ; and, from the fame caufes, he 
 never would confent to become moderator of the Ge- 
 neral Aflembly of the Church of Scotland. But his 
 influence among his brethren was extenfive: his opinion, 
 guided by that found uprightncfs of judgment, which 
 formed the predominant feature of his intcllcdual cha- 
 rafter, had been always held in high refpett by the 
 friends with whom he afted ; and, for many of the lali 
 
 years of his life, it was received by them almoft as a 
 law. The great leading principle in whicli tlicv ^r- ^ 
 dially concurred with him, and which directed all thrir 
 meafures, was to preferve the church, on the one fide, 
 from a Oavilh, corrupting dcpendance on the civil power; 
 and, on the other, from a greater infufion of democra- 
 tical influence than is compatible with good order, and 
 the eftablilhed conlb'tution of the country. 
 
 The reputation which he acquired in the difcharge 
 of his public duties, was well fuilained by the great re- 
 fpedability of his private character. Deriving from 
 family aflbciations a ftrong fenfe of clerical decoium, 
 feeling on his heart deep impreffions of religious and 
 moral obligation, and guided in his intercourfe with 
 the world by the fame corrctl and delicate tade which 
 appeared in his writings, be was eminently dillinguilhcd 
 through life by the prudence, purity, and dignilied pro- 
 priety of his conduCl. His mind, by conftitntion and 
 culture, was admirably formed for enjoying happinefs. 
 Well balanced in itfelf by the nice proportion and ad- 
 juft;ment of its faculties, it did not incline him to any 
 of thofe eccentricities, either of opinion or of aftion, 
 which are too often the lot of genius : — free from all 
 tinClure of envy, it delighted cordially in the profperity 
 and fame of his companions : fenfible to the ellimation 
 in which he himfelf was held, it difpofed him to dv.'ell 
 at times on the thought of his fuccefs with a fatisfac- 
 tion which he did not affeCl to conceal : inacceifible 
 ahke to gloomy and to peevifli impreffions, it was aU 
 ways mailer of its own movements, and ready, in an 
 uncommon degree, to take an aifive and pleafing in- 
 terell in every thing, whether important or trifling, that 
 happened to become for the moment the objeft of his 
 attention. This habit of mind, tempered with the 
 moil unfufpefting timplicity, and united to eminent 
 talents and inflexible integrity, while it fecured to the 
 laft his own reliih of life, was wonderfully calculated to 
 endear him to his friends, and to render him an invalu- 
 able member of any fociety to which he belonged. 
 Accordingly there have been few men more univerfally 
 refpedted by thofe who knew him, more fincerely 
 eileemed in the circle of his acq\iaintance, or more ten- 
 derly belo-Ked by thofe who enjoyed the bkffing of his 
 private and domeflic connexion. 
 
 In April 1748, he married his coufin Katharine 
 Bannatine, daugluer of the Rev. James Bannatine, one 
 of tlie miniilers of Edinburgh. By her he Had a fon 
 who died in infancy, and a daughter who lived to her 
 twenty-firft year, the ])ridc of her parents, and adorned 
 with all the accomplifliments that became her age and 
 fex. Mrs Blair herfelf, a woman of great good fenfe 
 and fpirit, was alfo taken from him a few years before 
 his death, after fhe had Ihared with the tenderell aff'cc- 
 tion in all his fortunes, and contributed near half a cen- 
 tury to his happinefs and comfort. 
 
 Dr Blair had been naturally of a feeble conftitution 
 of body ; but as he grew up his confl.itution acquired 
 greater tirmnefs and vigour. Though liable to occa- 
 fional attacks from I'ome of the fliarpelt and molt pain- 
 ful dileafes that afiliCf the human frame, he enjoyed a 
 general ftate of good health ; aud, through habitual 
 cheerfulnefs, temperance, and tare, furvived the ufual 
 term of human life. — For fome years he had felt him- 
 felf unequal to the fatigue of inllrufting his very large 
 congregation from the pulpit ; and, under the inipreffion 
 L 2 which 
 
 Bh
 
 Bhir, 
 Bleaching. 
 
 B L E [ 84 ] B L E 
 
 which this feeling produced, he has been heard at times air rufhes out forcibly; the receiver mud be quickly Bl'-'^etiing: 
 to fay with a iigh, " thiit be was left almoll the laft of flopped, and another applied. Thus many receivers *"~~v-~" 
 
 * Blair', 
 SermonSy 
 vol. V. 
 
 his contemporaries." Yet he continued to the end in 
 the regular diicharge of all his other official duties, and 
 particularly in giving advice to the afflicted, who, from 
 diifercnt quarters of the kingdom, folicited his corre- 
 fpondence. His laft fummer was devoted to the pre- 
 paration of the laft volume of Ins fermous ; and, in the 
 courfe of it, he exhibited a vigour of underftandiug and 
 capacity of exertion equal to that of his bcft days. Ho 
 
 may be filled with the dephlogifticated muriatic acid ; 
 but it is neceffary to place the retort in fuch a manner 
 that the drops which rife into its neck may be able to 
 fall back. The water fcrves to retain the vapours of 
 the acid. " I ule (fays he) many receivers, that I may 
 not be obliged to repeat a limilar dillillation for every 
 experiment. It is not proper to employ large ones, 
 becaufe every time they are opened a great part of the 
 
 began the winter pleafed with himfclf on account of acid is diffipated in the air. What I fubmitted to ex- 
 
 tlie completion of this work ; and his friends were flat- 
 tered with the hope that he might live to enjoy the ac- 
 celfion of emolument and fame which he expected it 
 woidd bring. But the feeds of a mortal difeafe were 
 lurking unperceived within him. On the 24th of De- 
 cember i8?o, he complained of a pain in his bowels, 
 which,, during that and the following day, gave him but 
 little unealinefs ; and he received as ufual the vifits of 
 his friends. On the afternoon of the 26th, the lymp- 
 toms became violent and alarming : — he felt that he 
 was approaching the end of his appointed courfe : and 
 retaining to the laft moment the full poffeflion of his 
 mental faculties, he expired on the morning of the 27th, 
 with the conipofure aad hope which become a Chriftian 
 paftor. 
 
 The lamentation for his death was univerfal and deep 
 through the city which he had fo long inftruCled and 
 adorned. Its magiftratcs, participating in tlie general 
 grief, appointed his church to be put in mourning ; and 
 his colleague In It, Dr Finlayfon, from whom this ac- 
 count of his life Is borrowed*, preached his funeral 
 fermon. In which his charafter Is drawn In a mafterly 
 manner, though with the almoft unavoidable partiality 
 of friendftiip. 
 
 If we, who know Dr Blair only In his writings, 
 might prefume to eftimate his Intelleftual character, we 
 (hould fay that he poffeflVd a found judgment rather 
 than what could be called a vigorous mind ; that he 
 had more tafte than genius ; and that he taught fuc- 
 cefsfuUy, as far as It can be taught, the art of poetry, 
 though he could not himfclf have been a poet. His 
 moral character was amiable and refpeftable, though he 
 feems, even from a hint dropt by his biographer, to 
 have been in a flight degree tinftured with vanity. 
 But this was furely a venial weaknefs ; for where is the 
 
 aminatlon with this dephlogifticated muriatic acid was 
 placed In the neck of the receiver, which I had ftopped. 
 The cork was turned yellow as by aquafortis. Paper 
 tinged with turnfol became almoft white; all red, blue, 
 and yellow flowers, as alfo green planes, turned yellow 
 in a fhort time, and the water in the receiver was chan- 
 ged into pure but weak muriatic acid. Neither al- 
 kalis nor acids were able to reftore the colours of the 
 flowers, or of the plants." 
 
 M. Berthollet, In 1785, proved that this acid was 
 compofed of muriatic acid combined with oxygen ; and 
 that when It had deprived vegetable matters of their co- 
 lour, It was reduced to the ftate of common muriatic 
 acid ; that is, it had loft the oxygen with which it was j 
 united. Tills oxygen had combined with the colour- Its applica. 
 Ing particles of the vegetable matter, and had rendered ''<>" '<^ 
 them colourlefs. After making thcfe obfervations. It "*""f'E' 
 occurred to him that the oxy-murlatic acid might pro- 
 duce the fame efFeft upon thofe particles which give 
 colour to thread and cloth, and which it is the objedt of 
 bleaching to deftroy. "At firft (fays he) I made ufe .4/hi. A 
 of water highly Impregnated with this acid ; and 1 rt- Cl>im. II. 
 newed It when it was exhaufted, until the thread or '5 • 
 cloth appeared white ; but I foon perceived that they 
 were confiderably weakened, and that they were en- 
 tirely lofing their folldlty. I then weakened the liquor 
 a little, and I fucceeded In bleaching cloth without da- 
 maging it. But it fpeedily became yellow by keeping, 
 efpecially if ft wi^ warmed, or paffed through an al- 
 kaline ley. I r«lefted upon the circumftances of com- 
 mon bleaching, and I endeavoured to Imitate its pro- 
 cefs, becaufe I thought the oxygenated muriatic acid 
 might aft in the fame manner ns the expofiiion of the 
 cloth in the meadows, which alone does not futlice, but 
 which appears only to difpofe the colouring parts of 
 
 head that would be wholly unaffefted by the fumes of the cloth to be dlffolved by the alkali of the ley. 1 ex- 
 
 Difcovei7 
 cf the oty. 
 muriatic 
 aciJ. 
 
 incenle burnt before it for fifty years ? 
 
 BLEACHING. Since the article Bkathing In the 
 Encvclopasdia was written, very great Improvements 
 have been introduced into the art. Of thele improve- 
 m.ents we fliall proceed to give an account. 
 
 Mr Scheele of Sweden difcovered the oxy-muriatic 
 acid, or dephlogifticated muriatic acid, as he called it, 
 about the year 1774, and foon after obferved Its effefts 
 
 amined dew, not only that which falls trom the atmo- 
 fphere, but alfo that which comes from the nocturnal 
 tranfpiration of plants ; and I obferved that both of 
 them were Impregnated with oxygen, fufBciently to de- 
 ftroy the colour of paper flightly tinged with turnfol. 
 
 " I therefore employed leys, and the aftion of oxyge- 
 nated muriatic acid, alternately, and I then obtained a 
 permanent white ; and as, at the finifliing of the com- 
 
 on vegetable colours. His method of procuring It was mon bleaching, the cloth Is pafled through four milk, 
 
 as follows : In a fand-bath Is to be placed a glafs re- or through fulphuric acid diluted with a very large quan- 
 
 tort, in which muriatic acid has been poured upon man- tity of water, I alio tried paffing the cloth through a 
 
 ganefe ; to this fmall receivers are to be adapted capa- very dilute folutlon of fulphuric acid, and I obferved 
 
 ble of containing about twelve ounces each, into which that the white was thereby rendered more clear. As 
 
 is to be poured about two drachms of water, without foon as I made ufe of the leys intermediately, I found 
 
 any other lute than a flip of blotting-paper about the that it was not neceflary to employ a concentrated II- 
 
 neck of the retort. In about a quarter of an hour a quor, or to let the cloth, at every Immerfion, remain 
 
 yellow air is perceived in the receiver, which Is to be long therein : by this I avoided two Inconveniences, 
 
 taken off. If the paper has been properly applied, the which would hav€ rendered this proccfs impoflible to 
 
 be
 
 B L E [ 85 ] B L E 
 
 leiching. be praftifed in the large way. Tlie fufl is the fulfoca- ter ; for if the evaporation (hould take place, the fiil. Bleaching. 
 
 ■"V"" ting oJour of the hquor, which it would be very incon- phiiric atiJ, hecoiiiiiig thereby Lonctiitratcd, would cor- — ~v -' 
 venient, and even dangerous, to refpire for any length rode them. The cloths being then well waflied, rc- 
 of time, and which has difcouraged many perfons who quire only to be dried and drcfled in the ordinary man- 
 tried to ufe it ; the fecond is, the danger of weakening ner, accordiiig to their different forts. 
 
 the cloth. 1 now alfo left ol7 mixing any alkali with " It is of the utmoll importance to take care that the ' 
 
 the oxygenated muriatic acid, as I had praitifed in the water is not too ilrongly impregnated with the lulphu- 
 
 greatell part of my firft trials. ric acid. 
 
 "Tliis is nearly the ttate in which my experiments " The bleaching of cotton cloth Is much ealler and 
 
 were, when 1 made fome trials in the j>refence of the (horter ; two leys, or at mod three, and as many im- 
 
 celebrated Mr Watt. A iingle view fufficed for a phi- merfions in the bleaching liquor, are fnfficient for them, 
 
 lofopher wliofe genius has been exercifed fo long upon As they are bleached fo ealily, it is advantageous, when 
 
 the arts. In a (liort time Mr Watt wrote to me from 
 England, that even in the firll operation lie had bleach- 
 
 ed live hundred pieces of cloth at Mr Grigor'i 
 
 vho 
 
 there are flaxen, hempen, and cotton cloths, to be 
 bleached, to leferve for the cotton tlie litjuors which 
 have been previoufly weakened by the clotlis of flax or 
 has a large bleaching-ground at Glafgow, and who con- hemp; for it is economical to exhaull the li(|Uors as 
 tinues to make ufe of the new procefs. In the mean much as poffible, and thofe which are coufidcrably 
 time M. Bonjour, who had hitherto aflilled me in my weakened ftill fufKce for the cotton,, although they have 
 experiments, and who joins great fagacity to a moil ex- fcarcely any aiftion upon hemp or flax, 
 tended knowledge of chemillry, afl'ociated himfelf with " Thread, in the common way of bleaching, is attend- 
 
 Mr Conftant, at Valenciennes, in order to form an tfta- ed with a far greater number of difficulties than cloth; 
 blifliment in that city." becaufe of the immenfe number of furfaces which it is 
 
 M. Caillau made a great number of experiments at necefTary to prefent fucceilively to the ailion of the at- 
 Paris refpefting this new mode of bleaching ; but the mofphere. Some part of thefe difficulties occur in 
 greateft part of thefe experiments was made upon cot- bleaching with the oxygenated muriatic acid; neverthe- 
 ton, which is more eafy to bleach, and does not require lefs, in tlie end, it is more advantageous with 1 efpe<it to 
 leys lb often or fo ftrong as flax or hemp. He alfo thread than with refpeft to cloth. M. Welter has form- 
 went to St Quentin, to perform the operation upon the ed at Lifle, with two partners, an eftabliihment for 
 cloth of that country ; but he found that all the cloths, bleaching thread, with great fuccefs, and he has already 
 which he had bleached to the fatisfaftion of the manu- begun fome others. He has found that ten or twelve 
 fafturers, became again of a reddifh colour when they leys, and as many immerfions, are required for fom* 
 were expofed to a common ley, or even when they were forts of thread ; and, that the thread m.iy be furround- 
 Icft for fome time in a warchoufe. Several limilar com- ed with the liquor, it is neceffary to place it, quite 
 plaints were made by other perfons ; and M. Berthollet loofely, in a ba&et, which permits the liquor to pene- 
 himiclf had obferved the fame thing in his own experi- trate to all its furfaces; wlien the liquor is mucliweak- 
 ments. M. Bonjour, however, and M. Welter, aflirmed ened, it is Hill fit to be ufed for the bleaehino- of cot- 
 that the cloth which they had bleached preferved its co- ton. 
 
 lour perfectly. M. Berthollet foon found, that the im- " I had, in the beginning of my experiments, tried 
 
 perfeftion in his bleaching was owing to the manner in whether the vapour would not be preferable to the 
 which he had ufed the leys. " I had contented my- oxygenated muriatic acid in a liquid ftate, and I obfer- 
 fclf (fays he). In thofe trials on fmall pieces which 1 ved that It bleached with greater quicknefs; but, what- 
 made in my laboratory, to pour the hot alkaline folu- ever precautions 1 employed, it appeared to me that a 
 tion into a veffel where I placed the pieces : it there confidcrable lofs of It took place ; that thofe parts of 
 became cool very rapidly, and therefore did not aft the cloths which were the moll expofed to It were fub- 
 with fufficlent power ; but when I let thefe pieces re- jeft to be weakened ; and that it was more difficult to- 
 main in the liquor, which I kept nearly In a boiling obtain an equal whitenefs throughout, 
 heat during the fpace of two or three hours, they were " To prevent all the accidents which may refult 
 
 then no longer fubjeft to the above mentioned defedts : from the liquor afting with too great power, it is Im- 
 it was therefore merely the weaknefs of the leys which portant to have a means of meafuring its force. M. 
 had occafioned the accidents which were experienced by Dccroilllle thought of ufing, for that purpofe, a fohi- 
 Meffrs Caillau, Decroihlle, and myfelf. It is necefTary tion of Indigo In fulphunc acid. He takes one part of 
 that the colour of the cloth fhould not be changed by indigo, reduced Into fine powder, and eighteen parts of 
 the lall ley, and this is the fureft mark that the bleach- concentrated fulphuric acid ; this mixture is put Into a 
 ing is finlfhed ; neverthelefs, after this lafl aftlon of the matrafs, which Is kept, during fome hours. In a water- 
 ley, it Is proper to put the cloth, for a few moments, bath ; when the folutlon is finiflied, it Is diluted with a 
 in the bleaching liquor. thoufand parts of water. To try the power of the oxy- 
 
 " After this lafl immerfion, it Is necefTary to plunge genated muriatic acid, one meafure of this folutlon is 
 the cloth in four milk, or In water acidulated with ful- put into a graduated glafs tube, and fome of the liquor 
 phuric acid. I do not know the mofl convenient pro- is gradually added to It, until the colour of the indigo 
 portion of fulphuric acid; but It appeared to me that we Is dellroycd. We mufl flrfl determine how many mea- 
 might fnccefsfully, and without danger, make ufe of fures of a liquor, the goodnefs of which has been afcer- 
 one part, in weight, of this acid to fifty of water. We tained by experiments made upon cloth, are necefTary 
 mufl keep the cloths during about half an hour in this to deflroy the colour of one meafure of the folutlon of 
 liquor warmed ; after which it Is proper to fqueeze Indigo, and this number will ferve to eflimate the re- 
 them well, and plunge them direftly into common wa- fpedtive ftrength of all the liquors which it may be ne- 
 
 , cefTarjr
 
 B L E [86 
 
 I'Vachintr. ccITiry to compare with it. Mr Watt employs, in the 
 ^■~~^'~~^ fame manner, a folutioii of cochineal." 
 Method if ^^* Beithollet recommentled the following method 
 jirccuring of |)rocuring the oxy-miuiatic acid : " If we have good 
 tlie acid foioxide of mangancfc, formed in fmall crylhils, and con- 
 bleaching. (;,;p;,jg [,,,f little extraneous matter, the proportions of 
 the fnbllances to be fubmitted to dlftillation are the fol- 
 lowing : Six oimces of calx of manganefe reduced to 
 powder ; one pound of common fait, alfo reduced to 
 -powder ; twelve ounces of concentrated fulpluiric acid, 
 or oil of vitriol ; from ten to twelve ounces of water. 
 
 " When thefe materials are prepared, we muft care- 
 fully mix the oxide of manganefe with the common fait, 
 and introduce the mixture into the dillilling velfel pla- 
 ced upon a fand bath : we muft then pour upon it the 
 fnlpliuric acid, previoufly diluted (and of which the heat 
 occafioned by its mixture with water is diifipated), and 
 immediately apply to the mouth of the matrafs the tube 
 which is to conduft the gas into the intermediate vef- 
 fcl. — It mult not be forgot, that in this operation the 
 lutes require particular attention. 
 
 " The fize of the velfels (liould be fuch, that the dif- 
 tiUing matrafs may be about one-third empty ; and, for 
 the quantity above mentioned, tiie tub iliould hold loo 
 quarts of water ; there (liould alfo bean empty fpace 
 of about lo quarts, in order that when the gas lodges 
 ilfelf in the cavities intended to receive it, the water 
 rnay have a free fpace to rife in. 
 
 " Before the commencement of the operation, the 
 pneumatic tub muft be filled with water. The mix- 
 ture being made, the gas, which very foon begins to 
 difengage itfelf, drives out the atmofpherical air which 
 is in the apparatus ; when it is judged that the atmo- 
 fpheric air has pafl'cd into the cavities, it is to be drawn 
 off by means of a bent tube, which is to be introduced 
 fucceflively under each cavity : to drive out the water 
 which has entered into the tube, ihislall is to be forci- 
 bly blown into. The operation is then fuffered to go 
 on without fire until it is perceived that the bubbles 
 tome over but flovvly : then a little fire is to be applied, 
 winch is not to be haftijy increaled at the beginning, 
 but may be gradually augmented, io that at the end of 
 the operation the matter may be brought to a boiling 
 ftate. It is known to be nearly finifhed when the tube 
 l)y which the gas is difengaged, and the intermediate 
 vcffel, become liot. AVhen the gas is difengaged only 
 in a fmall quantity, the fire may be withdrawn ; and 
 ■when the diftilling veflel retains but a gentle warmth, it 
 is to be unluted, and warm water is to be poured upon 
 the rcfidue, that it may remain in folution, and thereby 
 be more eafily poured out. 
 
 " The operation is longer or ftiorter according to the 
 quantity of materials : with that above mentioned, it 
 (hould lall five or fix hours; it is proper not to hafleii 
 it, that a larger quantity of gas may be drawn oft". A 
 fingle perfon is able to manage feveral diftillations at the 
 fame time ; to each of which may be given much lar- 
 ger quantities of materials than thofe which have been 
 pointed out. 
 
 " The intermediate veflel by degrees becomes filled 
 with a liquor, which is pure, though weak, muriatic 
 acid ; neverthelefs, we may perform the operation fe- 
 veral times without extracting it : but when it is fup- 
 pofed that there is not fuificient empty fpace, this acid 
 ;s to be drawn off by means of a fyphon, aud, when 
 
 ] B L E 
 
 we have colleiSlcd a fufficient quantity of it, it may be Blesching 
 
 fubllitutcd for the mixture of vitriolic acid and com- """"V"— 
 
 mon fait in the operation we have defcribed, if we have 
 
 no other ufe to make of it. That there may pafs but 
 
 a fmall quautity of muriatic acid, not oxygenated, tiie 
 
 firft tube ought to form a right angle, or even an ob- 
 
 tu(e one, with the body matrals. 
 
 " During the operation, the agitator muft be from 
 time to time put in motion, to favour the abforption 
 of the gas by the water ; when it is finifhed, the liquor 
 is of a proper ftrength to ufe in bleaching; or- we may 
 put a Icfs quantity of water in the tub, and then di- 
 lute the liquor according to the proportion already men- 
 tioned. 
 
 " In this ftate of concentration, although the liquor 
 has a pretty llrong odour, it neverthelefs is not hurtful, 
 nor even very unpleafant, to thofe who ufe it : it is, 
 however, proper to conduft it into the troughs where 
 the cloths are placed by means of wooden canals, which 
 are to be coimefted with the faufet or tube which is at 
 the lower part of the tub." — The following is a de- 
 fcription of the apparatus: 
 
 A BCD is a reverberatory furnace, having, on a line pj^f^ yjj 
 with B, many fmall openings in its circumference, tofig. n. 
 ferve as chimneys; within which, upon a fand-bath n, is 
 placed a matrafs i, the neck of which ftands out above 
 the furnace, running through the opening D ; which is 
 to be clofed with clay. The mouth F, of the neck of 
 the matrafs, is clofed by a cork G, through the middle 
 of which pafles a tube H, which forms a communica- 
 tion between the infide of the matrafs I/, and the inter- 
 mediate veffel K, vfhere it alfo pafles through a cork I, 
 which clofes one of the three openings of that veffel. 
 The corks G and I ought to be prepared before-hand, 
 and well fitted to each end of the tifbe of communica- 
 tion H, which is to be fo difpofed that it may be fitted 
 in immediately after the mixture is made in the ma- 
 trafs. 
 
 The intermediate veffel K is about an eighth part 
 full of water ; into it is plunged the tube of fafety L, 
 to prevent danger from regurgitation. This tube ought 
 to be fo high, that the weight of the water which en- 
 ters into it, by the prcffure of the gas, may be great 
 enough to caufe the gas to pafs into the pneumatic tub 
 NOP, by the tube of communication M, which is 
 plunged therein, and reaches to the bottom, where it 
 is bent horizontally, fo that the gas may be emitted 
 under the firft of the three wooden, or (if they can be 
 procured) ftoneware, cavities, or receivers, which are 
 placed in the infide of the tub, one above the other. 
 O is a handle which ferves to turn the agitator E, the 
 movement of which facilitates the combination of the 
 gas with the water. P is a fpigot and faufet to draw 
 off the liquor. ^ 
 
 It is nrceffary to prepare the cloth by leaving it to Method c 
 foak for 2^ hours in water, or, which is better, in fome'^l^'"-'"''2 
 old ley. Afterwards it Ihould be fubmitted to the ac- 
 tion of one or two good leys; becaufe all the colouring' 
 part which may be extradled by the leys would elfe, 
 without any advantage, confume a part of that liquor, 
 which it is important to be as fparing of as poflible. 
 After this, the cloth is to be carefully wafhed ; then it 
 is to be placed in the troughs, without any part being 
 preffed or confined, in fuch a manner that it may be 
 thoroughly impregnated with the liquor which is to 
 
 run
 
 B L E 
 
 Bleaching, run tlicreon. The troup^^hs, as well as the tub, oupjht 
 
 -^-W—^ to be conilrufted withoiu iron ; for that metal, being 
 
 rulted by the oxygenated muriatic acid, would produce 
 
 iron moulds, which could not be taken out but by 
 
 means of fait of forrel. 
 
 The firft immerlion ought to be longer than the o- 
 thers ; it may be continued for three hours, after which 
 the cloth is to be taken out ; it is to be again fiib- 
 mitted to the aftion of ley, and then placed in a 
 trough, that freih liquor may be poured thereon : it is 
 fufficient that this immeriion, and the following ones, 
 continue half an hour. When the cloth is taken from 
 the trough, the liquor is to be wrung out, it is to be 
 again fubmitted to the ley, and afterwards to frefh im- 
 nierfions. The fame liquor may lerve until its ftrength 
 is exhaufted : when it is much weakened, there may be 
 fome freih liquor added to it. When the cloth ap- 
 pears white, except fome black threads and the lills, it 
 is to be impregnated with black foap, and then ftrong- 
 ly rubbed ; after which it is to be iubmittcd to the lall 
 
 [ 87 ] 
 
 B L E 
 
 Britain, and 13 now almolt univerfal among bleachers. Blcnchit/r. 
 
 A great many changes have been made in the proctfs ; ' v ' 
 
 one of the moll important of which is fubllituting lead 
 velTels for wooden ones, which, befides weakeniiig its 
 aftlou exceedingly, were very foon dellroved by the 
 acid. We believe, too, that the blvadiers very Gene- 
 rally add fome alkali to the acid, notwithdanding the 
 ilrong objections which Mr JLJerthoUet has made to that 
 manner of bleaching. 
 
 This method of bleaching has been found to anfwer 
 remarkably well: tlie only objedlion that has been made 
 to it is, tliat the cloth is apt to be weakened. And 
 this, no doubt, mull be the cafe, if care be not taken 
 to prevent the acid from being too much concentrated: 
 but we have little doubt that, with a fufficient decree 
 of caution, it will prove as fafe as any other whatever ; 
 and, in point of expedition, there cannot furely be any 
 comparifon drawn between the old mode of bleaching 
 and the new. 
 
 It remains for us now to confider whether the newT! cory of 
 
 ley and the lall immerfion. We cannot determine difcoveries in chemillry do not throw fome rays of light I'leaching. 
 
 what number of leys and immerfions may be neceflary, 
 becauie it varies according to the nature of the cloth : 
 ncverthlefs, the limits of this number are between four 
 and eight for linen or hempen cloths. 
 
 The manufafturers at Javelle, to whom M. Berthol- 
 let had communicated this procefs, foon after publifhed, 
 in different journals, that they had difcovered a parti- 
 cular liquor which had the property of bleaching cloth 
 by an immerfion of fome hours only. The change they 
 
 upon the theory of bleaching ; for it is only by per- 
 feiling the theory that we can advance with certainty 
 in our practical improvements. 
 
 It has been already obfcrved, in the article Bleach- 
 ing [EncycL), that cloth, alter being bleached, was a 
 good deal lighter than it had been before that opera- 
 tion : It follows, therefore, that it mult have been de- 
 prived of fomethlng during the bleaching. Cloth bleach- 
 ed by means of the oxy-muTiatic acid likewife under- 
 had made in the procefs, performed in their prefence, goes a lofs of weight ; lb that, in all probability, both 
 confilted in putting fome alkali into the water which modes acl in precifely the fame manner, 
 receives the gas ; this enables the liquor to become If raw linen or thread be boiled in a folution of cau« 
 
 much more concentrated, fo that it may be diluted flic alkali, properly diluted, it gives out fomething which 
 ■with feveral times its own q^uantity of water before it tinges the ley of a deep brown, and at the fame time 
 
 the alkali lofes its caullicity. If the huen be boiled in 
 another fimilar folution, it communicates the lame co- 
 lour, and even a third may be llightiy tinged ; but af- 
 ter this, alkalies, uidefs fo much concentrated as to in- 
 jure the texture of the cloth, have no effedt on it 
 whatever. If the linen be now plunged into oxy-mu- 
 riatic acid, properly prepared, and allowed to remaia 
 till it begins to become white, and then plunged into 
 an alkaline ley, the alkali lofes its caufticit), and af^ • 
 fumes the fame Jeep colour that the lirlt ley did. Here,. 
 tlicii, we have two alkaline folutions; the one faturated. 
 with colouring matter before the adlion of tiie oxy-mn- 
 riatic acid on the linen, the other after it. When theie 
 folutions are faturated with an acid, a yellow-coloured 
 precipitate is obtained, which u'hen dried alTumes the 
 appearance of a black powder. Piecilely the fame iub- 
 ftance is obtained from both folutions. This colouring 
 matter is almoft infoluble in wiier. Pure or cauftic 
 potafs dillblves about double its own weight of it; car- 
 bonat of potais not fo much. 
 
 Hence we fee the ufe of alkalies in bleaching. Tire, 
 colouring matter is not foluble in water, but part of it 
 is foluble in alkali. However, after the alkali has ex- 
 haulled all its power, the luieu is not white : colouring 
 matter therefore exifts in it, which alkalies cannot a£t 
 upon. But alter being plunged in oxy muiiatic acid, it. 
 alfo becomes foluble in acids. Here, then, is the ufe of 
 
 is ufed. 
 
 " Thefe are the proportions which yielded me (fays 
 Berthollet), a liquor fimilar to the pretended Javelle ley : 
 two ounces and a half of common fait, two ounces of 
 fulphuric acid, iix drachms of calx of manganefe, and, 
 in the veflel where the gas is to be concentrated, one 
 pound of water, and five ounces of potalh, which Ihould 
 be dilfolved in the water. The Javelle liquor has a 
 fomewhat reddiiii appearance, occaiioned by a fmall 
 quantity of manganefe, which either paifes in the dittil- 
 lation, becaufc an intermediate velTel is not ufed, or ex- 
 ifts in the potafli; mod kinds of which contain it, as I 
 have well convinced myielf. 
 
 " This liquor may be diluted with from ten to twelve 
 parts of water ; and, after this, it bleaches more fpeedi- 
 ly than the liquor itfelf ; but without fpeaking of the 
 imperfeftions of the method which is delcribed in the 
 publications from Javelle, and which can only fuffice 
 for cotton, we are not able to bleach near the fame 
 quantity of cloth with the oxygenated muriatic acid 
 combined in this manner with an alkali, as might be 
 bleached with the fame quantity ot that acid mixed 
 with water alone ; becaufe there is formed a portion of 
 that neutral fait which is known at prefent by the name 
 of oxygenated murlat of potais, and in which the oxy- 
 gen becomes concentrated. Now all the oxygen which 
 •nters into the compofition of this fait is rendered ufe- 
 
 lefs for bleaching ; becaufe the oxygenated muriat of that acid in bleaching — it communicates fomething to 
 potalh does not dellroy colours." the colouring matter which renders.it foluble in alkali. 
 
 This method of bleaching was very foon adopted iu This fomething, we have already feen, is oxvgen. It 
 
 follows, .,
 
 B L E [ 88 
 
 Dleaclilng. follows, therefore, that hefore the greater pnrt of the 
 ""—v™"' colouring matter of linen can be extradled by alkalies, 
 
 it muil be combined with oxygen. It is in producing 
 
 this combination that the ufe of the expofure to the 
 
 fun and air confills ; and it is becaufe the oxy-muriatic 
 
 acid prodncej it alnioft inftantaneoudy, that the new 
 
 mode of bleaching is fo much more expeditious thaa 
 
 the old. 
 
 If into the alkaline folution of the colourmg matter 
 lime-water be poured, there takes place a copious pre- 
 cipitate, which confjfts of the lime and colouring mat- 
 ter combined. Lime, therefore, has a ftronger affinity 
 for the colouring matter than alkali has ; and as the 
 compound of lime and the colouring matter is not very 
 foluble in water, lime-water might be ufed to deprive 
 ' the alkaline ley of the colouring matter which it has 
 imbibed ; after which it might be ufed again. Care, 
 however, mull be taken, that no lime-water remains in 
 the ley ; otherwife it might precipitate and fix the co- 
 louring matter on the linen, after which it would be ve- 
 6 ry difficult to remove it. 
 Nature of From an alkaline ley, faturated with the colouring 
 the colour- matter of linen yarn, Mr Kirwan, by means of muriatic 
 ing matter ^^;j^ precipitated the colouring matter. He found it to 
 "■ poffefs the following properties : When fuffered to dry 
 for fome time on a fiher, it afTumed a dark green co- 
 Ir:p, r,a«/lour, and felt fomewhat clammy like moift cla^. "I ^ eunn.mara .cip 
 
 ^7SP. took (fays he) a fmall portion of it, and added it to 60 ^.^^y ^^j-^, j^^^^^^j ^y ^ 
 
 rimes its weight of boiling water, but not a particle ot t;^,.,„„f„^^ \^y^ 
 it was diflblvcd. The remainder I dried in a fand heat; 
 it then alTumed a (hining black colour, became more 
 brittle, but internally remained of a greenifli yellow, 
 and weighed one ounce and a half. 
 
 «' By treating eight quarts more of the fatiirated ley 
 in the fame manner, I obtained 3 further quantity of 
 the greenilh depofite ; on wliich I made the following 
 experiments : _ 
 
 " lit, Having digelled a portion of it in reftified fpi- 
 rit of wine, it communicated to it a reddith hue, and 
 w^s in a great meafure difToIved : but by the attulion 
 ' of diftilled water the folution became milky, and a white 
 depofite was gradually formed ; the black matter diflol- 
 ved in the fame manner. 
 
 " 2dly, Neither the green nor the bkck matter was 
 foluble ill oil of turpentine or linfeed oil by a long-con- 
 tinued digeftion. 
 
 " jdly. The black matter being placed on a red hot 
 iron, burned with a yellow flame and a black fmoke, 
 leaving a coaly reliduum. 
 
 " 4thly, The green matter being put into the vitri- 
 olic, marine, and nitrous acids, communicated a brown- 
 i(h tinge to the two former, and a greenifh to the lat- 
 ter, but did not feem in the leall diminilhed. 
 
 " Hence it appears, that the matter extrafted by al- 
 kalies from linen yarn is a peculiar fort of refin, different 
 from pure refins only by its infolubility in effential oils, 
 and in this refpeft refembling laca. 1 now proceed to 
 examine the power of the different alkalies on tins fub- 
 » ftance. Eight grains of it being digeilcd in a folution 
 
 of cryftallized mineral alkah, faturated in the tempera- 
 ture of 60°, inftantly communicated to the folution a 
 dark brown colour; two meafures (each of which would 
 contain 11 pennyweights of water) did not entirely dif- 
 folve this fubilance. Two meafures of the mild vege- 
 table alkali diffolved the whole. 
 
 1 B L E II 
 
 •' One meafure of caullic mineral alkali, whofe fpeci- DleatWuj,! 
 fie gravity was 1,053, dilfolved nearly the whole, lea- ' \i —': 
 vin'T only a white rcfiduum. 
 
 " One meafure of caullic vegetable alkali, whofe fpe- 
 cific gravity was 1,039, diffolved the whole. 
 
 " One meafure of liver of lulphur, whofe fpecific gra- 
 vity was 1,170, diffolved the whyle. 
 
 " One meafure of caullic volatile alkali diffolved alio 
 a portion of this matter." 
 
 The colouring matter of cotton is much more foluble 
 in alkali than that of linen ; hence the greater facility 
 with which cotton is bleached. 
 
 From thefe obfervations, the great importance of al- 
 kalies in bleaching, and the neceffity of regulating the 
 ftrength, and afcertaining the purity, of the leys made 
 ufe of, mull be apparent. Manufaftureis, therefore, lie 
 under very great obligations to Mr Kirwan, who has 
 lately examined the alkaline matters ufed in bleaching 
 with his ufual accuracy and abilities. The refult ot his 
 experiments was as follows : 
 
 Tali/e of the quantity of mere aliali in 1 00 Avoirdupois Trijh Tranj , 
 pounds of the folloiuing fuhjiances. 'y^g- 
 
 One hundred lbs. Mineral Alkali. 
 
 Cryftallized foda - 20 lbs. 
 
 Sweet barilla - - - 24 
 
 Mealy's cunnamara kelp - 3'437 
 
 "xed air - 4i457 
 
 Strangford kelp - - 1,25 
 
 One hundred lbs. Vegetable Aliali, 
 
 Dantzic pearl a(h - 63>33 Ihs. 
 
 Clarke's refined afli - - 26,875 
 
 Caftiup - - 19)37^ 
 
 Common ravr Irifli weed-afh 1,666 
 
 Ditto nightly calcined 4,666 
 
 When linen is allowed to remain for fome time in 
 oxy-muriaric acid, it becomes white. It is evident, then, 
 that when the colouring matter of linen is faturated 
 with oxygen, it becomes colourlcfs : But linen bleach- 
 ed in this manner very loon becomes yellow, efpecially 
 when expofed to ht-at. Benhollct, to whofe ingenious 
 experiments and obfervations we are indebted for the 
 greater part of the above remarks, has given the fol. 
 lowing explanation of the caiile of this change : He 
 diftilled the colouring matter of linen, and obtained a 
 thick oil, a little ammonia, and /j'*^ of carbon remain, 
 ed behind. The oil contained carbon ; and he fuppo- 
 fed that carbonic acid gas, and carbonated hydrogen 
 gas, were difengaged. He concluded in confequence, 
 that one-third of this colouring matter was carbon. 
 The other ingredient in the oil was hydrogen ; for La- 
 voilier has proved that oil is compofed of oxygen and 
 hydrogen. The colouring matter of linen, then, is 
 compofed principally of carbon and hydrogen. 
 
 Oxygen combines with hydrogen at a lower tempe- 
 rature than it does with carbon ; for if a confiderable 
 quantity of oxy-muriatic acid be mixed with a folution 
 of fugar (a fubftance which confills chiefly of carbon 
 and hydrogen), and the liquor be evaporated, there 
 remains behind little elfe than carbon, the hydrogen 
 having combined with oxygen and formed water, which 
 had paffed off in the form of vapour. Now, whenever 
 a quantity of hydrogen is feparated from a body prin- 
 
 cipally
 
 B L E [ 89 ] B L E 
 
 Bleaching, cipally compofed of hydrogen and carbon, tliat body fpirit only wbich has been kept in veffels of glafs, of BlcacMngi 
 
 ^—^ ' afTumes a brown or yellow colour, becaufe the carbon tinned copper, or of pure tin. Leaden velTels are abfo-*""*— ~* 
 
 becomes predominant; and this colour becomes the lutely to bcrcjefted ; wooden vell'cls tinge the fpirit, 
 
 deeper the greater the proportion of the carbon is, coin- which gives the filk a degree of colour of confiderable 
 
 pared to that of the hydrogen ; and at lall, when no- permanency, and very inimical to the bleaching procefs, 
 thinw but carbon remains, it becomes quite black. The filk is wound off upon a reel, v.hile the cocons 
 
 It is probable, then, that when the oxy-rriuriatic a- are kept immerfcd in water almoll boiling. Upon tliis 
 
 cid renders linen white, a quantity of oxygen has com- 
 bined with the colouring particles; but that this oxy- 
 gen gradually enters into a combination with the hy- 
 drogen, arid forms water which palles oti; that then the 
 carbon becomes predominant, and the linen in conle- 
 
 * Ann Jr. qucnce afTuuies a yellow colour*. 
 Cbim.Vl. -pfjg {mx~e method does not fucceed in bleaching 
 
 * *- wool and filk which anfwers for linen and cotton. One 
 Bkaching would be difpofed to think that thefe fiibllances are 
 of wool and bleached rather by loling oxygen than by abforbing it. 
 filk- Wool, for inftance, is rendered white very quickly when 
 
 expofed to the fumes of fulphurous acid, which we 
 know has a ftrong affinity for oxygen, and foon fatu- 
 rates itfelf with it. But what pafles during the whiten- 
 ing of animal matters has never yet been properly 
 inquired into, though it would not only greatly eluci- 
 date bleaching, but i!yeing likewife, and throw much 
 light upon fome of the obfcureft parts of chemiftry. 
 A great improvement, however, has htely been made 
 by M. Baume in the manner of bleaching lilk. Of this 
 improvement we (hall proceed to give an account f. 
 Before the filk is wound off the cocons in which the 
 Cb' "xv'' '"'"^ vvorms are enclofed, it is neceffary to kill the in- 
 
 iSb. and a- fefts, otherwife they would in all probability eat thro' adhere, if wrung while wann for the purpofe of clearing 
 jridgcd in it and dcllroy it. This is commonly done by expofing it of the water. After inch improper treatment there 
 Nuhclfin s ji^g cocons, properly wrapped up, for two hours to the would be no other remedy than to foak it again in warm 
 ii°"frrm ^'^'"- "^ about 158 degrees of Fahrenheit in an oven ; water. 
 
 which lafl after which they are kept for a certain time in a mafs The apparatus for bleaching the filk confifts of a 
 
 [vehaveta-to preferve their heat, and efTeftually dcftroy fuch of (lone ware veflel, nearly of a conical form, capable of 
 lenourac-jijg infei^s as might have efcaped the power of the holding about 12 gallons, havhig a large opening at the 
 
 "3 'oven. The effett of this procefs is, that the filk is 
 New mode hardened, and is more difficult to wind off than before, 
 if whiten- Hence the produft of filk is lefs by one ninth part in 
 quantity, and inferior in quality to what might have 
 been obtained by winding off without this previous ba- 
 king. M. Baume, not only from thtfe views, but like- 
 wife becaufe the filk which has not been baked proves 
 fufceptible of a greater luftre, was induced to dcitroy 
 the chryfalis by Ipirit of wine. For this pui-pofe he 
 difpofes them in a wooden box in a ftratum fix inches 
 
 \ See the 
 memoir in 
 
 part ot the procefs M. ]53ume remarks, I. That the 
 dead cocons muil be feparated. Thefe are known by 
 the brown or black fpots on their furface. 2. That 
 wtllvvater, which on account of its clearnefs is almoll 
 iiniverially ulcd in the filk manufattories, moftly con- 
 tains nitre, and is extremely prejudicial to the bleaching 
 procefs. The prefence of nitrous acid gives a yellow 
 colour, which refills bleaching and even fcouring ; he 
 therefore recommends river-water. 3. In fome coun- 
 tries a fmall quantity of alum is ufed. Neither this nor 
 any other faline fubilance is of the lead advantage to 
 the colour, beauty, or quality of the filk. 
 
 At the four places ot contaft of the filk upon the 
 reel, all the threads (lick together. It is abfolulcly ne- 
 cefl'ary that this (hould be remedied. The method con- 
 fids in foaking the filk in a iufficlcnt quantity of v.drm 
 water, at about g~> degrees, for about two hours ; a'ter 
 which the threads are to he feparated by opening the 
 hanks upon a pin, and lightly rubbing the parts which 
 cohere. When the filk is dry, it is to be loofely folded 
 in its original form, and is ready for bleaching. 
 
 The filk while wet is foft, and part of its gummy 
 matter is in fuch a (late, that its threads would readily 
 
 iig filk. 
 
 one end, and a fmaller of about an inch diameter at 
 the other end. Common pottery cannot be ufed in 
 this operation, becaufe it Is foon rendered unferviceable 
 by the aflion of the muriatic acid, and the (lone-ware 
 it(clf is not very durable. This vcfTel mud be carefully 
 examined, to afcertain that it does not leak in the (lighted 
 degree ; after which the infide is to be rubbed with a 
 pumice-done, to clear it of afperities which might break 
 the threads. A cover of the fame material is to be fit- 
 ted on by grinding ; and the fmaller aperture, which \n 
 deep : upon each fquare foot half a pint of fpirit of the ule is the lowed, is to be clofed with a good cork, 
 
 wine is to be fprinkled with a fmall watering-pot made 
 for that purpofe. The liquid is to be equally didribu- 
 ted, but it is not neceffary that all the cocons (hould 
 be wetted. They are then to be mixed by hand. In 
 the next place another dratum is to be formed over the 
 fird, nearly of the fame depth, which is to be fprinkled 
 and treated as before. By this method of proceeding, 
 the box becomes filled, and mud then be covered, and 
 left for 24 hours; during which time they become fpon 
 
 in the middle of which is thrud a fmall glafs tube about 
 a quarter of an inch in diameter; this is likewife flop- 
 ped witli a cork, excepting at the time when it is requi- 
 red to draw off the liquid contents of the jar. A fmall 
 perforated falfe bottom is placed within the velTel, to 
 prevent this tube from being obdrufted. 
 
 Six pounds of yellow raw filk are to be difpofed in 
 the earthen pot ; upon this is to be poured a mixture, 
 previoufly made, of 48 pounds of fpirit of wine of the 
 
 taneoudy heated to about too degrees, and the vapour fpecific gravity .867, with 12 ounces of very pure ma- 
 
 of the fpirit of wine exerts itfelf with wonderful a<lftivi- rine acid, abfolutely exempt from all prefence of nitrous 
 
 ty. After this treatment they mud be fpread out to acid, and of the fpecific gravity 1.114. The pot is 
 
 dry, which happens in a (hort time, and is abfolutely then to be covered, and the whole left in digedion till 
 
 neceffary previous to winding off. the following day, or until the liquor, which at fird af- 
 
 The fpirit of wine to be ufed in this operation ought fumes a fine green colour, (hall begin to affume that of 
 
 to be of the fpecific gravity .847, at the temperature of a dullcy brown. 
 
 55 degrees. It is of the greateft importance to ufe that The acidulated fpirit is then to be drawn off, clean 
 
 SuppL. Vol. I. Part. I. M fpirit
 
 B L E 
 
 [ 90 ] 
 
 B L E 
 
 Bleathing;. fpirit of wine poured upon the filk, and drawn off re- 
 ''""" peatcdly until it paffes culourlcfs. The fdk is then fuf- 
 fered to drain without ilirring it. In this ftate it is 
 ready for a fecond infufion. 
 
 Forty-eight pounds of fpirit of wine, acidulated with 
 11 ounces of marine acid, are now to be poured on the 
 filk, and the whole fuliVrLd to remain for 24 hours or 
 longer, until the filk becomes perfcftly white. The 
 time required for this fecond infufion is commonly long- 
 er than for the firll : it fometimes amounts to two, 
 three, or even fix days, according to circumftances, par- 
 ticularly the temperature and the nature of the filk. 
 Silk which has been in the oven is in general more dif- 
 ficult to bleach. 
 
 When the filk has thus obtained its utmoft degree of 
 whitenefs, the acidulated fpirit is to be drawn oft into a 
 leparate velTel. This fluid is but (lightly coloured, and 
 may be ufed again in the firft infufion of other yellow 
 filk, with the addition of fix ounces more of marine 
 2cid. The receiving vefTtl is to be removed, and ano- 
 ther clean veffel fubftltuted in its phice. The filk is 
 then iprlnkled with clean fpirit, and occafionally prelled 
 down with the hand. As foon as the fpirit of wine 
 comes off abfolutely colourlefs, a third infufion is to be 
 made by pouring upon the filk 48 pounds of the pure 
 fpirit without acid, which is to remain till the follow- 
 ing day : it is then to be drawn off, and referved for 
 ivafhing other filk after the firft infufion. 
 
 After the filk has been left to drain, and affords no 
 more fpirit, it flill retains its own weight of that fluid. 
 This is recovered by fprlnkling the filk with a fmall 
 quantity of very clear river- water at a time. While 
 the water applies itfelf and fubfides along the filk, it 
 drives the fpirit of wine before It, fo that the firft por- 
 tions which flow fiom the tube are fcarcely dliriniihed 
 in fl.rength. The addition of water is to be continued 
 tintll nothing but mere water comes off below. 
 
 In this filuation the filk Is found to be well bleached, 
 but ftlU retains a portion of marine acid fufficient to 
 render it harfh to the touch, and after a time brittle. It 
 muft be waihed off with water. The beft method is to 
 put the filk loofcly into a coarfe woollen bag, which is 
 to be fecured loofely in another cloth like a fmall bed or 
 pillow, then placed in a balket, and left in a running 
 fiream for five or fix hours ; but where the convenience 
 of a ftream is wanting, the earthen pot containing the 
 filk Is to be covered with a cloth, and water pumped 
 through it for five or fix hours, or until that which if- 
 fnes from the lower aperture gives no red colour to the 
 tinfture of turnfol. At this period the lower opening 
 is to be clofed, and the veffcl filled with water, which 
 muft be changed once or twice in 24 hours. 
 
 Though the mineral acids are the mott powerful and 
 deftrufllve of all fallne fubftances, yet they may be ap- 
 plied to filk when diluted with fpirit of wine in very 
 <;onfiderable dofes. In trials made to afcertain the maxi- 
 mum, tvi*o ounces of marine acid were added to one 
 pound of fpirit of wine, without altering the filk. Two 
 drams of marine acid caufe a very perceptible alteration 
 in one pound of filk. 
 
 Spirit of wine which has been mixed with nitrous 
 acid cannot be ufed in bleaching, even though after- 
 wards reftlfied, upon an alkali, becaufe it ftlU retains a 
 portion of nitrous gas. Pure fpirit of wine without 
 acid extrafts a fine yellow colour from filk, which does 
 
 not ftparate for years, even though txpofed to the fun's BlcacMng, 
 light. Yellow filk cxpofed to the fun, lofcs its colour """"v ' "^ 
 in a (hort time. The acidulated fpirit which has been 
 ufed In the Infufion of filk, is changed by expofure to 
 the fun, but not in fuch a manner as to be rendered fit 
 for uie a fecond time. In order to obtain a beautiful 
 white colour, it is cffential that the filk fliould be Im- 
 merled In a large quantity of the fluid, efpeclally at the 
 firft Infufion. Without this management it would be- 
 come neceffary to make three infufions in the acidula- 
 ted fpirit. When the firft infufion is well managed, 
 the filk will have loft all its yellow colour, and become 
 confiderably white, at the fame time that the liquor will 
 have begun to change colour a little. As long as it 
 continues of a fine green, it is certain that It has not 
 exhaufted Its whole aftion upon the filk. The duration 
 of this firft infufion may be longer or (hortcr, without 
 inconvenience, according to the temperature. When 
 the temperature is at 77" of Fahrenheit, the firft Infu- 
 fion is often made in 10 or 12 hours. In fmall experi- 
 ments the heat of the atmofphere may be fupplled by 
 the water bath ; in which cafe all the infufions are ea- 
 fily made in the courfc of a day. 
 
 When the firft infufion is finifhed, and the liquor 
 drawn off, the filk appears greenlfh : the fubfequent 
 wafliings in fpirit of wine clear it of the liquor it re- 
 tained. This fprlnkling fhould be made with the wa- 
 tering pot, otherwife the quantity poured will be great- 
 er, and the management more wafteful. ' 
 
 Pieces of gauze and entire garments of filk have been 
 fuccefsfully bleached in this way. 
 
 The fineft natural white filks are rendered infinitely 
 whiter by this procefs. Spirit of wine alone has the 
 property of depriving yellow filk of its colour, which it 
 brings to the ftate of the naturally white filk. In this 
 ftate the filk is difpofed to acquire a greater degree of 
 brightnefs by a fingle infufion in the acidulated fpirit. 
 This procefs has Its advantages over the other, to which 
 it is alfo inferior in certain refpefls ; concerning neither 
 of which the author has entered into any detail. 
 
 The colouring matter was found to be a refin per. 
 feftly animallzed, affording by diftillation the fame pro- 
 dudfs as other animal matters, and the concrete volatile 
 alkali. 
 
 Silk whitened by fcouring may be dried freely In the 
 air without affedfing its luftre. This is not the cafe 
 with the filk bleached in the gum : if it be left at li- 
 berty to dry in the air, it refembles white flax without 
 any luftre. The beauty of this filk confifts in its fhlning 
 brilliancy; to fecure which it muft be dried in a ftate of' 
 tenfion. Mr Baume has contrived a fimple machine for 
 this purpofe. It confifts of a ftrong fquare frame of 
 wood ftanding upright upon feet : the upper horizon- 
 tal bar is fix feet long, and has fix iron pins driven 
 through it at equal diftances, fo as to projeft on each 
 fide for the purpofe of receiving tv\'elve bobbins. The 
 lower horizontal bar is moveable up and down in a mor- 
 tice, by means of a fcrew at each end : it is furnlfhed 
 with fix holes adapted to receive as many pins to cor- 
 refpond with thofe above. The fliains of filk are to be 
 dreffed and arranged upon wooden pins, as they are 
 taken out of the lack from wafhing. As foon as there 
 are twelve together, they are to be wrung with a ftaff; 
 after which the Ikains are to be hung one by one upon 
 as many bobbins put upon the upper pins of the fquare 
 
 frame.
 
 Method of 
 recovering 
 the alcohol 
 ufed, 
 
 B L E [911] 
 
 BlMchin?. frame. Another bobbin with tails is to be inferted in fatisfaAory manner. 
 •"■^v—"^ the lower loop of the Hcain, and fadcned to the corre- 
 fpondlng pin of the lower bar, by means of a ftrap and 
 hook, which need not be defcribed to fuch as are flight- 
 ly acquainted with mechanical objeAs. Wlieii the ma- 
 chine is thus fupplied with fl<ains on both fides, the 
 lower bar of the frame is to be pretTed down by the 
 fcrews until the filk is moderately ftretched. When it 
 h dry, the fcrews are to be equally (lackened, the (Icains 
 taken off and folded with a flight twift, that they may 
 not become entangled. 
 
 To complete the defcription of this procefs, it only 
 remains to (how how to recover the alcohol, and enfure 
 Q the purity of the acids made ufe of. 
 
 The alcohol which has been ufed in bleaching filk is 
 acid, and loaded with colouring matter. In this Hate 
 it cannot be again ufed. There are two methods of 
 diftilling it which have their refpeftive advantages and 
 inconveniences. 
 
 By the firft the acid is loft ; which is faturated with 
 potafs, in order that the diftillation may be afterwards 
 performed in a copper alembic. A folution of potafs 
 is to be poured into the acid fpirit, and Ilirred about to 
 promote the faturation. Carbonic acid is difengaged 
 with ftrong effervefcence from the alkali ; and the point 
 of faturation is known by the ufual teft, that the fluid 
 does not redden the tinfture of turnfol. The diftilla- 
 tion is then to be made in the copper alembic, and the 
 alcohol referved in proper vefTels. 
 
 In the fecond procefs for diftilling without alkali, the 
 acid fpirit is diftributed into a great number of glafs re- 
 torts, placed in the fand bath, on the gallery of a fur- 
 nace. The firft product is fcarcely acid ; but what 
 follows is more and more fo, and muft be kept in vef- 
 fels of glafs or ftone-ware, which become embarrafling 
 on account of their number. The fluid which remains 
 in the retorts has the colour of beer flightly turbid, and 
 contains the greateft part of the marine acid. It muft 
 be poured into one or more retorts, and concentrated by 
 heat gradually applied. The firft liquor which comes 
 over is (lightly red, turbid, and fcarcely acid. This is 
 to be thrown away, and the receivers changed. The 
 fucceeding produft is the colourlefs marine acid, of an 
 aromatic fmell refembling the buds of poplar. The re- 
 fin of the filk remains in the retort deconyjofed by the 
 acid. The marine acid thus obtained is weaker than it 
 originally was ; which is in faft of little confequence, 
 as it is pure, and may be fafely ufed, either by incrca- 
 fing the dofe proportional to its diminifhed ftrength, or 
 by concentrating it if required in the ufual way. If 
 this diftillation be made in a filver alembic, inftead of 
 retorts of glafs, and a capital and worm of pure tin be 
 annexed, the alcohol will be obtained fo flightly acid as 
 fcarcely to redden the tinfture of turnfol ; but it is 
 fufficiently acid to receive injury if preferved in a cop. 
 per vefTel. 
 
 As to the acid, Mr Baume obferves that the muria- 
 tic acid of commerce is unfit for the purpofe. It was 
 formerly prepared with the marine fait of the faltpetre 
 manufadurers ; and even when it is made with good 
 fait, the decompofition is effefted with common vitrio- 
 lic acid which contains nitrous acid. Marine acid 
 mixed with a fmall quantity of nitrous acid does not 
 
 prevent the filk from being beautifully whitened: it ^ ^ , 
 
 even accelerates the procefs confiderably, and in the moft juft come out of the prefs. 
 
 Ma 
 
 10 
 
 And of pre. 
 
 ->aring a 
 '*ure mu- 
 iatic acid. 
 
 B L E 
 
 But the alcuhol, every time it is Bleaching, 
 ul'ed and reftified, becomes charged with the atid and '— — v— ' 
 gas of nitre, which alTume the characters of the iiilious 
 anodyne liquor. In this ftate neither diftillations nor 
 repeated redlifications from alkali are fufficiciit to fepa- 
 rate the nitrous matter from the alcohol. Then it is 
 that the fuccefs of the operator vaniflies, with a degree 
 of rapidity equal to the advances which encouraged his 
 hopes at the commencement. 
 
 To purify common fulphuric acid, 100 pounds of it 
 are to be mixed in a large bafon of copper with the fame 
 quantity of river-water, and ftirred with a wooden fpa- 
 tula. The mixture inftantly becomes heated to the 
 boiling water point, and a great quantity of red vapour 
 is difengaged, which has the fmell of aqua-regia, and 
 arifcs from the nitric and muriatic acids. When this 
 mixture is made, it is proper to immerfe the bafon to a 
 fuitable depth in a large veflel of water, to hallen the 
 cooling. As foon as it is fufficiently cooled, it is to be 
 drawn off into bottles, and left to become clear during 
 feveral days. It is in the next place to be decanted, 
 and conveyed into retorts by a fyphon furmel, and the 
 reftification proceeded upon until it becomes perfeftly 
 white. Towards the end of the operation a fmall quan- 
 tity of fulphur fubhmes in the neck of the retort. In- 
 ftead of receivers, a fmall glafs cup is placed beneath 
 the aperture of each retort, in order to facilitate the dil'- 
 fipation of the nitric and muriatic acids. When the 
 acid in the retorts is fufficiently cooled, it is poured a 
 fecond time into the copper bafon, and mixed with loa 
 pounds of river-water, as at firft, and again concentra- 
 ted in the retorts till it becomes perfectly clear. The 
 muriatic acid is to be difengaged from common fait 
 by the application of this acid in the ufual manner. u 
 
 The oxy-muriatic acid is alfo ufed very generally forBiea.hing 
 bleaching paper, or rather the ftufF out of which paperF^P"- 
 is made. It has been alleged, and we believe with fome 
 truth, that fince this mode of whitening paper was in- 
 troduced into this country, the ftrength of paper is 
 much inferior to what it was formerly. If this be 
 really the cafe, perhaps it is owing to the ufe of too 
 concentrated an acid. 
 
 We fliall finifti this article with MrChaptal's account 
 of this procefs, who was the firft perfon that introduced 
 ft. " Blotting paper (fays he), by being put into oxy- 
 genated muriatic acid, is bleached without fuftering 
 any injury ; and rags of coarfe bad cloth, fuch ao are 
 ufed in the paper manufaftorles to make this kind of 
 paper, may be bleached by this acid, and will then fur- 
 nifti paper of a very fuperior quality. I bleached by it 
 an hundred weight of pafte, intended to be made into 
 blotting paper, and the increafe of value in the produft 
 was computed at z^^ per cent, whereas the expence of 
 the operation, when calculated in the ftrideft manner, 
 amounted only to "^ per cent. ,. 
 
 The property poiTelTed by this acid, of bleaching Mosle of 
 
 . ^ - . . . . g' 
 
 paper without injuring its texture, renders it very va-*''''''"'''S 
 luable for reftoring old books and fmoked prints. The"''^ '"'"'"' 
 latter, when difcoloured to fuch a degree that the fub- 
 jeift of them could hardly be diftinguilhcd, were re-efta- 
 blifhed and revived, in fo aftonilhing a manner that they 
 appeared to be new ; and old books, foiled by that yel- 
 low tinge which time always produces, may be fo com- 
 pletely renewed, that one might fuppofe them to be 
 
 The fimple immedion of a 
 print
 
 BOA 
 
 Sleaching print in oxyjjenated muriatic acid (leaving it therein a 
 II lonf^er or a ihorter time, according to the ilrength of 
 • the liquor) is all that is required for bleaching it ; but 
 when a book is to be bleached, fome farther precau- 
 tions are to be ufed. As it is necelTary that the acid 
 fhould wet eveiy one of the leaves, the book mull be 
 completely fpread open, and then, by letting the boards 
 of the binding relt upon the fides ot the vedtl, the pa- 
 per only will be Immerfed in the liquor. If any of the 
 leaves (lick together they mull be carcfnlly feparated, 
 that ail of them may be equally Impregnated. The li- 
 quor takes a yellow tinge, the paper grows white ; and 
 after two or three hours the book may be taken out of 
 the liquor, and foaked in clean water, which (hould 
 be clianged from time to time, in order to wafli out 
 the acid with which the book is Impregnated, and 
 alfo to deprive it of the difagreeable fmell it has con- 
 traded. 
 
 " The above method, which Is the firft I made ufe 
 of, has generally fucceeded pretty well: too often, how- 
 ever, the leaves of my books have had a motley appear- 
 ance, and fometimes feveral pages were not at all bleach- 
 ed ; I was therefore obliged to have recourfe to the 
 following more certain procefs. 1 began by unfewing 
 the books, and reducing them into (lieets ; thefe Iheets 
 I placed in divifions made in a leaden vefiel, by means 
 of thin (lips of wood, fo that the leaves when laid 
 flat were feparated from each other by very fmall inter- 
 vals. I then put the acid into the veflel, pouring It 
 againft the fide, that the leaves might not be difturbed ; 
 and when the operation was finiihed, I drew off the 
 acid by means of a cock fixed in the bottom of the 
 veflel. I then filled the veffcl with clean water, which 
 ■wafhed the leaves, and took off the fmell of the oxyge- 
 nated acid. They may then be dried, fmoothed, and 
 new bound. In this manner I have reftored many va- 
 luable books, which had become worthlefs from the bad 
 ftate they were in. 
 13 « When I had to bleach prints fo torn to pieces 
 
 JAnd prints, ^j^^j. j^^y confifted only of fragments fitted together, 
 and palled upon paper, I \v:is afraid I might lofe fome 
 of thefe fragments in the liquor, becaufe they fcparate 
 from the paper by the foftening of the paile : in that 
 cafe therefore I took the precaution of enclofing the 
 print in a large cylindrical bottle, which I turned upfide- 
 down, fixing Its mouth to that of a veffel in which I 
 had put a mixture proper for difengaging oxygenated 
 muriatic gas. This gas fills the infide of the bottle, and, 
 adting upon the print, takes off the llains, ink-fpots, 
 &c. while the fragments remain palled to the paper, 
 and confequently keep their refpeftive places." 
 
 BLOCKS (Encycl. Plate XCV. fig. 5.) a Reprc- 
 fents a fingle block, and b, c, two double ones of diffe- 
 rent kinds, without ftraps ; e, /, two double tackle 
 blocks, iron bound, the lower one,/, being fitted with 
 a fwivcl ; g, a double Iron block with a large hook ; 
 h, a fmall block ; /, a top block ; k, a voyal block ; /, 
 a clew garnet block ; m, the cat block, employed to 
 draw the anchor up to the cat-head. See CAT-Heads, 
 Encycl. 
 
 Cape or Large Snouted BOAR, a fpecies of the 
 genus Sus, which, according to M, Vaillant, differs 
 from every known fpecies, and has not been accurately 
 defcrihed by any writer of natural hidory. Buffon, in- 
 deed, in the Supplement to his Hiftory of Quadrupeds, 
 
 t 92 1 BON 
 
 has given a figure of it ; but nothing like the head of 
 
 Boar, 
 
 Boiintt. 
 
 the animal is <lifcoverable, fays our author, in that fi 
 gure, all its charafterillics having been omitted by the ^ ~ 
 draughtfman. M. Vaillant, during his laft travels in ^^'e VII. 
 Africa, fnot a monllrous boar of this fpecies on the 
 hanks of Filh river, and in the country of the Greater 
 NiMii^vAs. He defcribes it in the following terms ; 
 Its fnout, inllead of being taper and in the form of a 
 probofcls, is, on the contrary, very broad and fquare at 
 the end. It has fmall eyes, at a very little diftance 
 from each other, level with the furface, and near the 
 top of the forehead. On each cheek a very thick carti- 
 laginous flcin projects horizontally, being about three 
 Inches long and as many broad. At firfl fight you 
 would be tempted to take thefe excrefcenccs for the 
 ears ; particularly as the real ears of the animal, flicking 
 as it were to the neck, which is very (liort, are partly 
 concealed by an enormous mane, the brillles of which. 
 In colour red, brown, and greyifn, are 16 inches in 
 length on the flioiJders. Direflly below thefe falfe 
 ears is a bony protuberance on each fide, projedling 
 mure than an inch, ferving the animal to ilrike with to 
 the right and left. The boar has, befides, four tulks, 
 of the nature of Ivory, two in each jaw : the upper ones 
 are feven or eight Inches long ; very thick at the bafe, 
 and terminating in an obtnfe point, grooved, and rifing 
 perpendicularly as they IlTue from the lips : the lower 
 ones are much fmaller, and fo clofe to the upper ones 
 when the mouth is fhut, that they appear as one. The 
 head is a truly hideous objedl. It is fcarcely lefs fo than 
 that of the hippopotamus, to which at firfl view it ap- 
 pears to have a flrlking refemblance. Syilematiils, ac- 
 cuflomed to view nature only according to rules ella- 
 bliflied by therafelves, will be far from acknowlcd^^ing 
 this animal to be a boar ; for not to mention Its large 
 fnout, it wants incifive teeth in both jaws. Notwith- 
 flandlng Its wide muzzle, it ploughs up the earth to 
 feek for roots, on which it feeds. It is very aclive, 
 though large and bulky ; running with fuch fpeed, that 
 the Hottentots give it the name of the runner. 
 
 BONNET (Charles), was defcended from a French 
 family, who being compelled, on account of their reli- 
 gious principles, to emigrate from their native country, 
 eflablillied themfclves at Geneva in the year 1572. His 
 grandfather was advanced to the maglftracy in that ci- 
 ty, and adorned by his integrity an eminent ftatlon. ' 
 His father, who preferred the llation of a private citi- 
 zen, paid unremitted attention to the education of his 
 fon, who was born on the 13th of March 1720 ; and 
 Charles, at a very early period, recompenfed hi^ father's 
 afliduity, by the amiablenefs of his difpofition, and the 
 rapid progrels he made in general literature. When he 
 was about 16 years of age, he applied himfelf, with 
 great eagernefs, to the perufal of he SpeUacle de la Na- 
 ture ; and this work made fuch a deep imprefiion on his 
 mind, that it may be fald to have direfted the tafte and 
 the ftudies of his future life. What that publication 
 had commenced, was confirmed by the work of ha 
 Pluche ; but having accidentally feen the treatife of 
 Reaumur upon infedls, he was in a tranfport of joy. 
 He was very impatient to procure the book ; but as the 
 only copy in Geneva belonged to a public library, and 
 as the librarian was reluftant to intruft it in the hands 
 of a youth. It was with the utmoil difficulty that he 
 could obtain his end. 
 
 By
 
 BON [ 93 ] BON 
 
 By the polTeflion of this treafure, our afiiduous youth on the leaves of plants ; which, of all his publications Br 
 'was enabled to make feveral new and curious experi- in natural hiftory, bore the llrongcft marks of origina- *"" 
 
 nnet 
 
 mcnts, which he communicated to Reaumur himftlf ; lity, both with rclpett to the manner in which his ex- 
 and the high applaufe he gained from (o great a natu- peiimciita were made, and the difcovetitsrefulting from 
 rahft added frefli vigour to his afliduity. them. His extreme attachment to natural hilhiry gra- 
 in compliance with his father's defires, he applied dually led him to a fti-dy of a very different nature*; 
 himfeU, though with much reludance, to the ftudy of fpeculative philofophy now engaged his whole alien- 
 the law. The works of Burldmaqul pleafed him the lion. The firll fruits of his meditations in this depart- 
 moft, on account of the perfpicuous and philofophic mem was his Eflay on Pfychulugy. In this work the 
 manner in which the fubjeft was treated : the Inftitutes principal fafts obfcrvable in human nature, and the con- 
 oi Heineccius g?iii him fome courage alfo, as he per- fcquenccs refultiiig from them, arc ftalcd in a concife 
 
 ceived order and connexion ; but the Roman law terri- 
 fied him as the hydra of Lerna. Notwithilanding his 
 application to thefe authors, he ftlll continued attached 
 to natural hiftory, and was very attlve in making expe- 
 riments. The experiments which demonllrate that tree- 
 lice propagate without copulation, was communicated 
 by Reaumur to the Academy of Sciences; and this clr- 
 cumttance occafioned an epiftolary correfpondence be- 
 tween M. Bonnet and that great nalurallil. This was 
 doubtlefs very flattering to a youth of twenty years. 
 
 and conipicuous manner. He contemplated man from 
 the firlt moment of his exiftcnce, and purfutd the dc- 
 velopemer.t of his fenfesand faculties from fimple growth 
 up to intelligence. The work, which was publilhed 
 without his name, met with great oppofition, and was 
 criticifed with feverily ; but the cenfures were direfted 
 more againft his exprcllions than his principles ; nor 
 were they of fufficient importance to impede the gene- 
 ral acceptance of the publication. 
 
 His analyfis of the mental faculties was fimply a de- 
 
 The letter of Reaumur was accompanied with a pre- velopement of the ideas contained in the preceding 
 
 fent of that very book which he had borrowed with fo work. It engaged his inccfTant attention for the fpace 
 
 much difficulty two years before. of five years ; nor was it completed before 1759. It is 
 
 Animated by fuch diftlnguilhed marks of approba- fomewhat Angular that both he and the Abbe de Con- 
 
 tion, he diligently employed every moment he conld dillac fhould have illullrated their principles by the fup- 
 
 fteal from the ftudy of jurifprudence to the completion pofition of a ftatue, organized like the human body, 
 
 of his natural hiftory of the tree- loufe ; to experiments which they conceived to be gradually infpired with a 
 
 on the refpiralion of catterpillars and butterflies, which foul, and the progreffive developement of whofe powers 
 
 he difcovered to beeffefted by ftigmata, or lateral pores; they carefully traced. In the year 1760 this work was 
 
 to an examination of the conftrudlion of the txnia or publKhed at Copenhagen, by order and at the expence 
 
 tape-worm ; in frequent correfpondence with Reaumur; of Frederick V. and it was followed in 1762 by con- 
 
 and in aflifting Trembley In his difcoveries and publica- templations on organized bodies. In this the author 
 
 tion concerning millepedes, &c. Having in the year had three principal objecls before him : the firft was tfl 
 
 174.3 obtained the degree of doctor of laws, he relin- give a concife view of every thing which appears inte- 
 
 qullhed a purfult which he had commenced with fo refting in natural hiftory, refpefting the origin, deve- 
 
 much reludrtanoe. In the fame year he was admitted a lopement, and reproduflion of organized bodies ; tho 
 
 fellow of the Royal Society, to which he had comma- fecoiid was to confute the two different fyftems founded 
 
 jiicated a treatife on Infecls. 
 
 Bonnet being now liberated from his other purfults, 
 ;ipplied himfelf, without intermiffion, to coUeftlng toge- 
 ther his experiments and obfervatlons concerning the 
 tree-loufe and the worm, which he publifhed In 1744 
 under the title of InJeSnlovy. This work acquired de- 
 
 upon the Epigenefis ; and the third was to explain the 
 fyftem of Germs, indicate the ground upon which it 
 was founded, its correfpondence with fafts, and the 
 confequences refulting from it. This work was recei- 
 ved with much fatisfactlon by natural philofophers. 
 The Academy of Berlin, which had propofed the fame 
 
 ferved approbation from the public, and was honoured fubjeft as a prize queftlon for 1761, declared that they 
 
 by the commendation of the celebrated B. de JulFieu. confidered the treatife as the offspring of clofe obferva- 
 
 He was reproached, however, in a periodical publica- tion and profound reafoning; and that the author would 
 
 tion, with having paid too little attention to the deli- have had an indubitable right to the prize, if he had 
 
 cacy of his reader ; though his patience and accuracy confined his labours to the precife ftatement of the 
 
 were acknowledged to be deferving of praife. Such queftlon. It muft alio be recorded, to the honour of 
 
 unremitted application and labour could not fail of be- the great Malejherles, that he reverfed the interdlft 
 
 coming injurious to his health. Inflammations, nervous which the public cenfor had laid upon this book, un- 
 
 fever, fore eyes, &c. compelled him to relinquifti the der the pretext that it contained dangerous principles. 
 ufeof the microfcope and the ftudy of infcfts. This The Contemplation of Nature appeared in 1764 In 
 
 prevention was fo extremely mortifying to a man of his this work the author firft enlarged upon the common 
 
 tafte and aftivity of mind, that he was thrown into a conceptions entertained concerning the exiftence and 
 
 deep melancholy, which could only be fubdued by the perfeftlons of God ; and of the order and uniformity' 
 
 refolutlon infpired by philofophy, and the confolatlons obfervable in the unlverfe. He next defcends to man, 
 
 of religion : thefe gradually roufcd him from a dejefted examines the parts of his compofition, and the various 
 
 ftate of mind. About the end of the year 1746 our capacities with which he Is endowed. He next pro- 
 
 philofopher was chofen member of the Literary Inftitu- ceeds to the plants ; affembles and defcribes the laws of 
 
 tion at Bologna, which introduced him to a correfpon- their economy ; and, finally, he examines the infeds, 
 
 dence with the famed Zanotti, who may be deemed the indicates the principal circumftances in which they dif- 
 
 Fontenelle of Italy. fer from larger animals, and points out the philofophi- 
 
 In the y€ar 1747 he undertook a very difficult work cal inferences that may legitimately be deduced from 
 
 thefc;
 
 BON 
 
 Bonncf. tliefe differences ; and he concludes with obfertations 
 '—v~— rclpcfting the iiiduftry of infcfts. This work being of 
 a popular nature, the author fparcd no pains in beftow- 
 hig upon it tliofe ornaments of which it was fufcep- 
 tible. The principles which he thus difcovered and ex- 
 plained, induced him to plan a J'yjfcm of moral philo- 
 foph\ ; which, according to his ideas, coniilled folely 
 in the obfcrvance of that relation in which man is pla- 
 ced, refpeding all the beings that furround him. The 
 firft branch would have comprehended, various means 
 which philofophy and the medical fcience have difco- 
 vered for tlie prevention of difeafe, the prefervation and 
 augmentation of the corporeal powers, and the better 
 exertion of their force : in the fecond, he propofed to 
 fnew, that natural philofophy has a powerful tendency 
 to embellifh and improve our mind, and augment the 
 raimber of our rational amufemeuts, while it is replete 
 with beneficial effects refpeftirg the fociety at large. 
 To manifeft the invalidity of opinions, merely hypothe 
 tical, he undertook, in the third place, to examine, whe 
 ther there vrere not truths within the Compafs of hu- 
 ■m'an knowledge, to which the mod fceptical philofopher 
 muft be compelled to yield his confent, and which might 
 ferve as the bafis of all our reafonings concerning man 
 and his various relations. He then would have direft- 
 ed his attention to a firft caufe, and have manifefted 
 iiow greatly the idea of a Deity and Supreme Law- 
 giver favoured the conclufions which reafon had drawn 
 From the nature and properties of things : but it is 
 deeply to be regretted that his health, impaired by in- 
 ceflant labour, would not permit him to complete the 
 defign. 
 
 His laft publication was the Palingenefis, which treats 
 of the prior exiftence and future flate of living beings. 
 
 Of his publications in natural hiflory, thofe deemed 
 the moft excellent are, his Treatife on the beft Means 
 of Preferving Infefts and Fifli in Cabinets of Natural 
 Hiftory ; a DifTertation on the Loves of the Plants ; 
 fundry pieces on the Experiments of Sfallanzani, con- 
 cerning the Reprodudtion of the Head of the Snail ; a 
 DifTertation on the Pipa, or Surinam Tod ; and diffe- 
 rent Treatifes on Bees. 
 
 In the year 1783 he was elefted honorary member 
 of the Academy of Sciences at Paris ; and of the Aca- 
 demy of Sciences and the Belles Lettres at Berlin. 
 
 Much of his time was employed in a very extenfive 
 correfpondence with fome of the moft celebrated natu- 
 ral philofophers and others. Of this number were Reau- 
 r:vr, De Geer the Reaumur of Sweden, Du Hnmel, 
 the learned Hallei; the experimental philofopher Spal- 
 lanzani. Van Smieten, Merian, and that ornament of 
 Switzerland the great Lambert. He entertained, how- 
 ever, the utmoft averfion to controverfy. He thought 
 that no advantage to be obtained by it could compen- 
 fate for the Jofs of that repofe which he valued, with 
 Newton, as the rem prorfus Jubjlantlalem. He never 
 anfwcred remarks that were made to the prejudice of 
 his writings, but left the decifion with the public ; yet, 
 ever ready to acknowledge his errors, he was fmcerely 
 thankful to every one who contributed to the perfec- 
 tion of his works. He was ufed to fay that one con- 
 feffion, •/ was in the ivrong, is of more -value than a 
 thoufand ingenious confutations. 
 
 His literary occupations, and the care he was obliged 
 to take of his health, prevented him from travelling. 
 
 [ 94 ] 
 
 BOO 
 
 ing. 
 
 He delighted in retirement, and every hoar was occu- Bonner, 
 pied in the improvement of his mind. The laft 25 UooKkccp. 
 years of his life were fpent in the fame rural fituation _ 
 where he had pafled the greater part of his early days ; 
 yet notwithllanding the purfuit of literature was his lu- 
 preme delight, he never refufed to fufpend his ftudies, 
 when the good of his country feemed to demand his 
 fervices. 
 
 He was cho!en in 1752 member of the Grand Coun- 
 cil in the republic of Geneva : and he afliftcd regularly 
 at their deliberations till the year 176R, where he di- 
 iflnguifhed himfelf by his eloquence ; his moderation, 
 united with firmnefs ; by his good fenfe and penetra- 
 tion in cafes of difficulty ; and by the zeal with which 
 he endeavoured to reclaim his fellow-citizens to that 
 ancient fimplicity of manners which had been fo condu- 
 cive to the welfare of the ftate, and to the love of vir- 
 tue, fo effential to the exiftence of genuine liberty. His 
 conduct, in every cafe, was confiftent with his princi- 
 ples. He took no pains to accumulate wealth, but re- 
 mained fatisfied with a fortune equal to his moderate 
 wants, and to the exercife of his benevolence. The 
 perfeft correfpondence between his extenfive knowledge 
 and virtuous deeds procured him univerfal efteem. 
 
 In the year 1788 evident fymptoms of an hydropt 
 peBor'is manifefted themfelves ; and from this time he 
 gradually declined. He fuftained his indifpofition with 
 unremitted cheerfulnefs and compofure. After various 
 fluftuations, ufual in that complaint, he died on the 
 20th of May 1793, in the 73d year of his age ; retain- 
 ing his prefence of mind to the laft moment, adminifter- 
 ing comfort to furrounding friends and relatives, and 
 attempting to alleviate the diftrefs of his difconfolate 
 wife, in whofe arms he expired. 
 
 As 3 demonftration of the high value placed upon 
 his labours and talents by the literati, we have only to 
 remark, that he was member of moft of the learned fo- 
 cieties of Europe. 
 
 BOOK-KEEPING, is an art of which the importance 
 is univerfally known; and as commonly praftifed, it has 
 been fufficiently explained in the Encyclopedia Britan- 
 nica. But fince that ariticle was written, a great im- 
 provement has been introduced into the art, or rather a 
 new method of book-keeping has been invented by 
 Mr Edward Thomas Jones of the city of Briftol, 
 accountant, who calls it the Engltjh fyjlem of book-keep- 
 ing ; and thinks that by it accounts may be more regu- 
 larly kept, and errors in accounts more eafily detefled, 
 than by any other method hitherto known. We are 
 much inclined to be of his opinion ; and ftiall therefore 
 lay before our redears his defcription of this method, as 
 we find it in the fpecification of the patent which was 
 granted to him January 26. 1 796. 
 
 The Englifb Syflem of BooK-Keeping requires three 
 books, called a day-book or journal, an alphabet, and a 
 ledger, which muft be ruled after the following method, 
 viz. the day-book to have three columns on each page, 
 for receiving the amount of the tranfaftions ; one co- 
 lumn of which to receive the amount of debits and cre- 
 dits, one column to receive the debits only, and one 
 column to receive the credits only ; or it may be ruled 
 with only two columns on each page, one column to 
 receive the amount of the debits, and one column to 
 receive the amount of the credits. There muft alfo be 
 on each page of the day-book four other columns ruled, 
 
 two
 
 BOO 
 
 [ 95 ] 
 
 BOO 
 
 Boole- two on the left fide next the amount of the debits, and 
 ktciiiig. t^vo on the right fide next the amount of the credits, 
 ""'^'~~' for receiving the letter or mark of polHng, and the page 
 of the ledger to which each amount is to be pofted. 
 
 The alphabet need not be ruled at all; but mull con- 
 tain the name of every account in the ledger, the letter 
 that is annexed to it as a mark of pofting, and the page 
 of the ledger. 
 
 The ledger muil be ruled with three, four, five, or 
 feven columns on each page, as may be moft agreeable, 
 for receiving the amounts of tlie different tranfaftions 
 entered in the day-book. And the procefs for uCng 
 thefe books, or making up books of accounts on this 
 plan, is as follows : 
 
 When a perfon enters into trade, whether by himfelf 
 or with copartners, he muft have an account opened 
 with himfelf in the ledger ; entering firft in the day- 
 book, and then to the credit of his account in the led- 
 ger, the amount of the property he advances into trade ; 
 The account may be headed either with his name only, 
 or elfe called his ilock-account. 
 
 Jf you buy goods, give the perfon credit of whom 
 you purchafe ; when you fell goods, debit the perfon to 
 whom faid goods are fold. If you pay money, debit 
 the perfon to whom paid, not only for what you pay, 
 but alfo for any difcount or abatement he may allow, 
 and give the calhier credit for the neat amount paid. 
 If you receive money, credit the perfon of whom you 
 receive it, not only for what he pays, but alfo for any 
 difcount or abatement you may allow, and debit the 
 cafhicr for the neat amount received ; taking care in 
 thefe entries to have nothing myfterious or obfcure, but 
 merely a plain narrative of the fad\, introducing not one 
 uftlcfs word, and avoiding every technical term or phrafe 
 except the words debit and credit, which are full and 
 comprehenfive, and the only terms that are applicable 
 to every tranfaftion, and maybe affixed to every entry. 
 
 But as a hurry of bufinefs will fomctimes take place 
 in almoft every counting-houfe, which may caufe the 
 entries to be made to the debit inftead of the credit of 
 an account in the day-book, and to the credit inftead of 
 the debit, Mr Jones has endeavoured as much as pofiible 
 to counteraft the evil, by having only one column for 
 receiving the amount of every tranfaftion, whether de- 
 bits or credits, at the inftant of making the entry ; and, 
 for the convenience of feparating the debits from the 
 credits, previous to pofting, which is neceffary to pre- 
 vent confufion and perplexity, he has two other columns 
 on the fame page ; that on the left fide into which the 
 amount of every debit n-.r ft be carefully entered, and 
 that on the right for the amount of the credits, which 
 columns muft be caft up once a month. The column 
 of debits and credits of ilfelf forming one amount ; the 
 column for the debits producing a fecond amount ; and 
 the column of credits a third amount ; which fecond 
 and third amounts added together, muft exactly agree 
 with the firft amount, or the work is not done right. 
 
 By this means the man of bufinefs may obtain month- 
 ly fuch a ftatement of his affairs as will Ihow how much 
 he owes for that month, and how much is owing to 
 him ; and the debits being added together for any given 
 time, with the value of the flock of goods on hand, 
 ■will, when the amount of the credit is fubtrafted there- 
 from, fhew the profits of the trade. 
 
 Our author now proceeds to the procefs of pofting ; 
 
 which begins with opening an account in the ledger Bo-k- 
 with every perfon to wliofe debit or credit there has Iti^^P "g- ^ 
 been an entry made in the day-book ; affixing to each ' 
 account a letter, which is to be ufed as a mark of poft- 
 ing. The perfon's name, place of abode, and the folio 
 of the ledger, muft then be entered in the alphabet, 
 with the fame letter prefixed to each name as is affixed 
 to the account in the ledger. Next, the page of the 
 ledger on which each account is opened (and which will 
 be feen in the alphabet) muft be affixed to each amount 
 in the day-book, in the column for that purpofe. The 
 date and amount of each debit muft then be pofted in 
 the columns for receiving it in the ledger, on the left 
 or debit fide of that account to which it relates ; enter- 
 ing, as a mark of pofting in the day-book, againft each, 
 amount, the fame letter that is affixed to the account in 
 the ledger, to which faid amount may be pofted. Ob- 
 ferving that the debits of January, Februaiy, March, 
 &c. muft be pofted into the column for thofe months 
 in the ledger, and the credits muft alfo be ported iu 
 like manner, filling up each account in the centre, at 
 the expiration of every month, with the whole amount 
 of the month's tranfadlivns ; thus having, in a fmall 
 fpace, the whole ftatement of each perfon's account for 
 the year ; in the columns to the right and left the a. 
 mount feparately of each tranfadion ; and iu the centre 
 a monthly ftatement. 
 
 Having defcribed the procefs of this method of book- 
 keeping, he thus fliews how to examine books kept by 
 this method, fo as to afcertain, to an abfolute certainty^ 
 if the ledger be a true reprefentation of the day-book ; 
 /'. e. not only if each tranfaftion be correftly pofted, as 
 to the amount thei-eof, but alfo if it be rightly enter-.d 
 to the debit or credit of its proper account. This ex- 
 amination differs from the modes that have heretofore 
 been praftiled, as well in expedition as in the certain 
 accuracy which attends tjic pioccfs ; it being only ne. 
 ceflary to caft up the columns through the ledger de- 
 bits and credits, according to the examples given ; and 
 the amount of thofe columns, if right, muft agree with 
 the columns in the day-book for the fame correfpond- 
 ing fpace of time. Thefe caftings fhould take place 
 once a month ; and if the amounts do not agree, the 
 pofting muft then, but not elfe, be called over : and' 
 when the time, whether it be one, two, three, or four 
 months, that is allotted to each column of the ledger is 
 expired, the amount of each column (liould be put at 
 the bottom of the firft page, and carried forward to the 
 bottom of the next, and fo on to tlie end of the ac- 
 counts ; taking care that the amount in the day-book, 
 of each month's tratifaftions, be brought into one grofs 
 amount for the fame time. 
 
 But although this procefs inuft prove that the ledger 
 contains the whole contents of the day-book, and nei- 
 ther more nor kfs, yet it is not complete without the 
 mode of afccrtaining if each entry be pofted to its right. 
 account ; which may be afcertained by the following 
 method: He has laid down a rule that aletter, whlcti 
 may be ufed alphabetically in any form or Ihape that h 
 agreeable, fhall be affixed to each account in the led- 
 ger, and the fame letter prefixed to the names in the al- 
 phabet, thefe letters being ufed as marks of porting, and 
 affixed to each account in the day-book as it is pofted; 
 it is only neceffary therefore to compare and fee that 
 the letter affixed to each entry in the day-book is the. 
 
 fame
 
 Boo't. 
 Bofjovi h 
 
 :b o s [9 
 
 fame as is prefixed to the fame name in the alphabet ; 
 a ditference here fliews of courfe an error, or elfe it 
 [ mull be right. 
 
 At the end of the year, or at any other time, when 
 perfons balance their accounts, if there be no obje£lions 
 to t!ie profits of the trade appearing in the books, the 
 ftock of goods on hand at prime coll may be entered in 
 the day book, either the value in one amount, or the 
 particulars fpecified, as may be moil expedient, and an 
 account opened for it in tiie ledger, to the debit of 
 which it mud be polled. The calling up of the led- 
 ger mull then be completed : and when found to agree 
 with the day-book, and the amount placed at the bot- 
 tom of each column, fubtradl the credits from the de- 
 bits, and it will (hew tlie profit of the trade ; unlefsthe 
 credits be the greater amount, which will Ihew a lofs. 
 In taking off the balances of the ledger, one rule muft. 
 be obferved, and it cannot be done wrong : As you 
 proceed, liril fee the difference between the whole 
 amounts of the credits and debits on each page for the 
 year, with which the difference of the outflanding ba- 
 lances of the fevcral accounts on each page mull exadl- 
 ly agree, or the balances will tiot be taken right. By 
 this means every page will be proved as you proceed, 
 and the balances of ten thoufand ledgers, on this plan, 
 could not unobfervedly be taken off wrong. 
 
 BOSCOVICH (Roger Jofeph), one of the moft 
 eminent mathematicians and philolophers of the pre- 
 fent age, was bom of virtuous and pious parents, on 
 the I :th of May 171 1, in the city of Ragufa, the ca- 
 pital of a fmall republic of the fame name, lying on the 
 eaftern coaft of the Adriatic Sea. At baptifm, the 
 name of Roger was given him, to which he added 
 that of Jofeph when he received the facrament (a) of 
 confirmation. 
 
 He iludied Latin grammar in the fchools which 
 were taught by the Jefuits in his native city. Here 
 it foon appeared that he was endued with fuperior ta- 
 lents for the acquilition of learning. He received know- 
 ledge with great facility, and retained it with equal 
 lirmnefs. None of his companions more readily per- 
 ceived the meaning of any precept than he ; none more 
 jullly applied general rules to the particular cafes 
 contained under them. He enounced his thoughts 
 with great perfpicuity, and came foon to compote with 
 propriety and elegance. His application was equal to 
 his capacity, and his progrefs was rapid. At the be- 
 ginning of the I 5 th year of his age, he had already gone 
 through the grammar claffes with applaufe, and had 
 ftudied rhetoric for fome months. His moral behavi- 
 our had likcwife been very good : he was refpeftful and 
 obedient to his parents and mailers, affable and obli- 
 ging to his equals, and exemplary in all the duties of 
 religion. It was now time for him to determine what 
 courle he would lleer through life ; nor did he hefitate 
 long in coming to a refolution. 
 
 The Jefuit fathers, by teaching the fciences to youth, 
 were very ufeful, and at the fame time had a fine op- 
 portunity of obferving their fcholars, and of drawing 
 into their fociety thofe boys who feemed fit for their 
 
 5 ] BOS 
 
 purpofe. Snch a fubjeft as the young Bofcovlch could Bofcnvich. 
 not efcape their attention. They fliewed him particu- ' y -^ 
 lar kindnefs, to which he was not infenfible. He had 
 an ardent thirll for learning ; to advance in which he 
 felt himfelf capable ; and he thought he could nowhere 
 have a better opportunity of gratifying this laudable 
 inclination than in their order, in which fo many per- 
 fons had (hone in the republic of letters. According, 
 ly, with the confent of his parents, he petitioned to be 
 received among them ; and his petition was immediately 
 granted, becaufe it was defired by thofe to whom it 
 was made. 
 
 It was a maxim with the Jefuits to place their moft 
 eminent fubjeifls at Rome, as it was of importance for 
 them to make a good figure on that great theatre. 
 Wherefore, as Roger's mailers had formed great ex- 
 peAations of him, they procured his being called to 
 that city ; whither he was fent in the year 1725, and 
 enteied the novicefhip with great alacrity. This no- 
 viceAiip was a fpace of two years, in which the candi- 
 date made a trial of his new (late of life ; and in the 
 mean time his new fuperiors obferved him, and delibe- 
 rated whether or not they would admit him into their 
 body. During thefe two years, the novice was princi- 
 pally employed in exercifes of piety, in lludying books 
 of Chrillian morality, and in becoming perfedlly ac-* 
 quainted with the rules and conftitutions of the order. 
 After thefe two years were pall, the Jefuits were wil- 
 ling to retain Bofcovich, and he was no lefs defirous of 
 remaining with them. He therefore paffed to the 
 fchool of rhetoric; in which, for two other years under 
 the moft expert mailers of the fociety, young men per- 
 fetled themfelves in the arts of writing and fpeaking, 
 which was of fo great confequence to perfons who were 
 dellined to treat fo much with their neighbours. Here 
 Bofcovich became perfeftly well acquainted with all the 
 claffical authors, and applied with fome predilcilion to 
 Latin poetry. 
 
 After this he removed from the noviciate to the Ro- 
 man College, in order to iludy philofopliv, which he 
 did for three years. In order to underlland the doc- 
 trine of phyfics, it was necelTary to premife the know- 
 ledge of the elements of geometry, which is alfo othcr- 
 VN'ilc proper for forming the mind, and for giving to it 
 a true tafte for truth. Here it was that our young 
 phllofopher came to be in his true element ; and it now 
 appeared how extremely fit his genius was for this kind 
 of iludy. His mailer, though he was able and expert, 
 inilead of leading him on, was fcarcely able to keep 
 pace with him, and his condifciples were left far be- 
 hind. He likewife found the application of the ma- 
 thematics to natural philofophy pleafant and eafy. 
 From all this, before the end of the three years, he 
 had made a great advancement in phyfical and mathe- 
 matical knowledge; and his great merit was generally ac- 
 knowledged by his companions, and well known to his 
 fuperiors. He had already begun to give private lef- 
 fons on mathematics. 
 
 According to the ordinary courfe followed by the 
 Jefuits, their young men, after ftudying philofophy, 
 
 were 
 
 (a) For this article we arc indebted to a dignified clergyman of the church of Rome, who was one of ^of- 
 covich's favourite pupils.
 
 BOS 
 
 were wont to be employed in teaching Latin and the 
 ' belles lettres for the fpace of five years, that fo they 
 might become dill better acquainted with polite learn- 
 ing, and arrive at the ftudy of theology and the priefl- 
 hood at a riper age. But as Roger had difcovered 
 extraordinary talents for geometrical ftudies, it was 
 thought by his fuperiors that it would be a pity to de- 
 tain him from his favourite purfuits in a drudgery for 
 ■which fo many others were tit enough. He was there, 
 fore difpenfed with from teaching thofe fchools, and 
 was commanded to commence the ftudy of divinity. 
 
 During the four years that he applied to that fub- 
 lime fcience, he ftill found fome leifure for geometry 
 and phyfics ; and even before that fpace was ended, 
 he was named profeffbr of his beloved mathematics. 
 
 He was now placed in an office for which he was 
 fuperlatively fit, and for which he had a particular pre- 
 dileftion. Befides having feen all the bell modern pro- 
 duftions on mathematical fubjefts, he ftudied diligently 
 the ancient geometricians, and from them learned that 
 exadl manner of reafoning which is to be obferved in 
 all his works. Although he himfelf perceived eafily 
 the concatenation of mathematical truths, and could 
 follow them into their molt abftrufe recefles, yet he ac- 
 commodated himfelf with a fatherly condefcenfion to 
 the weaker capacities of his fcholars, and made every de- 
 monftration clearly intelligible to them. When he per- 
 ceived that any of his difciples were capable of advan- 
 cing fatter than the reft, he himfelf would propofe bis 
 giving them private leffons, that fo they might not lofe 
 their time ; or he would propofe to them proper books, 
 with diredlions how to ftudy them by themfelves, being 
 always ready to folve difficulties that might occur to 
 them. 
 
 To the end that he might be the more ufeful to his 
 fcholars, he took time from higher purfuits to compofe 
 new elements of arithmetic, algebra, plain and folid 
 geometry, and of plain and fpheric trigonometry ; and 
 although thefe fubjefts had been well treated by a great 
 many authors, yet Bofcovich's work will always be e- 
 fteemed by,good judges as a mafterly performance, well 
 adapted to the purpofe for which it was intended. To 
 this he afterwards added a new expofition of conic fec- 
 tions ; in which, from one general definition, he draws, 
 with admirable perfpicuity, all the properties of thofe 
 three moft ufeful curves. He had meditated a com 
 plete body of pure and mixed mathematics, in which 
 were to be comprehended treatifes on mufic, and on ci- 
 vil and military architeflure ; but from accomplifhing 
 this he was prevented by other neceflary occupations. 
 
 According to the cullom of fchools, every clafs in 
 the Roman College, towards the end of the fcholaftic 
 year, gave to the public fpecimens of their proficiency. 
 With this view Bofcovich publifhed yearly a differtation 
 on fome interefting phyfico-mathematical fiibjedl. The 
 i)oftrine of this diftertation was defended publicly by 
 fome of his fcholars, affifted by their mafter. At thefe 
 literary differtations there was always a numerous con- 
 couife of the moft learned men in Rome. His new 
 opinions in philofophy were here rigoroudy examined 
 and warmly controverted by perfons well verfed in 
 phyfical ftudies : but he propofed nothing without fo- 
 lid grounds ; he had forefeen all their objeftions, an- 
 fwered them viftorioufly, and always came off with 
 great applaufe and increafe of reputation. He publilh- 
 
 SuPPL. Vol. I. Part I. 
 
 [ 97 ] 
 
 BOS 
 
 cd likewife differtations on other occafions ; and thefe Bo fcovicli. 
 works, though imall in fize, arc very valuable both for — "v— ' 
 the matter they contain, and alfo for the manner in 
 wliich it is treated. The principal fubjeifts of thefe dif- 
 fertations are the following : The fpots in the fnn ; 
 the tranfit of mercury under the fun ; the geometrical 
 conftruftion of fpheric trigonometry ; the aurora bo- 
 realis ; a new ufe of the telefcope for the determination 
 of celeftial objefts ; the figure of the earth ; the argu- 
 ments made ufe of by the ancients to prove the rotun- 
 dity of the fame ; the circles which are called ofcula- 
 tors ; the motion of bodies projected in a fpace void of 
 rcfiftance ; the nature of infinities and of infinitely little 
 quantities ; the inequality of gravity in different parts 
 of the earth ; the annual aberration of the fixed ftars ; 
 the limits of the certainty to which aftronomical obfer- 
 vations can arrive ; a difculTion on the whole of aftrono- 
 my ; the motion of a body attrafted by certain forces 
 towards an immoveable centre in fpaces void of refift- 
 ance ; a mechanical problem on the folid of greateft 
 attraftion ; a new method of ufing the obfervation of 
 the phafes in the lunar eclipfes ; the cycloid ; the lo- 
 giftic and certain other curve lines ; the forces that are 
 called living ; the comets ; the flux and reflux of the 
 fea ; light ; whirlwinds ; a demonftration and iUuftra- 
 tion of a palTage in Newton concerning the rainbow ; 
 the demonftration and illuftration of a method given 
 by Euler, regarding the calculation of fraftions ; the 
 determination of the orbits of a planet by means of ca- 
 toptrics, certain conditions of its motions being given ; 
 the centre of gravity and that of magnitude ; the at- 
 mofphere of the moon ; the law of continuity, and the 
 confequences of it in the elements of matter and their 
 forces ; the law of the forces that exift in nature ; len- 
 fes and dioptrical telefcopes ; the perturbation which 
 appears to be caufed mutually by Jupiter and Saturn, 
 and that chiefly about the time of their coiijunftlon ; 
 the divilibility of matter and the elements of bodies ; 
 the objeftive micrometer ; — befides other fubjetts of the 
 like nature, of which he has treated in feparate pieces, 
 or in communications inferttd in the tranfactions of li- 
 terary focieties or academies, he being a member of 
 thofe that are moft famous in Europe. > It was in fome 
 of the above-mentioned differtations that Bofcovich made 
 known firft to the world his fentiments conceroini^ the 
 nature of body, which he afterwards digefted into a re- 
 gular theory, which is juftly become fo famous among 
 the learned. 
 
 Father Noceti, another Jefuit, had conipofed two 
 excellent poeins on the rainbow and the aurora borealis. 
 Thefe poems were publiflied with learned annotations 
 by Bofcovich ; in which, among other things, he with 
 great fagacity difcovers errors in optics into which Dc 
 Dominis, Kepler, and others, had fallen. 
 
 His countryman, Benediiit Stay, after having pub- 
 liflied the philofophy of Defcartes in Latin verfe, at- 
 tempted the fame with regard to the more modern and 
 more true philofophy, and has executed it with won- 
 derful fuccefs, to the admiration of all good judges. 
 The two firft volumes of this elegant and accurate 
 work were publifhed with annotations and fupplements 
 by Bofcovich. Thefe fupplements are fo many fliort 
 differtations on the moft important parts of phyfics and 
 mathematics. Here is to be found a foUitlon of the 
 problem of the centre of ofcillation, to which Huygens 
 N had
 
 BOS 
 
 r 98 ] 
 
 BOS 
 
 Eofcov'ch. had come by a wrong method > here lie confutes Eu'cr, 
 ' > who had imagined that the vis imrliit was tietefiary in 
 
 matter ; here he refutes the ingenious efforts of Riccati 
 en the Lcibnitzian opinion of the forces called livirg. 
 He likewife fliews the falfehood of the mathematical 
 prejudice, according to which the right line is confider- 
 cd as efTtntially more furple than curves, and makes it 
 appear that the notion of tlie faid right line is com- 
 monly accompanied with many paradoxes. He demon- 
 ftrates, by the doflrine of combinations, feme beautiful 
 theorems concerning the fpace occupied by the fmall 
 maffes of body, with many ufeful obfervations on fpace 
 and time. 
 
 Benedict XIV. who was a great encourager of learn- 
 ing, and a beneficent patron of learned men, was not 
 ignorant how valuable a fubjeft Rome poffcffed in Bof- 
 covicli ; and this pope gave him many proofs of the 
 efteem he had for him. Two fiffures which had been 
 perceived in the cupola of the church of St Peter's on 
 the Vatican had occafioned fome alarm. The pope de- 
 fired Bofcovich and fome other mathematicians to make 
 their obfervations, and give their opinion on the fame. 
 They obeyed, and their opinion was printed. They 
 fhewed that there was no caufe to apprehend danger ; 
 but, for greater fecurity, they propofed certain precau- 
 tions, which were adopted and put in execution. 
 
 The high opinion which the pope had formed of his 
 talents, and the favour in which he was with Cardinal 
 Valenti, minifter of ftate, proved hinderances to his go- 
 ing to America, for which a propofal was made to him 
 by the court of Lifbon. Some differences had long 
 fubfdled between Spain and Portugal concerning the 
 boundaries of their refpeftive dominions in that great 
 continent ; and John V. of Portugal wiilied that Bof- 
 covich would go over and make a topographical furvey 
 of the country in difpute. He was not unwilling to 
 undertake fuch a taflv, which was entirely to his tafte ; 
 and he was refolved at the fame time to meafure a de- 
 gree of the meridian in Brazil, which might be com- 
 pared with that meafured at Quito by the French aca- 
 demicians Bouguer and Condamine, with the Spaniards 
 Ulloa and Doy. But the pope hearing of this propo- 
 fal, fignified to the Portuguefe minifter at Rome, that 
 his mafter muft. needs excufe him for detaining Bofco- 
 vich in Italy, where he had occafion for him, and could 
 by no means confent to part with him. 
 
 Accordingly a comm^Jlion was given to Bofcovich 
 by Benedift to correft the maps of the papal eftate, 
 and to meafure a degree of the meridian paffuig through 
 the fame. This he performed with great accuracy, 
 alTifted by F. Chriftopher Maire an Englifh Jefuit, and 
 likewife a great mathematician. Their map was en- 
 graved at Rome, and is perhaps the moll; exaft piece of 
 the kind that ever was printed, as all the places are 
 laid down from triangular obfervations made by the 
 ableft hands. Bofcovich alfo publifhed, in a quarto 
 volume in Latin, an account of the whole expedition, 
 which appeared at Rome in the year 1755, and \^3 
 afterwards printed at Paris in French in the year 17/O. 
 Here he gives a detail of their obfervations and of the 
 methods they followed, and likewife of the difficulties 
 they encountered, and how they were furmounted. One 
 <>{ thefe embarralTed them a good deal at the time, but 
 ■was afterwards matter of diverfion to them and others. 
 Jiome of the inhabitants of the Apennines, feeing them 
 
 pafs from hill to hill with poles and ftrange machines, Bofcovich, 
 imagined that they were magicians come among their « -' 
 
 motmtains in fearch of hidden treafUres, of which they 
 had fome traditions : and as tempcfts of thunder and hail 
 happened about the fame time, they fuppofed that thefe 
 calamities were caufed by the forcerics of their new 
 vifitants. They therefore infifted that Bofcovich and 
 Maire fliould depart ; and it was not eafy to convince 
 them that their operations were harmlefs. In this work 
 there is infcrted a defcription of the inftruments made 
 ufe of in determining the extent of the degree of the 
 meridian ; and the whole work may be extremely ufe- 
 ful to praclical geometricians and aftronomers. 
 
 In the year 1757 the republic of Lucca intrufted 
 Bofcovich with the management of an affair which was 
 to them of confiderable importance. Between that re- 
 public and the regency of Tufcany there had arifen a 
 difagreeable difpute concerning the draining of a lake, 
 and the direftion to be given to fome waters near the 
 boundaries of the two itates. The Lucchefe fenate 
 chofe our pliilofopher to treat of this bufniefs on their 
 part. He repaired to the fpot, confidered it attentive- 
 ly, and drew up a writing, accompanied with a map, 
 to Ihew m.ore clearly what appeared to him moft equi- 
 table and moft advantageous for both parties. In order 
 to enforce his reafons the more efleftually, it was 
 thought proper that he fliould go to Vienna, where the 
 Emperor Francis I. who was likewife grand duke of 
 Tufcany, refided. He was fo fuccefsful in this nego- 
 ciation, that he obtained every thing that Lucca defi- 
 red, and at the fame time acquired great efteem at the 
 Imperial court. In proof of this, tlie Emprefs Queen 
 made his opinion be allied concerning the liability of 
 the Cefarean library, and the repairs to be made in it ; 
 which he gave in writing, and it was received with 
 thanks, as being very well grounded. 
 
 When he had concluded the affair which had brought 
 him to Vienna, he forefaw that, for a month or two, 
 the fnowsin the Alps would not allow him to return 
 to Italy. He therefore refolved to employ that time 
 in completing his fyftem of natural philofophy, on 
 which he had been meditating for the fpace of thirteen 
 years. He publiftied his work on that great fubjeft 
 in the beginning of the year 1758, in the above-men- 
 tioned city. We ftiall in the end give an account of that 
 celebrated fyftem, and here go on with our narration. 
 
 On his return to Lucca, he not only met with the 
 approbation of all he had done for the intereft of the 
 republic ; but alfo the fenate, in teftimony of their gra- 
 titude, made him prefents, and enrolled him in the num- 
 ber of their nobiHty, which was the greateft honour 
 they had in their power to confer on him. 
 
 He, who was thus ufeful to foreigners, could not rc- 
 fufe to be ferviceable to his own country when an oc- 
 cafion of being fo offered itfelf. The Britifh miniftry 
 had been informed, that fliips of war, for the French, 
 had been built and fitted out in the fea-ports of Ragu- 
 fa, and had fignified their difpleafure on that account. 
 This occafioned uneafinefs to the fenate of Ragufa, as 
 their fubjefts arc very fea-faring, and much employed 
 in the carrying-trade ; and therefore it would have been 
 inconvenient for them to have caufed any difguft againlt 
 them in the principal maritime power. Their coun- 
 tryman Bofcovich was defired to go to London, in or- 
 der to fatJsfy that court on the above-mentioned head; 
 
 and
 
 BOS [ 99 ] BOS 
 
 B./covich. and ultli this dofiie he complied cheeifully on many ac- he taught, with great apphufe, for the fpacc of fix B.ifcovith. 
 
 ^"-v— counts. His iuccels at London was equal to that at years, having at the fame time the care of the obfcrva- ~~'v " ' 
 
 Vienna. He pleaded the caufe of his countrymen ef- tory of the Royal College of Brera. Ahout the year 
 
 jfedually there, and tliat without giving any offence to 1770, the Emprefs Queen made liim piofefl'or of aftro- 
 
 the French, with whom Ragnfa foon after entered in- nomy and optics in the Palatine fehools of Milan ; re- 
 
 to a treaty of commerce. quiring of him, however, that he (lioiild continue to 
 
 Bofcovich came to London the more willingly, as improve the obfervatory of Brera ; which, under liis di- 
 
 hc was dcHrous of converling with the learned men of rettion, became one of the moft perfeA in Euiope. 
 Britain. He was received by the prelideiit and prin- Here he was extremely happy, teaching the fciences, 
 
 cipal members of the Royal Society with great rcfped; applying to his favourite ftudies, and converfiug and 
 
 and to that great body he dedicated his poem on the correfponding with men of learning and of poliflud 
 
 eclipfes of the iuu and moon, which was printed on rranncrs ; when an event happened which caufed to 
 
 this occaiion at London, in the year 1760. This is him the moft fenfible affli<ftion. In the year 177?, the 
 
 one of his works on which he himfeif put the greateft fociety to which he belonged, and to which he had 
 
 value, and it has been much efteemed by the learned, been from his youth warmly attached, was, to his great 
 
 An edition of it was publifhed at Venice the veai- follow- 
 ing, and a third at Paris, which is the moll corrcft : a 
 tranflation of it into French has likevvife been publifhed 
 at Paris. In this very elegant Latin poem lie gives 
 an exaft compend of allronomy, which ferves as an in- 
 trodudion to the fubjcift ; he then explains all that be- 
 longs to the doArine of eclipfes, and their ufe in geo- 
 
 regret and difappointment, aboliihed. They who had 
 been Jefuits were allowed no longer to teach puhh'cly ; 
 nor was there any exception made in favour of Bofco- 
 vich, neither (fuch was his humour then) would he 
 have accepted of it, though it had been offered him. 
 Propofals were made to him by feveral perfons of dif- 
 tinftion : and, after fome deliberation, he chofe Paris 
 
 graphy ; he coniiders the phenomena that are obfer- for his phice of abode ; to which he was induced by 
 
 ved in the eclipfes of the fun, and likewife of the moon ; the circumftance of his being intimately acquainted 
 
 he propoles a theorem, which is his own, concerning with the prime miniller at that court. He had not 
 
 the dillribution of light refracted from the atmofphere been many months at Paris when the univerfity of Pifa 
 
 of the earth by tlie (hadow of the moon, whieli happens fent him an invitation to go tiiilher, in order to pro- 
 
 in the lunar eclipfes ; he explains the phenomenon of fefs aftronomy. But the French minider, underftand- 
 
 the reddiilt colour which often appears in the moon ing this, declared to the minifter of Tufcany, that it 
 
 when (he is ecllpfed, of which a fufficient explication was the intention of his moft Chriftian majefty to make 
 
 had not before been given: this the author draws from his dominions agreeable to Bofcovich, by giving him 
 
 the fundamental doiStrine of Newton's theory concern- liberal appointments. In faCl he was foon naturalized, 
 
 ing light and colours; and hence takes occafion to give and two large penfions were beftowed on him : the one 
 
 a clear idea of the principal confequences of the faid as an honourable fupport, to the end that he miclit 
 
 theory. All this is clothed with a beautiful poetical 
 drefs, and is adorned with pleafant epifodes, not to men- 
 tion the learned annotations which are fubjoined. This 
 poem was compofed, for the moft part, whilft the au- 
 thor was in journeys, or by way of amufement, when 
 he was obliged to wait for the opportunities of making 
 aftronomical ohfervations. 
 
 The fellows of the Royal Society invited Bofcovich 
 to accompany fome of their nifmber to America, to ob- 
 
 profecute his fublime ftudies at his eafc^ and in affluence; 
 the other as a falary annexed to a new office, created 
 in his favour, under the name of Diicflor of Opt';rs for 
 the Sea Service, and with the fole obligation of perfecting 
 the lenfes which are ufed in achromatical tckfeopes. 
 
 At Paris he remained ten years, applying principally 
 to optics, and much regarded, not only by the moft 
 reafonable men of letters, but likewife by the princes- 
 and minifters, both of France and of other nations. 
 
 ferve the tranfit of Venus, which was to happen in the But the greateft men are not exempt from being en- 
 year 1762; but being otherwife engaged, he could not vied. Some of the French were difpleafed that a fo- 
 accept of that invitation. He intended, however, by all reigner fliould appear fuperior to themfelves ; others of 
 means to obferi-e that remarkable phenomenon, and had them could not forget that Bofcovich had difcovered 
 fixed on Conftantinople as a proper place for doing fo. and expofed their miftakes. The irrtliTion which pre- 
 He was conduced thitiicr in a Venetian man of war, and vailed too much among thofe who bore the name of 
 much honoured by one of the baylos of that republic, philofophers, waj difagreeable to him. Thefe, and other 
 who commanded the veffel ; but, to his great regret, fuch circumft.inces, made him wearied of Paris, and :ie 
 they arrived too late. He returned, by land, in the defired to revilit his friends in Italy ; for which purpofe 
 company of the Englifh ambaffador ; and a relation of he obtained leave of abfence for two years, 
 that journey was publiftied in French and afterwards in The firft place in Italy in which he made any ftay was 
 Italian. at Baflano, a town in the territories of Venice. Here, 
 During thefe journeys, Bofcovich's place in the Ro- mindful of his obligations, he printed what he had been 
 man College was well filled by fome of thofe whom he preparing for the prefs during his ftay in France ; and 
 himfelf had trained up in mathematical learning. He this compofes five volumes in large oCtavo, and is a trea- 
 was now called by the fenate of Milan to teach mathe- fure of optical and aftronomical knowledge. The fub- 
 matics in the univerfity of Pavia, with the offer of a jefts treated of in thefe volumes are as follow: A new 
 very confiderahle falary. He and his fuperiors thought inftrument for determining the refrafting and diverging 
 proper to accede to this propofal, and he was received forces of diaphanous bodies ; a demonftration of the 
 without being fubjefted to any previous examinatioit ; falfehood of the Newtonian analogy between light and 
 which was always obferved, excepting in fuch an extra- found ; the algebraic formula: regarding the focufes of 
 ordinary cafe, by the decrees of the univerfity. Here knfes, and their applications for calculating the fpheri- 
 
 N 2 city
 
 BOS 
 
 [ '100 ] 
 
 BOS 
 
 Bofcovich. city of tliofe which are to he ufed in achromatical tele- 
 ^■~~*'~~' fcopes; the corrections to be inade in ocular lenfcs, and 
 the errors of the fphericity of certain glaffes ; the caules 
 which hinder the esaft union of the lolar rays by means 
 of the great burning glaffes, and the determination of 
 the lofs arifmg from it ; the method of determining the 
 different velocities of light pafllng through different me- 
 diums by means of two dioptrical telefcopes, one com- 
 mon, the other of a new kind, containing water between 
 the objeftive glafs and the place of the image ; a new 
 kind of objeflive micrometers ; the defedls and inutility 
 of a dioptrical telefcope propofed and made at Paris, 
 which gives two images of the fame objefl, the one di- 
 left, the other inverfe, with two contrary motions of 
 moveable objefls ; mafles floating in the atmofphere, as 
 hail of an extraordinary fize, feen on the fun with the 
 telefcope, and refembling fpots ; the aftronomical re- 
 fraftions, and various methods for determining them ; 
 various methods for determining the orbits of comets 
 and of the new planet, with copious applications of thefe 
 doftrines to other alironomical fubjedts, and ftill more 
 generally to geometry and to the fcience of calculation; 
 the errors, the reflifications, and the ufe of quadrants, 
 of fextants, of aftronomical feftors, of the meridian line, 
 of telefcopes called the iiiftruments of tranfits, of the 
 meridian, and of the parallaftic machine ; the trigono- 
 metrical differential formulae, which are of fo much ufe 
 in aftronomy ; the ufe of the micrometical rhombus, ex- 
 tended to whatever oblique pofition ; the error arifing 
 from refraftions in ufing the aftronomical ring for a fun- 
 dial, and the correction to be made ; the appearing and 
 the difappearing of Saturn's ring ; the methods of de- 
 termining the rotation of the fun by means of the fpots, 
 propofed formerly by the author, and now pei-fetted ; 
 the greateft exaftnefs pofFible in determining the length 
 of a pendulum ofcillating every fecond of middle time 
 by the comparifon of terrcftrial and celeftial gravity ; a 
 compend of aftronomy for the ufe of the marine, con- 
 taining the elements of the heavenly motions, and of 
 the aftronomical inilruments to be explained to a prince 
 in the courfe of one month ; a method for determining 
 the altitude of the poles with the greatefl exaft nefs, by 
 means of a gnomon alone, where other inftruments are 
 not to be had ; the determination of the illuminated 
 edge of the moon to be obferved on the meridian ; a 
 method of uling the retrograde return of Venus to the 
 fame longitude, for determining the lefs certain elements 
 of her orbit ; a method for correfling the elements of a 
 comet, of which the longitude of the node is given, and 
 the inclination of the orbit has been found nearly ; an- 
 other method for the fame purpofe, and for finding the 
 elliptical orbit, when the parabolic one does not agree 
 with the obfervations ; a method for correfting the ele- 
 ments of a planet by three obfervations ; the projeflion 
 of an orbit inclined in the plane of the ecliptic; the pro- 
 jeftion of an orbit inclined in any other plane ; the cal- 
 culation of the aberration of the ftars, arifing from the 
 fucceflive propagation of light; fome beautiful theorems 
 belonging to triangles, which are of great ufe in aflro- 
 nomy, reduced to mofl fi.nple demoiiffrations. 
 
 After having feen the impreiTion of thefe five volumes 
 finifhed, Bofcovich left Baffano, made an excurfion to 
 Rome, and vifited his old friends there and in other 
 places of Italy. He then took up his abode at Milan, 
 and applied to the reviling of fome of his old works, 
 
 and to the conipofmg of new ones. He fet himfelf par- Bofcovich, 
 ticularly to prepare annotations and fupplements to i he '•*~^ ' -^ 
 remaining two volumes of Stay's Modern Philofophy, 
 which he had not had time to publilli looiier, and which 
 he lived not to publifli. 
 
 He was happy at Milan in the neighbourhood of 
 Brcra, where was his favourite obfcrvatory ; and in the 
 company of many friends, who were become the more 
 dear to him by his long abfence from them. But he 
 began to confider, with grief, that his two years of ab< 
 fence were drawing to an end. He was very unwilling 
 to leave Italy and return to France. He thought of 
 applying for a prolongation of his abfence; he thought 
 of making interefl at the Imperial court for fome ho- 
 nourable commiflion, which might be a pretext to him 
 for remaining at Milan : but he was afraid that the pro- 
 pofal of never returning to France might appear indeli- 
 cate and ungrateful to a nation from which he was re- 
 ceiving confidersble penfions. He apprehended that 
 thofe perfons at Paris who had before oppofed him, 
 would take occafion to tax him with ingratitude, and 
 that hence his reputation would be tarnifhed. Thefe, 
 and other fuch thoughts, occafioned a great perplexity 
 of mind, which was followed by a deep melancholy ; 
 and this could not be alleviated by the advice and com- 
 fort of his friends, becaufe by degrees he became inca- 
 pable of hearing reafon, his ideas being quite confuted, 
 and his imagination difordered. To this difagreeable 
 change the ftate of his health perhaps contributed. A 
 gout had been wandering for fome time through his 
 body, and he had caught a fevere cold ; nor would he 
 admit of medical affiftance, of which he had always been 
 very diffident. It may alfo be that his long and in- 
 tenfe application had hurt the organs of the brain, 
 which in fome manner are fubfervient to the ufe of rea- 
 fon as long as the foul is united to the body. Be that 
 as it will, during the laft five months of his life, this 
 great man, who had been fo far fuperior in reafoning to 
 his ordinary fellow-creatures, was much inferior to eve- 
 ry one of them who is endued with the right ufe of the 
 underitanding. He had indeed fome lucid intervals, 
 and once there were hopes of a recovery ; but he foon 
 relapfed, and an impofthume breaking in his breaft, put 
 an end to his mortal exiftence. He died at Milan on 
 the 13th of February 1787, in the 76th year of his age. 
 
 He was tall in ftature, of a robuft conftitution, of 3 
 pale complexion. His countenance was rather long, 
 and was expreflive of cheerfulnefs and good humour. 
 He was open, hncere, communicativ.e, and benevolent. 
 His friends fometimes regretted that he appeared to be 
 too irritable, and too fenfible of what might feem an 
 affront or negleft, which gave himfelf unneceffary un- 
 eailnefs. He was always unftained in his morals, obe- 
 dient to his fuperiors, and exaft in the performance of 
 all Chriftian duties, as became a Catholic prieft, and in 
 the obfervance of the particular rules of his order. His 
 great knowledge of the works of Nature made him em- 
 tertain the highell admiration of the power and wifdom 
 of their Creator. He faw the necefhty and advantages 
 of a divine revelation, and was fincerely attached to the 
 Chriftian religion ; having a fovereign contempt of the 
 prefumption and fooliih pride of unbelievers, and being 
 fully perfuaded that we cannot make a more noble ufe 
 of our underftandtng than by fubjetting it humbly to 
 the authority of the Supreme £eiog, who knows numr 
 
 berlefs
 
 BOS [ 101 ] BOS 
 
 Bofcovleh. beliefs truths far beyond the utmoft limits of our nar- w^re performed for hi'ni with great fokmnity by cider Borcovich. 
 
 ^— v^-" row comprehenfion, and who may juftly require our of the fcnate, who affifted at them in a body; on which ' v '" ' 
 
 belief of any of them that he fees fit to propofe to us. occafion an eloquent oration in praife of him was pro- 
 
 The death of our philofopher, who truly deferved nounced. By a decree of the fame fenate, a Latin in- 
 
 that name, was heard with regret by the learned fcription to his honour, engraved on marble, was placed 
 
 through Europe, and more than ordinary refpeft has in the principal church of their city. Of this infcrip- 
 
 been paid to his memory. At Ragufa funeral exequies tion the following is a copy : 
 
 BoscoviCHii Elogium Ragus£, 
 
 Marmore Infculptum. 
 
 ROGERIO. NlCOLAI. F. BoSCOVICHIO, 
 
 Summi. Ingenii. Viro. Philofopho. Et. Mathematico. Prasftantiffimo 
 
 Scriptori. Operum. Egregiorum 
 
 Res. Phyficas. Geometricas. Aftronomicas 
 
 Plurimls. Inventis. Suis. Audlas. Continentium 
 
 Celebriorum. Europae. Academiarum. Socio 
 
 Qui, In. Soc. Jefu. Cum. Eflet. Ac. Romas. Mathefim. Profiteretur 
 
 Benedidlo. XIV. Mandante 
 
 Multo. Lahore. Singulari. Induftria 
 
 Dimenfus. Eft. Graduni. Terreftris. Circuli 
 
 Boream. Verfus. Per. Pontificiam. Ditionem. Tranfeuntis 
 
 Ejufdemque. Ditionis. In. Nova. Tabula. Situs. Omnes. Defcripfit. 
 
 Stabilitati. Vaticano. Tholo. Reddundae 
 
 Portubus. Superi. Et. Inferi. Maris. Ad. Juftani. Altitudinem. Redigendls 
 
 Reftagnantibus. Per. Campos. Aquis. Emittendis. Commonftravit. Viam 
 
 Legatus. A. Lucenfibus. Ad. Francifcum. I. Caefarem. M. Etrurise. Ducem. 
 
 Ut. Amnes. Ab. Eorum. Agro. Averterentur. Obtinuit 
 
 Merito. Ab. lis. Inter. Patricios. Cooptatus 
 
 Mediolarum. Ad. Docendum. Mathematicas. Difciplinas. Evocatus 
 
 Braidenfem. Extruxit. Inftruxitque. Servandis. Allris. Speculam 
 
 Deletae. Turn. Societati. Suae. Superftes 
 
 Lutetise. Pariliorum. Inter. Gallias. Indigenas. Relatus 
 
 CommifFum. Sibi. Perficiunda;. In. Ufus. Maritimos. 
 
 Opticse. Munus. Adcuravit 
 
 Ampla. A. Ludovico. XV. Rege. Xmo. Attributa. Penlione 
 
 Inter. Use. Et. Poefim. Mira. Ubertate. Et. Facilitate: Excoluit 
 
 Doftas. Non. Semel. Sufcepit. Per. Europam. Perigrinationes 
 
 Mukorum. Amicitias. Gratia. Virorum. Principum. Ubiquc. Floruit 
 
 Ubique. Anirnum. Chriftianarum. Virtutura 
 
 Veraeque. Rcligionis. Studiofum. Prse fe-tulit 
 
 Ex. Galha. Italiam. Revifens. Jam. Senex 
 
 Cum. Ibi. In. Elaborandis. Edendifque. Poftrerais. Operibus 
 
 Plurimum. ContendiCTet. Et. Novis. Inchoandis. Ac. Veteribus. Abfolvendis 
 
 Sefe. Adcingeret 
 
 In Diuturnum. Incidit. Morbum. Eoque. Obiit. Mediolani 
 
 Id. Feb. An. MDCCLXXXVII. Natus. Annos LXXV. Mcnfes IX, Dies II. 
 
 Huic. Optime. Merito. De. Republica. Civi 
 
 Quod. Fidem. Atque. Operam. Suam. Eidem. Ssepe. Probaverit 
 
 In. Arduis. Apud. Exteras. Nationes 
 
 Bene. Utiliterque. Expediundis. Negotiis 
 
 Qaodque. Sui. Nominis. Celebritate. Novum. Patriae. Decus. Adtulerit 
 
 Eoft. Funebrem. Honorem. In. Hoc. Templo. Cum. Sacro. Et. Laudation^' 
 
 Publice. Delatum 
 
 Ejufdcm. Templi Curatores 
 
 Ex. Senatus. Confulto 
 
 M. P. P. 
 
 This I'nfcription was compofed by his friend and coun- more full elogium has been written by M. Fabroni ; and • 
 
 trynian the celebrated poet Benedift Stay. Zamagna, another is to be met with in the journal of Modena ; a 
 
 another of his countrymen, who had likewife been his third was publifhed at Milan by the Abbale Ricca ; 
 
 fellowjefuit, publifhed a panegyric on him in elegant and a fourth at Naples by the Dr Juh'us Bajamonti, of 
 
 Latin. A fhort encomium of him is to be found in the which a fecond edition was made in the year 1790. Of • 
 
 EJlratto della Litteratura Europea ; and another, in form this laft chiefly ufe has been made here, 
 of a letter, was directed by M. de la Lande to the Pa- But what muft fecure to Bofcovich the efteem of pof. 
 
 riiian journaMs, and by them givea to the public, A terity are his works, of the greater part of which we 
 
 have i
 
 EOS [ 102 ] 
 
 Bofcnvich. «iave already taken notice. We have mentioned, i.His duced. 
 
 '■~"v~~-' Elements of Mathematics, with his Trentife on Conic 
 Sections; 2. His many dificrtations publiihed during 
 his profeflbrlhip in the Roman college ; ^. His account 
 of his Survey of the Popv;'s Ellate ; 4. His Theory of 
 N?-tural Pinlofophy ; 5. His Poem on the Eclipfcs ; 
 6. His live volumes printed at BaiTaiio. 
 
 To thtfe we may add his hydrodynamical pieces. He 
 had made a particular ftudy of the force of running wa- 
 ter, and of its effeCls in rivers ; and he was often con- 
 fuked concerning the bell means to prevent rivers from 
 corrodino- their banks, and from overflowing the neigh- 
 bouring plains, which often happens in Italy, where the 
 Alps and Apennines pour down fo many impetuous 
 ilreams. He gave a writing oa the damages done by 
 the Tiber at Porto Felice ; another on the projeA of 
 turning the navigation to Rome from Fiumiciiio to Mac- 
 carefe ; a third on two torrents in the territory of Pe- 
 rugia ; a fourth on the bulwarks on the river Pauaro ; 
 a fifth on the river Sidone, in the territory of Placen- 
 tia ; a fixth on the entrance into the fea of the Adige. 
 He wrote other fuch -works on the bulwarks ot tiie 
 Fo ; on the harbours of Ancona, of Rimini, of Magna 
 Vacca, and Savona, befides others, almoll all which were 
 printed. He had hkewife received a coinmiflion from 
 Clement XIH. to vifit the Pomptin lakes, on the drain- 
 ing of which he drew up his opinion in writing, to 
 which he added further elucidations at the defire of 
 Pius VI. On thefe occafions he fhewed how ufeful 
 
 BOS 
 
 We fhill, thirdly, take notice of the principal Bor^vJcli*, 
 objedions madi? to it, and fubjoin the author's anfwers ^>'^eni of 
 to'the fame. We (hall, finaihu fliew how happily it u^fTl' 
 may be applied to explain the general properties or mat- j 
 
 ter, as well as the particular qualities of all the clafles 
 of bodies, which have been examined according to what 
 it teaches. j 
 
 1. In this fyftem, therefore, the whole mafs of matter. View of 
 of which all the bodies of the univerfe are compofed, J^' fcvich't 
 conlills of an exceedinjj great, vet ilill linite number ^f ')'"<'"i ™ 
 hmple, maivilihle, mcxter.ded, atoms. 1 hele atoms are philof^,pJ,_, 
 endued with repuljive and atlraSive forces, which vary 
 and change from the one to the other, according to the 
 diilance between them, in the following manner : In 
 the leaft and innermoft diftances they repel one ano- 
 ther ; and this repulfive force increafes beyond all li. 
 tnits as the dillances are diminifhed, and is confequent- 
 Iv iufficient for extinguifliing the greateft velocity, and 
 for preventing the contact of the atoms. In the fen- 
 hble dillances, this force is allraSive and decreafes, at 
 leaft fenfibly, as the fqiiares of the diftances increafe, 
 conftituting univerfal gravity, and extending beyond 
 the fphere of the nioft ditlant comets. Between tin's 
 innermoft repulfive force and the outermoil attraftive 
 one, in the infenfible diftances, many varieties and chan- 
 ges of the force, or determination to motion, take 
 place : for the repulfive force decreafes as the diftance 
 increafes. At a certain diftance it comes to vanifti en- 
 tirely ; and, when that diftance is increafed, attraftion 
 
 philofophy may be to the public ; and of this he gave begins, increafes, becomes lefs, vanilhes; and the diftance 
 
 another proof when it was referred entirely to his judge- becoming greater, the force becomes repulfive, increafes, 
 
 ment to determine whether or not the cupola of the ca- lelfens, and vanilhes as before. Many varieties and chan- 
 
 thedral of Milan could bear the weight of a very high ges of this kind happen in the infenfible diftances, fome- 
 
 fpire, which it was propofed to raife on it, and which times more rapidly, fometimes more flowly, and fome- 
 
 was actually eretted accoiding to Ins directions. times one of the forces may come to nothing, and then 
 
 His application to abftruie ftudies did notjiinder return back to the fame without paffing to the other. For 
 
 him from paying iome attention to what is more ple.i- 
 fant. We have feen that he was a poet : he was alfo 
 well acquainted with hiftory, and particularly with that 
 of the Greeks and Romans, and with tlieir antiquities. 
 He wrote a diiitrtation on an ancient villa difcovered In 
 his time upon the Tufculan Hill, and on an ancient dial 
 found there; which difi'ertation was publilhed at Rome 
 in a literary journal. He wrote likewife three letters 
 on the obelifk of Casfar Auguftus, two of which were 
 printed with his own name, and the third under the 
 name of another. 
 
 Befides all thefe works that were given to the public 
 in his lifetime, many writings of his remained in nianu- 
 fcript in the hands of different perfons, and particularly 
 with his friend M. Gaetani, and ninny more with Count 
 Michael de Sorgo, a Ragufau fenator, who inherited 
 all his papers that were in his own hands at his death. 
 Thefe, it is hoped, have either been already fent to the 
 prefs or will be fo ; as nothing came from the pen of 
 Bofcovich which was not ufeful and defcrving 10 fee 
 the light. 
 
 It now remains that we give an account of his 
 Theory of NATtRAi, Philosophy; and in doing 
 this we (liall, in thejlr/l place, lay before our readers a 
 view of this fyftem. We ftiall, in the yiion;/ place, re- 
 late, from what principles and by what fteps it was de- 
 
 all this there is full room in the diftances that are in- 
 fenfible to us, feeing the leaft part of fpace is divilible 
 in irjJinUum. Befides thefe repulfive and attraftive for- 
 ces, our atoms have that vis inertia which is admitted 
 by almoft all modern philofopliers. Thefe atoms, en- 
 dued with theie forces, conllitute the whol,' fubftance 
 of Bofcovich's fyftem; which, however fimple and fliort 
 it may appear to be, has numberlefs and very wonder- 
 ful confequences, as we ftiall fee afterwards. But, that The whole 
 a more clear idea of the whole theory may be ealily therry ei- 
 formed, we Ihall make uie of a geometrical figure well l^"""^ ''. 
 accommodated to that purpofe. The right line CAC^^^^^^^_ 
 is an axis, from which, in the point A, is drawn the plate VI. 
 right line AB at right angles. AB is confidered as an fig- 6. 
 afymptole ; on each fide of which the two curves, quite 
 fimilar and equal, DEFGHIKLMNOPQRSTVU on 
 the one iide, and D'E F'G' on the other, are placed. 
 Now, if ED be fuppofed to be afymptohcal, and be ex- 
 tended, it will Hill approach to BA, but will never 
 come to touch it. This curve ED approaches to the 
 axis C'C, comes to it in E, cuts it and departs to a 
 certain diftance in F, after which it again approaches 
 the fame axis and cuts it in G. In like manner it 
 forms the arches GHI, IKL, LMN, NOP, PQL. 
 At lall it goes on in T /> .r V, which is afymptoti- 
 cal, and approaches to the axis ; fo that the diftan- 
 ces from it are in a duplicate reciprocal proportion 
 of the diftances from the right line BA. If from 
 any points of the axis, as from a, b, d, we raife the 
 
 per.
 
 BOS [ 103 ] BOS 
 
 Ififcovith's perpendiculars a g, b r, d h, tht fegments of the axis fix conditions, let us call tlie ordinate j;, the abfcifs x, 
 
 Nan^al^^ A (7, A 3, A </, arc c:dk-d abfqlfes, and rcprefent tlie dif- ' ' ' ' ' ' 
 
 iilofophy tances of any two points of matter from one anotlier ; 
 .. and the perpendiculars rt_f, b r, dh, are called onHnalts, 
 
 and exhibit the repulfive or attra'iive force, according 
 
 as it lies on the fame fide with D, or on the other fide 
 
 of the axis. 
 
 and let it be rnjide .v x =: 2. Then let us take the values 
 of all the abfcifil-s AE, AG, AI, &c. with the nega- 
 tive fi^n, and let the turn of the fcjuares of all theft va- 
 lues be called a, the funi of the produflj of every two 
 fquares b, the fum o\ the produ6t3 ot every three, c, 
 and fa on ; and let the produfl of all of them be cai- 
 
 Bifoovich** 
 
 Svflcm cf 
 
 Natuial 
 
 Pliilorophy. 
 
 ' ^^— i 
 
 Now It is evident that, in this form of the curve line, ledy, and the number of the fame values m. All this 
 
 the ordinate a g will be increafed beyond whatever li- 
 mits, if the abfcifs A n be leiTened likewlfe beyond what- 
 ever limits ; that if this abfcifs be increafed to A b, the 
 ordinnte will be lefTened, and will pafs into b r, which 
 will ftillbe leflened as it approaches from b to Z, where 
 it will come to nothing ; that then, the axis being in- 
 creafed to A d, the ordinate will change its direth'oii in- 
 to b h, and, on the oppofite fide, will increafe at firfl 
 to F, then it will decreafe through / / as far as G, where 
 it will again vaniih, and again change its direftion in 
 m n to the former; and that, in the fame manner, it 
 will vanifh and change its direflions in all the fections 
 1, 1^, N, P, R, uutd the ordiiiates op, v s, become of a 
 eonftant direftion, and decreafe, at leall fenfibly, in a 
 reciprocal duplicate proportion of the abfciiTes A 0, 
 
 being fuppoied, let it be made z'" -\- a s. '"~"-|- b z ' 
 4- f 2 "'~^ &c. -\-/=z P. If we fuppofe P equal to no- 
 thing, it is clear that all the roots of that equation will 
 be real and pofitive ; that is, the louares only of the 
 quantities AE, AG, AT, 5cc. v/hich wdl be the values 
 of z ; and therefore, as it is .x <r: =fc \/ z, btcaufe it is 
 X X =z z, it islikcwife clear that the values of .v will be 
 both AE, AG, AI, pofitive, and AE', A'G', &t. ne- 
 gative. 
 
 This being done, let any quantity be multiplied by 
 2, providing it hath no common divifor with P, left 
 2 vanidiing, it likewife might vanifii ; and iiaving made 
 •■c an infinitefim of the firll order, it may become an 
 infinitefim of the fame, or of a lower order, as will 
 be whatever formula a'' -\- g z'~' + /j z ''~^ Sec. -{• /; 
 
 A V. Wherefore, it is manifell, that by fuch a curve which, being fuppofcd equal to 0, may have as many 
 
 ace exprefled our forces ; at firft refulfive and increafing 
 beyond all limits, the dtftances being lefTened in like 
 manner, and which deereafe, the fame diilances being 
 augmented; then vaniih, change their diredlion, and be- 
 come attraB'i'ue ; vanifh again, and become repulfive ; till 
 at lart, at fenfible diftances, they remain on the fide 
 oppofite to D, and are attradlve in a duplicate recipro- 
 cal proportion of the diftances. 
 
 We may alfo obferve that the ord'mates may increafe 
 or decreafe rapidly, as in y v, z t, or flowly, as in v x, 
 z c ; and, confequently, that the forces may increafe or 
 decreafe in like manner. We may add, that the curve 
 may return back without interfering, or even touching, 
 the axis, as iny, and may return after having touched 
 the fame axis. 
 
 Although this curve exprefTes very clearly the repul- 
 sive and attracllve forces of our fyllem, yet, at firlt 
 
 imaginary, and as many and whatever real roots, pro- 
 viding none of them be thofe of AG, AE, AI, &c. 
 either pofitive or negative. If then the whole formula 
 be multiplied by 2, let this product be called Q. 
 
 If we make P — Q/"=: 0, this equation will fatlsfy 
 the five firll conditions above mentioned ; and the va- 
 lue of QJseing properly determined, the fixth conditioD 
 alfo may be complied with. 
 
 For, in the firll place, feeing the value P and Q are 
 made equal to 0, they have no common root, and there- 
 fore no common divifor. Hence this equation cannot 
 be reduced to two by divifion; and therefore it is not 
 compofed of two equations, but is fimple, and therefore 
 exhibits one fimple continued curve, which is not com- 
 pofed of any others ; which is the fiill condition. 
 
 Secondly, The curve thus exprefied will cut the axis 
 C'AC in all the points E', G, I, S:c. and G', 5;c. and in 
 
 e fimpli- 
 
 fight, it may appear to be a complicated irregular line, them only : for it will cut that axis only in thofe points 
 But the author fhews that his curve is uniform and re- 
 gular, and may be exprefied by one uniform algebrai- 
 cal equation ; which it will he necelTiry for us to con- 
 lider, in order to give fatisfatlion to our readers, and to 
 do juftice to the theory. 
 
 Wherefore, from what we have feen, the curve mud 
 '"f 'hi* have the following fix conditions : I/?, It muft be regular wherefore, only in thofe points will j; vaniih, and 
 i_ ''™" and fimple, and not compofed of an aggregate of arches the curve cut the axis. Again, that the fame curve 
 of different curves, idly. It is neceffary that it cut the will cut it in all thefe points, is clear froin this, that in 
 axis C'AC in certain given points only, at two equal them all It will be P = 0. Wherefore it will likewife 
 diftances on each fide AE', AE, AG , AG, and fo on. be Q^ = 0; but it will not be Q_= 0, feeing there is 
 ^dly. That to every abfcifs an ordinate correfpond. 
 i^thly. That If we take equal ahfcijfes on each fide of A, 
 they have equal ordinate!, ^thly. That the right line 
 AB be an afymptote, the area BAED being afympto- 
 tical, and confequently infinite, fithly. That the arches 
 
 In which J' =: 0, and in all of them. Moreover, where 
 it will be^ = 0, it will alfo be Q_ j' =. 0; and therefore, 
 becaufe of P — Q^_v = 0, It will be P =: 0. But this 
 will happen only in thofe points In which 2 will be one 
 of the roots of the equation P = ; that is, as we have 
 feen above, in the points E, G, I, or E', G', &c. : 
 
 no common root of the equations P =r » and One, 
 it mud therefore be^ = 0, and the curve will cut the 
 axis ; and thus the lecond condition Is fatisfied. 
 
 Befides, whereas it Is P— Qje = 0, it will bejr =; 
 
 termmated by any two mterfeftlons may be varied at the abfcifs x being, however, determined, we \\-\\\ have 
 
 pleafure, and recede to any diftance from the axis C'AC, a certain determinate quantity for 2 ; and thus P, Q, 
 
 and approach at pleafure to whatever arches of what- will be determined, and the only two of the klndT 
 
 ever curves, cutting them, touching them, or ofcula- Wherefore y alfo will be fole and determined ; and 
 
 ting them, in any place and manner. therefore to every abfcifs z, one only ordinate y will 
 
 In order to find an algebraical formula exprefling correfpond. This is the third condition, 
 
 the nature of a curve line that would anfwer all thefe Again, whether x be afluraed pofitive or negative, 
 
 pro.
 
 BOS 
 
 Ei'i'covich'f providing it be of the fame length, ftill the value z zs xx 
 
 "''kf '^"^ ''\ "■'" ^^ ^^^ fame, and therefore the values of both P 
 
 I'luloi. phv ''"^ C) will be the fame : wherefore y will flill be the 
 
 V— -y— — fame. Taking, therefore, equal abfc-iffcs z on both 
 
 fides of A, the one pofilive, the other negative, they 
 
 will have equal conefponding ordinates. This is the 
 
 fourth condrtion. 
 
 If .V be lelTeiicd beyond all limits, whether it be po- 
 fitive or negative, z likewife will be leflened beyond all 
 Jimits, and will become an infinitefim of the fecond or- 
 der : wherefore, in the value P, all the terms will de- 
 creafe in in/tnilum, except in y, becaufe all the rell be- 
 fides it are multiplied by z ; and thus the value P will 
 be as yet finite. But the value Q^ which has the for- 
 mula multiplied by z, will be lelfened in injinitum, and 
 
 P 
 will be an infinitefim of the fecond order : therefore -^ 
 
 = y will be augmented in infinitum, fo as to become an 
 infinite of the fecond order. Wherefore the curve will 
 liave the right line AB for an afymptote, and the area 
 BAED will increafe in iiyfintttim : and if the ordinate 
 y be aiTumed pofitive on the fide AB, and exprefs re- 
 pulfivt forces, the afyraptotic arch ED will lie on the 
 fame fide AB. This is the fifth condition. 
 
 Now the value C) can be varied in infinite manners ; 
 fo that ftill the conditions for which It was aflumed may 
 be fulfilled ; and therefore the arches of the curve in- 
 tercepted by the interfeAions may be varied in infinite 
 manners ; fo that the firll five conditions of the curve 
 may be implemented : whence it follows that they 
 may be fo varied that the fixth condition may alfo be 
 anfwered. 
 
 For if there be given, however many, and whatever 
 arches of whatever curve, providing they be fuch that 
 they recede always from the afymptote AB, and thus 
 no right line parallel to that afymptote cut thefe arches 
 in more than one point, and in them let there be ta- 
 ken as many points as you pleaie, and as near one ano- 
 ther ; it will be eafy to aifume fuch a value of P, that 
 the curve fhall pafs through all thefe points, and the 
 fame may be varied infinitely ; fo that iliU the curve 
 will pafs through all the fame points. 
 
 Let the number of points affumed be what you pleafe 
 — I-, and, from every one of fuch points, let right lines 
 be drawn parallel to /VB, as far as the axis C'AC, which 
 muft be the ordinates of the curve that is fought ; and 
 let the abfciiTes from A to the faid ordinates be called 
 M',M', M\ &c. and the ordinates 'N','Ns 'N^, &c. 
 Let there now be taken a certain quantity Az'' + Ba' ' 
 -}-C!s''~^+G!s, and let this quantity be fuppofed equal 
 to R. Then let another fuch quantity T be aflumed, 
 fo that z vanifliing, whatfoever term of it may vanifh, 
 and fo that there be no common divifor of the value of 
 P, and of the value of R + T : which may be eafily 
 done, feeing all the divifors of the quantity P are 
 known. Let it now be made Q= R-fT, and then the 
 equation of the curve will be P — Rj — T y=o. Af- 
 ter this, let there be put in the equation Mi, M2, M3, 
 fucceflively for.Y, and Nl, N2, N3, &c. for jv ; we will 
 have a number of equations equal to r, which will con- 
 tain the values of A, B, C, . . . . G, each of them of one 
 dimenfion, in number hkewife equal to r ; and, befides, 
 we will have the given values of Mi, M2, &c. Ni, N2, 
 Nj, &c. and the arbitrary values which in T are the 
 coefficients of z. 
 
 f »34 ] 
 
 BOS 
 
 By thefe equations, which are in number r, it will Bofcovic' 
 
 be eafy to determine the values A, B, C, G, which Syilem 
 
 are likewife in number r, afTuming in the firft equation, pAi^'r"!^ 
 according to the ufual method, the value A, and fub- ' ^ ' 
 diluting it in all the fallowing equations ; by which 
 means the equations will become r — 1. Thefe, again, ' 
 by throwing out the value B, will be reduced to c — 2, 
 and fo on until we come to one only ; in which the va- 
 lue Q^being determined by means of it, going back, 
 all the preceding values will be determined, one by each 
 equation. 
 
 The values A, B, C, . . . . G, being in this manner 
 determined, in the equation P — Rji — T y—o, or P — 
 Q^y=o, it IS clear that the values Ml, M2, M3, &c. 
 being fucceflively put for .v, the values of the ordinate 
 y mull: fucceflively be Nl, N2, N3, &c. ; and, there- 
 fore, that the curve muft pafs through thefe given points 
 in thofe given curves ; and ftill the value Q_v%'ill have 
 all the preceding conditions. For z being leflened be- 
 yond whatever limits, every one of its terms will be 
 leflened beyond whatever limits, feeiiig all the terms of 
 the value of T are leflened which were thus aflumed, 
 and likewife the terms of the value R are leflened, 
 which are all multiplied by s ; and, befides this, there 
 will be no common divifor of the quantities P and (3 , 
 feeing there is none of the quantity P and R-J-T. 
 
 But if two of the neareft of the points affumed in the 
 arches of the curves, on the fame fide of the axis, be fup- 
 pofed to accede to one another beyond whatever limits, 
 and at laft to coincide, which will be done by making 
 two M equal, and likewife two N equal; then the curve 
 fought will touch the arch of the given curve ; and if 
 three fuch points coincide, they will ofculate it : nay, as 
 many points as we pleafe may be made to meet together 
 where we pleafe ; and thus we may have ofculations of 
 what order we pleafe, and as near one another as we 
 pleafe, the arch of the given curve approaching as we 
 pleafe, and at whatever diftances we pleafe, to what- 
 ever arches of whatever curves, and yet ftill preferving 
 all the fix conditions required for exprefling the law of 
 the repulfive and attratlive forces. And whereas the 
 value of T can be varied in infinite manners, the fame 
 may be done in an infinite number of ways ; and there- 
 fore a fimple curve, anfwering the given conditions, may 
 be found out in an infinite number of ways. ^ E. F. 
 
 What we have faid will, we hope, fatisfy our readers, 
 and efpecially thofe of them who are in the leaft ac- 
 quainted with high geometry, that Boicovich's curve is 
 fimple, regular, and uniform ; and that therefore the 
 law of repulfive and attraftive forces, exprelfed by it, is 
 fimple and regular. 
 
 IL If this fyftem were a mere hypothefis, it would 
 ftill be very ingenious, and, from what we fliall fay af- 
 terwards, would ftill be well adapted for explaining the 
 phenomena of nature. But its author is far from look- 
 ing upon it as an arbitrary fuppofition ; he affures us 
 that he was led to it by a chain of ftridl reafoning, from 
 evident principles. We ftiall now give an abridgement 
 of that reafoning from his Diflertations on the Law of 
 Continuity, and from his Theory of Natural Philofophy. 
 
 He tells us, then, that in tlie examination of Leib-p„Qf, „f 
 nitz's opinion of the vires •vitht, he came to confiderthe theorj 
 the collifion of bodies, and took for example two equal 
 bodies. A proceeding with fix degrees of velocity, and 
 B following with the velocity of 12 : after the colli- 
 fion,
 
 BOS 
 
 [ 105 ] 
 
 BOS 
 
 Svftem of 
 Na'ural 
 
 BoftovicVe fion, they proceed jointly with the rommon velocity 
 g. Now, in the moment of collifion, it either happens 
 that A pafles abrubtly from the velocity 6 to the velo- 
 city 9, without pafiing through the velocity 7 and 8, 
 and B pafles from 12 of velocity to 9, without pafllng 
 through II and 10 ; or elle there inuft be fome caufe 
 which accelerates the one and retards the other be- 
 fore they come to contaft. In the firil cafe, the law 
 of continuity is broken ; in the fccond, immediate con- 
 taft of bodies would be rcjeCled. Maclaurin faw this 
 difficulty, and mentioned it in his work on Neiuton's 
 Difcoveries, 1. I.e. 4. He, not having courage to re- 
 cede from the common opinion, allowed a breach, in 
 fuch cafes, of the law of continuity ; but Bofcovich 
 maintains the univerfality of the law of continuity ; and 
 holds that no bodies touch one another really and ma- 
 thematically, but only phyfically and fenfibly to us. 
 The law of ^^'' '"'"' "f <:o'il'"""ly " '^■'"^ I'y "which iniriahle quan- 
 rontinuity I'lt'us., paffing from one magnitude to another, pafs through 
 jitoved all the inlermei/iate magnitudes, ivithotit ever abruptly paf- 
 fing over any of them. This law Bofcovich proves to 
 be univerfal, in the firil place, from induftion. Thus 
 we fee that the diftances of two bodies can never be 
 chan^'ed without their paffing through all the inter- 
 mediate diilances. We fee the planets move with dif- 
 ferent velocities an J direftions ; but in this they Hill 
 obferve the law of continuity. In heavy bodies projec- 
 ted, the velocity decreafcs and increafes through all the 
 intermediate velocities : the fame happens with regard 
 to elafticity and magnetifm. No body becomes more 
 or lefs denfe without paffing through the intermediate 
 denfities. The light of the day increafes in the morn- 
 ing and decreafes at night through all the intermediate 
 poffible degrees. In a word, if we go through all na- 
 ture, we fhall fee the law of continuity ftriftly take 
 place, if all things be rightly confidered. It is true, 
 ■we fometimes make abrupt paffages in our minds ; as 
 when we compare the length of one day with that of 
 another immediately following, and lay that the fccond 
 is two or three minutes longer or (liorter than the for- 
 mer, paffing all at once, in our way of fpeaking, round 
 the globe ; but if we take all the longitudes, we fhall 
 find days of all the intermediate lengths. We likewife 
 fometimes confound a quick motion with an inftantane- 
 ous one : thus, we are apt to imagine that the ball is 
 thrown abruptly out of the gun ; but, in truth, fome 
 fpace of time is required for the gradual inflammation 
 of the powder, for the rarefadlion of the air, and for 
 the communication of motion to the ball. In like man- 
 ner, all the objeftions made againft the law of continui- 
 ij ty may be folved to fatisfaftion. 
 A. breach of But however flrong this argument from judgment 
 •Mb law rnay appear to be, yet Bofcovich goes farther, and 
 mpollible. maintains, that a breach of this law, in the proper cafes, 
 is metaphyfically impoffible. This argument he draws 
 from the very nature of continuity. It is effi^ntial to 
 continuity that, where one part of the thing continued 
 ends and another part begins, the limit be common to 
 both. Thus, when a geometrical line is divided into 
 two, an indivifible point is the common limit to both ; 
 thus time h continued; and therefore where one hour ends, 
 another immediately begins, and the common limit is 
 an indivifible inftant. Now, as all variations in variable 
 quantities are made in time, they all partake of its con- 
 tinuity ; and hence none of them can haften by an 
 Suppi. Vol. I. Part I. 
 
 abrupt palTage from one magnitude to another, without Bofcovfch** 
 paffing through the intermediate magnitudes. As we Sy(li.'m of 
 cannot pafs from the fixth hour to the ninth without pjjj'^f"'^' 
 paffing through the feventh and eighth ; becaufc, if we i^-.^.-_L' 
 did, there would be a common limit between the fixth 
 hour and the ninth, which is impoffible: fo likewife you 
 cannot go from the diilance 6 to the diftance 9 without 
 paffing through the diltanrcs 7 and 8 ; becaufc, if you 
 did, in the iullaut of pafl'agc you woidd be both at the 
 diftance 6 and at the diftance 9, which is impoffible. In 
 like manner, a body that is condcnfed or rarefied can- 
 not pafs from the dtnfity 6 to the denfity 9, or vice 
 •verfa, without paffing through the denfities 7 and 8 ; 
 becaufe, in the abrupt pafl'age, there would be two den- 
 fities, 6 and 9, in the fame inftant. The body muft 
 pafs through all the intermediate denfities. This it may 
 do quickly or flowly, but ftill it muft evidently pafs 
 through them all. The like may be faid of all variable 
 quantities ; and thence we may conclude, that the law 
 of continuity is univerfal. 
 
 But, in creation, is there not an inftance of an abrupt Obj^aions 
 pafl'age froin non-exijlence to exi/lence ? No, there is not ; "> '*!'* ' 'V/ 
 becaufe before exiftence a being is nothing, and there- *"^*^"''' 
 fore incapable of any ftate. In creation, a being does 
 not pafs from one ftate to another abruptly ; it pafles 
 over no intermediate ftate : it begins to exift and to 
 have a ftate, and exiftence is not divifible. Do we not, 
 at leaft, allow of an abrupt palfage from rcpulfive to 
 attraflive forces in our very theory itfelf? We do not. 
 Our repulfive forces diminifli, through all the interm'=. 
 diate magnitudes, down to nothing ; through which, 
 as a limit, they pafs to attraftion. In tlie building of 
 a houfe or fliip, neither of them is augmented abruptly; 
 becaufe the additions made to them are tdcfted folely 
 by a change of diftances between the parts of which 
 they are compofed : and all the intermediate diftances 
 are gone through. The like may be faid of many 
 other fuch cafes ; and ftill the law of continuity re- 
 mains firm and conftant. 
 
 Let us now apply this doftrine to the cafe above impolTibi- 
 mentioned of the collifion of two bodies. We fay that'ify of con- 
 the body B cannot pafs from the velocity 6 to the ve- ''"^ ^^' 
 locity 9 without paffing through the velocities 6 and 7 ; j"?^" 
 becaufe if it did, in the moment of contaft of the two 
 fuperficies it would have the velocit|es 6 and 9. Now 
 a body cannot have two velocities at the fatne inftant. 
 For if it had two o&ual velocities at the fame time, it 
 would be in two difl'erent places at the fame time : if 
 it had two different ^(7/.'H//'a/ velocities or deterininations 
 to a certain velocity, it would be capable of being, after 
 a given time, in two places at once — both which are 
 impoffible. It is therefore neceflary that it go through 
 the velocities 7 and 8, and through all the parts of 
 them. What we have faid of the bodies A and B may 
 be faid univerfally of all bodies. Therefore no two bo- 
 dies in motion can come to immediate contact ; but 
 their velocities muft undergo the fucceffive neceflary 
 change before contaft. And as the velocity to be ex- 
 tinguiflied may be increafed beyond all limits, an ade- 
 quate caufe to effedl this extinftion muft be admitted. 
 
 This naturally leads us to the interior repulfive forces i)„„„^.... 
 ot our lyftem ; tor the caule retarding the one body forces 
 and accelerating the other muft be a force, becaufe by 
 this we mean a determination to motion ; and it muft 
 be repulfive, becaufe it a6ls/ro« the body ; and it muft; 
 O increafc
 
 BOS [ io6 ] 15 O S 
 
 S>riovich's jncreafe beyond all limits, fteing the velocity of the in- for the eflencc of a bang, as mutt lie allowed by all Bi'dovith', 
 
 iiyfttmof cuiring bodies may be incrcatid beyond all limits. It tliofe who hold that fpii its are iiicxtendcd, Becaufe Syl^fmof 
 
 Phlof"^ hv '""'^ likcwife be mutual, brcaufe aftiun and readion are all the bodies that fall under our ftnl'es are extended, we pjiiiofoojl 
 
 nl"'''y equal, as may be proved by induftion. are apt to look upon extenfion as eilential to matter: — ^ \ 
 
 lo From thefe repulfive forces Bufcovich deduces the but this error may be corrected by reHeftion, and an 
 
 In exten !- Jnextenfion of his atoms : for this repulfion being com- idea of an iiicxtendcd atom may be formed, by confidcr- 
 
 e acorns. jj,()ji to all matter, miiil caiil'e a perfeft (implicity in the ing the nature of a mathematical point, which is the 
 
 firll elements of body. If thefe elements were extend- limit of any two contiguous parts of a line, 
 ed, and confequently compounded of particles of an in- Others again have faid, that if the elements of mat- 
 
 ferior order, thefe particles might pofiibly be feparated, ter were void t)f extenfion, there would be no diffe- 
 
 and then they might meet, and an abrupt paffage from rence between body and fpirit. But the difference be- 
 
 one velocity to another might take place, which we tween body and fpirit does not confift in the having or 
 
 have excluded from nature by induction, and by a pofi- not having extenfion ; but in this, that the atoms of 
 
 rive argument. matter are endued with repulfive and attraftive forces, ; 
 
 Befides this, by rcjecling the extenfion of the firft which fpirit has not; and fpirit has a capacity of thought 
 
 elements of matter, we get rid at once of all the difli- and volition which bodies have not. 
 culties arifing from continued extenfion in body, which We may here obfervc, that among the ancients Zeno, 
 
 have always perplexed the philofophers, and have never and among the moderns Leibnitz, held, tiiat the firft 
 
 been fatisfafforiiy explained. If the elements of matter principles of matter are inextended points. But both 
 
 are extended, each of them may be divided in Injinllum, held this opinion with the inconfiftency, that they main- 
 
 and each part may ftill be divided in injiniliim. Can tained the continued extenfion of bodies, without ever 
 
 this divifion be aftually made by the power of God or being able to ihew how continued extenfion could arife 
 
 not ? Can there be one injinite in number greater than from inextended elements. 
 
 another ? Can theie be a compound without 3 Jimple of It has been objefted likewife, that our repulfive and 
 
 the fame kind ? Thefe difficulties regard not fpace, attraftive forces are no better than the occult qualities 
 
 which is no real being ; but they wouhl regard matter of the Peripatetics. The like objeftion has been made 
 
 if it had continued extenfion. All thefe perplexities to Newton's attraftion : but the anfwcr is eafy. We 
 
 are removed by maintaining, as Bofcovich does, that the obferve the eft'efts, and take notice of them : for them 
 
 firft elements of bodies are perfeftly fimple, and there- we muft admit an adequate caufe, without being able 
 
 jj fore inextended (a). to determine, whether that caufe is an immediate law 
 
 Attraftive With regard to the exterior attraftive forces of our of the Creator, vir fome mediate inflrument that he 
 
 forces. fvftem, there can be no queftion ; feeing they conftitute makes ufe of for that purpofe. 
 
 univerfal gravity, the efletts of which we fee and feel Some are unwilling to give up the idea of motion oc- 
 
 every day. But between the interior repulfive and ex- cafioned by immediate impulfe : but can they {how a 
 
 terior attractive forces we muft admit many tranfitions good reafon why fome diftance may not occafion motion 
 
 from repulfion to attraction, and from attraftion back as well as no dijtance ? Thefe are the principal objec- 
 
 to repulfion, in infenfible dillances, which are indicated tions that have been made againft the Bolcovichian 
 
 to us by cohefion, fermentation, evaporation, and other fyftem. ij 
 
 phenomena of nature. And thus we have given, in IV. Before we proceed to the explication of pheno- Obfer»a, 
 
 iliort, Bofcovich's proofs of his whole fyftem. mena by means of our theory, we muft advert, that in tions with 
 
 OVaions III. This fyftem has been well received by the learn- the curve exprefling this theory, the abfciffes denote [^1"'^^^ 
 
 to the fyf. ed in Europe, and has contributed much to render its au- the diftances between the atoms that are under confi- 
 
 tem an- thor famous ; yet many objeftions againft it have been deration ; the ordinates give the prefent ybrcf, and the 
 
 Jwered. propofed. Some are ftartled at the rejeftion of all imme- area between any two of thefe ordinates gives the fquare 
 
 diate contadl between bodies: and indeed Bofcovich is of the velocity generated between them; the arches are 
 
 perhaps the firft of mankind who advanced that opi- either repulfive or attraftive, according as they fall up- 
 
 iiion ; but he allows that bodies approach io near to on the fame fide with the afymptotic curve EG, or on 
 
 one another, as to leave no fenfible diftance between the oppofite fide. 
 
 them ; and his repulfive forces make the fame imprcflion We muft, in the next place, confider the paffages 
 
 on the nerves of our fenfcs as the folid bodies could do. from one fide of the axis to the other. Sometimes the 
 
 And therefore this opinion of his, however new, is no- paffage is from repulfion to attraftion, at other times 
 
 wife contrary to the teftimony of our fenfes. He only from attraftion to repulfion. The firft are called limits VssvAi fA 
 
 removes a prejudice which was before univerfal. of cohefion, becaufe a particle removed from that limit cohefion, 
 
 Some fay, that they cannot even form an idea of an returns back to it ; becaufe if it is removed to a greater^' 
 
 inextended atom, and that Bofcovich reduces all mat- diftance it is attrafted back, and if it is removed nearer 
 
 ter to nothing : but certainly extenfioa is not aeceflary it is repelled back. The fecond are called limits of nan- 
 
 cohefion ; 
 
 (a) If a particle of matter Is not extended, in what refpeft does it differ from a point of fpace ? Says Bofco- 
 vich, it is endowed with attraftive and repulfive forces. "What is this it before it is thus endowed ? Does it then 
 differ from a point of fpace ? We can form no notion of any fuch difference. But a point of fpace, confidered 
 ae an individual, is diftinguiftied from another individual only by its fituation ; it is therefore immoveable, but 
 matter is moveable. Have thefe forces, then, which make matter an objeft of fenfe, any fubftratum, any thing- 
 in which they are inherent as qualities I What are the things which thefe qualities diftinguifh from each other as 
 individuals i
 
 Figure, 
 
 BOS [ >o7 ] BOS 
 
 o(covUh'* cctrfon ! becaiifc a particle removed tlience to a great- of coliefion ; for when two atoms are placed in a limit BofcovUl!*! 
 ■.yftcm of er dilbnce is repelled ftill further, and if removed near- of tliat kind, they neceflarily cohere more or lefs ftronir- ^v"'"' "' 
 J!-"""' er it is attradtcd Hill nearer. Of the firft kind are ly, according as that limit is Itronj.cr or weaker. Tiom „,'^"'""',' 
 i.^.r^E. I, N; of the fecond are G, L. Likewife, when the the cohelion uf the atoms arifcs the cohcfion of .-nm. '"'' .•; 
 curve touches the axis, it may either be an attraflive pounded particles, and confcqiuntly of fcnfible bodies, 
 part of the curve, or a repullive part. Thefe limits trom the <:ohelion of panicles arites the extenf.dn of c '\ 
 may be nearer one another, or farther away ; and the bodies; becaufe there mull always be fpace between I lie ' 
 limits of coheiion maybe ilronger or weaker, accord- particles. However, it is evident that this extcnfioti is 
 ing as the forces near them are greater or lefs. not formed of a continuity of matter ; though it may 
 Bofcovich confiders minutely the effeds of thefe va- appear to be fo to our fenfes, which cannot perceive 
 rieties of limits and forces; firft with regard to two tlie fmall intermediate diftance between the riarts of fome 
 points, then with regard to three and four, demonilra- bodies, and much lefs the diihnces between the fimple 
 ting the great variety of forces that may arife from elements of which they are compofed. 
 thefe various combinations, and (hewing how from fun- Extenfion of bodies inxolvesJi^ura/iiUly; becaufe eve- 
 pie atoms a great variety of bodies may be formed. He ry extended body mull be furrounded by fome funerfi- 
 particularly proves, that, from the various polition of cies of a certain figure ; but the fuperticies of bodies 
 the atoms, they may either always repel or always at- can never be accurately determined, upon account of 
 ompofi- traft other atoms, or do neither. Four atoms inay the inequalities in all furfaces. We take, however, that 
 on of bo- form a pyramid, eight may form a cube, and fo on, in figure for the true one which the body appears to come 
 <•• regular or irregular figures. Particles of the lowcll or- ncareft. Thus we call the earth a globe, notwilhfland- 
 der may compofe particles of a fecond order, thefe of a ing the hills and valleys that are on it. 
 third, and fo on. Thfs he exemplifies by a library, in Under the fame figure, and of the fame magnitude, 
 which the letters of the books fiiould be compofed of there may be contained very different quantities of mat- 
 fniall points, placed fo near one another as that their ter. Hence we come to the confidcration of deitfity. 
 dillance could not be perceived without the help of a That body is moft denfe which contains in the fame 
 microfcope. Here the letters will be compofed of fpa'ce the greatett number of atoms, and vice verfa. 
 points, the words of letters, and all the variety of books This denfity may be increafed beyond any given li- rj *f» 
 on different fubjedls, and in different languages, would mits by the nearer approach of tiie atoms to one ano- 
 be compofed of words In like manner, he fays, his ther. Hence a body of any given magnitude, however 
 atoms may compofe particles, thefe may compofe others fmall, may come to be divifible beyond any given li- 
 of different orders, of which may be formed various mits. 
 bodies, animal, vegetable, air, fire, water, earth, whole Mobility, which is likewife reckoned among the ge- Mobilitv 
 
 neral properties of body, is cfTcntial to our fyilem, fee- 
 ing an effential part of it confifts in forces, which are de- 
 terminations to motion, at leall in certain diftances. 
 
 Univerfal gravity in fenfible diftances is likewife a Gravity, 
 
 ,5 planets, central bodies, the whole univerfe. 
 \c fydem But to be more particular, our author proceeds to 
 \\\tA ro apply his fyfteni to mechanics, and demonilrates, with 
 count lor j^jj yfj,jl accuracy and originality, what regards the 
 
 centre of gravity, atlion and reaftion, the collifion of branch of our theory. On which fubjeft it may be ob 
 
 bodies, the centre of equilibrium, and of ofcillation. Of ferved, that perhaps our curve, after it has extended 
 
 thefe fubjefts he treats in the fecond part of his Theoiia; beyond the fphere of the comets moft diftant from the 
 
 to which we inuft refer our learned readers, as it cannot fun, may depart from its afyniptotical nature, and ap- 
 
 be eafily abridged. proach to the axis, interfedt it, and pais to repulfion. 
 
 In the third part of the faine work he proceeds to This would effedlually anfwer the objetlion made by 
 
 ,y account for the general properties of matter, beginning fome againft Newton's attraction,, when they allege, 
 
 rtnetra- with impetielraWity. This naturally flows from the in- that, from his opinion, it would follow, that the fixed 
 
 "y> terior repulfive forces, which prevent the compenetra- ftars, and all matter, would be drawn together into one 
 
 tion of any two points. Befides, as the leaft part of mafs. If fuch a repulfion takes place, it may foon pafs 
 
 fpace is divifible in iiifinitum, it is infinitely improbable again into attraftion, and form limits of cohcfion ; fo 
 
 that any two points fhould ever meet, feeing they have that our fun may be in fuch a limit with regard to the 
 
 an infinite number of other lines in which they can fixed flars, and our planetary fyftcm make oidy a fmall 
 
 move, btfides the one that would join them. But an 
 
 apparent compenetration might take place, if one body 
 
 fliould meet another with fo great a velocity as not to 
 
 give time to the repulfive forces to exert their aclion. 
 
 Thus an iron ball may pafs fwiftly near a flrong mag. 
 
 pait of the whole uiu'verfe. And this may fuifice con- 
 cerning the general propertits of matter. 
 
 Let us now defcend to fome particular clafTes of bo- Fluidity 
 dies, of which fome are fluid, others folid. The parts 
 of fluid bodies are eafily feparatcd, and eafily moved 
 
 iS 
 
 leHoa, 
 
 net, without being fenfibly attracted by it, which it round one another, becauie they are fpheiical and very 
 
 would be if it moved more flowly. Thus a ball from homogeneous ; and hence their forces are direded more 
 
 a gnn pafles through a piece of wood fo quickly as to to their centres than to one another, and their motions 
 
 make only a paiTsge for itfelf, without breaking the through one another are lefs obftrufted. Between the 
 
 neighbouring parts, which it would do were its mo- particles of fome of them tliere is very little attraction, 
 
 tion more flow. Of this kind of compenetration we as in fine fand or fmall grains of feed, which approach 
 
 have a refemblance in light pafling through pellucid bo- much to fluidity. The particles of fome others of them 
 
 dies. attraft one another fenfibly, as do tliofc of water, and 
 
 Cohefion has never been well accounted for by any ftill more thofe of mercury. This variety ariles from 
 
 phdofopher before Bofcovich. From his fyftem it fol- the various combinations of the particles thend'elves, of 
 
 Jows naturally, as we have feen in fpeaking of the limits which ve have already taken notice. But in air the 
 
 O 2 particles
 
 BOS [ 10 
 
 Bofco»ich's particles repel one another very ftrongly ; and hence 
 ''n*'" "\ '-'""■'^^ *''*' great rarefaftion, when it is not comprefi'ed 
 Philofophy 
 
 ^5 
 Solidity, 
 
 17 
 Vircofity. 
 
 28 
 
 Organiza- 
 tioa. 
 
 by an external force. Its particles muft be placed in 
 ample limits of repulfion. 
 
 Solid bodies are formed of parallclopipeds, fibres, and 
 of irregular figures. This occafions a greater cohefion 
 than in fluids, and prevents the motion of the parts 
 round one another ; fo that when one part is moved all 
 the reft follow. Of thefe bodies fome are harder, whofe 
 particles are placed in limits which have ftrong repiil- 
 - five arches within them ; others are iofter, whole parti- 
 Softnef' cles have thofe arches of repullion weaker. Some are 
 flexibility, flexible, the particles of which are placed in limitsthat 
 and elalli- have weak arches of repulfion and attraction on each 
 "^"y* fide ; and if thofe arches are (liort, the particles may 
 
 come to new limits of cohefion, and remain bent : but 
 if the arches are longer, the former repulfion and attrac- 
 tion will continue to a£t, and bring back the body to 
 its former pofition ; nay, in doing this with an accele- 
 rated velocity, the parts will pafs their former limits, 
 and vibrate backwards and forwards, as may be feen in 
 a bended fpring. Tl'.us elafticity is accounted for. 
 
 Vifcous bodies Hand in the middle between folid and 
 fluid. Their particles have lefs cohefion than the firft, 
 and more than the fecond : they Hick to other bodies 
 by an attrattion which their particles have from their 
 compofition. In like manner water itfelf flicks to fome 
 bodies, and is repelled by others. All which arifes 
 from the different compofition of the particles, which 
 gives a variety of refpettive forces. 
 
 What appears very wonderful in nature, is the com- 
 pofition of organic bodies. But if we confider that 
 particles may be fo formed, that they may repel fome 
 and attrafl others, the whole of vegetation, nutrition, 
 and fecretlon, may be underftood, and follows from our 
 fyftem. And as one particle may attract another in 
 one part only, and repel it in every other fituation, 
 hence may be gathered the orderly fituation of the par- 
 ticles in many cryftallizations. The great variety of re- 
 pulfive and attractive forces, or linjits of cohefion, of 
 the pofition of atoms, and of combinations of particles, 
 will account for all thefe phenomena. 
 
 The chemical operations, which are fo curious In 
 themfelves, and fo ufeful to fociety, are well explained 
 by Bofcovlch's fyftem, and ferve as a confirmation of its 
 truth. Of this we fliall give fome inft^nces. When 
 fome folids arc thrown into fome liquids, there hap- 
 pens to be a greater attraction between the particles of 
 the folid and of the liquid than there is between the 
 particles of the folid itfelf. Hence the particles of the 
 folid are detached and furrounded by the fluid ; this 
 mixture retaining the form of globules, and therefore 
 continuing to be fluid. This is called folutloii. But 
 when the folid particles are covered to a certain depth, 
 the attraftive forces ceafe on account of the different 
 diftances, and no more of the folid is detached. Then 
 the fluid is faid to be faturated. If into this mixture 
 another folid be put, the particles of which attraft the 
 fluid more ftrongly, and perhaps at greater diftances 
 than the particles of the former ; then the fluid will 
 abandon the former and cleave to the latter, dlflolving 
 them, and the particles of the former will fall to the 
 bottom in the form of powder, into which they had 
 been reduced by the folution. This feparation is called 
 frecifuation. Perhaps rain arifes from a precipitation 
 
 «9 
 
 Chemical 
 
 operations. 
 
 8 ] BOS 
 
 of this kind, when the aqueous particles are left by the Bnfcovich'i 
 air, which is more ftrongly attraded by fome other par- Siftcm of 
 tides floating in the atmofphere. pn"r'"h 
 
 Fluids of the fame fpccific gravity are eafily mixed ; ' ' 
 
 and even though llie fjieclfic gravity be dift'erent, the 
 particles of the one attract thofe of the other, in fucha 
 manner that they feera to form one fluid by a kind of 
 folution. Nay, it happens that two fluids mixed toge- 
 ther form a folid, becaufe their particles come to be in 
 the limits of cohefion. They may even occupy lefs 
 fpace than they did before, by being attracted into lefs 
 diftances between their parts. 
 
 Fermentation is a necclfary confequence of our fyf- 
 tem. For when bodies, whofe particles, by the variety 
 of their compofition, are endued with different forces, 
 come to be mixed, there muft arlfe an agitation of the 
 parts, and an ofcillation among them ; fometimes great- 
 er, fometimes lefs, according to the nature of the par- 
 ticles. This agitation is ilopped by the expulfion of 
 fome particles, by the intrufion of others into vacant 
 fpaces, and by the impreflion of external bodies ; but 
 always there is a change in what remains, becaufe there ( 
 
 is a new difpofition of particles. ,- 
 
 Fire confifts in a violent fermentation of fulphure- Fire and fu 
 ous matter, efpecially when it meets with the matteriion, &c. 
 of light in any quantity. This fermentation agitates 
 ftrongly the parts of other bodies, feparates them from 
 one another, and often throws them into a ftate of fu- 
 fion ; the cohellon between their parts being broken, 
 and they being thrown into a circular motion. In this 
 ftate they may be often mixed together, fo as to form 
 one body ; they may be again feparated by the aftion 
 of the fame fire, which evaporates fome of them fooner, 
 fome later. Hence the art of fmelting metals. 
 
 When, in the agitation occafioned by fire, fome of 
 the particles are thrown out into an arch of repulfion, 
 they may fly off^ and evaporate. Sometimes the whole 
 body may be thrown into a ftrong repulfion and volati- 
 lizatlon, or a fudden explotion take place ; when, be- 
 fore the particles are near an equilibrium, a fmall force 
 may occafion a great change ; as the foot of a bird may 
 occafion the fall of a great rock, which was before al- 
 moft detached from a mountain. In evaporation, the 
 bodies that remain affume a particular figure, as all 
 falts do ; and this upon account of their particles ha- 
 ving certain parts only that attraft one another, and 
 confequently occafion a particular difpofition. All 
 thefe chemical operations evidently prove that there are 
 in nature repulfive and attraftive forces between the par- 
 ticles of bodies at fmall diftances : which greatly con- 
 firms our whole fyftem. 
 
 Bofcovich holds, that light is an efflwvium, emitted Lighu 
 with great velocity from the luminous bodies by a 
 ftrong repulfion. He explains all the moft remarkable 
 properties of this extroardinary matter according to his 
 own principles, and that with great acutenefs. On this 
 fubjeft it is obfervable, that Newton faw the neceflity 
 of admitting repulfive forces for the reflexion of light, 
 which extend at fome diftance from the reflefting fur- 
 face, and therefore referable the repidfive forces of our 
 theory. ... . . 3» 
 
 Our author gives likewife a probable explication ofgig^^rjcj 
 eleftricity, according to Franklin's ingenious hypothe-aud mag! 
 fis, and likewife of magnetifm, deducing the whole ofnetiihi. 
 the appearances from various attradioDs and repulfions. 
 
 He 
 
 1
 
 iyftcm of 
 
 Naturr.l 
 
 hiliifophy. 
 
 3.1 
 
 BOS . [ 109 ] BOS 
 
 He fiippofes that fire and the elcdlrical fluid differ only Wherefore 1 do not hcfitate to maintain the above faid EorfovJch's 
 in this, that fire is in actual fermentation, and not fo principles of motion, feeing they extend widely through ''y'*"-"^ ot 
 
 all nature." From this paifagc we may fafely conclude, phiio'ibphy, 
 that the great Briti(h philufopher would have been ' 
 highly plcaftd, had he fecn all nature fo well explained 
 by the one liuiple law of forces propoftd by the Ragu- 
 
 the cleftrical fluid 
 
 Finally, he explains our bodily fenfations, in which 
 he agrees pretty much with other pliilofophers ; except- 
 ing in (his, that what they attribute to the immetliate 
 contact of bodies, or of certain particles emitted from 
 them, he afcribes to attractions and rcpullions ; which 
 indeed are particularly fit for caufing that motion in 
 cur nerves, which is fuppofed to take place in the or- 
 
 fan . 
 
 a 6 
 
 34 
 ecoucilia- 
 on of this 
 ith other 
 'Items, 
 
 Bofcovich himfelf was fo fully convinced of the truth Comi ari. 
 of his fyllem, that he was wont to make ule of tlic fol- '"" "f 'hij 
 lowing coniparifon : When a letter has been written in'?'^'^'" '°. 
 
 gans of fenfation, and to be thence communicated to occult charaders, and we arc endeavouring to decyphcra cyihtr, 
 the brain, it, we make various fuppofitions of alphabets ; and 
 
 It is to be obferved, that although Bofcovich main- when we have found one according to which the v\hule 
 tains that the very firll elements of matter are void of letter comes to have a reafonable meaning, agreeable to 
 extcnfion ; yet he allows, that of thefe elements, com- all the circumllances of time, place, perfons, and things, 
 
 we can entertain no doubt of our having difcovered the 
 true key of the cypher — fo, faid he, my fyftem explains 
 fo well all the phenomena to which it has been properly 
 applied, that I muft flatter myfelf that I have difcover- 
 ed the true kev of nature. 
 
 3^ 
 
 rpecially 
 
 lat of 
 <ewton. 
 
 bined in a certain manner, may be formed extended 
 particles of various figures, the parts of which may be 
 fo coherent as to be infeparable by any power in na- 
 ture. By thefe means the opinion of thoie philolophers, 
 who are fo fond of extended particles, may be in fo far 
 gratified. Nay, the Peripatetics may, if they pleafe, 
 adopt Bofcovich's inextended atoms for their Jllateria 
 Prima without any inconfillency ; and his repulfive and 
 attractive forces may ferve (or their Jhi/luntial forms. 
 And as God can make impreflions on our fenfes inde- 
 pendently of the atoms, their abfolute accidents may 
 in fome fenfe be admitted. Nor would ftmie fucii ex- 
 traordinary exertions of Divine Power favour idealifm 
 in the ordinary courfe of nature. 
 
 But what is of more confequence, it is more than 
 probable, that had Newton lived to be acquainted with 
 the Bofcovifchian theory, he would have paid to it a very 
 great regard. This we may conjefture from what 
 he fays in his laft queftion of optics ; where, after ha- 
 vmg mentioned thnfe things which might be explained 
 by an attractive force, fucceeded by a repulfive one on 
 a change of the diltances, he adds, *' And if all thefe 
 things are fo, then all nature will be very fimple, and 
 
 The being accuftomed to contemplate fo deeply the Ktiftence 
 univerfe and the materials of which it is compofed, inade (if God. 
 Bofcovich fee mod clearly the evident neceffity of ad- 
 mitting an all-powerful, intelligent, felf-exiftent Being, 
 for the creation of thole materials, and for the arrange- 
 ment of them into their prefent beautiful form. He 
 was at a lols to find words ftrong enough to exprefs his 
 fuj'prife, that there fhouid be any man, not to fay any 
 one pretending to the name of philoiopher, who could 
 be fo dcat as not to hear the voice of nature loudly pro- 
 claiming its Author from all, even the leaft of its parts. 
 He gives us his fentiments on this, the moft important 
 of all fubjetls, in the appendix to his Tkeorla, in which 
 he treats of God and of the foul of man. 
 
 There, in the firll place, he fhows the abfurdity of -jv ^ ,. 
 their opinion, who maintain that this world may have cannot be 
 been the work of chance, the eff'cft of a jumble of felf- theefJefi of 
 exiftent, fclf-moving atoms ; becaufe chance is an empty '^''•""^' 
 
 confiftent with itfelf, effedling all the great motions of word without a real meaning. AVhatever exifl.s has its 
 
 the heavenly bodies by the attraction of gravity, which 
 is mutual between all thofe bodies, and almoft all the lefs 
 motions of its particles by another certain attraftive and 
 repulfive force, which is mutual between thofe parti- 
 cles." And a little after, treating of the elementary 
 particles, he fays : " Now it feems that thefe eleinen- 
 tary particles not only have in themfelves the vis ineriitc, 
 and thofe paffive laws of motion which neceflarily arife 
 from that force, but that they likewife perpetually re- 
 ceive a motion from certain aftive principles ; fuch as 
 gravity, and the caufe of fermentation, and of the 
 cohefion of bodies. And I confider thefe principles, 
 not as occult qualities, which are feigned to flow from 
 the fpecific forms of things, but as univerfal laws of na- 
 ture, by which the things themfelves were formed. For 
 that truly fuch principles exilt, the phenomena of na- 
 ture fhew, although what may be their caufes has not 
 
 determinate caufe, and can only be called fortuitous by 
 us on account of cur ignorance of that caufe. Befides 
 this, though the number of atoms compofing this world 
 is finite, yet their pofiible combinations are many times 
 injimlely iiifinile : for they may be placed in infinite pla- 
 ces of an mfinite line ; of thefe lines there is an infinite 
 number in every plane, and of thefe planes there is an 
 infinite number in fpace. Again, thefe points may have 
 an infinite number ol velocities in an infinite number of 
 direftions. From all this it is evident, that the combi- 
 nations in which the points of matter may be, is infi- 
 nite in a high degree, whereas duration can be infinite, 
 in only one dimenfion. Hence it is infinitely impro- 
 bable that ever the prefent combination of things could 
 come out by chance. And this is fo much the more 
 infinitely iiuprobable, becanfe the diforderly, chaotic 
 combinations are infinitely more than the regular ones. 
 
 as yet been explained. To affirm that every fpecies of The whole of matter might roll about in a blind motion 
 
 things is endued with fpecific occult ([ualities, by which for a boundlefs eternity, without ever being capable to 
 
 they have a certain power, is indeed to fay nothing ; produce one fingle mulhroom. 
 
 but to deduce two or three general principles of mo- Moreover, had matter been in motion from all eter- 
 
 tion from the phenomena of nature, and then to explain nity, every atom would have defcribed an infinite line, 
 
 how the properties and aftion of all corporeal things and then a part of that line would be affignable at an 
 
 follow from thofe principles, this truly would be to have infinite diftance from the point of fpace in which the 
 
 made a great advancement in philofophy, although the atom is at prefent : but an infinite line can never be run 
 
 caufes ot thofe principles were not as yet ^ known, over; therefore the atom could never have come to its 
 
 prefent
 
 Eofi ovich's 
 Svftcm "f 
 
 Philofophy. 
 
 Attt ♦ utes 
 ofG d 
 v.'hich ap- 
 pear in the 
 creatiun. 
 
 41 
 
 'Nituralre- 
 iigion. 
 
 BOS r II 
 
 prefent place ; and the.etore the fuppofition is abfurd. 
 Nothing fucccdivt can be eternal with a />/»/? eternity, 
 though it can continue witiiout end. God alone can 
 be eternal and aclually infinite ; but his eternity and 
 infinity are beyond our comprehenfion. 
 
 Neither can the world have exilled of itfclf in any 
 thing like to its prefent form from all eternity ; for 
 malter is perfcdiy iiidifterent to numbcrlcfs ilates, and 
 to its prefent (late it muft be determined. This prefent 
 ftate is perfeftly incapable of determining itfclf, bccaufe 
 tliis determination mull be previous to its exilience. It 
 niuil be determined by the preceding ftate, which is al- 
 fo incapable of determining ilfelf, and for its determina- 
 tion we mull have recourfc to the ftate before. Thus, 
 though we go back to eternity, we fhall ftill find a nul- 
 lity of determination ; now an infinite fum of nothing is 
 nothing: and iheretore as the prelcnt ftate of things could 
 have no determination, it could not pofiibly exift. 
 
 It is therefore evident that there muil be a Determi- 
 ner extrinfic to the material word. This Determiner 
 muft have an infinite knowledge of all the poflible com- 
 binations, and an infinite eleftive creative power to chufe 
 and create freely the combination he pleafed, in that 
 point of eternity that he chofe, with all the numberlefs 
 eircumftances that are agreeable to him. 
 
 And here what a vaft held of contemplation is laid 
 open to a philofophic mind ! Wliat a truly infinite 
 knowledge was requifite to forefce fo many ends, and 
 fo many means requitite for obtaining thofe ends, as are 
 contained in the creation! Let us confider light, for ex- 
 ample, which was to be emitted for fo many ages from 
 fo many luminous bodies, with fo great velocity, fo as 
 ,to penetrate fo many mediums with diff^erent degrees of 
 refledllbllity and refrangibility, with fo many other won- 
 derful qualities ; at the fame time, fo many bodies were 
 to be perfectly fitted for reflefting this light in a cer- 
 tain manner, and the animal eye was to be fo formed as 
 to have a picture of vifible objecls painted on the bot- 
 tom of it. - How many particular combinations were 
 neceftary for all this ? What ftiall we fay of the fo ma- 
 ny herbs, flowers, trees, and animal bodies, as there are 
 on this our earth ? AH their kinds and fpecies, all the 
 feries of their individuals, all their parts and particles, 
 were forefeen, intended, and contrived, by one ac^ of 
 the Divine Mind. Again, how wonderful are the hea- 
 venly bodies, of what furprifing magnitude, moving in 
 the moft beautiful order, at an immenfe diftance from 
 one another ? To fay nothing of the numberlefs crea- 
 tures that are beyond the reach of the beft telefcope, or 
 below that of the microfcope. He who reflects ever fo 
 little on thefe things, muft necelfarily fee the moft evi 
 dent proofs of an infinite power, wifdom, and provi- 
 dence ; and he muft be filled with admiration and awful 
 refpeft for the Creator and Ruler of the univerfe. 
 
 Nor are we unconcerned fpcftators of this grand 
 fcene. God has been pleafed to make us enter deeply 
 into his great plan of creation. He fingled us out 
 among an infinite number of poflible human beings, in 
 order to call us into exittence at a fixed period ; and he 
 has made a vaft number of his creatiires contribute to 
 the formation of thefe wonderful machines, our bodies, 
 as likewife to our nouriftiment, to our prefervation, to 
 our neceflilies, conveniences, and gratifications. Every 
 
 o ] BOS 
 
 moment that we exift, we are enjoying a great number BodiTcn. 
 of benefits, exprefsly difigned fur us by that Supreme ~~-v— ' 
 Being. This evidently demands from us the higheft 
 degree of gratitude, love, and obedience. 
 
 Let us go a ftep ftill farther : Is it not very reafon- Revelation, 
 able to fuppole, that our God, who affords us fo many 
 inftances of his beneficence towards us in the natural 
 order, will alfo, out of compaflion to our weaknefs and 
 ignorance, have favoured us with a more full and expli- 
 cit manifeftation of himielf, of our duties towards him, 
 and of his intentions concerning us? According to Bof- ' 
 
 covich and all true philofophers, reafon itielt alone, and 
 true philofophy, point out to us the probability at leaft 
 of God's having given us a tlill better and furer guide, 
 by whofe direftion we may attain to that perfect happi- 
 nefs which we naturally thirft after, and to which we 
 muft have been defigned by our Maker. This is pro- 
 bable from reafon alone ; and of this great fa6t we are 
 afcertained by unqueftionable authority. 
 
 BOSHMEN have been generally defcribed as a di- 
 flinct race of Hottentots, who are enemies to the pafto- 
 ral life (fee BosHiEs-Men, Encycl. ) This M. Vaillant 
 affirms to be a miftake ; and we think he has complete- 
 ly proved that it is fo. " Thefe infamous wretches 
 (lays he) do not form a particular nation, nor are they 
 a people who have had their origin in tlie places where 
 they are now found. Bojhmen is a name compofed of" 
 two Dutch words, which fignify bujh-vien, or men of the 
 •woods ; and it is under this appellation that the inhabi- 
 tants of the Cape, and all the Dutch in general, whe- 
 ther in Africa or America, diftinguifli thofe malefactors 
 or affaffins who defert from the colonies, in order to 
 efcape punifliment. In a word, they are what in the 
 Britifli and French Weft India iflands are called Maroon 
 Negroes. Thefe Bofhmen, therefore, far from being a 
 diftinft fpecies, are only a promifcuous affemblage of 
 mulattoes, negroes, and maftizos, of every fpecies, and 
 fometimes of Hottentots and baiters (fee Baster, Sup- 
 plement), i\ho all differing in colour, refemble each other 
 in nothing but in villany. They are land pirates, who 
 live without laws and without difcipline, abandoned to 
 the utmoft mifery and defpair ; bafe deferters, who have 
 no other refources but plundering and crimes. They 
 retire to the fteepeft rocks and the moft inacceflible ca- 
 verns, and there they pais their lives. From thefe ele- 
 vated places they command an extenfive profpedt over 
 the furrounding plains, lie in wait for the unwary tra- 
 veller and the fcattered flocks, pour down upon them 
 with the velocity of an arrow, and iuddenly tailing up- 
 on the inhabitants and their cattle, flaughtei them with- 
 out diftinftion. Loaded with booty, and whatever they 
 can carry with them, they then repair to their gloomy 
 caves, which they never quit till, like the lions, hunger 
 again impels them to frefh maffacres. But as treachery 
 always marches with a trembling ftep, and as the pre» 
 fence of one refolute perfon is fufficient to overawe whole 
 troops of thefe banditti, they carefully fliun thofe plan- 
 tations where they are certain that the owners their.- 
 felves refide. Artifice and cunning, the ufual refources 
 of timid fouls, are the only means which they employ, 
 and the only guides that accompany them in their ex- 
 peditions." — F^aillant's Travels into the Interior Parts of 
 Africa (a). 
 
 BOSWELL 
 
 (a) Since this article was firft publiflied, a diff"erent account has been given of the Bojhmen or Bojesmans by 
 
 Mr
 
 BOS [ 1 
 
 BOSWELL (James), known to the learned world 
 ' as the author of a life of l)r Johnfori and of feveral other 
 valualile works, was born, we believe, at Auchinlcck in 
 Airlhire, in 1740. The family from which he fprung 
 was ancient and honourable. At the time of his birth 
 his father was a well employed lawyer at the Scotch 
 bar ; but was afterwards raifed to the dignity of Judge, 
 and filled that important llation with acknowledged 
 learning, probity, and honour. His title was Lord 
 Auchinleck, taken from his family inheritance ; and he 
 died in 1782 : on which occafion Dr Johnfon wrote an 
 elegant and inftruAive letter to the fubjeft of this brief 
 memorial; of which we (hall tranlcribe a paflage that 
 alludes to fome flight domellic ditferences, which did 
 not happen in vain, fince they gave rife to fuch falutary 
 advice : 
 
 " Your father's death had every circumftance that 
 could enable you to bear it. It was at a mature age, 
 and it was expefted ; and as his general life had been 
 pious, his thoughts had, doubtlefs, for many years palt, 
 been turned upon eternity. That you did not find him 
 fenlible mull doubtlefs grieve you ; his dilpofition to- 
 wards you was undoubtedly that of a kind, though not 
 of a fond father. Ivindnefs, at kait aftual, is in our 
 own power, but fondnefs is not ; and it, by negligence 
 or imprudence, you had extinguilhed his tondncfs, he 
 could not at will rekindle it. Nothing then remained 
 betvireen you but mutual forgivenefs of each other's 
 faults, and mutual defire of each other's happinefs." 
 
 The occafion of this family diffention is unknown to 
 us. It might originate in the ditlerence of their poli- 
 tical principles, Mr Bofwell being a zealous Tory, and 
 his father, as he reprefents him, a rancorous Whig ; or 
 it may have arifen from the celebrated Douglas caufe, 
 which fct many friends at variance in Scotland, and in 
 which, though Lord Auchinleck and his fon took the 
 fame fide, they took it with very different degrees of 
 ardour. The Judge faw not the propriety of illumina- 
 ting his windows when the caufe was finally decided 
 by the Houfe of Peers ; and to compel him to illumi- 
 nate, the advocate got polfeflion of a Chincfe gong, and 
 at the head of a number of young men and boys pa- 
 trolled the ftreets of Edinburgh, and made a loud and 
 exulting noife at the windows of his father's houfe, 
 where there was no fymptom difplayed of the general 
 
 joy- 
 In 1762 Mr Bofwell made his firfl journey to Lon- 
 «3on; where, under the aufpices of Dudlley the bookfel- 
 ler, he publifhed, " The Cub at Newmarket, a Tale." 
 By the title of Cub he meant to charafterife bimlelf, as 
 the reader will perceive in the following lines, which we 
 fliall give as a fpecimen of the poem : 
 
 ■ Lord Eglintoune, who loves, you know, 
 A little dafh of whim, or fo. 
 By chance a curious Cub had got, 
 Qu Scotia's mountains ne-.vlv caught. 
 
 During his ftay in London Mr Bofwell was intro- 
 duced to Dr Johnfon, with whom it is well known he 
 
 II ] BOS 
 
 continued to live in intimacy from that time till John- Bofwell. 
 fon'a death in 1784 ; and this intimacy procurer liim ''""" 
 
 the friendfhip of Burke, Goldfmith, Sir Jodiua Rey- 
 nolds, and many other men of eminence, who compofed 
 what was called The Literary Club. In the latter end 
 of 1765 he became acquainted with General Paoli when 
 on his travels ; and after his return he publifhed, in 
 1768 or 1769, his account of Corfica, with the " Jour- 
 nal of a Tour to that llland." 
 
 Of this work, which gained him fome diflinftion in 
 the world, his great friend Johnfon writes thus: " Your 
 hiftory is like all other hillories, but your journal is in 
 a very high degree curious and delightful. There is be- 
 tween the hiflory and the journal that difference which 
 there will always be found between notions borrowed 
 from without and notions generated within. Your hif- 
 tory was copied from books ; your journal rofe out of 
 your own experience and obfervation. You exprefs 
 images which operated llrongly upon yourfclf, and you 
 have impreffed them with great force upon your read- 
 ers. I know not whether I could name any narrative 
 by which curioiity is better excited or better grati" 
 fied." 
 
 In 1770 Mr Bofwell, who was then in good prac- 
 tice at the Scotch bar, married an amiable woman, by 
 whom he had two fons and three daughters, who fur- 
 vived him. In 1773 he was chofen a member of the 
 Literary Club ; and in the autumn of the fame year 
 he vifited the Hebrides in company with his illuftrious 
 friend Johnfon ; after whofe death he publifhed a very 
 entertaining account of their tour, the places they faw, 
 the charadters with whom they converfed, and their own 
 remarks on the different' converfations. To many per- 
 Ions, both in England and Scotland, this book gave 
 great offence, as it brought before the public the un- 
 guarded talk of private locial circles ; but it furely fur- 
 nifhed much entertainment, as it exhi'oited a more faith- 
 fui pifture of Hebridiaii manners than the Britifh pub- 
 lic had ever before feen. 
 
 In [784, when Mr Fox's famous India bill was be- 
 fore Parliament, Mr Bofwell publiflied a '' Letter to the • 
 People of Scotland on the Pret'ent State of the Na- 
 tion ;" in which he contends, that no charter would be 
 fafe if that bill fhould pals into a law ; and more than 
 inflnuates, that the principle of it was equally inimieai 
 to the liberties of the fubjeCt and to the prerogative of 
 
 the king. Dr Johnfon ftcros to have thought of that 
 bill as he did ; tor having read the letter, he wTites to 
 the author his approbation of it in the following words: 
 " I am very much of your opinion ; and, like you, feel 
 great indignation at the indecency with which the king , 
 is every day treated. Your paper contains very confi- • 
 derable knowledge of the hiflory and of the conilitu- - 
 tion, very properly produced and applied."" 
 
 In 1785, Mr Bofwell quitted the Scotch bar, and • 
 went to refide in London, where he continued till the 
 day of his death. Having entered himfelf in one of the 
 inns of court, and fludied the Enghlh law, he became a 
 barjjfler in England ; but we have reafou to believe 
 
 that 
 
 Mr Barrow, who travelled into the interior of Southern Africa in 1 797 and 1 798. According to him, they are 
 a dillinft race, e.ttremely favage, who neither cultivate the ground, nor breed cattle, but fubfift in part un the 
 natural produce of their country, and fupply its deficiency by depredations on the colonills oa one fide, and tke : 
 Deighbouring tribes of people that are more civilized than themfelv^s, on the other .
 
 BOS [ II 
 
 Bnfwcll. tViat his praftice there was not fo fuccefsful as it had 
 ^ ' V been in his own country. He enjoyed, however, more 
 completely than he could do in Edinburgh, the conver- 
 fation of the great, the wile, the witty, and the good ; 
 am! fnch converfation he always valued above wealth. 
 He frequently vifittd his native country, and elpecially 
 Auchinleck, the feat of his anceftors ; and foon after 
 his return from one of ttiofe vifits he was feized with 
 a diforder which proved fatal, on TuefJay the iptli of 
 May 1795. 
 
 Such were the principal events in the life of Mr Bof- 
 well. Of his charafter, it would be difficult to fay 
 ■much more than he has faid himfelf in his " Journal of a 
 Tour to the Hebrides j" and which may, with feme 
 propriety, be copied here: 
 
 " I have given a flcetch of Dr Johnfon. My readers 
 ■may wifli to know a little of his fellow-traveller. Think, 
 then, of a gentleman of ancient blood ; the pride of 
 which was his predominant paffion. He was then in 
 his 33d year, and had been about four years happily 
 married. His inclination was to be a foldier ; but his 
 father, a refpeftable Judge, had prefTed him into the 
 profeffion of the law. He had travelled a good deal, 
 and feen many varieties of human life. He had thought 
 more than any body fuppofed, and had a pretty good 
 ■ftock of general learning and knowledge. He had all 
 Dr Johnfon's principles, with fome degree of relaxation. 
 He had rather too little than too much prudence ; and 
 his imagination being lively, he often faid things of 
 which the effedl was very different from the intention. 
 He refembled fometimes 
 
 * The bed good man, with the worft-natur'd mufe.' 
 
 •' He cannot deny himfelf the vanity of finifhing with 
 the encomium of Dr Johnfon, whole friendly partiality 
 to the companion of this tour, reprefents hiin as one 
 « whofe acutenefs would help my inquiry, and whofe 
 gaiety of converfation, and civility of manners, are fuf- 
 ficient to counteraft the inconveniences of travel, in 
 countries lefs hofpltable than we have pafTed.' 
 
 Few of Mr Bofwell's friends, we believe, could add 
 much to this candid confefiion. His enemies, if he had 
 any, might dwell upon his failings; but his failings were 
 few, and Injurious to no perfon. In his charafter good 
 nature was predominant. He appeared to entertain fen- 
 tlments of benevolence to all mankind, and to be inca- 
 pable of intentionally injuring a human being. His con- 
 verfation -talents were always pleafing, and often fafci- 
 nating. But can we wonder at this in him who, with 
 a capacity to learn, had been the companion of Johnfon 
 for more than 20 years ? His attachment to the Doc- 
 tor for fo long a period, was a meritorious perfeverance 
 in the defire of knowledge. To it the world is in- 
 debted for the moll: iinifhed pifture of an eminent man 
 that ever was executed. We know there are objedlions 
 to the mode of giving the life of Johnfon. It has been 
 thought that Ignorance has been wantonly expofed, and 
 the privacy of foclal life endangered. We (hall not en- 
 ter deeply into this queftion. All that we can certain- 
 ly affirm is, that the work has been read with avidity 
 and pleafure ; and that he who does not wirti to read it 
 again may be fufpefted to be deficient in tafte and in 
 temper. 
 
 Mr Bofwell has been accufed of vanity ; but when 
 this accufation is brought againft him, it fhould not be 
 
 2 ] B O U 
 
 forgotten that he enjoyed advantages which rendered Botany. 
 that confpicuous in him from which no man can claim ''^V' 
 an exemption. We know not the man who would not ^"^"'^''' 
 have been vain to poflefs fo much of Dr Johnfon's con- " 
 vcrfation, and proud to give it to the world, in hopes 
 that he wlio venerated Johnfon would not be unthank- 
 ful to his biographer. From the Dodtor, however, he 
 appeared to his friends to have imbibed a portion of me- 
 lancholy, of which indeed he complained himfelf during 
 the lall two or three years of his life ; and he flew for 
 relief where perhaps it is beft to be found, to the fociety 
 of the learned and the gay. Here, as he confefles, he 
 «' had rather too little than too much prudence ;" and, 
 with more attachment to the aflivity of rural life, he 
 might, probably, have lengthened his days. But as his 
 " belief in revelation was unfliaken," and his religious 
 impreffions deep, and recurring frequently, let us hope 
 that he has now attained that ftate from which imper. 
 feftlon and calamity are alike excluded. 
 
 BOTANY-BAY. See Neif Holland, Encycl. ; and 
 Neiv South IValrs in this Supplement. 
 
 BOUGUER (Peter), an eminent mathematician and 
 mechanical philofopher, was born at Croific, in Lower 
 Bretagne, on the loth of February 1698. His father 
 John Bouguer, who was likewlfe a coniiderable mathe- 
 maticlan, was then profeffor royal of hydrography at 
 that port ; and under him young Bouguer ftudied ma- 
 thematics, and the application of them to fhip-buildlng, 
 almoft from the period when he began to fpeak ; fo 
 that he was a proficient in thefe fciences before he had 
 reached beyond the years of childhood. He was, how- 
 ever, removed from Croific to the Jefuits college at 
 Vannes, where, at 13 years of age, he triumphed, in a 
 public conteft, over a profeffor of mathematics, who had 
 advanced a mathematical propofition erroneoufly. Two 
 years after this he loft his father, whom he was appoint- 
 ed to fucceed in the office of hydrographer, after being 
 publicly examined, and giving the moll complete proof 
 of his being duly qualified to fill the vacant chair. He 
 was indeed qualified by prudence as well as by fcience ; 
 for however furprlfing it may be, he filled it both with 
 dignity and with abilities, though then not more than 
 15 years of age. 
 
 In the years 1727, 1729, and 173 1, he gained the 
 prizes fucceffively propofed by the Academy of Sciences 
 for effays on the bell way of equipping Ihlps with mails, 
 on the beft method of obferving at fea the height of the 
 ftars, and on the moft advantageous way of obferving 
 the declination of the magnetic needle or the variation 
 of the compafs. In 1729 he publilhed an Optical EJfay 
 upon the Gradation of Light, in which he examined the 
 intenfity of light, and determined Its degrees of diminu- 
 tion in paffing through different pellucid mediums, and 
 particularly in traverfing the earth's atmofphere. Of 
 this effay, which was written upon a fubjeft that till then 
 had not attracted the attention of phllofophcrs, the read- 
 er will find fome account in the Encyclopedia Britan- 
 nica, under the title Optics, n" 32, cScc. 
 
 In 1730 Bouguer was removed from the port of 
 Croific to that of Havre. In 1731 he obtained, in the 
 Academy of Sciences, the place of affociate geometri- 
 cian, vacant by the promotion of Maupertuis to that of 
 penfioner ; and in 1735 he was promoted to the office 
 of penfioner-aftronomer. The fame year he was fent 
 on the commiffion to South America, along with Meffrs 
 
 Godin,
 
 B O U [ II 
 
 Siingutr. Godi'n, Condamine, and JeulTieu, to determine the mea- 
 ^' » ' lure of the degrees of the meridian, and the figure of 
 the earth. In this painful and troublefome bufuuis of 
 ten years duration, chiefly among the lofty Cordeh'cr 
 mountains, our author, hefides attending to the objedl of 
 the voyage, made many fcientific obfervations ; viz. on 
 the effedl of the Cordeh'ers on the polarity of the mag- 
 netic needle; on the expanfion and contradlion of metals 
 and other fubllances, by the fudden and alternate chan- 
 ges of heat and cold among thofe mountains ; and on 
 the refraction of the atmofpherc from the tops of the 
 fame, with the fiiigular phenomenon of the fudden in- 
 creafe of the refraction, when the Har can be obferved 
 below the line of the level. He likewife afcertained the 
 laws of the denfity of the air at different heights, from 
 obfervations made at different points of thofe enormous 
 mountains j he difcovered that the mountains have an 
 effeft upon a plummet, though he did not affign the 
 quantity of that effect ; he found out a method of etli- 
 mating the errors committed by navigators in determi- 
 ning their route ; gave a new conftruftion of the log 
 for meafuring a Ihip's way ; and made feveral other ufe- 
 ful improvements. M. Bouguer made at different times 
 fome important experiments on the famous reciproca- 
 tion of the pendulum ; he invented in i 747 the Helio- 
 METER (fee that article Encycl.) ; and made many dlf- 
 coveries relating to the intenfity of light (for which fee 
 ' 0?r\cs-/ni/ex, Encycl.) His unremitting application 
 to ftudy undermined his health, and he died on the 15th 
 of Auguft 1758, in the 6ift year of his age. 
 
 Of his works which have been publifhed, the chief 
 are, i. The Figure of the Earth, determined by the 
 Obfervations made in South America, 1749, '" 4'°- 
 2. Treatife on Navigation and Pilotage, Paris, 1752, 
 in 4to. This work has been abridged by M. La Caille, 
 in one volume 8vo, 1768. 3. Treatife ou Ships, their 
 Conftruftion and Motions, in 410, 1756. 4. Optical 
 Treatife on the Gradation of Light, firfl in 1729, then 
 a new edition in 1760, in 410. 
 
 His papers that were inferted in the Memoirs of the 
 Academy are very numerous and important : as, in the 
 Memoirs for 1726, comparifon of the force of the fo- 
 lar and lunar light with that of candles ; 1731, obfer- 
 vations on the curvilinear motion of bodies in mediums ; 
 
 1732, upon the new curves called the lines of purfuit ; 
 
 1733, to determine the fpecies of conoid, to be con- 
 ftrufted upon a given bafe which is expofed to the fhock 
 of a fluid, fo that the impulfe may be the leaft poflible ; 
 determination of the orbit of comets; 1734, compari- 
 fon of the two laws which the earth and the other pla- 
 nets mull obferve in the figure which gravity caufes 
 tliem to take ; ou the curve lines proper to form the 
 arches in domes ; 1735, obfervations on the equinoxes ; 
 on the length of the pendulum ; 1736, on the length 
 of the pendulum in the torrid zone ; on the manner of 
 determining the figure of the earth by the meafure of 
 the degrees of latitude and longitude; 1739, on the 
 allronomical refractions in the torrid zone ; obfervations 
 on the lunar eclipfe of the 8th September 1737, made 
 at Quito; 1744, fliort account of the voyage to Peru 
 by the members of the Royal Academy of Sciences, to 
 meafure the degrees of the meridian near the equator,and 
 from thence to determine the figure of the earth ; 174;, 
 experiments made at Quito and divers other places in the 
 torrid zone, on the expanfion and contraftion of metals 
 
 SuppL. Vol, L Part L 
 
 3 ] B R E 
 
 by heat and cold ; on the problem of the mailing of Dou^uer, 
 fhips; I 746, treatifeonfhips, their flru(?furt and motions; . 
 
 on the impulfe of fluids upon the fore parts of pyrami- 
 doids, having their bafe a trapezium ; continuation of 
 the fhort account given in 1744 of the Toyage to Peru 
 for meafuring the earth ; 1747, on a new co;iRruftii>n 
 of the log, and other inflrumcnts for meafuring the run 
 of a fhip; i 748, of the diameters of the larger planets j 
 the new inftrument called a helionicler, proper for deter- 
 mining them, with obfervations of the fun ; obfervatioi\ 
 of the eclipfe of the moon the Hth of Angull 1748 ; 
 1749, fecond memoir on aflrononiical refractions, ob- 
 feved in the torrid zone, with remarks on the manner 
 of conftrudting the tables of them ; figure of the earth 
 determined by MM. Bouguer and Condamine, with an 
 abridgment of the expedition to Peru; fj^o, obferva- 
 tion of the lunar eclipfe of the 13th December 1750 j 
 1 75 1, on the form of bodies mofl proper to turn about 
 themfelves, when they are pufhed by one of their ex- 
 tremities, or any other point ; on the moon's patallax, 
 with the eftimation of the changes caufsd in the paral- 
 laxes by the figure of the earth ; obfer\a'.ion of the lu- 
 nar eclipfe the 2d of December 1751 ; 1752, on the 
 operations made by feamen, called correRlons ; 1753, 
 obfervation of the palTage of Mercury over the fun the 
 6th of May 1753 ; on the dilatations of the air in the 
 atmolphere ; new treatife of navigation, conlaiiiing the 
 theory and praftlce of pilotage, or working of flu'ps ; 
 1754, operations, :kc. for diilinguilfiing, among the 
 different determinations of the degree oi the meridian 
 near Paris, that which ought to be preferred ; on the 
 direftion which the firing of a plummet takes; folution 
 of the chief problems in the working of fliips ; 1755, 
 on the apparent magnitude of objeCts ; fecond memoir 
 on the chief problems in the working of fhips ; 17571 
 account of the treatife on the working of fhips ; on the 
 means of meafuring the light. 
 
 BREAD is fo effential an article of food that every 
 ufeful method of making it fhould be generally known. 
 Much has accordingly been faid on that fubjeft [Encycl. ) 
 under the titles Baking, Barm, Bread, and Yeast : 
 but, fince the laft of thcfe articles was publiflied, we 
 have feen, in Dr Townfon's Travels in Hungary, a me- 
 thod of making bread at Debrctzen ; of which, as it 
 may fometimes be adopted with advantage in this coun- 
 try, an account may, with propriety, be inferted here. '♦ 
 
 In the baking of this bread, a fubftitute is ufed for 
 yeafl, which is thus made : Two good handfuls of 
 hops are boiled in four quarts of water : this is poured 
 upon as much wheaten bran as can be well moiRened 
 by it : to this are added four or five pounds of leaven ; 
 when this is only warm, the raafs is well worked to- 
 gether to mix the different parts. This mafs is then 
 put in a warm place for 24 hours ; and after that, it is 
 divided into fmall pieces about the fize of a hen's egg, 
 or a fmall orange, which are dried by being placed 
 upon a board, and expofed to a dry air, but not to the 
 fun ; when dry, they are laid by for ufe, and may be 
 kept half a year. This is the ferment ; and it may be 
 ufed in the following manner : For a baking of fix large 
 loaves, fix good handfuls of thefe balls, broken into fiag- 
 ments, are taken and diffolved in feven or eight quarts of 
 warm water. This is poured through a fieve into one end 
 of the bread trough', and three quarts more of warm 
 water are poured through the fieve after it, and what 
 P remains
 
 B R E 
 
 [ n 
 
 Bread. 
 
 remains in tlie fieve is well pretTcd out. This liquor is 
 mixed up with fo much flour as to form a mafs of the 
 fize of a large loaf: this is lire wed over with flour; the 
 fieve, with its contents, is put upon it, and then the 
 whole is covered up warm, and left till it has rifen 
 enough, and its furface Iihs bejjiin to crack : this forms 
 the leaven. Then i 5 ipiarts of worm water, in which 
 fix handfuls of fait have been diflolved, are poured 
 through the fieve upon it, and the neceflfary quantity 
 of flour is added, and mixed and kneaded with the lea- 
 ven : this is covered up warm, and left for about an 
 hour. It is then formed into loaves, which arc kept 
 in a warm room halt au hour ; and after that, they are 
 put in the oven, where they remain two or three hours, 
 according to the fize. The great advantage of this 
 ferment is, that it may be made in great quantities at 
 a time, and kept for ufe. Might it not on this ac- 
 count be ufcful on board of fliips, and likewife for ar- 
 mies when in the field ? 
 
 Bread, in whatever way it is made, is a dear article ; 
 and it may be a defirable objeft to many of our readers 
 to know at what price the baker can afford to fell it. 
 This depends upon the price of wheat, the quantity of 
 flour which the wheat may give, the lofs at the mill, 
 the expence of grinding, and the expence of baking. 
 
 Of the price of wheat we can fay nothing with pre- 
 cifion, becaufe it varies according to the goodiiefs or 
 badnels of the crop, and other circumftances ; but a 
 bufhel of Effex wheat, Winchefter meafure, may be 
 taken, on an average, as weighing 60 lb. Sixty pounds 
 of wheat will yield, exclufive of the lofs in grinding 
 and drefllng, 45i lb. of that kind of flour which is cal- 
 led fecnn^/s ; wlilch alone is ufed, through the greateft; 
 part of England, for bread, and which makes, Indeed, 
 the bell of all bread, though not the whitefl. A peck 
 of this flour, weighing 141b. will take up between fix 
 and feveri pints of water, and give 18 lb. of excellent 
 bread ; or a bufliel of flour, weighing 56 lb. will yield 
 72 lb. of bread. The expence of baking a bulhel of 
 fuch flour is, in Effex and fome other Englilh counties, 
 about nintpence ; viz. yeaft, on an average, twopence ; 
 fait, before the late tax, one halfpenny ; and baking, 
 fix pence. 
 
 But f^coiids is not all that is got from wheat. A 
 bufliel of 60 lb. of wheat gives, befides 454^ lb. of fe- 
 conds, 13 lb. of offal, i.e. of pollards and bran; for the 
 utmofl lofs in grinding and dreffing a bufhel of wheat 
 fliould not exceed i pound 8 ounces. The millers, in- 
 deed, ufually reckon on two pounds of lofs ; but we 
 can fay, with the utmofl confidence, that the aftual 
 lofs is rather lefs than we have flated it. A correfpon- 
 dent of ours, on whofe accuracy we can depend, weigh- 
 ed, in 1795, two bufhels, Winchefler meafure, the one 
 of white and the other of red wheat, and found the 
 weight of them both to be 132 lb. This wheat was 
 ground by his own fervants, and it yielded I2l4-lb. of 
 meal, fo that there was here but i lb. loff of two bufh- 
 els, or of 122 lb. in grinding. He admits that he fuflfer- 
 cd the ftones to turn too clofe, and that the lofs fliould 
 therefore have been fomewhat greater. The meal was 
 dreffed, as the wheat had been ground, under his 6wii 
 eye ; and every poffible precaution being taken to pre- 
 vent his being deceived in the refult, he had of flour, or 
 /econds, p^llb. and of bran and pollard 2 5|lb. ; fo that 
 he loft, of two bufhels, but 2i lb. both in grinding and 
 
 4 ] B R E 
 
 drcflTing. The ofFal, or bran and pollard, being drefled 
 in a bolting mill, yielded as follows : ' 
 
 Sliarps - 6 lb. o oz. 
 
 Fine pollard 5 8 
 
 Coarfe pollard 7 8 
 
 Broad bian 5 8 
 
 Bread. 
 
 Altogether 24 8 
 There was loft, therefore, in bolting, only one pound; 
 and of the fharps, about three pounds, if fifted, would 
 have been good flour. Indeed were the fharps and fine 
 pollard to be added to the flour, the bread would, per- 
 haps, be better, and more wholefome, than without 
 fuch addition. From thefe data, which we believe to 
 be very accurate, it will be eafy to calculate, if the 
 price of wheat be given, what fhould be the price of 
 flour per bulhel and peck, the price of bread per pound, 
 and the quantity of bread that fhould be fold for a 
 fhllling. 
 
 It is a faft, however, which fliould be attended to, 
 that loaves are not always of the fame weight, though 
 made of equal quantities of the very faine dough. This 
 was fully afcertained fome years ago at Paris. On a 
 violent complaint that the bread was not always of the 
 fame ftandard weight, the bakers of the city were cal- 
 led before the police officers. They admitted the faft, 
 that loaves, baked at the fame time, and in the fame 
 oven, were feldom, if ever, of the fame weight ; but 
 they infilled that they contained, each, the ftandard 
 quantity of dough, and that the variety of weight 
 among them muft proceed from fome caufe, which they 
 did not pretend to afcertain. The matter was refer- 
 red to the Royal Academy of Sciences, which appoint- 
 ed one of its members to fuperintend, for fome days, 
 the whole procefs of baking. This being done, it was 
 found that, of loaves baked in a large oven, thofe were 
 always heavicft which occupied the centre of the oven, 
 and that the bakers were innocent of the crime with 
 which they were charged. The faft, we think, may 
 eafily be accounted for. Even in an oven there mufl 
 be fome condenfation of fteam ; and, from the very 
 fhape of the oven, the greateft quantity muft be con- 
 denfed towards the centre. Hence the loaves in the 
 centre are neceffarily wetter and heavier than thofe 
 round the circumference, if the plain of the oven has 
 been equally heated. 
 
 Brf.ad of Rice might occafionally be of great ufe in 
 many countries during a fcarcity of wheat ; but the 
 method of making it is not generally known. It is in- 
 deed impoflible to make bread of the flour of rice, which 
 is harfli and dry like fand or afhes, by treating it in the 
 manner in which wheat-flour is commonly treated; and 
 therefore it has been propofed to mix it with an equal 
 quantity of the flour of rye. But this method of ufing 
 the flour of rice is a very uncertain remedy in cafe of 
 want; fince we can have no rice-bread if we have not 
 rye. We are taught, however, in the 'Journal des Sci- 
 ences, des Letlres, et des Arts, how to make excellent 
 bread from rice alone, by a method which the author 
 of the memoir fays he learned from the natives of A- 
 merica. 
 
 According to this method of making the wiilied-for 
 bread, the firft thing to be done to the rice is, to re- 
 duce it to flour, by grinding it in a mill, or, if we ha\-c 
 not a mill, it may be done in tha following manner: 
 
 Let
 
 Brfsd, 
 
 B R R [115 
 
 Let a certain quantity of water be heated In a fiuce- 
 pan or caldron ; when the water is near l)oihn{^, let the 
 ~ rice we mean to reduce into flour be thrown into it : 
 tiie velTel is then to be taken off the fire, and the rice 
 left to foak till the Jicxt morning. It will then be found 
 at the bottom of the water, which is to be poured off, 
 and the rice p\it to drain upon a table placed in an in- 
 clined pofition. When it is dry, it mull be beat to 
 powder, and paffed through the fined ficve that can be 
 procured. 
 
 When we have brought the rice into flour, we muft 
 take as much of it as may be thought neceffary, and 
 put it into the kneading trough in which bread is ge- 
 nerally made. At the fame time we muft heat fome 
 water in a faucepan or other veficl, and, having thrown 
 into it fome handtuls of rice, we mull let them boil to- 
 gether for fome time : the quantity of rice muft be 
 fuch as to render the water very thick anil glutinous. 
 When this glutinous matter is a little cooled, it mull 
 be poured upon the rice-flour, and the whole muft be 
 well kneaded together, adding thereto a little fait, and 
 a proper quantity of leaven. We are then to cover the 
 dough with warm cloths, and to let it ftand that it 
 may rife. During the fermentation, this pafte (which, 
 when kneaded, muft have fuch a proportion of flour as 
 to render it pretty firm) becomes fo foft and liquid 
 that it feems impolfible it fliould be formed into bread. 
 It is now to be treated as follows : 
 
 While the dough is rifing, the oven muft be heated ; 
 and, when it is of a proper degree of heat, we mull 
 take a ftewpan of tin, or copper tinned, to which is 
 fixed a handle of fufficient length to reach to the end 
 of the oven. A little water muft be put into this ftew- 
 pan, which muft then be filled with the fermented palle, 
 and covered with cabbage or any other large leaves, or 
 with a flieet of paper. When this is done, the ftew- 
 pan is to be put into the oven, and pufhed forward to 
 the part where it is intended the bread (hall be baked; 
 it muft then be quickly turned upfide down. The 
 heat of the oven a6ls upon the pafte ia fuch a way as 
 to prevent its fpreading, and keeps it in the form the 
 ftewpan has given it. 
 
 In this manner pure rice-bread may be made ; it 
 comes out of the oven of a fine yellow colour, like paf- 
 try which has yolk of eggs over it. It is as agreeable 
 to the tafte as to the fight ; and may be made ufe of, 
 like wheat-bread, to put into broth, &c. It muft, how- 
 ever, be obferved, that it lofes its goodnefs very much 
 as it becomes Hale. 
 
 It may be here remarked, that the manner in which 
 Indian corn is ufed in fome countries, fOr making bread, 
 can only produce (and does in fa£l produce) very bad 
 dough, and of courfe very bad bread. To employ it 
 advantageoufly, it Ihould be treated like rice ; and it 
 may then be ufed, not only for making bread, but alfo 
 for paftry. 
 
 BREWING is an art of vaft importance, and has 
 accordingly been explained in the EncyclopiEdia Bri- 
 tannica. A few improvements, however, have been 
 made in the art, which, though not noticed in that 
 Work, feem to be worthy of general attention, and, 
 therefore, to deferve a place in this Supplement. The 
 lirft, of which we fliall give an account, is an invention 
 of Mr William Ker of KerfieU, in the county of 
 Tweedale, for the faving of hops, and, at the fame 
 
 ] K II E 
 
 time, giving to the liquor, whether ale, beer, or porter, 
 a fupcrior flavour and quality. 
 
 The fteam which aril'es from the boiling copper is 
 known to be ftrongly impregnated with the effentlal 
 od ot the hops, in which their flavour confifts. In- 
 ftead, therefore, of allowing it to tfcape and evaporate, 
 as it does in the common mode of brewing, Mr Ker 
 contrives to preferve and condenfe it, by means of a 
 winding-pipe fixed to the copper, fimilar to the worm 
 of a ftill, or by a ftraight pipe pafling through cold 
 water, or any other cooling medium. The oil and wa- 
 ter, thus obtained, are returned Into the worts when 
 boiled, or the oil, after being feparated from the water, 
 along with which it had been exhaled, is returned into 
 the worts after they are boiled ; and the watery part, 
 which, after the oil is feparated, ftill continues impreg- 
 nated with the aromatic tafte and bitter of the hop, is 
 returned into the next copper or boiling-vefl'el ; and fi> 
 on from one copper or boiling-veflel into another. By 
 this procefs a confiderable part of the hop and flavour, 
 which is loft in the ordinary mode of brewing, is pre- 
 ferved : the flavour of the liquor is improved by the 
 prefervation of the finer parts of the aromatic oil : and 
 the ale and beer are better fecured from any tendency 
 to acidity or putrefaftion, and therefore muft be titter 
 for home conl'umption and exportation. For thia inven- 
 tion, vvhich is certainly fimple, and we think rational, 
 Mr Ker obtained a patent, dated March 4. 1 ySK. 
 
 On the 4th of June 1790, Mr John Long oi Long. 
 ■o'llle, in the county of Dublin, Ireland, obtained a pa- 
 tent for an improvement in brewing, refembling, in one 
 particular, this invention of Mr Ker's. To his inven. 
 tion, however, he gives the name of an entire new me- 
 thod, in all the ejfent'tal parts, of brewing good malt li- 
 quor ; and therefore, as it comprehends the whole pro- 
 cefs of brewing, we ftiall lay it before our readers in 
 the words of its author. 
 
 " I. For the better extrafting from malt, place near 
 a mafti tun a Ihallow copper or other veflel that will 
 readily heat ; the curb of which to be on a level with 
 the tun, and to contain from two to fix hogflieads, ac- 
 cording to the dimenlion of the tun, more or lefs; and, 
 at the lower end of the copper, have a cock from two 
 to five inches diameter, more or lefs, to condudl the 
 heated liquor from the copper into a tube which paf- 
 fes down the external part of the tun, and enters it 
 through an aperture about fix inches from the bottom; 
 then forming two revolutions, more or lefs, through the 
 body of the tun, and communicating its heat to the 
 wort as it pafles through the tube; and then, at a con- 
 venient dillance from the place it firft entered, it runs 
 from the tun into a ciftern or tub, fituate as near as 
 convenient to tlni copper or heatlng-velfel. In the tub 
 or ciftern is to be placed a pump, for the purpofe of 
 conveying the cooler liquor back to the copper or heat- 
 ing-vcffel again ; there to receive the heat of 208 de- 
 grees, more or lefs (which it will require after the firll 
 half-hour), and then convey it through the mafliing-tun 
 as before, and in the fame manner, as long as the work- 
 ing brewer or dilliller may think neceflary, to raife the 
 mafliing tun to any degree of heat required. By ad- 
 hering to the foregoing procefs, the lirft liquor may, 
 with the greateft fafety, be let upon the malt from 
 20 to 30 degrees lower than the prefent praftice ; by 
 which means it operates with gentlenefs, opens and ex- 
 P 2 panda 
 
 Brrwing.
 
 B R E 
 
 [ ii6 ] 
 
 B R 1 
 
 Brewing, pands the malt and raw corn, and prepares it for the 
 '""'"^'""^ reception of fharper or warmer liquor, fo as to extraft 
 the whole of the facchariiie quality from the malt and 
 raw corn. By the foregoing method, the mafliing-tun, 
 inllead of loliiig its firil heat (which it does by the 
 prelent praiftioi:), continues to iiicrcafe in heat every 
 moment, by conveying the heated liquor through the 
 tube into the tun ; by which means, at the end of two 
 hours, the working brewer or dilliller can have the tun 
 brought to any degree of heat he niall think bed fuited 
 to the diflertnt qnahties of the rnait or raw corn. Per- 
 fons wiio would wilh to fave expence, may heat their 
 malhing-t>in at the fide or bottom by a large piece of 
 metallic fubtlance made fire proof, and fixed therein ; 
 which, in fome degree, will anfwer the end propofed, 
 but with great trouble and delay. 
 
 " 2. To prevent the wort from receiving a difagree- 
 able flavour while in the under-back, a tube muft be 
 placed at the cock of the madiing-tun, to receive the 
 wort as it comes off, and convey it to a great cittern 
 or refrigeratory, which is fupplied with a ftream of 
 water. The wort, paffing through that medium in a 
 fpiral tube, foon lofes that heat which fo often proves 
 prejudicial to the brewer and diftiUer in warm weather: 
 then pafs it from the tube into a veflel in which pumps 
 are placed, to return the worts into the copper for the 
 purpofe of boiling off. All veffels for receiving the 
 cold wort muft be placed lower than the fource whence 
 the wort comes. 
 
 «' ^. As the great objeft of long boiling the wort is 
 remedied, by my invention of taking the extradl from 
 the hops in a feparate manner from the worts, I boil 
 my worts no longer than from 1 5 to 20 minutes ; and, 
 by purfuing that method, 1 fave much time and fuel, 
 and regulate my lengths accordingly. _ 
 
 «« 4. I fteep my hops, the preceding day to which 
 they are to be ufed, in a copper or other veffel, with 
 as much fluid, blood-warm, as will cover the hops, where 
 it is to remain over a flow fire at leaft 14 hours, clofe 
 covered ; the copper at the tenth hour not to be of a 
 greater heat than 175 degrees, continuing flow until 
 the lad hour. Then I bring the copper gradually to 
 a fimmer or flow boil ; in which ftate I let it remain 
 about 10 minutes, and then run off the fluid ; and this 
 1 do at the fame time the firft wort is boiled oft", that 
 they may both pafs together through the refrigeratory 
 into the fermentation or working tun. After the fore- 
 going operation, I cover the hops again with other li- 
 quor, and bring the copper to boil as foon as conve- 
 nient, and let it remain in that ftate a confiderable 
 time, until the fecond worts are boiled off. Then I 
 pafs the hop-fluid with the wort, the fame as in the 
 firft inflance ; and, if there is a third wort, I boil my 
 hops a third time with fmall worts, and pafs it off as 
 before ; by which means I gradually obtain the whole 
 of the effential oil and pleafing bitter from the hops, 
 which is effeftually prefervcd in the beer, 
 
 " r. To cool worts. When the wort is boiled off, 
 it is conduced from the cock of the copper or boiler 
 into a tube of a proper dimenfion, which paffes the 
 wort from the cock to the large ciflern or refrigerato- 
 ry, and there performs feveral revolutions, in a fpiral 
 manner, through the fame tube ; which is immeifed in 
 conftant fupply of cold water, where it lufes the greateft 
 Tart of its heat in a fliort time, and tkence continues a 
 
 ftraight courfe tlirough the tube, a little elevated and Brewing 
 of a fuitable length, placed in brick-work, until it meets . II 
 a fmall refrigeratory, fupplied with colder water from a . """''^X' 
 rcfervoir made for that purpofe at the head of the 
 works ; whence a continual flream runs on the furface 
 of the tube down to the great refrigeratory, cooling 
 the wort as it paffes, in order to enable the working 
 brewer or dilliller to fend it into the backs or working, 
 tuns at whatever degree of heat he fhall think proper. 
 There is no other difference between brewer and difliller 
 in this procefs, but that the difliller immediately paffes 
 the ttrong wort from the mafliing-tun to the back, thro' 
 the fame machinery above inferted, and the tubes may 
 be made of lead, or any other metallic fubllance. 
 
 " 6. To enable me to brew in the warm fummer 
 months, I fink my backs or working-tuns at leaft to a 
 level with the ground, but if deeper the better, and co- 
 ver thein clolely by an arch made of bricks, or other 
 materials, that will totally exclude the atmofpheric air 
 from them. I place them as near as poffible to a fpring 
 or fand-drain, as their depth will naturally draw the wa- 
 ter thence, which muft be fo contrived as to pafs or 
 flow round the backs or tuns. I then introduce a large 
 tube, which paffes through the tuns, and keeps the 
 wort feveral degrees lower than can poffibly be done by 
 the prefent prattice ; by which means I can produce a 
 complete fermentation even in the dog-days. 
 
 " 7. In cold or frofty weather, if the tun and backs 
 Ihould lofe the firft heat, intended to carry it through 
 the procefs by the foregoing method, you may convey 
 a fupply of warm or boKing water by the tube, which 
 paffes through the body of the backs or tun, communi- 
 cating its heat, which rifes to any degree the working 
 brewer fhall think proper : by purfuing this method, in 
 the coldefl feafon, I never want a fermentation." 
 
 We regret that we cannot wilh propriety ftate to 
 our readers, under this article, a fummary of Mr Rich- 
 ardfon of Hull's Philofophical Principles of Breiving ; 
 for as the author has a new edition of his work in the 
 prefs, it is our duty rather to refer to it, than to quote 
 from a former edition, which contains not his laft im- 
 provements. See Feriwentation and Malt, in this 
 Supplement. 
 
 BRIDEALE. See Scotale in this Supplement, 
 
 BRIDGE. See that article (Encycl.J, and Arch 
 
 in this Supplement. A luooden-hriA^K, of large fpan, 
 
 fhould be conftrufled on the principles explained under 
 
 the title Roof [Encycl.) See alfo Centre {^Suppl.) 
 
 BRINDLEY (James), was born at Tunfted, in 
 the parifli of Wormhill, Derbyftiire, in 1716. His fa- 
 ther was a fmal! freeholder, who diffipated his property 
 in company and field amufements, and neglefted his fa- 
 mily. In confequence, young Brindley was left defti- 
 tute of even the common rudiments of education, and 
 till the age of 17 was cafually employed in ruftic la- 
 bours. At that period he bound himfelf apprentice to 
 one Bennet, a mill-wright at Macclesfield, in Chefhire, 
 where his mechanical genius prefently developed itfelf. 
 The mafter being frequently abfent, the apprentice was 
 often left for weeks together to finifli pieces of works 
 concerning which he had received no inftruftion ; and 
 Bennet, on his return, was often greatly aftonifhed to 
 fee improvements in various parts of mechanifm, of 
 which he had no previous conception. It was not long 
 before the miilers difcovered Brindley's merits, and pre- 
 ferred.
 
 B R I 
 
 Brindley. ferred tiim in the execution of tlieir orJers to the maf- 
 •" V ' ter or any other workman. At the expiration of his 
 fervitude, Ben net being grown into years, he took the 
 management of the bufmefs upon himfelf, and by liis 
 fliill and indullry contributed to fupport liis old nudler 
 and his family in a comfortable manner. 
 
 In procefs of time Brindley, fet up as a mill-wright 
 on his own account ; and by a number of new and in- 
 genious contrivances greatly improved that branch of 
 mechanics, and acquired a high reputation in the neigh- 
 bourhood. His fame extending to a wider circle, he 
 was employed, in 1752, to ereft a water-engine at Clif- 
 ton, in Lancafhire, for the purpofe of draining fome coal 
 mines. Here he gave an eday of his abilities in a kind 
 of work for which he was afterwards lo much dillin- 
 gui/hed, driving a tunnel under ground through a rock 
 nearly 600 yards in length, by which water was brought 
 out of the Irwell for the purpofe of turning a wheel 
 fixed ^o feet below the furface of the earth. In 17 J5 
 he was employed to execute the larger wheels for a lilk 
 mill at Congleton : and another perfon, who was enga- 
 ged to make other parts of the machinery, and to fu- 
 perintend the whole, proving incapable of completing 
 the work, the bulinefs was entirely committed to Brind- 
 ley ; who not only executed the original plan in a maf- 
 terly manner, but made the addition of many curious 
 and valuable improvements, as well in the conftruftion 
 of the engine itfelf, as in tlie method of making the 
 wheels and pinions belonging to it. About this time, 
 too, the mills for grinding flints in the Staffordlhire 
 potteries received various ufeful improvements from his 
 ingenuity. 
 
 In the year 1756 he undertook to ereft a fteam en- 
 gine, upon a new plan, at Newcaftle-under-Line ; and 
 he was, for a time, very intent upon a variety of con- 
 trivances for improving this ufeful piece of mechanifm. 
 But from thefe deligns he was, happily for the public, 
 called away to take the lead in what the event has pro- 
 ved to be a national concern of capital importance — the 
 projefting the fyftem of canal navigation. The Duke 
 of Bridgevi'ater, who had formed his dcfign of carrying 
 a canal from his coal-works at Worfley to Manchefter, 
 was induced by the reputation of Mr Brindley to confult 
 him on the execution of it ; and having the fagacity 
 to perceive, and ftrength of mind to confide in, the ori- 
 ginal and commanding abilities of this felf-taught ge- 
 nius, he committed to him the management of the ar- 
 duous undertaking. The nature of this enterprife has 
 already been deferibed [Emycl. vol. IV. p. 8c.) ; it is 
 enough here to mention, that Mr Brindley, from the 
 very firft, adopted thofe leading principles, in the pro- 
 jefting of thefe works, which he ever after adhered to, 
 and in which he has been imitated by all fucceeding 
 artifts. To prefeuve as much as polhble the level of his 
 canals, and to avoid the mixture and interference of all 
 natural flreams, were objedls at which he conftantly 
 aimed. To accomplifh thefe, no labour or expence 
 was fpared ; and his genius feemed to delight in over- 
 coming all obllacles by the dilicovery of n^w and ex- 
 traordinary contrivances. 
 
 The moft experienced engineers upon former fyftems 
 were amazed and confounded at his projedts of aque- 
 duft bridges over navigable rivers, mounds acrofs deep 
 valleys, and fubterraneous tunnels ; nor could they be- 
 lieve in the prafticability of fome of thefe fchemes till 
 
 [ i'7 ] 
 
 B R I 
 
 they faw them effrftcd. In the execution, the ideas Brindley. 
 he followed were all his own ; and the nilnnteft, as well *'~~v— 
 as the greatell, of the expedients he employed, bore the 
 llamp of oiiginality. Every man of genius is an en- 
 thufKill. Mr Brindley was an enthufiail in favour of 
 the fupcriority of canal navigations above thofe of ri- ' 
 
 vers ; and this triumph of art over nature led him to 
 view with a fort of contempt the winding flream, in 
 which the lover of rural beauty fo much delights. This 
 fentiment he is fiiid to have exprefTed in a llrikiTig man- 
 ner at an examination before a committee of the Houfe 
 of Commons, when, on being afked, after having made 
 fome contcmpttious remarks relative to rivers, wliat he 
 conceived they were created for? he anfwered, " to feed 
 navigable canals." A diretl rivalry with the naviga- 
 tion of the Irwell and Merfey was the bold cnterprize 
 of his firlt great canai ; and fince the fuccefs of that 
 defign, it has become common, all over the kingdom, 
 to fee canals accompanying, with infulting parallel, the 
 courfe of navigable rivers. 
 
 After the fuccefsful execution of the Duke of Bridge- 
 water's canal to the Merfey, Mr Brindley was employ, 
 ed in the revived defign of carrying a canal from that 
 river to the Trent, through the counties of Cheller and 
 Stafford. This undertaking commenced in the year 
 1766 ; and from the great ideas it opened to the mind 
 of its conduilor, of a fcheme of inland navigation which 
 (hould conneft all the internal parts of England with 
 each other, and with the principal fca-ports, by means 
 of branches from this main item, he gave it the empha- 
 tical name of the giand trunk. In executing this, he 
 was called upon to employ all the refources of his in- 
 vention, on account of the inequality and various na- 
 ture of the ground to be cut through : in particular, 
 the hill of Harecallle, which was only to be pafTed by 
 a tunnel of great length, bored through flrata of dif- 
 ferent confiftency, and fome of them mere quickfand, 
 proved to be a mofl difficult, as well as txpenfive, 
 obllacle, which, however, he completely furmounted. 
 While this was carrying on, a branch from the grand 
 trunk, to join the Severn near Bewdly, was committed 
 to his management, and was finifiied in 1772. He alfo 
 executed a canal from Droitwieh to the Severn ; and 
 he planned the Coventry canal, and for fome time fu- 
 perintended its execution ; but on account of fome dif- 
 feience in opinion, he refigned that office. The Chcf- 
 terfield canal was the lad undertaking of the kind which 
 he conduced, but he only livedno finifli fome miles of 
 it. There was, however, fcarcely any defign of canal- 
 navigation fet on foot in the kingdom, during the lat- ^ 
 ter years of his life, in which he was not confulted, 
 and the plan of which he did not either entirely form, 
 or revife and improve. All thefe it is needlefs to enu- 
 merate ; but, as an infl;ance of the vaftnefs of his ideas, 
 it may be mentioned, that on planning a canal from Li- 
 verpool to join that of the Duke of Bridgewater at 
 Runcorn, it was part of his intention to carry it, by an 
 aqueduA bridge, acrofs the Merfey, at Runcorn Gap, 
 a place where a tide, fometimes rifing fourteen feet, rufties 
 with great rapidity through a fudden contraAion of the 
 channel. As a mechanic and engineer, he was like- 
 wife confulted on other occafions; as with refpeft to 
 the draining of the low lands in different parts of Lin- 
 colnfhire and the Ifle of Ely, and to the cleanfing of 
 the docks of Liverpool from mud. He pointed out z. 
 
 method,.
 
 B 11 I , [II 
 
 Brindley. mttliod, which has been fuccefsfully pradlifcd, of build- 
 
 '^'~^'~~~ iiig fea-walls without mortar ; and he was the author 
 
 of a very ingenious improvement of tlie machine for 
 
 drawing water out of mines by the contrivance of a lo- 
 
 . iiiig and a gaining bucket. 
 
 The intenfity of apph'cation which all his various and 
 complicated employments required, probably shortened 
 his days ; as the number ot his undertakings, in fome 
 degree, Impaired his ufefulnefs. He fell into a kind of 
 clironic fever, which, after continuing lome years, with 
 little intermifiion, at length wore out his frame, and put a 
 period to his life on September 27. 1772, in the 56th year 
 of his age. He died at Tunhuvft, in Staffordihire, and 
 was buried at New Chapel in the fame county. 
 
 "In appearance and manners, as well as in acquire- 
 ment, Mr Brindley was a mere peafant. Unlettered, 
 and rude of fpeech, it was eafier for him to devile 
 ■ means for executing a defign than to communicate his 
 'ideas concerning it to otiiers. Formed by nature for 
 the profefiion he affumed, it was there alone that he 
 was in his proper element ; and fo occupied was his 
 mind with his bufinefs, that he was incapable of relax- 
 ing in any of the common amufements of life. As he 
 had not the ideas of other men to affift him, whenever 
 a point of difficulty in contrivance occurred, it was his 
 cuftom to retire to his bed, where, in perfeft folitude, 
 he would lie for one, two, or three days, pondering the 
 matter in his mind till the requifite expedient had pre- 
 fented itfelf. This is that true infpiration which poets 
 have almoft exclufively arrogated to themfelves, but 
 which men of original genius in every walk are actua- 
 ted by, when, from the operation of the mind adling 
 upon itfelf, without the intrufion of foreign notions, 
 they create and invent. 
 
 A remarkably retentive memory was one of the ef- 
 fential qualities which Mr Brindley brought to his men- 
 tal operations. This enabled him to execute all the 
 parts of the mod complex machine in due order, with- 
 out any help of models or drawings, provided he had 
 once accurately fettled the whole plan in his mind. In 
 his calculations of the powers of machines, he followed 
 a plan peculiar to himfelf ; but, indeed, the only one 
 he could follow without inflruftion in the rules of art. 
 He would work the queftion fome time in his head, 
 and then fet down the refnit in figures. Then taking 
 it up in this ftage, he would again proceed by a mental 
 operaiion to another refult ; and thus he would go on 
 by ftages till the whole was finifhcd, only making ufe 
 of figures to mark the feveral refults of his operations. 
 But though, by the wonderful powers of native genius, 
 he was thus enabled to get over his want of artificial 
 method to a certain degree ; yet there is no doubt that 
 when his concerns became extremely complicated, with 
 accounts of various kinds to keep, and calculations of 
 all forts to form, he could not avoid that perplexity 
 and embarraflrnent which a readinefs in the proccfl'es 
 carried on by pen and paper can alone obviate. His 
 eftimates of expence have generally proved wide of rea- 
 lity ; and he feeras to have been better qualified to be 
 the contriver, than the manager of a great defign. His 
 moral qualities were, however, highly refpedlable. He 
 was far above envy and jealoufy, and freely communi- 
 cated his improvements to perfons capable of receiving 
 and executing them ; taking a liberal fatisfaftion in 
 forming a new generation of engineers able to proceed 
 
 8 ] B R I 
 
 with the great plans in the fuccefs of which he was fo E iSit, 
 deeply iiiterefted. Hii integrity and regard to the ad- '~~V—" 
 vantage of his employers were unimpeachable. In fine, 
 the name of Brindley will ever keep a place among that 
 fmall number of mankind who form eras in the art or 
 fcience to which they devote jhemfelves, by a large and 
 durable extenfion of its limits. 
 
 BRISSOT (J. P.), acted fo confpicuous a part in 
 the French revolution, that a fair detail of the principal 
 events of his life would undoubtedly be acceptable to all 
 our readers. A fair detail, however, of fuch a life, we 
 believe it impoflible at prefent to give ; for charafters 
 like Briffot's are almoft always mitrcprefcnted both by 
 their friends and by their enemies ; and till the troubles 
 which they have excited, or in which they have been 
 engaged, have long fubfided, the impartial truth is no- 
 where to be found. 
 
 In a fulfome panegyric, under the denomination of 
 The Life nf J. P. Brijfot, faid to be written by himfelf, 
 \v.e are told, that he was born January 14. 17^4 ; and 
 that his father was a tra'iteur, or " the keeper of an 
 eating-houfe," but in what place we are not informed. 
 Our author, however, affures us that the old man was 
 in eafy circumftances, and that he employed all the 
 means refulting from them to give to his numerous fa- 
 mily a good education. The fubjeft of this memoir 
 was intended for the bar ; but not relilhing the ftudies 
 neceflary to fit him for the profeflion of the law, or, if 
 we choofe to believe him, having a mind too pure and 
 upright for the ftudy of chicane, he relinquilhed the pur- 
 fuit after five years of drudgery ! 
 
 To relieve his wearinefs and difguft, he applied him- 
 felf, he fays, to literature and the fciences. The ftudy 
 of the languages was above all others his favourite pur- 
 fuit. Chance brought him acquainted with two Eng- 
 liftimen on their travels through France : he learned 
 their language ; and this circumftance, he tells us, de- 
 cided his fate. 
 
 " It was at the commencement of my pafiion for 
 that language (continues he) that I made the meta- 
 morphofis of a diphthong in my name which has fince 
 been imputed to me as fo heinous a crime. Born the 
 thirteenth child of my family, and the fecond of my 
 brothers in it, I bore, for the fake of diftinftion, ac- 
 cording to the cuftom of Beauce, the name of a village 
 in which my father pofieffed fome landed property. 
 This village was called Ouarvilk, and Ouarville became 
 the name by which I was known in my own country. 
 A fancy ftruck me that I would cart an Englilh air up- 
 on my name ; and accordingly I fubftituted, in the place 
 of the French diphthong ou, the lu of the Engliih, 
 which has precifely the lame found." For this pu- 
 erile afFeClation, which was certainly not criminal, he _ 
 juftifies himfelf by the example of the literati of the 
 16th and 17th centuries, who made no fcruple of Gre- 
 cifing and Latinifing their appellatives. 
 
 Having profecuted his ftudies for two years, he had 
 an application from the Englifh proprietor of a paper 
 then much in circulation, and intitled Le Courier de 
 /' Europe. This man having drawn upon himfelf an at- 
 tack from government, felt and yielded to the neceflity 
 of printing his paper at Boulogne-fur-mer. It was his 
 with to render it interefting to the French in the depart- 
 ment of mifcellaneous intelligence ; which he therefore 
 wilhed to fubmit to the fuperintendency and arrangement 
 
 of
 
 B R I 
 
 Briffot. of BrilTot, who reprefents hfmfclf as for fome moments 
 ■— « ' heikiting. The profcdion of a journallft, fubjccl to a li- 
 ceiifcr, was repugnant to his principles ; yet it lecured 
 his independence, and put into his power the means of 
 profecuting an inveftigation of conllitutions and of the 
 fciences. After fome ridiculous reaioning from the ori- 
 ginal ftations of Bayle, Pojld, and Roufflau, he at lad 
 accepted of the employment, and became enamoured 
 of it, " becaufe (fays he) it enabled me to ferve talents 
 and virtue, and, as it were, to inoculate the French 
 with the principles of the Englilh conftitution. 
 
 This employment, however, did not laft for any 
 length of time. The plan of the proprietor of the Cou- 
 rier was overthrown by adminiflration, and Briflot quit- 
 ted Boulogne to return to his iirft ftudies. Having in- 
 formed us of this fail, he makes an extravagant pre- 
 tence to unfuUied virtue, and calls upon the inhabitants 
 of the city which he had left to bear witnefs, not only 
 that he had no -vices, but that he had not even the feeds 
 of any one of the vices which his adverfaries, it fecms, 
 had laid to his charge. 
 
 " Doubtlefs (fays he), too eager to publifh my ideas, 
 I conceived that the proper moment had arrived, and I 
 felt an inclination to commence with an important work. 
 Revolting, from the very inftant of my beginning to re- 
 fleft, againft religious and political tyranny, I folemnly 
 protefted, that thenceforward I would confecrate my 
 whole life to their extirpation. Religious tyranny had 
 fallen under the redoubled llrokes of RoufTeau, of Vol- 
 taire, of Diderot, and of D' Alembert. It became ne- 
 ceflary to attack the fecond ;" and this was a taflc 
 which the vanity of Briflot led him to confider as refer- 
 ved for him. 
 
 What Voltaire and his friends meant by religious ty- 
 ranny, and how they condufted their attacks againft it, 
 are matters, alas ! too well known to all Europe ; and 
 as our author cliofe thefe philofophers for his guides, 
 we might infer, without much degree of miitake, what 
 he underllood by political tyranny, and by what means 
 he meditated its extirpation. But he has not left us 
 to make this difcovery by inference. 
 
 " It became neceifary (fays he) to break In pieces 
 the political idul, which, under the name of vwnarchy, 
 praflifed the mod violent dcfpotifm ; but to attack it 
 ppenly, was to expofe the aflailant without the polfibili- 
 ty of ferving mankind. It was by a fide blow that it 
 was to be wounded moft: efFeftually ;" and therefore he 
 refolved to begin his operations by attacking fome of 
 thofe abufes which might be reformed without apparent- 
 ly (baking the authority of the prince. 
 
 Our readers, at lead the fober part of them, will pro- 
 bably think that this mode of attack is not peculiar to 
 Briflot, but that it has been praflifed, or attempted to 
 be put in praftice, by afpiring demagogues in all ages 
 and countries, who have uniformly begun their career 
 of innovation by exciting the public mind againft thofe 
 abufes in government, of which the exiftence cannot 
 wholly be denied. The fnbjeft to which our author 
 thought fit to call the attention of liis countrymen, was 
 the criminal jurifprudence : a fubjedt, fays he, which, 
 with the exception of fome particulars that had been 
 fuccefsfully inveftigated by Beccaria and Servan, no 
 ivriterhad thoroughly confidcred in a phlloiophical point 
 of view. Thinking himfelf fully equal to this tallc, he 
 drew up a general plan ; and in the year 1780 publifl^- 
 
 [ 119 ] 
 
 B R. I 
 
 ed his Theory of Criminal Laws, in two vols 8vo. This BrlTot. 
 work, favourably received by foreigners, applauded by "—>"■"■ 
 fome journalifts, and pulled to pieces by others, procu- 
 red him the friendftilp of the warmeft advocates for hu- 
 man liberty, in whofe opinion the dtfefts of his plan 
 were highly pardonable, on account of the energy con- 
 fpicuons in his remarks. This publication was fooii 
 followed by two dlfcourfes which gained the prize in 
 1782 at the academy of Chalons-fur-Marne ; the one 
 upon the reform of the criminal laws, and the other on 
 the reparation due to Innocent perfons unjuftly accufcd. 
 
 It is natural to fuppofe that the government beheld 
 with an evil eye thefe writings, which, under pretext 
 of dragging into light the abufes of the criminal laws, 
 infinuated dangerous principles on the nature of govern- 
 ment In general. 
 
 His next work was intltlcd, A Philofopkical Library 
 of the Criminal La-Ms, In 10 vols; the true objedl of 
 which was to difrcminate in France thofe principles of 
 liberty which guided the Engllfh and the Americans In 
 framing and expounding their laws. 
 
 But the ftudy of iegiflation and politics had not en- 
 tirely drawn him off from that of other fciences; fuch 
 as chemiltry, phyfics, anatomy, theology, &c. Thefe 
 he conftantly cultivated with ardour ; but acknowledges 
 that In each he met with obfcurities, and that in eveiy 
 quarter truth cfcaped from his refearches. He there- 
 fore fat down to inveftigate the nature of truth, and 
 the proper method of attaining to it in every depart- 
 ment of refearch ; and the refult of his labours was a 
 kind of novum organum, by which he feems to have ex- 
 pected that Bacon's work would be burled In oblivion ; 
 and to this Important volume he gave the title of Con- 
 cerning Truth ; or. Thoughts on the Means of attaining 
 Truth in all the Branches of Human Knowledge. This 
 volume was meant as nothing more than the introduc- 
 tion to a greater work, in which he propofed to invefti- 
 gate what is certain In knowledge and what doultful, 
 and then to ftrike the balance of the account. 
 
 He was prevented, however, from completing his 
 plan, which he regrets exceedingly ; for, as he affirms, 
 with becoming modejly, his work would certainly have 
 amended Its readers ! But the French government ha])- 
 pened to think otherwife ; his aim, which, he fays, was 
 to lead mankind to refloft on their rights, was perceived, 
 and he was accufed to the m.ialfter as a fedit ions- writer. 
 The career of genius was ftopped by the dread of the 
 Baftlle ; and he was obliged to take refuge in London. 
 There It was his widi to create a univcrfal confederation 
 of the friends of liberty and truth, and to eftablifh a 
 centre of correjpondem e and union with the learned and 
 the politicians of Europe. This dark dtiign, however, 
 was fruftrated by the treachery, as it would appear, of 
 his affoclates, who had bound themfelves, he fays, by 
 the \x\Q^facred oaths, to alTift him, and had offered to- 
 fign articles even ivith their own Hood. 
 
 Finding himfelf unable to proceed diredly to the ob- 
 jeft which he had in view, he refolved to enliglteii his 
 countrymen gradually, and to begin with exciting their 
 love and admiration of the Englifli conftitution. That 
 conftitution, which he had Inveftigated on the fpot, ap- 
 peared to him a model for tliofe focleties which were 
 defirous of changing their form of government. Tt was 
 but little known, he fays, in France (the work of De 
 Lolme being at that time only in. the hands of the learn- 
 ed);
 
 B R I 
 
 [ 
 
 BrtlTit. eJ); and to make it known was to make it beloved, was 
 V ' to render it delired. But the Frencli minifters Hood 
 upon their guard, and it became neceflary to deceive 
 them. He refolved therefore to bring forward a jour- 
 nal written adually in London, and profelTing to con- 
 tain only a dcfcription of the fctences and arts of England, 
 wbilil the greater part of it was to be occupied in rea- 
 lity by an inveftigation of the Englijh conjlitulion. 
 
 After many difficulties, the minillry granted a privi. 
 lege for this journal, being publifhed in London, to be 
 reprinted in Paris; and it firft appeared in 17S4. " In 
 the twelve numbers which have been publifhed (fays 
 the author), the friends of liberty mull have perceived, 
 that if, on the one fide, I endeavoured to inculcate more 
 juft ideas than had hitherto been entertained concerning 
 this celebrated ifland ; fo, on the other, I refolutely 
 made my advances toward that important end which has 
 perpetually prefided over all my labours, the unlverfal 
 emans:/<.it'nn of m'-n." 
 
 His affairs calling him at this time to Paris, he was 
 arrelled and conveyed to the Baftile on the 12th of 
 July 1784. In this conduft of the government we 
 cannot perceive any thing very tyrannical or arbitrary, 
 fince he confefies, that, in the i6th page of the firft 
 number of his Journal, he had fufFered the fecret and fa- 
 vourite aim, which always guided his pen, to become 
 difcernible. He was, however, difcharged from prifon 
 on the ;th of September, and returned with increafed 
 zeal to his former employments. 
 
 "This perfecution (fays he), far from extinguifhing 
 the ardour of my wiflies to inculcate the principles of 
 freedom, ferved only to inflame it the more." Accord- 
 ingly, in 1785, he publiflied two letters to the Empe- 
 ror Jofeph II. concerning the right of emigration, and the 
 right of people te revolt. The firil of thefe letters, which, 
 though well known in Germany, were in France fup- 
 prefied by the police, was occafioned by what the au- 
 thor calls the ridiculous and barbarous edift again ft 
 emigration ; and the fecond by the puniftiment of Ho- 
 rlah the chief of the IValachian infurgents. In this hft 
 letter he lays it down as a maxim, that all people under 
 fuch a government as that of the IFa/achlans, have from 
 nature a facred rlghl to revolt, a right wliich they can 
 and ought to exercife. In the fame fpirit he brought 
 out, in 1786, his Philofophical Letters on the Hiftory 
 of England, in 2 vols, and A Critical Examination of 
 the Travels of the Marquis de Chatelleux in North A- 
 merica. 
 
 The French revolution appearing to him extremely 
 diftant, notwithftanding all his efforts to haften it, he 
 refolved to leave France for the purpofe of fettling in 
 America. His projefl received the approbation of fe- 
 veral, whofe fentiments were congenial with his own. 
 But as it was thought imprudent to tranfport numerous 
 families to a country fo far off, without thoroughly 
 knowing it, BrifTot was engaged to proceed thither, to 
 examine the different places, to obferve the inhabitants, 
 and to difcover where and in what manner the eftablifh- 
 ment they had propofed might be moll advantageoufly 
 fixed. He had fome time before inftituted a fociety at 
 Paris for accomplifhing the abolition of the negro trade, 
 and for foftening the condition of the flavesi. At the 
 period of his departure, this fociety confifted of a con- 
 fiderable number of dlllinguifhed members, and he was 
 commiflioncd to carry the firft fruits of their labours to 
 
 20 ] B R O 
 
 America. His ftay there, however, was not fo long as 
 he was deflrous of making it. In the beginning of 
 1789 he was recalled by the news of the French revo« 
 lution, which he conceived might probably produce a 
 change in his own meafures and in thole of his friend^. 
 This idea, added to other circumftances, accelerate'd his 
 return. The fire had blazed forth in his native coun- 
 try. " Hope (fays he) animated every heart ; the moft 
 diftinguifhed champions had engaged in the contell ; I 
 too became defiious to break a Lince, and I publifhed 
 my P/cjn of Conduct for the Deputies of the People." 
 
 This, and other works of a fimilar kind, of which he 
 loudly boafts the merits, raifcd him high in the favour 
 of tlve republican part of the nation, and he became 
 prefident of his diftric^ ; where he afted, according to 
 his own account, with great uprightnefs in the munici- 
 pality, in the firft committee of inquiries, and as an 
 eledlor. At laft he became a member, firft of the Na- 
 tional Affemhly, and, after its dilTolution, of the SanguU 
 nary Convention ; and by fome means or other got to 
 be the leader of a party called fometimes the Girondljls, 
 and fometimes the Brljfotlnes. From that period the 
 principal events of his life were involved with the pub- 
 lic tranfadlions of the nation, of which we have given 
 an account in the Encyclopedia under the title Revo- 
 lution (fee that article, n" 101 — 182.) The Giron- 
 dift fadlion was denounced by the Mountain, and Brif- 
 fot fuffered by the guiUotine on the 30th of November 
 1793. He fell indeed by a very unjuft fentence ; but 
 his fall was the natural confequence of that anarchical 
 tyranny under which no man had contributed more than 
 he to fubjeft his native country. 
 
 BROWN (Dr John), author of the Elementa Medi- 
 cine, &c. was born in the viUage of Dunfc, or, as fome 
 fay, Lintlaws, in the county of Berwick, in the year 
 1735-6. His paren'.s were of mean condition, but 
 much refpefted in the neighbourhood for the integrity 
 of their lives. His father gained his liveliliond in the 
 humble capacity of a day-labourer ; while his mother 
 contributed her fliare towards the fupport of the fami- 
 ly by the profits arifing from a milch cow. 
 
 Such were the perfons who, in an obfcure part of 
 the country, gave birth to a Ion deftined, at a future 
 period, to make a diftinguifhed figure in the republic of 
 letters ; and from whom originated a fyftem of the ani- 
 mal economy, wliich, whatever be its real merits, has 
 undoubtedly produced a confiderable revolution in the 
 practice of medicine. 
 
 At the age of three or four years, young Brown was 
 put to a reading fchool in Dunfe, which he himfelf 
 commemorates as the place rather of his education than 
 of his nativity. Here, under the tuition of an old wo- 
 man, he very early began to exhibit inarks of that 
 ftrength of mind for which he was afterwards fo emi- 
 nently diftinguifhed. In the (hort period of a year he 
 became able to read with facility any part of the Bible, 
 and acquired over his clafs-fellows that fuperiority which 
 he ever after maintained both at fchool and college. 
 
 It was almoft immediately after his entrance into this 
 fchool, that his infatiable defire of reading commenced; 
 and fo unremitting was his application, that he is faid 
 never to have been found, even at thofe hours which 
 children much more advanced in life devote to amufe« 
 ment, without a book in his hand. 
 
 While he was making this rapid progrefs in the ru- 
 
 dimentt
 
 B R O [I 
 
 Brown, diments of literature, he fuffered what fnuft have ap- 
 ■"v""- peared to be a very heavy lofs in the death of lu's fa- 
 ther ; but his mother foon afterwards married a worthy 
 man of the fame name, whofe care and attention Inp- 
 phed the place of a father to her fon. Tin's man being 
 a weaver, defigned to educate his fon-inlaw to the fame 
 bufmefs, and began to inftrudt him in his art when he 
 was about nine years of age: but the tafte which young 
 Brown had already acquired for letters, made him look 
 with difguft on the infipid employment of a weaver. 
 His ftep-father was no tyrant, and his mother was affec- 
 tionate. They were both proud of the talents which 
 at fo early a period of life had appeared in their fon, 
 and they felt no inclination to ftruggle with the invin- 
 cible averfion which he exprtfltd to the bufmefs for 
 which they intended him. 
 
 Another circumftance, however, contributed in no 
 fmall degree to make them recal their original refolu- 
 tion. They were both of that feft of religionifts which 
 in Scotland are called Seceders (fee Seceders, EncycL); 
 and it was fuggelled to them by fome perfons of their 
 own perfuafion, who had remarked the uncommon abili- 
 ties of the boy, that he might one day prove an able 
 fupport and promoter of their tenets as a preacher. He 
 ivas accordingly, much to his fatisfaftion, taken away 
 from the bufmefs to which he had conceived fuch a 
 diftafte, and fent to the grammar-fchool of Dunfe, 
 which was taught at that time by a gentleman of the 
 name of Cruickfhank, eminent for his grammatical 
 knowledge. Here he appears to have fpent fome years 
 with uncommon advantage and happinefs ; during which 
 he was eftcemed by all the country round as a kind of 
 prodigy. Like Johnfon, and many other men of the 
 highell celebrity, he united in the fatpe perfon uncom- 
 mon powers of mind, with no lefs ftrength of body, as 
 indeed his appearance indicated ; and in his youth he 
 enfured his own perfonal importance among his fchool- 
 fellows, by excelling them not lefs in athletic exercifes 
 than in the taflis prefcribed by their mailer. He was 
 particularly fond, when a boy, of praftifing the pugiliftic 
 art ; and indeed until the laft period of his life he was 
 obferved by his friends always to view an exhibition of 
 that kind with peculiar relifh. He alfo prided himfelf 
 much in being a (lout walker ; and mentions his ha- 
 ving in one day accomplilhed, when but fifteen years 
 of age, a journey of fifty miles between Berwick-upon- 
 Tweed and Morpeth in Northumberland. When far- 
 ther advanced in life, he travelled on foot from four in 
 the afternoon of one day to two in the afternoon of 
 next day, with the fhort interval of one hour's reft I 
 But as one of his biographers very juftly obferves, " we 
 have feen that he could make a more rational ufe of 
 his ftrength than merely to flake it againll time and 
 DrBed- fpace *." 
 
 's- His early years while at fchool were marked by the 
 
 moil rigid attachment to his feft. So ftrift indeed were 
 his religious fentiments, if a boy of ten or elevefi can be 
 faid to have any fentiments deierving to be called reli- 
 gious, that he would have conceived the holding of any 
 communion with the eftabhihed church as a kind of 
 profanation. An event, however, happened, fome time 
 between the eleventh and thirteenth years of his age, 
 which produced a total and unexpeeltd revolution in 
 his religious opinions. At a meeting of the provincial 
 fynod of Merfe and Tiviotdale, he was prevailed upon, 
 SupFL. Vol. I. Pan I. 
 
 21 ] B R O 
 
 though not without mauifefting much reluiflance, to 
 accompany a party of his fchool-fcllows to the parifli 
 church of Dunfe. Tlie coniequence of this tranfgref- 
 fion, as he liad dreaded, was an immediate funimons to 
 appear before the fellion of the Seceding congregation; 
 to which, through pride, not choofing to attend, in or- 
 der to preclude a formal expulfion, he voluntarily abju- 
 red their tenets, and openly avowed his apoftacy to the 
 ellablifhment. 
 
 All changes in religion whicli are not the confequence 
 of candid invettigation are dangerous. He who leaves 
 one fcA he knows not why, will quickly abandon, with 
 as little reafon, that to which in a fit of paflion he had 
 haftily joined himfelf. From the moment of his quit- 
 ting the communion of the Seceders, Brown's religious 
 ardour fuffered a gradual abatement ; and though, to 
 pleale his mother, he continued to profecute his fludies 
 with a view to the office of a clergyman in the church 
 of Scotland, his opiniuns became daily more and more 
 lax, and his life of courfe lefs and lefs regular. It was, 
 however, a confiderable time before he admitted, in 
 their full extent, thofe principles of irreligion which he 
 afterwards avowed ; for upon his firft perufing the Ef- 
 fays of Mr Hume, though his own zeal was then much 
 cooled, he expreffed great indignation at their danger, 
 ous tendency. 
 
 At the age of twelve years he had been employed by 
 Mr Cruickfhank asakindof ullierin the fchool of Dunfe; 
 and that gentleman having declared that his knowledge 
 of the Latin language was equal to his own, his fame as 
 a fcholar was fo fpread over the country, that at the age 
 of thirteen he was intrulled with the education of a 
 gentleman's fon in the neighbourhood, when he quitted 
 the fchool and his beloved mafter. In his new fit na- 
 tion, liowever, he remained not long. Dr Beddoes con- 
 jeftures, that to the ftiffnefs of pedantry he added the 
 fournefs of a bigot, and was therefore a difagreeable in- 
 mate of the family. That a boy of thirteen, proud of 
 his talents, and prouder of his learning, fliould have the 
 ftiffnefs of a pedant, is indeed extremely probable ; it 
 was the natural confequence of the praife with which 
 he had been honoured by Mr Cruickfhank : but there 
 is reafon to believe that of his original bigotry few tra- 
 ces now remained. The real caufe of his difniiifion from 
 the family, we are affured, was his pride; and as it muft 
 have been the pride of parts, it confirms the firll part of 
 Dr Beddoes's conjedlure. 
 
 It feenis he was much difpleafed that, when company 
 were at dinner, he was not defired to remain after tlie 
 cloth was removed ; and yet if he was then only thir- 
 teen years of age, it is not eafy to conceive for what 
 purpoie he fhould have ftaid. He could not polFibly 
 know much of the world, or of any thing likely to em- 
 ploy the convei fation of country gentlemen ; and wc 
 cannut help thinking, that the mafter of the houfc 
 would have treated his guefts with rudcnefs, had he de- 
 tained among them a raw bov to lillen to every un- 
 guarded expreffiou which migbt cfcape them over their 
 wine. It would appear, however, that he was not un- 
 willing to give the tutor of his fon an opportunity of 
 difplaying his abilities, when furh fubjedts were intro. 
 duced as he knew him to have lludied ; for a difpute 
 having arilen, one day after Brown had retired to his 
 own room, concerning the decrees of Providence, he 
 fent to requefl his opinions on that abftrufe fubjeft. By 
 CL 'he 
 
 nrown.
 
 B R O 
 
 [ 12 
 
 Brown, the meflenger Brown returned a verbal .infwer, that 
 . " the decreis of Providence are very uiijuft, for having 
 made blockheads lairds." 
 
 Mr Cruicklhank had fome time before requefted him 
 to return to tlie fituation which he had formerly held 
 in the fchool of Dunfe ; and we cannot wonder that, 
 immediately after making this infolent anfwer, he found 
 it convenient to comply with his rcqueih He was now 
 about fifteen, and he continued in the fchool till the 
 20th year of his age ; during which time, from the 
 conftant habit of teaching the Latin and Greek lan- 
 guages, he acquired a wonderful facility in reading both 
 thefc languages, and in writing the former, though he 
 wrote not with tarte. 
 
 About this time it occurred to him that he might 
 turn his claffical acquirements to more account, by be- 
 coming a private teacher of languages in Edinburgh. 
 To that city he accordingly repaired, where, while he 
 obtained a livelihood as a teacher, he propofed at the 
 fame time to purfue his theological iludies at the univer- 
 fity. But an accident happened to him here which made 
 him altogether change the plan he had come upon ; and 
 the death of his mother, after a relidence of fome time in 
 Edinburgh, abfolvedhim.as he thought,from the promife 
 which he had made to her of appearing one day in the 
 pulpit. Shortly after an unfuccefsful competition for 
 one of the chairs then vacant in the high-fchool, an ap- 
 plication was made to a friend of his for a proper per- 
 fon to turn a medical thefis into Latin. Brown was 
 recommended. He was limited to a certain time; with- 
 in which it appeared fcarce practicable to perform the 
 tafk. He accomplilhed it, however, and in fuch a ftyle 
 of crrammatical correftnefs and purity as far exceeded the 
 general run of fuch productions. On this being remark- 
 ed to him by his friends, he obferved, " that he now 
 knew his ftrength, and was ambitious of riding in his 
 carriage as a phyfician." He therefore determined to 
 apply himfelf with ardour to the lludy of medicine, to 
 which this accidental circumllance alone direfted his at- 
 tention. Accordingly, at the commencement of the 
 next winter feffion, he addrcfled a Latin letter to each 
 of the medical profeffors, and by them was prefented 
 with tickets of admittance to their fcveral clafles. 
 
 From fuch a favourable beginning, being of a very 
 fanguine difpofition, he conceived the moil flattering 
 expcclations of his future fuccefs ; and indeed for fome 
 time he feems to have lived in affluent circumftances. 
 His attainments were fo various, and in fuch requeft in 
 Edinburgh, that as a fmgle man he could fcarcely fail 
 to gain a competent living ; for during the lall five 
 years of his refidence under Mr Crulckftiank, to a tho- 
 rough acquaintance with ancient hiflory, he had added 
 a very confiderable knowledge of mathematics; in which, 
 among other branches of fcience, he never had any ob- 
 jeftion to give inftruclions. In the acquifition of that 
 variety of knowledge which he polTeffed, he was greatly 
 affifted by a moll tenacious memory ; to the retentive- 
 nefs of which an old fchool-fellow bears telliraony, by 
 affirming, that " after once reading over the lefTon, con- 
 fiding of two odlavo pages in Latin, he would lay afide 
 the book, and preleft the whole over without miftaking 
 a fmgle word." 
 
 Brown, already in eafy circumftances for an indivi- 
 dual, faw, or thought he faw, in the eftablifhment of a 
 boardiuK-houfe for ftudeuts a refource which would en- 
 
 2 ^ B 11 o 
 
 able him to maintain a family ; and in expeftatlon of Browo, 
 realiling this profpecl, he married, in 1765, the daugh- '~~ 
 ter of a rcfpeftable tradefman in Edinburgh. The di- 
 ftiiiguifhed attention at that time paid him by Dr Cul- 
 len, in whofe family he had become a neceflary perfon, 
 contributed in all probability to llrengthen his hopes 
 that his lioufe would be filled with proper boarders 
 through the Doftor's recommendation. His fuccefs in 
 this way for fome time anfwered his moft fanguine cx« 
 peftations ; and his circumftances at one period were fo 
 flourifhing, that he is faid to have kept a onc-horfe 
 chaife. 
 
 It was, perhaps, the greateft misfortune that could 
 have befallen Brown, that he poifelTed, in a high de- 
 gree, thofe talents which make a man's company fought 
 after by the gay and the diffipated : He was capa- 
 ble of " fetting the table in a roar." We need not 
 therefore wonder at his frequently neglefting more 
 neceffary purfuits to enjoy ttie conviviality of the nu- 
 merous friends who courted his company; or that drink- 
 ing and diflipation became habitual to him. He was 
 as deficient in point of prudence as he excelled in ge- 
 nius. His houfe was filled with refpeclable boarders ; 
 but as he lived too fplendidly for an income at bell but 
 precarious, he became gradually involved in debt, and his 
 affairs were Hill more embarraffed by the burden of a nu- 
 merous family. Soon after he began to be involved ia 
 thefe difficulties, he fuffered an additional lofs in being 
 deprived of the patronage of Dr CuUen, in confequencd 
 of a difagreement that had taken place between them. 
 This enmity, which had for fome time before fecretly 
 fubfifted, probably Jrom mutual jealoufy, was at length 
 excited into an open rupture ; firft, by Dr CuUen's not 
 exerting his intereft in procuring for Brown the theo- 
 retical chair of medicine, then vacant in confequence ei- 
 ther of the death or refignation of Dr Alexander Monro 
 Drummond; and, fecondly, by his rejecting, fome time, 
 after. Brown's petition for admittance into the Edin- 
 burgh Philofophical Society. 
 
 In 1776 Brown was elected prefident of the Medicab 
 Society ; and the fame honour v/as again conferred on 
 him in 1 780. He was led on, in the gradual manner 
 he himfelf defcribes in his mafterly preface to the Ek- 
 menta Medtcina, to the difcovery of his new doClrine f. 
 which, on dropping all correfpondence with his former 
 friend and benefactor, he now, for the firft time, began 
 to illuftrate ia a courfe of public leftures ; and in thefe 
 he difplayed equal ingenuity and philofophical profun- 
 dity. Much about the time of which we now fpeak^ 
 he publifhed the firft edition of the Ehmenta Medkina ; 
 a work which certainly proves its author to have been 
 a man of uncommon genius and originality of thought. 
 The circumftances in which this work was compoftd 
 refleft great honour on his abilities. He never retired 
 to his Itudy ; but, totally abforbed in his own ideas,. 
 wrote with the greateft tranquillity amidll the noife 
 of ten children, occafionally fettling their childilh dif- 
 ferences. 
 
 In the year 17791 though he had ftudied medicine 
 ten or twelve years at the univerfity of Edinburgh, he 
 was prevailed upon by his friends to take a degree at 
 St Andrews, where he gave a confpicuous proof of his 
 facility in Latin compofition. He wrote a thefis, or 
 inaugural dilfertation, in the tavern while the cloth was 
 laying for dinner ; and one of his companions, who was 
 
 finging
 
 B R O 
 
 [ »23 1 
 
 B R O 
 
 fingiiig befide him, having uttered a falfe note, or fung 
 out of time, Mr Brown, in the middle of his writing, 
 flopped to (hew him how the fong ougiit to be fung, 
 and then inilantly proceeded in his thelis. 
 
 His family having now become fo numerous as to ren- 
 der keeping a boarding-houfe inconvenient, he had alrea- 
 dy for fume time given it up, and depended for lupport 
 entirely on his praftice as a phyfician and his public 
 ledlures. At this time the dii'putcs between the Culle- 
 iiiaiis and the Brunonidiis (as the young men now llyled 
 themfelvcs) were carried on with iuch acrimony on both 
 fides, in the different focieties, that it was not unufual tor 
 them to terminate in duels ; and there cxiils at this day, 
 on the records of the Medical Society, a law which it 
 was thought expedient to enadi, by which a member 
 who challenges another for any thing laid in public de- 
 bate incurs the penalty of expullion. 
 
 Obferving the lludents of medicine frequently to 
 feek initiation into the mytteries of freemafonry, Dr 
 Brown thought their youthful curiofity afforded him a 
 chance of profelytes. In 1784, he inftituted a meet- 
 ing of that fraternity, and intitled it the Lodge of the 
 Roman Eagle. The bufniefs was condufted in the La- 
 tin language, which he fpoke with the fame fluency as 
 Scotch ; and he dilplayed much ingenuity in turning 
 into l.dtin all the. terms ufed in mafonry. 
 
 As the terms on which he lived with his brethren 
 of the faculty were fuch that hg, obftinately avoided 
 meeting them even in confultatftin, we may conclude 
 that his own private pra£lice was but limited. His 
 friends affirmed, perhaps without iufficient proof, that 
 cabals were formed againft him, and every advantage 
 taken of the errors he was led to commit by his own 
 imprudenc-e. After a long feries of itruggles, there- 
 fore, hoping to meet with that encouragement among 
 the Englilh uf which he had been dil'appointed in his 
 own country, he put in praftice a plan upon which he 
 had long meditated, and removed in 1786 with part of 
 his family to London. Immediately on his arrival, an 
 incident bcfel him, which Dr BeJdoes fays he has heard 
 the late Mr Murray, bookfeller in Fleet-ilreet, relate as 
 a proof of his fimplicity. The peculiarity of his ap- 
 pearance as he moved along (a (hort fquare figure, 
 with an air of dignity, in a black fuit, which heighten- 
 ed the fcarlet of his checks and nofe) fixed the atten- 
 tion of fome gentlemen in the flreet. They addrelTed 
 him in the dialeft of his country. His heart, heavy as 
 it muft have been, from the precarioufnefs of his fitua- 
 tion, and diilance from his accuftomed haunts, expand- 
 ed at thefe agreeable founds. A converfation eniued ; 
 and the parties, by common confent, adjourned to a ta- 
 vern. Here tlie flranger was kindly welcomed to town; 
 and, after the glafs had circulated for a time, fomethirg 
 was propofed by way of fober amufement — a game at 
 cards, or whatever the Doftor might prefer. The 
 Doftur had been too civilly treated to demur ; but his 
 purle was fcantily furniftied, and it was necefiary to 
 quit his new friends in fearch of a fupply. Mr Murray 
 was the perfon to whom he had recourfe : the reader 
 will not wonder that his interference fhould have fpoiled 
 the adventure. 
 
 A London {harper, of another denomination, after- 
 wards tried to make advantage by the Doftor. This 
 was an ingenious fpeculator in public medicines. He 
 thought a compofition of the mofl powerful ftimuiants 
 
 might have a run, under the title of Dr Brono/t's ex- Brown 
 citing pill ; and, for the privilege of his name, offered ' 
 
 him a lum in hand by no means contemptible, as well 
 as a {hare of the contingent profits. Poor Brown, 
 needy as he was, fpurned at the propofal. 
 
 After this period, his life affords little variety of in- 
 cident. Like Avicenna, his time fecms to have beea 
 fpent between his literary purluits and his plcalures. 
 A fplendid manner of living, without an income to fup- 
 port it, had become habitual to him : The confequencc 
 was, that, from inability to difcharge certain debts he 
 had contrafted, he was thrown into the king's bench 
 prifon ; from which, however, he was, not long after- 
 wards, releafed by the exertions of a few firm friends, 
 particularly Mr Maddlfon of Charing-crofs, a gentle- 
 man univerfally refpedled for his well-known benevo- 
 lence. As a proof of the attivity he was ftill capable 
 of exerting, it will be fufficient to mention, that he ac- 
 complifhed the tranflation of his Elementa, with the 
 addition of the fupplementary notes, within 23 days, 
 having been informed that a tranllation of the fame waB 
 about to be publiihed by another perlon. 
 
 Shortly before his death, the ambaffador of the 
 king of Pruffia, in the name of his mailer, made Dr 
 Brown an offer of a fettlement in the court of Berlin; 
 during the negociation of which he was unexpectedly 
 cut off by an apoplexv early in the morning of the ^th 
 of Oilober 1788, the day fucceeding that on which he 
 had delivered to a company of thirteen gentlemen the 
 greater part of the introduClory lecture to his fecoud 
 courfe. At his death, he was between 52 and 53 years 
 of age. His remains were interred in the church-yard 
 of St James's Picadillv ; and the only monument left 
 behind him to tranfmit his name to pofterity is bis 
 own works ; which, when perfonal prejudice no longer 
 ffiall prevail againll their ingenious author, cannot fail 
 to procure him all that delcrved celebrity which they 
 have already, in part, obtained in the different coun- 
 tries of Europe. 
 
 In 17S7, he publiihed his " Obfervations," without 
 his name, which he afterwards, however, i-efcrs to in 
 the Elements as his own. The " Enquiry," faid to 
 be written by Dr Jones, and which was compofed in as 
 (hort a time as the generality of men would tranfcribc 
 a work of its extent, we can affirm, from undoubted 
 authority, to be his produdlion. 
 
 This flcetch of the life of the unfortunate Dr Brown 
 would be of very little value if not followed by a view 
 01 his fyftem ; but to give a complete view of that fyf- 
 tem would far exceed the limits within which, in a 
 work like this, fuch articles muft be confined. We 
 trull, therefore, that our readers will be fatisfied with 
 an abftraft ; and as we are neither the partifans nor op- 
 ponents of the Dofilor, and not vei-y partial to any me- 
 dical fyftem whatever, we (liall content ourfelvcs with 
 inferting, in this place, the view which Dr Beddoes has 
 given of Dr Brown's fundamental propofitious in the 
 valuable obfervatitms which he has prefixed to his edi- 
 tion of the Elements of Medicine. 
 
 " The varied (Irudlure of organized beings (fays Dr 
 Beddoes), it is the bufinefs of anatomy to explain. Con- 
 fcioufnefs, aflifted by common obfcrvation, will diftin- 
 guifh animated from inanimate bodies with precifion 
 more than fufficient for all the ends of medicine. The 
 caufc of gravitation has been left unexplored by all pru- 
 Qj! dent
 
 B R O [ 
 
 Brovvn. dent philofophers ; and Brown, avoiding all ufelefs dif- 
 » quifition concerning the caufe of vitality, confines liim- 
 
 felf to the phenomena which this great moving prin- 
 ciple in nature may be obferved to produce. His moft 
 , general propolitions are cafy of comprehenfion. 
 
 " I. To every aninKited being is allotted a certain 
 portion only of the quality or principle on which the 
 phenomena of life depend. This principle is denomi- 
 nated excilalHity. 
 
 " 2. The excitability varies in different animals, and 
 in the fame animal at different times. As it is more 
 intenfe, the animal is more vivacious or more fufceptible 
 of the aftion of exciting powers. 
 
 " 3. Exciting powers may be referred to two claffes. 
 I. External; as heat, food, wine, poifons, contagions, 
 the bluod, fecreted fluids, and air. 2. Internal ; as the 
 funftions of the body itfelf, mufcular exertion, think- 
 ing, emotion, and pafDon. 
 
 " 4. Life is a forced (late; if the exciting powers 
 are withdrawn, death enfues as certainly as when the 
 excitability is gone. 
 
 " 5. The excitement maybe too great, too fmall, or 
 in juft meafure. 
 
 " 6. By too great excitement, weaknefs is induced, 
 becaufe the excitability becomes defeftive ; this is inJi- 
 ■ red debility : when the exciting powers and ftimulants 
 are withheld, weaknefs is induced ; and this is JireH de- 
 bility. Here the excitability is in excefs. 
 
 " 7. Every power that a£ts on the living frame is 
 ftimulant, or produces excitement by expending excita- 
 bility. Thus, although a perfon accuftomed to ani- 
 mal food may grow weak if he lives upon vegetables, 
 ftill the vegetable diet can only be confidered as pro- 
 ducing an effeft, the fame in kind with animals, though 
 inferior in degree. Whatever powers, therefore, we 
 imagine, and however they vary from fuch as are habi- 
 tually applied to produce due excitement, they can only 
 weaken the fyftem by urging it into too much motion, 
 or fuffering it to fink into langoiir. 
 
 " 8. Excitability is feated in the medullary portion 
 of the nerves, and in the mufcles. As foon as it is 
 anywhere affefted, it is immediately affefted everywhere ; 
 nor is the excitement ever increafed in a part, while it is 
 gcnei-ally diminifhed in the fyflem ; in other words, diffe- 
 rent parts can never be in oppofite ftates of excitement. 
 
 " I have already fpoken of an illuitration, drawn up 
 by Mr Chriftie from a familiar operation, to facilitate 
 the conception of Brown's fundamental pofitions. I 
 introduce it here as more likely to anfwer its purpofe 
 than if feparately placed at the end of my preliminary 
 obfervations. ' Suppofe a fire to be made in a grate, 
 filled with a kind of fuel not very combuftible, and 
 which could only be kept burning by means of a ma- 
 chine containing feveral tubes, placed before it, and 
 eonftantly pouring ftreams of air into it. Suppole alfo 
 a pipe to be fixed in the back of the chimney, through 
 which a conftant fupply of frefh fuel was gradually let 
 down into the grate, to repair the wafte occafioned by 
 the flame, kept up by the air machine. 
 
 ' The grate will reprefent the human frame ; the 
 fuel in it, the matter of life — the excitability of Dr 
 » Brown, and the fenforial power of Dr Darwin ; the 
 tube behind, fupplying frefh fuel, will denote the power 
 of all living fyftems, conftantly to regenerate or repro- 
 duce excitability ; while the air machine, of feveral tubes. 
 
 124 1 B R O 
 
 denotes the various ftimuli applied to the excitability 
 of the body ; and the flame drawn forth in confequence ' 
 of that application reprefents life, the produdt of the 
 exciting powers acting upon the excitability. 
 
 ' As Dr Brown has defined life to be a forced Jlate, 
 it is fitly rcprcfented by a flame forcibly drawn forth 
 from fuel little difpofed to combullion, by the conftant 
 application of ftreams of air poured into it from the 
 different tubes of a machine. If fome of thefe tubes 
 are fuppofed to convey pure or dephlogifticated air, 
 they will denote the higheft clafs of exciting powers, 
 opium, mufk, camphor, fpirits, wine, tobacco, &c. the 
 diffufible ftimuli of Dr Brown, which bring forth for » 
 time a greater quantity of life than ufual, as the blow- 
 ing in of pure air into a fire will temporarily draw forth 
 an uncommon quantity of flame. If others of the tubes 
 be fuppofed to convey common or atmofpheric air, they 
 will rcprelent the ordinary exciting powers, or ftimuli, 
 applied to the human frame, fuch as heat, light, air, 
 food, drink, &c. while fuch as convey impure and in- 
 flammable air may be ufed to denote what have for- 
 merly been termed fedative powers, fuch as poifons, 
 contagious miafmata, foul air, &c. 
 
 ' The reader will now probably be at no lofs to un- 
 derftand the feeming paradox of the Brunonlan fyftem ; 
 that food, drink, and all the powers applied to the bo- 
 dy, though they fupport life, yet confume it ; for he 
 will fee that the appJication of thefe powers, though 
 it brings forth life, yet at the fame time it waftes the 
 excitability or matter of life, juft as the air blown into 
 the fire brings forth more flame, but waftes the fuel or 
 matter of fire. ■ This is conformable to the commor\ 
 faying, " the more a fpark is blown, the brighter it 
 burns, and the fooner it is fpent." A Roman poet 
 has given us, without Intending It, an excellent illuilra- 
 tion of the Brunonlan fyftem, when he fays, 
 
 " Balnea, -vina, Venus, confumunt corpora nojlra; 
 " Sed "vitam faciuni balnea, vina, Venus. 
 
 " Wine, warmth, and love, our vigour drain ; 
 " Yet wine, warmth, love, our life fuftaln." 
 
 Or to tranflate it more literally, 
 
 " Baths, women, wine, exhauft our frame ; 
 " But life itfelf is drawn from them." 
 
 ' Equally eafy will it be to illuftrate the two kinds 
 of debility, termed dired and indireS, which, according 
 to Brown, are the caufe of all dileafes. If the quan- 
 tity of ftimulus or exciting power Is proportioned to 
 the quantity of excitability, that Is, if no more excite- 
 ment is drawn forth than is equal to the quantity of 
 excitability produced, the human frame will be in a 
 ftate of health, juft as the fire will be in a vigorous 
 ftate when no more air is blown in than Is fufficlent to 
 confume the frefh fupply of iuel conftantly poured down 
 by the tube behind. If a fufBcient quantity of ftimulus 
 is not applied, or air not blown in, the excitability in 
 the man, and the fuel in the fire, will accumulate, pro- 
 ducing diredt debility ; for the man will become weak, 
 and the fire low. Carried to a certain degree, they will 
 occafion death to the firft, and extlnftion to the laft. 
 If, again, an over proportion of ftimulus be applied, or 
 too much air blown in, the excitability will foon be 
 walled, and the matter of fuel almoft ibent. Henc-: 
 
 %vilJ
 
 B R O 
 
 [ ' 
 
 Brn\K-n. will arife Indireft debility, producing the fame wraknefs 
 •^-~/~—' ill the man, and lowiiefs in the fire, as before, and equal- 
 ly terminating, when carried to a certain degree, in 
 death and extinftion. 
 
 ' As all the difeafes of the body, according to Dr 
 Brown, are occafioned by direft or indireft debility, 
 in confeqiience of too much or too little ftimuli, fu all the 
 defefts of the fire muil arife from direft or indirctt low- 
 nefs, in confequence of too much or too little air blown 
 into it. As Brown taught that one debility was never 
 to be cured by another, but both by the more judicious 
 application of ftimuli, fo will be found the cafe in treat- 
 ing the defetls of the fire. If the fire has become low, 
 or the man weak, by the want of the needful quantity 
 of llimulus, more mutt be applied, but very gently at 
 firft, and increafed by degrees, Icil a ftrong ttimuhis ap- 
 plied to the accumulated excitability fhould produce 
 death ; as in the cafe of a limb benumbed with cold 
 (that is, weakened by the accumulation of its excitabi- 
 lity in confequence of the abllraftion ol the ufual lli- 
 mulus of heat), and fuddenly held to the fire, which 
 •we know from experience is in danger of mortification ; 
 or as in the cafe of the fire becoming very low by the ac- 
 cumulation of the matter of fuel, when the feeble flame, 
 aifailed by a fudden and ftrong blaft of air, would be 
 overpowered and put out, inltead of being nouiilhed 
 and increafed. Again, if the man or the fire have been 
 rendered indireftly weak, by the application of too 
 much ftimulus, we are not fuddenly to withdraw the 
 whole, or even a great quantity of the exciting powers 
 or air, for then the weakened life and diminifiied flame 
 might fink entirely ; but we are by little and little to 
 diminilh the overplus of ftimulus, fu as to ei:able the 
 excitability, or matter of fuel, gradually to recover its 
 proper proportion. Thus a man who has injured his 
 conftitution by the abufe of fpirituous liquors is not 
 fuddenly to be reduced to water alone, as is the prac- 
 tice of fome phyficians, but he is to be treated as the 
 judicious Dr Pitcairn of Edinburgh is faid to have 
 treated a Highland chieftian, who applied to him for 
 advice in this fituation. The Doftor gave him no me- 
 dicines, and only exafled a promife of him, that he 
 would every day put in as much wax into the wooden 
 queich, out of which he drank his whiiky, as would re- 
 ceive the imprefiion of his arms. The wax thus gra- 
 dually accumulating, diminifhed daily the quantity of 
 the vvhiflcy, till the whole queich was filled with wax ; 
 and the chieftain was thus gradually, and without injury 
 to his conftitution, cured ot the habit of drinking fpirits. 
 
 ' Thefe analogies might be purfued farther ; but my 
 objtft is folely to furnifh fome general ideas, to prepare 
 the reader for entering more eafily into the Brunonian 
 theory, which I think he will be enabled to do after 
 perufing what I have faid. The great excellence of that 
 theory, as applied, not only to the praftice of phyfic, 
 but to the general condudt of the health, is, that it im- 
 prefles on the mind a feafe of the impropriety and dan- 
 ger of going from one extreme to another. The hu- 
 man frame is capable of enduring great varieties, if 
 time be given it to accommodate itfelf to different ttates. 
 All the mifchicf is done in the tranfition from one ftate 
 to another. In a ftate of low excitement, we are not 
 r-afhly to induce a ftate of high excitement ; nor when 
 elevated to the latter, are we fuddenly to defcend to the 
 former, but ftep by ftep, and as one who from the top 
 
 25 ] B R U 
 
 of a high tower defcends to the ground. From hafty Bfnwn, 
 and violent changes the human frame always fuffers ; Bruce, 
 its particles are torn afunder, its organs injured, the vi- ''"" 
 
 tal principle impaired, and difenfe, often death, is the 
 inevitable confequence. 
 
 ' I have only to add, that though in this illuftratiou 
 of the Brunonian fyftem (written feveral years ago"), I 
 have fpokcn of a tube conftantly pouring in frelh fuel, 
 becaufe I could not otherwife convey to the reader a 
 familiar idea of the power poffeffed by all living fyftems, 
 to renew their excitability when exhaufted ; yet it may 
 be proper to inform the ftudent, that Dr Brown fup- 
 pofed every living fyftem to have received at the begin- 
 ning its determinate portion of excitability ; and, there- 
 fore, although he fpoke of the exhauftion, augmenta- 
 tion, and even renewal of excitability, I do not think 
 it was his intention to induce his pupils to think of it 
 as a kind of fluid fubftance exifting in the animal, and 
 fubjeft to the law by which fuch fubttances are govern- 
 ed. According to him, excitability was an unknown 
 fomeivhat, fubjetl to peculiar laws of its own,.and whofe 
 different ftates we were obliged to defcribe (though 
 inaccurately) by terms borrowed from the qualities of 
 material fubftances.' 
 
 " The Brunonian fyftem has frequently been char- 
 ged with promoting intemperance. The objedfion is 
 ferious ; but the view already given of its principles 
 fhews it to be groundlefs. No writer had infifted fo 
 much upon the dependence of life on external caufes, 
 or fo ftrongly ftated the inevitable confequenccs of ex- 
 cefs. And there are no means of promoting morality 
 upon which we can rely, except the knowledge of th'i 
 true relations between man and other beings or bodies. 
 For by this knowledge we are diredfly led to Ihun what 
 is hurtful, and purfue what is falutary. And in what 
 eife does moral condud, as far it regards the individual, 
 confift ? It may be faid that the author's life difprov^cs 
 the juftnefs of this reprefentation : his life,, however, 
 only lliews the fuperior power of other caufes, and of 
 bad habits in particular; and I am ready to acknow- 
 ledge the little efficacy of inftruction when bad hsbits 
 are formed. Its great ufe confifts in preventing their 
 formation; for which reafon popular inftruftion in me- 
 dicine would contribute more to the happincfs of the 
 human fpecies, than the complete knowledge cf every 
 thing which is attempted to be taught in education, iw 
 it is condufted at prefent. But though the prii.ciplea 
 of the fyftem in queilion did not correct the prcpenfi- 
 tie? of its inventor, it does not follow that they tend to 
 produce the fame propenfities in others." 
 
 BRUCE (James, Efq; F. R. S.), the celebrated 
 AbyfTmian traveller, was born, i 730, at Kinnaird houfe, 
 in the parilli of Larbert and county of Stirling. His 
 dcfcent by both parents was ancient and honourable ;' 
 and of that defcent be was, perhaps, too proud. Hij . 
 
 grandfather was Hay, Efq; of Woodcockdale, i;i 
 
 the county of Linlithgow, who, marrying Mifs Bruce, 
 the heirefs of Kinnaird, gave the name of Bruce to all 
 his defcendants. 
 
 Perhaps this change of name may have taken pliee 
 in obedience to the deed bv which the e ftate of ¥Ji\\- 
 naird was fettled on Mrs Hay's children ; but it is a 
 change which, in a country like Scotland, where au' 
 tiquity of defcent is highly valued, any man 'would vo- 
 luntarily have adopted, who had married the heirefs ot" 
 
 fuch
 
 B R U [ 12 
 
 Bruce, fucli a faniHy. The- Bruces of KInnaIrd hnd been in 
 — V— 'jjoflcHioii of that cilate for three ceiUuries : tlicy were 
 defceiided from a younger foil of Robert de Bruce, the 
 competitor with Baliul for the crown of Scotland. It 
 would readily occur, that the knowledge of luch a dc- 
 fcent would be bed preferved by continuing the name 
 of their great ancellor ; and we have reafon to believe, 
 that the fubjert of this memoir was not much delighted 
 when put in mind, as he frequently was, that, though 
 the heir of the line, he was not the mak heir of that 
 branch of the illurtiious family. 
 
 As he was allied to royalty by his father and grand- 
 mother, through his mother he was related to fome of 
 
 admiralty in Scotland, by Marion, daughter of James 
 Hamilton Efq; of Pencaitland ; and to a man of our 
 traveller's turn of mind, there can be no doubt but that 
 it mu!l have afforded much fatisfaftion to think, that 
 no family ranks higher in Scotland than thofe of Bruce, 
 Graham, and Hamilton. In him, however, it was.weak- 
 nefs to be proud, if indeed he was proud, of family ; 
 for the talents bellowed upon him by nature, or, to 
 fpeak more properly, by nature's God, would have made 
 him great though he had been born on a dunghill. 
 He would indeed have been, in all probability, much 
 greater than he was, had he not been in poffeflion of the 
 phantom of birth to gratify much of his ambition; for 
 the facility with which he mailered every ftudy in which 
 he eno-aged, would have carried him quickly to the top 
 of the moft honourable profeffion. 
 
 Mr Bruce was inftrufted in grammatical learning at 
 the fchool of Harrow on the Hill, in the county of 
 Middlefex, where he gave the moft unequivocal proofs 
 of g.nius, and acquired a very coniiderable knowledge 
 of the Greek and Latin languages. It was cullomary 
 with him to perform, not only his own exerciles, but 
 alfo the exercifes of fuchof his companions as were 
 not equal to the tallc themfelves. Among thefe was 
 his maternal uncle, who was frequently indebted to his 
 aflillance, and, on one occafion, produced a copy of ver- 
 fes of his compofition, which excited, not only the ap- 
 plaufe, but the admiration of their mailer. Mr Gra- 
 ham, who was but a few months older than Mr Bruce, 
 had, for fome tranfgrcffion (we know not what), been 
 punifhed, as boys in the great fchools in England are 
 often punifhed, by having a ta(l< fet him, whicli he loon 
 found himfelf unable to perform. His nephew delired 
 him to be under no uneafinefs, promiling to furnifli him 
 with the verfes before the time at which they were to 
 be given in. He was as good as his word ; but the 
 mailer of the fchool foon difcovei-ing that they were 
 not the performance of Mr Graham, exclaimed, that 
 the author of thefe verfes, whoever he was, might ap- 
 ply to himfelf the words of Horace, 
 
 Siibiimi feriam Jidera •vertice. 
 
 Wliile Mr Bruce was at Harrow, and for a year or 
 two after he had left it, he was of a very delicate 
 frame, and appeared to his friends to be threatened 
 with a confumption. The truth is, that he was un- 
 commonly tall for his age, and felt all the feeblenefs of 
 joints and other bodily weakneflTes to which overgrown 
 boys are generally fubjed. His father intended him 
 
 6 ] B R U 
 
 for the profciTun of the law; and, upon his return Trom 
 Harrow, he was entered into the miiveriity of Edin- 
 burgh, where he went through a regular courfe of ftudy 
 to fit him for being enrolled in the body of advocates : 
 but for fome reaf >n, which we do not perfectly know, 
 he relinquilhcd the ftudy of law for the purfnils of 
 trade; and, going to London, entered into partnerfhip 
 with a wine merchant of the name of Allen, whofe 
 daughter he married. 
 
 That lady falling into a bad ftate of health, Mr Bruce 
 took her abroad, in hopes that travelling would be at. 
 tended with beneficial effedls ; but in thefe he was dif- 
 appointed, as ftie died within a year after her marriage. 
 He was induced, in order to difpel his grief, to conti- 
 nue his travels ; during which his father dying (at E- 
 diiiburgh, 4th M.iy 1758), the inheritance of his .iiicel- 
 tors devolved upon him, and he returned to Britain. 
 Some of his fubfequent tranfadtions fhall now be rela- 
 ted in his own words. 
 
 " Every one will remember that period, fo glorious 
 to Britain, the latter end of the miniftry of the late earl 
 of Chatham. I was then returned from a tour through 
 the greateft part of Europe, particularly through the 
 whole of Spain and Portugal, between whom there was 
 then the appearance of an approaching war. 
 
 " I was about to retire to a fmall patrimony I had 
 received from my anceftors, in order to embrace a life 
 of ftudy and refleftion, nothing more adlive appearing 
 within my power, when chance threw me unexpeftedly 
 into 3 very fhort and very defultory converfation with 
 Lord Chatham. 
 
 " It was a few days after this that Mr Wood, then 
 under-fecretary of ftate, my zealous and fmcere friend, 
 informed me that Lord Chatham intended to employ me 
 upon a particular fcrvice ; that, however, I might go 
 down for a few weeks to my own country to fettle my 
 affairs, but, by all means, to be ready upon a call. No- 
 thing could be more flattering to me than fuch an ofler, 
 when fo young ; to be thought worthy by Lord Cha- 
 tham of any employment, was doubly a preference. No 
 time was loll on my fide; but juil after receiving orders 
 to return to London, his lordlhip had gone to Bath, 
 and refigned his office. 
 
 " This dil'appointment, which was the more fcnfible 
 to me that it was the tirft I had met with in public 
 life, was promifed to be made up to me by Lord Egre- 
 mont and Mr George Grenville. The former had been 
 long my friend ; but unhappily he was then far gone 
 in a lethargic indifpofition, which threatened, and did 
 very foon put a period to his exiftence. With Lord 
 Egremont's death my expeftations vanifhed. Further 
 particulars are unnecetTary ; but I hope that, at leaft in 
 part, they remain in that breaft where they naturally 
 ought to be, and where I fliall ever think, not to be 
 long forgotten, is to be rewarded. 
 
 " Seven or eight months were palFed in an expenfive 
 and fruitlefs attendance in London, when Lord Halifax 
 was pleated, not only to propofe, but to plan for me 
 a journey of confiderable importance, and which was to 
 take up feveral years. His lordfhip faid, that nothing 
 could be more ignoble than, at fuch a time of life, at 
 the height of my reading, health, andadivity, I fhould, 
 as it were, turn peafant, and voluntarily bury myfelf in 
 obfcurity and idlenefs; that though war was now draw- 
 ing fall to an end, full as honourable a competition re- 
 
 mained 
 
 Bruo
 
 B R U 
 
 [ 
 
 Bruce, mainet! jirriong men of fpirit, which Hiould acquit them- 
 '"'V""'' felves beft in the dangerous line ot uictul adventure and 
 difcovery. 
 
 «' He obferved, that the coaft of Barbary, wlu'ch 
 might be faid to be jult at our door, was yet but par- 
 tially explored by Dr Shaw, who had only illuilrated 
 (very judiciouiiy indeed) the geographical labours of 
 Sanfon; that neither Dr Shaw nor Saiilon had been, or 
 pretended to be, capable of giving the public any de- 
 tail of the large and magnificent remains of ruined ar- 
 chitetlure, which they both vouch to have fcen in great 
 quantities, and of exquiiite elegance and perfeftion, all 
 over the country. Such had not been their Ibidy, yet 
 fuch was really the tafte that was required in the pre- 
 fent times. He wiihtd, therefore, that I (liould be the 
 firll, in the reign jull now beginning, to fct an example 
 of making large additions to the royal collection ; and 
 he pledged himielf to be my fupport and patron, and to 
 make good to me, upon this additional merit, the pro- 
 mifes which had been held forth to me by former mi- 
 niiters for other fervices. 
 
 ■ " The difcovery of the fource of the Nile was alfo a 
 fubjeft of thefe converfations, but it was always men- 
 tioned to me with a kmd ot diffidence, as if to be ex- 
 pefled from a more experienced traveller. Whether 
 this was but another way of exciting me to the at- 
 tempt I Ihall not fay ; but my heart, in that inllant, 
 did ine juftice to fuggcft, that this too was either to 
 be atchieved by me, or to remain as it had done for 
 thefe laft 2000 years, a defiance to all travellers, and 
 an opprobrium to geography. 
 
 " Fortune feemed to enter into this fcheme. At the 
 ver)' inllant, Mr Afpinwall, very cruelly and ignonii- 
 nioufly treated by the dey of Algiers, had refigncd his 
 confulfliip, and Mr Ford a merchant, formerly thedey's 
 acquaintance, was named in his place. Mr Ford was 
 appointed, and, dj-ing a few days after, the confuKhip 
 became vacant. Lord Halitax prefled me to accept of 
 this as containing all forts of conveniences for making 
 the propofed expedition. 
 
 " This favourable event finally determined me. I had 
 all my life applied unweariedly, perhaps with more love 
 than talent, to drawing, the praftice of mathematics, 
 and efpecially that part neceflary to aftronomy. The 
 tranfit of Venus was at hand. It was certainly known 
 that it would be vifible once at Algiers, and there was 
 great reafon to expeft it might be twice. 1 had fur- 
 nidied myfelf with a large apparatus of inftruments, the 
 completell of their kind, for the obfervation. (n the 
 choice of thefe, 1 had been aflilled by my friend Ad- 
 miral Campbell, and Mr Ruffel fecretary to the Turkey 
 Company : every other neceflary had been provided in 
 proportion. It was a pleafure now to know that it 
 was not from a rock or a wood, but from my own houfe 
 at Algiers, I could deliberately take nieafures to place 
 myfelf in the lift of men of fcience of all nations, who 
 were then preparing for the fame fcientific purpofe. 
 
 " Thus prepared, I fet out for Italy, through France ; 
 and though it was in time of war, and fome ftrong ob- 
 jections had been made to particular paifports, folicited 
 by our government from the French fecretary of ftate, 
 Monfieur de Choifeul moil obligingly waved all fuch 
 exceptions with regard to me, and moft politely affu- 
 red me, in a letter accompanying my pafTport, that 
 thofe difficulties did not in any ihape regard me, but 
 
 27 ] B II U 
 
 that 1 was perfefdy at liberty to pafs throug'i, or re- 
 main in, France with thofe that accompanied me, with-^ 
 out limiting tlieir number, as Ihort or as long a time as 
 ihould be agreeable to mc. 
 
 " On my arrival at Rome, I received orders to pro- 
 ceed to Naples, there to await his majefty's further 
 commands. Sir Charles Saunders, tlien witli a fleet 
 before Cadiz, liad orders to vifit Malta before he re- 
 turned to England. It was faid tiiat the grand-mailer 
 of that order iiad behaved fo improperly to Mr Har- 
 vey (aftei-wards Lord Brillol) in the beginin'ng of the 
 war, and fo partially and unjuftly between the two na- 
 tions in the courfe of it, that an explanation on our 
 part was btcome neceflary. The grand-mafter no foon- 
 er heard of my arrival at Naples, than, guefling the er- 
 rand, he fent off Chevalier Mazzini to London, where 
 he at once made his peace and his compliments to his 
 majelly u.pon his acccffion to the throne. 
 
 " Nothing remained now but to take pontlfion of 
 my confullhip. I returned,^ without lofs of time, to 
 Rome, and from thence to Leghorn, where, having em- 
 barked on board the Montreal man of war, I proceeded 
 to Algiers. 
 
 " While at Naples, I received from (laves, redeemed 
 from the province of Conftantine, accomits of magnifi- 
 cent ruins they had feen while traverfing that country 
 with their mailer the Bey. I faw the abfohite neceffity 
 there was for affiftancc, without which it was impoflible 
 for any one man, however diligent and qualified, to do 
 any thing but bewilder himfelf. All my endeavours, 
 however, had hitherto been unfuccefsful to perfuadeany 
 Italian to put himfelf wilfully into the hands of a peo- 
 ple conftantly looked upon by them in no better light 
 than pirates. At lall Mr I^umifden, by accident, heard 
 ot a young man who was then lludying architcfture at 
 Rome, a native of Bologna, whofe name was Luicri Ba- 
 lugani. I can appeal to Mr Lumifden as to the extent 
 ot this perfon's pradice and knowledge, and that he 
 knew very little when firll fent to me. In the twenty 
 months which he ftaid with me at Algiers, by affiduous 
 application to proper fubjefts under my inllruftion, he 
 became a vei^ confiderable help to me, and was the on- 
 ly one that ever I made ufe of, or that attended me for 
 a moment, or ever touched one reprefentation of archi- 
 teiSure in any part of my journey." 
 
 Our traveller, when in Spain, liad endeavoured to 
 find accefs to that immenfe collcdlion of Arabic manu- 
 fcripts which were perilliing in the dud of the efcurial; 
 but in vain. " All my fuccefs (fays he) in Europe termi- 
 nated in the acquifition of thofe few printed Arabic 
 books tliat I had found in Holland ; and thefe were 
 rather biographers than general hillorians, and contain- 
 ed little in point of general information. The ftudy of 
 thefe, however, and of Maracci's Koran, had made me 
 a very tolerable Arab; a great field was opening before 
 me in Africa to complete a coUedlion of manufcripts, 
 an opportunity which 1 did not negleft. 
 
 " After a year fpent at Algiers, conflant converfa- 
 tion with the natives while abroad, and with my manu- 
 fcripts within doors, had qualified me to appear in any 
 part of the continent without the help of an interpreter. 
 Ludolf had afTured his readers, that the knowledge of 
 any oriental language would foon enable them to ac- 
 quire the Ethiopic ; and I needed only the fame num- 
 ber of books to have made my knowledge of that lan- 
 guage 
 
 Bruce.
 
 « R U [ 12 
 
 Bruff. giiase go hand in hand with my attainments in the A- 
 ~~v-— ' raljic. My immediate prol'peft of fetting out on my 
 journey to the inland parts of Africa had made me 
 "double my dih'gence ; ni<rht and day there was no re- 
 laxation from thefe ftudies, although the acquiring any 
 fingle language had never been with me either an objeft 
 of time or difficulty." 
 
 At Algiers Mr Bruce was detained longer than he 
 expcfted, in confequcnce of a difpute with the Dey 
 concerning Mediterranean paffcs. This being adjufted, 
 he proceeded to Mahon, and from Mahon to Carthage. 
 He next vitited Tunis and Tripoli, and travelled over 
 the interior parts of theic ftates. At Bengazi, a fmall 
 •town on the Mediterranean, he fuffered Ihip wreck, and 
 with extreme difficulty faved his life, though with the 
 lofs of all his baggage. He afterwards failed to the 
 ides of Rhodes and Cyprus, and proceeding to Aha 
 Minor, travelled through a confiderable part of Syria 
 and Paleftine, vifiting Haflia, Latikea, Aleppo, and 
 Tripoli ; near which laft city he was again in imminent 
 danger of perifliing in a river. The ruins of Palmyra 
 and Baalbec were next carefully furveyed and fetched 
 by him ; and his drawings of thefe places are depiofited 
 in the king's library at Kew ; " the moft magnificent 
 prefent in that line," to ufe his own words, " ever made 
 by a fnbjedl; to his fovereign." 
 
 It is much'to be regretted that Mr Bruce publifhed 
 no particular account of thefe various journeys ; from 
 the nature of the places viiited, and the abilities of the 
 man, much curious and ufeful information might have 
 been expefted. Some manufcript accounts of different 
 parts-of them are faid to have been left by him, but 
 whether in fuch a ftate as to be fit for publication, we 
 liave not learned. 
 
 In thefe various travels fome years were paffed ; and 
 Mr Bruce now prepared for the grand expedition, the 
 accomplifhment of which had ever been nearefl. his 
 heart, the difcovery of the fources of the Nile. In the 
 profecution of that dangerous objeft, he left Sidon on 
 the 15th of June 1768, and arrived at Alexandria on 
 the 20th of that month. He proceeded from thence 
 to Cairo, where he continued to the 12th of December 
 following, when he embarked on the Nile; and in a ve- 
 ry extraordinary boat, called a canja, of which he fays 
 the main-fail yard was about 200 feet in length, he fail- 
 ed up that river as far as Syene, vifiting in the courfe 
 cf his voyage the ruins of Thebes, and the place where 
 Memphis once flood, now known by the name of jlff- 
 frahsnny. Leaving Kenne on the Nile, i6th February 
 ! 769, he crofTed the defert of the Thebaid to Cofl'cir 
 on the Red Sea, and arrived at Jidda on the 3d of May. 
 In Arabia FeUx he remained, not without tnaking feve- 
 ral excurfions, till the 3d of September, when he failed 
 from Loheia, and arrived on the 19th at Mafuah, where 
 he was detained near two months by the treachery and 
 avarice of the Naybe of that place. It was not till the 
 15 th of November that he was allowed to quit Arkeeko, 
 
 8 ] B R U 
 
 near Mafua ; and he arrived on the i ;th of February 
 1770 at Gondar, the capital of Abyflinia, where he 
 ingratiated hinifclf with the mofl confiderable perfons 
 of both fexes belonging to the court. This he accom- 
 plilhed by being a phyficiau in the city, a foldier in the 
 field, a courtier everywhere, demeaning himfelf as con- 
 fcious that he was not unworthy of being a companion 
 to the firfl of their nobility, and the king's gueft, which 
 is there a charafter, as it was with eaftern nations of 
 old, to which a certain fort of confideration is due. 
 " To this I may add (fays he), that, being in the prime 
 of life, of no ungracious figure, having an accidental 
 knack, which is not a trifle, of putting on the drel's, 
 and fpeaking the language eafily and gracefully, I cul- 
 tivated, with the utmoft afTiduity, the friendfliip of the 
 fair fex, by the moil modeft and refpeflful diflant at- 
 tendance and obfequioufncfs in public, abating jufl as 
 much of that in private as fuited their humours and in- 
 clination ;" and jealoufy being a paffion unknown in 
 AbyfTinia, he thus acquired from the ladies great fup- 
 port at court. 
 
 Several months were employed in attendance on the 
 king, and in an unfuccefsful expedition round the lake 
 of Dambea. Towards the end of Oilober Mr Bruce 
 fet out for the fources of the Nile ; at which long de- 
 fired fpot he arrived on the 14th of November; and his 
 feelings on the accomplifhment of his wifhes cannot bet- 
 ter be exprcffed than in his own words: 
 
 " It is eafier to guefs than to defcribe the fituation 
 of my mind at that moment ; flanding in that fpot 
 which had baffled the genius, induftry, and inquiry, of 
 ancients and moderns for the courfe of near 3000 years. 
 Kings had attempted this difcovery at the head of ar- 
 mies, and each expedition was diflinguifhed from the 
 lafl only by the difference of the numbers which had 
 perifhed, and agreed alont^ in the difappointment which 
 had uniformly, and without exception, followed them 
 all. Fame, riches, and honour, had been held out for 
 a feries of ages to every individual of thofe myriads 
 thofe princes cotnmanded, without having produced one 
 man capable of gratifying the curiofity of his fovereign, 
 or wiping off this flain upon the enterprife and abilities 
 of mankind, or adding this defideratum for the encou- 
 ragement of geography. Though a mere private Bri- 
 ton, I triumphed here in my own mind over kings and 
 their armies ; and every comparifon was leading nearer 
 and nearer to the prefumption, when the place itfelf 
 where I flood, the objedt of my vain glory, fuggefted 
 what depreffed my fhort lived triumphs." 
 
 If thefe triumphs were fhort-lived, they were equally 
 ill-founded : for if the fource of the Nile was feen by 
 Mr Bruce, there can be no doubt of its having been 
 likewife feen by the Portuguefe jefuits. Of this we 
 have elfe where brought forward fufiicient proof; and 
 the candid reader, who fhall take the trouble to com- 
 pare the extraft printed at the bottom of this page (a), 
 with our traveller's account of thefe coy fountains, as it 
 
 flands 
 
 Bruce. 
 
 (a) " In the eaftern part of this kingdom, on the declivity of a mountain, whofe defcent is fo eafy that it 
 feems a beautiful plain, is that fource of the Nile which has been fought after at fo much expence of labour, and 
 about which fuch a variety of conjeftures hath been formed without fuccefs. This fpring, or rather thefe two 
 fprings, are two holes, each about two feet diameter, a ftone's call diftant from each other. The one is about 
 five feet and an half in depth, at leafl we could not get our plummet farther, perhaps becaufe it was Hopped by 
 
 roots.
 
 B R U 
 
 [ 12 
 
 ftands in his own book or in our article Nile [Encyr!.), 
 ' will be convinced th;it it was ridiculous in Mr Bruce, 
 and is equally ridiculous in liis friends, to prcicnd that 
 he difcovn-ed what had baffled the genius of inquiry fur 
 the courfe of near 3000 years. 
 
 It was not, iiowever, the confcioufnefs of having 
 been anticipated by the jefuits (for thcfe he without ce- 
 remony calls a fet of liars), but the profpeft of danger 
 to be encountered on his return to Europe, that call 
 fnch a damp on iiis jnefcnt enjoyment. " 1 was but a 
 few minutes (I'aye he) arrived at the lource of the Nile, 
 through numberlefs dangers and fnfferings, the lead of 
 which would have overwhelmed me, but for the conti- 
 nual goodnefs and proteftion of Providence ; I was, 
 however, but then half through my journey, and all 
 thofe dangers which I had already pafled awaited me 
 again on my return. I found a defpondency gaining 
 ground fall upon me, which blafted the crown of laurels 
 I had too rafhly woven for myfelf." 
 
 When he returned to reft the night of that difcovery, 
 repofe was fought for in vain. " Melancholy refieftions 
 upon my prefcin ftate, the doubtfulnefs of my return in 
 fafety, were I permitted to make the attempt, and the 
 fears that even this would be refiifed, according to the 
 rule obferved in Abyffinia with all travellers who have 
 once entered the kingdom ; the confcioufnefs of the 
 pain that I was then occafioning to many worthy indi- 
 viduals, expedting daily that information concerning my 
 fituation which it was not in my power to give them : 
 fome other thoughts, perhaps ftill nearer the heart than 
 thofe, crowded upon my mind, and forbade all approach 
 of fleep. 
 
 " I was, at that very moment, in pofleflion of what 
 had for many years been the principal objedl of my am- 
 bition and wilhes ; indifference which, from the ufual 
 infirmity of human nature, follows, at leaft for a time, 
 complete enjoyment, had taken place of it. The marfli, 
 and the fountains, upon comparilon with the rife of 
 many of our rivers, became now a trifling object in my 
 fight. I remembered that magnificent fcene in my 
 own native country, where the Tweed, Clyde, and An- 
 nan, rife in one hill ; three rivers I now thought not 
 inferior to the Nile in beauty, preferable to it in the 
 cultivation of thofe countries through which they flow; 
 fuperior, vaftly fuperior, to it in the virtues and qualities 
 of the inhabitants, and in the beauty of its flocks, 
 crowding its paftures in peace, without fear or violence 
 from man or beaft. I had feen the rife of the Rhine 
 and Rhone, and the more magnificent fources of the 
 Soane ; I began, in my furrow, to treat the inquiry 
 
 SuppL. Vol. I. Parti. 
 
 9 ] B R U 
 
 about the fource of the Nile as a violent effort of a dif- 
 Dempered fancy. 
 
 ' What's Hecuba to him, or he to Hccubai 
 ' That he Ihoiild weep for lier ?' 
 
 Grief and dtf[)ondency now rolling upon me like a tor- 
 rent, relaxed, not refreflied, by unquiet and iniperfcil 
 fleep, J darted from my bed ii\ the utmoft agony ; I 
 went to the door of my tent, every thing was ftill ; the 
 Nile, at whole head I ftood, was not cajiable cither to 
 promote or to interrupt n.y flumbers, but the coolnefs 
 and fcrenity of the night braced my nerves, and chafed 
 away thofe phantoms that while in bed had opprefl'ed 
 and tormented me. 
 
 " It was true that numerous dangers, hardfliips, and 
 forrows, had befet me through this half of my excur- 
 fion ; but it was ftill as true, thi't another Guide, more 
 powerful than my own courage, health, or underfland- 
 ing, if any of them can be called man's own, had uni- 
 formly protefted me in all that tedious half. 1 found 
 my confidence not abated, that ftill the (ame Guide was 
 able to condutl me to my wiftiedfor home. I imme- 
 diately refumed my former fortitude, confidered the 
 Nile as indeed no more than rifing from fprings as all 
 other rivers do, but widely differing in this, that it was 
 the palm for 3000 years held out to all the nations of 
 the world as a dclur HignjJJnno, which in my cool hours 
 I had thought was \\orth the attempting at the rifli of 
 my life, which I had long either rcfolved to lofe, or lay 
 this difcovery a trophy in which I could have no com- 
 petitor, for the honour of my country, at the feet of 
 my fovereign, whole fervant I w<ft." 
 
 How unworthy is this ranting refleftlon of the great- 
 nefs of mind which Mr Bruce on other occafions un- 
 queftionably difplaycd ! Had he indeed been the firft 
 European who difcovered thofe pitiful holes from which 
 the Nile is faid to flow, his merit would not have con- 
 filled in travelling from Gondar to the village Geeih, 
 and viewing the fountains which are at that village the 
 objefts of idolatrous adoration, but in the addrefs with 
 which he contrived to make himfelf the favourite of all 
 the fadlions which agitated a barbarous and almoft in- 
 human nation. In managing thole faftions, he was in- 
 deed great ; but he feems to have valued himfelt more 
 upon looking at three fprings, of which it is tar from 
 being certain that they are the fources of the Nile (fee 
 Nile in this SuppL), and of which two had certainly 
 been examined more than a century before he was born, 
 by diff'creiit miflionaries from the kingdom of Portu- 
 gal ! This, however, he calls the objcft of his wiflies ; 
 R and 
 
 Briic 
 
 roots, for the whole place is full of trees : of the other, which is fomewhat lefs, with a line of ten feet, we could 
 find no bottom, and were aflured by the inhabitants that none ever had been found. It is believed here that 
 thefe fprings are the vents of a great fubterraneous lake ; and they have this circumftance to favour their opinion, 
 that the ground is always moift, and fo foft that the water boils up under foot as one walks upon it. Such is 
 the ground round about thefe fountains. At a little diftance to the fouth is a village named Guix (the GcJh of 
 Mr Bruce), through which the way lies to the top of the mountain, whence the traveller difcovers a vail extent 
 of land, which appears like a deep valley, though the mountain rifes fo imper,ceptibly, that thofe who go up or 
 down it are fcarce fenfible of any declivity." — Johnfori's Tranjlation of Father Lobo's Voyage to Abyjfma, Chap, X. 
 The only diff'erence between Lobo's and Bruce's account of thefe fountains worthy of notice is, that the for- 
 iti-r found but tiuo, while the latter found t1>ree holes ; but Bruce fays exprelsly, that the holes are partly artifi- 
 cial ; and Lobo's defcripiion of them indicates the fame thing. It is therefore not improbable that there may 
 now be four or five holes.
 
 B R U [ 130 ] 13 R U 
 
 Broce. and having now accomplifhed it, he bent his thoughts journey ; the perils attending which lie has related with 
 """^on his return to his native country. "a power of pencil not unworthy of the greatcil mailers. '" 
 
 He arrived at Gondar on the 19th November 1770 ; All his camels having perilhed, Mr Bruce was under the 
 
 but found, after repeated foh'citations, that it was by neceffity of abandoning his baggage in the defert, and 
 
 no means an cafy talk to obtain permiiTion to quit Abyf- with the greateft difficulty reached Aflbuan upon the 
 
 finia. A civil war in tlie mean time breaking out (no Nile on the 29th of November. 
 
 uncommon occurrence in that barbarous country), feve- After fome days reft, having procured frelh camels, 
 ral engagements took place between the king's foices he returned into the defert, and recovered his baggage, 
 and the troops of the rebels, particularly three aftions among which is particularly to be remarked a quadrant 
 at a place called Serbraxos on the 19th, 20th, and 23d (of three feet radius) fupplied by Louis XV. from the 
 of May 177 I. In each of them Mr Bruce afted a con- Military Academy at Marfeilles ; by means of which 
 fiderable part; and for his valiant conduct in the fecond noble inftrument, now depofited in the Mufeum at Kin- 
 received, as a reward from the king, a chain of gold, of naird, Mr Bruce was enabled with precifion and accu- 
 184 links, each link weighing i^t't dwts. or fomewhat racy to fix the relative fituations of the feveral remote 
 more than 2^ lbs. troy in all. At Gondar, after thefe places he vifited. 
 
 engagements, he again preferred the moil earneft entrea- On the loth of January 1773, after more than four 
 ties to be allowed to return home, entreaties which were years abfence, he arrived at Cairo, where, by his manly 
 • long refilled ; but his health at laft giving way, from and generous behaviour, he fo won the heart of Maho- 
 the anxiety of his mind, the king confented to his de- met Bey, that he obtained a firman, permitting the 
 parture, on condition of his engaging by oath (b) to commanders of Englifh veflels belonging to Bombay 
 return to him in the event of his recovery, with as ma- and Bengal to bring their fhips and merchandife to- 
 ny of his kindred as he coyld engage to accompany Suez, a place far preferable in all refpefts to Jidda, to 
 },j[n_ which they were formerly confined. Ot this permif- 
 
 After a rcfidence of nearly two years in that wretch- fion, which no European nation could ever before ac- 
 ed country, Mr Bruce left Gondar on the 1 6th of De- quire, many Englilh velTels have fince availed them- 
 cember 1771, taking the dangerous way of the defert felves ; and it has proved peculiarly ufeful both in pub- 
 of Nubia, in place of the more eafy road of Mafuah, lie and private difpatches. Such was the worthy con- 
 by which he entered Abyffinia. He was induced to clufion of his memorable journey through the defert; a 
 take this route from his knowledge and former expe- journey which, after many hardfhips and dangers, ter- 
 rience of the cruel and favage temper of the Naybe of minated in obtaining this great national benefit. 
 Mafuah. Arriving at Teawa the 21ft March 1772, he At Cairo Mr Bruce's earthly career had nearly been 
 had the misfortune to find the Shekh Fidele of Atbara, concluded by a diforder in his leg, occafioned by a 
 the counterpart of the Naybe of Mafuah in every bad worm in the fielh. This accident kept him five weeks 
 quality : by his intrepidity and prudence, however, and in extreme agony; and his health was not re-eftablilhed 
 by making good ufe of bis foreknowledge of an eclipfe till a twelvemonth afterwards, at the baths of Porretta 
 of the moon, which happened on the 17th of April, he in Italy. On his return to Europe, Mr Bruce was re- 
 was permitted to depart next day, and he arrived at ceived with all the admiration due to fo exalted a cha- 
 Sennaar on the 29th of the fame month. rafter. After pafiing fome confiderable time in France, 
 
 Mr Bruce was detained upwards of four months at particularly at Montbard, with his friend the Comte de 
 that miferable and inhofpitable place ; the inhabitants of BufFon, by whom he was received with much hofpita- 
 which he defcribes in thefe expreffive words : " War lity, and is mentioned with great applaufe, he at laft rc- 
 and treafon feem to be the only employment of thefe vifited his native country, from which he had been up- 
 horrid people, whom heaven has feparated by almoft wards of twelve years abfent. 
 
 impaffable deferts from the reft of mankind, confining It was now expefted that he would take the earlieft 
 
 them to an accurfed fpot, feemingly to give them an opportunity of giving to the world a narrative of his 
 
 earneft in time of the only other worfe which he has travels, in which the public curiofity could not but be 
 
 leferved to them for an eternal hereafter." This delay deeply interefted. But feveral circumftances contribu- 
 
 was occafioned by the viUany of thofe who had under- ted to delay the publication ; and what thefe were will 
 
 taken to fupply him v^ith money ; but at laft, by dif- be beft related in his own words : 
 
 pofing of 178 links of his gold chain, the well-earned " My friends at home gave me up for dead ; and as 
 
 trophy of Serbraxos, he was enabled to make prepara- my death muft have happened in circumftances difficult 
 
 tion for his dangerous journey through the deferts of to have been proved, my property became as it were a 
 
 J^ubia. hicreditas jacens, without an owner, abandoned in com- 
 
 He left Sennaar on the 5th of September, and ar- mon to thofe whofe original title extended no further 
 
 rived on the 3d of Oftober at Chendi, which he quit- than temporary poffeffion. 
 
 ted on the 20th, and travelled through the defert of " A number of law-fuits were the inevitable confe- 
 
 Gooz, to which village he came on the 26th of Odlo- quences of this upon my return. To thefe difagreeable 
 
 ber. On the 9th of November he left Gooz, and en- avocations, which took up much time, were added others 
 
 tered upon the moft dreadful and dangerous part of his ftill more unfortunate. The relentlefs ague, caught at 
 
 Bengazi, 
 
 (b) With regard to this oath, Mr Bruce fays, that he hopes the difficulty of performing it extinguifited the 
 fin of breaking it ; and that, at any rate, it being merely perfonal, his engagement to return ceafed with the 
 death of the king, of which he received intelligence during his ftay at Sennaar,
 
 B R U [13 
 
 uce. Bengazi, maintained its ground, at times, for a fpace of 
 
 V ■ more than 16 years, though every remedy had been 
 
 nfed, hut in vain ; and what was word uf all, a h'nger- 
 ing dilleinper had ferloufly threatened the h'fe of a mod 
 near relation (his fecond wife), which, after nine years 
 conftant alarm, where every duty bound me to attention 
 end attendance, condudled her at lad, in very early life, 
 to her grave." 
 
 Amidft the anxiety and the diftrefs thus occafioned, 
 Mr Bruce was by no means negleftful of his private af- 
 fairs. He confiderably improved his landed property, 
 enclofing and cultivating the wafte grounds, and he high- 
 ly embellilhed his paternal feat, making many additions 
 to the houfe, one in particular of a noble mufeum, filled 
 with the moll precious (lores of oriental literature, large 
 coUeftions of drawings made, and curious articles ob- 
 tained, during his far extended peregrinations. An ex- 
 cellent ftratum of coal at Kinnaird drew much of his at- 
 tention : he erefted fteam engines of the moll approved 
 conftruftion, and placed his coalery on fuch a footing 
 that, at the period of his deceafe, it produced about 
 aoool. a-year. 
 
 The termination of fome law-fuits, and of other bufi- 
 nefs, which had occupied much of his time, having at 
 length afforded leifure to Mr Bruce to put his mate- 
 rials in order, his greatly defired and long expedled 
 work made its appearance in 1790, in five large quarto 
 volumes, embellilhed with plates and charts. It is un- 
 receffary, and might be tedious, to enter at prefent in- 
 to any critic or analyfis of this celebrated work. It is 
 vuiiverfally allowed to be replete with much curious and 
 ufeful information ; and to abound in narratives which 
 at once excite our admiration and intereft our feelings. 
 The very Angular and extraordinary pifture which it 
 gives of Abyflinian manners, ftartled the belief of fome; 
 but thefe manners, though ftrange in the fight of an 
 European, are little more than might be expedled in 
 fuch a barbarous country ; and had an enlightened phi- 
 lofopher vifited Scotland in the times of our earlieft mo- 
 narchs, he might perhaps have witnefled and related 
 fcenes, different indeed from what Mr Bruce faw in 
 AbyfTmia, but which to us would have feemed equally 
 ftrange. 
 
 A more ferious objeftion to the truth of Mr Bruce's 
 narrative was darted by an anonymous, but able, cri- 
 tic *, in an Edinburgh newfpaper, foon after the pub- 
 *^"PP° lication, from the account of two adronomical phe- 
 'lotheram nomena, which could not pojjibly have happened, as Mr 
 l.rofeflbr of Bruce afferts. The firll of thefe is the appearance of 
 i»turalpM-tln; new moon at Furfhout, during Mr Bruce's day in 
 oiophy in ^^.^^ place, which he mentions to have been from 25th 
 iity of St December 1768 to the 7th of January 1769 ; and on a 
 Andrew's, particular day in that interval aflTcrts, that the new moon 
 was feen by a fakir, and was found by the ephemerides 
 to be three days old ; whereas it is certain that the 
 moon changed on the 8th of January 1769. The other 
 phenomenon appears equally impollible. At Teawa 
 Mr Bruce fays he terrified the Shekh by foi-etelling 
 that an eclipfc of the moon was to take place at four 
 afternoon of the 17th of April 1772 i that accordingly, 
 foon after that hour, he faw the eclipfe was begun ; and 
 when the fhadow was half over, told the Shekh that in 
 a little time the moon would be totally darkened. Now-, 
 by calculation, it is certain that at Teawa this eclipfe 
 mud have begun at 36 minutes pad four, and the mooa 
 
 I j B R U 
 
 have been totally covered at 33 minutes pad five; while Brucp 
 the fun fet there a few minutes pad fix, before which """V"" 
 time the moon, then in oppofition, could not have ri- 
 fen : fo that as the moon rofe totally eclipfed, Mr Bruce 
 could not fee the diadow half over the diflc, nor point 
 it out to the Shekh. To thefe objeftions, which ap- 
 pear unfurmountable, Mr Bruce made no reply, though 
 in converfation he faid he would do it in the fecond edi- 
 tion of his book. 
 
 Thefe are midakes which can hardly be accounted 
 for by attributing them to the inaccuracy of his notes, 
 or indeed to any caufe which we are inclined to name ; 
 and perhaps he has fallen into a miflake of the fame 
 kind in his account of the enormous main-fail yard of 
 the canja, in which he failed up the river Nile. To 
 every man who has but dipped into the fcience of me- 
 chanics, it is known that a beam of wood ,00 feet in • 
 length, mud be of proportional thicknefs, or it would 
 fall in pieces by its own weight. This thicknefs mud 
 be greatly increafcd, to enable it to bear the drain oc- 
 cafioned by a prodigious fail filled with wind; and thofe 
 only who have been at the Nile, and have feen the can- 
 jas, can fay, whether thefe veffels, or indeed any vef- 
 fels which can be employed on that river, would not 
 be overfet by yards, 
 
 To equal which, the tailed pine 
 
 Hewn on Norwegian hills, to be the mad 
 Of fome great admiral, were but a wand. 
 
 The language of the work is in general harfli and un- 
 polifhed, though fometimes animated. Too great a 
 dilplay of vanity runs through the whole, and the ap- 
 parent facility with which the traveller gained the mod 
 familiar accefs to the courts, and even to the harams of 
 the fovereignsof the countries through which he palftd, 
 is apt to create in readers fome doubts of the accuracy 
 of the narration. Yet there appears upon the whole 
 fuch an air of manly veracity, and circumilances are 
 mentioned with a minutenefs fo unlike deceit, that thefe 
 doubts are overcome by the general impreffion of truth, 
 which the whole detail irrefidibly fadens upon the mind. 
 The charadler of Ras Michael has often ftruck us, as 
 containing very drong internal evidence of its having 
 been taken from nature ; for it is fuch a charafter, at 
 once extraordinary and confident, as neither Mr Bruce, 
 nor perhaps any writer fince Shakefpeare, had genius 
 to feign. 
 
 The fird impveflion of the book being almoft difpo- 
 fed of, Mr Bruce had ftipulated with an eminent book- 
 feller in London for a fecond edition to be publifhed, 
 we think in odlavo ; and he was bufy in preparing that 
 edition for the prefs when death removed him from 
 this tranfitoiy dage. On the 26th of April 1794 he 
 entertained fome company at Kinnaird-houfe with his 
 ufual hofpitality and elegance. About eight o'clock in 
 the eveninpr, when his guefis were ready to depart, be 
 was handing one of the ladies down flairs, when, having 
 reached the feventh or eighth flep from the bottom, his 
 foot flipped, and he fell down headlong. He was taken 
 up fpeechlefs ; his face, particularly the forehead and 
 temples, being feverely cut and bruifed, and the bones 
 of his hands broken. He continued in a date of appa- 
 rent infenfibility for eight or nine hours, and expired on 
 Sunday the 27th, in the 64th year of his age. 
 
 Mr Bruce's fecond wife, whom he married on the 
 R 2 icth
 
 B R U> [ 132 ] BUG 
 
 Bnicc. 20tK May 1776, was Mary, eldell daughter of Tho. TarfliJfli had been controverted by Dr Dofg of Stirling, 
 
 * ' mas Dundas, Efq; of Carron-ball, by I.ady Janet Malt- he earneftly courted the acquaintance of that eminent 
 
 land, daughter of Charles fixth Earl of Lauderdale. By 
 
 that lady, who, after a fcvcre and lingering indilpoli- xmci u.s <v...i".. ..>^ ...^ v,„,, ^w..,.,.. j, .^v .....utu luun- 
 
 tion died in 1784, he bad three children, of whom one ly at Kinnaird ; and till he became corpulent, fpent 
 
 fon Lnd one daughter furvivc him. much of his time in the various fporta of the field, in 
 
 Mr Cruce's pcrfon was large, his height exceeding which he engaged with great ardour. Though ttudious 
 
 fix feet, his bulk, being in proportion to his height j in youth, and at all times a ftranger to intemperance 
 
 and at the period when he entered on his dangerous ex- and diffipation, he read but little in his later years; and 
 
 pedition, he was equally remarkable for ftrength and feemed to find his cliief pleafure in converfation, efpe- 
 
 for agility. To thofe who never beheld him, the en- cially the converfation of well-informed ladies. In his 
 
 i.ravcd medallion in the title pages of the firft and third friendlhips he fometimes appeared to be capricious, at- 
 
 vo'lumes of his Travels will convey fome idea of his fea- taching himfelf to men in whofe heads and hearts no 
 
 tures. He excelled in all manly aecompliftments, being other perfon could perceive a charm for a mind lik'e his. 
 
 trained to exercife and fatigue of every kind. He was Though in his own deahngs he was always juft and ho- 
 
 a hardy, pradifed, and indefatigable fwimmer ; and his nourable, he was too ready to apprehend unfairnefs in 
 
 long residence among the Arabs had given him a more others, and to exprefs fuch apprehenfions with undue 
 
 than ordinary facility in managing the horfe. In the ufe warmth. To ftrangers he was often arrogant, and 
 
 of fire-arms lie was fo unerring, that in innumerable in- fometimes infolent ; but in his own family he was an 
 
 fiances he never failed to hit the mark ; and his dexte- affeaionate hufband, a kind father, an agreeable enter- 
 
 rity in handling the' fpear and lance on horfeback was tainer, and to his fervants a mailer perhaps too indul- 
 
 alfo uncommonly great. He was niafter of moft Ian- gent. In converfation, as well as in his writings, he 
 
 ges ; and was fo well (l<illed in oriental literature, embraced every opportunity of expreffing a deep and 
 
 t he revifed the New Tellament in the Ethiopic, Sa- lively fenfe of the care of a fuperintending Providence, 
 
 Bruce, 
 Buck, 
 wheat,. 
 
 without which he was convinced that tliere could be no' 
 fafety in human ftrength or human forefight. His belief 
 of the Chriftian religion retted on the furell grounds ; 
 and fuch was his veneration for the facrcd writings, that 
 for fome years before his death they feemed to occupy 
 all the time which he gave to ttudy. He read no fer- 
 mons, however elegant ; and dlifuaded others from fucli 
 reading. " Read the Bible (faid he), and you will 
 foon perceive the emptinefs of the moft applauded fei-- 
 
 gua 
 
 that . - rr 1 
 
 maritan, Hebrew, and Syriac, making many uletul 
 notes and remarks on difiicult paffages. He had ap- 
 plied from early youth to mathematics, drawing, and 
 aftronomy, and had acquired fome knowledge of phyfic 
 and furgery. His memory was aftonilhingly retentive, 
 and his mind vigorous. He was dexterous in negocia- 
 tion, a matter of public bufinefs, and animated with the 
 warmeft zeal for the glory of his king and country. 
 Such, at leaft, is his oaun reprefentatlon of his charac- 
 ter ; and though an impartial judge would probably mons." 
 make confiderable abatement for the natural bias of a BUCK-wheat, a fpecies of Polyganum (fee that 
 man drawing his own portrait, yet it cannot be denied, zrude EncycL), was firft introduced into Europe about 
 that in perfonal accompllfiiments Mr Bruce equalled, if the end of the 15th or the beginning of the i6th cen- 
 not exceeded, moft of his contemporaries. tury. According to fome botanifts, who lived at that' 
 Thus accomplifhed, he could not but be eminently period, its native country is the northern parts of Afia, 
 fitted for an attempt fo full of difficulty and danger as whence it was brought to Germany and France, where, 
 what he called the difcovery of the fources of the Nile : about the year 1587, it was the common food of the 
 no one who perufes his account of the expedition, can poor. 
 
 fail to pay an unfeigned tribute of admiration to his A new fpecies of this grain, or, to fpeak perhaps 
 
 intrepidity, manlinefs, and uncommon dexterity, in ex- more properly, a variety of this fpecies, has been for 
 
 tricatirg himfelf out of fituatlons the moft dangerous fome time known under the name of Siberian buck- 
 
 and alarming, In the courfe of his long and hazardous wheat, which appesrs to have confiderable advantages 
 
 journey ; not to mention his conduft during his refi- over the former. It was fent from Tartary to St Pe- 
 
 dence in AbyfTinia, his behaviour at Mafuah, Teawa, terfburgh by the German botanifts, who travelled thro* 
 
 and Sennaar, evinces the uncommon vigour of his mind : that country In the beginning of the prefent century ; 
 
 but it was chiefly during his paffage through the Nu- and it has thence been difperfed over all Europe. Lin- 
 
 bian defert, that his fortitude, courage, and prudence, n«us received the firft ieeds of it in 1737 from Garber 
 
 appeared to the greateft advantage. Of his learning the botanift, and defcribed the plant in his Hortus Clif- 
 
 and fagacity, his delineation of the courfe of Solomon's fertionus. After this it was mentioned by Ammann in 
 
 fleet from Tarlhlih to Ophir, his account of the caufe 1739 : but it muft have been earlier known in Gcrma- 
 
 of the inundations of the Nile, and his comprehenfive ny ; for in 1733 it was growing in the garden of Dr 
 
 view of the Abyflrnlan hiftory, afford ample proofs. It Ehrhart at Memmingen. In Siberia this plant fows it- 
 
 muft indeed be confefled, that in his account of the in- felf for four or five years by the grains that drop ; but 
 
 undations of the Nile, as well as in his delineation of at the end of that period the land becomes fo full of 
 
 the courfe of Solomon's fleet, he has not the merit of tares that it is choked, and mutt be fown afrelh. Even 
 
 originality; but on both thefe occafions he has ftated in the economical gardens of Germany, It is propagated 
 
 the hypothefis which he maintains with greater clear- in the fame manner; and in that country it is in lome 
 
 nefs, and fupported it with more plaufible argumei;ts, places found growing wild, though it is nowhere culti- 
 
 than any other author whofe writings have fallen into vated In the neighbourhood. It is not, however, indi- 
 
 our hands ; and it was furely to his honour, that as foon genous, otherwife Ehrhart might have raifed it from 
 
 as he learned that his hypothefis refpefting Ophir and German feed, which it feems he could not find in 1 733. 
 
 See
 
 B U L 
 
 [ 1 
 
 i S«e much curious information concerning this plant in 
 ~' Proftflbr Beekmann'a H'ljhry of Iiivenlicris and Ui/to- 
 •ueries. 
 
 BULAM, or BuLAMA, as it is more ufually called, 
 forms part of the Archipelago, or cluiler of idands, ly- 
 ing on the wellcrn or windward coalt of Africa, and 
 known by tke name of the B'ljfaos or B'ljfagos, which 
 are fuppofed to have been celebrated by the ancients 
 under the appellation of tiie HeJ'pcr'ules, It is fituatcd 
 at the mouth of the Rio Grande, in i lo N. Lat. and 
 15° W. Long, from the meridian of London; and is 
 between feventeen and eighteen leagues long, and from 
 four to five broad. 
 
 This illand has become an interefting objeA to the 
 inhabitants of Great Britain, in confequence of its ha- 
 ving been purchafed in the year 1792 by a foeiety infti- 
 tuted for the fame humane purpofes with thofe which 
 gave rife to the Sierra-Leona company (fee Siekrj- 
 ifona, Encycl ) The Bulam affociation was formed 
 towards the latter end of the year 1791 ; and they were 
 induced to pitch upon that ifland as the mofl eligible 
 traft for their intended colony, in confequence of the 
 flattering defcription given of its climate, foil, and har- 
 bours, by M. Brue, formerly direttor-general of the 
 Fi'ench African companies. 
 
 The gentlemen originally appointed as truftees for 
 managing the concerns of the affociation at home were, 
 J'auJ Le Mifurier, M. P. ; Jatnes Kh-l^alr'ick, Efq; 
 George Hartivell, Efq; Mofes Ximenes, Efq; Sir "John 
 Riggs Miller, Bart, and David Scott, Efq. M. P. ; and 
 for eftablifhing the colony, and conducing the affairs 
 of the foeiety abroad, the following gentlemen were no- 
 minated, viz. Meffrs H. H. Dalrywple, John Touiig, Sir 
 IVilliam Hallon, Bart. John King, Phiiip Beaver, Peter 
 Clulterbuck, Nicholas Bayly, Francis Brodie, Charles 
 Drohe, John Paiba, Richard Hancorne, Robert Dobbins, 
 and Ijaac Ximenes. 
 
 A fum of L. 9000 being quickly fubfcribed for the 
 eftablifhment of the intended colony, this committee 
 failed from Spithead in three fliips on the 1 ith of April 
 1792 ; and landing in due time at Bnlama, they pur- 
 chafed that ifland from the kings of Canabac, who 
 claimed it as their property. They purchafed likewife 
 from the kings of Ghinala the neighbouring ifland Ar- 
 eas, and the adjacent land on the continen/ ; and thefe 
 feveral purchafes being taken pofTciTion of in the ufual 
 form, a body of ftttlers, confifting of 49 men, 13 wo- 
 men, and 25 children, were left at Bulama under the 
 fuperintendence of Mr Beaver, with a temporary fup- 
 ply of provifions, ilores, plantation-tools, and merchan- 
 dife, for trading with the neighbouring natives. It is 
 from the difpatches of thefe fettlers, after having lived 
 fome time in Bulama, that the following account of 
 the ifland was drawn up by Mr Johanfen. 
 
 " The climate, on the whole, may be deemed falu- 
 bnous, and will become more fo in proportion to the 
 increafe of cultivation. The mornings and evenings are 
 temperate and pleafant ; the middle of the day is hot, 
 but the fine fea breeze which then fets in tends greatly 
 to cool and refrefh the air. The heat of the fun is not 
 either fo exceffive or intolerable as has been generally 
 fuppofed : indeed nature has moft admirably adapted 
 our mechanical and phyfical qualities to the exigencies 
 of different regions ; and man, who is the inhabitant of 
 €ver)' climate, may, in fome meafure, render himfelf in- 
 
 i3_ ] B U L 
 
 digeuous to every foil. Here the only danger arifcs Birlim. 
 from too fudden an expofure lo the operation of the """V"" 
 vertical rays of the inn, or an excels of labour ; both of 
 which the iiril fettlers ought mod Ihidioufly to avoid. 
 
 " It appears from Mr Beaver's obfcrvalions at noon, 
 between the 2-th of July 1792, and the 38th of April 
 1793, *''^' ''"^ thermometer, when loweft, was at 74 ; 
 the medium heat 83 ; and that it never exceeded 96, 
 except at one time wlien it role to loo, during a calm 
 that occurred in the interval between the north eafl 
 breeze in the morning and the fuuthwtll in the even- 
 ing of the 19th of February 1793. '^'"^ difference be- 
 tween the heat of noon and that of the morning and 
 evening is from 20 to 30 degrees. On the 23d of Oc- 
 tober 1792, hail of the iize of a pin's head fell during 
 two minutes, although not a cloud was to be feen du- 
 ring this phenomenon. The mercury in the thermo- 
 meter then flood at 85 ; the wind was at north-eall in 
 the morning and louth-wcfl in the evening. 
 
 " Immediately after fun-fet a <*ew conilantly begins 
 to fall, which induces fome to light a fire in their 
 houfes ; they at the fame time put on warm.er cloth- 
 ing. There is little or no twilight; and in'ght and day 
 are nearly equal : the earth has therefore time to cool 
 during twelve hours abfence of the fun. 
 
 " None of thofe terrible and dettrudtive hurricanes fo 
 frequently experienced in the Well Indies are to be 
 met with here. The tornadoes, which arife chiefly from 
 the ealtcrn point of the compaf^, are but of fliort dura- 
 tion, feldom lafting above an hour, and may be readily 
 forefeen fome time previoufly to their commencement. 
 They occur at the beginning and clofe of the wet fea- 
 fon, and are highly beneficial, as they purify the air, 
 and difpel the noxious vapours with which it would 
 otherwife abound. 
 
 " The rains fet in about the latter end of May or 
 the beginning of June, and difcontinue in Oftober or 
 November. Tiiey do not fall every day, for there is 
 often a confiderable interval of clear weather, during 
 which the atmofphere is beautifully fcrenC ; the Ihowers 
 in the fir1t and lafl month occur but feldom, and are 
 far from being violent ; while, on the other hand, they 
 fometimes relcmble torrents, more efpecially towards the 
 middle of the ieafon. During tlie whole of this period, 
 Europeans fliould, if pofuble, confine thcmfelves to 
 their habitations, as the rains prove injurious to health, 
 more efpecially if thofe expol'ed to them negleft to wipe 
 their bodies dry, and to change their clothes immedi- 
 ately on their return home. It is deemed prudent alfo 
 not to dig the earth until the expiration of a month af- 
 ter the return of fair weather, as this is confidered to 
 be unhealthy. 
 
 " During the continuance of the dry feafon, a dew 
 falls during the night, in iufHcient quantity to anfwer 
 all the purpofes of vegetation. 
 
 " Every ftranger is generally here, as well as in the 
 Well Indies, fubjeft to a fever or feafoning on his ar» 
 rival. This is not infeftious ; it proceeds perhaps from 
 an increafed perfpiration and a fudden extenfion of the 
 pores of the human body, in confequence of the heat, 
 by which means it is rendered more liable to imbibe 
 the abundant exhalations that arife from the animal, ve- 
 getable, and mineral kingdoms; but even this, flight as 
 it is, might doubtlefs be avoided by means of a proper 
 regimen, and a fliort feclufion from the full aition of 
 
 the
 
 B U L 
 
 EuUn-, the open air, more cfpcci.illy at nonn, and during the 
 
 » evening, until tlic climate has been rendered familiar. 
 
 " Dulama is admirably adapted for all the purpofes 
 
 of an exteniive commerce, being not only happily iitu- 
 
 ated at the mouth of the Rio Grande, bnt in the viti- 
 
 [ 134 ] 
 
 B U L 
 
 i^nnis, and materials for dyeing ; all of which it Is but Iluhm, 
 fair to fupjiofe, might be readily cultivated in a kindred ""'V"""' 
 climate and a congenial foil. 
 
 " The neighbouring feas abound with a variety of 
 fiili, highly agreeable to the palate. The lion, tyger. 
 
 iiity of feveral other navigable rivers ; fo that a trade jackall, S;c. are natives of the continent ; but in Bula- 
 
 with the internal parts of Africa is thereby greatly fa- 
 cilitated. The landing is remarkably eafy aiid fafe, there 
 being no furge ; the ebb and flow is regular, and there 
 is an increafe of 16 feet of water at fpving tide. The 
 "Jiay oppofite the Great Bulama is adorned with a num- 
 ber of iflands, covered w ith trees, and forms a moft ex- 
 cellent harbour, fufliciently capacious to contain tlie 
 whole navy of Great Britain, which might ride there 
 in fafety. The fettlement in general is well fupplied 
 with water. A number of fprings have been lately dif- 
 covered in different ])laces ; and befides a draw-well in 
 the fort, which was erefted for the defence of the 
 coh>ny, there is a fmall flream, which runs into E- 
 Jewfis Bay, near the new fettlement called Hefper 
 
 ma no animals have been difcovered, the wolf, fome buf- 
 faloes, a tew elephants, and a fpecies of the deer, ex- 
 cepted. 
 
 " The woods abound with doves, guinea-fowls, and 
 a variety of birds, celebrated for the beauty of their 
 plumage. 
 
 " The natives of this part of Africa, like all favages, 
 are entirely under tire dominion.of their paffions : hence 
 the violence of their attachment to their friends, and 
 the excefs of their refentment againil their enemies. 
 Their notions of property are very obfcure and confu- 
 fed : they have no idea of any right arifmg from occu- 
 pancy or improvement. What they want, they either 
 receive or take wherever they may happen to meet with 
 
 Elewfis : this is admirably fituated for the fiipply of it, and they permit others to do the fame. They have 
 (liipping. been taught by experience that the Europeans will not 
 " The ifland is beautifully furrounded, and interfper- agree to this : againft them therefore they employ- 
 fed with woods ; lofty fruit and foreft trees, moftly free every artifice that it is in the power of cunning to fug- 
 from underwood and brambles, form a verdant belt, in geft. 
 
 fome places two or three miles broad, which entirely 
 encircles it, in fuch a manner as to reprefent a planta- 
 tion artificiaUy formed around a park. Within this 
 the fields are regularly divided by trees, fo as to refem- 
 ble the hedge-rows in England. The beach has in foine 
 places the appearance of gravel walks ; it is fringed 
 with mangrove trees, which forming a line with the 
 high-water mark, dip their branches into the fea, and 
 thus afford nourifhment to the oyflers that often adhere 
 to their extremities. 
 
 " The colonifts need not fear any attack on the part 
 of the negroes, provided their own conduft be juft and 
 peaceable : for Mr Beaver, who was indeed admirably 
 calculated by nature and habit for the flation he occu- 
 pied, could enfure both fafety and refpeft when the fet- 
 tlers under him were reduced to four white men, al- 
 though the neighbouring nations knew that he was In 
 pofTeffion of commodities, for the acquliition of which 
 many of them had become day-labourers. He often 
 kept from twenty to forty gromlttos, or black cultlva- 
 
 " Several parts of Bulama have been occafionally cul- tors In pay, at that very period, at about four or five 
 
 tlvated by the neighbotiring blacks, though they did ba^rs (a) each per month. Thefe are eafy to be procu- 
 
 not conftantly refide on it. red, to almoft any number that can poffibly be wanted. 
 
 " The land in general rifes gradually towards the " Until a fufficient quantity of flock and provifions 
 
 middle of the ifland, where the hlgheft fpot is from 60 can be raifed in the company's fettlements, the adjacent 
 
 ,to 100 feet above the level of the fea. The fmall hill Iflands will funilfli abundance of cattle, hogs, fowls, &c. 
 
 on which the fort is fituated is nearly of the fame alti- at a very cheap rate. A horfe may be purchafed at 
 
 tude. Goree for il. ics. a bullock may be had from 12s. to 
 
 " The foil is abundantly rich and deep ; ftones do 18 s. ilerllng : provifions of all kinds are equally reafon. 
 
 not here impede the labours of the farmer; and indeed able. Honey is alfo to be procured in great plenty, 
 
 none have hitherto been difcovered, but a fmall fort, and bees-wax may be rendered an advantageous objeft 
 
 refembllng pieces of ore, which are to be met with on of commercial fpeculatlon. 
 
 the fliore. There are many fa-vunnahs or natural mea- " In fhort, the acquifition of Bulama, Areas, and 
 
 dows, fo extenfive that the eye can fcarcely defcry their the adjacent territories, prefents the faireft opportunity 
 
 boundaries. Thefe are admirably adapted for the rear- of furnifliing Europe with many valuable articles that 
 
 ing of flock and feeding of cattle of every kind. have hitherto been brought from more remote coun- 
 
 " Cotton, indigo, rice, and coffee, grow fpontane- tries, with much greater hazard, and at an increafed 
 
 oufly on this coafl ; the fugar-cane is Indigenous to expence. The Intercourfe with England Is eafy, fafe, 
 
 many parts of Africa, and might be cultivated here by and expeditious ; for the voyage may be performed in 
 
 the labour of freemen, in equal perfeftion, and to much the fpace of three or four weeks : and by the terms of 
 
 greater advantage, than In the exhaufled iflands of the the hrd fubfcrlptlon, a fettler on Bulama might pur- 
 
 Weft Indies. All kinds of tropical produftlons, fuch 
 as pine-apples, limes, oranges, grapes, plums, caffada, 
 guava, Indian wheat, the papaw, water-melon, mufk- 
 nielon, the pumpkin, tamarind, banana, and numbers of 
 other delicious fruits, alfo flourlfli here. The adjoin- 
 ing territories produce many valuable forts of fpices, 
 
 chafe 5C0 acres of land for L. 30 Sterling ; by the terms 
 of the fecond, which we fuppofe are the terms at pre- 
 fent, he might purchafe on the Iflands of Bulama and 
 Areas, or on that part of the adjacent coaft which was 
 ceded to the fociety by the kings of Ghinala, ioo acre* 
 for L. 50 ilerllng. 
 
 " The 
 
 (a) a bar is about the value of three fhillings and fixpence.
 
 BUN [ I 
 
 « The colonization of Africa opens a noble and ex- 
 ^ tenfive field to nations and to individuals. To people 
 tbofe fertile territories, defpoiled of their inhabitants by 
 the (lave-trade ; to rear the produdions of the climes 
 between the tropics, by the afiiftance of free men ; to 
 give ample fcope to the induftry and exertions of thofe 
 who may be inclined to remove from Great Britain ; 
 and to extend the commerce and the manufaftures of 
 our native country — thefe are fubjefts which have ex- 
 cited the attention of the Bulama affociation, and now 
 claim the affillance of the ingenious, the fupport of the 
 rich, and the concurrence and good wirties of all." 
 
 BUNTING, is a bird which has been defcribcd un- 
 der its generic name Emberiza {Encycl.) ; but there 
 is one fpecies, the orange Jljouldered bunting of Latham, 
 of which M. Vaillant relates fome particulars certainly 
 not unworthy of notice in this place, 
 
 " The female of this beautiful bird (fays he) has the 
 fimple colours of the flcy-lark, and a fliort horizontal 
 tail, likt that of almoft all other birds : the male, on 
 the contrary, is wholly black except at the flioulder of 
 the wing, where there is a large red patch ; and his tail 
 is long, ample, and vertical, like that of the common 
 cock. But this brilliant plumage and fine vertical tail 
 fublift only during the feafon of love, which continues 
 fix months. This period over, he lays aiide his fplendid 
 habiliments, and aflumes the more modeft drefs of his 
 mate. The moft extraordinary circumftance is, that the 
 vertical tail alfo changes to a horizontal one, and the 
 male fo exadlly refembles the female, that it is not pof- 
 fible to diftinguifh them from each other. 
 
 " The female has her turn. When flie reaches a cer- 
 tain age, and has loft the faculty of propagating the 
 fpecies, (he clothes herfelf for the remainder of her days 
 in the garb which the male had temporarily afTumed ; 
 her tail, hke his at that period, grows long, and, like 
 his alfo, from horizontal becomes vertical. 
 
 " The birds of this fpecies affociate together, live in 
 a fort of republic, and build their nefts near to each 
 other. The fociety ufually confifts of about fourfcore 
 females ; but, whether by a particular law of nature, 
 more females are produced than males, or for any other 
 reafon of which I am ignorant, there are never more 
 than twelve or fifteen males to this number of females, 
 who have them in common." 
 
 According to our author, this tranfmutation is by 
 no means confined to this parti'cular fpecies of bunting. 
 Many females of the feathered creation, when they 
 grow fo old as to ceafe laying eggs, affume the more 
 fplendid colours of the male, which they retain during 
 the remainder of their lives. This faft is ilrikingly per- 
 dcptible in thofe fpecies in which the male and female 
 very much differ in colour, as the golden pheafant of 
 China, for inftance. In fome fpecies, and thofe not a 
 few, the male alone regularly changes his colour, and 
 affumes once in a year the plumage of the female ; fo 
 that at a certain period all the birds of that fpecies ap- 
 pear females. " I have in my poflelTion (fays our au- 
 thor) fpecimens of more than fifty of thofe changing 
 fpecies, in all their tranfitions from one hue to another ; 
 and the change is fometimes fo great, that a perfon 
 ■would fuppofe himfelf to fee individuals totally diffe- 
 rent. A clofet-naturalift, for inftance, fhewed me four 
 birds as fo many different fpecies, and even as not be- 
 longing to the fame genus, with, which I was well ac- 
 
 35 .] BUR 
 
 qiiainted, and which I knew to be the fame bird, only Burke 
 of different ages." ' /— 
 
 Such changes as thefe, could they be proved to take 
 place occafionally among domcftic fowls, would in fome 
 meafure account for ftrange ftories of cocks laying eggs, 
 which we have heard related by perfons whole general 
 veracity was never qucftioned. 
 
 BURKE (Edmund), was born in the city of Dub- 
 lin on the ift of January 17.^0. His father was an at- 
 torney of confiderable knowledge in his profcflion, and 
 of extenfivc pradlice ; and the family from which he 
 fprung was ancient and honourable. He received the 
 rudiments of his claffical education under Abraham 
 Shackleton, a Quaker, who kept :i private fchool or 
 academy, as it has been called, at Bellytore, near Car- 
 low, and is faid to have been a very fliilful and fuccefs- 
 ful teacher. 
 
 Under the tuition of this mafter, Burke devoted him- 
 fclf with great ardour, induftry, and perfeverance, to 
 his ftudies ; and manifefted, even from his boyilli days, 
 a diftmguilhed fuperiority over his contemporaries. He 
 was the pride of his preceptor, who prognofticated eve- 
 ry thing great from his genius, and who was, in return, 
 treated by his illuftrious pupil, for forty years, with re- 
 fpeft and gratitude. 
 
 From fchool Burke was fent to Trinity-college, Dub- 
 lin, where it was afl"erted by Goldfmith and others his 
 contemporaries, that he difplayed no particular eminence 
 in the performance of his exercifes. Like Swift, he 
 defpifed the logic of the fchools ; and like him too, he 
 devoted his time and his talents to more ufeful purfuits. 
 Johnfon, though proud of being an Oxonian, did not 
 much employ himfelf in academical exercifes ; and Dry- 
 den and Milton, who ftudied at Cambridge, were nei- 
 ther of them ambitious of college diliinftions. Let 
 not, however, the example of a Burke, a Johnfon, a 
 Dryden, or a Milton, feduce into by-paths the ordina- 
 ry ftudent ; for though great genius either finds or 
 makes its own way, common minds iiiuft be content to 
 purfue the beaten track. Shakcfpeare, with very little 
 learning, was the greateft dramatic poet that ever wrote ; 
 but how abfurd would it be to infer from this fatl,'that 
 every illiterate man may excel in dramatic poetry ? 
 
 _ Whilil at college Burke applied himfelf with fuffi- 
 sient diligence to thofe branches of mathematical and 
 phyfical fcience which are moft fubfervient to the purpo- 
 fes of life; and though he neglefted the fyllogiltic lo- 
 gic of Ariftotle, he cultivated the method of induftion 
 pointed out by Bacon. Pneuniatology, likcvvife, and 
 ethics, occupied a confiderable portion of his attention ; 
 and whilft attending to the acciuifition of knowledge, 
 he did not negleft the means of communicatina- it. He 
 ftudied rhetoric and the art of compoiition, as well ai 
 logic, phyfics, hiftory, and moral philofophy ; and had 
 at an early period of his life, fays Dr Bidet, planned a 
 confutation of the metapliyfical theories of Berkeley 
 and Hume. 
 
 For fuch a taflc as this, we do not think that nature 
 intended him. Through the evcr-attive mind of Burki.' 
 ideas feem to have flowed with too great rapiditv to 
 permit him to give that patient attention to minute di- 
 itinftions, without which it is vain to attempt a confu- 
 tation of the fubtleties of Berkeley and Hume. The 
 ableft antagonift of thefe two pliilofophers was remark- 
 able for patient thinking, and even ap^ar^irt fiownefs of 
 
 apprebjnfiou 3
 
 1^6 
 
 BUR [ 
 
 TnirVc. apprehenfion ; and we have not a doubt, but that if he 
 - » had pofftfil'd the rapidity of thought which chara6te- 
 rifed Burke, hi> confutation of Hume and Berkeley 
 wo -Id have bet-n far from conclufive. It might have 
 bctn equal to the Ef.y on the Nature and Immutability 
 of Trir.h, but wonld not have been what we find it m 
 "The It quiry into the Human Mind en the Principles of 
 Common S^nfe, and in The EJfays on the Intel/eSual and 
 ^ili-ue Porufrs of Man. 
 
 A taflc much better fuited to Burke's talents than 
 the writing of metaphyfical difquifitions on the fubllra- 
 tum of body, prefented itfelf to him in the year 1749, 
 and 3 tan< \vhicb was likcwife more immediately uleful. 
 At that period one Lucas, a democratic apothecary, 
 wrote a number of very daring papers againll govern- 
 ment, and acquired by them as great popularity at Dub- 
 lin as Mr Wilkes afterwards obtained by his North 
 Briton in London. Burke, though a boy, perceived, 
 almoil intuitively, the pernicious tendency of fuch le- 
 veri:ig doftrines, and refolved to counteraft it. He 
 wruu- feveral effays in the ftyle of Lucas, imitating it 
 fo ey.idfly as to deceive the public ; purfuing his prin- 
 cip'tf to confequences necefTarily refulting from them, 
 and Ihcwing at the fame time their abfurdity and their 
 dai-^er. Thus was his firft literary effort, like his laft, 
 calculated to guard his country againft anarchical inno- 
 vations. 
 
 Whilft employed in treafuring up knowledge, which 
 at a future period was to command the admu-ation of 
 liftening fenates, he did not negledl the means iiecelfary 
 to render himfelf agreeable in the varied intercourfe of 
 private life. To the learning of a fcholar he added the 
 manners of a gentleman. His company was fought 
 among the gay and the fafhionable, for his pleafing con- 
 verfation and eafy deportment ; as much as among the 
 learned, for the force and brilliancy of his genius, and 
 the extent and depth of his knowledge. But though 
 ' the objeft of very general regard in his native country, 
 lie had hardly any profpeA of obtaining in it an inde- 
 pendent fettlement. He therefore applied, fome time 
 aftei' the publication of his letters expofing the do&rlnes 
 of Lucas, for the profeflbrlhip of logic, which had then 
 become vacant in the univerfity of Glafgow : but whe- 
 ther th^t application vias made too late, or that the uni- 
 verfity was unwilhng to receive a (Iranger, certain it is 
 that the vacant chair was filled by another, and that 
 Burke was difappointed of an office in which he was 
 eminently qualified to excel. For many years very little 
 attention has been paid in tlie univerfities of Scotland, 
 perhaps even too little, to the Ariftotellan logic ; and 
 the profeffors, inftead of employing their time in the 
 analyfing of fyllogifms, deliver leftures on rhetoric and 
 the principles of compofition — leisures which no man 
 was more capable of giving than the unfuccefsful can- 
 didate for the profelforlliip in Glafgow. 
 
 Difappointment ot early views has frequently been 
 the means of future advancement. Had Johnfon be- 
 come matter of the Stafford (hire fchool, talents might 
 have been confumed in the tuition of boys which Pro- 
 vidence formed for the inftrndlion of men ; and had 
 Burke obtained the profeflToi fhip of logic in Glafgow, 
 he would have been the moft eloquent lefturer in that 
 univerfity, inftead of the moft brilliant fpeaker in the 
 Britilh fenate : but whether his talents might not have 
 been as ufefully employed in the univerfity as in the it. 
 
 ] BUR 
 
 nate, may perhaps be a queftion, though there can be no Burke, 
 queftion whether they would have invefted himfelf with ~~~v~~ 
 an equal blaze of fplendour. 
 
 Difappointed in Glafgow, he went to London, where 
 he immediately entered himfelf of the Temple ; and as 
 there is reaiou to believe that he was in ftraitened cir- 
 cumftances, he fubmitted to the drudgery of regularly 
 writing for daily, weekly, and monthly publications, 
 elfays on general literature and particalar politics. The 
 profits ariling from fuch writings were at firft fmall ; 
 but they were fo necelfary to their author, that the in- 
 tenfe application which they required gradually impair, 
 ed his health, till at laft a dangerous illnefs enfued, 
 when he reforted for medical advice to Dr Nugent, a 
 phyfician whofe (Icill in his profeffion was equalled only 
 by the benevolence of his heart. The Doftor, confider- 
 ing that the noife, and various difturbances incidental to 
 chambers, muft retard the recovery of his patient, fur- 
 nlflied him with apartments in his own houfe, where 
 the attention of every member of the family contribu- 
 ted more than medicines to the reftoration of his health. 
 It was during this period that the amiable manners of 
 Mifs Nugent, the Doftor's daughter, made a deep im. 
 prefTion on the heart of Burke ; and as fhe could not 
 be infenfible to fuch merit as his, they felt for each 
 other a mutual attachment, and were married foon aftef 
 his recovery. 
 
 Hitherto his mental powers and acquirements were 
 known in their full extent only to his friends and more 
 intimate companions ; but they were now made public 
 in his firft acknowledged work, intitled, A Vindication 
 of Natural Society. The objeft of this performance was 
 to expofe the dangerous tendency of Lord Bolingbroke's 
 philofophy. By the admirers of that nobleman, his 
 principles were deemed inimical only to revealed reli- 
 gion and national churches, which they would have 
 been glad to fee overturned, provided our civil eftablifh- 
 ment had been preferved; and to the civil eftabliftment 
 they perceived no danger in the writings of the author 
 of The Patriot King. Mr Burke thought very diffe- 
 rently ; and endeavoured to convince them, that if his 
 Liordihip's philofophy fiiould become general, it would 
 ultimately dettroy their rank, their confequence, and 
 their property, and involve the church and ftate in one 
 common ruin. In his ironical attack upon artificial 
 fociety, he makes ufe of the fame common place mode 
 of unfair reafoning which his noble antagonift had em- 
 ployed againft religion and religious eftablifliments. He 
 argues, from the incidental abufes of political fociety, 
 that political fociety muft itfelf be evil ; he goes over 
 every form of civil polity, pointing out its defefls in 
 the moft forcible language; and, in perfeft imitation of 
 the fceptical philofophy, he pulls them all down, one 
 after another, without propofing any thing in their 
 ftead. So complete is the irony, that to many not ac- 
 quainted with fuch difquifitions, he would appear to be 
 ferioufly inveighing againft civil government ; and we 
 have aiifually heard fome of the advocates for modern 
 innovation mention this work as a proof how different 
 Mr Burke's opinions In politics once were from what 
 they appear to have been when he wrote his Refe3ions 
 on the French Re-volution. 
 
 The truth, however, is, that there is no inconfiftency 
 between The Vindication of Natural Society and the la- 
 teft ptiblications of its illuftrious author. At the pe- 
 riod
 
 BUR r I 
 
 rioJ when that work, was publiHied, infidelity had in- 
 ' fefted only tlie higher orders of men, and fuch of the 
 lower as had got the rudiments of a liberal edncatioii. 
 Of thefe we believe a finglc individual was not then to 
 be found, who fuppofed that fociety could fubhll both 
 without government and without religion ; and there- 
 fore while they laboured to overturn the church, and 
 to prove that Chrillianity itfelf is an Impollure, they 
 all pretended to be zealoufly attached to our civil go- 
 vernment as eftabliflied in king, lords, and commons. 
 Except the clergy of the eftabliflied church, there was 
 no order of men whom they indifcriminately reviled. 
 Hence it was that not Burke only, but Warburton, 
 and almoft every other opponent of Lord Bolingbroke, 
 b«gan their defences of revelation, by (hewing the in- 
 dlflbluble connexion between our civil and ecclefiaftical 
 eftabllfhments ; and all the difference was, that he did, 
 through the medium of the moft refined irony, the very 
 fame thing which they had done by ferious reafoning. 
 
 Soon after his Vindication of Natural Society, Burke 
 publllhed jl Philofophical Enquiry into the Origin of our 
 Ideas of the Sublime and Beautiful ; a work which foon 
 made its author univerfally known and admired, and 
 which has been ftudied by every Englifli reader ot tafte. 
 It is therefore needlefs for us to hazard any opinion 
 either of Its general merit or Its particular defefts. In 
 one of the literary journals of that day, Mr Murphy 
 urged objeftlons agalnft fome of its fundamental prin- 
 ciples, which, in our opinion. It would be very difficult 
 to anfwer ; whilft Johnfon, who was certainly a fevere 
 judge, confidered it as a model of philofophical criti- 
 clfm. " We have (faid he) an example of true crltl- 
 cifm in Burke's Efiay on the Sublime and Beautiful. 
 There is no great merit in (hewing how many plays 
 have giiofts in them, or how this gholt Is better than 
 that ; you mult (hew how terror is Imprefl'ed on the 
 mind." 
 
 In confequence of this manifeflation of Burke's In- 
 telleftual powers, his acquaintance was courted by men 
 of diftinguifhed talents, and, among others, by Johnfon 
 and Sir Jofliua Reynolds. The literary club which has 
 been mentioned [Encycl.) in the life of Johnson, was 
 inftituted for their entertainment and inflruftion, and 
 confifted at firff: of Johnfon, Burke, Reynolds, Gold- 
 fmith, Dr Nugent, Mr Topham, Beauclerk, Sir John 
 Hawkins, Mr Chamler, and Mr Bennet Langton, who 
 were all men of letters and general information, though 
 far above the reft ftood Burke and Johnfon. Of Burke 
 indeed Johnfon declared, upon all occafions, that he was 
 the greateft man living; whilft Burke, on a very folemn 
 occafion, faid of Johnfon, " He has made a chafra, 
 which not only nothing can fill fip, but winch nothing 
 has a tendency to fill up. Johnfon is dead. Let us 
 go to the next beft — There is nobody — No man can be 
 iaid to put you in mind of Johnfon." Nor was the 
 opinion which thefe two illultrious men held of each 
 other's powers peculiar to themfelves alone : all the 
 members of the club obferved, that in colloquial talents 
 they were nearly matched, and that Johnion never dlf- 
 courfed with fuch animation and energy as when his 
 powers were called forth by thofe of Burke. 
 
 Some years before the inftitution of this club, Burke, 
 who had devoted much of his time to the iludy of hl- 
 ftory and politics, propofed to Mr Dodfley, an eminent 
 bookfeller, a plan of an Annual RfiGiSTER.of the ci- 
 
 SuppL. Vol. I. Part I. 
 
 37 1 
 
 B IT R 
 
 vil, political, and literary tranfiCtious of the times ; and 
 the propolal being acceded to, the work was begun and ■■ 
 carried on for many years, cither by Burke himftlf, or 
 under his immediate infpeftioji. It bears indtcd inter- 
 nal marks of his genius, his learning, and his candour, 
 being by much the moft elegant and impartial periodi- 
 cal hiftory which has perhaps appeared in any age or 
 nation. Even when the heat of oppolition made him, 
 in his fpeeches, fometimes mifrcprelent the conduft ot 
 admlniftration, the Annual Regifter, under his manage- 
 ment, continued to render juftice to all parties. 
 
 He ftill continued to write occafionally political eC 
 fays for other publications than the Annual Regifter ; 
 and fome of thefe eflays in the Public ,-l dvertifer having 
 attrafted the notice of the Marquis of Rockingham, 
 that nobleman fought the acquaintance of their author. 
 It was In the year 1765 that the firft interview took 
 place between them ; and the Marquis, who was then 
 at the head of the treafury, off"erIng to make Burke his 
 own fecretary, the offer was readily accepted. On this 
 occafion he gave a remarkable pcoof of difintereftednefs 
 and delicate Integrity. Through the influence of Mr 
 Hamilton, known by the appellation of Single Speech 
 Hamilton, and long fufpe6ted to be the author of Ju- 
 nius's Letters, he had fome time before obtained a pen- 
 fion of L.300 a-year on the Irifti eftablKhment ; but 
 this penfion he now thought it incumbent upon him to 
 refign, becaufe he had connefted himfelf with a party 
 oppofite In many things to the party whofe meafures 
 were fupported by his friend. 
 
 During the Rockingham admlniftration he was cho- 
 fen member of Parliament for tlie borough of Wendover 
 in the county of Bucks ; and he prepared himfelf for 
 becoming a public fpeaker, by ftudying, ftUl more clofe- 
 ly than he had yet done, hiftory, poetry, and philofo- 
 phy ; and by ftoring his mind with fafts, Images, rea- 
 fonlngs, and fentlments. He paid great attention like- 
 wite to parliamentary ufage ; and was at much pains to 
 become acquainted with old records, patents, and pre- 
 cedents, fo as to render himfelf complete mailer of the 
 bufinefs of office. That he might communicate with- 
 out embarraflrnent the knowledge which he had thus 
 laborioudy acquired, he frequented, with many other 
 men of eminence, the Robin Hood Society, where he 
 praftifed the replies and contentions of eloquence ; and 
 to acquire a graceful adflon, with the proper manao-e- 
 ment of his voice, he was a very diligent obfcrver of 
 Ganick in Drury-Lane theatre. He procured his feat 
 In 1765, and in the enfuing fefliou delivered his maiden 
 fpeech ; which was fuch a difplay of eloquence as ex- 
 cited the admiration of the Houfe, and drew very high 
 praife from Its moft diftingulflied member Mr Pitt, af- 
 terwards Earl of Chatham. 
 
 The principal objefts which engaged the attention 
 of the Rockingham admlniftration were f,he ferments 
 In America, which was then in a ftate little (liort of re- 
 bellion, on account of the famous ftamp-adl. Parlia- 
 ment was divided In oplin'on refpefting that mcafure. 
 Whilft Mr Grenville and his party (under whofe au- 
 fpices the ftamp-aft had paiTed into a law) were for 
 enforcing obedience to it by coercive meafures, Mr Pitt 
 and his followers denied that the piulianunt of Great 
 Britain had a right to tax the Americans; and the mar- 
 quis of Rockingham, who was hardly able to carry any 
 meafure in oppolition to both thefe parties, had to cou- 
 S fidtr, 
 
 Buike
 
 BUR [ I 
 
 Barhe. fijer, on this occafion, vvhofe fentiments h; would a- 
 ""^V"^ dopt. By the advice, it is faid, of Mr Burke, he chofe 
 a middle courfe between the two oppofite extremes. 
 To gratify the Americans, he repealed the llamp-ad ; 
 and to vindicate the honour of Britain, he got a law 
 paffed declaratoiy of her ri^ht to legiflate for America 
 in taxation as in every other cafe. 
 
 This mcafure, whoever was its au'.hor, was certainly 
 not the offspring either of wifJcni or vigour. If the 
 mother-country had a right to Icglflite in all cafes for 
 America, obedience to the (lamp-ail; Ihonld cirlainly 
 have been enforced; and the miniltry which relinquilh- 
 ed an acknowledged right, to gratify tlie faelious dif- 
 pofition of dillant colonies, was obvioully unfit to guide 
 the helm of a great empire. Lord Rockingham and 
 his friends were accordingly difmilTed from office ; and 
 a new adminiftration was formed under the aufpices of 
 Mr Pitt, now created earl of Chatham. 
 
 Burke, in the mean time, wrote in defence of the 
 party with which he was conncAtd; and affum.ed great 
 credit to it for compofing the dillradtions of the Bri- 
 tifh empire by the repeal of the American ftamp-aft, 
 ■whilll the conftitutional fiiperiority of Great Britain 
 was preferved by the a& for fecuring the dependence 
 of the colonies. After defending his friends, he pro- 
 ceeds to attack thofe who had fucceeded them in office. 
 Of Lord Chatham he fays — " He has once more deign- 
 ed to take the reins of government into his own hand, 
 and will, no doubt,, drive with his wonted fpeed, and 
 raife a deal of dull around him. His horfes are all 
 matched to his mind ; but as fome of them are young 
 and ikittifh, it Is faid he has adopted the new contri- 
 vance lately exhibited by Sir Francis Delaval on Weft- 
 •mlnfler bridge : whenever they' begin to fnort and tofs 
 up their heads, he touches the fpring, throws them 
 loofe, and away they go, leaving his lordfliip fafe and 
 fnug, and as much at his eafe as if he fat on a wool- 
 pack." 
 
 The letter, of which this is an extraft, was printed 
 in the Public Advertifer ; and is faid to have contribu- 
 ted, in no fmall degree, to lelfen the popularity of the 
 illuftrious (latefman againll whom it was written. The 
 miniftry, indeed, which he had formed, confided of 
 very heterogeneous materials, and was not heartily ap- 
 proved of by the nation. It therefore foon fell In 
 pieces by its own difcord, and Lord Chatham retired 
 in difgufl. 
 
 The parliament being dilTolved in 1768, Burke was 
 re-eledled for Wendover, and took his feat, when the 
 houfe met, in November. The duke of Grafton was 
 now prime minifter, and was oppofed by two powerful 
 parlies in parliament ; that of the marquis of Rocking- 
 ham, and. that of which Mr Grenville was confidered 
 as the leader. Thefe two parties, however, differed 
 widely betveen thcmfelves. Mr Grenville had pub- 
 liflied a pamphlet, intitkd, Tke Prejent State of the Na- 
 tion ; in which he very ably vindicated his own mea- 
 fiircs, and of courfe condemned the mcafures of thofe 
 who had fucceeded him ; and Burkt replied to him, 
 with greater eloquence, but perhaps with lefs of argu- 
 ment. In a traft, intitled, Obfervalions on the Prefent State 
 of the Nation, in which he makes a very high panegyric 
 on his own patron, and the connexions of the party, 
 and animadverts with cutting feverity on their fuccelTora 
 in ofBce. 
 
 38 ] BUR 
 
 About thii period commenced the national frenzy Burlte. 
 which was excited by the expulfion of Wilkes from the """v^ 
 houfe of commons, yir having printed and pMijhed a 
 feditioiis Hhel, and three objcene and impious libels. In the 
 controverfy to which this tranfaftion gave rife, Burke 
 and Johnfon took oppofite fides. Joiinfon, in his Falfe 
 Alarm, contends, with great ability, that the expulfion 
 of a member from the houfe of commons for the com- 
 miffion of a crime, amounts to a difqualilication of that 
 member from fitting in the parliament from which he 
 is expelled ; whilll Burke, though he difapproved of 
 the condudt of Wilkes as much as his friend, laboured 
 to prove, that nothing but an aft of the legiflature can 
 difqualify any pcrlon from fitting in parliament who is 
 regularly chofen, by a majority of eledlors, to till a va- 
 cant feat. It does not appear that this difference of 
 opinion produced the fmalleil abatement of mutual re- 
 gard between him and Johnfon. They both attended 
 the weekly club, and were as much pleafed with each 
 other as formerly. 
 
 The proceedings of the Grafton adminlflration, re- 
 fpedling Wilkes and other fubjetls, gave rife to the ce- 
 lebrated Letters of Junius. That thofe compolitions 
 were, in clearnefs, neatnefs, and precifion of flyle, in- 
 finitely fuperior to perhaps every other feries of iiewf- 
 paper inve£lives, has never been controverted; and that 
 they difplay a yafl extent of hiflorical and political in- 
 formation, is known to all who are not themfelves 
 ftrangers to the hiftory of this kingdom. Unclaimed 
 by any author, and fuperior to the produftions of moll 
 authors, they have been given to Burke, to his brother 
 Richard, a man likewife of very bright talents, to Mr 
 Hamilton, and to Lord George Germalne. We fhould 
 hardly hefitate to adopt the opinion of thofe who a- 
 fcribe them to Burke, had he not difavowed them to 
 his friend Johnfon. " I fhould have believed Burke 
 to be Junius (faid Johnfon), becaufe I know no man 
 but Burke who is capable of writing thefe letters ; but 
 Burke fpontaneoufly denied it to me. The cafe would 
 have been different had I ajhed him if he was the au- 
 thor. A man may think he has a right to deny when 
 fo queftioned as to an anonymous pubhcation." The 
 difference between the ftyle of thefe letters and that of 
 Burke's acknowledged writings, would have had no 
 weight with us; becaufe fuch was his command of Ian- , 
 guage, that he could affume, and occafionally did af- 
 fume, any ftyle which he chofe to imitate. He had 
 already fo clofely imitated the very different flyles of 
 Lucas and Bolingbioke as to deceive the public ; and 
 what was to hinder him from imitating the flyle of 
 Lord George Germalne, which certainly has a (Irong 
 rcfemblance to that of Junius ? We think, however, 
 with Johnfon, that liis fpontaneous difanioiual of thefe 
 letters ought to be held as fufficient proof that he was 
 not their author. 
 
 Burke had now gotten a very pleafant villa near Bea- 
 consfield in Bucklnghamfhire ; and being one of the 
 freeholders of the county, he drew up a petition to the 
 king, complaining of the conduft of the houfe of com- 
 mons refpefting the Middlefex eleftion, and praying 
 for a diffolution of the parliament. The petition, though 
 explicit and firm, was temperate and decorous, and as 
 unlike to one on the fame fubjedt from the livery of 
 London, as the principles of a moderate Whig are to 
 thofe of a turbulent democrate. 
 
 About
 
 BUR 
 
 [ 139 J 
 
 BUR 
 
 About this period he ftated very clearly his own 
 'political principles in a pamphlet intitled, "Thoughts 
 on the Caufes of the Prcfent Difcoiitents ;" and his 
 plan for removing thefe difcontents had not a grain ot 
 democracy in its compofition. He propofed to place 
 the government in the hands of an open ariftocracy of 
 talents, virtue, property, and rank, combined together 
 on avowed principles, and fupported by the approba- 
 tion and confidence of the people ; and the arittocracy 
 which he thought fitted for this great truft, was a 
 combination of thofe Whig families which had moft 
 powerfully fupported the revolution and confequent efta- 
 blifhmeiits. He exprefitd, in ilrong terms, his dilappro- 
 bation of any change in the conftltutlon and duration 
 of parliament j and declared himfelf as averfe from an 
 adminilbation which fhould have no other fupport than 
 popular favour, as from one brought forward merely 
 by the Influence of the court. 
 
 In this plan there is not that wifdom or liberality 
 which might have been expefted trom a man of Burke's 
 cultivated mind and exteniive reading. The Whigs, 
 when in power, had been as venal as the Tories ; and 
 the imprifonment of Lord Oxford, the banilhnient of 
 Atterbury bilhop of Rochefter, and the rtfolution of 
 the houfe of commons to fit for feven years, when it 
 had been chofen by its conftituents for no more than 
 three, were certainly greater violations of the conftitu- 
 tion than the difqualilication of Wilkes, or any other 
 meafure that had been carried by the court during the 
 adminiilrations of Grenville and the duke of Grafton. 
 Burke fliewed himfelf in this publication to be indeed 
 no republican ; but every fentcnce of it breathed the 
 fpirit of party. 
 
 Lord North was now prime minifter ; and in order 
 to tranquillize America, he propofed, in the beginning 
 of his adminilbation, to repeal the obnoxious laws of 
 his predccefTors in office, and to referve the duty on tea 
 merely to maintain the authority of parliament. The 
 conftquences of this conduct we have detailed ehtwhere 
 (lee Britain, Encych); and they are too well known 
 to all our readers. The part which Burke afted du- 
 ring his adminillration will not, in our opinion, admit 
 of any plauilble defence. It was not indeed the part 
 of a democrate, but of a man determined to oppofe 
 every meafure of thofe in power. In the beginning of 
 the conteft, he certainly difplaycd more wifdom and 
 patriotifm than the minifter ; for, without entering di- 
 rectly into the queftion. Whether the mother country 
 had or had not a right to tax the colonies ? he content- 
 ed himfelf with warning the houfe againll dangerous 
 innovations. "The Americans (faid he) have been 
 very ferviceable to Britain under the old fyltem : do 
 not, therefore, let us enter ralhly upon new meafures. 
 Our commercial interefts have been hitherto greatly 
 promoted by our friendly intercourfe with the colonies; 
 do not let us endanger polTeflion for contingency ; do 
 not let us fubftitute untried theories for a fyllem expe- 
 rimentally afcertained to be ufeful." 
 
 This was undoubtedly found reafoning, and everyway 
 becoming a lover of his country : but his continued op- 
 pofition to government, after all Europe had leagued 
 againft Great Britain, was a conduft which will admit 
 of no vindication, and for which the only poflible apo- 
 logy muft be found in that ardour of temper which 
 made his friend Hamilton fay, on- another occafion. 
 
 " Whatever opinion Burke, from any motive, fupport?, Burke 
 fo duftile is his imagination, that he foon conceives it *— ~Y~- 
 to be right." In his moft violent oppofitiou, however, 
 though his exprefilons were often extravagant and in- 
 decent, he never for a moment gave his fupport to the 
 metaphyfical dodrlne of t\\t: impnj'jriptibk rights of nhiii, 
 or to the aftual innovations which fome meant to in- 
 troduce on the bafis of that doftrine. His upright 
 mind was indeed fufficiently guarded againft thefe no- 
 velties by what he had obfei ved in Fiance during the 
 year 1772. Whilft he remained in that country, his 
 literary and political eminence made him courted by all 
 the anti-monarchical and infidel philofophers of the lime; 
 and in the religious fcepticifm and political theories of 
 Voltaire, Helvetius, Roufleau, and D'Alembert, he faw, 
 even at that period, the probable overthrow of religion 
 and government. His fentinients on this fubjedt he 
 took occafion, immediately on his return, to communi- 
 cate to the houfe of commons ; and to point cut the 
 confpirac'y of atheifin to the watchful policy of every 
 government. He profefled that he was not over-fond 
 of calling in the aid of the fecular arm to fupprefs doc- 
 trines and opinions ; but he recommended a grand al- 
 liance among all believers againft thofe minifters of re- 
 bellious darknefs, who were endeavouring to ftiake all 
 the works of God eftablilhed in beauty and in order. 
 
 The American war proving unfuccefsful, though 
 Great Britain never made a more glorious Hand, Lord 
 North and his friends retired from office ; and, in Fe- 
 bruary 1782, a new miniftry was formed, at the head 
 of which was placed the marquis of Rockingham; Lord 
 Shelburne and Mr Fox were the fecretaries of ftate ; 
 and Mr Burke, who was appointed pay-mailer to the 
 forces, exulted, rather childiflily, in the houfe of com- 
 mons, on the happinefs which was to accrue, both to 
 the king and to the people, from the able and upright 
 conduct of the new niiiiifters. The time in which the 
 greater part of them continued in oSice was too (hort 
 to permit them to do eilhei much good or much evil. 
 
 On the ift of July the marquis of Rockingham 
 died ; and the earl of Shelburne being placed at the 
 head of the treafury. Fox and Burke refigned in dif- 
 guft, and, to the artonifhment of the nation, formed 
 the famous coalition with Lord North, whofe meafures 
 they had lo long, and fo vehemently oppofed. In the 
 coalition of North and Burke there would have been 
 nothing wonderful. In the intercourfe of private life, 
 thefe two ftattfmen had always met on terms of friend- 
 fhip and mutual regard ; they had the fame ideas of 
 the excellence of th.e conttitution, and the fame averfion 
 to innovation under the name of reform ; even their 
 ftudies and amufements were very fimilar, being both 
 men of tafte and claffical learning ; and though Burke 
 oppofed the taxation of America by the Britifti parlia- 
 ment, his oppofitiou proceeded rather from motives of 
 prudence and expediency than from any fettled con- 
 viftion that the meafure was unconftitutional. But the 
 political enmity of Fox and North had proceeded, not 
 only to perfonal abufe, but to profcfPions of mutual ab- 
 horrence ; and perhaps there was hardly an unprejudi- 
 ced perfon in the kingdom who entertained not fufpi- 
 cions, that the unexpefted union of fuch enemies was 
 cemented by a principle lefs pure than patriotifm. 
 
 Mr Pitt was now chancellor of the exchequer ; and 
 
 when he announced to the houfe of commons the peace 
 
 S z which
 
 BUR [, I 
 
 Burl:c. which was conchiikd in J,iniiai7 178^, he foiinJ the 
 V ' terms on which it had bei 11 marie i'everely condemned 
 by Korth, Fox, Burke, and all their friends. The cen- 
 fiire pafled on it by Lord North and his followers was 
 perfcilly confillent with their former conduft, and with 
 the opinions which they had uniformly maintained ; 
 but it was with no good grace that Fox and Burke, 
 who had offered an unconditional peace to the Dutch, 
 and fo frequently propofed to recognize the indepen- 
 dence of America, condemned the peace which had been 
 concluded by Lord Shelburne. On this, as on many 
 other occafions, they afted, not as enlightened politi- 
 cians, but as the rancorous leaders of a party. 
 
 In confequence of a vote of cenfure pafTed by the 
 commons, the minifters refigned their employments, and 
 were fucceeded by the dnke of Portland, Lord North, 
 ]\Ir Fox, Mr BiM-ke, and their friends. Burke had his 
 form.er employment of paymafler to the forces ; Lord 
 North and Mr Fox were fecretaries of flate, and the 
 duke of Portland was firft lord of the treafury. To 
 many perfons this minlttry had the appearance of greater 
 ftrength than any that had governed the kingdom fince 
 the time of Sir Robert Walpole ; but its duration was 
 not longer than that of the preceding. On the i8th of 
 November, Mr Fox introduced his famous India-bill, 
 into the merits of which it is foreign from our purpofe 
 to enter: fufBce it to fay, that after being ftrongly fup- 
 porttd by Burke, and ably oppofed by Pitt and Dun- 
 das, it paflcd the houfe of commons by a very great ma- 
 jority ; but was loft in the houfe of peers, and viewed 
 by the king in fuch a light, that he determined on an 
 entire change of adminiflration. 
 
 Mr Pitt was now placed at the head of the treafury, 
 where he has remained ever fince (1800), notwithftand- 
 ing the violent and powerful oppofition which he met 
 v/ith at firft from North and Fox and their coalefced 
 friends : the voice of t!ie nation has been on his fide ; 
 and that voice will always drown the bellowings of pa- 
 triot ifm. 
 
 The principal events in which Burke fignalized hlm- 
 fclf, fince the year 1784, were the trial of Haftings, 
 the deliberations of the houfe on the propofed regency 
 during the lamented illnefs of the king, and the French 
 revolution ; and on each of thefe occafions he ditplayed 
 talents which aftoniftied the nation. He has, indeed, 
 been feverely blamed for the pertinacity with which he 
 profecuted Mr Haftings, and his conduft has been at- 
 tributed to very unworthy motives ; but of this there 
 is neither proof nor probability. The temperament of 
 his mind vtas fuch, that, into whatever meafure he en- 
 tered, he entered with a degree of ardour of which 
 cooler heads can hardly form a conception. Burke 
 was but one member of a committee which found, or 
 thought it found, evidences of the guilt of Haftings ; 
 and, in forming his opinion, it is little likely that he 
 (hould have been biaffed by intereft or refentment, whofe 
 delicate fenfe of rectitude would not permit him to re- 
 tain a penfion when he could no longer fupport the 
 party of that friend v/ho had obtained it for him. 
 
 When the eftabliihment of a regency was thought 
 neceifary, he took the part, as it was called, ot the 
 Prince of Wales, in oppofition to the plan propofed by 
 Lord Thurlow and the minifter ; and we doubt not 
 but he was actuated by the pureft principles : but the 
 language which he ufed ia the houfe was vehement, 
 
 40 ] BUR 
 
 and fon^e of his exprcflions were highly indecent. Our 
 reeard for his memory makes us wifli to forget them. 
 
 Soon after the recovery of the king, the attention of 
 Burke was attracted to the moft momentous event of 
 modern times ; — an event which has convulfed all Eu- 
 rope, and of which, from the very firft, his fagacity 
 forefaw the conlequences. Many of his friends in Par- 
 liament, as well as numbers of wile and good men out 
 of it, augured, from the meeting of the ftates-general 
 of France, great benefit to that nation, of which the 
 government was confidered as defpotic and opprefiive ; 
 and fome were fanguine enough to prognofticate a new 
 and happy order of things to all the nations connefted 
 with France, when its government ihould become more 
 free. Burke thought vtiy differently : He was well 
 acquainted with the genius of the French people, and 
 with the principles of thofe philofophers, as they called 
 themfelves, by Vv'hom a total revolution in church and 
 ftate had long been projefted; and from the commence- 
 ment of their career in the conftituent affembly, when 
 they eftablifhed, as the foundation of all legal govern- 
 ment, the metaphyfical dofirine of the rights of man, he 
 predicted that torrent of anarchy and irreligion which 
 they have fince attempted to pour over all Europe. 
 Fox and fome of the other leading men in oppofition 
 affefted to confider this as a vain fear ; and a coolnefs 
 took place between them and Burke, though they ftill 
 afted together in Parliament. At laft, perceiving the 
 French doftrines of liberty and equality, and atheifm, 
 fpreading through this nation, not only among thofe 
 who had talents for fuch difquifitions, but in clubs and 
 focieties, of which the members could be no judges of 
 metaphyfical reafonings, he expreffed his apprehenfion 
 of the confequences in the houfe of commons. This 
 brought on a violent altercation between him and Fox, 
 who was fupported by Sheridan ; and a rupture took 
 place between thefe old friends which was never healed. 
 He no more attended the meetings of the oppofition 
 members ; and in 1790 he publiftied his celebrated Re- 
 jledions en the French Revolution. 
 
 By the friends of government this work was admired 
 as the moft feafonable, as well as one of the ableft, de- 
 fences of the Britifh conftitution that ever was written j 
 whilft Fox and his friends, with the great body of Eng- 
 lifh diffenters, though they admitted it to be the oif- 
 fpring of uncommon genius, affefted to confider it as 
 declamatory rather than argumentative, and as incon- 
 fiftent with tlie principles which its author had hitherto 
 uniformly maintained. Many anfwers were written to 
 it ; of which the moft confpicuous were V'lndiciir Gallicce 
 by !Mr Mac Intofh, and The Rights of Man by Thomas 
 Paine. To thefe Burke deigned not to make a direft 
 reply. He vindicated his general principles, as well as 
 fome of his particular reafonings, in A Letter to a Mem- 
 ber of the National AJfemlly ; and he very completely 
 evinced the confiftency of his principles in his Appeal 
 from the Neiu to the Old Whigs. 
 
 Of this great work, for great it undoubtedly is, the 
 merits as well as the demerits have been much exagge- 
 rated ; and fome have made it a queftion, Whether it 
 has on the whole been produdive of good or harm ? 
 By the enemies of the author, it is reprefented as ha- 
 ving given rife to the fpirit of difcontent, by exciting 
 fuch writers as Paine and his adherents, who, but for 
 the provocation given by The ReJleSions, might have 
 
 remained 
 
 B.i'l^e.
 
 BUR [I 
 
 remained in filencc and obfcnr'ty, Tli;3 was from the 
 "^ firft a very improbable fuppofition ; for the fplrit of de- 
 mocracy has at all times been relllcfs : but fnice the ap- 
 pearance of Profeflbr Robiloii's Proofs of a Con/piracy, 
 and Bairuel's Hijlory of jfacobitiifm, it mud be known 
 to every reader to be a fuppofition contrary to faft. 
 The confpirators were bufy long before Burke wrote 
 his Refiedians ; and the friends of order and religion 
 are his debtors, for having fo forcibly roufed them from 
 their flumber, and put them on their guard. With re- 
 fpeft to compolition, it is certainly neither fo energetic 
 nor fo argumentative as the political trajits of Johnfon, 
 to which forne have affeiSed to confider it as fuperior : 
 but it is more poetical, gives fcope for a greater diiplay 
 of the knowledge of human nature; and, being written 
 on a more intereillng fubjedl, it has had a much great- 
 er number of readers than thofe unrivalled pieces of po- 
 litical controverly. 
 
 Burke being now aifociated with Mr Pitt, continued 
 to write from time to time memorials and remarks on 
 the ftate of France, and the alliance that was formed 
 againft the new order of things in that diftrafted coun- 
 try, of which fome have been publilhed fmce his death ; 
 and having refolved to quit the buftle of public life as 
 foon as the trial of Mr Haftings fliould be concluded, 
 he vacated his feat when that gentleman was acquitted, 
 and retired to his villa at Beaconsfield, where, on the 
 ad of Auguil 1794, he met with a heavy dom^ic lofs 
 in the death of his only fon. In the beginning of the 
 fame year he had loft his brother Richard, whom he 
 tenderly loved : but though this reiterated ftroke of 
 death deeply affefted him, it never relaxed the vigour 
 of his mind, nor lelTened the intereft which he took in 
 the public weal. 
 
 In this retreat, while he was labouring for the good of 
 all around him, he v.'as difturbed by a very unprovoked 
 attack upon bis chnrafter by forae diilinguiflied fpeakcrs 
 in the houfe ^.^i Peers. Soon after the death of his fon the 
 king was gracioufly pieafed to beftow a penfion on him 
 and Mrs Burke; and this thofe noble lords were plcafed 
 to reprefent as the rewardof what they termed the change 
 of his principles and the defertion of his friends. The 
 injnilice of this charge muft be obvious to every impar- 
 tial mind, lince the penfion was given after he had re- 
 tired from parliament, and could not by his eloquence 
 either fupport the niinillry or gall the oppofitlon. He 
 was not a man to fubmit tamely to fuch an infult. He 
 publi(hed a letter on the occafion, addreffcd to a noble 
 lord (Earl Fitzv.-ilh'am), in which he repels the attack 
 on his charafter, and retaliates on thofe by whom it was 
 made, in terms of fuch eloquent and keen iarcafm, as 
 will be read with admiration as long as the language of 
 the letter rtiall be underftood. 
 
 Burke having employed every eff<)rt which benevo- 
 lence and wifdor.i could devife to illmulate civilized go- 
 vernments to unite in oppoGtion to the impiety and 
 anarchy of France, laboured likewife in private to re- 
 lieve thofe who had fuffered exile and profcription from 
 the direful fyitem. Through his influence a fchool was 
 eftabliflied in his neiglibourhood for the education of 
 thofe whofe parents, fur their adherence to principle, 
 were rendered unable, to afford to their children ufeful 
 inilruftion ; and that fciiool, which on his deathbed he 
 recoir.mended to Mr Pitt, continues to flourilh under 
 bis. powerful protediion. 
 
 41 ] BUR 
 
 When the appearance of melioration In the principles 
 and government of France induced our fovcreign to 
 make overtures of peace to the French diredtory, Burke 
 refumed his pen ; and in a feries of letters, intitled, 
 Thoughts on the Profpea of a Regicide Peace, difpla)e(l 
 a force of genius which is certainly not furpatfed, and 
 perhaps not equalled, even in his far-famed Rcflcaions on 
 the French Revolution. This was his laft work, and 
 was confidered by himfelf as in its nature teftamen- 
 tary. 
 
 From the beginning of June 1797 his health rapidly 
 declined ; but his underftanding exerted itfelf with un- 
 diminifhed force and uncontrafted range ; and his dif- 
 pofitions retained all their amiable fweetnefs. On the 
 7th of July, when the French revolution was mentioned, 
 he fpoke with pleafure of the confcious redlitude of hi.^ 
 own intentions in what he had done and written refpeft. 
 ing It ; entreated thofe about him to believe, that if any 
 unguarded expreihon of his on the fubjeft had offended 
 any of his former friends, no offence was by him in- 
 tended ; and he declared his unfeigned forglvenefs of all 
 who had on account of his writings, or for any other 
 caule, endeavoured to do him an injury. On the day 
 following he defired to be carried to another room ; 
 and whiUl one of his friends, aflifled by fome fervants, 
 was complying with his requcft, Mr Burke faintly ut- 
 tering, " God blefs you," fell back and expired in the 
 68th year of his age. 
 
 From this detail, we trufl that our readers are already 
 fufficiently acquainted with his general charaftcr. In 
 genius, variety of knowledge, and readinefs of expref- 
 fion, Johnfon alone of all his contemporaries could be 
 confidered as his rival; and, like that great man, he 
 took every opportunity, efpecially during his lail illnefs, 
 to declare his unfliaken belief of tlie Chriftian religion, 
 his veneration for fincere Chrlftlans of all perfuafion?, 
 and his own preference of the church of England. On 
 the worflilp of that church he had Indeed through the 
 whole of his life been a regular and devout attendant ; 
 and the tears which the poor, in the neighbourhood t-.i 
 his villa, (hed at his funer;;!, gave fufificient evidence that 
 his faith had been produiHve of charity. In his public 
 conduft, the Irritability of his temper, and the ardouv 
 of his imagination, fometlmes hurried him into tlie ix- 
 ceffes of a mere party-num ; but we believe tl,at Ins 
 great religious and political principles never varied. Be 
 has himfelf charaCterifed his public conduA in the con- 
 clufion of his Reflecflons on the French Revolution, 
 when he fay?, that " they come from one who has been 
 no tool of power, no flatterer of greatnefs, and who in 
 his laft afts docs not wiih to belie the tenor of his life;, 
 from one who wifhes to preferVe confiftency, but who 
 would preferve confiftency by varying his means to fe. 
 cure the unity of his end; snd when the equipoife of 
 the veffel in which he fails may be endangered by over- 
 loading it upon one fide. Is defirous of cari-vln;j the 
 fmall weight of his reafons to that which mayprcfei-ve 
 the equipoife." 
 
 BURNET (James, Efq;), better known by the 
 title of Lord Aloniodt'o, defcended from- an ancient fa. 
 mily In the county of MeaiTis in Scotland. He was the 
 tldeft fon of Arthur Burnet, Efq; of Monhoddo, wlierj 
 he was born in the year 1714. After pafiing throujli 
 the ufual courfe of fchool education, he profeeuted hli 
 ftudies at the univcifilics of ALerdecn, Edinburgh, ani 
 
 L.cyde;)j, 
 
 Bu-kf, 
 
 Euinct. 
 
 V— V .J
 
 BUR 
 
 [ H 
 
 Burnet. 
 
 Leydin, with diftinguilhcd reputation. He was admit- 
 'ted an advocate in 1737 ; and on the 12th of February 
 J 767, he was raifed to the bench, by the title of Lord 
 Monboddo, in the room of Lord Milton, ajipointcd a 
 judge the 4th of June 1742, and who had lucceeded 
 Sir John Lauder of Fountainhall, admitted November 
 I. 16^9 ; fo that he was only the third judge in fucccf- 
 fion fince the revolution. 
 
 Before his promotion to the bench, he had married 
 Mifs Farquharfon, a very amiable woman, by whom he 
 had a fon and two daujjhters ; whom, without reirard- 
 ing the diflerence of climate, he reared as the childrefl 
 of ancient Greece were reared. 
 
 From early youth Lord Monboddo's application to 
 literary and juridical ftudies was feverely diligent. Be- 
 tween claffical literature and the law of Scotland, there 
 exifts a ftrong connexion, arifing from the adoption of 
 the forms and maxims of the civil law of the Romans, 
 by the ancient legiflators and judges of Scotland. Ac- 
 cordingly, while Mr Burnet rofe into reputation as a 
 lawyer, he at the fame time improved into profound 
 erudition that knowledge of the Greek and Roman 
 authors which he had acquired at fchool and the uni- 
 verfity ; and his partiality to the Greek language could 
 'not fail to be ftrengthened by his frequent converfa- 
 tions with Dr Blackwell, the celebrated profelTor of 
 that language in the Marifchal College and Univcrfity 
 of Aberdeen. 
 
 His favourite ftudies, however, were not fufFered to 
 interfere with his duty as a judge. In his native coun- 
 ty, his integrity as Sheriff will be long remembered ; 
 and during the whole time that he was a Lord of Sef- 
 fion, he difcharged the duties of his high office with an 
 affiduity, a patience, a clear intelligence, and inflexible 
 reftitude, which did honour to the court of which he 
 was a judge. Like others, he was liable to error ; 
 but neither the awe of power, the blandilhments of flat- 
 tery, nor even compafTiun for dillrefs, could turn Lord 
 Monboddo afide from what he believed to be the courfe 
 of juftice. 
 
 Several of the judges of the court of feflion were at 
 that period ambitious of fliining among philofophers 
 and men of tafte ; and I>ord Karnes's Elements of Cri- 
 tkifm is a work which will be long read, and always ad- 
 mired. It was not, however, admired by Lord Mon- 
 boddo ; and he determined to vindicate the fuperiority 
 of the ancients over the moderns, as well in philolophy as 
 in belles Icttres. With this view he published, in 1773, 
 the firft volume of his Origin and Progress of Lan- 
 guage ; whicli wasperufed with mingled fentiments of 
 refpeft and indignation. It was better received in Eng- 
 land than in his own country ; and notwithilanding the 
 ridicule brought upon him by his belief in the exiilence 
 of mermen, and men nvith tails, the author felt himfelf 
 fufficiently encouraged to complete his plan in five vo- 
 lumes. 
 
 Having, as he thought, vindicated Grecian literature, 
 he was induced to undertake another great work in de- 
 fence of Grecian philofopljy, againll the ftill more arro- 
 gant claims, as he deemed them, of Bacon and New- 
 ton, with their followers. With this view, he publifli- 
 ed, at different times, and in fix volumes 4to, a work 
 intitled Jncient Metaphyftcs, fraught, it muft be confef- 
 fed, with much erudition, much good fenfe, and, Itrange 
 as the combination may feem, with much abfurdity. In 
 
 2 ] B U 11 
 
 the preface to tlie firft volume, he declares open war Burnet, 
 againft all modern writers of philofophy, except Mr iT"" 
 Harris, who was an adorer of the ancients like himfelf, 
 Mr Baxter, and Dr Cudworth. He acknowledges Bax- 
 ter's- book on the Immateriality of the Soul to be a 
 truly valuable work ; and lays of Cudworth's IntelleHual 
 Syliem, that he agrees with it throughout. There is 
 indeed fuch a coincidence of notions in the IntelleSual 
 Sy/lem and the Aticicnt Metaphyftcs, that an ill-natured 
 critic might be tempted to fufpeft, that every thing 
 valuable in the latter was borrowed from the former. 
 
 The Ancient Metaphyftcs had few admirers in Scot- 
 land ; but it procured for its author, from a frholar of 
 Oxford, we think Mr Huntingford, the title of at^Km 
 Apitr7i7i^Bc. His Lordfliip continued to cultivate what 
 hj? called Greek philcfophy, and to attend his judicial du- 
 ties, with indefatigable diligence till within a few days 
 of his death, which happened at his houfe in Edinburgh, 
 on the 26th of May 1799, at the advanced age of 85. 
 
 His private life was fpent in the prattice of all the 
 focial virtues, and in the enjoyment of much domelUc 
 felicity. Although rigidly temperate in his habits of 
 life, lie, however, delighted much in the convivial focie- 
 ty of his friends ; and among thefe he could number 
 almoft all the moft eminent of thofe who were diftin- 
 guifhed in Scotland for virtue, literature, or genuine 
 elegance of converfation and manners. His fon, a very 
 promifing boy, in whofe education he took great de- 
 light, was fnatched away from his affeftions by a pre- 
 mature death. But when it was too late for forrow 
 and anxiety to avail, the afflifted father ftifled the emo- 
 tions of nature in his breaft, and wound up the energies 
 of his foul to the firmeft tone of ftoical fortitude. He 
 was, in like manner, bereaved of his excellent lady, the 
 objeft of his deareft tendernefs ; and he endured the 
 lofs with a fimilar firninefs, fitted to do honour either 
 to philofophy or to religion. In addition to his office 
 as a judge in the court of feflion, an offer was made to 
 him of a feat in the court of jufticiary. But though the 
 emoluments of the office would have made a convenient 
 addition to his income, he refufed to accept it, left its 
 bufinefs (hould too much detach him from the purfuit 
 of his favourite ftudies. 
 
 The vacations of the court of feffion afforded him fiif- 
 ficient leifure to retire every )'car, in fpring and in au- 
 tumn, to the country ; and be ufed then to drefs in a 
 Ityle of iimplicity, as if he had been only a plain far- 
 mer ; and to live among the people upon his eftate with 
 all the kind familiarity and attention of an aged father 
 among his grown-up children. Although the eftate, 
 from the old leafes, did not afford an income of more 
 three or four hundred pounds a-year, he would never 
 raife the rents upon his old tenants, nor difphce an old 
 tenant, for the fake of any augmentation of emolument 
 offered by a richer or more enteqinfing ftranger In 
 imitation of the rural economy of fome of the ancients, 
 whom he chiefly admired, he accounted population the 
 true wealth of an eftate, and was defirous of no other 
 improvement of his lands, than that of having the num- 
 ber of perfons that ftiould refide upon them, and be luf- 
 tained by their produce, fuperior to that of the popula- 
 tion of any equal portion of the lands of his neighbour.s. 
 It was at Monboddo that he had the pleafure of 
 receiving Dr Samuel Johnfon, with his friend James 
 Bofwell, at the time when thefe two gentlemen were 
 
 upon
 
 BUR 
 
 r H3 ] 
 
 BUR 
 
 Burnet, upnn their well-known Tour tlirough the Highlands 
 ""^ 'of Scotland. Johnfon admired nolliing in literature 
 {o much as the difplay of a keen dilcrimination of hu- 
 man charader, a juft apprehenfion of the principles of 
 moral aftion, and that vigorous common fenfe which 
 is the moll happily applicable to the ordinary con- 
 duct of life. Monboddo delighted in the refinements, 
 the fubtleties, the abftradlious, the affectations, of li- 
 terature ; and, in comparifon with theie, defpifed the 
 grolTnefs of modern taite and of common aflairs. John- 
 ion thouglit learning and fcience to be little valu- 
 able, except fo far as they could be made fubfervient 
 to the purpofes of living ufcfully and happily with 
 the world upon its own terms. Monboddo's favourite 
 fcience taught him to look down with contempt upon 
 all fublunary, and efpecially upon all modern things ; 
 and to fit life to literature and philofopl)y, not litera- 
 ture and philofophy to life. James Bofwell, therefore, 
 in carrying Joiuifon to vilit Monboddo, probably thought 
 of pitting them one againft another, as two game cocks, 
 and promifed himfelf much fport from the colloquial 
 conteft which he expeAcd to cntje between them. But 
 Monboddo was too hofpitable and courteous to enter 
 into keen contention with a llranger in his own houfe. 
 There was much talk between them, but no angry con- 
 troverfy, no exafperation of that diflike for each other's 
 well-known peculiarities with which they had met. 
 Johnfon, it is true, ftill continued to think Lord Mon- 
 boddo what he called a prig in literature ; and Mon- 
 boddo to cenfure Johnfon for allowing the moderns, in 
 fome things, to furpafs the ancients. 
 
 Lord Monboddo ufed frequently to vifit London, to 
 which he was allured by the opportunity that great me- 
 tropolis affords of enjoying tlie converfution of a vaft 
 number of men of profound erudition. A journey to 
 the capital became a favourite amufement of his periods 
 of vacation from the buiincfs of the court to which he 
 belonged; and, for a tim.e, he made this journey once 
 a-year. A carriage, a vehicle that was not in common 
 ufe among the ancients, he confidcred as an engine of 
 effeminacy and fioth, which it was uifgraceful for a man 
 to make ufe of in travelling. To be dragged at the 
 tail of a horfe, inltead of mounting upon his back, 
 feemed, in his eyes, to be a truly ludicrous degradation 
 of the genuine dignity of human nature. In all his 
 journeys, therefore, between Edinburgh and London, 
 he was wont to ride on horfeback, with a fingle fervant 
 attending him. He continued this pra<ftict, without 
 finding it too fatiguing for his flrength, till lie was up- 
 wards of eighty years of age. Within a few years of 
 his death, on his return from a laft viat, which he 
 made on purpofe to take leave of all his old friends 
 in London, he became exceedingly ill upon the road, 
 and was unable to proceed ; and had he not been over- 
 taken by a Scotch friend, who prevailed upon him to 
 travel the remainder of the way in a carriage, he might 
 perhaps have aftually perifhed by the way-fide, or 
 breathed his lall in fome dirty inn. 
 
 In London, his vifits were exceedingly acceptable to 
 all his friends, whether of the literary or falhionable 
 world. He delighted to Ihevv himfelf at court ; and 
 
 nious, at the houfe of Mrs Montague. However, after 
 the death of his friend Mr Harris, he found a very fin- ^ 
 (Ible diminution of the pleaiurc he had been wont to 
 enjoy in the fociely of London. 
 
 A conllltution of body, naturally framed to wear 
 well and lail long, was (Ircngthened to Lord Monbod- 
 do by ext-rcife, guarded by temperance, and by a tenor 
 of mind too firm to be deeply broken in upon by thofe 
 paffions which confiime the principles of life. In the 
 country he always ufid much the cxtrcifes of walking 
 in the open air and of riding. The cold bath was a 
 means of preferring the health, to which he had re- 
 courfe in all ieafons, amid every feverity of the weather, 
 and under every inconvenience of indifpofition or bufi- 
 nefs, with a ptrfeverance invincible. He was accuilomed, 
 alike in winter and in fummer, to rife at a very early 
 hour in the morning, and, without lofs of time, to be- 
 take hi»nfclf to ftudy or wholefonie exercife. It is fsid 
 that he even found the ufe of what he called the air 
 bath, or the pradlice of occafionally walking about, for 
 fome minutes, naked, in a room filled with frefh and 
 cool air, to be highly falutary. In a word, if his pecu- 
 liarities were ftriking, his virtues, and learning, and ta- 
 lents, were equally llriking ; and, taken altogether, he 
 muft be confidered as a great and a good man. 
 
 BURNS (Robert), was a native of Airfhire, one 
 of the weftern counties of Scotland. He was the foa 
 of humble parents ; and his father paffcd through life 
 in the condition of a hired labourer, or of a fmall far- 
 mer. Even in this fituation, however, it was not hard 
 for him to fend his children to the parifh-fchool, to re- 
 ceive the ordinary inftruiftion in reading, writing, arith- 
 metic, and the principles of religion. By this courfe of 
 education young Robert profited to a degree that might 
 have encouraged his friends to deftine him to one of 
 the liberal profcffions, had not his father's poverty made 
 it neceffary to remove him from fchool, as foon as he 
 had grown up, to earn for himfelf the means of fupport 
 as a hired ploughboy or fhepheid. 
 
 The expence of education in the parilh-fchools of 
 Scotland is fo fjuall, that hardly any parents who are 
 able to labour want the means of giving to their child- 
 ren at leall fuch education as young Burns received. 
 From the fpring labours of a ploughboy, from the 
 fummer employment of a Ihepherd, the peafant-youth 
 often returns for a few months, eagerly to purfue his 
 education at the parifh-fchool. 
 
 It was fo with Burns : he returned from labour to 
 learning, and from learning went again to labour, till 
 his mind began to open to the charms of tafte and 
 knowledge ; till he began to feel a paffion for books, 
 and for the fubjetls of books, which was to give a co- 
 lour to the whole thread of his future life. On nature 
 he foon began to gaze with new difcernment and with 
 new enthufiafm : his mind's eye opened to perceive af- 
 fefting beauty and fublimity, where, by the mere grofs 
 peafant, there was nought to be feen but water, earth, 
 and Iky — but animals, plants, and foil. 
 
 What might perhaps firll contribute to difpofe his 
 mind to poetical efforts, is one particular in the devo- 
 tional piety of the Scottifh peafantry ; it is ftill corn- 
 
 Burnt. 
 
 the king is faid to have taken a pleafure in converfing mon for them to make their children get by heart the 
 with the old man with a diftinguifhing notice that could Pfalms of David, in that verfion of homely rhymes 
 not but be very flattering to him. He ufed to mingle, which is ufed in their churches. In the morning and 
 with great fatisfadioa, with the learned and the inge. in the evening of every day, or at leaft on the evening 
 
 of
 
 BUR [ 144 ] BUR 
 
 Burns, of every Saturday and Sunday, tlief^ PHiIma are Tung blaije of the beautiful and the ruggedly grand, of the 
 
 •~~v in folenin family-devotion, a' chapter of the Bible is cultivated and the wild ; looking upon human life with 
 
 Tcad, and extemporary prayer is fervently uttered. The an eye tiulck and keen, to remark as well the ibonger 
 
 whole books of the Sacred Scriptures are thus conti- and leading, as the nicer and fubordinate, features of 
 
 iiually in the hands of alnioft every peirfant. And it is charader ; to diicriminate the generous, the honour- 
 
 inipoffible that there ihould not be oecafionally fome able, the manly, in conduft, from the ridiculous, the 
 
 i'ouls among them, awakened to the divine emotions of bafe, and the mean— he was diiUnguifhed among his 
 
 genius by that rich aflemblage which thofe books pre- fellows for extraordinary intelligence, good fenfe, and 
 
 jent, of almoft all that is interefting in incidents, or pic- penetration, long before others, or perhaps even him- 
 
 turefque in imagery, or affeftingly fuhlime or tender in felf, fufpefted him to be capable of writing verfes. His 
 
 ■Sentiments and charafter. It is impofilble that thofe mind was mature, and well ftored with fuch knowledge 
 
 lude rhymes, and the fimple artlefs mufic with which as lay within his fearch : he had made himfelf matter of 
 
 ihey are accompanied, (liould not occafionally excite powers of language, fuperior to thofe of almoft any for- 
 
 Burni. 
 
 ey are accomp; 
 lome ear to a fond perception of the melody of verfe. 
 That Burns had felt thefe impulfes, will appear unde 
 iably certain to whoever fliall carefully perufe his Col 
 
 mer writer in the Scottlfli dialeft, before he conceived 
 the idea of furpaffing Ramfay and Fergufon. 
 
 Hitherto he had converied intimately ooly with pea- 
 fants on his own level ; but having got admiflion into 
 
 tjr's Saturday's AlgLt ; or fliall remark, with nice ob- fan _ 
 
 fervation, the various fragments of Scripture fentiment, the fraternity of free malons, he had the fortune, whe- 
 of Scripture imagery, of Scripture language, which . ther good or bad, to attrad in the lodges the notice of 
 are fcattered throughout his works. gentlemen better quahfied than his more youthful cora- 
 
 Still more intereiling to the young peafantry are panions to call forth the powers of his mind, and to 
 thofe ancient ballads of love and war, of which a great fliow him that he was indeed a poet. A mafonic fong, 
 number are, in the fouth of Scotland, yet popularly a fatirical epigram, a rhyming epiftle to a friend, at- 
 known, and often fung by the ruftic maid or matron at tempted with fuccefs, taught him to know his own 
 her fpinning-wheel. They are liitened to with ravilhed powers, and gave him confidence to try tafl-cs more 
 ears by old and young. Their rude melody ; that arduous, and which fhould command ftiU higher burlls 
 mingled curiofity and awe which are naturally excited of applaufe. 
 
 by the very idea of their antiquity; the exquifitely The annual celebration of the facrament of the Lord's 
 tender and natural complaints fometimes poured forth Supper, in the rural parlihes of Scotland, has much in it 
 in them ; the gallant deeds of knightly heroifm, which of thofe old popi(h fellivals, in which fuperftition, traffic, 
 they fometimes celebrate ; their wild tales of demons, and amufement,ufed to be ftrangely intermingled. Burns 
 ghofts, and fairies, in whole exiftence fuperftition alone faw, and feizcd in it one of the happiefl of all fubjeds, 
 has believed ; the manners which they reprefent ; the to afford fcope for the difplay of that ftrong and pier- 
 obfolete, yet pidurefque and expreffive, language in cing fagacity by which he could almoll intuitively di- 
 which they are often clothed — give them wonderful ftinguilh the reafonable from the abfurd, and the beco- 
 power to tranfport every Imagination, and to agitate coming from the ridiculous; of that pidurefque power of 
 every heart. To the foul of Burns they were like a fancy, which enabled him to reprefent fcenes, and per- 
 Kappy breeze touching the wires of an iEolian harp, fons, and groupes, and looks, attitude, and geftures, in 
 and calhng forth the moft ravifhing melody. a manner almoft as lively and imprefiive, even in words, 
 
 Befide all this, the Gentle Shepherd, and the other as if all the artifices and energies of the pencil had been 
 poems of Allan Ramfay, have long been highly popu- employed ; of that knowledge which he had neceflarily 
 iar in Scotland. They fell early into the hands of acquired of the manners, paflions, and prejudices of the 
 Burns ; and while the fond applaufe \vhich they recei- ruftics around him, of whatever was ridiculous, no lefs 
 ved drew his emulation, they prefented to him like- than of whatever was affedingly beautiful in rural 
 wife treafures of phrafeology and models of verfifica- life. 
 
 tion. He got acquainted at the fame time with the A thoufand prejudices of Popifh, and perhaps too of 
 poetry of Robert Fergufon, written chiefly in the Scot- ruder Pagan fuperftition, have from, time immemorial 
 tifh dialed, and exhibiting many fpecimens of uncom- been conneded in the minds of the Scottilh peafantry, 
 mon poetical excellence. The Seafons of Thomfon with the annual recurrence of the Eve of the Feftival of 
 too, the Grave of Blair, the far-famed Elegy of Gray, all the Saints or Halloween. Thefe were all intimate- 
 the Paradife Loft of Milton, perhaps the Minftrel of ly known to Burns, and had made a powerful impref- 
 Beattie, were fo commonly read, even among thofe fion upon his imagination and feelings. He chofe them 
 with whom Burns would naturally aflbciate, that poe- for the fubjed of a poem, and produced a piece which 
 tical curiofity, although even lefs ardent than his, could is almoft to frenzy the delight of thofe who are beft ac- 
 in fuch circumftances have little difficulty in procuring quainted with its fubjed ; and which will not fail to 
 them. preferve the memory of the prejudices and ufages which 
 
 With fuch means to give his imagination a poetical it defcribes, when they (hall perhaps have ceafed to give 
 bias, and to favour the culture of his tafte and genius, one merry evening in the year to the cottage tire- 
 Burns gradually became a poet. He was not, however, fide. 
 
 one of thofe forward children who, from a miftaken im- The fimple joys, the honeft love, the fincere friend- 
 pulfe, begin prematurely to write and to rhyme, and Ihip, the ardent devotion of the cottage ; whatever in 
 lience never attain to excellence. -Converfing familiarly the more folemn part of the ruftic's lite is humble and 
 for a long while with the works of thofe poets who artlefs, without being mean or unfeemly — or tender and 
 were known to him ; contemplating the afped of na- dignified, without afpiring to ftilted grandeur — or to 
 .ture in a diftrid. which exhibits an uncommon aflem- unnatural, bullcined pathos, had deeply imprefied the 
 
 imagination
 
 BUR 
 
 C Hi 1 
 
 BUR 
 
 imagination of the riling poet ; liaJ, in fome foit, 
 ' wrought itfelf into the very texture of the fibres of his 
 ioiil. He tried to exprefs in verfe what he moll ten- 
 derly felt, what he moft enthufiallieally imagined ; and 
 prodviced the Collar's Saturday Night. 
 
 Thefe pieces, the true clfulions of genius, informed 
 by reading and obfervation, and pnniipted by its own 
 native ardour, as well as by friendly applaufe, were 
 foon handed about among the moil difeerning of Burns's 
 acquaintance ; and were by every nev/ reader perufed, 
 and reperufed, with an eagernefs of delight and appro- 
 bation which would not fuffer their author long to with- 
 hold them from the prefs. A fubfcription was propofed, 
 was earneilly promoted by fome gentlemen, who were 
 glad to intered themfelves in behalf of luch fignal poe- 
 tical merit ; was foon crowded with the names of a 
 confiderable number of the inhabitants of Airlliire, who 
 in tlie proffered purchafe fought not lefs to gratify 
 their own paffion for Scottilli poefy, than to encourage 
 the wonderful ploughman. At Kilmarnock were the 
 poems of Burns for the firil time printed. The whole 
 edition was quickly dillributed over the country. 
 
 It is hardly poffible to exprefs with what eager ad- 
 miration and delight they were everywhere received. — 
 They eminently polTeffed all thofe qualities which the 
 moil invariably contribute to render any literary work 
 quickly and permanently popular. They were written 
 in a phrafeology, of which all the powers were univer- 
 fally felt ; and which being at once antique, familiar, 
 and now rarely written, was hence fitted to ferve all 
 tlie dignified and pidturefque ufes of poetry, without 
 making it unintelligible. The imagery, the fentiments, 
 were at once faithfully natural, and irrefiftibly impreifive 
 and interelling. Thofe topics of fatire and fcandal in 
 which the rultic delights ; that humorous imitation of 
 charadler, and that witty afTociation of ideas familiar 
 and ftriking, yet not naturally allied to one another, 
 which has force to Ihake his fides with laughter ; thofe 
 fancies of fuperftition, at which he dill wonders and 
 trembles ; thofe affetling fentiments and images of true 
 religion, which are at once dear and awful to iiis heart 
 — were all reprefented by Burns with all a poet's magic 
 power. Old and young, high and low, grave and gay, 
 learned or ignorant, all were alike delighted, agitated, 
 tranfported. 
 
 In the mean time, fome few copies of thefe fafcina- 
 ting poems found their way to Edinburgh; and having 
 been read to Dr Blacklock, they obtained his warmeit 
 approbation. In the beginning of the winter 1786-7 
 Burns went to Edinburgh, where he was received by 
 Dr Blacklock with the moft flattering kindnefs, and 
 introduced to every man of generolity and talle among 
 that good man's friends. Multitudes now vied with 
 each other in patronizing the ruftic poet. Thofe who 
 pofTefled at once true tafte and ardent philanthropy 
 ivere foon earneilly united in his praife : they who were 
 dilpoled to favour any good thing belonging to Scot- 
 land, purely becaufe it was Scottilh, gladly joined the 
 .cry ; thofe who had hearts and underllanding to he 
 'charmed, without knowing why, when they faw their 
 native culloms, manners, and language, made tlie fub- 
 jefts and the materials of poefy, could not fuppvefs that 
 voice of feeling which ftruggled to declare itfcif for 
 Burns : for the diliipaced, the licentious, the malignant 
 •tvits, .andJthe freetliiakers^ he was fo .unfortunate as to 
 ;" .SuppL. \'oL. T. I'art. I. 
 
 have fatire, and obfcenlty, and ridicule of thing.i facred, Bun-j. 
 fnflicie'U to captivate their f.iiicies ; even for the pfoiij *-— v— 
 he had paffiges in which the infpired language of de- 
 votion might leem to come mended from his pen. 
 
 Thus did Burns, ere he had been many weeks in E- 
 dinburgh, find himfelf the objeA of univerfal curicfity, 
 favour, admiration, and fondnefs. He was fought after, 
 courted with attentions the moll refpedtful and alTidu- 
 ous, feafled, flattered, carcfled, treated by all ranks as 
 the firll boall of his country, whom it was fcarcely pof- 
 fible to honour and reward to a degree equal to his 
 merits. In comparifon with the general favour whlcli 
 now promifed to more than crown his mod fangulni; 
 hopes, it could hardly be called praife at all which he 
 had obtained in Alrfhlre. 
 
 In this poflure of our poet's aflTairs a new edition of 
 his poems was earneilly called for. He fold the copy- 
 right for one liundred pounds ; but his friends at the 
 fame time fuggefled, and adlivcly promoted, a fubfcrip- 
 tion for an edition, to be publlllicd for the benefit of 
 the author, ere the bookfeller's right fliould commence. 
 Thofe gentlemen who had formerly entertained the pub- 
 lic of Edinburgh with the periodical publication of the 
 papers of the Mirror, having again combined their ta- 
 lents in producing the Lounger, were at this time abou- 
 to conclude this lafl ferics of papers ; yet before the 
 Lounger reliiiquilhed his pen, he dedicated a number to 
 a commendatory critlcifm of the poems of the Alrlhire 
 bard. 
 
 The fubfcn'ption-papers were raj>idly filled ; and it 
 was fuppofed that the poet nn'ght derive from the fub- 
 fcription and the fale of his copy-right a clear profit ot 
 at leall 700 pounds. 
 
 The converfatlon of even the mofl eminent authors 
 is often found to be fo unequal to the fame of their 
 writings, that he who reads with admiration can liilen 
 with none but fentiments of the mod profound contempt. 
 But the converfatlon of Burns was, in comparifon with 
 the formal and exterior circumftances of his education, 
 perhaps even more wonderful than his poetry. He af- 
 fefted no foft air or graceful mc>tions of politencfs, 
 which might have ill accorded with the ruflic plainnefs 
 of his native manners. Confcious fuperiority of mind 
 taught him to aflbciate with the great, the learned, and 
 the gay, v\lthout being overawed into any fuch baihful- 
 nefs as might have made him confufed in thought, or 
 hefitating in elocution. He ponVfled withal an extra- 
 ordinary fhare of plain common fenle or mother-wit, 
 which prevented lilm from obtruding upon perlons, of 
 whatever rank with whom he was admitted to converfe, 
 any of thofe clTufions of vanity, envy, or felf conceit, in 
 which authors are exceedingly apt to indulge, who have 
 lived remote from the general praclice of li(e, and whofe 
 minds have been almofl exclufively confined to contem- 
 plate their own ftudies and their own works. In con- 
 verfatlon he difplaycd a fort of intuitive quicknefs and 
 .re6t)tude of judgment upon every fubjecl that arofe. 
 The fenfibility of his heart, and the vivacity of In's fan- 
 cy, gave a rich colouring to whatever re;<foning he was 
 difpofcd to advance ; and his languagef>vn converfatlon 
 wai not at all lefs happy than in his writings. For 
 thefe reafons, thofe who had m< t andconvcrfed with hhn 
 once, were pleafcd to meet and to converfe with hrni 
 again and again. 
 
 For fome time he convcrftd only with the virtuous, 
 T ihr
 
 BUR 
 
 Burnt, the learned, and the wife ; and the purity of his morals 
 ""■v"—' remained uncontaminated. But, ahs ! he fell, as others 
 have fallen in fimllar circuniftances. He fulFercd liim- 
 felf to be fiuTOunded by a race of miferable beings, who 
 were proud to tell that they had been in company with 
 Burns, and had feen Burns as loofc and as foolifh as 
 themfelves. He was not yet irrecoverably loft to tem- 
 perance and moderation ; but he was already almoft 
 too much captivated with their wanton revels, to be 
 ever more won back to a faithful attachment to their 
 more fober charms. He now alfo began to contratl 
 fomething of new arrogance in converfation. Accuf- 
 tomed to be among his favourite affoclates what is vul- 
 g*rly but expreflively called ihe cock of th; company, he 
 could fcarcely refrain from indulging in funilar freedom 
 and dictatorial decifiou of talk, even in the prcfence of 
 perfons who could lefs patiently endure his prefump- 
 tion. 
 
 The fubfcription-edition of his poems, in the m.ean 
 time, appeared; and although not enlarged beyond that 
 which came from the Kilmarnock prefs by any new 
 pieces of eminent merit, did not fail to give entire ia- 
 tisfaftion to the fubfcribers. He was now to clofe ac- 
 counts with his bookfeiler and his printer, to retire to 
 the country with his profits in his pocket, and to fix 
 upon a plan for his future life. He talked loudly of 
 independence of fpirit and fimplicity of manners, and 
 boalied his refolution to return to the plough ; yet ftiU 
 he lingered in Edinburgh, week after week, and month 
 after month, perhaps expetting that one or other of his 
 noble patrons might procure him fome permanent and 
 competent annual income, which (hould fet him above 
 all neceffity of future exertions to earn for himfelf the 
 means of fubfiftence; perhaps unconfcioudy nluftant to 
 quit the pleafurec of that voluptuous town-life to which 
 he had for fome time too willingly accuftomed himfelf. 
 An accidental dlflocation or frafture of an arm or a leg 
 confining him for fome weeks to his apartment, left him 
 during this time leifure for ferious reflection ; and he 
 determined to retire from the town without longer de- 
 lay. None of all his patrons intcrpofed to divert him 
 from his purpofe of returning to the plough, by the of- 
 fer of any fmall penfion, or any finecure place of mode- 
 rate emolument, fnch as might have given him compe- 
 tence without withdrawing him from his poetical ftu- 
 dies. It feemed to be forgotten that a ploughman thus 
 exalted into a man of letters was unfitted for his for- 
 mer toils, without being regularly qualified to enter the 
 career of any new profefGon ; and that it became in- 
 cumbent upon thofe patrons who had called him from 
 the plough, not merely to make him their companion in 
 the hour of rio^, not limply to fill his purfe with gold 
 for a few tranfieut expences, but to fecure him as far 
 as was pofTible from being ever overwhelmed in diftrefs in 
 confequence of the favour which they had fliown him, 
 and of the habits of life into which they had fcduced 
 him. Perhaps indeed the fame delufion of fancy be- 
 trayed both Burns and his patrons into the miftaken 
 idea, that, after all which had paffed, it was ftill poffible 
 for him to return in cheerful content to the homely 
 joys and iimple toils of undiffipated rural life. 
 
 In this temper of Burns's mind, in this ftate of his 
 fortune, a farm and the excife were the objefts upon 
 which his choice ultimately fixed fo? future employment 
 and fupport. By the furgeon who attended him during 
 
 [ 146 ] 
 
 BUR 
 
 his illnefs, he was recommended with efTeft to the com- Burnt. 
 miflioners of excife ; and Patrick Millar, Efq. of Dal- '~"~v~~' 
 fwinton, deceived, like Burns himfelf and Burns's other 
 friends, into an idea that the poet and excifeman might 
 yet be refpeftable and happy as a farmer, generouily 
 propofcd to eftablifh him in a farm, upon conditions of 
 leafe which prudence and induftry might eafily render 
 exceedingly advantageous. Burns eagerly accepted the 
 offers of this benevolent patron. Two of the poet's 
 friends from Airfhire were invited to fuivey that farm 
 in Dumfriesdiire which Mr Millar offered. A leafe 
 was granted to the poetical farmer at that annual rent 
 which his own friends declared that the due cultivation 
 of his farm might eafily enable him to pay. What yet 
 remained of the profits of his publication was laid out 
 in the purchafe of farm-llock ; and Mr Millar might, 
 for fome fliort time, pleafe himfelf with the perfuafion 
 that he had approved himfelf the liberal patron of ge- 
 nius ; had acquired a good tenant upon his eilate ; and 
 had placed a deferving man in the very fituation in 
 which alone he himfelf defired to be placed, in order to 
 be happy to his wifhes. 
 
 Burns, with his Jane, whom, he now married, took 
 up their refidence upon his farm. The neighbouring 
 farmers and gentlemen, pleafed to obtain for an inmate 
 among them the poet by whofe works they had been 
 delighted, kindly fought his company, and invited him 
 to their houfes. He found an inexpreflible charm m. 
 fitting down btfide his wife, at his own firefide ; in 
 wandering over his own grounds; in once more putting 
 his hand to the Ipade and the plough ; in forming his 
 enclofures, and managing his cattle. For fome months 
 he felt almoft all that felicity which fancy had taught 
 him to expeft in his new fituation. He had been for 
 a time idle ; but his mufcles were not yet unbraced for 
 rural toil. He now feemed to find a joy in being the 
 hufband of the miftrefs of his affedlions, in feeing him- 
 felf the father of her children, fuch as might promife to 
 attach him for ever to that modell, humble, and domef- 
 tic life, in which alone he could hope to be permanent- 
 ly happy. Even his engagements in the fervice of the 
 excife did not, at the very firft, threaten neceffarily to 
 debafe him by affociation with the mean, the grofs, and 
 the profligate, to contaminate the poet, or to ruin the 
 farmer. 
 
 But it could not be : it was not poffible for Burns 
 now' to affume that fobernefs of fancy and pafTions, that 
 fedatenefs of feeling, thofe habits of earneft attention to 
 grofs and vulgar cares, without which fuccefs in his new 
 fituation was not to be expefted. A thoufand difficul- 
 ties were to be encountered and overcome, much money 
 was to be expended, much weary toil was to be exer- 
 cifed, before his farm could be brought into a ftate of 
 cultivation in which its produce might enrich the oc- 
 cupier. This was not a profpeft encouraging to a man 
 who had never loved labour, and who was at this time 
 certainly not at all difpofed to enter into agriculture 
 with the enthufiafm of a projeftor. The bufinefs of the 
 excife too, as he began to be more and more employed 
 in it, diilrafted his mind from the care of his farm, led 
 him into grofs and vulgar fociety, and expofed him to 
 many unavoidable temptations to drunken excefs, fuch 
 as he had no longer fufHcient fortitude to refill. Amidft 
 the anxieties, diltraftions, and feducements which thus 
 arofe to him, home becam.e infenfibly lefs and lefs plea- 
 
 fm?
 
 BUR 
 
 finff J even the endearments of his Jane's afTcdion be- 
 'gan to lofe their hold on liis heart ; he became every 
 day lefs and Icfs unwilh'ng to forget in riot thofe ga- 
 thcrinf forrows which he knew not to liibdue. 
 
 Ml Millar and fome others of his friends would glad- 
 ly have exerted an influence over his mind which might 
 have prefervcd him in this fituation of his affairs, equally 
 from dcfpondency and from diifipation ; but Burns's 
 temper fpiirned all controul from his fuperiors in for- 
 tune. He refented, as an arrogant encroachment upon 
 his independence, that tenor of coiiduft by which Mr 
 Millar wi{hed to turn him from diflolute conviviality, 
 to that Heady attention to the bullnefs of his farm, 
 without which it was inipoffible to thrive in it. His 
 croffes and difappointments drove him every day more 
 and more into diifipation ; and this diffipation tended to 
 enhance whatever was difagreeable and perplexing in 
 the (late of his affairs. He funk, by degrees, into the 
 boon companion of mere cxcifemen ; and almoft every 
 drunken fellow, who was willing to fpcnd his money la- 
 vlflily ill the alehoufe, could eafily command tlie com- 
 pany of Burns. The care of his farm was thus uegl-fl- 
 ed ; wade and loffes wholly confumed his little capital ; 
 he refigned his leafe into the hands of his landlord; and 
 retired, with his family, to ti,e town of Dumfries, de- 
 termining to depend entirely for the means of future 
 fupport upon his income as an excife-ofiicer. 
 
 Yet during this unfortunate period of his life, which 
 paffed between his departure from Edinburgh to fettle in 
 Dumfriesdiire, and his leaving the country, in order to 
 take up his refidence in the town of Dumfries, the ener- 
 gy and activity of his intclledlual powers appeared to 
 have been not at all impaired. In a colledllon of Scot- 
 tidi fongs, which were publifhed (the words with the 
 mufic) by Mr Johnfon, engraver in Edinburgh, in 4 
 vols Kvo, Burns, in many inftances, accomniod:ited new 
 verfcs to the old tunes with admirable felicity and Ikill. 
 He affiilcd in the temporary inftitution of a fmall fub- 
 icrrption library, for the uie of a number of the well- 
 difpofed peafants in his neighbourhood. He readily 
 aided, and by his knowledge of genuine Scottiih phra- 
 feolc^y and manners greatly enlightened, the antiqua- 
 rian refcarches of the late ingenious Captain Grofe. 
 He ftill carried on an epillolary correfpondence, fome- 
 tlmes gay, fportive, humorous, but always enlivened 
 by bright flalhea of genius, with a number of his old 
 triends, and on a very wide diverfity of topics. At 
 times, as it (hould feem from his writings of this period, 
 he reflected, with inexprefiible' heart-bitternefs, on the 
 high hopes from which he had fallen ; on the errors of 
 moral conduft into which he had been hurried by the 
 ardour of his foul, and in fome meafure by the very ge- 
 nerofity of his nature ; on the difgrace and wretchednefs 
 into which he faw himfelf rapidly finking ; on the for- 
 row with which his niifcondufl oppreffed the heart of 
 his Jane ; on the want and deftitute mifery in which it 
 feemed probable that he muft leave her and their in- 
 fants ; nor amidft thefe agonizing refleftions did he fail 
 to look, with an indignation half invidious, half con- 
 temptuous, on thofe who, with moral habits not more 
 excellent than his, with powers of intelleft far inferior, 
 yet balked in the fun-fhine of fortune, and were loaded 
 with the wealth and honours of the world, while his 
 follies could not obtain pardon, nor his wants an ho- 
 nourable fupply. His wit became from this time more 
 
 [ Ml ] 
 
 BUR 
 
 gloomily farcaftic ; and his converfation and writings Burni. 
 began to affiime fomething of a tone of mifanthropical ^~~v~~" 
 malignity, by wliicii they had not been before, in any 
 eminent degree, diftinguiflied. But with all thefe fail- 
 ings, he was Hill that exalted mind which had raifcd 
 itfclf above the depreffion of its original condition : 
 with all the energy of the lion, pawing to fet free his 
 hinder limbs from the yet encumbering earth, he Ilill 
 appeared not Icfs than .ircbaiigel ruined ! 
 
 His morals were not mended by his removal from 
 the country. In Dumfries his diffipation became ftill 
 more deeply habitual ; he was here more expofed than 
 in the country to be folicited to (hare the riot of the 
 diffolute and the idle: foolifii young men flocked eager- 
 ly about him, and from time to time preffed him to 
 drink with them, that they might enjoy his wicked wit. 
 The Caledonian Club, too, and the DumfriesOiire and 
 Galloway Hunt, had occalional meetings in Dumfries 
 after Burns went to refide there, and the poet was of 
 courfe invited to (hare their conviviality, and helitatcd 
 not to accept the invitation. 
 
 [n th? intervals between his different fits of intem- 
 perance, he fuffered Ilill the keeneft anguilh of rcniorfe, 
 and horribly affliftive foreiight. His Jane ftill behaved 
 with a degree of maternal and conjugal tendernefs and 
 prudence, which made him feel more bitterly the evil of 
 his mifcondudi, although they could not reclaim him. 
 At lail crippled, emaciated, having the very power of 
 animation wafted by difeafe, quite broken-hearted by 
 the fenfe of his errors, and of the hopclefs miferies in 
 which he faw himfelf and his family depreffed ; with, 
 his foul Ilill tremblingly alive to the fenfe of (liame, and 
 to the love of virtue ; yet even in the laft feeblenels, 
 and amid the laft agonies of expiring life, yielding rea- 
 dily to any temptation that offered the femblance of in- 
 temperate enjoyment, he died at Dumfries, in the funi- 
 mer of 1796, while he was yet three or four years un- 
 der the age of forty, furniihing a melancholy proof of 
 the danger of Juddenly elevating even the greateft mind 
 above its original level. 
 
 After his death, it quickly appeared that his failings 
 had not elfaced from the minds of his more refpeflable 
 acquaintance either the regard which had once been 
 won by his locial qualities, or the reverence due to his 
 intelletfual talents. The circumftances of want In which 
 he left his family were noticed by the gentlemen of 
 Dumfries with earned commifciation. His funeral was 
 celebrated by the care of his friends with a decent fo- . 
 lemnity, and with a numerous attendance of mourners, 
 fulficlently honourable to his memory. Several copies 
 of verfes were inferted in different newfpapers upon the 
 occafion of his death. A contribution, by fubfcrlption, 
 was propofed, for the purpofe of raifing a fmall fund, 
 for the decent fupport of his widow, and the education 
 of his infant children. 
 
 From the preceding detail of the particulars of this 
 poet's life, the reader will naturally and juftly infer him 
 to have been an honeft, proud, warm-hearted man ; of 
 high paffions and found underftandiug, and a vigorous 
 and excurfive imagination. He was never known to 
 defcend to any aft of deliberate meannefs. In Dum- 
 fries he retained many refpeftable friends even to the 
 laft ; and it may be doubted whether any poet of the 
 prefent age has exerciled a greater power over the 
 minds of his readers. Burns has not failed to command 
 T2 one
 
 BUT [ 148 ] BUT 
 
 Surram. one reitiavkable fort of homage, fuch es is never paid with the mixture appears of a rich marrowy confidence Buter, 
 
 pooler, 
 Butter. 
 
 but to great original genius ; a crowd of poetailers and fine colour, and never acquires a brittle hardnefs ' 
 ftarted up to imitate him, by writing verfes as he had nor taftes fait ; the other is comparatively liard and 
 done in the Scottilh dialeft ; but, imitatores ! fcrvum brittle, approaching more nearly to the appearance of 
 To v.'rite rugged rh!mi-s, in antiquated phrafe, is tallow, and is much falter to the tafte. I have ate but- 
 " ' " ~ ter cured with the above compofition that had been 
 
 kept three years, and it was as fweet as at firft ; but it 
 mufl be noted, that butter thus cured requires to ftand 
 three week& or a month before it is begun to be ufed. 
 If it be fooner opened, the falts are not fufficiently 
 blended with it ; and fometimes the coolnefs of the nitre 
 will then be perceived, which totally difappears after- 
 wards." 
 
 The following obfervationsrefpefting the proper me- 
 
 not to imitate tlie poctrv of Burns. 
 
 BURRAMPOOTER. See Sandpu, Encycl. 
 BUTTER is a fubftancc fo well known, that it is 
 needlcfs to give here any definition of it ; but as it is, 
 in this country at Icall, fo general an article of food, that 
 the proper methods of making and curing it have en- 
 gaged the attention of fome of our ablefl writers on 
 agriculture, in addition to what has been faid on thefe 
 
 fubjefls under the titles Butter and Dairy (iinfj'^'-) . _ . _ _ . . 
 
 our readers will probably be pleafed with the following thod of keeping both milk and butter are by the fame 
 method of curing it, which is praftifed by fome farmers author, and we truft may prove ufeful. Speaking ftill 
 in the p;ui(]i of Udney, in the county of Aberdeen, of the county of Aberdeen, he fays, " The pernicious 
 and gives to their butter a great fuperiority above that praftice of keeping milk in leaden veflels, and faking 
 of their neighbours. butter in ftone jars, begins to gain ground among fome 
 
 Take two parts of the beft common fait, one part of of the fine ladies in this county, as well as elfewhere, 
 A'gar, and one part of faltpetre; beat them up together, from an idea of cleanhnefs. The faft is, it is ju-ft the 
 and blend the whole completely. Tak'e one ounce of reverfe of cleanlinefs ; for in the hands of a careful per- 
 
 fon nothing can be more cleanly than wooden difhes, 
 but under the management of a flattern they difcover 
 the fecret which ftone diftcs indeed do not. 
 
 " In return, thefe latter communicate to the butter 
 and the milk, which has been kept in them, a poifon- 
 ous quality, which inevitably proves deftruflive to the 
 human conftitution. To the prevalence of this prac- 
 tice I have no doubt we muft attribute the frequency 
 of palfies, which begin to prevail fo much in this king- 
 
 this compofition for every 16 ounces of butter, work it 
 ■well into the mafs, and clofe it up for ufe. 
 
 Dr James Anderfon, from whofe View of the Agri- 
 culture of the County of Aberdeen this receipt is taken, 
 fays, that he knows of no fimple improvement in eco- 
 nomics greater than this is, when compared with the 
 iifual mode of curing butter by means of common fait 
 alone. " I have feen (continues he) the experiment 
 fairly made, of one part of the butter made at one time 
 
 being thus cured, and the other part cured with fait dom ; for the well known effeft of the poifon of lead is 
 alone : the difference was inconceivable. I fliould fup- bodily debility, paify — death !" 
 
 pofe that, in any open market, the one would fell for BYSAK, the firlt month of the Bengal year, begia- 
 ^7,0 per cent, more than the other. The butter cured ning in April. 
 
 c. 
 
 Caffcs. OAFFRES, the inhabitants of Caffraria, are gene- 
 ^ *-^ rally confounded with the Hottentots ; but, ac- 
 
 cording to M. Vaillant, there is a confiderable dift'e- 
 rence between the manners, cuftoms, and even appear- 
 ance of thefe two nations. 
 
 The Caffres, fays he, are generally taller than the 
 Hottentots, more robuft, more fierce, and much bolder. 
 Their figure ris likewife more agreeable, and their coun- 
 tenances have not that narrownefs at the bottom, nor 
 their cheeks thofe prominences, which are fo difagree- 
 able among the Hottentots. A round figure, a nofe 
 not too flat, a broad forehead, and large eyes, give them 
 an open and lively air ; and if prejudice can overlook 
 the colour of the fkin, there are fome Caffre women 
 who, even in Europe, wouM be accounted pretty. 
 Thefe people do not make their faces ridiculous, by pul- 
 ling out their eye brows like the Hottentots; they tat- 
 too themfelves much,, and particularly their bodies ; 
 
 their hair, which is frizzled very much, is never greafed, 
 but their bodies are liberally anointed, merely with a ,, 
 view to preferve their vigour and agility. 
 
 The men generally beftow more attention on their 
 drefs than the women, and are remarkably fond of beads 
 and copper rings. The women wear hardly any of the 
 ornaments in which the other favages in Africa take 
 fuch delight. They do not even wear copper brace- 
 lets ; but their fmall aprons, which are ilill (horter than 
 thofe of the Hottentots, are bordered with a few rows 
 of glafs beads ; and in this all their luxury confifts. It 
 would appear that the Caffres are not fo chafte as the 
 Hottentots, becaufe the men do not ufe a jackal to vail 
 what nature teaches other men, even favages, to con- 
 ceal. A fmall cowl, which covers only the glans, in- 
 ftead of difplaying modefty, feems to announce the 
 greateft indecency. This fmall covering adheres to a 
 thoug, which is fafteiied round their girdles, merely 
 
 that 
 
 Caffres
 
 C A F [ 
 
 that it may not be loft; for a Caffre, if he be not afraid 
 ■• of being hurt or ilung by infefts, cares very little whe- 
 ther his cowl be in its place or not. Our author faw 
 one Caffre who, Inftead of a cowl, wore a cafe made of 
 wood, and ornamented with fculpture. This was a new 
 and ridiculous fafliion, which he had borrowed from a 
 nation of black people who lived at a great diftance 
 from Caffraria. 
 
 In the hot feafon the CafFres go always naked, and 
 retain nothing but their ornaments. In cold weather 
 they wear kroITes made of calves or oxen hides, which 
 reach down to the ground ; but whatever the weather 
 he, both fcxes go bare-headed, except that they fome- 
 times, though rarely, fix a plume of feathers in their 
 hair. 
 
 The Caffre huts are more fpacious and higher than 
 thofe of the Hgttentots, and have alio a more regular 
 form. The frames of them are conftrufted of wooden 
 work, well put together, and very fohd, being intend- 
 ed to lail for a long time: for the Caffres, applying to 
 agriculture, which the free Hottentots do not, remain 
 fixed to one fpot, unlefs fomething unexpedled inter- 
 rupt their repofe. 
 
 A more perceptible induftr)', an acquaintance with 
 fome of the moft necelfary arts of life, a little know- 
 ledge of agriculture, and a few religious dogmas, feem 
 to announce that the Caffies approach much nearer to 
 civilization than the Hottentots. They entertain a to- 
 lerably exalted idea of the Supreme Being and his 
 power ; they believe that the good will be rewarded, 
 and the wicked punillied, in a future Hate ; but they 
 have no notion of creation, which indeed was not ad- 
 mitted by the fages of Greece and Rome. They prac- 
 tife circumcilion, but can give na account of its origin 
 among them, or of the purpofe for which the practice is 
 continued. 
 
 Polygamy is ufed among the Caffres ; and on the 
 death of a father the male children and their mothers 
 fhare the fucceffion among them. The girls remain 
 with their mothers without property of anv kind until 
 they can procure hufbands. One very fingulnr cultom 
 of the Calfres is, that they do not, in general, inter 
 their dead, but tranfport them from the krail to an 
 open ditch, which is common to the whole horde. At 
 this ditch favage animals feed at their leifure on the 
 multitude of carcafes which are heaped together. Fu- 
 neral honours are due only to kings and the chiefs of 
 each horde, whole bodies are covered with a heap of 
 flones collefted into the form of a dome. 
 
 This nation is governed by a general, chief, or king, 
 whofe power is very limited. He appoints, however, 
 the fubordinate chiefs over the different hordes, and 
 through them communicates his direftions or orders. 
 The arms of the Caffre are a cluli, two feet and a half in 
 length, and w here thickeft three inches in diameter, and 
 a plain lance or ajjagey. He defpifes poifoned arrows, 
 which are fo much ufed by fome of the neighbouring 
 nations ; and with his two fimple weapons feeks always 
 to meet his enemy face to face in the field. The Hot- 
 tentot, on the contrary, concealed under a rock or be- 
 hmd a bufh, deals out deftruftion, without being expo- 
 fed to danger. The one is a perfidious tyger, which 
 rufhcs treacheroufly on his prey; the other is a gene- 
 rous lion, which, having given warning of his approach, 
 
 149 ] C A L 
 
 makes his attack boldly, and peridies if he prevail not Culctlus. 
 againfl his antagouill. « 
 
 CALCULUS, in mathematics, denotes a certain 
 way of performing inveftigations and refolutions, which 
 occur on many occalions, particularly in mechanical phi- 
 lofophy. Thus we fay, the anteci/lental calculus, the 
 algebraical calculus, the arilhmetical calculus, the diffi- 
 renlial calculus, the exponenlial calculus, the Jluxioiml 
 calculus, and the integral calculus. Of by much the 
 greater part of theie cakuli fome account has been given 
 in the Encyclopaedia Britannicd ; but there is one of 
 them, of which no notice has been taken in that work. 
 It is, 
 
 The Anteccdental Calculus, a geometrical method of 
 reafoning, without any confideration of motion or ve- 
 locity, applicable to every purpofe to which the mucli 
 celebrated doflrine of fluxions of the illuftrious Newton 
 has been, or can be, applied. This method was in- 
 vented by James Glenie, Efq; " in which (he fays) 
 every exprellion is truly and ftridtly geometrical, i.j 
 founded on principles frequently made ufe of by the 
 ancient geometers, principles admitted into the very firll 
 elements of geometry, and repeatedly ufed by Euclid 
 himfelf. As it is a branch of general geometrical pro- 
 portion, or univerfal comparifon, and is derived from an 
 examination of the antecedents of ratios, having given 
 confequents and a given flandard of comparifon in ths 
 various degrees of augmentation and diminution they 
 undergo by compofition and decompofition, 1 have call- 
 ed it the antecedental calculus. As it is purely geo- 
 metrical, and perfeftly fcientilic, I have, llnce it iiril 
 occurred to me in 1779, always made ufe of it inltead 
 of the fluxionary and difl'erential calculi, v.'hich arc 
 inerely arithmetical. Its principles are totally uncon- 
 nec'fed with the ideas of motion and time, which, Itric'b 
 ly fpeaking, are foreign to pure geometry and -^ibftratt 
 fciencc, though, in mixed mathematics and natural plif- 
 Infophy, they are equally applicable to every invelbga- 
 tion, involving the confideration of cither v/ith the tv\.-> 
 numerical methods juil mentioned. And as many iutii 
 inveftigations require compoiitions and decompoiitions 
 of ratios, extending greatly beyond the triplicate and 
 fubtriplicate, this calculus in all ofthern f.irniihes every 
 exprellion in a ftrictly geometrical form. The ilan- 
 dards of comparifon in it may be any magnitudes what- 
 ever, and are of courfe indefinite and innumerable ; and 
 the confequents of the ratios, compounded or decoiii- 
 pounded, may be either equal or unequal, homogentous 
 or heterogeneous. In the fluxionary and difi'ereiuii-.l 
 methods, on the other hand, i, or unit, is not only the 
 flandard of comparifon, but alfo the confequent of cit- 
 ry ratio compounded or decompounded." 
 
 This method is deduced immediately from Mr Gie- 
 nie's Treatife on the Doiitrine of Univerfal Comparifon 
 or General Proportion : And as the limits of the pre- 
 fent work will not allow us to enter upon this fubiect, 
 we therefore refer our readers to the two above men- 
 tioned treatifes, and to the fourth volume of the Tranf- 
 aflions of the Royal Society of Edinburgh. 
 
 We confefs, however, that we do not expeift fncfi 
 great advantage from the employment of tills calculus 
 as the very acute and ingenious author feems to promlfc 
 from ft. The mathematical world is truly indebted to 
 him for the clear and dil'criminating view th:,t he lips 
 
 take a
 
 C A L 
 
 [ >5o 3 
 
 C A L 
 
 Ciltulu5. taken of the dodlrine of univerfal comparifon, and we 
 *" "V believe it to be perfectly accurate, and in fome refpefts 
 
 new. Notwithftanding the continual occupation of ma- 
 thematicians with ratios and analogies, their particular 
 objefts commonly reftricted their manner of conceiving 
 ratio to fome prefent modification of it. Hence it feems 
 to have happened that their conceptions of it as a mag- 
 nitude have not been uniform. But Mr Glenie, by 
 avoiding every peculiarity, has at once attributed to it 
 all the rr.eafurable affeiflions of magnitude, addition or 
 fubtraftion, multiplication or divifion, and ratio or pro- 
 portion. He is perhaps the firll who has roundly con- 
 fidered ratio or proportion as an affedlion of ratio ; 
 and it is chiefly by the employment of this undoubted 
 affeftion of ratio that he has rendered the geometrical 
 analyfis fo comprehenfive. 
 
 But when we view this antecedental calculus, not as 
 a method of exprefPuig mathematical fcience, but as an 
 art, as a calculus in (hort, and confider the means which 
 it muft. employ, and the notation which mull be ufed, 
 ■we become lefs fangnine in our hopes of advantage from 
 it. The notation cannot (we think) be more fimple 
 than that of the fiuxionary method, juftly called arith- 
 metical ; and if we infill on carrying clear conceptions 
 along with us, we imagine that the arithmetical expoii- 
 tion of our fymbols will generally be the fimpler of the 
 two. T\k fcience of the antecedental calculus feems to 
 confifl in the attainable perception of all the fimple ra- 
 tios, whether of magnitudes or ratios, or both, which 
 concur to the formation of a compound and complica- 
 ted ratio. Now this is equally, and more eafily attain, 
 able in the fiuxionary or other arithmetical method, 
 when the confcquent is a fimple magnitude. When it is 
 not, the fame proccfs is farther neceflai-y in both me- 
 thods, for getting rid of its complication. 
 
 We apprehend that it is a miftake that the geome- 
 trical method is more abfirafled than the fiuxionary, 
 becaufe the latter fuperadds to the notion of cxtenfion 
 the notions of time and motion. Thcfe notions were 
 introduced by the illuftrious inventor for the demonjlra- 
 tion, but never occupy the thoughts in the ufe ot his 
 propofitions. Thefe are geometrical truths, no matter 
 how demonllrated ; and when duly confidercd, involve 
 nothing tliat is omitted in the antecedental calculus. 
 We even prefuine to fay, that the complication of 
 thought, in the contemplation of the ratios of ratios, is 
 greater than what will generally arife from the addi- 
 tional elements, time and motion. 
 
 We do not find that any of our mod aftive mathe- 
 maticians have availed themfelves of the advantages of 
 this calculus, nor do we know any fpecimen that has 
 been exhibited of its eminent advantages in mathemati- 
 cal difculfions. Should it prove more fertile in geome- 
 trical exprelhons of highly compounded or complicated 
 quantities or relations, we fliould think it a mighty ac- 
 quifition ; being fully convinced that thefe afford to the 
 memory or imagination an obje£l (we may call it a fen- 
 fible pidture) which it can contemplate and remember 
 with incomparably greater clearnefs and fteadinefs than 
 any algebraical formula. , We need only appeal to the 
 geometrical expreflions of many fluents, which are to 
 be feen in Newton's lunar theory, in the phyfical trafts 
 of Dr Matthew Stewart, and others .who have {hewn a 
 partiality for this method. 
 
 It would be very prefumptuous, however, for us to 
 
 fay, that the accurate geometer and metaphyficlan may Calendar 
 not derive great advantages from profecuting the very j{ 
 ingenious and recondite ipcculations of Mr Glenie, in ' j 
 
 his doftrine of univerfal comparifon. 
 
 CALENDAR, in chronology. See (Encycl.) Ka- 
 LENDAR ; and Revolution, n° 1S4. 
 
 CALIPPIC PERIOD, in chronology, a period of 76 
 years, cv'ntinually recurring ; at every repetition of 
 which, it was fuppofed by its inventor Calippus, an A- 
 thenian ailronomer, that the mean and new full moons 
 would always return to the fame day and hour. 
 
 About a century before, the golden number, or cy- 
 cle of 19 years, had been invented by Meton ; which 
 Calippus finding to contain 19 of Nabonaffar's year, 
 4 days, and \\\, to avoid fraftions he quadrupled it, 
 and io produced his period of 76 years, or 4 times 19 ; 
 after which he fuppoied all the lunations, &c. would re- 
 gularly return to the fame hour. But neither is this 
 exaft, as it brings them too late by a whole day in 225 
 years. 
 
 CALLAO, as it is called by its inhabitants, but 
 more generally known to Europeans under the name of 
 Campello, is a fmall ifland, which was vifited by fome 
 of Lord Macartney's fuite on their voyage to Ch';ia. 
 In confequence of that vifit, we have the following de« 
 fcription of it in Sir George Staunton's Account of 
 the Embafly. 
 
 " It lies oppofite to, and about eight miles to the 
 eaftward of, the mouth of a confiderable river on the 
 coaft of Cochin-china, on the banks of which is fituated 
 the town of Fai-foo, a place of fome note, not far from 
 the harbour of Turon. The bearing of the higheft 
 peak of Callao from this harbour is about fouth eaft, 
 diftance thirty miles. The extreme points of the ifland 
 lie in latitude i 1;° J3', and i 1;" 57' nortli ; the greatell 
 Icnnrth is from north-weft to fouth-eail, and is fomewhat 
 about five miles, and the mean breadth two miles. The 
 only inhabited part is on the fouth-weft coaft, on a flip 
 of ground riling gently to the eaft, and contained be- 
 tween the bottom of a femilunar bay and the mountains 
 on each fide of it. Thofe mountains, at a diftance, ap- 
 pear as if they formed two diftinft iflands. The fouth- 
 ern mountain is the higheft, and is about 1500 feet. 
 The lower grounds contain about 200 acres. This 
 fmall but enchanting fpot is beautifully diverfified with 
 neat houfes, temples, clumps of trees, fmall hillocks 
 fwelling from the plain, and richly decorated with 
 flirubbery and trees of varioi'S kinds ; among which the 
 elegant arecn, rifing like a Corinthian column, is emi- 
 nently confpicuous. A rill of clear water, oozing from 
 the mountains, is contrived to be carried along the up- 
 per ridges of the v:de, from whence it is occafionally 
 conveyed through fluices, for the purpofe of watering the 
 rice grounds, and appeared, though then in the dry fca- 
 fon, fully iufficient for every jiurpofe for which it could 
 be wanted. 
 
 " The houfes, in general, were clean and decent ; a 
 few were built with ftone, and covered with tiles. One, 
 probably the manfion of the chief perlon of the ifland, 
 was enclofed by a ftone wall, and the appoach to it 
 was through a gateway between two ftone pillars. The 
 houfe was divided into a number of apartments, of 
 which the arrangement did not feeni to want cither 
 tafte or convenience. This building ftood at the head 
 of the principal village, which confifted of about thirty 
 
 habitations
 
 C A L 
 
 [ >5 
 
 Callao. habitations built of wood, chiefly the bamboo. Behind 
 •—v^~ the village, and on the fide of the hill, was a cave, ac- 
 ceflible only by one way, through an irregular range of 
 rocks. Within the cave, but near its mouth, was a 
 fmall temple, commanding a view of the whole vale. 
 Several other temples were difperfed over the plain, all 
 of which were open in front, with a colonnade before 
 them of round wooden pillars, painted red and varnilh- 
 ed. The number of houfes on the iiland fcarctly ex- 
 ceeded fixty. Behind every houfe, not immediately in 
 the principal village, were enclofures of fugar-cancs, to- 
 bacco, and other vegetables, growing in great luxuri- 
 ance. The mountains were covered with verdure, and 
 feemed well calculated for rearing goats, of wiiich the 
 jlland produced a few. 
 
 " Befide the principal bay, there were feveral fandy 
 inlets, with fmall patches of levc) ground behind them. 
 Boats might eafily land in any of thefe inlets ; but a 
 communication between them by land appeared to be 
 exceedingly difficult, if not entirely prevented, by the 
 ileep and rugged ridges which feparated them from each 
 other. On this account very fiight works, and an e- 
 ftablifliment of a few men only, would be requifite for 
 the defence of the idand, a great part of its coaft being 
 impregnably fortitied by nature. The depth of water 
 in the bay and road was fufficient for (hips of any bur- 
 den, and there was perfeft ihelter from every wind ex- 
 cept the fouth-weft, to which quarter it was dired^ly 
 open. The (hort diftance, however, from the conti- 
 nent in that direftion would always prevent the fea from 
 rifing high, though it might not be fufficiently near to 
 break the force of the wind." 
 
 The inhabitants of this idand are fo exceedingly fhy 
 and afraid of ftrangers, that upon the approach of the 
 Englifh veffel, they all, except a very few, retired on 
 boai-d their galleys. When the Britifli landed, therefore, 
 they found the doors of all the houfes open, with feveral 
 domeftic animals feeding before them, but neither man, 
 woman, nor child within. After fome time, however, 
 a perfon was perceived lurking among the neighbour- 
 ing trees, who, finding he was obferved, came forward 
 iffith reluftance and evident marks of fear. While he 
 was yet at fome diftance, he fell upon his knees, and 
 touched the ground with his forehead feveral limes. On 
 approaching to him, it was noticed that the firft joint 
 ct every one of his fingers and toes was wanting, and 
 as if twilled off by violence : it was poflible that he 
 might have thus been treated byway of punilhment for 
 fome crime, and that he was confidered as the fitted 
 perfon to be expofcd to the fuppofed danger of watch- 
 ing the movements of the ftrangers coming afliore. In 
 a little time fome others, hidden in the thickets, find- 
 ing that no mifchief was fuffered by the firft, ventured 
 out. None of them could underftand the Chinefe inter- 
 preter ; and net being able to read or write, there was 
 no converfing with them by the medium of the Chinefe 
 charafters. _ Recourfe was had to hieroglyphics, and 
 lude figures were drawn of the articles which were pro- 
 pofed to be purchafed ; and this method fucceeded to- 
 lerably well ; poultry and fruits were brought for fale, 
 for which high prices were given,, purpofely to conci- 
 liate the good will of thofe iflanders. The few that 
 were found grew foon familiar ; and one old man pref- 
 fingly invited the ftrangers to his houfe, fituated upon 
 an eminence, at a little diftance. On arriving there, 
 
 I 1 CAM 
 
 he introduced them to his wife, an old woman, who, 
 after recovering from her aftonilhmcnt at the fight of 
 figures fu different from thofe (he had ever been aecuf- 
 tomed to behold, laid, in a ne.it manner, before them 
 fome fruits, fugar, cakes, and water. On departing 
 from the houfe, tliij decent and hol'pitable couple made 
 figns to teftity their defire of feeing ihem again." 
 
 The poflVlTion of this iiland would b^ of fuch im- 
 portance to any European nation who wifhed to trade 
 fecurely wltli Tungquin and Coch in chis.a, that it is 
 faid the French had formerly fc'me thoughts of purcha- 
 ling it. Sir George Staunton, hoivever, li of opinion, 
 that the want of (hclterin the fouth-well monfoon would 
 render it of little value, v.ithout a further fettlement 
 near it upon the main land of Cochin-china : and he 
 thinks, that if a folld eftablifliment there could be pro- 
 ducfive of advantage to any European nation, it would 
 necefiarily be fo to Great Britain ; becaufe, befide the 
 opening which it would make for the fale of Britifti 
 manufaftures among the people of the country, the Bri- 
 tifli pofTcfiions in Kindoftan would be fure of a very 
 conliderable demand for tlieir produftions. 
 
 CAMEL, in navigation, is a machine which has 
 been defcribed with fufficient accuracy in the Encyclo- 
 pvEdia ; but the following account of its invention, given 
 by ProfeiTor Beckmann, is perhaps not unworthy of a 
 place in this Supplement. 
 
 " In the Zuydei-Zee, oppofite to the mouth of the 
 river Y, about fix miles from the city of Amfterdam, 
 there are two fand banks, between which is z palfage 
 called the Pampus, which is fufficiently deep for fmall 
 fhips, but not for fuch as are large or heavy laden. In 
 1672 the Dutch contrived, however, to carry their nu- 
 merous fleet through this paflage, by means of large 
 empty chefts faftencd to the bottom of each fliip ; and 
 this contrivance gave rife to the invention of the camtl." 
 In the Encyelopa:dia Britannica its invention is given 
 to the famous De Wit ; in the Germ:m Cyclopaedia to 
 Meyer a Dutch engineer of very confidcrable eminence; 
 but the Dutch writers, almnft unaiiiniouily, afcribe the 
 invention of the camel to a citi/en of Amfterdam, who 
 calls himfelf Meeuves Meindertfoon Bakker. " Some 
 make the year of the invention to have been 16S8, and 
 others 1690. Much has been faid of the utility of this 
 invention ; but however beneficial it may be, we have 
 reafon to fuppofe that fuch heavy vefTcls as fliips of war 
 cannot be railed up, in fo violent a manner, without fuf- 
 taining injury. A fure proof of this is the well known 
 circumftance mentioned by Mufchenbroek ( InlrodnS'w 
 ad Philnfopb. Nalur.J, that the ports of a Ihip which 
 had been railed by the camel could not afterv\ards be 
 fhut clofcly." 
 
 CAMELEON, one of the conilellations of the 
 fouthern hemifphere, near the fouth pole, and invifiblc 
 in our latitude. There are 10 liars marked in this con- 
 ftellation in Sharp's catalogue. 
 
 CAMELOPARDALUS, a new conftellation of 
 the northern hemifphere, formed by Hevelius, confift- 
 ing of 32 ftars, firft obferved by him. It is fituated 
 between Cepheus, Caffiopeia, Perfeus, the Two Bears, 
 and Draco; and it contains 58 ftars in the Britifti ca- 
 talogue. 
 
 CAMELLIA, in botany (fee EncycL), is a plant 
 which the Chinefe call Cha-iuha, or flower of tea, on 
 account of the refemblance of the one to the other, and 
 
 becaufe
 
 GAM 
 
 [ 152 ] 
 
 CAM 
 
 0.'.m|.!'ell. hecaufe its petals are fometimes mixed among the teas 
 ' v-~— to increnfe tlicir fragrance. Sir George Staunton, who 
 calls it Cc.infiiia Sefanqua, faw it flonrilhing on the fides 
 and very high tops of moinitaius, where the foil con- 
 filled of little mare than fragments of (lone, crumbled in- 
 to a fort of coarfe earth by the joint aftion of the fun and 
 rain. It yields, he fays, a nut, from which is exprtlfed 
 an ifculent o::, equal to tiie bell which conies from Flo- 
 rence. On this account, it is cultivated in vafl abun- 
 dance ; and is particularly valuable from the facility of 
 itr. culture in fit nations fit for little elfe. 
 
 CAMPiyLLL (George, D. D.), fo juftly admired 
 for his metaphy Ileal acutenefs and various erudition, was, 
 in I 7 19, born at Aberdeen, where his father, the reve- 
 rend Colin Campbell, was one of the minifters of the 
 cftabliflied church. He was educated in his native city ; 
 and, after paffirg through the ufual courfe of acade- 
 mical learning, he lludicd divinity under the Rev. J. 
 ■CJialmers, profeflbr of divinity in Marifehal College. — 
 He was, in 1749, an unfuccefsful candidate for the 
 thurch of Fordown, though his competitor Mr For- 
 bes was a man of very flender abilities, and fuppofed to 
 he attached to the conftitution and liturgy of the church 
 of England. It might indeed be that attachment which 
 contributed principally to procure him the living in pre- 
 ference to Mr Campbell. 
 
 The living of Fordown is in the gift of the crown ; 
 and it has generally been a rule with his majetty's mi- 
 uillers, to give fuch livings, when they become vacant, 
 10 thofe candidates who are favoured by the majority 
 of land-owners in the parilh. At the era of 1745, the 
 land-owners in feme of the northern and middle coun- 
 lies of Scotland were more generally attached to the 
 conllitutiou of the church of England than to that of 
 their own eftabliihment ; and fuch was certainly the caie 
 in the parifli of Fordown. 
 
 But whatever was the caufe of Mr Campbell's failure, 
 he failed by a very fmall number, and was not long 
 without an eftabliihment. In 1750, he was prefented, 
 by Sir Thomas Burnet of Leys, to the living of Ban- 
 chary Ternan, on the Dee, about twenty miles weft 
 from Aberdeen. From this he was tranilated, or, as 
 the Scotch ecclefiattical phrafe is, tranj'porled to Aber- 
 deen in 1756, and nominated one ot the city minifters, 
 iiY the room of Mr John Biffet deceafed, a puritan of 
 the old fchool, whole ftriftnefs and peculiarities are yet 
 lemembered by many in that place. 
 
 In 1759, oil the deceafe of principal pollock, he was 
 chofen principal of the Marilchal college, and fucceeded 
 to the divinity chair in 1771, on Dr Alexander Ge- 
 rard being tranflated to the profefforlliip of divinity in 
 King's college. Before his fettling in Aberdeen, he 
 stianied Mils Grace Farquhavfon, daughter of Mr Far- 
 quharfon of Whitehoule, by whom he had no ifl'ue. 
 This amiable woman died about a year before him. 
 They were an eminent pattern of conjugal affeftion. 
 
 From this time he enjoyed a remarkable fliare of 
 good health and Iplrits. He had, all his life, a rooted 
 ■averfion to medicine. He got tiie better of every ail- 
 ment by a total and rigorous abltlnence Irom all kind of 
 fuftenanee whatever ; and it was not till lie was attacked 
 by an alarming illnefs, about two years before his death, 
 that he was ptrfuaded by his friends to call in medical 
 iiid. What nature could do, (he had all along performed 
 -\vcll ; but her day was over, and fomethiug of art be- 
 
 came neceflary. Then, for the firft time, he owned Campbell 
 the utility of medical men, and declared his recantation ~^~v~~' 
 of the very mean opinion he had formerly entertained 
 of them and their art. A few months before his death, 
 he religned his offices of principal, profefi'or of divinity, 
 and one oi the city minifters, and was in all fucceeded 
 by Dr W. L. Brown, late of Utrecht, a man of dif- 
 tinguillied abilities. Dr Campbell retained all his fa- 
 culties entire to the laft, and died on the 6th of April 
 1796, in the 77th year of his age. His charadler has 
 been fo juftly drawn by his luccefTor, that we fhall give 
 it to our readers in his words, adding only a circum- 
 ftance or two, which we have reafon to think will con- 
 tribute to endear his memory to every liberal and en- 
 lightened mind. 
 
 " Dr Campbell, as a public teacher, was long ad- 
 mired for the clearne's and copioulncfs with which he 
 illullrated the great doftrines and precepts of religion, 
 and the ftrength and energy with which he enforced 
 them. Intimately perfuaded of the truth and infinite 
 conlequence of what relevation teaches, he was ftrong- 
 ly delirous of carrying theiame conviction to the minds 
 of his hearers, and delivered his difcourfes with that 
 zeal which flows from ftrong impreffions, and that 
 power of perfualion which is the refult of fincerity of 
 heart, combined with clearnefs of underllanding. He 
 was fatisfied, that the more the pure diftates of the' 
 gofpel were ftudied, the more they would approve 
 themfelves to the mind, and bring forth, in the affec- 
 tions and condudl, all the peaceable fruits of righteouf- 
 nefs. The unadulterated dictates of Chriftianity, he 
 was, therefore, only lludious to recommend and in- 
 culcate, and knew perfectly to difcriminate them from 
 the inventions and traditions of men. His chief ftudy 
 ever was, to direft belief to the great objefts of praftice ; 
 and, without thefe, he viewed the moll orthodox pro- 
 feflion as " a founding brafs, and a tinkling cymbal." 
 But, befides the charadler of a preacher of righteouf- 
 nefs, he had alfo that of a teacher of the fcience of di- 
 vinity to fullaln. How admirably he difcfiarged this 
 duty, and with what effeCl he conveyed the foundeft 
 and moft profitable inftruClion to the minds of his fcho- 
 lars, let thofe declare who are now in various congre- 
 gations of this country, communicating to their fellow 
 Chriftians the fruits of their ftudies under fo able and 
 judicious a teacher. Dilcarding all attachment to hu- 
 man fyftems, merely confidered as fuch, he tied his faith 
 to the Word of God alone, poffefted the happieft ta- 
 lent in inveftigating its meaning, and communicated to 
 his hearers the refult of his own inquiries, with a pre- 
 cifion and perfpicuity which brought light out of ob- 
 fcurity, iiud rendered clear and fimple what appeared 
 intricate and perplexed. He expofed, without referve, 
 the corruptions which ignorance, cratt, and hypocrify, 
 had introduced into religion, and applied his talent for 
 ridicule to the bell of all purpofes, to hold up to con- 
 tempt the abfurdities with which the pureft and fub- 
 limell truths had been loaded. 
 
 " Placed at the head of a public feminary of learn- 
 ing, he felt all the importance of fuch a fituation, and 
 uniformly directed his influence to public utility. His 
 enlarged and enlightened mind juftly appreciated the 
 extenfive confequence of the education of youth. He 
 anticipated all the eft'etts refulting to the great commu- 
 nity of mankind, from numbers of young men iffuing, 
 
 ir\
 
 CAM 
 
 [ 
 
 Campliell. in regular fucceflion, from the univerfity over wliich he 
 "■■"v— prcfidcd, and occupying the different departments of 
 facial life. 
 
 " His benevolent heart delighted to reprefent to it- 
 felf the ftudents under his diredlion ufefully and ho- 
 nourably difcharging the refpeftive duties of their dif- 
 ferent profeffions ; and fome of them, perhaps, filling 
 the mod dillinguillied ftations of civil fociety. With 
 thefe profpeds before him, he conilantly diredted his 
 public conduA to their attainment. He never fuffered 
 his judgment to be warped by prejudice or partiality, 
 or his heart to be feduced by paffion or private intereit. 
 Thofe mean and ignoble motives by which many are 
 aftuated in the difcharge of important trulls, approach- 
 ed not his mind. A certain honourable pride, if pride 
 it may be called, diffufed an uniform dignity over the 
 whole of his behaviour. He felt the man degraded 
 by the perverfion of public charafter. His underftand- 
 ing alfo clearly fhewed him even perfonal advantage at- 
 tached to fuch principles and praftice, as he adopted 
 from a fenfe of obligation, and thofe elevated concep- 
 tions of real worth which were fo congenial to his foul. 
 He faw, he experienced, efteem, refpeft, and influence, 
 following in the train of integrity and beneficence ; but 
 contempt, difgrace, averfion,and complete infignificance, 
 clofely linked to corruption and felfifhuefs. Little minds 
 are feduced and overpowered by felfilh confiderations, 
 becaufe they have not the capacity to look beyond the 
 prefcnt advantage, and to extend to the mifery that 
 ftands on the other fide of it. The fame circumftance 
 that betrays the perverfity of their hearts, alfo evinces 
 the weaknefs of their judgments. 
 
 " His reputation as a writer is as extenfive as the 
 prefent intercourfe of letters ; not confined to his own 
 country, but fpread through every civilized nation. In 
 his literary purfuits, he aimed not, as is very often the 
 cafe, with men of diftinguiflied literary abilities, merely 
 at eftabliihing his own celebrity, or increafing his for- 
 tune ; but had chiefly at heart the defence of the great 
 caufe of Religion, or tlie elucidation of her dilates. 
 
 " At an early period he entered the lifts as a cham- 
 pion for Chriftianity againll one of its acuteft oppo- 
 nents. He not only triumphantly refuted his argu- 
 ments, but even conciliated his refpeft by the handfome 
 and dexterous manner in which his defence was conduc- 
 ed. While he refuted the infidel, he fpared the man, 
 and exhibited the uncommon fpedlacle of a polemical 
 ■writer poireiTmg all the moderation of a Chriftian. But 
 while he defended Chriftianity againft its enemies, he 
 was defnous of contributing his endeavours to increafe, 
 among its profefTors, the knowledge of the facred wri- 
 tings. Accordingly, in the latter part of his life, he 
 favoured the world with a work, the fruit of copious 
 erudition, of unwearied application, for almoft thirty 
 years, and of a clear and comprehenfive judgment. We 
 have only to regret, that the other writings of the 
 New Teftament have not been elucidated by the fame 
 pen that tranflated the Gofpels. Nor were his literary 
 merits confined to theology, and the ftudies more im- 
 mediately connected with it. Philofophy, and the fine 
 arts, are alfo indebted to his genius and labours ; and 
 in him the polite fcholar was eminently joined to the 
 deep and liberal divine. 
 
 " Pohtica! principles will always be much affefled 
 by general charafter. This was alfo the cafe with Dr 
 SuprL. Vol. I, Part 1. 
 
 153 ] CAM 
 
 Campbell. In politics, he maintained that moderation r.implicU. 
 which is the furcft criterion of truth and reftltude, and '^ — ^^— ' 
 was equally diftant from thofe extremes into which men 
 are fo apt to run on great political queftlons. He che- 
 nflied that patriotifm which confifts in wKhing, and en- 
 deavouring to promote the greateft happinefs of his 
 country, and is always fubordinatc to univerfal benevo- 
 lence. Firmly attached to the Britini conftitutlon, he 
 was anmiated with that genuine love of liberty which 
 it infpires and invigorates. He was equally averfe to 
 defpotifm and to popular anarchy ; the two evils into 
 which political parties are fo frequently hurried, to the 
 dcftruftion of all that is valuable in government. Par. 
 ty-fplrit, of whatever defcription, he coniidered'as ha^ 
 ving an unhappy tendency to pervert, to the moft per- 
 nicious purpofes, the beft principles of the human miiid, 
 and to clothe the moft iniquitous aCions with the moft 
 fpecious appearances. Although tenacious of thofe fen- 
 timents, whether in religion or politics, which he was 
 convinced to be rational and juft, he never fuffered 
 mere difference of opinion to impair his good-will to 
 obftruft his good offices, or to cloud the cheerful'nefs 
 of converfation. His own converfation was enlivened 
 by a vein of the moft agreable pleafantry." 
 
 So far was he from being influenced by jealoufy, or 
 any portion of that corporation-fpirit which fometimes 
 incites men of undoubted abilities to detraft from the 
 merit of every writer who fills not a ftation as confpi- 
 cuous as their own, that he was loud in his praifes of 
 thofe, whom men of meaner minds would have looked 
 upon with difguft, as upon prefumptuous rivals. This 
 generofity was fully experienced by the writer of the 
 article Miracle, in the Encyclopaedia Britannica, who, 
 though he had prefumed to treat the fubjed differently 
 from Dr Campbell, received from him fuch a teflimony 
 of approbation of what he had done, as he will hnrdly 
 look for from any other man in fimilar circumftances. 
 
 Among his other qualities, which fo much endeared 
 him to all who had the honour of his acquaintance, Dr 
 Campbell poffeffed an uncommon facility of palling from 
 the graveft to the moft airy fubjeds, and from the live- 
 heft to the graveft, without degrading the one or di- 
 minifliing the pleafure of the other. The infirmities of 
 age abated not the cheerfulnefs of his temper, nor did 
 even the perfuafion of approaching diffolution impair 
 his ferenity. 
 
 We cannot conclude this fliort n<etch better than 
 with a lift of his works, in the order in which they 
 were publlftied. In 1752, he publiflied a Sermon 
 preached before the Synod of Aberdeen. ' ' 
 
 1 76 1. A DIflertation on Miracles, againft Mr Hume. 
 This treatife is well known to the learned world. He 
 obtained, and defervedly obtained, a very high reputa- 
 tion, not only from the able manner in which he hand- 
 led the fubjea, but from the liberal ftyle in which he 
 addreffed his antagonift. It was f"peedily tranflated in- 
 to French, German, and Dutch. 
 
 1771. A Sermon before the Society for Proparra- 
 ting Chriftian Knowledge, Edinburgli. 
 
 ;^ before tlfe Synod of Aberdeen. 
 
 1776. The Philofophy of Rhetoric, 2 vols 8vo. A 
 work which difcovers a clearnefs of difccrnment, and 
 accuracy of ohfervation, which juftly entitled him to be 
 ranked among the moft judicious critics. He entered 
 on tins inquiry as early as 1750, when a part of the 
 U work
 
 CAM 
 
 [ '54 ] 
 
 CAN 
 
 Camrhor. work was compofed. The laws of elegant compofition 
 '~~~ir~~'and criticifm are laid down with great perfpicuity : but 
 the moft valuable part of the work h undoubtedly the 
 /heory of cviihnce, to wliich we know nothing fuperior, 
 perhaps nothing equal, on the fubjeft, in our own or any- 
 other language. His philofophy, in genera!, is the plii- 
 lofophy of Dr Reid ; and where he differs from that a- 
 cute reafoner refpeAing alftracVion, and feme other ob' 
 
 CANALS OF CoMMUNicATioM may be of fuch 
 advantage in a commercial or agricultural country, that 
 every attempt to render them more convenient, and lefs 
 cxpenfive in the conftruftion, is intitled to public no- 
 tice. Li the Encyclopedia, an account, fufficient'lv 
 pcrfpicuous, is given of the common canals with locks; 
 but ill many cafes it is very difficult to provide a fuflicietit 
 quantity of water for the eonfumption of a canal where 
 
 Canals 
 
 jedts of metaphysical difqulTition, we think it impoffible many boats are to pafs. Different attempts have there- 
 to refufe him the preeminence in every thing but ilyle. fore been made, by ingenious men, to fave water in the 
 
 palfing of boats or ligbJTvs from one lock of a canal tii 
 
 precmuience \n every tnnig 
 1777. A Sermon on the King's Fail-day, on Alle- 
 giance, firft printed in 410, and afterwards, at the 
 expcnce of government, fix thoufand copies were print- 
 ed in l2mo, enlarged with notes, and fent to Ame- 
 rica, when the unhajipy ftruggle had, however, put on 
 appearances which prevented the effedl hoped for from 
 this fermon. 
 
 1780. An Addrefs to the People of Scotland on 
 the Alarms which have been raifed by what is called 
 the Popifh Bill. This is a powerful diffuafive from bi- 
 gotry, and every fpecics of religious perfecution. 
 
 1795. His Magnum Opus. The tranilation of the 
 Gofpels, with Preliminary Differtations, 2 vols 4to. 
 
 1800. Ledures on Ecclefiaftical Hlllory, a pollhu- 
 mous work, in 2 vols 8vo ; which, in the opinion of 
 moft people, (hould have been luppreffed. 
 
 CAMPHOR, or Camphire, (fee EncycL), is, in 
 China, obtained by boiling the branches, twigs, and 
 leaves, of the Laurvs-Camfhora in water, upon the fur- 
 face of which it is found fwimming in the form of an 
 oil, or adhering, in a glutinous form, to a wooden rod, 
 with which the boiling matter is conftantly ftirred. 
 The glutinous mafs is then mixed with clay and lime, 
 and put into an earthen veffcl, with another of the fame 
 fize properly luted over it ; the lower veffel being placed 
 over a flow fire, the camphor gradually fublimes through 
 the clay and lime, and adiieres to the fides of the upper 
 veflel, forming a cake of a fiiape correfponding to the 
 cavity which received it. It is, however, lefs pure and 
 much weaker than what is difcovered in a folid ftate 
 among the fibres of the trunk, as turpentine is found 
 in different forts of pines. In the great, but ill-peo- 
 pled, ifland of Borneo, and alfo in Japan, the camphor 
 tree is felled for the fole purpofe of finding this coftly 
 drug in fubftance among the fplinters of the trunk, in 
 the fame manner as other trees are felled in Loulfiana 
 merely for collecting the fruit they bear upon their 
 fummits. The Borneo, or Japan camphor, is pure, 
 and fo very ftrong, as readily to communicate much of 
 its odour and its virtues to other infpiffated oils, which 
 thus pafs for real camphor ; and this adulterated drug 
 is fold by Chintfe artifls at a vaftly lower price than 
 they gave themfelves for the genuine fubftance from 
 Borneo or Japan. 
 
 Sir George Staunton, from whom we have this ac- 
 count, does not inform us whether the camphor-tree 
 of China, if felled and torn into fplinters, would not 
 produce as large quantities of the drug, and equally 
 pure, as the trees of Borneo and Japan ; but he affures 
 us, that in China it is never fo torn, being there a large 
 and valuable timber-tree. " It is ufed (fays he) in 
 the beft: buildings of every kind, as vv-ell as for mafts of 
 veffels, and hears too high a price to allow of any part, 
 except the branches, being cut up for the fake of the 
 drug." 
 
 another ; and, among thefe, perhaps none is more de 
 ferving of public favour than the following, by the late 
 Mr James Playfair of Ruffel-ftreet, architeft. We (liall 
 flate his invention in his own woids. 
 
 " The nature and principle of this manner of faving 
 water confift in letting the water which has ferved to 
 raife or fall a boat or barge from the lock, pafs into 
 refervoirs or cifterns, whofe apertures of communication 
 with the lock are upon different levels, and which may 
 be placed or conftrufted at the fide or fides of the lock 
 with which they communicate, or in any other conti- 
 guous fituation that circumllances may render eligible ; 
 which apertures may be opened or fhut at plcaf'^re, fo 
 that the water may pafs from the lock to-.each rcfervoir 
 of the canal, or from each refervoir to the lock, in the 
 following manner : The water which fills the lock, 
 when a boat is to afcend or defcend, inilead of being 
 pafied immediately into the lower part of the canal, is 
 let pafs into thefe cifterns or refervoirs, upon different 
 levels ; then, their communications with the lock being 
 fhut, they remain full until another veffel is wanted to 
 pafs ; then, again, the cifterns are emptied into the 
 lock, which is thereby nearly filled, fo that only the re- 
 malnder which is not filled Is fupplled from the higher 
 part of the canal. Each of thefe cifterns muft have a 
 furface not lefs than that of the lock, and muft con- 
 tain half as much water as is meant to be expended for 
 the paffing of each veffel. The ciftern the moft eleva- 
 ted is placed twice its own depth (meafurlpg by the 
 aperture, or communicating opening of the cifterns) 
 under the level of the water in the higher part of the 
 canal. The iecond ciftern is placed once its own depth 
 under the firft, and fo on are the others to the loweft ; 
 which laft is placed once its own depth above the level 
 of the water in the lower part of the canal. The aper- 
 tures of the Intermediate cifterns, whatever their num. 
 ber may be, muft all be equally divided into different 
 levels ; the furface of the water in the one being al- 
 ways on the level of the bottom of the aperture of the 
 ciftern which is immediately above. As an example 
 of the manner and rule for conftrufting thefe cifterns, 
 fuppofe that a lock is to be conftrutted twelve feet 
 detp, that is, that the veffel may afcend or defcend twelve 
 feet in paffing. Suppofe the lock fixty feet long and 
 fix feet wide, the quantity of water required to fill the 
 lock, and to pafs a boat, is 43 20 cubic feet ; and fup- 
 pofe that, in calculating the quantity of water that can 
 be procured for fupplying the canal, after allowing for 
 wafte, it is found (according to the number of boats 
 that may be expefted to pafs) that there will not be 
 above 800 cubic feet for each ; then it will be necef- 
 fary to fave five-fixths of the whole quantity that in the 
 common cafe would be neceffary : to do which ten cif- 
 terns mull be made (the mode of placing which is ex- 
 
 preffed
 
 CAN [15 
 
 pixffod in the drawing, fig. i. Plate VII.). each of 
 which mud be one foot deep, or deeper at plcafure, 
 and each muil have a fuiface of 360 feet fquare, eqii.d 
 to the fuvface of the lock. The bottom of the aper- 
 ture of the loweft cillcrn muft be placed one foot abuve 
 the level of the water in the lower part of the ciuial, or 
 tlcven feet under the level of the high water; the le- 
 cond ciftern mufl be two feet above the level ol the 
 low water; the third three feet, and fo on of the others ; 
 the bottom of the tenth, or uppermoft cidern, being 
 ten feet above the low water, and two feet lower than 
 the high water ; and, as each cillern muil be twelve 
 inches in depth, the furface of the water in the higher 
 ciftern will be one foot under the level of the water in 
 the upper part of the canal. Tiie cillerns being thus 
 conftrufted, when the lock is full, and the boat to be 
 let down, the communications between the lock and the 
 ciftcrns, which until then have all been fliut, are to be 
 opened in the following manner : firlt, the communica- 
 tion with the higher ciftern is opened, which, being at 
 bottom two feet under the level of the water in the 
 lock, is filled to the depth of one foot, the water in the 
 lock defcending one foot alfo at the fame time ; that 
 communication is then fhut, and the communication be- 
 tween the lock and the fecond ciftern is opened ; one 
 foot more of the water then paftes into that ciftern from 
 the lock, and fills it ; the opening is then ftiut : the 
 fame is done with the third, fourth, fifth, fixth, feventh, 
 eighth, ninth, and tenth, cifterns, one by one, until 
 they are all filled ; and when the tenth, or lowermoft 
 ciftern, is filled, there remains but two feet depth of 
 water in the lock. The communication between the 
 lock and the lower part of the canal is then opened, 
 and the laft two feet depth of water is emptied into the 
 lower part of the canal. By this means, it is evident 
 that, inftead of twelve feet depth of water being let 
 defcend into the lower part of the canal, there is only 
 two feet depth that defcends, or one-fixth of the whole; 
 therefore, inftead of 4320 cubic feet being iifed, there 
 are only 720 cubic feet ufcd: the remainder of the wa- 
 ter in the cifterns being ufcd as follows: Wiien another 
 boat is to mount, the iluices being then ftiut, and ihe 
 boat in the lock, the tenth or loneimoft ciftern is 
 emptied into the lock, which it fills one foot; the com- 
 munication being then fliut, the next loweft ciftern, or 
 the ninth, is emptied into the lock, which is thereby 
 filled another foot ; and fo, in like manner, all the other 
 cifterns are emptied one after another, until the higher 
 ciftern being emptied, which fills the tenth foot of wa- 
 ter in the lock, there remains but two feet of water to 
 fill, which is done from the upper part of the canal by 
 opening the higher flnice to pafs the boat ; by that 
 means, the fame quantity of water defcends from the 
 upper part of the canal into the lock, that in the other 
 cafe defcended from the lock into the lower part of the 
 canal ; fo that, in both cafes, the fame quantity of wa- 
 ter is faved, that is, five-fixths of what would be necef- 
 fary were there no cifterns. Suppofe again that, upon 
 the fame canal, and inunediately after the twelve feet 
 lock, it would be advantageous to conftruA one of 
 eighteen feet ; then, in order not to ufe any greater 
 quantity of water, it will be necefiary to have fixteen 
 cifterns, upon different levels, communicating with the 
 lock in the fame manner. Should, again, a lock of 
 only fix feet be wanted, after that of eighteen, then it 
 
 5 ] CAN 
 
 will only be neceffary to have four ciftcrns on different Caralv 
 levels, and fo of any other height of lock. The rule ~~^ 
 is this: For finding the number and iize of the cifterns, 
 each ciftern being the fame in fuperfieies with the lock, 
 its depth muft be fueh as to contain one half the quau- 
 tity of water meant to be ufcd in the palfing of one 
 boat. The depth of the lock, divided by the depth 
 nccefTary for fnch a ciftern, will ^ive, in all cafi^, the 
 whole number of cifterns, and two more : deduft the 
 number two, therefore, from the number which you 
 find by dividing the depth of the lock by the depth of 
 one ciftern, and you have always the number ot ci- 
 fterns required ; which are to be placed upon difterent 
 levels, according to the rule already given. The above 
 is the principle and manner of ufing the lock, tor fa- 
 ving water in canals, and for enabling engineers to lon- 
 ftrutt locks of different depths upon the fame lanal, 
 without ufing more water for the deep locks than for 
 the ftiallow ones. With regard to the manner of dif- 
 pofing the cifterns, the circumftances of the ground, 
 the declivity, &c. will be the heft guide for the engi- 
 neer." 
 
 But fuppofing a fufficiency of water, or admitting 
 that this method of Mr Playfair's of faving it, where 
 defective, is adequate to his fondelt expeftations, ftdl, 
 in paffing numerous locks, where the rife is confider- 
 able, the interruption is fo great, that it has often been 
 wiflied that' an eligible method of lowering and eleva- 
 ting boats could be devifed, without the affiftance of 
 water-locks. Though this is evidently at firft view prac- 
 ticable, and feveral different modes of doing It have 
 been fuggefted, fome of which have adlually been car- 
 ried into effeft, yet all of them have been found to be 
 attended with fuch inconvenience as to render an im- 
 provement in this refpeCt ftill necefiary. 
 
 In China, where water-carriage is more generally prar- 
 tifed than in any kingdom of Europe, boats are raifed 
 and lowered from one canal into another, by Aiding thein 
 along an inclined plane : but the contrivances for ef- 
 fefting that purpofe are fo awkward, and fuch a num- 
 ber of hands are required, that it has in general been 
 deemed inexpedient to refort to that mode of praftice 
 in Europe. Several devices, that difcover confiderable 
 ingenuity, however, have been publlfhed, with a view 
 to facilitate this operation ; either by rendering the mo- 
 tion up the inclined plane more equable, or ])roducing 
 a power fufficient to move thefe great weights. But 
 none of them have yet been fo fimplc in their conftruc- 
 tion as could be wiihed, nor have they afforded fatisfac- 
 tion in praftice. For the greater part of them, like- 
 wife, patents have been granted ; fo that whatever be 
 their value, no engineer could avail himfelf of them 
 without previoufly purchafing a licence from the pa- 
 tentee. 
 
 The following contrivance for this purpofe is the in- 
 vention of James Anderfon, LL. D. whofe knowledge 
 of economics is well known, and of whofe public fpirit 
 there cannot be a doubt. Inftead of applying for a pa- 
 tent, to fecure to himfelf the fruits of his ingenuity, he 
 publiftied, for the good of his countrymen in general, 
 his device, in the View of the Agriculture of the Coun- 
 ty of Aberdeen, which he drew up for the confidera- 
 tion of the board of agriculture. He introduces it to 
 public notice with juftly obferving, that it pofTeffes at 
 leaft the merit of fimplicity, in as high a degree, per- 
 il a haps,
 
 N [ I 
 
 and, " ill the opinion (fays 
 
 C A 
 
 Canals, haps, as could be wifiifd 
 
 • he) of very good judges of matters of this fort, to 
 whom the plan lias been (hewn, it has been deemed 
 fully adequate to the purpofe of raifing and lowering 
 boats of a moderate fize, that is, of 20 tons, or down- 
 wards ; and it is the opinion of moft men with whom I 
 have converfed, who are beft acquainted with the in- 
 land navigations, that a boat of from 10 to i ^ tons is 
 better than thofe of a larger fize. When feveral are 
 wanted to be lent at once, they may be affixed to one 
 another, as many as the towing-horfe can conveniently 
 draw. Were boats of this fize adopted, and were all 
 tlie boats on one canal to be of tlie fame dimenljons, it 
 would prove a great convenience to a country in a ftate 
 of beginning improvements; becaufe the expence of fuch 
 a boat would be fo trifling, that every farmer could 
 have one for hinifelf, and might of courfe make ufe of 
 it when he plcafed by the aid of his own horfe, without 
 being obliged to have any dependence on the time that 
 might fuit the convenience 'of his neighbour ; and if 
 two or more boats were going from the fame neigh- 
 bourhood, one horfe could ferve the whole. 
 
 " You are to fuppofe that fig. 2. (Plate VII.) repre- 
 fents a bird's-eye view of this fimple apparatus, as feen 
 from above. A is fnppofed to be the upper reach of 
 the canal, and B the lower reach, with the apparatus 
 between the two. This confifts of three divifions ; the 
 nu'ddle one, extending from C to D, is a folid piece of 
 mafonry, raifed from a firm foundation below the level 
 of the bottom of the fecond reach : this is again divi- 
 ded into five parts, viz. ddd, where the wall rifes only 
 to the height of the water in the upper reach, and e e, 
 two pillars, raifed high enough to Aipport the pivots 
 of a wheel or pulley g, placed in the pofition there 
 marked. 
 
 " The fecond divifion h confifts of a wooden coffer, 
 of the fame depth nearly as the water in the upper 
 reach, and of a fize exaftly fitted to contain one of the 
 boats. This communicates direftly with the upper 
 reach, and being upon the fame plane with it, and fo 
 connected with it as to be water-tight, it is evident, 
 from infpeftion, that nothing can be more eafy than to 
 float a boat into this coffer from the upper reach ; the 
 part of the wheel that projeds over it being at a Suffi- 
 cient height above it, fo as to occafion no fort of inter- 
 ruption. 
 
 " Third divifion. At ; is reprefented another cof- 
 fer, precifely of the fame dimenfions with the firil. But 
 here two fluices, which were open in the former, and 
 only reprefented by dotted lines, are fuppofed to be 
 fhut, fo as to cut off all communication between the 
 water in the canal and that in the coffer. As it was 
 impoflible to reprefent this part of the apparatus on fo 
 fmall a fcale, for the fake of illullration it is reprefent- 
 ed more at large in fig. 5. where A, as before, repre- 
 fents the upper reach of the canal, and h one of the 
 coffers. The fluice k goes into two cheeks of wood, 
 joined to the mafonry of the dam of the canal, fo as to 
 fit perfeftly clofe ; and the fluice / fits equally clofe 
 into cheeks made in the fide of the coffer for that pur- 
 pofe ; between thefe two fluices is a fmall fpace 0. 
 The coffer, and this divifion 0, are to be fuppofed full 
 of water, and it will be eafy to fee that thefe ihiices 
 may be let down or drawn up at pleafure with much 
 facility. 
 
 S6 ] CAN 
 
 " Fig. C. reprefents a perpendicular feftion of thefe 
 parts in the fame direiffion as in fig. 5. and in which * 
 the fame letters reprefent the fame parts. 
 
 " Things being thus arranged, you are to fuppofe 
 the coffer h to be fufpended, by means of a chain paffed 
 over the pulley, and balanced by a weight that is fuffi- 
 cient to countcrpoiie it, fufpended at the oppofite end 
 of the chain. Suppofe, then, that the counterpoife be 
 made fomewhat lighter than the coffer with its con- 
 tents, and that the line mn (fig. 6.) reprefents a divi- 
 fion between the folid fides of the dam of feparation, 
 which terminates the upper reach and the wooden cof- 
 fer, which had been clofcd only bv the prelfure of its 
 own weight (being pufhed a very little from A towards 
 B, beyond its precife perpendicular fwing), and that the 
 joining all round is covered with liils of cloth put upon 
 it for that purpofe ; it is evident that, fo long as the 
 coffer is fufpended to this height, the joining muft be 
 water-tight ; but no fooner is it lowered down a little 
 than this joining opens, the water in the fmall divifion 
 is allowed to run out, and an entire feparation is made 
 between the fixed dam and this moveable coffer, which 
 may be lowered down at pleafure without lofing any 
 part of the water it contained. 
 
 " Suppofe the coffer now perfeftly detached, turn 
 to fig. 3. which reprefents a perpendicular feftion of 
 this apparatus, in the direftion of the dotted line /^ 
 (fig. 2.) In fig. 3. h reprefents an end view of the 
 coffer, indicated by the fame letter as in fig. 2. fufpend- 
 ed by Its chain, and now perfedlly detached from all 
 other objefts, and balanced by a counterpoife «, which 
 is another coffer exaSly of the fame fize, as low down 
 as the level of the lower reach. From infpedlion only, 
 it is evident, that in proportion as the one of thefe 
 weights rifes, the other muft defcend. For the pre- 
 fent, then, fuppofe that the coffer h is by fome means 
 rendered more weighty than /', it is plain it will de- 
 fcend while the other rites ; and they will thus conti- 
 nue till h comes down to the level of the lower reach, 
 and / rifes to the level of the higher one. 
 
 " Fig. 4. reprefents a feftlon in the direftion AB 
 (fig. 2.), in which the coffer i (feen in both fituations) 
 is fuppofed to have been gradually raifed from the level 
 of the lower reach B, to that of the higher A, where 
 it now remains ftationary ; while the coffer A (which is 
 concealed behind the mafonry) has defcended in the 
 mean time to the level of the lower reach, where it 
 clofes by means of the junfture r s, fig. 6. (which junc- 
 ture is covered with lifts of cloth, as before explained 
 at m II, and is of courfe become water-tight), when, by 
 lifting the fluice /, and the correfponding fluice at the 
 end of the canal, a perteft communication by water is 
 eftablifhed between them. If, then, inftead of water 
 only, this coffer had contained a boat, floated into it 
 from the upper reach, and then lowered down, it is ve- 
 ry plain that when thefe fluices were removed, after it 
 had reached the level of the lower reach, that boat 
 might have been floated out of the coffer with as much, 
 facility as it was let into it above. Here then we have 
 a boat taken from the higher into the lower canal ; 
 and, by reverfing this movemeat, it is very obvious 
 that it might be, with equal eafe, raifed from the lower 
 into the higher one. It now only remains that I 
 fhould explain by what means the equilibrium between 
 
 thefe
 
 CAN [ 1 
 
 Carals, thefe counterbalancing weiglits can be deftroycd at plca- 
 ""~v fure, and the motion of courfe produced. 
 
 " It is very evident, that if the two corrcfponding 
 coffers be precifely of the fame dimenfions, their weight 
 will be exaftly the fame when they are both filled to 
 the fame depth of water. It is equally plain, that 
 fliould a boat be floated into either or both of them, 
 whatever its dimenfions or weight may be, fo that it 
 can be contained afloat in the coffer, the weight of the 
 coffer and its contents will continue precifely the fame 
 as when it was filled with water only : hence, then, 
 luppoimg one boat is to be lowered, or one to be raifed 
 at a time, or fuppofing one to be raifed and another 
 lowered at the fame time — they remain perfeftly in 
 equilibrium in either place, till it is your plealure to 
 dellroy that equilibrium. Suppofe, then, for the pre- 
 fent, that both coffers are loaded with a boat in each, 
 the double fluices both above and below clofetl ; and 
 fuppofe alfo that a ftop-cock u, in the under edge of 
 the fide of the lower coffer (fig. 4. and 6.), is opened, 
 fome of the water which ferved to float the boat in the 
 coffer will flow out of it, and confequently that coffer 
 will become lighter than the higher one ; the upper 
 coffer will of courfe defcend, while the other mounts 
 upwards. When a gentle motion has been thus com- 
 municated, it may be prevented from accelerating, mere- 
 ly by turning the llop-cock fo as to prevent the lofs 
 of more water, and thus one coffer will continue to 
 afcend, and the other to defcend, till they have affumed 
 their liations refpeftively ; when, in confequence of a 
 flop below, and another above, they are rendered fla- 
 tionary at the level of the refpeftive canals (a). 
 
 " Precifely the fame effeft will be produced when the 
 coffers are filled entirely with water. 
 
 " It is unneccffary to add more to this explanation, 
 except to obferve that the fpace for the cofler to de- 
 fcend into muft be deeper than the bottom of the lower 
 canal, in order to allow a free defcent for the coffer to 
 the rcquifite depth ; and of courfe it will be neceffary 
 to have a fmall conduit to allow the water to get out of 
 it. Two or three inches free, below the bottom of the 
 canal, is all that would be neceffary. 
 
 " Where the height is inconfiderable, tliere will be 
 no occafion for providing any counterpoife for the 
 chain, as that v.ill give only a finall addition to the 
 weight of the undermofl coffer, fo as to make it pre- 
 ponderate, in circumfl:anccs where the two coffers would 
 otherwife be in perfeft equilibrium : but-, where the 
 height is confiderable, there will be a neceffity for pro- 
 * viding fuch a counterpoife ; as, without it, the chain, 
 
 by becoming more weighty every foot it dcfcended, 
 would tend to deftrcy the equilibrium too much, and 
 accelerate the motion to an inconvenient degree. To 
 guard againft this inconvenience, let a chain of the fame 
 weight, per foot, be appended at the bottom of each 
 coffer, of fuch a length as to' reach within a few yardi 
 of the ground where the coffer is at its greatcfl height 
 (fee fig. 3.) ; it will aft with its whole weight upon 
 the higheft coffer while in this pofition ; but, as that 
 gradually dcfcended, the chain would reach the ground, 
 and, being there fupported, its weight would be di- 
 
 57 .] , CAN 
 
 miniflied in proportion to its defcent ; while the weight Canals 
 of the chain on tlie oppofite fide would be augmented — ~^~~" 
 in the fame proportion, lo as to counterpoife each other 
 cxaftly, in every fituation, until the uppcrmoft chain 
 was raifed from the ground. Alter which it would 
 increafe its weight no more; and, of courfe, would then 
 give the under coffer that preponderance which is ne- 
 ceffary for preferving the machine (leady. The under 
 coffer, when it reached its lowed pofition, would touch 
 the bottom on its edges, which would then fnpport it, 
 and keep every thing in the fame pofition, till it was 
 made lighter for the purpofe of afcending. 
 
 " What conftitutcs one particular excellence of the 
 apparatus here propofed is, that it is not only unlimited' 
 as to the extent of the rife or depreffion of which it 
 is fufceptible (for it would not require the expendi- 
 ture of one drop more water to lower it one humlreJ 
 feet than one foot) ; but it would alfo be eafy fo to 
 augment the number of pulleys at any one place as to 
 admit of two, three, four, or any greater number of 
 boats being lowered or elevated at the fame time ; fo 
 that let the fucceilion of boats on fuch a canal be near- 
 ly as rapid as that of carriages upon a highway, none 
 of them need be delayed one moment to wait an op- 
 portunity of paffing : a thing that is totally imprafti- 
 cable where water-locks are employed ; for the inter- 
 courfe, on every canal conftrufted with water-locks, 13 
 ncceffarily limited to a certain degree, beyond which it 
 is impoffible to force it. 
 
 " For example ; fuppofe a hundred boats are follow- 
 ing each other, in fuch a rapid fucceffion as to be only 
 half a minute behind each other : By the apparatus 
 here propofed, they uould all be elevated precifely as 
 they came ; in the otlier, let it be fuppofed that the 
 lock is fo well conftrufted as that it takes no more than, 
 five minutes to clofe and open it ; that is, ten minutes 
 in t'.se whole to each boat (for the lock, being once 
 filled, muft be again emptied before it can receive aiio. 
 ther in the fame dircftion) : at this rate, fix boats only 
 could be paffed in an hour, and of courfe it would take 
 fixteen hours and forty minutes to pafs the whole hun- 
 dred ; and as the laft boat would reach the lock in the 
 fpace of fifty minutes after the firft, it would be detain- 
 ed fifteen hours and fifty minutes before its turn would 
 come to be raifed. This is an inmienfe detention ; but 
 if a fucceffion of boats, at the fame rate, were to follow 
 continually, they never could pafs at all. In (hort, in 
 a canal conftrufted with water-locks, not more than fix 
 boats, on an average, can be parted in an hour, fo that 
 beyond that extent all commerce muft be ftupped; but, 
 of the plan here propofed, iixty, or fix hundred, migiit 
 be paffed in an hour if neceffary, fo as to occsfion no 
 fort of interruption whatever. Thefe are advantages 
 of a very important nature, and ought not to be over- 
 looked in a commercial country. 
 
 " This apparatus might be employed for innume- 
 rable other ufes as a moving power, whicii it would be 
 foreign to our prefent purpofe here to fpecify. Nor 
 does its power admit of any limitation, but tliat of the 
 ftrength of the chain, and of the coffers which are to 
 fupport the weights. All the other parts admit of 
 
 hciii^r 
 
 (a) " It does not feem neceffary to adopt any other contrivance than the above for regulating the motions ^ 
 but if it ihould be found neceffary, it would be eafy to put a ratch-wheel on the fame axle."
 
 CAN 
 
 [ 1 
 
 Canary, being made To imtnoveably firm as to be capable of fup- 
 
 '^"''*- portiiif; almoft any affignable weight. 
 "" * " I will not eiil irge on the benclits that may be deri- 
 
 ved from this very firaple apparatus : its cheapncis, when 
 compared with any other mode of railluij and lowering 
 vedds that has ever yet been praitiled, is very obvious; 
 the wade of water it would oceafion is next to nothing; 
 and when it is eonfidered that a boat might be railed 
 or lowered fifty feet nearly with the fame eafe as five, 
 it is evident that the interruptions which arlfe from 
 frequent locks would be avoided, and an immenle fa- 
 ving be made in the original expence of the canal, and 
 ill the annual repairs. 
 
 " It is alio evident that an apparatus, on the fame 
 principle, might be eafdy applied for raifing coals or 
 metals from a great depth in mines, wherever a very 
 fmall llream of water could be commanded, and where 
 the mine was level-free." 
 
 CANARY-BIRD, of which a dtfcription is given in 
 the Encyclopedia, was not known in Europe till to- 
 Avards the end of the 15th century. Even in 1 555, 
 Bellon, who about that time defcribed all the birds 
 then known, docs not fo much as mention it. When 
 it was lirft brought from the Canary Illands, It was fo 
 dear that it could be purchafed only by people of for- 
 tun^-, who were often impofed upon. It was called the 
 fugar-l'ird, becaufe it was faid to be fond of the fugar- 
 cane, and could eat fugar in great abundance. This is 
 rather a fr.igular circumllance, fugar being to many 
 fowls a poifon. Experiments have (hewn that a pi- 
 geon, to which four drams of fugar was given, died in 
 four hours ; and that a duck, which had fwallowed five 
 drams, did not live feven hours. 
 
 In the middle of the lail century canai-y-birds began 
 to be bred in Europe ; and to this the following cir- 
 cumllance, related by Olina, feenis to have given ocea- 
 fion : " A vefTel which, among other commodities, was 
 carrying a number of canary birds to Leghorn, was 
 wrecked on the coaft of Italy ; and thefe birds being 
 thus fet at liberty, flew to the nearcll land, which was 
 the ifland of Elba, where tlvey found the climate fo fa- 
 vourable, that they multiplied, and perhaps would have 
 become domefticated, had they not been caught in 
 fnares ; for it appears that the breed of them there has 
 been long deftroyed. Olina fays that the breed foon 
 degenerated ; but it is probable that by much the 
 greater part of thefe canary-birds were m.ales, which 
 coupling with birds ot the ifland, produced mules, fuch 
 as aie defcribed by Gefner and other naturalills>" 
 
 " Various treatifes have been publlfhed in different 
 languages, on the manner of breeding theie birds, and 
 many people have made it a trade, by which they have 
 acquired coufiderable gain. It does no difcredit to the 
 indullry of the Tyrolians, that they have carried it to 
 the greateft extent. At Ymlt there is a company, who, 
 after the breeding feafon is over, fend out perfons to 
 different parts of Germany and Switzerland to purchafe 
 birds from thofe who breed them. Each perfon brings 
 with him commonly from three to four hundred, which 
 are afterwards carried for fale, not only through every 
 part of Germany, but alfo to England, Rufiia, and even 
 Conftantinople. About fixteen hundred are brought 
 every year to England ; where the dealers in them, not- 
 withftandlng the confiderable expence they are at, and 
 after carrying them about on their backs, perhaps a 
 
 jS ] CAN 
 
 hundred miles, fell them for five (hillings a piece. This 
 trade, hitherto neglefted, is now carried on in Scliwartz- 
 walde ; and at prefent there is a citizen at Gottingen ; 
 who takes with him every year to England feveral ca- 
 nary-birds and bulfinches ( loxia pyrrhuLi), with the pro- 
 duce of which he puvchafes fuch fmall wares as he has 
 oceafion for." — Profrffbr BccLmann's HiJIory of Inven- 
 tions and Di/coz'criss. 
 
 C.iiWARY-Seed. tiee Phalaris, Encycl. — ProfcfTor 
 Beckmann doubts whether the plant which bears the 
 canary-feed be i\\t phalaris of the aneients, becaufe that 
 name feems to have been given by Pliny to more than 
 one fpecies of grafs. He thinks it very probable, how- 
 ever, that the plant, which the modern botanifts call 
 phalaris, was firft brought from the Canary Illands to 
 Spain, where it began to be cultivated, as well as in the 
 fouth of France, as foon as canary-birds came into ge- 
 neral efteem. At prefent it is cultivated in various 
 places, and forms no inconfiderable branch of trade, 
 particularly \n the ifland of Sicily, where it is called 
 Scagliuola or Scaghiola. Were it not that the grains are 
 not eafily freed from the hulks, this plant might be cul- 
 tivated for the food of man, for its feeds yield a good 
 kind of meal. The phalaris has by feveral writers been 
 confounded with argol or the lichen rocolla of Linneus ; 
 but they are very different plants. See Lichen Ro- 
 colla in this Supplement. 
 
 CANDLE, a thing fo univerfally known as to need 
 no particular defcription. Its ufe, however, is fo great, 
 that every information tending to its improvement mull, 
 we (hould think, be acceptable to our readers. Of the 
 common method of making candles, whether of wax or 
 of tallow, a fufficient account has been given in the En- 
 cyclopaedia ; but candles of every kind are far from be- 
 ing yet brought to that degree of pcrfcdlion of which 
 they feem fufceptible. Thus, for example, the light of 
 a candle, which is fo exceedingly brilliant when firft 
 fnuffed, is very fpeedily dlminilhed to one half, and is 
 ufually not more than one-fifth or one-fixth, before the 
 uneafinefs of the eye induces us to fnuff it. Hence it 
 follows, that if candles could be made fo as not to re- 
 quire fnuffing, the average quantity of light afforded by 
 the fame quantity of combutlible matter would be more 
 than doubled. It may likewife be worthy of inquiry, 
 fince the coft and duration of candles are eafily afcer- 
 tainable, whether more or lefs light is obtained at the 
 fame expence during a given time, by burning a number 
 of fmall candles inltead of one of greater thicknefs. 
 
 To determine this laft point, a method mull be found 
 of meafuring the comparative intenfities of I'glit, for 
 which fee Photometer in this Supplement. With 
 refpeft to the defideratum firll mentioned, we have 
 fome very ingenious obfervations and well-contrived ex- 
 periments by Mr Nicholfon, in the fecond number of 
 his valuable Journal, which we (hall here infert nearly 
 in the words of their author. 
 
 In every procefs of combuftion the free accefs of air 
 is of the utmoft confequence. When a candle has a 
 very (lender wick, the flame is fmall and of a brilliant 
 white colour ; if the wick be large, the combuftion is 
 lefs perfeft, and the flame brown ; and a wick (till lar- 
 ger, not only exhibits a brown flame, but the lower in- 
 ternal part appears dark, and is occupied by a portion 
 of volatlhzed matter, which does not become ignited till 
 it has afcended towards the point. When the wick is 
 
 either
 
 CAN [ 159 ] CAN 
 
 '!!«• either very large or very long, part of this matter occalionally brought into its vicinity by the vtrorkman. 
 
 ^~~^ efcapes combuftion, and fliews itfelf in the form of coal But for the ufual piir}5ofes of illumination, it cannot be 
 or fmoke. The fame things take place in the burning fuppofed that a perfoii can attend to fupply the com- 
 of a lamp; but when the wick of a lamp is once ad- bulliblc matter. Confiderable dilTiculties arifc in the 
 julled as to its length, the flame continues nearly in the projett for affording this gradual fupply as it may be 
 fame ftate for a much longer time than the flame of a wanted. A cylindrical piece of tallow was inferted in- 
 candle. to a metallic tube, the upper aperture of which was 
 " Upon comparing a candle with a lamp (fays Mr partly clofed by a ring, and tiic central part occupied 
 Nicholfon), two very remarkable particulars are imme- by a metallic piece nearly refembling tluit part of the 
 diately feen. In the firft place, the tallow itfelf, which common lamp which carries the wiek. In this appara- 
 remains in the unnifed Hate, affords a cup or cavity to tus the piece lalt defcribed was intended to anfwcr the 
 hold that portion of melted tallow which is ready to fame pnrpofe, and was provided with a fhort wick. 
 flow into the lighted part of the wick. In the fecond The cylinder of tallow was fupported beneath in fuch a 
 place, the combuftion, inftead of being confined, as in manner that the metallic tube and other part of this 
 the lamp, to a certain determinate portion of the fibrous lamp were left to reft with their whole weight upon 
 matter, is carried, by a (low fuccelfion, through the the tallow at the ring or contraftion of the upper aper. 
 vifhole length. Hence arifes the greater neceflity for ture. In this fituation the lamp was lighted. It burn- 
 frequent fnuffing the candle ; and hence alfo the llatlon ed for fume time with a very bright clear flame, which, 
 of the freezing point of the fat oil becomes of great wlien compared wllii that of a candle, poffeffed the ad- 
 confeqnence. For it has been fhewn, that the bril- vantage of uniform intenfity, and was much fuperlor to 
 liancy of the flime depends very m\ich on the diameter the ordinary flame of a lamp In Its colour, and the per- 
 of the wick being as fmall as pofilble ; and this requi- tedf ablence of fmell. After fome minutes It began to 
 fite will be moft attainable in candles tornied of a mate- decay, and very foon afterwards went out. Upon exa- 
 rial that requires a higher degree of heat to fu(e It. minatlon, It was found that the metallic piece which 
 The wick of a tallow candle muft be made thicker in carried the wick had fufed a infiicient quantity of tal- 
 proportion to the greater fufibility of the matclal, low for the fupply during the combuftion ; that part of 
 which would otherwife melt the fides of the cup, and this tallow had flowed beneath the ring, and to other 
 run over in (beams. The flame will therefore be yel- remote parts of the apparatus, beyond the influence of 
 low, fmoky, and obfcure, excepting for a fhort time the flame ; in confequence of which, the tube and the 
 immediately after fnuflang. Tallow melts at the yad cylinder of tallow were faftened together, and the ex- 
 . degree of Fahrenheit's thermometer ; fpcrmaceti at the peftcd progreffion of fupply prevented. It feems pro- 
 133d degree; the fatty matter formed of flefli, after bable that. In every lamp for burning confiftejit oils, the 
 long immerfion in water, melts at 127 degrees; the material ought to be fo difpofed that it mav dfifcend to 
 pela of the Chinefe at 145 degrees; bees-wax at 142 the flame upon the principle of the fountain refervolr. 
 degrees ; and bleached wax at 15J degrees. Two of I fhall not here ftate tlie obftacles which prefent them- 
 thefe materials are well known in the fabrication of can- felves in the profpeft of this coaftruftion, but ftiall dif- 
 dles. Wax in particular does not aflord fo brilliant a mifs the fubjecf by remarking, that a contrivance of this 
 flame as tallow; but, on account of its lefs furibilltv, nature would be of the g.rcatcft >)ublic utility. 
 the wick can be made fmailer, which not only affords " The wick of a candle being furrounded by the 
 the advantage of a clear perfect flame, but from its flexi- flame, Is nearly In the fituation of a body expofed to 
 blllty It is difpofed to turn on one fide, and come in deftruftive diftlUation in a clofe veffel. After lofing its 
 contaft with the external air, which completely burns volatile products, the carbonaceous refidue retains its Ti- 
 the extremity of the wick to white afhes, and thus per- guic, until, by the defcent of the (hme, the external 
 Jorms the office of fnufling. We fee therefore that the air can have accefs to its upper extvemity. But, in this 
 important object to fociety of rendering tallow candles cafe, the requlfite combuftion, wh'ch might fnuff It, Is 
 equal to thofe of wax, does not at all ilepend on the not effefted : for the portion of oil emitted by the 
 combuftlbillty of the refpeftlve materials, but upon a long wick is not only too large to be perfeftly burned, 
 mechanical advantage in the cup, which is afforded by but alfo carries off much- of the heat of the flame while 
 the inferior degree of fufibility in the wax ; and that, it affumes the elaftlc ftate. By this dimlnilhed com- 
 to obtain this valuable objed, one of the followii;g ef- buftlon and Increafed efflux of half-dccompofed oil, a 
 fefts muft be produced: Either the tallow mult be portion of coal or foot is depolited on the upper part of 
 burned in a lamp, to avoid the gradual progreffion of the wick, which gradually accumulates, and at length 
 the flame along the wick ; or fomenieans muft be de- affumes the appearance of a fungus. The candle does 
 
 Cr.n!!e. 
 
 \ 
 
 vlfed to enable the candle to fnuff itfelf, as the wax 
 candle does ; or, laftly, the tallow itfelf muft be render- 
 ed lefs fufible by fome chemical procefs. I have no 
 great reafon to boaft of fuccefs in the endeavour to ef- 
 feft thefe ; but my hope is, that the fatfs and obferva- 
 tlons here prefented may confiderably abridge the la- 
 bour of others in the fame purfuit. 
 
 "The makers of thermometers and other fmall arti- 
 cles with the blow-pipe and lamp, give the preference to 
 tallow inftead of oil, bccaufe its combuftion is more 
 complete, and does not blacken the glafs. In this ope 
 
 not then give more than one-tenth of the light emitted 
 in Its beft ftate. Hence it is that a candle of tallow 
 cannot fpontancoufly fnuff itfelf. It was not probable 
 that the addition of a fubftancc containing vital air or 
 oxygen would fupply that principle at the preclfe pe- 
 riod of time required ; but as experiment is the teft of 
 every probability of this nature, 1 foaked a wick of 
 cotton in a folution of nitre, then dried It, and made a 
 candle. When this came to be lighted, nothing re- 
 markable happened for a fliort time ; at the expiration 
 of which a decrepitation followed at the lower extremi- 
 
 ration the heat of the lamp melts the tallow which is ty of the flame, which completely divided the wick 
 
 where
 
 CAN [ 1 
 
 Can.l'.e. where the blackened part commences. The whole of 
 —^r—- tJie niattf r In combulllon tliereforc fell off, and the can- 
 dle was of courfc inftantly cxtinguifhed. Whether this 
 would have happened in all proportions of the fait or 
 conllruitions of the candle, I did not try, becatife the 
 fmell of azot was fufficlently ftrong and unpleafant to 
 forb!<l the ufe of nitre in the purfuit. From various 
 confiderations, I am difpofed to think that the fponta- 
 neous fnuffiug of candles made of tallow, or other fuli- 
 ble materials, will fcarcely be effefted but by the difco- 
 very of fome material for the wick which fhall be volu- 
 minous enough to abforb the tallow, and at the fame 
 time fufficitntly flexible to bend on one fide. 
 
 " The moll promifing fpeculation refpedlirg this moft 
 ufeful article, feems to dired itfelf to the cup which 
 contains the melted tallow. The imperfeftion of this 
 part has already been noticed, namely, that it breaks 
 down by fu%)n, and fuffers its fluid contents to efcape. 
 The Chinele have a kind of candle about half an inch 
 \\\ diameter, which, in the harbour of Canton, is called 
 a lobchock ; but whether the name be Chinefe, or the 
 corruption of fome European word, I am ignorant. 
 The wick is of cotton, wrapped round a fmall Hick or 
 match of the bamboo cane. The body of the candle is 
 white tallow ; but the external part, to the thicknefs of 
 perhaps one thirtieth of an inch, confifts of a waxy- 
 matter coloured red. This covering gives a confider- 
 able degree of folidlty to the candle, and prevents its 
 glittering, becaufe lefs fulible than the tallow itfelf. I 
 did not obferve that the fl:ick in the middle was either 
 advantageous or the contrary ; and as I now write from 
 the recolleftion of this objeft at fo remote a period as 
 25 years ago, I can only conjefture that it might be of 
 advantage in throwing up a lefs quantity of oil into the 
 flame than would have been conveyed by a wick of 
 cotton fnfficiently ftout to have occupied its place un- 
 fupported in the axis of the candle. 
 
 " Many years ago I made a candle in imitation of 
 the lobchock. The expedient to which I had recourfe 
 confided in adapting the wick in the ufual pewter 
 mould : wax was then poured in, and immediately af- 
 terwards poured out : the film of wax which adhered 
 to the inner furface of the mould foon became cool, and 
 the candle was completed by filling the mould with tal- 
 low. When it was drawn out, it was found to be 
 cracked longitudinally on its furface, which I attribu- 
 ted to the contraClion of the wax, by cooling, being 
 greater than that of the tallow. At prefent I think it 
 equally probable that the cracking might have been 
 occafioned by too fudden cooling of the wax before the 
 tallow was poured in ; but other avocations prevented 
 the experiments from being varied and repeated. It is 
 probable that the Chinefe external coating may not be 
 formed of pure hard bleached wax. 
 
 " But the mcft decifive remedy for the imperfeftion 
 of this cheapelt, and in other refpefts bell, material for 
 candles, would undoubtedly be to diminifli its fufibilitv. 
 Various fubilances may be combined with tallow, either 
 in the direCl or indirect method. In the latter way, 
 by the decompofition of foap, a number of experiments 
 were made by Berthollet, of which an account is in- 
 ferted in the memoirs of the Academy at Paris for -the 
 year 1780, and copied into the 26th volume of the 
 'Journal He Phyfique. None of thefe point direftly to 
 the prefent objeft ; btfides which, it is probable that 
 
 60 ] CAN 
 
 the foap made ufe of by that eminent chemift was form- Candle, 
 ed not of tallow, but oil. I am not aware of any re- "~~v~~" 
 gular feries of experiments concerning the mutual ac- 
 tion of fat oils and other chemical agents, more efpe- 
 cially fuch as may be direfted to this important objedt 
 of diminifliing its folubility ; for which reafon I (hall 
 mention a few experiments made with this viewr. 
 
 " I . Tallow was melted in a fmall filver veffel. Solid 
 tallow finks in the fluid, and diflblves without any re- 
 markable appearance. 2. Gum fandarach in tears waj 
 not diflblved, but emitted bubbles, fwelled up, became 
 brown, emitted fumes, and became crifp or friable. No 
 folution nor improvement of the tallow. 3. Shell-lac 
 fwelled up with bubbles, and was more perfedlly fufeJ 
 than the gum fandarach in the former experiment. 
 When the tallow was poured off, it was thought to 
 congeal rather more fpeedily. The lac did not appear 
 to be altered. 4. Benzoin bubbled without much fwel- 
 ling, was fufcd, and emitted fumes of an agreeable fmell, 
 though not refembling the flowers of benzoin. A flight 
 or partial folution feemed to take place. The benzoia 
 was fofter and of a darker colour than before, and the 
 tallow lefs confiflent. J. Common refin unites very 
 readily with melted tallow, and forms a more fufible 
 compound than the tallow itfelf. 6. Camphor melts 
 eafily in tallow, without altering its appearance. When 
 the tallow is near boiling, camphoric fumes fly off. 
 The compound appeared more fuiible than tallow. 
 7. The acid or flowers of benzoin diffolves in great 
 quantities without any ebullition or commotion. Much 
 fmoke arifes from the compound, which does not fmell 
 like the acid of benzoin. Tallow alone does not fume 
 at a low heat, though it emits a fmell fomething like 
 that of oil olive. When the proportion of the acid was 
 confiderable, fmall needled cryftals appeared as the tem- 
 perature dimlniflied. The appearances of fcparation are 
 different according to the quantity of acid. The com- 
 pound has the hardnefs and confiftence of firm foap, 
 and is partially tranfparent. 8. Vitriolated tartar, nitre, 
 white fugar, cream of tartar, crydallized borax, and 
 the fait (old in the markets under the name of fait of 
 lemons, but which is fuppofed to be the effential fait 
 of forrel, or vegetable alkali fuperfaturated with acid of 
 fugar, were refpeftively tried without any obvious mu- 
 tual aftion or change of properties in the tallow. 9. 
 Calcined magnefia rendered tallow opaque and turbid, 
 but did not feem to diffolve. Its effeft refembled that 
 of lime. 
 
 " It is propofed to try the oxygenated acetous acid, 
 or radical vinegar ; the acid of ants, of fugar, of borax, 
 of galls, the tanning principle, the ferous and gelatinous 
 animal matter, the fecula of vegetables, vegetable glu- 
 ten, birdlime, and other principles, either by direiS or 
 indireft application. The objeft, in a commercial point 
 of view, is intitled to an extenfive and afiiduous invefti- 
 gation. Chemifts in general fuppofe the hardnefs or 
 lefs fufibility of wax to arife from oxygen ; and to thij 
 objeft it may perhaps be advantageous to direft a cer- 
 tain portion of the inquiry. The metallic falts and cal- 
 ces are the combinations from which this principle is 
 moft commonly obtained; but the combinations of thefe 
 with fat oils have hitherto afforded little promife of the 
 improvement here fought. The fubjeft is, however, fo 
 little known, that experiments of the loofeft and moft 
 conjeftural kind are by no means to be defpifed." 
 
 Thus
 
 C A O 
 
 [ i6i ] 
 
 G A O 
 
 chouc. 
 
 •aronjics Thus far Mr Nicholfon : but it is probable that ma- 
 Caonr- „y. „£ the advantages which lie propofes by thefe mix- 
 lures might be obtained merely by purifying the tallow, 
 and keeping it in that (late for a long time expofed to 
 the air before it be formed into candles. It is certain 
 that tallow is rendered more difficult of fufion by age ; 
 and this is the fole reafon that old candles are lefs apt 
 to run, and therefore more valuable than fnch as have 
 been lately made. 
 
 CANONGOES, in Bengal, are the regifters of land 
 and hereditary expounders of the ufagea of the country. 
 They have their officers and deputies everywhere ; they 
 are not liable to removal ; and all papers atteltcd by 
 them are received as authentic and decifive in all dif- 
 putes relative to lands and their boundaries. See Sir 
 Charles Roufe Boughton's D'ljfcrtLiiwn on the LmuLd Pro- 
 perly of Bengal. 
 
 CAOUTCHOUC, Elastic Gum, or InJmn Rub- 
 ier, is a fubftance of which a pretty full account has 
 been given in the Eucyclopasdia. It has there been 
 likewife obferved how ufeful it might be, if we could 
 form it into catheters and other flexible inftrunients, by 
 diffolving it in a menilruum lefs expenfive, or at leaft 
 more eafily attained, than ether. Since that article was 
 publiflieJ, we have feen an account of fuch a merftruum 
 in the Annales de Chlm'ie, by M. GrofTart (Chirly) ; 
 and of the expence of that menftruum, or the diihtulty 
 of procuring it, no complaint will be made, when it is 
 known to be nothing more than very hot water. 
 
 The author was led to this difcovery by fome experi- 
 ments made with ether on caoutchouc ; of which he 
 gives the following account : 
 
 " It appeared, even in my firft experiments, that I 
 was attempting" too much, and giving myfclf ufelefs 
 trouble, in fearching for a manner of completely diffal- 
 ving the elaftic gum, fo that it might be again made up 
 in new forms. I then thought that it would be eafier 
 to find out a method, as it were, of foldering it, and of 
 not afling upon it more than might be neceffary to 
 caufe its foftcned parts to reunite. Experience has 
 fliewn me, that a (Irong preffure made upon two pieces 
 of caoutchouc (when brought to that ftate of foftnefs) 
 and continued until they are entirely dry, caufed them 
 to coiitracl; fo ftrong an adlufion, that the piece, being 
 pulled out till it broke, often broke, not at the united 
 part, but by the fide of it. 
 
 " By means of ether I immediately fucceeded in ma- 
 king thefe tubes. The method which appears to me to 
 fucceed the beft is, to cut a bottle circularly in a fpi- 
 ral flip of a few lines in breadth. It is very eafy to cut 
 a bottle in fuch a manner as to form a fingle long flip, 
 and thus unnecefTitry joinings are avoided. 
 
 " The whole flip is to be plunged into ether until it 
 is fufncicntly foftcned, which comes to pafs fooner or 
 later according to the quality of the vitriolic ether that 
 is employed. Half an hour frequently fuffices ; but I 
 have already obferved, that there is a great divevhty in 
 the manner in which different forts of vitriolic ether att, 
 and of which the caufe is not yet, fo far as I know, de- 
 termined. 
 
 " The flip being taken out, one of the extremities is 
 to be taken hold of and rolled, firfl upon itfelf at the 
 bottom of the tube, prefTmg it ; then the rolling is to 
 be continued, mounting fpirally along the mould, and 
 taking care to lay over and comprefs with the hand 
 
 SuPFL. Vol. I. Parti. 
 
 every edge, one again ft tiie other, fo that there nlay 
 not be any vacant fpace, and that all the edges may join 
 exaftly. The whole then is to be bound hard with a 
 tape of an inch in width, taking care to turn it the 
 fame way with the flip of elaftic gum. The tape is to 
 be tied up with packthread, fo that, by every turn of 
 the packthread joining another, an equal preflhre u 
 given to every part : it is then left to dry, and the tube 
 is made. 
 
 " The bandage is to be taken off with great care, 
 that none of the outward furfaces, wliich may have been 
 lodged within the hollows of the tape (of which the 
 caoutchouc takes the exaft imprcffion), may he pulled 
 away. I advife the application of a tape before pack- 
 thread, becaufe, efpecially in the thinner tubes, we fhoulJ 
 run the rifk of cutting the caoutchouc if the packthread 
 were applied immediately upon it. 
 
 " It is eafy to take off the tube of elaftic gum which 
 has been formed upon a folid mould of one piece : if 
 the mould be made rather conic, it may be made to 
 Hide off by the fmaller end ; at the worft, it is eafily 
 accomplifhed by plunging it into hot water ; for it 13 
 foftcned by the heat, and is diftended : without this 
 precaution it would be fometimes difficult to draw it off 
 when dry, becaufe, having been applied upon the mould 
 whilft it had its volume augmented by the interpofition 
 of the ether, the parts of the caoutchouc are drawn 
 nearer each other by the evaporation of the iuterpofed. 
 bodies. 
 
 " The great afiinity between thefe two bodies is feen 
 by the length of time that the odour of the ether re- 
 mains, notwithftanding the great volatility of the latter, 
 and that the apparent drynefs of the tube feems to (hew 
 that there is none remaining ; nevcrthelcfs, after a cer- 
 tain time, the odour difappears entirely. One of thofe 
 tubes, which was ir.ade with ether after the method 
 here defcribed, does not retain the leaft trace of the ful- 
 vent. It is needlefs to fay that it is eafy to make tubes 
 as thin or as thick as may be judged proper. 
 
 " Although the procefs that 1 am now defcribin"' is 
 but very little expenfive, yet I have tried to emplov 
 other folvents in lieu of ether, becaufe it is not to be 
 had in every place, and requires particular care in its 
 prefervatiou. I have employed, with fome fuceefs, the 
 effential oils of lavender and of turpentine: both of them 
 fpeedily dilate the caoutchouc, and are of no great 
 price. The difagreeable fmell of the oil of turpentine 
 becomes, perhaps, in procefs of time, lefs difagreeable 
 than that of lavender. This lall is dearer : but the dif- 
 ference is not fo great as it appears at firft; for we may 
 make fome advantage of the oil of lavender that is em- 
 ployed by the following operation : Upon plunging in- 
 to alcohol the elaftic tube prepared with the oil of la- 
 vender, the alcohol charges itfelf with the oil, and forms 
 a very good lavender water; the fame as would be made 
 by an immediate mixture of oil of lavender with fpirit 
 of wine. Immerfion in this liquor alfo ferves to haften 
 the drying of the caoutchouc inftruments thus made 
 by means of effential oils. I have made tubes with the 
 oils of turpentine and of lavender; both are much (low- 
 er in evaporating than ether. The oil of turpentine 
 particularly appeared to me always to have a kind of 
 ftickinefs, and I know not as yet that we have any 
 means whereby to get fpeedily rid of its fniell. 
 
 •' Neverthelefs there is a folvent which has not that 
 X incon- 
 
 Caont-
 
 C A O 
 
 [ 16 
 
 inconvenience ; it !s cheaper, and may enfily be procu- 
 rt d by every one : this folvcnt is water. I conceive it 
 will appear ftrant^e to mention water as afolvent of elaf- 
 tic jrum, that liquid having been always fuppofcd to 
 have no aftion upon it. I inyfclf refifted the idea; but 
 refleftinfr that ether, by being faturatcd with water, is 
 the better enabled to aft on caoutchouc, and that this 
 Tum when plunged into boiling water beconnes more 
 tranfparent at the cdi;es, I prefuined that this efTeCt was 
 not due limply to the dilatation of its volume by the 
 heat. I thought that, at that temperature, fome ac- 
 tion might take place, and that a long continued ebul- 
 lition might produce more fenfible effefts. I was not 
 difappointed in my expeftations, and one of thofe tubes 
 was prepared without any other folvent than water and 
 lieat. I proceeded in the fame manner ps with ether : 
 the elaftic gum dilates but very little in boiling water ; 
 it becomes whitllh, but recovers its colour again by dry- 
 ing it in the air and light. It is fufficiently prepared 
 for ufe when it has been a quarter of an hour in boiling 
 water: by this time its edges are fometimes tranfpa- 
 rent. It is to be turned fpirally round the mould, in 
 the manner we defcribed Ijefore, and replunged fre- 
 quently into the boiling water during the time that is 
 employed in forming the tube, to the end that the edges 
 may be difpofed to unite together. When the whole 
 is bound with packthread, it is to be kept fome hours 
 in boiling water; after which it is to be dried, Hill keep- 
 ing on the binding. 
 
 " If we wifli to be more certain that the conneftion 
 is perfeft, the fpiral may be doubled ; but we muft al- 
 ways avoid placing the exterior furfaces of the flips one 
 upon the other, as thofe furfaces are the parts which 
 moft refill the aftion of folvents. This precaution is 
 lefs necefTary when ether h employed, on account of its 
 great adlion upon the caoutchouc. 
 
 " It might be feared that the aftion of water upon 
 caoutchouc would deprive us of the advantages which 
 might otherwife be expefted ; but thefe fears will be 
 removed, if we confider that the affinities differ accord- 
 ing to the temperatures ; that it is only at a very high 
 temperature that water exercifes any fenfible aftion up- 
 on caoutchouc, I can affirm, that at i 20" of Reaumur's 
 thermometer (302'' of Fahrenheit ) this affinity is not 
 fuch as that the water can give a liquid form to caout- 
 chouc ; and It does not appear that we have any thing 
 to fear in praftice from a combination between thefe 
 two bodies, which, though it really is a true folutlon, 
 does not take place in any fenfible degree but at a high 
 temperature. It is therefore at prefent eafy to make of 
 raoutchouc whatever inflruments it may be advantage- 
 ijUs to have of a flexible, fupple, and elaftic fubftance, 
 which is impermeable to water at the temperature of 
 our atmofphere, and refills the aftion of acids as well 
 as that of mofl other folvents. As to the durability of 
 thefe inftruments, few fubllances promife more than this, 
 becaufe it may be foldered afrelh in a damaged part. 
 Any woven fubftance may be covered with it ; it is on- 
 ly required that the fubftance fhould be of a nature not 
 to be afted upon during the preparation, either by ether 
 or by boiling water ; for thefe two agents are thofe 
 which appear to me to merit the preference. Artifts 
 will frequently find an advantage in employing ether, 
 as it requires lefs time ; fo that a perfon may make, in 
 a fingle day, any tube he may have occafion for. The 
 
 2 ]. CAP 
 
 expeuce of ether is very little, fince it is needful only to 
 difpofe the caoutchouc to adhere ; and being brought 
 into ih.at fhite, the caoutchouc may be kept in a vedel 
 perfeftly well clofed. It would alfo diminifh the ex- 
 pence of the ether if, iullead of walliing it with a large 
 quantity of water, there fhould be added to it only as 
 iruch water as it can take up." 
 
 CAP and Button, are two fmall illands, or rather 
 rocks, lying in longitude \o^° i\Vi' ;>,->" eall ; and in la- 
 titude, the former 5^ 58' 30", the latter 5^49'fouth. 
 They Avere vifited by fome of the perfons attending 
 L,oid Macartney on his embafly to China; and are thus 
 defcribed by Sir George Staunton. 
 
 " At a little dlilance they might be miftaken for the 
 remains of old caftles, mouldering into heaps of ruins, 
 with tall trees already growing upon the tops ; but at 
 a nearer view, they betrayed evident marks of a volca- 
 nic origin. Explofions from fubterraneous fires, pro- 
 duce, for the moft part, hills of a regular fhape, and ter- 
 minating in truncated cones ; but when from a fub- 
 aqneous volcano eruptions are thrown up above the 
 furface of the fea, the materials, falling back into the 
 water, are more irregularly dlfperfed, and generally 
 leave the fides of the new creation naked and mifhapen, 
 as in the inllance of Amsterdam, and of thofe fmaller 
 fpots called, from fome refemblance in lliape, the Cap 
 and Button. 
 
 " In the Cap were found two caverns, running ho- 
 rizontally into the fide of the rock ; and in thefe were a 
 number of thofe birds ncfts fo much prized by the Chi- 
 nefe epicures. They feeraed to be compofed of fine fi- 
 laments cemented together by a tranfparent vifcous mat- 
 ter, not unlike what is left by the foam of the fea up- 
 on ftones alternately covered by the tide, or thofe gela- 
 tinous animal fubftances found floating on every coaft. 
 The nefts adhere to each other, and to the fides of the 
 cavern, moftly in rows, without any break or interrup- 
 tion. The birds that build thefe nefts are fmall grey 
 fwallows, with ■bellies of a dirty white. They were 
 flying about in confiderable numbers; but they were fo 
 fmall, and their flight fo quick, that they efcaped the 
 fhot fired at them. The fame nefts are fald alfo to be 
 found in deep cavern;;, at the foot of the higheft moun- 
 tains in the middle of Java, and at a dlilance from the 
 fea, from which the birds, it is thought, derive no ma- 
 terials, either for their food or the conftrudllon of their 
 nefts ; as it does not appear probable they Ihould fly, 
 in fearch of either, over the interm'ediate mountains, 
 which are very high, or againft the boifterous winds 
 prevailing thereabouts. Tliey feed on infefts, which 
 they find hovering over ftagnated pools between the 
 mountains, and for catching which their wide opening 
 beaks are particularly adapted. They prepare their 
 nefts from the bell remnants of their food. Their 
 greateft enemy is the kite, who often intercepts them in 
 their pall'age to and from the caverns, which are gene- 
 rally furrounded with rocks of grey limellone or white 
 marble. The nefts are placed in horizontal rows at 
 different depths, from 50 to 500 feet. The colour and 
 value of the nefts depend on the quantity and quality 
 of the infefts caught, and perhaps alfo on the fituation 
 where they are built. Their value is chiefly determined 
 by the uniform finenefs and delicacy of their texture ; 
 thofe that are white and tranfparent being moft elleem- 
 ed, and fetching often in China their weight in filver. 
 
 Thefe 
 
 Cap,
 
 CAP 
 
 [ 
 
 dp. Tlicfe nefts are a confiderable objeft of traffic among 
 •'-v—'~- t),e Javanefe, and many are employed in it from their 
 infancy. The birds having fpent near two months in 
 preparing their nefts, lay each two eggs, which are 
 hatched in about fifteen days. When the young birds 
 become fledged, it is thought time to feize upon their 
 nefts, which is done regularly thrice a-year, and is ef- 
 fected by means of ladders of bamboo and reeds, by 
 which the people defccnd into the cavern ; but when it 
 is very deep, rope ladders are preferred. This operation 
 is attended with much danger ; and feveral break their 
 necks in the attempt. The inhabitants of the moun- 
 tains generally employed in it begin always by facri- 
 ficing a buffalo ; which cullom is conftantly obferved 
 by the Javanefe on the eve of every extraordinary en- 
 terprife. They alfo pronounce iome prayers, anoint 
 themfelves with fweet fcented oil, and fmoke the en- 
 trance of the cavern with gum-benjamin. Near fome 
 of thofe caverns a tutelar goddefs is worfhipped, whofe 
 pried burns incenfe, and lays his protefling hands on 
 every perfon preparing to deicend into the cavern. A 
 flambeau is carefully prepared at the fame time, with a 
 gum which exudes from a tree growing in the vicinity, 
 and is not eafily extingulihed by fixed air or fubterra- 
 reous vapours. The fwallow which builds thofe nefts 
 js defcribed as not having its tail feathers marked with 
 
 63 ] CAR 
 
 white i'pots, which is a charafter attributed to it by 
 Linnjeus ; and it is poflible that there arc two fpecies 
 or varieties of the fwallow, whofe nefts are alike va- 
 luable." See BiRDS-Nefs, Encycl. 
 
 CAPE OF Good Hope. See Good Hope, both in 
 Encycl. and this Supplement. 
 
 CAPITAL of a Bastion, is an imaginary line 
 dividing any work into two equal and fimilar parts ; or 
 a line drawn from the angle (■? the polygon to the point 
 of the baition, or from the point of the baftion to the 
 middle of the gorge. 
 
 CAPRA, or tlie Shegoat, a name given to the 
 ftar Capella, on the left ftioulder of Auriga, and fome- 
 times to the conftcllation Capricorn. Some again re- 
 prefent Capra as a conftellation in tlie northern hemif- 
 phere,'confifting of three itars, comprifed between tiie 
 45th and 55th degree of latitude. — The poets fable her 
 to be Amalthea's goat, which fuckled Jupiter in his 
 infancy. 
 
 CAPUT Draconis, or Dragon's Head, a name 
 given by fome to a fixed ftar of the firft magnitude, in 
 the head of the conftellation Draco. 
 
 CARBON. See Chemistry in this SuppUmenI, 
 Part I. Chap. 11. Seft. iii. 
 
 C.\RP. See Cyprinus, both in the Encycl. and 
 in this Supplement. 
 
 CARPENTRY, 
 
 (efinitior. 
 
 n impor- 
 nt brdnch 
 niechaiu- 
 1 kieucc 
 
 ' I 'HE art of framing timber for the purpofes of archi- 
 -*■ tedm-e, machinery, and, in general, for all confi- 
 derable ftruftures. 
 
 It is not intended in this article to give a full account 
 of carpentry as a mechanical art, or to defcribe the va- 
 rious ways of executing its diff^erent works, fuited to 
 the variety of materials employed, the procefles which 
 muft be followed for faftiioning and framing them for 
 our purpofes, and the tools which muft be ufed, and the 
 manner in which they muft be handled : This would 
 be an occupation for volumes ; and though of great im- 
 portance, muft be entirely omitted here. Our only aim 
 at preftnt will be to deduce, from the principles and 
 laws of mechanics, and the knowledge which experience 
 and judicious inferences from it have given us concern- 
 ing the ftrength of timber, in relation to the ftrain laid 
 on it, fuch maxims of conftruftion as will unite econo- 
 my with ftrength and efficacy. 
 
 This objeft is to be attained by a knowledge, ift, of 
 the ftrength of our materials, and of the abfolute ftrain 
 that is to be laid on them ; 2dly, of the modifications 
 of this ftrain, by the place and direftion in which it is 
 txerted, and the changes that can be made by a proper 
 difpofition of the parts of our ftrufture; and, jdly, ha- 
 ving difpofed every piece in fuch a manner as to derive 
 the uttnoft advantage from its relative ftrength, we muft 
 know how to form the joints and other connexions in 
 fuch a manner as to fecure the advantages derived from 
 this difpofition. 
 
 This is, evidently, a branch of meclianical fcience, 
 which makes carpentry a liberal art, conltitutes part of 
 the learning of the ENGiNEtR, and diltingiiilhcs him 
 from the workman. Its importance in all times and 
 ftates of dvil focitty is inanifeft and great. In the pre- 
 
 fent condition of thefe kingdoms, railed, by the adlive 
 ingenuity and energy of our couyptrymen, to a pitch of 
 profperity and influence unequalled in the hiftory of 
 the world, a condition which confifts chiefly in the fu- 
 periority of our manufactures, attained by prodigious 
 multiplication of engines of every defcription, and for 
 every fpecies of labour, the Science (io to term it) of 
 carpentry is of immenfe confequence. We regret 
 therefore exceedingly, that none of our celebrated ar- 
 tifts have done honour to themfelves and their country, 
 by digefting into a body of confecutive doftrines the 
 refults of their great experience, fo as to forni a fyftem 
 from which their pupils might derive the (irft principles 
 of their education. The many volumes called Com- 
 plete Instructors, Manuals, Jewels, &c. take a 
 much humbler flight, and content themfelves with in- 
 ftruifting the mere workman, or fometimes give the ma- 
 fter-builder a few approved forms of roofs and other 
 framings, with the, rules for drawing them on paper; and 
 from thence forming the working draughts which niuil; 
 guide the faw and the chiftel of the workman. Hardly 
 anv of them ofter any thing that can be called a prin- 
 ciple, applicable to many particular cafes, with the rules , 
 for this adaptation. We are indebted for the greateft Prioc'pally 
 part of our knowledge of this fubjeci to the labours of ■a'fe'Tfd to 
 literary men, chiefly foreigners, who have publiflicd jn 'o eijintrs^ 
 the memoirs of the learned academies diflertations on ledreof this 
 different parts of what may be termed the fcience &/fiibjc>5l, 
 carpentry. It is finguiar that the members of the Royal 
 Society of London, and even ot that ellabllftied and fiip- 
 portcd by the patriotifin ot thefe days for the encou- 
 ragement of the arts, have contributed fo little to the 
 public inftrnftion in this refpeCf. We obferve of late 
 foine beginnings of this kind, fueJi as the laft part of 
 X 2 Nichollon's
 
 164 C A R P E 
 
 Nicliolfoii's Carpenters and Joiners Assistant, 
 publillud by J. Tavior, Holboin, 1 797. And it is 
 with plcafure that we can fay, that we were told by the 
 editor, that this work was prompted in a great meafure 
 by what has been dclivcTed in the Encycloptedia Britan- 
 n'ua ill the articles Rook and Strengih of Matenah. 
 It abounds more in important and new obfervatioiis than 
 any book of the kind that we arc acquainted with. We 
 agai'! call on fnch as have given a fcientlfic attention to 
 this fnbjciS, and pray that tiiey would render a merito- 
 rious fervice to their country by inijiarting the refiilt of 
 their relearches. The very limited nature of this work 
 does not allow us to treat the fubjeCf in detail ; and we 
 mull confine our obfcrvanons to the fundamental and 
 
 4 leading propofitions. 
 
 Theoq-, "Ylxt theory (fo to term it) of carpentry is founded 
 
 louiidcd on . j-n- ii .• r u • 1 r • _ 
 
 what ""^ ililtuict portions 01 mechanical Icience, name- 
 
 ly, a knowledge of the ftrains to which framings of 
 timber are expoied, aMi a knowledge of their relative 
 ftrength. 
 
 We fhall therefore attempt to bring into one point of 
 view the propofitions of mechanical icience that are 
 more immediately applicable to the art of carpentry, 
 and are to be found in various articles of our work, 
 particularly Roof and Strrngth of Materials. From 
 thefe propofitions we hope to deduce fuch principles as 
 fhall enable an attentive reader to comprehend diilindly 
 what is to be aimed at in framing timber, and how to 
 attain this objeft with certainty : and we fhall illuf- 
 trate and confirm our principles by examples of pieces 
 of carpentry which are acknowledged to be excellent 
 
 5 in their kind. 
 
 Compofi- The moft important propofition of general mechanics 
 folution of carpenter is that wnich exhibits the conipohtion 
 
 forces and refolution of forces ; and we beg our praftical rea- 
 
 ders to endeavour to form very diftinft conceptions of 
 it, and to make it very familiar to their mind. When 
 accommodated to their chief purpofes, it may be thus 
 expreffed : 
 
 I. If a body, or anv part of a body, be at once pref- 
 PlaleVin. Cgj jj, j},g ^^^ direaions AB, AC (fig. i ), and if 
 the intenfity or force of tliofe preffures be in the pro- 
 portion of thefe two lines, the body is affefted in the 
 fame manner as if it were preffed by a fingle force a£l- 
 ing in the dircftion AD, which is the diagonal of the 
 parallelogram ABDC formed by the two lines, and 
 whofe intenfity has the fame proportion to the intenfity 
 of each of the other two that AD has to AB or AC. 
 Such of our readers as havey?«,/;W the laws of mo- 
 tion, know that this is fully demonltrated. We refer 
 them to the article Mechanics, n° 5, &c. where it is 
 treated at fome length. Such as wifli for a very accu- 
 rate view of this propofition, will do well to read the 
 demonftration given by D. Bernoulli, in the firil vo- 
 lume of the Comment. Pelropol. and the improvement of 
 this demonllration by D'Alembert in his Opufcles, and 
 in the Comment. Taurinenf. The praftitioner in car- 
 pentry will get more ufcful confidence in the dodlrinc, 
 if he will Ihut his book, and verify the theoretical de- 
 
 6 monftrations by aftual experiments. They are remark. 
 Bluftrated ably eafy and convincing. Therefore it is our requeft, 
 mem''^"' ^^^ '^^^ artiil, who is not fo habitually acquainted with 
 
 the fubjeft, do not proceed further till he has made it 
 quite familiar to his thoughts. Nothing is fo condu- 
 eive to this as the a6\ual experiment j and fince this on- 
 
 N T R Y. 
 
 ly requires the trifling expence of two fmall pulleys and 
 a few yards of whipcord, we hope that none of our 
 pradical readers will omit it : They will thank us for 
 this injunftion. 
 
 2. Let the threads A </, AFi, and AE c (fig. 2.), 
 have the weights d, b, and c, appended to them, and 
 let two of the threads be laid over the pulleys F and E. 
 By this apparatus the knot A will be drawn in the di- 
 reiAions AB, AC, and AK. If the inin of the weights 
 I and c be greater than the fingle weight d, tlie alfem- 
 blage will o{ itfelf Icttle in a certain deterniined form ; 
 if you pull the knot A out of its place, it will always 
 return to it again, and will reft in no other pofition. 
 For example, if the three weights are equal, the threads 
 will always make equal angles, of 120 degrees each, 
 round the knot. If one of the weights be three pounds, 
 another four, and the third five, the angle oppofite to the 
 thread ftretchv'd by five pounds will always be lquaie,&.c. 
 When the knot A is thus in equilibrio, we mull infer, 
 that the aflion of the weight d^ in the direction A d, 
 is in direft oppofition to the combined aftion of i, in 
 the cireiJlion AB, and of c, in the diretlion AC. 
 Therefore, if we produce f/A to any point D, and 
 take AD to reprefcnt the magnitude of the force, or 
 preflurc exerted by the weight r/, tlie preflures exerted 
 on A by the weights b and c, in the dire£lions AB, 
 
 AC, are in fail equivalent to a prelfure afting in the 
 direftion AD, whofe intenfity we have reprefented by 
 
 AD. If we now meafure off by a fcale on AF and 
 AE the lines AB and AC, having the fame propor- 
 tions to AD that the weights b and c have to the weight 
 d, and if we draw DB and DC, we lliall find DC to 
 be equal and parallel to AB, and DB equal and paral- 
 lel to AC ; fo that AD is the diagonal of a parallelo- 
 gram ABDC. We fhall find this always to be the 
 cafe, whatever are the weights made ufe of ; only we 
 muft take care that the weight which we caufe to adl 
 without the intervention of a pulley be lels than the 
 iium of the other two : if any one of the weights ex- 
 ceeds the fum of the other two, it will prevail, and drag 
 them along with it. 
 
 Now, iince we know that the weight a' would jufl. 
 balance an equal weight g, pulling direftly upwards by 
 the intervention of the pulley G L and fince we fee that 
 it ju(l balances the weights h and^f, afting in the direc- 
 tions AB, AC, we mull infer, that the knot A is af. 
 feded in the fame manner by thofe two weights, or by 
 the fingle weight _§■ ; and therefore that two preJfureSf 
 OLling in the direSions, and it'ith the intenjilies, AB, AC, 
 are equivalent to a Jingle prejfure having the direBion and 
 proportion of AD. In hke manner, the preffures AB, 
 AK, are equivalent to AH, which is equal and op- 
 pofite to AC. Alfo AK and AC are equivalent to 
 AI, which is equal and oppofite to AB. 7 
 
 We fhall confidcr this combination of preffures a little (3onfidered 
 more particularly. more partU- 
 
 Suppofe an upright beam BA (fig. 3.) pufhed in*^ "^' 
 the direftion of its length by a load B, and abutting on 
 the ends of two beams AC, AD, which are firmly re- 
 filled at their extreme points C and D, which refl on 
 two blocks, but are nowife joined to them : thefe two 
 beams can refiil no way but in the directions CA, DA; 
 and therefore the preffures which they fuflaiu from the 
 beam BA are in the direiilions AC, AD. We wifli 
 to know how much each fuftains i Produce BA to £, 
 
 takiog
 
 C A R P E N T R Y. 
 
 taking AE from a fcalc of equal parts, to reprtfent the fentcd by the dotted lines in fig. 3. The (Iralns on 
 number of tons or pounds by which BA is preiTed. both tlie battens AD, AC, are now greatly increafcd. 
 Draw EF and EG parallel to AD and AC; then AF, The fame confcquences refult from an improper 
 
 meafured on the fame fcale, will give us the number of change of the polition of AC. If it is placed as in fig. 
 
 pounds by which AC is (trained or crulhed, and AG 8. the llrains on both are vailly increaled. In fliort, 
 
 will give the ftrain on AD. the rule is general ; tliat the mure open we make the 
 
 It deferves particular remark here, that tlie length angle againit which the piilh is exerted, the greater arc 
 
 of AC or AD has no influence on the llrain, arifing the drains which are brought on the flruts or tics which 
 
 from the thrull uf BA, while the directions remain the form the fides of the angle. 
 
 fame. The etFefts, however, of this ftrain are moditi- The reader may not readily conceive the piece AC 
 ed by the length of the piece on which it is exerted, of fig. 8. as fudaining a comprcffion ; for the weight 
 This llrain coniprelRs the beam, and will therefore com- B appears to hang from AC as much as from AD. 
 prefs a beam of double length twice as much. This But his doubts will be removed by confideiing whether 
 may change the form of tlie affemblage. If AC, for ex- he could employ a rope in place of AC. He cannot : 
 ample, be very much fhorter than AD, it will be much But AD may be exchanged for a rope. AC is there- 
 lets comprelTed : The line CA will turn about the cen- fore a ilrut and not a tit. 
 
 tre C, while DA will hardly change its pofition ; and In tig. 9. AD is again a ftrut, butting on the block 
 
 the angle CAD will grow more open, the point A fink- D, and AC is a tie : and the batten AC may be re- 
 
 ing down. Tlie artifl will find it of great confequence placed by a rope. While AD is comprefTed by the 
 
 to pay a very minute attention to this circumftance, and force AG, AC is ftretciicd by the force AF. 
 to be able to fee clearly the change of fluipe which ne- If we give AC the pofition reprcfented by the dotted 
 
 ceffarily refults from thefe mutual ftrains. He will fee lines, the coniprefliun of AD is now AG', and the force 
 
 in this the caufe of failure in many very great works. — Ilretching AC- is now AF' ; both much greater than 
 
 By thus changing fhape, ftrains are often produced in they were before. This difpofition is analogous to fig. 
 
 places where there were none before, and frequently of 8. and to the dotted lines in fig. 3. Nor will the young 
 
 the very worll kind, tending to break the beams artifl have any doubts of AC being on the flretch, if 
 
 acrofs, he confider whether AD can be replaced by a rope. 
 
 The dotted lines of this figure fhew another pofition It cannot, but AC may ; and it is tlitrefore not com- 
 
 of the beam AD'. This makes a prodigious change, prcffed, but ftretchcd. 
 
 not only in the ftrain on AD', but alfo in that ou AC. It» fig. lo. all the three pieces, AC, AD, and AB, 
 
 Both of them are much increafed ; AG is almoll are ties on the llretch. This is the complete inverfion 
 
 doubled, and AF is four times greater than before, of fig. 3.; and the dotted pofition of AC induces the 
 
 This addition was made to the figure, to fhew what fame changes in the forces AF', AG', as in fig. 3. 
 enormous ftrains may be produced by a very moderate Thus have we gone over all the varieties which can 
 
 force AE, when it is exerted on a very obtufe angle. happen in the bearings ot three pieces on one point. All 
 
 The 4th and 5th figures will affifl the moft uiiinflruft- calculations about the ftrength of carpentry are redu- 
 
 cd reader in conceiving how the very fame ftrains AF, ced to this cafe : for when more ties or braces ineet iu 
 
 AG, are laid on thefe beams, by a weight fimply hang- a point (a thing that rarely hippens), we reduce them 
 
 ing from a billet reiling on A, prefling hard on AD, to three, by fubftituting for any two the force which 
 
 and alfo leaning a Lttle on AC ; or by an upright piece refults from their combination, and then combining this 
 
 AE, joggled on the two beams AC, AD, and per- with another ; and fo on. 
 
 Ids 
 
 The young artift muft be particularly careful not to 
 miftake the kind of ftrain that is exerted on any piece 
 of the framing, and fuppofe a piece to be a brace which 
 is really a tie. It is very eafy to avoid all miftakes in 
 this matter by the following rule, which has no excep- 
 tion. 
 
 Take notice of the direction in which the piece a£ls Rule for 
 
 lorming the office of an ordinary king-poft. The read 
 er will thus learn to call off his attention from the means 
 by which the ftrains are produced, and learn to confider 
 them abftraftedly, merely as ftrains, in whatever fituation 
 he finds them, -and frcm whatever caufe they arife. 
 
 We prefume that every reader will perceive, that 
 the proportions of thefe ftrains will be precilely the 
 
 fame if every thing be inverted, and each beam be from which the ftrain proceeds. Draw a line in that ''''^'"K"'"'- 
 
 drawn or pulled in the oppofite diredtion. In the fame diredlion _/;•</»; the point on which the ftrain is exerted ;!-"-'^ r '^ '^' 
 
 way that we have fubftituted a rope and weight in fig. and let its lengtli (mcafured on fome fcale of equal prefTioii and 
 
 4. or a king-poft in fig. 5. for the loaded beam BA of parts) cxprefs the magnitude ot this adtion in pounds, cxteuCon. 
 
 fig. 3. we might have fubftituted the framing of fig. 6. hundreds, or tons. From its remote extremity draw 
 
 which is a very ufual pradice. In this framing, the lines parallel to the pieces on which the ftrain is excrt- 
 
 batten DA is ftretched by a force AG, and the piece ed. The line parallel to one piece will nccefilirily cut 
 
 AC is comprefTed by a force AF. It is evident that the other, or its diredlion produced : If it cut the piece 
 
 we may empfoy a rope, or an iron rod hooked on at D, itfelf, that piece is comprefted by the ftrain, and it is 
 
 in place of the batten DA, and the ftrains will be the performing the office of a ftrut or brace : if it cut its 
 
 fame as before. diredlion produced, the piece is ftretched, and it is a 
 
 This feemingly fimple matter is ftill full of inftruc- tie. In fhort, the ftrains on the pieces AC, AD, are 
 tion ; and we hope that the well-informed reader will to be eftimatcd in the diredlion of the points F and G 
 pardon us, though we dwell a little longer on it for the from the ftrained point A. Thus, in fig. 3. the up- 
 fake of the young artift. f'gl't piece BA, loaded with the weight B, preffes the 
 
 By changing the form of this framing, as in fig. 7. point A in the diredlion AE : fo does the rope AB 
 
 we produce the tame ftrains as in the difpofition repre- in the other figures, or the batten AB in fig. j. 
 
 In;
 
 i66 
 
 C A R P E 
 
 In general, if the ftraining piece is within the angle 
 fonned by the pieces which arc Ibained, the Rrains 
 which they fuftaiii are of the oppofite kind to that 
 which it exerts. If it be pufliing, they are drawing ; 
 but if it be within the angle formed by their direftions 
 ])roduced, the ftrains which they fuftain are of the fame 
 kind. All the three are either drawing or prefTing. If 
 the ftraining piece lie within the angle formed by one 
 piece and the produced direftion of the otlier, its own 
 llrain, whether compreffion or extenfion, is of the fame 
 kind with that of the moft remote of the other two, 
 and oppofite to that of the neareft. Thus, in fig. 9. 
 where AB is drawing, the remote piece AC is alfo 
 drawing, while AD is pulhing or rcfjiUng compreffion. 
 In all that has been faid on this fiibjett, we have not 
 fpoken of any joints. In the calculations with which 
 Ave are occupied at prefent, the refiftance of joints has 
 no Ihare ; and we muft not fuppofe that they exert any 
 force which tends to prevent the angles from changing. 
 The joints are fuppofed perfectly Hexible, or to be like 
 compafs joints; the pin of which only keeps the pieces 
 together when one or niore of the pieces draws or pulls. 
 The carpenter muft always fuppofe them all compafs 
 joints when he calculates the thruftsand draughts of the 
 ditlerent pieces of his frames. The ftrains on joints, 
 and their power to produce or balance them, are of a 
 9 different kind, and require a very different examination. 
 
 Ge^f^a!ex- Seeing that the angles which the {)ieces make with 
 prefli 11 (if g^^Vj other are of fuch importance to the magnitude 
 t'ude"iift".e 3'"'! ^^^ proportion of the excited ftrains, it is proper to 
 • ftraiu. find out fome way of readily and compendioufly con- 
 
 ceiving and expreffing this analogy. 
 
 In general, the ftrain on any piece is proportional to 
 the ftraining force. This is evident. 
 
 Secondly, the ftrain on any piece AC is proportional 
 to the fine of the angle, which the ftraining force makes 
 with the other piece direftly, and to the fine of the 
 angle which the pieces make with each other inverfely. 
 For it is plain, that the three prefTures AE, AF, 
 and AG, which are exerted at the point A, are in the 
 proportion of the lines AE, AF, and FE (becaufe FE 
 is equal to AG). But becaufe the fides of a triangle 
 are proportional to the fines of the oppofite angles, the 
 itrains are proportional to the fines of the angles AFE, 
 AEF, and FAE. But the fine of AFE is the fame 
 ■with the fine of the angle CAD. which the two pieces 
 AC and AD make with each other ; and the fine of 
 AEF is the fame with the fine of EAD, which the 
 ftraining piece BA makes with the piece AC. There- 
 fore we have this analogy, Sin. CAD : Sin. EAD =: 
 
 AE : AF, and AF = AE x4'."' ^^^■— Now the 
 
 Sin. CAD 
 
 fines of angles are moft conveniently conceived as deci- 
 mal fraftions of the radius, which is confidcred as uni- 
 ty. Thus, Sin. ^o" is the fame thing with 0,5, or i ; 
 and fo of others. Therefore, to have the ftrain on AC, 
 arlfing from any load AE afting in the direction AE, 
 multiply AE by the fine of EAD, and divide the pro- 
 duct by the fine of CAD. 
 
 This rule fticws how great the ftrains muft be when 
 the angle CAD becomes very open, approaching to 
 iSo degrees. But when the angle CAD becomes very 
 fmall, its fine (which Is our divifor) is alfo very fmall ; 
 and we ftiould expecf a very g-^eat quotient In this cafe 
 alfo. But we muftobferve, that in this cafe the fine of 
 
 N T R Y. 
 
 EAD is alfo very fmall; and this is our multiplier. In 
 fuch a cafe, the quotient cannot exceed unity. 
 
 But it Is liuiiecenary to confider the calculation by 
 the table", of fines more particularly. The angles are 
 feldom known any otlierwife but by drawing the figure 
 of the frame of carpciury. In this cafe, we can al- 
 ways obtain the meafures of the ftrains from the fame 
 fcale, with equal accuracy, by drawing the parallelo- 
 gram AFCG. 10 
 
 Hitherto we have confidered the ftrains excited at Strains pro. 
 A only as they afFeCl the pieces on which they are ex- 1'/''^'" '^f* "• 
 erted. But the pieces, in order to fuftain, or b^ fi'hjeft . r'l , 
 to, any ftrain, muft be fupported at their ends C and 
 D ; and we may confider them as mere intermediums, 
 by which thefe ftrains are made to aft on thofe points 
 of fupport : Therefore AF and AG are alfo mea- 
 fures of the forces which prefs or pull at C and D. 
 Thus we learn the fupports which muft be found for 
 thefe points. Thefe may be Infinitely various. We 
 fhall attend only to fuch as fomehow depend on the 
 framing Itfelf. n 
 
 Such a ftrufture as fig. 11. very frequently occurs, Aftion of 4 
 where a beam BA is ftrongly preffed to the end of an- jj"'"'"8 
 other beam AD, which is prevented, from yielding, 
 both becaufe it lies on another beam HD, and becaufe 
 its end D is hindered from fliding backwards. It is in- 
 diff^erent from what this prefTiiie ariles : we have re- 
 prefented it as owing to a weight hung on at B, while 
 B is withheld from yielding by a rod or rope hooked 
 to the wall. The beam AD may be fuppofed at full 
 liberty to exert all its prefture on D, as if it were fup- 
 ported on rollers lodged in the beam HD ; but the 
 loaded beam B \. prefFcs both on the beam AD and on 
 HD. We wifti only to know what ftrain is borne by 
 AD? 
 
 All bodies aft on each other in the direftion perpen- 
 dicular to their touching furfaces ; therefore the fup- 
 port given by HD is In a direftion perpendicular to it. 
 We may therefore fupply its place at A by a beara 
 AC, perpendicular to HD, and firmly fupported at C. 
 In this cafe, therefore, we may take AE, as before, to 
 reprefent the preft"ure exerted by the loaded beam, and 
 draw EG perpendicular to AD, and EF parallel to It, 
 meeting the perpendicular AC in F. Then AG is the 
 ftrain compreffing AD, and AF is the prellure on the 
 
 beam HD. 
 
 .11 
 It may be thought, that fince we aflume as a prin- The form 
 ciple that the mutual preffures of folid bodies are exert- of the abat- 
 ed perpendicular to their touching furfaces, this ba- ''"K J'""' 
 lance of preffures, in framings of timbers, depends on ?^"°^_ 
 the direftlons of their butting joints : but it does notj^n^;, 
 as will readily appear by confidering the prefent cafe. 
 Let the joint or abutment of the two pieces BA, AD 
 be mitred, in the ufual manner, in the direftion/ A/'. 
 Therefore, if A « be drawn perdendicular to A/, it 
 will be the direftion of the aftual pieffure exerted by 
 the loaded beam BA on the beara AD. But the re- 
 aftlon of AD, in the oppofite direftion A t, will not 
 balance the prefture of BA ; becaufe it is not in the 
 direftion precifely oppofite. BA will therefore Aide 
 along the joint, aud prefs on the beam HD. AE re- 
 prefents the load on the mitre joint A. Draw E e per- 
 pendicular to Af, -ind E/ parallel to it. The preffiirc 
 A£ will be balanced by the reaftlons e A and/.\ : or, 
 the ^prefture AE produces the preffures A e and A/; 
 
 of
 
 CARPENTRY. 
 
 167 
 
 of which A/ miifl be refilled by the beam HD, and 
 A ? by the beam AD. Tiie prelTurc A/ not being 
 perpendicular to I ID, cannot be fully refilled by it ; 
 becaufe (by our afl'umed principle) it reads only in 
 a dircSion perpendicular to its fuiface. Therefore draw 
 fp,fi parallel to HD, and perpendicular to it. The 
 prtfTure A/ will be refilled by HD with the force p A ; 
 but there is required another force ; A, to prevent the 
 beam BA from flipping outwards. This mud be furnifh- 
 ed by the rcaflioii of the beam DA. — In like manner, 
 the other force A e cannot be fully refilled by the beam 
 AD, or rather by tlie prop D, afling by the interven- 
 tion of the beam ; for the aclion (jf that prop is exert- 
 ed through the beam in the direction DA. The 
 beam AD, therefore, is preflcd to the beam HD by 
 the force A e, as well as by A/. To find what this 
 prefTure on HD is, draw eg perpendicular to HD,and 
 e parallel to it, cutting EG in r. The forces g A 
 and A will refill, and balance A e. 
 
 Thus we fee, that the two forces A e and A/, which 
 are equivalent to AE, are equivalent alfo to A ^, A i, 
 A 0, and A^. But becaufe A/and e E are equal and pa- 
 rallel, and E r andy"; are alfo parallel, as alfo e r and 
 J p, it is evident, that ;'/ is equal to r E, or to F, and 
 i A is equal to re, 01 to G^. Therefore the four forces 
 A_f, Ao, A/, A/', are equal to AG and AF. There- 
 fore AG is the comprtfrion of the beam AD, or the 
 force prefling it on D, and AF is the force prefling it 
 on the beam HD. The proportion of thele preffures, 
 therefore, is not afiefted by the form of the joint. 
 
 This remark is important; for many carpenters think 
 the form and direSion of the butting joint of great 
 importance ; and even the theorift, by not profecuting, 
 the general principle through all its confeq.uences, .may 
 be led into an error. The form of the joint is of no 
 importaiice, in as far as it affettsthe ilrains iii the direc- 
 tion of tlic beams ; but it is often of great confequence, 
 in refptct to its own firmnefs, and the efieil it may 
 have ill bruifing the piece on winch it adls, or being 
 ,, crippled by it. 
 Irigiri cf The fame compreffion of AB, and the f.ime tlinift on 
 le ftrain the point D by the intervention of AD, will obtain, in 
 " ^ ''^" whatever way the original prefTure on the end A i.s pro- 
 duced. Thus fuppofing that a cord is made fall at 
 A, and pulled in the diretlion AE, and with the lame 
 force, the beam AD will be equidly coinprefftd, ai;d 
 the prop D mull reaCl with the fame force. 
 
 But it often happens that the obliquity o^ the pref- 
 . fure on AD, inficad of comprtfliug it, tlrctche'; it ; 
 and we defire to know what tenfion it fuftains ? Of this 
 we have a familiar example in a common roof. Let 
 the two rafters AC, AD (fig. 12.), prefs on the tie- 
 beam DC. We may fuppofe the whole weight to prefs 
 vtttieally on the lidge A, as if a weiglit B were hung 
 on- there. We may reprefent this weight by the por. 
 tion A i of the vertical or plumb line, intercepted be, 
 tween the ridge and the beam. Then drawing /^yand 
 bg parallel to AD and AC, A^ and Ay" will reprefent 
 the prefl'ures on AC and AD. Produce AC till CH 
 be equal to Ay. The point C is forced out in this di- 
 redion, and with 3 force reprcfented by this line. As 
 this force is not perpendicularly acrofs the beam, it evi- 
 dently ilretches it ; and this extending force muft be 
 ■witlillcod by an equal force pulling it in the oppofite 
 direciion. This muft ariie from a finiiiar oblique thrull 
 
 of the oppofite rafter on the other end D. We con- 
 cern ourfelvcs only with this extenfion at prefent ; but 
 we fee that the cohefion of the beam does nothing but 
 fupply the balance to the extending forces. It muft 
 ftiil be fupported externally, that it may rcjij}, and, by 
 refifting obliquely, be llretched. The points C and 1) 
 are fupported on the walls, which they prefs in the di- 
 reftions CK and DO, parallel to A b. If we draw H K 
 parallel to DC, and HI [jarallel to CK (that is, to Ab), 
 meeting DC produced in I, it follows from the com- 
 pofition of forces, that the point C would be fupported 
 by the two forces KC and IC. In like manner, ma- 
 king DN = A ^, and completing the parallelogram 
 DMNO, the point D would be liipported by the forces ■• 
 
 OD and MD. If we draw g and//' parallel to DC, 
 it is plain that they are equal to NO and CK, while 
 A and Ak are equal to DO and CK, and A i is 
 equal to the fum of DO and CK (becaufe it is equal to 
 A + A k). 1 he weight of the roof is equal to its 
 vertical prefljre on the walls. 
 
 Thus we fee, that while a nrefliiie on A, in the di- 
 reftion A b, produces the ftrains Ay" and Ag, on the 
 pieces AC and AD, it alfo excites a ftrain CI or DM 
 in the piece DC. And this completes the mechaiiifin 
 of a frame ; for all derive their efficacy from the tri- 
 angles of which they are compofed, as will appear move 
 clearly as we proceed. 14 
 
 But there is more to be lear.ied .from this. . The^'".^"'*' 
 confideration of the ftrains on the two pieces AD and ? *■ Jf " " " 
 AC, by the aftion of a force at A, only fhewed them 
 as the means of propagating the fame ftrains in their 
 own direction to the points of fupport. But, by add- 
 ing the ftrains exerted in DC, we fee that the frame 
 becomes an intermedium, by which exertions may be 
 made on other bodies, in certain diredions and propt)r. 
 tiuns ; fo that this frame may become part of a niore 
 complicated one, and, as it were, an element oi its con- 
 ftitution. It is worth while to aleertain the proportion 
 of the preffures CK and DO, which are thus exerted 
 oil the walls. The fimilarity oi triangles gives the lol- 
 lowing analogies : 
 
 DO : DM = A i : i D 
 CI, or DM : CK = CA : Ab 
 Therefore DO : CK =Cb:b'D. 
 Or, the prejjurcs on the points C and D, In the d'ireSion of 
 the Jlrahnng force A b, are reciprocally proporlionul to ilie 
 portions ofViZl. intercepted by A b. 
 
 Alfo, fmce Ai is = DO + CK, we have 
 
 Ab:Cr&.=.Cb + iD (or CD) : i D, and 
 Ab : DO=.CD : iC. 
 
 In general, any two of the three parallel forces A /;, 
 DO, CK, are to each other in the reciprocal propor- 
 tion of the parts of CD, intercepted between their di- 
 redions and the direction of the third. 
 
 And this explains a. ftill more important office of tlie 
 frame ADC. If one of the points, tueli as D, be fiip- 
 ported, an external power afting at A, in tlie d rtCilou 
 Ab, and with an intenfity which may be n.eafured by 
 A b, may be fet in equlllb.io, with another acting at C, 
 in the diiedlion CL, oppofite to CK or A b, aiul wiil» 
 an intenfity reprefented by CK : for fince the ptrelfurc 
 CH is partly withftood by the force IC, or the firmi.ef) 
 of the beam DC fupported at D, the force KC will 
 complete the balance. ■ Wiien we do not attend to the 
 fuppi.rt at D., wc conceive llic force Al to be lala.iced 
 
 by
 
 i68 
 
 C A R P E 
 
 15 
 
 by KC, or KC to be balanced by A b. And, in like 
 manner, we may negleft the fupport or force aiSing at 
 A, and confider the force DO as balanced by CK. 
 It becomcj Thus our frame becomes a lever, and we are able to 
 a lever. trace the interior mechanical procedure which gives it 
 its efficacy : it is by the intervention of the forces of 
 cohefion, whicJi conneft the points to which the exter- 
 nal forces are applied with the fupported point or ful- 
 crum, and witli each other. 
 
 Thele llrains or prcdiires A b, DO, and CK, not be- 
 ing in the direttions of the beams, may be called tranf- 
 •verfe. We fee that by their means a frame cf carpen- 
 try may be confidered as a iulid body: b>it the example 
 vliich brought this to our view is too limittd for ex- 
 plaining llie efficacy whieh may be given to fuch con- 
 ftrudions. We fliall therefore give a general propofi- 
 tion, which will more diftinflly explain the procedure 
 of nature, and enable us to trace the llrains as they are 
 propagated through all the parts of the moll complica- 
 ted framing, finally producing the exertion of its mott 
 jg dillant points. 
 General We prefume that the reader is now pretty well habi- 
 
 propofi- tuated to the conception of the llrains as they are pro- 
 *"'°' pagated along the lines joining the points of a frame, 
 
 and we Hiall therefore employ a very limple figure. 
 
 Let the llrong lines ACBD (fig. iv) reprefent a 
 frame of carpentry. Suppole that it is pulled at the 
 point A by a for?e aiiling in the diredion AE, but 
 that it rells on a fixed point C, and that the other ex- 
 treme point B is held. back by a power which refills in 
 the direftion BF : It is required to determine the pro- 
 portion of the llrains excited in its different parts, the 
 proportion of the external prelTures at A and B, and 
 the prelTurc which is produced on the obftacle or ful- 
 crum C ? 
 
 It Is evident that each of tbe external forces at A 
 and B tend one way, or to one fide of the frame, and 
 that each would caufe it to turn round C if the other 
 did not prevent it; and that if, notwithftanding their ac- 
 tion, it is turned neither way, tlie forces in atlual exer- 
 tion are in equillbrio by the intervention of the frame. 
 It is no lefs evident that thefe forces concur in prefTing 
 the frame on the prop C. Therefore, if the piece CD 
 were away, and if the joints C and D be perfeiflly flexi- 
 ble, the pieces CA,CB would be turned round the prop 
 C, and the pieces AD, DB would alfo turn with them, 
 and the whole frame change its form. This ftiews, 
 by the way, and we delirc it to be carefully kept in 
 mind, that the firmnefs or HifFaefs of framing depends 
 entirely on the triangles bounded by beams which are 
 contained In it. An open quadrilateral may always 
 change its fliape, the fides revolving round the angles. 
 A quadrilateral may have an infinity of forms, without 
 any change of Its fides, by merely puftiiiig two oppo- 
 fite angles towards each other, or drawing them afun- 
 der. But when the three fides of a triangle are deter- 
 mined, its Ihape is alfo invariably determined ; and if 
 two angles be held fall, the third cannot be moved. It 
 is thus that, by inferting the bar CD, the figure be- 
 comes unchangeable ; and any attempt to change It by 
 applying a force to an angle A, immediately excites 
 forces of attratlion or repulfion between the particles 
 of the Huff which form its fides. Thus it happens, in 
 the prefent Inllance, that a change of fliape is prevented 
 i>y the bar CD, The power at A prefles its end againft 
 
 N T R Y. 
 
 the prop; and in doing this it puts (he bar AD on the 
 ftretch, and alfo the bar DB. Their places might there- 
 fore be fupplied by cords or metal wires. Hence it 13 
 evident that DC is comprell'ed, as is alfo AC : and, for 
 the fame reafon, CB is alio in a Hate of compreflion ; 
 for either A or B may be confidered as the point that 
 is impelled or withheld. Therefore DA and DB arc 
 llretched, and are refilling with attradlive forces. DC 
 and CB are comprefled, and are refilling with repulfive 
 forces. DB is alfo ailing with repulfive forces, being 
 comprefled in like manner: and thus the fupport of 
 the prop, combined with the firmnefs of DC, puts the 
 frame ADBC into the condition of the two frames in 
 fig. 8 and fig. 9. Therefore the external force at A 
 is really in equillbrio witli an attracling force afting in 
 the diredllon AD, and a repulfive force ai£ling In the 
 diredtion AK. And fince all tlie connefting forces are 
 mutual and equal, the point D Is pulled or drawn In the 
 diredlion DA. The condition of the point B is fimi- 
 lar to that of A, and D is alfo drawn in the direftion 
 DB. Thus the point D, being urged by the forces in 
 the direftlons DA and DB, prefles the beam DC on 
 the prop, and the prop refills in the oppofite direftion. 
 Therefore the line DC is the diagonal of the parallelo- 
 gram, whofe fides have the proportion ot the forces 
 which conneft D with A and B. This is the prin- 
 ciple on which the reft of our inveftigation proceeds. 
 We may take DC as the reprefentation and meafure of 
 their joint effect. Therefore draw CH, CG, parallel 
 to DA, DB. Draw HL, GO, parallel to CA, CB, 
 cutting AE, BF in L and O, and cutting DA, DB 
 In I and M. Complete the parallelograms ILKA, 
 MONB. Then DG and AI are the equal and oppo- 
 fite forces which conneft A and D ; for GD := CH, 
 = AI. In like manner DH and BM are the forces 
 which conneft D and B. 
 
 The external force at A is In immediate equillbrio 
 with the combined forces, connecling A with D and 
 with C. AI is one of them : Therefore AK Is the 
 other ; and AL is the compound force with which 
 the external force at A is In immediate equilibrium. 
 This external force is therelore equal and oppofite to 
 AL. In like manner, the external force at B Is equal 
 and oppofite to BO ; and AL is to BO as the exter- 
 nal force at A to the external force at B. The prop 
 C refifts with forces equal to thofe which are propagated 
 to it from the points D, A, and C. Therefore It re- 
 fills with forces CH, CG, equal and oppofite to DG, 
 DH ; and it refills the comprefiions KA, NB, with- 
 equal and oppofite forces C /■, C ti. Draw kl, n pa- 
 rallel to AD, BD, and draw C /Q^, C P : It Is plain 
 that /■ CH / is a parallelogram equal to KAIL, and that 
 C / is equal to AL. In like mianner C is equal to 
 BO. Now the forces Ci, CH, exerted by the prop, 
 compofe the force C / ; and C n, CG compofe the force 
 C 0. Thefe two forces C /, C are equal and parallel 
 to AL and BO ; and therefore they are equal and op- 
 pofite to the external forces acting at A and B. But 
 they are (primitively) equal and oppofite to the pref- 
 fures (or at leaft the compounds of the preflures) exert- 
 ed on the prop, by the forces propagated to C from 
 A, D, and B. Therefore the prelfures exerted on the 
 prop are the fame as If the external forces were applied 
 there in the fame direftions as they are applied to A 
 and B. Now if we make CV, CZ equal to C / and C 0, 
 
 and
 
 CARPENTRY. 
 
 and complete tlie parallelogram CVYZ ; it is plain that blenis of liis art. He alfo learns, from this propofition, 
 
 the force YC is in equilibrio with /C and oC. There- how to afcertain the ilraiiis that arc produced, without 
 
 fore the preflures at A, C, and B, are fuch as would his intention, by pieces which he intended for other of- 
 
 balance if applied to one point. fices, and which, by their tranfvcrfc aftion, put hij work 
 
 Laftly, in order to determine their proportions, draw in hazard. In fliort, this propofition is liic key to the 
 
 CS and CR perpendicular to DA and DB. Alfo draw fcience of his art. 
 
 169 
 
 A J, B /"perpendicular to CQjind CP ; and draw Cg, 
 C /' perpendicular to AE, BF. 
 
 The triangles CPR and BP/ are fimilar, having a 
 common angle P, and a right angle at R andy". 
 
 In like manner the triangl's CQS and AQjf are fi- 
 milar. Alfo the triangles CHR, CGS are fimilar, by 
 reafon of the equal angles at H and G, and the right 
 angles at R and S. Hence we obtain the following 
 analogies : 
 
 Co : CP = 0« : PB, = CG : P3 
 CP : CR z= PB :/B 
 
 CR: CS = ■ CH:CG 
 
 CS : CQj= Ad: A(X_ 
 
 CQj C / = AQj K /, = AQj CH. 
 
 Therefore, by equality, 
 Co : C/ = AJ:/B 
 
 orBO:AL=r Cg.Cl. 
 
 Tiiac is, the external forces are reciprocally propor- 
 tional to the perpendiculars drawn from the prop on 
 the lines of their diredlion (a). 
 
 This propofition (fufliciently general for our pur- 
 pofe) is fertile in confequences, and furnilhes many ufe- 
 ful inilruftions to the artift. The drains LA, OB, 
 CY, that are excited, occur, in many, we may lay in all, 
 framings of carpentry, whether for edifices or engines, 
 and are the fources of their efficacy. It is alio evident, 
 
 18 
 
 We would now counfel the artifl, afier he has made 
 the tracing of the firains and thrulls through the v?.- 
 rlous parts of a frame familiar to his mind, and even 
 amufcd himfelf with fome complicated fancy framings, 
 to read over with care the articles Stsfngth of Alole- 
 r'uils and Roof in the Encyclnpitdia Bnlanmca. He 
 will now conceive its doftrincs much more clearly than 
 when he was coniidcring them as abltratt theories. I'he 
 mutual a6lion of the woody fibres will now be eallly 
 comprehended, and his confidence in the rcfults will be 
 greatly increafed. 
 
 There is a propofition (n° 19. in the article Roop) nerifion of 
 which has been called in queftion by feveral very intelli- a nfj'uted 
 gent perfors; and they fay that Bi'lldor has dcmonllra-!"''' '^'"^ 
 ted, in his Science des Ingeniecrs, that abeam f-rfn- l"Jlni^^'" 
 ly fixed at both ends is not twice as lliong as when 
 fimply lying on the props, and that its llrength is in- 
 creafed only in the proportion of 2 to ^ ; and they fup- 
 port this determination by aliil-of experiments reci- 
 ted by Belldor, which agree predftly with it. Belidor 
 alfo fays that Pitot had the fame refult in his experi- 
 ments. Thefe are refpedlable authorities : but IJeli. 
 dor's reafoning is any thing but demonftratlon ; and 
 his experiments are defcribed in fuch an imperfeil man- 
 ner, that we cannot build much on them. It is not 
 faid in what manner the battens were fecured at the 
 
 that the doftrine of the tranfverfe fl:rength of timber is ends, any farther than that it was by cLei'itlets. If by 
 
 this word is meant a trefsle, we cannot conceive how 
 they were employed ; but we fee it foinetlmes nfed for 
 a wedge or key. If the battens were wedged in the 
 holes, their refinance to fraitiire inay be made whvt we 
 pleafe : they may be loofe, and therefore refllt little 
 more than when finiply laid on the props. They may 
 See Strencth of Materials, be (and probably were) wedged very fall, and bruifed 
 
 or crippled. 
 
 Our propofi.tion mentioned diftlnflly the fecurity 
 given to the ends of the beams. They were mortifed 
 into remote pofts. 0\xr precife meaning was, that they 
 were fimply kept from rifing by thefe mortifes, but at 
 full liberty to bend up between E and I, and between 
 Y G 
 
 contained in this propofition; for every piece of timber 
 may be confidered as an affemblage of parts, conneftfd 
 by forces which aft in the direftion ot the hues winch 
 join the ftrained points on the matter which lies be- 
 tween thofe points, and alfo aft on the rcl!: of the mat- 
 ter, exciting thofe lateral forces which produce tiie in 
 flexibility of the whole. 
 Encycl. 
 
 Thus it appears that this propofition contains the 
 principles which direft the artiff to frame the mod 
 powerful levers ; to fecure uprights by fiiores or bra- 
 ces, or by ties and ropes ; to fecure fcafFoldings for the 
 ereftion of fpires, and many other moft delicate pro- 
 
 SupPL. Vol. I. Part I. 
 
 ( \) The learned reader will perceive, that this analogy is precifely the fame with that of forces which are in 
 equilibrio by the intervention of a lever. In faft, this whole frame of carpentry is nothing elfe than a built or 
 framed lever in equilibrio. It is afting in the fame manner as a folid, which occupies the whole figure comprcf- 
 fed in the frame, or as a body of any fize and fiiape whatever that will admit the three points of application 
 A, C, and B. It is always in equilibrio in the cafe firft dated ; becaufe the prelTure produced at B by a force 
 applied to A is always fuch as balances it. The reader may alfo perceive, in this propofition, the analyfis or tra- 
 cing of thofe internal mechanical forces which are indifpenfably requifite for the funftions of a lever. The me- 
 chanicians have been extremely puzzled to find a legitimate demonftratlon of the equilibrium of a lever ever fiiice 
 the days of Archimedes. Mr Vince has the honour of firft demonftrating, moft ingenioufly, the principle aflu- 
 med by Archimedes, but without fufficient ground, for his demonftratlon : but Mr Viuce's demonllration is on- 
 ly a putting the mind into that perplexed ftate which makes it acknowledge the propofition, but without a 
 clear perception of its truth. The difficulty has proceeded from the a'bftraft notion of a lever, conceivino- it as 
 a mathematical line — inflexible, without reflcfting how it is inflexible — for the very fource of this indifpenfable 
 quality furnifhes the mechanical conneftion between the remote preflures and the fulcrum ; and this fupplies the 
 demonftratlon (without the lead difficulty) of the defperate cafe of a ftraight lever urged by parallel forces. See 
 Rotation, n° 11. Encycl.
 
 xyo 
 
 CARPENTRY. 
 
 15 
 
 The btd 
 
 manner of 
 
 framing 
 
 purlins. 
 
 G and K. Our afTeition was not made from theory alone 
 (although we think the reafoiiiiig incontrovertible), but 
 was agreeable to numerous experiments made in thofe 
 precife circumftances. Had we mortifed the beams 
 lirmly into two very ftout polls, which could not be 
 drawn nearer to each other by bending, the beam would 
 have borne a muc/j greater weight, as we have verified 
 by experiment. We hope that the toUowhig mode of 
 conceiving this cafe will remove all doubts. 
 
 Let LM be a long beam (fig. 14.) divided into fix 
 equal parts, in the points D, B, A, C, E. Let it be 
 firmly fupported at L, B, C, M. Let it be cut thro'igh 
 at A, and have compafs-joints at B -ind C. Let FB, 
 GC be two equal uprights, refting on B and C, but 
 without any connexion. Let AH be a fimilar and 
 equal piece, to be occafionally applied at the feam A. 
 Now let a thread or wire AGE be extended over the 
 piece GC, and made fall at A, G, and E. Let the 
 fame thing be done on the other fide of A. If a weight 
 be now laid on at A, the wires AFD, AGE will be 
 ftrained, and may be broken. In the inftant of fraflure 
 we may fuppofe their flrains to be reprefented by A/ 
 and Ag. Complete the parallelogram, and An is the 
 magnitude of the weight. It is plain that nothing is 
 concerned here but the cohefion of the wires ; for t!ie 
 beam is fawed through at A, and its parts are perfeftly 
 moveable round B and C. 
 
 Inftead of this procefs apply the piece AH below A, 
 and keep it there by ftraining the fame wire BHC over 
 it. Now lay on a weight. It mull prets down the 
 ends of BA and CA, and caufe the piece AH to drain 
 the wire BHC. In the inftant of frafture of the fume 
 wire, its refiftance H3 and H r mud be equal to Af 
 and A^, and the weight h H which breaks them mult 
 be equal to A a. 
 
 Laftly, employ ail the three pieces FB, AH, GC, 
 v.'ith the fame wire attached as before. There can be 
 no doubt but that the weight which breaks nil the four 
 wires muft be -zz a \-\- h, or twice A a. 
 
 The reader cannot but fee that the wires perform the 
 very fame office with the fibres of an entire beam LM 
 held faft in the four holes D, B, C, and E, of fome up- 
 right pods. 
 
 In the experiments for verifying this, by breaking 
 llender bars of ime deal, we get complete demonftration, 
 by meafuring the curvatures produced in the parts of 
 the beam thus held down, and comparing them with the 
 curvature of a beam fimply laid on the props B and C: 
 and there are many curious inferences to be made from 
 thefe obfervations, but we have not room ior them in 
 this place. 
 
 We may obferve, by the way, that we learn from this 
 cafe, that purlins are able to carry twice the load when 
 notched into the rafters that they carry when mortifed 
 into them, which is the mod ufual manner of framing 
 them. So would the binding joids of floors ; but this 
 would double the thicknefs of the flooring. But this 
 method fhould be followed in every poflible cafe, fuch 
 as bread fummers, lintels over feveral pillars, &c. Thefe 
 fhould never be cut off and mortifed into the fides of 
 every upright ; numberlefs cafes will occur which fhew 
 the importance of the maxim. 
 
 V/e muft here remark, that the proportion of the 
 
 . fpdces BC and CM, or BC and LB, has a very fenfible 
 
 effeiSt on the ilrength of the beam BC ; but we have 
 
 not yet fatisfied our minds as *-o the rationak of this ef- 
 fcft. It is undoubtedly connedled with the fcrpentinc 
 form of the curve of the beam before frafture. This 
 (hould be attended to in the condruftion of the fprings 
 of carriages. Thefe are frequently fupported at a middle 
 point (and it is an excellent practice), and there is a 
 certain proportion which will give the eafieft motion to 
 the body of the carriage. We alfo think that it is con- 
 nected with that deviation from the bed theory obfer- 
 vable in Buffon's experiments on various lengths of the 
 fame fcantling. The fovce of the beams diminidied 
 much more than in the inverfe proportion of their 
 lengths. 
 
 We have feen that it depends entirely on the pofitionTiiTare in 
 of the pieces in refpedt of their points of ultimate fup- j;eneral bet- 
 port, and of the direftiou of the external force which '^'' '^*n 
 produces the drains, whether any particular piece is in ' 
 
 a date of extenfion or of compreffion. The knowledge 
 of this circumftance may greatly influence us in the 
 choice of the cundrudtion. In many cafes we may fub- 
 ftitute flender iron rods for mafTive beams, when the 
 piece is to a£t the part of a tie. But we muft not in- 
 vert this difpofition ; for when a piece of timber afts as 
 a ftrut, and is in a Hate of compreffion, it is next to 
 certain that it is not equally compreffible in its oppofite 
 fides through the whole length of the piece, and that 
 the compreffing force on the abutting joint is not act- 
 ing in the mod equable manner all over the joint. A 
 very trifling inequality in either of thefe circumdanccs 
 (efpecially in the firft) will comprefs the beam more on 
 one fide than on the other. This cannot be without 
 the beam's bending, and becoming concave on that fide 
 on *hich it is molt compretfed. When this happens, 
 the frame is in danger of being crufhed, and foon going 
 to ruin. It is therefore indifpenfably neceffary to make 
 ufe of beams in all cafes where ftruts are required of 
 contlderable length, rather than of metal rods of flender 
 dimenhons, unlefs in fituat ions where we can elfetlually 
 prevent their bending, as in trufiing a girder internally, 
 where a caft iron ftrut may be firmly cafed in it, fo as 
 not to bend in the Inialleft degree. \.\\ cafes where the 
 preffures are enormous, as in the very oblique ftruts of 
 a centre or arch frame, we muft be particularly cautious 
 to do nothing which can facilitate the compreffion of 
 either fide. No mortifcs fhould be cut near to one fide ; 
 no lateral preffure, even the flightelt, fhould be allowed 
 to touch it. We have feen a pillar of fir i 2 inches long 
 and one inch in feftion, when loaded with three tons, 
 fnap in an inftant when preffed on one fide by 16 pounds, 
 while another bore 4 J- tons without hurt, becaufe it was 
 inclofed (loofely) in a flout pipe of iron. 
 
 In fuch cafes of enormous compreffion, it is of great 
 importance that the compreffing force bear equally on 
 the whole abutting furfaces. The German carpenters 
 are accuftomed to put a plate of lead over the joint. 
 This prevents, in fome meafure, the penetration of the 
 end fibres. Mr Perronet, the celebrated French ar- 
 chiteft, formed his abutments into arches of circles, the 
 centre of which was the remote end of the ftrut. By 
 this contrivance the unavoidable change of form of the 
 triangle made no partial bearing of either angle of the 
 abutment. This always has a tendency to fplinter off 
 the heel of the beam where it preffes ftrongeft. It is a 
 very judicious practice. 
 
 When circumftances allow^it, we ftiould rather em- 
 ploy
 
 CARPENTRY. 
 
 ploy ties than ftriits for fecuiing a beam againft lateral 
 itrains. When an upright pillar, fiich as a flag ftaff, a 
 niaft, or the uprights of a very tall fcaflolding, are to he 
 fliored up, the ilependciice is more e;;rtaiii on thofe 
 braces that are ftretchcd by the (train than on thofe 
 which are comprefled. The fcaffolding of the iron 
 bridge near Su\iderlaiid had feme ties very judicioudy 
 dilpofed, and others with lels judgment. 
 
 We (liould proceed to confider the tianfverfe drains 
 
 8. Laftly, the tranfvcrfe drain on any feAion, occa- 
 fioued by a force applied obliquely, is diminiflied in the 
 proportion of the fine of the angle which the direftion 
 of the force makes with the beam. Thus, if it be in- 
 clined to it in an angle of thirty degrees, the ftrain is 
 one half of the drain occafioned by the fame force a&- 
 ing peipendictllarly. 
 
 On the other hand, the relative strfngth of a 
 beam, or its power in any particular fedbOn to rcfiil: 
 
 J7I 
 
 us they afledl the various parts of a frame of carpentry ; any tranfverfe ftrain, is proportional to the abfolute co- 
 
 but we have very little to add to what has been faid al- hefion of the feftion direc\ly, to the diftance of its 
 
 ready in the article Strength of Mii/triah (Encycl.), centre of eftort from the axis of frafture direitly, and 
 
 and in the article Roof. What we (liall add fn this ar- to the diftance from the drained point inverfely. 
 ticle will find a place in our occafional remarks on dif- Thus in a reftangular fcdtion of the beam, of which A 
 
 fercnt works. It may, however, be of ufe to recal to is the breadth, rf the depth (that is, the dimenfion in 
 
 the reader's memory the following propofitions. the diredlion of the draining force), meafured in inches, 
 
 I. When a beam AB (fig. 15.) is firmly fixed at the and /"the number of pounds which one fquare inch will 
 
 end A, and a draining force adls perpendicularly to its juft fupport without being torn afunder, we mud have 
 
 conceruinK length at any point B, the drain occafioned at any fee- fXiXd', proportional to w X C B (fig. ly.) Or, 
 
 the r lativtjjgjj q between B and A is proportional to CB, and fXbXd', multiplied by fome number m, depending on 
 
 lrlfm"=' " may therefore be reprefentea by the produdl WxCB ; the nature of the timber, mud be equal to w X CB. 
 
 feeneral 
 theoicms 
 
 beams. 
 
 that is, by the produdl of the number of tons, pounds, 
 &c. which mealure the draining force, and the number 
 of feet, inches, &c. contained in CB. As the loads on 
 a beam are eafily conceived, we ftiall fubftitute this for 
 any other draining force 
 
 2. If the drain or load is uniformly diftributed along 
 any part of the beam lying beyond C (that is, further 
 from .A ), the drain at C is the fame as if the load were 
 all collefted at the middle point of that part ; for that 
 point is the centre of gravity of the load. 
 
 3. The ftrain on any fedlion D of a beam AB 
 
 (fig. 16.) reding freely on two props A and B,- is 
 
 ^ AD xDB /f o o IP I- 
 
 "wX ^-— (lee Rqof, n° 19. and Strength of 
 
 AB 
 
 Materials, n" 92, &c. Encycl.) Therefiire, 
 
 4. The drain on the middle point, by a force applied 
 there, is one fourth of the drain which the fame force 
 would produce, if applied to one end of a beam of the 
 fame length, having the other end fixed. 
 
 5. The-«jTain on any feftion C of a beam, reding on 
 two props A and B, occafioned by a force applied per- 
 pendicularly to another point D, is proportional to the 
 reftangle of the exterior fegments, or is equal to 
 
 ACxDB 
 
 Or, in the cafe of the ftdlion C of fig. 16. that ii 
 drained by the force lu applied at D, we mull have 
 
 ^fUJ^ ^ AC XDB 
 
 m Xfb d' = lu X . ,,; 
 
 •^ AB 
 
 Thus if the beam is of 
 
 i (fee Strength of Ma- 
 fi£ 
 
 9 
 
 Therefore we have 
 
 wX 
 
 AB 
 
 Therefore 
 
 The drain at C occafioned by the preffure on D, is 
 the fame with the ftrain at D occafioned by the fame 
 prelfure on C. 
 
 6. The ftrain on any fedlion D, occafioned by a load 
 uniformly diffufed over any part EF, is the fame as if 
 the two parts ED, DF of the load were colledled at 
 their middle poin,ts e andf. Therefore 
 
 The drain on any part D, occafioned by a load uni- 
 formly diftributed over the whole beam, is one-half of 
 the ftrain that is produced when the fame load is laid on 
 at D ; and 
 
 The ftrain on the middle point C, occafioned by a 
 load uniformly diftributed over the whole beam, is the 
 lame which half that load would produce if laid on 
 at C. 
 
 7. A beam fupported at both ends on two props B 
 and C (fig- 14.) will carry twice as much when the 
 
 found oak, m is very nearly 
 
 teriah, 11° 116. Encycl.) 
 ACXCB 
 
 = ^ ^— 7Cb — 
 
 Hence we can tell the precife force tv which any fec- 
 tion C can juft refift when that force is applied in any 
 way whatever. For the above-mentioned formula give* 
 
 iu 1=. ^ , for the cafe reprefented by ficr 1 r. But 
 
 9CB '^ / o J 
 
 the cafe reprefented in fig. 16. having the ftraining 
 
 force applied at D, gives the ftrain at C ( = w ) ■=. f 
 
 9ACXCB' 
 
 Example. Let an oak beam, four inches fquare, red 
 
 freely on the props A and B, feven feet apart, or 84. 
 
 inches. What weight will it juft fupport at its middle 
 
 point C, on the fuppofition that a fquare inch rod will 
 
 juft carry 16,000 pounds, pulling it afunder ? 
 
 m, r 1 , 160CO X 4 X 16 X 84, 
 The rormula becomes iu z= 3 Z_ 
 
 86oifio:o 9X42X42 
 
 orw=: r-T — > = 5418 pounds. This is very 
 
 15070 
 
 near what was employed in Buffon's experiment, v.hich 
 
 was 531 2. 
 
 Had the ftraining force adted on a point D, halfway 
 
 between C and B, the force lufRcient to break the beam 
 
 . (^ ij u 16-00X4X16X84 o ^ !U 
 
 at C would be = — i Z = 1C856 lbs. 
 
 9 X 42 X 2f 
 Had the beam been found red fir, we muft have ta- 
 ken y^ 10,000 nearly, and m nearly 8 ; for a)tl/0jgh 
 fir be lefs cohefive than oak in the proportion of 5 to 8 
 nearly, it is lefs comprelfible, and its axis of fracture is 
 therefore nearer to the concave fide. 
 
 Having confidered at fufficient length the ftrains Of joints, 
 of different kir.ds which arife from the form of the 
 parts of a frame of carpentry, and the dircdtion of 
 ends beyond the props are kept from rifing, as it will the externa! forces whicli adl on it, whether conlidercd 
 carry when it reiis loofely on the props. as impelling or as fupporting its different parts, we muft 
 
 y 2 now
 
 172 
 
 CARPENTRY. 
 
 now proceed to confider the means by which this form 
 is to be fccured, and the conneflions by which thofe 
 ftrains are excited and conimiinicateJ. 
 
 The joinings practifcd in carpentry are almoft infi- 
 nitely various, and eacli has advantages vvhlcti make it 
 preferable in fonie circuinllances. Many varieties are 
 employed merely to pleafe the eye. We do not con- 
 cern ourfelves with theft : Nor fliall v.e conilder thofe 
 which are only employed in conneftirg imall works, 
 ;nid can never ai)pear on a grtnt fcale : yet even in fome 
 of thefe, the fliiil of the carpenter may be difcovered by 
 his choice ; for in all cafes it is wife to make every, even 
 the fmallcfl, part of his work as ftrong as the materials 
 will admit. He will be particnlarly attentive to the 
 changes which will n^cefurily happen by the flirinking 
 of timber as it dries, and will confider what dimenfions of 
 his framings will be affefted by this, and what will not ; 
 and will then difpofe the pieces which are lefs effential 
 to the ftrength cf the whole, in fuch a manner that 
 their tendency to fhrink iliall be in the fame direAion 
 with the flirinking of the whole framing. If he do 
 otherwife, the feams will widen, and parts will be fplit 
 afunder. He will difpofe his boardings in fuch a man- 
 ner as to contribute to the ftiffnefs of the whole, avoid- 
 ing at the fame time the giving them pofitions which 
 will produce lateral ftrains on trufs beams which bear 
 great prefTures; recollecting, that although a imgle board 
 has little force, yet many united have a great deal, and 
 may frequently perform the office of very powerful 
 flruts. 
 
 Our limits confine us to the joinings which are moft 
 eifential for connefting the parts of a fingle piece of a 
 frame when it cannot be formed of one beam, either for 
 want of the neceffary thickncfs or length ; and the 
 joints for connefting the different fides of a trulTed 
 J, frame. 
 Of building Much ingenuity and contrivance has been heftowed 
 up beams. q[, the manner of building up a great beam of many 
 thickneifcs, and many fingular methods are praftlfed as 
 great noftrums by different artlif s : but when we con- 
 fider the manner in which the cohefion of the fibres 
 performs its ofSce, we will clearly tee that the fimpleft 
 are equally effetf ual with the moft refined, and that they 
 are lefs apt to lead us into falfe notions of the ftrength 
 of the afTemblage. 
 
 _ .,^+ Thus, were it required to build up a beam for a 
 
 Building up , ' . ,T - , . r 
 
 a girder cr great lever or a girder, lo that it may act nearly as a 
 
 lever. beam of the fame fize of one log — it may either be 
 
 ^5 done by plain joggling, as in fig. 17. A, or by fcarfing. 
 
 in ficr. 17. B or C. If it is to act as a lever, ha- 
 
 Joggling 
 
 io fcarfing. ving the gudgeon on the lower fide at C, we believe 
 that moft artifis will prefer the form B and C ; at leaft 
 this has been-the cafe with nine-tenths of thofe to whom 
 we have propofcd the queftion. The beft informed on- 
 ly hefitated ; but the ordinary artifts were all confident 
 in its fuperiorlly ; and we found their views of the 
 matter very coincident. They confider the upper 
 piece as grafping the lower in its hooks ; and feveral 
 imagined that, by driving the one very tight on the 
 other, the beam would be ftronger than an entire log : 
 but if we attend carefully to the Internal procedure in 
 the loaded lever, we fliall find the upper one clearly the 
 ftrongeft. If they are formed of equal logs, the upper 
 one is thicker than the other by the depth of the jog- 
 
 gling or fcarfing, which we ftippofc to be the fame in 
 both ; confequently, if the cohefion of the fibres in the 
 intervals Is able to bring the uppermoft filaments into 
 full aAion, the form A is ftronger than B, In the {pro- 
 portion- of the greater diftance of the upper filaments 
 from the axis of the fratfure : this may be greater than 
 the difference of the thicknefs, if the wood is very com- 
 prefTible. If the gudgeon be in the middle, the effeft, 
 both of the joggles and the feaifings, is confiderably 
 diminilhed ; and if It is on the upper fide, the fcarf. 
 ings atf in a very different way. In this fituation, if 
 the loads on the arms are alfo applied to the upper fide, 
 the joggled beam is ftill more fuperior to the fcarfed 
 one. This will be beft undtrllood by refolvlng it in ima- 
 gination into ;i truffed frame. But when a gudgeon is 
 thus put on that fide of the lever which grows convex 
 by the ftrain, it is ufual to conntdt it with the reft by 
 a powerful ftrap, which embraces the beam, and caufes 
 the oppofite point to become the refilling point. This 
 greatly changes the internal aftions of the filaments, 
 and, in fome meafure, brings it into the fame ftate as 
 the firft, with the gudgeon below. Were it pofTible to 
 have the gudgeon on the upper fide, and to bring the 
 whole into adion without a ftrap, it would be the 
 Ifrongeft of all ; becaufe, in general, the refiftance to 
 compreffion is greater than to extenfion. In every 
 fituation the joggled beam has the advantage ; and it is 
 th* eafieft executed. 
 
 We may frequently gain a confiderable acceflion of 
 ftrength by this building up of a beam ; efpecially if 
 the part which is ftretched by the ftrain be of oak, and 
 the other part be fir. Fir being fo much fuperior to 
 oak as a pillar (if Muffchenbroek's experiments may be 
 confided in), and oak fo much preferable as a tie, this 
 conftru6tion feems to unite both advantages. But we 
 fhall fee much better methods of making powerful le- 
 vers, girders, jfc. by truffing. 
 
 Obferve that the efficacy of both methods depends 
 entirely on the difiiculty of caufing the piece between 
 the crofs joints to Aide along the timber to which it 
 adheres. Therefore, if this be moderate, it is wrong 
 to make the notches deep ; for as foon as they are fo 
 deep that their ends have a force fuflicient to pufh the 
 ilice along the line of junftion, nothing is gained by 
 making them deeper; and this requires a greater ex- 
 penditure of timber. 
 
 Scarfings are frequently made oblique, as in fig. 18. 
 but we imagine that this is a bad practice. It begins 
 to yield at tlie point, where the wood is crippled and 
 fplintered off, or at leaft bruifed out n little : as the 
 preflure increafes, this part, by fqueezing broader, caufes 
 the folid parts rife to a little upwards, and gives them 
 fome tendency, not only to pufh their antagonifls along 
 the bale, Lut even to tear them up a little. For fimi- 
 lar reafons, we difapprove of the iavourite praftlce of 
 many artifts, to make the angles of their fcarfings acute, 
 as in fig. ip. This often caufes the two pieces to tear 
 each other up. The abutments fhould always be per- 
 pendicular to the direftions of the preffures. Left it 
 fhould be forgotten in its proper place, we may extend 
 this injunftion alfo to the abutments of different pieces 
 of a frame, and recommend it to the artift even to at- 
 tend to the (hrinking of the timbers by drying. When 
 two timbers abut obliquely, the joint ftiould be moft 
 
 full
 
 IVe nuift 
 
 full at the obtufe angle of the end ; becaufe, by dryinj^', 
 that angle grows more obtufo, and the beam would then 
 be in danger of fplintering off at tlie acute angle. 
 
 It IS evident that the nicell work is inditpenfably 
 ntwcrlL'e necelfary in building up a beam. The parts mull abut 
 [00 hard. ^^^ ^^^.j^ qjIj^.,- completely, and the i'mallcll play or void 
 takes away the whole efficacy. It is ulual to give the 
 butting joints a fmall taper to one fide of the beam, fo 
 that they may require moderate blows of a maul to 
 force them in, and the joints may be perfeiStly clote when 
 the external furfaees are even on each fide of the beam. 
 But we mull not exceed in the leall degree ; for a very 
 taper wedge has great force ; and if we have driven the 
 pieces together by very heavy blows, we leave the whole 
 in a Hate of violent llrain, and the abutments are per- 
 haps ready to fplinter off by a fmall addition of pref- 
 fure. This !s like too fevere a proof for artillery; 
 which, though not fuffitient to burft the pieces, has 
 weakened them to fuch a degree, that the llrain of or- 
 dinary fervice is fufficient to complete the fradlure. 
 The tL-orkman is tempted to exceed in this, becaufe it 
 fmooths off and conceals all uneven fcams ; but he mull 
 be watched. It is not unufual to leave fome abutments 
 open enough to admit a thin wedge reaching through 
 the beam. Nor is this a bad pradtice, if the wedge is 
 of materials which is nut comprclfed by the driving or 
 the flrain of fervice. Iron would be preferable for this 
 purpofe, and for the joggles, were it not that by its too 
 great hardnefs it cripples the fibres of limber to fome 
 diftanee. In confequence of this, it often happens that, 
 in beams which are fubjefled to dcfultory and fudden 
 ftrains (as in the levers of reciprocating engines), the 
 joggles or wedges widen the holes, and work tlicmfelves 
 loofe : Therefore flcilful engineers never admit them, and 
 indeed as few bolts as poflilile, for the faine reafon : but 
 when refining a fleady or dead pull, they are not foim- 
 proper, and are frequently ufed. 
 
 Beams are buiit up not only to incrcafe their dinien- 
 Cons in the direftion of the llrain (which we have hi- 
 therto called their depth), but alfo to increafe their 
 breadth or the dimenfions perpendicular to the flrai 
 
 CARPENTRY.' 173 
 
 Fig. 21. exhiWts anotlier method. The two halves »9 
 of the beam arc tabled info each other in the fame man ^^ ^^'^' 
 ner as in fig. 17. It is plain that this will not be af.'""'^'"^ 
 fefted by the unequal fwelling or fhrinking, becaufe 
 this is inlenfible in tiie direftion of the fibres ; but when 
 bent in tlie direction a 6, the beam is weaker than fig. 
 2C. bent in the diredion ef. Each half of fig. 20. has, 
 in every part of its length, a tliicknefs greater than half 
 the thicknefs of tl'.e beam. It is the c^jntrary in the 
 alternate portions i;f the halves of fig. 21. AVhen one 
 of them is bent in the diredion AB, it is plain that it 
 drags the other with it by means of the crofs butments 
 of its tables, and there can be no longitudinal Hiding. 
 But unlefs the work is accurately executed, and each 
 hollow completely filled up by the table of the other 
 piece, there"will be a lateral Hide along the crofs joints 
 fufHcient to compenfate for the curvature ; and this will 
 hinder the one from comprcinng or llretching the other 
 in conformity to this curvature. jo 
 
 'I he impcrfediou of this method is fo obvious, that Its imper. 
 it has feldom been pradf ifed : but it has been combined '•'^"'"' 
 with the other, as is reprefentcd in fig. 22. where the 
 beams are divided along the middle, and the tables in 
 each half are alternate, and alternate alfo with the 
 tables of the other lialf. Thus i, 3, 4, are prominent, 
 and 5, 2, 6, are depreffed. Tiiis conilrudion evidently 
 puts a flop to both fides, and obliges every part of 
 both pieces to move together, a b and c d fhow fec- 
 tions of the built-up beam correfponding to AB and 
 CD. 
 
 No more is intended in this praftfce by any intelli- 
 gent artitt, than the caufing the two pieces to ad to- 
 gether in all their parts, although the llrains may be un- 
 equally dillributcd on them. Thus, in a built-up gir- 
 der, the binding joints are frequently monifed into very- 
 different parts of the two fides. But many feem to 
 aim at making the beam flronger than if it were of one 
 piece ; and this inconfiderate projeft has given rife to 
 many ivhimfical modes of tabling and fcarfing, which 
 we need not regard. ,j 
 
 The praftice in the Britifli dock-yards is fomewhat Brieifli 
 
 We fometimes double the breadth of a girder which different from any of thefe methods. The pieces are ""=''""' 5 
 
 ij thought too weak for its load, and where we mnfl 
 
 not iucreafe the thicknefs of the flooring. The mafl of 
 
 J. a great fhip of war muft be made bigger athwartfhip, as 
 
 iuildingof well as fore and aft. This is one of the nicefl pro- 
 
 nalb. bleras of the art ; and profeffinn-.d men are by no means 
 
 agreed iu their opinions about it. We do not prefume 
 
 to decide ; and fhall content ourfclves with exhibiting 
 
 the different methods. 
 
 The niofl obvious and natural method is that (liewn 
 in fig. 20. It is plain that (independent ot the con. 
 nedion of crofs bolts, which are ufed in them all when 
 the beams are fquare) the piece C cannot bend in the 
 diredion of the plane of the figure without bending the 
 piece D along with it. This method is much ufed in 
 the French navy ; but it is undoubtedly imperfed. 
 Hardly any two great trees are of equal quality, and 
 fwcU and fhrink alike. If C fhrinks more than I), the 
 feather of C becomes loofe in the groove wtoiight in D 
 to receive it ; and when the beam bends, the parts can 
 ilide on each other like the plates of a coach fpring ; 
 and if the bending is in the diredion e f, there is no- 
 thing to hinder this Aiding but the bolls, which foon 
 work, themfelves loofe in the bolt-holes. 
 
 as 
 lethod 
 ed in ihc 
 encli 
 3vy, 
 
 tabled as in fig 22. but the tables are not llun paralle. 
 lopipeds, but thin prifms. The two ouHvard joints or 
 vifible feams are flraight lines, and the table n" I. rifes 
 gradually to its grcatefl thicknefs in the axis. In like 
 niauQCf, the hollow 5 for receiving the oppofite table, 
 finks gradually from the edge to its greatell depth in 
 the axis. Fig. 23. reprefents a fedion of a round piece 
 of timber built up iri this way, where the full line . 
 EFGH is the fedion correfponding to AB of fig. 22. 
 and the dotted line EGFH is the fedion correfpond- 
 ing to CD. 
 
 This conftrudion, by making the external feani 
 flraight, leaves no lodgment for water, and looks much 
 fairer to the eye : but it appears to us that it does 
 not give fuch firm hold when the maft is bent in the 
 diredfion EH. The exterior parts are moll flretched 
 and moll comprefled by this bending ; but there is 
 hardly any abutment in the exterior parts of thefe 
 tables. In the very axis, where the abutment is the 
 firmetl, there is little or no difference of extenfion and 
 compreffion. 
 
 But this conftrudion has an advantage, which we 
 imagine much more than compenfates for thefe imper- 
 
 fe<9;ions5.
 
 J 74 C A R P E 
 
 /e(?Sif!n=!, at leafl in tVic particular cafe of a round maft: 
 it will draw togcthc-r hy hooping incomparably better 
 than any of the others. If the cavity be made fome- 
 what too (hallow for the prominence of the tables, and 
 if this be done uniformly along the whole length, it 
 will make 3 fomewhat open feam ; and this opening 
 can be regulated with the utmoil exaftnefs from end 
 to end by the plane. The heart of thofe vaft trunks 
 is very fenfibly fofter than the exterior circles : There- 
 lore, when the whole is hooped, and the huops hard 
 driven, and at confidcrable inter\'als between each fpell 
 — we are confident that all may be coinprelTed till the 
 feam difappears ; and then the whole makes one piece, 
 ii:iich rtronger than if it were an original log of that 
 lize; bccaufe the middle has become, by compreffion, as 
 folid as the crull, which was naturally firmer, and refifted 
 farther compreffion. We verified this beyond a doubt, 
 by hooping a built ftick of a timber which has thi^ in- 
 equality of firmnefs in a remarkable degree, and it was 
 nearly twice as ftrong as another of the fame fize. 
 
 Our mattmakers are not without their fancies and 
 whims ; and the manner in which our mails and yards 
 are generally built up, is not near fo fimple as fig. Z2.: 
 but it confdts of the fame effential parts, afting in the 
 very fame manner, and derives all its efficacy from the 
 ,1 principles which are here employed. 
 rAM^nded This conftrudtion is particularly fuifed to the fitua- 
 -with ptcu- tjpfi anjl ofBce of a (hip's maft. It has no bolts ; or, 
 ■^ ^'^^ " at leafl, none of any magnitude, or that make very im- 
 portant parts of its conftruftion. The m.oft violent 
 f*rains perhaps that it is expofcd to, is that of twifting, 
 when the lower yards are clofe braced up by the force 
 of many men afting by a long lever. This form refifts 
 a twill with peculiar energy : it is therefore an excel- 
 lent method for building up a great (haft for a mill. 
 The way in which they are ufually built up is by redu- 
 cing a central log to a polygonal prifm, and then filling 
 it up to the intended fize by planting pieces of timber 
 along its fides, either fpiking them down, or cocking 
 them into it by a feather, or joggling them by (lips of 
 hard wood funk into the central log and into the (lips. 
 A'. B. Joggles of elm are fometimes ufed in the middle 
 of the laige tables of mafts ; and when funk into the 
 firm wood near the furface, they muft contribute much 
 to the llrength. But it is very neceflary to employ 
 wood not much harder than the pine ; otherwife it 
 will foon enlarge its bed, and become loofe ; /or the 
 timber of thefe large trunks is very foft. 
 
 The moft general reafon for piecing a beam is to in- 
 creafe its length. This is frequently neceffary, in order 
 to procure tie-beams for very wide roofs. Two pieces 
 mull; be Icarfed together. — Numberlefs are the modes 
 f/f doing this ; and almofl every mailer carpenter has 
 his favourite nollrum. Some of them are very ingeni- 
 ous : But here, as in other cafes, the moft fimple are 
 ."■' commonly the ftrongeft. We do not imagine that any, 
 nietho'.'is r>f t'' moft ingenious, is equally ftrong with a tie confift- 
 fcarni^g. ing of two pi> ces of the fame fcantling laid over each 
 other for a certain length, and firmly bolted together. 
 We acknowledge that this will appear an artlefs and 
 clumfy tie-beam ; but we only fay that it will be 
 ftronger than any that is more artificially made up of 
 the fame thicknefs of timber. This, we imagine, will 
 appear fufficiently certain. 
 
 The fimplcft and moft obvious fcarfing (after the 
 
 N T R Y. 
 
 one now mentioned) is that reprefented in fig. 24. n" t. 
 and 2. If confidered mertlv as two pieces of wootj 
 joined, it is plain that, as a tic, it has but half the 
 ftrtngth of an entire piece, fuppofing that the bolls 
 (which arc the only connedtions) are faft in their holes. 
 N° 2. requires a bolt in the middle of the fcarf to give 
 it that ftrength ; and, in every other part, is weaker on 
 one iide or the other. 
 
 But the bolts are very apt to bend by the violent 
 ftrain, and require to be ilrengthened by uniting their 
 ends by iron plates ; in which cafe it is no longer a 
 wooden tie. The form of n° i. is better adapted to 
 the ofRce of a pillar than n' 2. ; efpecially if its ends 
 be formed in the manner tliewn in the elevation n^ 3, 
 By the fally given to the ends, the (carf refifts an effort 
 to bend it in that diredlion. Befides, the form of n' 
 7. is unfuitable for a poft ; becaufe the pieces, by fii- 
 ding on each other by the prelTure, are apt to fplinter 
 off the tongue which confines their extremitv. 
 
 Fig. 25. and 26. exhibit the moft approved form of 
 a fcarf, whether for a tie or for a poft. The key re» 
 prefented in the middle is not eftentially neceiTary ; the 
 two pieces might fimply meet fquare there. This form, 
 without a key, needs go bolts (although they ftrength- 
 cn it greatly) ; but, if worked very true and clofe, and 
 with fquare abutments, will hold together, and will re- 
 fift bending in any direflion. But the key is an inge- 
 nious and a very great improvement, and will force the 
 parts together with perfeft tightULfs. The fame pre- 
 caution muft be obferved that we mentioned ori*ano- 
 ther occafion, not to produce a conftant internal ftrain 
 on the parts by ovei'driving the key. The form of fig. 
 25. is by far the beft; becaufe the triangle of 26. is 
 much eafier fplintered o(f by the ftrain, or by the key, 
 than the fquare wood of 25. It is far preferable for 
 a poft, for the reafon given when fpeaking of fig. 24. 
 n= 1. and n^ 2. Both may be formed with a fally at 
 the ends equal to the breadth of the key. In this 
 ftiape, fig. 25- is vaftly well fuited for joining the parts of 
 the long corner ports of fpires and orher wooden towers. 
 Fig. 25. n" 2 differs from n" 1. only by having three 
 keys. The principle and the longitudinal ftrength are 
 the fame. The long fcarf of n' 2. tightened by the 
 three keys, enables it to refill a bending much better. 
 
 None of thefe fcarfed tie-beams can have more than 
 one-thiid of the ilrength of an entire piece, unlefs with 
 the alTiftance of iron plates ; for if the key be made 
 thinner than one-third, it has lefs than one-third of the 
 fibres to pull by. 
 
 We are confident, therefore, that when the heads of 
 the bolts are conncfted by plates, the fimple form of 
 fig. 24. n° I. is ftronger than thofe more ingenious 
 fcarfings- It may be ilrengthened againft lateral bend- 
 ing by a little tongue, or hy a fally ; but it cannot 
 have both. 
 
 The ftrongeft of all methods of piecing a tie-beam 
 would be to fet the parts end to end, and grafp them 
 between other pieces on each fide, as in fig. 27. This 34 
 is what the (hip-carpenter czlh fijhing a beam ; and is a Fi1''"g"* 
 frequent pra&ice for occafional repairs. Mr Perronet *"'■ 
 ufed it for the tie-beams or ftretchers, by which he con- 
 nected the oppofite feet of a centre, which was yield- 
 ing to its load, and had pufiied afide one of the piers 
 above four inches. Six of thcle not only withilood a 
 ftrain of i8co tons, but, by wedging behind them, he 
 
 brought
 
 CARP 
 
 Brought the feet of the trufs 2t inches nearer. The 
 ftretchers were ^t] inches by 1 1 of found oak, and could 
 have withllood three times that ttrain. Mr Perronet, 
 fearing that the great lengtli of the bolts employtd to 
 conncft the beams of tliefe ftretchers would expofe 
 them to the rilk of bending, fcarfed the two fide pieces 
 into the middle piece. The fcarfing was of the trian- 
 gular kind ("Trail de Jupiter), and only an inch deep, 
 each face being two feet long, and the bolt pafTed 
 through clofe to the angle. 
 
 In piecing the pump rods, and other wooden ftretch- 
 ers of great engines, no dependence is had on fcarfing; 
 and the engineer connects every thing by iron ftraps. 
 We doubt the propriety of this, at leaft in cafes wliere 
 the bulk of the wooden conneftion is not inconvenient. 
 Thefe obfervations muil fuffice for the methods employ- 
 ed for connecting the parts of a beam ; and we now 
 proceed to confider what are more ufually called the 
 
 35 joints of a piece of carpentry. 
 
 quare Where the beams ftand fquare with each other, and 
 
 Jints, {|,j ftrainf are alfo fquare with the beams, and in the 
 
 plane of the frame, the common mortife and tenon is 
 the moil perfect junftion. A pin is generally put 
 through both, in order to keep the pieces united, in 
 oppofition to any force which tends to part them. 
 Every carpenter knows how to bore the hole for this 
 pin, fo that it (hall draw the tenon tight into the mor- 
 tife, and caufe the fhoulder to butt clofe, and make 
 neat work ; and he knows the rifle of tearing out the 
 bit of the tenon beyond the pin, if he draw it too 
 much. We may juft obferve, that fquare holes and 
 pins are much preferable to round ones for this pur- 
 pofe, bringing more of the wood into aftion, with lefs 
 tendency to fplit it. The fhip carpenters have an in- 
 gcnious method of making long wooden bolts, which 
 do not pafs completely through, take a very faft hold, 
 though not nicely fitted to their holes, which tliey mull 
 
 36 not be, left they fiiould be crippled in driving. They 
 oitail (.3II Jt jQxtail ivtdgirg. They ftick into the point of 
 
 ^ ■*' the bolt a very thin wedge of hard wood, fo as to pro- 
 jeft a proper difta.ice ; when this reaches the bottom 
 of the hole by driving the bolt, it fplits the end of it, 
 and fquetzes it hard to the fide. This may be prac- 
 tifed with advantage in carpentry. It the ends of the 
 mortife are widened inwards, and a thin wedge be put 
 into the end of the tenon, if will hzve the fame etfcft, 
 and make the joint equal to a dovetail. But this rifcs 
 the fplitting the piece beyond the fhoulder of the te- 
 non, which would be unfightly. This may be avoided 
 as follows : Let the tenon T, fig. 28. have two very 
 thin wedges a and c ftuck in near its angles, projedling 
 equally ; at a very fmall diftance within thefe, put in 
 two ftiorter ones b, il, and more within thefe if nccef- 
 fary. In driving this tenon, the wedges a and c will 
 take firft, and fph't off a thin flice, which will eafily 
 bend without breaking. The wedges b, d, will act 
 next, and have a finiilar tffeft, and the others in fucr 
 ceflion. The thickncfs of all the wedcres taken toee- 
 ther muft be equal to the enlargement of the mortife 
 toward the bottom. 
 
 When the ftrain is traufvcrfe to the plane of the two 
 fceams, the principles Inid dov^n in n" 85, 86. of the ar- 
 ticle Strcsgih of Materials, will direft the aitift in 
 placing his mortife. Thus the mortife in a girder for 
 receiving the tenon of a binding joift of a floor ftiould 
 
 ENTRY. 175 
 
 be as near the upper fide as poffible, becaufe the girder 
 becomes concave on that fide by the ilrain. But as 
 this cxpofes the tenon of the binding joill to the rifk 
 of being torn off, we are obliged to mortife farther 
 down. The form (fig. 29.) generally given to this 
 joint is extremely judicious. The Hoping part a b gives 
 a very firm fupport to the additional bearing e.d, with- 
 out much weakening of the girder. This form flionld 
 be copied in every cafe where the ftrain has a fimllar 
 direftion. ,« 
 
 The joint that moft of all demands the careful atten- Oblique 
 tion of the artift, is that which conntdls the ends of "'^''"'^^'^'"^ 
 beams, one of which pufhes the other very obliquely, ^'" "• 
 putting it into a ftaie of extenfion. The moft iainiJiar 
 inftance of this is the foot of a rafter preffing on the 
 tie-beam, and thereby drawing it away from the other 
 wall. When the direftion is very oblique (in which 
 cafe the extending ftrain is the greateft), it is difficult 
 to give the foot of the rafter luch a hold of the tie- 
 beam as to bring many ot its fibres into the proper ac- 
 tion. There would be little diificulty if we could al- 
 low the end of the tie-beam to projeft to a fmall dif- 
 tance beyond the foot of the rafter : but, indeed, the 
 dimenfions which are given to tie-beams, for other rea- 
 fons, are always fufficient to give enough of abutment 
 when judicioufly employed. Unfortunately this joint 
 is much expofed to failure by the effefts of the wea- 
 ther. It is much expofed, and . frequently pcrifties by 
 rot, or becomes fo ioft and friable that a very fmall 
 force is fuificlent, either for pulling the filaments out of 
 the tie-beam, or for crufiiing them together. We are 
 therefore obliged to fecure it with particular attention, 
 and to avail ourfelves of every circumllance of con- 
 ftruftion. 
 
 One is naturally difpofed to give the rafter a deep 
 hold by a long tenon ; but it has been frequently ob- 
 ierved in old roofs that fuch tenons break oft. Fre- 
 quently they are oblcrved to tear up the wood that is - 
 above them, and pulh their way through the end of the 
 tie-beam. This, in all probability, arifes from the tail 
 fagging of the roof, by the comprefllon of the rafters • 
 and of the head of ihe king-poll, '['he head of the rat- 
 ter defcends, the angle with the tic-beam i? diniiailhed 
 by the rafter revolving round its ilcp in the tie-beam. 
 By this motion the heel or inner angle of the rafter be- 
 comes a fuicium to a very long and powerful lever much 
 loaded. Tlie tenon is the other arm, very lliort, and 
 being Hill frelh, it is therefore very powerful. It tiierc- 
 fore forces up the wood that is above it, tCLiring it out 
 from between the cheeks of the mortife, and theri pullics 
 it along. Carpenters have therefore given up long te- 
 nons, and giv^e to the toe of the tenon a (hape which 
 abuts firmly, in the direftion of the thruftj on the folid . 
 bottom of the mortife, which is will fuppoitcd on the 
 under fide by the wall-plate. This form has the farther 
 advantage of having no tendency to tear up the end of ' 
 the mortife. This form is reprcfentcd in fig. ^o. The 
 tenon has a fmall portion a b cut perpendicular to thc 
 furfate of the tie-beam, and the reft be is peipeiidicular 
 to the rafter. 
 
 But if the tenon is not fufflciently ftr'ong (and it is 
 rot fo llrong as the rafter, which is thought not to he 
 ftronger than is neceffary), it will be crufaed, and then 
 the rafter will fliade out along the furface of the bcsm. 
 It ij therefore necelTary to Citll in the ;iffifta.ice of tlic 
 
 vvlujle,-
 
 176 
 
 C A R P E 
 
 whole rafter. It is in tliis diftributioii of the Iliai.i 
 among the various abutting parts that the varieties of 
 joints and tlieir merits ehiefly conlilL It would be 
 endlefs to defcribc every nollrum, and wc fliall only men- 
 o tion a few that are moll gen;;rally approved of. 
 Mofl ap. ihe aiin in fig. 31. is to make the abutments exaft- 
 
 prored ly perpendicular to the thruils. It does this very pre- 
 forms, cifely ; and the ftare which the tenon and the (houlder 
 have of the whole may be what we pleafe, by the por- 
 tion of the beam tint we notch down. If the wall-plate 
 lie duly before the heel of the rafter, there is no rifk of 
 ftraining the tie acrofs or breaking it, becaufe the thruft 
 is made diredl to that point where the beam is fupport- 
 ■ed. The aftion is the fame as again II the joggle on the 
 head or toot of a king-poft. We have no doubt but 
 that this is a very effectual joint. It is not, however, 
 much praftifed. It is faid that the Hoping feam at the 
 (houlder lodges water; but the great reafon feems to be 
 a fecret notion that it weakens the tie-beam. If we 
 conllder the diredlion in which it acts as a tie, we muft 
 acknowledge that this form takes the bell method for 
 bringing the whole of it into aclion. 
 
 Fig. 32. exhibits a form that is more general, but 
 certainly worfe. What part of the thruft that is not 
 borne by the tenon afls obliquely on the joint of the 
 flioulder, and gives the whole a tendency to rife up and 
 ilide outward. 
 
 The (lionlder joint is fometimes formed like the dot- 
 ted line abctlefg of fig. 32. This is much more 
 agreeable to the true principle, and would be a very 
 perfeft method, were it not that the intervals hd and 
 i/f are fo fliort that the little wooden triangles iv c/, 
 def, will be cafily pufli:-d off their bales h d, df. 
 
 Fig. 33. feems to have the moll general approbation. 
 It is the joint recommended by Price (page 7.), and 
 copied into all books ot carpentry as the true joint for a 
 rafter foot. The vifible Ihoulder-joiut is flufli with the 
 upper furface of the tie-beam. The angle of the tenon 
 at the tie nearly bifedls the obtufe angle formed by the 
 rafter and the beam, and is therefore fomewhat oblique 
 to the thruft. The inner (houlder ar is nearly perpen- 
 dicular to b d. The lower angle of the tenon is cut off 
 horizontally as at e d. Fig. 34. is a feclion of the beam 
 and rafter foot, (hewing the different Ihoulders. 
 
 We do not perceive the peculiar merit of this joint. 
 The effeft of the three oblique abutments ab, a c, e d, 
 is undoubtedly to make the whole bear on the outer 
 end of themortife, and there is no other part of the tie- 
 beam that makes immediate refiftance. Its only advan- 
 tage over a tenon extending in the direction of the 
 thruft is, that it will not tear up the wood above it. 
 Had the inner flioulder had the form e c i, having its 
 face ic perpendicular, it would certainly have atted 
 more powerfully in ftretching many filaments of the tie- 
 beam, and would have had much lefs tendency to force 
 out the end of the mortife. The little bit c i would 
 have prevented the Aiding upwards along e c. At any 
 rate, the joint a 3 being fludi with the beam, prevents 
 any fcnfible abutment on the fhoulder ac. 
 
 Fig. 33. n^ 2. is a Ampler, and in our opinion a pre- 
 ferable, joint. We obferve it praftifed by the raoft 
 eminent carpenters foi all oblique thruils ; but it furely 
 employs lefs of the cohefion of the tie-beam than might 
 be ufed without weakening 'it, at leatt when it is fup- 
 ported on the other fide by the wall-plate. 
 
 N T R Y. 
 
 Fig. 33. no 3. is alfo much pra£lifcd by the firft car* 
 
 penters. 
 
 Fig. 35. is propofed by Mr Nicholfon (page 65.) zs 
 preferable to fig. ^}. i\'' ^. becaufe the abutment of the 
 inner part is better iupported. This is certainly the 
 cafe; but it fuppofes the whole rafter to go to the bot- 
 tom of the focket, and the beam to be thicker than the 
 rafter. Some may think that this will weaken the beam 
 too much, when it is no broader than the rafter is thick; 
 in which cafe they think that it requires a deeper focket 
 than Nicholion has given it. Perhaps the advantages 
 of Nicholfon's conftruftion may be had by a joint like 
 fig- 35- "'2-. , 
 
 Whatever is the form of thefe butting joints, great Circum- 
 care (hould be taken that all parts bear alike, and the dances to 
 artift will attend to the magnitude of the different fur-*''^ attend- 
 faces. In the general compreffion, the greater furfaces' "'' 
 will be lefs compreffed, and the fmaller will therefore 
 change moft. When all has fettled, every part (lioidd 
 be equally clofe. Becaufe great logs are moved with 
 difficulty, it is very troublefome to try the joint fre- 
 quently to lee how the parts fit ; therefore we muft ex- 
 peft lefs accuracy in the interior parts. This (hould 
 make us prefer thofe joints whofe efficacy depends chief- 
 ly on the vifible joint. 
 
 It appears from all that we have faid on this fubjeft, 
 that a very fmall part of the cohefion of the tie-beam is 
 fufficient for withftanding the horizontal thruft of 'a 
 roof, even though very low pitched. If therefore no 
 other ufe is made of the tie-beam, one much flenderer 
 may be ufed, and blocks may be firmly fixed to the 
 ends, on which the rafters might abut, as they do on 
 the joggles on the head and foot of a king-poll. Al- 
 though a tie-beam has commonly floors or ceilings to 
 carry, and fometimes the workfhops and ilore-rooms of 
 a theatre, and therefore requires a great icantling, yet 
 there frequently occur in machines and engines very ob- 
 lique llretchers, which have no other ofirce, and are ge- 
 nerally made of dimenfions quite inadequate to their fi- 
 tuation, often containing ten times the neceffary quan- 
 tity of timber. It is therefore of importance to afcer- 
 tain the moft perfedl manner of executing fuch a joint. 
 We have directed the attention to the principles that 
 are really concerned in the effefrl. In all hazardous 
 cafes, the carpenter calls in the affiftance of iron llraps; 
 and tliey are frequently neceffary, even in roofs, not- 
 withftanding this fuperabundant ilrength of tlietie-beam. 
 But this is generally owing to bad conftruftion of the 
 wooden joint, or to the failure of it by time. Straps 
 will be confidered in their place. 
 
 There needs but little to be faid of the joints at a 
 ioggle worked out of folid timber ; they are not near 
 fo difficult as the laft. When the fize of a log will al- 
 low the joggle to receive the whole breadth of the a- 
 butting brace, it ought certainly to be made with a 
 fquare flioulder ; or, which is ftill better, an arch of a 
 circle, having the other end of the brace for its centre. 
 Indeed this in general will not fenfibly differ from a 
 ftraight line perpendicular to the brace. By this circu- 
 lar form, the fettling of the roof makes no change in 
 the abutment ; but when there is not fufficient Ituff for 
 this, we muft avoid bevel joints at the flioulders, becaufe 
 thefe always tend to make the brace Aide off. The 
 brace in fig. ^6. muft not be joined as at a, but as at 
 i, ox foEie equivalent manner. Obferve the joints at 
 
 the
 
 C A R P E 
 
 the head of the main pofts of Drury Line theatre, fig. 
 40 D. 
 
 itting When the very obh'que aftion of one fide of a frame 
 
 iits. of carpentry docs not extend but coniprcfs the piece on 
 
 Vv-hich it abuts (as in fig. 11.), there is no dilllcully in 
 the joint. Indeed a joining is unnectfTary, and it ij 
 enough that the pieces abut on each other; and we 
 have only to take care that the mutual prelVure be equal- 
 ly borne bv all the parts, and that it do not produce la- 
 teral prelTilres, which may caufe one of the pieces to 
 Aide on the buttir,'^ joint. Avery (light mortife and 
 tenon is fufficient at the joggle of n king-pod with a 
 rafter or llraining beam. It is bell, in general, to make 
 the butting plain, bil'cfting the angle formed by the 
 fides, or clfe perpendicular to one of the pieces. In 
 iig. 36. n" z. where the llraining beam a h cannot flip 
 away from the prcfiure, the joint a is preferable to h, or 
 indeed to any uneven joint, which never fails to produce 
 very unequal prefTures on the different parts, by which 
 ^, fome are crippled, others are fpliiitered off, ic. 
 iredliors When it is necefiary to employ iron llraps for llrength- 
 r placing ening a joint, a confiderable attention is necefiary, that 
 ■» '^"1 *• we may place them properly. The firft thing to be deter- 
 mined is the direftion of the ilniin. This is learned by 
 the obfervations in the beginning of this article. We 
 mull then refolvethis ftrain into a drain parallel to each 
 piece, and another perpendicular to it. Then the drap 
 which is to be made fad to any of the pieces muil be fo 
 fixed, that it fliall refid in the direiftion parallel to the 
 piece. Frequently this cannot be done ; but we mud 
 come as near to it as we can. In fuch cafes we mud 
 fuppofe that the affemblage yields a little to the pref- 
 fures which aft on it. We mud examine what change 
 of fliape a fmall yielding will produce. We mud now 
 fee how this will afieft. the iron drap which we have al- 
 ready fnppofed attached to the joint in fome manner 
 that we thought fultable. This fetthng will perhaps 
 draw the pieces away from it, leaving it loofe and un- 
 ferviceable (this frequently happens to the plates which 
 are put to fecure the obtufe angles of butting timbers, 
 when their bolts are at fome diftance from the angles, 
 efpecially when thefe plates are laid on the infide of the 
 angles) ; or it may caufe it to comprefs the pieces hard- 
 er than before; in which cafe it is anfwering our inten- 
 tion. But it may be producing crofs drains, which 
 may break them ; or it may be crippling them. We 
 can hardly give any general rules ; but the reader will 
 do well to read what is written in n" 36. and 41. of the 
 article Roof, Encycl. In n° 36. he will fee the nature 
 of the drap or dirrup, by which the king-pod carries 
 the tie-beam. The ilrap that we obferve mod gene- 
 rally ill placed is that which connedls the foot of the 
 rafter with the beam. It only binds down the rafter, 
 but does not adl againd its horizontal thrud. It (hould 
 be placed farther back on the beam, with a bolt through 
 it, which will allow it to turn round. It Ihould em- 
 brace the rafter almod horizontally near the foot, and 
 (hould be notched fquare with the back of the rafter. 
 Such a condrudlion is reprefented in fig. 37. By mo- 
 \'ing round the eye-bolt, it follows the rafter, and can- 
 not pinch and cripple it, which it always does in its or- 
 dinary form. We are of opinion that draps which have 
 eye-bolts in the very angles, and allow all motion round 
 them, are of all the mod perfeft. A branched drap, 
 fuch as may at once bind the king-poft and the two 
 SuppL. Vol. I. Part I. 
 
 N T R Y. 177 
 
 braces which butt on its foot, will be more ferviccable 
 if it have a joint. When a roof warps, thofe branched 
 draps frequently break the tenons, by affording a ful- 
 crum in one of their bolts. Aii attentive and judicious 
 artiil win confider how the beams will aft on fuch oc- 
 cafiuns, and will avoid giving rife to thefc great drains 
 by levers. — A fliilfiil carpenter never employs many 
 draps, coufidering tliein as auxiliaries foreign to his art, 
 and fubjeft to im])erfcftions in workmanlhip which he 
 cannot difccrn nor amend. We mull refer the reader 
 to Nicholfon's Carpi-nfir and Joiner's Assistant 
 for a more particular account of the various forms of 
 dirrups, fcrewed rods, and other iron work forcarrying 
 tie-beams, &c. 
 
 As for thofe that are neceflary for the turning joints 
 of great engines conllrufted of timber, they make no 
 part of the art of carpentry. 
 
 4* 
 After having attempted to give a fydematic viewDnamplej 
 of the principles of framinsf carpeniry, we fiiall con- f'f different 
 
 elude, by g-iving- fome examples which will iilfldrate and'""^''' 
 
 r \ r ■ 'I carpentry, 
 
 confirm the foregoing principles. ^j 
 
 Fig. 38. is the roof of the chapel of the Royal Hof-Roofof 
 
 pital at Greenwich, condrufted by Mr S. Wyat Greenwich 
 
 Scantling. 
 AA, Is the tie-beam, 57 feet long, fpanning 
 
 51 feet clear - - - - 14 by 12 
 
 CC, Queen-pods .... oXi.'J 
 
 D, Braces ..... pX7 
 
 E, Trufs beam .... 10X7 
 
 F, Straining piece .... 6X7 
 
 G, Principal rafters ... 10X7 
 H, A cambered beam for the platform . 9.7 
 B, An Iron dring, fupporting the tie-beam 2X2 
 
 The trufles are 7 feet apart, and the whole is covered 
 with lead, the boarding being fupported by horizontal 
 ledgers h, h, of 6 by 4 inches. 
 
 This is a beautiful roof, and contains lefs timber than 
 rood of its dimenfions. The parts are all difpoied with 
 great judgment. Perhaps the iron rod is unneceffary ; 
 but it adds great diffnefs to the whole. 
 
 The iron llraps at the rafter feet would have had 
 more eflfcft if not fo oblique. Thofe at the head of 
 the polls are very effeftive. 
 
 We may obferve, however, that the joints between 
 the draining beam and its braces are not of the bed 
 kind, and tend to bruife both the draining beam anti 
 the trufs beam above it. 
 
 Fig". 39. tlie roof of St Paul's, Covent Garden, con-st Taul's, 
 drufted by Mr Waplhot in 1796. Covcht 
 
 A A, Tie-beam fpanning 50 feet 2 inches 16.12 
 
 B, Queen-pod 9X8 
 
 C, Trufs beam 10X8 
 
 D, King-pod (14 at the joggle) . - 9X8 
 
 E, Brace »X74- 
 
 FF, Principal brace (at bottom) - - 1oX8t 
 
 HH, Principal rafter (at bottom) . IoXBt 
 
 gg. Studs fupporting the rafter - . 8x8 
 
 This roof far excels the original one put up by Inigo 
 Jones. One of its truffes contains 198 feet of timber. 
 One of the old roof had 273, but had many inaftive 
 timbers, and others ill difpofed. (A''. B. The figure 
 which we gave of it in the article Roof, copied from 
 Z Price, 
 
 Garden.
 
 178 
 
 45 
 
 Birming'- 
 bam the- 
 atre. 
 
 C A R P E 
 
 Price, IS very erroneous). The internal trufs FCF is 
 admirably contrivtd for fupporting the exterior ratters, 
 without any prefTure on the far projefling ends of the 
 tie-beam. The former roof had bent them greatly, fo 
 as to appear ungraceful. 
 
 We think that the camber (fix inches) of the tie- 
 beam is rather hurtful ; bccaufe, by fettling, the beam 
 lengthens; and thlsmufl be accompanied by a confidrr- 
 ahle finking of the roof. This will appear by calcula- 
 tion. 
 
 Fig. 40. the roof of Birmingham theatre, conflruft- 
 ed by Mr Geo. Saunders. The fpan is 80 feet clear, 
 and the truffes are 10 feet apart. 
 
 N T R Y. 
 
 A, Is an oak corbel 
 
 B, Inner plate ... 
 
 C, Wall plate 
 
 D, Pole plate 
 
 E, Beam .... 
 
 F, Straining beam 
 
 G, Oak king-poll (in the Ihaft) 
 H, Oak queenpoft (in the Ihaft) 
 I, Principal rafters 
 
 K, Common ditto 
 
 I., Principal braces 
 
 M, Common ditto 
 
 N, Purlins ... 
 
 Q, Straiiiing^ fill 
 
 9X5 
 9X9 
 
 7x5 
 15X15 
 12X9 
 9x9 
 7X9 
 9X9 
 4X24 
 9 and 6X9 
 6X9 
 
 7X5 
 5iX9 
 
 This roof is a fine fpecimen of Britifh carpentry, and 
 IE one of the boldeft and lighteft roofs in Europe. The 
 ftraining fill Q_ gives a firm abutment to the principal 
 braces, and the fpace between the pofts is 19I feet 
 wide, affording roomy workfhips for the carpenters and 
 other workmen conneftcd with a theatre. The con- 
 trivance for taking double hold of the wall, which is 
 very thin, is excellent. There is alfo added a beam 
 (marked R), bolted down to the tie-beams. The in- 
 tention of this was to prevent the total failure of fo 
 bold a trufling, if any of the tie-beams (hould fail at the 
 ^f end by rot. 
 EruryLane Akin to this roof is fig. 41. the roof of Drury Lane 
 theatre. theatre, 80 feet 3 inches in the clear, and the trufles 15 
 feet apart, conftrufted by Mr Edward Grey Saunders. 
 
 A, Beams - - - - - 10 by 7 
 
 B, Rafters 7X7 
 
 C, King-poft* .... 12X7 
 
 D, Struts - - - - - 5X7 
 
 E, Purlins ..... 9X5 
 G, Pole plates - - - - ■ S^^S 
 I, Common rafters .... 5X4 
 K, Tie-beam to the main trufs - - 15X12 
 L, Pofts to ditto .... 15X12 
 M, Principal braces to ditto - 14 and 12X12 
 
 N, Struts 8X12 
 
 P, Straining beams • - - -' 12X12 
 
 The main beams are truffed in the middle fpace with 
 oak trufles 5 inches fquare. This was neceflary for its 
 width of 32 feet, occupied by the carpenters, painters, 
 &c. The great fpace between the truffes affords good 
 ftore-rooms, drefiing-rooms, &c. 
 
 It is probable that .this roof has not its equal in the 
 world for lightnefs, ftiffnefs, and ftrength. The main 
 trufs is fo judicioufly framed, that each of them will fafe- 
 ly bear a load of near 300 tons ; fo it is not likely that 
 
 47 
 
 4? 
 
 they will ever be quarter loaded. The divifion of the 
 whole into three paits makes the exterior roofings very 
 liglit. The ftrains are admirably kept from the walls, 
 and the walls are even firmly bound together by the 
 roof. They alfo take oft the dead weight from the 
 main trufs one-third. 
 
 The intelligent reader will perceive that all thefe roofs Remarks 
 are on one principle, depending on a trufs of three 
 pieces and a ftraight tie-beam. This is indeed the 
 great principle of a trufs, and is a ftep beyond the roof 
 with two ratters and a king poft. It admits of much 
 greater variety of forms, and of greater extent. We 
 may fee that even the middle part may be carried to 
 any fpace, and yet be flat at top ; for the trufs beam 
 may be fupported in the middle by an inverted king, 
 poft (of timber, not iron), carried by iron or wooden 
 ties from its extremities : And the fame ties may carry 
 the horizontal tie-beam K ; for till K be torn afunder, 
 or M, M, and P be crippled, nothing can fail. 
 
 The roof of St Martin's church in the Fields is con. 
 ftrufted on good principles, and every piece properly 
 difpofed. But although its fpan does not exceed 40 
 feet from column to column, it contains more timber in 
 a trufs than there is in one of Drury-Lane theatre. The 
 roof of the chapel at Greenwich, that of St Paul's, Co- 
 vent Garden, that of Birmingham, and that of Drury 
 Lane theatres, form a ferles gradually more perfect. 
 Such fpecimens afford excellent leffons to the artifts. 
 We therefore account them a ufeful prefent to the pub- 
 lic. 
 
 There is a very ingenious projeft offered to the pub-Prfjei5l bj 
 lie by Mr Nicholfon [Carpenter's Affijlant, p. 68.) He Mr Nictio 
 propofcs Iron rods for king-pofts, queen-pofts, and all''"'' 
 other fituations where beams perform the of&ce of ties. 
 This is in profecutlon of the notions which wc publlfti- 
 ed in the article Roof of the Encycl. (fee n"36, 37.) 
 He receives the feet of the braces and ftruts in a focket 
 very well conntfted with the foot of his iron king-poll; 
 and he fecures the feet of his queen-pofts from being 
 pufhcd inwards, by interpofing a ftraining fill. He 
 does not even mortlfe the toot of his principal rafter in- 
 to the end of the tie-beam, but fets it in a focket like a 
 Ihoe, at the end of an iron bar, which is bolted into the 
 tie-beam a good way back. All the parts arc formed 
 and difpofed with the precifion of a perfon thoroughly 
 acquainted with the fiibjetl; and we have not the fmall- 
 eft doubt of the fnccefs of the projedt, and the complete 
 fecurity and durability of his roofs, and we expect to 
 fee many of them executed. We abound In Iron, but 
 we muft fend abroad for building timber. Thls-is there, 
 fore a valuable project ; at the fame time, however, let 
 us not over-rate its value. Iron is but about 1 2 times 
 ftronger than red fir, and is more than 1 2 times hea- 
 vier ; nor is It cljeaper, weight for weight, or ftrength 
 for ftrength. 
 
 Our Illuftrations and examples have been chiefly taken 
 from roofs, becaufe they 3re the moft familiar Inflances 
 of the diiBcult problems of the art. We could have 
 wlfhed for more room even on this fubjeft. The con- 
 ftruclion of dome roofs has been (we think) miftaken, 
 and the difficulty is much lefs than is imagined. We 
 mean in refpefl of ftrength ; for we grant that the ob- 
 liquity of the joints, and a general intricacy, increafes 
 the trouble of workmanlhip exceedingly. Another op- 
 portanity may perhaps occur for confidering this fubje(ft> 
 
 Wooden
 
 (AH I'l; N I i;v n..vn. \ in 
 
 ■'iQ-. J . 
 
 Fig. 2. 
 
 -^H 
 
 riR-. 3. 
 
 Tiff. 8 
 
 --.& 
 
 Fie-. 6. 
 
 --^.ra 
 
 :=^_1
 
 CAHPl'.XTRV Pi,ATK IX. 
 
 Fie-. JO. 
 
 U I.,«-.ri f^-ulr,
 
 I
 
 C-ARFJATin' 1-1 ^VIK X.. 
 
 Fi„-. m. 
 
 Kig-.TO. 
 
 Fig-. 2Z. 
 
 Kio-. ■.';). X° 2. 
 
 tie-. v?l. 
 
 Tie-. M. 
 
 Fio- . 24 . V"! 
 
 fi]^.24, v;^ 
 
 Kio- ^.'J . 
 
 Flr-'^J.V? ■-'• 
 
 Fig". ?()
 
 [i.r 
 
 I'VlU'EVfUV I'l.ATK XU 
 
 i^li .1 
 
 CO
 
 I!
 
 CARFKXTRy in.ATt xi. 
 
 Xi ii 
 
 fig-. 33. IS^ 2. 
 
 s.,^.^fe 
 
 TU. 33. 
 
 I Fie-.33.3S^°3 >^-r- 
 
 rip-. 3 4. 
 
 rig'. 30. 
 
 
 T\'.- .3b 
 
 J 
 
 Tig. 36. 
 
 te„/- ^. i 
 
 rig-.35 x° :? 
 
 Fig-. 3g:s[° ?. 
 
 /
 
 "'t
 
 49 
 'oodcn 
 Uges. 
 
 raming of 
 rest lever 
 
 C A R P E 
 
 Wooden bridges form another clafs equally difficult 
 and important ; but our limits arc alieady overjiafred, 
 and will not admit them. The principle on which they 
 fliould all be con(lru6ted, without exception, is that of 
 a trufs. avoiding all lateral bearings on any of the tim- 
 bers. In the application of this principle, we mud far- 
 ther remark, that tlie angles of our truls thould be as 
 acute as poflible ; therefore we fliould make it of as few 
 and as long pieces as we can, taking care to prevent the 
 bending of the trufs beams by bridles, which embrace 
 them, but without prefling them to either lide. When 
 the trufs confifts of many pieces, the angles are very ob- 
 tufe ; and the thrufts increafe nearly in the duplicate 
 proportion of the number of angles. The proper ma- 
 xims will readily occur to the artift who confiders with 
 attention the fpecimens of centres or coombs, which we 
 (hall give in the article Centre. 
 
 With refpcft to the frames of carpentry which occur 
 
 engines and great machin&s, the varieties are fuch 
 that it would require a volume to treat of them proper- 
 ly. The principles are already laid down ; and if the 
 reader be really interefted in the ftudy, he will engage in 
 it with ferioufnefs, and cannot fail of being inftru<iled. 
 We recommend to his confideration, as a fpecimen of 
 what may be done in this way, the working beam of 
 Hornblower's fteam-engine [itt SlE/iM-Engine, n" 84. 
 Encycl. ) When the beam muft a£l by chains hung from 
 the upper end of arch heads, the framing there given 
 feems very fcientifically conftrufted ; at the fame time, 
 we think that a ftrap of wrought iron, reaching the 
 whole length of the upper bar (fee the figure), would 
 be vaftly preferable to thofe partial plates which the en- 
 gineer has put there, for the bolts will foon work loofe. 
 
 But when arches are not neceflary, the form employ- 
 ed by Mr Watt is vaftly preferable, both for fimplicity 
 and for ftrength. It confifts of a fimple beam AB 
 (fig. 42.), having the gudgeon C on the upper fide. 
 The two pifton-rods are attached to wrought iron joints 
 
 N T R Y. 
 
 A and B. Two ftronj* (Irufs DC, EC reft on the up. 
 per fide of the gudgeon, and carry an iron ftring 
 ADEB, confifting of three pieces, connefted with the 
 ftrnts by proper joints of wrought iron. A more mi- 
 nute defcription is not needed for a clear conception of 
 the principle. No part of this is expofed to a crofa 
 ftrain ; even the beam AB might be fa wed through at 
 the middle. The iron ftring is the only part which is 
 ftretched ; for AC, DC, EC, BC, are all in a ftate of 
 compreflion. We have made the angles equal, that all 
 may be as great as poflible, and the prtlfure on the 
 ftrnts and ftrings a minimum. Mr Watt makes them 
 much lower, as A d e B, or A ' ■ B. But this is for 
 economy, becaufe the ftrengtli is almoft inluperable. It 
 might be made with wooden ftrings; but the workman- 
 (hip of the joints would more than compenfate thechcap- 
 nefs of the materials. 
 
 179 
 
 51 
 
 We offer this article to the public with deference, ConcluCoO. 
 and we hope for an indulgent reception of our effay on 
 a fubjeft which is in a maimer new, and would require 
 much ftudy. We have bellowed our chief attention 
 on the ftrength of the conftrufti'on, becaufe it is here 
 that perfons of the profefTion have the moft fcanty in- 
 formation. We beg them not to confider our obferva- 
 tions as too refined, and that they will ftudy them with, 
 care. One principle runs through the whole ; and 
 when that is clearly conceived and familiar to the mind, 
 we venture to fay that the praditioner will find it of 
 cafy application, and that he will improve every per- 
 formance by a continual reference to it. 
 
 If this attempt to inftruft our moft valuable and much 
 efteemed artifts (hall appear to meet with their approba- 
 tion, it may encourage us to engage in the ferious taflc 
 of compofing a fyttem on the fubjeft. But this is a 
 great work, and will require much time and liberal-con- 
 tribution of knowledge from the eminent carpenters who 
 do honour to this country by their works. 
 
 ■Mv«A;)NS^Vi%>«!v^« 
 
 rafcabel 
 
 II 
 Caflli.i. 
 
 CAS 
 
 CASCABEL, the knob or button of metal behind 
 the breech of a cannon, as a kind of handle by which 
 to elevate and diredl the piece ; to which fome add the 
 ' fillet and ogees as far as the bafe-ring. 
 
 CASEMATE, or Cazemate, in fortification, a 
 kind of vault or arch of ftone-work, in that part of the 
 fiank of a baftion next the curtain ; ferving as a battery 
 to defend the face of the oppofite baftion, and the moat 
 or ditch. 
 
 It is now feldom ufed, becaufe the batteries of the 
 enemy are apt to bury the artillery of the cafemate in 
 the ruins of the vault; befide, the great fmoke made by 
 the difchacge of the cannon renders it intolerable to the 
 men. So that, inflead of the ancient covered cafemates, 
 later engineers have contrived open ones, only guarded 
 by a parapet, &c. 
 
 Casemate is alfo ufed for a well with feveral fubter- 
 raneous branches, dug in the paffage of the baftion^ till 
 the miner is heard at work, and air given to the mine. 
 
 CASSINI (James), a celebrated French aftronomer, 
 was born at Paris February 18. 1677, being the young, 
 er fon of Johannes Dominicus CaHini, of whom fome 
 account has been given in the Encych^tSa- 
 
 CAS 
 
 After his firfl ftudies in his father's houfe, in which 
 it is not to be fuppofed that mathematics and aftronomy * 
 would be neglefted, he was fent to ftudy philofophy at 
 the Mazarine college, where the celebrated Varignon was 
 then profeftor of mathematics. From the affiftance of this 
 eminent young man Caflini profited fo well, that at 15 
 years of age hefupported a mathematical thefisvvith great 
 honour. At the age of 1 7 he was admitted a mem- 
 ber of the Academy of Sciences ; and the fame year he 
 accompanied his father in a journey to Italy, where 
 he aflifted him in the verification of the meridian at Bo- 
 logna and other meafurenients. On liis return he per- 
 formed fimilar operations in a journey into Holland, 
 where he difcovered fome errors in the mealnre ot the 
 earth by Snell, t!ie refult of which was communicated to 
 the Academy in 1702. He made alfo a vifit to England 
 in 1696, where he was made a member of the Iloyal 
 Society. In 1712 he fucceeded Us father as aftronomer 
 royal at the obfervatory of Paris. In 1717 he gave to 
 the Academy his refearches on the diftance of the fixed 
 ftars ; in which he fiiewcd that the whole annual orbit, 
 of near 200 millions of milea diameter, is but as a point 
 in comparifon of that diftance. The fame year he com- 
 Z 2 municated 
 
 Cadini.
 
 CAS [ i8 
 
 CalTini. municated alfo his difcoveries concerning the inch'nation 
 •"—v^"' of the orbits of the fatelh'tes in general, and efpecially 
 of thofe of Saturn's fatellites and ring. In 1725 he 
 undertook to determine the caufe of the moon's hbra- 
 tion, by which (he (hews fometimes a little to'.vards one 
 fide, and fometimes a little on the other, of that half 
 which is commonly behind or hid from our view. 
 
 In 1732 an important qnellion in aflronomy exercifed 
 the ingenuity of our author. His father had determi- 
 ned, by his obfervation?, that the planet Venus revolved 
 about her axis in the fpacc of 23 hours ; and M. Eian- 
 chini had publiflied a work in 1729, in which he fettled 
 the period of the fame revolution at 24 days 8 hours. 
 IVom an examination of Bianchini's obfervations which 
 were upon the fpots in Venus, he difcovered that he 
 had intermitted his obfervations for the fpace of three 
 hours, from which caufe he had probably miftaken new 
 fpots for the old ones, and fo had been led into the mi- 
 ftake. The probability is, that both had fallen into 
 fome miftake, or that they had proceeded on very diffe- 
 rent principles; for othervvife fuch different refults are 
 wholly unaccountable. Dr Herlchel feems fatisfied that 
 the period of the revolution is lefs than Bianchini has 
 made ; but he does not fay what it is, or that it is not 
 much greater than it was fuppofed by Caffini. Our 
 author, after he had convifted Bianchini, as he thought, 
 of error, determined the nature and quantity of the 
 acceleration of the motion of Jupiter at half a fecond 
 per year, and of that of the retardation of Saturn at 
 two minutes per year ; that thefe quantities would go 
 on increafing for 2000 years, and then would decreafe 
 again. In 1740 he publifhed his Aftronomical Tables, 
 and his Elements of Ailronomy ; very extenlive and ac- 
 curate works. 
 
 Although aftronomy was the principal objeft of our 
 author's confideratlon, he did not confine himfelf nbfo- 
 lutely to that branch, hut made occafional excurfions 
 into other fields. We owe alfo to him, for example. 
 Experiments on Eledlricity, or the Light produced by 
 Bodies by Friftion ; Experiments on the Recoil of Fire- 
 arms ; Refearches on the Rife of the Mercury in the 
 Barometer at different Heights above the Level of the 
 Sea; Refi.'Hions on the perfefting of Burning- glaffcs; 
 and other Memoirs. 
 
 The French Academy had properly judged, that one 
 of its mod important objefts was the meafurement of 
 the earth. In 1669 Picard meafured a little more than 
 a degree of latitude to the north of Paris ; but as that 
 extent appeared too fmall from which to conclude the 
 whole circumference with fuflicient accuracy, it was re- 
 folved to continue that meafure.-nent on the meridian of 
 Paris to the north and the fouth, through the whole 
 extent of the country. Accordingly, in 1683, the late 
 M. de la Hire continued that on the north fide of Pa- 
 ris, and the older Caffmi that on the fouth fide. The 
 latter was alfilled in 17CO in the continuation of this 
 operation by his fon our author. The fame work was 
 farther continued by the fame academicians; and, finally, 
 the part left unfinifhed by De la Hire in the north was 
 finillied in 17 18 by our author, with the late Maraldi, 
 and De la Hire the younger. 
 
 Thefe operations produced a confiderable degree of 
 precifion. It appeared alfo, from this meafured extent 
 of fix degrees, that the degrees -.vere of different lengths 
 in different parts of the meridian; and in fuch fort that 
 
 o ] CAS 
 
 our author concluded, in the volume publiihed for 1718, Cafiini. 
 that they decreafed more and more towards the pole, ' - ■ v— 
 and that therefore the figure of the earth was that of 
 an oblong fphcroid, or having its axis longer than the 
 equatorial diameter. He alfo meafured the perpendicu- 
 lar to the fame meridian, and compared the meafured dif- 
 tance with the differences of longitude as before deter- 
 mined by the eclipfes of Jupiter's fatellites : whence he 
 concluded that the length of the degrees of longitude 
 was fmaller than it would be on a fphere, and that 
 therefore again the figure of the earth was an oblong 
 fpheroid, contrary to the determination of Newton by 
 the theory of gravity. Though Ncivton was of all men 
 the mod averfe from controverfy, the other mathema- 
 ticians in Britain did not tamely fubmit to conclufions 
 in direil oppofition to the fundamental doftrine of a 
 philofopher of vvhofe talents the nation was juiUy proud. 
 The confequence was, that the French government fent 
 two difierent fets of meafurers,theonetomeafure a degree 
 at the equator, the other at the polar circle ; and the 
 couiparifon of the whole determined the figure to be an 
 oblate fpheroid, contrary to Cafiini's determination. 
 
 After a long and laborious life, James Caffini died 
 in April 1756, in confequence of a fall, and was fuc- 
 ceeded in the Academy and Obfervatory by the fubjeft 
 of the following article. He publifhed, A Treatife on 
 the Magnitude and Figure of the Earth ; as alfo, The 
 Elements or Theory of the Planets, with Tables ; be- 
 fide an infinite number of papers in the Memoirs of the 
 Academy, from the year 1699 to 1755. 
 
 C,Ji5;A7fl'i'7'(6ury(Cefar Fran cois),acelebrated French 
 aftronomer, direftor of the obfervatory', penfioner aftro- 
 nomer, and member of moff of the learned focieties of 
 Europe, was born at Paris June 17. 1714, being the fe- 
 cond fon of James Cafiini, the fubjcft of the preceding 
 memoir, whofe occupations and talents he inherited and 
 fupported with great honour. He received his firft leffons 
 in aftronomy and mathematics from MM. Maraldi and 
 Camus ; a^d made fuch a rapid progrefs, that when he 
 was not more than ten years of age he calculated the 
 phafes of a total eclipfe of the fun. At the age of 
 eighteen he accompanied his father in his two journeys 
 imdertaken for drawing the perpendicular to the ob- 
 fervatory meridian from Strafbourg to Breft. From 
 that time a general chart of France was devifed.; for 
 which purpoie it was neceffai")- to traverfe the countiy 
 by feveral lines parallel and ptrpendicuhir to the meri- 
 dian of Paris, and our author was charged with tlie con- 
 dudl of this bufinefs ; in which he was fo fcrupulous as. 
 to meafure again what had been meafured by his father. 
 This great work was publifhed in 1740, with a chart 
 fiiewing the new meridian of Paris, by two different fe- 
 ries of triangles, paffing along the fea coalfs to Bayonne, 
 traverfing the frontiers of Spain to the Mediterranean 
 and Antibes, and thence along the eaftern limits of 
 France to Dunkirk, with parallel and perpendicular 
 lines defcribed at the diftance of 6000 toifes from one 
 another, from fide to fide of the country. 
 
 A tour which, in 1741, pur author made in Flanders, 
 in the train of the king, gave rife, at his majefty's in- 
 llance, to the chart of France ; relative to which Caf- 
 fini publifhed different works, as well as a great number 
 of the fheets of the chart itfelf. In 1761 he under- 
 took an expedition into Germany, for the purpofe 
 of continuing to Vienna the perpendicular of the Pa-
 
 CAT 
 
 [ i8i 1 
 
 C A 
 
 T 
 
 I Caflini 
 
 II 
 Catalojrues 
 
 ris meridian ; to unite the triangles of the chart of more perfciS: ; but nothing has there been faid of their CadloRutJ 
 
 France with the points taken in Germany; to pre- origin, or of tlic iifes which might be made of the oldclt "^ Co'-ks.^ 
 
 pare the means of extendiiig into that comitry the catalogues. —— y— < 
 
 fame plan as in France ; and thus to cilabllfh fuc- According to tlie ProRlTor, George Wilier, whom 
 
 (.efiivcly for all Europe a moll ufeful uniforir.ity. — fomc improperly call Viller, and otiit-rs Walter, a book- 
 
 Our author was at Vienna the 6lh of June 1761, the feller at Augibnrg, wiio kept a very large ihop, and 
 
 dav of the tranfit of the planet Venus over the fun, of frequented the Fiaiickfort fairs, firlt fell upon the plan 
 
 wliicli he obfervcd as much as the llate of the weather of caufuig to be printed, before every fair, a catalogue 
 
 would permit him to do, and publilhed the account of of all the new books, in which the iize and printers 
 
 it in his P'oya^e at Alkniagne. names were marked. Le Mire, better known under 
 
 Finally, M. Caffuii, always meditating the perfeftion the name of Miiaeus, fays that catalogues were lirft 
 
 of his grand defign, proiited of thepeace of 1783 to pro- printed in the year 1 554; but Labbe (a), Reimann (b), 
 
 pofe the joininu- of certain points taken upon the Eng- and Heumann (c), who took their information from Le 
 
 lilh coall with thofe which iiad been determined on the Mire, make the year erroncouily to be 1564. Willer's 
 
 coaft of France, and thus to conned the general chart catalogues were printed till the year 1592 by Nicol. 
 
 of the latter with that of the Britidi iflcs, like as he Balffeus, printer at Franckfort. Other bookfcllers, 
 
 had before united it with thofe of Flanders and Gerrna- however, muft have foon publilhed catalogues of the like 
 
 iiv. The propofal was favourably received by the Eng- kind, though that of Wilier continued a long time to 
 
 liih government, and prefently carried into eti'edt under be the principal. 
 
 the direftion of the Royal Society, the execution being 
 committed to the late General Roy. tiee the life ot 
 that general in this SuppUmsiit. 
 
 Between the years 1735 and 177c, M. Caffini pub- 
 lidied, in the volumes of Mem.oirs of the Fiencii Aca- 
 demy, a prodigious number of pieces, confiding chief- 
 ly of aftronomical obiervations and queftions ; among 
 
 In all thele catalogues, which are in quarto and not 
 paged, the following order is obfcrved. The Latin 
 books occupy the full place, beginning with the Pro- 
 tettant theological works, perhaps becaufe Wilier was a 
 Lutheran ; then come the Catholic ; and after thefe, 
 books of jurifprudencc, medicine, philofophy, poetry, 
 and mufic. The fecond place is afligned to German 
 
 wiiich are obfervable, refearches concerning the parallax books, which are arranged in the fame manner 
 of the fun, the moon, Mars, and Venus ; ou altronomi- The bookiellers of Leipilc foon perceived the advan- 
 
 cal refraAions, and the effedf caufed in their quantity tage of catalogues, and began not only to reprint thofe 
 
 and laws by the weather ; numerous obfervations on the of Franckfort, but alfo to enlarge them with many 
 
 obliquity of the ecliptic, and on the law of its variations, books which had not been brought to the fairs in tliat 
 
 In fhort, he cultivated aftronomy for fifty years, the city. Our author had for fome time in his cuilody, 
 
 moft important for that fcience that ever elapfed for Calalo^us univerjalis pre inmdinh Fraiucfurtcnjihus ver- 
 
 tlie magnitude and variety of oljefts, in which he com- nu/ilus, de anno l6co; or, A catalogue of all the books 
 
 monly fuftained a principal ihare. on fale in Book-lliect, Franckfort, and alfo of the books 
 
 M. Caflini was nf a very ftrong and vigorous confti- publifhed at Leipfic, which have not been brought to 
 
 tution, which carried him through the many laborious Franckfort, with the perniiliion of his highncfs the clec- 
 
 operations in geography and aftronomy which he con- tor of Saxony, to thole new works wlu'ch have appeared 
 
 dufted. An habitual retention of urine, however, ren- at Leipfic. Fiinted at Leipfic by Abraham Lamberg, 
 
 dered the lafl twelve years of his life very painful and and to be had at his fnop. On the September catalogue 
 
 diftreffmg, till it was at length terminated by the fmall- of the fame year, it is faid that it is printed from the 
 
 poK the 4th of September 1784, in the 71ft year of his Franckfort copy with additions. He found an imperial 
 
 age. He was fucceeded in the academy, and as di- privilege for the firll lime on the Franckfort September 
 
 reftor of the obfervatory, by his only fon John-Do- catalogue of 1616: Cum gratia et privilegio fpeciali f. 
 
 minic Caflini, the fourth in order of direft defcent who caef. maj. Projiat c.pud y. Krugcrum jiugujlar.um. 
 has filled that honourable ftation. Reimmann fays, that after Willer's death the cata- 
 
 CASTRAMETATION, the art or aeT; of encamp- logue was publilhed by the Leipfic bookfeller Henning 
 
 mg an army. 
 
 CATACAUSTICS, or Catacaustic Curves, in 
 the higher geometry, are the fpecies of cauftie curves 
 formed by refleftion. 
 
 CATACOUSTICS,orCATAPHONics,is the fcience 
 
 Grofle, and by his fon and grandfon. The council of 
 Franckfort caufed feveial regulations to be iffued re- 
 fpccting catalogues ; an account of which may be feen 
 in D. Ortli's Yreatife on ibc Imperial Fairs at Franck- 
 fort, After the bufinels of bookfeliing was drawn from 
 
 of reflefled founds ; or that part of acoullics which treats Franckfort to Leipfic, occaiioned principally by the re- 
 of the properties of echoes. ^ ftrictions to which it was fubjeded at the former by 
 
 CATALOGUES of Books, is a fubjeft of which the cenfors, no more catalogues were printed there; 
 a very curious hidory has been given to the world by and the fhops in Book-ilreet were gradually converted 
 Profeflbr Beckmann. In the Encyclopa;dia mention has into taverns (d). 
 
 been made of fome of the moft valuable catalogues, their " In the 16th century there were few libraries ; and 
 deftfts pointed out, and rules given for making them thefe, which did not contain many books, were in mo- 
 
 naiteriesj. 
 
 (a) Labbe, Bibliotheca Bibliothecarum. Lipfiae, 1682, izrao, p. 
 
 (b) Einleitung in die Hijloriam Literariam, i. p. 203. 
 
 (c) Confpeftus Reip. Litter, c. vi. § 2. p. 316. 
 
 (d) Joh. Adolpfi. Stock, Frankfurter Chronik, p. 77. 
 
 112.
 
 CAT L 
 
 CatjloB"" nafterics, and cotififted principally of theological, philo- 
 "[^■"''' ^ ^ - fopliical, and liiftorical works, with a few, however, on 
 '^ ' iurifpnidtiice and medicine ; while thole whiili treated 
 
 of agriculture, manufafturcs, and trade, were thounht 
 unworthy of the notice of the learned, or of being pre- 
 ferved in large colleftions. The number of thefe works 
 was, neverthelefs, far from being inconfidcrable ; and at 
 any rate, many of them would have been of great ufe, 
 as thev would have ferved to illuftrace the inftrudtive 
 hillory of the arts. Catalogues which might have given 
 occafion to inquiries alter books, thai may be Hill fome- 
 vvhere preferved, have fuffered the fate of tomb-ftones, 
 which, being wafted and crumbled to pieces by the de- 
 ftroying hand of time, become no longer legible. A 
 complete feries of tliem perhaps is nowhere to be found, 
 at lead I do not remember (fays the Profeflbr) to have 
 ever feen one in any libra'ry." 
 
 This lofs, however, he thinks, might be in fome mea- 
 fure fupplied by the catalogues of Clefs and Draudius ; 
 ti'ho, by the defire of fome bookfellers, collefted toge- 
 ther all the catalogues which had been publiihed at the 
 dilTerent fairs in different years. The work of Clefs has 
 the following title : Unhis fscuTi cjufque virorum littera- 
 toriim monumentis tumjlorcntijjimi, turn fertUjfimi, ab an- 
 no I ceo ad 1602 nundinarum aulumnallum inclufiTe, elen 
 thus confummat'ijfimus— defumtus part'tm ex fingularum nun- 
 din.irum cntalcgis, partim ex Hbl'tothecis. Audore Joanne 
 Cleflio, Wineccenfi, Hannoio, philofopho ac medico. — 
 By the editor's preface, it appears that the firft edition 
 was publi(hed in 1592. The order is aimed the fame 
 as that obferved by Wilier in his catalogues. 
 
 The work of Draudius, which was printed in feveral 
 quarto volumes for the firft time in 161 1, and after- 
 wards in 1625, is far larger, more complete, and more 
 nethcdical. Our author, however, confeffes, that he 
 never faw a perfeft copy of either edition. This cata- 
 Io<Tue confifts of three parts ; of which the firft has the 
 title of Bibliotheca clajfica, ft-ve Catalogus officinalis, in 
 quo finguli ftngularum faciihatum ac profcffionum Itbri, qui 
 in quavis fere lingua extant — recenjintur ; ufque ad an- 
 num 162+ inclufive. Auftore M. Georgio Draudio. — 
 . It contains Latin works on theology, jurifprudence, 
 medicine, hiftory, geography, and politics. The copy 
 in the library of the univerfity of Gottingen ends at 
 page 1304, which has, however, a catch-word, that 
 feems to indicate a deficiency. — The fecond part is in- 
 titled, Bibliotheca clajfica five Catalogus ojicinalis, in quo 
 philofophici artiumque adto humaniorum, poetici etiam et 
 mufici librt ufque ad annum 1624 continentur. This part, 
 containing Latin books alfo, begins at page 1298, and 
 ends with page 1654, which is followed by an index of 
 all the authors mentioned. — .\ fmaller volume, of 302 
 pages, without an index, has for title, Bibliotheca exotica, 
 fl-ve Catalogus officinalis Ubrorum peregrinis Unguis ufuali- 
 'bus fcriptorum. And a third part, forming 759 pages, 
 befides an index of the authors, is called, Bibliotheca li- 
 brorum Germanicorum clajfica ; that is, A catalogue of 
 all the books printed in the German language till the 
 year 1625. 
 
 We have reafon to believe that there are other edi- 
 tions of this catalogue than thofe mentioned by Profef- 
 for Beckmann ; and it might become fome prince or 
 great man, for it is not a work for a book feller, to com- 
 pare all the editions together, and publilh a new one 
 more correa than any that is at prefent extant. This 
 
 1S2 ] CAT 
 
 indeed would ne an expenfive and not an eafv tafl{ ; for '^'f*'"t''i" 
 our author obfcrves, that all the oldeft catalogues had "^ ^^'' ''"''' • 
 the fame faults as thofe of later date, and that thofe ' 
 
 faults have been copied by Draudius. Many'books are 
 mentioned which were never printed, and many titles, 
 names, and dates, are given incorreflly ; but Draudius 
 neverthelefs is well worth the attention of any one who 
 may be inclined to employ his time and ingenuity on 
 the hiftory of literature ; and his work certainly was of 
 ufe to Haller when he compofed his Bibliotheca. 
 
 Catalogufs of the Stars, have ufually been difpofed, 
 either as collcfted into certain figures called <-<)ny?f//<j//onj, 
 or according to their right afcenfions, that is, the order 
 of their pafling over the meridian. 
 
 Of the principal catalogues, according to the firft of 
 thefe forms, an account has been given in the Encyclo- 
 piedia. The firft catalogue, we believe, that was printed 
 m the new or fecond form, according to the order o£ 
 the right afcenfions, is that of De la Caille, given in his 
 Ephemerides for the ten years between 1755 and 1765, 
 and printed in 1755. It contains the right afcenfions 
 and declinations of 307 ftars, adapted to the beginning 
 of the year 175:. In 1757 De la Caille publiftied his 
 AJlronomiit Fundamenta, containing a catalogue of the 
 right afcenfions and declinations of 398 ftars, likewife 
 adapted to the beginning of 1750. And in 17*^3, the 
 year after his death, was publifhed the Ctelum Aujlrale 
 Stelliferum of the fame author ; containing a catalogue 
 of the places of 1942 ftars, all fituated to the fouthward 
 of the tropic of Capricorn, and obferved by him wnilc 
 he was at the Cape ot Good Hope in 175 I and 7s2; 
 their places being alfo adapted to the beginning of 
 17^0. In the fame year was publiftied his Epheme- 
 rides for the ten years between 1765 and 1775 ; in the 
 introduttion to which are given the places of 515 zo- 
 diacal ftars, all deduced from the obfervations of the 
 fame author ; the places adapted to the beginning of 
 the year 1765. 
 
 In the Nautical Almanac for 1773, is given a cata- 
 logue of 387 ftars. in right afcenfion, declination, lon- 
 gitude, and latitude, derived from the obfervations of 
 the late celebrated Dr Bradley, and adjufted to the be- 
 ginning of the year 1760. This fmall catalogue, and 
 the refplts of about I 200 obfervations of the moon, are 
 all that the public have yet feen of the multiplied la- 
 hours of this moft accurate and indefatigable obferver, 
 although he has now (179H) been dead upwards of 38 
 years. 
 
 In 1775 was publiftied a thin volume, intitled Opera 
 Inedita, containing feveral papers of the late Tobias 
 Mayer, and among them a catalogue of the right afcen- 
 fions and declinations of 998 ftars, which may be oc- 
 culted by the moon and planets ; the places being adapt- 
 ed to the beginning of the year 1756. 
 
 At the end of the firft volume of " Aftronomical 
 Obfervations made at the Royal Obfervatory at Green- 
 wich," publiftied in 1776, Dr Maikelyne, the prefent 
 aftronomer royal, has given a catalogue of the places of 
 34 principal ftars, in right afcenfion and north polar 
 diftance, adapted to the beginning of the year 1770. 
 
 Thefe being the refult of Icveral years repeated ob- 
 fervations, made with the utmoft care and the beft in- 
 ilruments, It may be prefumed are exceedingly accurate. 
 In 1782, M. Bode of Berliii publiftied a very ex- 
 tenfive catalogue of 5058 of the fixed ftars, coUefted 
 
 from
 
 CAT 
 
 [ I 
 
 Cai»'cE!»es from the obfervatluns of Flamfteed, Bradley, Hevelliis, 
 of tlie Stars. j^jay^i-^ D^. ]^ Cnlllf, Meffier, Monnier, D'Arqueir, and 
 « other aftronomers ; all adapted to the beginning of the 
 
 )ear 1780; and accompanied with a celelliid atlas or 
 iet of maps of the conftcllations, engraved in a moft de- 
 licate and beautiful manner. 
 
 To thefe may be added Dr Herfchel's catalogue of 
 double ftars, printed in the Phil. Tranf. for 1782 and 
 1783 ; Mefder's nebula; and cinders of ftars, published 
 in the Connoijfince des Temps for I 784 ; and Herfchel's 
 catalogue of the fame kind, given in the Phil. Tranf. 
 for 17^86. 
 
 In 1 789 Mr Francis Wollafton publifhed " A Spe- 
 cimen of a General Aftronomical Catalogue, in Zones 
 of North-polar Diftance, and adapted to January 1. 
 179a." Thefe ftars are collected from all the cata- 
 logues before- mentioned, from that of Hevelius down- 
 wards. This work contains five diftinft catalogues ; 
 viz. Dr Malkelyne's new catalogue ot 36 principal ftars; 
 a general catalogue of all the ftars, in zones ot north- 
 polar diftance ; an index to the general catalogue ; a 
 catalogue of all the ftars, in the order in which they 
 pafs the meridian ; and a catalogue of zodiacal ftars, in 
 longitude and latitude. 
 
 Finally, in 1792, Dr Zach publifhed at Gotha, Ta- 
 bula Motuum Soils ; to which is annexed a new catalogue 
 of the principal fixed ftars, from his own obfervations 
 made in the years 1787, 1788, 1789, 1790. This ca- 
 talogue contains the right afcenfions and declinations of 
 381 principal ftars, adapted to the beginning of the 
 year 1800. — Mutton's Mathematical DiBwnary. 
 
 Befides thefe two methods of forming catalogues of 
 the ftars, Dr Herfchel has conceived a new one, in 
 which the comparative brightnefs of the ftars Is accu- 
 rately exprefTed. It is long fince aftronomers were firft 
 led to arrange the ftjrs in claffes of different magnitudes 
 by their various degrees of brilliancy or luftre. Bright- 
 nefs and fize have at all times been confidered as fyno- 
 nymous terms ; fo that the brighteft ftars have been re- 
 ferred to the clafs comprehending thofe of the firft mag- 
 nitude; snd as the fubfequent orders of ftars have been 
 fuppofed to decreale in luftre, their magnitude has been 
 determined in the fame decreafing progrcffion : but the 
 want of fome fixed and fatisfaftory ftandard of luftre has 
 been the fource of confiderable confufion and uncertain- 
 ty in fettling the relative magnitudes of the ftars. A 
 ftar marked i. ana. is fuppofed to be between the firft 
 and fecond magnitude; but 2. im. intimates that the 
 ftar is nearly of the fecond magnitude, and that it par- 
 takes fomewhat of the luftre of a ftar of the firft order. 
 Such fubdivifions may be of fome ufe in afcertalning 
 ftars of the firft, fecond, and third claffes; but the ex- 
 prefTions 5m, 5.6 m, 6.fm, 6m, muft be very vague and 
 indefinite. Dr Herfchel obferves that he has founJ 
 them fo in faft; and he therefore confiders this metiiol 
 of pointing out the different luftre of ftars as a reference 
 to an imaginary ftandard. If any dependence could be 
 placed on this method of magnitudes, " it would follow, 
 that no lefs than eleven ftars in the conftellation of the 
 Lion, namely, (' »■ ' 5 A 3 c </ 54, 48, 72, had all under- 
 gone a change in their luftre fince Flamftced's time : 
 For if the idea of magnitudes had been a clear one, our 
 author, who marked JJ i.jm. and y 2m. ought to be 
 underftood to mean that H is larger than y ; but we now 
 find that aftually y is larger thaa.1^ Every one of th« 
 
 83 ] CAT 
 
 eleven ftars (fays Dr ITerfciiel) which I have pointed Catalojrut* 
 out may be reduced to the fame contrudiillion." ct the >:t:'.rt. 
 
 The author has pointed out the inllanccs of the in- • 
 
 fufficiency of this method, and of the uncertain conclu- 
 fions that are deduced from it, in determining the com- 
 parative brightnefs of ftars found not only in Mr Flam- 
 ftced's catalogue, but alfo in the catalogues of other 
 aftronomers. It is fufficiently apparent that the prefent 
 method of exprefting the brightnefs of the ftars is very 
 defeflive. Dr Herfchel therefore propofes a difterent 
 mode, that is more precife and fatisfaflory. 
 
 " I place each ftar (he fays), inftead of giving its 
 magnitude, into a fhort feries, conftrudled upon the or- 
 der of brightnefs of the neareft proper ftars. Fur in- 
 ftance, to exprefs the luftre of D, I fay CDE. By thij 
 fhort notation, inftead of referring the ftar D to an 
 imaginary uncertain ftandard, I refer it to a precife and 
 determined exifting one. C is a ftar that has a greater 
 luftre than D, and E is another of lefs brightnefs than 
 D. Both C and E are neighboui ing ftars, chofen in 
 fuch a manner that I may fee them at the fame time 
 with D, and therefore may be able to compare them 
 properly. The luftre of C is in the fame manner afcer- 
 taiiied by BCD ; that of B by ABC ; and alfo the 
 brightnefs of E by DEF ; and that of F by EFG. 
 
 " That this is the moft natural, as well as the mofl: 
 effeftual way to exprefs the Iirightnefs of a ftar, and by 
 that means to deteft any change that may happen in its 
 luftre, will appear, when we confider what is requifite 
 to afcertain fuch a change. V/e can certainly not wifh 
 for a more decifive evidence, than to be allured, by ac- 
 tual infpeftion, that a certain ftar is now no longer more 
 or lefs bright than fuch other ftars to which it has been 
 formerly compared ; provided we are at the fame time 
 affured that thofe other ftars remain flill in their former 
 unaltered luftre. But if the flar D will no longrc 
 ftand in its former order CDE, it mufl have undergone 
 a change ; and if that order is now to be exprefTed by 
 CED, the ftar has loft fome part of its luftre ; if, on 
 the contrary, it ought now to be denoted by DCE, its 
 brightnefs muft have had fome addition. Then, if we 
 fliould doubt the ftability of C and E, we have recourie 
 to the ordeis BCD and DEF, which exprefs their 
 luftre ; or even to ABC and EFG, which continue the 
 feries both ways. Now having before us the feries 
 BCDEF, or if neceffary even the more extended one 
 ABCDEFG, it will be impoflible to miftake a change 
 of brightnels in D, when every member of the feries is 
 found in its proper order except D." 
 
 In the author's jouraal or catalogue, in which the 
 order of the lufbe of the ftars is fixed, each ftar bears 
 its own proper name or number, e. g. " the brightnefs 
 of the ftar S Leonis may be exprefTed by /5 J 1 Leonis, 
 or better by 94 — 68 — 17 Leonis; thefe being the 
 numbers which the three above ftars bear in the Britidi 
 catalogue of fixed ftars." 
 
 This method of arrangement occurred to Dr Her- 
 fchel fo early as the year 1782; but he was diverted 
 from the regular purfnit of it by a variety of other .if- 
 tronomical engagements. After many trials, lie prj- 
 pofeJ, in the iranfaftions of the Royal Society of 
 London for 1796, the plan which appeared to him the 
 moft eligible. It is as follows: -Inftead of denoting 
 particular ftars by letters, he snakes ufe of numbers ; and' 
 in his choice of the ftars which are to exprefs the luftre 
 
 of
 
 CAT 
 
 [ 
 
 Cata'.Oi^ues of any particular one, lie diretls his firft view to perfeft 
 ofthe Scarf. eqygiity When two ftars feem to be finillar both in 
 ' ' brightncfs and inngnitude, he puts down their numbers 
 together, feparated merely by a point, as 30.24 Leonis; 
 but if two ftars, which at firft feemed alike in their 
 liiftre, appeared on a longer infpedtion to be diff'erent, 
 and the preference ftiould be always decidedly in tavour 
 of the fame ftar, he feparates thefe ftars by a comma, 
 thus, 41,9+ Leonis. This order muft not be varied ; 
 nor can three fiich ftars, as 20, 40, 39, Librx, admit 
 of a different arrangement. If the ftate of the henvens 
 ftiould be fuch as to require a different order in thefe 
 numbers, we may certainly infer that a change has ta- 
 ken place in the lullre of one or more of them. When 
 two ftars differ very little in brightnefs, but fo that the 
 preference of the one to the other is indilputable, the 
 numbers that exprefs them are feparated by a (liort line, 
 as 17 — 70 Leonis, or 68 — 17 — 70 Leonis. When two 
 ftars differ fo much in brightnefs, that one or two 
 other ftars might be interpofed between them, and ftill 
 leave fufficient room for diftinftion, they are diftlnguilh- 
 ed by a line and comma, thus, — , or by two lines, as 
 32— — 41 Leonis. A greater difference than this is 
 
 denoted by a broken line, thus 29 Bootis. On 
 
 the whole, the author obfervcs, the marks and diftinc- 
 tlons which he has adopted cannot poffibly be miftaken ; 
 " a point denoting equality of luftre ; a comma indica- 
 ting the leall perceptible difference ; a ftiort line to 
 mark a decided but fmall fuperiority ; a line and com- 
 ma, or double line, to exprefs a confiderable and ftriking 
 cxcefs of brightnefs ; and a broken line to maik any 
 other fuperiority which is to be looked upon as of no 
 ufe in eftimations that are intended for the purpofe of 
 direfting changes." 
 
 The difficulties that attend this arrangement are not 
 difguifed ; but the importance and utility of it more 
 than compenfate for the labour which it muft neccffarily 
 require. By a method of this kind, many diicoveries 
 of changeable and periodical ftars might probably have 
 been made, which have efcaped the moft diligent and 
 accurate obfervers. We might then, as the author fug- 
 gefts, be enabled to refolve a problem in which we are 
 all immediately concerned. 
 
 " Who, for inttance, would not wifti to know what 
 degree of permanency we ought to atcribe to the luftre 
 of our fun ? Not only the ftability of our climates, but 
 the very exiftence of the whole animal and vegetable 
 creation itfelf, is involved in the queftion. Where can 
 we hope to receive information upon this fubjeft but 
 from aftrononiical obfervations i If it be allowed to ad- 
 mit the fimilarity of ftars with our fun as a point efta- 
 blifhed, how neceff^rj- will it be to take notice of the 
 fate of our neighbouring/u/w, in order to guefs at that 
 of our own ? That7?ar, which among the multitude we 
 have dignified by the name oi fun, to-morrow may (low- 
 ly begin to undergo a gradual decay of brightnefs, like 
 fi Leonis, a Ceti, " Draconis, J" Urfse niajoris, and many 
 other diminiftiing ftars that will be mentioned in my ca- 
 talogues. It may fuddenly increafe, like the wonderful 
 ftar in the back of Caffiopea's chair, and the no lefs re- 
 markable one in the foot of Serpentarius ; or gradually 
 come on like f> Geminorum, S Ceti, K Sagittarii, and 
 many other increafing ftars, for which I alio refer to 
 my catalogues ; and, laftly, it may turn into a periodical 
 one of 25 days duration, as Algol is one of three days, 
 
 84 ] CAT 
 
 i Cephei of fivf, (5 Lyrae of fix, » Antinoi of feven Cafalt 
 days, and as many others as are of various periods." ofthe ! 
 
 Having thus explained the general principle on which '' 
 
 this catalogue is formed, as we find it in the author's 
 firft memoir on the fubjeft, we muft refer tlie leader to 
 the Doftor's own account for its particular arrange- 
 ment; obferving only that the catalogue fubjoined com- 
 prehends nine conftellations, which are arranged in al- 
 phabetical order, witli the comparative brightni-fs of the 
 ftars accurately ftated. In a fubfequcnt paper, publidi. 
 ed in the fame volume, he has completely verified the 
 utility of his method by experience, and ftiewn that there 
 is no permanent change of luftre in the ftars. In the 
 notes to his firft catalogue he mentioned a Herculis as 
 a periodical ftar. By a feries of obfervations on this 
 ftar, compared with ». OphiuchI, which was moft con- 
 venicntly fituated for his purpofe, he has been able not 
 only to confirm this opinion, but to afcertain its period. 
 His obfervations are arranged in a table, by means of 
 Avhich he determines that this ftar had gone through 
 four fucceffive changes in an interval of 241 days ; and 
 therefore the duration of its period muft be about fio 
 days and a quarter. This faft concurs with other cir- 
 cumftances in evincing the rotatory motion of the ftars 
 on their axes. " Dark fpots, or large portions of the 
 furface, lefs luminous than the reft, turned alternately 
 in certain direttions, either towards or from us, will ac- 
 count for all the phenomena of periodical changes in the 
 luftre of the ftars, fo fatisfaftorily, that we certainly 
 need not look out for any other caufe." If it be al- 
 ledged that the periods in the change of luftre of fome 
 ftars, fuch as Algol, ft Lyrte, i Cephei, and » Antinoi, 
 are ftiort, being only 3, 5, 6, and 7 days refpeclively ; 
 while thofe of Ceti, and of the changeable ftar in Hy- 
 dra, and that in the neck of the Swan, are long, a- 
 mounling to 331, 394. and 497 days; and that we 
 cannot afcribe phenomena fo different in their duratioa 
 to the fame caufe — it may be anfwercd to this objeftion, 
 that the force of it is founded on our limited acquaint- 
 ance with the ftate ofthe lieavens. To the 7 ftars, the 
 periodical changes of which were before known, we 
 may now add ^ Herculis, which performs a revolution 
 of its changes in 60 days. 
 
 " The ftep from the rotation of a Herculis to that of 
 Ceti is far lefs confiderable than that from the period 
 of Algol to the rotation of " Herculis ; and thus a link 
 in the chain is now fupplied, which removes the objec- 
 tion that arofe from the vacancy." The rotation of 
 the fifth fatellite of Saturn is proved by the change ob- 
 fervable in its light ; and " this variation of light, ow- 
 ing to the alternate cxpofition of a more or lefs bright 
 hemifphere of this periodical fatellite, plainly indicates 
 that the fimilar phenomenon of a changeable ftar arifes 
 from the various luftre of the different parts of its lur- 
 face, fuocefiively turned to us by its rotatory motion." 
 
 Befides, we perceive a greater fimilarity between the 
 fun and the ftars, by means of the fpots that muft be 
 admitted to exift on their furfaces, as well as on that of 
 the fun. 
 
 Dr Herfchel farther obferves, that the ftars, befides 
 a rotatory motion on their axes, may have other move- 
 ments ; " fuch as nutations or changes in the inchna- 
 tion of their axes ; which, added to bodies much flat- 
 tened by quick rotatory motions, or furrounded by rings 
 like Saturn, will eafJy account for many new phenome-
 
 CAT 
 
 [ »85 3 
 
 C A T 
 
 CnKinaria, na tliat may tlien offer ttiemfelvcs to our extended views." 
 
 C;\th3nnt. 'p,, djij p;,pe,- jj likewife fnbjoined a catalo^rue of nine 
 
 ' conftdlatioiis ; an.' the author promifei to e;ivc' the 
 
 whole of them in fuccefllve (hort catalogues on the fame 
 
 phn. 
 
 CATENARIA, or C.^ten.^ry Curve. See En- 
 cycl. and Arch in this Sufyplemenl. 
 
 CATH \RI-^4E II Eniprefs of all the Riiflias, aft- 
 ed fo confpicuous a part on the theatre of the world ; 
 pofTcfled fuch uncommon povrers of mind, highly culti- 
 vated by fcience and literature ; and was fuch a patron- 
 efs of fcience and literature in others —that it cannot 
 be deemed foreign from a work of this nature to give 
 fome account of the principal events of her more pri- 
 vate life. 
 
 Sophia Augusta Frederica, who, upon her mar- 
 riage to the grandfon of Peter the great, affumed the 
 name Cath.'vrcna Alexievna, was born at Stettin on 
 the 2d of May 1729. Her father was Chriftian .A.u- 
 guftus, prince of Anhalt Zerbft Dornburg, at that time 
 major general in the Pruffian fervice, commander in chief 
 of the regiments of infantry, and governor of the town 
 and fortref? of Stettin. Her mother, who was born 
 princefs of Holftein Eutin, was a woman of great parts 
 and beauty, of nearly the fame age with the prince-royal 
 of Pruflja, afterwards Frederic the Great, with whom 
 file kept up a regular correfpondence, and who after- 
 wards contributed to the aggrandifement of her daugh- 
 ter. This accomplllhed princefs took upon herfeli the 
 care of educating the young Sophia, whom fhe brought 
 up in the fimpkft maimer, and would not fuffer to ex- 
 hibit the Icaft fymptoms of that pride to wliich fhe 
 had fome proDenllty from her earlielt childhood. The 
 confequence of this falutary reftraint was, that good hu- 
 mour, intelligence, and fpirit, were even then the ftri- 
 klng features of her youthful charafter. Being natu- 
 rally addifted to reading, to reflcftlon, to learning, and 
 to employment, (he was taught tlie French and other 
 fafhionable languages ; and was inftrufted to read fuch 
 books chiefly as might make her acquainted with hifto- 
 ry and with the principles of fcience ; whilft the doArines 
 of the Lutheran religion were carefully explained to her 
 by a divine, who little thought how foon his illullrious 
 pupil would embrace another faith. 
 
 The Emprefs Elizabeth, who then fwayed the fcep- 
 tre of Rullia, had in early life been promifed in marriage 
 to the young prince of Holftein Eutin, brother to the 
 princefs of Anhalt Zerbft ; but at the indant when the 
 marriage was about to be celebrated, the prince fell fick 
 and died. Elizabeth, who loved him to excefs, became 
 inconfolabk, and in the bitternefs of her grief made a 
 •vow of celibacy. This vow, though fenfual, and even 
 Saicivlous, flie kept fcf far as never publicly to acknow- 
 ledge any man as a hufband ; and upon her afcending 
 the throne of her ancertors, (he called her nephew the 
 Buke of Holftein Gottorp to her couit, where he was 
 lolemnly proclaimed, when fourteen years ot age. Grand 
 Duke, with the title of Imperial HIghnefs, and decla- 
 red fncceflor to the Emprefs Elizabeth. 1 o fecure the 
 fucceflion in the family of Peter the Great, the Emprefs 
 was very defirous to have her nephew married ; and the 
 princefs of Anhalt Zerbft, not ignorant of the tender 
 remembrance which fhe ftill prefer ved for her brother, 
 conceived the idea of placing, by means of it, her daugh- 
 ter on the throne of Ruflia. She communicated her 
 SuppL. Vol. I. Part I. 
 
 plan to the king of PralTia, who not only applauded it, Ci'hnri • 
 but lent her his affiftance to cany it into execution. """ 
 
 Full of ambitious hopes, therefore, the princefs re- 
 paired with her daughter to St Peteilburg, where (he 
 was received with frienrifhip by F.li/.abetli, and where 
 the young Sophl-i foon made a. conliderable imprefTion 
 on the mind of the Grand Duke. As Peter was well 
 made, of a good figure, and, though uneducated, not 
 deftitute of natural talents, the attachment became reci- 
 procal ; and the princefs of Zerbft, throwing hcrlelf at 
 the feet of the empref?, affured her, that the two lovers 
 were attached to each other by a paflion uuconqner.ible ; 
 and, calling to her mind the lote which (he had herfelf 
 borne to the prince of Holflein, conjured her to pro- 
 mote the happinefs of that prince's niece. The ftrata- 
 gem fucceeded. The choice of Elizabeth was next day 
 announced to the council and to the foreign minifters ; 
 and preparations were made for celebrating the mar- 
 riage with a magnificence worthy of tlie heir of the 
 throne of the RulTias. In the mean time the Grand 
 Duke was feized with the fmall-pox, from which, th>>' 
 he recovered, it was with fuch a change of features, as 
 rendered him, from being comely, almofl hideous, and 
 converted the love of the young princefs of .'\nh:ilt, if 
 indeed (he ever felt for him tiiat paffion, into horror and 
 dilguft. She was not, however, of a dilpofition to let 
 a disfigured countenance frighten her from a throne. 
 She embraced the Greek religion, changed her name 
 from Sophia Augufta Frederica to Catharina .\i.exi- 
 EVNA, and with the entire approbation of Elizabelli 
 was married to her iiepheu' the Grand Duke. 
 
 For fome time this ill-matched pair lived together, 
 though without love, yet on terms apparently decent ; 
 but a mutual dlflike gradually took place between them, 
 which the courtiers quickly difcovered, and were at 
 pains to foment into hatred. Peter was now ugly, and 
 his mind was uninformed. Catharine, if not a beauty, 
 was at leaft a lovely woman, and highly accompli fhed. 
 She could find no entertainment in his converfation, and 
 he felt himfelf degraded by her fuperiority. A faction 
 was formed at court, headed by the great chancellor 
 BeftuchefF, to exclude the Grand Duke from the throne, 
 and to place Catharine at the head of affairs ; and to 
 accomplifh this end, every art was employed to till the 
 feeble mind of the emprefs with jealoulies of her nephew, 
 and with a contempt of his clnraAer. He was repre- 
 fented at one time as extremely ambitious, and capable 
 of the moft daring enterprifes, to get immediate poftef- 
 (ion of the throne ; and at another, as a wretch given 
 up to drunkennefs and to every unprincely vice. 
 
 The confequence of the firft of tlufe accufations was, 
 that he was kept at a diftance from his aunt, and a 
 ftranger to public afjairs ; and being wholly unemploy- 
 ed, that time which his education had not fitted him to 
 fill up with reading, refledlion, and rational converfa- 
 tion, hung fo heavy on his mind, that it was no diffi- 
 cult matter f'.r thofe diflipated young men, who were 
 placed about him for that very purpofe, to initiate him 
 in the habits of drunkennefs, and the otdei mean prac- 
 tices to which it was pretended he had long been de- 
 voted. In fuch a fcliool, it wai. no wonder that he be- 
 came a proficient in grovelling difTipatlon ; or that, be- 
 ing unpolifhed, and even of rude manners, he chofe for 
 his companions fome of the ioweft of the people. 
 
 Catharine, in the mean time, ianguifhed for that hap- 
 A a pincis
 
 CAT [18 
 
 CatTiarine. plnefa which (he could not find in the foclcty of her 
 
 * * hufband. She was fond of pleafure ; but It was that 
 
 comparatively refined pleafure whicli (he had enjoyed at 
 the court of Berlin. She loved balls, mufic, and ele- 
 gant converfation, and could take no (hare in the drunk- 
 en revels of Peter. Among the young men with whom 
 lie was furrounded, his chamberlain Soltikoff was parti- 
 cularly remarked for the elegance of his tafte and the 
 graces of his perfon ; and though yet fcarcely more than 
 a boy ill years, he was faid to have obtained the favours 
 of feveral ladies of the court. Succtls had made him 
 conlident and ambitious ; and his ambition prompted 
 him to afuire at making a conqueft even of the Grand 
 Duchefs. By ftudying her tafte, and contriving to 
 amufe her, he was at lall fuccefsful ; and obtained from 
 her Imperial Higbnefs every favour which he could 
 wifh : but he enjoyed not his fortune with moderation, 
 and his enemies contrived to get him placed in an ho- 
 nourable oiTice at a-dlftance from the court. He wss 
 commiflioned to repair to Stockholm, with the title of 
 Envoy Extrsordinary, to notify to the king of Sweden 
 the birth of Paul Petrovitch, of whom the Grand Duch- 
 
 * 0(51. 1, efs had juft been delivered *. The prefuinptuous Solti- 
 '754- koif, proud of the employment, fet off with halle to 
 
 Sweden, and left it with equal fpeed. But fcarcely had 
 he quitted Stockholm, on the wings of love and ambi- 
 tion, when he was (lopped on the road by a courier, 
 who put into his hands an order for him to go imme- 
 diately to Hamburg, and there to refide in the quality 
 of minifter plenipotentiary from the court of Ruflia. 
 
 Catharine for fome time preferved her attachment to 
 the exiled chamberlain ; but all at once the prefence of 
 a ftranger, whom fortune had brought to the court of 
 Ruflia, made her forget the lover whom (he no longer 
 faw. This perfon was Staniflaus Poniatowlliy, the late 
 king of Poland, who (irft m:ide his appearance at St Pe- 
 teriburg in the train of the Britiih ambaflador, and very 
 quickly gained the affeftions of the Grand Duchefs. In 
 carrying on this intrigue, the lovers were not fo cau- 
 tious as to deceive the eyes of the envious courtiers, who 
 reported to the emprefs not only all that they faw, but 
 whatever they fufpefted. Elizabeth was incenfed, and 
 commanded Ponlatowfliy to quit without delay the domi- 
 nions of RufTia. The accomplifhed Pole obeyed ; but 
 foon returned clothed with a charafter which made him 
 in fome degree indeoendent of the emprefs. 
 
 The Count de Bruhl, then prime minifter to the 
 king of Poland, faw of what importance it was to his 
 mafter to have a povrerful inteieft at the couit of Riif- 
 fia. He was likewife no ftranger to the p^fiion which 
 the Grand Duchefs entertained for Poniatow(l<y ; and 
 having got that nobleman decorated with the order of 
 the White Eagle, lie fent him back to St Peterfburgh in 
 the quality of miniiler plenipotentiary from the repub- 
 lic and king of Poland, l^or was this all that Bruhl 
 did for the two lovers. Being informed by the chan- 
 cellor Beiiuchcff, that the Grand Duke and Grand 
 Duchefs were langui(hing in a penury unworthy of their 
 rank, he remitted to Ponlatowfliy 6coo ducats, to be 
 employed, in fuch a manner as he might judge beft, for 
 iecuring che favour of the prince and his cnnfort. The 
 ambaffador pro(ited by thefe counfels and bcnetaftions. 
 He was already fure of the Grand Duchefii's heart, and 
 he very quickly gained the favour of her hufband. He 
 talked Englifli and German with him j drank, fmoked, 
 
 5 ] CAT 
 
 abufed the French, and extolled the king of Prafila Cashsrine. 
 with unlimited praife. ■ ' 
 
 The Grand Duchefs was fo blinded by her paflion, 
 that fhe was never without Poniatowflcy in her company. 
 She devoted to him the whole of her time ; and fhe 
 made tills intimacy fo little a fecret, that public report 
 was loud to her prejudice. In the mean time (he was 
 delivered of the Princefs Annef , who lived only fifteen f February 
 months. The Grand Duke was the only perfon about '75S. 
 court who feemed to know nothing of what was paffing. 
 His whole time was occupied in copyiu'4, with fervlle 
 affeftatlon, the air, the manners, the tone of the king 
 of PrulHa ; and in drefling a little army at Oranlanbaum 
 in the Pruftian uniform. His eyes, however, were at 
 laft opened. Some of the courtiers, from hatred to the 
 chancellor, who countenanced the Intrigue between the 
 Grand Duchefs and the Polifh ambaffador, roufed hi* 
 jealoufy in order to deftroy their enemy. They fuc- 
 ceedcd. He forbade his wife to be feen with Ponla- 
 towfl<v, and prevailed with the emprefs to deprive the 
 chancellor of his office, and to banlfh him to an eftatc 
 which he had i 20 verfts beyond Mofcow. 
 
 Catharine had now to fupport at once the averfion of 
 her hufband, the indignation of the emprefs, the in- 
 fulting dildaln of a court, which a few days before was 
 lavifh of its alTiduities and fmiles; and what afflifted her 
 moft of all, the dread of lodng for ever her favourite Po- 
 niatowlky. Her courage, however, did not forfake her. 
 Ponlatowfliy was Indeed recalled, and left Ruffia, after 
 fuffering fome deferved indignities from the Grand 
 Duke, who about this time formed a conneftlon with . 
 one of the daughters of the Senator Vorontzofl", brother 
 to the new chancellor. This lady, Elizabeth Roma- 
 novna Vorontzoff, was elder (ifter to the Princefs Dafh- 
 koff, who afted fo confplcuous a part in the revolution 
 which fet the crown on the head of Cacharine. She 
 was beautiful, but vain ; and poCfeffed not either the wit 
 or the underftanding of her lifter. 
 
 In the mean time the health of the emprefs vlfibly 
 declining, Catharine was veiy defirous of being recon- 
 ciled to her : but the irritated fovereigu would liften to 
 no accommodation, except on terms too humiliating for 
 the haughty fplrit of the Grand Duchefs. Catharine, 
 therefore, abfented herfelf from court, and aflied permif- 
 fion to retire into Germany. This, as fhe had forefeen, 
 was refufed. Elizabeth was too fond of the young Paul 
 Petrovitch to permit the departure of his mother, and 
 thereby expofe him to the danger of being at fome fu- 
 ture period declared illegitirnate. She took the Grand 
 Duchefs again into favour ; and it is thought, that had 
 fhe lived a little longer than (he did, ihe would have ex- 
 cluded Peter from the throne, and declared Paul her 
 immediate fucceffor. 
 
 Whim the emprefs was meditating the aggrandife- 
 ment of the young prince and his mother, the Grand 
 Duke liad conceived a plan for degrading them both. 
 He had refolved, at the moment his aunt (hould clofe 
 her eyes, to aftemble his troops, to get himfelf proclaim- 
 ed emperor, to repudiate the Grand Duchefs, to declare 
 the young Paul Petrovitch illegitimate, and publicly 
 to marry his miftrefs Elizabeth Romauovna Voront- 
 zoff. We have fhewn elfcwhere (fee Russia, n" 72. 
 Eiyycl.) how this plan, when almoft ready to be carried 
 into execution, was betrayed to Catharine, who, ever 
 fiRce her caballing with the Chancellor Bcftuchefif, had 
 
 refolved,
 
 CAT 
 
 afh'.iriiit;. refolved, by fome means or other, to fnatch the fcoptre 
 ""^ fiom the feeble hand of her hufb'nd. At prcfent, we 
 believe (he was not acquainted with it ; and though fhe 
 had, fine could not now have turned it to htr advan- 
 ta-re, as her party, ever fincc the difgrace of DeftuchefT, 
 was v'ithout a leader of any abilities. 
 
 Amid thefe ditlraftions, caufed by the profpeft of the 
 death of the emprcfs, and the known hatred of the 
 Grand Duke and Duchefs to each other, Count Panin, 
 preceptor to the young prince, devoted hinifelf entirely 
 to Catharine. He widied to fee her pofTefTcd of all the 
 power of the empire ; but he was afraid to proceed to 
 the extremity to which (he propofed to go, and to de- 
 prive Peter of the name of Emperor. He contrived 
 therefore to procure an apparent i-econciliation between 
 the Grand Duke and his confort, as well as between him 
 and his aunt Elizabeth ; and he had almoft perluadcd 
 the filly prince not to affume the foverelgn power on 
 the death of the emprefs, till he Ihould be iolemnly in- 
 veiled with it by a decree of the fenate. Could he ob- 
 tain this point, he knew that the power of Peter would 
 be limited, and the authority fecured to his wife and his 
 fon. He was, however, difappoiuted. Catharine her- 
 felf dlfapproved of this plan, and concun-ed with the 
 real friends of herhufband in adviling him " to conform 
 to eftablilhed cuftom in affuming the reins of empire." 
 
 He had hardly received this advice \»hen word was 
 brought him that the Emprefs Elizabeth was dead (a ) ; 
 and the courtiers preffed in crowds about him. He 
 accofted them with dignity, received the oaths of the 
 officers of his guard, and feemed at once to have laid 
 afrde his weaknefs. In an hour he got on horlebaek, 
 traverfed the ftreets of St Peterfburgh, and dillributed 
 money among the multitude and tlie foldiers. He had 
 been fo treated by his aunt, that he could not poffihly 
 be grieved at her death ; but in paying the laft duties 
 to her remains, he betrayed no indecent elation. The 
 fir ft aftions of his reign were prudent and patriotic, and 
 fuch as would have done honour to a greater prince. 
 He appeared to be reconciled to his wife, in whofe 
 company he fpcnt much of his time ; he recalled from 
 prifon and baniihmenc 17,000 pcrfons, fome of them of 
 rank and of great talents, who had been the viftims of 
 Elizabeth's jealous timidity ; he permitted the nobility 
 to bear arms or not at their own difcretion, freeing them 
 at the fame time from the extreme fervitude under 
 which they had been held by his immediate predecef- 
 fors ; and he aboliflied thefecret committee, an infamous 
 inquifitorial tribunal, which ever fmce the reign of the 
 ^father of Peter the Great had been the chief engine of 
 Ruffian defpolifm. 
 
 He neglefted, however, one thing ; which, among 
 the people over whom he was appointed to reign, would 
 have contr-ibuted more to the fecurity of his throne than 
 all the wife and beneficent ediAs which he had publifh- 
 ed. He made no preparations to be crowned at Mof- 
 cow. Inftead of complying with this ancient ceremony, 
 and humouring the prejudices of his fuperftitious fub- 
 jefts, he thought of nothing but of war with Denmark, 
 and of a perfonal interview with the king of Pruffia in 
 Germany. His admiration of that great monarch hur- 
 
 [ »S7 ] 
 
 CAT 
 
 lied him indcrj into the moil extravagant follies. Not Ca'bjrJ-r 
 contented with giving him peace, and entering into an • 
 ofTenfive and defenfive alliance with him, he had the 
 meannefs to folicit a commiifion in liis army, and to ac- 
 cept of the rank of major-general. Of this title he feem- 
 ed more vain than of that of Emperor of all the Ruf- 
 fias. He conilanlly wore the PrufRan unifoim; intro- 
 duced among his troops the Pruffian difcipline, which, 
 though better than tlieir own, was difagrceable, bccaufe 
 it was new, and nuich more becaufe it was German ; 
 and he railed his imclc, a man of no military talents, and 
 a foreigner, to the dignity of gcneraliiCmo of the Ruf- 
 fian armies ; giving him at the fame time the particular 
 command of the horfe-guards, a body of men which had 
 never before been under ap.y command but that of the 
 fnpreme head of the empire. Nor did his infatuated 
 predileftion for Germany, a country abhorred by the 
 Ruffians, ftop even here : He diibanded the noble guards 
 which had placed Elizabeth on the tiirone, difmilTed 
 the horfe-guards from the fervice which they performed 
 at court, and fubftituted his Holllein guards in their 
 place. 
 
 Whilft he was thus alienating from himfelf tlie affec- 
 tions of the army, he contrived to difguft another or- 
 der of men, whofe attachment he fhould hav; -aboured 
 above all things to retain. He was at pains to !aew his 
 preference of the Lutheran faith and wor.l^ip 10 the 
 doftrines and ceremonies of the Greek church ; he at- 
 tempted to make fome alterations in the drels of the 
 monks ; he annexed great part of the pofTeffions t.f the 
 church to the domains of tiie crov.'n ; and he baniflied 
 the archbifhop of Novogorod, who oppofed thefe inno- 
 vations ; and found himfelf obliged luddenly to i-ecal 
 him. 
 
 He had now returned to his former courfes. He 
 {hut himfelf up for whole days with his miftrefs and 
 drunken companions ; he compelled the nobility and 
 ladies of the court to (it in company v/ith buffoons and 
 comedians ; he infulted every foreign minilter hut the 
 minifters of Great Britain and Pruffia ; and he made no 
 fecret of his intention to repudiate the emprefs, declare 
 Paul Petrovitch illegitimate, and marry the Ccuntefs 
 Vorontzoff. Convinced, however, as it would ftcm, 
 that he could not be a father, he refolved to adopt 
 Prince Ivan, the defcendant of the elder brother of Pe- 
 ter the Great, whom Elizabeth had dethroned and con'i- 
 ned in prifon; to declare him his lucceflbr; and to unite 
 him in marriage with the young princefs of HoUteiti 
 Beck, who was then at St Peterlburgh, and whom he 
 cherKhed as his daughter. 
 
 This Inconfillent and weak conduft of the emperor 
 turned the attention of all orders of men to the em- 
 prefs, who made it her fole employment to gain thofe 
 hearts which he was lofing. Inftrufted from her in- 
 fancy in the arts of diflimulation, it was not difficult for 
 her to afFcft, in the fight of the multitude, fentiments 
 the moft foreign to her mind. The pupil of the French 
 philofo'phers put on the air of a bigot to the moft fu- 
 perftitious ceremonies of the Greek religion, and treat- 
 ed the minifters of tliat religion with the profoundeft 
 reverence. And whilft her hufband was getting drunk 
 A a 2 amidft 
 
 (a) Chrillmae day 1761 according to the Ruffian calendar, or the 5th of January 1762 according to our«.
 
 CAT [ X 
 
 Cath arine, amidft a rabble of buffoons, and difgrfti'^g evcty perfon 
 
 ^——v—^ of dectncy who approached him, llie ktpt her court 
 
 with a mixture of dignity and affability, which attraft- 
 
 ed to her all who, by capacity, courage, or reputation, 
 
 were capable of ferving her. 
 
 Correft, however, as her public conduft appeared, 
 her private life was not lets- licentious than formerly. 
 While yet Grand Duchefs, (he had formed a very ten- 
 der coiincflion with Gicgory Orloff, a man of mean 
 birth, and of no education, but podeffed at once of 
 perfonal beauty and the moft daring courage. He had 
 an inferior commiffion in the artillery, while his two 
 biothers were common foldiers in the regiments of 
 guards. The intrigue which (he carried on with him 
 WHS known only to one o' her women named Catharine 
 Ivanov'ia ; nor did O'loff himftlf for fome time fufpcft 
 the rank of the lady who fo lavifhly conferred upon him 
 her favt ars in fecret. At laR, finding him intrepid and 
 difcvcct, rtie difcbvtred hevfelf, unveiled to him all her 
 ambitious defgns, and eafily prevailed with him and his 
 brothers to enter with zeal into her confpiracy againft 
 the emperor. Orloff likevvife gained over Bibikoff his 
 friend, a Lieuten.mt Paffick, with other ofScers ; and by 
 their means eafdy leduced fome reglrr:ents of the guards. 
 The i'rince(s DafV koff was ftrongly attached to Catha- 
 liiie, we believe, from worthy motives, and had frequent 
 meetings with Orloft" on the bufinefs of the confpiracy, 
 v/ithout fufpeftir.g that he was fo much as known to 
 the emprefs. Count Pain'n, too, and the Hetman of 
 the Kofacks, were deteimined to tumble Peter from the 
 throne; but they were not inclined to go all the lengths 
 propofed by Catharine and her two favourites. Ho- 
 ping to enjoy the aiStuai power of the empire them- 
 felves. thty were for declaring Paul Petrovitcli empe- 
 ror in the room of his father, and conferring upon his 
 mother the name and authority only of regent ; while 
 the princefs and Orloff, knowing the fentiments and 
 withes of the emprefs, were refolved to veft her with 
 fovereign power, or to perilh themfelves in the hazar- 
 dous attempt. 
 
 In the mean time the anniverfary of the patron faints 
 of Ruffia was at hand, when Peter had determined, at 
 the conclafion of the feftival, to divorce the emprefs, 
 fliut her up in prifon, declare her fon illegitimate, and 
 publicly marry his miftrefe. As they who plan a con- 
 spiracy are always more vigilant thf.n thofe againft whom 
 It is diretted, the friends of Catharine were carefully 
 informed of all that paffed about the emperor, whilft he 
 ■was kept in total ignorance of their proceedings. It 
 was therefore rcccliary for them to unite in the fame 
 plan, and to carry it quickly into execution ; for delay 
 or divifions would inyolve them all m one common ruin. 
 The emprefs contrived to bring over the Hetman en- 
 tirely to her views ; and the Princefs Dafhkoff, by the 
 fecrifice, it has been faid, of her charms, found little dif- 
 ficulty in reconciling Count Panin to the fame mcafures. 
 They now agreed to feize the Tzar on his arrival at Pe- 
 terhoff, an Imperial palace on the (hore of the Gulf 
 ofCronfledt, where he propofed to celebrate the ap- 
 proaching feftival ; and they were wailing impatiently 
 for the moment of adion, when all at once, their plot 
 was difcovered. 
 
 Paffick, who has been mentioned among the confpi- 
 rators, had gained the foldiers of the company of guards 
 ia tivhich he was a licuunant ; bul one of them, who 
 
 SS ] CAT 
 
 thought that his cap^a'" ""as in the fecret, afl-ced that Catha 
 officer one evening. When they v/ere to take up arms '~~*v 
 againft the emperor ? The captain, furprifed, had re- 
 courfe to diflimulation, and eafily drew from the foldier 
 all that he knew of the confpiracy. It was nine o'clock 
 at night. Vaffick was put under arreft ; but found 
 means to flip into the hands of a man who had been 
 placed as a fpy over him by the Princefs Dafhkoff, a 
 fcrap of paper containing thefe words, " Proceed to ex- 
 ecution this inftant, or we are undone." The man was 
 defired to carry it to the Hetman, by whom he would 
 be handiomely rewarded ; but he hurried with it to the 
 princefs, who inllantly communicated the intelligence to 
 the other confpirators. She herlelf put on man's appa- 
 rel, and haftened to the place where ftic was accuftomed 
 to meet Orloff and his friends ; where ftie found them, 
 as impatient as herfelf to carry their plot into imme- 
 diate execution. 
 
 During this awful crifis the emprefs was at Peter- 
 hoff, at the diftancc of 25 verfts from St Peterfburgh ; 
 and one of the brothers of Gregory Orloff, named A- 
 lexius, undertook to find her out, whilft he himfelf, 
 with his other brother and Bibikoff his friend, repaired 
 to the barracks for the purpofe of inltrufting the fol- 
 diers of their party how to aft on the tirft f:gnal. A- 
 lexius Orloff carried with him a fiiort note from the 
 Princefs Dafhkoff, but neglefted to deliver it ; and the 
 emprefs, being fuddtnly roufed from a found deep, wai 
 much alarmed, when fhe faw at the fide of her bed a 
 foldier of whom fhe knew nothing. Her alarm was in- 
 cieafed when the ftranger laid, " Your majefty has not 
 a moment to lofe ; get ready to follow me ;" and in- 
 ftatitly difappeared. She tofc, however, and calling ber 
 woman Ivanovna, they difguifed themfelves in fuch a 
 manner that they could not be known by the fentinela 
 about the palace ; and the foldier returning, they hur- 
 ried with him to a coach which was waiting at the gar- 
 den gate. Orloft took the reins, but drove with fuch 
 fury that the horles ioon fell down ; and they were 
 obliged to travel part of the way on foot. They had 
 not, however, gone far, when they met a light country 
 cart ; and fhe who was afpiring to the throne of the 
 greateft empire in the world, was glad to enter the ca- 
 pital of that empire in this humble vehicle. 
 
 It was feven in the morning when fhe arrived in St 
 Peteifburgh: and to the ioldicis, who gathered about 
 her in great numbers, fhe laid, that " her danger had 
 driven her to the ncccflity of coming to aflc their afliil. 
 ance ; that the Tzar had intended, that very night, to 
 put her and hsr fon to death ; and that fhe had fo great, 
 confidence in their difpofitions, as to put herlelf en- 
 tirely into their hands." They immediately fliouted, 
 " Long live the emprefs!" And the chaplain of one of 
 the regiments fetching a cruatix, received their oaths- 
 of fidelity. 
 
 The troops, however, were not unanimous in this re- 
 volt. Though Gregory Orloff was treafurer of the ar- 
 tillery, and well enough beloved by the foldiers, that 
 corps refufed to follow him until he fliould produce the 
 orders of Villcbois their general : and that officer, with- 
 held either by hdclity to the emperor or by fear, pre- 
 fumed to fpeak to Catharine of the obftades which yet 
 remained for her to furmoiuit; adding, that fhe ought to 
 have forefeen them. She haughtily replied, that " fhe 
 had not fent for him to aik what fix ought to have 
 
 forefeen,
 
 CAT 
 
 [ 189 1 
 
 CAT 
 
 Cath?.r!ne. lorefeen, but to know how he intended to aft." " To 
 ^■""v""" obey yiiur Mrjefty," returned Villtbcis ; and putting 
 himfeif at the head of his regiment, he immediately join- 
 ed the confpirators. So lipe indeed were the minds of 
 all men for this revolt, that in the fpace of two hours 
 the emprefs found herfelf furrounded by 2000 warriors, 
 together with great part of the inhabitants of Peterf- 
 but?h : and with that numerous train of attendants Hie 
 repaired to the church of Kafan, where the archbifhop 
 of Novogorod, Jetting the Impcilal crown on her head, 
 proclaimed her fovercign of all the Ruflias, declaring, 
 at the lame time, f'aul Petrovitch her fucceifor. 
 
 Matters had now proceeded by much too far to ad- 
 mit of any compromife between Catharine and her huf- 
 band : but had the infatuated Tzar put his affairs whol- 
 ly into the hands of Marihal Munich, that intrepid ve- 
 teran would have tumbled the emprefs from her throne 
 almoft as quickly as (he had got poffefiion of it. He 
 afled, however, a very different part. Upon receiving 
 intelligence of what had been done at St Peterfburgh, 
 he afked indeed the Marfhal's advice, but fuffered him- 
 ftlf to be guided by his miflrefs and timid companions. 
 Through their terrois and his own irrefolution oppor- 
 tunities were loft v/hich could never be recovered ; for 
 though his Hclftein guards, with tears in their eyes, 
 Iwore that they were all ready- to facritice their lives in 
 his Icrvice, and though the old Marffial offered to lead 
 them againil the rebels, faying to the emperor, " I will 
 go before you, and their fwords fhall not reach you till 
 they have pierced my body," he was peifuaded to treat 
 vith the emprefs, to acknowledge his mliconduft, and 
 to ofier to (hare with her the fovereign power. At 
 lalt he was weak enough to abandon his troops, and to 
 furrender at difcrction to his contort ; whofe creatuiis 
 hurried him from Oranienbaum to Peterhofl', ftripped 
 him of all his clothes, and, after leaving hiin for lome 
 time in his fliirt, a butt to the outrages of an infoleiit 
 foldiery, threw over him an old morr.ing-gown, and ihut 
 liim up alone, with a guard at the door of his wretched 
 • July JO. apartment. On the 29th of June, O. S.* 1762, Count 
 Panin was fent to him by the emprefs; and after a long 
 conference, prevailed with him to write and fign a lo- 
 lemn reiignation of his crown, and a declaration of his 
 utter incapacity to govern fo great an empire. 
 
 The revolution was now complete, and Peter fcemed 
 to enjoy fome conipofure of mind ; but in the evening 
 he was carried a priloner to Ropfcha, a fmall Imperial 
 palace, at the diflance of 20 verfts from Ptttihofl, where 
 he V 3s murdered ^m the 17th of July, juit one week af- 
 ter his depoiition. Of the manner of his death difierent 
 accounts have been given. By fome he is laid to have 
 been poifoned ; by others, to have been ftrangled by one 
 of the Orloflo ; and a few have thought that he perifhed 
 by the fame means as Edward II. of England. Whe- 
 ther the emprefs was acceflbry to his death is not known ; 
 though it is certain, that fo far from making any in- 
 quity after his murderers, fhe aflefted to believe that he 
 had died naturally of the piles ! 
 
 The firft care of Catharine was to rewaid thofe who 
 had been the principal aftors in the revolt. Panin was 
 made prime miniiler ; the Orloffs received the title of 
 Goniit ; and the favourite Gregoty was appointed lieu- 
 tenant-general of the Rufiian armies, and knight of the 
 order of tit Alexander Nefsky, the fecond order of the 
 empire. Several officers of the guards were promoted, 
 
 of whom 24 received confidcrable eflatcs ; and among Catharine. 
 
 the foldiers, whom fhe treated with the greatcfl affabi- ' " ' 
 
 lity, brandy and beer were liberally dilliibuted. The 
 Chancellor Beftucheff, who had been the mod inveterate 
 enemy of Peter, was recalled from his exile, reltored to 
 his rank of field- marrtial, and had an annual penfiMi fet- 
 tled upon him of 20.000 rubles. To the friends of the 
 emperor fire behaved with great moderation. P.incc 
 George, whom he had conflituted Duke of Courland, 
 was indeed obliged to renounce his title ; but the ad- 
 miniftration of Holflein was committed to him, and he 
 ever after ferved the emprefs with zeal and fidelity. 
 
 The news of the revolution was foon fpread over 
 Europe ; and none of the foverelgns, tliough they knew 
 by what fteps Catharine had mounted the thi-one, heA- 
 tated for a moment to acknowledge her title. She was 
 not, however, at perfeft eafe in her own mind ; nor was 
 her right recognifed by all her lubjeffs. Though fhe 
 publifhed manifeftoes, fettiirg forth the intentions of the 
 late emperor towards her and her fon, which made rc- 
 fillance necefTary ; though in tliefe papers fhe attribu- 
 ted her elevation to the wifhes of her people and the 
 providence of God ; and though fhe called upon all who 
 were fmcerely attached to the orthodox faith of the 
 Greek chutch, to confider the fudden death of Peter as 
 the judgment of heaven in favour of the revolution — yet 
 in the diftant provinces no exaltations were heard ; both 
 foldiers and peafants obferved a gloomy filcnce. Even 
 at Mofcow, fo great was the cifaffeftion to Catharine'e 
 government, that it was fome time before fhe could ven- 
 ture to go to that city to be crowned ; and fhe found 
 in it at laft fo cold a reception, that fhe very quickly 
 returned to St Peterfburgh. 
 
 Nor was this the only caufe of her uneafinefs. The 
 connetlion between Orloff and her became vlfible, and 
 gave jirft offence to her other friends. The prinrcfs of 
 Dallikoft firft perceived it ; and when fhe prtfuiiied tO' 
 expofliilale with the emprefs on the meannefs and im- 
 prudence of her pafTion, (he was banifhed from the 
 court to Mofcow. Count Panin and the Hetrtjan faw 
 with iiidignalion that they had dethroned the grandfon 
 of Peter the Great, to aggrandifc a rude and hiw born 
 upflart. Cabals and confpiiacics were entered into by 
 high and low, both agdinll Catharine and againft her 
 favourite ; and it required all her abilities and fiimrjcfs- 
 to prefer ve at once her throne and her lover. Un one 
 occafion flie hoped to obtain from the Princefs Dafh- 
 koff fufticient proof that Panin and the Hctman of the 
 Kofacks were concerned iu a plot which had jull been 
 dilcovered ; and with this view fhe wrote to het a letter 
 of four pages, tilled with the moil tender epithets and 
 the moft niagnllicent promifes, conjuring her in the name 
 of their loiig-ftandrng friendfliip, to rcvesl what flie 
 knew of the recent conlpiracies. With becoming mag-- 
 namity, the princefs replied, " Madam, 1 have heard 
 nothing ; but if I had heard any thing, I fhould take 
 good care how I fpoke of it. What is it you require 
 of me ? That I fliould expire upon a fcafJold ? I am 
 ready to mount it." 
 
 Catharine, Gel-pairing of conquering fuch a fpirit, at- 
 tempted to attach to her thofe whom flie dared not to 
 punifh. Some of the inferior confpirators were banifh- 
 fii to Siberia, while Panin and the Hetman, whom flie 
 niofl dreaded, received additional marks of her favour, 
 la the meaa litne, to gain the ati'ediuus of the people
 
 C A T 
 
 CMhtfJre. nt large, (lie paid tlic utmofl: attention to die adminiftra 
 ' /~~— tion of jurtice ; formed mav^'nificcnt ellablilhaients for 
 the education uf the youth of both fcxeB : founded hof- 
 pitals for orphans, for the fick, and for lyinL(-in \>.omen; 
 invited foreigners of all nations, pofTtlTed of any merit, 
 to fettle in different parts of lier vaft territories; increa- 
 fed the naval force of the empire ; and gave fuch en- 
 couragement to the cultivation of every elegant and ufe- 
 ful art, that in the (hort fpace of a year and a half from 
 her acceffion to the throne, the national improvement of 
 Ruffia was vifible. 
 
 In the good fortune and glory of Catharine, no one 
 rejoiced more fincercly than Count Poniatowfty. He 
 approached towards the confines of Ruffia, and wrote 
 to her in the tendereft Ryle of congratulation, requeft- 
 ing riermifTion to pay his refpetls to her in the capital 
 of htren.pire It is not improbable that he flattered 
 himfelf with the hopes that fhe would give him her 
 hand in marriage, and thus raife him to the throne of 
 the Tzarsi ; but fhe hadpromifed to the Emprcfs Eli- 
 zabeth, that (he would never again lee the count ; and 
 to ih-t promife fhe at prefent adhered. She wrote to 
 him, however, in the moll affeftionate terms ; and tho' 
 fhe ga<^ him no encouragement to repair to St Pttevl- 
 burgh, fhe affured him that flie had other profpefts in 
 view for his aggrandi'tment. and that he might depend 
 upon her perpetual fiicr.dfhip : and (he foon appc.red 
 to be as good as her word. On the death of Auguftus 
 III. (he raifed her foimtr favourite to the throne of 
 Poland, in oppofition to the wilhes of the courts of 
 Vienna and Verfaillts, as well as of a great majority of 
 the Polidi nobles. Slie defeated the intrigues of the 
 two foreign courts by more flcilfuUy cor.duifttd intrigues 
 of her own ; and by pourirg her armies into tlie re- 
 public, (he fo completely overawed the nuncios, that 
 Poniatowficy was chofen by the unanimous fulFrages of 
 the diet which met for the ekftion of a fovereign ; and, 
 on the 7th of September 1764, was proclaimed Kmg 
 of Poland and Grand Duke of Lithuania, by the name 
 of Stanidaus Augulfus. 
 
 Whilft file was thus difpofing of foreign kingdoms, 
 fhe was kept under perpetual dread of being tumbled 
 from the throne of her own vaft empire, f ler want 
 of title to that throne was now feen by all ranks of her 
 fubjefts : the good qualities of Peter the third were 
 remembered, and his failings and faults forgotten. His 
 fate was univerfally lamented ; and, except the confpi- 
 rators, who may be faid to have embrued their hands 
 in his blood, there was hardly a Ruffian who did not 
 regret that the fovcreignty had palfed from the ancient 
 family of the Tzars to a foreigner, allied only by mar- 
 riage to the blood royal. Even the confpirators them- 
 felves had loft much of their regard for Catharine. 
 The princefs of Dafhkoff was a fecond time banifhed 
 to Mofcow ; and, to magnify her own importance, fhe 
 fpoke freely of the means by which the emprefs, whom 
 ■ fhe accufed of ingratitude, had been raifed to the throne. 
 The inhabitants of Mofcow, who never favoured the 
 ufurpation, were thus made ripe for a revolt. At St 
 Peterfburgh, Count Panin felt himfelf uneafy under the 
 predominant influence of the favourite, and tried in vain 
 to divert Catharine's aflfeftions to a new objeft. She 
 received a few fecrct vifits from a handfome young man, 
 and then appointed him to a luciatfve and honourable 
 employment in fome diftant province of the empire; 
 
 r 190 1 
 
 CAT 
 
 when Orloff recovered his former afcendency, which Cathiulnsi 
 
 through his own carelefTnefs lie had nearly loft. In v~-^ 
 
 this Hate of the public mind, confpiracies were very 
 frequent ; and as the general objeft of them was to 
 place on the throne Prince Ivan, who v/as again lan- 
 gui(hing in the dungeon from which Peter had taken 
 him, the emprefs had given to his guard an order, fign. 
 ed by her own hand, to put that unfortunate prince to 
 death, (hould any attempt be made to liberate him from 
 his prifon. An attempt was made by a very inferior 
 officer, as fome have fuppofed, by thevinftructions of 
 Catharine, and her bloody order was inftantly obeyed. 
 The aflaffins were rewarded, and promoted in the ar- 
 my; but the officer who attempted to refcue the prince 
 was condemned to death, and fuft'ered unexperledly the 
 fentencc of the law. The brothers and iilters of Ivan, 
 who had been kept in a prifon difterent from his, were 
 fent to Denmark ; and, to provide them with nccef- 
 fanes fuitable to their rank, tlie emprefs nisde them a 
 prefent of 2co,ooo rubles, and paid annually, to the 
 maintenance of their dignity, a penCon of thirty thou- 
 fand. 
 
 The throne of Catharine was now firmly eftablilhed, 
 by the death or renunciation of every perfmi who was 
 defcended of the imperial family ; and (he had leifure 
 to turn her thoughts to the aggrandifement of the em- 
 pire. It was foon feen that this was the objetl which 
 fhe had in view when (lie raifed Count Poniatowfky to 
 the throne of Poland, and that (lie was not adtuated on 
 that occafion by any remains of her former attachment. 
 We have elfewhere (hewn (fee Poland, Encycl. n" 98 
 — 115) under what pretences (he invaded the kingdom 
 of him who had formerly been one of her moft favour- 
 ed lovers, and by what means (he annexed great part 
 of it to the territories of Ruffia. But it is not through 
 her wars that in this article we mean to trace her cha- 
 ra6ter : It is not as a fovereign and heioine that her 
 life is entitled to a place in a general repolitory of aits, 
 fciences, and mifcellaneous literature, but as a patronefa 
 of art and of fcience, and as the legiflalrix of a valt em- 
 pire, who employed all her talents and all her power 
 for the civilization of a great part of the human race. 
 
 Under the article Russia (Encyc/.), we have men- 
 tioned the famous coife of laivs for a great empin; and 
 the propofed convention 0/ deputies from all the claffes, 
 which Catharine and the Princefs Da(hkofF fo artfully 
 employed as means to bring about the revolution which 
 feated the former on the throne. The Hates adually 
 met in the ancient capital of the em;'lre, and the fove- 
 rei^n's inftruftions for framing: a new code of laws was 
 read amidll reiterated burits of applaule. All prefent 
 extolled the lagacity, the wifdom, the humanity of the 
 emprefs ; but fear and flattery had a greater (hare ia 
 thefe exclamations than any jull knowledge of the lub- 
 jeft. The deputies of the Samoides alone had the 
 courage to fpcak freely. One of them ftood up, and, 
 in the name of himfelf and his brethren, faid, " We are 
 a fimple and honeft people. We quietly, tend our rein- 
 deer. We are in no want of a new code ; but make 
 laws for the Ruffians, our neighbours, that may put a 
 ftop to their depredations." The following fittings 
 did not pafs fo quietly. A debate about the liberation 
 of the boors was carried on with fuch warmth, that fa- 
 tal confequences were to be apprehended ; and the de- 
 puties were difmilTed to their refpe£tive provinces irt 
 
 the
 
 CAT 
 
 [ I9T ] 
 
 CAT 
 
 the minner which we have elfc^where related. Previ- 
 ' oils, }iowever, to the dilTolution of this afTembly, the 
 members weie required to fi^nah'ze the meeting by 
 fome confpicuous aft of o-ratitiule ; and, by a sre'ieial 
 acclamation, the titles of Great, Wise. Prudfnt, 
 and Mother of the Country, were decreed to the 
 emprefs. With affiimed modefby fhe accepted only of the 
 laft, "as the moft benign and glorious recompence for 
 her labours and folicltudes in behalf of a people whom 
 {he loved." 
 
 For that people Hie did indeed labour, and labour 
 moil ufe'iilly. She introduced into the adminiftration 
 of juftice the f^reitell reformation of which the halfci- 
 v'lized Itate of Ruffia would perhaps admit. She fpa- 
 red neither trouble nor expence to diffufe over the em- 
 pire the light of fcience, and the benefits of ufefiil and 
 elegant arts ; and (he protefted, as far as (he could, the 
 poor from the opprelTIons of the rich. About the 
 middle of 1767, (lie conceived the idea offending feve- 
 ral learned men to travel through the interior of her 
 vaft dominions, to determine the geographical pofition 
 of the principal places, to mark their temperature, and 
 to examine into the nature of their foil, thelr_ vegetable 
 and mineral produftions, and the manners of the peo- 
 ple by whom they were inhabited. To this employ- 
 ment fhe appointed Pallas, Gmelin, Euler, and many 
 others of the higheft eminence in the republic of letters ; 
 from whofe journals of thefe interefting travels large 
 additions have been made to the general ftock of ufe- 
 ful knowledge. This furvey of the empire, and the 
 maps made from it, had Catharine done nothing elfe, 
 would alone have been fufficient to render her name im- 
 mortal. Well convinced inkier own mind, that it is 
 not fo much by the pov^er of arms, as by precedence 
 in fcience, that nations obtain a conlpicuous place in 
 the annals of the world, with a laudable zeal (he en- 
 couraged artiils and fcholars of all denominations. She 
 granted new privileges to the two academies of fciences 
 and the arts ; encouraged fuch of the youth as had be- 
 haved well in thefe national inftitutes, to travel for far- 
 ther improvement over Europe, by beflowing upon them, 
 for three years, large penfions to defray their expence ; 
 and, to remove as mr.eh as poflilile the Ruffian pre- 
 judice againft all kinds of learning, (lie granted patents of 
 nobility to thofe who, during their education, had con- 
 dufted themi'elves with propriety, and become profi- 
 cients in any branch of ufeful or elegant knowledge. 
 Still farther to encourage the fiine arts in her domi- 
 nions, (he affigned an annual fum of 5000 rubles for 
 the tranflatioti of foreign literary works into the Ruffian 
 language. 
 
 In the year 1768, the fmall-pox raged at St Peterf- 
 burgh, and proved fatal to vail numbers of all ranks 
 and of every age. The emprefs was defirous to intro- 
 duce the praftice of inociilation among her fubjefts ; 
 and refolved to fet the example by having herfelf and 
 her fon inoculated. With this view, (he applied for a 
 phylician from England : and Dr Thomas Dimfdale of 
 Hertford being recommended to her, he repaired with 
 his fon to the capital of Ruffia, where he inoculated 
 firll the emprefs, then the grand duke, and afterwards 
 many of the nobility. The experiment proving fuc- 
 cefsful, he was created a baron of the empire, appoint- 
 ed aftual counfellor of ftate, and phyfician to her impe- 
 rial majefty, with a penfion of L. 300 fterling a-year, to 
 
 be paid him in England, belides L. i o,ooo which he im- Catharuie. 
 mediately received. So popular was the emprefs at ■— v~~^ 
 this period, that, by a decree of the fenate, the anni- 
 verfary of her recovery from the fimll pox was enjoin- 
 ed to be celebrated as a religious fellival ; and it has 
 ever fi.ice been obfcrved as fuch. 
 
 She was now eigaged in war with the Turks, of 
 which a fufficient account for a work of this nature has 
 been given under the title Turkky (Encycl); but 
 there was one tranfaftion of her and her friends, of 
 which no mention was made in that article, thougli it is 
 of importance to him who would form a jull eltimate 
 of her perfonal charafter. 
 
 We have noticed the fenfuality of the emprefs Eliza- 
 beth. She bore three children to the grand veneur 
 Alexey Gregorievifch Razumofffliy, to whom, indeed, 
 fne is faid to have been clandellinely married. Of thefe 
 children the youngefl was a gitl, brought up under the 
 name of Princefs Tarrakanoff. Pi ince Radzivil, who 
 has been mentioned in the article Poland ( Eiicycl.Jy 
 irritated at Catharine's cruelties to his countrymen, 
 conceived the project of placing the young princefs on 
 the throne of her ancellors ; and, having gained over 
 the perfons to whom her education was intnilled, he 
 carried her off to Rome as a place of fafely. Catha- 
 rine, in return, feized his large eftates ; and he and the 
 princefs were reduced to extreme poverty. Radzivil 
 repaired to Poland in order to learn what could be done 
 to forward his great enterprife ; and fcarcely had he ar- 
 rived there when an offer was made to rcllore to him his 
 pofferGons, upon condition of his carrying his ward to 
 St Peter(burgh. This he refufed : but hid the bafe- 
 nefs to promife, that he would give himfcLf no farther 
 concern about the daughter of Elizabeth ; and he was 
 put in poffeffion of all his ellates. 
 
 By the inftruftions of the emprefs, Alexius Ovloff, 
 who nominally commanded the Ruffian fleet at the Dar- 
 danelles, repaired to Rome, got accefs to young Tar- 
 rakanolf, and found means to perfuade her that all Ruf- 
 fia was ready to revolt from Catharine, and place her 
 on the throne of her mother. To convince her of his 
 fincerity, he orctended to feel for her the tendered and 
 moft refpeftful paffion ; and the unfufpicious lady was 
 induced to accept of him as a hufband. The ruffian 
 who had affaffinated the grandfon of Peter the Great, 
 did not hefitate to feduce and betray his grand daughter. 
 Under pretence of having the marriage ceremony per- 
 formed according to the rites of the Greek church, he 
 uiborned fome fubaltern villains to perfouate priells and 
 lawyers ; thus combining profanation with impofture 
 againft the unprotefted and too confident Tarrakanoff. 
 
 Having been treated for fome days, both at Rome 
 and at Leghorn, with all the refpedl due to a fovereign, 
 the unfufpefling princefs exprelTed a wi(h to go on 
 board a Ruffian (hip of war. This was juft what Or- 
 loff wanted. Attended by a numerous and obfequious 
 train, (he was rowed from the fhore in a boat with mag- 
 nificent enfigns, hoifted upon the deck of the (hip in 
 a fplendid chair, and immediately handcuffed. In vain 
 did (lie throw herfelf at the feet of her pretended huf- 
 band, and conjure him by every thing tender which 
 had paffed between them. She was carried down into 
 the hold ; the next day the veffel failed for St Peterf- 
 burgh ; where, upon her arrival, the princefs was (hut 
 up in the fortrefs ; and what became of her fince was 
 
 never
 
 CAT 
 
 [ 192 1 
 
 CAT 
 
 CiUharinf. never known. Sucli were the mens which Catharine 
 '"""''"""' fcruplcd not to employ in oider to gtt rid of all pre- 
 tenders to her throne. 
 
 Soon after this fervice rendered to her by Alexius 
 Orloff, (he difinifed hi:i brother Gregory from her fa- 
 vour, and ronnefled herfelf with Viffiltohikoff, a fub- 
 lientenant of the guards. The foimor favourite li^d 
 indeed become infolent, and, as Catharine th JUffht, 
 ungrateful. He afpircd to nothing lefs than the throne. 
 Ffom love to hlmfelf, and to a fon which (he had born 
 to him, (he offtred to enter into a fecret marriage ; but 
 with this propofal the proud prince (a) was nat fatis- 
 ficd, and hoped that his refufal would impel her to re- 
 ceive him publicly as her hufband and partner in power. 
 He was miftaken. She diveftcd him of alt his employ- 
 ments ; but gave him a penfion of t <ro,ooo rubles, a 
 hnndfomc fervice of plate, and an eftate with 6000 pea- 
 fanfs upon it ; and, thus enriched, he fet out upon a 
 iourrey through various parts of Europe. He return- 
 ed, however, much fooner than was expefted ; the new , 
 favourite was handfomely rewarded, and fent to a dif- 
 tance ; Orloff vas reftored to all his offices, and his 
 baleful influence wae again felt. 
 
 He attempted to perfuade the emprefs to difmifs 
 Panin from the court ; but the grand duke interpnfed 
 in behalf of his old preceptor ; and, for once, Catharine 
 liftened to the entreaties of her fon. When a dreadful 
 rebellion, under a Kofak of the name of Puget(hofF, 
 ■who pretended to be Peter III. efcaped from his af- 
 faffins, was fhaking the throne to its foundation — the 
 influence of Orloff was fuch as to prevent the cmprefa, 
 for fonie time, from employing her ableft general againft 
 the rebels, becaufe that general was Panin, brother to 
 the minider. Danger, however, at lad prevailed over 
 the favourite : Panin was fent againft Pugetfhoff; the 
 rebellion was cru(hed ; and Catharine found leifure to 
 give fomething like a legal conftitution to the empire. In 
 that work, the laws and regulations eftablilhed for the go- 
 vernment of the various provinces, and for the equitable 
 adminiftration of jnftice through the whole of hervaftdo- 
 minions, evinces the greateft wifdom and fagacity in their 
 author, as well as a proper regard to the prafticable li- 
 berties and rights of men. In the capital, (he eftablifh- 
 cd the mod perfeft police, by which the internal tran 
 qulllity of a great city was, perhaps, ever maintained ; 
 and whilft her private conduft was far from correft, (he 
 was afting in the capacity of fovereign, fo as to de- 
 ferve, indeed, the appellation of Molha- of her people. 
 
 To follow her through all her wars and intrigues 
 with foreign courts, would fwcU this article to the fize 
 of a volume. Such a narrative, too. belongs rather to 
 ' the hiftory of Ruffia than to the memoirs of Catharine; 
 in v/hich it is the buCnefs of the biographer to deve- 
 lop the private charafter of the woman, rather than to 
 detail the exploits of the fovereign. Her partition of 
 Poland, and afterwards the annihilation of it as an in- 
 dependent republic ; her encroachments on the territo- 
 ries of the grand fignior ; her formation of the armed 
 neutrahty ; the influence which (he maintained over the 
 courts of Sweden and Denmark ; and the art with 
 which (he threw the weight of Ruffia fometimes into 
 
 the fcali of .\j!lria, and fometimes Into that of PrufTia, dthirine. 
 juft as the intcrefts of her own dominions required the ^~~~> 
 one or the other to preponilerate — (hew how admirably 
 fhe was qualified to guide the helm of a greit empiic 
 ill all its traulatlions with foreign (l-ites. We fpeak 
 not o^'the fjuitv of her proceeding.;; for it mull be 
 confclTed, that equitv formed no barrier agiiuH hei am- 
 bition ; and that (he never failed to fubjugate thofc 
 w'lom (lie pictended to take under her proteftion. Her 
 ruling paffion was to enlarge her own territories, al- 
 ready fj very extenfive ; and, for the attainment of that 
 oUjcil, (be contrived the mod judicious plan', which 
 (he executed with vigour. In this pirt of her conduft, 
 hi>w'vdr, fhe has been equalled by other monarchs ; but 
 in the 7.'*al and the wiliom with which flie endeavoured 
 to introJuce among her hali-favage fubjeifts the blef- 
 fings of knowledge and indudry, (he ftands unrivalled, 
 except, perhaps, by her predecefl'or Peter the Great. 
 Of this we need bring no other proof, in addition to 
 what has beea already dated, than that (he founded in 
 St Peterfburgh alone thirty-one ieminaries, where 6800 
 children of both fexes were educated at the annual ex- 
 pence to the government of 7 51,3 ^ J rubles. She fu- 
 perintended herfclf the education of her grandchildren, 
 and wrote for them books of inftruAion. If it be true, 
 that " every man acquainted with the common principles 
 of human aftion, will look with veneration on the wri- 
 ter who is at one time combating Locke, and at another 
 making a catechifm for children in their fourth year ;" 
 with what veneration (hould we look upon the emprefs 
 of Ruffia, could we forget the means by which (he ob- 
 tained that elevation from which Hie frequently defcend- 
 ed for a fimilar employment : This (he did, not for her 
 own delcendants alone, but alfo for the children of 
 others ; of whom (he had always a great number in her 
 apartments, who fhared in the inftruiSion given to her 
 grandchildren, and wliofe caitfles (he returned with ex- 
 treme complaifance. 
 
 Her greated weaknefs was furely that grofs paffion 
 which her panegyrids have dignified with the name of 
 love ; but to fuch an appellation it had no claim, if 
 love be any thing more than a fexual appetite. Befides 
 Gregory Orloff, (he had not fewer than ten favourites 
 atter the death of her hufband ; and of thefe (he feems 
 to have felt a refined affection for none but Lanfltoi, a 
 young Pole of a very ancient family, and of elegant 
 manners, and the famous Potemkin, to whom (he is 
 faid fecretly to have given her hand, and who prcfer- 
 ved her friendfhip, if not her affeftion, to the end of 
 his life. To Lanfkoi, whofe education had been much 
 neglefled fhe condefcended to become precepttix ; and, 
 as he made great piogrefs in the acquifition of ufeful 
 knowledge, (he admired in him her own creation Po- 
 temkin, though not amiable, deferved her favour for 
 the fidelity and abilities with which he ferved her, both 
 in the council and in the field ; and in him, when (lie .. 
 had ceafed to look on him with the eyes of love, (he 
 refpefted the intriguing politician and intrepid com- 
 mander, who had formed plans tor driving the Turka 
 out of Europe, and fetting her on the throne of By- 
 zantium. Her other favouritea had nothing to recom- 
 mend 
 
 (a) She had fome time before obtained for him a patent, creating liim a prince of the Roman empire.
 
 CAT 
 
 [ 
 
 "'"e mend them but mafculine beauty and corporeal ftrength. 
 ~~ One of them, however, thought it nectflary to have a 
 library in ihe grand hoiife, of which the cnnprefs, upon 
 receiving him into favour, had made him a prefent ; and 
 dcfired thr principal bookfcller to fill his {helves. The 
 man allied him what books he would pleafe to have. 
 " You under ftand that better than I (replied the fa- 
 vourite) ; that is your bufinefs. You know the pro- 
 per aflbrtments ; I have dellined a large room to receive 
 them. Let there be large books at the bottom, and 
 fmaller and fmaller up to the top ; that is the way they 
 Hand in the emprefs's library!" In the converlation 
 of fuch men the cultivated mind of Catharine could en- 
 joy no interchange of fentiments. 
 
 We know not whether that more than Afiatic mag- 
 nificence, which (he difplayed on every public occafion, 
 {hould be confidered as an inftance of weaknefs or of 
 wifdom. If fhe delighted in balls, and malquerades, 
 and fumptuous entertainments, and drefs loaded with 
 jewels, and every kind of fplendid ornament, for their 
 own fakes, Ihe betrayed a weaknefs unworthy of that 
 fovereign who held in her hand the balance of Europe, 
 and at whofe nod the greateft powers of Afia trembled : 
 but if (he introduced fuch fplendorinto her court mere- 
 ly to divert the attention of the Ruffians from the means 
 by which Ihe got pofleffion of the throne, and to ween 
 them from their own favage and flovenly manners ; even 
 this may perhaps be conlidtred as one of her moft maf- 
 terly ftrokes in politics. 
 
 Her ambition was boundlefs ; but, if fuch a phrafe 
 may be allowed, it was not always true ambition. When 
 the French republic had eftabliihed itfelf on the ruins of 
 monarchy, and was propagating new theories of govern- 
 ment through all Europe, true ambition would furely 
 have led the autocratrix of the north to unite her forces 
 with thofe of the coalefced powers, in order to crufh 
 the horrid hydra, before its anarchical principles could 
 be introduced among her own barbarous fubjei^s. .Such 
 would certainly have been the advice of her favourite 
 Potcmkin, who longed to lead a Ruffian army into 
 France, even before the murder of the unfortunate 
 Lewis. That general, however, had died in OAober 
 1791 ; and when Britain, Auftria, and Pruffia, were 
 leagued againft the new republic, Catharine looked 
 coolly on, in hopes, it is probable, of availing herfelf of 
 their weaknefs, when exhaufted by a long and bloody 
 war. She gave refuge, indeed, in her dominions to many 
 emigrants from France, and fent a fqir.idron of fhips to 
 co-operate with the navy of England : but in this laft 
 ineafure fhe regarded merely her own immediate inte- 
 reft ; for her crazy fhips were repaired by Britifh car- 
 penters at the expence of the Britifh government, and 
 her officers had an opportunity of learning the evolu- 
 tions of the Britifh navy. She had likewife other prof- 
 pefts in view when (he lent to the allies this flender aid. 
 She meditated a new war with Turkey ; and, depend- 
 ing upon meeting with no oppoStion, if fhe fhould not 
 receive affiftance from England and Auftria, (he Hattcr- 
 «d herfelf with accomplifliing her dailing projeft of 
 driving the Ottomans out ot Europe, and of reigning 
 in Conftantinople. But fhe was difappointed. On the 
 morning of the 9th of November 1796, fhe was feized 
 with what her principal phyfician judged a fit of apo- 
 plexy ; and, at 10 o'clock in the evening of the follow- 
 ing day, expired, in the 68th year of her age, leaving 
 Suppi. Vol. I. Part I, 
 
 93 ] C A U 
 
 behind her the charafter of one of the gre«teft I'ove- 
 reign» that ever fwayed a fceptre. 
 
 After this long detail of the incidents of her life, it 
 ie necdlefs to inform the reader that Catharine II. had 
 no religion, and, of courfc, no principles of morality, 
 which could induce her in every inftance to do to others 
 as (he would have them do to her. She was a prufeded 
 difciple of the brench philofophers ; by fome of whom 
 flic was ridiculed, and by others cheated. The iacenfe 
 which (he paid to the genius of Voltaire did not hinder 
 him trom frequently breaking his jefts upon the auto- 
 cratrix of RufTia and her fuccelTive favourites ; and Di- 
 derot, whom fhe careffed, fold to her an immcufe li- 
 brary, when he pofTeffed hardly a book, and was obli- 
 ged to ranfack Germany and France for volumes to 
 enable him to fulfil his bargain. Such is the friendfhip, 
 and fuch the gratitude, which fubfilU among the ami- 
 able pupils of nature, and the philanthropic advocates 
 for the rights of man. 
 
 CAUDA Capricorni, a fixed ftarof the fourth mag. 
 nitude, in the tail of Capricorn ; called alfo, by the 
 Arabs, Dineb Algedi i and y by Bayer. 
 
 Cauda Cett, a fixed (lar of the third magnitude ; 
 called alfo, by the Arabs, Dined Kaetos ; marked fi by 
 Bayer. 
 
 Cauda Cygni, a fixed (lar of the fecond magnitude, 
 in the Swan's tail ; called by the Arabs Dineb .iJigege', 
 or ElJegiagich ; and marked a by Bayer. 
 
 Cauda Delphini, a fixed liar of the third magnitude, 
 in the tail of the Dolphin. ; marked ; by Bayer. 
 
 Cauda Draconis, or Dragon's tail, the moon's fouth- 
 ern or defcending node. 
 
 Cauda Leonis, a fixed ftar of the firft magnitude, in 
 the Lion's tail ; called aifo, by the Arabs, Dine'> E!e- 
 ced ; and marked ^ by Bayer. It is called alfo Lucida 
 Cauda. 
 
 Cauda Urfie Majoris, a fixed ftar of the third mag. 
 nitude, in the tip of the Great Bear's tail ; called alfo, 
 by the Arabs, Alalioth, and Bensnath ; and marked „ by 
 Bayer. 
 
 Cauda Urfe Minoris, a fixed ftar of the third ma<r. 
 nitude, at the end of the Leffer Bear's tail ; called alio 
 the Pole Star, and, by the Arabs, Alrukahah ; and 
 marked a by Bayer. 
 
 CAUSE has been defined, we thijik, with accuracy 
 in the Encyclopaedia, and the doftrine ftated which we 
 believe to be true. Objertions however have been made 
 to that doflrine, of which we have endeavoured to re- 
 move fome, under the title Action, in this Supple- 
 ment ; and the doiTtnne itfelf has been well illuftrated 
 (at lead fuch is our opinion) in the fuppleiiu-nta;y ar- 
 ticle AsTRONOMT. We have, theiefoie, very Hi tie to 
 add here on the fuhjeft of caufes, though it is the moft 
 important fubjeft which can employ the mind of man. 
 What is the relation between a phylical caiife and shat 
 which is termed its cffe6t — betivi.cn l.iMt, fo' inilance, 
 and the fufion of metals ? Is it a nee ffliry cortneSio/i, or 
 only a conjunLlion, difcovered by experience to be con- 
 Jiant ? 
 
 If by necejfary conneftion be meant that kind of con- 
 neftion of which the contrary cannot be conceived, we 
 do not think that the connexion of any phyfical caufe 
 with its effetl can be called neceffary. We fee no dif. 
 ficnlty in conceiving, that fire, inftead o; fufiiig gold, 
 might fix mercury. This may indeed be impoffible ; 
 Bb and 
 
 Caurtj, 
 Caiife.
 
 C E N 
 
 [ 194 ] 
 
 C E N 
 
 Caufe, and we might perhaps fee the impoffibillty, did we as 
 Cenicr. complttely know the nature of fire and of metnls, as we 
 '~~^ kno\v the relations of pure geometry. We know that 
 the tliiee arglcs of a plain triangle cannot poffibly be 
 eitlier greater or lefs tlian two right angles ; for in this 
 comparifon nothing is hid from our mental view. We 
 do not, however, perceive the impofTibility of mercury 
 ■being fixed, as chiy is hardened, by heat : for of heat, 
 and mercury, and clay, we know very little, and that 
 little is the offspring of experience. 
 
 I'.ut if the connexion betwccrf caufc and effefl be not 
 nece/fary,zxi we not deprived of the means ofdemonftra- 
 ting the great fundamental truth of nligion ? We have 
 nowhere faid, that the connection between caufe and 
 effea is not neceffary ; but only, that we do not per- 
 ceive the neceffary connexion between what are called 
 fhyfu-al cmks and their effeds. That every event is, 
 and muft be, brought about hy forne caufe or fome ag:n- 
 tjF, we hold to be a felf evident truth, which no man 
 can deny who underftar.ds the terms in which it is ex- 
 prefTed ; but what or where the agency is, we can very 
 fcldom, if ever, know, except when we think of our own 
 voluntary aftions. When a change is obferved, we can- 
 not doubt of its being produced by fomething : either 
 the thing changed is animated, and has produced the 
 change by its own agency, juft as we move our heads 
 and leo-3 by an aft of volition ; or if it be inanimated, 
 and of itfelf incapable of agency, the change has been 
 produced by fomething external, denominated a caufe. 
 But all external caufes, which are not likewife agents, in 
 the proper fenfe of the word, may be traced, we think, 
 as effeds up to fome agency ; and therefore, in our 
 opinion, there is no real, ultimate, efficient caufe but 
 mind, or tliat which is endued with power. In proof 
 of this doftrine, if it need any proof, we can only refer 
 to what has been faid elfewhere on our notions oi poiver 
 and oi phfical caiifs. See {Encycl.) Metaphysics, 
 n° 109, &c. — Philosophy and Fhy sics, J>q//im — and 
 [SuppL) Action and Astronomy. 
 
 CENTER, or Centre, a word borrowed from the 
 French name ceitUre or cintre, given to the frame of tim- 
 ber, by which the brick or ftone of arched vaulting is 
 fuppotted during its ereftion, and from which it re- 
 ceives its form and curvati:re. 
 
 It is not our intention to defcribe the variety of con- 
 ftruftions which may be adopted in eafy fituations, 
 where the a:ches are of fmall extent, and where fuffi- 
 cient foundation can be had in every part of it for fuu- 
 pnrting the frame. In fuch cafes, the frequency of the 
 props wliich we can fet up difpenfes with much care ; 
 and a frame of very (light timbers, connefted together 
 in an ordinary way, will fuKce for carrying the weight, 
 and for keeping it in exaft fliape. But when the arches 
 liave a wide fpan, and confequently a very great weight, 
 and when we cannot fet up intermediate pillars, either 
 for want of a foundation in the foft bottom of a river, 
 or becaufe the arch is turned between two lofty piers, 
 as in the dome of a (lately cathedral — we are then obli- 
 o-ed to reft every thing on the piers themfelves ; and the 
 framing which is to fupport our arch before the key- 
 ftone is fet, muft itfelf be an arch, depending on the 
 mutual abutment of its beams. One fhould think that 
 this view of the conftruftion of a centre would offer it- 
 felf at the firft, naturally derived from the ereftion it 
 was to affift : but it has not been fo. When intermedi- 
 
 Cc&Ditioc. 
 
 2 
 Purpofe of 
 this aitide 
 
 ate pillarj were not employed, it was ufual to frame the Centtr. 
 
 mould for the arch with little attention to any thing but •' "' 
 
 its fliape, and then to crofs it and recrofs it in all direc- 
 tions with other pieces of timber, till it was thought fo 
 bound together that it could be lifted in any pof:tion, 
 and, when loaded with any weight, could not change 
 its .fliape. The frame was then raifed in a lump, like 
 any lolld body of the fame fliape, and let in its place. 
 This is the way ftill pradliftd by many country artills, 
 who, having no clear principles to guide them, do not 
 flop till they have made a load of timber almoft equal 
 to the weight which it is to carry. 
 
 But this artlefs method, betides leading the employer 
 into great expence, is frequently fatal to the undeitake"-, 
 frpm the unflcilfulnefs of the conflruftion. The beams 
 which conneft its extremities are made alfo to fuppott 
 the middle by means of polls which reft on them. They 
 are therefore expoled to a tranfverfe or crofs (Irain, 
 which they are not able to bear. Their number muft. 
 therefore be incieafed, and this increafes the load. Some 
 of thele crofo ftrains are derived from beams which are 
 prefl'ed vety obliquely, and therefore exert a prodigious 
 thruft on their fuppoits. The beams are alio greatly ■ 
 weakened by the niortifes whidi are cut in them to re- 
 ceive the tenons of the croffing beams : and thus the 
 whole is exceedingly weak, in proportion to what the 
 fame quantity of timber may be made by a proper dif- 
 pofitlon.of its parts. 
 
 The principles from which we are to derive this dif- General 
 polition are the general mechanical principles of carpen- 1 rincijlts 
 try, of which we have given fome account in that ar-"'*^™'"''^ 
 tide. Thefe furnilh one general rule : When we would ' ' 
 
 give the utmoft ftrength poffible to a frame of carpen- 
 try, every piece (hould be fo difpofcd that it is fubjedt 
 to no ftrain but what cither puflies or draws it in the 
 direfiion of its length : and, if we would be indebted 
 to timber alone for the force or ftrength of the centre, 
 we muft reft all on the lirft of thefe ftrains ; for when 
 the draining force tends to draw a beam out of ita 
 place, it mull be held there by a mortife and tenon, 
 which pofleiTcs but a very trifling force, or by iron 
 ftraps and bolts. Cafes occur where it may be very 
 difBcult to make every ftrain a thruft, and the beft art- 
 ifts admit of ties ; and indeed where we can admit a 
 tie-beam connefting the two feet of our frame, we need 
 feek no better fecurity. But this may fometimes be 
 very inconvenient. When it is the arch of a bridge that 
 we are to fupp(r.t, fuch a tie-beam would totally ftop 
 the paffage of fmall craft up and down the river. It 
 would often be in the water, and thus expofed to the 
 moft fatal accidents by frefhes, &c. Interrupted ties, 
 therefore, muft be employed, whofe joint or meetings 
 muft be fupported by fomething analogous to the king- 
 pofts of roofs. When this is judicioufly done, the fe- 
 curity is abundantly good. But great judgment io ne- 
 ceffary, and a very fcrupulous attention to the difpofi- 
 tion of the pieces. It is by no means an eafy matter 
 to difcern whether a beam, which makes a part of our 
 centre, is in a ftate of comprefiion or in a ftate of ex- 
 tenlion. In fome works of the moft eminent carpen- 
 ters even of this day, we lee pieces confidered as ftruts 
 (and contiderablc dependence had on them in this ca- 
 pacity), while they are certainly performing the office 
 of tie-beams, and fhoidd be fecured acceordingly. This 
 was the cafe in the boldeft centre (we think) that has 
 
 beea 

 
 iiefs and 
 iireugtli. 
 
 C E N [19 
 
 Center been executed in Europe, that of tlie bridge of Oileans, 
 ^""—t by Mr Hupeau. Yet it is evidently of great confe- 
 qucnce not to be miftaken in this point ; for when we 
 are miftaken, and the piece is ftretched which we ima- 
 gine to be compretTed, we not only are deprived ot fome 
 fupport that wc expcfted, but the cxpefted fuppott Tias 
 become an additional load. 
 * ,., To afcertain this point, we may fiippofe the piers 
 tincuiih a '° yield a little to the prelTure of the aichftoncj on the 
 ftrijt from 3 centre frames. The feet, therefore, fly outwards, and 
 tie. the (hape is altered by the finking of the crown. We 
 
 mult draw our frame anew for this new ilate of things, 
 and n'.uft notice what pieces mud be made longer than 
 before. All fuch pieces have been afting the part of 
 tie-beams. 
 
 But a centre has ftill another office to fuftain ; it 
 muft keep the arch in its form ; that is, while the load 
 on the centre is continually increaling, as the n.alons 
 lay on more courfes of arch (tones, the fiame mud not 
 yield and go out of Ihape, finking under the weight on 
 the haunches, and rifing in the crown, which is not yet 
 carrying any load. The frame muft not be fuDple ; and 
 mud derive its ftiffnefs, not from the clofenefs and 
 ftrength of its joints, which are quite infignificant when 
 * fet is competition with fuch immenfe ftrains, but from 
 {Iruts or ties, properly diipofed, which hinder any of 
 the angles from changing its amplitude. 
 
 It is obvious, from all that has been faid, that the 
 How to fc- ftrength and ftiffnefs of the whole muft be found in the 
 cureftifF- triangles into whicli this frame of carpentry may be re- 
 folved. We have feen that the ftrains which one piece 
 produces on two others, with which it meets in one 
 
 ^ point, depends on the angles of their interleftion ; and 
 
 that it is greater as an obtfJe angle h mote obtufe, or 
 an acute angle more acute. And this fiiggefts to us 
 the general maxim, " to avoid as much as pofiible all 
 very obtufe angles.'' Acute angles, which are not ne- 
 ceftarily accompanied by obtufe ones, are not fo liurtful; 
 becaufe the drain here can never exceed the ftraiuing 
 force ; whereas, in the cafe of an oblufe angle, it may 
 fuipafs it in any degree. 
 
 Such are the general rules on this fubjeft. Although 
 fomething of the mutual abutment of timbers, and the 
 fupport derived from it, has been long perceived, and 
 employed by the carpenters in roofing, and alfo (doubt- 
 lefs) in the forming of centres, yet it is a matter of hi- 
 ftorical faft, that no general and diftinft views had been 
 taken of it till about the beginning of this century, or a 
 little earlier. Fontana has preferved the figure of the 
 frames on which the arches of St Peter's at Rome were., 
 turned. The one employed for the dome is conftruft- 
 ed with viry little fitill ; and thofe for the arches of the 
 nave "Slid tranfepts, though incomparably fuperior, and 
 of confiderable fimplicity and drcngth, are yet far infe- 
 rior to others which have been employed in later times. 
 It is much to be regretted that no trace remains of the 
 forms employed by the great architeft and confummate 
 mechanician Sir Chridopher Wren. ,We Ihould doubt- 
 lefshave feen in them every thing that fcience and great 
 fagacity could fugged. We are told, indeed, that his 
 centering for the dome of St Paul's was a wonder of its 
 kind ; begun in the air at the height of 160 feet from 
 • the ground, and without making ufe of even a projeft- 
 ing coiniche whereon 10 reft it. 
 
 The earlicft theory of the kind that we have met 
 
 ] 
 
 C E N 
 
 with, that is propofed on fcicntific principles, and with Cci-.tjr. 
 the exprcfe purpufe of ferving as a Icflbn, are two cen- ~~~^~~~' 
 tres by Mr I'itot of the Academy of Sciences, about the The eai lied 
 beginning of this century. As they have confidcrable tl cory, on 
 merit (greatly refcmbling thofe employed by Michael f'''-'''''^' 
 Angelo in the nave of St Peter's), and aft'ord fome good l"'""^'l''"' 
 maxims, we diall give a (hort account of them. We 
 crave the excufe of the attifts if we fhould employ their 
 terms of art fomewhat aukwardly, not being very fami- 
 harly acquainted with them. Indeed, we oblerve very 
 great differences, and even ambiguity, in the terms em- 
 ployed. 
 
 What we fliall defcribe under the name of a cen/re Is 
 (properly fpeaking) only one frame, trufs, or rib, of a 
 centre. They are fet up in vertical planes, parallel to 
 each other, at the didance of ;, 6, 7, or 8 feet, like 
 the truflfes or main couples of a roof. Biidging joifts 
 are laid acrofs them. — In fmaller works thefe are laid 
 fparingly, but of confidcrable fcantling, and are board- 
 ed over ; but for great arches, a bridging joift ia laid for 
 every courfe of archltones, with blockings between to 
 keep them at their proper diilances. The dones are 
 not laid immediately on thefe joifts, but beams of foft 
 wood are laid along each joift, on which the done is 
 laid. Thefe beams are afterwards cut out with the 
 chiffel, in order to fepatate the centre from the ring of 
 Hones, which muft now fupport each other by their mu- 
 tual abutment. 7 
 
 The centre is diftinguiftiable into two parts, ALLB lUudrated. 
 (fig. I.) ar.d LDL, which are pretty independent ofphteXIV. 
 each other, or at lead a6t feparately. The horizontal 
 Stretcher LL cuts the femicircle ADI3 halt way be- 
 tween the fpring and the crown of the arch ; the arches 
 AL, LD, being 45" each. This fttetcher is divided in 
 the fame proportion in the points G and H ; that is, 
 GH is one half of LL, and LG, HL are each one- 
 fourth of LL nearly. Each end Is fupported by twvo 
 Struts EI, GI, which red below on a Sole or Bed 
 properly fupported. The interval between the heads of 
 the ftruts GI, HK is filled up by the Straining Beam 
 GH, abutting in a proper manner on the ftruts (fee 
 Carpentry, Supplement), The extremities L, L, are 
 united in like manner by butting joints, with the heads 
 of the outer ftruts. The Arch Moulds AP, BP, are 
 connected wldi the ftruts by crofs pieces PQ. which we 
 (hall call Bridles, which come inwards on each fide of 
 the druts (being double), and are bolted to them. This 
 may be called the lower part of the frame. The upper 
 part confids of the king poft DR, fupported on each 
 fide by the two ftruts or braces ML, ON, ir.ortifed into 
 the poft, and alfo mortifed into the ftretcher, at the 
 points L, N, where it is fupported by the (truts below. 
 The arches LD, LD are conneded with the druts by 
 the bridles PQ, in the fame manner as below. g 
 
 There is a great propriety in many parts of this ar- Proi riety 
 rangement. The lower parts or haunches of the arch "^ ''''» '•"• 
 prefs very lightly on the centres. Each archdone is ly. r^ngstu'it- 
 ing on an inclined plane, and tends to Aide down only 
 with its relative weight ; that is, its weight is to its 
 tendency to Aide down the joint as radius to the fine of 
 elevation of the joint. Now it is only by this tendency 
 to Aide down the joint that they prefs on the centering, 
 which in every part of the arch is perpendicular to the 
 joint : But the preCTure on the joint, arifing from this 
 caufe, 13 much lefs than this, by reafon of the friftion of 
 B b 2 the
 
 C E N 
 
 [ 196 ] 
 
 C E N 
 
 Centir. the joints. A block of dry fict-ilone will not Aide down 
 ' ' » at all ; and therefore will not prels on t!ie centering, if 
 
 the joint be not elevated ;?5 degrees at leaft. But the 
 aiclilfones are not laid in this manner, by Aiding them 
 down along the joint, but are laid on the centres, and 
 Aide down their flope, till they touch the blocks on 
 which they are to reft ; fo that, in laying the arch- 
 ftones, we are by no means allowed to make the great 
 deduction fiom their weight juft now mentioned, and 
 which Mr Couplet prefcribcs (Mem. Acad. Sciences, 
 1729). But there is another caufe which diminiflies 
 the preffure on the centres ; each block Aides down the 
 ■ planks on which it is laid, and prcfies on the block be- 
 low it, in the direftion of the tangt-nt to the arch. This 
 prefTure is tranfmi'.ted throui^h this block, in the fame 
 diredlion, to the next, and through it to the third, &c. 
 In thij manner it is plain that, as the arch advances, 
 there is a tangential preffure on the lower archflones, 
 which diminilTies their prefTure on the frame, and, if 
 fufficiently great, might even pufh them away from it. 
 Mr Couplet has given an analyfis of this preffure, and 
 (hews, that in a fcmicircular arch of uniform thickntfs 
 none of the arch flones below 30° prefs on the frames. 
 But he (without faying fo) calculates on the fuppofi- 
 tion that the blocks defcend along the circumference of 
 this frame in the fame manner as if it were perfeftly 
 fmooth. As this is far from being the cafe, and as the 
 obftruftions are to the laft degree various and irregular, 
 it is quite ufelefs to inftitute any calculation on the fub- 
 jeft. A little refleftion will convince the reader, that 
 in this cafe the obftruftion arifing from friftion mufl be 
 taken into account, and that it mujl not be taken into 
 account in cftimating the prefTure of each fucceflive 
 courfe of ftones as they arc laid. It is enough that we 
 fee that the prefTure of the lower courfes of archftones 
 on the frame is diminiflied. Mr Couplet fays, that the 
 whole prefTure of.a femicircular arch is but ^ths of its 
 weight ; but it is much greater, for the reafon jufl now 
 By a centre given. We have tried, with a well made wooden mo- 
 ot M. Pi- del (of which the circumference was rubbed with black 
 lead to render it more flippery), whether onj' part of the 
 wooden blocks reprefenting the archftones were detach- 
 ed from the frame by the tangential prelTure of the fu- 
 perior blocks ; but we could not fay confidently that 
 any were fo detached. We perceived that all kept hold 
 of a thin flip of Chinefe paper (alfo rubbed with black 
 lead) between them and the frame, fo that a fenfible 
 force was required to pull it out. From a combination 
 of circumi\anres, which would be tedious to relate, we 
 believe that the centres carry more than two- thirds of 
 the weight of the arch before the keyftone is fet. In 
 elliptical and lower pitched circular arches, the propor- 
 tion is (till greater. 
 
 It feems reafonable eoough, therefore, to difpofe the 
 framing in the manner propofed by Pitot, directing the 
 main fupport to the upper mafs of the arch, which 
 prefTes mofl on the frame. We fhall derive another ad- 
 ■vantage from this conitruftion, which has not occurred 
 to Mr Pitot. 
 
 There is an evident propriety in the manner in which 
 he has diflributed the fupports of the upper part. The 
 flruts which carry the king poll fpring from thofe points 
 of the flretcher where it refls on the flruts below : thus 
 the flretcher, on which all depends, bears no tranfverfe 
 drains. It is ilretched by the &rut above it, and.it ig 
 
 tot's. 
 
 comprcfTtd in a fmall degree betvi'een the ftriits below Cfnttr. 
 it, at leaf! by the outer ones. Mr Pitot propofes the """v— ~ 
 (training beam GH as a lateral fupport to the flretcher, 
 which may therefore be of two pieces : but although it 
 (lots augmmt its ftrenglh, it does not feem necefl'arj' for it. 
 The flretcher is abiuidanlly carried by the ftrap, which 
 may and fhould fiifpend it from the king poll. The 
 great ufe of the flraining piece is to give a firm abut- 
 ment to the inner llruts, without allowing any lateral 
 flrain on the flretcher. N. B. Great care muft be ta- 
 ken to make the hold fufficiently firm and extenfive be- 
 tween the flretcher and the upper flruts, fo that its co- 
 hetion to relift the thrulls from thcfc flruts may be much 
 employed. 
 
 The only imperfefiion that we find in this frame is 
 the lateral flrains which are brought upon the upper 
 ftruts by the bridles, which certainly tranfmit to them 
 part of the weight of the archftones on the curves. 
 The fpace between the curves and ML fhould alfo have 
 been trufTed. Mr Pitot's form is, however, extremely 
 ftifT ; and the caufing the middle bridle to reach down 
 to the ftretcher, feems to fecure the upper ftiuts from 
 all rifle of bending. 
 
 This centre gives a very diftinft view of the ofSces 
 of all the parts, and makes therefore a proper introduc- 
 tion to the general fubjeiSl. It is the fimplell that can 
 be in its principle, becaufe all the elTential parts are fub- 
 jefted to one kind of (train. The flretcher LL is the 
 only exception, and its extenfion is rather a collateral 
 circumftance than a ftep in the general fupport. 10 
 
 The examination of the ftrength of the frame is ex-T"he 
 tremely eafy. Mr Pitot gives it for an arch of 60 feet ^^^"g''' ^^ 
 fpan, and fuppofes the archftones 7 feet long, which is 
 a monftrous thicknefs for fo fmall an arch ; 4 feet is an 
 abundant allowance, but we (hall abide by his conftruc- 
 tion. He gives the following fcantlings of the parts : 
 
 The ring or circumference conCfts of pieces of oak 
 12 inches broad and 6 thick. 
 
 The ftretcher LL is 12 inches fquare. 
 The ftraining piece GH is alfo 12 by 12. 
 The lower ftruts 10 by 8. . 
 The king poft 12 by 12. 
 The .upper ftruts 10 by 6. 
 The bridles 20 by 8. 
 
 Thefe dimenfions are French, which is about ~i\t\t 
 larger than ours, and the fuperficial dimenfions (by 
 which the fedlion and the abfolute ftrength is meafured) 
 is almoft 4^th larger than ours. The cubic foot, by 
 which the ftones are meafured, exceeds ours nearly j-th. 
 The pound is deficient about rVth. But Cnce very 
 nice calculation is neither eafy nor necefTary on this fub- 
 jedl, it is needlefs to depart from the French meafures, 
 which would occafion many fraftional parts and a trour 
 blefome reduflion. 
 
 The arch is fuppofed to be built of flone which, 
 weighed 160 pounds per foot. Mr Pitot, by a compu* 
 tation (In vhich he has committed a miftake), fays, 
 that only T^ths of this weight is carried by the frame. 
 We believe, however, that this is nearer the truth than 
 Mr Couplet's afTumption of ^^ths already mentioned. 
 
 Mr Pitot farther alTumes, that a fquare inch of found 
 oak will carry 8640 pounds. By his language we 
 (hould imagine that it will not carry much more ; but 
 this is very far below the ftrength of any Britifh oak 
 that we have tried ; fo far, indeed, that we rather ima- 
 gine
 
 C E N 
 
 [ 
 
 Computed. 
 
 Cf r.ter. gine that he means that this load may be laid on it with 
 ■"'>"■"' ptrfeA fecurity for any time. B'.it to compenfate for 
 krota and other accidental imperfcftlons, he atTumcfi 
 7200 as tlie meafure of its abfohite force. 
 
 He computes the load on eacti frame to be 707520 
 pounds, which he reduces to -J-jths, or 55590S pounds. 
 The abfolute force of each of the lower ftruts is 
 576000 (at 7200 per inch), and that of the curves 
 5 1 8400. Mr Pitot, confiderinjr that the curves are 
 kept from bending outwards by the arch-ftones which 
 prefs on them, thinks that they may be conlidered as 
 aSing precifely as the outer ftruts EI. We have no 
 objettion to this fuppofition. 
 
 With thefe data we may compute the load which the 
 lower trufs can fafely bear by the rule delivered in the 
 article Carpentry. We therefore proceed as fol- 
 lows : 
 
 Meafure off by a fcale of equal parts a s, at, each 
 576000, and add /-u 518400. Complete the paralle- 
 logram avKs, and draw the vertical xc, meeting the 
 horizontal line aC in f. Make cb equal to en. Join 
 xb, and complete the parallelogram ax by. It is evi- 
 dent that tlie diagonal xy will reprefent the load which 
 thefe pieces can carry ; for the line a-u 1% the united 
 force of the curve AP and the ftrut IE, and as Is the 
 flrer.gth of IG. Thefe two are equivalent to a x. 
 It h is, in like manner, equivalent to the fupport on the 
 other fide, and xy is the load which will jull balance 
 the two fupports a x and b x. 
 
 When xy is meafured on the fajne fcale, it will be 
 found = 28 50000 pounds. This is more than five 
 times the load which aAually lies on the frame. It is 
 therefore vaftly ftronger than is necelTary. Half of 
 each of the. linear dimenfions would have been quite fuf- 
 ficient, and the ftruts needed only to be 5 inches by 4. 
 Even this would have carried twice the weight, and 
 would have borne the load really laid on it with perfeA 
 fefety. 
 
 We proceed to meafure the ftrength of the upper 
 part. The force of each ftrut is 432000, and that of 
 the curve is 518400; therefore, having drawn M.v pa- 
 rallel to the ftrut ON, make Mw =r 432000, and Ms 
 = 432C00 -1- 518400. Complete the parallelogram 
 hii rv. Draw the horizontal line r i, cutting the ver- 
 tical MC in i, and make iy =: Mi. It is plain, from 
 what was done for the lower part, that Mji will mea- 
 fure the load which can be carried by the upper part. 
 This will be found = 1160000. This is alfo greatly 
 fuperior to the load ; but not in fo great a proportion 
 as the other part. The chief part of the load lies on 
 the upper part ; but the chief reafon of the diflerence is 
 the greater obliquity of the upper ftruts. This fhort- 
 ens the diagonal My of the parallelogram offerees. Mr 
 Pitot (hould have adverted to this ; and inftead of ma. 
 king the upper ftruts more flender than the lower, he 
 fliould have made them ftouter. 
 
 The ftrain on the ftretcher LL is not calculated, It 
 IS meafured by r' i', when My is the load actually ly- 
 ing on the upper part. Lefs than the fixth part of the 
 cohcfion of the ftretcher is more than fuflkient for the 
 
 97 ] C E N 
 
 horizontal thruft ; and there is no difficulty of making Center. 
 
 the foot joints of the ftruts abundantly ftrong for the ' \r— ' 
 
 purpofe. 
 
 The reader will perceive that the computation juft 
 now given does not ftate the proportions of the ftrains 
 aaiuilly exerted on the dlff'erent pieces, but the load on 
 the whole, on the fuppofition that each piece is lubjeft- 
 cd to a ftrain proportioned to its ftrength. The other 
 calculation is much more complicated, but is not necef- 
 fary here. 
 
 This centre has a very palpable defeiS. If the piers 
 fliould yield to the load, and the feet of the centre fly 
 out, the lower part will exert a very confiderable ftrain 
 on the ftretcher, tending to break it acrofs between N 
 and L, and on the other fide. HKFof the lower part 
 is firmly bound together, and cannot change its ftiape,. 
 and will therefore zSl like a lever, turning round the 
 point F. It will draw the ftrut HK away from its a- 
 butment with GH, and the ftretcher will be ftrained 
 acrofs at the place between H and F, where it is bolt- 
 ed with the bridle. This may be refifted in fome de- 
 gree by an iron ftrap uniting ON and HK ; but there 
 will ftill be a want of proportional ftrength. Indeed, 
 in an arch of fuch height (a femicircle), there is but 
 little rifk of this yielding of the piers ; but it is an im- 
 perfeftion. 
 
 ^ The centre (fig. 2.) is conftrufted on the fame prin-A centre- 
 clple precifely for an elliptical arch (a). The calcula-"" the fame- 
 tion of its ftrength is nearly the fame alfo; only the '"^''"^'P''^? 
 two upper ftruts of a fide being parallel, the parallelo- [?,'!ji ^j j,'''' 
 gram Msrv (of fig. 1.) is not needed, and in its ftead 
 w^ meafure off on ON a line to reprefent twice its 
 ftrength. This comes in place of Mr' of fig. i. — N. B. 
 The calculation proceeds on the fuppofition that the 
 fiiort ftraining piece MM makes but one firm body with 
 the kingpoft. Mr Pilot employed this piece (we pre- 
 fume) to feparate the heads of the ftruts, that their ob- 
 liquity might be leffened thereby : and this is a good 
 thought ; for v/hen the angle formed by the ftruts on 
 each fide is very open, th-e ftrain on them becomes very 
 great. 
 
 The ftretcher of this frame is fcarfed in the middle. 
 Suppofe this joint to yield a little, there is a danger * 
 of the lower Itrut ON lofing its hold, and ceafing to 
 join in the fupport : for when the crown finks by the- 
 lengthening of the ftretcher, the triangle ORN of tig. 2. 
 will be more diftorted than the fpace above it, and ON 
 will be loofened. But this will not be the cafe when ■ 
 the finking of the crown arifes from the mete com. 
 prefQon of the ftruts. Nor will it happen at all in 
 the centre, fig, i. On the contrary, the ftrut ON 
 will abutt more firmly by the yielding of the foot of 
 MI.,. 
 
 The figure of this arch of Mr Pilot's confifts of three 
 arches of circles, each of 60 degrees. As it is elegant,, 
 it will not be unacceptable to the artift to have a con- 
 ftruftion for this purpofe. 
 
 Make BY = CD, and CZ = -l CY. Defcribe the.Howw 
 femicircle ZjEY, and make ZS = "LM. S is the centre conftrua 
 of the fide arches, each of 60 degrees. Tlie centre T of '>"^'' ^n 
 
 the.*''*'- 
 
 (a) It is the middle arch of the bridge at Lille Adam, of which Mr Pitot had the direftion. It is of 80 
 feet fpan, and rifes 31 feet.
 
 C E N 
 
 r 19S ] 
 
 C E N 
 
 Center, tlie arcli, vhlch unites thefe two, is at the angle of an 
 ^-"■y^—^ equilateral triangle STS. 
 
 This conftruiSion of Mr Pitot's makes a liandfome 
 oval, and very near an ellipfis. but lies a little without 
 it. We fhall add another of our own, which coincides 
 with the ellipfe in eight points, and furrifhes the artift, 
 by the way, a rule for drawing an infinite variety of 
 ovals. 
 
 Let AB, DE (fig. 2. N" 2.) be the axes of an el- 
 lipfe, C the centre, and F, /"the two foci. Make C^ 
 = CD, and dtfcribe a circle ABie paffing through 
 the three given points A, D, and i. It may be de- 
 monftrated, that if from any ptiint P of the arch AD 
 be drawn a chord PD, and if a line PR r be drawn, 
 making the angle DPR = PDC, and meeting the two 
 axes in the points R and r, then R and r will be the 
 centres of circles, which will form a quarter APD of 
 an oval, which has A3 and DE for its two axes. 
 
 We want an oval which fhall coincide as much as 
 poflible with an elliplis ? The moft likely method for 
 this is to find the very point P where the ellipfis cuts 
 the circle ADl>e. The eafieft way for the artift is to 
 dtfcribe an arch of a circle a m, having AB for its ra- 
 dius, and the remote focus/for its centre. Then fet 
 one foot of the compaffes on any point P, and try whe- 
 t'.ier the diftance PF from the nearcll focus F is exaol- 
 ly equal to its diftaixe P m from that circle. .Shifting 
 the foot of the conipafTc i from one point of the arch to 
 another, will foon difcover the point. This being found, 
 draw PD, make. the angle DP r — PD r, and R and r 
 are the centres wanted. Then make C s z^ CR, and 
 we get the centres for the other fide. 
 
 The geometer will not relifh this mechanical conftrnc- 
 tion. He may therefore proceed as follows : DrawDrf 
 parallel to AB,"cutting the circle in d. Draw e 1^^ cut- 
 ting AC in N. Draw CG parallel to Ae, and make the 
 angle CG i = AD e. Bifedl CN in O, and join O ('. 
 Make OM, OM' = O i, and draw MP, MT perpen- 
 dicular to AJi. Thefe ordinates will cut the circle 
 ADie in the points P and P', where it is cut by the 
 ellipfe. We leave the demonftration as a geometrical 
 t . « €xercife for the dilettante. 
 Centre for We faid, that this centering of Mr Pitot's refembled 
 the nave >jf In principle the one employed by Michael Angelo for 
 St Peter's, ^^^g ^^^^ ^^jj tranfepts of St Peter's church at Rome. 
 Fontana, who has preferved thi», afcribes the contlruc- 
 tion of it to one of the name of San Gallo. A ilcetch 
 of it is given in fig. 3. It is, however, fo much fupe- 
 rior, and fo different in principle, from that employed 
 for the cupola, that we cannot think it the invention of 
 the fame perfon. It is, like Pitot's, not only divifible, 
 but really divided into two parts, of which the upper 
 carries by much the greateft part of the load. The 
 pieces are judicioufly dilpofed, and every important beam 
 is amply fecured againll all tranfverfe Itrains. Its only 
 fault is a great profuGon of ilrenglh. Ihe innermoft 
 polygon aghb is qviite fuperfluo-js, becaufe no ftrain 
 can force in the ftruts which reft on the angles. Should 
 the piers yield outwards, this polygon will be loofe, and 
 can do no fervice. Nor is the triangle gih oi any ufe, 
 if the king-poft above it be ftrapped to the tie-beam and 
 ftraining fill. Perhaps the inventor confidered the king- 
 poft as a pillar, and wifhed to fecure the tie beam againft 
 its crofs ftrain. This centering, however, muft be al- 
 lowed to be very well compofed ; and we expecl that 
 
 the well-informed reader will join us in preferring It to Ccnrrp. 
 Mr Pitot's, both for fimplicicy oi principle, for fcienti- ^""^ "^ 
 fie propriety, and for ftrength. 
 
 Thereis one confiderable advantage which may be de- 
 rived from the aClual div'non of the tnifs into two parts. 
 If the tie-beam LL, inftead of refting on the ftretcher 
 EF, had rcfted on a row of chocks formed like double 
 wedges, placed above each other, head to point, the up- 
 per part of the centering might be ftruck iniiependent 
 of the lower, and this might be done gradually, begin- 
 ning at the outer ends of the ftretcher. By this proce- 
 dure, the joints of the arch-ftones will clofe on the 
 haunches, and will almnft relieve the lower centering, 
 fo that all can be pulled out together. Thus may the 
 arch fettle and conlolidate in perfect laftty, without any 
 chance of breaking the bond of the mortar in any part ; 
 an accident which frequently happens in great arches. 
 This procedure is peculiarly advKable for low pitched or 
 elliptical arches. But this will be more clearly fcen af- 
 tenvaids, when we treat of the iiitcrnal movements of 
 an arch of mafonrj'. 
 
 This may fuffice for an account of the more fimple 
 conftrui5tion of trufted centres ; and we proceed to fuch 
 as have a much greater complication of principle. We 
 (hall take for examples fome conftrufted by Mr Perro- 
 net, a very celebrated French architeft. j. 
 
 Mr Perronet's general maxim of conftruftion is to Perrrjnet's 
 make the trufs confift of feveral courfes of feparate truf- "'^■'"'" "f 
 fes, independent (as he thinks) of each other, and thus^."" ^"'^" 
 to employ the joint fupport of them all. In this con- 
 ftruftion it is not intended to make ufe of one trufs, or 
 part of one trufs, to fupport another, as in the former 
 iet, and as is praAifed in the roofs of St Paul's church, 
 Covent Garden, and in Drury Lane theatre. Each 
 trufs fpans over the whole diftance of the piers, and 
 would iband alone (having, however, a tottering equili- 
 brium). It confifts of a number of ftruts, fet end to 
 end, and forming a polygon. Thefe truffes are fo ar- 
 ranged, that the angles ot one are in the middle of the 
 fides of the next, as when a polygon is infcnbed in a 
 circle, and another (of the fame number of fides) is cir- 
 cumfcribed by lines which touch the circle m the angles 
 of the infcribed polygon. By this conftruftion the 
 angles of the alternate trufTcs lie in lines pointing to- 
 wards the centre of the curve. King-pofts are there- 
 fore placed in this direftion between the adjoining beams 
 of the truffes. Thefe king-pofts confill of two beams, 
 one on each fide of the trufs, and embrace the trufs- 
 beams between them, meeting in the mid:!le of their 
 thicknefs. The abutting beams are mortlfed, half into ^ 
 
 each half of t^.e poft. i he other beam, which makes 
 the bafe of the triangle, paffes through the poft, and a 
 ftrong.bolt is driven through the joint, and fecu.ed by 
 a key or a nut. In this manner is the whole united ; 
 and it is expefted, that when the load is laid on the up- 
 permoft truls, it will all butt together, forcing down the 
 king poft<:, and therefore preffmg them on the beams of 
 all the inferior truffes, caufing them alfo to abutt on each 
 other, and thus bear a ftiare of the load. Mr Pcrronet 
 does not affume the invention to himfelf ; but fays that 
 it was invented and praftifed by Mr Manfard de Sa- 
 gonne at the great bridge of Moulins. It is much more 
 ancient, and is the work of the celebrated phyfician and 
 architeft Ferrault ; as may be feen in the coUeftion of 
 machines and inventions of that gentleman publifhed af- 
 ter
 
 C E N [ 1 
 
 ter his death, and alfo in tht greit tolkftion of inven- 
 tions approved of by the Academy of Sciences. It i» 
 this which we propofe to examine. 
 
 Fig 4. reprefents tlie centering employed for the 
 bridge of Ciavant. The arches are eUlptlcal, of 60 feet 
 fpan and 20 feet rife. The archftoncs are four feet 
 thick, and weigh 176 pounds per foot. The tiuis- 
 beam<i were from 15 to 18 feet long, and their feAion 
 was 9 inches by 8. Each half of the king polls was 
 about 7 feet long, and its fcdlion 9 inches by 8. The 
 whole was of oak. The five truffes were ^i feet afiin- 
 dcr. The whole weight of the arch was ijjoooc lbs. 
 which we may call 600 tons (it is 5'58). This is a'. )ut 
 1 1 2 tons for each trufs. We mult allow near 90 tons 
 of th's really to prefs the trufs. A gieat part of this 
 preffure is borne by the four beams wh.ich make the feet 
 cf the trufs, coupled in pairs on each fide. The dlago- 
 nalof the parallelogram of forces drawn for thcfe beams 
 is, to one of the fides, in the proportion of 360 to 285. 
 Therefore fay, as 360 to 28J ; fo is 90 to 7 i| tons, the 
 thruft on each foot. The fcftion of each is 144 inches. 
 We may with the utmoll faftty lay three tons on tvery 
 inch for ever. This amounts to 432 tons, which is more 
 than fix times the ftrain really prcfling the foot beams 
 in the direflion of their length ; nay, the upper trufs 
 alone is able t*o carry much more than its load. The 
 abfolute ftrength of its foot-beam is 216 tons. It is 
 much more advantageoudy placed ; for the diagonal of 
 the parallelogram of forces coirefponding to its pofition is 
 to the fide as 438 to 285. This gives 58/5- tons for the 
 ilrain on each foot; which is not much above the fourth 
 part of what it is able to carry for ever. No doubt can 
 therefore be entertained of the fuperabundant ftrength 
 of this ccnteiing. We fee that the upper row of ftruts 
 is quite fufBcient, and all that is wanted is to procure 
 Itiffnefs for it ; for it muft be carefully kept in mind, 
 that this upper row is not like an equilibrated arch. It 
 will be very unequally loaded as tl)c work advances. 
 The haunches of the frame will be p^eficd down, and 
 the joints at the crown raifed up. This muft be re- 
 fitted. 
 
 Here then we may gather, by the way, a ufeful Itf- 
 fon. Let the outer row of ftruts be appropriated to 
 the carriage of the load, and let the reit be employed 
 for giving ftlfihtfs. For this purpofe let the outer row 
 have abundant itrength. The advantages of this me- 
 thod are confiderable. The pofition of the beams of 
 the exterior row is more advantageous, when (as in this 
 example) the whole is made to reft on a narrow foot ; 
 for this obliges us to make the laft angle, at leaft of the 
 lower row, more open, which increafes the ftrain on 
 the ftrut ; befidts, it is next to impoffible to dillribute 
 the comprefiing thruSs among the different rows of the 
 trufs beams ; and a beam which, during one period of 
 the mafon work, is afting the part of a ilrut, in another 
 period is bearing no ftrain but its own weight, and in 
 another it is flretched as a tie. A third advantage is, 
 that, in a cafe like this, where all refts on a narrow foot, 
 and the lower row of beams are bearing a great part of 
 the thruft. the horizontal thruft on the pier is very great, 
 and may pulh it afide. This is the moll ruinous acci- 
 dent that can happen. An inch or two of yielding will 
 caufe the crown of the arch to fink prodigioufly, and 
 will inftantly derange all the bearings of the abutting 
 beams ; but when the lower beams already aft as ties, 
 
 99 ] C E N 
 
 and r.rc qiTiie a<5equate to their ofljce, t/e render the Center 
 frame perfectly ttiff or iincnangeable in its form, and ^~-V— 
 take away the horizontal thruft from the piers enlire/y. 
 This advantage is tlie more valuable, becaufe the very 
 circumflance which obliges us to reft all on a narrow 
 foot, places this foot on the very top of the pier, and 
 makes tlie horizontal ihrult the more dangerous. 
 
 BuJ, to proceed in our examination ofihe centering 
 of Cravant bridge, let us fuppofe that the king pofts 
 are renwved, and that the beams are joined by compafs 
 joints. ]f the pier fhall yield in the fmalleft degree, 
 both rows of ftruts muft fink ; and fince the angles (at 
 leaft the outermoft) of the lower row are more open 
 than thcfe of the upper row, the crown of the lower 
 row will fink more than that of the upper. 
 
 The angles of the alternate rows muft therefore fepa- 
 rate a little. Now rtftore the king pofts ; they pre- 
 vent this feparation'. Therefore ihey are ftrtuhsd ; 
 therefore the beams of the lov.-er row are alfo firetched; 
 confequemly they no longer butt on their mortifes, and 
 mult be held in their placts by bolts. Thus it appears 
 thrt, in this kind of fagging, the original diftribution of 
 the load among the different rows of beams is changed, 
 and the upper low becomes loaded beyond our expedi- 
 tion. 
 
 If the fagging of the v.'liole trufs proceed only fiotn 
 the compreffion of the timbers, the cafe is different, and 
 we may preferve the original di!lribution of mutual abut- 
 ment more accurately. 13ut in this cafe the ftiffnefs of 
 the frame arifcs chitfly from crofs ftrains. Suppofe that 
 the frame is loaded with archftones on each fide up to 
 the pofts HC, he; the angles E and e are prcffed 
 down, and the beams EOF, eo F pufh up the point F. 
 This cannot rife without btiiding the beams EOF, to F; 
 becaufe O and are htld down by the double king pofts, 
 which grafp the bt;Kms between them. There is there, 
 foie a crofs llrain on the b..'am8. Obferve alfo, that the 
 tiiangle EHF does not preferve it; Ihape by the con- 
 nexion of its joints; for although the ftrut beams are 
 mortifed into the king poft, tliey are in very {hallow 
 mottifes, rather for fteadying them than for holding 
 them together. Mr Peironct did not even pin them, 
 thinking that their abutment was very great. The tri- 
 angle is kept in fliape by the bafe EF, which is firmly 
 bolted into the middle poft at O. Had tliefe interfec- 
 tions not been flrongly bolted, we imagine tliat the cen- 
 tres of fome of Mr Perronet's bridges would have yield- 
 ed much more than they did ; ytt fome of them yield- 
 ed to a degree that our artifts would have thought very 
 dangerous. Mr Perronet was obliged to load the crown 
 of the centering with very great weights, incrcafing 
 them as the work advanced, to prevent the fiames from 
 going out of (hape : in one arch of 12c feet he laid on 
 45 tons. Notwiihftanding this impel ftftion, which is 
 perhaps unavoidable, this mode of framing is undoubt- 
 edly very judicious, and perhaps the bcft which can be 
 employei without depending on iron-work. ,_ 
 
 Fig. 5. reprefents another, conftrufted by Perronet For the 
 for an arch of 90 feet fpan and 28 feet rife. The truf- '"'''K'' "^ 
 fes were 7 feet apart, and the arch was 44 thick ; fo that ^°£'"'> 
 the unreduced load on each frame was very nearly 23 c 
 tons. The fcantling of the ftruts was 1 5 by 1 2 inches. 
 The principle is the fame as that of the former. Phe 
 chief diffeience is, that in this centre the outer trufs- 
 bcaiB of the lower row is not coupled with the middle 
 
 row.y
 
 Center. 
 
 ti' Max. 
 ence. 
 
 Neiiilly, 
 
 C E N [2 
 
 row, but kept nearly parallel to tlie rvut<?r team of ttie 
 '' upper row. This adds greatly to the (Irength of the 
 foot, and takes off much of the horizontal thrull from 
 the pier. 
 
 Mt Perronft has ftewn great iudfjment in caufing 
 the polygim of the inner row of trufs beams gradually 
 to Kppro?.ch the polygon of the outer row. By this 
 difpofition, the angleb of the innir polygon are more 
 ac\ite thnn thofe of the outer. A little attention will 
 ftcw, that the general fagging of all the polygons will 
 keep the abutments of the lower one nearer, or exaftly, 
 to their original quantity. We mull indeed except the 
 foot beam. It is dill too oblique ; and, inftead of con- 
 verging to the foot of the upper row, it (hould have di- 
 verged from it. Had this been done, this centre is al- 
 moli perfect in its kind. As it is, it is at lead fix times 
 ftronrer than was abfolutely neceffary. We (hall have 
 occa.'ion to refer to this figure on another occafion. 
 
 This maxim is better exemplified by Mr Perronet in 
 the centering of the bridge of St May.ence, exhibited in 
 fig. 5 n° 2. than in that of Nogent, fig. 5. n° i. Bat 
 we think that a horizontal trufs-beam ab (liould have 
 been inferted (in a fubordinate manner) between the 
 king-ports next the crown on each fide. This would 
 prevent the crown from rifing while the haunches only 
 are loaded, without impairing the fine abutments of c </, 
 c (I, when the arch is nearly completed. This is an ex- 
 cellent centering, but is .rot likely to be of much ufe in 
 ihefe kingdoms ; becaufe the arch itfclf will be coufi- 
 dered as ungraceful and ugly, looking like a huge lin- 
 tel. Perronet fays, that he preferred it to the ellipfe, 
 becaufe it was lighter on the piers, which were thin. 
 But the failure of one arch mull be immediately follow- 
 ed by the ruin of all. We know much better methods 
 of lightening the piers. 
 
 Fig. 6 reprefents the centering of the bridge of 
 Neuilly, near Paris, alfo by Perronet. The arch has 
 I zo feet fpan, and 30 feet rife, and is 5 feet thick. 
 The frames are 6 feet apart, and each carries an abfo- 
 lute (that is, not reduced to \-^ or to ^) load of 350 
 tons. The ftrut beams are 17 by 14 inches in fcant- 
 ling. The king pofts are of i 5 by 9 each half ; and 
 the horizontal bridles, which bind the different frames 
 together in five places, are alfo i ,- by 9 each half. 
 There are eight other horizontal binders of 9 inches 
 fquare. 
 
 This is one of the moft remarkable arches in the 
 world ; not altogether on account of its width (for 
 there are feveral much wider), but >or the flatnefs at 
 the crown ; for about 26 feet on each fide of the middle 
 it was intended to be a portion of a circle of 150 feet 
 radius. An arch (femicircular) of ^00 feet fpan might 
 therefore be eafily conftruAed, and would be much 
 ftronger than this, becaufe its horizontal thruft at the 
 crown would be vallly greater, and would keep it more 
 firmly united. 
 
 The bolts of this centre are differently placed from 
 thofe of the former ; and the change is judicious. Mr 
 Perronet had doubtlcfs found by this time, that the 
 ftiffnefs of his framing depended on the tranfverfe ftrength 
 of the beams ; and therefore he was careful not to weak- 
 en them by the bolts. But notwithftanding all his care, 
 the framing funk upwards of 1 3 inches before the key- 
 ftones were laid ; and during the progrefs of the work, 
 the crown rofe and funk, by various fteps, as the loading 
 
 00 ] C E N 
 
 was extended along it. When 20 courfes were laid on Ccter. 
 each fide, and about 16 tons laid on the crown of each *—- v— ■ 
 frame, it funk about an inch. When 46 coiirfcs were 
 laid, and the crown loaded with 50 tons, it funk about 
 halt an inch more. It conlirued finking as the work 
 advanced ; and when the key Hone was fct it had funk 
 i^i inches. But this finking was not general ; on the 
 contrary, the frame had rifen greatly at the very haunch- 
 es, fo as to open the upper pait of the joints, many of 
 which gaped an inch ; and this opening of the joints 
 gradually extended from the haunches towards the 
 crov.'ii, in the neighbourhood of which they opened on 
 the under fide. i'his evidently arofe from a want of 
 ftiffnefs in the frame. But thefe joints clofed again 
 when the centres were ftruck, as will be mentioned af- 
 terwatds. 
 
 *- We have taken particular notice of the movements 
 and twilling of this centre, becaufe we think that they 
 indicate a deficiency, not only of ftiffnefs, but of abut- 
 ment among the trufs beams. The whole has been 
 too flexible, becaufe the angles are too obtufe : This 
 arifes fiom their multiplicity. When the intercepted 
 arches have fo little curvature, the power of the load 
 to prefs it inward Increafes very fait. When the in. 
 tercepted arch is reduced to one half, this power is 
 more than doubled ; and it is alfo doubled when the 
 radius of curvature is doubled. The king polls (hould 
 have been farther apart near the crown, fo that the 
 quantity of arch between them (hould compenfate for 
 its diminilhed curvature. 
 
 The power of withftanding any given inequality of 
 load would therefore have been greater, had the centre 
 confifted of fewer pieces, and their angles of m:eting 
 been proportionally more acute. The greattft improve- 
 ment would have been, to place the fool of the lower 
 tier of trufs-beams on the very foot of the pier, and to 
 have alfo feparated it at the head from the reft with a 
 longer king-poft, and thus to have made the diftances 
 of the beams on the king-pofts increafe gradually from 
 the crown to the fpring. This would have made all 
 the angles of abutment more acute, and would have pro- 
 duced a greater prelTure on all the lower tiers when the 
 frame fagged. 
 
 Fig. 7. reprefents the centering of the bridge of Or-Q , ^° 
 leans. The arch has 100 feet fpan, and rifes 30, and 
 the arch-ftones are 6 feet long. It is the conftruAion 
 of Mr Hupeau, the firft architeA of the bridge. It is 
 the boldell work of the kind that we have leen, and is 
 conftrufted on clear principles. The main abutments 
 are few in number. Becaufe the beams of the outer 
 polygon are long, they are very well fupported by 
 ftraming beams in the middle ; and the ftruts or braces 
 which fupport and butt on them, are made to reft on 
 points carried entirely by ties. The inventor, however, 
 feems to have thought that the angles of the inner po- 
 lygon were fupported by mutual compreflion, as in the 
 outer polygon. But it is plain that the whole inner 
 polygon may be formed of iron rods. Not but that 
 both polygons may be in a ftate of compreflion (this i» 
 very poffible) ; but the fnialleft fagging of the frame 
 will change the proportions of the preffures at the an- 
 gles of the two polygons. The preffures on the exte- 
 rior angles will incrcale, and thofe on the lower or iu- 
 terior angles will diminilh moft rapidly ; fo that the a- 
 butraents in the lower polygon will be next to no- 
 
 thing.
 
 Center. 
 
 Inflrufllvi; 
 Mftory of 
 this centre 
 
 C E N [ 20! ] C E N 
 
 thin^. Such points could bear very little prcfTiire from the whole load (fny hy doubling its beams), and we Center, 
 
 the braces which fupport the middle of the long bear- may then make the lo'vcr polygon of (lender dimen- v~~~- 
 
 ings of the upper beams, and their prtflures mull be fions, provided we fecure the joint.'; on the k.ing-p(jfts 
 
 borne chiefly by the joints fiipported by the king-pofts. by iron ftraps which embrace a confiderable portion of 
 
 The king-pofts would then be in a ftate of extenfion. the tie on each fide of thf joint. 2, 
 
 It is difficult, however, to decide what is the precife We are far from thinking that thefe centres are of .-ill th'fe 
 
 ftate of the preffure at thefe interior angles. the befl kind that could be employed in their fituation •,«'"|=, 
 
 The hiftory of the ereftion of this bridge will throw 
 mucli light on this point, and is very inftruftive. Mr 
 Hupeau died before any of the arches were carried far- 
 ther than a very few of the firft courfes. Mr Perronet 
 fucceeded to the charge, and finifhed the bridge. As 
 the work advanced, the crown of the frame rofe very 
 itiuch. It was loaded ; and it funk as remarkably. 
 This (hewed that the lower polygon was giving very 
 little aid. Mr Perronet then thought the frame too 
 weak, and inferted the long beam DE, making the 
 diagonal of the quadrangle, and very nearly in the di- 
 
 but thcv are excellent in their kind : and a careful^/ 
 
 >rt'J ill 
 
 ftudy of them will teach the artift much of his profef- 
 fion. When we have a clear conception of the (late 
 of ftrain in which the parts of a frame really are, we 
 know what (hould be done in order to draw all the ad- 
 vantage polTible from our materials. We have faid in 
 another place, thnt where we can give our joints fufii- 
 cient connexion (as by flraps and bolts, or by cheeks 
 or fifhes), it is better to ufc ties than ftruts, becaulc 
 ties never bend. 
 
 We do not approve of Mr Perronet's praftice of gi 
 
 cheir kiiiJ. 
 
 reiStion of the lower beam a h, but falling rather below ving his trulTes fuch narrow feet. By bringing the foot 
 
 this line. He now found the frame abundantly llrong. 
 It is evident that the trufs is now changed exceedingly, 
 and confills of only the two long fides, and the (hort 
 ftraining beam lying horizontally between their heads. 
 The whole centering confifts now of one great trufs 
 aY^el, and its long fides aY^, eb, are truffed up at B 
 artdy. Had this fimple idea been made the principle 
 of the conllruftion, it would have been excellent. The 
 angle a DE might have been about 176*^, and the po- 
 lygon D c A ^ employed only for giving a flight fup- 
 port to this great angle, fo as not to allow it to exceed 
 
 of the lower polygon farther down, we greatly diminirti 
 all the drains, and throw more load on the lower poly- 
 gon : and we do not fee any of Mr Perronet's centres 
 where this might not have been done. He feems to af- 
 fedl a great fpan, to (hew the wonders of his art ; but 
 our objedl is to teach how to make the bell centre of a 
 given quantity of materials ; and how to make the moll 
 perfett centre, when we are not limited in this refpecl, 
 nor in the extent of our fixed points. H 
 
 We (hall conclude this feries of examples with one '^f'^-ll<;^i=e 
 where no fuch affeftation takes place. This is the cen- "' '"^^ '^f'" 
 180". But Mr Perronet found, that the joint c, at the tering of the bridge at Blackfriars, London. The fpaa'/j f,,"''""''' 
 foot of the poll E c, was about to draw loofe, and he of the arch is 100 feet, and its height from the fpring Blackfriars 
 was obliged to bolt long pieces of timber on each fide is about 4^. The drawing fig. 8. is fufliciently minutel'fiJge- 
 of the joint, embracing both beams. Thefe were evi- to convey a diftinft notion of the whole conilrudlion. 
 dently afting the fame part as iron ftraps would have We need not he very particular in our obfervations, af- 
 done ; a complete proof that, whatever may have been ter what has been faid on the general principles of con- 
 the original prefFures, there was no abutment now at ftruftion. The leading maxim, in the prefent example, 
 the point c, and that the beams that met there were feems to be, that every part of the arch fiall be fupported 
 not in a ftate of compreflion, but were on the ftretch. by a fimple trufs of two legs refl'm^, one on each pier. 
 
 H, H, &c. are called apron piecfs, to ftrengtheii the 
 exterior joints and to make the ring as ftiff in itfelf 
 as poffible. From th« ends of this apron-piece proceed 
 the two legs of each trufs. Thefe legs are 12 inches 
 fquare : They are not of an entire piece, but of feveral, 
 meeting in firm abutment. Some of their meetings are 
 
 Mr Perronet fays that he put thefe cheeks to the joints 
 tofliffen them. But this was not their office ; becaufe 
 the adjoining beams were not ftruts, but ties, as we have 
 now proved. 
 
 We may therefore conclude, that the outer polygon, 
 with the alTiftance of the pieces a b, DE, were carrying 
 
 the whole load. We do not know the diftance between fecured by the double king-pofts, which grafp them 
 
 the frames ; but fuppofing them fevcn feet apart, and firmly between them, and are held together by bolts, 
 
 the arch 6 feet thick, and weighing 170 pounds per foot, At other interfeftions, the beams appear halved into 
 
 we learn the load. The beams were 16 inches fquare. each other; a pradlice which cannot but weaken them 
 
 If we now calculate what they would bear at the fame much, and would endanger their breaking by crofs 
 
 very moderate rate allowed to the other centres, we find drains, if it were poflible for the frame to change its 
 
 that the beams AB and ab are not loaded to one-fixth fhape. But the great breadth of this frame is an ef- 
 
 of their ftrength. _ feftual flop to any fuch change. The faft was, that 
 
 We have given this centre as a fine example of what no ftnkinn or twijUng whatsiier was oLferved during the 
 carpentry is able to perform, and becaufe, by its fim- progrefs of the mafon work. Three points in a ftiaight 
 plicity, it is a fort of text on which the intelligent ar- line were marked on purpufe for this obfervaiion, and 
 tift may make many comments. We may fee plainly were obferved every day. The arch was more than lix 
 that, if the lower polygon had been formed of iron rods, feet thick; and yet the finking of tlie crown, before 
 firmly bolted into the feet of the king-pofts, it would fetting the k~y-ftones, did i),jt amount to one inch, 
 have maintained its fhape completely. The fervice done The centre employs about one-third more timber 
 by the beam DE was not fo much an increafe of abut- than Perronet's great centre in proportion to the fpan 
 ment as a difcharge of the weight and of the pull at the of the arch ; but the circumference incrcafes in :i 
 joint c. Therefore, in cafes where the feet of the trufs greater proportion than this, becaufe it is more f leva- 
 are necejarily confined to a very narrow fpace, we (hould ted. In every way of making a comparifon of the di- 
 be careful to make the upper polygon fuificicnt to carry meufions, Mr Mylne's arch employs more timber ; bat 
 
 SuppL. Vol. I. Part T ' Cc :♦
 
 ^C E N [2 
 
 Center. Jt Jg tfygnd all comparifon ftronger. The ^reat elevation 
 • is partly the reafon of this. But the diiijofilion of the 
 
 timbers is alfo much move advantageous, and may be 
 copied even in the low pitched arches of Ncuilly. The 
 fimple tvufs, reaching from pier to pier for the middle 
 point of the arch, gives the ihong fupport where it is 
 moft of all wanted ; and in the lateral points H, al- 
 though one leg of the trufs is very oblique, the other 
 compenfates for it by its upright pofilion. 
 
 The chief peculiarity of this centre is to be feen in 
 its bafe. This demands a more particular attention : 
 but we muft firlt make fome obfervacions on the condi- 
 tion of an arch, as it reits on the centering after the 
 keyftones are all fet, and on the gradual trjnsferenee 
 of the preffure from the boards of the centering to the 
 joints of the archftones. 
 '< While all the archftones lie on the centering, the 
 
 - "^T^".^. lower courfes are alfo leaning pretty ftrongly on each 
 ftaeofan Other. But the mortar is hardly comprelled in the 
 arch as it joints ; and leaft of all in the joints near the crown, 
 refts on the Suppofe the arch to be catenarian, or of any other 
 ceiueriDg. ^^p^, j|jj,(, jg pej-ftftly equilibrated : When the center- 
 ing is gradually withdrawn, all the ^chftones follow it. 
 Their wedge-like form makes this impoffible, without 
 the middle ones fqueezing the lateral ones afide.' This 
 comprelFes the mortar between them. As the ftones 
 thus come nearer to each other, thofe near the crown 
 muft defcend more than thoie near the haunches, be- 
 fore every ftone has leflened its diftance from the next 
 by tlie fame quantity ; for example, by the hundredth 
 part of an inch. This circumftance aloiie muft caufe a 
 finking in the crown, and a change of (hape. But the 
 joints near the crown are already more open than thofe 
 near the haunches. This produces a ftill greater change 
 of form before all is fettled. Some mafons endeavour 
 to remedy, or at leaft to diminifh, this, by ufing no 
 mortar in the joints near the crown. They lay the 
 ftones dry, and even force them together by wedges 
 and blocks laid between the ftones on oppofite fides of 
 the crown : They afterwards pour in fine cement. This 
 appears a good praftice. Perroijet rejefts it, becaufe 
 the wedging fometimes breaks the ftones. We (hould 
 not think this any great harm ; becaufe the frafture 
 will make them clofe where they would otherwife lie 
 hollow. But, after all our care, there is ftill a linking 
 of the crown of the arch. By gradually withdrawing 
 the centering, the joints clofe, the archftones begin to 
 butt on each other, and to force afide the lateral courfes. 
 This abutment gradually increafing, the preffure on the 
 haunches of the centering is gradually dimliiifhed by 
 the mutual abutment, and ceafes entirely in that courfe, 
 which is the loweft that formerly prefled it : it then 
 ceafes in the courfe above, and then in the third, and 
 fo on. And, in this manner, not only the centering 
 quits the arch, gradually, from the bottom to the top, 
 hy its own retiring from it, but the arch alfo quits the 
 centenng l/y changing itsjhape. If the centering were 
 row puihed up again, it would touch the arch firft at 
 the crown ; and it muft lift up that part gradually be- 
 fore it come again in contaft with the haunches. It 
 is evident, therefore, that an arch, built on a centre of 
 a fiiape perfeftly fuited to equilibration, will not be in 
 equilibrio when the centering is removed. It is there- 
 fore neceffary to form the centering in fuch a manner 
 {by raifing the crown), that it ftiall leave the arch of 
 
 25 
 A delicate 
 
 02 ] C E N 
 
 a proper form. Tfiis is a very delicate tafl{, requiring Center, 
 a previous knowledge of the enfuing change of form. '— v-— 
 This cannot be afcertained by the help of any theory 
 we are acquainted with. 
 
 But, fuppofe this attained, there is another difficulty: 
 While the work advances, the centering is warped by 
 the load laid on it, and continually increafing on each 
 fide. The firll preffure on ^he centering forces down 
 the haunches, and raifes the crown. Tlie arch is there- 
 fore lefs curved at the haunches than is intended : the 
 joints, however, accommodate themfelves to this form, 
 and are clofe, and filled with mortar. When the ma- 
 fons approach the middle of the arch, the frame finks 
 there, and rifes up at the haunches. This opens all the 
 joints in that place pn the upper fide. By the time that 
 the keyftones are fet, this warping has gone farther ; 
 and joints are opened on the under fide near the crown. 
 It is true we are here fpeaking rather of an extreme 
 cafe, when the centering is very flexible ; but this oc- 
 curred to Mr Perronet in the two great bridges of Neu- 
 illy and of Mantz. In this laft one, the crown funk 
 above a foot before the key was fet, and the joints at 
 the haunches opened above an inch above, while lome near- 
 er the crown opened near a quarter of an inch beloiu. 
 
 In this condition of things, it is a delicate buGnefs to (,*,(;„ j'fsTo 
 ftrike the centering. Were it removed in an inftant, all ftrike ihe_ 
 would probably come down ; for the archftones are not'^2""f'''g' 
 yet abutting on each other, and the joints in the middle 
 are open below. Mr Perronet's method appears to us 
 to be very judicious. He began to detach the center- 
 ing at the very bottom, on each fide equally, where the 
 preffure on the centering is very flight. He cut away 
 the blocks which were immediately under each arch- 
 ftone. He proceeded gradually upwards in this way 
 with fome fpeed, till all was detached that had been put 
 out of (liape by the bending of the centering. This be- 
 ing no longer fu])ported, funk inward, till it was flopped 
 by the abutment which it found on the archftones near 
 the crown, which were ftill refting on their blocks. 
 During part of this procels, the open joints opened ftill 
 more, and looked alarming. Tliis was owing to the re- 
 moval of the load from the haunches of the centenng. 
 This allowed the crown to fink ftill more, by forcing 
 out the arch ftones at the haunches. He now pauled 
 fome days; and during this time the two haunches, now 
 hanging in the air, gradually preffed in toward the cen- 
 tering, their outer joints clofing in the meanwhile. The 
 haunches were now prefling pretty hard on the arch- 
 ftones nearer the crown. He then proceeded more 
 flowly, deftroying the blocks and bridgings of thele up- 
 per archftones. As foon as he deftroyed the fupport of 
 one, it immediately yielded to the preffure of the haunch; 
 and if the joint between it and the one adjoining to- 
 ward the crown happened to be open, whether on the 
 under or the uj'perfide, it immediately clofed on it. 
 But in proceeding thus, he found every ftone fink a 
 little while it clofed on its neighbour ; and this was like 
 to produce a ragged foffet, which is a deformity. He 
 therefore did not allow them to fink fo much. In the 
 places of the blocks and bridgings which he had cut 
 away, he fet fmall billets, ftanding on their ends, between 
 the centering and the archftones. Thefe allowed the pen- 
 dulous arch to pufli toward the crown without fenfibly 
 defcending ; for the billets were puftied out of the per- 
 pendicular, and fome of them tumbled down. Proceed- 
 ing
 
 C E N [a 
 
 ing in this way, he advanced to the very next courfe to 
 the keyllone on each fide, the joints cloliii^ all the way 
 as he advanced. The lalt job was very tioublefome ; 
 we mean the detaching the three uppernioll courfes from 
 the centering : for the whole elalllcity of the center- 
 ing was now trying to unbend, and preifing hard againil 
 them. He found that they were litted up ; for the 
 joints beyond them, which had doled completely, now 
 opened again below ; but this job was linilhed in one 
 day, and the centre fprung up two or three inches, and 
 the whole arch funk about fix inches. This was an 
 anxious time ; for he dreaded the great momentum of 
 fuch a vaft mafs of matter. It was hard to fay where 
 it would Hop. He had the pleafure to fee that it Hop- 
 ped very foon, fettling (lowly as the mortar was coni- 
 prcd'ed, and after one or two days fettling no more. 
 This fettling was very confiderable both in the bridge 
 at Neuilly and U^ that at Mantz. In the former, the 
 finking during the work -amounted to 13 inches. It 
 funk fix inches more when the blocks and bridgings 
 were taken out, and i-J- when the little ilandards were 
 deftroyed, and i^ more next day ; fo that the whole fink- 
 ing of \\\t pendulous arch was g-J- inches, befides what it 
 had iunk by the bending and compreflion of the center- 
 ing. 
 
 The crown of the centering was an arch of a circle 
 defcribed with a radius of 150 feet ; but by the finking 
 of the arch its (hape was confiderably changed, and 
 about fio feet of it formed an arch of a circle whofe 
 radius was 244 feet. Hence Mr Perronet infers, that 
 a ftmicircle of joo feet fpan may be ereiited. It would 
 no douljt be ftronger than this arch, becaufe its greater 
 horizontal thrull would keep the ftones firmer together. 
 The finking of the arches at Mantz was not quite fo 
 great, but every thing proceeded in the fame way. It 
 amounted in all to 23 J- inches, of which 12 inches were 
 owing to the compreflion and bending of the center- 
 ing- 
 
 In fig. y. n° I. mav be obferved an indication of this 
 procedure of the mafonry. There may be noticed a 
 horizontal line a c, and a diagonal a b. Thefe are fup- 
 pofed to be drawn on the mafonry as it would have 
 flood had the frames not yielded during the building. 
 The dotted line A^' c (hews the (liape which it took 
 by the finking of the centering. The dotted line on 
 the other fide was aftuallv drawn on the malonry when 
 the keyftone was fet ; and the wavy black line on the 
 fame fide (liews the form which the dotted line took by 
 the ftriking of the centering. The undulated part of 
 this line cuts its former pofition a little below the middle, 
 going without it below, and falling within it above. 
 This (hews very diftindly the movement of the whole 
 mafonry, diftinguifhing the parts that were forced out 
 and the parts which funk inward. 
 
 We prefume that the praAlcal reader will think this 
 account of the internal movements of a (lupendous arch 
 very inftruftlve and ufeful. As Mr Perronet obferved 
 It to be uniformly the fame in feveral very large arches 
 ■which he erefted, we may conclude that it is the gene- 
 ral procefs of nature. We by no means have the con- 
 fidence in the durability or folidity of his arches which 
 he prudently profelTes to have. We have converfed with 
 fome very experienced mafons, who have alfo erefted 
 very great arches, and in very difficult fituations, which 
 have given univerfal fatisfaftion ; and we have found 
 
 o.'5 ] C E N 
 
 them uniformly of opinion, that nn arch whicli has fet- Center. 
 tied to fuch a proportion of Its curvature as to change '— -Y— 
 the radius from 150 to 244 feet. Is in a very hazardous 
 fituation. They think the hazard the greater, becaufe 
 the fpan of the aich is fo great in proportion to ita 
 weight (as they cxpiefs it very emphatically) or its 
 height. The weight, fay they, of the haunches is too 
 fmall tor forcing together the keylhwes, which have 
 fcarccly any vvedge like form to keep them from Aiding 
 down. This is very good rcafoning, and expreffes very 
 familiar notions'. The mechanician would fay, that the 
 horizontal thruft at the crown Is too fmall. When we 
 quellioned them about the propriety of Mr Perronet'* 
 method of removing the centering, they unanimoufly 
 approved of its general principle, but fiiid that It was 
 very tlckhfli indeed In the execution. The cafes which 
 he narrates were new to them. They fiiould have al- 
 moil dcfpalred of fuccefs with arches wiiich had gone fo 
 much out of (liape by the bending of the centres ; be- 
 caufe, faid they, the (lope of the centering, to a great 
 diftance from the crown, was fo little, that the arch- 
 fl;ones could not (lide outwards along It, to clofe even 
 the under fide of the joints which had opened above 
 the haunches ; fo that all the archftones were at too 
 great a dillance from each other ; and a great and gene^ 
 ral fubfiding of the whole was necelfary for bringing 
 them even to touch each other. They had never obfer- 
 ved fuch bendings of the centerings which they had em- 
 ployed, having never allowed themfelves to contraft the 
 feet of their trulfes into fuch narrow fpaces. Thev ob- 
 ferved, that nothing but lighters with their malls down 
 can pafs under the trulTes, and that the fides iniift he {t3 
 proteded by advanced works from the accidental (hock 
 of a loaded boat, that there cannot be left room for 
 more than one. They added, that the bridges of com- 
 munication, necefi'aiyfor the expeditious conduftlng of 
 the work, made all this fuppofcd roomincfs ufelefs :°be- 
 fides, the bufinefs can hardly be fo urgent and crowded 
 anywhere, as to make the palfagc through every arch in- 
 dil'penfably neceflary. Nor was the inconvenience of 
 this obllruftion greatly complained of during the erec- 
 tion of Wellminlter or Blackfrlars bridges. Nothing 
 (hould come in competition with the undoubted folidity 
 of the centering and the future arch ; and all boalting 
 dllplay of talent and Ingenuity by an engineer, in the 
 exhibition of the wonders of his art, is mifplaced here. 
 
 Thele appeared to us good reafons for preferring the 
 more cautious, and incomparably more fecure, conllruc- 
 tion of Mr Mylne, in which the breadth given to each 
 bafe of the truifes permitted a much more cffeftlve dif- 
 pofition of the abutting timbers, and alfo enabled the 
 engineer to make It incomparably ftlffer ; fo that no 
 change need be apprehended in the joints which have 
 already doled, and in which the mortar has already ta- 
 ken its fet, and commenced an union that never can be 
 reilored if it be once broken In the fmalleft degree, no 
 not even by greater compreffion. 
 
 Here we beg leave to mention our notions of the- ' 
 connexion that is formed by mortar compofed of lime pefli,,, 
 or gypfum. We confider it as confilling chiefly, if notJhaVi'^' 
 folely, in a cryRalllzation of the lime or gypfum and formed 
 water. As much water is taken up as is neceflfary for*"^' !"<"■'»' 
 the formation of the cryftals during their gradual con-^^'"' 
 verfion into mild calcareous earth or alabafter, and the 
 reft evaporntes. When the free accefs of air is abfo. 
 C c 2 lutely 
 
 7 
 
 con- 
 ion 
 
 mie,
 
 C E N 
 
 [ 204 ] 
 
 C E N 
 
 Center, lutely prevented, the crylluUizatlon never proceeds to 
 I that ilatf, even although the mortar becomes extremely 
 
 dry and hard. We had an opportunity of obferving 
 this accidentally, when palTing through Maellricht in 
 J 7 70, while they were cutting up a mafly revftment of 
 a part of the fortifications more than 300 years old. 
 The mortar between the bricks was harder than the 
 bricks (which were Dutch clinkers, fuch as are now 
 iiied only for the greateft loads) ; but when mixed with 
 water it made it lime water, fecmlngly as ftrrong as if 
 frefli lime had been ufcd. We obfervcd the fame thing 
 in one fmall part of a huge mafs of ancient Roman work 
 near Romney in Kent ; but the reft, and all the inry 
 old mortar that we have feen, was in a mild ftate, and 
 vas generally much harder than what produced any 
 lime-water. New when the mortar in the joints has 
 begun its fir!\ cryftallization, and is allowed to remain 
 in perfcdt reit, we are confident that the fubfequent cry- 
 ftals, whether of lime, or of calcareous earth, or of gyp- 
 fum, will be much larger and ftronger than can ever be 
 produced if they are once broken ; and the farther that 
 this cryftallization has been carried, that is, the harder 
 that the mortar has become, Icfs of it remains to take 
 any new cryftallization. Why fhould it be otherwife 
 here than in every other cryflallization that we are ac- 
 18 quaintcd with ? 
 Neccffity ol We think therefore that it is of great confequence 
 _kfep:ngthej^ keep the joints in iheir Jrj} ftale if poffible ; and 
 ihcVfirft tli!>t the ftrength (as far as it depends on the mortar) 
 ftate. is greatly diminiihed by their opening; efpecially when 
 
 the mortar has acquired confiderable hardnefs, which it 
 will do in a month or fix weeks, if it be good. The 
 cohefion given by mortar is indeed a mere trifle, when 
 oppofed to a force which tends to open the joints, adt- 
 ing, as it generally does, with the traniverfe force of a 
 lever : but in fituations where the overload on any par- 
 ticular archftones tends to pulh them down through be- 
 tween their neighbours, like wedges, the cohefiun of the 
 mortar is then of very great confequence. 
 
 We muft make another obfervation. Mr Perronet's 
 ingenious procefs tended very effcftually to clofe the 
 joints. It doing this, the forces which he brought in- 
 to aftion had little to oppofe them ; but as foon as they 
 were clofed, the contaiSt of the parts formerly open op- 
 pofed an obftrudtion incomparably greater, and imme- 
 diatrly balanced a force which was but juft able to turn 
 the ftone gently about the two edges in which it touch- 
 ed the adjoining ftones. This is an important remark, 
 though feemingiy very trifling ; and we wifli the prac- 
 titioner to have a very clear conception of it ; but it 
 would take a multitude of words to explain it. It is 
 worth an experiment. Form a little arch of wooden 
 blocks ; and form one of thcfe fo, that when they are 
 all refting on the centering, it may be open at the outer 
 joint — Remove the centering — Then prefs on the arch 
 at fome diftance from the open joint. — You will find 
 that a very fmall prefTure wUl make the arch bend till 
 that joint clofes. — Prefs a little harder, and the arch will 
 bend more, and the next joint will open. — Thus you 
 will find that, by prefling alternately on each fide of the 
 open joint, that ftone can ealily be made to flap over to 
 either fide ; and that immediately after this is done the 
 refiilance increafes greatly. This fiiews clearly, that a 
 very moderate force, judicloufly employed, will clofe 
 the joints, but will not prefs tie parts ftrongly toge- 
 
 ther. The joints therefore are clofed, but no more than Center. 
 clofed, and are hanging only by the edges by which they *-"-»—— ' 
 were hanging while the joints were open. The arch, 
 thcicfore, though apparently clofe and firm, is but loofe 
 and tottering. Mr Perronet fays, that his arches were 
 firm, becauie hardly a ftone was obfervcd to chip or 
 fplinter off at the edges by the fettlement. But he had 
 done every thlEig to prevent this, by digging out the 
 mortar from between the headere, to the depth of two 
 inches, with faws made on purpofe. But we are well 
 informed, that before the year 1791 (twent)- years af- 
 ter the eredtion) the arches at Ncuilly had funk very 
 fenfibly, and that very large fplinters had flewn off in . 
 feveral places. It could not be otherwife. The oiigi- Mr Perro- 
 nal conllruftion was too bold ; we may fay needlcfsly net's con- 
 and oftentatioufiy bold. A very gentle (lope of the '^'■"^'°°' 
 roadway, which would not have flackened the mad gal- 
 lop of a ducal carriage, nor fenfibly checked the labo- 
 rious pull of a loaded waggon, and a proper dliference 
 in the fize of the arches, would have made this won- 
 derful bridge incomparably ftronger and alfo much 
 more elegant and pleafiug to the eye. Indeed, it is far 
 from being as handfome as it might have been. The 
 eUipfe is a moft pleafing figure to every beholder ; but 
 this is concealed as much as poffible, and it is attempt- 
 ed to give the whole the appearance of a tremendous 
 lintel. It has the oppreffive look ot danger. It will 
 not be of long duration. The bridge at Mantz is ftill 
 more exceptionable, becaufe its piers are tall and /lender. 
 If any one of the arches fails, the reft muft fall in a 
 moment. An arch of Blackfriars Bridge might be 
 blown up without difturbing its neighbours. ^ 
 
 Mr Perronet mentions another mode of ftriking the A bad me. 
 centering, which he fays is very ufual in France. Every thod of 
 fecond bridging is cut out. Some time after, every fe- "■'''""g '"* 
 cond of the remainder ; after this, every fecond of the 
 remainder ; and fo on, till all are removed. This is ne- 
 ver prattifed in this country, and is certainly a very bad 
 method. It leaves the arch hanging by a number of di- 
 ttant points ; and it is wondertul that any arch can bear 
 this treatment. 
 
 Our architedts have generally proceeded with extreme 
 cautioni Wherever they could, they fupported the cen- 
 tering by intermediate pillars, even when it was a trufTed 
 centre, having a tie-beam reaching from fide to fide. 
 The centre was made to reft, not immediately on t^c'^xhe o 
 pillars, but on pieces of timber formed like acute wedges, nion me- 
 placed in pairs, one above the other, and having thethodin 
 point of the one on the thick end of the other. Thcfe J*"'^'- 
 wedges were well foaped and rubbed with black lead, to 
 make them flippery. When the centres are to be ftruck, 
 men are Rationed at each pair of the wedges with heavy 
 malls. They are diredled to ftrike together on the op- 
 pofite wedges. By this operation, the whole centering 
 deicends together ; or, when any part of the arch is ob- 
 fervcd to have opened its joints on the upper fide, the 
 wedges below that part are flackened. The framing 
 may perhaps bend a little, and allow that part to fub- 
 fide. If any part of the arch is obfervcd to open its 
 joints on the under fide, the wedges below that part are 
 allowed to ftand after the reft have been flackened. By 
 this procefs, the whole comes down gradually, and as 
 flowly as we pleafe, and the deiedls of every part of the 
 arch maybe attended to. Indeed the caution and mo- 
 deration of our builders have commonly beea fbcb, that 
 
 few
 
 C E N 
 
 Center, few defc..!^s have been allowed to fhew themfelves. Wl 
 • are but little acquainted with joints opening to the ex- 
 
 tent of two inches, and in futU a caie would probably 
 lift every ilone of the arch a^ain (b). We have not 
 employed trufled centerings lo much perhaps as we 
 ihould have done ; nor do we fee their advantage (fpeak- 
 ing as mere builders) over centres fupported all over, 
 and unchangeable in their form. Such centres mull 
 bend a little, and require loading on the middle to keep 
 them in fliape. Their compreliion and their elallicity, 
 are very troublelbme in the ilriking of the centres in 
 Mr Perronel's manner. The elallicity is indeed of ufe 
 when the centres are ftruck in the way now delcribed. 
 
 Theie obfervations on the management of the inter- 
 nal movements of a great arch will enable the reader to 
 appreciate all the merit of Mr Mylne's very ingenious 
 conftruilion. We proceed therefore to complete our 
 ilefcription. 
 
 The gradual enlargement of the bafe of the piers of 
 Blackfriars bridge enabled the architedl to place a feries 
 of five polls c, c, c, c, c, one on each flap of the pier ; 
 the ingenious contexture of which made it like one fo- 
 _, ^* , lid block of (lone (fee Arch, Supplement). Tliefe Itruts 
 fnjj gfj^jj. were gradually more and more oblique, till the outer 
 Vlylne's one formed an obtufe angle with tlie lowcil fide of the 
 nethod. interior polygon of the truls. On the top of thefe polls 
 was laid a floping seat or beam D of llout oak, the up- 
 per part of which was formed like a zig-zag Icarfing. 
 The polls were not perpendicular to the under fide of 
 the feat. The angles next the pier were fomewhat ob- 
 tufe. Short pieces of wood were placed between the 
 heads of the polls (but not mortifed into them), to pre- 
 vent them from flipping back. Each face of the fcarf 
 was covered with a thick and fmooth plate of copper. 
 The feet of the tnifs were mortifed into a iimilar piece 
 F, which may be called the sole of the trufs, having 
 its lower fide notched in the fame manner with the up- 
 per fide of D, and like it covered with copper. Ee- 
 tween thefe two lay the striking wedge L,, the faces 
 of which correfponded exadtly with the flant faces of 
 the feat and the fole. The wedge was fo placed, that 
 the correfponding faces touched each other for about 
 half of their length. A block of wood was put in at 
 the broad end or bafe of this wedge, to keep it from 
 flipping back during the laying the arch-llones. Its 
 outer end E was hound with iron, and had an iron bolt 
 feveral inches long driven into it. The head of this 
 bolt was broad enough to cover the whole wood of the 
 wedge within the iron ferule. 
 
 We prcfume that the reader, by this time, forefees 
 the ufe of this wedge. It is to be driven in between 
 the fole and the feat (having firil taken out the block 
 at the bafe of the wedge). As it advances into the 
 wider fpaces, the whole trufs mull defcend, and be freed 
 from the arch ; but it will require prodigious blows to 
 drive it back. Mr Mylne did not tliink fo, founding 
 
 [ 20J ] 
 
 C E N 
 
 his expeflation on what he faw in the launching of great Center, 
 ftiips, which Hide very eafily on a fiope of lo or 12 de- *— v— ^• 
 grees. He rather feared, that taking out the block 
 behind would allow the wedge to be pullied back at 
 once, fo that the defcent of the trufs would be too ra- 
 pid. However, to be certain of the operation, he had 
 prepared an abundant force in a very ingenious manner. 
 A heavy beam of oak, armed at the end with iron, was 
 lufpended from two points of the centre like a battering 
 ram, to be ufcd in the fame manner. Nothing could 
 be more fimple in its ftrufture, more powerful in its 
 operation, or more eafy in its management. Accord- 
 ingly the fuccefs was to his wifli. The wedge did not 
 flip back of itfelf ; and very moderate blows of the ram 
 drove it back with the greateR eafe. The whole ope- 
 ration was over in a very few minutes. The fpeftators 
 had fufpedled, that the fpace allowed for the re?efs of 
 the wedge was not fufficient for the fettlement of the 
 arch ; but the architeft truHed to the precautions he 
 had taken in its conllruftion. The reader, by turning'- 
 to the article Arch in this Supplement, will fee that 
 there was only the arch LY which could be expefted 
 to fettle : accordingly, the recefs of the wedge was 
 found to be much muie than was necelTary. However, 
 had this not been the cafe, it was only neceflary to take 
 out the pieces between the polls below the feat, and 
 then to drive back the heads of the flruts ; but this was 
 not needed (we believe) in any of the arches. We are 
 well allured that none of the arches funk an inch and a 
 half. The great arch of 100 feet fpan did not fink one 
 inch at the crown. It could hardly be perceived whe- 
 ther the arcli quitted the centering gradually or not, fo 
 imall had been the changes of fhape. 
 
 We have no hefitation in faying, that (if we except The'Vrcat 
 fomc wafte of great timber by uncommon joggling) thefnpcriority" 
 whole of this performance is the moll perfect of any"' 'f": "n- 
 that has come to our knowledge. We doubt not butjf '^f^"*^*^' 
 that feveral have equalled it, or may have excelled it j ^ 
 but we do not know of them : and we think that the 
 bringing forward fuch performances is no lefs fcrvicc- 
 able to the public, than it is honourable to the inventor. 
 Nor do we luppofe that any views of interefl can ht fo 
 powerful as to prevent ;ui ingenious architedt from com- 
 municating to the public iueh honourable fpttimens of 
 his own talenls. We lliould be iiappy to communicate 
 more of this kind ; for we confider it as a very import- 
 ant article of praftlcal mechanics, and think that it is 
 of confcquence to the nation that it fliould be very ge- 
 nerally underltood. In every corner of the country 
 bridges arc to be built — wc have everywhere good ma- 
 fins, v/ho are fully able to execute any prafticable pro- 
 je6t, but too little acquainted with principle to invent, . 
 or to accommodate even what they know to local cir- 
 cumftanccs, and are very apt to be duped by appear- 
 ances of ingenuity, or milled by erroneous notions of 
 the ilrains which are. excited. We profefs more fcience, 
 
 and 
 
 (b) The writer of this article can only fay, that, after much inquiry, he has no information of any arch being 
 received from the builder as fufficient that had fuifered half the charge of fliape mentioned by Mr Terrouct. 
 The arch of Dublin bridge, built by an excellent, but a very private, niafon, Mr Steeven, is 105 feet wide, with ■ 
 only 22 feet of rife. It was eretled (but not on a truffed centering) without changing one full inch in its ele- 
 vation ; and when the centering was removed, it funk only i|th inches, aud about half an inch ir.ote whec the 
 parapets were added and the bridge completely finifhed.
 
 C E E [20 
 
 ^ Cen tny and to treat the fubjeft with the alTiftance of accurate 
 * principles : But while we are certain that every cir- 
 cumftance is ful'ccptible of flie moll accurate determi- 
 nation, we mull acknowledge that we have by no means 
 attained an accurate knowledge of all the ftrains which 
 are produced and excited in a frame of carpentry, which 
 is fettling and changing its fiiape, even though it be not 
 very cumplicated ; far lefs are we pofTefied of a clear 
 view of wliat happens in a mafs of mafonry in fimilar 
 conditions. Therefore, though we fpeak with the flrong 
 belief of our being right, we fpeak with a fenfe of our 
 fallil.ility, and with great deference to the judgment of 
 eminent and experienced architedls and engineers. We 
 fhould . conlider their free and candid criticifms as the 
 highell favour ; and we even folicit them, with affuran- 
 ces of llianks, and that we will take fome opportunity, 
 before the clofe of this work, to acknowledge and cor- 
 reft our miilakes. We even prefume to hope, that the 
 libcral-mindtd arlift will be pleafed with this opportu- 
 nity which we give him of increaling the national (lock 
 of knowledge. Let mutual jealoufy and rivallhip reign 
 in the breafts, and prompt the exertions, of our reftlefs 
 neighbours on the continent— let them think that the 
 dignity of man confids In perpetual warfare, in which 
 every individual feels himfelf indebted only to liimtclf, 
 freed from all the fwect ti;s of domeftic partiality, of 
 fricndlhip, and of patriotic attachment. We hope that 
 thf hearts of Britons will long continue to be warmed 
 and forlifirdhv the thoughts of mutual affiilance, mu- 
 tual co-operation, mutual attachment, and a patriotic 
 preference of their countrymen to all other men. While 
 thefe fentiments are regulated by unfhaken honeily, by 
 candour, and by Chriltian charity, we fliall be fecurcd 
 from the errors of partial attachments, and yet enjoy all 
 the pleafures of unfophifticated nature. Families will 
 ftill be bound together by the affectionate ties of blood; 
 and the whole frame of Britifli fociety will be in har- 
 mony with the bonds which connefl the members of 
 each family, by their endlefs croffings and intermi.\ings. 
 In tin's ilalc, the (late of focial nature, the man of ta- 
 lents will not lock up all the fruits of his exertions in 
 his own brealt, but will feel a pleafure in imparting 
 them to a fociety that is dear to him, and on which he 
 depends for all his bell enjoyments. Nothing will hold 
 the good man back when this is in his power, but the 
 virtuous ufe which he can make of his fuperiority in 
 the difcharge of his own little circle of duties. This is 
 all that is required of true patriotifm ; and it is not too 
 much to be cxpefted from Britons, who feel a pleafure 
 in viewing their country as the great fchool of the arts, 
 under the patronage of a fovereign who has done more 
 for their improvement than all the other princes of Eu- 
 rope, and who (we are well affured) is now meditating 
 a plan which mult be highly gratifying to every emi- 
 nent profeffor of the aits. 
 
 _, 3^, The fubjeft which we have been confnlering is very 
 
 ■ie<a of this clofely connecled with the conllrutlion of wooden 
 article con- bridges. Thefe are not always conllruCted on the fole 
 nccftei with principles of equilibrium, by means of mutual abutment, 
 ft^a" fTh'^y 3''6 ftiff frames of carpentry, where, by a proper 
 wooden difpofition, beams are put into a Hate of extenfion, as 
 bridges. well as of compreiTion, fo as to Hand in place of folid 
 
 bodies as big as the fpaces which the beams enclofe ; 
 
 and thus we are enabled to couple two, three, or four 
 
 5 ^ 
 
 C E N 
 
 of thefe together, and fet them in abutment with each P'ttcr. 
 other like mighty arch-ftones. We fliall clofe this ar- ^""^ -* 
 tide, therefore, with two or three fpecimens ol wooden 
 bridges, difpofcd in a ieries of progrcllive compotltion, 
 fo as to ferve as a fort of introduction to the art in ge- 
 neral, and furnifii a principle which will enable the in- 
 telligent and cautious artifl to pufli it with confidence 
 as far as it can go. 
 
 The general problem is this. Suppofe that a bridge 
 is to be thrown over the fpace AB (lig. 9-), and that Plate 
 this is too wide for the fliength of the fize of timber -^^ "• 
 which is at our command ; how may this beam AB be 
 fupported with fufiicicnt effcft ? There are but two 
 ways in which the middle point C (where the greateit 
 drain is) can be fupported : i. It may be futpended by 
 two ropes, iron rods, or wooden ties, DC, liC, made 
 fad to two firm points, D, E, above it ; or it may rell on 
 the ridge of two rafters tlC, eC, which reft on two firm 
 points c/, e, below it 2. It may be fupported by con- 
 nefting it with a point fo fupported ; and this connec- 
 tion may be formed, either by fulpending it from this 
 point, or by a poll relh'ng on it. Thus it may hang, 
 by means of a rod or a king-poll FC, from the ridge F 
 of two rafters AF, BF ; or it may reft on the llrut Cf, 
 whofe lower extremity /"is carried by the ropes, rod*, 
 or wooden ties Af, B_/". 
 
 Whichfoever of thefe methods we employ, it follows, 
 from the principles of carpentry, that the fupport given 
 to the point C is fo m.uch the more powertul, as we 
 make the angle DCE, or JCe, or the equivalent angles 
 AFB, or A/B, more acute. 
 
 Each of thefe methods may be fuppofed equally 
 ftrong. Our choice will depend chiefly on the facility 
 of finding the proper points of fuppoit D, K, J, e ; ex- 
 cept in the fecond cafe, where we require no tixed points ,, 
 but A and B. The limple forms of the firft cafe re-Theufual 
 quire a great extent of figure. Very rarely can we fuf- ^nd limp. eft 
 
 pend it from points fituated as D and E. It is even ""^'^ "* ' ' 
 ■ 1 . 1 1 11 • r 1 1 11 1 conltruct- 
 
 ieldom that we nave depth enougti ot bank to allow the j^j [^^^^^ 
 
 fupport of the rafters dC, eC ; but we can always find bridges. 
 
 room for the fimple truls AFB. This therefore is the 
 
 moft uliialiy prattiled. 
 
 In the conllruclion, we muft follow the maxims and 
 direftions prelcribed in the article Carpentry of this 
 volume, and the article Roof of the Encyd. The beams 
 FA, FB muft be mortifed into AB, in the firmeft man- 
 ner, and there fecured with ftraps and bolts ; and the 
 middle mult hang by a ftrap attached to the king-poll 
 FC, <fr to the iron rod that is ufed for a king-poft. No 
 mortifing in the point C muft be employed ; it is unne- 
 ceflary, and it is hurtful, becaufe it weakens the beam, 
 and becaufe it lodges water, and foon decays by rot. 
 The bell praftice is not to fufpend the beam immedi- 
 ately by this ftrap, but to let it reft, as in fig. to. on a 
 beam C, which crolfes the bridge below, and has its 
 other end fupported in the fame manner by the other 
 trufs. 
 
 It is evident that the length of the king-poft has no 
 cfFeil on the fupport of C. We may therefore con- 
 tradl every thing, and preferve the fame ftrength of fup- 
 port, by finding two points a and b (fig. i i.) in the 
 banks, at a moderate diftance below A and B, and fet- 
 ting up the rafters a F, ^ F, and fufpending C from the 
 fhortened king-poft. In this conllruftion, when the 
 beam AB refts on a crofs bearer, as is drawn here, the 
 
 ftruts
 
 ihod 
 
 C E N [2 
 
 Center, ftrufs aT, iV are kept clear of it. No connexion be- 
 » tvveea them is necclTary, and it may be hurtful, by in- 
 ducing crofs llrains on both. It will, however, greatly 
 incrcafe ttie ftiffiufs of the whole. This conftrudlion 
 may fafcly be loaded with ten times the weight that AB 
 g can carry alone. 
 An i'm- Suppofe this done, and that the fcantling of AB is 
 
 provLmcnt too weak for carrying the weight which may be brought 
 ^l'^'^^ ""^'on the parts AC, CB. We may now trufs up each 
 half, as in fig 12. and then tlie wl\ole will form a hand- 
 fonie bridge, of the iimplcil conllrudtion poffible. The 
 interfeilions of the fecondary braces with thofe of the 
 main trufs will form a hand-rail of agreeable figure. 
 
 We are not confined to the employment of an entire 
 piece AB, nor to a redlilineal form. We may frame 
 the bridge as in fig. 13. and iu this form we difFuade 
 from allowing any conneftion with the middle points 
 of the main braces. This conilruction alfo may be fol- 
 lowed till each beam AC and CB is loaded to len 
 times what it can fafcly bear without the fecondary 
 trufling. 
 
 There is another way by which a bridge of one beam 
 may be fuppnrted beyond the power of the firft and 
 fimplell conftruftion. "This is reprefented in fig. 14. 
 and fig. ly. The trufs beam FG fliould occupy one- 
 third of AB. The advantage of this conl)ruftion is 
 very confiderable. The great elevation of the braces 
 (which is a principal element of the llrength) is prefer- 
 ved, and the braces are greatly (hortened. 
 
 This method may be pufhed ftill farther, as in fig. 
 16. 
 
 And all thefe methods may be combined, by joining 
 com- []^g conllructions of fig. 14. and fig. 15. with that of 
 
 37 
 IVnnther 
 sctbod. 
 
 38 
 rhtfc mC' 
 ho-is 
 'iiied, 
 
 fig. 16. 
 
 In all of them there is much room for the difplay of 
 
 Hcill, in the proper adjuftment of the fcantling of the 
 
 timber, and the obliquity of the braces to the lengths 
 
 of the different bearings. A very oblique ftrut, or a 
 
 {lender one, will fuffice for a fmall load, and may often 
 
 give an opportunity to increafe the general llrength ; 
 
 while the great timbers and upright fupports are refer- 
 
 ved for the main prcflui-es. Nothing will improve the 
 
 compofition fo much as reflefting progreffivelv. and in 
 
 the order of thefe examples, oii tlie whole. This alone 
 
 can preferve the great principle in its fimplicity and full 
 
 39 energy. 
 
 rhe e'e. Thefe conftrnftions are the elements of all that can 
 
 ncnts otaiijj^ done in the art of buildinij wooden bridsres, and are 
 
 hat can lie , „ , , r 1 • n , .-.i ■ 11 • 1, 
 
 [one in this ° "'^ round more or leis obvioully and diltnittly in all 
 
 attempts of this kind. We may affert, that the more 
 obvioufly they appear, the more perfedl the bridge will 
 be. It is allonifliing to what extent the principle may 
 be carried. We have feen a bridge of 42 feet fpan 
 formed of two oak truffes, the biggeil timber of which 
 did not exceed fix inches fquare, bearing with perfect 
 fteadinefs and fafety a waggon loaded with more than 
 two tons, drawn by four ftout horfes. It was framed 
 as fig. 16. nearly, with the addition of the dotted lines, 
 and was near thirty years old ; protefled, however, from 
 the weather by a wooden roof, as many bridges in Ger- 
 many are. 
 
 We recolleft another in the neighbourhood of Stet- 
 tin, which feemed conftrufted with great judgment and 
 fpirit. It had a carrriage road in the middle about 20 
 feet (we think) wide, and on each fide a foot-way about 
 
 rt. 
 
 07 ] C E N 
 
 five feet wide. The fpan was not lefs than 60 feet, »nd Center, 
 the greatcll fcantling did not appear to exceed 10 ' v ' 
 inches by 6. 
 
 This bridge confided of four truffes, two of which 
 formed the outfide of the bridge, and the other two 
 made the feparation between the carriage road and the 
 two foot ways. We noticed the conitrudlion of the 
 truffes very particularly, and found it fimilar to the lait, 
 . except in the middle liivifion of the upper trufs, which, 
 being very long, was double truflcd, as in fig. i 7. 
 
 The reader will find in that volume of Leupold's 
 Theatrum Machinarum, which he calls Tlx-atrum Ponltfi- 
 cum, many fpecimens of wooden bridges, which are vtry 
 frequent in the cliampain parts of Germany. They are 
 not, in general, models of mechanic art ; but the reflcft- 
 ing reader, who confiders them can-fully, will pick up 
 here and there fubordinate iiints, which are ingenious, 
 and may iometimes be uftful. 
 
 What we have now exhibited are not to be confider- 
 ei as models of conflruftion, but as elementary examples 
 and leffons, for leading the reader fyllematically into a 
 thorougli conception of the fubjeft. 
 
 We cannot quit the fubjeA without taking notice of A wonder- 
 a very wonderful bridge at Wittengen in Switzerland, I"' t"""lge 
 nightly defcribed by Mr Coxe {Travels, vol. I. i 32.) j" ^*""'^" 
 It is of a conftruftion more fimple ftill than the bridges ^° ' 
 we haive been defcribing. The fpan is 2^0 feet, and it 
 rifes only 2?. The ll<e"tch (fig. 18.) will make it fufii- 
 ciently intelligible. ABC is one of two great arches, 
 approaching to a catenarian lltape, built up of feven 
 courfes of folid logs of oak, in lengths of 1 2 or 14 feet, 
 and 16 inches or more in thicknefs. Thefe are all 
 picked of a natural fhape, fuited to the intended curve; 
 fo that the wood is now here cut acrofs the grain to trim 
 it into fhape. Thefe logs are laid above each other, fo 
 that their abutting joints are alternate, like thofe of a 
 brick wall ; and it is indeed a wooden wall, finiply 
 built up, by laying the pieces upon each other, -taking 
 care to make the abutting joints as clofe as poffible. 
 They are not faflened together by pins or bolts, or by 
 fcarfings of any kind. They are, however, held toge- 
 ther by iron flraps, which furround them, at the diflance 
 of five feet from each other, where they are fallened by 
 bolts and keys. 
 
 Thefe two arches having been erefted (by the help, 
 we prefume, of pillars, or a centering of feme kind\ and 
 well butted ngaluft the rock on each fide, were freed 
 from their fupports, and allowed to fettle. They are 
 fo placed, that the intended vod.i abc interfedis them 
 about the middle of their height. The roadway is fup- 
 ported by crofs joifls, which refl on a long horizontal 
 fummer beam. This is connefted with the arches on 
 each fide by uprights bolted into them. The whole is 
 covered with a roof, which projedls over 'the arches on 
 each fide to defeiid them from the weather. Three of' 
 the fpaces between thefe uprights havt ftruts or braces, 
 which give the upper work a fort of trufling in that 
 part. 
 
 This conftruftion is fimple and artlefs ; and appears, 
 by the attempt to trufs the ends, to be the performance 
 of a perfon ignorant of principle, who has taken the 
 whole notion from a ftone arch. It is, however, of a- 
 ftrength much more than adequate to any load that can 
 be laid on it. Mr Coxe fays, but does not explain how, 
 tLat it is fo contrived that any part of it can be repair- 
 ed.
 
 Ccter. 
 
 41 
 Another 
 ■AD North 
 J^merica. 
 
 C E N [ 
 
 er! independent of the reft. It was tlic laft work of one 
 ■* Ulricli Gnibciilinmm of TinTen, in the canton of Ap- 
 peiizel, a carpenter without education, hut celebrated 
 for fcveral works of the fattie kind ; particularly the 
 bridge over the Hhine at Schaflianfen, confillinc^ ol two 
 arches, one of 172 and the other of 193 feet fpan, botii 
 iiltini;on a fmall rock near the middle of the river. 
 
 Wliile writing this article, we got an account of a 
 wooden bridge, erefted in North America, in which 
 this fimple notion of Grubenhamm'a i? mightily impro- 
 ved. The fpan of the arch was faid to exceed 250 
 feet, and its rife exceedingly fmall. The defcnption 
 we got is very general, but fufficicnt, we think, to make 
 it perfectly intelligible. 
 
 In fig. 19. DD, EE, FF, are fuppofed to be three 
 beams of the arch. They confift of logs of timber of 
 fmall lengths, fiippofe -of ro or 12 feet, fuch as can be 
 found of a curvature fuited to its place Jn the arch with- 
 out trimming it acrofs the grain. Each beam is double, 
 confilHng of two logs applied to each other, fide to fide, 
 and br.ik'mg joint, as the workmen term it. They are 
 kept tojether bv wedges and keys driven through them 
 at (hort Intervals, as at K, L, &c. 
 
 The manner of joining and ftrongly binding the two 
 fide pieces of each beam is (hewn in fig. 20. The 
 niortife aic b and dc'io, which is cut in each half beam, 
 is confiderably longer on the outfide than on the infide, 
 where the two mortifes meet. Two keys, BB and 
 CC, are formed, each with a notch be d, or a to, on its 
 fide ; which notch tits one end of the mortife. The in- 
 ner fide of the key is ftraight, but fo formed, that when 
 both keys are in their places, they leave a fpace between 
 them wider at one end than the other. A wedge AA, 
 having the fame taper as the fpace juft; mentioned, is 
 put into it and driven hard. It is evident that this muil 
 hold the two logs firmly together. 
 
 This is a way of uniting timber not mentioned in 
 the article Carpentry ; and it has fome peculiarities 
 worthy of notice. In the firft place, it may be employ- 
 ed fo as to produce a very flrong lateral connedion, 
 and would then co-operate finely with the other artifi- 
 cial methods of fcarfing and tabling that we defcribed 
 in the article referred to. But it requires nice attention 
 to fome circumftances of conftrudtion to fecure this 
 effeiS. If the joints are accurately formed to each 
 other, as if the whole had been one piece divided by an 
 infinitely thin faw, this manner of joining will keep them 
 all in their places. But no driving of the wedge AA 
 will make them firmer, or caufe one piece to prefs hard 
 on the other. If the abutment of two parts of the half 
 beam is already clofe, it will remain fo ; but if open in 
 the fmallell degree, driving of the wedge will not make 
 it tighter. In this refpeft, therefore, it is not fo pro- 
 per as the forms defcribed in Carpentry. 
 
 In order that the method now defcribed may have 
 the efFeA of dra'Tvlng the halves of the beams together, 
 and of keeping them hard fqueezed on each other, the 
 joints muft be made fo as not to correfpond exaftly. 
 The prominent angle aio (fig- 21.), formed by the 
 ends of the two half mortifes, muft be made a little 
 more obtufe than the angle afo of the notch of the 
 key which this prominence is intended to fill up. More- 
 over, the oppofite fide et oi this key fhould not be 
 quite ftraight, but a very little convex. With thefe 
 precautions, it is eafy to fee that, by driving the wedge 
 
 oS ] C E N 
 
 AA, we caufe the notch afo to take hold, fivft at the Ctn»er 
 two points a and 0, and then, by continuing to drive ~~~\r— ■ 
 the wedge, the fides af, of, of the notch gradually 
 compiefs the wood of the half beams, and pefs liicm 
 on each other. By continuing to drive the wedge, the 
 mutual comprefFion of the key and the beam Ujueezes 
 all together, and tlie fpace afo i is completely filled uj). 
 We niay fee, from this procefs, that the mutual coni- 
 prcfiion and d-'awing together of the timber will bc 
 greatcr in proportion as we make the angle aio more 
 prominent, and its correfponding angle afo more deep ; 
 always taking care that the key (liall be thick enough 
 not to break in the narro«- part. 
 
 This adjuftment of the keys to the mortife is necef- 
 fary on another account. Suppofing the joints to fit 
 each other exaflly before driving the wedge, and that 
 the v\hale (brinks a little by drying — by this the angle 
 aio will become more prominent, and the angle afo 
 will become more (liallow ; the joint will open at a and 
 0, and the mutual comprefTure will be at an end. 
 
 We may alfo obferve, that this method will not give 
 any additional firmnefs to the abutments of the different 
 lengths employed to piece out the arch-beam; in which 
 refpeft it differs materially from the other modes of 
 joining timber. 
 
 Having fhewn how each beam is pieced together, we 
 muft now (hew how a number of them are united, fo 
 as to compofe an arch of any thicknefs. This is done 
 in the very fame way. The beams have other mortifes 
 worked out of their inner fides, half out of each half 
 ^of the beam. The ends of the mortifes are formed in 
 the fame way with thofe already defcribed. Long 
 keys BB, CC, (fig. 19.) are made to fit them properly, 
 the notches being placed fo as to keep the beams at a 
 proper diftance from each other. It is now plain that 
 driving in a long wedge AA will bind all together. 
 
 In this manner may an arch be extended to any fpan, 
 and made of any thicknefs of arching. The bridge 
 over Portfmouth river in North America was more 
 than 250 feet in length, and confifted of feveral parallel 
 arches of beams. The inventor (we think that his name 
 is Bludget) faid that he found the ftrength fo great, 
 that he could with perfedl confidence make one of four 
 times the fpan. 
 
 We admire the ingenuity of this conftruftion, and 
 think it very effeftual for bringing the timbers into firm 
 and uniform abutment ; but we imagine that it requires 
 equilibration, becaufe it is extremely flexible. There is 
 nothing to keep it from bending, by an inequality of 
 load, but the tranfverfe ftrength of the beams. The 
 keys and wedges can have very little power to prevent 
 this bending. The diftance between the beams will 
 alfo contribute little or nothing to the ftiffnefs ; nay, 
 we imagine that a great diftance between them will 
 make the frame more flexible. Could the beams be 
 placed fo near each other that they could be fomchow 
 joggled on each other, the whole would be ftiffer ; but 
 at prefent they will bend like the plates of a coach- 
 fpring. But nothing hinders us from adding diagonal 
 pieces to this conftruftlon, which will give it any de- 
 gree of ftiffnefs, and will enable it to bear any inequali- 
 ty of loading. When completed in this manner, we 
 imagine that it will be at leaft equal to any conftruc 
 tion that has yet been thought of. One advantage it 
 pofTciTes that is very precious : Any piece that fails 
 
 may
 
 ('K.NTiii'.S I'l. vi'i: xi\'.
 
 i'i..\ rio.N I'l \ 1 1 /M
 
 n.vvijr.s I'l, vir. . /Ml 
 
 V'i'«.:'. 
 
 llV. 11.
 
 C E N 
 
 [ 
 
 Center, may be taken out, and rcphced by nnotlier, without 
 ■—~-\ <iifturl)iiig tlic reil, and without the fmalk-ft rifle. On 
 
 the whole, wc think it a very vaUitible adJicion to Bri 
 tilh carpentry. The method here praiiifed, both for 
 joining the parts of one beam and for framing the dif- 
 ferent beams together, fuggeils the moft firm and h'ght 
 conftruAions for dome-roofs that can be conceived i 
 incomparably fuperior to any that have yet been ereft- 
 ed. The whole may be framed, without a nail or a 
 fpike, into one net like fhell that cannot even be pulled 
 in pieces. We may perhaps confider this in another ar- 
 tick ; at prefent we return to the confideratian of truff- 
 ed bridges. 
 BriHiies When the width of the rii'er exceeds what is thought 
 
 combined prafticable by a fingle trufs, we muft then combine, 
 by fini;ilc ^jther by fimple addition, or by compofition, different 
 bv comuo- '•'uT'^s together. We compofe a bridge by fimple ad- 
 fieion. dition when we make a frame of carpentry of an un- 
 
 changeable and proper fliape, to ferve as one of the 
 archftones of a bridge of mafoniy. This may eafily 
 be comprehended by looking at fig. 22. Each of the 
 frames A, B, C, D, mull be confidered as a feparate 
 body, and all are fupported by their mutual abutment. 
 The nature of the tiling is not changed, although we 
 fuppofe that the rails of the frame B, inflead of being 
 mortifed into an upright i' b', unconnefted with the 
 frame C, is mortifed into the upright c c Qi that frame, 
 the direction and intenfity of the mutual prelfures of 
 the two frames are the fame in both cafes ; accordingly 
 this is a very common form of fmall wooden bridges. 
 It is ufual, indeed, to put diagonal battens into each : 
 but we believe that this is more frequently done to 
 pleafe the eye than to produce an unalterable fhape of 
 each frame. 
 
 To an unfl<Ilful carpenter this bridge does not feem 
 effentially different from the centering of Mr Hupeau 
 for the bridge of Orleans ; and indeed, in many cafes, 
 St requires refleftion, and fometimes very minute reflec- 
 tion, to diftinguifh between a conflruftion which is only 
 an addition of frame to frame till the width be covered, 
 from a conflruflion where one frame works on the ad- 
 joining one tranfverfcly, puthing it in one part, and 
 Howtodif. <3'"<'wing it in another. The ready way for an unletter. 
 (inguifli ed artifl to form a juft notion of this point, is to exa- 
 
 hridges mine whether he may faw through the conneftincf piece 
 Formed ac- - - - - ■ • - . . o ^ 
 
 cording (o 
 
 l> b' from one end to the other, and make them two 
 
 t-hoj'. 
 
 fhefe iiffc- feparate fran>es. Whenever this cannot be done with- 
 rent me. out that part opening, it is a conflruftion by compofi- 
 tion. Some of the beams are on the ilretch ; and iron 
 ilraps, extending along both pieces, are neceffary for fe- 
 curing the joint. The bridge is no longer a piece of 
 matonry, but a performance of pure carpentry, depend- 
 ing on principles peculiar to that art. Equilibration is 
 •tieceffary in the firft conftruftion ; but, in the fecond, 
 any inequality of loading is made ineffectual for hurt- 
 ing the edifice, by n\eans of the (Iretch that is made to 
 operate on fome other piece. We are of opinion, 
 that this mofl fimple employment of the diftinguiffiing 
 principle of carpentry, by which the beams are made 
 to aft as ties, will give the moft perfeft conftruftion 
 of a wide bridge. One polygon alone fhould contain 
 the whole of the abutments ; and one other polygon 
 .*hould confill entirely of ties; and the beams which 
 form the radii, conneding the angks*of the two poly- 
 gons, complete the whole. By confining the attcn- 
 SufPL. Vol. I, Part I. 
 
 09 ] C E N 
 
 tion to thefe two fimple obj-fts, the abutments of th« Cemrr. 
 outer polygon, and the joints of the inner one, may l)c — -v— 
 formed in the motl fimple and efficient minner, without 
 any collateral connections and depcrtdenci-s, which di- 
 vide the attention, increafe the complication, and com- 
 monly produce unexpected and hurtful ftrains. It was 
 for this reafon that we have fo frequently recommended 
 the centering of the bridge of Orleans. Its office will 
 be completely performed by a trufs of the form of fig. 
 23. ; where the polygon ABCDEF, confifting of two 
 layers of beams (if one is not fufikient), contains the 
 whole abutments, and the other Ai^-^f F is nothing 
 but an iron rod. In this conflruftion, the obtufeiiefs 
 of the angles of the lower polygon is rather an advan- 
 tage. The braces G c , G </, which are wanted for trulT- 
 ing the middle of the outer beam;, will effectually fe- 
 cure the angles of the exterior polygon agalnft all rifle 
 of change. The reader mult perceive that we have The bed 
 now terminated in the conllruction of the Norman roof. • eneral 
 We indeed think it the beft general form, when fome'^"''" °^* 
 moderate dechvity is not an infuperable objedtfon. When ^^';j„e'* 
 this is the cafe, we recommend the general plan of the 
 centering of the bridge of Orleans.' We would make 
 the bridge (we fpeak of a great bridge) confill of four 
 truffes ; two to ferve as the outfides of the bridgfe, and 
 two inner truffes, feparating the carriage-way from the 
 foot-paths. The road fhould follow the courfe of the 
 lower polygon, and the main trufs fhould form the rails. 
 It miglit look flrange ; but we are here fpeaking of 
 ftrength; and evident, but not unwieldy, flrength, once 
 it becomes familiar, is the fureil fource of beauty in all 
 works of this kind. 
 
 Centre of Frinlon, is that point in the bafe of a 
 body on which it revolves; into which, if the whole 
 furface of the bafe, and the niafs of the body, were 
 collected, and made to revolve about the centre of the 
 bafe of the given body, the angular velocity dellroycd 
 by its friction would be equal to the angular velocity 
 deftroyed in the given body by its friclion in the fame 
 time. See Friction in this Supplement. 
 
 Centre of Gyration, is that point in which, if the 
 whole mafs be collefted, the fame angular velocity will 
 be generated in the fame time, by a given force acting 
 at any place, as in the body or fyftem itfelf. This point 
 differs from the centre of ofcillation, in as much as in 
 this latter cafe the motion of the body is produced by 
 the gravity of its own particles ; but, in tlie cafe of the 
 centre of gyration, the body is put in motion by fome 
 other force afting at one place only. 
 
 Centre of Cfcillalion, is that point in the axis or line 
 of fufpenfion of a vibrating body, or fyftem of bodies, 
 in which, if the whole matter or weight be collected, 
 the vibrations will flill be performed in the fame time, 
 and with the fame angular velocity, as before. Hence, 
 in a compound pendulum, its dillance from the point 
 of fufpenfion is equal to the length of a iunple pendu- 
 lum whofe ofoillations are ifochronal \\h\\ thofe of the 
 compound one. 
 
 Crntre of Preffure, of a fluid againft a plane, is that 
 point againil which a force being applied equal and 
 contrary to the whole prcflure, it will juft fuftain it, fo 
 as that the body prcffed on will not incline to either 
 fide. — This is the fame as the centre of percufllon, fup- 
 pofing the axis of motion to be at the interfeCtion of 
 this plane with the furface of the fluid ; and the centre 
 Dd of
 
 C H A [21 
 
 Ccntroba. of prefTure Upon a plant parallel to the liovizon, nr upon 
 '"° any plane where the preffiire is unifiiim, is the lame as 
 Chamhcr= 'he centre of pjravitv of that plane. 
 
 ., ^ ' CENTROB ARICO, the fame as centre of gravity. 
 
 CENTROBARIC Method, is a method of deter- 
 
 mining the quantity of a fiirface or folid, by means of 
 
 the generating line or plane and its centre of gravity. 
 
 The doctrine is chiefly comprifed in this theorem : 
 
 Every figure, whether fuperficial or folid, generated 
 by the motion of a line or plane, is equal to the pro- 
 dudl of the generating magnitude and the path of its 
 centre of gravity, or the line which its centre of gra- 
 vity defcribes. 
 
 CERUSE, or White-lead, is a fubftance fo much 
 ufed in painting, and for other purpofes, that n\imero.!S 
 modes have been employed for the preparation of it. 
 Of the mod common of thefe, a fuffioient account has 
 been given in the Encyclopedia (fee Cerusk, and the 
 fame word CHEMisTRy-/«</«j; but Lord Dundonald 
 has difcovered a more expeditious and facile method 
 than any of them, which becomes the more ufeful, 
 as the fubftance with which it is effeAed has been hi- 
 therto rejefted by the chemical world as a caput mor- 
 luum. 
 
 His lorddiip direds common lead to be reduced to a 
 calx, but not too fine, and to have a proportion of five- 
 fixth parts thereof, intimately mixed with muriat, or 
 folution of potafs. In this (late, he direfts it to be 
 frequently ftirred, in order to have the new furfaces of 
 the mixture expofed to the carbonic acid of atmofpheric 
 air ; as his lordlhip obferves, that the effeds of the car- 
 bonic acid on the alkali exilling in the prefent Hate of 
 the mixture is effentially neceflary, in order to effeft the 
 intended purpofe. In this ftate it is to be frequently 
 fprinkled with water, and, after the calx has been long 
 enough immerfed with the muriat- to be fufficiently o- 
 perated upon, the muriat is to be levigated by common 
 water from the calx, and to be concentrated by evapo- 
 ration, in order to be made ufe of at a future period 
 with other calx. The calx is to be afterwards ground, 
 levigated, and dried for utc. 
 
 For this difcovery, his lordftip obtained a patent on. 
 the iSth of Auguft 1797 ^ and the fuccefs which has 
 attended the former patents of this fcientific nobleman 
 leads us to conclude, that the prefent difcovery is entit- 
 led to the attention of the public. 
 
 CHAMBERS (Sir William), the celebrated archi- 
 tect, was defcended of the ancient family of Chalmers in 
 Scotland, barons of Tartas in France. His grandfather 
 fuffered confiderably in his fortune by fupplying Charles 
 XII. of Sweden with money, &c. which that monarch 
 repaid in bafe coin. Sir William's father refided feveral 
 years in Sweden to recover his claims ; and there Sir Wil- 
 liam was born, and, at eighteen years of age, appointed 
 fupercargo to the Swedifii Eall India company. From a 
 voyage which he made to China, he brought home the 
 Afiatic ftyle of ornament, in tents, temples, nvofques, and 
 pagodas. Thefe ornaments (through the interefl of Lord 
 Bute) he was enabled to apply in the gardens at Kcw. 
 Patronifed by the princefs dowager and the king, Mr 
 Chambers had much of the falhionable ijufinefs of the 
 day. Under Burke's reform, he was appointed furvey- 
 or general of the board of works. Somerfet-houfe was 
 worth to him atleaft L. 2000 a-year. His Chef d'awures 
 are his ftaircafes, particularly thofe at LordBefoorough's, 
 
 o ] C H A 
 
 Lord Gower's, and the Royal and Antiquari.iii Socie- Ch8nif<r, 
 tits. The terrace behind Somerfct-houfe is a bold ef- Cl-;u«acr» . 
 fort of conception. His dciigns for interior arrange- 
 ments were excellent. His Treatife on Civil Architec- 
 ture alone will immortalize his name. In private life. 
 Sir William was hofpitable, kind, and amiable. His fon 
 married Mifs Rodney ; Mr Cotton, Mr Innis, and Mr 
 Harward, married his beautiful daugiiters. Having 
 been abftcmious in his youth, Sir William's conllitution 
 did not begin to break till he was feventy years of age. 
 For the lall three years, he was kept alive by wine and 
 oxygenated air: and died on the 5th of March 179'). 
 His celebrity will be lalling in the works which he has 
 left ;and as he was equally fl-illed in the theory and 
 praflice of the arts which he profefFcd, his precepts are 
 as valuable as his works. At his death, he was fellow 
 of the Royal and Antiquarian Societies, trealurer of 
 the Royal Academy, furveyor-general of the board of 
 works, and knight of the Swediih order of the Polar 
 Star. 
 
 CHAMFER, or Chamferet, an ornament in ar- 
 chitefture, confifting of half a Icotia ; being a kind of 
 fmall furrow or gutter on a column. 
 
 Universal CHARACTERS, could they be in- 
 troduced, would contribute fo much to the diffufion of 
 ufeful knowledge, that every attempt to make fuch a 
 fcheme fimple and prafticable is at leaft intitled to no- 
 tice. Accordingly, in the Eniyclopid'ia Brltannica, uu- 
 der the word Character, a fhort account is given of 
 the principal plans of univerfal characters which had 
 then fallen under our obfervation ; but fince that article 
 was publilhed, a new method of writing, by which the 
 various nations of the earth may communicate their 
 fentiments to each other, has been propofed by Thonuu 
 Nortbmore, Efq; of Queen-flreet, Mayfair. It bears 
 fome refemblance to that which we have given from the 
 Journal L.keraire, i 720, but it is not the fame ; and of 
 the two, Mr Northmore's is perhaps the mofl ingenious. 
 The ground-work of the fuperftrutlure differs not in- 
 deed from that of the journalift, being this in both,. 
 " That if the fame numerical _y?^.'(rf be made to repre- 
 fent the fame 'it'ortl in the various languages upon earth, 
 an univerfal charafter is immediately obtained." The 
 only objection which the author or his friends faw to 
 fuch a plan, originates in the diveriity of idioms ; but, 
 as he truly obferves, every fchoolboy has this difficulty 
 to encounter es often as he conflrues Terence. 
 
 Such then was Mr Northmore's original plan : but he 
 foon perceived that it was capable of confiderable im- 
 provement; for, inflead of ufing a figure for every word, 
 it will be neceffary to apply one only to every ufeful 
 word ; and we all know how few words are abfohitely 
 neceffary to the communication of our thoughts. Even, 
 thefe may be much abbreviated by the adoption of cer-^ 
 tain uniform fixed figns (not amounting to above 20), 
 for the various cafes, numbers, genders, degrees of com- 
 parifon, of nouns, tenfes, and moods of verbs, &c. All 
 words of negation, too, may be expreffed by a prefixed 
 fign. A few inftances will bed explain the author's 
 meaning. 
 
 Suppofe the number 5 to reprefent the wordy^*'. 
 
 6 — — a man, 
 
 7 — — . happy, 
 
 8 -^ — never, 
 
 9 - _ / 
 
 ■ " I
 
 C H A [2 
 
 Cliarafltri . «( I would then (fays he) expi<efs tlic tcnfes, genders, 
 ' cafes, &c. in all languages, in fomc fuch uniform manner 
 as following ; 
 
 (0 
 
 
 = 
 
 prefeni tenfe. 
 
 — 
 
 fee, 
 
 (2) 
 
 
 = 
 
 perfca It-nfe, 
 
 — 
 
 faw. 
 
 (3) 
 
 
 = 
 
 perfcH participle. 
 
 — 
 
 feen, 
 
 (4) 
 
 3: 
 
 = 
 
 pri-fen! participle, 
 
 — 
 
 feeing, 
 
 (5) 
 
 
 = 
 
 future, — 
 
 — 
 
 will fee. 
 
 (6) 
 
 
 = 
 
 fuhfluiitive. 
 
 — 
 
 fight. 
 
 (7) 
 
 
 = 
 
 pcrfonal fiihjlantive, 
 
 — 
 
 fpeftator, 
 
 (8) 
 
 "6 
 
 = 
 
 twmiiialive cafe. 
 
 — 
 
 a man, 
 
 (9) 
 
 6 
 
 = 
 
 genitive, — 
 
 — 
 
 of a man. 
 
 (.0) 
 
 6' 
 
 = 
 
 ilutive, — 
 
 — 
 
 to a man, 
 
 (n) 
 
 "? 
 
 = 
 
 feminine, — 
 
 — 
 
 a woman. 
 
 (iz) + 6 
 
 = 
 
 plural, — 
 
 ■— 
 
 men, 
 
 (13) 
 
 7 
 
 = 
 
 poftlive, — 
 
 — 
 
 happy, 
 
 (H) 
 
 A 
 
 7 
 
 = 
 
 comparative, 
 
 — 
 
 happier, 
 
 (15) 
 
 7 
 
 = 
 
 fuperlative. 
 
 — 
 
 happieft, 
 
 
 ^ 
 
 := 
 
 as above. No. 6. 
 
 — 
 
 happinefi. 
 
 (16)- 
 
 -7 
 
 = 
 
 negation, — 
 
 — 
 
 unhappy. 
 
 " From the above fpecimen, I fliould find no difficul- 
 ty in comprehending the following fentence, though 
 it were written in the language of the Hottentots : 
 
 9, 8, .f, — 7, 6. I never faw a more unhappy luoman. 
 
 " Thofe languages which do not ufe the pronoun 
 prefixed to the verb, as the Greek and Roman, &c. 
 may apply it, in a fmall charafter, fimply to denominate 
 the perfon ; thus, inllead of 9, 8, .5, I never faiu ; 
 they may write, 8, p.5, which will fignify that the 
 verb is in the firlt perfon, and will ftill have the fame 
 meaning." 
 
 Our author feems confident that, according to this 
 fcheme of an unlverfal charafler, about 20 figns, and 
 lefs than io,OO0 chnfen words (fynonyms being fet a- 
 fide), would anfwer all the ends propofed ; and that fo- 
 reigners, by referring to their numerical diftionary, 
 would eafily comprehend each other. He proceeds next 
 Jo (hew how appropriate founds may be given to his 
 
 II ] CHE 
 
 figns, and an univcrfal living language formed from the Chars<aer» 
 univcrfal iharnHers. || _ 
 
 To attain this end, he propofes to diftingulfh the ten ■^'""""; ,, 
 numerals by ten monofyllabic names of cafy prcmonncia- ' 
 tion, and fuch as may run without diflicuky into ore 
 another. To illuftrate his fcheme, however, he calls 
 them, for the prefcnt, by their common Englidi names ; 
 but would pronounce each number made ufe of by ut- 
 tering feparately its component parts, after the manner 
 of accountants. Thus let the number 694? reprefent 
 the word horf, he m oidd not, in the univerfal language, 
 call a liorfej7.v thoufand nine hundred and forty-three, but 
 fix, nine, four, three, and fo on for all tlie words of a 
 fentence, making the proper flop at the end of each. 
 In the fame manner, a diftinft appellation muft be ap- 
 propriated to each of the prefixed figns, to be pronoun, 
 ced immediately after the numeral to which it is an ap. 
 pendage. Thus if */a be the appellation or the fign of 
 the plural number,/*, nine, four, three, plu will be horfes. 
 
 " Thus (fays our author), I hope it is evident that 
 about 30 or 40 diftinft fyllables are fufficient for the 
 above purpofe ; but 1 am much miftaken if eleven only 
 will not anfwer the fame end. This is to be done by 
 fubftituting the firft 20 or 30 numerals for the figns. 
 and faying, as in algebra, that a term is in the power of 
 fuch a number, which may be expreflcd by the 'fimple 
 word under. Ek. gr. Let 6943 reprefent the word 
 horfe ; and fuppofe four to be the fign of the plural 
 number, I would write the word thus, ^/jy ; and pro- 
 nounce it, fix, nine, four, three, in the power of or under 
 four. By thefe means eleven diftinft appellations would 
 be fufficient, and time and ufe would much abbreviate 
 the pronunciation." 
 
 To refufe the praife of ingenuity to this contrivance 
 for an univerfal language would be very unjuft ; but 
 elocution in this manner would be fo very tedious, that 
 furely the author himfelf, when he thinks more coolly 
 on the fubjett, will perceive, that in the living fpeech 
 its defefts would more than balance its advantages. A 
 pangraph, as he calls his univerfal charadler, would in- 
 deed be ufeful, and is certainly praftieable ; a panleg 
 (if we may form fuch a word) would not be very ufeful, 
 unlefs it were much more perfeft than it could be made 
 according to the plan before us. 
 
 CHAUSETRAPPES. _ See Ctotf's Feet, Encycl. 
 
 CHEMIN DEs RoNDs, in fortification, the way of 
 the rounds, or a fpace between the rampart and the low 
 parapet under it, for the rounds -to go about it. 
 
 Dda 
 
 CHEMISTRY,
 
 [ 212 ] 
 
 CHEMISTRY, 
 
 DtfiuitioD. TS a fcience, the obji-ft of which is to afccrtaln the 
 ■^ ingredients that enter into the compofition of bodies, 
 to examine the nature of thefe ingredients, the manner 
 in which they ton'.bine, and the properties refulting 
 liom tlieir combination. 
 
 As an art, it has been in fome meafure coeval with 
 the hi.ma:i race ; for many of the moft important 
 brandies of manufattures could not have been condudi- 
 ed without at lead fume knowledge of chemical combi- 
 nalions. As a fcience, it can hardly be dated farther 
 back than the middle of the 17th century; but fince 
 that time it has advanced with a rapidity altogether un- 
 precedented in the annals of philofophy. Newton laid 
 its foundation ; and fince his days an almofl incredible 
 number of the moft diftinguifhed names in Europe have 
 enlllled under its banners. So rapid has this progress 
 been, that though the article Chemistry in the Ency- 
 clopsdiii Britannka was written only about ten years 
 ago, the language and reafoning of chemiftry have been 
 fo greatly improved, and the number of fafts have ac- 
 cumulated fo much, that we find ourfelves under the 
 ncceflity of tracing over again the very elements of the 
 J fcience. 
 Importance Indeed, if we confider the importance of chemiftry, 
 ofchemif- vre ihall not be fo much furprifed at the ardour with 
 "^y* which it has been cultivated. As a fcience, it is inti- 
 
 mately conne&ed with all the phenomena of nature ; 
 the caufes of rain, Inow, hail, dew, wind, earthquakes: 
 even the changes of the feafons can never be explored 
 with any chance of fuccefs while we are ignorant of 
 chemiftry ; and the vegetation of plants, and fome of 
 the moft important funclions of arimals, have received 
 all their illuftration from the fame fource. No ftudy 
 can give us more exalted ideas of the wifdora and good- 
 nefs of the Great Firft Caufe than this, which Ihews us 
 everywhere the moft aftoniftiiiig effefts produced by 
 the moft fimple though adequate means, and dii- 
 plays to our view the great care which has everywhere 
 been taken to fecure the comfort and happinefs of every 
 living creature. As an art, it is intimately connected 
 with all our manufaftures : The glafs-blower, the pot- 
 ter, the fmlth, and every other worker in metals, the 
 tanner, the foap-maker, the dyer, the bleacher, are reaU 
 
 ly praftical chemifts ; and the moft eflentlal improve- 
 ments have been introduced into all thefe arts by the 
 progrefs which chemiftry has made as a fcience. Agri- 
 culture can only be improved rationally and certainly 
 by calling in the afliftance of chemiftry ; and the ad- 
 vantages which medicine has derived from the fame 
 fource are too obvious to be pointed out. 3 
 
 It is evident from the definition of chemiftry that it Arrange- 
 muft confift in a hlftory of the fimple fubftances which """'• 
 enter into the compofition of bodies, in an inveftlgation 
 of the manner in which thefe fubftances combine, and 
 in a dcfcrlption of the properties of the compounds 
 which they form. And this is the arrangement which 
 we mean to purfue ; referving to ourfelves, however, the 
 liberty of deviating a little from it, whenever it may 
 appear neceflary for the fake of perfpicuity. All our 
 claftlficatlons are in faft artificial; nature does not know/ 
 them, and will not fubmit to them. They are ufeful, 
 however, as they enable us to learn a fcience fooner, and 
 to remember it better ; but if we m.ean to derive thefe 
 advantages from them, we muft renounce a rigid adhe- 
 rence to arbitrary definitions, which nature difclaims. 
 
 We ftiall begin by an account of the fimpleft bodieSj 
 and proceed gradually to thofe which are more com- 
 pound. Tiy Jimpk bodies, we do not mean what the an- 
 cient philofophers called the elements of bodies, but mere<- 
 ly fubftances which have not yet been decompounded. 
 Very poflibly the bodies which we reckon fimple may 
 be real compounds ; but till this has attually been pro- 
 ved, we have no right to fuppofe it. Were we acquaint* 
 ed with all the elements of bodies, and with all the 
 combinations of which thele elements are capable, the 
 fcience of chemiftry would be as perfedl as poffible ; but 
 at prefent this is very far from being the cafe. 
 
 We fliall divide this article into four parts. Thejirft 
 part ftiall treat of thole bodies which are at prefent con- 
 fidered as liniple ; the feeotid, of thofe bodies which are 
 formed by the union of two fimple bodies, and which, 
 for want of a lietter word we ftiall call compound bodies ; . 
 the third, of thofe bodies which are formed by the union 
 of two compound bodies ; and the fourth, of bodies fuch 
 as they are prefented to us by nature in the mineral, vci- 
 getable, and animal kingdoms. 
 
 Part I. Of SIMPLE BODIES. 
 
 Claffesof A LL the bodies which are at prefent reckoned fim- 
 fimple bo- X*- pie, becaufe thty liave never been decompounded. 
 
 dies. 
 
 may be redaced into fix claftcs. 
 
 I. Oxygen, 4. Earths, 
 
 2- Simple combuftibles, 5. Caloric, 
 
 3. Metals, 6. Light. 
 
 Thefe ftiall form the fubjefts of the fix following 
 chapters. 
 
 Chap. I. 0/" Oxygen. 
 
 Pla'e Take a quantity of nitre, or faltpetre, as it is alfo 
 
 XVIII. called, and put it into a gun-barrel A (fig. I.), the 
 
 touch-hole of which has been previoudy clofed up with Method of 
 metal. This barrel is to be bent in fuch a manner, P'''"^'"''"S 
 that while the clofe end, in which the nitre lies, is put°*''^'"' 
 into the fire E, the open end may be plunged below the 
 furface of the water, with which the veflel B is filled. 
 At the fame time, the glafs jar D, previoufly filled with 
 water, is placed on the fupport C, lying at the bottom 
 of the velfel of water B, fo as to be exaftly over the 
 open end of the gun-barrel A. As foon as the nitre 
 becomes hot, it emits a quantity of air, which ifluing 
 from the end of the gun-barrel, afcends to the top of 
 the glafs jar D, and gradually difplaces all the water. 
 The glafs jar D then appears to be ompty, but is in faft 
 filled with air. It may then be removed in the follow- 
 ing
 
 Parti. CHEMISTRY. 213 
 
 Oxvjjen. ing manner r SL'Jc it avray n little from the giin-barrel nnon air. Like it too, it is elaftlc, and capable of in- Oxygfn. 
 
 ' V ■' and the fiipport, nnd then dipping any flat difli into the definite expanfion and comprcfTioii. ' >- 
 
 P water below it, raife it on it, and bear it away. The 2. If a lighted taper be let down into ajar of oxgen <;j JJ , 
 
 difh muft be allowed to retain a quantity of water in it, gas, it burns with fiich fpltndor that the eye can fearcc-flamc 
 
 (fee fig. 2.) Another jar may then be filled with air ly bear the glare of light, and at the fume time time pio- 
 
 in the fame manner ; and this procefs may be continued duces a much greater heat than when burning in com- 
 
 cither till the nitre ceafcs to give out air, or till as many mon air. It is well known that a candle put into a well 
 
 jarfuls have been obtained as are required. This me- clofed jar, filled with common air, is extinguifhed in a 
 
 thoil of obtaining and confining air was firil invented few feconds. This is the cafe alfo with a candle enclo- 
 
 bv Dr Mayow, and afterwards much improved by Dr fed in oxygen gas ; but it burns much longer in an equal 
 
 Hales. All the airs obtained by this or any other quantity of that gas than of conuiion air. ic 
 
 r procefs, or, to fpeak more properly, all the airs differ- 3. It was proved long ago by Boyle, that animals can- And life, 
 
 ing from the air of the atmofphere, have, in order to di- not live without air, and by Mayow that they cannot 
 
 ftinguifli them from it, been called gafis, and this name breathe the fame air for any length of time without fuf- 
 
 ^ we fhall afterwards employ. focation. Dr Prieftley and fcvcral other philofophers 
 
 SIfcovered 1'he gas which we have obtained by the above pro- have fhewn us, that animals live much longer in the 
 
 by f ricftlcy cefs was difcovered by Dr Prieftley on the irtof Au- fame quantity of oxygen gas than of common air. 
 
 »ndScheele,gu(l 1774, and called by him dephlo_(ifltcated air. Mr Count Morozzo placed a number of fparrows, one after 
 Scheele of Sweden difcovered it in 1775, without any 
 
 another, in a glafs bell filled with common air, and in- 
 verted over water. h. M. 
 
 The firft fparrow lived - - 30 
 
 The fecond - • - - 03 
 
 The third ....01 
 
 He filled the fame glafs with oxygen gas, and re- 
 peated the experiment. 
 
 The firft fparrow lived 
 
 The fecond 
 
 The third 
 
 The fourth 
 
 The fifth 
 
 The fixth 
 
 The feventh 
 The eighth 
 The ninth 
 
 The tenth 
 
 H. 
 
 M. 
 
 J 
 
 23 
 
 2 
 
 10 
 
 I 
 
 30 
 
 I 
 
 10 
 
 
 
 30 
 
 
 
 47 
 
 
 
 27 
 
 
 
 .^0 
 
 
 
 22 
 
 
 
 21 
 
 previous knowledge of what Dr Prieftley had done : he 
 
 gave it the name of empyreal air. Condorcet, fo con- 
 
 fpicuous during the French revolution, gave it firft the 
 
 name of -uiial air ; and Mr Lavoifier afterwards called 
 
 it oxygen gas ; a name which is now generally received, 
 
 and which we fhall adopt. 
 
 Oxygen gas may be obtained likewife by the follow- 
 ing procefs : 
 
 D (in fig. 3.) reprefents a wooden trovigh, the infide 
 
 of which is lined with lead or tinned copper. AB is a 
 
 flielf running along the infide of it, about three inches 
 
 from the top. C is the cavity of the trough, which 
 
 ought to be a foot deep. It is to be filled with water 
 
 at leaft an inch above the fhelf AB. In the body of 
 the trough, which may be called the ciftern, the jars 
 deftined to hold gas are to be filled with water, and then 
 to be lifted, and placed inverted upon the (lielf at B, He then put in two together ; the one died in 20 mi- 
 with their edges a little over it. This trough, which was nutes, but the other lived an hour longer. rr 
 
 invented by Dr Prieftley, has been called by the French 4. Atmofpherical air contains abuut 27 parts in the^''''^'' '•"' 
 
 chemifts iht pneumato-chcmicnl, or fimpiy ^«^ama/;V appa- hundred of oxygen gas. This was firft dilcovered by ^.'^ a'uw. 
 ratus, and is extremely ufeful in all experiments in which Sciiecle. It has been proved by a great number cf ex- 
 gafes are concerned. Into the glafs veftll E put a quan- periments, that no fubftance will burn in common air 
 tity of the black oxide (a) of manganefe in powder, and previoufly deprived of all the oxygen gas which it coi\- 
 jjour over it as much of that liquid which in commerce tained ; but combuftibles burn with great fplendor in 
 is called oil of vitriol, and in chemiftry fulphuric acid, as oxygen gas, or in other gafes to which oxygen cfas has 
 will lomewhat more than cover it. Then infert into been added. Oxygen gas- then is abfolutely nectlTary 
 the mouth of the velTel llie glafs tube F, fo clofely that for combuftion. 
 
 no air can efcape except through the tube. This may 5. It has !)een proved alfo, by many experiments, that 
 
 be done by covering the joining with a parte m;ide of no breathing animal can live fur a moment in any air or ' 
 wheat-flour and water, or any other /u/c, as fubftances gas which doe;; not contain oxygen mixed with it. Oxy- 
 iifed for fimilar purpofes are called. The end of the gen gas then is abfolutely neceffary for refpiration. 
 tube C is then to be plunged into the pneumatic appa- 6. When fubftances are burnt in oxygen gas, or iri , 
 
 ratus D, and the jar G, previoufly filled with water, to any other gas containing oxygen, if the air be examined 
 be placed over it on the llielf. The whole apparatus be- after the combuftion, a great pat-t cf the oxygen will he 
 ing fixed in that fituation, the glafs veffel E is to be found to have difappeared. If charcoal, for inftance, 
 heated by means of a lamp or a candle. A great quan- be burnt in oxygen gas, there will be found, inilcad of 
 tity of oxygen gas rulhes along the tub F, and fills the part of the oxygen, another very dift'erent gas, known by- 
 jar G. As foon as the jar is filled, it may be Aid to an- the name of carbonic acid gas. Exaftly tlie fame thini'- 
 other part of the flielf, and other jars fubftituted in its takes place when air is refpired by animals ; part of the 
 place, till as much gas has been obtained as is wanted. oxygen gas difappears, and its place is occupied bv fub- 
 I. Oxygen gas is colourlefs, and invifible like com- ftances pofTefTed of very dill'ereiit properties. Oxygen 
 
 gas 
 
 (a) This fubflance fhall be afterwards defcribed. 
 ufe with bleachers and feveral other manufafturers. 
 
 It is now very well known in En'tai.n, as it is in comm.on
 
 CHEMISTRY. 
 
 Part h 
 
 la 
 Its f)<ecific 
 jjravity. 
 • Oil P/jIc. 
 gj/loitf fed . 
 
 *3 
 pluned. 
 
 gas then undergoes feme change during combuftion, as 
 well as the bodies which liave been burnt ; and the fame 
 obfer\':iiion apphcs alfo to relpiration (b). 
 
 7. The fpccific gravitj- of oxygen gas, as determined 
 by Mr Kirvvan *, is 0,001^5, that of water being 
 
 ■. i,c03O, as is always the cafe when fpecific gravity in 
 '•mentioned abfohitcly. It is therefore 740 times hghter 
 tlian the fame bulk of water. Its weight to atmofphe- 
 rical nir i-. as ( 103 to loco : 116 cubic inches of oxy- 
 gen gas weigh ,;9,oj grains troy, 116 cubic inches of 
 common air, ?J,38 grains. 
 
 8. Oxygen is capable of combining with a great num- 
 ber of bodies, and forming compounds. As the com- 
 bination of bodies is of the utmolt importance in che- 
 miltry, before proceeding farther we (hall attempt to 
 explain it. When common fait is thrown into a veffel 
 of pure water, it melts, and very foon fpreads itfelf 
 through the whole of the liquid, as any one may con- 
 vince himfelf by the talle. In this cafe the fait is com- 
 bined with the water, and cannot afterwards be fepara- 
 ted by filtration or any other method merely mechani- 
 cal. It may, however, by a very fimple procefs : Pour 
 into tha folution a quantity of fpiiit of wine, and the 
 whole of the fait inlfantly falls to the bottom. 
 
 Why did the fait diffolve in water, and why did it 
 fall to the bottom on pouring in fpii it of wine ? Thefe 
 queilions were full anfwered by Sir Ifaac Newton. 
 There is a certain altiaftion between the particles of 
 common fait and thofe of water, which caufes them to 
 unite tO'Tcthcr whenever they are prefented to one ano- 
 ther. Tlicre is an attraftion alfo between the particles 
 -of water and of fpirit of wine, which equally dilpofes 
 them to unite, and this attraftion is greater than that 
 between the water and fait ; the water therefore leaves 
 the fait to unite with the fpiiit of wine, and the lalt be- 
 ing now unfupported, falls to the ground by its gravi- 
 ty. This power, which dilpofes the particles of diffe- 
 rent bodies to unite, was called by Newton altniflion, 
 by Bergman, eL-aive allradion, and by many of the Ger- 
 man and French chemiifs, affinity; and this laft term we 
 fliall employ, bccaufe the other two are rather general. 
 All fubftances which are capable of combining together 
 are faid to have an affinily for (c) each other: thofe 
 fubftances, on the contrary, which do not unite, are 
 faid to have no ajjlmty for each other. Thus there is 
 no affinity between water and oil. It appears from the 
 iuftance of the common fait and fpirit of wine, that lub- 
 flances differ in the degree of their affinity for other 
 fubftances, fmce the fpirit of wine difplaced the fait and 
 
 united with the water. Spirit of wine therefore has a Oxygen, 
 llronger affinity for water than common fait has. t— y— j 
 
 In 1719 Geoffroi invented a method of reprefenting 
 the different degrees of aflinities in tables, which he 
 called taUes of ajfinlly. llis method conlilled in pla- 
 cin<T the fubllances whofe affinities were to be afcertain- 
 ed at the top of a column, and the iubftances with which 
 it united below it, each in the order of its affinity ; the 
 fubftance whicii had the flrongeft affinity next it, and 
 that which had the weakell fartheft diflant, and fo of 
 the relL According to this metliod, the affinity of 
 water for fpirit of wine and common fait would be 
 marked as follows : 
 
 Water, 
 
 Spirit of wine, 
 
 C'oniinon fait. 
 This method Ims been univerfally adopted, and has con- 
 tributed very much to the rapid progrefs of che- 
 miftry. 14 
 
 We fliall proceed therefore to give a table of the af- Affinities of 
 finities 01 oxygen. ■"■ 
 
 Oxygen, 
 
 Carbon, 
 
 Zinc, 
 
 Iron, 
 
 Manganefe, 
 
 Hydrogen, 
 
 Azot, 
 
 Sulphur, 
 
 Phofphorus, 
 
 Cobalt, 
 
 Nickel, 
 
 Lead, 
 
 Tin, 
 
 Phofphorous acid, 
 
 Copper, 
 
 Bifmuth, 
 
 Antimony, 
 
 Mercury, 
 
 Silver, 
 
 Arfenic, 
 
 Sulphurous acid, 
 
 Oil, 
 
 Nitrous gas. 
 
 Gold, 
 
 White oxide of arfenic, 
 
 Muriatic acid. 
 
 Oxide of tin, 
 
 White 
 
 (b) Mayowhad in the laft. century made confiderable progrefs towards the difcovery of oxygen gas. He knew 
 that only a part of the air fupported combuftion : This part he ca]led fart icuU igneo-acrejr. He knew that this part 
 was contained in nitre: " Pars nitr! acrea nihil aliud quam particulse ejus igneo-aerex eft." He adds, " At non eft 
 eftimandum pabulum igneo-aereum ipfum aerem effe, fed tantum partem ejus majus adlivam fubtilemque. Quippe 
 lucerna vitro inclufa expirat cum tamen copia aeris fatis ampla in eodem continetur." He knew alfo that it was 
 this part of the air which was ufeful in refplration. After mentioning feveral experiments to prove this, he adds, 
 " Ex didlis certo conltat animalia refpirando particulas quafdam vitales eafque elaiticas ab aere haurire." See his 
 TraSatus quinque Medico-Phyfid, p. 12. and 106. — He knew alfo that this part of the air was neceffary to com- 
 buftion : " Et tamen certo conftat, particulas nitro-aereas non minus quam fulphureas ad ignem conflandum ne- 
 ceft'areas effe." Ibid, p. 26. 
 
 (c) We are not certain that the phrafe affinity for is warranted by claflical authority ; we have ventured, 
 however, to ufe it, becaufe, as the word ajiniiy in this article fignifies a fpecies of attraftion, we thought it would 
 be more perfpicuous to put after it the p»repofition/o/-, which ufually follows the word attraSion, than lo or vjitli, 
 which come after ajjinity when ufed in its ordinary acceptation.
 
 Part r. 
 
 Sulphvir, 
 
 CHEMISTRY. 
 
 15 
 
 Five fimple 
 
 coni!iufti- 
 
 blcs. 
 
 • ri:„y. 
 
 lib.xxnv, 
 c. ij. 
 
 16 
 Propcrries 
 of fulphiir. 
 
 f Fourcroy, 
 
 % Dr Bhci. 
 
 17 
 Flower<; of 
 (ulfhur. 
 
 i Tourcroy. 
 
 iS 
 iulphur ca. 
 able of 
 ryftalli- 
 ing. 
 
 White oxide of load ? 
 Nitrous acid, 
 
 White oxide of manganefe. 
 Water. 
 The reafon of this order will appear when we treat 
 cf thcfc various fubllances. 
 
 Chap. If. 0/"Simple Combustible Bodies. 
 
 By comhuJliUes, we mean fubftances capable of com- 
 buftion ; and by Jimple cnmhiijllhlts, bodits ot that na- 
 ture wliich have not yet been decompounded. Thefe 
 are onl/ five in number, Sulphur, Phosphorus, 
 Cariion, Hvdrogkn, and Azor. Were we to adhere 
 Itriclly to our delinltion indeed, we Ihonld add all the 
 metils ; for they are alfo comhuftible, and have not yet 
 been decompounded ; But for the rcafons formerly 
 given, we ihidl venture to deviate a little from llricl lo- 
 gic, and conlider them afterwards as a diltincl clafa of 
 I'ublUnces. 
 
 Sect. I. Of Sulphur. 
 
 Sulphur, diftinguilhed alfo in Englidi by the name 
 of brimjlone., was known in the earlitil ages. As it is 
 found native in many parts of the world, it could not 
 fail very foon to attraft the attention of mankind. It 
 was ufed by the ancients in medicine, and its fumes were 
 employed in bleaching wool*. 
 
 Sulphur is a hard brittle fubftance, commonly of a 
 yellow colour, without any fmell, and of a weak though 
 perceptible tafte. 
 
 It is a non-condu6tor of eleftricity, and of courfe 
 becomes eleftric by frifticn. 
 
 If a confiderable piece of fulphur be expofed to a 
 fuddcn though gentle heat, by holding it in the hand, 
 for inftance, it breaks to pieces with a crackling noifcf. 
 
 Its fptcific gravity is 1,990. 
 
 When heated to the temperature of 1P5'' of Fahren- 
 heit, it melts and becomes very fluid. If the tempera- 
 ture be ftill farther increafed, the fluidity diminifiies; but 
 when t"he fulphur is then carried from the fire and al- 
 lowed to cool, it becomes as fluid as ever before it con- 
 geals J. 
 
 When fulphur is heated to the temperature of 170°, 
 it rifes up in the form of a fine powder, winch may be 
 eafily collefted in a proper veffe). This powder is call- 
 ed JloiLiers of fulphur. When fubftances fly off in this 
 manner on the apphcation of a moderate heat, they are 
 called volatile ; and the procefs itfelf, by which they are 
 raiied, is called •volaiiUxatlon . 
 
 Sulphur undergoes no change by being allowed to 
 reinain e.'ipofed to the open air. 
 
 When thrown into water, it does not melt, as com- 
 mon fait docs, but falls to the bottom, and remains 
 there unchanged ; it is therefore infoluble in water. If, 
 however, it be poured, while in a ftate of fufion, into 
 water, it aflfumes a red colour, and retains fuch a degree 
 of foftnefs, that it may be kneaded between the fingers ; 
 but it lofes this property in a few days ^. 
 
 There are a great many bodies which, after being dif. 
 folved in water or melted by heat, aje capable of afFu- 
 ming certain regular figures. If a quantity of common 
 
 2IJ 
 
 fait, for inflance, be dilTdlvcd in water, and that fluid, Sulphur. 
 by the application of a moderate heat, be made to fly ^"^ ^ 
 off in the form of ikam ; or, in other words, if the wa- 
 ter be flowly evnporuled, the fait will fall to the bottom 
 of the vefll-l in cubts. Thefe regular figures are called 
 cr\jlah. Now iuli>hnr is capable of cryllallizing. If it 
 be melted, and as foon as its furface begins to congeal, 
 the li.jnid fulphur beneath be jioured out, the internal 
 cavity will exhibit long needle-lhapcd cryllals of an oc- 
 tahedral figure. This method of cryl'ialliiing fulphur 
 was contiived by Rouelle. 
 
 When fulphur is heated to the temperature of 3 02° Converted 
 In the open air, it takes fire fpontaneoufly, and burns by combuf- 
 with a pale blue fl.ime, and at the fame time emits a""" '"'°^ 
 great quantity of fumes of a very ftrong fuffocating 
 odour. When heated to the temperature of 370°, or 
 a little higher, it burns with a bright white flame, and 
 at the fame time emits a valt quantity of fumes. If the 
 heat be continued long enough, the fulphur burns all 
 away without leaving any afhes or rcfiduum. If the 
 fumes be collefted, they are found to confift: entirely of 
 fulphuric add. By combuilion, then, fulphur is con- 
 verted into an acid. This faft was known feveral cen- 
 turies ago, but no intelligible explanation was given of it 
 till the time of Stahl. That chemill undertook the ta(]<; 
 and founded on his experiments a theory fo exceeding- 
 ly ingenious, and fupported by fuch a vail number of 
 fafts, that it was in a very (hort time adopted with ad- 
 miration by all the philolophic world, and contributed 
 not a little to raife chemiilry to that rank among the 
 fciences from which the ridiculous pretenfions of the 
 early chemills had excluded it. ,, 
 
 According to Stahl, there is only one fubftance in Stahl's cs— 
 nature capable of combuftion, which therefore he called I^j.^",^f'"" 
 Phlogiston ; and all thofe bodies which can be fet 
 on fire contain lefs or more of it. Combuftion is mere- 
 ly the reparation of this fubftance. Thofe bodies which 
 contain none of it are of courfe incombuilible. All com- 
 bnftibles, except thofe which conlill of pure phlogifton 
 (if there be any fuch), are compofed of an incoinbuftbile 
 body and phlogifton united together. During combuf- 
 tion the phlogifton flies ofl^, aiul the incombuftlble body 
 remains behind. Now when fulphur is burnt, the fub- 
 ftance which remains is fulphuric acid, an incoinbuftible 
 body. Sulphur therefore is compofcd of fulphuric acid 
 and phlogifton. 
 
 To eftablilh tliis theory completely, it was neceffary 
 to ftiew that fulphur could be aftually made by combi- 
 ning fulphuric acid and phlogifton ; and this alfo Stahl 
 undertook to perform. Sulphat of pottfs is a fubftancff 
 compofed of fulphuric acid and potafs (d), and charcoal 
 is a combuftible body, and therefore, according to the 
 theory of Stahl, contains phlogifton : when burnt, it 
 leaves a very inconfiderable relidnum, and confequently 
 contains hardly any thing elfe than phlogifton. He 
 melted together in a crucible a mixture oi polafs ?indful- 
 phat of potafs, Itlrred into it one-fourth part by weight 
 of pounded charcoal, covered the crucible with another 
 inverted over it, and applied a ftrong heat to it. He 
 then allowed it to cool, and examined its contents. The 
 charcoal had difappeared, and there only remained in 
 the crucible a mixture of potafs and fulphur combined 
 together, 
 
 of this. 
 
 (d) The nature oi potafs (hall afterwards be explained, 
 purity. 
 
 It is the potafb well known in commerce in a ftate of
 
 2l6 
 
 S;.l[.l'«r together, and of a darker colour than ufual, from the 
 *~~v~— rclidiuim of the charcoal. Now there were only thiec 
 fubftaiiccs in the crucible :it firll, potafs, fulphuric acid, 
 and charcoal : two of thele have difappeared, andy«/- 
 f/.tir has been found in their place. Sulphur then nuift 
 hive been formed by the combination of thefe two. 
 Uut charcoal coiifilbs of phlo;;illon and a very fmall rc- 
 fidunni, which is flill found in the crucible. The ful- 
 
 CHEMISTRY. 
 
 fame, there was not the finalleft reafon to fiippofe that 
 any fubftance had left the fulphur.. 
 
 It is impofiible, then, that fulphur can be compofed 
 of fulphuric acid and phlogiilon, as Stahl fuppofed ; 
 finee fulphur ilfclf enters as a part into the conipofitiotj 
 of that acid. There muft therefore have been foine 
 want of accuracy in the experiment by which Stahl 
 proved the compolition of fulphur, or at leaft fome f-.d- 
 
 Part I. 
 
 Sblj-huf. 
 
 21 
 
 Unfatirfac- 
 tuiy. 
 
 phnr then mull have been formed by the combination lacy in his reafouings; for it is impoflihle that two con- 
 of fulphuric acid and phlogiilon. This fimple and lu- tradiftory fafts can both be true. Upon examiiring the 
 rr.iiious explanation appeared fo fatisfaftory, that the potafs and fulphur produced by Stahl's experiment, we 
 compofition of fulphur was long confidered as one of tind them to be confiderably lighter than the charcoal, 
 the bell demonilrated truths in chemilhy. fulphuric acid, and potafs originally employed. Some- 
 
 There are two fai\s, however, which Stahl either did thing therelore has made its efcape during the applica- 
 not know or did not Aifiiciently attend to, neither of tion of the heat. And if the experiment be conduded 
 which were accounted for by his theory. The tirft is, in a clofe veffel, with a pneumatic apparatus attafhed 
 that fulphur will not burn if air be completely exclu- 
 ded ; the fccond, that fulphuric acid is heavier than the 
 fulphur from which it was produced. 
 
 To account for thefe, or fafts fimilar to thefe, fuc- 
 ceedinop chemifts refined upon the theory of Stahl, de- 
 
 li 
 R'al rxp!; 
 ration hy 
 I.ivoificr. 
 
 43 
 
 to it, a quantity of gas will be obtained exactly equal 
 to the weight which the fubftances operated on have 
 loft ; and this weight confiderably exceeds that of all 
 the charcoal employed. This gas is carbonic acid ^as, 
 which is cojTipofed d( charcoal and oxygen, as will af- 
 
 privedhis phlogiilon of gravity, and even affigned it a terwards appear. We now perceive what pafles in this 
 
 principle of kvity. Still, however, the neceflity of the experiment : Charcoal has a ilronger affinity for oxygen 
 
 contadl of air remained unexplained. At lall Mr La- at a high temperature than fulphur has. When char- 
 
 voifier, who had already difcinguiftied himfelf by the ex- coal therefore is prefented to fulphuric acid in that 
 
 tenfivenefsof his views, the accuracy of his experiments, temperature, the oxygen of the acid combines with it, 
 
 and the precifion of his reafoning, undertook the exa- they fly off in the form of carbonic acid gas, and the 
 
 mination of this fubjcft, and his experiments were pub- fulphur is left behind. 
 
 liflied in the Memoirs of the Academy of Sciences for The combuftion of fulphur, then, is nothing elfe than 
 
 '■• 1777. He put a quantity of fulphur into a large glafs the adt of its combination with oxygen j and, for any 
 
 veflel filled with air, which he inverted into another vef- thing which we know to the contrary, it is a fimple 
 
 fel containing mercury, and then fet fire to the fulphur fubftance. 
 
 by means of a burning-glafs. It emitted a blue flame, 
 
 and gave out thick vapours, but was very foon extin- as follows : l'u)phur. 
 
 guifhed, and could not be again kindled. There was, 
 
 however, a little fulphuric acid formed, which was a 
 
 good deal heavier than the fulphur which had difap- 
 peared ; there was alfo a diminution in the air of the 
 
 vefTcl proportional to this increafe of weight. The 
 
 fulphur, therefore, during its converfion into an acid, 
 
 muft have abforbed part of the air. He then put a 
 
 quantity of fulphuret of iron, which confifts of fulphur 
 
 and iron combined together, into a glafs veflfel full of air, 
 
 which he inverted over water (e). The quantity of air 
 
 in the velTel continued diminifliing for eighteen days, as 
 
 was evident from the afcent of the water to occupy the 
 
 fpace which it had left ; but after that period no farther 
 
 diminution took place. On examining the fulphuret, it 
 
 •was found fomewhat heavier than when firft introduced 
 
 into the veffel, and the air of the veffel wanted precifely 
 
 the fame weight. Now this air had loft all its oxygen ; 
 
 all the oxygen of the air in the veffel muft therefore - — 24 
 
 have entered into the fulphuret. Part of the fulphur 
 
 The affinities of fulphur, according to Bergman, are /^fljnjjjjj^j 
 
 Lead, 
 
 Tin, 
 
 Silver, 
 
 Mercury, 
 
 Arfenic, 
 
 Antimony, 
 
 Iron, 
 
 Fixed alkalies, 
 
 Ammonia, 
 
 Barytes, 
 
 Lime, 
 
 Magnefia, 
 
 Phofphorus ? 
 
 Oils, 
 
 Ether, 
 
 Alcohol. 
 
 Sect. II. Of Phofphorus. 
 
 Let a quantity of bones be burnt, or, as it is term-Produilion 
 was converted into fulphuric acid ; and as all the reft of ed in chemiftry, calcined, till they ceafe to fmoke, or "^ P"°'l'"'' 
 the fulphuret was unchanged, the whole of the increafe to give out any odour, and let them afterwards be re- 
 ef weight muft have been owing to fomething which duced to a fine powder. Put this powder into a glafs 
 had entered into that part of the fulphur which was veffel, and pour fulphuric acid on it by httle at a time, 
 converted into acid. This fomething we know was till farther additions do not caufe any extrication of air 
 oxygen. Sulphuric acid therefore muft be compo- bubbles (r). Dilute the mixture with a good deal of 
 fed of fulphur and oxygen ; for as the original weight water, agitate it well, and keep it hot for fome hours j 
 of the whole contents of the veffel remained exaftly the then pafs it through a filter. Evaporate the liquid 
 
 flowly 
 
 (e) This experiment was firft made by Scheele, but with a different view. 
 
 (f) The copious emiffion of air bubbles is called in chemiftry effervefccnce.
 
 Part I. 
 
 C H E M 
 
 45 
 Its dilco- 
 very. 
 
 Berlin. 
 
 Phoi", liiriii fliAvly till a quantity of white powdei' f<tlls to the bottom. 
 This powder mud be fcparated by filtration and thrown 
 away. The evaporation is then to be relumed ; and when- 
 ever any white powder appears, the fikration mull be re- 
 peated in order to IVparate it. During the whoK- proc-efs, 
 what remains on the filter mull be waflied with pure 
 water, and this water added to tlie liquor. The evapo- 
 ration is to lie contiiuicd till all the nioillure dllappears, 
 and nothing but a dry mifs remains. Put this mafs in- 
 to a crucible, and keep it melted in the fire till it ceales 
 to exhale fulphureous odours ; then pour it out. When 
 cold it alhimes the appearance of a brittle glafs. Pound 
 this glals in a mortar, and mix it with one-third by 
 weight of charcoal dull. Pu^t this mixture into an 
 earthen ware retort, and apply a receiver containing a 
 little water. Put the retort into a fand bath, and in- 
 creaie the fire till it becomes red hot. A fubftance 
 then pafTes into the receiver, which has the appearance 
 of melted wax, and which congeals as it falls into the 
 water of the i-eceiver. This fubftance is phojphoi-.is. 
 
 It was difcovcred by Brandt, a chemill ot Hamburgh, 
 about the year 1667, while he was employed in attempt- 
 ing to extratt from h\iman urine a liquid capable of con- 
 * Leiki:!tz, verting filver into gold *. 
 
 ' ' Kunkel, another German chemift, hearing of the dif. 
 
 covery, was anxious to find out the procefs, and for 
 that purpofe aflbciated himlelf with a friend of his na- 
 med Kraft. But the latter piocured the fecret from 
 the difcoverer ; and expedting by means of it to acquire 
 a fortune, refufed to give any information to his alTo- 
 ciate. Vexed at this treachery, Kunkel refolved to at- 
 tempt the difcovery himfelf ; and though he knew on- 
 ly that phofphorus was obtained from urine, profecuted 
 the inquiry with fo much zeal, that he fncceeded, and 
 has been defervedly confidered as one ot the difcover- 
 era f. 
 
 Boyle likewile difcovered phofphorus. Leibnitz in- 
 '''m ^''"^"deed aflirms that Kraft taught ISuyle the wlioie pro- 
 cefs, and Kraft declared the lame thing to Stahl. But 
 ■furely the afiertion of a dealer in fecrets, and one who 
 had deceived his own friend, on which the whole of this 
 ftory is founded, cannot be put in competition with the 
 
 f affirmation of a man like Boyle, who was one of the 
 
 honefteft men, as well as greatell philofophers, of Kis 
 age ; and he pofitively allures us that he made the dif- 
 covery without being previoufly acquainted with the 
 t JJojfc A- procefs |. 
 
 triJgciiiy Gahn, a Swedifli chemill, difcovered, in 1769, that 
 
 .'"'"' phofphorus was contained in bones |{, and Scheele (g) 
 
 ji Bergman' s^'^'^Y f''"" after invented a procefs for obtaining it from 
 
 Notej on them. Pholphorus is now generally procured in that 
 
 Hcbefer. : manner. The procelsdefcribed in the beginning of this 
 
 fetlion is that of the Dijon academicians : it differs 
 
 , from that of Scheele only in a fingle particular. 
 
 Its proper. Phofphorus, when pure, is of a clear, tranfparent, 
 
 ties. yellowilli colour ; but when kept fome time in water, it 
 
 SuppL. Vol. I. Part I. 
 
 Three Hui 
 
 I S T R Y. 217 
 
 becomes opaque, and then has a great refemblance to Phofphorui 
 wliite wax. Its confillencc is nearly that of wax : it » 
 may be cut with a knife or twilled to pieces with the 
 lingers. It is infolublc in water. Its Ipecific gravity 
 is 1,714. 
 
 It melts at the temperature of 991 •, and even at 67" « Vclht'ier, 
 it gives out a white finoke, and is luminous in tlie dark > Journal de 
 that is to fay, it fufl'ers a How combullion : fo tlut it ^'hf'}"'' 
 
 , , ' . r , • ,- 1. 1 • •. • ilOtV. 380, 
 
 can only be prevented trom taking lire by keeping it in 
 a very low temperature, or by allowing it to remain al- 
 ways plunged in water. If air be excluded, it evapo- 
 rates at 219", and boils at 554*^ f. When heated io^Uid-iit. 
 
 I22'> f H^, it burns with a very briaht flame, and gives .. '^7 
 
 \ ' . r 1 • /■ 1 1 • L ■ 1 • Converted 
 
 out a great quantity ot white Imoke, which is luminous |, combuf« 
 
 in the dark; at the fame time it emits an odour which tion 
 has fome refemblance to that of garlic. It leaves no 
 refiduum ; but when the wliitc fmoke is collected, it is 
 found to be an acid. Stahl conlidered this acid as the 
 muriatic (.1). According to him, phofphorus was com- 
 pofed of muriatic acid and phlogillon, and the combuf- 
 tion of it was merely the feparatinn of phlogillon. Pie 
 even declared, that to make phofphorus, nothing more 
 was neceffary than to combine muriatic acid and phlo- 
 gillon ; and that this compofition was as eafily accom- 
 phlhed as that of fulphur itfelff. \ThreeHun. 
 
 Thefe aflertions gained implicit credit ; and the com- dred Expiri- 
 pofition and nature of phofphorus were confidered as "'"'''• 
 completely underllood, till Margraf of Berlin publidied 
 his experiments in the year 1743- That great man, 
 one of thofe illullrious philofophers who have contribu- 
 ted fo much to the rapid increafe of the fcience, dillin- 
 guilhed equiiUy for the ingenuity of his experiments and 
 the clearnefs of his reafaning, attempted to produce 
 phofphorus by combining together phlogillon and mu- 
 riatic acid ; but though he varied his procefs a thou- 
 fand ways, prefented the acid in many ditferent Hates, 
 and employed a variety ot fubllances to turniih phlogil- 
 ton, all his attempts failed, and he w.hs obliged to give ,g 
 up the combination as impradlicable. On examining Into phof- 
 the acid produced during the combuftion of phofpho- phone acid, 
 rus, he found that its properties were very different trom 
 thofe of muriatic acid. It was therefore a diftinft fub- 
 ftance. The name of pbofphoric acid was given to it ; 
 and it was concluded tliat phofphorus was compofed of 
 this acid united to phlogifton. 
 
 But it was obferved in 1772 by Morveau J, that § Oifrr/. 
 phofphorlc acid was heavier than the phofphorus from " ""' 
 which it was produced (k); and Boyle had long before 
 (hewn that phofphorus would not burn except when in 
 contaft with air. Thefe fadts were fufficient to prove 
 the inaccuracy of the theory concerning the compofi- 
 tion of phofphorus ; but they remained thenifelves un- 
 accounted tor, till Lavoifier publilhed thofe celebrated 
 experiments, which threw fo much light on the nature 
 and compofition of acids. , 
 
 He exhaufted a glafs globe of air by means of an air- 
 E e pump ; 
 
 (g) Crell, in his life of Scheele, informs us that Scheele was himfelf the difcoverer of the fail. This, he fays, 
 clearly appears from a printed letter of Scheele to Gahn, who was before looked upon as the difcoverer. See 
 CreU's yjnnals, Englilh Tranf. I. 17. 
 
 (h) Morveau, Encyd. Method. Chimie, art AffmUc. — According to Nicholfon at 160". See his TranJlaUon of 
 Chaptal. 
 
 ( I ) This acid fhall be afterwards defcribed. 
 
 (k) The fame obfervation bad been made by Margraf, but no attention was paid to it.
 
 2l8 
 
 Phofphorus, 
 
 19 
 
 Which is 
 phofphorc 
 comi-intd 
 ■with oxy- 
 gen. 
 
 ^L.ii'oifiir. 
 Hbenrjiry, 
 Part I. 
 chap. V. 
 
 30 
 Fhofphorus 
 tor. bine 
 ■with ful- 
 phur. 
 
 C H E M 
 
 ■pump ; and after weighmg it accurately, he filled it 
 with oxvgen gas, and iiitrnduced into it ico grains ot 
 phofphorus. The globe was furnifhed with a ftup- 
 cock, bv which oxygen gas could be admitted at plea- 
 lure. He i^et fire to the phofphorus by means of a 
 Lurning-glafs. The combnllion was extremely rapid, 
 accompanied by a bright flame and muclt lieat. Large 
 quantities of white flakes attached thcmfelves to the in- 
 ncr furface of the vlobe, and rendered it opaque ; and 
 thtfe at laH became fo abundant, that notwithllandin;^ 
 the conftant fupply of oxygen gas, the phofphorus was 
 txtinguiflied. The globe, after being allowed to cool, 
 was again weighed before it was opened. The quantity 
 of oxygen employed dniing the experiment was afcer- 
 tained, and the phofphorus, which ilill remained un- 
 changed, accurately weighed. The white flakes, which 
 were nothing tlfe than pure phofphoric acid, were found 
 exaftly equal to the weights of the phofphorus and 
 oxygen, which had difappeared during the procefs. 
 Phofphoric acid therefore niuft have been formed by 
 the combination of thefe two bodies ; for the ablolute 
 weight of all the fubftances together was the fame be- 
 fore and after the procefs *. It is impofuble then that 
 phofphorus can be compofed of phofphoric acid and 
 phlogifton, as phofphorus itfelf enters into the compo- 
 fition of that acid (l). 
 
 Thus the combuilion of phofphorus, like that of ful- 
 phur, is nothing elfe than its combination with oxygen; 
 for during the procefs no new fubflance appears except 
 the acid, accompanied indeed with much heat and 
 light. 
 
 Phofphorus combines readily with fulphur, as Mar- 
 graf difcovered during his experiments on phofphorus. 
 This combination was afterwards examined by Mr Pel- 
 letier. The two fubllanccs are capable of being mixed 
 in different proportions. Seventy-two grains of phof- 
 phorus and nine of fulphur, when heated in about four 
 ounces of water, melt with a gentle heat. The com- 
 pound remains fluid till it be cooled down to 77'^, and 
 then becomes folid. Thefe fubftances were combined 
 in the fame manner in the following proportions : 
 
 'fiTr^f"''? congeals at 59" 
 18 Sulphur S ° ■'^ 
 
 Phofphor.l 
 
 Sulphur J 
 
 72 Phofphor. 1 
 
 r J 
 
 !■>■ 
 36 
 
 at 
 
 at 
 
 at 
 
 509 
 99' 
 
 ■f VtUtiUr, 
 
 'Jour, de 
 jehyf. XMV. 
 381. 
 
 72 Sulphur 
 72 Phofphor. I 
 216 Sulphur J 
 
 Phofphorus and fulphur may be combined alfo by 
 melting them together without any water; but the com- 
 bination takes place fo rapidly, that they are apt to 
 rufh out of the veffe! if the heat be not exceedingly mo- 
 derate -j-. 
 
 Phofphorus is capable of combining alfo with many 
 other bodies : the compounds produced are called phoj- 
 fburtlt. 
 
 I S T R Y. Parti. 
 
 The affinities of phofphorus have not yet been afecr- Csrbou. 
 tained. *~~^""""' 
 
 Sect. III. Of Carbon. 
 
 If a piece of wood be put into a crucible, well co- 
 vered with faiid, and kept red hot for feme time, it is 
 converted ijito a black ihining brittle fubllance, without 
 either taltc or fmell, well known under the name of 
 charcoal. This fubftance contains always mixed with 
 it icveral eai thy and faline particles. When freed from 
 thefe impurities it is called carbon. 
 
 Charcoal is infoluble in water. It isnotafiefted (pro- properties 
 vided that all air be excluded) by the moft violent heat of carbon, 
 which can be applied, excepting only that it is lendered 
 much harder. 
 
 New-made charcoal abforbs moifture with avidity. 
 When heated to a certain temperature, it abforbs air 
 copioufly. La Metherie plunged a piece of burning 
 charcoal into mercury, in order to extinguifli it, and 
 introduced it immediately after into a glafs veffel filled 
 with common air. The charcoal abforbed four times 
 its bulk of air. On plunging the charcoal in water, 
 one-fifth of this air was difengaged. This air, on be- 
 ing examined, was found to contain a much fmaller 
 quantity of oxygen than atmofpherical air does. He 
 extinguilhed another piece of charcoal in the fame man- 
 ner, and then introduced it into a veflel filled with oxy- 
 gen gas. The quantity of oxygen gas abforbed ainount- 
 ed to eight times the bulk of the charcoal ; a fourth 
 part of it was difengaged on plunging the charcoal into 
 water *. It appears from the experiments of Sennebier, *Jcur. dt 
 that charcoal when expofed to the atmofphere abforbs ^AV- ^^^t- 
 oxygen gas in preterence to a%oi \, as the other portion J°9 
 of common air is called. f;^,-,^ '-^ 
 
 When heated to the temperature of 370° |, it takes i6i. 
 fire, and, provided it has been previoufly freed from the t Moriicai, 
 earths and ialts which it generally contains, it burns ^'O''- ^'- 
 without leaving any refiduum. If this combuftion be dir^-fi ' 
 performed in clofe veffels filled with oxygen gas inftead ^2 
 of common air, part of the charcoal and oxygen difap- Converted 
 pear, and in their room is found a particular gas exaftly "?'° ^^ '* 
 equal to them in weight. This gas has the properties'"' 
 of an acid, and is therefore called carbonic acid gas. Mr 
 Lavoifier, to whom we are indebted fur this difcovery, 
 afcertained, by a number of very accurate experiments, 
 that this gas was compofed of about 28 parts of carbon 
 and 72 of oxygen ||. || M,m. A. 
 
 Carbon is fufceptible of cryftallization. In that ftatc <■"'''• 1781, 
 it is called diamond. The figure of the diamond varies ^' ^''^" 
 confiderably ; but moft commonly it is a hexagonal prifm Sufceptilde 
 terminated by a iix-fided pyramid. When pure it is co- of cryftalli- 
 lourlefs and tranfparent. Its fpecific gravity i» from nation. 
 3,44 to 3,55. It is one of the hardeft fubftances in 
 nature ; and as it is not aflefted by a confiderable heat, 
 it was for m.any ages confidered as incombuftible. Sir 
 Ifaac Newton, obferving that combuftibles refrafted " 
 
 light more powerfully than other bodies, and that the 
 diamond poflefled this property in great perfeftion, fuf- 
 
 pe£le4s 
 
 (l) The quantity of phofphorus confumed was 45 grains 
 
 The quantity of oxygen gas ... 69,375 
 
 Weight of the phofphoric acid produced 1 14,375 
 
 Phofphoric acid therefore is compofed of 100 parts phofphorus and 1.54 oxygerb
 
 CHEMISTRY. 
 
 pcdid, from that circumftanct, tliat it was capable of 
 cciribiiftion. This lingular coiijidlure was verified in 
 1 f)94 by the Florentine academicians, in the prtfence of 
 Cofnio III. grand duke of Tufcany. By means of a 
 burnlng-glafs, tliey deftroyed ftviral diamonds. Fran- 
 cis I. emperor of Germany, afterwards witncfTed the de- 
 flrudlion of feveral more in the heat of a furnace. Thefe 
 experiments were repeated by Rouelle, Macquer, and 
 D'Arcet ; who proved that the diamond was not merely 
 evaporated, but aftually burnt, and that if air was ex- 
 cluded it underwent no change. 
 
 No attempt, however, was made to afcertain the pro- 
 dn£l, till Lavoificr undertook a feries of experiments tor 
 that purpofe in 1772. He obtained rarionic acid gas. 
 It might be concluded from thefe experiments, that the 
 diamond contains carbon ; but it was referved for Mr 
 Tennant to fhew that it confiited entirely of that fub- 
 llance. 
 
 Into a tube of gold, having one end clofed and a 
 glafs tube adapted to the other to coUedl the produrt, 
 that gentleman put 2{ grains of diamonds and a quar- 
 ter of an ounce of nitre (m). This tube was heated 
 flowly ; the confequence of which was, that great part 
 of the nitric acid pafled off before the diamond took 
 fire, and by that means almoll the whole of the carbonic 
 3cid formed during the combullion of the diamond re- 
 mained in the potafs, for which it has a llrong affinity. 
 To afcertain the quantity of this carbonic acid, he dii- 
 folved the potafs in water, and added to the folution an- 
 other fait compofed of muriatic acid and lime. Muria- 
 tic acid has a ftronger affinity for potafs than for lime; 
 it therefore combines with the potafs, and at the fame 
 time the lime and carbonic acid unite and tall to the 
 bottom of the veffcl, becaufe they are nearly infoluble in 
 water. He decanted off the liquor, and put the lime 
 which contained the carbonic acid gas into a glafs globe, 
 having a tube annexed to it. This globe and tube he 
 then filled with mercury, and inverted into a veffel con- 
 taining the fame fluid. The lime by that means occu- 
 pied the very top of the tube. It now remained to fepa- 
 rate the carbonic acid from the lime, which may be done 
 by mixing it with any acid, as almoft every other acid 
 has a ftronger affinity for lime than carbonic acid has. 
 Accordingly on introducing muriatic acid, 10,3 ounce 
 meafures ot carbonic acid gas, or nearly 9,166 grains, 
 were feparated. But, according to the experiments of 
 Lavoifier, this gas is compofed of 72 parts of oxygen and 
 2H of carbon; 9,166 grains, therefore contain 2, 56 grains 
 of carbon, which is almoll precifely the weight of the 
 diamond confumed. It follows, therefore, that it was 
 compofed of pure carbon*. The difficulty of burning 
 the diamond is owing entirely to its hardnefs. Mefl'rs 
 Morveau and Tennant rendered common charcoal fo 
 liard by exj)ofn)g it for fome time to a violent fire in 
 dole veiTels, that it loll much of its natural tendency to 
 combuftion, and endured even a red heat without catch- 
 ing fire f. 
 
 Charcoal poffeffes a number of fingular properties, 
 
 219 
 
 which render it of confiderable importance. It is in-Hydr.>Kcn. 
 capable of putrefying or rotting like wood, and is not'""'^ '"' 
 therefore liable to decay through age. This property 
 has been long known. It w3s cuftc-mary among the 
 ancients to char the outfide of thofe flakes which were 
 to be driven into the ground or placed in water, in or- 
 der to preferve the wood from fpoiling. New-made 
 charcoal, by being rolled up in cloths which have con- 
 tracted a difagreeable odour, effedlually ilcltroys it. It 
 takes away the bad taint from meat beginning to pu- 
 trefy, by being boiled along with it. It is perliaps the 
 bell teeth powder known. Mr Lowitz of Pelerfburgh 
 has fhewn, that it may be ufed with advantage to puri- 
 fy a great v.;riety of lubftances. 
 
 Carbon unites with a number of bodies, and forms Carbmctj, 
 with them compounds known by the name of carburets. 
 
 Its affinities have not yet been afcertained. 
 
 Sect. IV. Of Hydrogen. 
 
 Put into a glafs veffel furnifhed with two mouths a - 
 
 quantity of freih iron filings, quite free from rull. Lute\ierhod of 
 into one of thefe mouths the end of a crooked glafsprocurTig 
 tube. Infcrt the other end of this tube below a glafs *'y'^''<'g«"- 
 jar filled with water, and inverted into a pneumatic ap- 
 paratus. Then pour upon the iron filings a quantity of 
 fulphuric acid, diluted with twice its own weight of 
 water, and clofe up the mouth of the veffel. Imme- 
 diately the iron filings and acid tffervcfce with violence, 
 a valt quantity of gas is produced, which rufhes through 
 the tube and fills the jar. This gas is called hydrogen 
 gas {t^). 
 
 It was obtained by Dr Mayow and by Dr Hales 
 from various fubllances, and had been known long be- 
 fore in mines under the name oit)neJi'e damp. MrCa- 
 vendifh * was the fn (I who examined its properties with » pf.^ 
 attention. They were afterwards more fully invelliga- iVan/rijje. 
 ted by Prieftley, Scheele, and Fontana. 
 
 Hydrogen, like a/r, is invifible and elaftic, and ca- its proper- 
 pable of indefinite comprefTion and dilatation. ties. 
 
 Its fpecific gravity differs according to its purity, 
 Kirwan found it o,cooiof ; Lavoifier 0,000094 ;j:, or^OnPhlegif- 
 about twelve times lighter than common air. *on , ft-et. 1 ft. 
 
 All burning fubllances are immediately extin^uifhedL "''."'J'"'' 
 
 ... 1,. 1. T-. ,.°. Uicmijlri, 
 
 by benig plunged mio this gas. It is mcapable, there- ^fpinjfx, 
 fore, of fupporting combuftion. 
 
 Animals, when they are obliged to breathe it, die al- 
 moft inftantaneoufly. Scheele, indeed, found that he 
 could breathe it for lome time without inconvenience § ;^ Sdeilccn 
 but Fontana, who repeated the experiment, difeoveredi"''"- 
 that this was owing to the quantity of common air con- 
 tained in the lungs when he began to breathe ; for 011 
 expiring as ftrongly as poflible before drawing in the 
 hydrogen gas, he could only make three refpirations, 
 and even thefe three produced extreme feeblcnefs and 
 opprefhon about the breait p . II 7"""' '''• 
 
 If a phial be filled with hydrogen gas, and a lighted ''^■'•'■''*'9'* 
 candle be brought to its mouth, the gas will take fire, 
 and burn gradually till it is all confumed. If hydro- 
 E e 2 gen 
 
 (m) Niti'e is compofed of potafs and nitric acid ; and nitric acid contains a great quantity of oxygen, w-hich 
 is eafily feparated by heat. Diamond, when mixed with nitre, burns at a much lower heat than by any other 
 procefs. 
 j[n) It was formerly called irJlammaLle air,zin\ by fome ditrmVi^ phlogijloit.
 
 220 C H E M I 
 
 Hydrogen, rren and oxygen gas be mixed together and kindled, 
 
 ' »r— ' lliey burn inllantaneoufly, and produce an ey.plollon 
 
 like 'Tunpowder. The fame efFeft follows when a mix- 
 ture of hydrogen gas and almofpherical air is kindled, 
 but the exploiion is kfs viulent. Hydrogen gas will 
 not biirii except in contatt with oxygen gas, nor 
 will it burn even in contad with oxygen gas, unlcfs a 
 red heat be applied to it. If 85 parts by weight of 
 oxygen gas, and 1 5 of hydrogen gas, be mixed toge- 
 ther, and fet on fire in a clofe veflll, they dil'appcar, 
 and in their place there is found a quantity of water 
 „ 3*„ exaAlv equal to them in weieht. This water miift be 
 finn of wa- compufed of thele two gales ; tor it did not previoully 
 tcr. exilt in the vcfTel, and no other fubftante except the 
 
 gafcs was introduced. Water then is compofed ot oxy- 
 gen and hydrogen ; and the combullion yt hydrogen is 
 nothing elfe but the att of its combination with oxy- 
 gen (o). 
 
 It had been fuppofed, in confequence of the experi- 
 ments of Dr Piicltley and feveral other philofophers, 
 that when hydrogen gas was allowed to remain in con- 
 tad with water, it was gradually dccompofcd, and con- 
 _,. . verted into another gas; but Mr de Morveau *, Mr 
 
 I X'n. J/**" Halfenfratz f , and Mr Libes^, have fliewn that it un- 
 ti/OT.i. ipx.dergoes no change, provided fufBcient care be taken to 
 f Jaur. J,' exclude every other gas. 
 
 J'li;if ixxvi. Hydrogen gas difTolves fulphur, phofphorus, and car- 
 bon. The compounds are calledyu^Ai»aW,/iAo/^io/-a- 
 Compounds W, and carbonnled hydrogen gas. 
 
 if hydro- j. Sulphurated hydrogen gas was firft examined with 
 
 gen gas. attention by Scheele, \v\\o, together with Bergman, dif- 
 covered many of its properties. Mr Kirwan likewife 
 publifhed a very valuable paper on the fame fubjeiS. 
 If equal parts of fulphur and potafs be melted together 
 in a covered crucible, they combine together, and form 
 a compound known by the name of fidphurct of potafs, 
 but formerly called, from its red colour, hepar fulphur is, 
 or li-uer of fulphur. When this fubltance is moiftened 
 with water, it gives out a quantity of fulphurated hy- 
 drogen gas; hence this gas was at firft called hepatic gas. 
 Mr Gengenibre enclofed a bit of fulphur in a glafs 
 velTel filled with hydrogen gas, and melted the fulphur 
 by means of a burning-glals. A quantity of it difap- 
 peared, and the hydrogen affunied all the properties of 
 hepatic gas. Hence it follows that this gas is merely 
 fulphur diffolved in hydrogen gas. 
 
 The eafieft method of obtaining it Is to pour an 
 acid, the muriatic for inftancc, on a quantity of the 
 fulphuret reduced to powder. An effervefcence takes 
 place, the gas is extricated, and may be coUefted by 
 means of a pneumatic apparatus. The theory of this 
 emiffion is obvious. The fulphur is gradually convert- 
 ed into fulphuric acid, by decompofing the water, which 
 is always united with acids, and feizing its oxygen : 
 the hydrogen of the water is thus fet at liberty ; it af- 
 fumes the gafeous form, and at the fame time difTolves 
 
 S T R y. 
 
 Part r. 
 
 * F.ncycl. 
 Mith'od. 
 
 Sulphura- 
 ted bydro- 
 gcB gas. 
 
 part of the remaining fulphur, for which it has a con-Hydroi-en, 
 liderablc aflinity. ^ ' 
 
 The fpeeltic gravity of fulphurated hydrogen gas is 
 0,00135*; it is to common air as 1 106 to 1000. * ^irwnn 
 
 It has a very fetid odour, prccifely funilar to tWdt"" ^^'''•^'^"'* 
 emitted by rotten eggs, which indeed is owing to the ^ ' 
 emiffion of the very fame gas. 
 
 It is not more rcfpirable than hydrogen gas. When 
 fet on fire, in contaft with oxygen gas, it burns with a 
 light blue flame, without exploding, and at the fame 
 time a quantity of fulphur is depofited. The combuf- 
 lion of this gas, then, is merely the union of its hydro- 
 gei^, and perliaps part of its fulphur, with oxygen. 
 
 This gas turns iyrup of violets to a green colourf.f Fourcrey't 
 
 It does not feem capable of exiftinjr in atmufpherical '''"'""^'''-?'' 
 
 •I . J ,- ■ f , ° ^ .'^ arl.Sulphur 
 
 air without deeompolition ; tor the moment it comes 
 
 into contaft with oxygen gas, fulphur is depofited :f. { Bergman. 
 
 2. Phofphorated liydrogen gas was difcovcred by Mr 4i 
 Gergembre in 1783, and by Mr Kirwan fome time af- J'^"^'' j^"* 
 ter, before he became acquainted with the experiments ^j, „j3_ 
 of that gentleman. It may be procured by mixing 
 phofphorus with potafs dilfolved in water, and applying 
 a boiling heat to the folution. The phofphorus is gra- 
 dually converted into an acid by decompofing the wa- 
 ter, and uniting with its oxygen. The hydrogen af- 
 fumes the form of a gas, and flies off after diflblving 
 a little of the phofphorus. This gas may be coUefted 
 by means of a pneumatic apparatus. 
 
 Phofphorated hydrogen gas has a fmell refembling 
 that of putrid filh. When mixed with oxygen gas or 
 common air, it becomes luminous ; and on the applica- 
 tion of the fmalleft heat, it burns with aftonifhing rapi- 
 dity §. The produfts are water and phofphoric acid. 5 Kinean, 
 The combuftion of this gas therefore is nothing elfe 
 than the union of its phofphorus and hydrogen with 
 oxygen, attended by an emiffion of heat and light. 
 
 Phofphorated hydrogen gas may alfo be formed by 
 introducing a bit of phofphorus into a jar containing 
 hydrogen gas : but care mull be taken to make this gas 
 as dry as poffible ; for its affinity with phofphorus is 
 weakened in proportion to its moifture |]. II BrugimUl- 
 
 3. Carbonated hydrogen gas arifes fpontaneoufly inv!' ^'''"'' 
 
 hot weather from marfiies, but always mixed with feve-'"/; °"'" 
 
 ■ . «ii*, 1. 445' 
 
 ral other gafes. Several fpecies of it have been lately 
 
 difcuvered by the alTociated Dutch chemifts Bondt, 
 DIeman, Van Troollwyck, and Lauwcrenberg^. WhenH Anr.de 
 75 parts of fulphuric acid and 25 of fpirit of wine are '^*'"'' ^^'* 
 mixed together, a gas is extricated which fuffers no al-'^ 
 teratioii from [landing over water. Its fpecific gravity 4» 
 is 0,00111, or it is to common air as 9:9 to loco. Itj^"^"^^" 
 has a fetid odour, and burns with a llrong compaftgas.. 
 flame. When paffed through fulphur It is converted in- 
 to fulphurated hydrogen gas, and at the fame time a 
 quantity of carbon is depofited in the form of a fine 
 powder ; It muft therefore be compofed of carbon and 
 hydrogen gas. When burnt, the produft is carbonic 
 
 acid 
 
 (o) The hiflory of this great difcovery, and the obi.e£lions which have been made to it, we referve for the 
 chapter which treats of Water, where they will be better underftood than they could be at prefent. ^This fub- 
 flance was called hydrogen by the French chemills, becaufe it enters into the compofition of water, from ^i"? "wa- 
 ter, and y""i^3i I am horn. Ohjeclions have been made to the propriety of the name, into which we fhall not 
 enter. It ought never to be forgotten that Newton had long before, with a fagacity alraoll greater than human, 
 corjedlured, from its great refratling power, that water contained a combuflibh fubflance.
 
 • IbiJ. 
 
 f UiJ. 
 
 4.1 
 
 Part I. 
 
 Hydrogen, acid gas and water*. By making ether (p) pafs thro' 
 a red hot glafs tube, another carbonated hydrogen gas 
 was formed, the Ipecffic gravity of which was 0,00086. 
 Spirit of wine, pafTed in the fame manner, afforded a 
 gas, the fpecific gravity of which was 0,1005.?, '^^'•^ 
 which burned with a paler flame than the otlier two. 
 Thcfe gafes were found to contain from 80 I0 74 parts 
 of carbon, and from 20 to 26 of hydrogcii. The iiril 
 fpecieo was found to contain moll carbon, and the lait 
 to contain Icall f . 
 
 The aflinity of hydrogen gas for thefc three combuf- 
 
 Aflinitic'oftibles is as follows: 
 
 tilde gafct. Sulphur, 
 
 Carbon, 
 
 Phofphorus (c^). 
 Dr Auftin found, that by repeatedly pafling eleftric 
 explofions through a fmall quantity of carbonated hy- 
 drogen gas, it was permanently dilated to more than 
 twice its original bulk. He rightly concluded, that 
 this reiriarkable cxpanlion could only be owing to the 
 
 ,..'*■ . . evolulion of hydrogen yas. On burniiU'" air thus ex- 
 Attempt to , , , r ' , ? P • , *' • r 
 dcompofe panded, he tonnd that it required a greater quantity or 
 
 cdrbon oxygen than the f.ime quantity of gas not dilated by 
 eleiitricity : An addition therefore had been made to 
 the combullible matter ; for the quantity of oxygen 
 neceflary to complete the conibuftion of any body, is 
 always proportional to the quantity of that body. He 
 concluded from thefe experiments, that he had decora- 
 pofed the carbon which had been diffcilved in the hy- 
 drogen gas; and that carbon was ccmpoled of hydro- 
 gen and a7.ot(R), fome of which was always found in 
 the veffel after the dilated gas had been burnt by means 
 t PhU. of oxygen \. If this conclufion be fairly drawn, we 
 Tru//. axx.mull expunge carbon from the lill of fimple fubilances, 
 J'' and henceforth confider it as a compound. 
 
 There was one. circumftance which ought to have 
 prevented Dr Aullin from drawing this coiichilion, at 
 leaft till warranted by mere deciiive experiments. The 
 quantity of combuihble matter had been I'ncrealed. 
 Now, if the expanlion of the carbonated hydrogen gas 
 was owing merely to the decompolition of carbon, no 
 fuch increafe ought tc have taken place, but rather the 
 contrary; for the carbon, which was ittelf a combullible 
 fubftance, was refolved into two ingredients, hydrogen 
 and azot, only the lull of which burnt on the addition 
 of oxygen and the application of heat. Dr Aullin's 
 experiments have been lately repeated by Mr William 
 c p,., Henry with a great deal of accuracy §. He found 
 •/-,^„r'ij„.that the dilatation which Dr Auftin delcribes adlually 
 part id. took place, but that it could not be carried beyond a 
 certain degree, a little more than twice the original 
 
 CHEMISTRY. 
 
 45 
 
 £x.iriiiiied, 
 
 221 
 
 bulk of the gas. Upon burnin|T feparately by means of Azot. 
 oxygen, two equal portions of caibonsted hydrogen gas, * 
 one of which had been expanded by ele<!1ricity to double 
 its original bulk, the other not, he found that each of 
 them pioihiced precifely the fame quantity of carbonic 
 aciJ j;,is. Both therefore contained the fame quantity 
 of carbon ; confequently no carbon had bem decom- 
 pounded by the eleftric fhocks. ^.^ 
 
 Mr Henry then fufpcfted lluit the dilatation was ow- And fimnj 
 ing to the water which every gas contains in a larger "nf^cccft- 
 or Imaller quantity. To afcirtain tin's, he endeavoured " 
 to deprive the carbonated hydrogen gas of as much wa- 
 ter as poffible, by making it pafs over very dry potafs, 
 which attrafts water with avidity. Gas treated in this 
 manner could only be expanded one fixth of its btdk ; 
 but on admitting a drop or two of water, the expaiifion 
 went on as ufual. The fubftance decompounded by the 
 eletlricity, then, was not the carbon, but the water in 
 the carbonated hydrogen gas. Nor is it difficult to fee 
 in what manner this decompofition is effedled. Caibon, 
 at a high temperature, hasn greater affinity for oxygen 
 than hydrogen has ; for if the lleam of water be made 
 to pafs over red iiot charcoal, it is decompofed, and car- 
 bonic acid and hydrogen gas are formed. Tiie eleftric 
 explofion fupplies the proper temperature ; the carbon 
 unites with the oxygen of the water, and forms carbo- 
 nic acid ; and the hydrogen, thus fet at liberty, occa. 
 lions the dilatation. Carbonic acid gas is abforbed with 
 avidity by water : and when water was admitted into 
 709 meafures of gas thus dilated, 100 raeafures were ab- 
 forbed ; a proof that carbonic acid gas was aflually 
 prefent. As to the azot which Dr Auftin found in his 
 dilated gas, it evidently proceeded from the admilllon 
 of fome atmofpheric air, about 73 parts of which in the 
 100 conlill of this gas : for Dr Auftin's gas had ftood 
 long over water ; and Drs Prieflley and Higgins have 
 fhewn that air in fuch a fituation always becomes im- 
 pregnated with azot. 
 
 The aflinities of hydrogen have not yet been afcer- ;^g-„|i,;j5Qf 
 tained, but perhaps they are as follows : hydrogen. 
 
 Oxygeny 
 
 Carbon, 
 
 Azot. 
 
 Sect. V. OfJzot. 
 
 48 
 
 If a quantity of iron filings and" fulplutr, rrn'xed to- Method of 
 gether and moiftened with water, be put into a glafs procuring 
 veffdl full of air, it will abforb all the oxygen in the^^"'" 
 courfe of a fev/ days ; but a conliderable refiduum of 
 air ftill remains incapable of any farther diminution. This 
 reliduum has obtained the appellation of azotic gas. 
 
 (p) Ether i? a very volatile and fragrant L'quid, obtained by mixing fpi'rit of wine and acids, and diftilling. It 
 {hall be afterwards defcribed. 
 
 (q^) Sulphur decompofes carbonated hydrogen gas ; therefore its affinity is greater than that of carbon. The 
 Dutch chemifts melted phofphorus in carbonated hydrogen gas, but no change was produced ; therefore the 
 affinity of phofphorus is inferior to that of carbon. 
 
 (r) See next Section. — His theory was, that carbonated hydrogen gas was compofed of hydrogen, and azot, 
 and carbon of azot, and carbonated hydrogen gas, which comes nearly to the fame thing with regard to the ele- 
 ments of carbon. It is fingular enough, that though Dr Auftin would not allow the prefence of carbon in car- 
 bonated hydrogen gas, he aftually decompofed it by melting fulphur in it : the fulphur combined with the hy- 
 drogen gas, and a quantity of carbon was precipitated. This experiment he relates without making any reinarks 
 upon it, and feems indeed not to have paid any attention to it.
 
 'Z2 
 
 Az.it. 
 
 4V 
 Diiccivery 
 
 » KuM- 
 /h.i*s jfvt/r- 
 
 C H E M 
 
 It was ilifcovered in 1772 by Dr Rutherford, now 
 pr.'/ffflbr of botany in the univerlity of lidiiibuigh (s). 
 Schecle procured it by the above procefs as early as 
 1776, and proved that it w;is a dilliiicl fluid. Mr La- 
 voifitr aftcrwaids proved the fame thing, without any 
 previous knowledge ot Schtcle's diicovtries. 
 
 i"he air of the atmolphere contains about ,73 paits of 
 azDiic gas ; almoll all the reft is oxygen gas. 'i'he ea- 
 fitll method of procuring azotic gas is to put fome ful- 
 phuret of potafs into a glafs veflel filled with air, and 
 accurately clofcd, and then to apply heat to the fulphu- 
 ret. /\11 the oxygen is abforbed alinoll inftantly. This 
 method was iirlf pointed out by Morveau*. 
 
 Mr Kirwan examined the fpecitic gravity of azotic 
 n.i/, i.ioS. gas obtained by Schtele's procels ; it was 0,00120: 
 it is therefore fomewhat lighter than the atraofpheric 
 t On Ph:o- air ; it is to atmofpheric air as 98 ? to looof . 
 gifiin. ) 111. Jt tinges delicate blue colours (lightly with green J. 
 ^° It is exceedingly noxious to animals ; if they are obli- 
 ties S'-'l ^° refpire it, they drop down dead almoft inftant- 
 
 % fcurcrcy, ly (t). No comb'jftible vill burn in it. This is the 
 ylrn. lie rcafon that a candle is extinguifhed in atmofpherical air 
 im. 1. 4;. ^^ (qmx as the oxygen near it is confumcd. Mr Goett- 
 ling, indeed, publiHied, in 1794, that phofphorus ibone, 
 and was converted into phofphoric atid, in pure azotic 
 gas. Were this the cafe, it would not be true that no 
 conibuttible burns in this gas ; for the converfion of 
 phofphorus into an acid, and even its fhiiiing, is an ac- 
 tual though flow combuftion. Mr Goettling's experi- 
 ments were foon alter repeated by Drs Scherer and Jae- 
 ger, who found that phofphorus does not fliine in azotic 
 J5JS when it is perfectly pure; and that therefore the gas 
 on which Mr Goettling's experiments were made had 
 contained a mixture of oxygen gas, owing principally 
 to its having been only confined by water. Thefe re- 
 fults were afterwards confirmed by Profeffor Lampadius 
 and Profeffor Hildebrandt. It is therefore proved be- 
 yond a doubt, that phoiphorus does not burn In azotic 
 gas, and that whenever it appears to do fo, there is al- 
 JhV^oytViWays fome oxygen gas prefent §. 
 
 7oa,«u/, ii. Azotic gas is capable of difTolving phofphorus, as 
 3. has been proved by the experiments of Fourcroy and 
 
 Vauquelin. 
 
 It diilolves alfo a little carbon : for azotic gas ob- 
 tained from animal fubftances, which contain a great 
 deal of azot, when confined long in jars, depofites on the 
 
 I S T R y. 
 
 Part I. 
 
 iides of them a black matter which has the properties A/or. 
 of carbon *. ^ ,, ' 
 
 Thefe two folutions, the properties of which have ^ot .^°"'^'^' 
 yet been accurately examined, are called phojphorated cbim.\.^^, 
 and carbonated azotic gas. 
 
 Azotic gas is capable of combuftion. Take a glafs ,Jrf,j,,flion 
 tube, the diameter of which is about the fixth part of , i litiic 
 an inch ; (liut one of its ends with a cork, thrcnigh the'cid. 
 middle of which paffes a fniall wire with a ball ot metal 
 at each end. Fill the tube with mercury, and then 
 plunge its open end into a bafon of that fluid. Throw 
 up into the tube as much of a mixture, compofed of 1^5 
 parts of azotic and 87 parts of oxygen gas, as will fill 
 ^ inches. Through this gas make, by means of the 
 wire in the cork, a number of eleftric explofions pafs. 
 The volume of gas gradually diminilhcs, and in its place 
 there is found a quantity of nitrous acid. This acid, 
 therefore, is compofed of azot and oxygen : and thefe 
 two fubftances are capable of combining, or, which is 
 the fame thing, azotic gas is capable of combuftion in 
 the temperature produced by eleftricity, which we know 
 to be pretty high. The combuftibility of azotic gas, 
 and the nature of the produft, was firll difcovered by 
 Mr Cavendilh, and communicated to the Royal So- 
 ciety on the 2d of June • 7'^5(u)- 52 
 
 The affinities of azot are ftiU unknown. It has never Attempts 
 yet been decompounded, and mull therefore, in the pre-'" de">m- 
 fent ftate of our knowledge, be confidered as a fimpleP°**^° 
 fubftance. Dr Prieftley, who obtained azotic gas at a 
 very early period of his experiments, confidered it as a 
 compound of oxygen gas and phlogifton, and for that 
 reafon gave it the name of phlogi/iicated air. Accord- 
 ing to the theory of Stahl, which was then univerfally 
 prevalent, he confidered combuftion as merely the le- 
 paration of phlogifton from the burning body. To 
 this theory he made the following addition : Phlogif- 
 ton is feparated during combuftion by means of chemi- 
 cal affinity : Air (that is, oxygen gas) has a ftrong af- 
 finity for phlogifton : Its prefence is neceflary during 
 combuftion, becaufe it combines with the phlogifton as 
 it feparates from the combuftible ; and it even contri- 
 butes by its affinity to produce that feparation : The 
 moment the air has combined with as much phlogif- 
 ton as it can receive, or, to ufe a chemical term, the 
 moment it is faturaled with phlogifton, combuftion ne- 
 ccffarily ftops, becaufe no more phlogifton can leave the 
 
 combuf- 
 
 (s) See his thefts De Aere Mephitico, pubhfhed in 1772. — " Sedaer falubris et purus refpiratione animali non 
 modo ex parte fit mephiticus fed et aliam indoUs Jut mutalionem inde patitur. Poftquam enim omnis aer mephiti- 
 rus (carbonic acid gas) ex eo, ope lixivii cauftici fecretus et abduflus fuerit, qui lamen rejlat nullo modo ialubrior 
 jnde evadit ; nam quamvis nuUam ex aqua calcis prsecipitationem faciat baud minus quam antea et Jlammam et 
 I'itam extingiiit. Page 17. 
 
 " Aer qui per carbones ignitos folle adaftus fuit, atque deinde ab omni aere mephitico (carbonic acid gas) ex- 
 purgatus, malignus tamen adhnc reperitur et omnino fimilis eft ei qui refpiratione inquinatur. Immo ab experi- 
 meritis patet banc folam efte aeris mutationem quae inflammation! adfcribi poteft. Si enim accenditur materies 
 quoilibet qua; ex phlogifto et bafi fixa atque fimplici conftat, aer inde natus ne minimam acris mephitici quantitatem 
 in fe continere "videtur. Sic aer in quo fulphur aut phofphorus urinae cotnbuftus luit, licet maxime malignus, cal- 
 cem tamen ex aqua minime praccipitat. Interdum quidem fi ex phofphoro natus tuerit, nubeculain aquae calcis 
 inducit fed tenuiffimam, nee acri mephitico attribuendam, fed potius acido illi quod in phofphoro ineft, et quod, 
 ut experimenta docuerunt, hoc fingulari dote pollet." Page 19. 
 
 (t) Hence the name azot, given it by the French chemifts, which fignifies dejlrudive to life, from « and f^i". 
 
 (u) It is remarkable enough, that the acidity of nitric acid was afcribed by Mayow, in 1674., to the pretence 
 of oxygen. Indoles caujlica 'piritus nilri (fays hej a particulis ejus igneo-aereis j^rovenil. Traft. p. 19-
 
 Part I. 
 
 C H E M 
 
 Aznt. combuftible (v) : Air faturated with phlogifton is azo- 
 ""~v~~- tic gas. This was a very ingenious theory, and, when 
 Dr Prieftley pubh'fhed it, exceedingly plaufible. A 
 great number of the moft eminent chemifts accordingly 
 embraced it : But it was foon after difcovered, that 
 during combullion the quantity of air, inftead of in- 
 creaiing, as it ought to have done, had phlogifton been 
 added to it, aftually diminilhed both in volume and 
 - weight. There was no proof, therefore, that during 
 combuftion any fubftance whatever combined with air, 
 but rather the contrary. It was difcovered alfo, that 
 a quantity of air combined with the burning fubftance 
 during combuftion, as we have feen was the cafe with 
 fulphur, phofphorus, carbon, and hydrogen ; and that 
 this air had the properties of oxygen gas. Thefe dif- 
 coveries entirely overthrew the evidence on which Dr 
 Prieftley's theory was founded ; accordingly, as no at- 
 tempt to decompound azot has fucceedtd, it has beei» 
 given up by almoil every chemift excejit Dr Prieftley 
 himfelf. Atmofpheric air, as Schtele firil proved, is oom- 
 pofed of about 27 parts of oxygen and 73 of azotic gas. 
 During combuftion, the oxygen is abftrafted and the 
 azotic gas remains behind. 
 
 La Metherie made an attempt to prove that azot 
 was compofed of oxygen and carbon (w). He took a 
 bit of burning charcoal, extiuguilhed it in mercury, and 
 then plunged it while hot into oxygen gas. On being 
 plunged into water, one fourth of the gas was dilenga- 
 ged, and part of it was found to confift of azotic gas. 
 From this he concluded that he had formed azotic gas 
 by combining oxygen and carbon : But it was proved 
 by Mr Lavoifier, beyond the poffibility of doubt, that 
 oxygen and carbon form carbonic acid gas. They can- 
 not then certainly form azot ; for two contradiftory 
 lafts cannot both be true. There mull then have been 
 fomething overlooked in the experiment. Indeed the 
 experiment itfelf does not warrant the conclufion which 
 De La Metherie drew from it. He did not afcertain 
 whether the weight of the charcoal was diminiftied ; 
 and, befides, there was azot mixed with the oxygen gas 
 "ivhich he employed, as he himielf has informed us : 
 And how was it pcffible for him to admit the charcoal 
 into water without, at the fame time, admitting fome 
 atmofpherical air ? 
 
 We have now defcribed all the combuftibles which 
 are at prefent reckoned fimple, except the nietals. We 
 have found, that during combuftion all of them com- 
 bine with oxygen ; that no part of them is difengaged, 
 no part of them loft : we have therefore concluded, 
 that the combuftion of thefe fuhftances is nothing clfe 
 but the aft of their uniting with oxygen. We have 
 feen, however, that none of them, except phofphorus, 
 was capable of uniting with oxygen at the common 
 temperature of the atmofphere ; that, iu order to pro- 
 duce the union, heat was necelfary, and that the degree 
 of this beat v/as different for each. Hydrogen required 
 a red heat, and azot a ftiU greater. We have feen. 
 
 I S T R Y. 225 
 
 too, that during tliefe combinations a quantity of heat Metals, 
 and light efcaped. Now, why is heat necefTary for thefe '— v— ~' 
 combinations ? and whence come the heat and the light 
 which we perceive during the combuftion of thefe bo- 
 dies ? Thefe queftions are of the highell importance, 
 and can only be anfwered by a particular invtftigation 
 of the nature and properties of lieat and light. This 
 inveftigation we (hall attempt, as foon as we have de- 
 fcribed the mttals and cirths, which form the fubjeft of 
 the two following chapters. 
 
 CiiAP.lII. 0/ Metals. 
 
 J4 
 
 Metals may be confidered as the great inftruments Properties 
 of all our improvements : Without them, many of the°^ metals, 
 arts and fciences could hardly have exifted. So fen- 
 lible were the ancients of their great importance, that 
 they raifed thofc pcrfyns who firft difcovered the art of 
 working them to the rank of deities, fn chemiftry, 
 they have always filled a conlpicuous ftation : at one 
 period the whole fcience was confined to them ; and it 
 may be faid to have owed its very exiftence to 3 raj^c 
 for making and tranfmuting metals. 
 
 1. One of the moft confpicuous properties of the Liiltre. 
 metals is a particular brilliancy which they poffefs, and 
 which has been called the metallic lujtre. This proceeds 
 
 from their reflefti?ig much more light than any other 
 body ; a property which fecins to depend partly on the 
 clofenefs of their texture. This renders them peculiar- 
 ly proper for mirrors, of which they always form the 
 balls. 
 
 2. They are abfolutely opaque, or impervious to Opatit" 
 light, even after they have been reduced to very thin 
 plates. Silver leaf, for inft^nce, tttb^ss- of an inch 
 thick, does not permit the fmallell ray of hVht to pafs 
 throught it. Gold, however, may be rendered tranf- 
 parent ; for gold leaf, t-jb-'ob^ of an inch thick, tranf- 
 
 mits light of a lively green colour*. And it is not » KhhoJ 
 improbable that all the other metals, as Sir Ifaac Newton fo,}, "noi,^ 
 fuppofcd, would become tranfparent, if they could be «" f'ourcro^ 
 reduced to a fufficient degree of thinnefs. It is to tiiis 
 opacity that a part of the excellence of the metals, as 
 mirrors, is owing ; their brilliancy alone would not qua- 
 lify them for that purpofe. 
 
 3. They may be melted by the application of heat, PufiSility, 
 and even then ftill retain their opacity. This property 
 enables us to cail them in moulds, and then to give them 
 
 any fliape we pleafe. In this manner many elegant iron 
 utenfils are formed. 
 
 4. Their fpecific gravity is greater than that of any Gravitf. 
 other body hitherto difcovered. 
 
 ?. They are better condudlors of eledricity than any 
 other body. 
 
 6. But one of their moft important properties is Malleabili, 
 malleabiltty ; by which is meant the capacity of being 'X- 
 extended and flattened when ftruck with a hammer. 
 This property enables us to give the metallic body any 
 form we think proper, and thus renders it eafy for us 
 
 to 
 
 (v) This ingenious theory was firft; conceived by Dr Rutherford, as appears from the following palTage of 
 his thefis. " Ex iifdem etiam deducere licet quod aer ille malignus (azotic gas) componitur ex aere atmofbhericrt , 
 cum phlogiflo u/iito et quafifatiirato. Atque idem confirmatur eo, quod aer qui meiallorum calciiiationi jam in-.- 
 ferviit, et phlogifton ab iis abripuit, ejufJem plane fit indolis." De aere Mephitico, p. 20. 
 
 (w) Or rather of hydrogen, for he confidered carbon itfelf as a compound.
 
 CHEMISTRY. Part I. 
 
 to convert tliem into tlie various inftruments for which Were the calcination to be continued long enough to Mcud^. 
 we liave occalioii. All uu-tals do not poiL-fs tliis pro- deprive them altogether of phlogilton, they would be -^"v— ^ ^ 
 perty ; but it is remarkable that almoil ;ill thofe which reduced to the (late of other earths; and then it would ■ 
 
 60 
 
 es 
 
 of metals 
 
 were known to the ancients have it. Heat increaieti be etpially difficult to convert them into metals, or, to 
 this property confiderably. ^^^ a chemical term, to reduce them. Accordingly wt; 
 
 **. Another property which 13 alfo wanting in many find that the more completely a calx has been calcined, 
 of the metals, \% duallily ; by which we mean the capa- the more dilficult is its redudlion. This explanation 
 city of being drawn out into wire by being forced was favourably received. But after the charaCU'rillic Portlier im« 
 throuoli iioles of various diameters. This property has properties of the various earths had been afcertained.P''''*^'*" 
 by fjnie bee.i called lenacily ; and it doubtlel's depends and the calces of metals were accurately examined, it 
 upon the tenacity of the v.iiiuus metals. was perceived that the calces differed in many particu- 
 
 f- 1 ^'. • 8. When expofed to the action of heat and air, mod lars from all the earths, and from one another. To call 
 
 of the metals lofe their lullre, and are converted into them all the fame fubltance, tlien, was to go much far- 
 earthv-like powders of diiferent colours and properties, ther than either experiment or obfervation would war- 
 according to the metal and the degree of heat emplo) cd. rant, or, rather, it was to declare open war agaiiill both 
 Several of the metals even take fire when expofed to experiment and obfervation. It was concluded, there- 
 a ftron-T enough heat^; and after combuilion the refi- fore, that each of the metals was compoled of a pecu- 
 du'.im is found to ,je the very fame earthy-hke fub- liar earthy fub/lance combined with phlogifton. For 
 ftance. If any of thefe calces, as they are called, be this great improvement in accuracy, chemillry is chiefly 
 mixed " ith charcoal-powder, and expofed to a ftrong indebted to Bergman. 65 
 
 hea in a prope- vefTel, it is changed again to the metal But there were feveral phenomena of calcination Still impi 
 
 Stahl's the- from which it was produced. Froin thefe phenomena which had all this time been unaccountably overlooked, 'ed. 
 oryofthe Slahl concluded, that metals v/ere compoled of earth The calces are all confiderably heavier than the metals 
 compol'ition^j^jj y,/^/g ^(/(^_ He was of opinion that there was only from which they are obtained. Boyle had obferved 
 "'^ """"'" Qj,g primitive earth, which not only formed the bafis of this circumllance, and had afcribed it to a quantity of 
 all thofe fnbftanccs known by the name of earths, but fre which, according to him, became fixed in the me- 
 the balls rlfo of <i!! the metals. He found, however, tal during the procefs*. But fucceeding chemifts paid* Fin and 
 that it was inipufiible to combine any mere eartli with little attention to it, or to the action of air, till Mr l^a.J>'--'^c wci^i- 
 nhlo^-illon ; and concluded, therefore, with Beccher, that" voifier publiflicd his celebrated experiments on caleina-^ ' 
 there' was another princtple befides earth and phlogif- tion, in the Memoirs of the Paris Academy for 1774. 
 ton wiiich entered into the compofition of the metals. He put eight ounces of iin into a large glafs retort, the 
 To this princi')le Beccher gave the name of mercur':a! point of which was drawn out into a very (lender tube 
 earth, becaufe, accoiding to him, it exilled moll abun- to admit of eafy fulion. This retort was heated flowly 
 dantly in mercury. This principle was fuppofed to be till the tin began to melt, and then fealed hermetically, 
 very volatile, and therefore to fly off during calcination: This heat was applied to expel fome of the air from 
 and fome chemifts even aflirmed that it might be ob- the retort : without which precaution it would have ex- 
 tained in the foot of thofe chimneys under which metals panded and burft the veffel. The retort, which was 
 have been calcined. capable of containing 250 cubic inches, was then weigh- 
 
 A ftriking defeft was foon perceived in this theory, ed accurately, and placed again upon the fire. The tin 67 
 The orijrinal metal may again be produced by heating foon melted, and a pellicle formed on its top, which Uefuied by 
 its calx along vvitlpfome other fubftance which contains was gradually converted into a grey powder, that funk '-^''■"''"^'■• 
 phlofrifton : now, if the mercurial earth flies off during by a little agitation to the bottom of the liquid metal : 
 combuftion, it cannot be neceffary for the formation of in fliort, the tin was partly converted into a calx. This 
 complete metals, for they may be produced without it : procefs went on for three hours ; after which the cal- 
 if on the contrary, it adheres always to the calx, there cination flopped, and no farther change could be pro- 
 is no proof of its exiftence at all. Chemills, in confe- duced on the metal. The retort was then taken from 
 Quence of thefe obfervations, found themfelves obliged the fire, and found to be precifely of the fame weight 
 to difcard the mercurial principle altogether, and to as before the operation. It is evident, then, that no 
 conclude that metals were compoled of earth only, new fubftance had been introduced, and that therefore 
 united to phlogifton. But if this be really the cafe, the increafed weight of calces cannot, as Boyle fuppo- 
 how comes it that thefe two fubftances cannot be uni- fed, be owing to the fixation of fire (x). 
 ted bv art ? Henkel was the firft who attempted to 
 
 «3 
 
 Defeilive. 
 
 ■ *4 folve this difficulty. According to him, earth and 
 Improved ' ~ ' 
 
 When the point of the retort was broken, the air 
 rufhed in with a hiffing noife, and the weight of the 
 improved j^j^.^jfl-on are fubflances of fo oppofite a nature, that retort was increafed l>y ten grains. Ten grains of 
 ^" ^ "ft is exceedingly difficult, or rather it has been hitherto air, therefore, mull have entered, and, conlequenlly, 
 impoffible, for us to commence their union ; but after precifely that quantity mull have difappeared during 
 it has been once begun by nature, it is an eafy matter the calcination. The metal and its calx being weigh- 
 to complete it. No calcination has hitherto deprived ed, were found juft ten grains heavier than before : 
 the metals of all their phlogifton ; fome Hill adheres to therefore, the air which difappeared was abforbed by 
 the calces. It is this remainder of phlogifton which the metal : and as that part of the tin which remained 
 renders it fo eafy to reftore them to their metallic ftate. in a metallic ftate was unchanged, it is evident that this 
 
 air 
 
 (f\ This experiment had been performed by Boyle with the fame fuccefs. He had drawn a wrong conclufion 
 from not attending to the ftate of the air of the veflel. Shatu' s Boyle, II. 394.
 
 Part I. C H E M 
 
 Metals, air muft have united with the calx. The increafe of 
 ^ /""■ weight, then, whicli metals experience during calcina- 
 tion, is owing to their uniting with air (y). But all 
 the air in the veflel was not abforbed, and yet the cal- 
 cination would not go on. It is not the whole, then, 
 but feme particular part of the air which unites with 
 the calces of metals. By the fubfequent difcoven'es of 
 Prieftley, Scheele, and Lavoifier himfelf, it was afcer- 
 tained, that the reflduum of the air, after calcination 
 has been performed in it, is always pure azotic gas : It 
 follows, therefore, that it is only the oxygen which com- 
 bines with calces; and that a metallic calx is not a fimple 
 fubftance, but a compound. Mr Lavoifier obferved, 
 that the weight of the calx was always equal to that of 
 the metal employed, together with that of the oxy- 
 gen abforbed. It became a queftion then, Whether 
 metals, during calcination, loft any fubftance, and con- 
 fequently, whether they contained any phlogifton i' Mr 
 Lavoifier accordingly propofed this queftion ; and he 
 anfwered it himfelf by a number of accurate experi- 
 ments and ingenious obfervations. Metals cannot be cal- 
 cined excepting in contaft with oxygen, and in propor- 
 tion as they combine with it. Confequently they not only 
 abforb oxygen during their calcination, but that abforp- 
 tioo is abfolutely neceflary to their affuming the form 
 of a calx. If the calx of mercury be heated in a re- 
 tort, to which a pneumatic apparatus is attached, to 
 the temperature of i 200°, it is converted into pure mer- 
 
 tcury ; and, at the fame time, a quantity of oxygen fe- 
 parates from it in a gafeous form. As this procefs was 
 performed in a clofe veffel, no new fubftance could en- 
 ter : The calx of mercury, then, was reduced to a me- 
 tallic ftate without phlogifton. The weights of the 
 metal and the oxygen gas are together juft equal to 
 that of the calx ; the calx of mercury, therefore, muft 
 be compofed of mercury and oxygen ; confequently 
 there is no reafon whatever to fuppofe that mercury 
 contains phlogifton. Its calcination is merely the adi 
 of uniting it with oxygen (z). The calces of lead, 
 filver, and gold, may be decompof^d exaftly in the fame 
 manner ; and Mr Van Marum, by means of his great 
 eleftrical machine, decompofed alfo thofe of tin, zinc, 
 and antimony, and refolved them into their refpeftive 
 • Jour.Ji metals and oxygen *. The fame conclufions, therefore, 
 thy/. ijSs- muft be drawn with refpeA to thefe metals. All the 
 metallic calces may be decompofed by prefenting to 
 Suppt.VoL. I. Parti. 
 
 I S T R Y. 225 
 
 then^ fubftances which have a greater affinity for oxy- Mttali. 
 gen than they have. 1 his is th • -earoii that ciiarcoal- '""V— ' 
 powder is fo efficacious in reducing them : and if they 
 are mixed with it, and heated in a proper vcnc), fur- 
 niftied with a pneumatic apparatus, it will be cafy to 
 difcover what pafles. During the redudion, a great 
 deal of carbonic acid gas comes over, which, together 
 with the metal, is equal to the weight of the calx and 
 the charcoal : it muft therefore contain all the ingre- 
 dients; and we know that carbonic acid gas is compo- 
 fed of carbon and oxygen. During the procefs, then, 
 the oxygen of the calx combined with charcoal and 
 the metal remained behind. It cannot be doubted, 
 therefore, that all the metallic calces are compofed of 
 the entire metals combined with oxygen ; and that cal- 
 cination, like combuftion, is merely the aft of this com. 
 bination. All metals, then, in the prefent ftate of che- 
 miftry, muft be confidered as fimple fubftances ; for 
 they have never yet been decompounded. ,„ 
 
 The words calx and calcination are evidently impro- Oxide and 
 per, as they convey falfe ideas; we ftiall therefore af- oxidation, 
 terwards employ, inftead of them, the words oxiJe and*''^'- 
 oxidation, which were invented by the French chemifts. 
 A metallic oxide fignifies a metal united with oxygen ; 
 and oxidation implies the a&. of that union. 
 
 Metals are capable of uniting with oxygen in diffe- 
 rent proportions, and, confequently, of forming each 
 of them different oxides. Thefe are diftinguifhed from 
 one another by their colour. One of the oxides of iron, 
 for inftance, is of a green colour ; it is therefore called 
 the green oxide ; the other, which is brown, is called the 
 brotvn oxide. r 
 
 The metals at prefent amount to 21 ; only 11 of Number of 
 which were known before the year 1730. Their names metals, 
 are gold, filver, platinum, mercury, copper, iron, tin, 
 lead, zinc, antimony, bifmuth, arfenic, cobalt, nickel, 
 manganefe, tungften, molybdenum, uranium, telluiium, 
 titanium, ciii'omum. 
 
 The firft eight of thefe were formerly called metah 
 by way of eminence, becaufe they are pofleffed either 
 of malleability or duftility, or of both properties toge- 
 ther ; the reft were called y^«;W/j/.', becaufe they are 
 brittle. But this diftlnftion is now pretty generally 
 laid afide ; and, as Bergman obferves, it ought to be fo 
 altogether, as it is founded on a falfe hypothefis, and 
 conveys very erroneous ideas to the mind. The firft 
 F f four 
 
 the 
 
 (y) It ik remarkable that John Rey, a phyfician of Perigord, had afcribed it to this very caufe as fa^ back as 
 : year 1630 : But his writings had excited little attention, and had funk into oblivion, till after his opinion bad 
 been inconteftibly proved by Lavoifier. Mayow alfo, in the year 1674, afcribed the increafe of weight to the 
 combination of metals with oxygen ^lippe I'ix concipi potejl (lays he), unde augmentum iHud antimonii (calcinaH) 
 nifi a partiadis nitro-aereis igneifque inter calcinandum nxis procedat. Trad. p. 28. Plane lit an;im"nii fixatio non 
 tarn a fulphuris ejus externi ajjhinptione, quam particuHs nitro-aereis, quilus jlamma nitri abundat Ei ;t:FixJS prove- 
 fiire "videatur. Ibid. p. 29. 
 
 _(z) This experiment was performed by Mr Bayen In 1774. This philofopher perceived, earlier than La. 
 voifier, that all metals did not contain phlogifton. " Ces experiences (fays he) vont nous detrompcr. Je 
 ne tiendrai plus le langage des dlfcljjles de Stahl, qui feront forces de rcftreindre la dodrlne fur le phlogiftlqne, 
 ou d'avouer que les precipites mercurials, dont je parle, ne font pas des chaux metalliques, ou enfin qu'il y a 
 des chaux qui peuvent fe reduire fans le concours du phlogiftique. Les experienceii que j'ai faitcs me force' de 
 conclure que dans la chaux mercuriale dont je parle, le mercure doit fon etat calcoire, non a la perte du plylogi/liqite 
 qu'il n'a pas efiiiyee, rnais a fa comhinaifon intinie avec le fuide ehfique, dont le poids ajoute a celui du mer- 
 cure eft la feconde caufe de I'augmentalion de pefanteur qu'on obferve dann les precipites que j'ai foumis a 
 I'examen." Jour, de Phyf. 1774, pages 288, 295. It was in confequence of hearing Baycn's paper read that 
 Lavoifier was induced to turn his attention to the fubjed.
 
 226 
 
 GclJ. 
 
 TO 
 Propt rties 
 of guld. 
 
 four metals were formerly called iwhk or perfccl melals, 
 becaiifi; their oxides are reducible by the mere appli- 
 cation of heat ; the next four were imptrficl metals, be- 
 caufe their oxides were thought not reducible without 
 the addition of fome combulHble fubilance ; but this 
 diftinction alfo is now very propeily CNploded. 
 
 Sect. I. Of Gold. 
 
 Gold fcems to have been known from the very l)e- 
 glnning of the world. Its properties and its fcarcity 
 have rendered it more valuable tiuin any other metal. 
 
 It is of <in orange red, or reddifli yellow culour, and 
 has no perceptible tafle or fmell. 
 
 No other fubllanee can be compared with it in due- 
 tility and malleability. It may be beaten out into leaves 
 fo thin that one giain of gold will cover 56] iquare 
 inches. Thefe leaves are oidy ^-^^^-j^ of an inch thick. 
 But the gold leaf with which filver wire is covered has 
 only y'j of that thicknefs. An ounce of gold, upon 
 filver wire, is capable of being extended more than 1300 
 miles in length. 
 
 Its tenacity is fuch, that a gold wire -rV "^ ^" ■"'-'^ 
 in diameter is capable of fupporting a vva'ght of 500 
 
 * ATofjawV pounds without breaking*. 
 
 P'A Its hardnefs is 6(a); its fpecific gravity 19,3. It 
 
 melts at 32'' of Wedge wood's pyrometer (b). When 
 melted, it alFumes a bright bluilh green colour. It ex- 
 pands in the aft of fnfion, and confcquently contrafts 
 while becoming folid more than moil metals ; a cir- 
 cumftance which renders it lefs proper for calling into 
 moulds. 
 
 It requires a very violent heat to volatilize it ; it is 
 therefore, to ufe a chemical term, exceedingly Jixed. 
 Boyle and Kunkel kept it for fome months in a glafs- 
 houfe furnace, and yet it underwent no change : nor 
 did it lofe any perceptible weight, atter being expofed 
 
 > K'trvians for fome hours to the utmoft heat of Mr Parker's lens f . 
 
 JMinfr.i.yj.Mr Lavoifier, however, obferved, that a piece of filver, 
 held over gold melted by a fire blown by oxygen gas, 
 which produces a much greater heat than common air, 
 was fennbly ^;.V : Part of the metal, then, mull have 
 been volatilized. 
 
 After fufion, it is capable of afTiiming a cryftalline 
 form. Tillet and Mongez obtained it in iliort qua- 
 drangular pyramidal cryftals. 
 
 It is capable of combining with oxygen, and form- 
 ing an oiade of gold. There are two methods of produ- 
 cing this combination, the application of heat, 2.xiii Jolu- 
 tion in acids. When it is expofed to a very violent heat 
 
 CHEMISTRY. 
 
 ill contaft with air, gold abiorlis oxygon. 
 
 Oxidation 
 ef goUJ. 
 
 Part I 
 
 But the ^'^■'i- 
 temperature mu(l be very high ; fo high, iiukcj, that ^~-~Y~"~ 
 hardly any certain method of oxidating gold by heat 
 is known, except by cletlricity. When the eleftric ex. 
 plolion is tranfniitted through gold leaf placed between 
 two plates of glafs, or when a ftrong charge is made to 
 fall on a gilded lurface — in both cafes the metal is oxi- 
 dated, and afuiincs a purple colour. It has been faid 
 alfo, that the fame efleft has been produced by a very 
 violent five 4 but few ot the iiillances wljieh have been 
 adduced are well authenticated. 
 
 The other method of oxidating gold is much eafier. 
 For this purpole, equal parts ot nitric and muriatic 
 acids arc mixed together" (c) and poured upon gold; 
 an effervefcence takes place, the gold is gradually dif- 
 folved, and the liquid alFumes a yellow colour. It i:- 
 eafy to fee in what manner this folution is produced. 
 No metal is foluble in acids till it has been reduced to 
 the Rate of an oxide. There is a ftrong alHiiity be- 
 tween the oxide of gold and muriatic acid. The ni- 
 tric acid furnilhes oxygen to the gold, and the muria- 
 tic acid diflfolves the oxide as it forms. When nitric 
 acid is deprived of the greater part of its oxygen, it af« 
 fumes a gafeous form, and is then called nitrous gas. 
 It is the emiffion of this gas which caufes the effervef- 
 cence. The oxide of gold may be precipitated from 
 the nitro-muriatic acid by pouring in a little potafs 
 dilfolved in water, or, which is much better, a little 
 lime ; both of which have a ftronger afSnity for muriatic 
 acid than the oxide has. This oxide is of a yellow 
 colour. 
 
 It is probable that gold is capable of two different 
 degrees of oxidation, and of forming two difTeient 
 oxides, theyelloiu and the purple : But neither the quan- 
 tity of oxygen contained in thefe oxides, nor the dif- 
 ferences between them, have been accurately afcertairtd. 
 The oxides of gold may be decompofed in clofe veiTels 
 by the applicalion of heat. The gold remains fixed, 
 and the oxygen aflumes the gafeous form. They may 
 be decompofed, too, by all the fubftances which have 
 a ftronger affinity with oxygen than gold has The af- 
 finities of the oxides of gold, according to Bergman *,* Bergman 
 are as follows : 
 
 Muriatic acid, 
 
 Nitro-muriatic, 
 
 Nitric, \ 
 
 Sulphuric, 
 
 Arfeiiic, 
 
 Fluoric, 
 
 • Tartarous, 
 
 n EteBivt 
 AttraSialts, 
 Qpufc. 1,3. 
 
 (a) We have borrowed from Mr Kirwan the method of denoting the different degrees of hardnefs by figures, 
 which we think a great improvement. Thefe figures will be undcritood by Mr Kirwan's own explanation, which 
 we here fubjoin. 
 
 3, Denotes the hardnefs of chalk, 
 
 4, A fuperior hardnefs, but yet what yields to the naih 
 
 5, What will not yield-to the nail, but eafily, and without grittinefs, to the knife. 
 
 6, That which yields more difficuk'y to the knife. 
 
 7, That which fcarcely yields to the knife. 
 
 8, That which cannot be fcraped by ;i knife, but does not give fire with fteel. 
 
 9, That which gives a lev.' feeble fparks with fteel. 
 
 10, That which gives pkntiful lively fparks. Kirniian^s Mineralogy, I. 38. 
 
 (b) According to the caJculation of the Dijon academicians, it melts at 1 2980 Fahr. ; according to Bei:g- 
 man, at 1301°. 
 
 fc) This mixture, from its property of diffolving gold, was formerly called aqua regta (for gold, among the 
 alchymifts, was the king of metals) ; it is now called nitro-muriatic acid.
 
 Phofpliure 
 of gold. 
 
 * Ann. de 
 dim, i. 71. 
 
 \ lUJ.XVU. 
 104. 
 
 Part I. C H E M 
 
 Silver. Tartarouaj 
 
 *" ' • Phofphonc, 
 
 Sebacic, 
 
 Pruffic, 
 
 Fixed alkali (d), 
 
 Ammonia. 
 « Gold is not changed either by air or water. It does 
 not feem capable of combining either with fulphur or 
 carbon. Mr Pclteticr combined it with phoiphorus, 
 by melting together in a crucible half an ounce of gold 
 «^ and an ounce of phofphoric glafs (e), iurrounded with 
 charcoal. The phofphiirtt of gold thus produced was 
 brittle, whiter tlian gold, and had a cryllaUized appear- 
 ance. It was compofed of 23 parts of gold and one 
 of phofphorus *. He formed the lame compound by 
 dropping fmall pieces of phofphorus into gold in fu- 
 ll on \. 
 
 Gold is iilfo capable of combining with mod of the 
 metals. Its affinities are placed, by Bergman, in the 
 fuUowing order : 
 
 Mercury, 
 
 Copper, 
 
 Silver, 
 
 Lead, 
 
 Bifmuth, 
 
 Tin, 
 
 Antimony, 
 
 Iron, 
 
 Platinum, 
 
 Zinc, 
 
 Nickel, 
 
 Arfenic, 
 
 Cobalt, 
 
 Manganefc, 
 
 Phofphorus ? 
 
 Sulpliurets of alkalies. 
 
 Sect. II. Of SUvrr. 
 
 Silver appears to have been known almoft as early 
 as gold. It is a metal of a Ihining white colour, with- 
 out either tafte or fmell. 
 
 It is the moft malleable and duftile of all metals ex- 
 cept gold, and perhaps platinum. It can be reduced to 
 leaves about rs-a^ij^ of an inch thick, and drawn into 
 wire much finer than a human hair. 
 
 Its tenacity is fnch, that a wire of filver, tV^ °f 3" 
 inch in diameter, is capable of fuilaining 270 pounds 
 ', without breaking }:. 
 
 Its hardnefs is 6,^ §. Its fpecific gravity, before 
 hammering, is 10,474; after hammering, io,5io|| : for 
 it is remarkable that the fpecific gravity of almoft all 
 the metals is increafed by hammering. 
 
 It continues melted at 28" Wedgewood (f), but re- 
 f A'iVTOan*j<l""'^s a greater heat to bring it to fuilon ^. 
 Mineral.ii. The experiments of the French academicians have 
 107. 
 
 » 
 
 73 . 
 Properties 
 of filvcr. 
 
 j } Macqun- 
 
 i ^ Kirzvfin, 
 ! 11 Brilfan. 
 
 I S T R Y. 227 
 
 proved that it may be volatilized, but that it requires a Silver, 
 very violent heat. v ' 
 
 When cooled flowly, it afTumcs a cryftalllne form. 
 Tillet and Monge/. obtained it in quadrangular pyra- 
 midal cryllals, both infulated and in groups. »• 
 
 Silver may be combined v/itli oxygen, and converted Oxides of 
 into an oxide by expofure to a very violent luat. By tliis*''^"'- 
 method Junker partly converted it into zglafs; and Mac- 
 quer, by cxpofing it 20 times fuccefTivcly to the beat 
 of a porcelain furnace, obtained a g/nfs (g) of an olive 
 green colour *. Tiie oxide of filver may alio be formed *Min:quer'i 
 by difiblving the metal in an acid, and precipitating it ^'^• 
 from its folution by potafs, lime, &c. : for, during its 
 folution, the metal becomes oxidated. Little is known 
 at piefent concerning the oxides of filver, nor whether 
 there be more than two, the Had and the blue. From 
 the experiments of Wenzel and Bergman, it follows, 
 that one oxide of filver is compofed of about 90 jiarts 
 of metal and 10 of oxygen f. The affinities of ihc \- Kirivjn't 
 oxides, according to Bergman, are as follows : Miner, ii. 
 
 Muriatic acid, 493_> 
 
 Sebacic, 
 
 Oxalic, 
 
 Sulphuric, 
 
 Saccholadtic, 
 
 Phofphoric, 
 
 Sulphurous, 
 
 Nitric, 
 
 Arfenic, 
 
 Fluoric, 
 
 Tartaric, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Acetous, 
 
 Succinic, 
 
 rrufllc. 
 
 Carbonic, 
 
 Ammonia. 
 When filver is melted with fulphur in a low red heat, .Sulphuret 
 it combines with it and forms fulphuret of Jilver. It is of filver. 
 very difficult to determine the proportion of the ingre- 
 dients which enter into the compofition of this fub- 
 ftance, becaufe there is an affinity between filver and 
 its fulphuret, which difpofes them to combine together. 
 The greateft quantity of fulphur which a given quan- 
 tity of filver is capable of taking up is, according to 
 Wenzel, tVo t- Sulphuret of filver is of a black ox\I^''i-A^' 
 very dc^ep violet colour, brittle, and much more fufible 
 than filver. If fufficient heat be applied, the fulphur is 
 volatilized, and the metal remains behind in a ftate of 
 purity. 
 
 If one ounce of filver, one ounce of phofphoric glafs, Ph,,fphuret 
 and two drams of charcoal, be mixed together, and of filver. 
 heated in a crucible, phofphuret of filver is formed. It 
 F f z is 
 
 (d) Have the alkalies any affinity for the yellow oxide ? Is not their affinity confined to (he purple oxide 
 alone ? And does not this oxide adl as an acid ? 
 
 (e) Phofphoric acid evaporated to drynefs, and then fufed. 
 
 (f) According to the Dijon academicians, it melts at 1044° Fahr. ; according to Bergman, at iooo'-\ 
 
 (g) Metallic oxides, after fufion, are called ^/a/>, becaufe they acquire a good deal of refemblance, in fome 
 particulars, to common glafs.
 
 * PMttier, 
 Ann de 
 Ch'tm. i. 
 
 73- 
 
 \ liiJ. 3d;i. 
 
 1 10. 
 
 77 
 Alloys of 
 iilver. 
 
 i Tranjla- 
 i:on cf Wac 
 querns Ty'i£i. 
 art. Alhy. 
 
 Becf^'mes 
 tarniflied 
 by ex^o- 
 furc. 
 
 C H E M I 
 
 is of a white colour, anti appears granulated, or as it 
 were cryftalllzed. It breaks undtr the hammer, but 
 may be cut with a knife. It is compofed of four parts 
 of filver and one of phofph )rus. Heat decompofes it 
 by feparating the phofphorus *. Pelletier has obferved, 
 that iilver in fufion is capable of combining with more 
 phofphorus than folid filver : for when phofphuret of 
 iilver is formed by projefting phofphorus into melted 
 filver, after the crucible is taken from the fire a quan- 
 tity of phofphorus is emitted the moment the metal con- 
 geals f. 
 
 Silver does not feem capable of combining with car- 
 bon. 
 
 Silver is capable of combining with gold, and form- 
 ing an aUoy ( h ) compofed of one part of fdver and five 
 of gold. That this is the proportion of the ingredients, 
 was difcovercd by Romberg. He kept equal parts of 
 gold and filver in gentle fufion for a quarter of an hour, 
 and found, on breaking the crucible, two malTes ; the 
 uppermoft of which was pure filver, the undermoll the 
 whole gold combined with ^th of filver. Silver, however, 
 may be mixed with gold in almofl any proportion. But 
 there is a great difference between the mixture of two 
 fubftances and their chemical combination. Metals 
 which melt nearly at the fame temperature may be 
 mixed from that very circumftance in any proportion ; 
 but fubftances can combine chemically only in one pro- 
 portion. This obfervation, which is certainly of im- 
 portance, was firfl made, as far as we know, by Mr 
 Keir J. The alloy of filver and gold is of a greenifh 
 colour ; but its properties have not yet been accurately 
 examined. 
 
 Silver is not effefted by water, nor by expofure to 
 the air ; but Mr Prouft has remarked, that when long 
 expofed in places frequented by men, as in churches, 
 theatres, &c. it acquires a covering of a violet colour, 
 which deprives it of its luftre and malleability. This 
 covering, which forms a thin layer, can only be detach- 
 ed from the filver by bending it, or breaking it in pieces 
 with a hammer It was examined by Mr Prouft, and 
 found to be Julplmret of filver. He accounts for this 
 tranfition of the filver into a fulphuret, by fuppofing 
 
 S T R Y. 
 
 that a quantity of fulphur is con ftantly formed and ex- 
 haled by living bodies *, 
 
 The affinities of filver, according to Bergman, are as 
 follows : 
 
 Lead, 
 
 Copper, 
 
 Mercury, 
 
 Bifmuth, 
 
 Tin, 
 
 Gold, 
 
 Antimony, 
 
 Iron, 
 
 Manganefe, 
 
 Zinc, 
 
 Arfenic, 
 
 Nickel, 
 
 Platinum, 
 
 Sulphurets of alkalies. 
 
 Sulphur, 
 
 Phofphorus. 
 
 Sect. III. Of Platinum. 
 
 The metals hitherto defcribed have been known to 
 mankind from the earlieft ages, and have been always 
 in high eftimation on account of their beauty, fcarcity, 
 duftility, and indeftruftibility. But platinum, though 
 perhaps inferior to them in none of thefe qualities, and 
 certainly far fuperior in others, was unknown, as a dif- 
 tin<S metal, before the year J752 (i). 
 
 It has been found only in America, in Choco in 
 Peru, and in the mine of Santa Fe, near Carthagena. 
 The workmen of thefe mines muft no doubt have been 
 early acquainted with it ; but they feem to have paid 
 very little attention to it. It was unknown in Europe 
 till Mr Wood brought fome of it from Jamaica in 1741. 
 Soon after it was noticed by Don Antonio de UUoa, 
 a Spanifli mathematician, who had accompanied the 
 French academicians to Peru In their voyage to mea- 
 fure a degree of the meridian. In the year 1752 it 
 was examined by Scheffer of Sweden, and difcovered 
 by him to be a new metal, approaching very much to 
 the nature of gold, and therefore called by him aurum 
 
 album. 
 
 Part I. 
 
 Platinum, 
 
 ' .—-» 
 
 * Ann, di 
 ClAm. i. 
 
 79 
 Itbafiinities, 
 
 So 
 Difcovery 
 of plati- 
 num. 
 
 /h) Metals combined together are called alloys or allays. 
 
 (i) Father Cortinovis, indeed, has attempted to prove that this metal was the eleSrum of the ancients. See 
 the Chemical Annals cf Brugnatelli, 1-790. That the eleftrum of the ancients was a metal, and a very valuable 
 one, is evident from many of the ancient writers, particularly Homer. The following lines of Claudian are 
 alone fufficient to prove it : 
 
 Atria cinxit ebur, trabibus folidalur ahe/iis 
 
 Culmen et in celfas furgunt eleftra columnas. L. I. v. 164. 
 
 Pliny gives us an account of it in his Natural Hiftory. He informs us that it was a compofition of filver and 
 gold; and that by candle-light it flione with more fplendor than filver. The ancients made cups, ftatues, and 
 columns of it. Now, had it been our platinum, is it not rather extraordinary that no traces of a metal, which 
 muft have been pretty abundant, ftiould be perceptible in any part of the old continent? 
 
 As the paftage of Pliny contains the fullcft account of eledlrum to be found in any ancient author, we (hall 
 give it in his own words, that every one may have it in his power to judge whether or not the defcription will 
 apply to the platinum of the moderns. 
 
 " Omni auro inert argentum vario pondere.-^Ubicunque quinta argenti portio eft, ele8rum vocatur. Scrobes 
 eae reperiuntur in Canalienfi. Fit et cura eleftrum argento addito. Quod fi quintam portionem excelTit, incudi- 
 bus non reftitit. Et eleftro auftoritas, Homero tefte, qui Menelai regiam auro, eleftro, argento, ebore fulgere 
 tradit. Minervae templum habet Lindos infulas Rhodiorura in quo Helena facravit calicem ex eleftro. — Eleftri na- 
 tura eft ad lucernarum lumina clarius argento fplendere. ,Quod eft nativum, et venena deprehendit. Namque 
 difcurrunt in calicibus arcus coelellibus fimiles cum igneo ftrldore, et geminarationeprsdicunt."— -Z,(i.xxxiii.ffl/.iv-
 
 Part r. 
 
 platinum. 
 
 8x 
 Its proper- 
 
 ly Withering 
 
 ^ Kirivons 
 Mintr. ii. 
 103. 
 
 8i 
 Phofphuret 
 cf jJati- 
 liuni. 
 
 % Ann. de 
 Cbim. i. 7 1 
 
 j ItlJ. xiii. 
 
 8.? 
 Alloys of 
 platJEum. 
 
 C H E M 
 
 album, •white gold. Soon nftcr it was examined by Lewis, 
 Margraf, Macquer andDeaume, Morveau, Bergman, and 
 many other illuflrious chemirts. 
 
 Platinum, when pure, is of a white colour like filver, 
 but not fo bright (k). It has no tafle nor fmell. 
 
 It is both duftile and malleable ; but the prccil'e de- 
 gree has not yet been afcertained. It has been drawn 
 into a wire of t73tt of an inch in diameter. This wire 
 admitted of being flattened, and had more ftrength than 
 a wire of filver or gold of the fame fize *. 
 
 It is exceedingly difficult to fufe it. Macquer and 
 Beaume fucceeded by means of a powerful burning- 
 glafs. It melts more eafily when mixed with other 
 fubftances. Its fixity is ftill greater than its infufibili- 
 ty. If the ftrongeft fires cannot melt it, much lefs can 
 they volatilize it. 
 
 Its hardnefs is 7,5f . Its fpecific gravity, after being 
 hammered, is 23,000 ; fo that it is by far the heavieft 
 body known. 
 
 Some of tlie experiments which have been made on 
 platinum feem to prove that it may be oxidated by the 
 application of a violent heat. The oxide of this metal 
 may be eafily formed by diflblving platinum in nitro- 
 muriatic acid, and precipitating it by means of an earth 
 or potafs. The various oxides of platinum have never 
 yet been examined with accuracy. The one at prefent 
 beft known pofielTes, as Mr Bertbbllet has proved, the 
 properties of an acid. 
 
 'T\ie fulphuiet of platinum is unknown. 
 
 By mixing together an ounce of platinum, an ounce 
 of phofphoric glafs, and a dram of powdered charcoal, 
 and applying a heat of about 32° Wedgewood, Mr 
 Pelletier formed s. phofphuret of platinum weighing more 
 than an ounce. It was partly in the form of a button, 
 and partly in cubic cryftals. It was covered above by 
 a blackilh glafs. It was of a filver white colour, very 
 brittle, and hard enough to ftrike fire with fteel. When 
 expofed to a fire ftrong enough to melt it, the phof- 
 phorus was difengaged, and burnt on the furface %. 
 
 He found alfo, that when phofphorus was projefted 
 on red hot platinum, the metal inftantly fufed and 
 formed a phofphuret. As heat expels the phofphorus, 
 Mr Pelletier has propofed this as an eafy method of pu- 
 rifying platinum f . 
 
 Platinum does not feem capable of combining with 
 carbon. 
 
 It is not in the leaft affefted by the aftion of water 
 or air. 
 
 1. When gold and platinum are expofed to a ftrong 
 heat, they combine, and form an alloy of a much whi- 
 ter colour, but nearly as ductile as gold. The propor- 
 tions of the ingredients are not known. When jV on- 
 ly of the alloy is platinum, the gold is fcarcely altered 
 in colour. 
 
 2. Whether filver and platinum combine chemically 
 has not yet been properly afcertained. When fufed 
 together (for which a very ftrong heat is necelFary), 
 they form a mixture, not fo duftile as filver, but harder 
 and lefs white. The two metals are feparated by keep- 
 
 I s T R y. 
 
 ing them for fome time in the ftatc of fufion ; the pla- 
 tinum finking to the bottom from its weight. This 
 circumftance would induce one to fuppofe that there is 
 very little affinity between them. 
 
 Sect. IV. Of Mercury. 
 
 Mercury, called alfo quichfilver, was known to the 
 ancients, and feems to have been employed by them in 
 gilding. 
 
 It is of a white colour, exaftly like that of pclifhed 
 filver. It has no tafte, but acquires a flight odour wlien 
 rubbed between the hands. 
 
 Its fpecific gravity is l^,;68*. 
 
 It differs from all other metals in always exifting, at 
 the common temperature of the atmofphere, in a ftate 
 of fluidity. It freezes at -^90 f; or, which is the fame 
 thing, it ceafes to be a folid, and melts whenever it is 
 placed in a temperature above -39°. It boils at the 
 temperature of 600". 
 
 From the experiments made on frozen mercury ia 
 Ruflia, Hudfon's Bay, and Britain, we know that this 
 metal, when folid, is malleable ; but the extreme dif- 
 ficulty of examining it in that ftate, on account of the 
 lownefs of the temperature, has rendered it hitherto im- 
 poffible to afcertain the precife degree either of its mal- 
 leability, duftility, or hnrdnefs. 
 
 Mercury is capable of combining with oxygen, and 
 of forming oxides, differing from each other in the quan- 
 tity of oxygen which they contain. The oxides of mer- 
 cury, at prefent known, are the black, the jellozu, and 
 the red. 
 
 1. When mercury is agitated for fome time in con- 
 tact with oxygen gas, or atmofpheric air, it is partly 
 converted into a greyifti black powder,, and at the fame 
 time part of the oxygen difappears. This is the Hack 
 oxide of mercury. It is not known how much oxygen 
 it contains, nor even whether the whole of the mercury 
 which compofcs it be aftually combined with oxygen. 
 
 2. The beil way of forming the yellow oxide is to 
 difiolve mercury, either in boiling fulphuric acid or in 
 cold nitric acid. During its folution, it deprives thefe 
 acids of jull as much oxygen as is neceffary to convert 
 it into a yellow oxide j and if potafs or lime be after, 
 wards added to the folution, it precipitates, and may 
 be obtained pure by wafliing it with vi'ater. It is a 
 bright yellow-coloured powder, which a&s very power, 
 fully as an emetic. From the obfervations of Bergman,' 
 it appears that it is compofed of about 96,8 parts of 
 mercury, and 3,2 of oxygen J. 
 
 3. The red oxide of mercury may be prepared, either 
 by dillilling nitric acid off the metal repeatedly, or by 
 keeping mercury for a long time expofed to a heat fuffi- 
 cient to evaporate it while it is in contaft with air. 
 When formed by the firft procefs, it was formerly called 
 red precipitate; when by the IjA, precipitate per fe. It is 
 a beautiful red powdei", or rather fmall red cryftals, which 
 have fome efcharotic qualities. When prepared by the 
 fecond procefs, the heat muft not be much below Gzo" 
 uor much above 800", otherwife no union would taka 
 
 place ; 
 
 229 
 
 Mercury. 
 
 84^ 
 ProperTe* 
 of mercury, 
 
 « Brifon. 
 
 t .See Mac- 
 nab'i Ex pi' 
 riments,¥tit 
 'Ttanf. 
 
 If forms 
 tl'.ree ex. 
 ides; 
 
 The bhick 
 oxide, 
 
 Yellow 
 oxide, 
 
 \ Kirwcn^s 
 Miner, ii. 
 459. 
 
 SS 
 And red- 
 oxide. 
 
 (k) To this colour it owes its name. Plata, in Spanilli, is Jiher ; and platina, lillle fd-ver, was the name Si ft 
 given to the metal. Bergman changed that name Into platinum, that the Latin names of all the metals might have 
 tlie fame termination and gender. It was, however, fjrft czUed p/atinum by Linnaeus.
 
 230 
 Mercury. 
 
 CHEMISTRY. 
 
 Part. r. 
 
 S9 
 Their affi- 
 
 EUck ful- 
 jihurct of 
 mercury. 
 
 9' 
 Re<l ful. 
 I'huiet. 
 
 place; ami it mull be conunucd fovfome weeks. From 
 the exp.-riments of Mr Rirwan, it appears to contain 
 92,6 parts of mercury and 7,4 of oxygen*. 
 
 Thefe o.tides may be decoiiipofcd by the apph'cation 
 of a heat amounting to 1 100". The oxygen flies off 
 in the form of gas, and running mercury remains be- 
 hind. 
 
 The afSnities of tlie oxides of mercury, according to 
 Eer'-'man, are as follows : 
 
 Sebacic acid, 
 
 Miniaiic, 
 
 Oxalic, 
 
 Succinic, 
 
 Arfenic, 
 
 Phofphoric, 
 
 Sulphuric, 
 
 Btn/oic ( l) ? 
 
 Saccholadtlc, 
 
 Tartarous, 
 
 Citric, 
 
 Sulphurous, 
 
 Nitric, 
 
 Fluoric, 
 
 Zoonic (m)? 
 
 Acetous, 
 
 Boracic, 
 
 Pnlfric, 
 
 Caibonlc. 
 When two parts of mercury and three parts of flowers 
 of, fulphur are triturated for fume time together, or 
 when equal parts of mercury and melted fulphur are 
 mixed together — they combine, and form a black pow- 
 der, formerly called elh'wps mhicral, and now black ful- 
 phuret of mercury. 
 
 When 300 grains of mercury and 63 of fulphur, 
 with a few" drops of folution of potai's to moillen them, 
 are triturated for fome time in a porcelain cup by 
 means of a glafs pellle, black oxide of mercury is pro- 
 duced. Add to this 160 grains of potafs, diftolved in 
 a^ much water. Heat the vefisl containing the ingre- 
 dients over the flame of a candle, and continue the tri- 
 turation witliout interruption during the heating. In 
 proportion as the licjuid evaporates, add clear water from 
 time to time, fo that the oxide may be conllantly co- 
 vered to the depth of near an inch. The trituration 
 muft be continued about two hours ; at the end of 
 which time tlie mixture begins to change from its ori- 
 ginal black colour to a brown, which ufually happens 
 when a large part of the fluid is evaporated. It then 
 pafles very rapidly to a red. No more water is to be 
 added ; but the trituration is to be continued without 
 interruption. When the mafs has acquired the con- 
 fifl:ence of a gelly, the red colour becomes more and 
 more bright, with an incredible degree of quicknefs. 
 The iuflant the colour has acquired its ntmoil beauty, 
 the heat rnuil be withdrawn, otherwife the red pallcs 
 to a dirty brown. This red powder is the red fulphu- 
 ret of mercury, called formerly chiiiabcir, and, when re- 
 duced to a fine powder, icrmiiio/i {n). The proceis 
 
 above defcribed has been lately difcovered by Mr Kir- Mercury, 
 choff, and is by far the limpleil and ciieapell mode of"""~v~ ' 
 formiilg red fulphurct with which we are acquainted*. ' !< ichdf.n' , 
 Count De MoulFm Poufchin has difcovered, that it3 paf-7'""'''- ''■ '• 
 fin'g to a brown colour may be prevented by taking it 
 from the fire as foon as it has acquired a red colour, and 
 placing it for two or three days in a gentle heat, taking 
 care to add a few drops of water, and to agitate the 
 mixture from time to time. During tin's expofure, the 
 red colour graJnally improves, and at laft becomes ex- 
 cellent, lie difcovered alfo, that when this fulphuret 
 is expofed to a ftrong heat, it becomes inttantly brown, 
 and then paffes into a dark violet ; when taken from 
 the fire it pafles inllantly to a beautiful carmine redf. f /WY. p 7, 
 
 The difi^erencc betvvcen thefe two fulphurets lias never 
 yet been afcertained. One would ^be apt to fulpeft at 
 iirft that the black fulphuret confifts of the real fulphu- 
 ret of mercury combined with fulphur ; the red, of the 
 fulphuret of mercury combined with mercury, and that 
 the real fulphurct of mercury w?s not yet accurately 
 known. But it cannot be doubted that, during the for- 
 mation of the red fulphuret , according to Kirchoff's pio- 
 cefs, there is an abforption of oxygen. The phenomena 
 above defcribed point out that almofl: incontellibly ; and 
 we obferved, on attempting to repeat the experiment, 
 that the black fulphuret, during its trituration, emitted 
 fulphurated hydrogen gas. Perhaps, then, the mercu- 
 ry may be oxidated. We fufpefted at firfl; that part of 
 tlie fulphur might be converted into an acid ; but on 
 attempting an alteration of the procefs, in confequence 
 of that fuppofition, we could not fucceed. 
 
 The red fulphuret of mercury is found naturally in 
 feveral parts of the world. It ufed to be prepared by 
 forming a black fulphuret with three parts of fulphur 
 and one of mercury, and then fetting fire to it. Part 
 of the fulphur is burnt, and there remains behind a vio- 
 let-coloured body, which is powdered and put into a glals 
 veflel, to the bottom of which a red heat is applied. 
 A reddifll brown fubftance fublimes, which is \tA ful- 
 phuret of mercury ; but its colour is not nearly equal to 
 that which is prepared by Kirchoff's procefs. ^j 
 
 Mr Pelletier, after feveral unfuccefsful attempts to phoipiiure- 
 form phofphurct of mercury, at lafl fucceedcd by dil-ul ui"curj-. 
 tilling a mixture of red oxide of mercury and phoipho- 
 rus. Part of the phofphorus combined with the oxy- 
 gen of the oxide, and was converted into an acid ; the 
 rell combined with the mercury. 
 
 Phofphurct of mercury is of a black colour, of a 
 pretty folid confillence, and capabk of being cut with 
 a knife. When expofed to the air, it exhaled vnpours 
 of phofphorus %■ 'chiT'Ji 
 
 Mercury does not feem capable of combining with ,'^"' 
 carbon. 
 
 The combinations of mercury with the other metals [,5 ap,'ai. 
 are called amalgams, gams. 
 
 1 . The amalgam of gold forms very readily, becaufe 
 there is a very llrong affiiu'ty between the two metals. 
 If a bit of gold be dipped into mercury, its furface, by 
 combining with mercury, becomes as white as fdver. 
 
 The 
 
 (l) Benzoat of mercury is decompofed by fulphuric acid. Tronifdorf, Ann. de Chim. xi. 316. 
 
 (m) Zoonic acid decompofes the acetite of mercury. Berlhollel. 
 
 { N ) The word •vermilion is derived from the French word vermeil, which comes from "virmicnlus or -vermicu/um; 
 names given in the middle ages to the iermes or coccus ilicis, well known as a red dye. Vermilion originally fig- 
 nified the red dye of the kermes. See Beckmanifs Hijl. of JtivenUons, ii, 180.
 
 part I. 
 
 MtT'-ury. 
 
 CHEMISTRY. 
 
 Js/ott-s on 
 1>M ait, 
 
 If 
 
 I An:!, de 
 Ciii/n. xxiv, 
 
 t UiJ. 
 
 9+ 
 
 Afliniiie!. 
 
 The eaficfi; way of fonning this amalgam is to throw 
 fmall piccts of red hot gold into mercury. The pro- 
 portions of the ingredients are not eafily determined, 
 bteaiife the amalgam has an afiinity both fur the gold 
 and the meicury ; in conlequcnce of which they appear 
 to combine in any proportion. Molt probably it is 
 compufed of two piirts of gold and one of meicury. 
 The coivibination is formed mod readily in thefe pro- 
 portioiib ; and if too much mercury be addeil, it may 
 be feparated by filtration. Tlie amalgam is of a white 
 colour, and of the conlillence ol butter*. This amal- 
 gam cryftullizes in quadrangular prifms ; whicli cry- 
 rtals, accoiding to the Dijon academicians, are conipo- 
 fed of fiK jjaits of mercury and one of gold. It is 
 much uM ill gilding. 
 
 2. The amalgam of filver is lande in the fame man- 
 ner. It forms dendritical cryllal.-;, which, according to 
 the Dijon academicians, contain eight parts of mercury 
 and one of filver. Gcilert was the fn It who remarked 
 that its fpecitic gravity was greater than that ol ratr- 
 cury, though that of lilver be lefs. 
 
 3. Dr Lewis attempted to form an amalgam of pla- 
 tinum, but hardly fucceeded after a labour which lafled 
 for feveral weeks. Mr Morveau fucceeded by means of 
 heatf. But a much more expeditious method has 
 been lately difcovered by Count Mouflin Poufchin. He 
 took a dram of the orange-coloured lidt, compofed of 
 ox'ulc of platinum and ammonia (o), and triturated it 
 with an equal weight of nitrcury in a mortar of chal- 
 cedony. Ii. a few minutes the fait became brown, and 
 afterwards acquired a greenilh lliade. The matter was 
 reduced to a very fine powder. Another dram of mer- 
 cury was added, and the trituration continued : The 
 matter became grey. A third dram of mercury began 
 to form an amalgam ; and fix drains made the amalgam 
 perfeft. The whole operation fcarce laftcd 20 minutes-. 
 Mercury was added till it amounted to nine times the 
 weight of the fait, and yet the amalgam continued very 
 tenacious. It was eafily fpread out under the pellle ; 
 it received the impreffion of the moll delicate feals, and 
 had a very clofe and brilliant grain. This amalgam is 
 decompoied, and the mercury' pafTcs to the Hate of 
 black oxide iiy the fimple contaCl of feveral of the me- 
 tals and a great number of animal matters. This cffetl 
 even takes place on rubbing it between the fingers \. 
 
 The affinities of mercury, as afcertained by the expe- 
 riments of Morveau (p), are as follows : 
 
 Gold, ' 
 
 Silver, 
 
 Tin, 
 
 Lead, 
 
 Bifmuth, 
 
 Zinc, 
 
 Copper, 
 
 Antimony, 
 
 Arfenic (0> 
 
 Iron. 
 
 Sect. V. Of Coppir. 
 Except gold and fdver, copper feems to have been 
 
 more early known than any other metal. In the firft Copper. 
 ages of the world, before the metlujd of working iron ' 
 
 was difcovered, co]iper was a principal ingredient in all 
 dome'lic utcnlils and iiiih-uments of war. Lven during 
 the Trojan war, as we learn from Homer, the comba- 
 tants had no other armour but what was made of 
 bronze, which is a mixture of copper and tin. The 
 word copper is derived from the illaiid of Cyprus, where 
 it was tirft difcovered, or at leaft wrought to any ex- 
 tent, by the Greeks. 55 
 
 Copper is of a pale red colour with a fliade of yel- Propertiei 
 low. Its talle is ilyptic and naufeous ; and when vub-of 'oppsr- 
 bed it emits a difagreeable fniell. It poflefi'ts a confi- 
 dtrable degree of malleability, though lefs than filver. 
 Its tenacity is fuch, that a wire of -,'j, "f an inch in dia- 
 meter can fuilain a weight of 299J poujids without 
 breaking*. _ *Maiijuir't 
 
 Its hardnefs is 8f. Its fpecific gravity, when not Dia. 
 hammered, is 7,788 ; when wire-drawn, 8,878$. The t^^^^^ff '' 
 fpecific gravity of Japan copper is 9,000 J ; that oi^J^"' "* 
 Swediili coppt», 9,3243 ||. _ } Brijfon. 
 
 It melts at 27" Wedgcwood ; according to the cal-§ Ktirs 
 cuhtion of the Dijon academicians, at 1.^49" Fahrenheit. ^"' "", 
 When allowed to cool flowly, it affumes a cryftalllne ^^J""' 
 form. The Abbe Monge, to whom we owe many || Bergman, 
 valuable experiments on the cryilallization of metals, ii. 263. 
 informs us, that thefe cryftals are quadrangular pyra- 
 mids, frequently inferted into one another. jj 
 
 When copper is heated red hot in contaft with air, Brown 
 it is foon covered with a brown earthy crufl, which mayo^"''^ °f 
 be ealily feparated by hammering or by plunging the me-'"^^^'^'' 
 tal into water. If the heat be continued, another fcale 
 of the fame kind foon forms ; and by continuing the 
 pruccfs the whole metal may be converted into an ear- 
 thylike cnill, which ;s merely a combination of copper 
 and oxygen, and is therefore called broiun oxide of copper. 
 Ir is compofed of about 84 paits of copper and 16 of 
 oxygen*. *■ Kirwan', 
 
 When copper is diffolved in fulphurlc acid, and pre- 0.' ' 
 cipitated by means cf lime, it falls in the form of a blue- <)y 
 coloured powder, which is the blue oxide of copl/cr. If Blue and 
 this oxide of copper be dried in the open air, it anumesK''^'j'' 
 a green colour, and is then called \.\\e green oxide of cop' 
 per. I'his laft oxide may alfo be produced by diililling 
 a fufficient quantity of nitric acid off copper. Little 
 fatlsfadtory is yet known with refpedt to thefe oxides ; 
 it has not even been afcertained whether the blue and 
 green be really two difFtrent oxides, or whether the dif- 
 ference in colour be owing to fome other caulc. It is 
 probable, however, that the _j«m oxide contains more 
 oxygen than the blue ; becaufe the blue oxide affumes 
 a green colour when expofed for fome time to the open 
 air, during which it may be fuppofed to abforb oxygen. 
 An experiment of Fourcroy proves inconteftibly, that 
 the brown oxide contains lefs oxygen than the green. 
 He converted the green oxide into the brown by applying 
 heat; and during tire diftillation obtained oxygen gasf .f Fo»k«j( 
 
 Tlie affinities of the oxides of copper, according to'"" '°'- 
 Bergman, are as follows : ' y^^^ 3(5. 
 
 Pyro- mucous acid I rities. 
 
 Oxalic, \Scbrkksl. 
 
 Tartarous, 
 
 (o) .Ammonia Is an alkali hereafter to be defcribed. It is often called, in Englilh, harljhorn, 
 
 (p) We (hall have occafion to confider thefe celebrated experiments afterwards. 
 
 (ci,) Thefe two are added from Bergman. Bergman places had before tin, and zinc before bifmuth.
 
 99 
 
 Siilphiiret 
 of copper. 
 
 C H E M I 
 
 Tartarous, 
 
 Muriatic, 
 
 Sulphuric, 
 
 SaccholuAic, 
 
 Nitric, 
 
 Sc'acic, 
 
 Arfciiic, 
 
 Phofphoric, 
 
 Succinic, 
 
 Fluoric, 
 
 Citric, 
 
 Formic, 
 
 X.aAic, 
 
 Acetous, 
 
 Boracic, 
 
 Pruffic, 
 
 Carbonic, 
 
 Fixed alkalies. 
 
 Ammonia, 
 
 Fixed oils. 
 Wh-n copper is long expofed to the air, its furface 
 becomes covered over with a green cruft, which is green 
 oxide of copper. This oxidation never penetrates be- 
 yond the furface. 
 
 Copper is not attacked by water at the boiling tem- 
 perature ; but if cold water be allowed to remain long 
 on its furface, the metal becomes partly oxidated. 
 
 Sulphur mixes readily with copper. The combina- 
 tion may be formed by mixing the ingredients together 
 and applying a pretty ftrong heat. Sulphuret of copper 
 is brittle, fofter than copper, of a black colour exter- 
 nally, and within of a leaden grey. It is compofed, ac- 
 cording to Kirwan's experiments, of 8i parts of copper 
 
 • Klrvian i3Xid I 9 of fulphur*. 
 
 Mintr. ii, jj^r Pelletier formed phofphuret of copper by melting 
 5"^ ■ together one ounce of copper, one ounce of phofphoric 
 
 •Phofphuret glafs, and one dram of charcoal. It was of a white 
 of copper, colour. On expofure to the air, it loft its luftre and 
 became blackifhf. Margraf was the firft perfon that 
 formed this phofphuret. His method was to diftil 
 phofphorus and brown oxide of copper together. It 
 is formed moft eafdy by projedling phofphorus into red 
 hot copper. According to Pelletier, it contains 20 
 % mj. xiii. parts of phofphorus and 80 of copper f . This phof- 
 •3' phuret is harder than iron : It is not duftile, and yet 
 
 cannot eafily be pulverifed. Its fpecific gravity is 
 $ Sage 7,1220. It cryftallizes in tetrahedral prifms^. 
 Journ. dt j_ Copper combines readily with gold when the two 
 
 isxviii.468."'^*^'^ are melted together. The compound is of a 
 1 01 reddilli colour, more fufible than gold, but lefs duftile. 
 The proportions of the ingredients which form this al- 
 loy are not known ; nor would it be eafy to afceitain 
 them, as the two metals are almoft equally fufible. The 
 current gold of this country is compofed of 1 1 parts of 
 gold and one part of copper. 
 
 2. The alloy of copper and filver is made as eafily as 
 that of gold, and the properties are equally unknown. 
 It is harder and more fonorous than filver. The cur- 
 rent filver coin of Britain is compofed of 15 parts of 
 f:lver and one of copper. 
 
 + Ann. dt 
 Chim. i. 74, 
 
 Alloys of 
 copper. 
 
 S T R Y. Part 1. 
 
 3. Platinum combines readily with copper. The al- Iron. 
 loy is mucli more fufible than platinum ; it is duflile, • •' 
 hard, takes a fine polifh, and is not liable to tarnilli. 
 
 This alloy has been employed with advantage for com- 
 
 pofing the mirrors of reflefting tclefcopes. { 
 
 4. The amalgam of copper cannot be formed by fim- 1 
 ply mixing that metal with mercury, nor even by the 
 application of heat ; becaufe the heat necelTary to melt 
 
 copper fublimes mercury. Dr Lewis has given us fe- 
 veral procefTes for forming this amalgam. One of the 
 fimpleft is to triturate mercury with a quantity of cora- 
 moQ fait and verdigrife ; a fubftance compofed of oxide 
 of copper and vinegar. The theory of this procefs is 
 not very obvious. loi . 
 
 The affinities of copper are, according to Bergman, Its affiaitici 
 as follows : 
 
 Gold, 
 
 Silver, 
 
 Arfenic, 
 
 Iron, 
 
 Manganefe, 
 
 Zinc, 
 
 Antimony, 
 
 Platinum, 
 
 Tin, 
 
 Lead, 
 
 Nickel, 
 
 Bifmuth, 
 
 Cobalt, 
 
 Mercuiy, 
 
 Sulphuret of alkali. 
 
 Sulphur, 
 
 Phofphorus. 
 
 Sect. VI. Of Iron. 
 
 Iron, the moft abundant and moft ufeful of all the Difcovery 
 metals, was neither known fo early, nor wrought fo of iron, 
 eafily, as gold, filver, and copper. For its difcovery 
 we muft have recourfe to the nations of the eaft, among 
 whom, indeed, almoft all the arts and fciences firft 
 fprung up. The writings of Mofes (who was born 
 about 1635 years before Chrift) furnifli us with the 
 umpleft proof at how early a period it was known in 
 Egypt and Phoenicia. He mentions furnaces for work- , 
 
 ing iron*, ores from which it was extraftedf ; ^'^^u'Deai ir t- 
 tells us that fwordsj, knives J, axes||, and tools for jg. 
 cutting ftones<^, were then made of that metal. Howf ZWJ. viii. 
 many ages before the birth of Mofes iron muft have 9. 
 been difcovered in thefe countries, we may perhaps con-J^^""Jg' 
 ceive, if we rejleft, that the knowledge of iron was t LeVit. i. 
 brought over from Phrygia to Greece by the Dadlyli*, 17. 
 who fettled in Crete during the reign of Minos I. about II D«>"- 
 I431 years before Chrift ; yet during the Trojan ^'^r, "'^"^^^^jj_ 
 which happened 200 years after that period, iron was^ 
 in fuch high eftimation, that Achilles propofed a ball* Htfod, aj 
 of it as one of his prizes during the games which hequoiedby 
 celebrated in honour of Patroclus (r). At that period C''"^.'. 
 none of their weapons were formed of iron. Now if^ \- ' 
 the Greeks iu 200 years had made fo little progrtfs in 
 an art which they learned from others, how long niuft 
 
 it 
 
 Oy srpiv ^(v ptrrraaxi fjayoi tr^t^Cf HsTiMn^f 
 A\\* l»T?( Toy i-Xi^ii CTO(fa;:XBf JiOf A^iXXtv/, 
 
 r.»
 
 104 
 Vs proper- 
 ties. 
 
 Viil. 
 
 105 
 
 Form 5 two 
 oxides. 
 
 f Ann. de 
 Chim, xxiii. 
 85. and Ni- 
 tholfort's 
 ^otinial^ i. 
 
 45.i- 
 
 X M.-m. A- 
 
 caii ftjr, 
 
 I7S2. 
 
 la's 
 The r affi- 
 nities. 
 
 ^LaGran^e. 
 
 I Scbrichl. 
 
 C H E M I 
 
 it have taken the Egyptians, Phrygians, Chalybes, or 
 whatever nation firft dilcovered the art of working iron, 
 to have made that progrefs in it which vi'e find they hud 
 done in the days ot Muics ? 
 
 Iron, when frefh broken, is of a bluifh grey colour. 
 It has a llyptic taite, and emits a fmell when rubbed. 
 
 It is malleable and diittile in every temperature ; and 
 its malleability is increafed in proportion as the tempe- 
 rature augments. Its tenacity is fuch, that an iron 
 wire Vo "^ ""^ '"^'^ ■" diameter fuilains a weight of 430 
 pounds without breaking *. 
 
 Its hardnefs is fuch, that it may be eafily reduced to 
 powder by the appllcntion of a iile. Its fpecific gra- 
 vity is 7,788. It is iaiufible in the ilrongell heats hi- 
 therto produced. 
 
 It is attrafted by the magnet or loadflone, and is it- 
 felf capable of becoming magnetic ; Init it retains this 
 property only for a very ihort time. 
 
 It is not hardened by being plunged into liquids 
 while hot, nor foftened by being cooled flowly. 
 
 Iron combines with oxygen very readily. When 
 kindled in oxygen gas, it burns with great rapidity and 
 fplendor, and is in this manner converted into an oxide. 
 It is converted into an oxide alfo when iurrounded by 
 nioill air, or when plunged in water ; becaufe it has a 
 ftronger affinity for ox) gen than hydrogen has, and is 
 therefore capable of decompofing water. 
 
 Mr Prouit has lately proved, that there are only two 
 oxides of iron, the green and the broivn or reel, and that 
 all the other fuppofed oxides are merely mixtures of thefe 
 two in various proportions f. 
 
 The green oxide may be obtained by diffolving iron in 
 fulphuric acid, and then precipitating it by potafs. It 
 is a light, green-coloured, earthy-like fubftance, com- 
 pofed, as Mr Lavoifier has fhewn, of 27 parts of oxy- 
 gen, and 73 of iron %. Wlien this oxide is expofed to 
 the air, it quickly abforbs more oxygen, and is con- 
 verted into a brown powder, which i& the Ironun oxide, 
 Mr Proull lias proved that it contains 52 parts of 
 iron and 48 of oxygen. This oxide is well known 
 under the name oi riijl of iron, which is generally, how- 
 ever, or perhaps always, combined with carbonic acid 
 gas. 
 
 The affinities of thefe oxides, according to Bergman, 
 are as follows : 
 
 Gallic acid ? 
 
 Oxalic acid, 
 
 Tartarous, 
 
 Camphoric §, 
 
 Sulphuric, 
 
 Saccholaftic, 
 
 Muriatic, 
 
 Pyroraucous ||, 
 
 Nitric, 
 
 Sebacic, 
 
 Phofphoric, 
 
 Arfenic, 
 SuppL. Vol. I. Part. I. 
 
 107 
 
 S T R Y. 
 
 Fluoric, 
 
 Succinic, 
 
 Citric, 
 
 Formic, 
 
 Laflic, 
 
 Acetous, 
 
 Boracic, 
 
 Pruffic, 
 
 Cirbonic. 
 Iron unites readily with fulpl^ur. Sulphuret of iron, Sulpfiurct. 
 formerly called pyrites, is found ready formed in many 
 parts of the world. It is not eai'y to determine the 
 proportions of its ingredients, becaufe it is capable of 
 combining both with iron and fulphur, and confequent- 
 ly, if there happens to be any excefs of either during its 
 formation, it takes it up. Perhaps the proportions are 
 not far from equal parts of fulphur and of iron. It is 
 of a pale yellow or browniili colour, and is cflpable of 
 afluming a cryllalline form. Its fpeciiic gravity is a- 
 bout 4,000. When placed upon the fire it precipi- 
 tates ; and at a red heat lofes its yellow colour, and be- 
 comefi of an iron grey, excepting its furface, which is 
 of a bright red. It melts at 102° Wedgewood in a 
 covered crucible into a bluifh flag, fomewhat porous 
 internally*. When expofed to air and moifture, \.\\t'^ Klr-wan't 
 fulphur, as happens in all fulphurets, gradually abforbs •''^''"»■•"• 
 oxygen, and is conyerted into an acid. 7*- 
 
 If iron filings and fulphur be mixed together, and 
 formed into a pafte with water, the fulphur decompofes 
 the water, and abforbs oxygen fo rapidly, that the mix- 
 ture takes fire, even though it be buried under ground. 
 This phenomenon was firil difcovered by Homberg j 
 and it is conlidered as afibrdiiig an explanation of the 
 origin of volcanoes. The native fulphuret of iron has 
 been obferved more than once to take iire on being fud- 
 denly moiftened with water. 
 
 Iron combines readily with phofphorus, and forms pj,^^! 
 phojpljiiret of iron ; to which Bergman, who firil difco-rct°^ 
 vered it, gave the name o(fidcrum. 
 
 There is a particular kind of iron, known by the 
 name of coldjhort iron, becaufe it is brittle when cold, 
 though it be malleable when hot. Bergman was cm- 
 ployed at Upfal in examining the caufe of this proper, 
 ty, while Meyer was occupied at Stetin with the fame 
 inveiligation ; and both of them dilcovered, nearly at 
 the fame time, that, bjr means of fulphuric acid, a white 
 powder could be feparated from this kind of iron, whf ;h 
 by the ufual procefs they converted into a metal of a 
 dark fteel grey, exceedingly brittle, and not very fo- 
 luble in acids. Its fpecific gravity was 6,700 ; it was 
 not fo fufible as copper ; and when combined with iron 
 rendered it cold Jhort. Both of them concluded that 
 this iubftance was a new metal ; and Bergman gave it 
 the name oi fiderum. But Klaproth foon after recol. 
 lefting that the fait compofed of phofphoric acid and 
 iron bore a great refemblance to the white powder ob- 
 tained from cold fliort iron, fufpefted the prefence of 
 G g phofphoric 
 
 Toy J' ttryir (v vvtio-j-f o-utf a.\\oi7i y-TtaTttrai. 
 
 -OfVUtT^- , oi KXt TBTB af&K\J rrftptnTt^^C 
 
 Kptuf^ivoi' u /ttfy y»p 01 arf^j3ajUfvo( ys trt^n^v 
 
 Iliad, xxiii. 1. 826.
 
 • Fcllttlcr, 
 
 jinn ds 
 Chtm. I. 
 104. 
 
 CHEMISTRY. Part I. 
 
 To decide the lead it acquires this property by being immerfcd while If n. 
 
 pornriie'combiiKd phofphoric acid and iron, and oh- ignited int.. a cold liquid : for this immcriion, though ' ^ ' 
 
 iained, by heating it in a crucible along with charcoal it has no cffeft upon iron, adds greatly to the liardntfs 
 powde'rf's), a fubltance exaftly r.fcmbling the new oi Jleel. , ' rn .u ci . 1 r <r j r l 
 
 rietal Meyer when Klaproth communicated to h.m It is brittle, refifts the file, cuts glafs, affords fparks 
 
 ' ' - ' 1 r.!. ^vith flint, and retains the magnetic virtue for any length 
 
 of time. 
 
 It lofts this hardnefs by being ignited and cooled very 
 (lowly. 
 
 It melts at above 130° Wedgewood. It is malleable 
 The fulerum when red hot, but fcarcely fo when raifed to a white heat. 
 It may be hammered out into much thiimer plates 
 than iron. It is more fonorous ; and its fpecific gra- 
 vity, when hammered, is greater than that of iron. 
 
 By being repeatedly ignited in an open veffel, and 
 hammered, it becomes lurought iron*. ^ Dr Fia 
 
 Cast Iron is diftinguifhed by the following pro-/on 01; 
 perties : H'tii,tz,Fhil, 
 
 It is fcarcely malleable at any temperature. It is ge- """/• 
 nerally fo hard' as to refill the file It can neither be q^^^^ j^^jj 
 hardened nor foftened as Heel can by ignition and cool- 
 ing. It is exceedingly brittle. It melts at 130° Wedge- 
 wood. It is more fonorous than fteel -|-. | JiW, 
 crucible it may De lormeo aiio uy u,e.j,i..„g ........ Caft iron is converted into wrought iron by expofing it 
 
 f IJ.Ann. bits of phofphorus into iron filincrs heated red hot f. for a confiderable time in a furnace to a heat lufficiently 
 df Cb.m. Tjjg proportions of the ingredients of this phofpuret ftrong to melt it. During the procefs it is conftantly 
 """'■ "3- have not yet been determined. fti"-^d by a workman, that every part of it may be 
 
 And?arhu. Iron likewife combines with carbon, and forms a equally expofed to the air. In about an hour the hot- 
 Tctofircn. carluret Carburet of iron has been long known and teft part of the mafs begins to heave and iwell, and to 
 ufed in the arts under the names of plumbago and black emit a h-mbent blue flame. This continues nearly an 
 kad It i"! of a dark iron grey or blue colour, and has hour; and by that time the converfion is completed, 
 {omething of a metallic luftre. It has a greafy feel, and The heaving is evidently produced by the emiffion of an 
 blackens the fingers, or any other fubftance to which it elaftic fluid J. . j • , n , , , ■ l^'ft"' ~ 
 
 is applied It is found in many parts of the world, ef- Wrought iron may be converted into fteel by being Ph,!. Tranj. 
 
 reciallv in En-land, where it is manufaftured into pen- kept for fome hours in a ftrong red heat, furrounded '/i^'- 
 cils it is not^ffefted by the moft violent heat as long with charcoal powder in a covered crucible. By this 
 as air is excluded, nor is it in the leaft altered by fimple procefs, which is called cementatton, the iron gams iome 
 txpofure to the air, or to water. Its nature was firft weight. ,-, r- , , , , "■» 
 
 inveftitrated by Schede ; who proved, by a very inge- Thefe different kinds of iron have been long known, Caufc ot 
 nious analvfis that it could be converted almoft wholly and the converting of them into each other has been thele va- 
 into carbonic'acid e?E, and that the fmall refiduum was praaifed in very remote ages. Many attempts have ■■'""=■•■ 
 iron It follows fr^om this analyfis, that it is compofed been made to explain the manner in which this conver- 
 cif -arbon and iron ; for the carbon, during its combuf- fion is accompllihcd. According to Pliny, fteel owes 
 tion had been converted into carbonic acid gas. By its peculiar properties chiefly to the water into which it 
 the fubfcquent experiments ofPelletier and other French is plunged in order to be cooled §. Beccher fuppofed^ ^/;„,_ 
 chemifts, it has been fliewn to confift nearly of nine that tire was the only agent; that it entered into the 1. xxiiv. 14. 
 
 phofphoric acid in this n<w metal. 
 
 this difcovcry, informed him that he had already fatis- 
 fied himfelf, by a more accurate examination, that fide- 
 ram contained phcl'plwric acid. Soon after this Scheele 
 adually decompofed the white powder obtained from 
 cold Ihort iron, and thereby demon llrated, that it was 
 compofed of phofphoric acid and iron. The fiderum 
 of Bergman, however, is compofed of phofphorus and 
 iron, the phofphoric acid being deprived of its oxygen 
 during the red,i3ion ; or it is phofphuret of iron. It 
 may be formed by fufing in a crucible an ounce of phof- 
 phoric gkfs, an ounce of iron, and half a dram of char- 
 coal powder. It is very brittle, and appears white when 
 broken. When expofed to a ftrong heat, it melts, and 
 the phofphorus is dirHpated *. It may be formed alio 
 by meltlag-to;;ether equal parts of phofphoric glals and 
 iron filings. Part of the iron combines with the oxy 
 gen of the phofphoric glafs, and is vitrified ; the reft 
 forms the phofphuret, which finks to the bottom of the 
 crucible. It may be formed alfo by dropping fmall 
 
 110 
 Varieties 
 of iroii. 
 
 Ill 
 ■Wrought 
 irDO. 
 
 Ill 
 £toeL 
 
 parts of carbon to one of iron. 
 
 There are a great many varieties of iron, which ar- 
 tifts diftinguifti by particular names ; but all of them 
 may be re'duced under one or other of the three follow, 
 ing ftates : Wrought iron (or fimply iron),Jieel, and cajl 
 
 or raw iron. 
 
 Wrought Ihon is the fubftance which we have been 
 hitherto defcribing. As it has never yet been decom- 
 pounded, we confider it when pure as a fimple body ; 
 but it has feldom or never been found without fome 
 
 iron, and converted it into fteel. Reaumur was the firft 
 who attended accurately to the procefs; and his nume-- 
 rous experiments have certainly contributed to elucidate • 
 the fubjcft. He fuppofed that iron was converted in- 
 to fteel by combining with faline and oily or fulphure- 
 ous particles, and that thefe were introduced by the 
 fire. But it was the analyfis of Bergman, publifhed in 
 1781, that firft paved the way to the explanation of 
 the nature of thefe different fpecies of iron. 
 
 By diflblving in diluted fulphuric acid lOO parts of caft 
 
 fmall mixture of foreign fubftances. Thefe fubftances iron, he obtained 40 ounce meafures of hydrogen ; from 
 are either fome of the other metals, or oxygen, carbon, joopartsof^fteel he obtained 48 ounce meafures; and from 
 or phofphorus 
 
 100 parts of wrought iron, 50 ounce meafures. Now as 
 St EELirdiftinguiflied from iron by the following the hydrogen is produced by the property which iron has 
 
 . of decompofing water and uniting with its oxygen, it is 
 
 ^"^°It is fo'hard as to be unmalleable while cold, or at evident that the greater the quantity of hydrogen ob. 
 
 tained, 
 
 (s) ThiB procefs in chemiftry is called redudion.
 
 Parti. C H E M 
 
 Iron, tained, with the more oxygen does the iron combine. 
 
 *■■ « But the quantities of iron were equal ; they ought 
 
 therefore to have combined with equal quantities of oxy- 
 gen. But it is evident, from the quantities of hydro- 
 gen obtained, that the caft iron received lefs oiiygcn 
 than either of the other two : call iron therefore mull 
 contain already fome oxygen, fmce it requires leis than 
 the other two fpecies in order to be faturated. Here 
 then is one difference between caft iron and the other 
 two kinds ; it contains oxygen. Steel, on the contrary, 
 does not appear to contain any oxygen. The difference 
 between the quantity of hydrogen produced during its 
 folution and that of wrought iron, which contains no 
 oxygen, is exceedingly fmall, and it has been found to 
 diminllh in proportion to the purity ot the ileel. 
 
 From lOO parts of call iron Bergman obtained 2,3 
 of plumbago, or -j'^ ; from loo parts of fteel, 0,5, or 
 ^^ ; and from 100 parts of wrought iron, 0, 12, or 
 ■g-3^. Now plumbago is compofed of T%ths of carbon; 
 caft iron therefore contains a confiderable quantity of 
 carbon, fteel a fmaller quantity, and wrought iron a ve- 
 ry minute portion, which diminilhes according to its pu- 
 rity, and would vanilh altogether if iron could be ob- 
 tained perfedlly pure. Mr Giignon, in his notes on this 
 analyfis, endeavoured to prove that plumbago was not 
 effentially a part of call iron and fteel, but that it was 
 merely accidentally prefent But Bergman, after conli- 
 dering his objeftions, wrote to Morveau on the 1 8th No- 
 vember 1783. " I will acknowledge my miftakc when- 
 ever Mr Grignon fends me a fmgle bit of call iron or fteel 
 which does not contain plumbago; and I beg of you, my 
 dear friend, to endeavour to dilcover fome fuch, and to 
 fend them to me ; for if I am wrong, I wi(h to be unde- 
 ceived as foon as poffible*." This was almoft the lall 
 adlion of the illuftrious Bergman. He died a few months 
 after at the age of 49, leaving behind him a moft bril- 
 
 mu, 1. 44S. jj^jjj. reputation, which no man ever more dcfervedly 
 acquired. His induftry, his indefatigable, his aftonifli- 
 ing induftry, would alone have contributed much to ef- 
 tablifh his name ; his extenfive knowledge would alone 
 have attrafted the attention of philofophers ; his inge- 
 nuity, penetration, and accurate judgment, would alone 
 have fecured the applaufe ; and his candour and love of 
 truth procured him the confidence aod the efteem of 
 the world. — But all thefe qualities were united in Berg- 
 man, and confpired to form one of the greatell men and 
 cobleft charafters that ever adorned human nature. 
 
 The experiments of Bergman were fully confirmed 
 by thofe of Morveau, Vandermonde, Monge, and Ber- 
 thollet, who have likewife thrown a great deal of addi- 
 tional light on the fubjeft. From all thefe e.iperiments 
 the following deduAions may be made. 
 
 Wrought iran is a fimple fubilance, and if perfeftly 
 pure would contain nothing but ii'on. 
 
 Steel is iron combined with carbon. Tlie proportion 
 of this laft ingredient has not vet been afcertained ; Dr 
 Pearfon fixes it at y^^th part at a medium. Steel, in 
 confequence of its compofition, has been called by fome 
 chemifts carburet of iron ; but before affigning it that 
 name, which has been alfo given to plumbago, it ought 
 to be determined what are the proportions of carbon 
 and iron which faturate each other. Is it the propor- 
 
 JJ 
 
 Iron. 
 
 * Moyjeau 
 £ncyct. ''i4e- 
 tbod. Chi 
 
 I S T R Y. 
 
 tion in which thefe two fubf^ancfs exift I'n fteel, or thit 
 
 which forms plumbago? In tlji- firll cafe, plumb.igo is ' ' 
 carburet of iron combined with carbon ; in the fecond, 
 fteel is carburet combined with iron. Or is it fome in- 
 termediate proportion ? Till thtfe points be determined, 
 perhaps it would be better to continue the old name* 
 than to rifle the impofing of fnlfc ones. 
 
 Cnjl iron is iron contaminated with various foreign 
 fubftances, the proportions of which vary according to 
 circumftances. Thefe fubftances are chiefly oxide ot 
 iron and carbon, and fometimcs filica (t). 
 
 Bergman found a quantity of manganele in the iron 
 and fteel which he examined ; but it appears from the 
 experiments of Vauquclin, that his method of determi- 
 ning the prefence of that metal was not accurate. 
 
 Mr Vauquelin * has lately analy fed four kinds of fteel * 7^"'- ''■" 
 with ereat care, and contrived his procefTes with much ^''V',r^?^ 
 
 °. _,, . , ri • 1 r • r 11 l^ieholfin s 
 
 ingenuity. The refult ot his analyfis is as tollows : Journal, i. 
 
 rCavbon, - o,co7?9 ' j,. 
 
 Fi. ft fteel, compofed of ] ^^''f', * °'°^^ ' ^ ^^""5"'-, 
 
 ' '^ ) Phofphorus, - 0,003451111 s anily- 
 
 (.Iron, - - 0,9855 1 fi'o'""'- 
 
 r Carbon, 
 
 Second fteel, compofed of ■< 'X, ;- ', 
 
 ' ' 1 Phofphorus, 
 
 (.Iron, - 
 
 Third fteel, compofed 
 
 rCarboi 
 r 1 Silica, 
 °M Phofpl 
 Liron, 
 
 Carbon, 
 :a, 
 fphorus, 
 
 o,co68j 
 0,0027 J 
 0,00827 
 0,98217 
 
 0,00789 
 0,00315 
 
 0,00791 
 0,98105 
 
 {"Carbon, 
 ica. 
 
 Fourth fteel, compofed of j pi'^'^phorus, 
 (_Iron, - 
 
 0,00631 
 0,00252 
 0,01520 
 0,97597 
 
 It cannot be concluded from thefe experiments that 
 all fteel contains phofphorus and filica ; far lefs that 
 thefe fubftances enter neceflarily into the compofition 
 of fteel. This may be the cafe, and former analyf'es may 
 not have been nice enough to detedl it ; but before it 
 can be admitted, it mutt be fliewn that taefe fubftances 
 are always prefent in heel, ai.d th.it it lofes its eflential 
 properties when deprived of them. 
 
 Iron combines with moll metals. j,g 
 
 1. The alloy of gold and iron is very hard, and might,, Alloys li" 
 according to Dr Lewis, who examined it, be eniphjycd'ron. 
 with advantage in forming cutting Inftruments. 
 
 2. That iron cumbiiies with filver is certain, but 
 hardly any thing is known about the nature of the 
 compound. 
 
 3. Platinum is ufually found alloyed with iron. Dr 
 Lewis did not fucceed in his attempts to unite thefe 
 
 C 
 
 metals 
 
 (t) An earth which fliall be defcribed in the next chupter.
 
 Cbim. Vi. 
 39- 
 
 C H E M I 
 
 metals by fufion, but he melted together cad iron and 
 platinum. The alloy was exceflively hard, and poflefled 
 
 duAility. 
 
 4. There is very little affinity between iron and mer- 
 cury ; they cannot therefore he amalgamated by fimple 
 mixture, even with the afhltance of heat. Vogel affirms 
 that he has produced an amalgam of iron by the follow- 
 ing procefs : Pound one part of iron filings and two 
 parts of alum in a mortar to a fine powder ; then pour 
 in two or three parts of mercury, and triturate till the 
 fubltances be thoroughly mixed. Pour on a little wa- 
 ter, and continue the trituration for about an hour. If 
 then no particles of iron can be diftinguilhed, pour on 
 a little more water to walh out the alum, and then dry 
 the amalgam. If particles of iron be perceptible, the 
 * Ann. ic trituration muft be continued till they difappear *. 
 
 5. Iron may be united to copper by fufion, but not 
 without confiderable difficulty. The alloy has been ap- 
 ii» plied to no ufe. 
 UsaSinities. The affinities of iron, according to Bergman, are as 
 follows : 
 
 Nickel, 
 
 Cobalt, 
 
 Manganefe, 
 
 Arfenic, 
 
 Copper, 
 
 Gold, 
 
 Silver, 
 
 Tin, 
 
 Antimony, 
 
 Platinum, 
 
 Bifmuth, 
 
 Lead, 
 
 Mercury, 
 
 oulphuret of alkali, 
 
 Carbon ? 
 
 Phofphorus ? 
 
 Sulphur ? 
 
 Sect. VII. Of Tin. 
 
 The Phenicians were the firft of thofe nations whicii 
 make a figure in ancient hiftory that were acquainted 
 t Ptiny, 1. with tin. They procured it from Spain f and from Bri- 
 <■ c- 34- tain, with which nations they carried on a very lucra- 
 tive commerce. At how early a period they imported 
 this metal we may eafily conceive, if we recollect that 
 it vi-as in common -uie in the time of Mofes |. 
 
 Tin is of a greyltli white colour : it has a ftrong dif- 
 agrceable tafte, and emits a peculiar Imell when rub- 
 bed. 
 
 It is very malleable ; tin -leaf, or iinfcil as it is called, 
 is about T33oth part of an inch thick, and it might be 
 beat out into leaves as thin again if fuch were wanted 
 for the purpofes of art. Its duftility, however, is ex- 
 ceedingly imperftdl ; for a tin wire -j-'oth of an inch in 
 diameter, is capable of fupporting only 49 pounds with- 
 5 MffcjMcr jQut breaking J. It is very flexible, and produces a crack- 
 
 I lonary. \\^„ noife when bended. 
 Miner.ii. I's hardnefs is 6 ||. Its fpecific gravity is 7,291 ; 
 
 X95. after hammering, 7,299 ^f. 
 
 ^Jirijjhn. It melcs at the temperature 410", according to Dr 
 
 yorir"/ Lewis ; according to the Dijon academicians, at 419°. 
 yiiy/. When heated red hot in clofe veflels it fublimes. It 
 
 juxviii. j3. cryllallizes in the form of a rhomboidal prifm*. 
 
 •ind 1. 34. c 
 
 47- 
 
 J Numbers, 
 
 XXxi. 2 2. 
 
 ij8 
 Properties 
 of tin : 
 
 S T R Y. Part I. 
 
 Tin unites very readily with oxygen. When heated 'J'm 
 in contaft with air, its furface foon becomes covered *■""*■ 
 with a grey pellicle ; when this is taken off, another qj^j, 
 appears ioou after; and in this manner the whole metal 
 may be converted into a dirty grey powder, which is 
 the grey oxide of tin. It is compofed, according to 
 Fourcroy, of 90 parts of tin and 10 of oxygen. 
 
 When tin is heated red hot in contact with air, it 
 takes fire *, and burns with a very lively white flame, and * Geoffrey. 
 is gradually fubhmed. If the I'ublimate be examined, 
 it is found to confift of a white powder ; it is the <zvhile 
 oxide of tin. The white oxide is perhaps never obtained 
 quite pure by this procefs ; it feems always to contain a 
 mixture oi grey oxide : but it may be obtained pure by 
 pouring nitric acid upon tin, and then drying it. That 
 metal having a much Itronger attraction for oxygen 
 than azot has, decompofes the acid with the greatell 
 rapidity, and afiumes the appearance of a white powder, 
 which is the while oxide. This oxide poft'cfies many of 
 the properties of an acid, and is therefore often called 
 flannic acid. It feems to confift of about 77 parts of tin 
 and 2^ of oxygen \. t Kir-.van's 
 
 The affinities of the grey oxide of tin, according to ^l^""' "■ 
 Bergman, are as follows : 
 
 Pyromucous acid +, \^ih,khJ, 
 
 Sebacic acid, 
 
 Tartaric, 
 
 Muriatic, 
 
 Sulphuric, 
 
 Oxalic, 
 
 Arfenic, 
 
 Phofphoric, 
 
 Nitric, 
 
 Succinic, 
 
 Fluoric, 
 
 Saccholaftic, 
 
 Citric, 
 
 Formic, 
 
 Ladtic, 
 
 Acetous, 
 
 Boracic, 
 
 Pruffic. 
 
 Tin combines readily with fulphur. This fulphuref s.i!j]hiiret9, 
 may be formed by fufing the two ingredients together. 
 It is brittle, heavier than tin, and not fo fufible. It is 
 of a bluifh colour and lamellated ftrufture, and is ca- 
 pable of cryftallizing. According to Bergman, it is 
 compofed of 80 parts of tin and 20 of fulphur ; accord- 
 ing to Ptlletier, of 8 1; parts of tin and 15 of fulphur ^. 5 /^/,„.cV 
 
 Sulphur likewife combines with t lie white oxide of C'Ww. xiii. 
 tin, by mixing them together, and applying a gentle^ '" 
 heat |l. This compound has been called mirum mufivum. n Peii,i;tr 
 It is a mafs confifting of beautiful gold-coloured flakes, W;W. p. 297. 
 and is ufed as a paint. It is compoled of about 40 parts 
 of fulphur and 60 of white oxide of tin ^. The [irocefs \ ibid. 253. 
 for making this fubftance w;:s formerly very complica- 
 ted. Pelletier firft demonftrated its real compofition, 
 and was hence enabled to make many important im- 
 provements in the manner of manufafturing it *. * See his 
 
 Phofphorus is eafily combined with tin, by melting in "^"""'"t.. 
 a crucible equal parts of filings of tin and phofphoric ^;^y^^ j^jy 
 glafs. Tin has a greater affinity for oxygen than phof-ii;:o. 
 phorus has. Part of the metal therefore combines with m 
 
 the Phofi bu- 
 ret. ,
 
 * Attn, dt; 
 ChiiR, xii'. 
 116. 
 Ill 
 
 Alloys, 
 
 Part I. CHEMISTRY. 
 
 Tin. the oxygen of the jjlafs during the fiifion, nnd flies ofF 
 » in the (late of an oxide, nnd the reft of the tin combines 
 
 with the phofphorus. The phofphuret of tin may he 
 cut with a knife ; it extends under the hammer, btit fe- 
 parates in laminx. When newly cut it has the colour 
 of filver ; its filings refemble thofe of lead. When thei'e 
 filings are thrown on burning coals, the phofphorus 
 takes fire. This phofphuret may likewife be formed by ' 
 
 droppinjr phofphorus gradually into melted tin. Ac- 
 cording to Pclletier, to whofe experiments we are in- 
 debted for the knowledge of all the phofphurcts, it is 
 compofed of about 85 parts of tin and 15 of phofpho- 
 rus*. Margraf alfo formed this phofphuret, but he 
 was ignorant of its compofitiou. 
 
 Tin does not fcm capable of combining with car- 
 boil. It is capable of combining with mod of the me- 
 tals. 
 
 1. It mixes readily with gold by fufion ; but the 
 proportions in which thefe metals connbine chemically 
 are ftill unknown. When one part of tin and twelve 
 of gold are melted together, the alloy is brittle, hard, 
 and bad coloured. Twenty-four parts of gold and one 
 of tin produce a pale coloured alloy, harder than gold, 
 but pofTeffed of confiderable duftility. Gold alloyed 
 with no more than yV^h of tin is fcarcely altered in its 
 
 f Aldarm, properties, according to Mr Alchornef ; but MrTillet, 
 IbiUirciJ. ^jjg ]jgg lately examined this alloy, found, that when- 
 ever it was heated it broke into a number of pieces. 
 
 2. The alloy of filver and tin is hardly known. Ac- 
 cording to Gellcrt and fucceeding chemills, it is exceed- 
 ingly brittle. 
 
 3. The alloy of platinum and tin is very fufible and 
 brittle, at leaft when thcie metals are mixed in equal 
 
 } Dt le-j. '^.proportions J. 
 
 4. Mercury diffolves tin very readily, by being pour- 
 ed on it when melted. This amalgam cryftallizes in the 
 form of cubes, according to Darbenton ; but, accord- 
 ing to Sage, in grey brilliant fquare plates, thin to- 
 wards the edges, and attached to each other fo that the 
 cavities bttween tbem are polygonal. It is compofed of 
 three parts of mercury and one of tin. The amalgam 
 of tin is ufed to filver the backs of glafs mirrors. 
 
 5. Tin unites very readily with copper, and forms al- 
 loys known by the names oi bronze and bell-metal. The 
 proportions of the ingredients cannot eafily be afTifrncd, 
 perhaps becaufe the alloy has an affinity both for copper 
 and tni. The fpecific gravity of the alloy in all propor- 
 tions is greater than the mean fpecific gravity of the two 
 metals feparately. When the quantity of tin is fmall com- 
 pared to that of the copper, Tsth for inllance, the alloy 
 is called bronze ; it is brittle, yellow, and much heavier 
 than copper; much more fufible, and iefs liable to be al- 
 tered by expofure to the air. It was this alloy which tlie 
 ancients ufed for fharp-edged inftruments before the me- 
 thod of working iron was brought to perfeftion. The 
 ;^^a\K9!- of the Greeks, and perhaps the as of the Ro- 
 mans, was nothing elfe. Even their copper coins con- 
 tain a mixture of tin §. 
 
 6. Tin feems capable of being united to iron by fu- 
 fion. That there is an affinity between thefe metals is 
 
 Piyf. 1790. evident from their adhefion when iron is dipt into mclt- 
 123 ed tin. This is the method of making tinplate. 
 
 Zinc, 
 
 Mercury, 
 
 Copper, 
 
 Antimony, 
 
 Gold, 
 
 Silver, 
 
 Lead, 
 
 Iron, 
 
 Mangancfe, 
 
 Nickel, 
 
 Arfenie, 
 
 Platinum, 
 
 Bifmuth, 
 
 Cobalt, 
 
 Sulpluiret of alkali, 
 
 Oxygen ? 
 
 Sulphur ? 
 
 Phofphorus ? 
 
 5 See 
 Dizc'i A- 
 
 tiLiiyftSy 
 "Jour, de 
 
 Andaffim- The affinities of tin, according to Bergman, area 
 Iks ot tin. r n a a > 
 
 Sect. V] II. Of Lead. 
 
 Leid appears to have been veiy early known. It is 
 mentioned feveral times by Mofes. The ancients feem 
 to have confidered it as nearly related to tin. 
 
 Lead is of a bluifii white colour, fomewhat darker p^g"^;- 
 than tin. When newly melted it is very bright, but of lead, 
 foon becomes tarnifiied bv expofure to the air. It has 
 fcarcely any tatte, but emits on friftion a peculiar fmell. 
 
 It is very malleable, and may be reduced to thin 
 plates by the hammer ; but its duAility is very im- 
 perfect : a wire of lead -r'otli of an inch in diameter is 
 only capable of fupporting a weight of 2ij\ pounds*. * Mucjrm'j 
 
 Its hardncfs is 5-f ; its fpecific gravity is i 1,3523:!:. 'J'^''""'"-}'; 
 
 Its fpecific gravity is not increaftd by hanimerintr, nei. t/"'""''" 
 .1 • , •. 1 I , . , •' ^ . , ,t>' Miner, n. 
 
 ther eioes it become harder, as is the cafe with other me-ao2. 
 
 tals : a proof that the hardnefs vshich metals alfume un-{ Bnjtn. 
 der the hammer is in confequence of an incrcafeof denfity. 
 It melts, according to Dr Lewis, at 540° Fahrenheit; 
 according to the Dijon academicians, at 549^ When 
 expofed to a violent heat it evaporates completely. 
 
 When cooled (lowly, after being fufed, it cryftallizes. 
 The Abbe Mongez obtained it in quadranguhir pyra- 
 mids, lying on one of their fides. Each pyrr.inld was 
 compofed as it were of three layers. Pajot obtained it 
 in the form of a polyhedron with 32 fides, formed by 
 the concourfe of fix quadrangular pyramids^. r rr^^ , 
 
 Lead ftains paper or the fingers of a bluilh black co-I'hv/. ' 
 lour. xxxviii, 5j. 
 
 There is a (Irong affinity between this metal and oxy- '*' 
 gen. When nitric acid is poured upon it, an effervef. " ''^'"''• 
 cence enfues, owing to the decompofition of the acid ; 
 the lead feizes oxygen from it, and is converted into a 
 white powder, which may be obtained pure by evapo- 
 rating it to drynefs, and then wafliing it in pure water. 
 This is the luhile oxide of lead. It is compofed of about 
 95 parts of lead and five of oxygen ||. The aflrnities|| Klrwan'! 
 of this oxide are, according to Bergman, as follows : Miner, ii.. 
 
 Sulphuric acid, 4J9' 
 
 Sebacic, 
 
 Saccholadlic, 
 
 Oxalic, 
 
 Arfenie, 
 
 Tartarous, 
 
 Phofphoric, 
 
 Muriatic, 
 
 ' ■ ■ Benzoicj
 
 <238 
 
 Levi. 
 
 Benzoic (u) ? 
 ■ ■ » Siilpliurous, 
 
 Suberic ?1 / v 
 
 Zoonic > I ^''' 
 
 Nitric, 
 
 Pyroniucous (v) ? 
 
 Fluoric, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Acetous, 
 
 Boracic, 
 
 Prufilc, 
 
 Carbonic, 
 
 Fixed alkali. 
 When lead is expofed to heat in contaft with air, its 
 furface is foon covered with a grey pellicle ; when this 
 is taken off, another foon forms : and in this manner 
 the whole lead may foon be converted into a dirty grey 
 powder, which feems to be the white oxide mixed with 
 a little lead. When this powder is heated red hot, it af- 
 fumcs a deep yellow colour. This is t.\\t yellow oxide oi 
 lead, formerly called majjicot. If the heat be continued, 
 the colour is gradually changed to a beautiful red. This 
 is the red ox'ule of lead, formerly called mi/iium. It is 
 conipofed, as Lavoifier has (hewn, of 88 parts of lead 
 * ATcn:. and 1 2 of oxygen *. 
 
 Par. J7Si. The manner in which thefe changes are brought 
 about is evident ; the metal gradually abfovbs oxygen 
 from the atmofphcre. This has been aftually proved 
 by experiment. Thefe oxides (if they really differ in 
 the proportion of oxygen) refemble acids in feveral of 
 their properties. They are very eafily converted into 
 glafs by fufion. Scheele has fhewn that there is alfo a 
 iroti'i! oxide of lead, which contains more oxygen than 
 ii6 any of the others. 
 Suljihuret, Sulphur unites eafily to lead by fufion. The fulphu- 
 ret of lead is brittle, of a deep grey colour, and much 
 Itfs fuiible than lead. Thefe two fubftances are often 
 found naturally combined ; the compound is then called 
 galena. Sulphuret of lead is compofed, according to the 
 experiments of Wenzel, of 868 parts of lead and 132 
 ^ Kirtvanj of fulphurf. 
 
 Mhiir. ii. Phofphuret of lead may be formed by mixing toge- 
 ^^^' ther equal parts of filings of lead and phofphoric glafs, 
 
 Phofphu- ''"'^ fufuig them in a crucible. It may be cut with a 
 rtt, knife, but feparates into plates when hammered. It is 
 
 of 3 white filver colour with a (hade of blue, but it foon 
 tarni(hes when expofed to the air. This phofphuret 
 may alfo be formed by dropping phofphorus into melt- 
 ed lead. It is compofed of about 12 parts of phof- 
 % Pellitisr, phorus and 8b of lead J. 
 "f?"' *... Lead combines with mod of the other metals. 
 
 ' ' I. Little is known concerning the alloy of lead and 
 128 gold. It is faid to be brittle. 
 Alloys, an i 
 
 CHEMISTRY. Part I. 
 
 2. The alloy of filver and lead is very fufible, and t.t:.d. 
 
 neither elallic nor fonorous 
 
 3. Platinum and lead unite in a ftrong heat 
 
 the 
 
 ' Fourcre^\ 
 
 loy is brittle, of a puiplifh colour, and foon changes on 
 expofure to the air *. 1 
 
 4. Mercury, when poured upon melted lead, dlffolves 
 it' readily. The amalgam is white and brilliant, and 
 alTumes a folid form. It is capable of cryftallizing. 
 The cryftals are compofed of one part of lead and one 
 
 and a half of mercury f. f nij^n A- 
 
 5. Copper and lead combine eafily by fufion ; but the '"dimUian^ 
 alloy has not been apphed to any ufe. J 
 
 6. Iron does not unite with lead. ^ 
 
 7. Lead and tin may be combined by fufion. The 
 alloy in the proportion of two parts of lead and one of 
 tin is more foluble than either of the metals feparately. 
 
 It is accordingly ufed by plumbers as a folder. jj. 
 
 Lead, when taken internally, adls as a poifon. Its Afl5mtie* 
 affinities, according to Bergman, are as follows : 
 
 Gold, 
 
 Silver, 
 
 Copper, 
 
 Mercury, 
 
 Bifmuth, 
 
 Tin, 
 
 Antimony, 
 
 Platinum, 
 
 Arfenic, 
 
 Zinc, 
 
 Nickel, 
 
 Iron, 
 
 Sulphuret of alkali, 
 
 Sulphur, 
 
 Phofphorus ? j,q 
 
 The ancients gave to the fcven metals lad defcribed Names and 
 (omitting f/iUinum, which they did not know) the namesT^''" 
 of the planets, and denoted each of them by particular ^[^^^^°] 
 marks, which rcprefented both the planet and the metal, by the an- 
 Gold was the Sun, and reprefented by 0. cients. 
 
 Silver the Moon, J). 
 
 ?. 
 d". 
 
 ■y. 
 h- 
 
 It feems moft probable that thefe names were firft 
 given to the planets ; and that the fevcn metals, the 
 only ones then known, were fuppofed to have fome re- 
 lation to the planets or to the gods that inhabited them, 
 as the number of both happened to be the fame. It 
 appears from a palTage in Origen, that thefe names firft 
 arofe among the Perfians (w). Why each particular 
 metal was denominated by a particular planet it is not 
 eafy to fee. Many conjeftures have been made, but 
 fcarcely any of them are fatisfaftory. 
 
 As 
 
 Mercury 
 
 Copper 
 
 Iron 
 
 Mercury, 
 
 Venus, 
 
 Mars, 
 
 Tin 
 
 Lead' 
 
 Jupiter, 
 Saturn, 
 
 (u) Benzoat of lead is decompofed by muriatic acid. Trommfdorf, Ann. de Chim. xi. 317. 
 
 (;/) Suberic acid decompofes nitrat of lead. Qze Jamefon's Mineralogy, ^. 166. Zoonic acid produces the 
 fame effect, as Berthollct has obfevved. 
 
 (v) Schrickel places it after the three mineral acids. 
 
 (w) Contra Celfiim, lib vi. 2 2. — " Celfus de quibufdam Perfarum myfteriis ferraonem facit. Harum rerum, in- 
 quit, aliquod reperitur in Perfarum doftrina Mithracifque eorum myfteriis veitigium. In illis enim dux cjeleftes 
 converfiones, alia llellarum fixarum, errantium alia, et animas per eas tranfitus quodam fymbolo reprasfentantur, 
 quod hujulmodi eft, Scala altas portas habens, in fumma autcm oi^ava porta. Prima portarum plumbea, altera 
 
 llanaea,
 
 »o the ai- 
 ologer 
 
 131 
 Aecnrdtng 
 to the al- 
 
 Part r. C H E M 
 
 l.eaii. As to the charaflers by which thefe metals were cx- 
 
 * ' ' " ' prefTed, adrologcrs ieem to have confiJered them as the 
 Oriinii of attributes! of the deities of the fame name. The circle 
 thefc marksin the earliell periods among the Egyptians was the 
 accnrdiiii; fyrabol of divinity and perfcflion ; and ieems with great 
 propriety to have been chofen by them a^ the character 
 of the fun,efpecially as, when furrounded by fmall ftrokes 
 projefting from its circumference, it may form fome re- 
 prefentation of the emilfiou of rays. The femicii'cle is, 
 in like manner, the image of the moon ; the only one 
 of the heavenly bodies that appears under that form to 
 the naked eye. The chara<fter fj is fuppofed to repre- 
 fent the fcythe of Saturn ; li the thunderbolts of Jupi- 
 ter ; cf the lance ot Mars, together with his fiiield ; J 
 the looking-glafsof Venus ; and ^ the caduceus or wand 
 of Mercury. 
 
 The alchymifts, however, give a very different ac- 
 count of thefe fymbols. Gold was the mod perfeft me- 
 tal, and was therefore denoted by a circle. Silver ap- 
 proached neareft it; but as it was inferior, it was deno- 
 ted only by a iemicircle. In the charafter ^ the adepts 
 difcovered gold with a filver colour. The crofs at the 
 bottom expreffed the prefence of a myfterious fome- 
 thing, without which mercury would be filver or gold. 
 This fomething is combined alfo with copper; the pof- 
 fible change of which into gold is expreffed by the cha- 
 rafter 5. The charafter J* declares the like honour, 
 able affinity alfo ; though the femicircle is applied in a 
 more concealed manner: for, according to the propereft 
 mode of writing, the point is wanting at the top, or the 
 upright line ought only to touch the horizontal, and 
 not to interfed: it. Philofophical gold is concealed in 
 fteel ; and on this account it produces fuch valuable 
 medicines. Ot tin, one half is filver, and the other con- 
 iifts of the unknov/n fomething ; for this reafon the 
 crofs with the half moon appears in 1{.. In lead this 
 fomething is predominant, and a fimilitude is obferved 
 in it to filver. Hence in its charaAer fj the crofs ftands 
 at the top, and the filver charadler is only fufpended on 
 the right hand behind it. 
 
 The fadl, however, according to Profeffor Beckmann, 
 
 from whom moll of the above remarks have been taken, 
 
 feems to be, thai thefe charafters are mere abbreviations 
 
 of the old names of the planets. " The charafter of 
 
 *lJfJ}oi-y o/Mars (he obierves*), according to the oldeft mode of 
 
 ^'jtntions, reprefenting it, is evidently an abbreviation of the word 
 
 trTJhtior, ^"'P'ii under which the Greek, mathematicians under- 
 
 »33 
 Their real 
 origin. 
 
 I S T R Y. 239 
 
 flood that deity ; or, in other words, the firll letter O, ,^ Zjuc. ^ 
 with the lafl letter t placed above it. The charaftcr of " » 
 Jupiter was originally the initial letter of Ziuf ; and lu 
 the oldeft manul'cripts of the mathematical and aflrolo- 
 gical works of Julius Firmicus, the capital Z only is ufcd, 
 to which the lafl letter t was aftervirards added at the 
 bottom, to render the abbreviation more diftinft. The 
 fuppofed looking-glafs of Venus is nothing elfe than the 
 initial letter diilorted a little of the word ^aircx) which 
 was the name of that goddefs. The imaginary fcythe ' 
 
 of Saturn has been gradually formed from the two fiift. 
 letters of his name k;.«3c, which tranfcribers, for the 
 fake of difpatch, made always more convenient for ufe, 
 but at the fame time lefs perceptible. To difcover in 
 the pretended caduceus of Mercury the initial letter of 
 his Greek name Srafov, one needs only look at the ab- 
 breviations in tht oldefl manufcripts, where they will 
 find that the s was once written as C ; they will remark 
 alfo, that tranfcribers, to diftlnguifh this abbreviation 
 from the reft Hill more, placed the C thus O, and add- 
 ed under it the next letter r. If thofe to whom this 
 deduction appears improbable will only take the trouble 
 to look at other Greek abbreviations, they will find 
 many that differ Hill farther from the original letters 
 they exprefs than the prefent charafler ^ from the C 
 and r united. It is poffible alfo that later tranfcribers, 
 to whom the origin of this abbreviation was not known, 
 may have endeavoured to give it a greater refemblance 
 to the caduceus of mercury. In fhort, it cannot be de- 
 nied that many other aftronomical charaiSlers are real 
 fymbols, or a kind of proper hieroglyphics, that repre- 
 fent certain attributes or circumftances, like the charac- 
 ters of Aries, Leo, and others quoted by Saumaife." 
 
 Sect. IX. Of Zinc. 
 
 The ancients were acquainted with a mineral to which 
 they gave the name of Cadmea, from Cadmus, who lirlt 
 taught the Greeks to ufe it. They knew that when 
 melted with copper it formed brafs ; and that when 
 burnt, a white fpongy kind of afhes was volatilifed, 1-4 
 which they ufed in medicine*. This mineral contained Difcnvcry 
 a good deal of zinc ; and yet there is no proof remain- "^ y"*^- 
 ing that the ancients were acquainted wifh that me- j ."^''j 
 tal (x). It Is firll mentioned in the writings of AlberJanJ ic. 
 tus Magnus, who died in 1280: but whether he had 
 fcen it is not fo clear, as he gives it the name of mar. 
 cafite of gold, whichJmplies, one would think, that it- 
 had. 
 
 ftannea, tertia ex aere, quarta ferrea, quinta ex asre mixto, fexta argentea, feptima exauro, km^k? u.|-i;ri/x-)r, rrt 
 
 J'a(T» Tr\j\in oyScn. 'H r^uTn ri'v -ruXQf f^/iXt^iou^ n iiunpa naoTfrtpci;, «' rpirn ^a^xou, r! TfTaprn a-iStipou, p Tt^rrn y.xpxrov 
 
 »!),u.i<7-^a7-oc, » iKTB apyupof, .;^(iu<rou ■!•' I'l iCoun. Primum affignant Saturno tarditatem illius fideris plumbo indicantes ; 
 alteram Veneri, quam referunt, ut ipfi quidem putant, llanni fplendor et mollities ; tertiam Jovi, aheneam illaiu 
 quidem et folid^im : quartam Mercurio, quia Mercurius et ferrum, uterque operum omnium toleranten, ad merca- 
 turam utiles, laborum patientilTimi. Marti quintam, inaequalem illam et variam propter mixturam. Scxtam, 
 quae argentea eft, lunas ; feptimam auream foil tribuunt, quia lolls et lunse colores haec duo metalla referunt," 
 
 Borrichius fufpefts, with a good deal of probability, that the names of the gods in this paffage have been tranf. 
 pofed by tranfcribers, either through ignorance or defign. He arranges them as follows : " Secundam portam 
 faciunt Jovis, comparantes ei ftanni fplendorem et mollitiem ; tertiam Veneris a;ratam et folidam ; quartam Mnr- 
 tis, ell enim laborum patiens, seque ac ferrum, celebratus hominibus; qufntam Mercurii propter mifturam iiiKqiia-, 
 lem ac variam, et quia negotiator eft ; fixtam Lunx; argenteam ; feptimam Solis aiueam." OL Barr'icl.ius dc 
 crtu et progreffii chemie. Hafniae, 1 668, 410, p. 29. 
 
 (x) Grignon indeed fays, that fomething like it was difcovered in the ruins of an ancient Roman city in 
 Champagne ; but the fubftance which he, took for it was not examined with any accuracy. It is impolliblth. 
 therefore to draw any inference whatever from his affertion. Bulletin des fouilUs d'uns.viUe Romo'me, p. 11.
 
 240 CHEMISTRY. PattT.^ 
 
 Zinc, had a yellow colour(v). The word zinc occurs firft iii but one would be apt to fufpeiS, from tfce expen'mcmta ii nc 
 ^^"^'""^ the writings of Paracclfiis, who died in IC41. He in- mentioned by Mr Kiiwan, that it contained a eood deal '"T?' / 
 
 vi. of bit 
 tt'orh in 
 4ta. 
 
 .309 
 
 ■Properties 
 of zinc. 
 i Sag!. 
 
 1.499. 
 
 f SitrlcM, 
 
 forms us very gravely, that it is a metal, and not a me 
 
 • See ^ol. tfilj and that it confifts chiefly of the alhis of copper *. 
 This metal has alfo been called y/;c//fr. 
 
 Zinc has never been found in Europe in a Rate of 
 purity, and it was long before a method was difcuvered 
 of extrafling it from its ore(z). Henkel pointed out 
 \ one in 1721, and Von Swab obtained it by diftillation 
 in 1742, and Margraf publiflicd a procefs in the Berlin 
 ^j^/on"'"' Memoirs in I746f. 
 
 It is of a bluifn wiiite colour, fomewh:»t lighter than 
 lead. It has neither talle nor fmell. 
 
 It has fome degree of malleability ; for by compref- 
 
 fion it may be reduced into ihin plates :J: ; but it cannot 
 
 be drawn out into wire. It is more brittle when hot 
 
 than when cold. 
 
 § Kinvcns Its hardnefs is 6§. Its fpecific gravity, when com- 
 
 J\W.ii. prefFed, is y.ipob' || ; in Its ufual ftate, 6,862 1[. It 
 
 « Briffbn. "idts at about 699^ Fahrenheit *. 
 
 ^ Kirnan, When allowed to cool flowly, it cryftallizes in fmall 
 iiiJ. bundles of quadrangular prilms, difpofcd in all direc- 
 
 * Bergman. tJopg^ If they are expofed to the air while hot, they 
 
 J, J ' allume a blue changeable colour -)-. 
 Its oxides, When zinc is kept melted in contaft with air, it 
 becomes covered with a grey pellicle, which gradually 
 
 aflumes a jellowifh tint. By removing this pellicle evident from thefe two fubftances being often found uni- 
 from time to time, the whole of the metal may be redu- ted ; but it is very difficult to form the fulphuret of 
 ced icto a grey powdtr. This is the ^nji oxiile of zit:c. zinc artificially, on accomit of the rapid oxidation aud 
 This oxide is probably compofed of about 8 5 parts of confequent volatilization of the zinc. Morveau, how- 
 i Morveau, ^jpj. 2,jd 15 of oxygen J. When zinc is violently heated, ever, fucceeded in forming it. 
 
 ir-wan I j^. hums with a bright white flame, and at the fame time Zinc may be combined with phofphorus, by dropping p|,^jpjm. 
 4Sg. a quantity of very light white flakes are fublimed. Thefe fmall bits of phofphorus into it while in a ftate of fu- rets, 
 flakes are the nvhitt- oxiJe of zinc, \\hieh contains a good fion. Pelletier, to whom we are indebted tor the expe- 
 deat more oxygen than the grey oxide (a). riment, added alfo a little refin, to prevent the oxida. 
 Zinc may alio be oxidated by folutlon in acids, par- tion of the zinc. Phoii'huret of zinc is of a white co- 
 ticutarly the nitric acid. Whether the oxide obtained lour, a metallic fplciiJor, but reicnibles lead more than 
 by precipllating zinc from its folution in that acid, or zinc. It is fomewhat malleable. When hammered or 
 by diftilling that acid off zinc, be really different from filed, it emits the odour of phofphorus. When expo- 
 the white oxidcj has not yet been properly afcertained; fed to a ftrong heat, it burns like zinc ij;. t Ann. Jr 
 _^ Phofphorus '"'"'"• "'"• 
 
 more oxygen *. 
 
 The afiinilici of the oxiti .'S, or rather of the white 
 oxide of zinc, are, according to Bergtoan, as i^ollows : 
 
 Oxalic iicid. 
 
 Sulphuric, 
 
 Pyromucous -j-, 
 
 Muriatic, 
 
 Saccholiflic, 
 
 Nitric, 
 
 Sebacle, 
 
 Tartaric, 
 
 Pbofphoric, 
 
 Citric, 
 
 Succinic, 
 
 Fluoric, 
 
 Arfenic, 
 
 Formic, 
 
 Laftic, 
 
 Acetous, 
 
 Boracic, 
 
 PrufFic, 
 
 Carbonic, 
 
 Ammonia. 
 There is an afiinity between fuiphur and zinc, as iso^i'u' » 
 
 119. 
 
 (v) The pafl'ages in which he mentions it are as follows : — De Mineral, lib. ii. cap. ii. " Marchafita, five 
 marchaliJa ut quidam dicunt, eft lapis in fubftantia, et habet multas fpecies, quare colorem acclpit cujulhbct me- 
 talli, et fie dicitur marchafita argentea et aurea, et fie dicitur aliis. Metalium tamen quod colorat eum non di- 
 IllUat ah ipfo, fed cvapoiat in ignem, et fie rclinquitur cinis inutilis, et hie lapis notuseil apud aleliimicos, et in 
 inultis locif veniuntur. 
 
 Lib. iii. cap. lo. " TEs autem invenitur in venis lapldis, et quod eft apud locum' qui dicitur Gofelaria eft purif- 
 fimum et optimum, et toti fubftantix Inpidis incorporatum, ita quod totus lapis eft ficut marchafita aurea, et pro- 
 fundatum eft melius ex eo quod pnrius. 
 
 Lib. v. cap. ?. " Dlcimus igitur quod marchafita dupllcem habet in fui creatione fubftantiam, argenti vivi fci- 
 licet mortificati, et ad fixionem approximantis, et fulphuris adurentis. Ipfam habere fulphureitatem comperimu? 
 manlfefta experientia. Nam cum lublinintur, ex ilia emanat fubftantia fulphurea manifefta comburens. Et fine 
 fublimatione fimlliter perpenditur lUius fulphureitas. 
 
 " Nam fi ponatur ad ignitionem, non fufelpit illam priufquam inflammationc fulphuris infiammetur, ft ardeat. 
 Ipfam vero argenti vivi fubflantiam manifcftatur habere lenfibiliter. Nam albedincm pia?ftat Veneri meri argenti, 
 quemadmodum et ipfum argcntum vivum, et colorcm in ipfius fublimatione casleftium pracftare, et luciditatem 
 manifeftam metallicam habere vidimus, quae certum reddunt artificem Alchimise, illam has fubftantlas continere in 
 radice fua." 
 
 (z) The real difcoverer of this method appears to have been Dr Ifaac Lawfon. See Potl, III. Diff. 7. and 
 JVatfan's Chemical EJfays. 
 
 (a) Pott obferved, that it was t'o^I' heavier than the zinc from which it was obtained; and Mr Boyle had 
 long before afcertained the fame fatt. — Shaw's Boyle, II. 391, 394. 
 
 This oxide of zinc was well known to the ancients. Diofcorides defcribes the method of preparing it. The 
 ancients called [tpompholyx, the early chemifts gave it the name oi lana philofophica. Diofcorides compares it to wool, 
 
 Iflill TI)A.UT«(f ttfojKO/ovlai, v. 85. p.3jS.
 
 ■« rdtellir, 
 ihiJ. n8. 
 
 Carburet, 
 
 140 
 Alloys, 
 
 C I-I E M 
 
 Phofphorue combine* alfo with the oxide of linc, a 
 compound which Margraf had obtained during his cx- 
 pei-itiients on phofphonis. When i 2 parts of oxide of 
 zinc, 12 parts of phofphoric glafs, and two parts of 
 cliaicoal powder, are diilillcd in an earthen ware retort, 
 and a ftrong lieat applied, a metallic iabft.ince fubh'mes 
 of a filver- white colour, which, when broken, has a vi- 
 treous appearance. This, accordinjj to Pelletier, is 
 phofphuret of oxide of zinc. When heated by the blow- 
 pipe, the phofphorus burns, and leaves behind a glafs 
 tranfparent while in fufion, but opaque after cooling*. 
 Zinc alfo combines with carbon, and forms carburet 
 of zinc. The French chemiils have (hewn that zinc ge- 
 nerally contains fome carbon. 
 
 Zinc combines with mod of the metals : 
 I. It mixes with gold in any proportion. The 
 alloy is the whiter and the more brittle the greater 
 (Juantity of zinc it contains. An alloy, confifting of 
 equal parts of thefe metals, is very hard and white, re- 
 ceives a fine polifh, and does not tarnifh readily. It has 
 f MfCT. A- therefore been propofed by Mr Malouinf as very pro- 
 caJ. Par. per for the fpecula of telefcopes. One part of zinc is 
 Vi^' . faid to deftroy the ductility of 100 parts of gold J. 
 Mullu'er's 2. The alloy of filver and zinc is eafily produced by 
 
 DiiJionary. fuflOH. It is brittle. 
 
 3. Platinum combines very readily with zinc. The 
 alloy is brittle, pretty hard, very fufible, and of a bluilh 
 
 ^ Dr Lnvli.vfhhe colour, not fo clear as that of zinc J. 
 
 4. Zinc may be combined with mercury by fufion. 
 The amalgam is folid. It cryftallizes when melted and 
 cooled flowly into lamellated hexagonal figures, with 
 cavities between them. They are compofed of one part 
 
 II Khminsdco( zinc and two and a half of mercury ||. It is ufed to 
 Ciin. Di- rub on tledlrical machines, in order to excite eleftri. 
 jcn, t. 3. g;j.y_ 
 
 5. Zinc combines very readily with copper. This 
 alloy, which is called brafs, was known to the ancients. 
 They ufed an ore of zinc to form it, which they called 
 cadmia. This alloy was very much valued by the an- 
 cients. Dr Watfon has proved that it was to brafs 
 
 ^ Manche- which they gave the name of orif/'«/fum ^. Their ^j was 
 ftr Tranf. coppcr or rather bronze (b). Brafs is compofed of 
 about three parts of copper and one of zinc. It is of a 
 beautiful yellow colour, more fufiblc than copper, and 
 not fo apt to tarnifh. It is malleable, and fo duiilile that 
 it may be drawn out into wire. When the alloy con- 
 tains three parts of zinc and four of copper, it afTumes 
 a colour nearly the fame with gold, hut it is not fo mal- 
 leable as brafs. It is then called pinchbeck, prince's me- 
 ial, or Prince Rupert' s metal. 
 
 6. The alloy of iron and zinc has fcarcely been exa- 
 mined : but Malouin has (liewn that zinc may be ufed 
 
 SuppL. Vol. I. Part I. 
 
 I S T R Y. 
 
 241 
 
 vol ii. 
 
 inftead of tin to cover iron plates j a proof that there is Antimony, 
 an affinity between the two metals*. ~T?- ' 
 
 7. Tin and zinc combine cafdy. The alloy Is harder r- 'T., 
 than tin. \ his alloy is often tlic principal ingredient in 
 
 the compound called pewter. 
 
 8. Mr Gmelin has fucceeded in forming an alloy of 
 zinc and lead by fufion. He put fome fuet into the 
 mixture, and covered the crucible, in order to prevent 
 the evaporation of the zinc. When the ziiic exceeded 
 the lead very much, the alloy was malleable, and much 
 harder than lead. A mixture of two parts of zinc and 
 one of lead formed an alloy more dudile and harder 
 than the lall. A mixture of equal parts of zinc and 
 lead formed an alloy differing little in duftility and co- 
 lour from lead ; but it was harder, and more fufceptible 
 of polifh, and much more fonoroiis. When the mixture 
 contained a fmaller quantity of zinc, it flill approached 
 nearer the duftility and colour of lead, but it continued 
 harder, more fonorous, and fufceptible of polifli, till 
 the proportions approached to one of zinc and 16 of 
 lead, when the alloy differed from the lafl metal only in 
 being fomewhat harderf . \ Ant,, da 
 
 The affinities of zinc, according to Bergman, are as Chim. is. 
 follows i- 95- 
 
 Copper, - A„;,\Vm:. 
 
 Antimony, tij,. 
 
 Tin, 
 
 Mercury, 
 
 Silver, 
 
 Gold, 
 
 Cobalt, 
 
 Arfenic, 
 
 Platinum, 
 
 Bifmuth, 
 
 Lead, 
 
 Nickel, 
 
 Iron. 
 
 Sect. X. Of Antimony. 
 
 The ancients were acquainted with an oxide of anti- 
 mony to which they gave the names of c-;,k«, di\iij}ibium. 
 Pliny:]: informs us that it was found in filver ore ; and \ Plhiy, I. 
 we know that at prefent there are filver ores § in which '"''"^'- '• <^- 
 it is contained. It was uled as an external application V, "'" ' 
 to fore eyes; and Pliny gives us the method of preparing, ,0 
 it||. Galen fuppofes that the Ti1,oay.v»o. of Hippocrates I! i'llny,ili!if. 
 was a preparation of antimony ; but this wants proof. '4- 
 It does not appear, however, that the ancients confider-fj"^^'^'' 
 ed this tubllance as a metal, or that they knew aiitimo-„y.' 
 ny in a ftate of purity (e). Who lirll extrafted it from 
 its ore we do not know ; but Bali! Valentine, a che- 
 niifl of the i6th century, is the firil who defcribcs the 
 H h proccfs. 
 
 (b) The ancients do not feem to have known accurately the difference between copper, brafs, and bronze. 
 Hence the confufion obfervable in their names. They coufidered brafs as only a more valuable kind of cojiper, 
 and therefore often ufed the word w indifferently to denote either. It was not till a late period that miner do- 
 gills began to make the diflindlion. They called copper as cyprium, and afterwards only cyprium, whicii in p>ro- 
 cefs of time was converted into cuf'rum. AVhen thefe changes took place is not known accurately. Plinv i.lir. 
 cyprium, lib. xxxvi. c. 26. The word cuprum occurs firlt in Spartian, who lived about the year 290. He lays 
 in his life of Caracalla, cancelli ex are vel cupro. 
 
 (c) Mr Roux indeed, who at the requefl of Count Caylus analyfed an ancient mirror, found it compofecl of 
 copper, lead, and antimony. This would go far to convince us that the ancients knew this metal, provided it 
 could be proved that the mirror was really an ancient one ; but this point appears to be ejttieraely doubttu!.
 
 242 
 
 CHEMISTRY. 
 
 Part I. 
 
 Antimony, procefs. To him indeed we are indebted for our ac- 
 
 *— V quaintance with many of the properties of this metal. 
 
 Antimony is of a white colour, with a (hade of grey. 
 • Fourcrcy. It has a fcnlible tafte, but no fmell *. 
 
 '43 It is neither malleable nor dudile, but exceedingly 
 
 Pro(>crties jj|.;jj|g_ jts ipecitic gravity, according to BrifTon, is 
 of amimo- ^^^^^ _ according to Bergman, 6,860. Its hardncfs is 
 ikirnv^n-s 6,5 f. It melts at 809° Fahrenheit |. If after this the 
 Minir.U. jj^at be increafed, the metal evaporates. On cooling it 
 *''l affumes the form of oblong cryllals, perpendicular to 
 
 } £,rgma^. ^^^ i„t^,.„ai f„rface of the veffel in which it cools. It 
 is to this crydallization that the laminated flrudure 
 which antimony always affumes is owing. 
 
 Neither air nor water liave much effeft on this metal. 
 Itsoilde- When antimony is beat to powder, and expofed for 
 fome time to a gentle heat, it abforbs oxygen, and is 
 converted into a grey powder. This is the giry oxide of 
 antimony. When this metal is kept for fume time melt- 
 ed in contaa with air, it fublimes in the form of a white 
 powder, formerly called/now or luhite Jlowers of anti- 
 mony. This is the white oxide of antimony. This oxide 
 may be procured alfo by pouring nitric acid on antimo- 
 my, and then evaporating to drynefs. Antimony at- 
 trafts the oxygen from the acid, and thus palfes very 
 rapidly into the ftate of an oxide. This oxide feems to 
 confid of about 77 parts of antimony and 23 of oxy- 
 5 Klrwan's ^„ f The nature of thefe oxides has never yet been 
 '"■"" "- accurately inquired into. It is not even known at pre- 
 fent whether the white oxide obtained by heat and that 
 obtained by nitric acid contain the fame quantity of 
 oxygen. The experiments mentioned by Mr Kirwan 
 make the contrary probable || ; and yet thefe oxides 
 have too many qualities in common to render thefe ex- 
 periments conclufive. The white oxide of antimony 
 is foluble in waterf ; and when fufed, is converted into 
 a tranfparent glafs. The white oxide obtained by nitric 
 acid feems to poffefs many of the properties of an acid. 
 The afTuiities of the grey oxide of antimony are, ac- 
 cording to Bergman, as follows : 
 Sebacic acid, 
 Muriatic, 
 Benzoic (d) ? 
 Oxalic, 
 Sulphuric, 
 Pyromucous *, 
 Nitric, 
 Tartarous, 
 Saccholaflic, 
 Phofphoric, 
 Citric, 
 Succinic, 
 Fluoric, 
 Arfenic, 
 Formic, 
 Laftic, 
 Acetous, 
 Boracic, 
 Pruffic, 
 Carbonic. 
 Sulphur combines readily with antimony. This com. 
 pound is often found native : it was formerly called an. 
 timony, and the pure metal was then called regulus of 
 
 Miner, ll 
 489 
 
 II nid. 
 
 ^ Rouelte, 
 
 * Sel/rideL 
 
 145 
 
 Sulphurets, 
 
 antimony. Sulphuret of antimony is eafily melted by a Antimony, 
 moderate heat : if the heat be continued, the fulphur '~~^ 
 fublimes, and at the fame time the antimony abforbs 
 oxygen, and Is converted into a grey oxide. This ful- 
 phurct is compofed of 74 parts of antimony and 26 of 
 fulphur*. * Bergman, 
 
 The grey oxide of antimony is alfo capable of combi-iii' idj. 
 ning with about tsjj of fulphur. This compound, by 
 fufion, may be converted into glafs. It was formerly 
 ufed in medicine under the name of g/afs of antimony. 146 
 
 When equal parts of antimony and phofphoric glafs P'lofphu- 
 are mixed togetlier with a little charcoal powder, and"^^'' 
 melted in a crucible, phofphuret of antimony is produ- 
 ced. It is of a white colour, brittle, appears laminated 
 when broken, and at the frafture there appear a luimber 
 of fmall cubic facettes. When melted it emits a green 
 flame, and then fublimes in the form of a white powder. 
 Phofphuret of antimony may likewife be prepared by 
 fufing equal parts of antimony and phofphoric glafs, or 
 by dropping phofphorus into melted antimony f . f Pelleiier, 
 
 Antimony is capable of combining with raoft of the-^""- <''• 
 metals _ ^'^^''' »'"• 
 
 1. Gold may be alloyed with antimony by fnfing ' . 
 them together. The antimony is afterwards feparable Alloys, 
 by an intenfe heat. This alloy is little known, and has 
 never been applied to any ufe. 
 
 2. The alloy of filver and antimony is brittle, and its 
 fpecific gravity, as Gellert has obferved, is greater than 
 intermediate between the fpecilic gravities of the two 
 metals which enter into it. 
 
 3. Platinum eafily combines with antimony. The 
 
 alloy is brittle, and much lighter than platinum :j:. The ( Dr Leviii. 
 
 antimony cannot afterwards be completely feparated by 
 
 heat. 
 
 4. Mercury does not ealily combine with antimony. 
 Mr Gellert fucceedcd in amalgamating this metal by 
 putting it into hot mercury, and covering the whole 
 with water. 
 
 J. Copper combines readily with antimony by fufion. 
 The alloy is of a beautiful violet colour, and its fpeci- 
 fic gravity is greater than intermediate §. j CelUrt. 
 
 6. Iron combines with antimony, and forms a brittle 
 Tiard alloy, the fpecilic gravity of which Is lefs than in- 
 termediate. The magnetic quality of iron is much more 
 dlminlfhed by being alloyed with antimony than with 
 any other metal ||. | ij, 
 
 7. The alloy of tin and antimony is white and brittle ; 
 
 its fpecific gravity is Icfs than intermediate ^. ^ y. 
 
 8. When equal quantities of lead and antimony are fu- 
 fed, the alloy is porous and brittle : three parts of lead 
 and one of antimony form a compacfl alloy, malleable, 
 and much harder than lead: 12 parts of lead and one 
 of antimony form an alloy very malleable, and a good 
 deal harder than lead : 16 parts of lead and one of an- 
 timony form an alloy which does not differ from lead 
 except in hardnefs *. This alloy forms printers types, n, Gmelw 
 ■ g. Zinc and antimony form a brittle alloy, the {•fi.cx- Aim.de 
 fie gravity of which is lefs than Intermediate f. The Chim. viii. 
 alloys of antimony are little known. Gellert is almoft^',?" 
 the only pcrfon who has examined them. It would re- 
 qiu're a great number of experiments to be able to fix 
 the proportions of their ingredients. 
 
 The 
 
 t GellaU 
 
 (d) Muriatic acid decompofcs benzoat of antimony. Tromnfdorf, Ann, de Chim, xi. 317.
 
 Part I. 
 
 Bil'iniith. 
 
 148 
 
 Properties 
 of biimuth. 
 
 • Kirtvan^ 
 \ Brijin. 
 
 149 
 Its oxides, 
 
 § Kifwan , 
 h/lirur. ii. 
 489. 
 
 II Ihid. 
 
 C H E M 
 
 The affinities of antimony are, according to Berg- 
 man, as follows : 
 
 Iron, 
 
 Copper, 
 
 Tin, 
 
 Lead, 
 
 Nickel, 
 
 Silver, 
 
 Bifmuth, 
 
 Zinc, 
 
 Gold, 
 
 Platinum, 
 
 Mercury, 
 
 Arfcnic, 
 
 Cobalt, 
 
 Sulphiiret of arfenic. 
 
 Sulphur, 
 
 Pliofphorus? 
 
 Sect. XL Of Difmulh. 
 
 The ancients appear to have known nothing of bif- 
 muth, nor do we know who difcovercd it ; but it is firft 
 mentioned by George Agricola, who was boru about 
 the end of the 15th century. 
 
 Bifmuth is of a yellowifli or rcddilh white eolour, and 
 . alraoft deftitute both of tafte and fmell. 
 
 It is brittle. Its hardnefs is 6*. Its fpecific gra- 
 vity is 9,8z27t. It melts at 460" Fahrenheit f. 
 
 Wlien heated in clofe veffels, it fublimes. When al- 
 lowed to cool flowly after fufion, it cryftallizes. 
 
 Bifmuth is not altered by water. When expofed to 
 the air it foon tarniflies. 
 
 When bifmuth is kept fufed in contaft with air, it is 
 gradually oxidated. When heated red hot, it emits a 
 very faint blue flame, and its oxide evaporates in the 
 form of a yellowifli fmoke. When this fmoke is colleft- 
 ed, it is found to confift of a brown coloured powder. 
 This is the brown oxide of bifmuth. It is compofed of 
 about 94. parts of bifmuth and 6 of oxygen $. Bifmuth 
 decompofes nitric acid with great rapidity, by attiadl- 
 ing its oxygen. If the quantity of acid be conlider- 
 able, it diifolves the oxide as it forms ; but the greater 
 part of it may be precipitated by diluting the acid with 
 water. This precipitate, which is a white powder, is 
 while oxide of bifmuth. It is compofed of about 84 parts 
 bifmuth and 16 of oxygen ||. 
 
 The affinities of the oxides of bifmuth are, according 
 to Bergman, as follows : 
 
 Oxalic acid, 
 
 Arfenic, 
 
 Tartarous, 
 
 Phofphoric, 
 
 Sulphuric, 
 
 Sebacic, 
 
 Muriatic, 
 
 Benzoic (e) ? 
 
 Nitric, 
 
 Fluoric, 
 
 Saccholadlic, 
 
 Succinic, 
 
 Citric, 
 
 I S T R Y. 
 
 Formic, 
 
 Laftic, 
 
 Acetous, 
 
 Pruffic, 
 
 Carbonic, 
 
 Ammonia. 
 
 Birmuch. 
 
 150 
 
 Sulphur combines readily with bifmuth by fufion. 3 uiphuret. 
 The fulphuret of bifmuth is of a bluifli grey colour, and 
 cryftallizes into Ijeautifnl tetrahedral needles. It is com- 
 pofed of 85 parts of bifmuth and 15 of fulphur*. • IVenzel, 
 
 There appears to be little affinity between bifmuth^'';""'"/ 
 and phofphorus. Mr Pellelier attempted to produce ^'"'"'- "• 
 the phofphuret of bifmuth by various methods without ,', , 
 fucccfs. When he dropped j)hofphoru;, however, into Phofphu- 
 bifmuth in fufion, he obtained a fubftance which did not ret, 
 apparently dilfer irom bifmuth, but which, when expo- 
 fed to the blow-pipe, gave evident figns of containing 
 phofphorus. Phofphuret of bifmuth, according to Pel- 
 letier, is compofed of about 96 parts of bifmuth and 
 four of phofphorus f . M'"'- * 
 
 Bifmuth combines readily with mofl; of the metals. "^"- ^"'* 
 
 1. Equal parts of bifmuth and gold form a brittle al- ,"jj 
 loy, nearly of the fame colour with biimuth:};. Alloys, 
 
 2. Equal parts of bifmuth and filver (xjrm alio a l^rittle t K"'"' , 
 alloy, but lefs fo than the lafl. The fpecific gravity of ^^^'?""' ' 
 both thefe is greater than intermediate Ji. § /i,,/. 
 
 3. The alloy of bifmuth and platinum is alfo very 
 brittle. When expofed to the air it afl'umes a purple, 
 violet, or blue colour. The bifmuth may be feparated 
 
 by heat II . \iDrLiivi,. 
 
 4. Mercury difliolves bifmuth very eafily. The amal- 
 gam is more fluid than pure mercury, and has the pro- 
 perty of diflblving lead and rendering it alfo fluid ^. It^ Cramer. 
 is capable, however, of cryftallizing. The cry Hals are 
 
 either otlahedrons, lamellated triangles, or hexagons. 
 They are compofed of one part ot bifmuth and two of 
 mercury *. * '-■^'"'' ^'' 
 
 5. The alloy of copper and bifmuth is not fo red as^""' '• ^* 
 copper. 
 
 6. Nothing is known concerning the alloy of iron and 
 bifmuth. 
 
 7. Bifmuth and tin unite readily. A fmall portion 
 of bifmuth increafes the brightnels, hardnels, and fono- 
 roufnefs of tin : it often therefore enters into the com. 
 pofition of the compound called pewter. Equal parts 
 of tin and bifmucii form an alloy that melts at 280° : 
 eight parts of tin and one of bifmuth, melt at 390": 
 
 two parts of tin and one of bifmuth, at 330°!. \ Dr Lewru 
 
 8. The alloy of lead and bifmuth is of a dark grey 
 colour, a clofe grain, but very brittle. 
 
 9. Bifmuth does not combine with zinc. 
 
 10. The alloy of antimony and bifmuth is unknown. 
 Bifmuth likewife enters into triple compounds with 
 
 metals : Two parts of lead, three of tin, and five of 
 bifmuth, form an alloy which melts at the heat of boil- 
 ing water, which is 2 1 2°. is3 
 
 The affinities of bifmuth, according to Bergman, are And afBni- 
 as follows : '"' 
 
 Lead, 
 Silver, 
 Gold, 
 
 H h 2 Mercury, 
 
 (e) Muriatic acid decompofes benzoat oi biita^lh.—'Tromm/Jor/, /inn. de Cb'm. xi. '317.
 
 C H E IM 
 
 Mercury, 
 
 Antimony, 
 
 Tin, 
 
 Copper, 
 
 Platinum, 
 
 Nickel, 
 
 Iron, 
 
 Sulphuvei of alkali, 
 
 .Sulphur, 
 
 Phofphorus ? 
 
 Sect XII. Of Arjtmc. 
 
 The word arfenic (af5-i«i,o») occurs firft in the works 
 of Diofcorides, and of fome other authors wlio wrote 
 about the beginning of the Chriftian era. It denotes in 
 their works the fame fubilance which Ariftotle had 
 called cutia^a-^Y, (f), and his difciple Theophraftus 
 apcitiyi; which is a reddifh coloured mineral, compofed 
 of arfenic and fulphur, ufed by the ancients in painting, 
 and as a medicine. 
 
 The ivhite oxirJe of arfenic, or wbat is known in com- 
 merce by the name of arfenic, is mentioned by Avicen- 
 na in the nth century ; but at what period the metal 
 called arfer.ic was firft extrafted from that oxide is un. 
 known. Paracelfus feems to have known it. It is 
 ■pif ntioned by Schroeder in his Pharmacopoeia publilhed 
 
 * Birgman, in 1 649 *. 
 
 ii. 27S. Arfenic, when pure, is of a bluifh white colour, [t is 
 
 „ '■'•^ . exceedinglv brittle. Its hardnefs is 7+. Its fpecific 
 
 cf arfenic. gravity S.JIoJ. 
 
 i Kirzuan, When expoled to the temperature of 354° in clofe 
 veffels it fublimes ^, and cryilallizes in regular tetrahe- 
 drons. 
 
 It is not much altered by water. Boiling water, how- 
 ever, is capable of diflblving, and retaining .r_L__th of 
 arfenic ; but that pan of the metid is no doubt reduced 
 to the ftate of an oxide l|. 
 
 When arfenic is expoled to the open air, it very foon 
 lofes its luftre, and is gradually converted into a erevift 
 black fvibftance by combining with oxygen. This is 
 called the grey oxide of arfenic. 
 
 When expofed to a moderate heat in contaft with 
 air, it fublimes in the form of a white powder, and at 
 the fame time emits a fmell rcfembling garlic. If the 
 heat be increafed, it burns with an obfcure bluifh flame. 
 This fiiblimate is •white oxide of arfenic, which is compo- 
 
 5 Kir-wan'i {ed of 93 parts of arfenic and 7 of oxygen ^. 
 
 iWwtr. 11. jj jj ^jf 2 (},arp acrid tafte, which at laft leaves an im- 
 preflion of fweetnefs, and is one of the moll virulent 
 poifons known. It has an alliacious fmell. It is fo- 
 luhle in bo parts of water at the temperature of 60'', 
 
 * Bergman, zni in 15 parts of boiling water*. When this folu- 
 + B ' dt *'°" '^ evaporated, the oxide cryftallizes f. When 
 Ali. Upfal, heated to 283*, it fublimes : if heat be applied in clofe 
 1 733. veffels, it becomes pellucid like glafs, but when expofed 
 
 to the air it foon recovers its former appearance. The 
 fpecific gravity of this glafs is 5,000 ; that of the white 
 } Btr^CTu/i, oxide, 3,706 J. This oxide is capable of combining 
 'sji. ays. vvith moil of the metals, and in general renders them 
 brittle. Its af&nities, according to Bergman, are as 
 follows : 
 
 Mine,, u. 
 
 li. 278. 
 { JliJ. 
 
 154 
 Its oxidec, 
 I H^jbrenuin, 
 Chrn. At, 
 I7SS, i. 
 i8i. 
 
 1 S T R Y. PartT. 
 
 Muriatic acid, , Arfenic. ^ 
 
 Oxalic, '' 
 
 Sulphuric^ 
 
 Nitric, 
 
 Sebacic, 
 
 Tartaro'js, 
 
 Phofphoric, 
 
 Fluoric, 
 
 Saccholaftic, 
 
 Succinic, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Arfenic, 
 
 Acetous, 
 
 Pruffic, 
 
 Ammonia, 
 
 Water, 
 
 Alcohol ? 
 Arfenic, or rather the white oxide of arfenic, is ca- 
 pable of combining with an additional dofe of oxygen. 
 The compound produced is arfenic acid, firft difcovered 
 by Scheele, which contains 91 parts of arfenic and 9 of 
 oxygen*. * Bertbdlei, 
 
 Arfenic combines readily with fulphur. When heat A/r'aan", 
 is applied to a mixture of white oxide of arfenic and ' '""' "' 
 fulphur, the oxide is decompofed, part of the fulphur n-^ 
 combines with its oxygen, and the remainder unites Suiphurct, 
 with the reduced metal. The fulphuret of arfenic pro- 
 duced by this procefs is of a yellow colour, and was for- 
 merly called orpiment. It is compofed, according to 
 Wcftrum, of 20 parts of arfenic and 80 of fulphur f. 
 It is often found native. If a ftronger heat be applied, .'„j 
 fo as to melt the fulphuret, it affumes a fcarlet colour, 
 and is much kfs volatile than formerly. This new com- 
 pound was formerly called realgar. It is compofed, ac- 
 cording to Weftrum, of 80 parts of arfenic and 20 of 
 fulphur J. The difference therefore between it and or- ' "'*• 
 piment is evident. During the fufion part of the ful- 
 phur without doubt fublimes. It might be called red 
 fulphuret of arfenic. 156 
 
 Arfenic combines readily with phofphorus. The Phofphu- 
 phofphuret of arfenic may be formed by diililling equal''"' 
 parts of its ingredients over a moderate fire. It is black 
 and brilliant, and ought to be preferved in water. It 
 may be formed likewife by putting equal parts of phof- 
 phorus and arfenic into a fufficient quantity of water, 
 and keeping the mixture moderately, hot for fome 
 time §. § PMitler, 
 
 Arfenic unites with moft metals, and in general ren- ■^": 
 ders them more brittle and more fufible. ' 
 
 1. Melted gold takes up ^'^th of arfenic ||. The al- p b. 
 loy is brittle and pale. ikii. 
 
 2. Melted filver takes up Tjth of arfenic f. The al-^ -''•''■ 
 loy is brittle. Alloys, 
 
 3. The alloy of platinum and arfenic is brittle and 
 very fufible. It was firft formed by Scheffer. The 
 arfenic may be feparated by heat. 
 
 4. The amalgam of arfenic is compofed of five parts 
 of mercury and one of arfenic *. * ^^'^• 
 
 5. Copper takes u'p |-ths of arfenic f. This alloy is \ ItiJ. 
 
 white ; 
 
 f JClr-wan't 
 \Uner. ii. 
 
 .d! 
 Chim. Xlii.' 
 
 ngna% 
 
 (f) Pliny feems to make a diftinftion between fandaracha and arfenic. See Lib. xxxiv. c. 18.
 
 Part r. 
 
 Cobalt 
 « Ccllert. 
 
 \'Bergman, 
 Ann. de 
 Chim xiii. 
 
 139- 
 
 5 Kirivan 3 
 £ Bergman, 
 
 JbiJ. 
 
 11 UiJ. 
 
 And ^Di- 
 ti£5. 
 
 f AB. Up. 
 
 159 
 
 PrpJlrIti«S 
 
 •f mhr-.lt, 
 
 '*^-LcQnhatdh 
 
 ^ Kirivan s 
 
 fdiner, ii. 
 
 168. 
 
 X Bergman y 
 
 IT. 
 
 C H E M 
 
 white ; and when the quantity of arfenic contained in 
 it is fmail, both duftile and malleable *. It is called 
 ivhile tombac. 
 
 6. Iron is capable of combining with more than its 
 own weight of arfenic •)•. This alloy is white, brittle, 
 and capable of cryftallizing. It is found native \. 
 
 7. The alloy of tin and arfenic is harder and more fo- 
 norous than tin, and has much refemblance externally 
 to zinc. Tin often contains a fmall quantity of ar- 
 fenic. 
 
 8. Lead takes up ~th of arfenic J. The alloy is brittle 
 and dark coloured. 
 
 q. Zinc takes up fth of arfenic, antimony ^th, and 
 bifmuth -rVth II . 
 
 The affinities of arfenic, according to Bergman, arc 
 as follows : 
 
 Nickel, 
 
 Cobalt, 
 
 Copper, 
 
 Iron, 
 
 Silver, 
 
 Tin, 
 
 Gold, 
 
 Platinum, 
 
 Zinc, 
 
 Antimony, 
 
 S'jlphuret of alkali, 
 
 Sulphur, 
 
 Phofphorus. 
 
 Sect. XIII. Of Cobalt. 
 
 A MINERAL called cobalt (g), of a grey colour, and 
 ▼ery heavy, has been ufed in different parts of Europe 
 fmce the 15th century to tinge glafs of a blue colour. 
 From this mineral Brandt obtained in 1733 ^ '"^"' ^'^- 
 tal, to which he gave the name of cobalt ^. 
 
 Cobalt is of a white colour, inclining to a bluiih or 
 ftecl grty. When pure, it is fomewhat malleable while 
 red hot *. Its liardnefs is 8 f-. Its fpecific gravity is 
 8,15 (h). It requires for fufion a heat at lealt as great 
 
 as call iron, which melts at 130° Wedgewood. No 
 heat has been produced great enough to volatalize itf. 
 
 Cobalt, when pure, does not feem to be afltdtcd by 
 air or water. 
 
 It is attra<S,ed by the magnet. 
 
 Miner, li. 
 z03. 490. 
 
 I S T 11 Y. 245 
 
 It is not oxidated by heat without very great diffi- Co balt, 
 culty ; but it has the property of decompofing nitric ' 
 acid, and of attrafting oxygen by that means with j^j o^jj^s 
 great rapidity. 
 
 The oxide of cobalt is of fo deep a blue as to appear 
 black. The oxide procured by heat is compofed of 88 
 parts of cobalt and i 2 of oxygen ; that by nitric acid 
 contains about 77 parts of cobalt and 23 of oxygen *. ' Kirivan 1 
 Its affinities, according to Bergman, arc as follows : 
 
 Oxalic acid. 
 
 Muriatic, 
 
 Sulphuric, 
 
 Tartarous, 
 
 Nitric, 
 
 Sebacic, 
 
 Phofphoric, 
 
 Fluoric, 
 
 Saccholaftic, 
 
 Succinic, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Acetous, 
 
 Arfenic, 
 
 Boracic, 
 
 Pruffic, 
 
 Carbonic, 
 
 Ammonia. 
 
 T\it fulphurct of cobalt is not formed without difRcul-Sul]liuicf, 
 ty. It is fcarcely known. 11S2 
 
 Phofphuret of cobalt may be formed by heating the Phofphu- 
 metal red hot, and then gradually dropping in fmall bits'*'' 
 of phofphorus. It contains about -t\t\i of phofphorus. 
 It is white and brittle, and when expofed to the air 
 foon lofes its metallic luftre. The phofphorus is fepa. 
 rated by heat, and tlie cobalt is at the fame time oxida- 
 ted. This phofphuret is much more fufible than pure 
 
 "'baltf. . . ^Pelleticr,. 
 
 The combmations of cobalt wjth other metals havey/„,.rf, 
 been very little examined into. Ciwi. xiij. 
 
 I . 
 
 xf,t 
 
 The alloy of gold and cobalt is not known. '34- 
 
 2. Cobalt does not combine with filver by lution J; aii ' 
 
 ■y. 
 
 but, according to GtUert, the alloy of filver and cobalt t Hergman. 
 
 may be formed : it is brittle and of a grey colour ^ EleB. At- 
 3. The allov of platinum and cobait is unknown. '''"^ 
 ^ ^ 4,Mer-f^^""''''"- 
 
 i 
 
 Chin:. 
 
 (g) The word cobalt feems to be derived from cobalus, which was the name of a fpirit that, according to the 
 fuperltitious notions of the times, haunted mines, deftroyed the labours of the miners, and oiten gave them a 
 great deal of unncceffary trouble. The miners probably gave this name to the mineral out of joke, becaufe it 
 thwarted them as much as the fuppofed fpirit, by exciting falfe hopes, and rendering their labour often truit- 
 lefs ; for as it was not known at lirft to wiiat ufe the mineral could be applied, it was thrown aiide as ufelets. It 
 was once cullomary in Germany to introduce into the church-fervice a prayer that God would preferve miners 
 and their works from Lobalts and ipirits. See Beckmann's Htjlory of Inventions, II. 362. 
 
 Mathefins, in his tenth fermon, where he fpeaks of cadmia fojfilis (probably cobalt ore), fays, " Ye miners 
 call it kobolt ; the Germans call 1 lie black devil and the old devil's whores and hags, old and black iobel, which, 
 by their witchcraft do injury to people and to their cattle." 
 
 Lehmann, Paw» Delaval, and fcveral other philofophers, have fuppofed that /wn// (oxide of cobalt melted, 
 with glafs and pounded) was known to the ancients, and ufed to tinge the beautiful blue glafs ilill vifible in fome 
 of their works ; but we learn from Gmelin, who analyfed fome of thcfe pieces of glafs, that they owed their blue 
 colour, not to the prefcnce oi cobalt but of iron. 
 
 According to Lehmaun, cobalt ore was firft ufed to tinge glafs blue by Chriftopher Schurer, a glafs maker at 
 Eiatten, about the year I 540. 
 
 (h) Berg. II. 231. According to Biifibn, 7,8119.
 
 « Bj 
 
 iv. 
 
 164 
 And afSni. 
 tie;. 
 
 Difcoveiy 
 of nickel, 
 
 C H E M 
 
 4. Mercury doea not appear to amalgamate with co- 
 balt. 
 
 5. The alloy of copper and cobalt is fcarcely known. 
 
 6. The alloy of iron and cobnlt is very hard, and not 
 eafily broken. Cobalt generally contains fome iron, 
 from which it is with great diffiLulty fi'iorated. 
 
 7. The alloy of tin and cobalt is o> a light violet 
 colour. 
 
 8. Cobalt does not combine with lead by fufion. 
 
 9. The alloy of zinc and cobalt is not formed with- 
 out difficulty. 
 
 JO. The alloy of antimony and cobalt is unknown. 
 J I . Cobalt does not combine with bilmuth by fu- 
 fion *. 
 
 12. Arfenic combines very readily with cobalt. The 
 alloy is brittle, mucli more fufible, and more ealily oxi- 
 dated than pnre cobalt-|-. 
 
 The affinities of cobalt are as follows ; 
 Iron, 
 Nickel, 
 Arfenic, 
 Copper, 
 Gold, 
 Platinum, 
 Tin, 
 
 Antimony, 
 Zinc, 
 
 Siilphuret of alkali, 
 ' Sulphur, 
 
 Pofphorus ? 
 
 Sect. XIV. Of Nich!. 
 
 A HEAVY mineral of a red colour is met with in fe- 
 veral parts of Germany, which bears a ftrong refem- 
 blance to an ore of copper; but none of that metal can 
 be extrafted from it : for this reafon the Germans call- 
 ed it hupfer nickel (devil's copper). Hierne mentioned 
 it in 1694. Cronlledt was the I'lrft chemift who exa- 
 mined it with accuracy. He concluded from his expe- 
 riments, which were yubliflied in the Stockholm Tranf- 
 aftions for 1751 and 17^4, that it contained a new me- 
 tal, to which he gave the name of nickel. 
 
 Some chemills, particularly Mr Sage, affirmed, that 
 it contained no new metal, but merely a compound of 
 various known metals, which could be feparated from 
 each other by the ufual procefies. Thefe alTertions in- 
 duced Bergman to undertake a very laborious courfe of 
 experiments, in order if poffible to obtain nickel in a 
 (h: 1 of purity : for Cronftedt had not been able to fe- 
 parate a quantity of arfenic, cobalt, and iron, which 
 adhered to it with much obllinacy. Thefe experiments 
 have been very fully detailed in the article Chemistry, 
 in the Encycl. to which be beg leave to refer. Berg- 
 man has fliewn, that nickel poiTefles peculiar properties, 
 and that it can neither be reduced to any other metal, 
 nor formed artificially by any combination of metals. 
 It mull therefore be confidered as a pecuhar metal. It 
 may poflibly be a compound, and fo may likewlfe many 
 other metals ; but we muft admit every thing to be a 
 peculiar body which has peculiar properties, and we 
 muft admit every body to be fmiple till fome proof be 
 aftually produced that it is aj^ompound ; otherwife we 
 forfake the road of fcience, and get i-nto the regions of 
 fancy and romance. 
 
 I S T R Y. Parti. 
 
 Nickel is of a greyifii white colour, and when lefs Nickel. ■ 
 
 pure inclines a little to red. '"■"">• ■' 
 
 It is both duftile and malleable. Its hardnefs is 8*. ,. ' 
 T c ■/• • . r •/•/-,- Its proper- 
 
 its Ipecihc gravity 9, coof. It requires tor tuhon aiies, 
 
 temperature at Icill equal to i ?o° Wedgewood f. * Kii-wmU 
 
 It is powerfully attrafted by the magnet, and is even ^^^""■'■- 'i- 
 
 pofieffed of the property of attrafting iron. This in- , „ 
 
 duced Bergman to fuppofe that nickel, when pureft,ii. jj,. ' 
 
 was ilill contaminated with about one-third of iron : f JiiJ. 
 
 but as this is the only proof of its containing iron, 
 
 Klnproth, with reafon, deems it an iafufficient one, and 
 
 confiders attradlion by the magnet as a property of 
 
 nickel §. 5 /?„„. j: 
 
 When expofed to a ftrong heat, nickel is oxidated cli^. i. 
 
 flowly. Its oxide is of a brown colour ; if impure, it '7°- 
 
 is greeny]}. The oxide of nickel, according to Klaproth, oxides 
 
 is compoied of 77 parts of nickel and 23 of oxygen ^.^ Kim-m't 
 
 Its affinities, according to Bergman, are as follows ; Miner, ii. 
 
 Oxalic acid, 490- 
 
 Muriatic, 
 
 Sulphuric, 
 
 Tartarous, 
 
 Nitric, 
 
 Sebacic, 
 
 Phofphoric, 
 
 Fluoric, 
 
 SaccholaAIc, 
 
 Succinic, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Acetous, ^ 
 
 Arfenic, 
 
 Boracic, 
 
 Pruffic, 
 
 Carbonic, 
 
 Ammonia, 
 
 Potafs .' 
 
 Soda ? jgj 
 
 Cronftedt found that nickel combined readily with Suiphuret 
 fulphur by fufion. The fulphuret which he obtained 
 was yellow and hard, with fmall fparkling facets ; but 
 the nickel which he employed was impure. 
 
 Nickel combines very readily with phofphorus, either pi,ofnhu- 
 by fufing it along with phofphoric glafs, or by drop-r^t, 
 ping phofphorus into it while red hot. The phofphu- 
 ret of nickel is of a white colour, and when broke ex- 
 hibits the appearance of very flender prifms coUefted 
 together. When heated, the phofphorus burns, and the 
 metal is oxidated. It is compofed ot 8:? parts of nickel 
 and 17 of phofphorus *. The nickel, however, iin* Pdutltr, 
 which this experiment was made, was not pure. '^i"- d' 
 
 Little is known concerning the alloys of nickel wlth'^'-""' '""• 
 other metals. Equal parts of filver and nickel form a "' ,-0 
 white dudtile alloy. Equal parts of copper and nickel Alloys, 
 form a red duftile alloy. The compounds which this 
 metal forms with tin and zinc are brittle. It does not 
 combine with mercury f. It has a very ftrong afSnityf Bergman, 
 for iron, cobalt, and arfenic, and is fcarcely ever found"- 251. 
 except combined with fome of them. 
 
 Its af&nities, according to Bergman, are as follows : ^ndVlEni- 
 
 Iron, 
 
 Cobalt, 
 
 Arfenic, 
 
 Copper,
 
 Part L 
 
 C H E M 
 
 r'7'i 
 
 Difcovery 
 Iiefc-. 
 
 * Bergman, 
 ii. 211. 
 
 17-2 
 Its proper- 
 ties, 
 
 ■^ Kirtvan j 
 Joiner, lu 
 
 a88. 
 
 173 
 Oxides 
 
 ^ Bergman, 
 Ji. »3J, 
 
 Copper, 
 
 Gold, 
 
 Tin, 
 
 Antimony, 
 
 Platinum, 
 
 Bifmulh, 
 
 Leud, 
 
 Silver, 
 
 Zinc, 
 
 Siilplmrct of alkali. 
 
 Sulphur, 
 
 Popfphorus ? 
 
 Sect. XV. Of Mansamfe. 
 
 The dark grey mineral called man^anefe, in Latin 
 magtiefia (according to Boyle, from its rtfemblance to 
 the magnet), has been long known and ufed in making 
 glafs. A mine of it was difcovered in England by Mr 
 Boyle. It was long iuppofed to be an ore of iron ; but 
 Port and Cronftedt having denionllratcd that it contain- 
 ed very little of that metal, the latter referred it in his 
 Mineralogy to a diltinft order of earths, which he call- 
 ed terrs magnefia. Bergman, from its fpecific gravity, 
 and feveral other qualities, fufpefted that it was a me- 
 tallic oxide : he accordingly made feveral 'attempts to 
 reduce it, but vyithout fuccefs ; the whole mafs either 
 alTuming the form of fcoriae, or yielding only fmall fe- 
 parate globules attrafted by the magnet. This difficul- 
 ty of fufion led him to fufpeft that the metal he was in 
 queft of bore a ftrong analogy to platinum. In the 
 mean time, Dr Gahn, who was making experiments on 
 the fame mineral, aijtually fucceeded in reducing it by 
 the following procefs : He lined a crucible with char- 
 coal powder moiftened with water, put into4t fome of 
 the mineral formed into a ball by means of oil, then 
 filled up the crucible with charcoal povviler, luted ano- 
 ther crucible over it, and expofed the whole for about 
 an hour to a very intenfe heat. At the bottom of the 
 crucible was found a metallic button, or rather a num- 
 ber of fmall metallic globules, equal in weight to one- 
 third of the mineral employed*. It is eafy to fee by 
 what means this reduftion was accomplifned. The char- 
 coal attrafted the oxygen from the oxide, and the me- 
 tal remained behind. This metal is called manganefe. 
 
 Manganefe is of a greyilh white colour. It is not 
 malleable, and yet not fo brittle as to be eafily broken. 
 
 Its hardnefs is 8 f . Its fpecific gravity is 7,000 \. 
 Its fufion requires fo great a heat, that it has been vefy 
 fcldora accomplifhed. 
 
 When reduced to powder, it is attrafted by the 
 magnet. 
 
 AVhen expofed to the air, it very foon tarnifhes, and 
 affumes a darker colour, till at lad it becomes black and 
 friable. This change is produced by the abforption of 
 oxygen. It takes place much more rapidly if heat be 
 applied to the metal. The fubilance thus obtained is 
 the black oxide of manganefe. This oxide is found in 
 great abundance in nature, though fcarcely ever in a 
 ftate of purity. It is compofed of 75 parts of manga- 
 nefe and 25 of oxygen §. 
 
 I S T R Y. 247 
 
 If a quantity of tniiriatic acid be poured upon this Manganefe. 
 oxide, and heat applied, part of the acid combines with ^"^ ' 
 fome of the oxygen of the oxide, and flies off in yellow 
 fumes. The oxide is dilfolved in the reft. If potafs be 
 added to this folution, a white powder is precipitated. 
 This is the ivhifs oxide of manganefe. It contanis, ac- 
 cording to Bergman, about 80 parts of manganefe and 
 ao of oxygen. It foon attrafts more oxygen when ex- 
 pofed to the air, and is converted into black oxide. 
 
 The affinities of the white oxide, according to Berg, 
 man, are as follows : 
 
 Oxalic acid, 
 
 Citric, 
 
 Phofphoric, 
 
 Tartarous, 
 
 Fluoric, 
 
 Muriatic, 
 
 Sulphuric, 
 
 Nitric, 
 
 Saccholaftic, 
 
 Succinic, 
 
 Sebacic, 
 
 Tartaric, 
 
 Formic, 
 
 Laftic, 
 
 Acetous,, 
 
 Fruffic, 
 
 Carbonic. 
 The fulphuret of manganefe is unknown. ,^4 
 
 Phofphorus may be combined with manganefe by Phofphu- 
 melting together equal parts of the metal and of phof-'''' 
 phoric glafs ; or by dropping phofphorus upon red hot 
 manganefe. The phofpluiret of manganefe is of a white 
 colour, brittle, granulated, difpofed to cryftallize, not 
 altered by expofure to the air, and more fufible than 
 manganefe. Wh-en heated, the phofphorus burns and 
 the metal becomes oxidated *. * VelUtler, 
 
 Manganefe combines readily with carbon by fu- '^"'•- <>' 
 fion (i). •a.>..xiii. 
 
 Little is known concerning the alloys of manganefe. j,. 
 It combines readily with copper. The compound, ac-Carburet, 
 cording to Bergman, is very malleable, its colour is red, 176 
 and it fometimes becomes green by age. Gmelin mado ■'^"°y'« 
 a number of experiments to fee whether this alloy could 
 be formed by fufing the black oxide of manganefe along 
 with copper. He partly fucceeded, and propofed to 
 fubltitute this alloy inftend of the alloy of copper and 
 arfenic, which is ufed in the artsf. We believe, how- f Ann. dt 
 ever, that upon trial the new alloy has been found not C^'ot. u 
 to anfwer. ^°^' 
 
 Manganefe combines readily with iron ;, indeed it has 
 fcarcely ever been found quite free from fome mixture 
 of that metal. It combines alfo very eafily with arfe- 
 nic and tin, not eafily witli zinc, and not at all with 
 
 mercury \. \ Bergman, 
 
 The affinities of manganefe, according to Bergman, 'i-*"- 
 
 are as follows : AndYffini- 
 
 Copper, jigj_ 
 
 Iron, 
 Gold, 
 
 Silver, 
 
 (i) Bergman, III. 379. — Sometimes manganefe is very fpeedily oxidated by expofure to the air; fometimes 
 fcarcely altered by it, as Klaproth and Pelletier have obferved. Mr Kirwan fuppofes that the manganefe 
 which is foon altered contains carbon, and that tbis is the caufe of the diS'erence. See Miner. II. 2 88<
 
 178 . 
 t>ifc<ivcry 
 
 C H E M I 
 
 Silver, 
 
 Tin, 
 
 Sulphuret of alkali, 
 
 Phofphorus ? 
 
 Carbon ? 
 The three metals, colalt, n'uLI, nnd mangm-.tfe, refem- 
 ble iron in feveral particulars : Like if, they are inag- 
 rctlc, very hard, and very difficult to fufe : but they 
 d!(r;r from it in fpccitic gravity, malleability, and in 
 the properties of all their combinations with other fub- 
 llances ; the oxides, for inftance, of iron, cobalt, nickel, 
 qnd mangancfe, poflefs very different qualities. 
 
 Sect. XVI. Of Tungsten. 
 
 There is a mineral found in Sweden of an opaque 
 of tungften. white colour ar.d great w.eight ; from which lalt cir- 
 cumftance it got the name of tungsten, ov ponderous Jlone. 
 Some mineralogifts confidered it as an ore of tin, others 
 fuppofed that it contained iron. Scheele analyfed it in 
 17S1, and found that it was compofed of lime and a 
 peculiar earthy-like fubftance, which he called from 
 its properties tungstic acid. Bergman conjectured that 
 the bafis of this acid was a metal ; and this conjefture 
 was foon after fully confirmed by the experiments of 
 MefTrs D'EUmyart, who obtained the fame fubftance 
 from a mineral of a brownitli black colour, called by 
 the Germans wolf ram , which is fometimes found in tin 
 • mines. This mineral they found to contain ^Vs of 
 tungftic acid ; the reft ot it confifted of manganefe, 
 iron, and tin. This acid fubftance they mixed with 
 charcoal powder, and heated violently in a crucible. 
 On opening the crucible after it had cooled tliey found 
 in it a button of metal, of a dark brown colour, which 
 crumbled to powder between the fingers. On viewing 
 it with a glafs, they foUi)d it to conlift of a congeries 
 of metallic globules, fome of which were as large as a 
 pin-head. The metal thus obtained is called tungsten. 
 The manner in which it was produced is evident ; tung- 
 ftic acid is compofed of oxygen and tungften : the oxy- 
 gen combined with the carbon, and left the metal in a 
 170 ftate of purity. 
 If: Pioper- Tungften is externally of a brown colour, internally 
 of a fteel grey *. 
 
 Its fpecific gravity is 1 7,600 f . It is more infufible 
 than manganele J. 
 
 When heat is applied to tungften it is converted in- 
 to a yellow powder, compofed of 80 parts of tungften 
 and 20 of oxygen §. This is iht yellow o\\de of tungsten 
 or tungstic acid. 
 
 The fulphuret of tungften is of a bluifh black colour, 
 hard, and capable of cryftallizing. 
 
 Phofphorus is capable of combining with tungften ||. 
 
 Of the alloys of tungften we know nothing, except 
 
 from the experiments of Elhuyarts, which have been 
 
 tranfcribed into the article Chemistry in the Encyclo- 
 
 tidia ; to which, therefore, we beg leave to refer. 
 
 Sect. XVII. Of Molybdenum. 
 
 The Greek word molybdena, and its Latin tranllation 
 
 nf niolyh- plumlago, feem to have been employed by the ancients 
 
 denuni. to denote various oxides of lead ; but by the moderns 
 
 they were applied indifcriminatcly to all fubftances pof- 
 
 fefted of the following properties : Light, friable, and 
 
 S T R Y. 
 
 Part I. 
 
 tiep. 
 
 * Luyart. 
 
 %Id. 
 
 B Ptllitier, 
 Jinn, de 
 Cbim. xiii. 
 137- 
 
 i8ol 
 lUfcnvery 
 
 foft, of a dark colour and greafy feel, and which leave Molyhde- 
 
 a ttain upon the fingers. Scheele firft examined thcfe , """'• . 
 
 minerals with attention. He foinid that two very dif. 
 
 ferent fubllances had been conh)unded together. To 
 
 one of tlicfe, which is compofed of carbon and iron, 
 
 and which has been already defcrilied,- he appropriated 
 
 tlic word pJumbnoo ; the other he called mclyhdena. 
 
 Molydbena is compofed of fcaly particles adhering 
 nightly to each other. Its colour is bhiifli, very mucl» 
 relembling that of lead. Scheele analyfed it, and ob. 
 tained fulphur and a whitldi powder, which poffeflTed 
 the properties of an acid, and which, therefore, he call- 
 ei acid of molybdena. Bergman fiilt fufpcfted that the 
 bafis of this acid was a metal. It was at the requeft of 
 Bergman and Scheele that Mr Hielm began the labo- 
 rious courfe of experiments by which he lucceeded in 
 obtaining a metal from this acid. His method was to 
 form it into a pafte with linfeed oil, and then to apply 
 a very ftrong heat. This procefs he repeated feveral 
 times fucceffively. Klaproth and Ptrlictier alfo attempt- 
 ed to reduce it, and with equal fuccefs. The metal is 
 molybdenum (k). jgi 
 
 Molybdenum is externally of a whitifil yellow colour, Us proper- 
 but its frafture is a whitilh grey. ''^V 
 
 Hitherto it has only been procured in fmall grains, 
 agglutinated together in brittle maifes. 
 
 Its fpecific gravity is 7,500. It is almoft iafufible 
 in our fires. 
 
 When expofed to a ftrong heat, it is gradually con- 
 verted into a whitifli-coloured oxide *. When nitric * PeilttUr, 
 acid is poured upon it, molybdenum attracts oxygen, and Jmirr:. dt 
 is converted into a ■white oxide, which poffeffes the pro- ^hf- '/^S- 
 perties of an acid f . This is the molybdic acid. \ Hid. 
 
 Molybdenum combines readily with lulphur; and the 
 compound has exaftly the properties of molybdena, the 
 fubftance which Scheele decompounded %. Molybdena % Hid. 
 h there{ore fulphuret of molybdenum. The reafon that 
 Scheele obtained from it molybdic acid was, that the 
 metal combined with oxygen during his procefs. 
 
 Molybdenum is alfo capable of combining with phof- 
 phorus §. § Pellct'itr, 
 
 Few of the alloys of this metal have been hitherto ^""- *. 
 examined. 
 
 It feems capable of uniting with gold. The alloy is 
 probably of a white colour (j. {| Ruprecbt, 
 
 It combines readily with platinum while in the ftate ■^""- '''... 
 of an oxide. The compound is futible. Its fpecific g^""' ""' 
 gravity is 20,00 %. •[ Hitlm, 
 
 The alloys of molybdenum with filver, iron, and cop- .-//in. <fe 
 per, are metallic and friable ; thofe with lead and tin Citm. iv. 
 are powders which cannot be fufed *. ^^'ptlifur 
 
 Sect. XVIII. Of Uranium. '^^"fX' ~ 
 
 There is a mineral found in the George Wagsfort ^'"-gy"^' 
 mine at JohannGeorgenftadt in Saxony, partly in aQ;fj.Q^..ry 
 pure or unmixed ftate, and partly ftratified with other f urani- 
 kinds of ftoncs and earths. The firft variety is of a"m- 
 blackifli colour inclining to a dark iron grey, of a mo- 
 derate fplendor, a clofe texture, and when broken pre- 
 fents a fomewhat uneven, and, in the fmaileft particles, 
 a conchoidal furface. It is quite opaque, tolerably 
 hard, and on being pounded yields a black powder. Its 
 fpecific gravity is about 7,500. The fecond fort is 
 
 diftinguifhed 
 
 Chim, XI li. 
 137- 
 
 ( K ) This name was given it by Hielm.
 
 Part I. 
 
 C H E M 
 
 Uranium, dillinguillicd by a finer black colour, with here and there 
 
 » a rcddilh call ; by a ftronger liiftrc, not unlike that of 
 
 pitcoal; by an inferior hardnefs; and by a Ihadc of green, 
 which tinges its black colour when it is reduced to 
 
 » KUprM, 
 Crrll',J<!ur- 
 Fi il, feng. 
 Trann. 
 i. f 20. 
 
 iUU 
 
 l8j 
 Its proper- 
 ties. 
 J J6IJ. 233 
 
 $ Hi J, 
 
 powder ^. 
 
 This foffil was called pechLlenJe ; and mincralogifts, 
 milled by the name (l), iiad taken it for an ore of 
 zinc, till the celebrated Werner, convinced from its 
 texture, hardnefs, and fpecific gravity, that it was not 
 a blende, placed it among the ores of iron. Afterwards 
 he fufpefted that it contained tungsten ; and this con- 
 jefture was feemingly confirmed by the experiments of 
 fome German mincralogifts, publifhed in the Miners 
 Journal f. But Klaproth, whofe analyfes always dif- 
 play the moll confummate flvill, joined with the moll 
 rigid accuracy, examined this mineral about the year 
 1789, and found that it confifted chiefly of fulphur 
 combined with a peculiar metal, to which he gave the 
 name of uranium ( M ). 
 
 Uranium is of a dark grey colour ; internally it is 
 fomewhat inclined to brown f. 
 
 Its malleability is unknown. Its hardnefs is about 
 6. It requires a ftronger heat for fufion than raanga- 
 nefe. Indeed Klaproth only obtained it in very fraall 
 conglutinated metallic grains, forming altogether a po- 
 rous and fpongy niafs. — Its fpecific gravity is 6,440 §. 
 
 When expofed fcr fome time to a red heat, it fuffers 
 no change. By means of nitric acid, however, it may 
 be converted into a yellow powder. This is the yel/ow 
 oxide of uranium. This oxide is found native mixed 
 with the mineral above defcribed. Its affinities have not 
 yet been determined. 
 
 Uranium is capable of combining with fulphur. The 
 mineral from which Mr Klaproth firft obtained it is a 
 native fulphuret of uranium. 
 
 Nothing is known concerning the alloys or afHnities 
 of uranium. 
 
 Sect. XIX. Of Titanium. 
 
 Difcov rv There is a mineral found in Hungary which, from 
 
 of titanium, its external appearance, has been called redjhorl ; but 
 
 Klaproth, who examined It about the year ijg^, dif- 
 
 covered that It confifted chiefly of a peculiar metal, to 
 
 which he gave the name of titanium. 
 
 ''5 Titanium is of a brownllh red colour, and confider- 
 
 ^s^ proper- ^y^ luftie. It is brittle. Its hardnefs Is 9 ; its fpecific 
 
 gravity 4,18. 
 
 When expofed to a ftrong heat in a clay crucible, it 
 fuffercd no alteration, except that its colour became 
 browner ; but in a coal crucible it loft its luftre and 
 broke to pieces. 
 
 It Is found naturally cryftalllzed in right-angled qua- 
 drangular prifms, longitudinally furrowed, and about 
 half an Inch In length. 
 
 No acid had any effeil in oxidating it ; but when 
 mixed with five times Its weight of potafs, and heated 
 -i|i a porcelain furnace, it melted, and formed when cold 
 SuppL. Vol. I. Part I. 
 
 I S T R Y. 249 
 
 a denfe greyidi mafs, the furface of which was cryRal- TcMurium 
 llzcd. When difTolved In boiling water, it foon let fall » 
 a white powder, weighing about one-third more than 
 the titanium employed. This is the oxide of titanium. 
 Fifty grains of it were reduced by ignition to 38. 
 While hot it was yellowlfli, but, like oxide of zinc, be- 
 came white as it cooled. When heated on charcoal, 
 it aflumes firft a rpjy red, and afterwards a //ate blue co- 
 lour, and at laft melts into an imperfetl bcid with a 
 finely ftriated furface. ' Mr Klaproth did not fucceed 
 in reducing it to the metallic ftate. 
 
 Titanium does not feem to have any affinity for ful- 
 phur *. *M*Grrgor. 
 
 There was a fubftance dlfcovciTd by Mr M'Gregor in |vt '^''l 
 the valley of Menachan In Cornwall, and hence called „ijj 
 menaclianite. Upon this fubftance Mr M'Gregor made 
 a very Interefting fet of experiments, which were pub- 
 lilhed in the Journal de Phyiiqiie for 1791. He fuf- 
 pefted It to contain a new metal. From its properties, 
 Mr Kirwan conjedlured that it was the fame with tita- 
 nium f ; and this conjedlure has been very lately con- 1. ""''''• 
 firmed by Mr Klaproth, who analyfed menachanite, and"" ^^'' 
 found it to be an ore of that metal. 
 
 Sect. XX. Of Tellurium. 
 
 .87 
 
 In the mountains of Fatzbay, near Zalethna in Tran- DIfcovery 
 fylvania, there is a mine called Mariahilf ; the ore of°f """"' 
 which is wrought for the gold that it contains. Mr""'' 
 Muller of Relchenftein examined it in 17SJ, and fufpec- 
 ted that it contained a new metal ; and Bergman, to 
 whom he had fent fome of the ore, was of the fame opi- 
 nlou : but the quantity of the mineral which thefe che- 
 mifts had examined was too inconfiderable to enable 
 them to decide with certainty. Klaproth analyfed a 
 larger quantity of it about the year 1797, and found 
 that 1000 parts of it confifted of 72 parts of Iron, 
 2,5 of gold, and Q2y,5 of a new metal, to which he has 
 given the name of tellurium (n). 18S 
 
 Tellurium is of a white colour like tin, approaching'?' P'"?"" 
 fomewhat to the grey colour of lea 1 1. V*^; .. .l 
 
 It IS very brittle and triable. Its iratture is laminated. rbHofoflncal 
 Its fpecific gravity is 6, 1 1 5. Magazine, 
 
 It is as eafily melted as lead. When fufFered to cool'- 7^" 
 quietly and gradually, it readily aflumes a cryftallized 
 furface §. § ^-'l'>-- 
 
 When heated by the blowpipe upon charcoal, it burns 
 with a very lively flame of a blue colour, inclining at the 
 edges to green. It is fo volatile as to rife entirely in a 
 whitifli grey fmoke ; at the fame time It exhales a dif- 
 agreeable odour like that of radlfhes. This fmoke is 
 the white oxide of tellurium, which may be formed alfo 
 by dlfl^olving the metal In iiitroinurlatic acid, and pour- 
 ing into the faturated folutlon a quantity of water : a 
 white powder precipitates, wlilcli is the oxide ||. " II Kl''f"tli. 
 
 When this oxide is heated tor fome time in a retort, 
 
 it melts, and appears, after cooling, of a yellow ftraw 
 
 colour, having acquired a fort of radiated texture. When 
 
 I i formed 
 
 (l) Blende is tTie name given to ores of zinc. 
 
 (m) From Uranus (oujawo^), the name given by Mr Bode to the new planet difcovered by Herfchel ; which 
 name the German aftronomers have adopted. Mr Klaproth c^.lled the metal at firft uranile ; but he afterwards 
 changed that name for uranium. 
 
 (n) Mr Kirwan, in the new edition of his Mineralogy, which was publiflied before Mr Klaproth's experi- 
 ments were known, gives this metal the name of Syhanite. — Tellurium exifts in fevcral other mines in the fame 
 Tnountalns.
 
 CHEMISTRY, 
 
 formed into a pafte with any fat oil, and diftllled in a When placed on red hot cliarcoal, the metal burns as ' 
 
 ' red heat, brilh'ant metallic drops are obferved to cover well as the fulphur with a blue flame, 
 the upper part of the retort, which at intervals fall to Tellurium amalgamates with mercury by fimple tritu- 
 
 the bottom of tlie veflel, and are immediately replaced rationf. — Theotherpropertie5ofthismetalareunknown.j 
 by others. After cooling, metallic fixed drops are 
 
 found adhering to the fides and at the bottom of the A new metal has lately been difcovered by Vauquclin ( 
 
 veiTel ; the remainder of the metal is reduced. Its fur- in the red lead ore of Siberia. It is grey, very hard, 
 
 face is brilliant and almoft always cryftallized. When brittle, and eafily cryftallizes in fmall needles J. Het 
 
 this oxide Is expofed to heat on charcoal, it is reduced has given it the name oi chromum (o). 
 ♦ iT/a/iro/i. with a rapidity that refembles detonation ♦. We have now defcribed all the metals at prefent' 
 
 TeUurium combines with fulphur. The fulphuret of known. The following table will exhibit in one view 
 
 this metal is of a grey colour and radiated ftvufture. their principal properties. 
 
 Metal*. 
 
 Colour. 
 
 4ara- 
 nefs. 
 
 Specific 
 gravity 
 
 Fuling 
 Point. 
 
 32W.(P) 
 1398 F. 
 
 Mallea- 
 bility. 
 
 Duaility 
 
 
 Gold. 
 
 Yellow. 
 
 6 
 
 7t 
 
 19,300 
 
 28 2000 
 
 500 
 270 
 
 
 Silver. . 
 
 White. 
 
 IO,J10 
 
 28 W. 
 
 1C44 F. 
 
 160000 
 
 
 Platinum. 
 
 White. 
 
 23,000 
 
 150W..? 
 
 
 above 
 500 
 
 
 Mercury. 
 
 White. 
 
 
 13,568 
 
 -39 F- 
 
 
 
 
 
 Copper. 
 
 Red. 
 
 8 
 
 8,870 
 
 27 W. 
 1449 F. 
 
 299J 
 
 
 Iron. 
 
 Blue-grey. 
 
 9 
 
 7,788 
 
 150W. 
 20577 F. 
 
 
 450 
 
 Magnetic. 
 
 Tin. 
 
 White. 
 
 6 
 
 5 
 6 
 
 6i 
 6 
 
 7 
 
 7.299 
 
 410 F. 
 
 2000 
 
 49 
 
 
 Lead, 
 
 Blue-white. 
 
 11.352 
 
 540 F. 
 
 
 29i 
 
 
 Zinc. 
 
 White. 
 
 7,190 
 
 700 F. 
 
 
 
 
 
 Antimony. 
 
 Grey. 
 
 6,860 
 
 700 F. 
 
 
 
 
 
 
 Bifmuth. 
 
 Yellow-white. 
 
 9,822 
 
 460 F. 
 
 
 
 
 
 
 Arfenic. 
 
 White. 
 
 8,310 
 
 400 F. ? 
 
 
 
 
 
 
 Cobalt. 
 
 White. 
 
 8 
 8 
 
 8,150 
 
 9,000 
 
 130 W. 
 17977 F. 
 
 
 
 Magnetic. 
 
 Nickel. 
 
 White. 
 
 150 W. 
 
 20577 F. 
 
 
 
 Magnetic. 
 
 Manganefe. 
 
 White. 
 
 8 
 6 
 
 7,000 
 
 150 W. 
 20577 F. 
 
 
 
 
 
 
 
 Magnetic. 
 
 Tungften. 
 
 Brown. 
 
 17,600 
 
 
 
 
 
 Molybdenum 
 
 Grey. 
 
 7,500 
 
 
 
 
 
 
 
 Uranium. 
 
 Grey. 
 
 6 
 
 6,440 
 
 
 
 
 
 Titanium. 
 
 Red. 
 
 9 
 
 4,180 
 
 
 
 
 
 
 
 Tellurium. 
 
 White. 
 
 
 6,115 
 
 540 F. 
 
 
 
 
 
 
 Chromum. 
 
 Grey. 
 
 
 
 
 
 
 
 
 
 (o) From xri"'' becaufe it poffefles the property of giving colour to other bodies in a remarkable degree. 
 \t) W. Wedgewood's pyrometer. F. Fahrenheit's thermometer. We
 
 Part I. 
 
 C H E M 
 
 Chhn. xxiu. 
 €5.— A^i- 
 thoijln's 
 Jcur/t. i. 
 
 Tellurium. V.'c liave fccii tliat ali the metals arc capable of com- 
 
 ^-—v—— bining with oxygen ; that almoll every one forms va- 
 
 Remarks '""'"^ oxides, containing different quantities of oxygen, 
 
 on metallic and varying in colour and other properties according to 
 
 oxides. tlie proportion of oxygen which they contain. No part 
 
 of chemillry has more engaged the attention of philo- 
 
 fophcrs tlian the metallic oxides ; and yet fuch is the 
 
 difficulty of the fubjeft, that fcarcely any part of che- 
 
 iTiillry is more imperfectly underllood. 
 
 We neither know how many oxides every particular 
 metal is capable of forming, nor the manner in which 
 they are formed : neither have the dhferenccs between 
 oxides of the fame metallic bale been inquired into ; 
 thougli there cannot be a doubt tliat they differ, not 
 only in their affinities, but in many of their other pro- 
 perties. The -white oxide of manganefe, for inllance, 
 combines readily with acids, but the black is incapable 
 of uniting with any. 
 
 Mr Proud, in a very valuable paper which he lately 
 * Am.de publiflied concerning the oxides of iron*, hints that 
 metals are only capable of two degrees of oxidation, or, 
 which is the fame thing, that only two difierent oxides 
 can be produced from the fame metal. We think he 
 has proved this completely as far as iron is concerned ; 
 and probably the obfen-ation holds good with refpeA 
 to many other metals. Arfenic, copper, tin, molybde- 
 num, and perhaps even mercury, feem to be capable of 
 only two degrees of oxidation ; but it would require a 
 ■very numerous and accurate fet of experimcntb to be 
 able to determine the matter, or even to form a pro- 
 bable conjefture. Analogy is certainly againll the fup- 
 pofition ; for it has been demonftrated that fome fub- 
 ftances at lead are capable of combining with three dif- 
 ferent dofes of oxygen (cl)> and why may not this be 
 the cafe alfo with the metals ? 
 
 There is one obfervation, however, which we owe to 
 Mr Proud, the truth of which cannot be doubted, and 
 which is certainly of the higheft importance — that me- 
 tals are not capable of indetinite degrees of oxidation, 
 but only of a certain number ; and that every particular 
 oxide confids of a determinate quantity of the metal 
 and of oxygen chemically combined. Iron, for inftance, 
 is not capable, as has been fuppofed, of uniting with 
 oxygen in all the intermediate degrees between tVs and 
 ^~, and confequently of forming 20 or 30 different 
 oxides ; it can only combine with precifely -^-^ parts, 
 or ^^ parts, and with no other proportions ; and there- 
 fore is only capable of forming two oxides, the green 
 and the brown. In like manner, every other metal com- 
 bines with certain proportions of oxygen, and forms 
 cither two oxides or more according to its nature. To 
 talk therefore of oxidating a metal indefinitely is not 
 accurate, except it be intended to fignify the combi- 
 ning of part of it with oxygen, while the red remains in 
 its natural date. If iron be oxidated at all, it mull be 
 combined with -i^-'- of oxygen ; if it be oxidated more 
 than this, it muft be combined with xsV oi oxygen. 
 
 We beg leave to add another obfervation, which we 
 confider as of no lefs importance, and which will ferve 
 in fome meafure to modify and explain what has been 
 juft now faid. Oxygen is capable of uniting with me- 
 
 I S T R Y. 251 
 
 tals, or with any other fubftance for which it has an Telljrium. 
 affinity, only in one determinate proportion. Iron, for in- ' v ' 
 ftance, and oxygen can only combine in the proportion 
 of 73 parts of iron and 27 of oxygen. Thefe two quan* 
 tities laturatc cacli other, and form a compound which 
 is incapable of receiving into it any more oxygen or 
 iron : this compound is the green oxiJc of iron. How 
 comes it then, it will be alked, that there is another 
 oxide of iron, the broiun oxide, which contains 52 parts 
 of iron and 48 of oxygen, proportions certainly very 
 different from 73 and 27 ? We aufwer, there is an af- 
 finity between the green oxide of iron and oxygen ; they 
 are capable of combining together, and of faturating 
 each other in the proportion of about 71,5 parts of 
 green oxide and 28,5 of oxygen ; and the compound 
 which they form is the Irotun oxide, which of courfe 
 contains 52 parts of iron and 48 of oxygen : But then 
 it is not formed by the combination of thele two fub- 
 ftances direftly, but by the combination of the green 
 oxide and oxygen. In like manner, the arfenic acid is 
 not compofed of arfenic and oxygen combined direiftly, 
 but of white oxide of arfenic combined with oxygen. 
 The vei"y fame thing takes place in all the other metals. 
 We cannot at prefent prove the truth of this obferva- 
 tion in a fatisfaSory manner, becaufe it would be ne- 
 ceffary to draw our proofs from combinations which are 
 yet uridefcribed ; but we will have occahon to confider 
 it afterwards. 
 
 We have feen that all the metals hitherto tried are 
 capable of combining with fulphur, except gold and 
 titanium ; that all of them on which the experiments 
 have been made can be united with phofphorus ; and 
 that three of them, iron, zinc, and manganefe, united 
 with carbon ; and perhaps many more of them may 
 hereafter be found capable of affuming the form of car- 
 burets. 
 
 We have feen, too, that they are capable of uniting 
 with one another and forming alloys. This was long rec- 
 koned peculiar to metals, and it is at prefent one of the 
 bed cviterions for determining the metallic nature of 
 any fubdance. Much is wanting to render the che- 
 midry of alloys complete. Many of them have never 
 been examined ; and the proportions of alniod all of 
 them are unknown. Neither has any accurate method 
 been yet difcovered of determining the affinities of me- 
 tals for each other. The order of af5,nities which we 
 have given for each metal was determined by Bergman ; 
 but he acknowledged himfelf that he wanted the pro- 
 per data to enfure accuracy. 
 
 Chap. IV. 0/" Earths. 
 
 The word earth, in common language, has two mean 
 ings ; it fomctimes fignifies \}\t globe which we inhabit, 
 and fometimes the mould on which vegetables grow. 
 Chemifts have examined this mould, and have found 
 that it confids of a variety of fubdances mixed together 
 without order or regularity. The greated part of it, 
 however, as well as of the ifones, which forni apparently 
 fo large a proportion of the globe, confids of a fmall 
 number of bodies, which have a variety of commmon pro- 
 I i 2 perties. 
 
 (q^) We (hall fee afterwards that azot is one of thefe.
 
 191 
 
 Pr >iLr!ic5 
 ct tatths. 
 
 llIEC, 
 
 C H E M I 
 
 perties. Thcfe bodies chemifts have agreed to clai's to- 
 gether, and to denominate larths. 
 
 Everv body which poflclTts the following properties 
 is an tcrth : 
 
 1. Infolable in water, or nearly fo ; or at leail be- 
 coming infoluble when combined with carbonic acid. 
 
 2. Little or no tafte or fmell ; at leaft when com- 
 bined with carbonic acid. 
 
 ^. Incombuftible, and incapable while pure of being 
 altered by the fire. 
 
 4. A fpecific gravity not exceeding 4,9. 
 
 5. When pure, capable of afTuming the form of a 
 white pow'der. 
 
 The earths at prefent known amount to ten ; the 
 ^nsmes of which are, liir.e, magnefia, barytcs, ftrontitts, 
 alumina, fiiica, jargonia, glucina, yttria, aguftina. 
 
 Every one of the above charafteriilics is not perhaps 
 rigoroufly applicable to each of thefe bodies ; but all of 
 them polTefs a fufficient number of common properties 
 to render it ufeful to arrange them under one clafs. 
 
 Sect. I. Of Lime. 
 
 Lime has been known from the earlieft; ages. The 
 ancients employed it in medicine ; it was the chief in- 
 gredient in their mortar ; and they ufed it as a manure 
 jn, to fertilize their fields. 
 Method of It abounds in many parts of the world, or perhaps 
 procuring we fhruld rather fay, that there is no part of the world 
 where it does not exift. It is found pureft in lime- 
 ftones, and marbles and chalk. None of thefe fubllances, 
 however, is, llriftly fpeaking, liifie ; but they are all 
 capable of becoming lime by a well-known procefs, by 
 keeping them for fome time in a white heat : this procefs 
 is called the burning of lime ; the produti; is denominated 
 quicklime. This lait fubftance is what we call lime. 
 
 Pure limJ is of a white colour, moderately hard, but 
 eafily reduced to a powder. 
 
 It has a hot burning tafte, and in fome meafure cor- 
 rodes and deftioys the tfxture of thofe animal bodies to 
 which it is applied. It has no fmell. Its fpecific gra- 
 
 * KirwansVltJ is 2,3 *. 
 
 Miner, i. J. if water be poured on newly burnt lime, it fwells 
 and falls to pieces, and is foon reduced to a very fine 
 powder. In the mean time, fo much heat is produced, 
 that part of the water flies of in vapour. If the quan- 
 tity of lime flacked (as this procefs is termed) be great, 
 the heat produced is fufSicient to fet fire to combuftibles. 
 In this manner veffels loaded with lime have fometimes 
 been burnt. When great quantities of lime are flacked 
 in a dark place, not only heat, but light alfo is emitted, 
 iJcur.Je as Mr Pelletier has obferved +■ When flacked lime is 
 J'ivf.t.s.i- weighed, it is found to be heavier than it was before. 
 This additional weight is owing to the combination of 
 part of the water with the lime ; which water may be 
 feparated again by the apphcation of a red heat ; and 
 by this procefs the lime becomes juft what it was before 
 i Dr Bhti. being flacked J. 
 
 Six hundred parts of water, at the temperature of 
 60", diffolve about one part of lime ; boiling hot water 
 diffolves about double that quantity §. This folution 
 is called ime-mater. It is limpid, has an acrid tafte, 
 and changes vegetable blue colours to green. One 
 ounce troy of lime-water contains about one grain of 
 Ume. 
 
 194 _ 
 
 Properaes 
 of lime. 
 
 .195 
 Lime-wa- 
 ter. 
 
 5 Kirwiin^s 
 THiiur. i. 5 
 
 S T R Y. Part I. 
 
 One thoufand parts of lime are capable of abfovbing, Lime. 
 and retaining, at a heat of 600°, 228 parts of water*. ~"^ . -' 
 
 Lime has never yet been obtained in the ttate of "i*"'' 
 cry Hals. 
 
 It is incapable of being fufed by the moft violent 
 heat that can be produced in furnaces, or even by the 
 mod powerful burning-glaiTes. jtjg 
 
 Lime unites readily with fulphur, and forms y'u^iur^'/Sulphuret, 
 of lime. This compound may be obtained by niixing^""^ 
 un.Oacked lime and flowers of fulphur together, and 
 adding a little water. The heat produced by the flack- 
 ing t)f the lime is fufficient to make the fulphur and 
 the lime unite. This fulphuret is of a red colour. 
 When water is poured on it, fulphurated hydrogen gas 
 is emitted. The fulphur is gradually converted into 
 fulphuric acid by uniting with the oxygen of the water, 
 the hydrogen of which flies off in the form of gas, dif- 
 folving at the fame time a part of the fulphur. j.- 
 
 It is capable alfo of combining with phofphorus. — Phofphurei 
 The phofphuret of lime decompofes water by the affift- of lime, 
 ance of a moderate heat, and gives out phofphurated 
 hydrogen gas. .^g 
 
 Limeflone and chalk, though they are capable of be- Caufe of 
 ing converted into lime by turning, pofTefs hardly any tiie diffe- 
 of the properties of that aftive fubilance. They aie""'-'^ 'f' 
 taflelefs, fcarcely foluble in water, and do not pf rcep- j^^j^g ^^^ j 
 tibly aft on animal bodies. Now, to what are the newimie, 
 properties of lime owing ? What alteration does it un- 
 dergo in the fire ? 
 
 It had been long known that limeflone lofes a good 
 deal of weight by being burned or calcined. It was na- 
 tural to fuppofe, therefore, that fomething was iepara- 
 ted from it during calcination. Accordingly, Van Hel- 
 mont, Ludovicus, and Macquer, made experiments in 
 fucceffion, in order to difcover what thai fomething was; 
 and they concluded from them that it was pure -water, 
 which the lime recovered again when expofed to the 
 atmofphere. As the new properties of lime could j 
 hardly be afcribed to this lofs, but to fome other caufe. According 
 Stahl's opinion, like all the other chemical theories oftoStahli 
 that wonderful man, was generally acceded to. He 
 fuppofed that the new properties which lime acquired 
 by calcination, were owing entirely to the more minute 
 divifion of its particles by the aftion of the fire. Boyle 
 indeed had endeavomed to prove, that thefe properties 
 were owing to t\te fixation of fire in the lime : a theory 
 which was embraced by Newton and illuftrated by 
 Hales, and which Meyer new modelled, and explained 
 with fo much ingenuity and acutenefs as to draw the 
 attention of the moll diftinguifhed chemifts. But while 
 Meyer was thus employed in Germany, Dr Black, of 
 Edinburgh, publifhedthofe celebrated experimentswhich 
 form fo brilliant an era in the hiftory of chemiftry. j^^ 
 
 He firft afcertained that the quantity of water fepa- Explained 
 rated from limeftone during its calcination was not near-byDrBlack- 
 ly equal to the weight which it lofL He concluded in 
 confequence that it muft have loft fomething elfe than 
 mere water. What this could be, he was at firft at a 
 lofs to conceive ; but recoUefting that Dr Hales had 
 proved, that limeftone, during its folution in acids, 
 emitted a great quantity of air, he conjeftured that this 
 might probably be what it loft during calcination. He 
 calcined it accordingly, and applied a pneumatic appa- 
 ratus to receive the produft. He found his conjefture 
 
 verified ;
 
 'artl. C H E M 
 
 Lime, verified ; and that the air and lie water which fepara- 
 -— V ' ted from the lime, were together precifely equal to the 
 lofs of weight which it had fuflained. Lime therefore 
 owes its new properties to the lofs of air; and limtftone 
 differs from lime merely in being combined with a certain 
 quantity of air : for he found that, by reftoring again 
 the fame quantity of air to lime, it was converted into 
 limeftone. This air, becaufe it exiflcd in lime in a fix- 
 ed ilate, he called Jixed air. It was afterwards exami- 
 ned by Dr Prieftley and other philofophers, found to 
 poffefs peculiar properties, and to be that fpecies of gas 
 now known by the name of carbonic acid gas. Lime 
 then is a fimple fubftance, that is to fay, it has never 
 yet been decompounded ; and limeftone is compofed of 
 carbonic acid and lime. Heat feparates the carbonic 
 acid, and leaves the lime in a ftatc of purity. 
 
 The affinities of lime, according to Bergman, are as 
 follows : 
 
 Oxalic acid. 
 
 Suberic (r) ? 
 
 Sulphuric, 
 
 Tartarous, 
 . Succinic, 
 
 Phofphoric, 
 
 Saccholaftic, 
 
 Nitric, 
 
 Muriatic,. 
 
 Sebacic, 
 
 Fluoric, 
 
 Arfenic, 
 
 Formic, 
 
 La£lic, 
 
 Citric, 
 
 Benzoic, 
 
 Sulphurous, 
 
 Acetous, 
 
 Boracic, 
 
 Nitrous, 
 
 Carbonic,- 
 
 Pruffic, 
 
 Sulphur, 
 
 Phofphorus,, 
 
 Water, 
 
 Fixed oil. 
 
 Sect. IL Of Magnefa. 
 
 About the beginning of the eighteenth century, a 
 Roman canon expofed a white powder to fale at Rome 
 a» a cure for all difeafes. This powder he called mag- 
 nejja alba. He kept the manner of preparing it a pro- 
 found fecret ; but in i 707 Valentini informed the pub- 
 lic that it might be obtained by^calcining the lixivium 
 which remains after the preparation of nitre ; and two 
 
 I S T R Y. 253 
 
 years after, Slevogt difcovered that it might be prcci- Magnelia.^ 
 pitated by potafs from the mother ley (s) of common ' 
 fait. This powder was generally fuppoled to be lime, 
 till Frederic Hoffman oblerved that it formed very dif- 
 ferent combinations with other bodies *. But little was • Bfrgmjn, 
 known concerning its nature till Dr Black publifhed his i. 305. 
 celebrated experiments in 1755. Margraf publini<;d a 
 differtalion on it in 1759, and Bergman another in 
 1775, in which he collefted the ol)l'crvatioiis of thefe 
 two philofophers, and which he enriched alfo with many 
 additions of his own. - ^^, 
 
 As magnefia has never yet been found native in a Methmi of 
 ftate of purity, it may be prepared in the following procuring 
 manner: Sulpliat af magnefia, a fait compofed of this"' 
 earth and fulphuric acid, exifts in fea- water, and in ma- 
 ny fprings, particularly fome about Epfom, from which 
 circumftancc it was formerly called Epfom fait. This 
 fait is to be difl'olved in water, and half its weight of 
 potafs added. The magnefia is immediately precipita- 
 ted, becaufe potafs has a ftronger affinity for fulphuric 
 acid. It is then to be wafhed with a fufficient quantity 
 of water, and dried. 
 
 Magnefia thus obtained is a very foft white powder, jt^ p,opgr„ 
 which has very little tafte, and is totally deflitute of tits, 
 fmcll. Its fpecific gravity is about 2,3 f. ^ K!r-war's 
 
 It is foluble in about 7900 times its own weight of-^^'"""- '■ *• 
 water at the temperature of 60° J. j juj. 
 
 Even when combined with carbonic acid (for which it 
 has a ftrong affinity) it is capable of abforbing and re- 
 taining 14^ times its own weight of water, without let- 
 ting go a drop ; but on expofure to the air, this water 
 evaporates, though more flowly than it would from lian-. 
 
 Magnefia has never yet been obtained in a cryllalli- 
 zed form. 
 
 It tinges vegetable blues of ati exeedingly fliglit 
 green. 
 
 It is not melted by the ftrnngeft heat which it has 
 been pofilble to apply ; but Mr D' Aicet obferved that, 
 in a very high temperature, it became foinewhat agglu- 
 tinated. 
 
 When magnefia and fulphur are put into a veffel of 
 water, and kept for fome time expofed to a moderate 
 heat, they combine, and form fulphuret of magnefia ; 
 which, according to Fourcroy, is capable of cryftalli- 
 zing. 
 
 The phofphuret of magnefia has never been examined • 
 
 Equal parts of lime and magnefia mixed togetlier, Effeift of 
 and expofed by Lavoifier to a very violent heat, did not heat "" 
 
 of lime and ■ 
 
 melt ; neither did they melt when Mr Kirwan placed 
 them in the temperature of 1 50° Wedgewood. Tlie,^^ j^^jj^ 
 following Table, drawn up by Mr Kirwan from his own 
 experiments, fhcws the effect of heat on thefe two earths 
 mixed together in different proportions. 
 
 Proportions. 
 
 (r) The affinity of this acid for lime is inferior to the oxalic, which decompofes the fuberat of lime, ya- 
 mefon's Mineral, of Shetland and /Irran, p. 168. 
 
 (s) The mother ley is the liquid that remains after as much as poflible of any fait has been obtained from 
 it. Common fait, for inflance, is obtained by evaporating fea-water. After as much fait has been extracted 
 from a quantity of lea-water as will cryflallize, there is iliil a portion of liquid remaining. This portion is t'.ie 
 mother lev.
 
 354 
 
 Magnefil, 
 
 C H E M I 
 
 Propoitioii.s, 
 
 -■'H.at. ■■' 
 
 Eflea. 
 
 80 Lime 
 
 20 Mag. 
 
 i50°We(lg. 
 
 Went through the crucible. 
 
 75 Lime 
 25 Mag. 
 
 160 
 
 Went through the crucihle. 
 
 66 Ijime 
 33 Mag. 
 
 
 Went through the crucible. 
 
 20 Lime 
 
 ho Mag. 
 
 165 
 
 Did not melt. 
 
 33 Lime 
 66 Mag. 
 
 138 
 
 Did not melt. 
 
 30 Lime 
 10 Mag. 
 
 156 
 
 Melted into a fine greenifh 
 yellow gla.s; but the crucible 
 was corroded throughout. 
 
 406 ,. n 
 
 Affinities of The affinities of magnefia, according to Bergman, are 
 magnefia. 33 follows ; 
 
 Oxalic acid, 
 
 Phofphoric, 
 
 Sulphuric, 
 
 Fluoric, 
 
 Sebacic, 
 
 Arfcnic, 
 
 Saccholaftic, 
 
 Succinic, 
 
 Nitric, 
 
 Muriatic, 
 
 Tartarous, 
 
 Citric, 
 
 Formic, 
 
 La&ic, 
 
 Benzoic, 
 
 Acetous, 
 
 Boracic, 
 
 Sulphurous, 
 
 Nitrous, 
 
 Carbonic, 
 
 Pruffic, 
 
 Sulphur, 
 
 Phofphorus ? 
 
 Water. 
 
 Sect. IIL Of Barytes. 
 
 A ^-ERY heavy mineral is found in Sweden, Germa- 
 ny, and Britain, which Margraf coiifidered as a com- 
 pound of fulphuric acid and lime. But Schecle and 
 Gahn analyfed it in 1774, ^f"^ found that it cnnfillcd 
 of fulphuric acid combined with a peculiar fpecies of 
 earth. This analyfis was foon after confirmed and ex- 
 tended by Bergman. The earth was at firft called terra 
 ponderofa, heavy earth, on account of the great fpecific 
 gravity of the fubllance from which it was obtained. 
 Morveau called it borate (from eapv;, heavy), which 
 Bergman changed into barytes ; and this lalt term is now 
 univerfally adopted. 
 
 107 
 Difcovery 
 of barytes. 
 
 S T R Y. Parti. 
 
 Barytes is generally found combined eitlicr with ful- Barytes. 
 jihuric or carbonic acid. From the firft of theie conv '~~^ "^ 
 pounds, which is by far the moll common, it may bej^^'^^^ ^ ^ 
 obtained by the following procefs : obtaiuing 
 
 Reduce the mineral to a powder and mix it with 2 ^ it- 
 its weight of carbonat of foda (t), previoufly deprived 
 of all its water. Expole the mixture to a red heat for 
 an hour and a half, avoiding fufion, and a double de- 
 compofition takes place ; the fulphuric acid unites with 
 the foda, while the carbonic acid combines with the ba- 
 rytes. Walh it in a fufficient quantity of water to dif- 
 folve the compound of fulphuric acid and foda, the car- 
 bonat of barytes, which is almoft infoluble, remains be- 
 hind. Left it (hould be mixed with fome other earths, 
 which is generally the cafe, boil it for three hours in 
 ten times its weight of diftilled vinegar, the fpecific gra- 
 vity of which is 1,033 ; by which the barytes will be 
 difiolved, and likewife the lime and magnefia, if there 
 happen to be any; but every other earth (u) remains 
 untouched. Pour off the folution, and add to it ful- 
 phuric acid as long as any precipitate is formed. This 
 precipitate confifts of the whole barytes and the lime 
 (if there be any) combined with fulphuric acid. Wafli 
 it in 50 times us weight of water, and all the lime will 
 be diffolved. There will now remain nothing but bary- 
 tes combined with fulphuric acid, which may be decora- 
 pofed as before by carbonat of foda *. The carbonic *A/s'!iet'un, 
 acid may then be feparated by applying a very violent^""- ^5.. 
 heat f ; or, what is better, nitric acid may be poured , ^' '"■ 
 upon it, which will feparate the carbonic acid and com- £j,„ Tranf. 
 bine with the barytes ; and then the nitric acid may beiv. 36. 
 driven off by a moderate heat J". t ^"ir"^ 
 
 Bary tes thus obtained i, a light, fpongy, porous bo- ^" ji",Tdc 
 dy, which may be very eallly reduced to powder. It c/j/m. ixi. 
 has a harfli and more cauftic taftc than iime; and when 276. ' 
 
 taken into the ftomach, proves a moft violent poifon. *°9 
 It has no perceptible fmell. 
 
 Its fpecific gravity has not yet been afcertained. 
 It imbibes water with a hiffmg noife, but, according 
 to Dr Hope, without fvvelling or fplitting as lime 
 does ^. However, wlien expoted to the air, as Four- 5 FJ'tx. 
 croy and Vauquelin inform us, it efBorelces, cracks, '^runf. ibid. 
 burfts, fwells up, heats, and becomes white, by abforb- 
 ing moifture]]. I| Ann.d: 
 
 Cold water diffolves about ^^xh. part of its weight of ''''"■ '^''■ 
 barytes, and boiling water more than half its weight. ° , 'cy„„,,' 
 As the water cools, the barytes is depofited in cryllals,,^/ 1.335. 
 the (hape of which varies according to the rapidity with 
 which they have been formed. When moft regular, they 
 are flat hexagonal prifms, having two broad fides, with 
 two intervening narrow ones, and terminated at each 
 end by a four-fided pyramid, which in fome inltances 
 conftitutes the larger part of the cryftal. When formed 
 flowly, they are diftintl and large ; but when the water 
 is faturated with barytes, they are depofited rapidly, 
 and are generally more (lender and delicate. Then, too, 
 they are attached to one another in fuch a manner as to 
 affume a beautiful foliacious appearance, not unlike the 
 leaf of a fern f . ^ Ho/f, iM 
 
 Thefe cryftals are tranfparent and colourlefs, and ap- 
 pear to be compofed of about 53 parts of water and 47 
 
 of 
 
 Its proper- 
 ties. 
 
 (t) Soda is an alkali, which ftiall be afterwards defcribed. Carbonat of foda is foda combined with carbonic 
 acid, the common ftate in which it is obtained ; potafs might alfo be ufed. 
 (n) Except ftrontites, which Pelletier has deteAed in this mineral.
 
 Part I 
 
 Baryre«. 
 
 St'ontitCJ. 
 
 • //. 
 
 and Vauque- 
 Itn^ ibiJ, 
 
 iio 
 Sulphuret 
 cf barjtef. 
 
 J Faurcfcy. 
 
 5 Lavoiper ^ 
 Ac^d. Par. 
 
 311 
 
 Its affinu 
 tics. 
 
 CHEMISTRY. 
 
 ofbarytes. "WTieti espofcd to the heat of boiling wa- 
 
 ter, they undergo iht watery fuji on, or, which ib the 6ect. IV. Of Slronliles. 
 
 fame thin^, they melt without loling any of the water About the year 1787, a mineral was brought to^^i/.'* 
 
 which they contain. A ftronger heat makes the water Edinhurgb, by u dealer in foffils, from tlie lead mine of,,f'ltron^ 
 
 fly oir. When expofed to the air, they attrattcaibo- Strontian in Argylrfhire, where it i,s found imbedded cites. 
 
 ric acid, and crumble into dull. They are foluble in in the ore, mixed witli feveral other fi.bllances. It is 
 
 174 parts of water at the temperature of 60° ; but boil- fometimcs tranfparcnt and colouilefs, but generally has 
 
 jng water difTolves any quantity whatever : the rcafon a tinge of yellow or green. Its liardnefs is c. Its fpe- 
 
 of wliich is evident; at that temperature tlieir own wa- cific gravity varies from 3,4 to 5,726. Its texture is 
 
 ter of cryllallization is fsfficient to keep them in folu- generally tihrous; and fometimcs it is found cryftallized 
 
 tion *. _ in flendcr prifmatic columns of various lengths*. « fT„A, £, 
 
 Water faturated with barytes is called barytic lualer. This mineral was generally confidered as a carbonate-". Iri/i/:' 
 
 It has the property of converting vegetable blues to a ofbarytes; but Dr Crawford haviu"- obferved fome'v-44- 
 
 green- _ differences between its folution in muriatic acid and tliat 
 
 When barytes is expofcd to the blowpipe on a piece ofbarytes, mentioned in his treatife on Mur'iat of Bury - 
 
 of charcoal, it fufes, bubbles up, and runs into globules, tes, publiihed in 1790, that it probably contains a new 
 
 which quickly penetrate the cliarcoal \. This is pro- earth, and feiit a fpecimen to Mr Kirwan that he might 
 
 .bably in confequence of containing water; for I, avoifier examine its properties. Dr Hope had alfo fufpedted 
 
 found barytes not affeded by the Urongell beat which that its balls diflertd from barytes; and accordinfrly he 
 
 he could produce. made a let of experiments on it in 1791, which were 
 
 Barytes combines readily with fulphur. The eafieft read to the Royal Society of Edinburgh in J702. 
 
 way of forming fuiphuret of barytes is to mix eight Thefe experiments fully proved that it contained a pe- 
 
 parts of fulphat of barytes with one part of pounded culiar earth. Mr Kirwan likewifc analyfed the ftron- 
 
 charcoal, and to apply a ftrong heat. The charcoal tian mineral, and drew precifely the fame conclufions. 
 
 combines with the oxygen of the fulphuric acid, and It has been analyfed alfo by Mr Klaproth of Berlin, 
 
 the compound flies off in the form of carbonic acid gas. and Mr Pelletier of Paris. It confifts of carbonic acid 
 
 There remains behind fulphur combined with barjtes. combined with a peculiar earth, to which Dr Hope gave 
 
 Sulphuret of barytes is foluble in water : It is of a yel- the name oijlrcntites. This appellation we fliall adopt. 
 
 The c;irbonIc acid may be feparated by a heat of 
 
 low colour. It is capable of cryftallizing ; and then 
 affumes a yellowilh white colour J. 
 
 The phofphuret of barytes has not been examined. 
 
 No mixture of barytes and lime, nor of barytes and 
 magncfia, is fufible in the ftrongell heat which it has 
 been poffible to apply §. 
 
 140° Wedgewood, and then the ftrontites remains be- 
 
 l""dt- . ^Kir-wan't 
 
 Strontites has been found in Argylefhire in Scot--^'"""-'- 
 land, near Briftol in England, and in Pcnnfylvania f . It^^^^} 
 has been found alfo in France and in Sicily. It is of a;: r„T"''' 
 
 The affinities of barytes, according to Bergman, are white colour. It has a pungent acrid tafte. When 
 
 as follows 
 
 2'3 
 
 Sulphuric acid. 
 
 Oxalic, 
 
 Succinic, 
 
 Fluoric, 
 
 Phofphoric, 
 
 Saccholaftic, 
 
 Suberic (v) ? 
 
 Nitric, 
 
 Muriatic, 
 
 Sebacic, 
 
 Citric, 
 
 Tartarous, 
 
 Arfenic, 
 
 Fluoric, 
 
 Laftic, 
 
 Benzoic, 
 
 Acetous, 
 
 Boracic, 
 
 Sulphurous, 
 
 Nitrous, 
 
 Carbonic, 
 
 Pruffic, 
 
 Sulphur, 
 
 Phofphorus, 
 
 Water, 
 
 Fixed oils. 
 
 ties. 
 Hope, ihidt 
 PMclitr. 
 
 pounded in a mortar, the powder that rifes is ofFenfive 'ts proper 
 to the noftrils and lungs §. It is not poifonous ||. 
 
 One hundred and fixty-two parts of water, at the 
 temperature of 6c°, dilTolve nearly one part of it. The 
 folution is clear and tranfparent, and converts vegetable 
 blues to a green. Hot water diflblves it in much lar- 
 ger quantities; and as it cools the ftrontites is depofited 
 in colourlefs tranfparent cryftals. Thefe are in the form 
 of thin quadrangular plates, generally parallelograms, 
 the largeli of v. hich feldom exceeds one-fourth of an 
 inch in length. Sometimes their edges are plain, but 
 they oftener confill of two facets, meeting together and 
 forming an angle like the roof of a houfe. Thefe cry- 
 ftals generally adhere to each other in fuch a manner as 
 to form a thin plate of an inch or more in length and 
 half an inch in breadth. Sometimes they affume a cu- 
 bic form. They contain about 68 parts in 100 of wa- 
 ter. They are foluble in 51,4 parts of water, at the 
 temperature of 60". Boiling water difi"olves nearly half 
 its weight of them. When expofed to the air, they lofe 
 their water, attrad carbonic acid, and fall into pow- 
 
 When ftrontites is thrown into water, it attrads it«/y 
 with a hiffing noife, much heat is produced, and it falls 
 into powder much more rapidly than lime *. 
 
 It combines with fulphur either by fufion in a cru- 
 
 cible, or by being boiled with it in water. The ful- 
 
 phuret 
 
 (v) Suberic acid decompofes muriat and nitrat of barytes. Jamefon's Mineral, of Shetland and ^rran.
 
 CHEMISTRY. 
 
 Part r. 
 
 phurct Is of a Jark yellowifh brown colour. It is fo- 
 luble in water*. 
 
 Tiic airiLiities of ftrontitcs, 3S afcertained by Dr Hope, 
 are as follows : 
 
 Sulpluiric acid, 
 
 Oxalic, 
 
 Tartarous, 
 
 Fluoric, 
 
 Nitric, 
 
 Muriatic, 
 
 Succinic, 
 
 Pholphoric, 
 
 Acetous, 
 
 Arfenic, 
 
 Boracic, 
 
 Carbonic. 
 
 Sect. V. Of Silica. 
 
 IIS 
 TVTerhnd of 
 obtaining 
 filica. 
 
 «i6 
 
 Its I roj^tr- 
 ties. 
 
 f Kivwans 
 
 Jliiiitr.i. lo. 
 
 t Hid. 
 
 j Ibid. 
 
 1! ScUeU. 
 
 ^ Kir*wans 
 JMin. i. J4I. 
 
 There are two methods of imitating thefe cryftaU by Si ica. 
 avt. Tlie tirll metliod was difcovered by Bergman. He ' v ■■' 
 dilTolvtd iilica in fluoric acid, the only acid in which it 
 is folublo, and allowed the folution to remain undlilurb- 
 td for two years. A number of cryftals were then 
 found at the bottom of the vcffLl, moftly of irregular 
 figures, but fome of them cubes with their angles trun- 
 cated. They were hard, but not to be compared in 
 this refpeft with rock cryfta! *. * Bctgmae, 
 
 The other method was difcovered by accident. Pro."-3J- 
 feflor Seigling of Erfurt had prepared a liquor fihcum, 
 ■which was more than ufually diluted with water, and 
 contained a fuperabundance of alkali. It lay undifturb- 
 ed for eight years in a glafs veffel, the mouth of which 
 was only covered with paper. Happening to look to 
 it by accident, he obferved it to contain a number of 
 crj'ftals ; on which he fent it to Mr Trommfdorft, pro- 
 feffor of chemlftry at Erfurt, who examined it. The 
 If one part of powdered flints or fand, mixed with liquor remaining amounted to about two ounces. Its 
 three parts of potafs, be put into a crucible, and kept furface was covered by a tranfparent crull, fo ftrong 
 in a ftate of fufion for half an hour, a brittle mafs will that the veffel might be inverted without fpilling any 
 be formed almoft as tranfparent as glafs, which quickly of the liquid. At the bottom of the veffel were a num- 
 attrafts moillure from the atmofphere, and is entirely ber of cryflals, which proved on examination to be ful- 
 fohible in water. This folution k called /iqi/orji/icum, phat of potafs and carbonat of potafs (w). The cruft 
 or liquor of Jiinls. It was firft accurately defcribed by on the top confided partly of carbonat of potafs, partly 
 Glauber, a themift who lived about the middle of the of cryilallized filica. Thefe lafl. cryfl;als had aflumed the 
 j^th century. form of tetrahedial pyramids in groups ; they were per. 
 
 If an acid be poured into this liquor, a white fpongy feflly tranfparent, and fo hard that they ftruck fire 
 fubllance is precipitated, which may be purified from with fteel f . \ Nkhal- 
 
 tvery accidental mixture by walhlng it m acids, muria- Silica endures the moft violent heat without altera-yi"'' Jour/i, 
 tic acid for inftance. This fubftaiice is called _/?//Vfo«j tion. ^'7- 
 
 tarlh or plica. It was firft djftlnguifhed as a peculiar It feems incapable of combining with fulphur or phof- 
 earth by Pott in 1741^, though it had been known long phorus. 
 
 before ; and Carthcufer, Schcele, and Bergman, proved i. The e'feft of heat upon lime and filica, mixed in£(f^.^ pj- 
 
 in fucceflion that it could not, as fome chcmifts had fup- various proportions, will appear from the following ex- heat on 
 pofed, be reduced to any other earth. periments of Mr Kirwan J. mixtures of 
 
 Silica, when dried, is a foft white powder, without 
 either tafte or fmell. 
 
 Its fpecific gravity is 2,66 f. 
 
 It is Infoluble in water except when newly precipita- 
 ted from the liquor filicum, and then one part of it is 
 foluble in 1000 parts of water J. It has no effeft on 
 vegetable colours. 
 
 It is capable of abforbing about one-fourth of Tts 
 weight of water, without letting any drop from it ; 
 but on expofure to the air, the water evaporates very 
 readily J. 
 
 Silica may be formed Into a parte with a fmall quaii- 
 tity of water : this pafte has not the fmalleft duftillty, 
 and when dried forms a loofe, friable, and incoherent 
 mafs 11 . 
 
 Silica is capable of afluming a cryftalline form. Cry- . 
 
 ftals of it are found in many parts of the world. They 5. Equal part of magnefia and filica melt with great Mj^^^fj^ 
 are known by the name oi rock cryflal. When pure difficulty into a white enamel when expofed to the moft andYilica : 
 they are tranfparent and colourlefs like glafs : they af- violent heat which can be produced $. They are infu-§ Lamifur, 
 fume various forms; the moft ufual is a hexagonal fible in inferior heats in whatever proportion they are ■™"- ■'"'"■• 
 prifm, furmounted with hexagonal pyramids on one or mixed ||. J98. " 
 
 both ends, the angles of the prifm correfponding with 3. The effeft of heat on various mixtures of barytes 2,9 
 thofe of the pyramids. Their hardnefs is very great, and filica w^U appear from the following experiments of Barytesand 
 amounting to eleven. Their fpecific gravity is 2,653 f. Mr Kirwan ^. ll".^** d 
 
 proportions. |l,jJ,X;,. 
 
 17S0, p. .13. 
 
 ^ Mineral. 
 'SJ- 
 
 4 
 
 Proportions. 
 
 Heat. 
 
 iiffcd. 
 
 50 Lime 
 50 Silica 
 
 150° Wedg. 
 
 Melted into a mafs of a white 
 colour,femitranfparent at the 
 edges, and ftriking fire, tho' 
 feebly, withfteel: itwasfome- 
 what between porcelain and 
 enamel. 
 
 80 Lime 
 20 Silica 
 
 .56 
 
 A yellowifli white loofe pow- 
 der. 
 
 20 Lime 
 80 Silica 
 
 156 
 
 Not melted, formed a brittle 
 mafs. 
 
 lime and 
 filica ; 
 I ]\iir.eral. 
 i.ili. 
 
 (w) Potafs, combined with fulphuric acid and witL carbonic acid.
 
 Part I. 
 
 CHEMISTRY. 
 
 ^51 
 
 Silica. 
 
 I'roi'orticin';. 
 
 Heat. 
 
 fffcd. 
 
 80 Silica 
 20 Barytes 
 
 1550 Wcdg. 
 
 A white brittle mafs. 
 
 75 Silica 
 20 Barytes 
 
 150 
 
 A brittle hard mafs, femi- 
 tranfparcut at the edges. 
 
 66 Silica 
 33 Barytes 
 
 150 
 
 Melted into a hard fome- 
 what porous porcclaiu 
 mafs. 
 
 50 Silica 
 50 Barytes 
 
 148 
 
 A hard mafs not melted. 
 
 20 Silica 
 80 Barytes 
 
 148 
 
 The edges were melted 
 into a pale greenifh mat- 
 ter between a porcelain 
 and enamel. 
 
 25 Silica 
 75 Barytes 
 
 150 
 
 Melted into a fomewhat 
 porous porcelain mafs. 
 
 33 Silica 
 66 Bar)'tes 
 
 150 
 
 Melted into a ycllowiih 
 and partly greenifh white 
 porous porcelain. 
 
 tzo 
 And lime, 
 magnefia, 
 aiid lilica. 
 
 • Mim. 
 Berl. ibid, 
 and Jour, de 
 J'tyf- ixiv. 
 
 an 
 Affinities 
 of filica. 
 
 Method of 
 
 obtaining 
 
 alumina. 
 
 313 
 Its proper- 
 ties. 
 
 ^ Kirwan^s 
 fitter . i. 9- 
 
 4. The effeft of heat on mixtures of ftrontites and 
 filica is not known. 
 
 5. It follows from the experiments of Achard, that 
 equal parts of lime, magnefia, and iilica, may be melted 
 into a greenidi-coloured glafs, hard enough to Itrike 
 fire with fteel ; that when the magiieila exceeds either 
 of the other two, the mixture will not melt; that when 
 the filica exceeds, the mixture feldom melts, only indeed 
 with him in the following proportions ; three fiiica, two 
 lime, one magnefia, which formed a porcelain ; and that 
 when the lime exceeds, the mixture is generally fu- 
 fible*. 
 
 The affinities of filica are as follows : 
 Fluoric acid. 
 Fixed alkali. 
 
 Sect. VL Of Alum'wa. 
 
 Dissolve alum in hot water, and add to the folu- 
 tion potafs as long as any precipitate is formed. De- 
 cant off the fluid part, and wa(h the precipitate in a 
 fufficient quantity of water, and then allow it to dry. 
 The fubftance thus obtained is called alumina. Its pro- 
 perties were nril afcertained with accuracy by Mar- 
 
 Alumina thus obtained is a very white fpongy pow- 
 der, without any fmell or tafte. 
 
 Its fpecific gravity is 2,00 f. It is fcarcely fdluble in 
 water, but may be diffufed through it with great faci- 
 lity. 
 
 SuppL. Vol. I. Part I. 
 
 With a fmall quantity of water it forms a very tough Alnmina. 
 duiilile paile, and does not readily mix with more. » 
 
 In its ufual Hate of drynefs it is capable of abforbing 
 2\ times its weight of water, without fuffcring any to 
 drop out. It retains this water more obfliuatcly tlian 
 any of the earths hitherto defcribed. In a freezing cold 
 It contracts more, and parts with more of its water than 
 any other earth ; a circumllaiice which is of fome im- 
 portance in agriculture *. * llij. 
 
 Alumina has never yet been obtained in a cryftalli- 
 zed form. It has no e(fe(3t whatever on ve£;etable co- 
 lours. 
 
 The mod intenfe heat does not fufe it, but it has the 
 Angular property of diminillung in bulk in proportion 
 to the intenfity of the fire to which it is expofed. It 
 becomes at the fame time exceedingly hard: Mr Lavoi- 
 fier rendered it capable of cutting glafs ; and Mr Boyle 
 had long before done the fame thing f. f Sbaw't 
 
 Wedgewood took advantage of this property of alu- ^o;''. '"• 
 mina, and by mean.s of it conllrufted an inllrument for''^"' 
 meafuring high degrees of heat. It confills of pieces ^^'^.,l„J. 
 of clay of a determinate fi/.e, and an apparatus for mea- wood's 
 furing their tulk with accuracy : One of thefe pieces istfie'nionie- 
 put into the fire, and the temperature is eftimated by"*^' 
 the contraftion of the piece. For a more complete de- 
 fcription of this important inftrument, we refer to the 
 article Thermometer in the Encycl. 
 
 Alumina is hardly lufceptible of combining with ful- 
 phur or phofphorus ; but from the experiments of La 
 Grange, it appears to have an affinity for carbon \. t Nichol- 
 
 I. The effect of heat on various mixtures of lime and ^f"' J""'- 
 alumina will appear from the following table (J ; li Kir 
 
 56. 
 
 Effca of 
 
 eat on 
 mixtures of 
 lime and 
 alumina; 
 
 Propoitions. 
 
 Htat. 
 
 Effc-a. 
 
 75 Lime 
 25 Alumina 
 
 150'= Wedg. 
 
 Not melted. 
 
 66 Lime 
 33 Alumina 
 
 33 Lime 
 66 Alumina 
 
 150 
 
 Remained a powder. 
 
 {-) 
 
 Melted. 
 
 25 Lime 
 75 Alumina 
 
 (x) 
 
 Melted. 
 
 20 Lime 
 80 Alumina 
 
 (X) 
 
 Melted. 
 
 226 
 
 2. Magnefia and alumina have no aftion whatever on Magnefia 
 each other, aven when expoled to a heat of 150" Wedge- !"id aluini- 
 
 wood II . _ "^^jj.^j 
 
 3. The effeft of heat on different mixtures of barytes ' ' ' ^''' 
 and alumina will appear from the following experiments Barytes and 
 of Mr Kirwarn ^. alumina ; 
 
 Kk Proportions.^-^*'* 
 
 (x) Thefe three experiments were made by Ehrman : The heat was produced by direfting a flrcam of oxygen 
 gas on burning charcoal, and is the mod intenfe which it has been hitherto pofFible to produce.
 
 2j8 
 
 Alumina. 
 
 CHEMISTRY. 
 
 Proportions. 
 
 Heat. 
 
 Effs.l. 
 
 80 Alumina 
 20 Barytes 
 
 i50°Wedg. 
 
 Scarcely hardened. 
 
 75 Alumina 
 25 Barytes 
 
 156 
 
 No fign of fufion, a 
 ioofe powder. 
 
 66 Alumina 
 33 Barytes 
 
 152 
 
 As the former. 
 
 50 Alumina 
 50 Barytes 
 
 150 
 
 As the former. 
 
 20 Alumina 
 80 Bai7tes 
 
 148 
 
 Somewhat harder, but 
 no fign of fufion. 
 
 25 Alumina 
 75 Barytes 
 
 150 
 
 Harder, but no fign 
 of fufion. 
 
 Part I. 
 
 Alumina. 
 
 4, Nothing is known concerning the efFeft of heat 
 323 on mixtures of ftrontites and alumina. 
 Alumina 5. Equal parts of alunilna and filica harden in the 
 
 andfilica; temperature of 160° Wedgewood, but do not fufe *. 
 * ^'"""g' Achard found them infufible in all proportions in a heat 
 '"' '' ^ ' probably little inferior to 150" Wedgewood. Mi.\tures 
 of thefe two earths in various proportions form clays, 
 but thefe are feldom uncontaminated with fome other 
 ingredients. 
 Limefmag- (>• From the experiments of Achard, it appears that 
 nefia/and no mixture of lime, magnefia, and alumina, in which the 
 alumina ; \[^^ predominates, is vitrifiable, except they be nearly 
 in the proportions of three lime, two magnefia, one alu- 
 mina ; that no mixture in which magnefia predominates 
 will melt in a heat below 166' ; that mixtures In which 
 the alumina exceeds are generally fufible, as will appear 
 ^ Ibid. i. 7a. from the following table f . 
 
 3 Alumina 
 2 Lime 
 I Magnefia 
 
 A porcelain. 
 
 3 Alumina 
 
 1 Lime 
 
 2 Magnefia 
 
 A porcelain. 
 
 3 Alumina 
 I Lime 
 3 Magnefia 
 
 Porous porcelain. 
 
 3 Alumina 
 
 2 Lime 
 
 3 Magnefia 
 
 Porous porcelain. 
 
 3 Alumina 
 2 Lime 
 2 Magnefia 
 
 Porcelain. 
 
 */iiV. j. 73. 
 
 431 
 
 Magnefia, 
 filica, and 
 alumiua ; 
 
 f Ibid. i. 73. 
 
 131 
 And lime, 
 magn fia, 
 lilica, and 
 alumina. 
 
 ^33 
 Affinities o£ 
 alumina. 
 
 7. From the fame experiments, and thofe of Kirwan, 
 
 430 
 ^.Tn'd'^al'u-we'learn, that in mixtures of lime, 
 mina; when the lime .eaCceeds, the mixture is generaUy iulible 
 
 filica, and alumina, 
 
 cither into a glafs or a porcelain, according to the pro- 
 portions. The only infufible proportions were, 
 2 3 Lime 
 
 1 I Silica 
 
 2 2 Alumina. 
 That If the filica exceeds, the mixture Is frequently fu- 
 fible into an enamel or porcelain, and perhaps a glafs ; 
 and that when the alumina exceeds, a porcelain may 
 often be attained, but not a glafs *. 
 
 8. As to the mixtures of magnefia, filica, and alumina, 
 when the magnefia exceeds, no fufion takes place at 
 150''. When the filica exceeds, a porcelain may often 
 be attained ; and three parts filica, two magnefia, and 
 one alumina, formed a glafs. When the alumina exceeds, 
 nothing more than a porcelain can be produced f. 
 
 9. Achard found that equal parts of lime, magnefia, 
 filica, and alumina, melted into a glafs. They fiifed al- 
 fo in various other proportions, efpecially when the fili- 
 ca predominated. 
 
 The affinities of alumina as as follows : 
 Sulphuric acid, 
 Nitric, 
 ' Muriatic, 
 Oxalic, 
 Arfenic, 
 Fluoric, 
 Sebacic, 
 Tartarous, 
 Succinic, 
 Saccholatlic, 
 Citric, 
 Phofphoric, 
 Formic, 
 Ladllc, 
 Benzoic, 
 Acetous, 
 Boracic, 
 Sulphurous, 
 Nitrous, 
 Carbonic, 
 Pruffic. 
 
 Sect. VIL Of Jargoma. 
 
 Among the precious ftones which come from the dij-^q'^™ 
 Ifland of Ceylon, there is one called jargon, which is uf jargoiua* 
 poflelfed of the following properties. 
 
 Its colour is various, grey, greenilh white, yellowlfh, 
 reddlfh brown, and violet It is often cryftalllzed, ei- 
 ther in right angular quadrangular prifms furmounted 
 with pyramids, or ottahedrals confifling of double qua- 
 drangular pyramids. It has generally a good deal of 
 luftre, at lead internally. It is moftly femitranfparent. 
 Its hardnefs is from 10 to 16 : Its fpecific gravity from 
 4,416 to 4,7 %. X Ibid. i. 
 
 It lofes fcarcely any of its weight in a melting heat ;333- 
 for Klaproth found that 300 grains, after remaining in 
 it for an hour and a half, were only one-fourth of a grain 
 lighter than at firft J. Neither was it attacked either { Jour.dt 
 by muriatic or fulphuric acid, even when aflifted by heat, ^hf- 3** 
 At laft, by calcining it with a large quantity of foda, '^ ^"^ 
 he diflblved it in muriatic acid, and found that 100 parts 
 of it contained 31,5 of filica, five of a mixture of nick- 
 el, 
 
 434
 
 Part T. 
 
 Glucina. 
 
 J. p. 14. 
 
 236 
 Difcovery 
 
 of giuciiu, 
 
 C H H M 
 
 cl and iron, nnd 68 of an cartli potTcffLd of peculiur pro- 
 peities. Tills earth lias been czlhdjtirgonia. 
 
 Jargonia has a ftrong refcmblancc to ahimlna. It is 
 of a white colour. Its fpeciiic gravity probably exceeds 
 4,000. 
 
 It differs from alumina in the compounds which it 
 
 forms with other bodies, in being inioluble in a boiling 
 
 lolntion of pure potais or foda, imd in being infulible by 
 
 heat when mi.xcd with tliele fubftances in a Itatc of dry- 
 
 » A'lVmin'incfs*. 
 
 No more of its properties are yet known. 
 
 S£CT. VIII. Of Glucina. 
 
 In the beryl was difcovered, fome time ago by Vau- 
 quclin, a new earth, to which he gave the name of g/u- 
 ciiia. To obtain it pure, the beryl, reduced to powder, 
 is to be fuled with thrice its weight of potafs. The 
 mafs is to be diluted with water, diffolved in muriatic 
 acid, and the folution evaporated to drynefs. The re- 
 fiduiim is to be mixed with a large quantity of water, 
 and the whole thrown on a fdter. The fdica, which 
 conftitutes more than half the weight of the (lone, re- 
 mains behind ; while the glucina and the other earths, 
 combined with muriatic acid, remain in folution. They 
 are to be precipitated by means of carbonat ct potafs ; 
 the precipitate is to be wafhed, and then diffolved in ful- 
 phuric acid. When the folution, after potafs has been 
 added to it, has been evaporated to the proper con- 
 fillency, alum cryftals are gradually formed. When as 
 many of thefe have been obtained as poffible, carbonat 
 of ammonia in excefs is to be poured into the liquid, 
 which is firft to be filtered and then boiled for fome 
 time, when a white powder gradually appears. This 
 powder is glucina. 
 
 It is a foft light powder, without either tafle or 
 fmell, but has the property of adhering ilrongly to the 
 tongue. It has no aftion on vegetable colours, is alto- 
 gether infufible by heat, and neither hardens nor con- 
 trails in its dimenfions. It is infoluble in water, but 
 forms with a fmall quantity of that liquid a palle to a 
 certain degree duftile. It does not combine with oxy- 
 gen, nor with any of the fimple combulUbles ; but ful- 
 phurated hydrogen dilTolves it, and forms with it a hy- 
 drolnlphuret, iimilar in its properties to other hydro- 
 fulphurets. Glucina is foluble in the liquid fixed alka- 
 lies ; infoluble in ammonia, but foluble in carbonat of 
 ammonia. It combines with all the acids, and forms 
 with them fwect tafted falts ; and hence its name, from 
 yhvt.ofyf'weet. Its other properties have not been exa- 
 mined. 
 
 Sect. IX. Of Tttria and Jgujllna. 
 
 Difcovery Some time before 1788 was difcovered, in the quar- 
 and ]iro].er ry of Ytterby in Sweden, a peculiar mineral, called 
 ties uf yt- from Profeffor Gadolin, who lirfl analyfed it, gadolinite. 
 ""• Its colour is black, and its frafture like that of glafa. 
 
 It is magnetic, and foft enough to be fcratched by a 
 knife, and fometimes even by the nail. In this mine- 
 ral a new earth has been difcovered by various chemifts, 
 who have agreed to give it the name oi yttria. When 
 feparated from the other fubflances with which it is 
 
 I S T R Y. 
 
 259 
 
 5J7 
 \Xi 1 lope 
 ties- 
 
 combined, viz. the oKiden of iron- and mangatiefe, a Y una and 
 little lime, and a conliderable quantity of lilica, it has *^" ''" ,, 
 the appearance of a line while powder, and has neither 
 tafle nor fmell. It is not melted by the application of 
 heat, has no aftion on vegetable blues, and is not fo- 
 luble in water. It is likiwlie inlolnhle In pure alka- 
 lies ; but it dlffolves readily In carbonat of ainmonia. It 
 combines wllh acids, and forms with them falts, which 
 have a fweet talle, and at the fame time a certain de- 
 gree of aullcrity. j.p 
 
 Trommfdorf has la'ily difcovered in the Saxon icrj'/Uifcovcry 
 a new earth, to which he has ^Iven the name of /Igujli-ol i^u^'iai. 
 tia, becaufe the falts which il forms have little or no 
 tafle. As Trommfdorf's experiments have not hither- 
 to been repeated, the exillence of this earth mufl con- 
 tinue doubtful till the conclufious of the difcoverer be 
 confirmed by other philofophers. 
 
 These are all the fimple earths that have yet been Rcmarlt ton 
 difcovered; and the firfl four of them have a great ma- the eartlis. 
 ny common properties. They tinge vegetable blues 
 green, they have a ftrong affinity for carbonic acid, and 
 combine readily with all acids. They have fometimes 
 been called alkaline earths. 
 
 None of the earths have been hitherto decompound- 
 ed, nor has the fmalleft proof ever been brought that 
 they are compounds. We mufl therefore, in the ])re- 
 fent ftate of chemiftry, confider them as fimple bodies. 
 Many attempts, indeed, have been made to fliew that 
 there was but one earth in nature, and that all others 
 were derived from it. The earth generally made choice 
 of as the fimpleft was filica(Y). But none of thefe at- 
 tempts, notwithftanding the ingenuity of feveral of the 
 authors, has been attended with the fmalleft fhadow of 
 fuccefs. 
 
 We have mentioned formerly, that it was almofl the 
 univerfal opinion of chemifts that metals were compofed 
 of fome of the earths united to phloglfton ; but of late 
 an attempt has been made to prove that all the earths 
 are metallic oxides, and that they can aftually be redu- 
 ced to the ftate of metals. 
 
 Baron had long ago fufpefted that alumina had fome- 
 what of a metallic nature ; and Bergman had been in- 
 duced, by its great weight and feveral other appearan- 
 ces, to conjefture that barytes was a metallic oxide : 
 But the firft chemlft who ventured to hint that all 
 earths might be metallic oxides was Mr Lavoilier *. * Chemijry, 
 About the year 1790, foon after the publication of MrE;Y''|j ''^' 
 Lavolfier's book, Mr Tondi and Profeffor Ruprecht, 
 both of Schemnitz, announced, thit they had obtained 
 from barytes, by the application of a ftrong heat, a me- 
 tal of the colour of iron, and attiafted by the magnet, 
 which they called borbonium ; from magnefia another, 
 which they called auflrum ; a third from lime, alfo 
 called auflrum ; and a fourth from alumina, which they 
 denominated apulum. Their method of proceeding was 
 to apply a violent heat to the earths, which were fur* 
 rounded with charcoal in a Heffian crucible, and co- 
 vered with calcined bones in powder. 
 
 But their experiments were foon after repeated by 
 
 Klaproth, Savorefi, and Tihaulki ; and thefe accurate 
 
 K k 2 chemifts 
 
 (y) Mr Sage, however, pitched upon lime.
 
 26o C H E M 
 
 Caloric, chcmifis foon proved, that the pretended metals were all 
 '"""V—— oi t\xm J>/jcj] r.ure/s of ira:. The iron, by tlie violence 
 of the heat, had been e,\tr.ifted from the crucible, and 
 the phofphorus from the bones. The earths therefore 
 nmft il.U continue a dillinft clafs of bodies: and, as Kla- 
 proth has obferved, their properties are fo exceedingly 
 different from thofe of metallic oxides, that the fuppo- 
 fition of their being compofed of the fame ingredients is 
 coiitraiy to every faft, and to every analogy with which 
 we are acquainted. 
 
 Cn.4P. V. 0/C.\LORic. 
 
 Nothing is more familiar to \is than henl ; to at- 
 tempt to define it therefore would be unneceflary . When 
 we fay that n ferjon fteh heat, that ajlone is hot, the ex- 
 prefTions caufe no difficulty ; every one underlf ands them 
 perfcdfly : yet in each of theie propofitions the word 
 heat has a dithnft meaning. In the one, it fignifies the 
 J.-nfaiion of heat ; in the other, the caiife'oi that fenfation, 
 This ambiguity, though of little confcquence in common 
 lii'e, leads unavoidably in philofophical difcuffions to con- 
 fiifion and perplexity. It was to prevent this that the 
 French chemifts made choice of the word caloric to fig- 
 uify the caufe of heat. When I put my hand on a hot 
 itone, I experience a certain fenfation, which I call the 
 241 fenfation of heat ; the caufe of this fenfation is caloric. 
 Whether Concerning the nature of caloric, there are two opi- 
 
 ral' nc he a nJons v.hich have divided philofophers ever fince they 
 ^feibftance. t„f„ej their attention to the fubjeft. Some fuppofe 
 that caloric, like gravity, is merely a property of mat- 
 ter, and that it confifts, fome how or other, in a pecu- 
 liar vibration of its particles ; others, on the contrary, 
 think that it is a diftinft fubftance. Each of thefe opi- 
 nions has been fupported by the greateft philofophers ; 
 and the obfcurity of the fubjeft is fuch, that both fides 
 have been able to produce exceedingly plaufible and for- 
 cible arguments. The recent difcoveries, however, in 
 
 Part I. 
 
 Caloric. 
 
 1 S T R Y. 
 
 this branch of chtmiftry, have rendered the latter opi- 
 nion much more probable than the former. Indeed we 
 do not fee how it is polIibL' to account for many of the 
 phenomena of nature, unlefs caloric be confidered as a 
 fubftance, as we trull fliall appear from the invettiga- 
 tion into which we are about to enter. We mean, then, 
 with the generality of modern chemifts, to take it for 
 granted that caloric is a fubftance, without pretending 
 to be able to demonftrate the truth of our opinion, but 
 nierely becaufe we conlider it as infinitely more plau- 
 fible than the other. If the receiver of an air-pump, 
 while it contains a thermometer, be fuddenly exhaufttJ 
 of air, the thermometer finks feveral degrees, and then 
 gradually rlfes again to its former height. Now if heat 
 be owing to vibration, how comes it that the fmall quan- 
 tity of matter remaining in the receiver is firft infufB- 
 cient, and afterwards fufficient to maintain the tempe- 
 rature ? Is it not more probable that part of the calo- 
 ric was carried off with the air, and that it gradually 
 returned through tlie glafs, which it is capable of per- 
 vading, though with difficulty *. When air is let into « See Pi:. 
 an exhaufted receiver, the thermometer, as Lambert firft trtfur t: 
 obferved, rifes feveral degrees. Is not this owing to an '^"'< '■"• '' 
 additional quantity of caloric introduced by the air ? 
 The thermometer then finks flowly. Is not this becaufe 
 the fuperabundant caloric gradually pervades the glafs 
 and flies off? Taking it for granted then that caloric is 
 a fubftance, we proceed to examine its propertis. 241 
 
 I. When bodies become hot, or, which is the fame Caloric m» 
 thing, when caloric enters into them, they expand in P?"ds bo- 
 every direftion ; and this expanfion is proportional to the 
 accumulation of caloric. The firft: and moil obvious 
 property of caloric then is the power of expanding bo- 
 dies. It does not, however, expand all fubftances equal- 
 ly, and we are ftill ignorant of the law which it follows. 
 All that can be done therefore is to coUeft fails till 
 this law be difcovered. A number of thefe may be feen- 
 in the following Table : 
 
 i 
 
 i 
 
 * BligJcn. 
 •^ [^eijuton. 
 
 Table of the Expanfion ef various Bodies at different Temperatures . 
 
 Tem-f e- 
 racure. 
 
 Water ». 
 
 Mercury. 
 
 Linfced 
 
 Ollf. 
 
 Alcohol *. 
 
 Tempe- 
 rature. 
 
 100° 
 
 Water *. 
 
 Mercury. 
 
 l.infeed 
 
 oilf. 
 
 Alcohol *. 
 
 30° 
 
 ^_ 
 
 
 
 
 
 I 00000 
 
 100908 
 
 100711,8 
 
 — 
 
 104162 
 
 .S2 
 
 — 
 
 1 00000,0 
 
 I 00000 
 
 — 
 
 105 
 
 — 
 
 100762,7 
 
 
 
 35 
 
 100000 
 
 100030,0 
 
 — 
 
 100267 
 
 no 
 
 — 
 
 100813,6 
 
 
 
 40 
 
 99997 
 
 100081,0 
 
 — 
 
 100539 
 
 120 
 
 101404 
 
 100915,4 
 
 
 
 45 
 
 100005 
 
 100131,9 
 
 — 
 
 IO1818 
 
 130 
 
 — 
 
 101017,2 
 
 
 
 50 
 
 100023 
 
 100182,8 
 
 — 
 
 IOIIO5 
 
 140 
 
 — 
 
 101119,0 
 
 
 
 S5 
 
 100053 
 
 100253,7 
 
 — 
 
 IOI40I 
 
 150 
 
 102017 
 
 101220,8 
 
 
 
 60 
 
 100091 
 
 100304,6 
 
 — 
 
 101688 
 
 160 
 
 — 
 
 101322,6 
 
 
 
 65 
 
 IOOI4I 
 
 '00355,5 
 
 — 
 
 101984 
 
 167 
 
 102753 
 
 — 
 
 
 
 70 
 
 100197 
 
 100406,4 
 
 — 
 
 IO2281 
 
 170 
 
 — 
 
 101424,4 
 
 
 
 75 
 
 100261 
 
 100457,3 
 
 — 
 
 102583 
 
 1 80 
 
 — 
 
 101526,2 
 
 
 
 80 
 
 100332 
 
 100508,2 
 
 — 
 
 102890 
 
 19D 
 
 103617 
 
 101628,0 
 
 
 
 85 
 
 100411 
 
 100559,1 
 
 — 
 
 103202 
 
 200 
 
 — 
 
 101729,8 
 
 
 
 90 
 
 100694 
 
 100610,0 
 
 — 
 
 103517 
 103840 
 
 212 
 
 104577 
 
 101835,0 
 
 107250 
 
 
 95 
 
 100790 
 
 100660,9 
 
 102560 
 
 408 
 
 — 
 
 ■"" 
 
 II5160 
 
 
 ■\ Newt 9a f 
 
 Table
 
 CHEMISTRY. 
 
 Tabls of the Expanfton ofvarious Bodies at dijfsrent Temperatures eonliiiueJ. 
 
 Tempf- 
 
 Sulph. 
 
 Nitric 
 
 Glafs f . 
 
 Air 
 
 Oxyxen 
 
 Azotic 
 
 Hydrogen 
 
 Nitrous 
 
 Cirb. acid 
 
 Animonia- 
 
 rature 
 
 acid ». 
 
 acid*. 
 
 
 gafj. 
 
 gas 5. 
 
 gas 5. 
 
 gas }. 
 
 ga8§. 
 
 calgas§. 
 
 32° 
 
 __» 
 
 
 
 lOOCOO 
 
 lOCOOO 
 
 I 00000 
 
 1 00000 
 
 lOOOCO 
 
 I 00000 
 
 100000 
 
 1 00000 
 
 40 
 
 — 
 
 — 
 
 — 
 
 101790 
 
 
 
 
 
 
 
 45 
 
 — 
 
 loooo; 
 
 — 
 
 — 
 
 
 
 
 
 
 
 J-^ 
 
 100149 
 
 100149 
 
 — 
 
 104140 
 
 
 
 
 
 
 
 5? 
 
 10026:? 
 
 101C74 
 
 100006 
 
 — 
 
 
 
 
 
 
 
 60 
 
 100382 
 
 10J389 
 
 ___ 
 
 106560 
 
 
 
 
 
 
 
 65 
 
 ioo6n 
 
 101767 
 
 — 
 
 — 
 
 
 
 
 
 
 
 70 
 
 10075 1 
 
 102096 
 
 — 
 
 108950 
 
 
 
 
 
 
 
 75 
 
 — 
 
 — 
 
 ICOOI4 
 
 — 
 
 
 
 
 
 
 
 77 
 
 — 
 
 — 
 
 — 
 
 — 
 
 104520 
 
 103400 
 
 108390 
 
 106520 
 
 IIIO5O 
 
 1279IO 
 
 80 
 
 — 
 
 — 
 
 — 
 
 III3CO 
 
 
 
 
 
 
 
 90 
 
 — 
 
 — 
 
 — 
 
 H359O 
 
 
 
 
 
 
 
 100 
 
 — 
 
 — 
 
 100023 
 
 — 
 
 
 
 
 
 
 
 no 
 
 _ 
 
 
 — 
 
 II7580 
 
 
 
 
 
 
 
 122 
 
 — 
 
 
 100033 
 
 — 
 
 124830 
 
 121860 
 
 122830 
 
 II7630 
 
 130660 
 
 184870 
 
 130 
 
 — 
 
 — 
 
 — 
 
 121870 
 
 
 
 
 
 
 
 150 
 
 — 
 
 — 
 
 100044 
 
 126030 
 
 
 
 
 
 
 
 .67 
 
 — 
 
 
 100056 
 
 — 
 
 I9OI80 
 
 176640 
 
 137420* 
 
 144370 
 
 173850 
 
 358780 
 
 170 
 
 — 
 
 
 — 
 
 130090 
 
 
 
 
 
 
 
 190 
 
 — 
 
 — 
 
 100069 
 
 133970 
 
 
 
 
 
 
 
 2;2 
 
 ^"~ 
 
 
 100083 
 
 134890 
 
 547670^ 
 
 694120 
 
 139120$ 
 
 160290J 
 
 200940J 
 
 680090I 
 (A) 
 
 Table of the Expanjion of Metals from 320 to 2i2''f . 
 
 Tempera- 
 ture. 
 
 Antimony. 
 
 Steel. 
 
 Iron. 
 
 Caft Iron. 
 
 Bifmuth. 
 
 Copper. 
 
 Caft 
 Brafs. 
 
 Brafs M^ire. 
 
 32° 
 212 
 •White! 
 heat 
 
 1 20000 
 I 20 I 30 
 
 1 20000 
 120147 
 
 123428* 
 
 120000 
 120151 
 
 121500* 
 
 120000 
 122571* 
 
 1 20000 
 120167 
 
 120000 
 120204 
 
 120000 
 120225 
 
 IJOOOO 
 120232 
 
 1 
 
 
 Tin. 
 
 , J ,,. Hammered 
 Lead. Z.nc. ^inc. 
 
 Zinc S 
 Tin I 
 
 Lead i 
 Tin I 
 
 Brafs ^ 
 Ziuc I 
 
 Pewter. 
 
 Copper 3 
 'I in ( B ) I 
 
 3^^ 
 212 
 
 120000 
 120298 
 
 120000 
 12034+ 
 
 I2COO0 120000 
 
 120355 120373 
 
 120000 
 120323 
 
 1 20000 
 
 ii030i 
 
 I 20000 
 120247 
 
 120000 
 120274 
 
 I 20000 
 1 202 1 8 
 
 261 
 
 Caloric. 
 
 § Du ftr- 
 
 Mtibod. art- 
 Air. 
 
 Phil. Trany 
 xlviii. 612. 
 
 • Rim 
 
 Froi: 
 
 (a) This mark % implies that, owing to fome inaccuracy in making the experiments, the numbers to which it 
 is attached are not to be depended on. 
 
 (b) The metal whole expanfion is here given was an alloy compofed of three parts of copper and -)ne of tin, . 
 The figures in fome of the preceding columns are to be underftood in the fame manner. Thus in the laft column > 
 but two, the metal coiififted of two parts of brafs alloyed with one of zinc. .
 
 • £%</« 
 
 362 C H E M I 
 
 C'jloric. From this table, it appears that the gafes are more 
 
 "—"^ 'expanded by caloric than fluids, and fluids more than 
 
 Esc/ption ^°^^^^ ' '"^^ '^''^'^ ^^^^ cxpanlion of all bodies hitherto ex- 
 amined, mercury alone excepted, goes on in an increa- 
 fing feries. To the expanding power of caloric there 
 is one lingular exception : From 30'' to 40° Fahrenheit, 
 •water, inllead of being expanded, iuffers a remarkable 
 contraction, as is evident from the following table of 
 its bulk for every rlcgree between 31" and 40". 
 
 Bulk. 
 30''- - - 100074 
 
 31 - - - 100070 
 
 32 - • - 100066 
 ^3 - - - 100063 
 
 ■ 34 " " " iooc6o 
 
 35 . - - 100058 
 
 36 • - - ioooj6 
 
 37 - - - 10005J 
 
 38 - - - 100054 
 
 39 - - - 100054 
 
 40 - - - 100C54 *. 
 From 400 it expands like other fubftances on being 
 
 J heated (b). 
 
 Thermo- The expanfion of bodies by caloric has furnilhed us 
 
 meter. with an inftrument for meafuring the various degrees of 
 it in different fubftances, we mean the thermometer ; 
 and as mercury is the oi:ly fluid which expands equably, 
 it is obvioufly the only proper one for thermometers. 
 The thermometer uniformly ufed in this article is that 
 of Fahrenheit, except when fome other is particularly 
 ^ mentioned. 
 
 No bo'dy 2. By means of the thermometer, we learn that there 
 
 without is no body which does not contain coloric, becaufe there 
 caloric. jj none fo cold that it cannot be made colder: and cool- 
 In-r a body is nothing elfe but abllracling a part of the 
 ^ f^ caloric which it contains. 
 J^quiliSri- 3. Caloric cannot be confined in any body while 
 um ofta- thofc in its neighbourhood are colder, but continues to 
 lone. y^f[^ QUI- tj)] every thing is reduced to the fame tempe- 
 
 rature. This does not proceed from the attraftion of 
 the colder bodies, but from the tendency ot caloric to 
 exill everywhere in an equal degree of tenfion : For 
 when hot bodies are placed in the exhaufted receiver of 
 tSorfcF«,an air-pump, as we learn from Mr Pidletf, or in the 
 chap. ■»!. Torricellian vacuum, as Count Rumford has Ihewn us|, 
 t Pill. jj^^ caloric leaves them in the fame manner, tho' more 
 "^^ii flowly, and they are equally reduced to the temperature 
 Part i. of tbc furrounding bodies. This property has been 
 called the ejuiliirium of caloric. The only way there- 
 fore to confine or accumulate this fubftance in a body, 
 is to furround it with bodies which are hotter than itfelf. 
 4. The equilibrium of caloric feems evidently to prove 
 
 S T II Y. 
 
 Part. T. 
 
 that its particles repel each other. This repulfiun will Calniic. 
 caufe them when accumulated in any place to fly off in > -' 
 every direflion, and to continue to ftparate till they are.j..'''7 . 
 oppofed by caloric in other bodies of the fame relativedes of calo. 
 denfity with themfelves, ivhich, by repelling them in itsnc repel 
 turn, compels them to continue where they are. The'-'*''' other. 
 caloric in bodies therefore is in wliat has l)een called by 
 Mr Pidet a ftate of tenfion (c). Its particles are actu- 
 ated by a force which would make them feparate to an 
 indefinite dillance, were they not confined by the op- 
 pofite force of the caloric which lurrounds thci.'. The 
 equililrlam therefore depends on the balancing of two op- 
 pofite forces ; the repulfion between the particles of ca- 
 loric in the body, which tends to diminilh the tenipera- 
 ture ; and the repuliion between the caloric of the body 
 and the furrounding caloric, which tends to raife the 
 temperature. When the firll force is greater than the 
 fecond, as is the cafe when the temperature of a body is 
 higher than that of the furrounding bodies, the caloric 
 flies off, and the body becomes colder. When the lall 
 force is ftronger than the firlt, as is the cafe when a 
 body is colder than thofe which are around it, the par- 
 ticles of its caloric are obliged to approach nearer each 
 other, new caloric enters to occupy the fpace which 
 they had left, and the body becomes hotter. When 
 the two forces are equal, the bodies are faid to be of 
 the fame temperature, and no change takes place *. *See Pic- 
 
 It is the aftion of thefe oppofite forces which makes'''/"''/'' 
 the thermometer a mcafure of temperature. When ap- ''''"''"• '" 
 plied to any body, it continues to rife or fall till the ca- 
 loric in it and in the body to which it is applied are of 
 the fame tenfion, and then it remains ftationary. The 
 thermometer therefore merely indicates that the tempe- 
 rature of the body to which it is applied is equal to its 
 own. It is obvious that, in order to obtain the real 
 temperature of bodies, the thermometer fliould be fo 
 fmall that the quantity of caloric, which enters or leaves 
 it, may not materially affcft the refult. 
 
 This property of caloric feems to be the caufe of the 
 elafticity of the gafes, in which, as we fliall fliew after- 
 wards, it exifts in great quantities. Perhaps it is the 
 caufe of elafticitv in general ; for we liave no demon- 
 ftrative evidence that the particles of elaftic bodies repel 
 each other (d), and we are certain that all of them 
 contain caloric. Peihaps alfo it is owing to this repul- 
 five property of caloric that the particles of no body 
 aftually touch each other ; for the lefs caloric we leave 
 in a body, the nearer its particles approach to one ano- 
 ther. The expanfion of bodies by caloric feems alfo to 
 depend on the fame property. The particles of caloric 
 uniting with thofe of the body, endeavour to drag them 
 along when they recede from each other. 1 he expan- 
 fion 
 
 (b) There was a curious faft concerning dilatation obferved by Mr de Luc. A brafs rod which he ufed as a 
 thermometer became in fummer hahitually longer ; that is to fay, that after being for fome time lengthened by 
 heat, it did not contrad by the application of cold to its old length, but continued fomewhat longer. In winter 
 the contrary phenomenon took place. After being contrafted for fome time by cold, it did not return to its old 
 length on the application of heat, but kept fomewhat fltorter. A leaden rod fliewed tliefe effects in a greater 
 degree. Glafs has not this quality. De Luc fufpefts that this property is inverfely as the elafticity of bodies. 
 Glafs is perfeftly elaftic, and lead is lefs elaftic than brafs. — Journ. de Phyf. xviii. 369. 
 
 (c) The phrafe was firft ufed by Mr Volta. 
 
 (d) We acknowledge that feveral philofophers of the firft rank, iEpinus for inftance, and Bofcovich, have 
 fuppofed that the particles of all bodies both attradl and repel each other : but we cannot help thinking it rather 
 improbable (if it be pofTible) that two fuch oppofite properties fhould exift together.
 
 14S 
 Bodies be- 
 come li<;hc- 
 
 Part I. 
 
 Caloric, fion of bodies therefore ought to be inverfely as their 
 <| ' ' cohelion, ami diredlly as the tenfion of the caloric which 
 they contain. This property of caloric feems likewile to 
 afford an explanation of a very curious fact, which was 
 firil, we believe, mentioned by De Luc in his Treatile 
 on the Modifications of the Atmofphere, and afterwards 
 afccrtaincd by Dr George Fordyce, that bodies become 
 . abfolutely ligiitcr by bcinir heated. He took a ghfs 
 healed globe three inches in diiii'.eter, with a fliort neck, and 
 weighing 451 grains; poured into it 1700 grains of 
 water from the New river, London, an<l then icaled it 
 hermetically. The whole weighed 2150-1-4- grains at 
 the temperature of 32°. It w.is put for twenty mi- 
 nutes into a freezing mixture of fnow and fait till fome 
 of it was frozen ; it was then, after being wiped fnll 
 with a dry linen cloth, next with clean waflied dry lea- 
 ther, immediately weighed, and found to be yV'' "^ "^ 
 grain heavier than before. This was repeated cxaitly 
 in the fame manner five different times. At each, more 
 of the water was frozen and more weight gained. When 
 the whole water was frozen, it was rV*-''^ °^ "^ grain 
 heavier than it had been when fluid. A thermometer 
 applied to the globe ilood at 10". When allowed to 
 remain till the thermometer rofe to 32", it wiigheJ 
 ■j^tbs of a grain more than it did at the fame tempera- 
 ture when fluid. We Ihall (hew afterwards that ice 
 contains lefs caloric than water of the fame temperature 
 with it. The balance ufed was nice enough to mark 
 •rj^Vo part of a grain *. Morveau, too, found, much 
 about the fame time, that water put into veffels herme- 
 tically fealed, weighed more when frozen than when 
 ^ Jsiirn. dt fluid f: and Mr Chauflier found, that two pounds of 
 Ort '' ^' ^^''p'l"''''-' 3'^'d were three grains heavier when frozen than 
 \ Jmrn.d: '^^^^'^ they had recovered their fluidity \. Now, if the 
 Savans, particles of caloric repel each other, bodies which con- 
 17S5. tain it in great quantities muft be fomewhat repelled by 
 
 P' •*93- each other. The more replete therefore that any body 
 And v^by. '^ "'"^ caloric, the more it will be repelled by the earth, 
 which always contains a great quantity ; and this re- 
 puhion mull in fome degree counteraft its gravitation. 
 This explanation was hrll fuggefted, we believe, by 
 150 Dr Black. 
 Caloric The fame property explains another curious fa£l dif- 
 
 ^°^.^j''"^<"'* covered by Mr Piftct of Geneva, that caloric moves 
 war.s than"^"*^^ readily vertically upwards than downwards. He 
 downwards took a tube of tinplate, two inches in diameter and 4.4 
 in length, and enclofed in it a bar of copper four lines 
 in diameter and 3^ inches in length, which was placed 
 and fixed exaftly in its axis. This tube was exhaullcd 
 JSeeAfn- of air, by means of an air-pump, till the manometer ^ 
 mmttcr in ftood at the height of four lines. It was inclofed in an- 
 tLuSuppl. ether tube of paftcboard, except about two inches, ex- 
 adlly in the middle, to which place the fun's rays were 
 directed for half an hour by means of a concave mirror. 
 The ends of the copper bar were fcooped out into con- 
 cave hemifpheres ; and into each of thefe the bulb of a 
 very fenfible thermometer was fixed. The tube was 
 placed vertically. The higheft thermometer, which we 
 (hall call A, rofe to 95", a hundred and one feconds 
 before the lowefl: B. The thermometer B rofe no higli- 
 
 » Phil. 
 
 'Iranf. 
 
 Part II, 
 
 CHEMISTRY. 263 
 
 er th»n 95° ; but the thermometer A reached 101,75='. ^"'"'"^ 
 To fee whether this difference was owing to the ther- ' 
 
 mometers, the tube was inverted, and confequcntly the 
 higheft thermometer in the firmer experiment was low- 
 eft in this. The thermon.cter li now rcfe from 49*^ to 
 97,25 in 28:0"; the thermometer A in 2763", or 47" 
 fooner than B. It wa.s evident from this refult, that 
 the thermometer A Was more fenfible than the thermo- 
 meter B by 47'. If this be fubtracfed from ici", the 
 former dift'crcnce, it will leave ^4', as the dilTcrence rc- 
 fulting from polition. Thefe experiments wtie repeat- 
 ed with only this difference, that round the ends of the 
 bar and the bulbs of the thermometers (but without 
 touching the bulbs) fome folds of oiled paper were 
 wrapped to confine the caloric. The fuperiur thermo- 
 meter A rofe from 50° to 106,25" '" 34 minutes, 
 which was 93' fooner than the inferior B : it rofe to 
 iir,75'', the thermometer B only to 106,25". The 
 tube being reverfed, the thermometer A, which was now 
 lowefl, rofe from 46" to 1 15,25° in 40' 30", or fortv fe- 
 conds fooner tiian the thermonieter B. This fubtracted 
 from yy, as formerly, leaves ^7^' for the difference of 
 fituation. The fuperiur thermometer mounted aftci the 
 burning.glafs was removed 0,45*-', remained ftationary 
 for 83 ', and after five minutes had only dtfcended 0,45-: 
 the other did not afcend at all ; in one minute it defcend- 
 ed 0,225", and in 6' 8' it dcfccuded 2,47*^. In 22' 50" 
 the infeilor defcended 63,725", the fuperior 61,475"*- * -^'^'^ 
 From thefe experiments, it is obvious that the particles-^j'^ '' ^""^ 
 of caloric move fomewhat fafter, and in fomewhat great- 
 er quantity, upwards than downwards ; owing, doubt- 
 lefs, to the repulfive power of tlie caloric in the earth. 
 The fmall quantity of air that remained in the tube 
 may perhaps be fuppofed fufficicnt to accomit for the 
 difference, without allowing any fuch tendency upwards 
 in caloric. But it is evident from the experiments of 
 the Florentine academicians on the fame fubjed, with 
 tubes full of air, that even when in great abundance, 
 that fluid hardly affefted the riling of the fuperior ther- 
 mometer ; furely then its elfecl mull be altogether im- 
 perceptible when fo little of it remained ; and in the 
 third and fourth experiments the oiled paper prevented 
 any of the heated air from approaching the thermo- 
 meter. 
 
 5. If we take a bar of iron and a piece of (lone of ConduiJlirg 
 equal dimenfions, and putting one end of each into theP"™"" "f 
 fire, apply either thermometers or our hands to the''"'^'^'" 
 other, we fliall find the extremity of the iron fenfiblv 
 hot long before that of the flone. Caloric therefore 
 does not pafs through all bodies with the fame celerity 
 and eafe. The power that bodies have to allow it 3 
 paffagc through them Is called their conduiltn^ (iniuer ; 
 thofe that allow it to pafs with facility, arc called vood 
 conduSors ; thofe through which it paifcs with difficul- 
 ty, are c3\\eA Lad conduilors ; and thule which do not 
 allow it to pa-fs at all, noii-condullors. 
 
 It is probable that all folids conduft heat in fome de- Of wooi 
 gree, at leall this is the cafe with every one at prefent and char- 
 known. Woodandcharcoal are exceeding bad condudlors '°*' » 
 of caloric (e). Count Rumford informs us, that a piece 
 
 of 
 
 (e) This faft merits the attention of chemlfts. It is obvious, that when metallic oxides are furrounded with 
 charcoal powder, their temperature cannot be raifed near fo high as it otherwlfe would be. It Is net unlikely 
 that fome part of the difficulty which has been experienced in attempting to reduce and fufe feveral nietalljc fuix- 
 ftances may have been owing to this caufe.
 
 CHEMISTRY. 
 
 of green oak plank was employed to (lir the meltcff me- of ice, the velocity of both currents was accelerated. It 
 '••' of which cannons were founding at Munich, and it diminifliod as the liquid cooled ; and when it had acqni 
 
 was often allowed to renviin a tonfiderablc time in the 
 furnnoe ; yet the caloric hii<l ]icnetrated to fo inconfi- 
 derible a depth, that at the dill mce of xnth of an inch 
 below the fnrface, the wood did not feem to have been 
 
 diminifliec 
 
 red tile temperature of the room, the motion ceafeil al- 
 toT^ether. This experiment was repe.ited with lintfeed 
 oil, and the refiitt was precifely the fame. Thefe cur- 
 rents were evidently produced by the particles of the li- 
 
 Of giaCs; 
 
 •54 
 Of n etal; : 
 
 ■f Jsurn.df order f 
 
 Pb\'. 17S9, 
 p 6s. 
 
 the Icall afleCled by it ; the colour remained unchan- quid going individually to the fides of the tube, and gi- 
 
 ged, and it did not appear to have loll even its moif. ving out their caloric. The moment they did fo, their 
 
 ture *. fpecific gravity being increafed, they fell to the bottom, 
 
 Glafs, when not tranfparent (f), is alfo a very ba<i and of courfe puflied up the warmer part of the fluid, 
 ccnduftor : and this is the reafon that it is fo apt to which was thus forced to afcend along the axis of the 
 crack cm being heated or cooled fuddenly ; one part of tube. Having reached the top of the tube, the parti- 
 it receiving or parting with its caloric before the relt, cles gave out part of their caloric, became fpecifically 
 expands or contrafts, and deftroys the cohefion. heavier, and tumbled in their turn to the bottom. 
 
 Metals are the bell conduftors of caloric of all the As thefe internal motions of fluids can only be dif- 
 
 folids hitherto e.^;amined. The conducting powers of covered by mixing with them bodies of the fame fpe- 
 
 all, however, are not equal. Dr Ingenhoufi procured cific gravity with themfelves, and as there is hardly any 
 
 cylinders of feveral metals exactly of the fame fize, and fubllance of the fame fpecific gravity with water which 
 
 having coated them wiih wax, he plunged their ends is not foluble in it. Count Rumford had recourfe to the 
 
 into hot water, and judged of the conducting power of following ingenious method of afcertaining whether 
 
 each by the length of wax-coating melted. From thefe that fluid alfo followed the fame law. The fpecific 
 
 experiments he concluded, that the conducting powers gravity of water is increafed confiderably by difTolving 
 
 of the metals which he examined were in the following any fait in it ; he added, therefore, potafs to water till 
 
 Silver, 
 Gold, 
 
 ry- ' > nearly equal. 
 
 Platinum,' 
 
 o J > much inferior to the others. 
 
 Lead 
 
 Of rtones 
 and folicli 
 capable of 
 melting. 
 
 456 
 Whether 
 fluids be 
 
 condu(ftArs 
 of tiluric. 
 
 257 
 •What led 
 him to this 
 opinion. 
 
 inum,"! 
 
 ■• 
 
 water, 
 
 its fpecific gravity was exaftly equal to that of amber, 
 a fubftance but very little heavier than pure water. A 
 number of fmall pieces of amber were then mixed with 
 this folution, and the whole put into a glafs globe with 
 a long neck, which, on being heated and expofed to 
 cool, exhibited exactly the fame phenomena with the 
 other fluids. A change of temperature, a.-nounting on- 
 ly to a very few degrees, was fufficient to fet the cur- 
 rents a-flowing ; and a motion might at any time be 
 Next to metals ilone feems to be the beft conJiuSors; produced by applying a hot or a cold body to any part 
 but this property varies confiderably in different ftones. of the veflel. When a hot body was applied, that part 
 Bricks are much worfe conductors than moll ftones. of the fluid neareft it afcended; but it defcended on the 
 All lollds capable of being melted become non-conduc- application of a cold body. ,.g 
 
 tors the moment they are heated to the melting point: If caloric pals through water only by the internal Proofs of 
 
 the caloric enters them eafily enough, but it remains in motion of its particles, as this experiment feems to'''^"°n; J 
 them_. prove, it is evident that every thing which embarraires*^"'"'" "?» 
 
 A qnefllon has lately been agitated among philofo- thefe motions niuft retard its tranfmiffion : and accord-jyater I 
 phers, Whether fluids be conduftors of caloric ? No ingly Count Rumford found this to be the cafe. He 
 doubt was entertained of their being not only conduc- took a large lintfeed oil thermometer with a copper 
 tors, but good conduftors, till the publication of Count bulb and glafs tube : the bulb was placed exaftly in the 
 Rumford's Eflays, in which the author contends, with centre of a brafs cylinder, fo that there was a void fpace 
 much plaufibillty of reafoning, that though fluids carry, between them all around 0,25175 of an inch thick. 
 they do not condud heat ; or, in other words, let it pafs The thermometer was kept in its place by means of 
 freely from one particle to another. four wooden pins projefting from the fides and bottom 
 
 In a fet of experiments on the communication of of the cylinder, and by the tube of it pafling through 
 heat, he made ufe of thermometers of an uncommon the cork flopper of the cylinder. This cylinder was 
 fize. Having expofed one of thefe (the bulb of which filled with pure water, then held in melting fnovv till 
 was near four Inches in diameter) filled with alcohol to the thermometer fell to 32°, and immediately plunged 
 as great a heat as it could fupport, he placed it in a into a veflel of boiling water. The thermometer role 
 window to cool where the fun happened to be flilning. from 32° to zoc in 597 '. It is obvious that all the 
 Some particles of duft had by accident been mixed with caloric which ferved to raife the thermometer mull have 
 the alcohol: thefe being illuminated by the fun, became made its way through the water in the cylinder. The 
 perfeftly vlfible, and dllcovered that the whole liquid in experiment was repeated exaftly in the fame manner; 
 the tube of the thermometer was in a moll rapid mo- but the water in the cylinder, which amounted to 2276 
 tion, running fwiftly in oppofite direftlons upwards and gr. had 192 gr. of llarch boiled in it, which rendered it 
 downwards at the fame time. The a/cending current much lefs fluid. The thermometer now took 1 109'' to 
 occupied the axis, the defcend'wg cvivrtnv the fides of the rife from 32° to 200°. The fame experiment was again 
 tube. When the fides of the tube were cooled by means repeated with the fame quantity of pure water, having 
 
 ( F ) When tranfparent, it tranfmits caloric.
 
 Vivt I. C H li M 
 
 ■Caloric. 192 gr. of tifierdown mixed with it, vhich would mcrc- 
 ^•— V— — ly tend to cmbarrafs the motion of the particles, A 
 quantity of Rcwed apples were alfo in another cxjieri. 
 incnt put into the cylinder. The following Tables ex- 
 hibit the refult of all thefe experiments. 
 
 Time tie Caloric was in pajjing into the Thermometer 
 
 159 
 
 Tempera- 
 ture. 
 
 Through 
 the Water 
 
 and Starch. 
 
 Thro* the 
 Water and 
 Ei Jerdown. 
 
 Through 
 
 llewed 
 
 Aiiplc'. 
 
 Through 
 
 pure 
 Water. 
 
 Therm, rofc 
 from 3 !" tu 
 2CG° in 
 
 seconds. 
 1109 
 
 Seconds. 
 
 949 
 
 Seconds. 
 IC96J 
 
 Second-. 
 
 J97 
 
 Therm, rofe 
 80°, mv.. 
 from So° to 
 160°, ill 
 
 34« 
 
 269 
 
 335 
 
 172 
 
 Time the Caloric tuas in paffing out of the Thermometer. 
 
 Tempera- 
 ture. 
 
 Througli 
 the Water 
 and Starch. 
 
 Thro' the 
 Water and 
 Eiderdown. 
 
 Through 
 
 ftewed 
 
 Apples. 
 
 Through 
 
 (lire 
 
 Water. 
 
 Therm, fell 
 from 200° 
 to 40° in 
 
 Seconds. 
 1548 
 
 Seconds. 
 1541 
 
 Second?. 
 
 '7491 
 
 Seconds. 
 1032 
 
 Therm, fell 
 800, viz. 
 from 160° 
 to So=', in 
 
 468 
 
 460 
 
 520 
 
 277 
 
 Now neither the ftarch nor the eiderdown could pro- 
 duce any alteration in the water except impeding its 
 internal motions; confequently whatever impedes thefe 
 motions diminifhes the condufting power of water. But 
 this could not happen unlefs every individual particle 
 aftually went from the cylinder to the thermometer. 
 Hence it follows that, if liquids be conduiftors, their 
 conducing power is but fmall when compared with 
 their carrying power. 
 
 All liquids, however, are capable of condufting calo- 
 ric ; for when the fource of heat is applied to their fur- 
 face, the caloric gradually makes its way downwards, 
 and the temperature of every ftratum gradually dimi- 
 nilhes from the furface to the bottom of the liquid. 
 The increafe of temperature in this cafe is not owing 
 to the carrying power of the liquid. By that power 
 caloric may indeed make its way upwards through li- 
 quids, but certainly not downwards. Liquids then are 
 conduftors of caloric. 
 
 Count Rumford, indeed, has drawn a different con- 
 clufion from his experiments. He fi.\ed a cake of ice 
 in the bottom of a glafs jar, covered one-fourth inch 
 thick with cold water. Over this was poured gently a 
 coniiderable quantity of boiling water. Now if water 
 were a non-con duftor, no caloric could pafs through 
 the cold water, and confequently none of the ice would 
 be melted. The melting of the ice, then, wan to de- 
 termine whether water be a conduftor or not. In two 
 hours about half the ice was melted. This one would 
 think, at firft fight, a decifive proof that water is a con- 
 duftor. But the Count has fallen upon a very ingeni- 
 
 Suppi.. Vol. I. Part. I. 
 
 I S T R V, 265 
 
 ou6 method of accounting for the melting of the lee, Caloric, 
 without being under the neccflity (as he tells us) of re- • ' 
 nouncing his theory that fluids are non-conduftors. 
 
 It is well known that the fpecifio gravity of water at 
 40° is a m:\ximum : if it be cither heated above 40'', or 
 cooled down below 40°, its dcnlity diminifiies. There- 
 fore, whenever a particle of water arrives at the tempe- 
 rature of 40'^ it will link to the bottom of the velTcL 
 Now as the water next the ice was at 32*, it is evident 
 that whenever any part of the hot water was cooled 
 down to 40°, it would fink, difplace the water at 32°, 
 come into contadl with tlie ice, and of courfe melt it. 
 The Count's ingenuity, never without rcfources, ena- 
 bled him to prove completely, that the ice employed in 
 his experiment was adually melted in that manner : for 
 when he covered the ice partially with flips of wood, 
 that part which was (haded by the wood was not melt- 
 ed ; and when he covered the whole of the ice with a 
 thin plate of tin, having a circular hole in the middle, 
 only the part exattly under the hole was melted. From 
 thefe fafts it certainly may be concluded that the ice 
 was melted by defcending currents of water. 
 
 But the point to be afcertained, is not whether there 
 were defcending currents, but whether water be a con. 
 duftor or not. Now if water be a non.conduftor, by 
 what means was the hot water cooled down to 40°? 
 Not at the furface ; for the Count himfelf tells us, that 
 there the temperature was never under 108'': not by 
 the fides of the velfel ; for the defcending current in one 
 experiment was exadlly in the axis : and it follows ir- 
 refiftibly, from the experiment with the flips of wood, 
 that thefe defcending currents fell equally upon every 
 part of the furface of the ice ; which would have been 
 impoflible if thefe currents had been cooled by the fide 
 of the veflel. The hot water, then, muft have been 
 cooled down to 40° by the cold water below it ; con- 
 fequently it muft have imparted caloric to this cold wa- 
 ter. If fo, one particle of water is capable of abforb- 
 ing caloric from another ; that is, luater is a condudor 
 of caloric. After the hot water has ftood an hour over 
 the ice, its temperature was as follows : 
 
 At the furface of the ice 40' 
 
 One inch above the ice 80 
 
 Two inches • - 118 
 
 Three inches - - 128 
 
 Four inches - - 130 
 
 Seven inches • - 131 
 
 How is it poffible to account for this gradual diminli- 
 tion of heat as we approach the ice, if water be a non- 
 conduftor ? The water, it may be faid, gives out calo- 
 ric at its furface, falls down, and arranges itfelf accord- 
 ing to its fpecific gravity. If fo, how comes it that 
 there is only one degree of difference between the tem- 
 perature at 4 and at 7 inches above the ice ? Thus it 
 appears that the Count's experiment, Inflead of demon- 
 ftrating that water is a non-conduftor, rather favours 
 the common opinion that it is a conduftor. 
 
 The Count tried whether oil and mercury be con- «^ ' * 
 duftors in the following manner : When water was fro-anj o\\ pro. 
 zen in a glafs jar by means of a freezing mixture. Count ved to be 
 Rumford obferved that the ice firft began to be formed condu<2ort. 
 at the fides, and gradually increafed in thicknefs ; and 
 that the water on the axis of the velTel, which retained 
 its fluidity longeft, being comprefled by the expanfion 
 of the ice, was forced upwards, and when completely 
 L I frozen.
 
 166 
 
 C H E M I 
 
 
 Caloric, frozen, formed a pointed projeftion or nipple, which 
 ■""v-"^ was foinetimes half an inch higiier than the rt(t of the 
 ice. Upon ice frozen in this manner, he poured olive 
 oil, previuiifly cooled down to 32°, till it flood at the 
 lifiyht of tliree inches above the ice. The veffel was 
 furroiirded as high as the ice with a mixture of pounded 
 ice and water. A folid cylinder of wrought iron, i-Jth 
 inch in diameter, and 12 inches long, provided with a 
 hollow cylindrical fheath of thick paptr, was heated to 
 the temperature of 2 10° in boiling water; and being 
 fuddenly introduced into its fheath, was fuipended from 
 the ceiling of the room, and very gradually let down 
 into the oil, until the middle of the flat furface of the 
 hot iron, which was direCily above the point of conical 
 projtftion of the ice, was diflant from it only t'o'^^^ '^^ 
 an inch. The end of the fneatli dcfcenJed VoVh "' ^n 
 inch lower than the end of the hot nietallic cylinder. 
 Now it is evident, that if olive oil was a condudlor, ca- 
 loric would pafs down through it from the iron and 
 melt the ice. None of the ice, however, was melted ; 
 and when mercury was fubllituted for oil, the refult 
 • Rumjord, was jufl the fame * ; confequently it follows that nei- 
 F.J-iy-n. iJj^T oil nor mercury is a conduftor of heat. 
 
 But this experiment is by no means fufficiently deli- 
 cate to decide the point. If a thermometer be fubili- 
 tuted inilead of the nipple of ice, it always rites fcve- 
 ral degrees ; whence it follows that, even in this cafe, 
 caloric palTcs downwards; fo that the experiment is 
 in faft favourable to the fuppofition that oil and mer- 
 cury are conduftors. 
 
 Count Rumford therefore has not proved that fluids 
 are non-conduftors of caloric ; and that they are in 
 truth cunduftors, the author of this article afctrtained 
 in the following manner : The liquid of which the con- 
 ducting power was to be examined was poured into a 
 glals vcfTcl till it filled it about half way ; then a hot 
 liquid ot lels fpeciiic gravity was poured over it. Ther- 
 mometers were placed at the furface, in the centre, and 
 at the bottom of the told liquid ; if thefe rofe, it fol- 
 lowed that the liquid was a condudlor, becaufe the ca- 
 loric made its way downwards. For inflance, to exa- 
 mine the condufting power of mercury, a glafsjar was 
 iialf filled with that liquid metal, and boiling water then 
 poured over it. The thermometer at the furface began 
 immediately to rife, then the thermometer at the centre, 
 and hillly that at the bottom. The firit rofe to 118", 
 the fecond to 90 , and the third to 86": the firfl reach- 
 ed its maximum in i', the fecond in 15', the third in 
 25'. The conducing power of water was tried in the 
 iame manner with hot oil poured over it ; and the re- 
 iult was fimilar. 
 
 Fluids, then, as far as experiments have been made, 
 
 are conduftors of caloric as well as folids ; and hence 
 
 it follows that caloric is capable of making its way thro' 
 
 all bodies with which we are acquainted. In this rc- 
 
 fpedt it differs from all other lubltances, even from 
 
 light, which, as far as we know, cannot make its way 
 
 through all bodies. 
 
 Tranfmif- '-^^^ motion of caloric through bodies is indeed of 
 
 fioii of c3- two kinds : Through fome it feems to move with the 
 
 Icric ra- fame rapidity as througli. free fpace ; whillt through 
 
 diant heat. 
 
 S T R Y. Part L 
 
 others, as we' have fecn, it moves flowly. When it Caloric. 
 
 moves through a body with undiminilhed velocity, it is v ' 
 
 faid to be tranfmilted through it ; and when its velocity 
 
 is prodigioufly dlminilhed, it is faid to be conduftcd. 
 
 Air, and all tranfparent bodies hitherto examined, have 
 
 the property ot iranfm'tllin^ caluiic through them ; 
 
 though fome of them, ao glafs, do not tranimit it till 
 
 after thty have combined with a certain proportion of 
 
 it : and probably no body tranfnu'ts it unlefs a greater 
 
 quantity enter than is capable of combining witli it in 
 
 the flate in which the body is placed. The phenomena 
 
 of the tranfmifGon of caloric are exaiflly fimilar to the , 
 
 tranfmlflion of light, and admit of precifely Uie fame ■ 
 
 explanation. What Scheele and feveral other chemiflij 
 
 have called radiant heat, is nothing elfe than tranfmitted 
 
 caloric ; as has been completely proved by Dr Hcr- 
 
 fchel. See 'TuhRMOMETRtc SpeBrum in this Supplement. t, 
 
 6. If equal quantiiiea of water and of mercury be pin- Specific ca- 
 ced at the lame dilfance from a fire, the mercury will loiic of bo- 
 become hot much fooner than the water. After a fuf.'^'^^i "ha:, 
 ficient interval, however, both of them acquire the fame 
 temperature. Now caloric flows into all bodies while 
 they continue of a lower temperature than thofe around 
 them, and it flows with equal rapidity into all bodies 
 of the fame conducting powers, as is the cafe with thcfc 
 two fluids: But if equal quantities of caloric were con- 
 flantly flowiflg into the mercury and the water, and yet 
 the water took a longer time to become hot than the 
 mercury, it mufl require a greater quantity of caloric to 
 raife water to a given temperature than it does to raife 
 mercury. Bodies that require a greater quantity of 
 caloric to raife them to a particular temperature than 
 other bodies require, are faid to have a greater capacity 
 for caloric. That the capacity for caloric i.s different 
 in different bodies, was firfl obferved by Dr Black. 
 Dr Irvine afterwards invefligated the fubjeff, and Dr' 
 Crawford publifhed a great number of experiments on 
 it in his Treatife on Heat. Piofeffor Wilcke of Stock- 
 holm alfo difeovered ths fame property of bodies. He 
 called the quantity of caloric necelTary to raife the tern-- 
 perature of fubllances a given number of degrees, their 
 fpecific caloric ; a term which we fliall alfo employ, be- 
 caufe the phrafe capacity for caloric is liable to a greaf 
 deal of ambiguity, and has introduced confufion into 
 this fubjett (f). It two fubflances of unequal tempe- 
 ratures, as water at 100° and alcohol at 50", be mixed 
 together, the mixture will be of a temperature different' 
 both from that of the water and the alcohol, the water 
 will become colder and the alcohol hotter : the water 
 will give out caloric to the akohol till both are reduced 
 to the fame temperature. Now if it requires juft as 
 much caloric to raife alcohol a certain number of de- 
 grees as it docs to raife water the fame number, that is, 
 if thefe two fluids are of the fame fpecific caloric, it is 
 evident that the temperature of the mixture will be jufl;' 
 7 i;" ; for as foon as the water has given out 25° of ca- 
 loric, the alcohol has acquired 25°, confequently both 
 will be reduced to the fame temperature, and will re- 
 main flationary ; but if the fpecific caloric of the wa. 
 ter be greater than that ot the alcohol, the tempera, 
 ture of the mixture will be higher than 75° ; for 25" 
 
 of 
 
 (f) The term fpecific caloric has been ufed in a different fenfe by Seguin. 
 which a body contains. 
 
 He ufed it for the ivliole caloric
 
 Part I. 
 
 Calorii 
 
 _ 16.1 
 Bxpcri- 
 Iiients on 
 fpecific ca- 
 loric by 
 Wilckc, 
 
 of caloric in tliat cafe would niifc alcoliol more tlian 
 2j°. If the fpecific caloric of water be fo much great- 
 er than that of alcohol, that what raifes water 20" will 
 raife alcohol 30" ; then the temperature after mixture 
 will be 80", bccaufe when the water has given out 20\ 
 the alcohol will liave rifen 30% and of courfe both will 
 be of the fame temperature. On the contrary, if the 
 fpecific caloric of alcohol were greater than that of wa- 
 ter, the temperature of the mixture would be under 7 j". 
 If the fame quantity of calorie that raifed alcohol 20" 
 raifed water 30°, then the temperature of the mixture 
 would be 70". Thus the ratios of the fpecific caloric 
 of bodies may be dilcovered by mixing them together 
 at different temperatures. 
 
 The firil fet of experiments on this fubjcft, in point 
 of time, were probably thofe of Mr VVilcke. They 
 were firft publilhed in the Stockholm TranfaCtions for 
 1781, but had been made long before. The manner in 
 which they were conduced is exceedingly ingenious, 
 and they furnifh us with the fpecific caloric of many of 
 the metals. The metal on which the experiment was 
 to be made was firft weighed accurately (generally one 
 pound was taken), and then being fufpended by a 
 thread, was plunged into a large veflel of tinplate, filled 
 with boiling water, and kept there till it acquired a cer- 
 tain temperature, which was afcertained by a thermo- 
 meter. Into another fmall box of tinplate exadlly as 
 much water at 32" was put as equalled the weight of 
 the metal. Into this velTel the metal was plunged, and 
 fufpended iri it fo as not to touch its fides or bottom ; 
 and the degree of heat, the moment the metal and wa- 
 ter were reduced to the fame temperature, was marked 
 ■hy a very accurate thermometer. He then calculated 
 what tlie temperature would have been if a quantity of 
 water equal in weigh/ to the metal, and of the fame tem- 
 perature with it, had been added to the ice-cold water 
 inftead of the metal. 
 
 Let M be a quantity of water at the temperature C, 
 m another quantity at the temperature c, and let their 
 common temperature after mixture be x ; according to 
 
 a rule demonftrated long ago by Richman, x=;-rT- — ^ 
 
 ° " ■' M -H m • 
 
 In the prcfent cafe the quantities of water are equal, 
 
 therefore M and m are each = i ; C, the temperature 
 
 r .1 • , J , _ MC -J- ?71 c 
 
 ot the ice-cold water = 32 : therefore ,.■ ' 
 
 32 4-c . M-f-m 
 
 — J M„..r , ,s the temperature of the metal. 
 
 CHEMISTRY. 
 
 ties. Therefore the volume of ice cold water is to 
 a quantity of hot water equal in volume to theme-' 
 as tiie fpecific gravity of the metal to that of the 
 
 Now 
 
 Therefore if ^2 be added to the temperature of the me- 
 «al, and the whole be divided by 2, the quotient will ex- 
 prefs the temperature of the mixture, if an equal weitrht 
 of water with the metal, and of the fame temperature 
 with it, had been added to the ice-cold water inftead of 
 the metal. 
 
 He then calculated what the temperature of the mix- 
 ture would have been, if, inftead of the metal, a quantity 
 of water of the fame temperature with it, and equal to 
 the metal in hulk, had been added to the ice-cold water. 
 As the weights of the ice-cold water and the metal are 
 rqual, their volumes are inverfely as their fpecific gravi- 
 
 tal, 
 
 water. Let M = volume of cold water, m = volume 
 ot hot water, g =: fpecific gravity of the metal, i = 
 fpecific gravity of water ; then m : M : : i : g\ hence 
 
 M . - , 
 
 "' — ~r — (^ being made 3: i ) — . Subftituting 
 
 this value of m in the formula, . , . ' ' ■ = x, in 
 
 v/l -\- m 
 
 which M : 
 
 and C = 
 
 32, X wi 
 
 be = . 
 
 + I 
 
 (g) We have altered all thefe fonnulas to make them corrtfpond wit'h Fahrenheit's thermometer. They are a 
 pood deal fimpler when the experiments are made with Celfius's thermometer, as Mr Wlleke did. In it the 
 freezing point is zero ; and confequently inftead of 32 in the formula, o is always fubftituted. 
 
 267 
 
 Calotic. 
 . pi 
 
 Therefore if the fpecific gravity of the metal be multi- 
 plied by 32, and the temperature of the metal be add- 
 ed, and the fum be divided by the fpecific gravity of 
 the metal -I- r, the quotient will exprefs the tempera- 
 ture to which the ice-cold water would be raifed by 
 adding to it a volume of water equal to that of the me- 
 tal, and of the fame temperature witli it. 
 
 He then calculated how mucii water at the tempera- 
 ture of the metal it would take to raife the ice-cold wa- 
 ter the fame number of degrees which the metal had 
 raifed it. Let the temperature to which the metal had 
 raifed the ice-cold water be =: N, if in the formula 
 MC-f-mf 
 ~M'+7,r' - "' " '^^ '"^'^^ ~ '^' M = T, C = 32, w 
 
 N— :!2 
 will be = ^ j^ . Therefore if from the temperature 
 
 to which the ice-cold water was raifed by the metal 32 
 be fubtratled, and if from the temperature of the metal 
 be fubtratled the temperature to which it raifed the wa- 
 ter, and the firft remainder be divided by the laft, the 
 quotient will exprefs the quantity of water of the tempe- 
 rature of the metal which would have raifed the ice-cold 
 water the fame number of degrees that the metal did. 
 
 XT N-32 
 
 Now ^ ^ exprefles the fpecific caloric of the me- 
 tal, that of water being =: i. For (negleding the 
 fmall difference occafioned by the difference of tempera- 
 ture) the weight and volume of the ice-cold water are 
 to the weight and volume of the hot water as i to 
 N— 32 
 • ^ ^ . and the number of particles of water in each 
 
 are in the fame proportion. But the metal is equal in 
 weight to the ice-cold water ; It muft therefore contain 
 as many particles of matter ; therefore the quantity of 
 matter in the metal muft be to that in the hot water as 
 
 N — 32 ^ , 
 I to — _ ^ '. But they give out the fame quantity of 
 
 caloric ; which, being divided equally among their par. 
 tides, gives to each particle a quantity of caloric in- 
 verfely as the bulks of the metal and water ; that is, the 
 fpecific caloric of the water is to that of the metal as t 
 
 We fliall now give a fpeclmen or two of I1I3 experi- 
 ments, and the calculations founded on them, as above 
 dcfcribed. 
 
 I- 1 2 Gold
 
 C H E M 
 
 Gold. Specific Gravity 19,040. 
 
 164 
 Crawfortl, 
 
 265 
 
 Lavoifier 
 and J.a 
 Place, 
 
 
 
 
 Temper, to 
 
 Tempera- 
 
 
 
 
 Tempe- 
 
 which it 
 
 ture to 
 
 Denomina- 
 
 
 
 would have 
 
 which it 
 
 tor of the 
 
 Num- 
 
 Tempe- 
 
 which 
 the me- 
 tal raifoi 
 thewatci 
 
 been ralfed 
 
 would have 
 
 fradion 
 
 ber of 
 experi- 
 ments. 
 
 rature of 
 the me- 
 tal. 
 
 by a (juan- 
 tityof watei 
 
 equal in 
 weijiht and 
 
 been railed 
 by water e- 
 qual in bulk 
 and te.iipe- 
 
 M-3. ' 
 
 N_32 
 
 the numera. 
 
 
 
 
 heat to the 
 metal. 
 
 ratureto ihc 
 metal. 
 
 tor bein^; i . 
 
 I 
 
 163,4" 
 
 38.3" 
 
 97,7" 
 
 38,555" 
 
 I9.«57 
 
 2 
 
 •44.5 
 
 37.4 
 
 88,25 
 
 37,58 
 
 19,833 
 
 3 
 
 '27.4 
 
 36.5 
 
 79,7 
 
 36,68 
 
 20,500 
 
 4 
 
 118,4 
 
 36,05 
 
 75.2 
 
 36,15 
 
 20,333 
 
 5 
 
 103,1 
 
 2S^(^ 
 
 65,75 
 
 35>42 
 
 18,750 
 
 6 95 
 
 34.45 
 
 63,5 
 
 35,06 
 
 t9,ooo 
 
 Mean 19,712 
 
 Lead. Specific Gravity 11,^^6. 
 
 Num- 
 ber of 
 experi- 
 ments. 
 
 Tempe- 
 rature ol 
 the me- 
 tal- 
 
 Tempe- 
 rature to 
 
 vhxh 
 
 the me- 
 tal raifed 
 thewater 
 
 at 3J°. 
 
 Tempera- 
 ture to 
 
 which the 
 waterwi.'uld 
 
 have been 
 raifed hy a 
 quantity nf 
 water equal 
 
 in weight 
 and heat to 
 
 (he meial. 
 
 Tempera- 
 ture to 
 
 which the 
 waterwoulc 
 
 have been 
 
 raifed by 
 water equa] 
 in bulk and 
 temijeraturc- 
 
 to the me- 
 tal. 
 
 Denomina- 
 tor of the 
 fradlion 
 
 I 
 
 c— N 
 
 N-3» 
 
 I 
 
 186,8 
 
 38,3 
 
 109,4 
 
 44.425 
 
 23,571 
 
 2 
 
 181,40 
 
 37,85 
 
 106,7 
 
 43.473 
 
 24,538 
 
 3 
 
 165,2 
 
 37,4 
 
 98,6 
 
 42,692 
 
 23,666 
 
 4 
 5 
 6 
 
 163,4 
 
 37.4 
 
 97,7 
 
 42,548 
 
 23,333 
 
 136,4 
 
 36,5 
 
 84,2 
 
 40,344 
 
 22,200 
 
 >3i 
 
 36,05 
 
 81,5 
 
 39,947 
 
 24,700 
 
 7 
 
 '26,5 
 
 36,05 
 
 79.25 
 
 39,585 
 
 22,333 
 
 ■ 8 
 
 107,6 
 
 35,15 
 
 69,8 
 
 3«.339 
 
 23,000 
 
 9 
 
 94,1 
 
 34,7 
 
 63,05 
 
 56,985 
 
 22,000 
 
 Mtan 23^515 
 
 It is needk'fs to add, that the laft column marks^he 
 denominator of the fpecific caloric of the metal, the 
 numerator being always i, and the fpecific caloric of 
 ■water being i. Thus the fpecific caloric of gold is 
 
 . In exaftlv the fame manner, and by takine: 
 
 19,712 ■' ' / o 
 
 a mean of a number of experiments at different tempe- 
 ratures, did Mr Wilcke afcertain the fpecific caloric of 
 a number of other bodies. He afcertained at the fame 
 timf, that the fpecific caloric of a body did not vary 
 witlr the temperature, but continued always the fame. 
 This will appear evident from the experiments oa gold 
 and lead above exhibited. 
 
 Next, in point of time, and not inferior in Ingenious 
 contrivances to enfure accuracy, were the experiments 
 of Dr Crawford, made by mi.xing together bodies of 
 different temperatures. Thefe were publifiied in his 
 Trcatife on Heat. 
 
 Several experiments on the fpecific caloric of bodies 
 were made aifo by Lavoifier and De la Plaee, which, 
 from the well-known accuracy of thefe philofophers, 
 cannot but be very valuable. 
 
 Their method was exceedingly fimple and ingenious; 
 
 I S T R Y. 
 
 it was firft fuggeiled by De la Place. An iiiftrument 
 was contrived, to which Lavoifier gave the name of ca- ' 
 lorimeler. It confills of three circular veflcls nearly in- 
 fcribed into each other, fo as to form three different a- 
 partments, one within the other. Thefe three we fhall 
 call the interior, middle, and external cavities. The in- 
 terior cavity ///y"( fee feftion of the inllrument fig. 4.), 
 into ivhich the fubftances fubmitted to experiment aie 
 put, is compofed of a grating or cage of iron wire, fup- 
 ported by feveral iron bars. Its opening or mouth LM 
 is covered by the lid HG, which is compofed of the 
 fame materials. The middle cavity bbbb is filled with 
 ice. This ice is fupported by the grate m m, and un- 
 der the grate is placed a fieve. The external cavity 
 aaflflis alfo filled with ice. We have mentioned al- 
 ready, that no caloric can pafs through ice. It can en- 
 ter ice, indeed, but it remains in it, and is employed in 
 melting it. The quantity of ice melted, then, is a mea- 
 fure of the caluric which has entered into the ice. The 
 exterior and middle cavities being filled with ice, all the 
 water is allowed to drain away, and the temperature of 
 the interior cavity to come down to 32°. Then the 
 fubftance, the fpecific caloric of which is to be afcer- 
 tained, is heated a certain number of degrees, fuppofe 
 to 2r2', and then put Into the interior cavity enclofed 
 in a thin vefTcl. As it cools, it melts the ice in the mid- 
 dle cavity. In proportion as it melts, the water runs 
 through the grate and fieve, and falls through the co- 
 nical funnel cc d and the tube xy into a veiTel placed 
 below to receive it. The external cavity is filled with 
 ice, in order to prevent the external air from approach- 
 ing the ice in the middle cavity and melting part of it. 
 The water produced from It is carried off through the 
 pipe ST. The external air ought never to be below 
 32^, nor above 41°. In the firft cafe, the ice in the 
 middle cavity might be cooled too low ; in the laft, a 
 current of air flows through the machine and carries 
 off fome of the caloric. By putting various fubftances 
 at the fame temperature Into this machine, and obfer- 
 vlng how much ice each of them melted in cooling 
 down to 32s it was eafy to afcertain the fpecific calo- 
 ric of each. Thus, if water, in cooling from 212 to 
 32, melted one pound of ice, and mercury ,029 of r 
 pound ; the fpecific caloric of water was one, and that 
 of mercury ,029. This appears by far the fimpleft 
 method of making experiments on this fubjedl ; and 
 muft alfo be the moft accurate, provided we can be cer- 
 tain that all the melted fnow flows Into the receiver. 
 But from an experiment of Mr Wedgewood, one would- 
 be apt to conclude that this does not happen. He 
 found that the melted Ice, fo far from flowing out, ac- 
 tually yroz^ again, and choaked up the paffage. 
 
 A table of the fpecific caloric of various bodies was^^j^jjjr^ 
 llkewlfe drawn up by Mr KIrwan, and publlfhed by Ma--n'an. 
 gellan in his Treatife on Heat. , . 
 
 From all thefe fources we have drawn up the follow. R^fuit of 
 Ing table, which exhibits at one view the fpecific calo- thefe eipe« 
 ric of thofe bodies on which experiments have hkherto'"^""* 
 been made. 
 
 We have added to it a column, expreffing the fpeci- 
 fic caloric of equal bulks of the fame bodies ; which: 
 feeras to be a more accurate way of confidering this- 
 fubjecl, and indeed the only way in which the phrafe 
 capacity for caloric is intelligible. This column was 
 formed, by multiplying the fpecific caloric of equal 
 weights of the variouj fubftances into their refpeftive 
 fpecific gravities. 
 
 Table 
 
 266
 
 Parti. 
 
 Caloric. 
 
 CHEMISTRY. 
 
 Tasle of the Specific Caloric of Various Bodies, that of Water being a i,oooo (h). 
 
 Calorie. 
 
 BoJii 
 
 I. Gases*. 
 
 Hydrogen gas - • 
 Oxygen gas ... 
 Common air ... 
 Carbonic acid gas 
 Steam . . - - . 
 Azotic gas - . - 
 
 II. Liquids. 
 
 Water 
 
 Carbonat of ammonia f 
 
 Arterial blood* - - 
 
 Cows milk* . . - 
 
 Sulphuret of ammoniaf 
 
 Venous blood* . - 
 
 Solution of brown fugarf 
 
 Nitric acid J ... 
 
 Sulphat of magnefia i 7 + 
 
 Water 8 J ^ 
 
 Common fait 
 
 Water 8 
 
 Nitre I 7 X 
 
 Water 8J + 
 
 Muriat of ammonia 
 
 Water 
 
 Tartar I 7 
 
 Water 237.3 5 
 
 Solution of potafs f 
 
 Sulphat of iron 
 
 Water 
 
 Sulphat of foda 
 
 Water 
 
 Oil of olives \ 
 
 Ammoniaf 
 
 Muriatic acidf 
 
 Sulphuric acid 
 
 Water 
 
 Alum I 7 
 
 Water 4.45 J. 
 
 Nitric acid 9 
 
 Lime 
 
 Nitre 1 7 . 
 
 Water 33* 
 
 Alcohol * - . 
 
 Sulphuric acid § 
 
 Nitrous acid-f- 
 
 Linfeed oilf . . 
 
 Spermaceti oil * 
 
 Oil of turpentine f 
 
 Vinegarf - - ■ 
 
 Lime 97 + 
 
 Water 16 J "f 
 
 Mercury ^ - . 
 
 Dillilled vinegar f 
 
 n 
 
 nia 1 7 X 
 
 V - 
 
 .fsf - 
 
 t - - 
 
 Specific 
 Gravity. 
 
 0,000094 
 
 0,0034 
 
 0,00122 
 
 0,00183 
 
 0,00120 
 
 r,oooo 
 
 1,0324 
 0,818 
 
 1,346 
 
 0.9 '53 
 
 0,997 
 
 1,122 
 
 0,8371 
 840 
 
 355 
 
 0,9403 
 
 0,9910 
 
 13.568 
 
 Specific Caloric 
 
 of equal 
 Weighf 
 
 21,4000 
 
 4.7490 
 1,7900 
 1,0459 
 l,55CO 
 
 0,7036 
 
 1,0000 
 
 1,851 
 
 1,030 
 
 0,9999 
 
 0,9940 
 
 0,8928 
 
 0,8600 
 
 0,844 
 0,844 
 
 0,832 
 
 0,8167 
 
 0.779 
 
 0,765 
 0,759 
 0.734 
 
 0,728 
 
 0,710 
 
 0,7080 
 
 0,6800 
 
 0,6631 
 
 0,649 
 
 o,6i8i 
 
 0,646 
 
 0,6021 
 
 0,5968 
 
 0,576 
 
 0,528 
 
 0,5000 
 
 0,472 
 
 0,3870 
 
 0.3346 
 
 0,3100 
 0,1030 
 
 f equal 
 Volumes. 
 
 0,00214 
 0,00641 I 
 0,002183 
 0,00193 
 
 0,000952 
 
 1,0000 
 
 1,03:2 
 0,8130 
 
 I,Z2l6 
 
 0,6498 
 
 0,7041 
 0,763 
 
 0,4993 
 
 1,120 
 
 0,780 
 0,4964 
 
 0,4132 
 0,3966 
 
 4.'23 
 0,1039 
 
 
 
 Specific Calorie 
 
 Bodies. 
 
 Specific 
 
 of equal 
 
 of equal 
 
 
 Gravity. 
 
 Weight. 
 
 Volumes. 
 
 III. Solids. 
 
 
 
 
 Icef 
 
 
 0,9000 
 
 
 Ox-hide with the hair * 
 
 
 0,787 
 
 
 Lungs of a rtieep * 
 
 
 0,769 
 
 
 Lean of ox. beef * 
 
 
 0,7400 
 
 
 Rice* 
 
 
 0,5050 
 
 
 Horfe beans * - - 
 
 
 0,5020 
 
 
 Dull of the pine tree * 
 
 
 0,5000 
 
 
 Peafe* 
 
 
 0,4920 
 
 
 Wheat* ■. . . - 
 
 
 0,4770 
 
 
 Barley* .... 
 
 
 0,4210 
 
 
 Oats* ..... 
 
 
 0,4160 
 
 
 Pitcoal* .... 
 
 
 0.2777 
 
 
 Charcoal* . - . . 
 
 
 0,2631 
 
 
 Chalk* .... 
 
 
 0,2564 
 
 
 Ruft of iron * . - 
 
 
 0,2500 
 
 
 White oxide of antimony 
 
 
 
 
 wafhed • . . - 
 
 
 0,2270 
 
 
 Oxide of copper nearly 
 
 
 
 
 freed from air * 
 
 
 0,2272 
 
 
 Quicklime {c) - - 
 
 
 0,2199 
 
 
 Stoneware f ... 
 
 
 0,195 
 
 
 Agate **.... 
 
 2,648 
 
 0,195 
 
 0.517 
 
 CryftalJ .... 
 
 3.189? 
 
 0,1929 
 
 0,6151 
 
 Cinders* .... 
 
 
 0,1923 
 
 
 Swedilh glafs** . . 
 
 2,386 
 
 0,187 
 
 0,448 
 
 AHies of cinders * 
 
 
 0,1885 
 
 
 Sulphur f . . . . 
 
 '.99 
 
 0,183 
 
 0,3680 
 
 Flint glafs t .... 
 
 3.3293 
 
 0,174 
 
 0,5792 
 
 Ruft of iron nearly freed 
 
 
 
 
 from air * . . . 
 
 
 0,1666 
 
 
 White oxide of antimo- 
 
 
 
 
 ny ditto * . . . 
 
 
 o,T 666 
 
 
 Afhcs of the elm * - 
 
 
 0,1402 
 
 
 Oxide of zinc nearly free 
 
 
 
 
 from air * . • - 
 
 
 0,1369 
 
 
 Iron (.^) .... 
 
 7.876 
 
 0,1264 
 
 0.993 
 
 Brars(rt') .... 
 
 8,358 
 
 0,1141 
 
 0,971 
 
 Copper (^) ... 
 
 8,784 
 
 0,1121 
 
 1,027 
 
 Sheet iron J ... 
 
 
 0,1099 
 
 
 Oxide of lead and tin * 
 
 
 0,102 
 
 
 Gun- metal || - - - 
 
 
 0,1100 
 
 
 White oxide of tin nearly 
 
 
 
 
 free from air * 
 
 
 0,0990 
 
 
 Zinc (//) .... 
 
 7.154 
 
 0,0981 
 
 0.735 
 
 A (lies of charcoal* 
 
 
 0,0909 
 
 
 Silver** .... 
 
 10,001 
 
 0,082 
 
 0,833 
 
 Yellow oxide of lead near- 
 
 
 
 
 ly freed from air * 
 
 
 0,0680 
 
 
 Tin [e) 
 
 7.380 
 
 o,c66i 
 
 0,444 
 
 Antimony (</) - - 
 
 6,107 
 
 0,0637 
 
 0,390 
 
 Gold** .... 
 
 19,040 
 
 0,050 
 
 0,966 
 
 Lead [e) .... 
 
 ii,45<5 
 
 0,0424 
 
 0,487 
 
 Bifmuth** - - - 
 
 9,86 1 
 
 0.043 
 
 0,427 
 
 T t" 
 
 7. If 
 
 (h) The fpecific caloric of the fubftances marked* was afcertained by Dr Crawford, thofe marked f by Mr 
 Kirwan, \ by Lavoifier and La Place, ** by Wilcke, || by Count Rumford. § Is the mean of Crawford, Kir- 
 wan, and Lavoifier; ^ mean of Lavoifier and Kirwan; (c) mean of Crawford and Lavoifier; (d) mean of 
 Wilcks and Crawford j {e) mean of Wilcke, Crawford, and Kirwan.
 
 769 
 
 Caloric nf 
 fluidity 
 
 c n E M I 
 
 •7. If a quantity of ioc, at a low temperature, fup- 
 pofe at 20", be fufpendcd in a warm room, it will be- 
 come gradually klscolil, as may be difeovercd by means 
 of a thermometer, till it reaches the temperature of 
 _32«> ; but there it ftops. The iee, however, dilTolves 
 flowly ; and at the end of feveral hours, when it ia all 
 jull melted, the thermometer ftill (lands at 32°. Af- 
 ter this it begins to rife, and foon reaches the tempera- 
 ture of the room. Here the ice continues for feveral 
 b.ours colder than the air around it. Caloric muft then 
 be continually flowing into it ; yet it does not become 
 hotter : it is changed, however, into water. Ice, there- 
 fore, is converted into water by a quantity of caloric 
 uniting with it. This calorie has been called /ateni ca- 
 loric, hecaufe its pvefence is not indicated by the ther- 
 mometer. It might, jierhaps with more propriety, as 
 Profeffor Pi&et obfervcs*, be called caloric of f.uidity ; 
 *''^'''' ''■■'■'"' for there are other cafes in which caloric exifts in bo- 
 dies without raifing their temperature. This very im- 
 portant difcovery was made by Dr Black as early as 
 J 757, and feems to have led the way to all the fubfe- 
 quent dii'coveries in this part of chemillry, which have 
 almofl completely changed tlic appearance of the fcience: 
 for the difcovery that caloric may cxift in bodies while 
 the thermometer cannot indicate its prcfence, is one of 
 the ftrongeil links in the chain of fatts by which the 
 uature of cowhullion was afcertained. 
 
 The caloric which unites with ice, and renders it 
 fluid, appears again during the aft o^ freezing. If a 
 quantity of water be carried into a room where the 
 temperature is below the freezing point, fuppofe at 20°, 
 ic cools gradually down to 32^; but it becomes no 
 colder till it is all frozen, which takes up fome time. 
 The moment it is all converted into ice, it begins 
 .jigain to cool, and foon reaches the temperature of the 
 room. In this cafe, the water is furrounded by a 
 cold atmofphere ; it muft therefore be giving out ca- 
 loric conftantly ; yet it does not become colder till it 
 is all frozen, that is to fay, till it has loll all its ca- 
 loric of fluidity. 
 
 Dr Black proved, by a very accurate experiment, 
 that the quantity of caloric cf Jluiilily is fufficient to 
 raife the fame quantity of water 140". 
 
 All foUds become fluid by abforbing a quantity of 
 caloric. Landriani proved that this is the cafe with 
 fTo.vr. A_ fulphur, alum, nitre, and feveral of the metals f ; and 
 /'iv/. xivi. jj. j^^^ \)eQn found to be the cafe with every fubftance 
 hitherto examined. Fluidity, therefore, is owing to a 
 \uiion between the foUd and a certain quantity of ca- 
 loric. 
 
 The late Dr Irvine of Glafgow advanced a theory on 
 this fubjed different from that of Dr Black. The fpe- 
 clfic caloric of water being greater than that of ice, it 
 requires a greater quantity of caloric to raife it to a 
 given temperature than it does to raife ice. The calo- 
 ric does not therefore become latent ; it only feems to 
 do fo from the greater fpecific caloric of water. This 
 
 S T R Y. 
 
 Part r. 
 
 theory was zcaloufly adopted by Dr Crawford. Dr Caloric. 
 Black obferved very juflly, that it did not account for « 
 the production of fluidity at all. The fpecific caloric 
 of water is indeed greateV than that of ice ; but how is 
 the ice convered into water ? This is an objettion 
 which the advocates for Dr Irvine's, or Dr Crawford's, 
 theory (as it has been improperly called) will not eafdy 
 anfwer. Let us now examine whether tills theory ac- 
 counts for the apparent lofs of caloric. It follows from 
 Mr Kirwan's expcrimenta, that the fpecific caloric of 
 water is to that of ice as 10 to 9(1). Dr Black 
 proved, that as much caloric entered the ice as would 
 have raifed it, had it been water, 140". Let >is fup- 
 pofe that it would only have raifed the ice 140'^; in 
 that cafe the melted ice ought to have been of the tem- 
 perature of 158^, for 10 : 9 : : 140 : 126; but it was 
 only 32°: Therefore 126'^ of caloric have difappear- 
 ed, and cannot be accounted for by the change ot fpe- 
 cific caloric. Nor can the accuracy of Dr Black's ex- 
 periment be fufpefted : it has been repeated in every 
 part of the world, and varied in evei y poflible way. 
 We cannot doubt, therefore, that caloric unites with 
 fubftances, and caufes them to become fluid, or that 
 there is in fad a caloric of Jlutdity dijerent from fpecific 
 caloric. ■ _ _ _ ,jo 
 
 Water alfo is converted into fleam by uniting wlthcjioric of 
 caloric. Dr Black put an iron veflel, containing fourevaporatiou. 
 ounces of water at tiie temperature of 53 ', upon a call- 
 iron table which was red hot. The water rofe to the 
 boiling point in three minutes ; but it did not after- 
 wards become any hotter. It evaporated, however, in 
 18 minutes; and the llcam was precifely at the tempe- 
 rature of 212^. During the firft three minutes, it re- 
 ceived 159" of caloric, and as much muft have been en- 
 tering it during every three minutes while the evapo- 
 ration continued, as the temperature was always much 
 lower than that of the table. This caloric, inftead of 
 ralfuig the temperature of the water, was employed in, 
 converting it into fteam. There is alfo, therefore, a 
 quantity of latent caloric in fteam. It might, as Mr 
 Pidlet obfcrves, be called, with propriety, caloric of eva- 
 poration. This caloric appears again if the fteam be 
 condenfed. Ifit be made to pafs, for inftance, through 
 a pipe furrounded with cold water, it is condenfed in 
 the pipe, and drops ont from it in the form of water. 
 The caloric of the fteam enters into the water around 
 the pipe, and the quantity of it in degrees may be dlf- 
 covered by the number of degrees which it raifes that 
 water. By an experiment of this kind, it was proved, 
 that the caloric of evaporation would be fufficient to 
 heat water red hot, were it employed only in raifing its 
 temperature, inftead of converting it into fteam. It is 
 therefore at leaft equal to hoo°. Mr Watt (hewed af- 
 terwards that it was 920°. 
 
 Even fpontaneous evaporation, as Dr Black firft ob- 
 ferved, is owing to the fame caufe : and this explains 
 why bodies cool when water is evaporated from their 
 
 furface ; 
 
 be 
 
 * Arn di 
 Clint, xi. 
 
 ">■•:■ 
 
 (i) We do not know how this was afcertained : Not by mixing water and ice furely ; becaufe that would 
 . taking for granted the thing to be proved ; becaufe it would give a very different refult ; and what is ftill worfe, 
 the fpecific caloric in that cafe would differ according to the temperature and the quantity of water. To give 
 an inftance : Mr Gadolln concludes, from 180 experiments made by mixing hot water and ice, that the fpecific 
 caloric of ice is to that of water only as I to 2 * ; and had he varied the quantities and the temperatures, he 
 might have obtained feveral other ratios.
 
 CHEMISTRY. 27» 
 
 furface ; a faft which has been long known, and which men bepran to think accurately on the fiibjeft, who con- Ca!onc. ^ 
 
 'has been employed in warm countries to diminilli the ctived the poffibihty of dcterminii)fj this queftion, was ^^^ 
 
 temperature of liquids, and even to convert them into Dr Irvine of Glafgow. He invented a theorem, in or- j^^-^,^^-^ 
 
 ice (k). That water is evaporated by uniting witli ca- der to afcertain the real zero, whicli has, we know not tlicorcin to 
 
 loric, and not by folution in air, has been proved very for what realbn, been afcribed by feveral writers to Mr Jiftovcr it. 
 
 completely by De Luc in his Treatife on Meteorology. Kirwan. He took it for granted (and the fad is Jiro- 
 
 The evaporation of alcohol, ether, and every other ved by all the experiments liitherto made) that the Ipe- 
 fubltance 'on which experiments have been made, has ciiic caloric of bodies continued the fame in evci7 de- 
 been found owing to the fame caufe. Bodies, there- gree of temperature, as long as they remained in the 
 fore, are converted into vapour by uniting with caloric, fame ftate, that is to fay, as long as they continued ei- 
 
 8. If caloric, as has been (hewn, exiils in bodies at ther folid or fluid or in a (late of vapour; but that the 
 
 the lowe ft temperature which we are able to procure, fpecific caloric of the fame body while folid was lefs 
 
 and if it exifts in them while the thermometer cannot than while fluid, and lefs while fluid than while in a 
 
 difcover its prcfence— is there any method of afcertain- ilate of vapour. He took it for granted, too, that the 
 
 ing its abfolute quantity in bodies ? At what degree 140 degrees of caloric which ei.lered ice during its fo- 
 
 would a thermometer Hand (fuppofmg the thermome- lution without raifing its temperature, entered merely 
 
 ter capable of meafuring fo low) were tlie body to which In confequence of the increafed fpecitic caloric of the 
 
 it is applied totally deprived of caloric ? or what degree water, and that they were exaftly proportional to this 
 
 of the thermometer correfponds to tiie reil zero ? increafed fpecific caloric. He took it for granted, like- 
 
 The firft perfou (as far as we know), at leaft fince wife, that the fpecific calorie of bodies was proportional 
 
 to 
 
 * _^ . 
 
 ' (k) Galen informs us, that the ancient Egyptians were accuflomed to put water prcvioudy boiled mto earthen 
 jars, and expofe them all night on the upper part of their houfes to the air. Before funrife thefe veffels were put 
 into the ground, moiftened on the outfidc with water, and then furrounded with frelh plants ; by which means the' 
 water was preferved cool during the whole day. Comment, in lib. vi. Hippoc. de morbis vulgar. 4. 10. p. 396. 
 
 By a fimilar procefs, water, in the Eall Indies, is converted into ice. 
 
 The following fmgular pafiage, which has been pointed out to us by the ingenious Dr Barclay, Itfturer 011 
 anatomy in Edinburgh, furnilhes a llriking proof that the ancients were led, by a very different method of- 
 rcafoning, to deduce, from their philofophical theory of the four elements, conclufions concerning the nature of 
 heat not very different from thofe of the moderns. _( 
 
 " Sic enim res fe habet, ut omnia, quae alantur et qua: crefcant, contineant in fe vim caloris ; fine qua nequt: 
 ali portent nee crefcere. Nam omne, quod eft calidum et igneum, cietur et agitur motu fuo : quod autem alitur 
 9t crefcit, motu quodam utitur certo et -.equabili ; qui quandiu remanet in nobis, tamdiu ienfus et vita remanet : ■ 
 refrigerato autem et extinfto calore, occidimus ipli et exftinguimur. Quod qnidem Cleanthes his etiain argu- 
 mentis docet, quanta vis infit caloris in omni corpore : negat enim ullum elfe cibum tarn graveni, quiu is node 
 et die concoquatur ; cujus etiam in reliquiis ineft calor his quas natura refpuerit. Jam vero vena; et arteria rni- 
 care non definunt, quafi quodam igneo motu ; animadverfunique faepe eft, cum cor animantis alicnjus evoUura ita 
 niobiliter palpitaret, ut imitarctur igneain celeritatem. Omne igitur quod vivit, five animal five terra editum, id"- 
 vivit propter inclufum in eo calorem. Ex quo intellcgi debet, earn caloris naturam, vim habere in fe vitalem per 
 omnem mundum pcrtinentem. Atque id facillus ccrnemus, toto genere hoc igneo, quod tranat omnia, fubtilius- 
 e-xplicato. ■ Omnes igitur partes mundi (tangam autem maxumas) calore full se fuftinentur. Quod primiim in • 
 terrena natura perfpici poteft. Nam et lupidum conflidlu atque tritu. elici ignem videmus ; et recenti foiujne 
 
 terram fumare cahnlem ; 
 
 atque etIam ex puteis jugibus aquam calldam trahi, et id maxume fieri teinporilnis liiberni?, quod magna vis ca-- 
 loris, terra; contineatur cavernis ; eaque hienie fit denfior ; ub eamque cauftam, caloreni infitum in terns cjatinean 
 
 arftius. ... ■ r- 
 
 " Longa eft oratio, multa;que rationcs, quibus doceri poffit, omnia, qua; terra conclpiat, fcmina, quxque ipfa ex • 
 fe generala ftirpibus infixa contineat, ea temperatione caloris et oriri et augefcere. Atque aqus eliam admixtu.|i 
 cfle calorem, primum ipfe liquor, tum aqua declarat efFulio : quss neque conglaciaret frigonbus, ncque nive prui- 
 naque concrefceret, nifi eadem fe admixto calore liquefatla et dilapfa difFandeiet. Itaque et aquilonibus i-elKpiif- 
 
 -_rporibus continget, cum motu atqu . . 
 
 miiiime eft expers caloris. llle vero et rniilto quldem calore admixtus eft : ipfe enim oritur ex refpiratione aqua- 
 rum : earum enim quali vapor quidam aer hatendus eft. Is autem exiftit motu ejus caloris, qui aqais coutinetur. • 
 Quam fimilitudiiiem cernere poffumus in his aquis, qua; effervefcunt fubditis ignibus. _ Jam_ vera rcl.<i'ja quarta 
 pars mundi, ea et ipfa lota natura fervida eft, et ceteris naturis omnibus falutarcm Inpertit et vitalem calorem. 
 Ex quo concluditur, cum omnes mundi partes fuftineantur calore, mandum etiam iplum liniili paiique iialura 111 
 tanta diuturnitate fervari : eoque magis, quod iutellegi debet, cahdum illud atque igneum ita 111 oniui fufuui efle , 
 natura, ut in eo infit procreandi vis et cauffa gignendi, a quo et animantia omnia, et ea quorum ftirpes terra eta- - 
 tinentur, et nafci fit necefle et augefcere. Cicero de natura Desrum, lib. i;. c. 9 et ic.
 
 272 C H E M I 
 
 Calorie, to thtir alfolute caJofie, or to all the caloric which exill- 
 •''"" ed in each. 
 
 On thefe data he reafoncd in the following manner : 
 Let A be a body in a Ibte of fluidity ; B the fame bo- 
 dy ill a ftate of folidity. If the fpecific caloric of A and 
 of B be known, and if it be known how many degrees 
 the caloric, difengaged during the change of B into A, 
 would raife the temperature of A, it may be found by 
 an eafy procefs how many degrees all the caloric con- 
 tained in B would raife the temperature of A ; and the 
 fura of thefe two numbers will reprefcnt in degrees the 
 whole quantity of caloric in A : for the quantity of 
 caloric in A mufl. be juft equal to the caloric in B, to- 
 gether with what entered into it in palTing from the 
 fiate of B to that of A. Let the fpecific caloric of A 
 be 6, that of B i ; and let the quantity of caloric dil- 
 engaged during the change of A into B be fufiicient to 
 raife the temperature of A 500°. If the fpecific calo- 
 ric be proportiond to the abfolute caloric, it muft. con- 
 tain exaftly 6 times as much caloric as B. The 500° 
 which entered into A when it changed its ftate, muft 
 be jull 5 times as great as all the caloric of B ; becaufe 
 when added to the caloric of B, it formed the caloric 
 in A, which is juft 6 times as great as the caloric in B. 
 Therefore to difcover the caloric in B, we have only to 
 divide 500 by 5, or, which is the fame thing, to ftate 
 •this proportion 6 — I : 500 : : I : I CO. The calorici in 
 B, therefore, in this cafe is juft as much as would raife 
 the temperature of A 100°. Therefore, if to 100'^, the 
 caloric of B, be added 5co'',^caloric difengaged in the 
 paffage of A to B, this will give 600°, =: to all the ca- 
 loric in A. Therefore, in all cafes, the difference be- 
 tween the numbers expreffing the fpecific caloric of the 
 folid and fluid, is to the number expreffiag the fpecific 
 caloric of the folid, as the quantity of caloric difengaged 
 during the pafTage of the fluid into a folid is to the 
 quantity of caloric in the fluid. 
 
 Dr Crawford embraced this theorem ; and concluded, 
 from a number of experiments made on purpofe to af- 
 certain the faft, that the real zero was 1 268'^ below o, 
 i;3 or 1300^ below the freezing point. 
 Siamined, This fubjeft defcrves to be confidered with attention. 
 If this theorem in fa£l furnifhes us with the real zero, 
 it is one of the moft important difcovcries which has 
 ever been made in chemiflry ; but if it proceeds on er. 
 roneous principles, it will only involve us in endlefs 
 mazes of error and abfnrdity. 
 
 In the firft place, if the real zeflp has any meaning 
 at all, it muft figniiy the degree to which tlie thermo- 
 meter (fuppofing it could be ufed) would fink on being 
 applied to a body which contained no heat. It muft 
 therefore be a fixed point ; and were the theorem 
 which we are examining well founded, experiments upon 
 every different fubftance, if conduced witii accuracy, 
 ■would lead to the fame refult. Let us fee whether this 
 be the cafe. 
 
 From Dr Crawford's experiments, it follows, as we 
 have feen, that the real zero is 1268^' below o. 
 
 Mr Kirwan, from comparing the fpecific caloric of 
 water and ice, fixed the real zero at 1048° below o. 
 
 From the experiments of Lavoifier and La Place on 
 a mixture of water and quicklime, in the proportion of 
 9 to 16, it follows, that the real zero is 2736° below o. 
 
 From their experiments on a mixture of 4 parts of 
 fulphuric acid and 3 parts of water, it follows, that the 
 real zero, is 5803,4." below o. 
 
 S T 11 Y. Part 1. 
 
 Their experiments on a mixture of 4 parts of ful- Caloric, 
 phuric acid and 5 of water, place it at 2073,3' below o. *~~^ - ' 
 Their experiments on g\ parts of nitric acid and i of 
 
 lime, place it at ^_- — below 32°*. • See Se- 
 
 Thefe refults differ from one another fo enormoufly,,/t Cbim. vii. 
 and the laft of them, which makes the real zero a ne- 
 gative quantity, is fo abfurd, that they are alone fufiicient 
 to convince us that the data on which they are founded 
 arc not true. Should it be faid that their difference ia 
 not owing to any defcdl in the theorem, but to inac- 
 curacies in making the experiments — we anfwer, that 
 the theorem itfelf is founded on finu'lar experiments ; 
 and if experiments of thfe nature, even in the hands of 
 the moft accurate chemills, cannot be freed from fuch 
 enormous errors, how can we depend on any confe- 
 quences deduced from them ? and where, then, is our 
 evidence for the truth of the theorem ? 
 
 But, farther, there is no proof whatever that the 
 fpecific caloric of bodies is proportional to their abfo- 
 lute caloric. The fpecific caloric of iron is greater than 
 that of water, or even azotic gas ; yet furely it is very 
 improbable that iron contains more abfolute caloric than 
 cither of thefe fubftances. 
 
 If the fpecific caloric of bodies has any meaning at 
 all, it can only be, that the fame quantity of caloric 
 raifes the temperature of one body a greater number of 
 degrees than it does another. When we fay that the 
 fpecific caloric of A is =: 6, and that of B = i, what 
 do we mean, unlcfs that the quantity of caloric which 
 raifes B 6' raifes A only 1'', or that what raifes B 60" 
 or 600", raifes A only 10° or ico"? When we fay that 
 the fpecific caloric of water is 10, and that of ice 9, do 
 we not mean, that tlie quantity of caloric which raifes 
 the ice lo" or 100", raifes water only 9° or 90°? Yet 
 during the change of ice into water, 140° of caloric en- 
 ter it without ralfing its temperature; a quantity greater 
 than what can be accounted for by the difference of 
 fpecific caloric by 126". The quantity that difappears, 
 therefore, is not proportional to the difference of fpeci- 
 fic caloric ; and therefore any theory which depends 
 on that fuppofitlon cannot be well founded. When 
 water is converted into fleam, 8oD° of caloric difappear, 
 yet the fpecific caloric of fteam is to that of water, ac- 
 cording to Dr Crawford's own experiments, only as 
 I ?5 to 100: fo thnt no lefs than 283" difappear, which 
 cannot be accounted for according to this theory. 
 
 Dr Irvine's theorem, therefore, is infufficlent for af-And f^und 
 certalning the real zero ; and hitherto no method hasinfuffiusnt. 
 been difcovered which can folve this problem. 
 
 9. If there be no body without caloric, if it exifts incaloncei- 
 dlflferent quantities in different bodies, even when their iits in bo- 
 temperatures are the fame, and while the thermometer"'" 
 cannot indicate its prefence — in what ftate does it exift 
 in them? We cannot furely fuppofe that it is contained 
 by them juft as water Is contained by a veffel of wood 
 or metal, or that they are filled with it in the fame 
 manner that a hollow globe of tinplate perforated with 
 holes is filled with water when it is plunged into a 
 quantity of that liquid ; or that bodies arc filled with 
 caloric merely becaufe they are immerfed in an ocean of 
 caloric. Were that the cafe, the fpecific and abfolute 
 caloric of bodies would always be proportional ; and 
 they would of neceflity be inverfely as the fpecific gra- 
 vity of the refpeftive bodies ; becaufe the lefs the fpeci- 
 fic gravity, the more room would be left for the par- 
 ticles 
 
 a74
 
 it(> 
 
 C H E M 
 
 ticks of caloric. But this is by no means the cafe : 
 the fpecific gravity of iron, for inflance, is greater than 
 that of tin, yet the fpecilic caloric of iron is more than 
 double that of tin : the fpecific gravity of oxygen gas 
 is greater than that of common air, yet the fpecilic ca- 
 loric of the tird of tlieft fnbftances is more than three 
 times as great as tliat of the other. There mull be 
 fomething, therefore, in bodies themfelvcs quite diffe- 
 rent from, and unconnefted with, the vacuities between 
 their particles, which dilpoies fome to admit more calo- 
 ric than others. And what can that be but a difpofi- 
 tion in diSerent bodies to unite with a greater or a 
 fmallcr quantity of caloric, and to retain it with more 
 or lefs fnmnefs according to their ajfinity for it ? Dr 
 Black pointed out, long ago, by diicovering latent heat, 
 that caloric unites with bodies ; and this feenis to be 
 the only real key for unfolding the aftions of this ex- 
 traordinary fubftance. If caloric be matter, can it be 
 deilitute of that property which all other matter poi- 
 In aftatpoffefles, we mean attraftion? And if it poflcd'es attradllon, 
 chemical rnuft it not combine with thofe bodies that attraft it 
 combina. jyj^ g^ other bodies combine with each other I Mull 
 there not be formed a chemical uin'on between caloric 
 and other fubftances, which can only be broken by che- 
 mical means, by prefenting a third body which has a 
 greater affinity either for the caloric or the body to 
 j,._ which it is united, than they have for each other ? 
 Proved to That it unites chemically with fome bodies, at lead, 
 te the cafe cannot be doubted, as we have flicwn already, that when- 
 in liquids, gy^j. ^ {q\\^ Js converted into a liquid, a quantity of ca- 
 '' loric enters, and remains in it ; and that both the folld 
 and the caloric lofe their charafteriflic properties. This 
 is prccilcly what takes place in every chemical union. 
 All liquids, therefore, confift of folids combined with 
 caloric. We have feen, too, that liquids are converted 
 into vapours by the very fame prucefs. There are there- 
 fore, atlcaft, two very large clafTes of bodies, liquids and 
 vapours, in which we are certain that caloric ex ills in a 
 J73 ilate of chemical combination. 
 Audgtfcs; There is another clafs of bodies which refembles va- 
 pours in almoft all their properties: thefe are the gales. 
 Ijike them, they are invifible and elallic, and capable 
 of indefinite expanfion. Is it not probable, then, that 
 . the gafes alfo, as well as the vapours, owe their proper- 
 tits to caloric ? that they alfo confift of their lefpedtive 
 bafes combined with that fubtlle fubftance i' This pro- 
 bability has been reduced to certainty by an experiment 
 of Lavoilier. By adding two tubes to the calorimeter 
 formerly defcribed, he contrived to make known quan- 
 tities ot air to pafs through the interior cavity, and to 
 fupport combullion. He found, that when a pound 
 of oxygen gas was made to combine in this manner 
 with phofpluirns, as much caloric was difengaged as 
 melted S^-J- pounds of ice*. Now every pound of ice 
 abforbs as much caloric in the aft of melting as is fuf- 
 ficient to raife a pound of water 140". Therefore the 
 whole caloric difengaged was fufficient to raife a pound 
 of water 12250°. AH this could not have come from 
 the phofphorus, becaufe it had been converted into a 
 liquid, and mufl; therefore have abforbed inltead of part- 
 ed with caloric, and becaufe the quantity of caloric dif- 
 engaged in all cafes of combuftion is proportional, not 
 to the combuftible,,but to the oxygen abforbed. Oxy- 
 gen gas, then, is compofcd of oxygen and caloric : and 
 if this be the cafe with one gas, why not with all ? 
 SupPL. Vol. I. Part I. 
 
 I S T R Y. 
 
 273 
 
 * Lartrficr. 
 f . i. ch. tj. 
 
 We may conclude, therefore, that the gafes, as well Ciltxic. 
 as liquids and vapours, owe their form, to the caloric "-"-V"^ 
 which they contain. The only difference between thenx 
 and vapours is, that the latter return to their liquid 
 ftate by the mere aftion of cold ; whereas mofl of the 
 gafes refift the loweft tenqierature which it has been 
 jtofhble to apply. It was natural to expccl, that if ca- 
 loric combined clieinitally with bodies, its af6 lity would 
 be difterent for dillerent fubftances, and that its affinity 
 for fome bodies would be fo great that it would not leave 
 them to combine with any other. It was natural to ex- 
 pcct this, becaufe it is the cafe with every other fubftance 
 with which we are acquainted. The difference, then, 
 between the gafes and vapours is not furprifing. The 
 affinity of the former for caloric is not only much greiit- 
 er than that of the latter, but much greater than that of 
 any other fubftances. 
 
 It is owing to this flrong affinity between oxygen, And't' be 
 hydrogen, and azot and caloric, that they cannot be the caufe i.f 
 obtained except in a gafeous form : and we (hall dcfcribe 'htir gafc- 
 feveral other fubftances afterwards exaftly in the fame """^ '^'^""' 
 circumllances. Had we any fubftance pofTeftVd of a 
 greater affinity for caloric than they have, we fhould be 
 able, by prefenting it, to deprive them of their gafeous 
 form. Doubtlefs there is a difference in the affinity 
 between thefe bodies themfelves and caloric ; but as all 
 of them are already faturated, this difference cannot be 
 difcovered. If we could obtain them uncombined with 
 caloric, that is to fay, in a concrete ftate, it would be 
 eafy to afcertain this point. Suppofe, for inftance, that 
 hydrogen had the ftrongeft affinity for caloric, and that 
 we poiTeffed it in a concrete Hate — it would be eafy, by 
 prelcntiiig it to the other gafes, to deprive their bafes 
 of the caloric with which they are united, and thus to 
 obtain them alfo uncombined with any other fubftance. 
 
 But though we are acquainted with no fubftance that Wiiy calo. 
 has a greater affinity for caloric than the bafes of the r.c appeari 
 gafes, there are many fubftances which have a greater '''"■'"& 
 affinity for thefe bales than caloric has. When any ""'^""'°"' 
 fuch fubftance is prefented, the bafe combines with it, 
 and the caloric is left at liberty. Thus, when phofpho- 
 rus is prefented to oxygen gas, the phofphorus and oxy- 
 gen unite together, and the caloric flies off. We are 
 now, therefore, able to anfwer one of the queflions pro- 
 pofed at tlie end of the fecond chapter, Wlience comes 
 the calo;lc which appears during combuftion ? It is fe- 
 parated from the oxygen, which leaves it in order to en- 
 ter into a new combination. o 
 
 The caloric alfo, which fometimes appears when two .An.1 during 
 bodies combine together, is let at liberty exaftly in the "'^"7 'he- 
 fame manner. When fulphuric acid and water, for in-T'"^*'. '^'""* 
 fiance, are mixed together, a very confiderable heat is "'^"°°'* 
 produced ; a good deal of caloric, therefore, becomes 
 ienfible. In this cafe, the water combines with the 
 acid, and at the fame time lets go the caloric with 
 which it was formerly combined, and becomes dcnfer. 
 In the fame manner, to give another inllance, when 
 water is poured upon quicklime, a very great quantity 
 of caloric becomes manifeft. The water in this cafe 
 combines with the quicklime, and alfumes a concrete 
 form, and of courfe lets go the caloric with which it 
 was previoufly united. „ 
 
 10. It is no uncommon thing in nature to obferve Why ccr- 
 two bodies, after combining together, manifefting a '•''■1 mix- 
 much ftronger affinity for a third body than either of '""^^P^"" 
 M m them
 
 74 
 
 Caloric. 
 
 C H E M I 
 
 tlicni liad while fcparate. Thus, filver has no percep- 
 tible afiiiity for fulphuric acid, ncitlier has iixygeii ; 
 but unite them together, and they combine with that 
 acid vcrv readily. A great many inilances of llie lame 
 kind migiit be produced. Were there fubftances, tlien, 
 which, after combining together, have a greater affinity 
 for caloric than any of tliein had while feparate, this 
 ought not to furprife us, hccaufe the fame phenomenon 
 is often obferved in other bodies. Now this is aftually 
 the cafe with regard to caloric. Mix together, for in- 
 Aance, common fait and fnow, the mixture inftantly be- 
 comes liquid, and fo cold, that it finks the thermometer 
 down to zero. In this cafe, the fnow and fait united 
 have a much ftro?iger affinity for caloric than either of 
 them had while feparate ; they attraft it therefore from 
 other bodies with which they happen to be in conta6t, 
 till they have obtained a dofe fufncient for their fatura- 
 tion ; and thisfaturationthey nianifcit by becoming liquid. 
 It is for this reafon that all falls produce cold during their 
 folution in water, when the freezing point of the folution 
 formed is below that of water. All fuch folutions have 
 a ilrong affinity for caloric ; they therefore attraft it till 
 they are faturated, which appears by their becoming 
 fluid. A number of experiments have been lately made 
 in order to procure artificial cold bv means of fuch 
 cfiinbinations. The moil complete ftt of experiments 
 of that nature with which V!t are acquainted, is thofe 
 of Mr Walker, publifhed in the Philofophical Tranf- 
 aftions for 179;. We rtiall prefent the reiult of his 
 experiments in the following Table : 
 
 T/iBiE 0/ Freizing Mixtures. 
 
 S T R Y. 
 
 Mixtures. 
 
 Thermometer finlc. 
 
 Muriat of ammonia 5 parts. 
 Nitre - 5 
 Water - - 16 
 
 From 50° to ]o". 
 
 Muriat of ammonia 5 
 Nitre - - 5 
 Sulphat of foda 8 
 Water - - 16 
 
 From JO to 4. 
 
 Nitrat of ammonia i 
 Water - - i 
 
 From 50 to 4. 
 
 Nitrat of ammonia I 
 Carbonat of foda i 
 Water - - i 
 
 From 50 to 7. 
 
 Sulphat of foda 3 
 Diluted nitric acid 2 
 
 From 50 to 3. 
 
 Sulphat of foda 6 
 Muriat of ammonia 4 
 Nitre - - 2 
 Diluted nitric acid 4 
 
 From 50 to 10. 
 
 Sulphat of foda 6 
 Nitrat of ammonia 5 
 Diluted nitric acid 4 
 
 From 50 to 14. 
 
 Phofphat of foda 9 
 Diluted nitric acid 4 
 
 From 50 to 12. 
 
 Mixtures. 
 
 Tlierniometcr Onks. 
 
 Phofphat of foda 9 parts. 
 Nitrat of ammonia 6 
 Diluted nitric acid 4 
 
 From 50° to 21°. 
 
 Sulphat of foda 8 
 Muriatic acid - 5 
 
 From 50 to 0. 
 
 Sulphat of foda 5 
 Diluted fulphuric acid 4 
 
 From 50 to 3. 
 
 Snow - - 1 
 Common fait - 1 
 
 From 32 to c. 
 
 Snow or pounded ice 2 
 Common fait - i 
 
 From to — J. 
 
 Snow or poimded ice i 
 Common fait - 5 
 Muriat of ammonia and 
 Nitre - - 5 
 
 From — 5 to — 18. 
 
 Snow or pounded ice 1 2 
 Common fait - 5 
 Nitrat of ammonia 5 
 
 From — 1 8 to — 25 . 
 
 Snow and diluted nitric acid 
 
 From to — 46. 
 
 Snow - - 2 
 Diluted fulphuric acid 1 
 Diluted nitric acid i 
 
 From — 10 to — 56. 
 
 Snow - - I 
 Diluted fulphuric acid i 
 
 From 20 to — 60. 
 
 Part I. 
 
 Caloric. 
 
 In order to produce thefe effefts, the falts employed 
 muil be frefh cryftallized, and newly reduced to a very 
 fine powder. The velfels in which the freezing mix- 
 ture is made fhould be very thin, and juft large enough 
 to hold it, and the materials fhould be mixed together 
 as quickly as poffible. The materials to be employed 
 in order to produce great cold ought to be firft redu- 
 ced to the temperature marked in the table, by placing 
 them in (ome of the other freezing mixtures ; and then 
 tliey are to be mixed together in a fimilar freezing mix- 
 ture. If, for inflance, we wifh to produce a cold 
 =: — 46, the fnow and diluted nitric acid ought to be 
 tooled down to o, by putting the veffel which contains 
 each of them into the 12th freezing mixture in the 
 above table, before they are mixed together. If a flill 
 greater cold is required, the materials to produce it are 
 to be brought to the proper temperature by being pre- 
 viouflv placed in the fecond freezing mixture. This 
 proceis is to be continued till the required degree of 
 cold has been procured *. ^ 7r«...-r 
 
 1 1. From the fafts already known, we may conclude,/"/,//, Traiif; 
 that the particles of caloric have two properties, that 1 795- 
 of repelling each other, and of attrafting and being at- ^^^ 
 tradled by other fubftances. As there is no body in„],j^f,(.(,5, 
 nature which does not contain caloric, we may fafely tain mod 
 conclude, that there is no body in nature which has notca'oric. 
 an affinity for it. When it unites with bodies, though 
 the repulfion of its particles may be overcome by their 
 attraction for the particles of the body, and by the at- 
 
 traftion 
 
 alltr,
 
 Part r. C H E M 
 
 Caloric, traction of tlielo particles for each other — we cannot 
 '— ■>"— ' fuppofe it anniliilated : It mull; therefore be the more 
 powerful the greater the quantity of caloric combined 
 in any body is. Probably, then, there is mod caloric 
 combined with fjafes, lefs with fluids, and leall with lo- 
 lids. It does not follow, however, from this, that the 
 quantity of caloric combiiied with any body is propor- 
 tional to the diftance between its particles, becaufe that 
 may depend on other caules. Thus, though hydrogen 
 jjas is much rarer than oxygen gas, it does not ioliow 
 that hydrogen is combined with more caloric than oxy- 
 gen, becaufe the rarity may be owing to the fmall- 
 er cohefive force of the particles of hydrogen allow- 
 ing a fmaller quantity of caloric to produce a greater 
 effeft. 
 
 If caloric unites only chemically with bodies, there 
 ought to be a certain point of faturation between it and 
 
 CjI" 
 
 275 
 
 I S T R y. 
 
 feebler than that between oxygen atid caloric ; for the 
 new compound is eafily broken, and the caloric abfotbed 
 by many other fubllances. We can even conceive this 
 new compound ftill to have an affinity for caloric, to 
 unite with it, and to form another conipotind, the affi- 
 nity between the ingredients of which is ftill feebler. 
 And in this manner may the indefinite iiicreafe of tem- 
 perature be accounted for. 
 
 Kubftances may be conceived to be condviclors of ca- Caiife'if 
 loric inverfcly as their affinity for it. Good conduftorstli= riifTi- 
 may have very little affinity for caloric ; and for that '''"'.'°"* 
 rcafon it may be eafily hirced through them by the re-p"^^"*' f- 
 pullion of its own particles. But thofe fubllances different 
 which have a great affinity for caloric, combine with it bojie.". 
 the moment it is prefented to them ; and confequently 
 it cannot pafs through them. Thus, when it is pre-, 
 fented to ice, the affinity between the two fubflances is 
 
 ^%6 
 
 the fubftances with which it combines, becaufe this takes fo great, that the caloric unites with the very firft par- 
 place in all other chemical combinations. Oxygen gas, tides of ice which it meets with. The particles behind 
 
 thefe cannot receive any caloric, except by attrafling it 
 from the particles with which it has already coiiibincd. 
 But the affinity of one particle of ice for caloric cannot 
 be greater than that of another particle of ice: and the 
 union of two bodies cannot be broken by a force not 
 greater than that which unites them ; therefore the ca- 
 loric cannot pafs from one particle to another. Confe- 
 quently, fuppofing all the particles to keep their places, 
 no new caloric could enter. Juft as when a piece of 
 marble is put into fulphuric acid, the crutl of fulphat 
 of lime which very foon covers it prevents the acid from 
 getting to the particles of marble within. But as foon 
 as a particle of ice unites with caloric, water, the new 
 compound, leaves its ftation, and allows the caloric a 
 paffage to the other particles. 
 
 In the fame manner, wlien caloric 15 prefented to wa- 
 ter, it combines with the outermofl llratum of parti- 
 cles, and forms with them a compound which cannot 
 be decompofed by the other particles of the water, be- 
 caufe their affinity for caloric is no greater than that 
 of the particles already united with it. No more ca- 
 
 ior inftance, confills of a certain quantity of oxygen 
 united with caloric. Now if this gas be a chtmical 
 compound, the two ingredients ought to faturate each 
 other in fuch a manner, that no more of either could be 
 admitted. But it cannot be denied, that more caloric 
 can ftill be added to oxygen gas, for its temperature 
 may be raifed at pleafure as high as we think proper. 
 This, at firil light, feems to be an infuperable objeftion 
 to the theory, that caloric only combines chemically 
 with bodies. It ought to be remembered, however, 
 that caloric is not fingul^r in this refpeft. There are 
 other bodies in nature, and bodies too which certainly 
 combine with other fubftances only by affinity, which 
 exhibit the very fame phenomenon. Water is capable 
 of combining with fulphuric acid and many other falts 
 almoft in any proportion, at leaft no limits have hither- 
 to been obierved. Oxygen, too, combines with almoft 
 ever)' body in various proportions : We have feen, that 
 with almoft every metal it forms at leall two dift'e- 
 fent oxides. Why then may not caloric be capable of 
 uniting in the fame manner? Allowing, therefore, that 
 
 it were impoffible to explain v^hy bodies are capable of loric, then, could gain admiffion, were it not that (the 
 
 combinintr with caloric after faturation, this could be 
 
 P ... 
 
 no objeflion to the theory that it only unites ctiemical- 
 
 iv with bodies, becauie the fame phenomenon is exhi- 
 bited by other bodies which it cannot be doubted com- 
 bine only by means of affinity. 
 
 The manner in which thefe other combinations are 
 formed has been already hinted, and (hall be conlidered 
 ■inore tnlly afterwards; at prefent we ihall only attempt 
 to explain the aftion of caloric. Let us fuppofe, then, 
 that caloric is prefented to oxygen; that they combine 
 together in a certain proportion, and latiirate each other. 
 The product of this combination is oxygen gas; a fub- 
 ilance polTelTed of properties very different from thofe 
 of caloric or oxygen in a concrete ftate ; it is incapable 
 of being decompoled by any merely mechanical method, 
 and exhibits all the appearances of a firaple fubilance. 
 Let us therefore coniider this compound tor a moment 
 as a fimple fubftance. May it not ftill have an affinity 
 for caloric? and will it not, in that cafe, unite with it ? 
 Oxygen gas and caloric have an affinity for each other; 
 accordingly when prefented to one another they combine 
 in a certain proportion, and form a new cotrpound, differ- 
 ing from oxygen gas, properly fo called, in elafticity, 
 fpecific gravity, and feveral other particulars. The af- 
 iinity, however, between oxygen gas and caloric h mucli 
 
 fpecific gravity of the new Compound being inferior to 
 that of the uncombined water) it immediately changes 
 its place, and allows another ftratum of particles to oc- 
 cupy its room. Thefe unite with caloric, and are dif- 
 placed in their turn. And in this manner the procefs 
 goes on, till all the particles have combined with calo- 
 ric ; or, which is the fame thing, til! the whole of the 
 water is heated. 
 
 But fuppofing the firft ftiatnm of particles to remain j, '^^ 
 in their place after their union with caloric, we can pj^^, .i*^^". 
 conceive an affinity ftill to fubfifl between the new com-foliJs. 
 pounil, thus formed, and caloric. In that cafe the 
 new compound, which we fliall call A, would com- 
 bine with an additional dole of caloric, and form a 
 fecond compound B, differing in fcvcral' refpefts from 
 the firft. We can conceive alio the affinity between 
 the firft compound A and caloric to be inferior to that 
 between water and caloric. In that cafe, the fecond 
 ftratum of particles of water would fepurate the addi- 
 tional dofe with which the hrll ftratum had united. In 
 this manner would two flratums of particles combine 
 with caloric. The firft ftratum of particles would com- 
 bine with another dofe of caloric, and form a fecond 
 compound B as before. But this ccnipound could not 
 now be decompofed by the fecond ftratum of particles, 
 M m 3 becaufe
 
 C H E M I 
 
 becaufe they had already uniwd with a dofe of caloric ; 
 and therefore their affinity for a new dofe louU be no 
 greater than that of the firft ftratuni of particles. The 
 procefs of heating could go on no farther. But we 
 can conceive the" fecond compound B, into which the 
 firil ftratum has entered, ilill to have an affinity for ca- 
 loric, to combine with a dofe of it, and to form with it 
 a third compound C. We can conceive, at the fame 
 time, the affinity between the fecond compound B and 
 caloric to be Icfs than that between the firft compound 
 A and caloric. In that cafe, the ftcond ftratum of par- 
 ticles would take thi« lall dofe from the firft ftratum, 
 and form with it a fecond compound B. The third 
 ftratum of panicles, which is ftill uncombined with ca- 
 loric, would now attraft this new dofe from the kcond 
 ftratum, and combine with it. And, fuppofing the ca- 
 loric ftill flowing towards the water, the firft ftratum 
 would again form the third compound C, by uniting 
 with a frefti dofe : this new dofe would be again at- 
 trafted by the fecond ftratum, and the firft ftratum 
 would again form the third compound C, by uniting 
 with another dofe of caloric. Thus three ftratums of 
 particles would be combined witli caloric; the firft ftra- 
 tum would contain three dofes, the fecond ftratum two, 
 nnd the third one. The procefs of heating would again 
 ftop ; becaufe now the affinity of the fecond ftratum is 
 no greater than that of the firft, nor the affinity of the 
 third ftratum greater than that of the fecond, nor that 
 of the fourth than that of the third. But we can con- 
 ceive an affinity ftill to fubfift between caloric and the 
 third compound C, into which the firft ftratum has en- 
 tered, and this affinity, at the fame time weaker than 
 that between the fecond compound B and caloric. In 
 that cafe they would combine and form a fourth com- 
 pound D. This new dofe would be attrafted by the 
 fecond ftratum of particles, which would combine with 
 it and form the third compound C ; the third ftratum 
 would attraft it from the fecond, and form with it the 
 fecond compound B ; and the fourth ftratum would at- 
 traft it from the third, and enter into the firft com- 
 pound A. The firft ftratum would again enter into 
 the fourth compound D ; which would be again de- 
 compofed by the fecond ftratum ; and the compound 
 formed by the fecond ftvatum, by the third ftratum. 
 The fourth compound D would be again formed by 
 the firft ftratum, and again decompofcd by tlie fecond 
 ftratum. It would be formed a third time, and could not 
 now be decompofed. Four ftratums of particles would 
 now have combined with caloric : the firft ftratum with 
 four dofes; the fecond, with three dofes; the third, with 
 two; and the fourth, with one. We can conceive this 
 procefs to go on exaflly in the fame manner, till all the 
 particles of water have combined with a dofe of caloric. 
 In that cafe, the quantity of caloric combined with 
 cverj- ftratum of particles would form a regular decrea- 
 fing feries from that part of the water at which the ca- 
 loric enters to that part which is fartheft diftant from 
 it. The procefs of heating would go on very llowly ; 
 and the heat of that part of the water which is far- 
 theft diftant from the fource of caloric could never be 
 nearly equal to that of the part which is neareft to that 
 fource. This feems in faiSt to be the manner in which 
 all thofe folids are heated which are bad conduftors of 
 caloric : in all probability it is the way in which all fo- 
 lids are heated. 
 
 S T R Y. Part I. 
 
 That caloric combines with bodies merely by means Caloric. 
 of affinity, feems at firft fight contrary to fa£l ; for '~~^r~~^ 
 there is no fubftance whatever v/hich may not be cooled go ^j^ji-o^; 
 indefinitely merely by furrounding it with other bodieseaeh other 
 which are colder than itfelf. Place a piece of hot iron,'ecipiucal. 
 for inftance, in cold water, it is very foon cooled down'''' 
 to the temperature of that liquid. This feems plain 
 enough ; the attra£lion of water for caloric is greater 
 tiian that of iron : but reverfe the experiment ; put 
 liot water within cold iron, and the water is cooled in 
 its turn down to the temperature of the iron : fo that 
 the iron alfo has a greater affinity for caloric, as well as 
 the water; which is abfuid. ^Sg 
 
 But it ought to be remembered, that caloric not on- And why, 
 ly poftcflls affinity, but that it has another property al- 
 fo, of which every other fpecies of matter, except per- 
 haps light, feems to be deftitute, a repulfion between 
 its own particles. It is neceflary for all organifed 
 bodies, and probably for all bodies, that they Ihould 
 poffefs a certain quantity of caloric ; and on this ac- 
 count the greatett care has been taken to fecure its 
 equal diftribution. This feems to be one ufc at leaft of 
 its rcpulfive power ; a power which is never dtftroyed, 
 however clofcly caloric is united with other bodies. We 
 have fhewn already, that this power is increafed by di- 
 minifhing the quantity of furrounding caloric ; and 
 when thus increafed to a certain degree, it may at laft 
 equal, and even exceed, the affinity between the caloric 
 and the bodies to which it is united ; and in that cafe 
 part of the caloric would neceflarily fly off. It feems 
 to be in this manner that bodies reciprocally cool each 
 other, and that they have always a tendency to an equi- 
 librium of temperature. Thus fteam by cold is con- 
 verted into water, and water into ice. And the affini- 
 ty between bodies and that caloric which is employed 
 in regulating the temperature feems to be fo weak, that 
 the repulfion between the particles of caloric eafily over- 
 comes it, and reftores the equilibrium. But the affini- 
 ty between feme fubftances and caloric is fo great, that 
 no diminution of temperature has been found fufficient 
 to overcome it. This is the cafe, as we have already 
 ften, with oxygen gas. 
 
 The fpecific caloric of bodies feems to depend on Caufe of 
 two things ; their affinity for caloric, and the diftancet' t dific- 
 between their particles. For vi'hat is temperature but "^^"^ '" _^ 
 the dli'pofition of a body to part with caloric? ^^he ^.^Jq^ -^ ^j ' 
 more caloric a body is difpofed to part with, we call itsbodies. 
 temperature the higher ; the lefs it parts with when a 
 colder body is applied, its temperature is laid to be the 
 lower. If oxygen gas parts with no caloric to a ther- 
 mometer which ftands at — io°, we fay its temperature 
 is — 10 ; yet we know that even then it contains, in all 
 probability, much more caloric than the mercury in the 
 thermometer does. Now the rtronger the affinity be- 
 tween any fubftance and caloric, the greater quantity 
 of caloric will be required before the repulfion between 
 its particles is fufficient to overcom.e this attraftion ; 
 confequently the more caloric is neceflary to raife it a 
 given number of degrees. And the farther diftant the 
 particles of bodies are, the farther from one another 
 muft the particles of caloric be to which they are united; 
 and confequently the weaker muft be the repulfion be- 
 tween them. 
 
 We cannot deny how new this theory of the aftion 
 of caloric will appear to thofe who have been accuftom- 
 
 ed 
 
 I 
 
 290
 
 Parti. CHEMISTRY. 277 
 
 Calor c. ed to look Upon Dr Craw ford's opinions on this fubjed of the oxygen, and, without any of the ufiial phenome- ^ Caloric. ^ 
 ^— ~v— ^ as fully proved ; nor do we pretend that it can be re- na which attend combiiftiow, is converted into phofpho- » 
 coiitiltd with thefe opinions. But this, we hope, is ric acid. StriAly fpeaking, then, combuilion is nothing 
 no proof of its fallehood. We think it can be fairly elfe but the combination of oxygen with the burning 
 ueduced from Dr Black's dodrine of latent heat : we body, and the term might therefore be ufcd in every cafe 
 know, too, that Bergman believed caloric capable of where fuch an union takes place; and in this fenfe indeed ,^4 
 combining chemically with bodies: and Morveau has it is now cnipluycd by feveral writers. But the term Whether it 
 not only embraced the fame opinion, but feems to af- cumliijllon h in common language confined to t'^"''-' "•^^s^^^''^'^^^^"-^'^ 
 firm, that all the combinations into which caloric en- where the oxygen was previoufly combined with calo- ^^^^g^.^ j, 
 » F.n:\!. ters are chemical *. And were this quellion to be de- ric, and where a quantity of heat and light btcome fen- not ptefent. 
 JMrfio./. cided by authority, we appeal to all the world, whether fible ; and perhaps it would be better, in order to pre- 
 ^'":'!'''' other three men could be produced to whofe decilions vent ambiguity, never to employ it in any other fenfe. 
 4ff,.iu: ^^^^ ^vould more willingly fubniit { 1 ). We do not, how- We are not yet abfolutely certain that caloric and light 
 ever, mean to reft its evidence on authority ; let it be may not become fenfible in other combinations befides 
 compared with fads, and put to the tell of experiment ; thoi'e into which oxygen enters. There are other fub- 
 and by its correfpondence with theic let it Hand or fall, ftances befides oxygen capable of combining with calo- 
 "^V . 12. Caloric both hallens the folution of falts in wa- ric ; for inftance, hydrogen and azot : and unlcfs their 
 flens'folu!' ter, and increafes the folvent power of the water ; for affinity for caloric be greater than foi; any other fub- 
 tion'and water diifolves a much greater quantity of alnioft every ftance, they may be capable of combining with other 
 ircreafes {alt when hot than when cold. The reafon that calo- fubftances, and Separating from caloric, at leaft the im- 
 the folvent ^.j^ produces thefe effei^is is obvious from thofe proper- poflibilily of this has never yet been demonftrated. It 
 P°*" ties of it which have been defcribed. It hallens folu- is improper, therefore, to appropriate the word comhuf- 
 tion by putting the panicles of the fluid in motion, and t'lon to the combinations of oxygen, till it can be fliewti 
 thus bringing all of them in their turn into contaft with that the phenomena ufually denoted by that name are 
 the fait : for only thofe particles can aCt as folvents never owing to any other caufe. Tliere is even one 
 which are in contad with the fak. It increafes the fol- cafe in which thefe phenomena prefent themfelves, in 
 vent power of the fluid by combining with it, and form- which we are next to certain tliat oxygen has no (liare. 
 ing a compound which has a greater affinity for the fait. There is an affinity between fulphur and iron, and a 
 and which therefore dllTolves more of it than the fluid high temperature promotes their union. When thefe 
 alone woidd have done. This new compound is de- fubllances are mixed together, and heated till they juft 
 ftroyed by cooling ; and then the additional dofe of the begin to appear red hot, they combine together, and 
 fait which had been diflblved is precipitated. at the fame time, as the Dutch cheniifts firlt obferved, 
 13. We Ihould come now to the confideration of the a good deal of caloric and light is evolved. _ The very 
 tworemainingqueftionspropofed atthcendofthe fecond fame phenomena appear in a vacuum, or in any kind 
 chapter. Why do bodies combine with oxygen at one of air whatever. The explanation of them is very 
 temperature and not at another I And why is caloric fimple and obvious. The fulphur or the iron, or per- 
 necelfary to produce this union ? But as the difficulty haps both, had previoufly been combined with a quan- 
 of thefe queftions is not inferior to their importance, tity of caloric ; and when they united together, this ca- 
 we thall delay any attempt to anfwer them till we come loric of courfe feparated from them. _ jqj 
 191 to treat of a^wi/^)/. The theory of combuftion adopted by the earlier Stahl's ihe- 
 Metlii>dsof i^.. It now only remains to confider the methods by chemifts was very different from the preceding, '^'^'^j'l' J^^,^i^„'^^y ' 
 obtaining which caloric may be obtained in a fenfible ftate. Thefe as has been already explained, confidered combuftion ^i^^ ^^,^1^^. 
 caloric. methods may be reduced to four; combuftion, percuf- in every inftance as owing to the feparation of phlogil-tion.ifphlo- 
 fion, fridion, and light : the laft of which ftiall be con- ton ; and this opinion foon became univerfal. He con-gidon. 
 fidered afterwards. fidered phlogifton as the fame thing with the element 
 Gornbuf- We have feen already, that the combuftion oi fimple of fire ; which was capable both of becoming fixed in 
 tion en- combujliblcs and mdah \s merely their combination with bodies, and of exifting iii^ a ftate of liberty. Two of 
 plained. oxygen, during which the oxygen parts with the calo- its properties in this lall ftate were heat and light. The 
 ric with which it was formerly united. Now the very heat and the light, then, which became fenfible during 
 fame thing takes place in other combuftions. The com- combuftion, were nothing clle, according to Stahl, but 
 burtible unites with oxygen, which at tiie fame time two properties of phlogifton or the clement ot fire. j^^j 
 gives out its caloric. The change tiien which the Macquer, to whofe illullrious labours feveral of the moft Improved 
 combuftible body fufters is not owing to the adion of important branches of chemiftry owe their exiftence,!'/ Mac- 
 caloric on it, but to its combining with oxygen. The was, we believe, the fii 11 perfon who perceived a ftri-l"'""' 
 very fame change can be brought about without any of king defed in this theory ot Stahl. Sir Ifaac Newton 
 the ufual phenomena which attend combuftion, fimply had proved that light is a body ; it was abfurd, there- 
 by prefenting the oxygen combined with fome other fore, to make it a mere property of phlogifton or the 
 body inftead of caloric. Nitric acid, for inftance, is element of fire. Macquer accordingly confidered phlo- 
 a body v/hich contains in it a good deal of oxygen : gifton as nothing elfe but light fixed in bodies. This 
 If phofphorus be mixed with this acid, it attrads part opinion was embraced by a great number of the moft; 
 
 diftin- 
 
 (i) The fame opinion has been embraced by Seguin, Pidet, Gadolin, and feveral other philofophers. We . 
 did not mention them, becaule the theory given above differs in a few particulars from theirs. But we have de- 
 rived much inftrudion from their ingenious writings; and many of the fads which we have given were obtained 
 from them.
 
 278 
 
 Cik.tic. 
 
 1Q7 
 
 SPrieftley, 
 
 And Craw 
 ford. 
 
 399 
 Jf.irwan's 
 thenry of 
 fhlo^ifton 
 
 C H E M 1 
 
 diftinpjuifhed cliemifts ; and many ingenious arguments 
 were brought forward to prove its truth. But it phlo- 
 giltoM be o;ih' light fixed in bodies, whence coincs the 
 lieat that manitefts itklt during ci)mbullioi\ ? Is this 
 heat merely a property of light ? Dr Black proved 
 that heat is capable of combining witii, or becoming 
 fixed in bodies which are not conibullible, as in ice 
 and water ; and concluded of courfe, that it is not a 
 property but a body. From that time heat or caloric 
 was confidered by the greateft number of chemifts as a 
 iliibinCl Aibftance from phlogillon. 
 
 Soon after this, a phenomenon, which had been ob- 
 ferved from the earliell ages, and which probably, for 
 that very reafon, had been neglefted, began to be at- 
 tended to ; that combuHibles would not burn except in 
 contact with air. Dr Prieftlev obferved, that the air in 
 which combuftibles had been fuffered to burn till they 
 were extliiguilhed, had midergone a very remarkable 
 change ; for no conibullible would afterwards burn in 
 it, and no annimal could breathe it without fuffo- 
 cation (k). He concluded, as Dr Rutherford had done 
 before him, that this change was owing to phlogif- 
 ton ; that the air had combined with that fubllance ; 
 and that air was neceffary to combullion, by at- 
 trafting the phlogifton, for which it had a ftrong af- 
 finity. If fo, phlogifton could not be light any more 
 than caloric ; for if it feparated from the combuftible 
 merely by combining with air, it could not furely dif- 
 play itfelf in the form of light. The queftion then re- 
 curred with double force, What is phlogifton ? Dr 
 Crawford, of whole ingenious experlmcn'-s on the fpe- 
 cific caloric of bodies we have already given an account, 
 w ithout attempting to anfwer this queftion, made a con- 
 fiderable improvement in the theory of combuftion, by 
 fuppofing that the phlogifton of the combuftible com- 
 bined with the air, and at the fame time feparated the 
 caloric and light with which that fluid had been previ- 
 oufly united. The heat and the light, then, which 
 appeared during combuftion, exifted previoufly in the 
 air. This theory was very different from Stahl's, and 
 certainly a great deal more fatisfadory. But ftill 
 the queftion. What is phlogifton ? remained to be an- 
 fwered. Mr Kirwan, who had already raifed himfelf 
 to the firft rank among chemical phllofophers by many 
 
 S T R Y. Part I. 
 
 important difcoveries, and many ingenious Inveftlga- Caloric, 
 tions or iome of the moll difficult parts of chcnn'llry, 't ' 
 
 attempted to anfwer this queftion, and to prove that 
 phlogifton was the fame with hydrogen*. The fub-* In hN 
 icft was now brought to a ftate capable of the molt /'"'■'' '^ 
 complete decilion. Does hydrogen actually exilt ui all J^ 
 combuftible fubllances ? and is it feparated from, them Refuted, 
 during every combuftion ? The French chemifts who 
 anfwered his treatlfe, (liewed that this is by no means 
 the cale ; and that therefore there was no proof what- 
 ever of the identity of phlogifton and hydrogen. And 
 Mr Kirwan in confequence, with that candour which 
 diftlnguifhes fuperior minds, gave up his opinion as un- 
 tenable. %^t 
 
 Mr Lavoifier had already put the queftion, What^"''^^"" 
 proof Is there of the exirtence of phlogifton at ^H ■ ton difuri^ 
 There is only this iingle proof, that fubftances after ved. 
 combuftion are different from what they formerly were. 
 That this difference takes place is certainly true ; but 
 it is owing, not to the feparation of any fubftance, but 
 to the combination of one. It follows, therefore, that 
 there is no proof whatever of the exlllence «f any fuch 
 fubllance z% phlug'ijion in nature; and of courfe we muft , 
 
 conclude that no fuch fubftance exifts (l). 5o» 
 
 15. It Is well known that heat Is produced by the P'""'^"^.''"'-, 
 percuflion of hard bodies agalnft each other. When aP Jpre'r. 
 piece of iron is fmartly and quickly ftruck with a ham-jjon 
 mer, it becomes red hot ; and the production of Iparks 
 by the collifion of flint and fteel is too familiar a faft to 
 require being mentioned. No heat, however, has ever 
 been obferved to follow the percuflion of liquids, nor of 
 loft bodies which eafily yield to the ftroke. ,p. 
 
 It has long been known, that hammering increafes Owing 
 the denfity of metals. The fpeclfio gravity of iron be- Partly to 
 fore hammering is 7,788; after being hammered, 7,840:"'"'™'^" 
 that of platinum before hammering is 19,50; after it, ' 
 23,00. Now condenfation dimlnifties the fpecific calo- 
 ric of bodies. After one of the clay pieces ufed In 
 Wedgewood's thermometer has been heated to 120°, it 
 is reduced to one half of Its former bulk, though it has 
 loft only two grains of its weight, and Its fpecific calo- 
 ric is at the fame time dlmlnlflied one third f. B ut * ^- ^^''''4''' 
 we cannot conceive the fpecific caloric of a body to be^.'^" V '' 
 dimlnllhed without its giving out at the fame time ajjoz. 
 
 quantity 
 
 i 
 
 (k) Thefe very obfervations had been made almoft a century before by Mayow ; but chemiftry was then in 
 its infancy ; little attention was paid to them, and they had been forgotten. 
 
 (l) Mr Lavoifier was therefore the author of w-hat Is called ihe aritiphlog'ijlic theory in chemiftry, or the theory 
 ■which accounts for the phenomena of chemiftry without the afliftance of phlogifton. It has been fo caUed iu 
 oppofition to the theory of Stahl, which explained every thin^ by means of phlogiflon, and which is therefore 
 •called the phlog'iflk theory. 
 
 Some chemift;. have aff^edfed to omit Lavoifier's name altogether, when they fpoke of the antlphlogiftic theory. 
 According to them, that theory was founded upon the experiments and difcoveries of other chemifts, and Lavoi- 
 fier had no other merit but that of brirging it into public notice. 
 
 That Mr Lavoifier, virtually at leaft, claimed feveral of the difcoveries of others, we are forry to be under the 
 neceflity of acknowledging ; and that many of the experiments, brought forward to difprove the exiftence of 
 phlogifton, were firft made by others, is known to all the world : but It Is equally evident, that the firft perfon 
 who aclually formed the theory was Lavoifier ; and furely the merit lies in that. It is not thofe who coUeft 
 the ftones, and the timber, and the mortar, but he who lays the plan, and ftiews how to put the materials toge- 
 ther, that Is in reality the builder of the houfe. Who did not know, as well as Newton, that a ftone fell to the 
 ground, and that the planets revolved round the fun ? and yet, who but Newton could have formed the theory 
 of gravitation ? We would not be underftood to detraft any thing from the merit of the other illuftrlous phllofo- 
 phers who have adorned the prefent age, liiany of whom are at leaft equal, and fome of them fuperior to Lavoi- 
 fier : But we are afraid that envy, or fome worfe motive, guided the pen of one at leaft of the moft active and vi- 
 lulent antagonlfts of that illuftrlous and unfortunate philofopher. It muft not, however, be concealed, that his 
 t'lieoiy of combuftion is incomplete. See Combustion in this Supplement.
 
 Part r. 
 
 Calo-ic. quantity of caloric ; and we know for certain that ca- 
 *- V loiic is evolved during condtnfation. A ihernionieter 
 plactd within a condenfer riles feveral degrees every 
 »Pir-n.m, time air is thrown in *. We can even fee a reafon for 
 ftil. Tra/j/;this. When the particles of a body are forced nearer 
 J78S. each other, the repulfive power of the caloric combined 
 
 with them is increafed, and confequently a paitofit 
 will be apt to fly off. Now, alter a bar of iron has 
 been heated by the hammer, it is much harder and brlt- 
 tler than before. It mufl then have become denfer, 
 and confequently mud have j>arted with caloric. It is 
 an additional coniirniation of this, that the fame bar 
 cannot be heated a fecond time by perculTion until it has 
 been expofed for fomc time to a red heat. It is too 
 brittle, and flies to pieces under the hammer. Now 
 lirittlencfs feems in moil cafes owing to the abfence of 
 the ufual quantity of calo'. ic. Glais unannealeil, or, which 
 is the fame thing, that has been cooled very quickly, is 
 always extremely brittle. When glafs is in a ftate of 
 fulion, there is a vaft quantity of caloric accumulated in 
 it, the repulfion between the particles of which mufl of 
 courfe be very great ; fo great indeed, that they would 
 be difpofed to fly off in every direftion with inconcei- 
 vable velocity, were they not confined by an unufually 
 great quantity of caloric in the furrounding bodies : 
 confequently if this furrounding caloric be removed, the 
 caloric of the glafs flies off at once, and more caloric will 
 leave the glafs than otherwife would leave it, bccaufe 
 the velocity of the particles rnnft be greatly increafed. 
 Probably then the brittlenefs of glafs is owing to the 
 deficiency of caloric ; and we can fcarcely doubt that 
 the brittlenefs of iron is owing to the fame caufe, if we 
 recoUeft that it is removed by the application of new 
 caloric. Part therefore of the caloric which appears in 
 confequence of percuffion feems to proceed from the 
 body llruck ; and this is doubtlefs the reafon why thofe 
 bodies, the denfity of which is not increafed bv percuf- 
 fjon, as liquids and foft fubftances, are not heated at 
 all. 
 AncTrarilv ^^ ^^Y /"""' ^'^ '^^^ caloric, becaufe, often at leaft, 
 to combuf- part of it is probably owing to another canfe. By con- 
 tion. denfation, as much caloric is evolved as is fufficient to 
 
 raife the temperature of fome of the particles of the 
 body high enough to. enable it to combine with the 
 oxygen of the atmofphere. The combination actually 
 takes place, and a great quantity of additional caloric is 
 fcparated by the decompofitlon of the gas. That this 
 happens during the colllfion of flint and fleel cannot be 
 doubted ; for the fparks produced are merely fmall 
 pieces of Iron heated red hot by uniting with oxygen 
 during tlieir paflage through the air, as any one may 
 
 CHEMISTRY. 
 
 279 
 
 convince hiinfelf by aflually examining them. Mr Lane Caloric 
 has (hewn that iron pr(jduces no fparks in the vacuum ' " "" '' 
 of an air-pump; but Mr Kirwan has obferved that they 
 are produced under common fpring water ; and we know 
 that iroii at a certain temperature is capable of decom- 
 pofing water. -q. 
 
 When quartz, rock-cryllal (m), or other very hard''p"k«e. 
 (loneS, are (Iruck agalnll one another they enu't fpark:i. "''"'''"'/ 
 It they be often made to emit fparks above a flieet of 'fJo'','„f„„ 
 white paper, there are found upon it a number of fmallcnfion. 
 black bodies, not very unlike tlie eggs of flies. Thcfe 
 bodies are hard but friable, and wiien rubbed on the 
 paper leave a black Ifain. When viewed with a rai- 
 crofcope, they feem to have been melted. Muriatic 
 acid changes their colour to a green, as it docs that of 
 lavas *. Thefe fubftances evidently produced tlie fparks • Lamanim, 
 by being heated red hot. Lamanon (n) fuppofes that .T"""'"- "'< 
 they are particles of quartz combined witli oxygen. ''^V- 'V^S'- 
 Were that the cafe, the phenomenon would be pre- 
 clfi-ly fimilar to that which is produced by the collifion 
 of flint and ileel. That they are particles of quartz 
 cannot be doubted; but to fuppofe them combined with 
 oxygen is contrary' to all experience : for thefe llone.<! 
 never fliew any difpofition to combine with oxygen even 
 when expofed to the muft violent heat. La Metherie 
 made experiments on purpofe to fee whether Lamanon's 
 opinion was well founded; but they all turned out unfa- 
 vourable to it. And Monge afcertained, that the par- 
 ticles defcribed by Lamanon were pure cryftal unalter- 
 ed, with a quantity of black powder adhering to them. 506 
 He concludes accordingly, that thefe fragments liad Csufe of 
 been ralfed to fo high a temperature during their pafl '* ""* 
 fage through the air, that tliey fet fire to all the mi- 
 nute bodies that came in their way f . We mull ihere-f ^nr.Jr 
 fore either fuppofe that all the caloric was produced by '^'"T"" ''^' 
 inere condenfation, wlilch is not probable, or acknow- 
 ledge that we cannot explain the phenomenon. 
 
 16. Caloric is not only produced by percufHon, but Rmiojon 
 alfo by fricfion. Fires are often kindled by rubblngof caloric 
 pieces of dry wood fmartly agalnlf one another. It is"" friction, 
 well known that heavy loaded carts fometimes take fire 
 by the friclion between the axle-tree and the wheel. ,,3 
 Now in what manner is the caloric evolved or accnmu-Not oR-ing-- 
 laled by friflion ? Not by increafing the denfity of the '" 5"'"'':" ■ 
 bodies rubbed againft each other, as happens in cafes of • 
 
 percuffion ; for heat is produced by rubbing foft bodies 
 againft. eacli other, the denfity of which therefore can- 
 not be increafed by that means, as any one may con- 
 vince himfelf by rubbing his hand fmartly agiinft his 
 coat. It is true, indeed, that heat is not produced by 
 the friction of liquids, but then they are too ylcldiiig ' 
 
 to • 
 
 (m) Thefe ftones are compofed of almoft pure filica. 
 
 (n) This ingenious and unfortunate young man, to whom we are indebted for thefe fads, fell a vlflim to his 
 ardour for knowledge. He accompanied La Peroufe in his laft voyage, and was murdered with the moll favage 
 cruelty, together with La Langle and feveral others, Ijy the natives of the Ifland of Maouna. When a man of: 
 genius, anxious to acquire honeft fame, and a man too fo nobly dilinterefted as Lamanon, thus falls prematurely' 
 before he has attained the objeft of his wifties, 
 
 " Cut off from nature's and fom glory's courfe ! 
 " Which never mortal was fo fond to run," 
 
 ■who can withhold the tribute of regret and admiration, when they 
 
 " Conjefture what he might have proved, 
 
 " And tliink life only wanting to his fame."
 
 28o 
 
 Caloric. 
 
 Nor to de- 
 creafe of 
 fpeci&c ca- 
 loric, 
 » NUhnl. 
 font yourn, 
 ^U. IC6. 
 
 CHEMISTRY. 
 
 310 
 Nor to 
 combuf- 
 tioij; 
 
 le Feu, ch. 
 
 to be fubjtfted to ftrong friflion. It is not owing to 
 the fpeciiic caloric of the rubbed bodies decreafing; for 
 Count Rumford found that there was no fenlible de- 
 creafe *, nor, if there were a decreafe, would it be fuf- 
 ficient to account for the vaft quantity of heat which is 
 fumctimes produced by friftion. 
 
 Count Rumford took a cannon cail folid and rough 
 as it came fronn the founJevy ; he caufed its extremity 
 to be cut off, and formed, in that part, a folid cy- 
 linder attached to the cannon 7^ inches in diameter 
 and 9t5 ir.ches long. It remained joined to the reft 
 of the metal by a fmall cyhndrical neck. In this cy- 
 linder a hole was bored 3,7 inches in diameter and 7,2 
 inches in length. Into this hole was put a blunt fteel 
 borer, which by means of horfes was made to rub again ft 
 its bottom ; at the fame time a fmall hole was made in 
 the cylinder perpendicular to the bore, and ending in 
 the folid part a little beyond the end of the bflre. This 
 was for introducing a thermometer to meafure the heat 
 of the cylinder. The cylinder was wrapt round with 
 flannel to keep in the heat. The borer preffed againft 
 the bottom of the hole with a force equal to about 
 10,000 lb. avoirdupois, and the cylinder was turned 
 round at the rate of 32 times in a minute. At the be- 
 ginning of the experiment the temperature of the cy- 
 linder was 60^ ; at the end of 30 minutes, when it had 
 made 960 revolutions, its temperature was 130°. The 
 quantity of metallic duft or fcales produced by this fric- 
 tion amounted to 837 grains. Now, if we were to 
 fuppofe that all the caloric was evolved from thefe 
 fcales, as they amounted to jull -jj-g part of the cylin- 
 der, they mull have given out 948° to raife the cylinder 
 1°, and confequently 66360° to raife it 70* or to 130-3, 
 which is certjiinly incredible f . 
 
 Neither is the caloric evolved during friftion owing to 
 the combination of oxygen with the bodies themfelves or 
 any part of them. By means of a piece of clock-work, 
 Mr Piftet made fmall cups (fixed on the axis of one of 
 the wheels) to move round with confidcrable rapidity, 
 and he made various fubllances rub againft the outfides 
 of thefe cups, while the bulb of a very delicate thermome- 
 ter placed within them marked the heat produced. The 
 whole machine was of a fize fufflciently Imall to be in- 
 troduced into the receiver of an air-pump. By means 
 of this machine a piece of adamantine fpar was made 
 to rub againft a fteel cup in air : fparks were produced 
 in o-reat abundance during the whole time, but the ther- 
 mometer did not rife. The fame experiment was re- 
 peated in the exhaufted receiver of an air-pump (the ma- 
 nometer ftanding at four lines); no fparks were produ- 
 ced, hut a kind of phofphoric light was vifible in the 
 dark. The thermometer did not rife. A piece of brafs 
 being made to rub in the fame manner againft a much 
 fmaller brafs cup in air, the thermometer (which almoft 
 filled the cup) rofe 0,3°, but did not begin to rife till the 
 friftion was over. This (hews us that the motion produ- 
 ced in the air carried off the caloric »s it was evolved. In 
 the exhaufted receiver it began to rife the moment the 
 friaion began, and rofe in all 1,2°. When a bit of wood 
 was made to rub againft the brafs cup in the air, the 
 thermometer rofe 0,7°, and on fubftituting alfo a wood- 
 en cup it rofe 2,1°, and in the exhaufted receiver 2,4°, 
 ;, and in air condenfed to i-| atmofpl.ercs it rofe 0,5° *. 
 9. If thefe experiments be not though: conclufive, we 
 have others to relate, which vvUl not leave a doubt that 
 
 Part r. 
 
 the heat produced by friflion is not contiefied with the Caloric, 
 decompofition of oxygen gas. Count Rumford con- ' ' v -^ 
 trived, with his ufual ingenuity, to enclofe the cylinder 
 above delcribed in a wooden box filled with water, which 
 effedually excluded all air, as the cylinder itfclf and the 
 borer were furrounded with water, and at the fame time 
 did not impede the motion of the inftrument. The 
 quantity of wat(?r amounted to 18,77 lbs. avoirdupois, 
 and at the beginning of the experiment was at the tem- 
 perature of 60'. After the cylinder had revolved for 
 an hour at the rate of 3 2 times in a minute, the tempe- 
 rature of the water was 107°; in 30 minutes more it 
 was 178° ; and in 2 hours and 30 minutes after the ex- 
 periment began, the water adiially boiled. According 
 to the computation of Count Rumford, the caloric pro- 
 duced would have been fufficient to heat 26,58 lbs. 
 avoirdupois of ice-cold water boiling hot ; and it would 
 have required 9 wax candles of a moderate fize, burning 
 with a clear flame all the time the experiment lafted, to 
 have produced as much heat. In this experiment all ac- 
 ccfs of water into the hole in the cylinder where the 
 fri(ition took place was prcvenleti. But in another ex- 
 periment, the rcfult of which was preci-fely the fame, the 
 water was allowed free accefs *. * Nkholfan 
 
 The caloric, then, which appears in confequence oiilid. 
 friction, is neither produced by an increafe of the den- S'' 
 fity, nor by an alteration in the fpecific caloric of the "„,'^i"\!* 
 fubftances expofed to friftion, nor is it owing to the de-prtfent ia- 
 compofition of the oxygen of the atmofphere. — Whence explicable, 
 then is it derived .' This queftion we are altogether un- 
 able to anfwer. We cannot, however, think that the con- 
 clufion which Count Rumford is difpofed to draw from 
 his experiments is warranted by the prenilfes. 
 pofes, that becaufe we cannot explain the manner that pnmf that 
 caloric Is accumulated by friction, there is no fuch fub-caloric is 
 ftance as caloric at all, but that it is merely a fieculiar"°'- ^ 5^' 
 iiml of motion. We would beg leave to afic, how the 
 fafts mentioned in tiie former part of this chapter, ma- 
 ny of which were furniftied by this ingenious philofo- 
 pher himfelf, and all of which combine to render the 
 exiftence of caloric as a fubilance probable, can be de- 
 flroyed and fet afide, merely btcaule there are other phe- 
 nomena in nature connefted with caloric which cannot 
 be accounted for ? Were it pofTible to prove that the 
 accumulation of caloric by fridfion is incompatible with 
 its being a fnbftance, in that cafe Count Rumford's 
 conclufion would be a fair one ; but this furely has not 
 been done. We are certainly not yet fufficlently ac- 
 quainted with the laws of the motion of caloric (allow- 
 ing it to be a fnbftance) to be able to affirm with cer- 
 tainty that fi iftion could not caufe it to accumulate in 
 the bodies rubbed. This we know at leaft to be the 
 cafe with electricity. Nobody has been hitherto able 
 to demonllratc, in what manner it is accumulated by 
 fridtion ; and yet this has not been thought a fufficient 
 reafon to deny its exiftence. 
 
 Indeed there feems to be a very clofe analogy between Analogy • 
 caloiic and eleftric matter. Both of them tend to difFufe ''^t""" 
 themfelves equally, both of them dilate bodies, both of '^^[■'■'"■" ^"^ 
 
 Hefup--rh?/i!o 
 
 313 
 
 them fufe metals, and both of them kindle combuftible 
 fubftances. Mr Achard has proved, that elettricity can 
 be lubftituted for caloric even in thoie cafes where its 
 agency feems peculiarly neceffary ; for he found that, 
 by conftantly fupplying a certain quantity of the elec- 
 tric fluid, eggs could be hatched jult as when they are 
 
 kept 
 
 eicilricity.
 
 Part I. 
 
 Caloric, 
 
 • PlSietfur 
 '■: Feu. ch.6. 
 
 ■ rnj. ch. 9. 
 314 . 
 
 iletflriciry 
 nay be an 
 gent in the 
 ] eating of 
 1 odies by 
 i£tiun. 
 
 C H E M 
 
 kept at the temperature of io?°. An accident indeed 
 prevented the cliickens from aftuatly turning out ; but 
 tliey were formed and living, and within two days of 
 binfting their (hell. Eleftricity has alio a great deal of 
 influence on the heating and cooling of bodies. Mr 
 Piftet cxhaufled a glafs globe, the capacity of which 
 was I 200, 199 cubic inches, till the manometer within 
 it flood at 1,75 lines. In the middle ot this globe was 
 fufpended a thermometer which hung from the lop of a 
 glafs rod fixed at the bottom of the globe, and going 
 almoll to its top. Oppofite to the bulb of this ther- 
 mometer two lighted candles w-ere placed, the rays of 
 which, by means of two concave mirrors, were concen- 
 trated on the bulb The candles and tiie globe were 
 placed on the fame board, which was iupportcd by a 
 non-conduftor of eleflricity. Two feet and a halt from 
 the globe there was an cledlrifying machine, which 
 communicated with a brafs ring at the mouth of the 
 globe by means of a metallic condudlor. This machine 
 was kept working during the whole time of the experi- 
 ment ; and confequently a quantity of eletlric matter 
 was cowftantly pafhng into the globe, which formed an 
 atmofphere not only within it, but at fome diftance 
 round, as was evident from the imperfect manner in 
 which the candles burned. When the experiment be- 
 gan the thermometer flood at 49,8°. It rofe to 70,2° 
 in 732". The fame experiment was repeated, but no 
 eleftric matter thrown in ; the thermometer rofe from 
 4g,8' to 70,2' ill 1050" ; fo that the eleftricity haftcn- 
 ed the heating almoft a third. In the firfl experiment 
 the thermometer rofe only to 71,3". but in the fecond 
 it rofe to 77°. This difference was doubtlcfs owing to 
 the candles burning better in the fecond than the firfl 
 experiment ; for in other two experiments made exaft- 
 ly in the fame manner, the maximum was equal both 
 when there was and was not eledric matter prcfcnt. 
 Thefe experiments were repeated with this dilFercnce, 
 that the candles were now infulated, by placing their 
 candleflicks in diflies of varniflied glafs. The thermo- 
 meter rofe in the eleftrical vacuum from 52,2° to 74,7° 
 in lojo"; in the fimple vacuum in 965". In the elec- 
 trical vacuum the thermometer rofe to 77° ; in the 
 fimple vacuum to 86°. It follows from thefe experi- 
 ments, that when the globe and the candles communica- 
 ted with each other, eleftricity haftencd the heating of 
 the thermometer ; but that when they were infulated 
 feparately, it retarded it *. One would be apt to fuf- 
 peft the agency of cleftricity in the following experi- 
 ment of Mr Pitlet : Into one of the brafs cups former- 
 ly defcribed, a fmall quantity of cotton was put to pre- 
 vent the bulb of the thermometer from being broken. 
 As the cup turned round, two or three fibres of the 
 cotton rubbed againfl the bulb, and without any other 
 friftion the thermometer role five or iix degrees. A 
 greater quantity of cotton being made to rub againft 
 the bulb, the thermometer rofe 1 5 degrees f . 
 
 We do not mean to draw any other conclufion from 
 thefe fafts, than that eleftricity is very often concerned 
 in the heating of bodies, and that probably fome fiich 
 agent is employed in accumulating the heat produced 
 by friftion. Suppofing that eleftricity is aftually a fub- 
 
 SupPL. Vol. I. Part I. 
 
 I S T R Y. 
 
 flance, and taking it for granted that it is different 
 from caloric, dues it not in all ])viibabdity contain ca- 
 loric as well as all other bodies ? Has it not a tendency 
 to accumulate in all bodies on friction, wluther conduc- 
 tors or non-conduftors ? May it not then he accumu- 
 lated in thole bodies which are rubbed againfl one ano- 
 ther ? or, if they are good cunduftors, may it not pafs 
 through thein during the friftion in great quantities.' 
 May it not part witli fome of its caloric to thefe bodies, 
 either on account of their greater afliniiy or fome otlier 
 caufe ? and may not this be the fource of the caloric 
 which appears during friftion ? | 
 
 Chaf. VI. O/Ught. 
 
 2^1 
 
 VS 
 
 By means of ligit bodies are rendered vifible. Light Newt, niio 
 has been confidcred as a fubrtance compofed of Wuai '.''" > °' 
 particles moving in ftraight lines from luminous bodies ^ 
 with inconceivable rapidity. The diicovcries of New- 
 ton eftabliflied this opinion on the firm bafis of mathe- 
 matical demonftration ; and fince his time it has been 
 generally embraced. Huyghens, indeed, and Euler, ad- 
 vanced another (o). They confidercd light as a fubtile 
 fluid, filling all fpace, which rendered bodies vifible by 
 its undulations. But they tupported their hypothcfis 
 rather by flarting objcdtions to the theory of Newton, 
 than by bringing forward direct proofs. Their objec- 
 tions, even if valid, infteadof ellablifliing their own opi- 
 nions, would prove only that the phenomena of light 
 are not completely underflood ; a truth which no man 
 will refufe to acknowledge, whatever fide of the quef- 
 tion he adopts, Newton and his difciplcs, on the con- 
 trary, have (hewn that the known phenomena of light 
 are inconjijhnt with the undulations of a fluid, and have 
 brought forward a great number of direft arguments, 
 which it has been impoITible to anfwer, in fupport of 
 their theory. It can hardly be doubted, therefore, that 
 the Newtonian theory of light is the true one, ,jg 
 
 Dr Bradley, who, by a number of very accurate ex- Vefocity of 
 periments, and a proceis of reatoning peculiarly ingeni.l'ght. 
 ous, 4'feovered the aberration of light of the fixed itars, 
 has fhewn from it that the velocity of light is to that 
 of the earth in its orbit as 10313 to i. Light there- 
 fore moves at the rate of 1952 18 miles in a fecond. ,,. 
 
 Light, by means of a prilm, may be feparated intoDiviliWe 
 feven rays, differing from each other in colour ; red, """ Icven 
 orange, yellow, green, blue, indigo, violet. None of'^^5'*' 
 thefe are capable of farther decompofition. Marat, in- 
 deed, pretended that he had reduced them to three ; 
 but his experiments are now known to have been mere- 
 ly philofophical frauds, ^15 
 
 When light paffes obliquely into a denfer medium, it OiflerinK 
 is refraSed towards the perpendicular; when into a ra-''! fff'^m- 
 rer, from the perpendicular, 6ir Ifaac Newton difco-^' ' ^' 
 vered that the rays differed in their refrangibility in the 
 order in which they have been named, the red being 
 the leaft, the violet the mofl refrangible. Mr Blair has 
 obfervcd, that the ratios of the refrangibility of the 
 different rays, though not their order, vary fomewhat in 
 different mediums *. • FJinhurgh 
 
 When light paffes. within a certain dillance of a body, P''/. Iran/. 
 N n parallel '"• 
 
 (o) Dr Franklin did the fame, without taking any notice of thefe philofophere, of whofc opinions perhaps 
 he was ignorant. See Tranf. Philad. III. 5.
 
 CHEMISTRY. 
 
 319 
 
 InflciilioB, 
 defleAion, 
 
 * rrar<f. 
 rhihd. ii. 
 + Phil. 
 
 1rar.f.\i^i, 
 
 320 
 And rcflex- 
 ity. 
 
 % Phil. 
 
 3 It 
 
 tij;ht ca- 
 pable of en. 
 tering bo- 
 dies. 
 
 parallel to which it is moving, it is beiit tttvardt it ; 
 when it pafTcs at a greater diftdiice, it is bent from it. 
 The llrll oi thefe properties is called injiulion, the lecond 
 deJleBion. Now the rays differ in thefe properties in the 
 order in which they were named ; the red being moji, 
 the violet leaft, inflexible and deflexible. This was ful- 
 peCtcd by David Rittenhoul'e *, bvit was fird demonftra- 
 ted by the ingenious experiments of Mr Brougham f. 
 
 When light falls upon a vilible body, fome of it is re- 
 flefted back ; and the more poliftied or the whiter any 
 furface is, the more light it reflefts. The rays of light 
 differ alfo in reflexity, the red being the moft, the vio- 
 let the leaft refleKible. This difcovcry we owe to the 
 fame ingenious gentleman J. 
 
 Thefe properties of light conftitute the fubjeft of 
 Optics ; to which we refer thofe who wifli to fee 
 them invefligated. We mention them here becaufe they 
 prove that light is adled on by other bodies, that it is 
 fubjetled to the laws of attraftion, and confequently 
 that it polTeffes gravity. 
 
 1. The particles of light fcem alfo, like thofe of ca- 
 loric, to poffefs the property of repelling one another ; 
 at lead their rapid motion, in all directions, from lumi- 
 nous bodies, fcems to be owing to fome fuch property. 
 
 ■3,. Light is capable of entering into bodies, and re- 
 maining in them, and of being afterwards extricated 
 without any alteration. Father Beccaria, and feveral 
 other philofophers, have fnewn us by their experiments, 
 that there are a great many fubftances which become lu- 
 minous after being expofed to the light. This property 
 ■was difcovered by carrying them inftantly from the 
 light into a dark place, or by darkening the chamber in 
 which they were expofed. Moil of thefe fubftances, 
 indeed, lofe this property in a very lliort time, but they 
 recover it again on being expofed to the light ; and this 
 may be repeated as often as we pleafe. We are indebt- 
 ed to Mr Canton for fome very interefting experiments 
 on this fubjeft, and for difcovering a compofition which 
 pofieffes this property in a remarkable degree. He cal- 
 cined fome common oyfter fhells in a good coal tire for 
 half an hour, and then pounded and fitted the pureft 
 part of them. Three parts of this powder were mixed 
 •with one part of the flowers of fulpliur, and rammed 
 into a crucible which was kept red hot for an hour. 
 The brighteft parts of the mixture v.e»e then fcraped 
 off, and kept for ufe in a dry phial well Hopped. When 
 this compofition is expofed for a few feconds to the 
 light, it becomes fufficiently luminous to enable a per- 
 fon to diftinguilh the hour on a watch by it. After 
 fome time it ceafes to fliine, but recovers this property 
 on being again expofed to the light. Light then is 
 not only afted upon by other bodies, but it is capable 
 of uniting with them, and afterwards leaving them with- 
 out any change. 
 
 It is well known that light is emitted during com- 
 buftion ; and it has been objedlcd to this conclufion, 
 that thefe bodies are luminous only from a flow and 
 imperceptible combullion. But furtly combuftion can- 
 not be fufpeftcd in many of Father Beccaria's experi- 
 ments, when we reflect that one of the bodies on which 
 they were marie was his own hand, and that many of 
 the others were altogether incombuilible; ai.d the phe- 
 nomena obferved by Mr Canton are alfo incompatible 
 with the notion of combuftion. His pyrcphorus (hone 
 only in confequence of being expofed to light, and loft 
 
 Part I. 
 
 that property by being kept in the dark. It is not 
 expofure to light wiilch caufes fubftances capable of 
 combuftion at the temperature of the atmofpheie to be- 
 come luminous, but expofure to air. If the fame tem- 
 perature continues, they do not ceafe to ftiine till they 
 are conUimed ; and if they ceafe, it is not the applica- 
 tion of light, but of caloric, which renders them again 
 luminous : but Canton's pyrophorus, on the contrary, 
 when it had loft its property of ihining, did not recover 
 it by the application of heat, except it was accompa- 
 nied by light. The only effeft which heat had was to 
 increafe the feparation of light from the pyrophorus, 
 and of courfe to fhorten the duration of its luminouf- 
 nefs. Two glafs globes, hermetically fealed, containing 
 each fome ot this pyrophorus, were expofed to the hght 
 and carried into a dark room. One of them, on being 
 immerfed in a bafon of boiling water, became much 
 brighter than the other, but in ten minutes it ceafed 
 to give out light ; the other remained vifible for more 
 than two hours. After having been kept in the dark 
 fur two days, they were both plunged into a bafon of 
 hot water ; the pyrophorus which had been in the wa- 
 ter formerly did not ihine, but the other became lumi- 
 nous, and continued to give out light for a conliderable 
 time. Neither of them afterwards ihone by the appli- 
 cation of hot water ; but when brought near to an iron 
 heated fo as fcarcely to be vifible in the dark, they fud- 
 denly gave out their remaining light, and never Ihone 
 more by the fame treatment : but when expofed a fe- 
 cond time to the light, they exhibited over again pre- 
 cifely the fame phenomena ; even a lighted candle and 
 eleftricity communicated fome light to them. Surely 
 thefe fadts are altogether incompatible with combuilion, 
 and fully fufficient to convince us that light alone was 
 the agent, and that it had aftually entered into the lu- 
 minous bodies. 
 
 It has been qucftioned, indeed, whether the light 
 emitted by pyrophori be rhe fame with that to which 
 they are expofed. Mr Wilfon has proved, that in ma- 
 ny cafes at leaft it is different, and in particular that 
 on many pyrophori the blue rays have a greater effeft 
 than any other, and that they caufe an extrication of 
 red light. Mr de Groffer has fiiewn the fame thing 
 with regard to the diamond, which is a natural pyro- 
 phorus *. Still, however, it cannot be queftioned that * Jour, de 
 the luminoufnefs of thefe bodies is owing to expofure ^hf- '"• 
 to light, and that the phenomenon is not connefted with ''°" 
 combuftion. jjj 
 
 But light appears capable, not only of entering Into And of be. 
 bodies, but of combining with them chemically. The '"8 """j^'- 
 phenomena of the phoiphori feem to be inftances of,v 
 this, and a great many fadfs concur to prove that light 
 enters into the compofition of oxygen gas. When ve- 
 getables grow in the light, they give out oxygen gas; 
 but no oxygen is extricated in the dark, even though 
 heat be applied-)-. From this it is evident, that the fe-t Priejiltf 
 paration of this gas from plants, or perhaps the decora-?" , "^'"^ 
 pofition of the water which they contain, depends upon 
 the aftion of light; and that as this decompofition is che- 
 mical, the light to produce it muft either combine with 
 the oxygen or the hydrogen, or at leaft contribute to 
 the combination of fome other fubftance with one or 
 other of them. When the oxides of gold or filver are 
 expofed to light, they are reduced to the metallic ftate \, \ SihuU. 
 and at the fame time a quantity of oxygen gas is extri- 
 cated.
 
 3>J 
 Light 
 ■which ap- 
 pears du- 
 ring coni- 
 buRioii fup- 
 poled com- 
 bined with 
 oxygen gas 
 
 3>4 
 Difficulties 
 attending 
 this rpi. 
 sion. 
 
 cated*. In this cafe, it is cviiknt that the light niuft 
 cither combine with the oxygen or the metals. If a 
 quantity of nitric acid he cxpofed for fome time to the 
 lisht, it becomes yellow, as is well known, and a quan- 
 tity of oxygen gas is found floating on its top. If it 
 be now carried to a dark place, the oxygen is gradually 
 abforbed, and the acid becomes coluurlcfs. In this cafe, 
 nitric acid is decompolcd by means of light, and rcfol- 
 ved into nitrous ac'ui and oX) gen gas. The light mult 
 therefore have combined eiliier with the nitrous acid or 
 the oxygen. But no ciiange wliatcver appears to have 
 been produced in the nitrons acid ; for if it be obtained 
 in the dark bv any other proeefs, it has precifely the 
 fame properties. The oxygen, on the contrary, is con- 
 verted into a gas. It is more probable, then, that the 
 llii-ht has combined with the oxygen than with the acid. 
 Hence there is reafon to fufpect that light makes one 
 of the ingredients of oxygen gas. Caloric has already 
 been Ihewn to make another ingredient. 
 
 During combuftion, a quantity of light as well as ca- 
 loric is almoll always evolved. Wc muil. conclude, there- 
 fore, that light makes a part ot the compolition either 
 of the combullibles themfelves, or of the oxygen gas 
 with which they unite. We have already fliewn that 
 oxvgen gas probably contains light ; and this probabi- 
 lity is confirmed by another faft. Subllances may be 
 combined with oxygen without the emifiion of any 
 light, provided the oxygen be not in the (late of a gas. 
 If phofphorus, for inilance, be put into nitric acid, it 
 attratts oxygen, and is converted into phofphoric acid 
 without the emiiTion of any light. Now if the light 
 which appears during combuftion had been combined 
 with the combullible, it ought to appear in all cafes 
 when that combullible is united with oxygen, whether 
 the oxygen has previoufly been in the ftate of a gas or 
 not. But as this is not the cafe^ we may certainly in- 
 fer, that the light which appears during combuftion is 
 extricated, not from the combullible, but from the oxy- 
 gen gas. And this feems at prefent to be the opinion 
 of the greater number of philofophers. 
 
 But we muft acknowledge, that this conclufion is 
 not without its difficulties, and difficulties, too, which, 
 in the prefent ftate of chemiftry, it does not feem poffible 
 to furmount. 
 
 In the firft place, it is evident, that light may be pro- 
 duced during combuftion, though the oxygen be not in 
 the ftate of a gas : For if nitric acid be poured upon 
 oil of turpentine, the oil takes fire, and burns with the 
 greateft rapidity, and a great deal of light is emitted. 
 This combuftion is occafioned by the oxygen of the 
 acid combining with the ingredients of the oil. It fol- 
 lows, therefore, if the light emitted was previoufly com- 
 bined with the oxygen, that oxygen muft contain liglit 
 when not in the ftate of a gas. Mr Prouft has (hewn 
 that a great variety of fimilar combuftions may be pro- 
 duced. But what is very remarkable, by proper cau- 
 tion the very fame combinations may be made to take 
 place without the vifible emifiion of any light. In that 
 cafe they take place very (lowly, as happens alfo when 
 phofphorus decompofes nitric acid ; fo that the emif- 
 iion or non-emilTion of light feems to depend not upon 
 the ftate of the oxygen, fo much as upon the rapidity or 
 llownefs of the combination. It is true, indeed, as the 
 late Dr Hutton of Edinburgh obferved, that light may 
 be emitted in thefe flow combinations though it be not 
 
 CHEMISTRY. 483 
 
 vilible ; and this is very probably the cafe : but then the I.!gl't. 
 
 proof is deftroycd that light exills in oxygen gas, from 
 its not appearing duting combinations in which the 
 oxygen did not exift previoufly in a gafeous ftate. 
 
 In the fecond place, the colour of the light emitted 
 during combuftion differs almoft always according to 
 the combullible. During the combuftion of phofpho. 
 rus, tin, and zinc, the liglit emllted is while ; during 
 that of fulphur and bifmuth, blue. Now if this light 
 were united with the oxygen, why does it not appear al- 
 ways (jf the fame colour, whatever be the combuftible? 
 
 In the laft place, the phenomena of phofpiiori fhcw 
 that light is capable of entering into other bodies as well 
 as oxygen gas ; and the emilfion of light on the colli- 
 (ion of two flint ftcnes, when no oxygen gas can be de- 
 compofed, is a proof of the fame kind, which cannot be 
 got over. 
 
 In the prefent ftate of chemiftry, therefore, it cannot 
 be concluded, that the light emitted during combuftion 
 does not exift in the combullibles as well as in the 
 oxygen. 3,5 
 
 4. Light has the property of heating bodies. All ^'k!>' '''^-3 
 bodies, however, arc not heated by it. Thofe which '""^"'" 
 arc perfcdly tranfparent, or which allow all the lio-ht 
 to pats throw them, fuifer no alteration in their tem- 
 perature. Thus light may be concentrated upon wa- 
 ter or glafs without producing any effeft. Neither 
 does it produce much change upon thofe bodies (mir- 
 rors for inftance) that refletl all or nearly all the light 
 which falls upon them. And the fmallnefs of the.altcr- 
 ation of temperature is always proportional to the fiiie- 
 nefs of the polilh, or, which is the fame thing, to the 
 quantity of light which is refieftcd. So that we have 
 reafon to conclude, that if a fubftance could be procu- 
 red which refledled all the light that fell upon it, the 
 temperature of fuch a fubftance would not be at all af- 
 fefted by light falling upon it. Dr Franklin expofed 
 upon fuow pieces of cloth of different colours (white, 
 red, blue, blick) to the light of the fun, and found 
 that they funk deeper, and confequently acquired heat, 
 in proportion to the darknefs of their colour. Now it 
 is well known that dark-coloured bodies, even when 
 equally expofed to the light, refleft lefs of it than thofe 
 which are light-coloured. But fince the fame quantity 
 falls upon each, it is evident that dark-coloured bodies 
 muft abforb and retain more of it than thofe which are 
 light-coloured. That fuch an abforption a6lually takes 
 place is evident from the following experiment. Mr 
 Tliomas Wedgewood placed two lumps of luminous or 
 phofphorefcent marble on a piece of iron heated juft 
 under rednefs. One of the lumps of marble which was 
 blackened over gave out no light ; the other gave out 
 a great deal. On being expofed a fecond time in the 
 fame manner, a faint light was feen to proceed from 
 the clean marble, but none at all could be perceived to 
 come from the other. The black was now wiped off, 
 and both the lumps of marble were again placed on the 
 hot iron : The one that had been blackened gave out 
 juft as little light as the other*. In this cafe, the •/■<;/. 
 light which ought to have proceeded from the lumi-rra/i/. 1791 
 nous marble difappeared : it muft therefore have been 
 ftopped in its paffage out, and retained by the black 
 paint. Now black fubftances are thofe which abforb 
 the moft light, and they are the bodies which are moft 
 heated by expofure to light. Cavallo obferved, that a 
 N n 2 thermometer
 
 284 C H E M 
 
 l.ght. thentiom«'ter wilh its bulb blackened (lands higher than 
 • one whifh has Its bulb clean, when e^ipofid to the light 
 
 « Phil. "^ the fun, the light of. day, or the light of a lamp *. 
 TMi/.i7Sc.^Tr Pidlct made the fame oliftrvation ; and took care to 
 afccitain, that when the two tliermomctcrs were allowed 
 to remain hjr fonie time in a dark jdacc, they iic(|uircd 
 preclkly the fame height. He oblerved, too, that when 
 both thermometers had been raifed a certain number of 
 degrees, the clean one fell a good deal fuller than the 
 + Sur Ic oth»-r-[-. Init it is not a fmall degree of heat alone 
 />!/, en. 4. ^lij^-li can be produced by means of light. When its 
 rays are concentrated by a burninj'-glals, they are ca- 
 pable of fetting fire to combuftiblcs with eafe, and even 
 of producii'^' a temperature at leatl as great, if not 
 greater, than what can be procured by the moll violent 
 and bed conducted fires. In order to produce thi<- ef- 
 fe<S, however, they mud be direfled upon fome body 
 capable of abforbing and retaining them ; for when 
 they are concentrated upon tranfparent bodies, or upi n 
 fluids, mere air for inftance, they produce little or no 
 efTecl whatever. We may conclude, therefore, in ge- 
 neral, that in all cafes when light produces heat it is 
 356 abforbed. 
 Heat rev- ^. AH bodies become luminous when their tempera- 
 «iei« bodies j,,^^. |g raifed a certain number of degrees. No fact is 
 luminous, ^^^^^ familiar than this ; fo well known indeed is it, 
 that little attention has been paid to it. When a body 
 becomes luminous by being heated in a fire, it is laid 
 in common language to be red hot. It follows from 
 all the experiments hitherto made, that the tempe- 
 rature at which they become red bed hot is nearly the 
 fame in all bodies. — It feems to be pretty near 8o3°. 
 A red hot body continues to fhine for fome time after 
 it has been taken from the fire and put into a dark 
 place. The conilant acceffion, thtn, either of light or 
 heat is not nifceflary for the fhining of bodies : but if 
 a red hot body be blown upon by a ftrong current of 
 % T.TVeJgi-- air, it ceafes to fhine immediately |. Confcquently the 
 ^■ood.Phil. tnoment the temperature of a body is diminilbed by a 
 T'JM/.i/i"- certain number of degrees, it ceafes to be luminous. 
 
 Whenever a body reaches the proper temperature, it 
 becomes luminous, independent of any contadl of air ; 
 for a piece of iron wire becomes red hot whde immerfed 
 % Id. Hid. i„ mdted lead$. 
 
 327 rp j^j „p|,j,|.al law there is one remarkable excep- 
 
 E»cept the . , ° , , /- l 1 
 
 talis. t!on. It does not appear that the gates become lu- 
 
 minous even at a much higher temperature. The fol- 
 lowing ingenious experiment of Mr T. Wedgevvood 
 fceras to fet the truth of this exception in a very clear 
 point of view. He took an earthen ware tube B (fig. 
 r.), bent fo in the middle that it could be funk, and 
 make feveral turns in the large crucible C, which was 
 filled with fand. To one end of this tube was fixed the 
 pair of bellows A ; at the other end was the globular 
 veffel D, in which was the paffage F, furnifhed with a 
 valve to allow air to pafs out, but none to enter. There 
 
 I S T R y. Part I.. 
 
 was another opening in ihii; globular ^veficl fil'ed with Light, 
 glafs, that one might fee what was going on within. ~"~~v -'■ 
 The crucible was put into a fire; and after the fand had 
 become red hot, the air was blown through the earthen 
 tube by means of the bellows. This air, after palling 
 through the red hot (and, cam.e into the globular velfel. 
 It did not Ihme ; but when a piece of gold wire E 
 was hung at that part of the veffel where the earthen 
 ware tube entered, it became faintly luminous. A 
 proof, that though the air was not luminous, it had been 
 hot enough to ralfe other bodies to the (liiuing tempe- 
 rature. 328 
 
 6. Thus it appears that light and heat reciprocally '''qu'ry in- 
 produce each other ; tliat the fixation of light in bodies"!'!^'' ."^^"'^ 
 always produces heat, and that the application of a fuf- phenomena, 
 ficiently ftrong heat always occafions the extrication of 
 light. Are lieat and light, then, owing to the fame 
 caufe? Docs light become caloric merely by being fixed 
 in bodies ? and does caloric affume the appearance of 
 light whenever it is extricated from them ? In fliort, 
 are caloric and light merely names for the fame fub- 
 ftance, called caloric when it is fixed in bodies, and light 
 when in a date of liberty ? 
 
 To thefe queftions it may be anfwered, That if calo- 
 ric and light were one and the fame fubftance, they 
 ought to produce precifely the fame effefts. Now this is 
 not the cafe: a black body is not heated fooner by mere 
 caloric than any other, though the contrary takes place 
 when both are expofed to the light*. Heat cannot » T. K-VA 
 make growing vegetables exhale oxygen gas, though 'i"""'. ^A* 
 light does it ahnoft indantaneoufly. When oxy-muriatic ■^'''"!/''' 
 acid (a compound of oxygen and muriatic acid) is ex- 
 pofed to the light, a quantity of oxygen gas flies off, and 
 nothing remains but common muriatic acid. Light then 
 decomjiofes this acid ; for if you wrap up a bottle in 
 black cloth, fo as to exclude light, and then expofe it 
 equally to the lun, no fuch decompofition takes place. 
 Now this decompofition cannot be produced by inere 
 caloric. If the acid be heated, it fimply evaporates with- 
 out being altered. Chaptal has proved (p), that the 
 rays of light direfted on certain parts of glaffes, con- 
 taining folutlons of falts, caufe them to crydallize in 
 that part in preference to any other f. Thefe obferva- t M^ot. 
 tions have been confirmed and extended by MrDorthes;};. T°"!°j' 
 Now caloric produces no fuch effefts, nor has the tern- f^tj„_\i 
 perature any influence on the phenomenon. 32. 
 
 Thefe facts are fufixcient to Ihew that light and calo- 
 ric, even when they have entered into bodies, produce 
 different effedls, and that therefore they have different 
 properties (cl). But if the only difference between them 
 were, that the one is in a date of liberty, the other in that 
 of combination, the i#bment light entered a body it ought 
 to be no longer light but caloric, and confequently ought 
 to produce precifely the fame effefts with caloric : And 
 fince this is not the cafe, we are warranted furely 
 to conclude that light and caloric are not the fame, 
 
 but 
 
 J 
 
 (p) Petit made the fame obfervations in 1722. See Memoirs of the .iJcaJfmy of Sciences for that year, p. 9J. 
 and 331. 
 
 (O We mud acknowledge, however, that the following ingenious experiments of Profeffor Piflet might be 
 adduced, to prove that light and caloric poffefs at lead one property in common, that of moving in draight lines. 
 
 He placed two concave mirrors of tin, of nine inches focus, at the didance of twelve feet two inches from one 
 another. In the focus of one of them he placed a ball of iron two inches in diameter, heated fo as not to be 
 
 vlfible
 
 Parti. 
 
 CHEMISTRY. 
 
 but difTerent fubfiances (r). How tlien does caloric oc- 
 calion the appearance of ligjht, and lij^ht that of caloric? 
 We have feen already, tliat there is no body in nature 
 Supi'oled ^,],;j,jj (jo^j n„t contain caloric ; and light has fuch an 
 
 OW-llL' to . - ... 1 '^r 1 • 
 
 the mutual influence upon every thuig, it produces Inch important 
 rcpuUion changes upon the animal and vegetable kingdoms, it 
 of IJijht anil can be extricated from fuch a vnll number of bodies, 
 '"•• that iii all probability we may conclude with regard to 
 it alfo, that it exilts in all, or in almoll all, the bodies in 
 nature. We have no means of afcertaining either the 
 quantity of light or of caloric that exifts in bodies ; 
 but if we were to judge from the quantity which ap- 
 pears during combuftiun, we mu(l reckon it very con- 
 liderrble. Now, may there not exiil a repulfion between 
 the particles of caloric and light ? It is not eafy, at 
 leaft, to iee why light flies off during combiiftion with 
 fuch rapidity, if this be not the cafe. If fuch a repul- 
 fion aftually exiits, it will follow that caloric and light 
 canr.ot be accumulated in the fame body beyond a cer- 
 tain proportion. If the caloric exceed, it will tend to 
 drive off the light ; if the light, on the contrary, hap- 
 pens to prevail, it will difplace the caloric. 
 
 If caloric and. light aftually exill in all bodies, there 
 muft be an affinity between them and all other bodies ; 
 and this afGnity nuift be fo great, as to render ineffec- 
 tual the repulfion which exilts between light and caloric. 
 Let us fuppofe now, that thefe two fubllances exill in 
 all bodies in certain proportions, it will follow, that tho 
 
 .85 
 
 more either of caloric or light is added to any body, the Light. 
 Uronger mult the repulfion between their particles be- """v— 
 come ; and if the accumulation be dill going on, this re. 
 pulliou will foon become great enough to balance their 
 affinity for the body in which tliey exilt, and confcquent- 
 ly will dilpofe them to fly off. If caloric, for inflance, 
 be added to a body, whenever the body arrives at a cer- 
 tain temperature it becomes luminous, becaufc part of 
 the lighi which was formerly combined with it is driven 
 oft. This temperature mull depend partly upon the 
 affinity between the body and caloric, and partly upon 
 its affinity for light. Pyrophori, for inftance, the affi- 
 nity between which and light does not feem to be very 
 great, become luminous at a very moderate temperature. 
 'J'his is the cafe with the pyrophorus of Canton. A 
 •great many hard bodies become luminous when they are 
 cxpofed to a moderate heat ; fluor, for in fiance, carbo- 
 nal of barytes, fpar, fea-lhells, and a great many others, 
 which are enumerated by Mr Thomas Wedgwood •. * pyj 
 The fame ingenious gentleman has obferved, thatTran/' 
 gold, filver, copper, and iron, become luminous when '?y». P- ' 
 heated in times inverfely proportional to their fpccific 
 calorics f. Now the fpecific calorics of thtfe metals . ^^^-^ 
 are in the following order: 
 
 Iron, 
 
 Copper, 
 
 Silver, 
 
 Gold, 
 
 Thejr 
 
 vlfible in the dark ; in the other was placed the bulb of a thermometer. In fix minutes the thermometer rofe from' 
 4" to 14° [Reaumur). A lighted candle, which was fubilituted for the ball of iron, made the thermometer rife in 
 one experiment from 4,6° to 14"; in another, from 4,2^ to 14,3°.. In this cafe both light and heat appeared to 
 aft. In order to feparate them, he interpofed between the two mirrors a plate of clear glafs. Before the inter- 
 pofition of the glafs, the thermometer had rifen from 2® to 12", where it was ftationaiy. After the interpoli- 
 tion of the glafs it funk in nine minutes to 5,7° ; and when the glafs was again removed it rofe in fcven mli;ntes 
 to 11,1°; yet the light which fell on the thermometer did not feem at all dimiiiiihtd by the glafs. Mr Piftet 
 therefore concluded, that the caloric liad been rcflcfted by the mirror, and that it had been the caufe of the rife 
 of the thermometer. In another experiment, a glafs matrals was fubilituted for the iron ball, nearly of the fame 
 diameter with it, and containing 2044 gi'^ins of boiling water. Two minutes after a thick fcreen of ijik which 
 had been interpofed between the two mirrors, was removed, a Fahrenheit's thermometer, which was in the other 
 focus, rofe from 47'' to 50-5 ; and the moment the inatrals was removed from the focus the thermometer ajraln 
 defcended. On repeating the experiment, with this variation, that the bulb of the thermometer was blackened 
 it rofe from ji-J- to 55I. 
 
 The minors of tin were now placed at the dillance of 90 inches from each other ; the matrafs with the boiliu<^ 
 water In one of the foci, and a very fenfible air thermometer in the other, every deo-ree of which was eo'ial to 
 ^gth of a degree of Reaumur. Exaftly In the middle fpaee between the two mirrqrs, there was placed a very thin 
 common glafs mirror, lufpcnded in fuch a manner that either fide could be turned towards the matrafs. When 
 the poliflied fide of this mirror was turned to the matrafs, the thermometer rofe only o, q" ; but when the fide 
 covered with liufoil, and which had been blackened with ink and fmoke, was turned toward the matrafs the ther- 
 mometer rofe 3,5°. In another experiment, when the polllhed fide of the mirror was turned to the matrafs the thcr-' 
 reometer rofe 3'^, when the other fide 9,2°. On rubbing off the tinfoil, and repeating the cxueriment, the ther- 
 mometer rofe 18°. On fubftitutiiig for the glafs mirror a piece of thin white pafteboard of the fame dimenlions 
 with it, the thermometer rofe 10'. On putting a matrafs full of fnow into one of the foci (the mirrors In this- 
 experiment were 10^ feet dillaut from each other), the air thermometer/uni feveral degrees, and rofe a"-aiii when 
 the matrafs was removed. When nitric acid was poured on the fnow, the thermometer funk c" or d' lower. 
 
 Taking it for granted that thefe experiments proved the motion of caloric in Ihaight lines like li"-ht, Mr PIc- 
 tet endeavoured to difcover the velocity of hs motion. For this purpofe he placed two concave mirrors at the 
 dillance of 69 feet from each other; the one of tin as before, the other of plafter gilt, and 18 inches in diame- 
 ter. Into the focus of this lall mirror he put the air thermometer, and the bullet of iron heated as before into 
 that of the other. A few inches from the face of the tin mirror there was placed a thick fcreen, which was re- 
 moved as foon as the bullet reached the fdcus. The thermometer rofe the inllant the fcreen was removed, with- 
 out any perceptible interval ; hence he concluded, that the time caloric takes in moving 69 feet is too (hort to 
 be meahued. See PiFlel fur h Feu, chap. ill. 
 
 (r) See more on this fubjeft. under Theruometric SptSrum in this Supplement,
 
 They become lumlnouB, tJicrffore, when expofcd to 
 the fame degree oi" lieat, in the foUov/iug order : 
 Gold, 
 Silver, 
 Copper, 
 Iron. 
 
 Now the fmaller the fpecilic caloric of any body is, 
 the Icfs niuft be the quantity of caloric necefTary to 
 raife it a given number of degrees ; the fooncr therefore 
 mud it arrive at the temperature at which it gives out 
 light. It was natural to expedl, then, if the emilfion of 
 L'ght from a body by the application of heat be owing 
 to the repulfion between caloric and light, that thofe 
 bodies (hould become luminous foonelt in which that 
 repullion increafes with the greateft rapidity ; and this 
 we fee is preeifely the cafe. The only queftion to be 
 determined before drawing this conclufion is. Whether 
 the fame quantity of caloric entered all of them ? That 
 depends upon their conducing power, which, accord- 
 ing to Ingenhoufz, is in the following order : 
 Silver, 
 Gold, 
 Copper, 
 Iron. 
 
 We fee, then, that this condufting power is nearly 
 in the order in which thefe metals become luminous ; 
 fo that the greateil quantity of caloric would enter thofe 
 which become fooiieft luminous. Now this is juft what 
 ought to happen, provided the expulfion of light from a 
 luminous body, by the application of heat, be owing to 
 the repullion between the particles of caloric and light. 
 
 The repulfion between the different rays of light and 
 caloric does not feem to be equal ; the repulfion be- 
 tween the blue rays and caloric feenis to be greater than 
 that between the red rays and caloric; and the repulfion 
 between all the rays and caloric feems to be dlreffly as 
 their refrangibility : accordingly, when heat is applied 
 to a body, the blue rays efcape fooner, and at a lower 
 temperature, than the red rays and others which are 
 moft refrangible. When fulphur, for inllance, is burnt at 
 a low temperature, the colour of the flame is blue ; and 
 when examined by the prifm, it is found to confift of the 
 violet, indigo, blue, and fometimes of a fmall quantity of 
 the green rays* ; but when this fubftance is burnt at a 
 high temperature, the colour of the flame is white, all 
 the rays feparating together. When bodies have con- 
 tinued to burn for fome time, they may be fuppofed to 
 have loit the greater part of the moll refrangible rays ; 
 hence the red appearance of bodies, charcoal for in- 
 ftance, that have burnt for fome time, the only rays which 
 remain to ftparate being the orange, yellow, and redf . 
 
 The blue rays feem not ordy to repel caloric with 
 greater force, but likewife to have a greater affinity for 
 other bodies than the red rays have ; for they decom- 
 pofe the oxide of filver (or rather the muriat of filver) 
 much fooner, and to a greater extent, than the red 
 f Sinnehler. "yst: hence we fee the reafon why the application of 
 
 CHEMISTRY. 
 
 the blue rays to Mr Wilfon's pyrophori and to the dia- 
 mond caufes an extrication of red rays. 
 
 Phil. Tranf. 
 1785- 
 
 f iby. 
 
 We have feen already, that the gafts are not heated 
 red hot by the application of heat. It would follow 
 from this, that the gafes do not contain light : but the 
 contrary is certain ; for light is atlually cxtiicated du- 
 ring tlie conibullion of hydrogen, and muil therefore 
 have exiiled either in the oxygen or hydrogen gas, or 
 in both. Probably therefore the reafon that heat does 
 not extricate light from the gales is, that the affinity 
 between their bafes and light is exceedingly (Irong : it 
 woiJd therefore require a more than ufual temperature 
 to produce its extrication ; and on account of the great 
 dllatabillty of thefe gafes, which always tends to dlmi- 
 nifh the repulfion between the caloric and light, this 
 temperature cannot be applied. It is eafy to fee, upon 
 the fuppofition that there exifts a repulfion between ca- 
 loric and light, why the accumulation of light fliould 
 produce heat, and why light only occafions heat in 
 thofe bodies that abforb It. 
 
 Such ;s the theory of the caufe of the reciprocal ex- 
 trication of light and caloric by the application of thefe 
 fubltances refpecillvely to bodies, which has been pro- 
 pofed by feveral ingenious chemifts (s) ; and we ac- 
 knowledge frankly, that it appears to us by far the 
 moft: plaufible of all the explanations of this phenome- 
 non with which we are acquainted. 
 
 It is not, however, beyond the reach of objeftions, obje^ions 
 and objeftions too, we are afraid, altogether incompa-to which 
 tible with its truth. Were the repulfion between caloric?''''^ thory 
 and light the only caufe of the luminoufiiefs of hot bo-"* '* ''" 
 dies, the continual application of heat would- furely in 
 time feparate the whole of the light which was com- 
 bined with the body, and then it would ceafe to be lu- 
 minous altogether ; but we have no reafon to fuppofe 
 that bodies ever ceafe to become luminous by the con- 
 tinued application of heat. Claveus kept melted, and 
 confequently red hot, gold for months in a furnace ; 
 but he does not fay that its luminoufnefs was dimlnifh- 
 ed, far lefs deilroyed ; and had fuch a remarkable phe- 
 nomenon taken place, certainly he would not have failed 
 to inform us ; but fo far from that, he ycprefsly fays 
 that It fuffered no alteration (t) ^. j Shan't 
 
 Whether light would continue to extricate a great Boye, hi. 
 deal of caloric during fo long a time, has never been 1^8. 
 tried : but we have no reafon for fuppofing that its 
 power to produce that effeft is ever exhaufted ; for bo- 
 dies, after being expofed to the fun for years, and even 
 for ages, are juft as much heated by It as ever. But 
 thefe eft"e£ls, far from being Inexhauftible, ought, ac- 
 cording to the theory, to come very fpeedily to an end. 
 It is certainly probable, then, as other philofophers 
 have fuppofed, that though light and caloiic are not 
 preeifely one and the fame fubftance, they are fome hoy? 
 or other intimately conncfted, and are either compofed 
 of different proportions of the fame ingredients, or the 
 one enters into the compofition of the other. 
 
 One 
 
 330 
 
 (s) Partictdarly by Dr Parr, v;ho is faid to be the author of a paper on this fubjeft, publllhed in the Exeter 
 Memoirs. 
 
 (t) a gentleman, to whom we mentioned this objeAion, obferved, that in the cafe of bodies long expofed to 
 heat, the light wliich appears to proceed from them, might, in fad, be extricated from the atmofphere by the ca- 
 loric communicated to it from the heated body. This thought is new and Ingenious, and might eafily be put to 
 the tell of experiment. Some of the fads mentioned in the text are rather hoftile to it ; but ftiould it prove 
 tv ell founded, it would go far to remove moll of the difficulties in which the theory of light is at prefent involved.
 
 Fart I. C H E M 
 
 Light. One of the fxrft theoriea of this kind (for the opinion 
 
 31 
 
 talonc. 
 • In hi^ 
 Ircatijc en 
 Fire. 
 
 of Stahl has been already (lifcufTed) was formed by Mr 
 Scheele's Scheele*, one of the moft extraordinary men and great- 
 th.'oiyot" ell philofophcrs that ever exitled. Without the adill- 
 lijrht and ancc of education or of wealth, his genius bui (I forth 
 with ailonifhing luftre; and at an age when moil phi- 
 lofopiiers are only riling into notice, he had finiihed a 
 career of difcoverios which liave no parallel in the an- 
 nals of chcmillry. Whoever widies to behold ingenuity 
 combined with fimpllcity, whoever wilhes to fee the in- 
 exhaullible refourcesof chemical analyfis, whoever wifh- 
 cs for a model in chemical refearches — has only to per- 
 ufe and to (Indy the works of Scheele (t). After a 
 vail number of experiments, eonduiSted with aflonidiing 
 ingenuity, he concluded, that caloric was compofed of 
 a certain quantity ot oxygen combined with piiloglilon; 
 that radiant heat, a fubltance which he fuppofcd capa- 
 ble of being propagated in ihaight lines like light, and 
 not capable of combining with air, was compofed of 
 oxygen united with a greater quantity of phlogillon, 
 and light of oxygen united with a itlll greater quantity. 
 He fuppofcd, too, that the difference between the rays 
 depended upon the quantity of phlogillon : the red, ac- 
 cording to him, contained the leall ; the violet, the 
 mod phlogillon. By ph/ogijlon Mr Scheele feems to 
 have meant hydrogen. It is needlefs therefore to exa- 
 mine his theory, as it is now known that the combina- 
 tion of hydrogen and oxygen forms not caloric but wa- 
 ter (u). The whole fabric therefore has tumbled to the 
 ground; but the importance of the materials will always 
 be admired, and the ruins of the ftrufture (hall remain 
 eternal monuments of the genius of the builder. 
 
 Mr de Luc, fo well known for his important meteo- 
 
 rolgicul labours, has advanced another theory-f-. Ac- 
 
 '^idicsTir la wording to him, light is a body which moves conilantly 
 
 Mdeoio- in llraight lines, with fuch rapidity that its gravitation 
 
 De Lu.'s 
 
 theory. 
 t In Ms 
 
 ttgic. 
 
 towards other fubilances bears no fenfible proportion to 
 its motion. Light has the property of combining with 
 another unknown fubllance, and the compound formed 
 is caloric, which poffeffes very different properties from 
 light. Caloric is conilantly dcfcribing helicoidal curves 
 round an axis, which accounts for the flownefs of its ap- 
 parent motion. Light produces or increafes heat, part- 
 ly by increaling the expanfive power of caloric, and 
 
 1 S T R Y. 287 
 
 partly by combming with the untnoiun fuljlancf, and Light. 
 
 forming new caloric ; caloric, on the other h-^nd, is al- ' v— ' 
 
 ways decompofed when bodies become luminou;. This 
 theory is certainly ingenious, and would remove many 
 of the difiiculties which we ;it prefent labour under in 
 attempting to explain the phenomena of caloric and 
 liglit. It is, however, liable to other difficulties which 
 could not be ealily furmouiited. But it is .i.edlefs to ex« 
 ann'ne tliefe, as the theory itfelf is fupjjoried by no evi- 
 dence whatever, and cannot therefore be admitted. 
 
 Another theory has been advanced by the late DrHuttm.'a 
 Hutton of Edinburgh (v) ; a man of undoubted genius, theory, 
 but of ralher too I'pecuLitive a turn of mind, and who 
 fometimes involved himl'elf in difiiculties from his very- 
 ingenuity. All his writings dilplay evident marks of 
 the piofound philofopher : they contain much inilruc- 
 tion ; and even his miflakes are not without their ufe : 
 but uutortunately his manner is fo peculiar, that it is 
 fcarccly more difficult to procure the lecrci^ of fcience 
 from Nat uic herfclf, th.iu to dig ihem from the writings 
 of this philofopher. He fuppofes that there are two 
 kinds of matter, gravitating matter and lio-ht ; the lail 
 of which wants gravity, and confequently neither pof- 
 feffes magnitude (w) nor momentum. Light has the 
 power of being fixed in bodies ; and then'it becomes 
 either caloric or phlogillon, which differs in fome parti- 
 culars from caloric, but in what, the Doftor does not 
 precifely tell us. 
 
 Part of this theory we have examined already when 
 \ve attempted to prove that light and caloric were dif- 
 ferent fubilances. The other part of the theory feems 
 to involve a contradidion ; for how could light become 
 fixed in a body, unleCs it were attrafted by it ? and if 
 light poffeffes attraction, it furely cannot be dellilute 
 of gravity ; for what is gravity but at/reiuioti (x)f 
 
 Thus, notwithftanding the ingenuity of the philofo- 
 phers who have attempted to inveiligate this part of 
 chcmiflry, the connexion between light and caloric is 
 flill unknown. We mull content ourfelves, therefore 
 with ccufidering them at prefent as difliuA fubflaiices, 
 and leave the folution of the many difficulties which at 
 prefent perplex us to the more happy labours of future 
 inquirers. 
 
 Part 
 
 (t) This Newton of chemiftry died in 178(5, at the age of 44. His moral charaSer, according to Mr Er- 
 hart and others, who were the companions of his youth, and Melfrs Gadolin, Efpling, and thofe who knew him 
 in his latter days, was irreproachable and pvaife worthy. His outward appearance was not exprcllive of the g-reat 
 mind which lay concealed as it were under a veil. He leldom joined in the ufual converfatior.s and amufements 
 of fociety, having as little leifure as inclination to do fo ; for what little time he had to fpare from the hurry of 
 his profeflion (an apothecary), was conilantly filled up in the profecution of experiments. It was only when 
 he received vifits from his friends, with whom he could converfe upon his favourite fcience, that he indulged him- 
 felf in a little relaxation. For fuch friends he had a fincere affeftion, as he had alfo for thofe that lived at a di. 
 fiance, and even for fuch as were not perfonally known to him. He kept up a regular correfpondencc with 
 Meffrs Erhart, Meyer, KIrwan, Crell, and feveral other chemifts. See Crell's Life of Scheele. 
 
 (u) This candid philofopher afterwards acknowledged, that the proofs for the compofitlon of water were 
 complete : but we do not know exaflly how he attempted to reconcile his theory of heat with the belief that 
 w-ater was compofed of oxygen and hydrogen ; two opinions which are certainly incompatible. 
 
 (v) See his dlffertations on different fubjeils of natural philofophy. 
 
 (w) Indeed Dr Hutton refufed this property to gravitating matter alfo ; following, in this particular the 
 theory of the celebrated Bofcovich. 
 
 (x) We hope not to be accufed of difputing merely about the meaning of a word, till what (s feid on tjiis 
 fubject in the chapter of the prefent article, which treats oi yiffinity, ha$ been examined.
 
 288 
 
 CHEMISTRY. 
 Part II. Of COMPOUND BODIES. 
 
 Part ir. 
 
 334 
 \Veii;ht of 
 water. 
 
 Water. 'T''0 thofe bodies which are compofed of two fimph 
 ——\ •' /-I fuhjiances combined tojethtr, for want of a better 
 name we have given the appellation of compound bodict. 
 They may be reduced under five clufies : 
 
 1. Water, 4. Alkr\lies, 
 
 2. Alcohol, 5. Acids. 
 
 3. Oils, 
 
 Thefe (hall be the fubjeft of the five following chn.p- 
 ters; and we fliall finilli this part of the article with fome 
 obfervations on AJfin'Uy. 
 
 Chap. I. 0/ Water. 
 
 Water is a well-knovn liquid, found in abundance 
 in every part of the world, and abfulutely neceflary for 
 the exiftence of animals and vegetables. 
 
 When pure, in which ftate it can be obtained only 
 by diilillation, it is tranfparent, and deltitute of colour, 
 tafte, and fmell. 
 
 A cubic foot of water, at the temperature of 5 ?», 
 weighs, according to the experiments of Profeflbr Ro- 
 bifon of Edinburgh (fee Specific Gravity, Encycl.), 
 998,74 avoirdupois ounces, of 437,5 grains troy each, 
 or only 1,26 ounces lefs than loco avoirdupois ounces; 
 fo that rain water, at the fame temperature, will weigh 
 pretty nearly 1000 ounces. The fpecific gravity of 
 water is always fuppofed = 1,00:, and it is made the 
 ,-^ meafure of the fpecific gravity of every other body. 
 ice. When water is cooled down to 32", it'affumes the 
 
 form of ice. If this procefs goes on very flowly, the ice 
 afTumes the form of cryftalline needles, croffing each 
 other at angles either of 60° or 120", as Mr de Mairan 
 has rem-irked ; and it has been often obferved in large 
 cryftals of determinate figures. Ice, while kept at a 
 temperature confiderably below 32°, is very hard, and 
 may be pounded into the fined dud. It is elaftic. Its 
 ^^6 fpecific gravity is lefs than that of water. 
 Steam. When water is heated to the temperature of 212°, 
 
 it boils, and is gradually converted into fteam. Steam 
 lis an invifible fluid like air, but of a lefs fpecific gravi- 
 ty. It occupies about 1 200 times the fpace that water 
 does. Its elafticity is fo great, that it produces the 
 nnoft violent explofions when confined. It is upon this 
 principle that the fteam-engine has been conftrufted. 
 See Steam and Steam- Engine, Encycl. 
 
 The phenomena of boiling are owing entirely to the 
 rapid formation of fteam at the bottom of the vefiel. 
 The boiling point of water varies according to the pref- 
 fure of the atmofphere. In a vacuum water boils at 
 90° ; and when water is confined in Papin's digefter, it 
 may be almoft heated red hot without boiling. The 
 mixture of various falts with water affeft its boiling 
 point confiderably. . Mr Achard made a number of ex- 
 periments on that fubjeft , the ixfult of which may be 
 '/. ieen in the following Tables * : 
 
 Class [. Salts 'which do not offeP. the Boiling Point. 
 Sulphat of copper. 
 
 Class II. Sails 'which raife the Boiling Point. 
 
 , f Muriat of foda "1 Raifes the C 10,35 
 J. < Sulphat of foda > boiling -J 5,6 
 ° (.Sulphat of potafs 3 point 
 
 337 
 Boiling 
 
 point of 
 water. 
 
 338 
 Impre^na 
 tt\ with 
 various 
 f.ilts. 
 
 » Trnr., 
 Berth 
 
 «7Sj 
 
 A faturated 
 Xolutioa 
 
 ;f 10,3 
 { 5.6 
 
 L 0,9 
 
 A faturated j f''^\ °^ ^^^^ 7 ^f'.' '^^ f -5' ^ 
 r 1 ■ c ■{ Uoracic acid > boiling -i 2,2 "- 
 
 folution ot)^, ^ c r 1 \ •.) 
 
 t Carbonat or ioda J point L'-J) 
 
 Water. 
 
 This augmentation varies with the quantity of fait 
 diflolved. In general, it is the greater the nearer the 
 folution approaches to faturation. 
 
 Class III. Salts •which loiuer the Boiling Point. 
 
 f In a fraall quantity, lowers the boiling 
 
 Borax, i. point . . . . 
 
 (.Saturated folution of, 
 
 c. 1 , , r r fin a fmall quantity, 
 
 bulphat ot magneha, < ., . , j /- 1 ^- r 
 '^ ° (Saturated iolution of 
 
 f A very fmall quantity of. 
 
 Alum, < A greater quantity, 
 
 C A faturated folution of. 
 
 in any proportion. 
 
 { 
 
 1.350' 
 
 0,22 
 
 2.+7 
 
 I.I 
 
 0,0 
 
 0,7 
 
 0,0 
 
 2,02 
 
 0'45 
 
 0,22 
 1,24 
 
 Class IV. 
 VT . r f Small quantity of, lowers the boil- 
 
 ma, ^ , 
 
 mg point - - . 0>45 
 
 Saturated folution of, raifes do. 9)79 
 Carbonat f Small quantity of, lowers do. 0,45 
 
 of potafs, |_ Saturated folution of, raifes do. 11,2 ,,„ 
 
 Water was once fuppofed to be incomprefiible, but Water 
 the contrary has been demonftrated by Mr Canton. The f"niprer- 
 Abbe Mongez made a number of experiments, long af- 
 ter that philofopher, on the fame fubjeft, and obtained 
 fimilar refults. ^.g 
 
 Water was believed by the ancients to be one of the Opinion 
 four elements of which every other body is compofed ; ' -t its 
 and, according to Hippocrates, it was the fubftance"^""^^ 
 which nourifties and lupports plants and animals. That 
 water was an unchangeable element continued to be be- 
 lieved till the time of Van Helmont, who made plants 
 grow for a long time in pure water : From which ek- 
 peviment it was concluded, that water was convertible 
 into all the fubllances found in vegetables. — Mr Boyle 
 having digefted pure water in a glafs veflel hermetically 
 fealed for above a year, obtained a quantity of earthy 
 fcales ; and concluded, in confequence, that he had con- 
 verted it partly into an earth *. He obtained the fame « shaw'i 
 earth by diftilling water in a tall glafs veffel over a Hovie, iii. 
 flow fire f. Margraf repeated the experiment with the 417- 
 fame refult, and accordingly drew the fame conclufion. '' * '" 
 But the opinion of thefe philofophers was never very 
 generally received. The laft perfon who embraced it 
 was probably Mr Wafelton, who publiflied his experi- 
 ments on the fubjcdt in the yournal de Phyjique for 
 1780. Mr Lavoifier had proved, as early as 1773, *^'''- 
 the glafs veffels in which the diilillation was performed 
 loll a weight exaflly equal to the earth obtained. Hence 
 it follows iirefiftibly, that the appearance of the earth, 
 which was filica, proceeded from the decompofition of 
 the veffels ; for glafs contains a large proportion of fili- 
 ca. It has been fince (hevs'n by Dr Priellley, that wa- 
 ter always decoinpofes glafs when applied to its furface 
 for a long time in a high temperature. 
 
 Vv'^ ;,. .e formerly mentioned, that water is compofed 
 of oxygen and hydrogen. This great difcovery has 
 
 con. 
 
 ■»67'
 
 fart II. CHEM 
 
 Water, contributed more purliaps than any otlier to the advance- 
 
 '~~"v— ' rnent of the fcience of chemiftry, by fiirniflting a key 
 
 •tin''' r for the explanation of a uiodi<n'ous number of plieno- 
 
 the difcii- meiia. J he evidence, theretoie, on which it rcUs, and 
 
 very of its tlie objeiftions wliich have been made to it, dcftrve to 
 
 compofi- ije examined Avith peciiHar attention. 
 
 "°"" The (iril perfon' probably who attempted to difcover 
 
 vh.it was produced by burniii;^ hydrogen gas wasSeheele. 
 
 He concluded, thst during the combultion oxygen and 
 
 hydrogen combined, and that tlie produdt was caloric. 
 
 Ill 1776 Macqiier, afTifted by Sigaud de la Fond, fct 
 
 fire to a bottle full of hydrogen gas, and placed a faucer 
 
 above the flame, in order to fee whether any fuliginous 
 
 fmoke woidd be produced. The faucer remained per- 
 
 feftly clean ; but it was moiftened with drops of a clear 
 
 • MT<-7Kfr'jliquid, which thty found to be pure water*. 
 
 Viitimjry, Next year Bucquet and Lavoifier exploded oxygen 
 
 °'''' ^"Z; '"'and hydrogen gas, and made an attempt to difcover 
 
 ' what was the product ; about tlie nature 01 wnicii tliey 
 
 had formed diifcrent conjectures. Bucquet had fuppo- 
 
 fed that it would be carbonic acid gas ; Lavoifier, on 
 
 the contrary, fufpeCled that it would be fulphuric or 
 
 fnlphurous acid. What the produe^ was tliey did not 
 
 difcover ; but they proved that no carbonic acid gas was 
 
 formed, and confcquently that Mr Bucquet's hypothelis 
 
 iMtm. Viiry^''-^ '" f"i"ided f . 
 
 178;, 470. In the beginning of the year 1781, Mr Warltire, at 
 the requeil of Dr Priellley, fired a mixture of thefe two 
 gafes contained in a copper veflel ; and obferved, that 
 after the experiment the weight of the whole was dimi- 
 nilhcd. Dr Priellley had previoufly, in the prefence of 
 Mr Warltire, performed the fame experiment in a glafs 
 veffcl. This veffel became moid in the infide, and was 
 covered with a footy fubflanec J, which Dr Priellley 
 afterwards Uippofed to be a part of the mercury ufed in 
 tilling the veffcl ^. 
 
 In the fummer of 1781, Mr Henry Cavendifli, who 
 had been informed of the experiments of Priellley and 
 Warltire, fet fire to joo,ooo grain meafurcs of hydrogen 
 gas, mixed with about %\ times that quantity of com- 
 mon air. By this procefs he obtained 1^5 grains of 
 pure water. He alio exploded 19,^00 grain meafures 
 of oxygen gas with 37,003 of hydrogen gas, and ob- 
 tained 30 grains of water, containing in it a little nitric 
 acid. From thcle experiments he concluded that water 
 was a compound. — Mr Cavendifli mull therefore be con- 
 fidered as the real difcoverer of the compofition of wa- 
 ter. He was the firft w'ho afcertained that water was 
 produced by firing oxygen and hydrogen gas, and the 
 firll that drew the proper conclulion from that fatt. Mr 
 Watt, indeed, had alto drawn the proper conclufion 
 from the experiments of Dr Priellley and Mr Warltire, 
 and had even performed a number of experiments him- 
 felf to afcertain the fait, before Mr Cavendifli had com- 
 municated his ; but he had been deterred from publifh- 
 ing his theOry by fome experiments of Dr Priellley, 
 I WiV. Ixxv. which appeared contrary to it (|. He has therefore a 
 I30' claim to the merit of the difcovery ; a claim, however, 
 
 which does not affeft Mr Cavendilh, who knew nothing 
 of the theory and experiments of that ingenious philo- 
 iopher. 
 
 SuPPL. Vol. I. Parti. 
 
 § nu. 
 
 Ixxiv. 331. 
 
 1 S T R Y. 289 
 
 Meanwhile, in the winter i ySi'J, Mr Lavoifier, wlio 'Water, 
 had fufpetted that when oxygen and hydrogen gaa were '~"~v~~' 
 exploded, fulphuric or fulphurous acid was produced, 
 made an experiment in order to afcertain the faft, at 
 wliich Mr Gingemlue affilled. They filled a bottle, ca- 
 pable of holding fix pints (French), with hydrogen ga^, 
 to which they fet fire, and then corked the bottle, after 
 pouring into it 20/,. (French) of lime-water. Through 
 the cork there pafled a copper tube, by means of which 
 a ftrcam of oxygen gas was introduced to fupport the 
 flame. Though this experiment was repeated three 
 times, and inftead ot lime-water a weak folution of al- 
 kali and pure water were fubllituted, they could not 
 obferve any pvodudl whatever*. This refult aftoniflicd* Af,„, 
 Mr Lavoifier exceedingly; he refolved, therefore, to n:. Par. 1781, 
 peat the experiment on a larger fcale, and if pofl'ibleP-470' 
 with more accuracy. By means of pipes furniflied with 
 flop-cocks, he put it in his power to luiijily both gafes 
 as they fliould be wanted, that he might be enabled to 
 continue the burning as long as he tiiought proper. 
 
 The experiment was made by Lavoifier and La Place 
 on the 24111 of June 1783, in the ])refence of Melfrs 
 Lc Roi, Vandcrmondt, feveral other academicians, and 
 Sir Charles Elagden, who informed them that Mr Ca- 
 vendifli had already performed it, and that he had ob- 
 tained water f. They continued the inflammation till t .W//. 
 all their flock of gafes was walled, and obtained about P- 47^- 
 295 grains of water, which, after the moll rigid exa- 
 mination, appeared to be perfectly pure. F'rom this 
 experiment Lavoifier concluded, that water was com- 
 pofed of oxygen and hydrogen. Mr Mongc foon after 
 performed the fair.e experiment, and obtained a fimilar 
 refult : and it was foon after repeated again by Lavoi- 
 fier and Meufiiicr on a fcale fulHciently large to put the' 
 fact beyond doubt \. \ liu. 
 
 The proofs that water is a compound are of two P- 474- 
 
 kinds ; it has been actually compofcd, and it has been „ •''*J' • 
 , r , i r ' Proofs of 
 
 decompofed. _ the compo- 
 
 With regard to the compofition of water, we fhall fition of 
 relate the celebrated experiment made by Lavoifier and water. 
 Meufnier in the month of February 1 78 ?, in the prefence „ 343 
 of a numerous deputation from the academy of fciences, m^*|j ^r 
 and fo many other fpeftators, that it may be confidered Lavoifier 
 as having been performed in public. Every precaution and Meuf. 
 was taken to enfure fuccefs. The gafes had been pre-''^"^* 
 pared with care, and held for fome time over a folution 
 of potafs, in order to deprive them of any acidity which 
 they might accidentally contain ; and before entering 
 into the glafs globe where they were to be burnt, they 
 were made to pafs over newly calcined potafs, to de- 
 prive them of the water which they might happen to 
 retain in folution. The hydrogen gas had been obtain- 
 ed by pafTing fleam through iron at a white heat ; the 
 oxygen gas was procured from the red oxide of mercu- 
 ry. The combuftion took place in a large glafs globe, 
 into which the gafes were admitted by means of tubes 
 furnilhed with flop-cocks; and the moll ingenious con- 
 trivances were employed to afcertain exactly the quan- 
 tities of each which were confumed(v). The whole 
 machine is defcribed at large by Mr Meufnier in ths 
 Memoirs of the Academy of Sciences for 1782. 
 
 O o The 
 
 (y) A variety of inftruments have been invented by the French ch«niifts for that purpofe. 
 they have denominated Gazometers. 
 
 Thefe inftruments
 
 ?9o 
 
 Water 
 
 CHEMISTRY. 
 
 Part 11. 
 
 344 
 Experi- 
 ment of Le 
 Fevre (le 
 Oineau, 
 
 * 'Journ. de 
 Piyif. 17S8, 
 P-4i7- 
 
 Tlie quantities of gas employed, after dedufting tlie 
 4^2 grains of refKluuin which were not confumed, were 
 2794,76 grains of oxygen gas, and 471,125 of hydro- 
 gen gas. A-fter taking from thefc 32,25 grains, := the 
 humidity of which the oxygen gas was deprived by the 
 c.ilcined potafs, and 44,25 grains, = the weight which 
 the hydrogen loft by the fame procefs, there remains 
 altogether 3188,4 grains of gas. 
 
 The quantity of water obtained amounted to 3219 
 grains; the fpecilic gravity of which was to dillilled wa- 
 ter as 1,0051 to 1. This quantity was 30 grains more 
 than the gas employed. The difference, no doubt, was 
 owing to a fmall error in efiimating the weight of the 
 gafcs; which indeed it is extremely difficult to avoid, as 
 the weight is altered by tlie fmrJIeft difference of tem- 
 perature. This water had a (light fmell, and a tafte 
 ienfibly acid ; it reddened flightly blue paper, and effer- 
 vefced v/ith the carbonat of potafs. 1152 grains of that 
 water being faturated with potafs, and evaporated to dry- 
 ricfs, left 20 grains of a fait which melted on the fire like 
 nitre. It follows from this experiment, that the quantity 
 of acid contained in the whole water would not have 
 been quite fufficient to have formed 56 grains of nitre. 
 
 The refiduum weighed, as has been already obferved, 
 432 grains; its volume was equal to 444 grains of 
 oxygen gas; it was diminiHied by nitrous gas (z) 
 precifely as gas would be which contained 0,24 parts 
 of oxygen ; it rendered lime-water fomewhat turbid, 
 which indicated the prefence of carbonic acid gas. 
 
 From the comparifon of the weights, and volumes of 
 the gafes confumed, it was concluded that water con- 
 fifts of 0,85 parts, by weight, of oxygen, and 0,15 of 
 hydrogen. 
 
 This experiment was foon after repeated by Mr Le 
 Fevre de Gineau upon a ftill larger fcale, and in the 
 prefence of a great number of I'peftators. It continued 
 for no lefs than 12 days, and was performed with the 
 iroft rigorous exaftnefs of which experiments of that 
 nature will admit *. 
 
 The oxygen gas employed, which had been procured 
 from the black oxide of manganefe, occupied the fpace 
 of 3508?,! cubic inches, and weighed 18298,5 grains. 
 
 The hydrogen gas was obtained by diffolving iron in 
 diluted fulphuric acid. Its volume was 7496,7 cubic 
 inches, and its weight 4756,3 grains. 
 
 The two gafcs therefore amounted to 
 From which taking the refiduum after com- 
 
 buition, which amounted to - - 
 
 There remains for the quantity confumed 
 
 23054,8 
 
 2831,0 
 20223,8 
 The water found in the glafs globe after the combuf- 
 tion amounted to - - - 20139,0 
 
 And there were carried off by the refiduum 54,0 
 
 In all . - 20193,0 
 
 Wh'ch is juft 30 grains lefs than the weight of the gafes 
 which difappcared, or -g\-^ part of their weight. This 
 difference arofe from the fame difficulties which attend- 
 ed the experiment of Lavoifier. As the errors are on 
 different fides, we are warranted to conclude that this 
 
 was the cafe, and that it was not owing to any real dif- Water, 
 ference between the gafes and tlie produft. " v * 
 
 The water was examined in the prefence of MefTrs 
 Lavoifier, Le Roi, Monge, Berlhollet, Bayen, and Pel- 
 Ictier. Its fpecific gravity was to that of dillilled wa- 
 ter as 1,001325 to I. It contained no fulphuric nor 
 muriatic acids ; yet it had an acid talle, and converted 
 vegetable blues to a red. 6606 grains of it required 
 for faturation 36 grains of carbonat of potafs, and fur- 
 nilhed by evaporation 26,5 grains of cryilals of nitre. 
 The whole water, therefore, would have required 109,7 
 grains of carbonat of potafs for faturation. 
 
 This water affefted lime-water a littL- ; and it was 
 found that the refiduum of the gas contained fome car- 
 bonic acid gas. This refiduum formed a 1 9th part of 
 the volume of the two gafes employed, and an eight of 
 their weight. It contained 462 grains of carbonic acid 
 gas, or about ^th part ; the reft was azotic gas, with 
 about Tith of oxygen. 
 
 This experiment gave the proportions of oxygen and 
 hydrogen in water as follows : 
 
 Oxygen ... ,848 
 Hydrogen - - ,152 
 
 1,000 
 
 This is fo near the determination of Mr Lavoifier, that 
 it muft be confidered as a very ftrong confirmation of it. 
 
 In the year 1790, another fimilar experiment was£jp^j. 
 performed by Scguin, Fourcroy, and Vauquelin, in thementof 
 prefence of a number of commiflioners appointed by the^^g"'"! 
 Academy of Sciences. Every precaution was taken to ''""■■"■T*- 
 afcertain the quantity of gas employed with the utmoftq„g]j„_ 
 exaftnefs, and to exclude all atmofpherical air as com- 
 pletely as poffible. 
 
 The hydrogen gas was procured by difiolving zinc 
 in fulphuric acid diluted with 7 parts of water. The 
 oxygen gas was obtained by diftilling oxy-muriat of 
 potafs (a). 
 
 The quantity of hydrogen gas employed amounted 
 to 862,178 grains troy. The quantity of oxygen gas 
 amounted to 13475,198 cubic inches (French). Its 
 purity was fuch, that it contained three cubic inches of 
 azotic gas in the 100. The whole gas, therefore, con- 
 tained 404,256 cubic inches. There were likewife in 
 the glafs veffcl in which the combuftion took place 15 
 cubic inches (French) of almofpheric air, which con- 
 fifted of II cubic inches of azotic and four of oxygen 
 gas. So that the whole oxygen gas employed amount- 
 ed to I ^074,942 cubic inches ; and it contained be- 
 fides 415,256 cubic inches of azotic gas. They afcer- 
 tained by experiment, that a cubic inch of this oxygen 
 gas, thus diluted with -^-^ of azot, weighed ,4040 of 
 a grain troy. Now, according to the experiments of 
 Lavoifier, a cubic inch (French) of azotic gas weighs 
 only ,3646 of a grain troy. Confequently the weight 
 of pure oxygen gas is greater than ,4040 ; and by cal- 
 culation they Ihewed it to amount to ,4051 of a grain 
 troy. The weight of the whole oxygen gas employed, 
 therefore, was 5296,659 grains troy ; and that of the 
 azotic gas mixed with it 151,402 grains troy. 
 
 The 
 
 I 
 
 (z) This gas (hall be afterwards defcribed. It has the property of abforbing almoft inftantaneoufly the oxy- 
 gen gas with which it comes into contaft. It is therefore often ufed, in order to difcover how much oxygen 
 gas exifts in any mixture. 
 
 ( A ) A fait compofed of oxy-muriatic acid aod potafs.
 
 'art if. 
 
 Water. 
 
 C H E M 
 
 The cotnbuftion continued 185 hours; ami during 
 ■' all that time our philofophers never quitted the labora- 
 tory. Tlic flame was exceedingly fmall, and the heat 
 produced by no means great. I'liis was owing to the 
 very fniall itream of hydrogen, which was conilantly 
 flowing into the vcird. 
 
 The water obtained amounted to 5943,798 grains 
 troy, or 12 oz. 7 dwts. and 15,798 grains. It exhi- 
 bited no mark of acidity, and appeared in every relpcdt 
 to be pure water. Its Ipecitlc gravity was to that of 
 diftilled water as 1S671 to 18670; or nearly as 1,000053 
 to 1. 
 
 The refiduum of gas in the velTel after combuftioa 
 amounted to 987 cubic inches (French) ; and on be- 
 ing examined, was found to confill of the following 
 quantities of gafes : 
 
 Azotic gas, ..... 467 cubic inches. 
 
 Carbonic acid gas, ... 39 
 
 Oxygen gas, 465 
 
 Hydrogen gas, .... 16 
 
 Total - - 987 
 
 The tv fight of which is as foUoius : 
 Azotic gas, ...... 170,258 gr. troy. 
 
 Carbonic acid gas, .... 23,306 
 
 Oxygen gas, ...... 188,371 
 
 Hydrogen gas, o»530 
 
 Total, - - 382,465 
 Now the weight of the whole gafes 
 
 employed was, .... 6310,239 gr. troy. 
 That of the water obtained, and 
 
 of the refiduum, .... 6326,263 
 
 852,693 gr. troy. 
 5093,940 
 
 Or - 16,024 grains 
 
 more than had been employed. Tlu's fmall quantity 
 muft have been owing to common air remaining in the 
 tubes, and other parts of the apparatus, in fpite of all 
 the precautions that were taken to prevent it ; if it did 
 not rather proceed from unavoidable errors in their va- 
 luations. Gr. Troy 
 The quantity of azotic gas introduced was 151,178 
 The quantity found in the refiduum was 170,258 
 
 There was therefore a furplus of - . - 19,080 gr. 
 
 As fufficient precautions had been faken to prevent 
 the iniroduftion of carbonic acid gas, the quantity 
 found in the refiduum muft have been formed during the 
 procefs. There muft therefore have been a fmall quan- 
 tity of carbon introduced. Now zinc often contains 
 carbon, and hydrogen has the property of diffolving 
 carbon : probably, then, the carbon was introduced in 
 this manner. The carbonic acid found in the refiduum 
 amounted to 23,3:6 grains, which, according to La- 
 voilier's calculation, is compofed of 8,958 grains of car- 
 bon, and 14,348 grains of oxygen. 
 
 Subtrading thefe 8,958 grains of carbon, and the 
 ,530 of a grain of hydrogen, which remained in the velfcl, 
 from the total of hydrogen introduced, there will remain 
 852,690 grains for the hydrogen that difappeared. 
 
 Mubtrafting the 14,348 grains of oxygen which en- 
 tered into the compofition of the carbonic acid, and the 
 refidoum of oxygen, which amounted to 188,371 grains, 
 the quantity of oxygen that difappeartd will amount 
 to 5093,940 grains. 
 
 5946,630 
 
 594.^7y*< 
 
 I S T R Y. 
 
 Hydrogen that difappeared, 
 0>^Yd^"> 
 
 Total, - 
 
 Quantity of water obtained. 
 
 Which is lefs than the gafes 
 
 confumed by . - . . . 2,832 grains *., ^^^^^ 
 
 Such are the principal experiments upon which the c/./«i. iiii. 
 opinion is founded tiut water is a compound. Let usJii- 
 examine tliem, and fee wlie'.her they are fufficient to 
 ellablifli that opinion. The circumftances whicli chiefly 
 claim our attention, and which have been chiefly infift- 
 ed on, are thefe : 
 
 1. The whole of the gafes was not confumed. Obfcdion? 
 
 2. In the refiduum were .''ound feveral fubftancestn the com- 
 which were not introduced, and which mull therefore pcfi""" "f 
 have been formed during the combuftion. water exa. 
 
 3. The water obtained was feldom perfeflly pure.*"'"^ 
 It generally contained fome nitric acid. 
 
 4. As only part of the gafes were confumed, and as 
 all gafes contain water in them, might not the gas 
 which difappeared have been employed in forming the 
 other fubftances found in the refiduum ? and might not 
 the water obtained have been merely what was former. 
 ly diflolved in the gafes, and which had been precipi- 
 tated during the experiment ? 
 
 That the whole of the gafes was not confumed will 
 not furprife us, if we recoiled that it is impoffible for 
 that to take place, allowing them to be perfedfly pure, 
 except they be mixed in precifely the proper propor. 
 tions ; and not even then, except every particle oftheui 
 could be raifed to the proper temperature. Nov/ how 
 can this be done in experiments of that nature ? 
 
 But how is it pofTible to procure a large quantity of 
 gas completely pure ? And fuppofing it were poflible, 
 how can every particle of atmofpiieric air be excluded ? 
 In the laft experiment, notwithilanding every prccau. 
 tion, 15 cubic inches (French) were admitted ; and 
 there is reafon to believe from the refults, that the quan- 
 tity was even confiderably greater than this. But if 
 any atmofpheric air be admitted, there muft be a refi. 
 duum of azotic gas. 
 
 In the firft experiment, it had been previoufly afcer. 
 tained that the oxygen gas employed contained Ti'h 
 of azotic, or about 233,05 grains ; and the refiduum 
 contained at moft 329,1 grains, or 96,05 grains more 
 than what had for certain pre-exifted in the gafes. 
 
 In the fecond experiment, the azot in the refiduum 
 amounted at moft to \t]\ of the oxygen gas employed. 
 But the oxygen was procured from the black oxide of 
 manganefe, which always yields a quantity of azot as 
 well as of carbonic acid. It has been afcertained, that 
 the azot, mixed with oxygen gas procured in that man- 
 ner, often exceeds .Jth. 
 
 Ill tlie third experiment, the azotic gas found in the 
 refiduum amounted to 170,258 grains; and the quanli. 
 ty contained in the gafes before combuftion amounted 
 to 151,178 grains : the furplus, therefore, amounted to 
 19,0?^ grains. 
 
 Now, is it not much more probable that thefe incon- 
 fiderablc quantities of azot, which in the laft experi- 
 ment amounted to no more than -j-y-j- part by v/eight 
 of the whole gas employed, pre-exllled in the gafes be- 
 fore the combuftion began, thougii their extreme ml- 
 nutcnefs prevented them from being difcovered, than 
 that they v/ere formed during the experiment : a fup- 
 O o 2 pofition
 
 CHEMISTRY. 
 
 Part IT. 
 
 • Ann. dd 
 Cbim, iii. 
 91. 
 
 \ A'nn. de 
 Cbim. ix. 
 
 48. 
 
 t Phil. 
 "Tranf. 
 1784. 
 
 pofitiotl which is direftly contraJifted by a great num. 
 ber of well ulcertained facls. 
 
 As to the carbonic acid gas, which in the fecond ex- 
 periment amounted to ,V''^ o*" '^e gafcs employed, it 
 was evidently derived from the raauganefe, which al- 
 nioft conrtaiitly contains it. And when carbonic acid 
 is once mixed witli oxygen, it is difficnlt to feparate it 
 by means of lime-water, except a large quantity be ufed, 
 as MrCavendidi Irs well obfervcd. The i-eafon is, that 
 oxygen gas has the property of diffblving carbonic acid, 
 as Mr Welter has remarked *. Mr le Fcvre de Gineau 
 afcertaiucd byexperiment, that 1 8-0 cubic inches of oxy- 
 gen gas, which did not affeft lime-water, loll between 
 y-j-th and ^j'^-th "f 'ts weight when Wiiflied in nnlk of 
 lime (b). 
 
 In a fecond experiment, he previondy waflied the two 
 gafes in milk of lime, and the refiduum after combuftion 
 contained no carbonic acid gas. In a third experiment 
 he wafiied only the oxygen, and obtained products e- 
 qually free from carbonic acid. It is certain, then, that 
 the carbonic acid is but an accidental mixture. As to the 
 carbonic acid of the third experiment above related, 
 which amounted only to yj-^ P^i't of the gafcs employ- 
 ed, the fource of it has been already pointed out. 
 
 As to the nitric acid, the quantity of nitre obtained 
 iu Mr Lavoifier's experiment was 56 grains ; which, ac- 
 cording to Mr Kirwan's calculation, contain 30,156 
 grains of nitric acid ; a quantity coufidcrably lefs than 
 -j-lpth part of the gafes which difappeared. In the fe- 
 cond experiment, the nitre obtained amounted to 80,7 
 grains ; which, according to Kirwan, contain 43,456 
 grains of nitric acid, or lefs than jf^rth part of the gafes 
 confumed. Now, as nitric acid is compofed of oxygen 
 and azot, both of which were prefent in the vefTcl, it is 
 eafy to fee how it was produced. And that its pro- 
 duftion is merely accidental, and not neceflary, is evi- 
 dent from the laft experiment, in which no nitric acid 
 was formed. It has been afcertained, indeed, that the 
 formation of this acid during thefe experiments is quite 
 arbitrary. It never is formed when the combultion 
 goes on fo flowly as to produce but little heat, as Se- 
 guin has afcertained f ; becaufe oxygen and azot do 
 not combine except at a high temperature. Nor is it 
 formed even at a high temperature, as Mr Cavendiih 
 has proved :j:, except there be a deficiency of hydrogen; 
 becauie hydrogen has a ftronger affinity for oxygen 
 than azot has. 
 
 The q_uantity of water obtained in the firft expe- 
 riment was juft ^o grains more than the weight of the 
 gafes whicii had difappeared : the water obtained in 
 the fecond was precifely 30 grains lefs than the gafes 
 confumed : and in the third experiment, the difference 
 was only 16 grains. The quantities of gas operated 
 
 upon were large ; in all of llie experiments fevcral thou- Water, 
 fand grains, and in one ot them above' 20 thoufand. —— v"— ' 
 Now, how is it poffible that the water produced (liould 
 correfpond fo exadly with the gafes confumed (for the 
 dlfferenccB are fo fmall as not to merit any attention), 
 uiiltfs the water had been formed by the combination 
 of thefe gafes ? 
 
 Dr PrielUey, however, who made a great many ex- 
 periments on this lubjeft, drew from them a very diffe- 
 rent conclufion ; and thought he had proved, that du- 
 ring the combultion the two gafes combined, and that 
 the combination was nitric acid. This theory was adopt- 
 ed, or rather it was fuggelled, by Mr Keir, who has 
 fuppoited it with a great deal of ingenuity *. * A' ' '• 
 
 Let us examine thefe experiments of Dr Pricffley f , D/a'w.cv, 
 and fee whether they warrant the conclufions he has art. Kitiy.. 
 drawn from them. The gafes were exploded in velfels'^";'; 
 of copper. He found that the quantity of water ob--j-^^„V 
 tained was always hj's than that of the gafes which hciySS. 
 had ufed. He obtained alfo a confidcrable quantity of 
 nitric acid. In the experiment made on the largeft 
 quantity of the gafes, and from v.-hich he draws his 
 conclufions, the quantity of liquid obtained amounted 
 to 442 grains. This liquid was examined by Mr Keir. 
 It was of a green colour, 72 grains of brown oxide of 
 copper were depofited in it, and it contained a folution 
 of nitrat of copper (copper combined with nitric acid). 
 Mr Keir analyied this liquor : It confilled of pure wa- 
 ter and nitrat of copper ; and Mr Keir concluded that 
 the nitric acii formed amounted to ^^Xh. of the oxygen 
 gas employed. Mr Berthollet, however, has (hewn that 
 it could not have amounted to more than -^-il\\ part J. { Arm da 
 Let us fuppofe, however, that it amounted to ^ gth. A Chim. iiu 
 quantity of oxygen and hydrogen gas has difappeared ; 
 Wliat has become of them ? They have combined, fays 
 Dr Prieftley, and formed nitric acid. This nitric acid 
 is only •j'o'-h "f their weight : Dr Prieftley fuppofes, 
 however, that it contains the whole oxygen and hydro- 
 gen that exifted in thefe gaies, and that all the reft of 
 the weight of thefe gafes was owing to a quantity of 
 water which they had held in folution. Oxygen gas, 
 then (for we {hall negleft the hydrogen, which Dr 
 Prieftley was not able to bring into view at all), is com- 
 pofed of one part of oxygen and 19 of water. Where 
 is the proof of this ? Dr Prieftley informs us, that he 
 afcertained by experiment that half the weight of car- 
 bonic acid gas was pure water. Suppofing the experi- 
 ment accurate (c), what can be concluded from it? 
 Surely to bring it forward in proof, that oxygen gas 
 confiits of 4sth parts, or almoft wholly of water, is 
 downright trifling. It is impoffible, therefore, from 
 Dr Prieftley's experiments, allowing his fuppofitlons and 
 conjedlures their ulmoft. force, to account for the difap- 
 
 pearing 
 
 \ 
 
 (b) I^ime mixed with water till it is of the thicknefs of milk, or rather ai cream. 
 
 (c) He informs us that the carbonat of barytes does not yield its carbonic acid by means of heat (this Dr 
 Hope has Ihewn to be a miftake) ; but that, when the vapours of water are palled over it, the gas is difengaged: 
 and he determines, by the water miffing, how much has combined with the gas. According to him, 60 grains, 
 of water enter into the compofition of 147 grains of gas. But, befides affigning too fmall a weight to the gas, 
 he forgot that its temperature was high, and that therefore it was capable of combining with much more water 
 than in its ufual ftate : nor did he aicertain whether more of this water was depofited on the veffels ; and yet, 
 by neglefting this precaution, Morveau has Ihewn that Mr Kirwan, in a fimilar experiment, obtained a refult 
 nine times greater than it ought to have been. EncycL Method. Chim. art. Air.
 
 Partir. C H E M 
 
 Water, pcaving of die two gafi'S, or the appearance of tlie \va- 
 '"""*'""' tcr, without admitting that this liquid was adually 
 compoffd of oxygen and hydrogen. H we add to this, 
 that no oxygen gas has hitherto (as far as we know at 
 Icall) been procured abfokitcly free from fome admix- 
 ture of azot, and that his oxygen was always procured 
 lither from red oxide of lead, or from black oxide of 
 manganefe, or red oxide of mercury, all of which fulv 
 llances yield a conlldcrable proportion of azot ; that in 
 one experiment, in which he obferves that his oxygen was 
 very pure, as it had been obtained trom red oxide ot mer- 
 cury, Mr Bcrtiiollet (d) afcerfaincd, by actually making 
 the experiment, that part of the very fatm oxide which 
 Dr Priellley liad employed yielded a gas, -jd of which 
 was azot * ; if we add, that it has been proved beyond 
 the polFibility of doubt, and to Dr Pricl\ley's own fa- 
 tisfavlion, that nitric acid is compofcd cf oxygen and 
 azot — we fliall find it no diflicult matter to explain the 
 origin of that acid in Dr Prieltley's experiments : and 
 if we recolledl that in Seguin's experiment, upon a 
 much larger' fcale indeed than Dr Priefllty's, no nitric 
 acid at all was formed, it will be impoffible for us to 
 believe for a moment that the compound formed by 
 oxygen and hydrogen is nitric acid. Thus Dr Prielt- 
 ley's experiments rather confirm than deftrov the theo- 
 ry of the compofition of water. We obtain from them, 
 however, one curious piece of information, that the pre- 
 fence of copper increafes the quantity of nitric acid 
 formed. This curious fa£l, Vv'itli a variety of others of 
 a fimilar nature, will perhaps afterwards claim our at- 
 tention ; but at prefent we muft confider another theory 
 which this phenomenon fuggeiled, and which was firll 
 propoiVd, we believe, by Mr de la Metherie (e). 
 
 Had tlie French chemills, it has been faid, employed 
 copper veffels in their experiments, they would have ob- 
 tained three times the quantity of nitric acid. This 
 acid, therefore, mull in their experiments have been de- 
 compofed, after having been formed, for want of a bafe 
 to combine with ; and the azot which appeared in the 
 refiduum was owing to this decompofition. Hydrogen 
 and oxygen, therefore, do not form water, but azot ( f). 
 Let us examine the experiment of Mr Le Fevre by this 
 theory, as the quantity of azot was accurately afcer- 
 tained. The nitric acid obtained amounted to 4:1,456 
 grains; three times that quantity is 130,^65 grains, 
 into which 230 54 grains of gas were converted ; which 
 is impoffible. Or even fuppofing that the decompofition 
 had been going on during the whole experiment, which 
 is diredlly contrary to Dr PrielUey's experiments, and 
 which there is no reafon whatever to fnppofe, but every 
 reafon againft — ftill the whole azot amounted only to 
 •^th of the quantity of gas employed, allowing this gas 
 
 I S T R Y. 293 
 
 to have contained no azot, which was evidently not the Wattr. 
 cafe. It appears, then, that this hypothefis, even if it ' v '' 
 could be admitted, would be totally inadequate to ac- 
 count h)r the phenomena. liut if we were to examine 
 it by Mr Seguin's experiment, its abfurdity would be 
 Hill more glaring. In that experiment the azotic gas 
 amounted to only 19 grains, and the quantity of gas 
 which difappcared was 5946 grains: fo that were the 
 hypothefis true, oxygen and hydrogen gas would con- 
 fill of one part of oxygen and hydrogen and 312 parts 
 of water ; a fuppofition fo enormoullv abfurd, that it ia 
 impoffible for any perfon even to advance it. 
 
 It is impofTiblc, therefore, for the pheriomena which 
 attend the combufiion of oxygen and hydrogen gas to 
 be accounted for in any way confillent witli common 
 fenfe, except we fuppofe that water is formed. 
 
 But the experiments above related, conclufivc as they Dccompo. 
 appear, are not the only ones by which this important fition of 
 f;id has been afcertaincJ. Melfrs Van Trooftwyk and*^'"- 
 Dieman, affifted by Mr Cuthbertfon, filled a fmall glafs 
 tube, -^th ot an inch in diameter and 12 inches long, 
 with diililled water. One end of this tube was fealed 
 hermetically ; but, at the fame time, a fmall gold wire 
 had been pafl'ed through it. Another wire pafl'ed thro' 
 the open end of the tube, and could be fixed at greater 
 or fmalltr dilhmces from the firfl wive. By means of 
 thefe wires, they made a great number of tleftrical ex- 
 plofions pats through the water. Bubbles of air ap- 
 peared at every explofion, and collected at the top of 
 the tube. AVhen eleftric fparks were pafled through this 
 air, it exploded and dif<)ppeared alnioft completely. It 
 mull therefore have confilted of a mixture of oxygen 
 and hydrogen gas, and this gas mull have been formed 
 by the decompofition of the water : for they had taken 
 care to deprive the water before hand of all its air, and 
 they ufed every precaution to prevent the accefs of at- 
 mofpherical air; and, befides, the quantity of gas pro- 
 duced did not diminifh, but rather increafed, by con. 
 tinning to operate a number of times upon the fame 
 water, whicli could not have been the cafe had it been 
 merely air difTolved in water : nor would atmofpherical 
 air have exploded and left only a very fmall refiduum, 
 not more than -g-'o-th part. They had taken care alfo 
 to prove that the eletlric fpark did not contribute to 
 form hydrogen gas ; for on paifing it through fulphu- 
 ric and nitric acids, the produft was not hydrogen, but 
 oxygen gas *. _ « y,„,_ j^ 
 
 Thefe experiments have been fince repeated by Dr Phyf. xhv. 
 Pearfon, afliftcd by Mr Cuthbertfon. He produced, 3^9- 
 by means of eleftricity, quantities of gas from water, 
 amounting to 56,5488 cubes of ^'sth of an inch each ; 
 on nitrous gas being added to which, it fulfercd a dimi- 
 nution 
 
 (o) Mr Berthollet had fupplied Dr Priellley with the oxide. He had received two ounces of it from Mr Le 
 Blanc, one of which he fent to Dr Priellley, and the other he referved. 
 
 (e) Another favourite theory of La Metherie was, that gafes themfelves are dcllitute of gravity, and that 
 they owe their whole weight to the water with which they are combined : that during combuftion the water of 
 the two gafes is depofited ; and that the gafes themfelves efcape through the veflel and are loll. He complains 
 bitterly that this theory had never been noticed by his antagonifts ; as if it were necelTary to refute a hypothefis 
 which is not fupported by any proof whatever, and as if it had not been proved that oxygen increafes the weight 
 of metals, and confequently pofTeires gravity. 
 
 (f) This, as has been formerly explained, was the original opinion of Dr Priellley ; to which, though he does 
 not explain himfelf fully, he evidently Hill adheres. There is then no difference betweea his theory and this, 
 except what relates to the decoropofition of the nitric acid.
 
 'j'Urnd, i. 
 
 £94 C H E M I 
 
 Alcolo!. nution of bulk, nnd nitrous acid sppeaied to have been 
 *■""* formed : It muft therefore liave contained oxygen gas. 
 
 When oxygen gas was added to the remainder, and 
 an eleftric fpaik paflld through it, a diminution took 
 place pricifely as wlien oxygen and hydrogen gas are 
 mixed : It mull therefore have contained hydrogen. 
 When ai\ eledtric fpark was pafll-d tlirough the gas 
 thus produced from water, the gas difappeared, being no 
 \^''"'"^/''''Aa\\\.\ converted into water*. 
 
 Such are the proofs by which the compound nature 
 of water is afcertained ; and we do not beheve that any 
 phyfic-al fact whatever can be produced which is fup- 
 ported by more complete evidence. 
 
 But wliat becomes of the caloric which was previ- 
 oufly combined with thefe gafes ? It pafFes through the 
 vefiel and is loft, and its weight is too inconfiderable to 
 make any fenfible variation in the cjuantity of the pro- 
 diift. If we were to judge from analogy, we would 
 conclude, that the oxygen and hydrogen, while in the 
 flate of gas, are probably fomewhat lighter than after 
 they are condenfed into water ; but the difference, if it 
 exifts, can fcarcely be fenfible. 
 
 Water is capable of combining with a vaft number of 
 _ . , f'ibltances: all bodies, indeed, which are foluble in wa- 
 waier ^^'^ form a chemical union with it. 
 
 Its afGnity for other bodies is doubtlefs various, tho' 
 we have no method of afcertaining this difference, ex- 
 cept in thofe bodies which have no affinity, or but a 
 very fmall affinity, for each other ; and it is only in 
 a few even of thefe that this difference can be afcer- 
 tained. If muriat of barytes be poured into lime-wa- 
 ter, the lime is precipitated, owing, no doubt, to the fu- 
 perior affinity of tlie muriat for water. Several very 
 curious inftances of the affinity of different falts for wa- 
 ter have been mentioned by Mr Quatreraere Dijonval. 
 When the folutions of nitrat of lime and nitrat of mag- 
 iiefia in water are mixed together, the nitrat of magne- 
 fia is precipitated. Muriat of magnefia is alfo precipi- 
 tated by muriat of lime, and fulphat of magnefia by 
 fulphat of lime ; fo that it would feem that the falts 
 which have magnefia for their bafis, have a lefs affinity 
 ■; 7«r/rir. ii for water than thofe whofe balls is lime -f. 
 Fhyf.w.i. Water has the property of diffolving oxygen gas. 
 If a quantity of common air be confined for fome time 
 above water, the whole cf the oxygen is abt'orbed, and 
 nothing but the azotic gas remains. This faft was firlt 
 obferved by Mr Scheele. 
 
 S T R Y. 
 
 Part If. 
 
 34S 
 
 Combina- 
 tion and 
 
 349 
 
 CiiAF. II. 0/" Alcohol. 
 
 "Dilcdve.-y WiNE has been known from the earlieft ages. The 
 of alcohol. Scriptures inform us, that Noah planted a vineyard 
 and drank wine; and the heathen writers are unanimous 
 in afcribing the invention of this liquor to their earlieft 
 kings and heroes. Beer, too, fecms to have been dilco- 
 vered at a very remote period. It was in common ule 
 iLib.ii. in Egypt in the time of Herodotus j. Tacitus informs 
 { d! Afs. us, that it was the drink of the Germans^. Whether 
 rU-.drm'. the ancients had any method of procuring ardent fpirits 
 ch. xxiii. from thefe or any other liquors, does not appear. The 
 Greeks and Romans feem to have been ignorant of ar- 
 dent fpirits altogether, at leafl we can difcover no tra- 
 ces of any fuch liquor in their writings. But among 
 the northern nations of Europe, into.sicating liquors 
 were in ufe from the earlieft ages. Whether thefe li 
 
 I 
 
 quors rcfembled the beer of the Germans, we do not Alcohol, 
 know. It is certain, at leaft, that the method of procu- ""^^ ' 
 ring ardent fpirits by dilhllation was known in the dark 
 ages; and it is more tl-.an piobable that it was praftifed 
 in the north of EUrope much earlier. They are mention- 
 ed exjirefsly by 'I hadda^us, Villanovanu's, and LuUy *. ^'f.?- 4''i 
 
 Ardent fpirits, fuch as brandy, for inftance, rum, and ''',■ 
 
 whilky, conlift almoft entirely of three ingredients, wa- Method of 
 ter, claJ.'ul or fpir'it of iv'ine, to which they owe tlieirprocuri..g 
 ftrength, and a Imall quantity of a peculiar oil, to which"* 
 they owe their tiavour. 
 
 'l"he alcohol may be feparated from the water by the 
 following proccls. Into the whiUcy or other ardent fpi- 
 rit a quantity of potals is to be put, which has jull imme- 
 diately before been expofed for about half an hour in a 
 crucible to a red heat, in order to deprive it of nioifture. 
 Potafs in this ftate has a ftrong attraction for water; it 
 accordingly combines with the water of the fpirit, and 
 the folution of potafs thus formed finks to the bottom of 
 the veffcl, and the alcohol, which is lighter, fwims over 
 it, and may calily be decanted off; or, what is perhaps 
 better, the folution of potals may be drawn off from be- 
 low it by means of a ftop.cock placed at the bottom of 
 the veffcl. It is impoffible to fix the quantity of potafs 
 which ought to be ufcd, becaufe that muft depend en- 
 tirely on the ftrength of the fpirit ; but it is of no con- 
 fequence though the potafs employed be a little more 
 than enough. The alcohol thus obtained contains a 
 little potafs diffolved, wliich may be feparated by dillil- 
 ling it in a water bath with a very fmall heat. The al- 
 cohol paffes over, and leaves the potafs behind. It is 
 proper not to dillil to drynefs. This procefs is firft 
 mentioned by LuUy. Alcohol may be obtained in the 
 fame manner from wine and from beer ; which liquids 
 owe their ilrength entirely to the quantity of that fub- 
 ftance which they contain. _, 
 
 Alcohol is a tranfpareut liquor, colourlefs like water, it, proper- ^ 
 of a pleafant fmell, and a ftrong penetrating agreeableties. 
 tafte. 
 
 It is exceedingly fluid, and has never been frozen, 
 though it has been expofed to a cold fo great that the 
 thermomer ftood at — 69'^ -f . \ At V.ud- 
 
 Its fpecific gravity when pure is about 0,800. />»'' "^'S' 
 
 It is exceedingly volatile, boiling at the temperature 
 of 176°; in which heat it affumes the form of an elaftic 
 fluid, capable of refilling the preffure of the atmofphere, 
 but which condenfes again into alcohol when that tem- 
 perature is reduced. In a vacuum it boils at 56°, and 
 exhibits the fame phenomena: fo that were it not for 
 the preflure of the atmofphere, alcohol would always 
 exifl in the form of an clallic fluid, as tranfparent and 
 invifible as common air. This fubjeft was firft exa- 
 mined with attention by Mr Lavoifier J. The fadf, J 7""'''- ^ 
 however, had been known long before, rb\J.\^^•■,• 
 
 Alcohol has a flrong affinity for water, and is mif- 
 cible with it in all proportions. The fpecific gravity of 
 all the different mixtures, in every proportion, and in 
 all the different degrees of temperature, from 32" to 
 lOO", has been lately afcertained with great accuracy by 
 Sir Charles Blagden and Mr Gilpin. But as a very full 
 account of thefe interefting experiments has been given 
 in the Encyclopsedia in the article Spiritdous Liquors, 
 we do not think ourfelves at liberty to repeat it here. 
 
 If alcohol be fet on fire, it burns all away with 
 a blue flame without leaving any refiduum. Boerhaave 
 
 obferved,
 
 Part II. 
 
 ,1731 
 
 C H E M 
 
 obfcrved, tlmt when the vapour whicli efcapes during 
 ' this combiillion is collcfted in proper veflcls, it is found 
 to conlllt of nothing but water. Junker had made tlie 
 fame rcmarlc ; and Dr Blacli fufpcfted, from liis own 
 obfcrvations, that tlie quantity of water obtained, if 
 properly collefted, exceeded tlie weight of the alcohol 
 confumed. This obfervation was cim firmed by Lavoifier; 
 who found that the water pruJuccd during the corn- 
 bullion of alcohol exceeded tiie alcohol confumed by 
 about 4th part*. 
 
 Different opinions were entertained by chemifts about 
 the nature ot alcohol. Stahl thought that it was com- 
 pofed of a very light oil, united by means of an acid 
 to a quantity of water. According to Junker, it was 
 compofcd of phlogifton, combined with water by means 
 of an acid. Cartheufer, on the other hand, affirmed, 
 that it contained no acid, and that it was nothing elfe 
 than pure phlogifton ar\d water. But thefe hypothefes 
 were mere aflertions fupported by no proof whatever. 
 Lavoiller was the firft who attempted to aualyfc it. 
 
 He fet fire to a quantity of alcohol in clofe vefttls, 
 by means of the following apparatus : BCDE (lig. 6.) 
 is a veflel of marble filled with mercury. A is a ilrong 
 glafs veflel placed over it, filled with common air, and 
 capable of containing about 15 pints (Fiench). Into 
 this vcfTel is put the lamp R filled with alcohol, the 
 weight of which has been exaftly determined. On the 
 wick of the lamp is put a fmall particle of phofphorus. 
 The mercury is drawn up by futtio', to the height IH. 
 This glafs communicates by m.eans of the pipe LK with 
 another glafs veflel S filled with oxygen gas, and placed 
 over a veflel of water T. This communication may be 
 fliut up at picafure by means of the ilop-cock M. 
 
 Things being thus difpofed, a crooked red-hot iron 
 wire is thruil up through the mercury, and made to 
 touch the phofphorus. This inftantly kindles the wick, 
 and the alcohol burns. As foon as the flame begins to 
 grow dim, the itop-cock is turned, and a communica- 
 tion opened between the veflels S and A ; a quantity of 
 oxygen gas ruflies in, and rtilores the brightncis of the 
 flame. By repeating this occafionally, the alcohol may 
 be kept burning for fume time. It goes out, however, 
 at lart, notwithllandiag the admiflion of oxygen gas. 
 
 The refuk of this experiment, which Mr Lavoifier 
 repeated a great number of times, was as follows : 
 
 The quantity of alcohol confumed amounted to 
 76,7083 grains troy. 
 
 The oxygen gas confumed amounted to 266,82 cu- 
 bic inches, and weighed 90,^06 grains troy. 
 
 The whole weight of the fubltances confumed, there- 
 fore, amounted to 167,2143 grains.. 
 
 After the combuftion, there were found in the glafs 
 veflel 115,41 cubic inches of carbonic acid gas, the 
 weight of which was 78,1 192 grains troy. Tliere was 
 like wife found a confiderable quantity of water in the 
 veffel, but it was not pofllble to collttf and weigh it, 
 Mr Lavoifier, however, ellinnted its weight at 89,095 1 
 gi'ains ; as he concluded, witii realon, that the whole 
 of the fubilances employed were ftiU in the veflel. Now 
 the whole contents of the veflel coniilled of carbonic 
 acid gas and water; therefore the carbonic acid gas 
 and water together mull be equal to the oxygen gas- 
 and alcohol which had been confumed. 
 
 But 78,1192 grains of carbonic acid g^s contain,, 
 according to Mr Lavoifier's calculationf , 5 5,279 grain.s 
 of oxygen ; 90,506 grains, however, of oxygen gas had 
 
 I S T R Y. 295 
 
 difappeared ; therefore 35,227 grains mull have been Alcoh.l. 
 em])loyed in forming water. » ' 
 
 35,227 grains of oxygen gas require, in order to 
 form water, 6,058 grains of hydrogen gas ; and the 
 quantity of water iormed by this combination is 41,265 
 grains. But there were found 89,09,- grains of water 
 in the glafs veflel ; therefore 47,83 grains of v/ater mull 
 have exitted ready formed in tlie alcohol. 
 
 It foUows from all thefe data, that the 76,7083 grains 
 of alcohol, confumed during the combuftion, were com- 
 poltd of 
 
 22,840 Carbon, 
 
 6,038 Hydrogen, 
 47,830 Water. 
 
 76,7* * ^"'- 
 
 Such were the confequences which Mr Lavoifier drew " ' 
 from his analyfis. He acknowledged, however, that 
 there were two fources of uncertainty, which rendered 
 his conclufions not altogetlier to be depended upon. 
 The firll was, that he had no method of determining the 
 quantity of alcohol confumed, except by the difference 
 of weight in the lamp before and after combufl;ion ; and 
 that therefore a quantity might have evaporated with- 
 out combuftion, which, however, would be taken into 
 the fum of the alcohol confumed. But this error could 
 not have been great ; for if a confiderable quaiuitv of 
 alcohol had exifted in the ftate of vapour in the veflel, 
 an explofion would certainly have taken place. The 
 other fource of error was, that the quantity of water 
 was not known by aftual weight, but by calculation. 354 
 
 To this we may add, that Mr Lavoifier was not war-Ingre.Hipntr 
 ranted to conclude from his experiment, that the water"^^'"^"'' 
 found in the veflel, which had not been formed by the 
 oxygen gas ufed, had exifled in the alcohol in the ftate 
 of water : he was intitled to conclude from his dat.i, that 
 the ingredients of that water exifted in the alcohol be- 
 fore combuftion ; but not that Vtity were aclually com- * 
 bined in the fttte of water, becaufe that combination 
 might have taken place, and in all probability did part- 
 ly take place, during the combuftion. It follows, theie. 
 fore, from Mr Lavoifier's experiments, that alcohol, 
 fuppofing he ufed it perfedlly pure, which is not pre-- 
 bable, is compofed of 
 
 0,2988 parts carbon, 
 
 0,1840 parts hydrogen,. 
 
 0,5 1 7 2 parts oxygen, 
 
 I,COOO' 
 
 But it gives us no information whatever of the manner' 
 in which thefe ingredients are combined. That alcohoii 
 contains oxygen, h.is been proved by a very ingenious 
 fet of experiments performed by Mefirs Fourcroy and' 
 Vauquelin. When equal parts of alcohol and fulphnric 
 acid are mixed together, a quantity of caloric in difcn- 
 gagcd, f'lfTicient to elev.ite the temperature of the mix. 
 ture to 190°. Bubbles of air are emitted, the liq'vir be- 
 comes turbid, aifumcs an opal colour, and atthetiid of 
 a few days a deep red. When examined, the fulphuiio 
 acid is found to have fuQ"ered no change ; but the alo- 
 hol is decompofed, partly converted into water and part- 
 ly into ether, a fubftance which we fliall dcfcribc imme- 
 diately. Now, it is evident that the alcohol could not 
 have been converted into water unlefs it had contained 
 oxygen*. * XL-W- 
 
 When equal parts of fulphuric acid and alcohol are/""''.?"'""- 
 mixed tagether and heat applied, tiie mixture boils at""'"'" ^S**" 
 
 aoS",.
 
 acjG 
 
 Akohcl, 
 
 355 
 Ether. 
 
 3S6 
 
 Its proper- 
 tiis. 
 
 * Count de 
 J^auraguais, 
 
 357 
 Theory of 
 its forma- 
 Cion. 
 
 C H E M I 
 
 ZoS", and a liquid <;qual to half the v^;iglit of the alco- 
 hol comes over into the receiver. This liquid is ether. 
 
 Ether is obfcurely hinted at in feme of the older che- 
 mical authors, but little attention was paid to it till a 
 paper appeared in the Philofop^ieid Tranfaftlons for 
 173c, written by a German, wiio called himfelf Frobe- 
 Tiius (g), containing a number of experiments on it. 
 In tliis paper it full received the name of et/ier. 
 
 Ether is limpid and colourlefs, of a very fragrant 
 fmcU, aiid a hot pungent talle. Its fpecific gravity is 
 0,73911. It is exceedingly volatile, boiling in the open 
 air at 98", and in a vacuum at — 20'. Were it not 
 therefore for the prelTure of the atmofphere, it would 
 always exill in a gafeous ftate. Ether u::ites with wa- 
 ter in the proportion of ten parts of the latter to one of 
 the former". It is exceedingly inflammable, and, when 
 kindled in the Hate of vapour, burns with rapidity, or 
 rather explodes, if it be mixed with oxygen gas. 
 
 Chemills entertained various opinions refpedling the 
 nature of ether. Macquer fuppofed that it was mere- 
 ly alcohol deprived by tlie acid of all its water. But it 
 was generally believed that the acid entered partly into 
 its compolition. Since the nature uf acids has become 
 better known, a great number of phllofophers have fup- 
 pofed that ether is merely alco'iol combined with a quan- 
 tity of oxygen furniditd by the acid. The real compa- 
 ction of this lingular fub lance has been lately afcertain- 
 ed by the experiments of Fourcroy and Vauquelin. 
 
 " A combination (fay they) of two parts of fulphu- 
 ric acid and one part of alcohol e'cvates the tempera- 
 ture to 201°, becomes immediate! jyof a deep red co- 
 lour, which changes to black a few days afterwards, 
 and emits a fmell perceptibly ethereal. 
 
 " V/hen we carefully obferve what happens in the 
 combination of equal parts of alcohol and concentrated 
 iulphuric acid expofed to the action of caloric in a pro- 
 per apparatus, the following phenomena are feen : 
 
 " I. When the temperature is elevated to 208'^, the 
 fluid boils, and emits a vapour which becomes conden- 
 fed by cold into a colourlels, light, and odorant liquor, 
 ■which from its properties has received the name ot elLer. 
 If the operation be properly condufted, no permanent 
 gas is diiengaged until about half the alcohol has palfed 
 over in the form of ether. Until this period there palfes 
 abfolutely nothing but ether and a finall portion of wa- 
 ter, without mixture of fuiphurous or of carbonic acid. 
 
 " 2. If the receiver be changed as foon as the fulphu- 
 rous acid manlfefts itfelf, it is obferved that no more 
 ether is formed, but the fweet oil of wine, water, and 
 acetous acid, without the difengagement hitherto of a 
 fino-le bubble of carbonic acid gas. When the fulphu- 
 ric acid contUtutes about four-hiths of the mafs which 
 remai'ns in the retort, an inflammable gas is difengaged, 
 which has the fmell of ether, and burns with a white 
 oily flame. This is what the Dutch chemlfts have call- 
 ed carbonated hydrogen gas, or ohjiant gas, bccaufe when 
 mixed with the oxy-muriatic acid it forir.s oil. At this 
 period the temperature of the fluid contained in the re- 
 tort is elevated to 230^ or 234°. 
 
 " 3. When the fweet oil of wine ceafes to flow, if the 
 teceiver be again changed, it is found that nothing more 
 pafles but fulphurous acid, water, carbonic acid gas; and 
 that the refiduum in the retort is a black mafs, confifting 
 for the moll part qf fulphuric acid thickened by carbon. 
 
 S T R Y. 
 
 Part ir, 
 
 (g) The name was fuppofed to have been feigned. 
 
 <' The feries of phenomena here expofed will juftify Alcohol. 
 the following general induiflions: *~~^ "^ 
 
 " 1. A fmall quantity of ether is formed fpontanc- 
 oufly, and wit limit the alTiftance of heat, by the combi- 
 nation of two parts of concentrated fulphuric acid and 
 one part of alcohol. 
 
 " 2. As foon as ether is formed, there is a produc- 
 tion of water at the fame time ; and while the firll: of 
 thefe compolitions takes place, the fulphuric acid under- 
 goes no change in its intimate nature. 
 
 " 3. As foon as the fulphurous acid appears, no more 
 ether is formed, or at lealt very little ; but then there 
 pafles the fweet oil of wine, together wiili water and 
 acetous acid. 
 
 " 4. The fweet oil of wine having ceafed to come 
 over, nothing further is obtained but the fulphurous and 
 carbonic acids, and at lail fulphur, if the dillillation be 
 carried to drynefs. 
 
 . " The operation of ether is therefore naturally divi- 
 ded into three periods : the firtt, in which 3 fmall quan- 
 titv of ether and water are formed witliout the aflTiftance 
 of heat ; the fecond, in which the whole of the etlier 
 which can be obtained is difengaged witliout the ac- 
 companiment of fulphurous acid; and the third, in which 
 tlie fweet oil of wine, the acetous acid, the fulphurous 
 acid, and the carbonic acid, are afforded. The three 
 ilages have no circumflance common to all, but the con- 
 tinual formation of water, which takes place during the 
 whole of the operation. 
 
 " The ether which is formed without the afliftanceof 
 caloric, and the carbon which is feparated without de- 
 rompofition of the fuljihuric acid, prove that this acid 
 acts on alcohol in a manner totally diflercnt from what 
 has hitherto been fuppofed. It cannot, in fa£t, be af- 
 firmed, that the acid is altered by the carbon, becaule 
 dally experience ftiews that no fenfible attraction takes 
 place between thefe two bodies in the cold ; neither can 
 it be afFefled by the hydrogen ; for in that cafe fulphu- 
 rous acid would have been formed, of which it is known 
 that no,trace is exhibited during this firft period. We 
 mule therefore have recourfe to another fpecies of ac- 
 tion, namely, the powerful attraftion exercifed bytjie ful- m 
 phuric acid upon v/ater. It is this which determines the " 
 union of the principles which exifl: in the alcohol, and 
 with which tlie concentrated acid is In contaft : but this 
 aftion is very limited if the acid be fmall in quantity ; 
 for an equation of affinity is foon eftabliflied, the effett ^ 
 of which is to maintain the mixture in a flate of repole. ■ 
 
 " Since it is proved that ether is formed in the cold 
 by the mixture of any quantities of alcohol and fulphu- 
 ric acid, it is evident that a mafs of alcohol might hi 
 completely changed into ether and vegetable acid by 
 ufing a fufficient abundance of fulphuric acid. It is 
 equally evident that the fulphuric acid would not by 
 this means undergo any other change than that of being 
 diluted with a certain quantity of water. This obler- 
 vation proves that alcohol contains oxygen, becaule wa- 
 ter cannot exift without this principle, which muft be 
 afforded by the alcohol only, lince the fulphuric acid 
 fuffers no decompofition. 
 
 " We mull not, however, imagine, from thefe fafls, 
 that ether is alcohol minus oxygen and hydrogen. Its 
 properties alone would contradidl this ; for a quantity 
 of carbon proportionally greater than that of the hy- 
 drogen
 
 Part ir. 
 
 C H E M 
 
 Alcnhol. drogen 18 at the fame time feparated. It may, in faft, 
 ' V ' ' be conceived that the oxygen, whicl- iii tliis cafe com- 
 bines with the liydrogeii to form water, not only fatu- 
 rated that liydrogen in the alcohol, but h'kewiie the 
 carbon. So that, inftead of confidering ether as alcoliol 
 minns hydrogen and oxygen, we mu(t, by keeping an 
 account of the precipitated carbon and the fniall quan- 
 tity of hydrogen contained iji the water which is form- 
 ed, regard it as alcohol plus hydrogen and oxygen. 
 
 " The foregoing are the efFeils produced by a combi- 
 nation of alcohol and fulphuric acid, fpontaneouily pro- 
 duced without foreign heat. Let us, in the next place, 
 obferve how this combination is effeftcd when caloric 
 is added. The phenomena are then very different, tho' 
 feme of the refults are the fame. 
 
 " In the firll place, we muit obferve, that a combina- 
 tion of fulphuric acid and alcohol in equal ]»arts does not 
 boil at lefs than 207 degrees of temperature, while (hat 
 of alcohol alone bolls at 176. Now fince ebullition does 
 not take place till the higher temperature, it is clear 
 that the alcohol is retained by the affinity of the ful- 
 phuric acid, which hxes it more confidcrably. Let us 
 alfo confider that organic bodies, or their immediate pro- 
 dufts, expofed to a lively brifk heat, without the poffi- 
 bility of efcaping fpeedily enough from its aftion, fuifer 
 B partial or total decompofition, according to the degree 
 of temperature. Alcohol undergoes this lalt alteration 
 when paflTcd through an ignited tube of porcelain. By 
 this fudden decompofition it is converted into water, 
 carbonic acid, and carbon. The reafon, therefore, why 
 alcohol is not decompofed when it is fubmittcd alone to 
 iieat in the ordinary apparatus for diflillation, is, that 
 - the temperature at which it rifes in vapours is not ca- 
 pable of effefting the fcparation of its principles ; but 
 when it is fixed by the fulphuric acid or any other bo- 
 dy, the elevated temperature it undergoes, without the 
 poflibility of difengagement from its combination, is fuf- 
 Hcient to effect a commencement of decompofition, in 
 which ether and water are formed, and carbon is depo- 
 fited. Nothing more therefore happens to the alcohol 
 in thefe circumftances than what takes place in the dif- 
 tillation of every other vegetable matter in which water, 
 oil, acid, and coal, are afforded. 
 
 " Hence it may be conceived that the nature of the 
 produfts of the decompofition of alcohol muft vary ac- 
 cording to the different degrees of heat ; and this ex- 
 plains why at a certain period no more ether is formed 
 but the fweet oil of wine and acetous acid. In faft, 
 ■when the greateft quantity of the alcohol has been chan- 
 ged into ether, the mixture becomes more denfe, and 
 the heat which it acquires previous to ebullition is more 
 confiderable. The affinity of the acid for alcohol be- 
 ing increafed, the principles of this acid become fepa- 
 rated ; fo that, on the one hand, its oxygen feizes the 
 hydrogen, and forms much water, which is gradually 
 volatilized ; while, on the other, the ether retaining a 
 
 I S T R Y. 297 
 
 greater quantity of carbon, with which at that tempe- Alcohol. 
 rature it can rife, affords the fweet oil of wine. Tliis *"*'"^'~~' 
 lait ought therefore to be confidered as an ether con- 
 taming an extraordinary portion of carbon, which givc3 
 it more denlity, lefs volatility, and a kmon yellow co- 
 lour. 
 
 " During the formation of the fweet oil of wine, the 
 quantity of carbon which is precipitated is no longer in 
 the fame proportion as during the formation of ether. 
 
 " What we have here Hated concerning the manner in 
 which ether is formed by the fimultaneous aftion of the 
 fulphuric acid and heat, ajipears fo conformable to truth, 
 that nearly the fame effefts may be produced by a cauf- 
 tic fixed alkali. In this cafe alfo a kind of ether and a 
 fweet oil of wine are volatilized, and coal is precipitated. 
 It is therefore only by fixing the alcohol that the ful- 
 phuric acid permits the caloric to operate a fort of de- 
 compofition. It may alfo be urged as a proof of this 
 affertion, that the fulphuric acid, which has ferved to 
 make ether as far as the period at which the fweet oil 
 of wine begins to appear, is capable of faturating the 
 fame quantity of alkali as before its mixture with the 
 alcohol *". « Nicho!- 
 
 Ether may alfo be obtained by means of feveral other/"""' J"""" 
 acids. The different liquids thus formed are diftin-''^''" 
 guifhed by prefixing the name of the acid ufed in the 
 procefs. Thus the ether above defcribed is called /u/- 
 phurlc ether ; that obtained by means of nitric acid, ni- 
 tric ether, and fo on. There are feveral minute ffiades 
 of difference between thefe various ethers, which have 
 not yet been properly inquired into. 35S 
 
 Alcohol is capable of diffolving a great many bodies, ^u'^'^anc'-s 
 A confiderable number of thefe, with the quantities fo.'^?'"^'^,''* 
 luble, is exhibited in the following tables. a co o . 
 
 I. Suljiances dijfolvcd in large families. 
 
 Names of tlic Subftances. 
 
 Tempi- 
 
 2^o parrs 
 of alcohol 
 
 
 
 lature. 
 
 diffolve 
 
 
 Nitrat of cobalt 
 
 54,5' 
 
 240parts 
 
 
 copper 
 
 54.i 
 
 240 
 
 
 alumina 
 
 54.5 
 
 240 
 
 
 magnefia 
 
 180,5 
 
 694 
 
 
 Muriat of zinc 
 
 54.5 
 
 340 
 
 
 alumina 
 
 54>5 
 
 240 
 
 
 magnefia 
 
 180,5 
 
 'lU 
 
 
 iron - . 
 
 1 80, J 
 
 240 
 
 
 copper - . 
 
 180,5 
 
 240 
 
 
 Acetite of lead - - 
 
 «i3 
 
 
 
 copper f 
 
 
 
 f Wilhcnng, 
 
 Benzoic acid . - . 
 
 J55.5 
 
 
 Phil. Tranf- 
 
 Sulphat of magnefia 
 
 
 hrii. 336. 
 
 Nitrat of zinc decompofed 
 
 
 
 iron decompofed 
 
 
 
 bifmuth decompofed 
 
 
 
 SuppL. Vot. I. Part I. 
 
 PP 
 
 IL
 
 CHEMISTRY. 
 
 Part ir. 
 
 II. Suljlantes diffbl'vid In fmall ^anthtet. 
 
 * U^if Bering, 
 Fbil. Tranf. 
 hxii. 336. 
 + Macquer, 
 ibid. 
 
 J Withering, 
 
 Hid. 
 
 § ^lacquer, 
 UU. 
 
 Niimes of the Subflarccs. 
 
 Mutiat of lime 
 Nitrat of ammonia 
 Oxy-muriat of mercury 
 Succinic acid 
 Acetite of foda 
 Nitrat of filver 
 Refined fugar 
 Boracic acid 
 Nitrat of foda 
 Acetite of copper 
 Muriat of ammonia 
 Arleniat of potafs 
 Acidulated oxalat of potafs 
 Nitrat of potafs 
 Muriat of potafs 
 Arfeniat of foda 
 Barytes 
 Strontites 
 
 White oxide of arfenic 
 Tartrat of potafe 
 Phofphorus 
 Nitrat of lead • 
 lime * 
 Muriat of mercury f 
 Carbonat of ammonia * 
 
 140 pans of 
 :ilcoliol at iht. 
 boiling tempt 
 rature difTi-lvr 
 
 240 parts 
 214 
 2 I 2 
 
 177 
 1 12 
 
 ICO 
 
 59 
 48 
 
 23 
 18 
 
 17 
 
 7 
 5 
 5 
 4 
 
 III. Suhjlances infoluble with Alcohol. 
 
 Sugar of milk, 
 
 Sulphat of foda. 
 
 Borax, 
 
 magnefia. 
 
 Tartar, 
 
 Sulphite of foda, 
 
 Alum, 
 
 Tartrite of foda and 
 
 Sulphat of ammonia. 
 
 potafs. 
 
 lime, 
 
 Phofphoric acid, 
 
 barytes %, 
 
 Nitrat of lead, 
 
 iron (green), 
 
 mercury. 
 
 copper, 
 
 Muriat of lead, 
 
 filver, 
 
 filver J, 
 
 mercury, 
 
 Common fait. 
 
 zmc, 
 
 Carbonat of potafs. 
 
 potafs, 
 
 foda. 
 
 in Genefi?, and during the time of Abraham was even Oils, 
 ufed in lamps *. The olive was very early cultivated, 
 
 Thefe have been chiefly borrowed from tables which 
 Mr de Morveau publifhed in the Journal de Phyjique 
 July 1785, and which were drawn up for the moft part 
 from the experiments defcribed in Wenzel's Treatife on 
 AfSnities. 
 UsaiSni'.ici. "^^^ affinities of alcohol are very imperfeftly known. 
 Thofe ftated by Bergman are as follows : 
 
 Water, 
 
 Ether, 
 
 Volatile oil, 
 
 Sulphurets of alkalies. 
 
 3";9 
 
 360 
 D'lfc livery 
 
 Chap. III. 0/Oils. 
 
 Oil, which is of fuch extenfive utility in the arts, 
 was known at a very remote period. It is mentioned 
 
 and oil extradled from it in Egypt. Cccrops brought '"' 
 it from Sais, a town in Lower Egypt, where it had 
 been cultivated from lime immemorial, and taught the 
 Athenians to e.\traft oil from it. In this manner the 
 ufe of oil became known in Europe f. But the Greeks f- HeroJot. 
 feem to have been ignorant of the method of procuring lib. ii 59. 
 light by means of lamps till after the fiege of Troy j.-^'^ ^*' 
 at leaft Homer never mentions them, and conftantly de- 
 fcribi's his heroes as lighted by torches of wood. 
 
 Oils are divided into two claffes. Fixed and Volatile; 
 each oi which is diftinguifhed by peculiar properties. .5, 
 
 I. The FIXED OILS, called alfo fut or <'A;/>r^'c/ oils. Fixed oilt 
 are numerous, and are obtained, partly from animals and 
 partly from vegetables, by fimple exprefiion. As in- 
 fiances, we (hall mention whale oil or train oil, obtained, 
 from the blubber of the whale ; olive oil, obtained from 
 the fruit of the olive ; lintfeed oil and almond oil, ob- 
 tained from lintfeed and almond kernels. Fixed oils 
 may alfo be obtained from poppy feeds, hemp feeds, 
 beech maft, and many other vegetable fubflances. 
 
 All thefe oils differ from each other in fcveral parti- 
 culars, but they alfo poflefs many particulars in com.- 
 mon. Whether the oily principle in all the fixed oils is 
 the fame, and whether they owe their differences to ac- 
 cidental ingredients, is not yet completely afcertained, 
 as no proper analyfis has hitherto been made ; but it is 
 exceedingly probable, as all the oils hitherto tried have 
 been found to yield the fame produfls. In the prefent 
 ftate of our knowledge, it would be ufelefs to give Ji 
 particular defcription of all the fixed oils, as the diffe- 
 rences between them have not even been accurately af- 
 certained. We (liall content ourfelves, therefore, with 
 giving the charaflers which ditlinguifh fixed oils in ge- 
 neral, and an analyfis of one oil, by way of ipecimen. , 
 
 Fixed oils are infoluble in alcohol, which diftinguiflies-pheir pro- 
 them from volatile oils. They are alfo infoluble in water, pertice. 
 
 They have an undluous feel, are tranfparent while 
 fluid, are deftitute of fmeli, and have a mild infipid kind 
 of tafte. 
 
 They are all fufceptible of becoming folid by expo- 
 fure to a fuflicient degree of cold. Olive oil and al- 
 mond oil freeze at iot degrees if. t Chaptal^t 
 
 They are capable of being converted into vapour hy ^'■'""'1^'}^ 
 heat ; but require tor that purpofe a temperature con--p"^ i ... 
 fideraLly fupevior to that of boiling water. Olive oil .,, 
 boils at 600'', and moft of the fixed oils hitherto tried 
 require nearly the fame degree of heat. 
 
 When in the ftate of vapour they take fire on the 
 approach of an ignited body, and burn with a yellowilh 
 white flame. It is upon this principle that candles and 
 lamps burn. The tallow or oil is full converted into 
 the ftate of vapour in the wick ; it then takes fire, and 
 fupplies a fufhcient quantity of heat to convert more 
 oil into vapour ; and this procefs goes on while any oil 
 remains. The wick is neceflary to prefent a fufficient- 
 ly fmall quantity of oil at once for the heat to adl up- 
 on. If the heat were fufScieptly great to keep the 
 whole oil at the temperature of 600°, no wick would be 
 neceflary, as is obvious from oil catching fire fponta- 
 neoufly when it has been raifcd to that temperature. ,5^ 
 
 Mr Lavoifier analyfcd olive oil by burning it in pre- Analyfis of 
 cilely the fame apparatus as that which he employed forol''^ '^''• 
 analyfiug alcohol. 
 
 The
 
 Parcir. C H E M 
 
 O'l'- The quantity of oil confumeJ amounted to 15,79 
 
 *" grains troy. 
 
 The quantity of oxygen gas amounted to jo,86 gr. 
 troy. The whole amount therefore of ihi fubilances 
 confumed during the coinbullion is 66,65 grains troy. 
 
 The carbonic acid obtained amounted to 44,50 gr. 
 There was alfo a confiderable quantity of water, the 
 weight of which could not be accurately afcertained : 
 but as the whole of the fubrtances confumed were con- 
 verted into carbonic acid gas and water, it is evident 
 that if the weight of the carbonic acid be fuhtratled from 
 the weight of thefe fubllances, there muft remain precile- 
 ly the weight of the water. Mr Lavoifier accordingly 
 concluded, by calculation, that the weight of tiie water 
 was 22,1 5 grains. Now the quantity of oxygen in 44, ^o 
 grains of carbonic acid gas is 32,04 grains, and the oxy- 
 gen in 22,15 grains of water is 18,82 grains ; both ot 
 which taken together amount to 50,86 grains, precifely 
 the weight of the oxygen gas employed. I'here does 
 not appear therefore to be any oxygen in olive oil. 
 
 The quantity of carbon in 44,50 grains of carbonic 
 acid gas is 12,47 grains; and the quantity of hydro- 
 gen in 22,15 grains of water is 3,32 grains; both of 
 which, when taken together, amount to 15,79 grains, 
 whicli is the weight of the oil confumed. 
 
 It follows, therefore, from this analyfis, that 15,79 
 grains of olive oil are compofcd of 
 12,47 Carbon, 
 3,32 Hydrogen. 
 Olive oil therefore is compofed of about 
 79 Carbon, 
 21 Hydrogen. 
 
 « Mrm. 100* 
 
 J'^r. 1734. In what manner thefe fubllances are combined, can. 
 
 ypj'r^ ''o'bs learned from this analyfis. Whether they combine 
 
 1787 7»/v '^''"S'Sly' ^"d faturate each other in that proportion, as 
 is moft probable or whether the hydrogen is combined 
 previoufly with a part of the carbon, and that compound 
 combining with a certain quantity of carboii, forms oil, 
 is altogether uncertain. Yet thefe queftions are of the 
 utmoft importance ; and till the method of folviiig them 
 be difcovered, we never can acquire any precife ideas 
 about the conftituent parts of a great number of fub- 
 llances, which, though formed ultimately of the fame in- 
 gredients, differ very much in their properties from one 
 » another; as wax and oil; alcohol, fugar, and ether. 
 
 Rancidicy. When fixed oils are expoled to the atmofpliere, they 
 become thick, acquire a brown colour, and a peculiarly 
 unpleafant fmell : they are then faid to be raiuij. 
 When oil is poured upon water, fo as to form a tliin 
 layer on its furface, and is in that manner expofed to 
 the atmofphere, thefe changes are produced much foou- 
 er, the oil becomes thicker, and affumes an appearance 
 very much refemhling wax. Berthollet, who firll exa- 
 mined theie phenomena with attention, afcribcd them 
 to the aftion of light: but Sennebier obferved, that no 
 fuch change was produced on the oil though ever fo 
 long expofed to the light, provided atmofpherical air 
 
 I S T R Y. 
 
 was excluded ; but that it took place on the admiflion OiU. 
 ot oxygen gas, whether the oil was expofed to the light ' 
 
 299 
 
 or not *. It cannot be doubted, then, that it is owing • -^o'. •^.• 
 to the combination of oxygen. All fubllances that arc '''""• ■"• 
 capable of fupplying that principle, the metallic oxides'*'^* 
 for inllance, and feveral of the ac'ds, produce the fame 
 effed upon oils ; and it is a known fart, that oil is 
 capable of reducing many of the metallic oxides to the 
 metallic Hate, and confequently that it has a ilrono-er 
 affinity for oxygen. 
 
 Mr Chaptal has fuppofed that oils become rancid 
 merely bccaufe they contain a quantity of mucilage, 
 with which the oxygen combines ; and that when oxy- 
 gen combines with lixed oils, it produces a different eV- 
 feil, converting them into what is called drying oils. 
 
 It is certain that oils contain a quantity of mucilage; 
 but fome change is evidently produced ou the oils them- 
 felves by rancidity; for no agitation in water is capable 
 of reftoring them to their former Hate, although water 365 
 deprives them of their mucilage. Drying oils, fo called Oryingoilf. 
 becaufe they are capable of aO-j;(«^completely when fpread 
 out, a property which renders them ufeful in painting, 
 feem, as Sennebier obferves, to be completely deprived of 
 mucilage ; for, in order to render an oil drying, it muft 
 be boiled, which evaporates or decompofes all the muci- 
 lage: they feem alfo to lofe part of their hvdroffenf. . ^ .. ,, 
 
 tixed oils are capable ot dillolving fulphur at their ,66 
 boihng temperature. The folution is very fetid, owing rixed oils 
 to a partial decompofition of the oil. Hydrogen gas'^''^"'"^ '"'• 
 flies off, having a quantity of fulphur diffolved in it. P''"'^' 
 When the folution cools, the fulphur cryllaliizfs. ,5, 
 
 Fixed oils diffolve phofphorus. The folution is lu- And phof- 
 minous, from the flow combuflion of the phofphorus. phorus. 
 
 Fixed oils are capable of combining with many of 
 the metallic oxides. The compounds are called metallic 
 foaps. Several of the oxides are decompofed by being 
 boded in oils. 
 
 Fixed oils combine alfo with the alkaline earths and 
 with alumiiia. The compounds are called <'a)-</;v/i/,7Aj-. 
 
 The affinities of the oih are as follows : 36' 
 
 Lime, Nitric acid. Their alh. 
 
 l3»rytes, Muriatic, 
 
 Fixed alkalies, Sulphurous, 
 
 Magnefia, Sulphuric, 
 
 Ammonia, Acetous, 
 
 Oxide of mercury. Sulphur, 
 
 Other metaiJtc oxides (11), Phofphorus(i). 
 
 Alumina. , 
 
 II. Volatile oils, called alfo ejfential oils, are all Volatile 
 obtained from vegetables. They have a f'trong aroma- o'ls. 
 tic fmell, and a pungent acrid talle. They arc fo vo- 
 latile that they may be diiliUed by the heat of boiling 
 water. They are foluble in alcohol, hut not in water. 
 They evaporate on the application of heat, without lea- 
 ving any llain behind tliem, which is not the cafe with 
 the fixed oils. By this ted, accordingly, it is cafy to 
 difcover whether they have been adulterated with any 
 of the fixed oils. Let a drop of the volatile oil fall 
 upon a iheet of writing paper, aiul then apply a gentle 
 f P 3 heal 
 
 (h) Their order not well afcertained. 
 
 (i) The firfl column was afcertained by Berthollet. The lafl is to be confidered as unconnected with the firft. 
 On account of the affinity of thefe two clafles of bodies for each other, it has not been polCble to difcover which 
 of them has the grcatell affinity for oil.
 
 ;oo 
 
 C H E M I 
 
 Alkalle«. heat to it. If it evaporates without leaving any (lain 
 ^~"'V^~' upon the paper- the oil is pure ; but if it leaves a ilain, 
 it has been coiuaminated with fome tixeJ oil or other. 
 
 Volatile oils are very numerous, ami difter from one 
 another, in fluidity and weight, in their freezing point, 
 and in feveral other particulars. Little attention has 
 been paid to the greatcft part of them, becaufe few of 
 them have been found of any ufe. The principal qua- 
 lity for which they are valued is their odour. Some of 
 them are obtained by cxprefiion, as oil of bcrgamot, le- 
 mons, oranges ; otheis by diltillation, as oil of pepper- 
 mint, thyme, lavender, &e. It would be ufclefs, even 
 if it were poffible, to give a particular dtlciiption of all 
 the volatile oils. 
 
 They are more inflammable than the fixed oils; a qua- 
 lity which they owe to their volatility. As far as expe- 
 riments have hitherto been made, they feem to confill 
 of carbon and hydrogen; but nothing is _ known con- 
 cerning the proportions of thefe ingredients. They 
 thicken when cxpofed to the air, probably by combi- 
 ning with oxygen, and form rtjuis (k). 
 
 When expofed to cold, or when kept for a long time, 
 fome of them depofite cryftals refembhng the acid of 
 benzoin ( l). 
 
 They dlffolve fulphur, and form what have been call- 
 ed bnlfams of fulphur. 
 
 They are capable of combining with mofl; of the fub- 
 ftances that unite with fixed oils. Their affinities, which 
 certainly difTer from thofe of fixed oils, have not yet 
 been properly afcertained. 
 
 S T R Y. 
 
 Part ir. 
 
 .■57° 
 Their pro- 
 perties. 
 
 Chap. IV. 0/ Alkalies. 
 
 37' 
 
 Properties Substances poflefTed of the following properties are 
 of .-.Ikalies. called alkiiUes : 
 
 1. Incombufl;ible. 
 
 2. Capable of converting vegetable blues to a green. 
 
 3. A hot cauilic talle. 
 
 4. Very foluble in water, even when combined with 
 
 carbonic acid. 
 There are three alkalies, polafs, foih, and ammonia. 
 The two firll are called fxeJ alkalies, becaufe a very 
 violent heat is neceffary to volatilize them ; the laft is 
 called volati/e alkali, becaufe it very eafily an"umes a ga- 
 feous form, and is confequently diflipated by a very mo- 
 derate degree of heat. 
 
 Sect. I. Of Polafs. 
 
 M''thod f If a fufficicnt quantity of wood be burnt to afhes, 
 procuring and thefe aflne« be afterwards wafhed repeatedly with 
 jjotafs. water till it comes off free from any tafte, and if this 
 liquid be filtrated and evaporated to drynefs, the fub- 
 ftance which remains behind is potafs ; not, however, 
 in a ftate of purity, for it is contaminated with feveral 
 other fubftances ; but fufficiently pure to exhibit many 
 
 of its properties. In this (late, it occurs in commerce A'kalies. 
 under the name of potaflj. It may be purified confi- — v— — ^ 
 derably, by putting it in a crucible, keeping it red hot 
 for fome lime ; then dilFolving it in water, filtrating it, 
 and evaporating it again to drynefs. By the following 
 method it may be obtained nearly pure : Mix together 
 equal quantities of nitre and carbon, and put them by 
 little and little into a red hot crucible. They burn 
 with a vivid flame, and leave behind them a quantity of 
 potafs. This is to be dlfTolved in water, filtrated, and 
 evaporated to drynefs. Or petals may be obtained by 
 burning tartar wrapt up in brown paper and placed in 
 a crucible (m). 
 
 The potafs procured by thefe laft procefles is exceed- 
 ingly white ; it is not, however, quite pure ; for it is 
 combined with a fubllance which bhmts all its properties 
 confiderably. This fiibltance is carbonic acid gas; from 
 which it may be feparated by dillolving it, and mixing 
 with it an equal quantity of lime made into a palle with 
 water. The lime has a greater affinity for carbonic acid 
 gas, and therefore combines with it ; and the pure pot- 
 afs remains didulved in the water, and may be feparated 
 from the lime by filtrating the mixture This procefs, 
 however, mull be performed in clofe vcffcls ; for there 
 is a little carbonic acid gas in the atraofphere, which 
 would again combine with the potafs if it were allowed 
 to ftand expofed to the air. 
 
 It is then to be evaporated till a thick pellicle appears 
 on its furface, and afterwards allowed to cool ; and all 
 the cryftals which have formed are to be feparated, for 
 they confift of foreign falts. The evaporation is then 
 to be continued in an iron pot ; and, during the pro- 
 cefs, the pellicle which forms on the furface is to be 
 carefully taken off with an iron fi<immer. When no 
 more pellicle appears, and when the matter ceafes to 
 boil, it is to be taken off the fire, and muft be conftant- 
 ly agitated while cooling with an iron fpatula. It is 
 then to be dlfTolved in double its own weight of cold 
 water. This folution is to be filtered and evaporated 
 in a glafs retort till it begin to depofite regular cryftals. 
 If the mafs confolidates ever fo little by cooling, a fmall 
 quantity of water is to be added, and it muft he heated 
 again. When a fufficient number of cryftals have been 
 formed, the liquor wliich fwims over them, and which 
 "has aflumed a very brown colour, muft be decanted off, 
 and kept in a wcU-clofed bottle till the brown matter 
 has fubfided, and then it may be evaporated as before, 
 and more cryftals obtained. The cryftals may then be 
 diffolved in pure water. By this procefs, which was 
 invented by Mr Lowitz of Peterlburgh *, potafs may * j^uiolfin, 
 be obtained in a ftate of the greateit purity. Thei. 164- 
 ftiape of its cryftals is very different, according to the 
 way in which they have been produced. When allow- 
 ed to form in the cold, they are oftahedrons in groups, 
 and contain 0,43 of water : When formed by evapora- 
 tion 
 
 i 
 
 (k] Rcfins are concrete vegetable juices ; the diftinguilhing property of which is infolubility in water and fo- 
 lubility in alcohol. Common rejin, or rofin, from which they derive their name, is one of them ; and fealing wax 
 confifts almoft entirely of another. 
 
 (l) See a paper by Margueron on this fubjeft, y}nn. de Ch'im. xxi. 174. 
 
 ( M ) That potafs was known to the ancient Gauls and Germans, cannot be doubted, as they were the inventors 
 of foap, which, Pliny informs us, they compofed of afhes and tallow. Thefe aflies (for he mentions the alhes 
 of the beech tree particularly) were nothing elfe but potafs ; not, however, in a ftate of purity. Pl'tmi, hb. xviii. 
 c. 51. The M,ia, too, mentioned by Ariftophanes and Plato, appears to have been a ley made of the fame kind 
 of afhes.
 
 Part n. 
 
 CHEMISTRY. 
 
 Allwlits. tioii on the fire, they affiime the figure of very thin traii- 
 ^——r—' ('parent blades of extraordinary magnitude, which, by 
 im alfemblage of lines croffing each other in prodigious 
 nnmbers, prefent an aggregate of cells or cavities, com- 
 monly fo very clofc, that the velfel may be inverted wilh- 
 « K[icUljli:,o\x\ loCnig one drop of the liquid wiileh it containsf . 
 i. 164. Pure potal.s is fo exceedingly cuirolive, that when 
 
 applied to any part of the body, it dellruys it almoll 
 inllanta]\eouIly. On account of this property, it has 
 been called caujl'tc, and is often iifcd by furgeons under 
 the name of lUi polciitiiil cautery^ to open ablcefl'es, and 
 ,,, delfroy ufelels or hurtful exercfcences. 
 Black'5 dif- As polafs is never obtained at firft in a (late of pu- 
 covey of rity, but always combined with carbonic acid, it was 
 
 !'''■ '^'"''"'^lont'- before cheniilh underllood to what the changes 
 
 Its caulti- ^', , • , 1- \ !• 
 
 jj,, produced upon it by lure were owmg. According to 
 
 fome, it was deprived of a quantity of mucilage, in 
 which it had formerly been enveloped ; « bile, accord- 
 ing to others, it was rendered riiorc atlive by being 
 more comminuted. At laft, in 175'i, Dr Black pub- 
 lillied the celebrated experiments which we have fo of- 
 ten mentioned ; in wiiich he proved, by the moll inge- 
 nious and fatisfaflory analylis, that the potafs which the 
 world had conlidered as a fimple fubftanee, was really a 
 compound, ccufilting of potafs and carbonic acid ; that 
 lime deprived it of this acid ; and that it became more 
 active by becoming more fimple. 
 
 While Dr Black, was thus occupied in Scotland, Mr 
 Meyer was employed in Germany in the fame refearches ; 
 from which, however, he drew very different conclu- 
 fions. His Effays on Lime appeared in 1 764. Pour- 
 ing into lime-water a folution of potafs (cariotiat ofpot- 
 a/ij, he obtained a precipitate, which he found not to 
 differ from 'llmellone. The alkali had therefore de- 
 prived the lime of its canftlcity and its aClive properties ; 
 and thefe very properties It had Itfelf acquired. From 
 which he concluded, that the cauiliiity of lime was 
 owing to a particular acid with which it had combined 
 during its calcination. The alkali deprived the lime of 
 this acid, and therefore had a flrongcr affinity for it. 
 To this acid he gave tlie name of acitlum puigiie or ainf- 
 i'lcum. It was, according to him, a fnbtile elaillc mixt, 
 analogous to fulphur, approaching very nearly to the 
 nature of fire, and aflually compofed of an acid prln- 
 ciple and fire. It was expanfible, comprcfhble, volatile, 
 aflringent, capable of penetrating all veflels, and was 
 the caufe of caufticity in lime, alkalies, and metals. 
 This theory was exceedingly ingenious, and it was fup- 
 ported by a vail number of new and important fafts. 
 But notwithllanding the reputation and acknowledged 
 genius and merit of its author, it never gained many 
 tollowers ; becaufe the true theory of caullicity, which 
 had been already publiihed by Dr Black, foon became 
 known on the continent ; and, notwithflanding fome 
 -oppofitlon at firll, foon carried conviction into every 
 unprejudiced mind. Even Mr Meyer himfelf readily 
 acknowledged its truth and importance, though he did 
 not at firft, on that account, give up his own theory. 
 
 When potafs Is expofed to the aftlon of fire, it firfl 
 becomes foft, and melts into a tranfparent liquid at the 
 commencement of ignition. 
 
 When expofed to the air, it attrafb moifture very 
 fait, and Is foon converted into a liquid. It attrafts, 
 at the fame time, carbonic acid gas, for which it has a 
 very ftrong affinity. It is impoffible, then, to keep 
 potafs in a ftate of purity, except in very clofe veffels. 
 
 30T 
 
 It unites readily with fulphur, and {ovm% fulphuret of Alkalies. 
 potafs. Tin's compound may be formed two ways ; ei- " '^ 
 
 ther by melting the ingredients together, or by boiling g^^,^^^^^^ 
 them in water, and tlien filliMting the folution. Sul-of potafs. 
 phuret of potafs when dry, in which llate It is obtained 
 by the firll procefs, is ot a brown colour. It is foluble 
 in water, and very foon attrafts moillure. 
 
 While dry it.protluees no change ujion the air of 
 the atmofphere, as MefiVs DIeman, Van Troollwyck, 
 Nieuwland, and Bondt, afcertalned by experiment *.» ^„„. ji 
 But when molltened with water. It very foon abforbsCi;™. xiv. 
 all the oxygen gas which happens to be in the vcflel in'9''* 
 which it is enclofed, and leaves notliing but azotic gas. 
 This fadl was fiifl obferved by Scheele, and induced 
 him to ufe fulphuret of potafs for an eiuiiomeler, or in- 
 (Irument to meafuie the quantity of oxygen contained 
 In any given poition ot aimufpheric air. 
 
 If lulphuret of potafs be allowed to remain moid, and 
 in contacl with the atmofphere, it is gradually convert- 
 ed into fulpliat of potals by tlie fulphur combining 
 with oxygen, and forming fulphuric acid. At the 
 fame time the fulphuret emits a fetid fmell, which is 
 known to be the odour of fulphurated hydrogen gas. 
 The fulphuret then decompefes the water with wiiich 
 it is mixed. Very little fulphurated hydrogen gas, 
 hoivever, is emitted, except an acid (the iulphnric, for 
 inllance) be poured upon the mixture, and then It is 
 given out very copioully. The reaion of this is, that 
 there is an affinity between t!ie potafs and this gas. 
 Accordingly It Is retained by the potafs after it Is form- 
 ed. But as the acids have a much ftronger affinity for 
 potafs, as foon as any of them is poured in the gas is 
 obliged to feparate f . ^ ii;j^ 
 
 It liquid fulpiiuret of potafs be kept in clofe vefrds, 
 it is not deconipofed except 1:1 part ; becaufe as foon 
 as the alkali is laturated with the fulphurated Iiydrogen 
 gas, the a£lion of the fulphur on the water is at an end ij;. ( Uid.. 
 
 The explanation of the action of this fulphuret on 
 the atmofphere, which the Dutch chemllls above-men- 
 tioned give from thefe data. Is as follows: 
 
 Sulphuret ot potafs decompofes water ; fulphurated 
 hydrogen gas is formed, and abforbed by the alkali. 
 This gas has a ilrong affinity for oxygen, which it 
 abforbs from the atmolphere : the hydrogen combines 
 with this oxygen, and forms water; and the fulphur is 
 again precipitated, or rather left combined with the pot- 
 afs. Water is again deconipofed by the attraction of 
 the fulphur for oxygen ; new fulphurated hydrogen gas 
 is again formed ; again abforbed ; again attradls oxy- 
 gen gas ; and is agam decompiifed. And this procefs 
 goes on till the whole of the fulphur has combined with 
 oxygen, and conlequently till the fulphuret is converted 
 into a fulphat §. — The only pait of this theory which 5 JUJ. 
 requires confirmation. Is tlie adllon of fulphurated hy- 
 drogen gas on oxygen gas, and the confequent forma- 
 tion of water. And this they have rendered not Impro- 
 bable, by (hewing that lulphurated hydrogen gas com- 
 bined with alkali has the property of abforbing oxygen 
 gas from the atmofphere {{. 11 niJ. p, 
 
 Potafs unites with phofphorus by fufion, and forms 305. 
 a phofphuret of potafs. Little is known conceruing '^'' 
 its properties, except that it produces phofphurated hy- r [Ir""" 
 drogen gas. 
 
 Potafs feems alfo capable of combining with carbon. 
 
 Potafs does not combine with the metals ; but it 
 unites with many of their oxides. 
 
 Whea
 
 ■Ji- 32. 
 
 377 
 Glafs. 
 
 C H E M 
 
 Wlien a folutioii of potafs is boiled upon filica re- 
 cently procured, !t difTolvcs part of it. As tlie folu- 
 tioii cools, it" affumes the appearance of a jelly, even 
 though prcvioufly diluted with 17 times its own weight 
 of water *. 
 
 When equal parts of filica and pot.nfs are melted to- 
 gether, they combine and form ^/qfs. A fubllance 
 which, whether we confidcr its hardnefs, beauty, and 
 tranfparency, its amazing dudlility, while hot, or the 
 difficulty of decompofing it, muft be allowed to be one 
 of the moll ufeful compounds ever invented by man. 
 
 When the quantity of potafs is double or triple that 
 of the filica, the glafs is foluble in water, and forms 
 what is called liquor Jtlicuin. 
 
 Potafs feems alfo capable of combining in the fame 
 manner with barytes, lime, magncfia, and alumina ; but 
 thefe combinations have never been examined with at- 
 tention. Lime, however, is often added to the mate- 
 rials for making glafs, and is fuppofed to increafe its 
 hardnefs and folidity. 
 
 The metallic oxides have the property of rendering 
 glafs more fufible, and of communicating various co- 
 lours to it ; they accordingly very often make a part 
 of its compofition. The colours communicated by thefe 
 oxides will appear from the following Table : 
 
 Metallic Oxides. Colour communicated to Glafs. 
 
 Oxide of gold and tin, - Purple. 
 
 Silver, - - . Yellow or golden. 
 
 378 
 Soap. 
 
 379 
 Potafs, 
 whether a 
 
 compound. 
 
 Iron, - - 
 Lead, - - 
 Zinc, - - 
 Antimony, 
 Arfenic, 
 Cobalt, - - 
 Nickel, - - 
 Manganefe, 
 Tungften, - 
 Molybdenum, 
 Uranium, 
 Titanium, - 
 Tellurium, - 
 Chromum, - 
 
 Pale green. 
 
 Colourleis. 
 
 White. 
 
 Green (n). 
 
 White. 
 
 Blue. 
 
 Blue (o). 
 
 Red. 
 
 Colourlefs. 
 
 Colourlefs. 
 
 Grey (opaque). 
 
 White (opaque). 
 
 White. 
 
 Green. 
 
 Potafs combines r>?adily with fixed oils, and forms 
 the compound known by the name of foap. 
 
 Potafs has never yet been decompofed. Several che- 
 mifts, indeed, have conjeftured, that it was a compound 
 of lime and azot ; and fome perfons have even endeavour- 
 ed to prove this by experiment ; but none of their proofs 
 are at all fatisfaftory. We ought, therefore, in ftridl 
 propriety, to have affigned it a place in the firft part of 
 this article : but this would have feparated the alkalies 
 from each other, and would have introduced a confufion 
 into the article, which would have more than counterba- 
 lanced the logical exaftnefs of the arrangement. Befides, 
 we are certain, from a variety of faiSls, that all the al- 
 kalies are compounds : One of them has aftually been 
 decompounded ; and the other two have been detefled 
 in the aft of formation, though the ingredients which 
 compofe them have not hitherto been difcovered. 
 
 I S T R Y. Part. II, 
 
 Whether potafs contains lime is a different queftion. Alkalies 
 Were we to judge from analogy, we Ihould liippofe, '— ~\— -^ 
 that the four alkaline earths, and the three alkalies, 
 poffefs one common principle. They have a great num. 
 ber of common properties, and perhaps ought to be 
 claffed altogether under the name of alkaHts. 
 
 That azot enters into the compofition of all thefe 
 bodies, as I'ourcroy has conjeftured, is far from impro- 
 bable. One alkali, as we (hall loon fee, aftually con- 
 tains azot. But no conclufion can be drawn till future 
 difcoveries have lifted off the veil which at j)refent ob- 
 ftrufts our view. 380 
 
 The affinities of potafs are as follows : Its affiniti«j 
 
 Sulphuric acid, 
 
 Nitric, 
 
 Muriatic, 
 
 Sebacic, 
 
 Fluoric, 
 
 Phofphoric, 
 
 Oxalic, 
 
 Tartarous, 
 
 Arfenic, 
 
 Succinic, 
 
 Citric, 
 
 Formic, 
 
 Laftic, 
 
 Benzoic, 
 
 Sulphurous, 
 
 Acetous, 
 
 Saccholaftic, 
 
 Boracic, 
 
 Nitrous, 
 
 Carbonic, 
 
 Pruffic, 
 
 Oil, 
 
 Sulphur, 
 
 Phofphorus, 
 
 Water. 
 The place of the metallic oxides has not yet been 
 afcertained. 
 
 Sect. IL Of Soda. 
 
 Soda, called mineral alkali, becaufe it is found in the 
 earth, was known to the ancients under the names of 
 v.'fo. and nitrum (p). It was long confounded with pot- 
 afs; and perhaps was never properly dillinguilhed from 
 it till Du Hamel publiihed a paper on the fubjeft in 
 
 ^''f- ■ w^ T, t. r ^8' 
 
 Its properties, while pure, are preciiely the fame p^ppcrtiej 
 
 with thofe of potafs, excepting only that its affinity foroffoda. 
 other bodies is not fo ftrong ; it does not, therefore, 
 require any particular defcription. We ought to men- 
 tion, however, that it differs from potais in one particu- 
 lar ; potafs attrafts moifture in the air, but foda parts 
 with it, and when expofed to the atmoiphere, foon 
 crumbles down into a dry powder. 
 
 It is capable of combining with all the fubftanceg 
 with which potafs unites; but it forms compounds pof- 
 feffed, in general, of very different properties from thofe 
 of the compounds into which potais enters. 
 
 It 
 
 (n) If the glafs be made with foda. 
 
 (o) But reddifh if the glafs be formed of foda. Klaproih. 
 
 (p) The M'f,, of the Athenians was evidently the fame fubftance; and fo was the inj of the Hebrews.
 
 391 
 Bifcovery 
 of ammo- 
 nia. 
 
 Part II. CHE M 
 
 Alkalies. It is reckoned more proper than potafs for foiming 
 '~^^f^~' glafs and foap. 
 
 Some cliemifts have fiippofcd that it is cornpofcd of 
 magnefia and azot ; but tlieir proofs are infufiicient. 
 
 The order of its al&nities is the fame with that of 
 potals. 
 
 Sect. III. Of Ammonia, 
 
 Ammonia {qJ)i volatile alkali, or hart/horn, as it is 
 called in commerce, is mentioned as early as the 15th 
 century. Both Bafil Valentine and Raymond LuUy 
 defcribed the methods of procuring it. Dr Black was 
 the firft who diftiiiguifhed pure anummia from the car- 
 bonat of ammonia, or ammonia combined with carbo- 
 nic acid ; and Dr PricRlcy firll difcovered the method 
 of obtaining it in a ftate of complete purity. 
 
 To obtain pure ammonia, mix common lal ammoniac 
 with three parts of flacked lime ; apply heat ; and re- 
 ceive the produdl in a veffel filled with mercury ftand- 
 ing in a bafon of mercury. A gas comes over, which 
 
 • Pr/'f/J/cjinnis pure ammonia*. This gas is tranfparent like com- 
 
 jiirMii; I -tnon air, and is not condenicd by cold. 
 
 . -^ ■' Its fnecific gravity is 0,000752. It is to common 
 
 Its pioiiei- . .' 1 ' / J 
 
 ^i55 air as 000 to 1000 f. 
 
 \Kirtvan en It has a very ftrong, but not unpleafant fmell. Ani- 
 
 jPA/of. li.ib.mals cannot breathe it without death. When a light- 
 ed candle is let down into this gas, it goes out three or 
 four times fucceffively ; but at each time the flame is 
 conhderably enlarged by the addition of another flame 
 of a pale yellow colour, and at lall this flame dcfcends 
 
 t PtlrjlUy, from the top of the vcflel to the bottom J. 
 
 ii. 3S1. Water abforbs this gas with avidity. It difappears 
 
 almofl: inftantly on the introduftion of a little water. 
 From an experiment of Dr PricU'ey, it appears that 
 water faturated with this gas is of the fpecific gravity 
 
 § njJ. p. 
 37»- 
 
 i.'4?5 J 
 
 II nid. p. 
 
 377' 
 
 3K4 
 It=; (Oiiip 
 
 This water acquires the fmell of ammonia. It has 
 a veiy itrong difagreeable talte, and converts vegetable 
 colours to a green. 
 
 Ammonia in the ftate of gas has no effedl upon ful- 
 phuv or phofphorus. Carbon abforbs it ; probably 
 becaufe it contains water. Neither hydrogen nor azot 
 produce any alteration on it ||. 
 
 Alcohol and ether abforb it in confiderablequantity ^. 
 Dr Priellley difcovered, that when tleftric cxplofions 
 were made to pals through this gas, its bulk was gra- 
 nent parts, dually augmented to thrice the fpace which it formerly 
 occupieil. It was then nioftly converted into hydro- 
 gen gas. He difcovered, too, that heat produced the very 
 * J'jid. jSo.f^'""^ effeft *. Thefe experiments prove that hydrogen 
 enters as an ingredient into the compofitiou of ammonia. 
 
 Mr Seheele oblerved, that when ammonia was treat- 
 ed with the oxides ot manganefe, gold, or mercury, the 
 oxides were reduced ; th^ ammonia difappeared ; and 
 nothing remained but a quantity of azotic gas. Thefe 
 fa£ls induced Bergman to conjetlure, that ammonia was 
 compofed of hydrogen and azot: a conjctlure which has 
 been fully conlirmed by the experiments of BtrthoUet. 
 
 This ingenious chemift obferved, that if oxy-muria- 
 tic acid and ammonia be mixed, an effervefcence takes 
 place ; azot is diftngaged, a quantity ot water formed, 
 
 I S T R Y. 303 
 
 and the oxy-muriatic acid is converted into common mu- Alkahi-^. ^ 
 riatic acid. Now the fnbftances mixed were an\moiu'a ' 
 
 and oxy-muriatic acid, which is compofed of oxygen and 
 muriatic acid ; the products were, muriatic acid, azot, 
 and water, which is compofed of oxygen and hydrogen. 
 The oxygen of the water was furnillKd by the acid ; 
 the other produfts muft. have been furnilhed by the am- 
 monia, which h<o difappeared. Ammo.ii:!, therefore, 
 mull be compofed of azot and hydrogen. Mr Berthol- 
 Ict proved, that ammonia was compoled of thefe ingre- 
 dients by a number of other experiments. For inllance, 
 if the oxide of copper Vic heated in rontaft with ammo- 
 niacal gas, it is reftored to the metallic flate; the ammo- 
 nia difappears, a quantity of water is formt'd, and azotic 
 gas is difengaged. It follows from Mr BerthoUet's ex- 
 periments, tiiat ammonia is compofed of 1 2 I parts of azot 
 and 29 of hydrogen *. According to Dr Auftin, it is *Mem.Par. 
 compofed of 121 parts of a/ot, and 33 of hydrogenf . !'^^£y 
 
 After the compofition of ammonia had been thus ^^- JrulJ~.l^%i. 
 certained, it became a qneftion of fome confequence, _^,S5 
 Whether it could be formed artificially ? Dr AuIHn ac- Furmatiou 
 cotdinjrlv mixed hydrogen and azotic gas together in "! ="""''" 
 the proper proportions, and endeavoured to make them 
 combine by the application of heat, by eleftricity, and 
 by cold ; but he found, that while thefe two fubftanees 
 were in a gafeuus flate, they could not be combined by 
 any method which he could devife. It could not be 
 doubted, however, that the combination often takes place 
 when thefe bodies are prcfented to each other in a dif- 
 ferent form. Dr Prieftley | and Mr Kirwan || had aflu- t On Air, il. 
 ally produced it, even before its compofition was known. "J'^^ h * . 
 Accordingly he found, that when tin is moiitened '^'^^^ticAirAui. 
 nitric acid, and after being allowed to digeft for a mi- 
 nute or two, a little potafs or lime is added, ammonia is 
 immediately exhaled j. In that cafe; the nitric acid and 5 Dr At^f- - 
 the water which it contains are decompoftd ; the oxygen ' "• 
 of each unites with the tin, and reduces it to the ftate of 
 an oxide; and at the fame time the hydrogen of the wa- 
 ter combines with the azot of the acid, and forms ammo- 
 nia, which is driven off by the ftronger affinity of the pot- 
 afs or lime. Dr Auftin fuecceded alfo in terming am.- 
 monia by feveral other methods. He introduced into a 
 glafs tube filled with inercury a little azotic gas, and thea 
 put into the gas fome iion fih'ngs moiftened with water 
 The iron dccompolcs the water and combines with its ■ 
 oxygen ; and the hydrogen meeting with azot at the mo- 
 ment of its admiihon, combines witli it, and forms ammo- 
 nia. This experiment ftiews, that the gafeous ftate of the 
 azot does not prevent its combination with hydrogen. 33s 
 
 Ammonia may be combined with fuiphur by mixing Sulphnrrt. • 
 together two parts of muriat of ammonia (ammonia ''f^"""'^" 
 combined with muriatic acid), two parts of lime, and 
 one part of fulphm-, and diiliUing ; a yellow liquor is 
 obtained, which contains fulphurct of ammonia. If is 
 capable of cryllallizing. 
 
 The phofphuret of ammonia is unknown. 
 Ammonia is capable of combining with f'j\cral of the 
 metallic oxides, particularly copper. 
 
 It combuies with fixed oils, and forms /;.//>. 
 The order of its affinities h precifely the fame with 
 that of the fixed alkalies. 
 
 Chap. 
 
 (q^) We have arlopted this word, which is Dr Black's, becaufe we think it preferable to ammov'uu or ammc 
 r.iaca, the words propofed and uftd by the French chemitis. .
 
 304 
 
 Acii!s, 
 
 3S7 
 P-optrties 
 of acid.-. 
 
 3S8 
 Theories 
 about the 
 acid prin- 
 
 3S9 
 I.avoifisr's 
 theory. 
 
 C H E M I 
 
 Chap. V. Of Acids. 
 
 Substances pofl'efltd of the following properties are 
 denominated ac'uls. 
 
 1. When aj>plied to the tongue they excite that fen- 
 fation which is called yc/j/r or ac'td. 
 
 2. Tlicy change the blue colours of vegetables to a 
 red. The vegetable blues employ>.(' for this purpofe 
 are geii>;rallj- tin.?t\ire of li'.miis and fyrup of violets or 
 of radifhes, which have obtained the name of rciigrits 
 or tejls. If thefe colours have been previoufly converted 
 to z great by alkalico, the acids reilore them again. 
 
 3. They unite with water in almoft any proportion. 
 
 4. They combine with all the alkalies, and mod of 
 the metallic o.Kidcs and earths, and form with them thofe 
 compc'unds which are called ueulral fahs. 
 
 It mull bj remarked, however, that every acid does 
 not r.ofTefs all thefe properties ; but all of them poflcfs 
 a fuliicient number of them to dillinguifli them from 
 other fubllances. And this is the only purpofe which 
 artificial definition is meant to anfwer. 
 
 Paracelfus believed that there was only one acid prin- 
 ciple in nature, vhich communicated tafte and fulubili- 
 ty to the bodies in which it was combir.ed. Becchcr 
 embraced the fame opinion ; and added to it, that this 
 acid principle was a compound of earth and water, 
 which he confidered as two elements. Stahl adopted 
 the theory of Beccher, and endeavoured to prove, that 
 his acid principle was fulphuiic acid; of which, ac- 
 cording to him, all the other acids were mere com- 
 pounds. But hit. proofs were only conjedures or vague 
 experiments, from which nothing could be deduced. 
 Neverthelefs, his opinion, like every other which he ad- 
 vanced in chemiftry, continued to have fupporters for a 
 long time, and wa^ even countenanced by Macquer. 
 At laft its defefts began to be perceived ; Bergman and 
 Scheele declared ojienly againit It ; and their difcove- 
 ries, together with thofe of the French chemifl;, not- 
 withllanding the ill-natured attempts of Monnet to fnp- 
 port it, demonftrated the falfehood of both parts of the 
 theory, by (hewing that fulphuric acid did not exHt in 
 the other acids, and that it was not compofed of water 
 and earth, but of fulphur and oxygen. 
 
 The opinion, however, that acidity is owing to fome 
 principle common to l\\ the falts, was not abandoned. 
 Wallerius, Meyer, and Sage, had advanced different theo- 
 ries m fucceflion about the nature of this principle ; but 
 as they were founded rather on conjefture and analogy 
 than direft proof, they obtained but few advocates. 
 At laft Mr Lavoifier, by a number of Ingenious and ac- 
 curate experiments, proved, that feveral combuftlble fub- 
 ftanccs when united with oxygen form acids ; that a 
 great number of acids contain oxygen ; and that when 
 this principle is feparated from them, they lofe their 
 acid properties. He concluded, therefore, that the aci- 
 difying principle is oxygen, and that acids are nothing 
 elfe but combuftlble fubftances combined with oxygen, 
 and differing from one another according to the nature 
 of the combuftlble bafe. This conclufion has been con- 
 
 S T R Y. Part II. 
 
 firmed by every fubfequent obfervation. All the acids Arid*, 
 hitherto analyfcd contain oxygen, one perhaps excepted, ' 
 
 the Prtijff add, which pofielfes properties fo difl'erent 
 from the reft, that it might, without gre;)t impropriety, 
 be placed in a diftinft clafs. It Is probable, therefore, 
 that thofe acids which it has not yet been polFible to 
 decompofe cor.fift of oxygen combined with a combuf- 
 tlble bafe : but till this analyfis Ii.is adlually been ac- 
 coniplilhed, the theory of Mr Lavoifier cannot be con- 
 fidered as completely demonftrated (r). 39<* 
 
 The acids at prefent known amount to about 39,'''.'^"''''* 
 molt of which have been examined within thefe 30' 
 
 years. i lieir names are as h 
 
 dUows 
 
 
 I. Sulphuric acid, 
 
 21. 
 
 Benzoic, 
 
 2- Sulphurous, 
 
 22. 
 
 Succinic, 
 
 3. Nitric, 
 
 *3- 
 
 Camphoric, 
 
 4. Nitrous, 
 
 24. 
 
 Suberic, 
 
 5. Muriatic, 
 
 2J- 
 
 Laccic, 
 
 6. Oxy muriatic. 
 
 26. 
 
 Pyromucous, 
 
 7. Pliofphoric, 
 
 27. 
 
 Pyrolignous, 
 
 8. Phofphorous, 
 
 28. 
 
 Pyrotartarous, 
 
 9. Boracic, 
 
 29. 
 
 PrufTic, 
 
 10. Fluoric, 
 
 30- 
 
 Formic, 
 
 1 T . Carbonic, 
 
 3»- 
 
 Scbacic, 
 
 12. Acetic, 
 
 3^- 
 
 Bombic, 
 
 13 Acetous, 
 
 33- 
 
 Zoonic, 
 
 14. Oxalic, 
 
 34- 
 
 Arfenic, 
 
 15. Tartarous, 
 
 35- 
 
 Tungftic, 
 
 16. Citric, 
 
 36- 
 
 Molybdic, 
 
 17. Malic, 
 
 37- 
 
 Chromic, 
 
 18. Ladle, 
 
 38. 
 
 Platinic, 
 
 19. Saccholadic, 
 
 3y- 
 
 Stannic, 
 
 20. Gallic, 
 
 
 
 Thefe acids (hall form the 
 
 fubjeCl of the foUowinij 
 
 feclions. 
 
 
 
 \ 
 
 Sect, I. 
 
 Of Sulphuric Acid. 
 
 Sulphur combines with two different quantities of 
 oxygen : with the fmaller quantity it {orm„ Julphuroiis 
 acid ; with thi; hrgtr fu'p/juric acid. The laft of thcle 
 is the fubjed of the prefent feftion. ^gr 
 
 The ancients were acquainted with fome of the com-'^'fcovery 
 pounds into which fulphuric acid enters ; a/am, for in-" ," P""""' 
 ftance, ana gr^cn -jitnol : but they appear to nave been 
 ignorant of the acid itfelf. It Is firft mentioned in the 
 works of Bafil Valentine, which were publiflied about 
 the end of the 15th century. 
 
 It was for a long time obtained by diftllllng green vi- 
 triol, a fait compofed of fulphuric acid and green oxide 
 of Iron ; hence it was called rAI of vitriol, and afterwards 
 vitriolic acid. Another method of oVitalnlng it was by 
 burning fulphur under a glafs bell ; hence it was called 
 alfo oleum Julphuris per campanam. The French che- 
 mifts in 1787, when they formed a new chemical no- 
 menclature, gave it the name of yui^ZiuWc artf/. , 
 
 At prefent it is generally procured by burning aMethoiof 
 mixture of fulphur and nitre in chambers lined withprocuringit, 
 lead. The theory of this procefs requires no explana- 
 tion. The nitre fupplies a quantity of oxygen to the 
 
 fulphur. 
 
 k 
 
 (r) This theory has been carried fo far by fome chemlfts, that they have confidered it as a conclufive proof 
 that oxygen did not enter into the compofition of a body, if they could fhew that the body was not an acid. 
 Thus, according to them, <water cannot contain oxygen, becaufe water is not an acid.— ^nt furely no theory, 
 however ingenious and fatisfadory, can for a moment be put in competition with experiment. The ways of 
 Nature are not as our ways, nor her thoughts as our thoughts.
 
 Part H. 
 
 CHEMISTRY. 
 
 Cor, 
 
 394 
 Its proper- 
 ties. 
 
 Sulphuric fulpliur, and tlie air of tlie atmofjjliere furnidies the reft. 
 ^" '~^- Tlic acid tluis obtained is not quite pure, containing a 
 * little potals, lome lead, and peiliaps a!fo nitric and lul- 
 pluirous acids. Tliefe acids may be driven off by ap- 
 plying for foine time a gentle heat, and afterwards the 
 ,n, fulphuric acid itfelf may be diililled over pure. 
 Its compo It appears from an experiment of Mr BcrthoUet, 
 jientpiits. that fulpiuiric acid contains 63,2 parts of fiilphur, and 
 * Mtm. 3f>i8 of oxygen. He afcertained, in the iirll place *, 
 Far. 17S1, that nitre is totally decoinpofcd by being heated with 
 *3*' 3th of f.ilpliur. He then niixcd together 288 grains of 
 
 nitre and j i of fnlphur ; and after expofing them to 
 a fnfficient heat, he fo<ind 12 grains of fulphur fnbli- 
 i Mem. med, and 22S grains of fulpliat of potafsf. But the 
 J'ar. 17S2, fum of the ingredients was 360 grains ; confcquently 
 120 grains liave been diOi paled. All this lois mull have 
 been fuffercd by the acid of the nitre, for the heat was 
 too fmall to feparate any of the alkali. According to 
 Mr Kirwan, 288 grains of nitre contain 132,96 ol al- 
 kali, and 155,-4 of acid. 155,04 — I 2C ,= 35,04 = 
 quantity of oxygen furniflled by the nitie to convert 
 60 grains of fulphur into acid. 
 
 Sulphuric acid is a liquid, fomewhat of an oily con- 
 fiftence, tranlparent and colourlefs as water, without 
 any fmell, and of a very ilrong acid tafte. When ap- 
 plied to animal or vegetable fubilances, it very foon de- 
 ftroys their texture. 
 
 It always contains a quantity of water; part of which, 
 however, may be driven off by the application of a mo- 
 derate heat. This is called concern rating the acid. When 
 as much concentrated as poffible, its fpecific gravity is 
 2,000. 
 
 It changes all vegetable blues to a red, except indigo. 
 According to Erxleben, it boils at 546°; according 
 to Bergman, at 572". 
 
 When expofed to a fufficient degree of cold, it cry- 
 ftallizes or freezes ; and after this has once taken place, 
 it freezes again by the application of a much inferior 
 cold. Moreveau froze it at — 4« ; it affumcd the ap- 
 pearance of frozen fnow. After the proccfs began it went 
 on in a cold not nearly fo intenfe. The acid melted flow- 
 ly at 27,1;"; but it froze again at the fame tempera- 
 ture, and took five days to melt in the temperature of 
 43" J. Chaptal, who manufaitured this acid, once ob- 
 ferved a lar^e glafs vcffel full of it cryftallized at the 
 temperature of 48°. Thefe cryitals were in groups, 
 and confided of flat hexahedral prifms, terminated by 
 a fix fided pyraniid. They felt hotter than the fur- 
 i; /"'!'' ''' rounding bodies, and melted on being handled J. Chap- 
 ,-■/' ' tal has obferved, that fulphuric acid, in order to cry- 
 ftallize, murt not be too concentrated. This obferva- 
 tion has been extended a good deal further by Mr Keir. 
 He found, that fulphuric acid, of the fpecific gravity of 
 1,780, froze at 45°; but if it was either much more 
 SuppL. Vol. I. Part. H. 
 
 505 
 
 39.5 
 Its cry. 
 aais. 
 
 \ Vncyct 
 Method. 
 
 Chim. i. 
 376. 
 
 103^. 
 
 or much lefs concentrated, it required a much greater Su'iliuric 
 cold for congelation *. "' •'"'• ^ 
 
 Sulphuric acid has a very ftrong attraction for water. « p/^^i 
 Neumann found, that when expofed to the atmofphere Trdnf. 
 it attrafted 6,25 times its own weight. Mr Gould !x«vii. 
 found, that j8o grains of acid, when expofed to the ''•'" ''• 
 atmofphere, attracted 68 grains of water the fnll day,,,,-^^,,;, 
 58 the fecond, 39 the third, 23 the fourth, 18 thcfor water, 
 fifth, and at lall only 5, 4, 3,4, 3, &c. The 28tK 
 day, the augmentation was only half a grain f. Thct Pli''- 
 affinity therefore between fulphuric acid and water, as ^""•'" 
 is the cafe in general with other fubilances, becomes 
 weaker the nearer they approach to fatnration. He 
 does not fpecify the fpecific gravity of his acid; but as 
 it only attracted 3,166 times its own weight, it could 
 not have been very concentrated. 
 
 When fulphuric acid is mixed with water, a great 
 quantity of caloric is evolved. A mixture of equal 
 parts ot theie liquids cauies a heat almoil equal to that 
 of boiling water. Lavoifier and Dc la Place found, 
 that when 2,625 "^^' f™y °^ fulphuric acid, of the fpe- 
 cific gravity 1,87058, was mixed with i,969lbs. troy 
 of water, as much caloric was evolved as melted 4,1226 
 pounds troy of ice, or as much caloric as the ncid and 
 water would have given out had they been heated with- 
 out mixture to 15 5,9'-' J- This caloric is owing chiefly, f •^"»»- 
 if not folely, to the increafe of denfity in the water; for ''"'■• '''"' 
 when equal quantities of fulphuric acid and water arc 
 mixed together, the fpecific gravity is much greater 
 than the mean ; and it has been formerly (liewn, that 
 whenever bodies become denfcr they give out caloric. wy 
 
 Sirice there is fuch n Ilrong affinity between fulphu-Stren(j'hof 
 
 ric acid and water, and fince the denfity of the mixture '^'li'^^'"^ 
 
 is different from the mean denfity of the ingredients, ;t ■'?"' " /"*" 
 , Li r 1 n ■ , nous <len- 
 
 becomes a problem or the greateit nnportance to deter- fmes. 
 
 mine how much of the llrongeft fulphuric acid that can 
 be prepared exills in any given quantity of fulphuric 
 acid of inferior fpecific gravity, and which confcquently 
 confifts of a determined quantity of this Ilrong acid di- 
 luted with water. 
 
 This problem has been folved by Mr Kirwan J. He^/rj/j 
 took fulphuric acid of the fpecific gravity 2,000, which Trj//. iv. 
 is the llrongeft that can be procured, for his Itandard, and 
 the point was to determine how much of this ftandard 
 acid exifted in a given quantity of acid of inferior denfity. 
 
 He concluded, from a number of experiments with 
 fulphui-ic acid, of the fpecific gravities 1,8846* 1,8689, 
 1,8042, 1,7500 (for he could not procure an acid of 
 the fpecific gravity 2,000 at the temperature of6oSin 
 which his experiments were performed), that when 
 equal parts of (landard acid and water are mixed, the 
 denfity is increafed by Vr'-'' P^'- "^ ''"^ whole mixture. 
 Then, by applying a formula given by Mr Poujet (s), 
 he calculated, that the increafe of denfity, on mixing 
 Q^q different 
 
 (s) Mr Poujet undertook the examination of the fpecific gravity of alcohol mixed with different quantities of 
 water. He took for his ftandard alcohol whole fpecific gravity was 0,8199, at the temperature of 65,75'^. He 
 then formed ten mixtures ; the firft containing nine meafures of alcohol and one of water, the fecond eight mea- 
 fures of alcohol and two of water, and fo on, till the laft contained only one meafure of alcohol and nine of water. 
 He took care that each of thefe meafures ffiould contain equal bulks, which he afcertained by weight, obferving 
 that a meafure of water was to a meafure of alcohol as 1 to 0,8199. Thus 10000 grains of virater and 8199 of 
 alcohol formed a mixture containing equal bulks of each. From the fpeij/lii; gravity of each of thefe mixtures 
 he difcovered how much they had diminiflted in bulk in confequence of mixture, by the following method. 
 
 Calling
 
 3o6 
 
 CHEMISTRY. 
 
 Part II. 
 
 Sulphuric JifL-icnt quantities of ftandard acid and water, was as 
 ■*"**• in the following table : 
 
 Number of 
 
 Number of 
 
 .-iujjn.enta- 
 
 part- of 
 
 parts of Itan- 
 
 tion ' f d^n- 
 
 water. 
 
 i.'.ard acid. 
 
 f.ty. 
 
 5 
 
 95 
 
 0,0352 
 
 lO 
 
 90 
 
 0,0479 
 
 15 
 
 85 
 
 0,0679 
 
 20 
 
 80 
 
 o,oi*_56 
 
 25 
 
 75 
 
 0,0699 
 
 30 
 
 70 
 
 0,1119 
 
 .35 
 
 65 
 
 0,1213 
 
 40 
 
 60 
 
 0,1279 
 
 1 4^ 
 
 55 
 
 0,1319 
 
 ' 50 
 
 iO 
 
 0.13^3 
 
 The firil 50 numbers of the following table were 
 formed by adding thefe augmentations to the fpecific 
 gravity of the above mixture found by calculation, and 
 taking the arithmetical mean for the intermediate quan- 
 tities. The remaining numbers were formed from ac- 
 tual obfervation. He found by the firft part of the 
 table, that 100 parts of acid, of the fpecific gravity 
 1,847^, contained 88,5 parts ftandard, confequently 
 
 400 grains of this acid contain 354 grains ftandard. He Sulphuric 
 took fix portions of this acid, each containing 400 , ""°- 
 grains, and added to them as much water as made them 
 contain rcfpeftively 4?-', 46, 44, 42, 40, 38 grains ftan- 
 dard. The quantity of water to be added in order to 
 produce this effefl, he found by the following method. 
 Suppofe X = the quantity of water to be added to 400 
 parts of acid, that the mixture may contain ^^ per cent. 
 of ftandard acid. Then 400 -f- x : 354 : : 100 : 48, and 
 confequently x ^ 337, ?• After finding the fpecific 
 gravity of thefe, the half of each was taken out, and as 
 much water added ; and thus the fpecific gravities, cor- 
 refponding to 24, 23, 22, 21, 20, 19, were found. 
 Then fix more portions, of 400 grains each, were ta- 
 ken, of the fpecific gravity 1,8^93, and the proper 
 quantity of water added to make them contain ^6, 34, 
 32, 30, 28, 26 per cent, of ftandard. Their fpecific 
 gravities were found, the half of them taken out, and as 
 much water added; and thus the fpecific gravity of 18, 
 17, 16, 15, 14, and 13 found. Care was taken, after 
 every addition of water, to allow the ingredient fuffi- 
 cient time to unite. 
 
 The laft 1 1 numbers were only found by analogy } 
 obferving the feries of decrement of the four laft num- 
 bers before them. 
 
 Table 
 
 Calling A the real fpecific gravity of any of the mixtures ; B its fpecific gravity found by calculation, fup- 
 
 pofing no diminution of bulk; n the number of meafures compofing the whole mafs; n — x the number to which 
 
 it is reduced in confequence of mutual penetration— it is evident, fince the increafe of denfity does not diminifli 
 
 A -p 
 
 the weight of the whole mafs, that nB = n — «XA. Therefore x = — v — X n, or (making n = l ) = 
 
 •^ " -^ ■" is therefore the diminution of volume produced by the mixture. 
 
 A A 
 
 The following table contains the refult of MrPoujet's experiments, calculated according to that formula; the 
 whole volume or n being := 1 . 
 
 Meafu 
 Water. 
 
 res of 
 AIcoh(»l. 
 
 Diminution of 
 the whole vo- 
 lume = I by 
 experiment. 
 
 By calculation. 
 
 1 
 
 9 
 
 0,0109 
 
 0,0103 
 
 2 
 
 8 
 
 0,0l!<7 
 
 0,0184 
 
 3 
 
 7 
 
 0,0242 
 
 0,0242 
 
 4 
 
 6 
 
 0,0268 
 
 0,0276 
 
 5 
 
 S 
 
 0,0288 
 
 
 6 
 
 4 
 
 0,0266 
 
 0,0276 
 
 7 
 
 3 
 
 0,0207 
 
 0,0242 
 
 8 
 
 3 
 
 0,01 23 
 
 0,0184 
 0,0103 
 
 9 
 
 I 
 
 0,0044 
 
 It is evident, from this table, that the diminution of the bulk of the mixture follows a regular progreffion. 
 It is greateft when the meafures of water and alcohol are equal, and diminiflies as it approaches both ends of the 
 feries. Mr Pou}et accounts for this by conceiving the alcohol to be dilfolved in the water, which retains a part 
 of it in its pores, or abforbs it. The quantity abforbed ought to be in the ratio of that of the folvent and of the 
 body diflblved, and each meafure of water will retain a quantity of alcohol proportional to the number of mea- 
 fures cf alcohol in the mixture. Thus in a mixture formed of nine meafures of alcohol and one of water, the 
 water will contain a quantity of alcohol = 9; in one of efght meafures of alcohol and two of water, the 
 water will contain a quantity of alcohol = 8. Therefore the diminution of bulk in each mixture is in a ratio 
 compounded of the meafures of alcohol and water which form it ; in the above table, as I X 9, 2 X 8, 3 X 7, 4 X 6, 
 &c. And in general, taking the diminution of bulk when the meafures of both liquids are equal for a conftant 
 quantity, and caUiDg it c, calling the number of meafures n, the number of meafures of alcohol x, the increafe of 
 
 denfity
 
 Part ir. 
 
 Table of tin ^ant'ily of Standard Sulphuric Acid, 
 Specific Gravily 2,000 in Sulphuric Acid of inferior 
 tlcnjity, Temperahtre 60". 
 
 CHEMISTRY. 307 
 
 But we liave no reafon to fiippofe that ftilphnric? acid, Sulphuric 
 at the denfity 2,000, is free from all mixture of water ; ^^^ . 
 
 ICO jarts, 
 
 Contain 
 
 100 fai t", 
 
 i'ontain 
 
 100 part-, 
 
 Cf»n!ain 
 
 at the Ipe- 
 
 of ftlill- 
 
 at ttiL- f'l.e- 
 
 of i>an 
 
 at the Spe- 
 
 pf ftan- 
 
 cific gra- 
 
 dard aciu 
 
 cific gra- 
 
 Jari! aciii 
 
 cific gra- 
 
 dard acid 
 
 vit," 
 
 
 vity 
 
 
 vity 
 
 
 2,000 
 
 100 
 
 1,6217 
 
 67 
 
 1,2847 
 
 34 
 
 1,9859 
 
 99 
 
 1,6122 
 
 66 
 
 1,27^7 
 
 33 
 
 |>y7i9 
 
 98 
 
 1,6027 
 
 65 
 
 1,2668 
 
 3« 
 
 i>9579 
 
 97 
 
 1.5932 
 
 64 
 
 1,2589 
 
 31 
 
 1.9439 
 
 96 
 
 1,5840 
 
 63 
 
 1,2510 
 
 30 
 
 1,9299 
 
 95 
 
 1.5748 
 
 62 
 
 1,2415 
 
 29 
 
 1,9168 
 
 94- 
 
 1,5656 
 
 61 
 
 1,2320 
 
 28 
 
 1,9041 
 
 91 
 
 '.5564 
 
 60 
 
 1,2210 
 
 27 
 
 1,8914 
 
 92 
 
 '.5473 
 
 59 
 
 i,2ior 
 
 26 
 
 1,8787 
 
 9' 
 
 ^^Si^'i 
 
 58 
 
 1,2009 
 
 25 
 
 1,8660 
 
 90 
 
 1,5292 
 
 57 
 
 1,1918 
 
 24 
 
 1,8542 
 
 89 
 
 1,5202 
 
 56 
 
 1,1836 
 
 23 
 
 1,8424 
 
 88 
 
 1,5112 
 
 S'i 
 
 III 746 
 
 22 
 
 1,8306 
 
 87 
 
 1,5022 
 
 54 
 
 1,1678 
 
 21 
 
 1,8188 
 
 86 
 
 '.4933 
 
 Si 
 
 1,16(4 
 
 20 
 
 1,8070 
 
 85 
 
 1,4844 
 
 52 
 
 I. '53' 
 
 >9 
 
 '.7959 
 
 84 
 
 ^AISS 
 
 51 
 
 1,1398 
 
 18 
 
 1,7849 
 
 83 
 
 1,4666 
 
 50 
 
 1,1309 
 
 17 
 
 1.773** 
 
 82 
 
 '.4427 
 
 49 
 
 1,1208 
 
 16 
 
 1,7629 
 
 81 
 
 1,4189 
 
 48 
 
 1,1129 
 
 '5 
 
 i,75'9 
 
 80 
 
 1,4099 
 
 47 
 
 1,1011 
 
 14 
 
 1,7416 
 1,7312 
 
 79 
 
 78 
 
 1,4010 
 1.3875 
 
 46 
 45 
 
 ',0955 
 
 '3 
 
 1,0X96 
 
 12 
 
 1,7208 
 
 77 
 
 '.374' 
 
 44 
 
 1.0833 
 
 11 
 
 1,7104 
 
 76 
 
 1,3663 
 
 43 
 
 1,0780 
 
 10 
 
 1,7000 
 
 75 
 
 '.3586 
 
 42 
 
 1,0725 
 
 9 
 
 1,6899 
 
 74 
 
 1.3473 
 
 4« 
 
 1,0666 
 
 8 
 
 J, 6800 
 
 73 
 
 1.3360 
 
 40 
 
 1,0610 
 
 7 
 
 1,6701 
 
 72 
 
 1.3254 
 
 39 
 
 1,05 ;5 
 
 6 
 
 1,6602 
 
 71 
 
 1.3 '49 
 
 38 
 
 1,0492 
 
 5 
 
 1,6503 
 
 70 
 
 1,31 = 2 
 
 37 
 
 1,0450 
 
 4 
 
 1,6407 
 
 69 
 
 1,3056 
 
 36 
 
 1,0396 
 
 3 
 
 1,6312 
 
 68 
 
 1,2951 
 
 35 
 
 1.0343 
 
 ^ 
 
 fo far from that, we know for certain that it contains a ,yg 
 conliderable proportion ; for when it is combined with Quantity 
 other bodies, barytcs, for inftance, or potafp, there is a;'' ''=='1 ••'i^' 
 coniiderable quantity of water which remains behind,).", J'"''^ 
 and docs not enter into the combmation. Now, is ita^jj, 
 poffiblc to determine what would be the denfity of ful- 
 phuric acid, fuppofing it to be deprived of all water, or 
 at leail of all water except what is neceflfary for its ev., 
 iftence as an acid ? or to determine, how much real acid 
 exifts in a given quantity of ilandaid acid ? 
 
 Homberg firfl. attempted to anfwer this queftion. It 
 was afterwards undertaken by Bergman, and Wenzel, 
 and Wiegleb. They do not inform us of the quantity 
 of water contained in a given weight of acid, but they 
 put it in our power to find it, by informing us how 
 much real acid is neceflary to laiurate a given quantity 
 of potafs. Their refpetlive experiments give the fol- 
 lowing numbers : 
 
 -- • - Wenze!. I Wiegleb. 
 
 I03 parts of pot-") 
 afs require J 
 
 Homb. 
 38.3 
 
 Berg. 
 78.5 
 
 82,63 I 10'. 92- 
 
 Homberg ufed carbonat of potafs, and did not take 
 into coniideration the carbonic acid driven off by the 
 fulphuric. When this is taken in, his number fiiould 
 be 54 inllead of 38,3. 
 
 Now to difcover the quantity of real acid in any ful- 
 phuric acid mixture, we have only to find out how much 
 potafs it would require for faturation. The differences 
 between the above refults are fo great, that there was 
 reafon to fufpedl their accuracy. Mr Kirwan therefore 
 attempted to afcertain the denfity of pure lulphuric 
 acid by another method, and he rated it at ,,226. As 
 this method has been already defcribed in the article 
 Chemistry, Encycl. we cannot enter upon it here. 
 At any rate, it would be unneceffary, as many of the 
 principles upon which Mr Kirwan went were erroneous, 
 as Mr Moi-veau* and Mr Keir f have fufficiently (hewn ; * Encye. 
 and Mr Kirwan, with his ufual candour, has accord- '^ '<;'*"'• art. 
 ingly abandoned it, and adopted another method which 't;^.'"'.''- 
 is not liable to the fame exceptions. He diffolved 1523,5 m^^^^art 
 Q_q 2 grains art, yf«V. ' 
 
 "ienfity or diminution of bulk z ,• we fhall have f : s : 
 
 n = I ) = 4 c .■>c^ 
 
 The diminution of bulk, calculated according to this formula, make the lafl; column of the above table. They 
 correfpond very well with experiment, while the meafures of alcohol are more than thofe of water, but not when 
 the reverfe is the cafe. This Mr Poujet thinks is owing to the attraftion which exiils between the particles of 
 water, and which, when the water is confiderable compared with the alcohol, refills the union of the water with 
 the alcohol. 
 
 By the formula s ^ 
 
 4 r n jc — 4 <r k' 
 
 , the quantity of alcohol of the flandard may be determined in any mix- 
 
 Jure where the alcohol exceeds the water. 
 
 Let the number of meafures, or the whole mafs • - - =1 
 
 The meafures of alcohol ---....- := x 
 
 The diminution of bulk at equal meafures - - • - ■=: c 
 
 The diminution of bulk of a mixture containing x meafures of alcohol - = 4 c « ■ 
 
 The fpecific gravity of water - . . . - zn a 
 
 The fpecific gravity of the alcohol - . - . . = ^ 
 
 The fpecific gravity of the unknown mixture - - • =: > 
 
 .4<:.x-
 
 Thi 
 
 Part IT. 
 
 as Morveau lias Sulphuric 
 
 iilj/huric acid deprived of the water with. 
 
 a folid form, or cryftallized, 
 
 fliewn, is 
 
 which it is ufually combined. When this glacial acid, 
 
 as it has been called, is expofed to the air, it rifes in 
 
 white fumes, and is foon diflipattd. This fingular effeft 
 
 is produced by its violent attraiition for the water which 
 
 Acid. 
 
 «.£->, 
 
 308 CHEMISTRY. 
 
 Sulrhucic grains of pure carbonat of potafs, dried in a red heat, in 
 . ■^"'^ diftillcd water. The whole weighed 4570 grains. He 
 ' took ^60 grains of this mixture, which contained 120 
 
 grains of carbonat of potafs, and faturated it with pure 
 fulphuric acid of the fpecific gravity 1,565, which, ac- 
 cording to the above table, contained 61 percent, of 
 
 ilandard acid. The acid required for faturating the fo- exifts m atmofpheric air. When thrown into water, it 
 
 lution of potafs amounted to i 30 grains, and contained felzes it with violence; a great deal of caloric is evolved, 
 
 therefore 79 of ftandard. The carbonic acid difenga- fufficient, if the quantity of water be not too great, to 
 
 ged was ^4 grains, and confeqiiently the quantity of al- elevate the whole in vapours * 
 
 kali was 1 20 34 = 86 grains. The fulution being Sulphuric acid is capable of decompofing alcohol and ^''''""l- 
 
 turbid, was diluted with 3238 grains of water. Its oils ; and when alfifted by heat, it dctompoles alfo fome -J^' '' 
 
 fpecific gravity was then 1,013 ^^ ^^^ temperature of of the metaUic oxides which contain the greateft quan- ' 399 
 
 60'-'. The weight of the whole was ^694 grains. Forty- tity of oxygen ; as red oxide of lead, black oxide of man- .^fiion oj 
 
 five grains of fulphat of potafs (potals combined with ganefe. It decompofes likevvife all the fulphurets and ''^"' ^j-"* 
 
 fulphuric acid), diffolved in 1017 grains of diftiUed wa- phofpliurets which have an alkaline or earthy bafis. bodieJ'" 
 ter, have the fame fpecific gravity at the fame tempera- It oxidates iron, zinc, and manganefe, in the cold, 
 
 ture • from whence it follows, that the proportion of By the aififtance of heat it oxidates lilver, mercury, 
 
 fait in each was equal. But in the lad folution the quan- copper, antimony, bifmuth, arfenic, tin, and tellurium. 
 
 I At a boiling heat it oxidates lead, cobalt, nickel, mo- 
 
 tity of fait was — -g of the whole ; therefore the quan^ lybdenum. It does not aft upon gold, platinum, tung- 
 
 tityof faltin theVirftwas l^j = ^j9,52grs. Now lUn, nor titanium . ^ „ , „ ,. ^ „,. 
 
 ' 23,0 It unites readily with all the alkalies, the alkaline 
 
 of this weight 86 grains were alkali ; the remainder, earths, alumina, and jargonia, and with mod of the me- 
 
 therefore which amounts to 70,52 grains, muft be tallic oxides, and forms falts denominatedya;^,6a/j. Thus 
 
 acid. But the quantity of ftandard acid employed was the combination of fulphuric acid and foda is called /a/- 
 
 79 grains ; of this there were 8^ grains which did not phal of foda ; the compound of fulphuric acid and lime, 
 
 enter into the combination, and which muft have been fulphat of lime, and fo on. It does not aft upon filica 
 
 pure water : 79 parts of ftandard acid, therefore, con- nor adamanta. 
 
 tain at leaft 8,5 parts of water, and confequently 100 The affinities of fulphuric acid are as follows f : 
 parts of ftandard acid contain 10,75 parts of water. It Barytes 
 
 X>i^ionary, 
 art. Aciii. 
 
 only remains now to confider how much water fulphat 
 of potafs contains. Mr Kirwan thinks it contains none, 
 becaufe it lofes no weight in any degree of heat below 
 ignition, and even when expofed to a red heat for half 
 an hour it hardly lofes a grain. This is certainly fuf- 
 ficient to prove, at leaft, that it contains very little wa- 
 ter ; and confequently we may conclude, with Mr Kir- 
 wan, that 100 parts of fulphuric acid, of the fpecific 
 gravity 2,000, are compofed pretty nearly of 89,25 of 
 pure acid and 10,75 o^ water. This method ufed by 
 Mr Kirwan is nearly the fame with that propofed by 
 Mr Keir *. 
 
 It feems even poffible to obtain fulphuric acid free 
 from all the water that may not be necefTary to its acid 
 ftate. When it is procured by diftillation from green 
 vitriol, if the receiver be changed after the procefs has 
 gone on for fome time, a quantity of acid is obtained in 
 
 Strontites J, 
 Potafs, 
 Soda, 
 Lime, 
 Magnefia, 
 Ammonia, 
 Alumina, 
 Jargonia ij ? 
 Oxide of zinc, 
 iron. 
 
 manganefe, 
 cobalt, 
 nickel, 
 lead, 
 tin, 
 
 copper, 
 . bifmuth, 
 
 400 
 Its af1ini» 
 ties. 
 
 f See Bus- 
 man and 
 
 I Dr Hope, 
 Tranf £Jiit^ 
 
 jinn, de 
 Chim. Xiii, 
 
 30S. 
 
 Oxide 
 
 Then fince the increafe of denfity does not change the weight of the whole, i — x y, a ■{■ b it ^s 
 
 V 4'^.)' ^ V 8<rj 
 
 i 
 
 1 4 <• A- -f 4 C X" X J'. 
 
 Hence « = o,j 
 
 ^c y 
 a — a jc + ^* 
 
 •O'j) 
 
 •' I — i^c x-^r ^c «' 
 And making a = 1, b zz 0,8199) ' = 0,02 88 
 0,1801 
 
 « = 0,5 — 
 
 J' = 
 
 o»2304> 
 
 0,1801 X 
 
 t. /_L::i^+(2zl5£i 0,5) 
 
 V 0,1152;! \©,2304> / 
 
 I — 0,115a* + 0,1 152 x'- See Iri/b Tranf. HI,
 
 Part IT. 
 
 Sulphurous 
 At id. 
 
 4Ct 
 
 Oxide of antimony, 
 
 - arfenic, 
 •^— — mercury, 
 -' iilver, 
 
 gold, 
 
 - ■ ■ platinum, 
 Oil, 
 Water. 
 
 Sect. II. Of Sulphurous /IclJ. 
 
 Component SuLrHunous acid is compofed of fiilphur and oxy- 
 !'•"■'" "f*^"'" gen combined : the proportions have not been afcer- 
 cid"""^ *" tained ; but the faft itielf, and that the quantity of 
 oxygen is lefs than what enters into fulphuric acid, has 
 been proved beyond the polUbility of doubt. Neither 
 can It be doubted, though the fuA has not been attend- 
 ed to, that in this acid the fulphur and oxygen mutu- 
 ally faturats each other ; and that fulphuric acid is not 
 compofed of fulphur and oxygen, but of fulphurous acid 
 and oxygen. Phofphorus is capable of decompoiing 
 fulphuric acid by the affillance of heat, of fei/.ing a 
 quantity of its oxygen, and converting it into fulphu- 
 rous acid ; but upon fulphurous acid it has no efteft 
 * Fourcroy whatever *. The affinity of phofphorus therefore for 
 3,nA rau. oxygen is lefs than that of fulphur; yet it is capable of 
 taking oxygen from fulphuric acid. Is it not evident 
 from this, that fulphuric acid is compofed of fulphu- 
 rous acid and oxygen ? and that fulphur has a ftronger 
 affinity for oxygen than fulphurous acid has ? For if 
 both the acids were compofed direClly of fulphur and 
 oxygen, it would follow from experiment, that the affi- 
 nity of phofphorus for oxygen was both llronger and 
 .Qj weaker than that of fulphur; which would be abfurd. 
 Its Ui(ta. Sulphurous acid has been known fnice the time of 
 
 '"/• Stahl. Scheele firft difcovered the method of obtain- 
 
 ing it in quantities ; and Dr Prieltley firft procured it 
 in a ftate of purity ; for Scheele's acid was diflolved in 
 water. 
 WcthoJ cf Stahl's method of procuring fulphurous acid was to 
 procuring burn fulphur at a low temperature, and expofe to its 
 it- flames cloth dipped in a folution of potafs. By this me- 
 
 thod he obtained a combination of potafs and fulphu- 
 rous acid ; for at a low temperature fulphur forms by 
 combuftion only fulphurous acid. On this fait Scheele 
 poured a quantity cf tartarous acid, and then applied a 
 gentle heat. The fulphurous acid is in this manner dif- 
 placed, becaufe its affinity for potafs is not fo ftrong as 
 that of tartarous acid ; and it comes over into the recei- 
 ver diflolved in water. It is now commonly procured 
 by mixing with fulphuric acid oil, greafc, metals, or 
 any other fubftance that has a ftronger affinity for oxy- 
 gen than fulphurous acid, and applying a heat fufiicient 
 to diftil over the fulphurous acid as it form,;. Mr Ber- 
 thoUet has found, that fugar is the beft fubftance to 
 employ for this purpofe. 
 
 Dr Prieftley poured a little oil on fulphuric acid, ap- 
 plied heat, and received the produft in a glafs jar filled 
 with mercury. It was fulphurous acid free from all fu- 
 ^0^ perfluous water, and in a gafeous form. 
 ■Its proper- In this ftate it is colourlefs and invifible like common 
 *'"> air. It is incapable of maintaining combuftion ; nor 
 
 can animals breathe it without death. It has a ftrong 
 and fufFocating odour. It is this odour which burning 
 fulphur exhales. Its fpecific gravity, according to Berg. 
 
 CHEMISTRY. 309 
 
 man, is 0,0^246* i accordinj* to Lavoifier, o.oozyi f.Sulrhwn'Uj 
 
 Clouet and Mongc found, that by the application of ^ ^ "" ^ 
 
 extreme cold it is converted into a liquid. « ,j|i /.,/«- 
 
 Dr Prieftley difcovered, that when a ftrong heat niivc Attmc. 
 applied to this acid in ciofe veffels, a quantity ot ful- ■''"•.§- 3- 
 phur is precipitated, and tie acid is converted into ful- \_-''"""i'''3i 
 pluiric J. BerthoUet obtained the fame refult ; but , ^J„ ^,y 
 Fourcroy and Vauquelin could not fucceedj. ii. 3,fo. 
 
 Water abforbs this acid with avidity. According to 5 Nicbol- 
 Dr Prieftley, I too grains of water, at the temperature-/^" ■'7°"''" 
 54,5 ', abforb 39,6 grains of this acid. The fpecific""' ' 
 gravity of water faturated with fulj)hurousacid is t,040||. || BcrilolUt, 
 Water in the ftate of ice ahlbrbs it very rapidly, and is ^"'<- '^ 
 inftantly melted. Water faturated with this acid can ''^"''' "• 
 be frozen without parting with any of it. When wa- 
 ter, which has been faturated with this acid at the free- 
 zing temperature, is cxpoftd tt) the heat of 65,25', it is 
 filled with a vaft number of bubbles, which continually 
 increafe and rife to the furtace. Thefe bubbles are a 
 part of the acid feparating from it. It freezes a few 
 degrees below jZ^f. t Vourcny 
 
 Sulphuric acid abforbs it at zero; but allows great ^', ^''"' 
 
 V ■ r ^ Quel' 
 
 part ot It to elcape at 32 * 
 
 Ni- 
 
 - cbol forty ibiJ^ 
 
 It reddens tindure of turnfol ; but deftroys the co- * U.d. 
 lour of fyrup of violets. 
 
 It is decompofed by hydrcigen and carbon, and ful- 
 phurated hydrogen gas, when aflifted by heatf . f UiJ. 
 
 Oxygen gas gradually converts it into fulphuric acid; 
 but this' change does not take place unlefs water be 
 prefent. 
 
 It does not feem capable of oxidating any of the 
 metals except iron, zinc, and manganefc. 
 
 When in the ftate of gas it is abforbtd by oils and 
 ether. 
 
 AVhen glafs tubes, filled with fulphurous acid in the 
 ftate of ga,«, are expofed to a llrong heat, a quantity of 
 fulphur precipitates, 'and the reft ot the acid is convert- 
 ed into the fulphuric. 40^ 
 
 It combines with the alkalies, alkaline earths, andl'scombi- 
 alumina, and many of the metallic oxides, and forins ncu-"^"""'" 
 tral falts, known by the name oi fulph'iles. ^g 
 
 Its affinities, as far as they have been inveftigated. And aiEm. 
 are as follows J : ties. 
 
 Barytes, » i^'''- 
 
 Lime, 
 Potafs, 
 Soda, 
 Mag' 
 A mm 
 Alumina, 
 Jargon ia * ? 
 Metallic oxideS; 
 Water. 
 
 jnefia, l 
 imonla, J" 
 
 Chintt xxiir 
 
 aoS. 
 
 4or 
 
 S E C T. 1 1 1 . Of Nltrk Acid. 
 
 There are three different fubftances compofed of a- 
 zot and oxygen, nilrlc acid, nitrous acid, and nitrous gas. 
 The firft contains moft oxygen; the laft contains Icaft. 
 
 Nitric acid feems to have been firft obtained in a fe-oifcovery 
 parate ftate by Raymond Lully, who was born at Ma- of nitric 3- 
 jorca in 1235. He procured it by diftilling a mixtureciJ. 
 of nitre and clay. Bafil Valentine, who lived in the 
 15th century, defcribes the procefs minutely, and calls 
 the acid water of nitre. It was afterwards denomina- 
 ted
 
 310 
 
 NItr'c 
 AckI 
 
 j-iot urirg 
 it. 
 
 » Sch,eU. 
 
 4Cp 
 f^i'covery 
 "* its cora- 
 porent 
 pai ts. 
 
 » regH. 
 ii. 2S4. 
 
 ■f Pbtt. 
 
 •Tralf. 
 
 C H E M I 
 
 ted rijiia forth nnd Jpirh 0/ tiilre. The name tiilric acid 
 was fivft given it in 1787 bv the French chemiits. 
 
 Nitiic ;icid is gciicraliy obtained in large manufado- 
 ries by diililling a mixture of nitre (t) and clay ; hut 
 the acid procured by this prmefs is weaii and impure. 
 Cliiiniili cenerally prepare it by diftilhng three parts 
 of nitre and one of fulphurie ae-id in a gUfs retort. This 
 metliod was hrtl ufed by Glauber. When obtained in 
 thiv. manner .'t contains fome nitrous acid, which may 
 be exj)e!led by the application of a very gentle heat *. 
 
 Nitric acid is one of the moil important inftruments 
 of analyfis which the chemift poffefTes ; nor is it of in- 
 ferior cbnfequence when confidered in a political or com- 
 mercial view, asit foims one of the moft efTential in- 
 gredients of gunpowder. Its nature and compofition 
 accordingly have long occupied the attention of philo- 
 lophers. We faall endeavour to trace the various fteps 
 by which its component parts were difcovered. 
 
 As nitre is often produced npon the furface of the 
 earth, and never except in places which have a commu- 
 nication with atmufpheric air, it was natural to fuppofe 
 that air, or fome part of the air, entered into the com- 
 pofition of nitric acid. Mayow having obferved, that 
 nitre and atmofpherical air were both poffeiTed of the 
 property of giving a red colour to the blood, and that 
 air was deprived of this property by combuftion and 
 refpiration —concluded, that nitre contained that part of 
 the air "jihich fupported comlnjlion, and was nscejfary for 
 refpiration. 
 
 Dr Hales, by applying heat to nitric acid, and what 
 he called IValtcn mineral, obtained a quantity of air pof- 
 feiTcd of fmgi'.lar properties. V/hen atmofpherical air 
 was let into the jar which contained it, a reddiflr turbid 
 fume appeared, a quantity of air was abforbed, and the 
 remainder became tranfparent again *. Dr Prieftley 
 difcovered that this air could only be obtained from 
 nitric (u) acid; and therefore called it nitrous air. He 
 found that when this gas was mixed with oxygen gas, 
 nitrous acid was reproduced. Here, then, we find, that 
 oxygen is a part of the nitric acid, and confequently 
 that Mayow's affirmation is verified. 
 
 Dr Prieftley, however, explained this fad in a diffe- 
 rent manner. According to him, nitrous gas is com- 
 poled of nitrous acid and phlogillon. When oxygen 
 is added, it feparates this phlogiftqxi, and the acid of 
 courfe is precipitated. This hypothefis was adopted 
 \)y Macquer and Fontana ; and thefe three philofophers 
 endeavoured to fupport it with their ufual ingenuity. 
 But there was one difficulty which they were unable to 
 furmount. When the two gafes are mixed in proper 
 proportions, almofl the whole afTumes the form of ni- 
 tric acid ; and the fmall refiduum (yith part), in all 
 probability, or rather certainly, depends on fome acci- 
 dental impurity in the oxygen gas. What then be- 
 comes of the oxygen and phlogiflon ? Dr Prieftley 
 fuppofed that they formed carbonic acid gas : but Mr 
 Cavendifh proved, that when proper precautions are ta- 
 ken, no fuch acid appears \. 
 
 S T R Y. Part 11. 
 
 Dr Prieflky had proctired his tiitrous gas by difTolving Nitnc 
 metals in nitric acid ; during the iohition of which a , '^'^ "^- 
 great deal of nitrous g;is eleapes. He iuppoftd that '' 
 
 nitrous gas contained phlogillon, becaufe the metal was 
 oxidated (and co' fequently, accoidiiig to the then rc- 
 cei\ed theory, niufl have lofl phlogillon) during its for- 
 mation. Mr Lavoifier proved that this luppohtion was 
 ill-founded by the following celebrated experiment * : * ^•"'^ 
 To 94; grains of nitric acid (fpecific gravity 1,316) "^',1'^ ' 
 he added 1 104 grains of mercury. During the folution 
 273,2^4. cubic inches of nitrous gas were produced. Ho 
 then diililled the fait (oxide of mercury) which had 
 been formed to drynefs. As foon as it became red hot 
 it emitted oxygen gas, and continued to do fo till al- 
 mofl the whole of the mercury was revived: The quan- 
 tity of oxygen emitted was 287,742 cubic inches. All 
 that had happened, therefore, during the folution of the 
 mercury, was the feparation of the acid into two parts; 
 nitrous gas, which flew off, and oxygen, which united 
 with the metal (x). 
 
 Mr Lavoilier concluded, therefore, that the whole of 
 the nitrous gas was derived from the nitric acid ; that 
 nitric acid is compofed of oxygen and nitrous gas ; and 
 that the proportions are nearly 64 parts by weight of 
 nitrous gas, and 36 of oxygen gas. 
 
 But there was one difficulty which Mr Lavoifier ac- 
 knowledged he could not remove. The quantity of 
 oxygen obtained by decompofing nitric acid was often 
 much greater than what was neceffary to faturate the 
 nitrous gas. Mr De Morveau attempted to account 
 for this ; but without fuccefsf . Nitrous gas itfelf was \ Emyc. 
 evidently a compound ; but the difficulty was to difco- _.f " V.-, 
 ver the ingredients. Mr Lavoifier concluded, from an f^jt,igus. 
 experiment made by decompofing nitre by means of 
 charcoal, that it contained azot : and feveral of Dr 
 Priellley's experiments led to the fame refult. But 
 what was the other ingredient ? 
 
 Mr Cavendifh had obferved, while he was making ex- 
 periments on the compofition of water, that fome nitric 
 acid was formed during the combuflion of oxygen and 
 hydrogen gas, and that its quantity was increaled by 
 adding a little azot to the two gafes before the explo- 
 fion. Hence he concluded that the formation of the 
 acid was owing to the accidental prefence of azotic gas. 
 To verify this conjefture, he pafTed an eleftrical fhock 
 through a quantity of common air enclofed in a glafs 
 tube : the air was diminifhed, and fome nitric acid 
 formed. He repeated the experiment, by mixing toge- 
 ther oxygen and azotic gas ; and found that when they 
 bore a certain proportion to each other, they were to- 
 tally convertible into nitric acid. In one experiment, 
 the proportion of azot to oxygen (in bulk) was as 416 
 to 914 ; in another, as 1920 to 4860 J. j pm, 
 
 Thefe experiments were immediately repeated by Tranf. 
 MelTrs Van Marum and Van Trooilwyk, and with near-'/ 33' 
 ly the fame refult. 
 
 The moil convenient method of performing them is 
 the following : Take a glafs tube, the diameter of 
 
 which 
 
 (t) Nitre is compofed of nitric acid and potafs. 
 
 (u) Or nitrous acid : for at the period of Dr Prieftley's difcovery (1772) they were not accurately diflin- 
 guifhed. 
 
 (x) We have already mentioned, in a preceding note, that this experiment was firfl made by Mr Bayen. See 
 Part I. chap. iii. of this Article.
 
 Part II. 
 
 CHEMISTRY. 
 
 311 
 
 Nitric 
 Acid. 
 
 411 
 
 llsilrength 
 at different 
 fpccific gra- 
 vities. 
 
 wliicli is about the fixth part of an inch, through the 
 cork that fliuts one enil of wlu'ch let a I'mall metalh'c 
 con<luftor pafs with a ball at each end. Fill this tube 
 with mercury, and plunge its open end into a bafon of 
 mercury : then put into it a mixture of 0,13 of azotic 
 and 0,87 of oxygen gas, till it occupies three inches of 
 the tube ; and introduce a folution of potals till it fill 
 half an inch more. Then, by means of the conduftor, 
 make eleflrlcal explofions (trom a very powerful ma- 
 chine) to pafs through the tube till the air is as much 
 diminiilied as pofGble. Part of the potafs will be found 
 converted into nitre. Mr Cavendilh actually faturated 
 the potafs with this acid. Mr Van Marum did not, 
 though a good deal more gas had difappenred than in 
 the experiments of Mr Cavendifh. This difference evi- 
 dently depends on the quantity of potafs contained in 
 a given weight of the folution. The folution which 
 Mr Van Marum ufed was no doubt ftroiiger than that 
 which Mr Cavendifh employed. 
 
 Dr Prieftley had obferved, feveral years before thefe 
 experiments were made, that atmofpherical air was di- 
 iiiiiiiihed by the eleftric fpark, and that during the di- 
 minution the infufion of turnfol became red ; but he 
 concluded merely that he had precipitated the acid of 
 the air. Landriani, who thought, on the contrary, 
 that carbonic acid gas was formed, enounced the alte- 
 ration of lime-water by it as a proof of his opinion. It 
 was to refute this notion that Mr Cavendilh undertook 
 his experiments. He has fmce that time repeated them 
 with the fame luccefs *. 
 
 It cannot be doubted, then, that nitric acid is com- 
 pn'ed of azot and oxygen ; for the objeiftions of Dr 
 Prieltley have been conCdetcd while we were treating 
 of water. Confequendy nitrous gas mull alfo be com- 
 pofed of the fame ingredients. According to Lavoi. 
 fier, nitric acid is compofed of four parts, by weight, 
 of oxygen and one part of azut. 
 
 Nitric acid is liquid, colonrlefs, and tranfparent ; but 
 the affinity between its component parts is fo weak, 
 that the atlion of light is liiiHcient to drive oiT a part 
 of its oxygen in the form of gas ; and thus, by convert- 
 ing it partly into nitrous acid, to make it affume a yel- 
 low colour. Its taile is exceedingly acid and peculiar. 
 It is very corrofive, and tinges the il<in of a yellow co- 
 lour, which does not difappear till the epidermis comes 
 off. 
 
 It has a tlrong afSnity for water, and has never yet 
 been obtained except mixed with that liquid. Wheu 
 concentrated, it attracts moillure from the almofphere, 
 but not fo powerfully as fulphuric acid. It alfo pro- 
 duces heat when m.ixed with water, owing evidently to 
 the concentration of the water. 
 
 The fpecific gravity of the ftrongefl. nitric acid that 
 can be procured is, according to Rouelle, 1,583 ; but 
 at the temperature of 60'^, Mr Kirwan could not pro. 
 cure it fconger than 1,5543. 
 
 Taking this acid for the llandard, Mr Kirwan has 
 calculated how much of it exiils in nitric acid of infe- 
 rior denfity. His determination may be feen in the 
 following Table, which was formed precifely in the fame 
 manner as tliat formerly given of the itrength of ful- 
 phuric acid. 
 
 100 ]inru, 
 at the fpt- 
 
 Cont.iin 
 of Itar- 
 
 100 psrts, 
 at the f|)c- 
 
 Contain 
 of llan 
 
 too part*, 
 :t the fpc- 
 
 Contain 
 
 of llDll. 
 
 cific ^ri. 
 
 <lard uciii 
 
 lilic gra- 
 
 djfd acid 
 
 ciiic gra- 
 
 lard acid 
 
 vlty 
 
 
 vity 
 
 
 vity 
 
 
 I.5J43 
 
 100 
 
 1,4318 
 
 1° \ 
 
 1,2 q86 
 
 44 
 
 •.5^95 
 
 95 
 
 1.3975 
 
 69 
 
 1,252,- 
 
 43 
 
 1,5183 
 
 94 
 
 '^^9^5 
 
 68 
 
 1,2464 
 
 42 
 
 1,5070 
 
 93 
 
 '.3^75 
 
 67 
 
 1,2419 
 
 41 
 
 1.4957 
 
 92 
 
 1,3825 
 
 66 
 
 1.^374 
 
 40 
 
 1,4844 
 
 9> 
 
 '.3775 
 
 65 
 
 1,2291 
 
 39 
 
 1.4731 
 
 90 
 
 1,3721 
 
 64 
 
 1,2209 
 
 38 
 
 i>47'9 
 
 89 
 
 1,3671 
 
 63 
 
 1,2180 
 
 37 
 
 1.4707 
 
 88 
 
 1,3621 
 
 62 
 
 1,2152 
 
 36 
 
 1,4695 
 
 87 
 
 '.357' 
 
 61 
 
 1.2033 
 
 35 
 
 1,4683 
 
 86 
 
 •-352' 
 
 60 
 
 1,2015 
 
 34 
 
 1,4671 
 
 85 
 
 1,3468 
 
 59 
 
 1,1963 
 
 33 
 
 1,4640 
 
 84 
 
 i.34'7 
 
 58 
 
 1,1911 
 
 32 
 
 1,461 1 
 
 83 
 
 ^^ii(-'(^ 
 
 57 
 
 1.1845 
 
 31 
 
 1,4582 
 
 82 
 
 i.33'5 
 
 56 
 
 I. '779 
 
 30 
 
 i'45J3 
 
 81 
 
 1.3264 
 
 55 
 
 1.1704 
 
 29 
 
 1.4524 
 
 80 
 
 1,3212 
 
 54 
 
 1,1639 
 
 28 
 
 1.447' 
 
 19 
 
 1,3160 
 
 53 
 
 1,1581 
 
 27 
 
 1,4+22 
 
 78 
 
 1,3108 
 
 52 
 
 1,1524 
 
 26 
 
 1.4373 
 
 77 
 
 1,3056 
 
 5' 
 
 1,1421 
 
 25 
 
 i»4324 
 
 76 
 
 1,3004 
 
 5^ 
 
 1,1319 
 
 24 
 
 I;4^75 
 
 75 
 
 1,2911 
 
 49 
 
 1,1284 
 
 23 
 
 1,4222 
 
 74 
 
 1,2812 
 
 48 
 
 1,1241 
 
 22 
 
 1,4171 
 
 73 
 
 1.2795 
 
 47 
 
 1,1165 
 
 21 
 
 1,4120 
 
 72 
 
 i^iT19 
 
 46 
 
 1,1111 
 
 20 
 
 1,4069 
 
 71 
 
 1,2687 
 
 45 
 
 1,1040 
 
 19 
 
 Nitric 
 Acid 
 
 Now, how much water does nitria acid cont.iin, the 
 denfity of which is 1,5543 ? 4;^-? 
 
 Mr Kirwan dried a quantity of cryftallizeJ carbonat Qm mtity 
 of foda in a red heat, and diffblved it in water, -in fuch"' '^^.' ^"^'"^ 
 a proportion, that 367 grains of the folution contained "'''"'^' 
 50,05 of alkali. He faturated 367 grains of this folu-traicd ni- 
 tion with 147 grains of nitric acid, the fpecific gravity trie acid, . 
 of which was 1,2754, and which, therefore, by the pre. 
 ceding table, contained 45,7 per cent, of acid flandard. 
 The carbonic acid driven oil amounted to 14. grains. 
 On adding 939 grains of water, the fpecil\c gravity of 
 the folution, at the temperature of 58,5^, was 1,0401. 
 By comparing this with a folution of nitrat of foda, of' 
 the fame denfity, precifely in the manner defcribcd for. 
 merly under fulphuric acid, he fuund, that the fak con- 
 tained in it amounted to of the whole. There 
 
 16,901 
 
 was an ex'cefs of acid of about two grains. The weio-hf 
 of the whole was 1439 grains : The quantity of fait, 
 
 confequently, was — "lilL zz 85,142 grains. The quan- 
 16,901 
 
 tity of alkali was 50,05 — 14 = 36^05. The quantity 
 of ftandard acid employed was 66,7. Tire whole 
 of which amounted to 102,75 grains ; but as only 
 85,142 grains entered into the conipofition of the fait, 
 the remaining 17,608 mull have been pure water mix- 
 ed with the nitric acid. But if 66,7 of llandard acid 
 contain 17,608 of water, 100 parts of the fame acid 
 mull contain 26,38*. * Irlfa 
 
 One hundred parts of llandard nitric aciil, therefore, 7Vu/^. iv, - 
 J8 compofed of 73,62 parts of pure nitric acid and 26,38 
 of water. But as Mr Kirwan has not proved that ni- 
 tiat of foda contains no water, perhaps the proportion 
 
 of
 
 Its a<:tion 
 on other 
 bodies, 
 
 • PrmJ}, 
 Dijon Aca- 
 
 and Cer- 
 
 ntu. 
 \'TromJd(ir£^. 
 
 414 
 Its combi- 
 
 And affini- 
 
 ties. 
 
 C H E M I 
 
 of water may be greater. He lias rendered it probable, 
 however, that nitrat of foda contains very little water. 
 Nitric acid is decompofed by a great variety of fub- 
 ftances. \Vlien poured upon oils, it fets them on fire. 
 This is occafioned by a decompoiition both of the acid 
 and oil. The o;;ygen of the acid combines with the 
 carbon arid with the hydrogen of the oils, and at the 
 fame time lets go a quar.tity of caloric. Hcuce we lie 
 that the oxygen which enters into the compofitioii of 
 the nitric acid ttill contains a great deal of caloric ; a 
 fatt which is confirmed by a great number of other 
 phenomena. The combuftion of oils by this acid was 
 firft taken notice of by Borrichius and Slare ; but it is 
 probable that Homberg communicated it to Slare. In 
 order to fet fire to the fixed oils, it muft be mixed with 
 fome fulphuric acid ; the reafon of which teems to be, 
 that thefe oils contain luater, which muit be previouily 
 removed. The fulphuric acid combines with this wa- 
 ter, and allows the nitric acid, or rather the oil and ni- 
 tric acid together, to adt. The drying oils do not re- 
 quire any fulphuric acid ; they have been boiled, and 
 confequently deprived of all moifture. It fets fire alfo 
 to charcoal, provided it be perftSly dry. This fact 
 was firll obferved by Prouft, and afterwards confirmed 
 by the Dijon academicians. It fets fire alfo to zinc, 
 bifmuth, and tin, if it be poured on them in iufion, 
 and to filings of iron, if they be perfectly dry *. In 
 all thefe cafes the acid is decompofed. Sulphurated 
 hydrogen gas alfo takes fire, and burns with a ttrong 
 flame by means of this acidf . 
 
 It is capable of oxidating all the metals except gold, 
 platinum (x), and titanium. It appears, trom the ex- 
 periments of Scheffer, Bergman, Sage, and Tillet, that 
 nitric acid is capable of diifolving (and confeqvently of 
 oxidating) a very minute quantity even of gold. 
 
 Nitric acid combines with alkalies, alkaline earths, 
 alumina, and jargonia, and with the oxides of metals, 
 and forms compounds which are called iihraU. It does 
 not act upon filica nor adamanta. 
 
 The order of its affinities is as follows : 
 
 Barytes, 
 
 Potafs, 
 
 Soda, 
 
 S T R Y. 
 
 Sect. IV. Of Nitrous /teiJ, 
 
 Part ir. 
 
 t Dr Kofi. 
 
 5 Vauquelin^ 
 ^nn. de 
 Chim. xxii. 
 
 los. 
 
 Strontites \, 
 
 Lime, 
 
 Magnefia, 
 
 Ammonia, 
 
 Alumina, 
 
 J.nrgonia y ? 
 
 Metallic oxides, in the fame order 
 
 as for fulphuric acid. 
 Water. 
 
 Nitrous 
 Acid. 
 
 If oxygen gas be mixed -with nitrous gas, a quanti- " 
 ty of red fumes appear, which are readily ablorbcd by Componeat 
 water. Thefe red tumcs are nitrous acid. jians of 
 
 If a glafs veffel containing nitric acid be inverted in-"'"''"'^ »• 
 to another vetTel containing the fame acid, and expofcd" " 
 to the light, the inverted glafs will become partly full 
 of oxygen gas, and at the fame time part of the nitric 
 acid is converted into nitrous acid *. It follows, from « Schtfit 
 this experiment, that nitrous acid contains lefs oxygen Crf//'i An- 
 than nitric acid. Lavoifier has calculated, that it con-"''^ ijSa. ; 
 tains fomewhat lefs than three parts of oxygen to one 
 of azot. 4,^ 
 
 Nitrous acid is of a brown or red colour, exceeding- rts proper- 
 ly volatile, and emitting a very fuffocating and fcarcely ''". 
 toleiable odour. When to this acid, concentrated, u 
 fourth part by weight of water is added, the colour is 
 changed from red to a fine green ; and when equal 
 parts of water are added, it becomes blue +. Dr Prieil- ( Bergmar., 
 ley obferved, that water impregnated with this acid in 
 the ftate of vapour became firll blue, then green, and 
 laftly yellow. A green nitrous acid became orange- 
 coloured while hot, and retained a yellow tinge when 
 cold. A blue acid became yellow on being heated in 
 a tube hermetically fealed. An orange-coloured acid, 
 by long keeping, became green, and alterwards of a 
 deep blue ; and when expofed to air, refumed its ori- 
 ginal colour. Thefe colours feem to depend upon the 
 concentration of the acid. 
 
 Dr PrieiUev found that water abforbed great quan- 
 tities of this acid in the ftate of vapour ; and that w"i» n 
 faturated, its bulk was increafed one-third. 
 
 In the ftate of vapour, it is abforbed rapidly by 
 oils. Whale oil, by abforblng it, became green, thick, 
 and heavier It gradually decompofed the acid, re- 
 tained the oxygen, and emitted the azot in the ilate of 
 
 gas J;. _ _ i?ri,Jllej, 
 
 It is abforbed by fulphuric acid, but feemingly with-'"- '"• 
 out poducing any change ; for when water is poured 
 into the mixture, the heat produced expels it in the 
 nfual form of red fumes ^. The only fingular circum-^ u\j_ 
 fiance attending this impregnation is, that it difpofesp. 144- 
 the fulphuric acid to cr)llaUize ||. This fa^'t, firil ob-'| Uid. 
 ferved by Dr Prieft.ley in 1777 (y), was afterwards p. ij 6. 
 confirmed by Mr Cornette. 
 
 Nitrous acid appears capable of combining with moft 
 of the bodies with which nitric acid unites. The lalts 
 which it forms are called nitrites. 
 
 Its affinities have never been accurately examined. 
 Bergman fuppofes them the fame with thole of nitric 
 acid. 
 
 Of 
 
 Morveau had 
 
 (x'l Nitre, however, afts upon platinum, as Mr Tennant has proved. Phil. Tranf. 1 797. 
 made the fame obfervation in the Elemens de Chimie de V ^-icadtmie de Dijon. 
 
 (y) Bernhardt, however, relates, in 1765, that once, when he was diftilling a mixture of ten pounds of nitre 
 with an equal quantity of calcined vitriol, which he had put into a retort, to which was fitted an adapter be- 
 tween the retort and the receiver, which contained a quantity of water — he obferved a confiderable quantity of 
 a white cryftalline fait formed in the adapter, while the liquid acid pafTed as ufual into the receiver. This fait 
 was very volatile, fmoked ilrongly when it was expofed to the air, and exhaled a red vapour; it burnt, to a black 
 coal, wood, feathers, or linen, as fulphuric acid does ; and where a piece of it fell, it evaporated in form of a 
 blood red vapour, till the whole of it difappeared. Half an ounce of thefe cryftals difiblved in water with fpurt- 
 ing and hifling, like that of a red-hot iron dipped in water, and formed a green nitrous acid. Some of this fait 
 being put into a bottle, which was not well flopped, entirely vanilhed. Thefe cryftals were evidently the fame 
 with Dr Prieftley's. See Keir^s Diffiorn'ry.
 
 Part 11. 
 
 C H E M I 
 
 419 
 
 ) Ibid. p. 
 407. 
 
 Of Nilrout Gas. 
 
 Nitrous gas was firft obtained hy Dr Hales, but 
 Its properties were difcovcred by Ur PriciUey. It may 
 be pnicgred by difTolving mttals in nitric or iiitruus 
 acid, and cattliiiig the produiil by means of a pneuma- 
 tic apparatus. 
 
 As nitrous acid is formed by combining nitrous gas 
 and oxygen, it is evident that nitrous gas contains lefs 
 oxygen than nitrous acid. According to Lavoifier, it 
 is compofed of two parts of oxygen and one of azot. 
 
 Nitrous gas is elaftic, and invifible like common air. 
 Itsproi'er- It extinguilhes light, and inllantly kills all thofe ani- 
 *"*■ mals that are obliged to breathe it. Its fpccific gravi- 
 
 • On Phlo- 'y» according to Mr Kirwan, is 0,001458 *. 
 
 tiRcn, p. 28. Dr Prieftley found that water was capable of abforb- 
 ing about one-tenth of nitrous gas, and that by the ab- 
 
 ♦ PrUfiley fu'ption 't acquired an aftringent tafte f. Water parts 
 ,61;. with all the nitrous gas it has imbibed on being frozen |. 
 
 Neither phofphorus nor fulpbur leem capable of de- 
 compofing nitrous gas. 
 
 Mr Linck, profeffor at Roftoc, found, that three 
 parts of nitrous gas and two of hydrogen gas, obtained 
 by fulphuric acid and iron, are Icarcely, or not at all, 
 diminiflied when expofed to day-light over water. Com- 
 mon air Is not more dminilhed by this admixture kept 
 a long time : but the mixture itfelf of thefe two gafes 
 is diminifhed by the addition of new portions of nitrous 
 gas. Mr Linck concludes, from this obfervation, that 
 part of the oxygen of the nitrous gas combined with 
 the hydrogen and formed water, and that the remaining 
 oxygen and azot formed a mixture fimilar to the air of 
 the atmofphere. Mr Vauquelin had previoufly made 
 the fame obfervation. The affinity of hydrogen, there- 
 fore, for oxygen is greater than that of azot §. 
 
 Oils imbibe nitrous gas with avidity, and dccompofe 
 it. 
 
 Nitric acid abforbs a vaft quantity of it, and is by 
 that means converted into nitrous acid. — Sulphuric acid 
 alio abforbs It. 
 
 The moft important property of nitrous gas is that 
 of combining inllantly vvitii oxygen gas, and forming 
 nitrous acid, which is inllantly abiorbed by water. This 
 property induced Dr Prieftley to ufe nitrous gas as a 
 tcft. of the purity of common air. He mixed together 
 equal bulks of thefe fubftances, and judged of the pu- 
 rity of the air by the diminution of bulk. The appa- 
 ratus uftd for this purpofe, which confifls of a gradua- 
 ted tube, has been called a eudiometer. This eudiome- 
 ter has been greatly improved by Fontana, but it is llill 
 liable to uncertainty in its application. Perhaps the 
 bell eudiometer is fulphuret of potafs, which, as Mor- 
 veau has dlfcovercd, ablorbs, on the application of heat, 
 the whole oxygen in a given bulk of air almoft inftan- 
 taneoufly. 
 
 Dr Prieftley found that nitrous gas was decompofed 
 by paffing eleftric explofions through It. 
 
 Let us now confider In what manner oxygen and 
 azot are combined in the three fubftances which have 
 been juft defcrlbed. 
 Manner ia It can hardly be conceived that azot is capable of 
 which azot combining with three'different proportions of oxygen, 
 and oxygen jj,)(} ^f being faturated with each: it Is furely much 
 ,yj '' more probable, that in nitrous gas the oxygen and azot 
 faturate each other dlredtly and completely ; that ni- 
 trous acid is compofed of nitrous gas and oxygen, and 
 
 SuppL.VoL, L FartL 
 
 f NIchol 
 fans 'Jtiur, 
 a. ■)%. 
 
 410 
 The eudio- 
 
 STRY. 3T3 
 
 nitric acid of nitrous add and oxygen. And tMs fup- Muriatic 
 pofition is confirmed by confidering th.it ilie ftrength ''^"^- , 
 of affinity by which tlie oxygen is retained in each of """"^ 
 thefe fubftances is very different. Sorrlc lubftances, as 
 light, are capable of decompoling nitric acid, by fe'zing 
 fome ot its oxygen, and of converting it into nitrous 
 acid ; but they have no effcdl whatever upon nitnnis 
 acid or nitrons fjas. Others, as bifniuth, copper, jihof. 
 phorus, and fulphur, are capable of decompoling both 
 nitric and nitrous acids, but are incapable of altering 
 nitrous gas : And others, again, as carbon, zinc, and 
 Iron, are capable of (lecompoling all the three. Every 
 body which is capable^ of dccompofing nitrous add is 
 capable alfo of dccompofing nitric acid ; and every body 
 that decomjxjfes nitrous gas is capable alfo of dccom- 
 pofing the other two. But the reverfe of this is not 
 true. The affinity of oxygen, tiien, for azot, nitrous 
 gas, and nitrous add, Is different : oxygen has a ftronger 
 affinity for azot than it has for nitrous gas, and a 
 ftronger affinity for nitrous gas than for nitrous add. 
 But if all thefe bodies were dircft combinations of azot 
 and oxygen, how could this difference of affinity take 
 place ? Is it reafonable to fuppofe that a fubftance has 
 a ftronger affinity for one proportion of any other body 
 than for another proportion? or that, if fuch a difference 
 exifted, the ftrongeft affinity (hould not always prevail? 
 Mix together nitric add and nitrous gas in proper pro- 
 portions, and the whole mixture is converted into ni- 
 trous acid : but mix nitrous and nitric adds together, 
 and no change whatever is produced. In the firil cafe. 
 Is It not evident that the affinity of nitrous gas for oxy- 
 gen is greater than that of nitrous acid ; that therefore 
 It decompofes the nitric acid, deprives it of oxygen, 
 and leaves It in the ftate of nitrous acid? But, in the 
 fecond cafe, no change can take place, becaufc nitric 
 acid is compofed of nitrous acid and oxygen ; and it 
 would be abfurd to fuppofe, that nitrous acid has a 
 ftronger affinity for oxygen than nitrous acid lias. But 
 were azot and oxygen capable of uniting In various 
 proportions, why lliould not a mixture of nitric and ni- 
 trous acids, or of nitrous gas and nitrous acid, form new 
 fubftances ? And why are the only fubftances which 
 appear in decompofitions nitrous acid and nitrous gas ? 
 Surely thefe reafons are fufficient to fhew us, that thefe 
 bodies are combined In the following manner ; 
 
 Azot and 1 ^ 
 
 0> torm nitrous cas ; 
 xygen y ° ' 
 
 Nitrous eas \ c ■ • . 
 
 , J ° > form nitrous acid ; 
 and oxygen \ ' 
 
 Nitrous add 1 c ■ ■ ■ , 
 
 _ I J- form nitnc acid, 
 
 and oxygen J 
 
 Perhaps there may be even more links in the chain 
 than we are aware of. The dephlogifticated nitrous air 
 of Dr Prieftley, which Dieman and Van Trooftwyck 
 have lately proved to be compofed of 37 parts of oxy- 
 gen and 6j of azot, and of which little more is known 
 than that It fupports flame. Is noxious to animals, ab- 
 forbed by water, and only obtained by means of fub- 
 ftances capable of dccompofing nitrous gas — perhaps 
 this air is compofed direttly of oxygen and azot, ni- 
 trous gas of this air and oxygen, and fo on. There 
 may be even links ilill farther back than that. 
 
 Sect. V. 0/ Muriatic JcU. 
 
 •lit 
 
 Muriatic acid appears to have been known to Bafil Difcovtry 
 Valentine ; but Glauber was the fiift who extrafted it"f marutic 
 
 from 
 
 acid.
 
 314 CHEMISTRY. , Part If 
 
 Muriatic from common fait by means of fulphuric acid. Com- is always called by that name) is generally of a pale Ox)- muria 
 
 . ''^ , mon fait is compofed of muriatic acid and fuda, for yellow colour, owing, ae Dr Pricflley fuppofed, to fome '"^ '^"J- 
 
 which lad fubftance fulphuric acid has a ilronger afiini> earthy matter difl'olved in it ; but much more probably """"v— 
 
 ty. This acid «as firil called^wV// of fall, afterwards to its having abforbed a quantity cf oxygen, for which 
 
 • From ««-»""■'"« ocitl, and now, pretty generally, mur'nuic acid*, it has a Ibong affinity. Indeed, that tliij is the caufe 
 
 ria. It is fonietimes prepared by mixing one part of com- ap])ears evidently from Dr Prieftley 's own obftrvations ; 
 
 mon fait with feven or eight prrts of clay, and diftilling for it was deftroyed only by thofc bodies which had a 
 
 the mixture. The clay, in this inilance, is fuppofcd to Ilronger affinity for oxygen. It is very volatile, as 
 
 acl chiefly by means of the fulphuric acid which it al- might be expefted, conitantly emitting white fumes of 
 
 ways contains (z) : But this fubjeft ftill requires far- a peculiar and unpleafant odour. 
 
 ther elucidation. By thefe pioccITes, muriatic acid is Muriatic acid is capable, by the affiftance of heat, oflsa(aion 
 
 obtained diffolved in water. Dr Prieftley dilcovered, oxidating the following metals : Iron, tin, lead, zinc, °" "'her 
 
 that by applying heat to this folution, and receiving the bifmuth, cobalt, nickel, manganefe, antimony, arfenic. "' 
 
 product in veffels filled with mercury, a gas was procu- Several of thclc, as iron, for inftance, it oxidates even 
 
 4>3 
 
 Its proper 
 ties. 
 
 red ; which gas is muriatic acid in a ilate of purity. 
 
 Muriatic acid gas is invifible and elalllc, like com- 
 mon air. It deitroys life and cxtinguiflics flame. A 
 candle, juft befoie it goes out in it, burns with a beau- 
 tiful'green, or rather light bine flame ; and the fame 
 
 ^ Pritfiliy, flame appears when it is fuil lighted again +. 
 
 "•»93- - - 
 
 Tranf, iv. 
 
 without the afliftance of heat. 
 
 At a boiling heat, it oxidates filver and copper. It 
 has no atlion on gold, platinum, mercury, tungften, 
 molybdenum, tellurium, titanium. Its atlion on ura- 
 nium has not been tried. 
 
 In the Hate of gas, it appears to decompofe alcohol 
 
 The fpecific gravity of muriatic acid in the Rate of and oils by its afiinity for water 
 
 * PrunU' 
 
 gas is, according to Mr Kirwan \, 0,0023x5, which is 
 nearly double that of common air. 
 
 Water abforbs this gas with avidity. Ten grains of 
 water are capable of ablorbing ten grains of the gas. 
 The folution thus obtained occupies the fpace of 13,3 
 grains of water nearly. Hence its fpecific gravity is 
 
 It 
 
 'i<"}f 
 
 IS capable of diffolvintr a little fulphat and fluat + " ^''' „ 
 c V jr-.r + see feet, 
 
 01 lime, and arleniat 01 mercury. ■ 
 
 It combines with the alkalies, alkaline earths, alumi- 
 na, and jargonia, and with moft of the metallic oxides, 
 and forius neutral falts, known by the name olmurlats. 416 
 
 Morveau hrft fhewed, that this acid, in the Hate of Deflroys 
 
 i,;oo, and the denfity of the pure muriatic acid in it gas, neutralized putrid miafmata, and by that means 1'"'"'' '"'* 
 
 7r§'T«">.'M'°3HA)- deftroyed their bad eft'eds. In 1 773, the cathedral of """^'*- 
 
 vol. iv. '* As muriatic acid can only be ufed conveniently when Dijon was fo infefted by putrid exhalations, that it was 
 
 diflblved in water, it is of much confequence to know deferted, after feveral unfuccefsful attempts to purify it. 
 
 how much pure acid is contained in a given quantity of Application was made to Mr Morveau to fee whether 
 
 424 liquid muriatic acid of any particular denfity. he knew any method of deftroying thefe exhalations. 
 
 Quantity nf J^qw the fpecific gravity of the pureft muriatic acid He poured two pounds of fulphuric acid on i\ii. pounds 
 
 It contained jj^^^ can eafily be procured and preferved, is 1,196 ; it of common fait, contained in a glafs capiule, which had 
 
 various would be needlefs, therefore, to examine the purity ot been placed on a few live coals in the middle of the 
 
 denfitits. any muriatic acid of fuperior denfity. Mr Kirwan cal- church. He withdrew precipitately, and fliut all the 
 
 culated that muriatic acid, of the denfity 1,196, con- doors. The muriatic acid gas foon filled the whole ca- 
 
 tains rVo pai'ts of acid of the denfity 1,500, which he thedral, and could even be perceived at the door. After 
 
 took for the ftandard ; then, by means of experiments, 1 2 hours, the doors were thrown open, and a current of 
 
 he formed the following Table : air made to pafs through to remove the gas. This de- 
 
 too parts, 
 at the fpe- 
 cific i;ra- 
 viiy 
 
 1,196 
 
 Contain 
 of ftan. 
 lard acid 
 
 103 parts, 
 at the fpe- 
 cific gra- 
 vity 
 
 Contain 
 of llan- 
 c'ard acid 
 
 100 parts, 
 a* the Tpe- 
 cific gra- 
 vity 
 
 Contain 
 of Han- 
 dard acid 
 
 49 
 
 1. 147 
 
 37 
 
 1,1036 
 
 26 
 
 1,191 
 
 48 
 
 1,1414 
 
 36 
 
 1,0984 
 
 25 
 
 1,187 
 
 47 
 
 1,1396 
 
 35 
 
 1,0942 
 
 24 
 
 1,183 
 
 46 
 
 1,1358 
 
 34 
 
 1,0910 
 
 23 
 
 I. "79 
 
 45 
 
 1,1320 
 
 33 
 
 1,0868 
 
 22 
 
 i>i7S 
 
 4+ 
 
 1,1282 
 
 32 
 
 1,0826 
 
 21 
 
 1,171 
 
 43 
 
 1. 1244 
 
 31 
 
 1,0784 
 
 20 
 
 1,167 
 
 42 
 
 1,1206 
 
 30 
 
 1,0742 
 
 19 
 
 I, "63 
 
 41 
 
 i,ti68 
 
 29 
 
 1,0630 
 
 16 
 
 1,159 
 
 4^ 
 
 1,1120 
 
 28 
 
 J, 0345 
 
 10 
 
 i-'JS 
 
 39 
 
 1,1078 
 
 27 
 
 1,0169 
 
 5 
 
 i.iyi 
 
 ?« 
 
 
 1 
 
 
 
 ftroyed completely every putrid odour -j- 
 The affinities of muriatic acid are as follow 
 Barytes, 
 Potafs, 
 Soda, 
 
 Strontites f , 
 Lime, 
 Magncfia, 
 Ammonia, 
 Alumina, 
 Jargonia II, _ 
 Metallic oxides as in fulphuric acid, ■^''"' ' .. 
 
 --, '^ Chim. Xill. 
 
 \V ater 
 
 I Jour, de 
 
 427 
 ItsaSnitiei, 
 
 5 Drliofe. 
 
 Vaiiqiiclinf 
 
 »0S. 
 
 Sect. VI. Of Oxy-murlattc Acid. 
 
 41S 
 
 Put into a glafs retort one part of the black oxide Difcovery 
 
 of manganefe and three parts of muriatic acid ; place ^"4 P'*?*' 
 ■ • r . , 1 ■ r 1 I 11- 1 • 1 ration 01 
 
 it in a fand-bath in Inch a manner that the liquor which (,jy.„uf;i. 
 
 Muriatic acid (for this folution of the acid in water rifes up into the neck of the retort may fall back again tic acid. 
 
 into 
 
 (z) Morveau has (hewn, that even alumina contains fulphuric acid, provided a precipitation, on adding mu- 
 riat of barytes, be a fufficient left. 
 
 (a) For let D =: the denfity of a mixture; m the weight of the denfer ingredient; iits denfity; /the weight of 
 
 an
 
 Part II. 
 
 CHEMISTRY. 
 
 419 
 
 !ts compo 
 Ccion. 
 
 Oxy-muri- into tKc vtfTcl ; and npply a fmall receiver, with a little 
 atic AciJ. ^yater in it, luted to the retort merely by a fillet of 
 *"""*'""" brown paper. In about a quarter of an hour the re- 
 ceiver will appear filled with a yellow-coloured gas; it 
 is then to be removed, and others applied fucceilively 
 till the operation be fini(hed. 
 
 This gas is oxy-murlatic acid, firll difcovcred by 
 Scheele, while he was making experiments on manga- 
 nefe, and called by him dephlogijVicUed muriatic acid, be- 
 canfe he thought it muriatic acid deprived of phlo- 
 gifton. The French chemitls called it osygenala! muri- 
 atic acid, which l)r Pcarfon contrafted into oxy-miiria- 
 tic acid ; and this lall name we have adopted, becaufe it 
 is fhorter and equally dlilincl. 
 
 The true theory of the formation and compofition 
 of this acid, wllich was firll given by Berthollet, will 
 appear from the following facts : The black oxide of 
 manganefe is, during the proeefs, converted into tuhite 
 oxide, and mull therefore have given out a quantity of 
 oxygen. When oxy-muriatic acid dilTolved in water is 
 prefented to the ligiit in a vefiel half empty, oxygen 
 gas is difengaged and floats above, and the acid is con- 
 verted into common muriatic acid : Confequently oxy- 
 muriatic acid is compofed of muriatic acid and oxygen. 
 Black oxide of manganefe is compofed of white oxide 
 and oxygen ; muriatic acid has a llronger affinity for 
 oxygen than the white oxide ; during the dillillation 
 the black oxide is decompofed, the oxygen combines 
 with muriatic acid, and the produdl is oxy-muriatic 
 acid gas. 
 
 Oxy-muriatic acid gas is of a yellow colour. It fup- 
 ports flame, but cannot be breathed without proving 
 noxious. The death of the ingenious and induHrious 
 Pelletier, to whom we have fo often referred, was occa- 
 fioned by his attempting to relplre it. A confumption 
 was the confequence of this attempt, which, in a fliort 
 time, proved fatal. 
 
 It does not luute readily with water. Scheele found, 
 that after Handing ! 2 hours over water, iths of the gas 
 were abforbed : the remainder was common air, which 
 no doubt had been contained in the velfel before the 
 operation. Berthollet furrounded feveral bottles con- 
 taining it with ice : as loon as the water in thefe bottles 
 was faturated, the gas became concrete, and funk to 
 the bottom of the veffcls ; but the fmalleft heat made it 
 rife in bubbles, and endeavour to efcape in the form of 
 • J^urn. * gas*. Wellrum obferved that it became folid when 
 + "y '' J expofed in large veffcls to the temperature of 40°; and 
 fMjti'i:, ^''*t t'l'^" ■'^ exhibited a kind of cryllallization ■]-. The 
 xsxvii. 3Si.fpecific gravity of water faturated with this gas, at the 
 
 430 
 Its prop;-- 
 ties 
 
 • Morveau^ 
 
 5«5 
 
 temperature of 43'', 18 1,0:3 *• Water impregnated Oiy-mnri. 
 with it has not an acid, but an auftcre tafte f , unlike .°"^ - • '■c'd-^ 
 that of other acids. « » ,111. 
 
 T , 111 I • , , Btrtbollet, 
 
 U renders vegetable colours tobite, and not red, as jaurn. de 
 other acids do; and the colour thus dellroyed can '"^.-.y- ' ?85. 
 neither be rellored by acids nor alkalies. It has the t •^^*"''' 
 fame tffefts on yellow wax. If the quantity of vegetable 
 colours to which it is applied be fuffic'ently great, it is 
 found reduced to the Rate of common muriatic acid. 
 Hence it is evident, that it dellroys thefe tol.iurs by 
 communicating oxygen. This property has rendered 
 oxy-muriatic acid a very important auicle m bleaching. 
 
 Nitrous gas, hydrogen, fulphur, luiphurous acid, and 
 phofphorus, deeompole this acid, by depriving it of its 
 oxygen, and leaving the muriatic acid in a ieparate (late. 
 Phofphorus, however, does not produce this efTeft fo 
 readily, except when aflrilled by heat*. 
 
 When muriatic acid is mixed with nitric acid, the f""c." 
 compound has precifely the fmell and the qualities of Wfjoi/. 
 oxy-muriatic. It can fcarcely be doubted, therefore, •'""""i'' 
 that as far as it a6ls as an acid, different from the mu-*^'" 
 riatic and the nitric, it is nothing elfe but oxy-muriatic Nitro-nMu 
 acid, riatic acidi 
 
 This mixture of the two acids was formerly called 
 aqua regia ; but at prefent it is called by the French 
 chemifts nilro-tnurialic acid. It is firll mentioned by 
 Ifaac the Hollander, and feems to have been known be- 
 fore the muriatic acid itfelf. It was prepared by pour- 
 ing nitric acid on common fait. The nitric acid de- 
 compofes the fait, and part of it unites with the muri- 
 atic acid thus fet at liberty- a-i% 
 
 Oxy-muriatic acid oxidates all the metals (except, Its aiSiin 
 perhaps^ titanium) without the affillance of heat. "" 9'''=r 
 
 It decompofen red fulphuret of mercury, or cinnabar, ''"^^^ 
 which neither fulphuric nor nitric acid is able to ac- 
 
 complifh § , , r ■ . § B'rf«."». 
 
 All the fubflances placed before muriatic acid In the 
 table of the affinities ot oxygen, are capable of decompo- 
 fingthis acid. Many of them, when plunged into it while 
 in the flate of gas, aftually take fire. Wellrum obfer- 
 ved, for inflance, that when pieces of wood were plun- 
 ged into this gas, they took fire ; that arfenic burned 
 with a blue and green flame ; bifmuth, with a lively 
 bluifli flame ; nickel, with a whire flame, bordering dn 
 yellow ; cobalt, with a white flame, approaching to 
 blues ziuc, with a lively white flame ; tin, with a feeble 
 bluifli flame ; lead, with a fparkling white flame ; cop- 
 per and iron, with a red flame : that powdered char- 
 coal took fire in it at the temperature of 9-0", and that 
 ammonia produced with it a loud detonation |{. || jcurn.dt 
 
 R r 2 With Pl'iffi^-'c, 
 
 xxxvii. 3S51 
 
 m -^m' 
 
 an equal billk of Vsfater; and m', d', and /', the fame elements of the rarer : Then D = . . In the above 
 
 cafe, m-<-m' = 20, and / -f / = 13,3. Then D = = 1,5, Now to find the fpecific gravity of the 
 
 condenfed muriatic acid gas, we have from the above equation / = tt := — ~ = 3,3 j and d =: 
 
 m 10 
 -j-^ =: 3«P3' ^'^ I''lft> TranfaSioni, vol. iv. 
 
 This calculation, however, is formed upon the fuppofition that the water fuflfers no condenfation at all a 
 
 fuppofition certainly contradifted by every analogy, and which, as Mr Keirhas Ihewn, the experiments mentioned 
 in Mr Kirwan's firft paper are tnfuMcient to prove.
 
 3i6 > CHEMISTRY. Part IL 
 
 Oxy-muri- With alkalie'!, earths, and metallic oxides, it is ca- out of the bottle ; they were ftrongly inflammable, and Pliof^Iiorle. 
 atic Acid, p^y^. ^,f combining and forming neutral falls, which probably, therefore, pure hydrogen gas. The liquor, 
 ' have been called oxy-i)hiriats. 
 
 Acid. 
 -V" 
 
 Its 
 
 • Vauqiie' 
 fin, Ann di 
 Chtm. xxii. 
 
 ac8. 
 
 ffiuitiei. The affinities of this acid, according to Lavoifier, 
 are as follows : 
 
 Alumina, 
 Jargonia * ? 
 Ammonia, 
 Oxide of antimony, 
 
 fdver, 
 
 arfenic, 
 
 Barytes, 
 Strontites ? 
 Oxide of bifmuth, 
 Lime, 
 
 Oxide of cobalt, 
 
 ■ copper, 
 
 ■ ■ tin, 
 
 iron, 
 
 Magnefia (b). 
 Oxide of nianganefe, 
 
 — -^ — mercury, 
 
 molybdenum, 
 
 nickel, 
 
 gold, 
 
 — platinum, 
 
 lead, 
 
 Potafs, 
 
 Soda, 
 
 Oxide of tungften, 
 
 zinc (c). 
 
 Of*Wom- The component parts of muriatic acid are ftill ira- 
 perfeftly known. Dr Girtanner pretended, about the 
 year i 790, that he had decompofed it ; and that it con 
 
 gradually loll its odour of iulphurated hydrogen gas, 
 and after iome days ImtUcd very much like ftagnant 
 rain-water. As the bubbles ceaied to be produced, it 
 recovered its tranfparency. On evaporating a fmall 
 quantity of this iolution in a watch-glafs to drynefs, a 
 bitter deliquefcent fait was left behind. On this fait 
 a little fulphuric acid was dropped, and paper moiften- 
 ed with ammonia was held over the glafs ; white va- 
 pours were immediately formed over the glafs ; and 
 confequently fonie volatile acid was feparated by the 
 fulphuric acid. Mr Lambe evaporated about eight 
 ounce meafnres of the lame liquor, and, as before, drop- 
 ped a little fulphuric acid on the reiiduum ; a ftrong 
 effervefcence was excited, very pungent acid fumes arofe, 
 which, from their fmell, were readily known to be mu- 
 riatic. The fame truth was eftabliflied beyond a doubt, 
 by holding a bit of paper moillened with water, which 
 made the vapours vifible in the form of a grey fmoke ; 
 a diftinguifliing charafteriftic, as Bergman has obferved, 
 of the muriatic acid. — When manganefe and mercury 
 were difTolved in fulphurated hydrogen gas, the falts 
 formed gave the fame unequivocal marks of the pre- 
 fence of muriatic acid *. * tamht, 
 
 Shall we conclude from thefe fafts, that the bafis of'^'''- 
 muriatic acid is fulphurated hydrogen ; that muriatic 
 acid is fulphurated hydrogen combined with oxygen ; 
 that this combination takes place during the folution 
 of the iron ; and that the efcape of hydrogen is owing 
 to the decompofition of the water ? 
 
 fonent 
 
 y>a '5 of 
 muriatic 
 acid. 
 
 Sect. VII. Phofphoric Add. 
 
 435 
 
 Phosphorus is capable of forming combinations'-'"'^'''''^ 
 
 lifted of hydrogen combined with a greater proportion with two different quantities of oxygen ; with the larger"^ ^ o p e- 
 
 of oxygen than enters into the compofition of water, it forms phofphoric ; and with the Imaller phofphorous 
 
 He pafled eleftrical explofions through muriatic acid, acid. 
 
 and obtained a quantity of oxygen and hydrogen gas. Phofphoric acid was unknown till after the difcovery 
 
 But a repetition of thefe experiments (hewed, that the of phofphorus. Boyle is perhaps the firft perfon who 
 
 gafes were owing, not to the decompofition of the acid, mentions it : he difcovered it by allowing phofphorus 
 
 but to that of the water with which the acid was com- to burn flowly in common air. But Margraf was the 
 
 bined. firft perfon who examined its properties, and difcovered 
 
 The experiments of Mr Lambe (d) have lately opened it to be a peculiar acid, 
 a new and unexpedled path, which feems to lead direft- It may be procured by expofmg phofphorus to a mo- 
 
 ly to the difcovery of the component parts of this acid, derate heat : the phofphorus takes lire, combines with 
 
 He found, that when iron was acted upon by fulphu- oxygen, and is converted into an acid. ^36 
 
 rated hydrogen gas, a fubftance was produced which It may alfo be prepared by expofing phofphorus Method of 
 
 poffefied all the properties of oxy-muriat of iron (oxy- during fome weeks to the ordinary temperature of the pi'«P*'"'6 '' 
 
 muriatic acid combined with iron). The fulphurated atmofphere, even in winter; when the phofphorus un- 
 
 hydrof en gas which he ufed was obtained from fulpliuret dergoes a flow combuftion, and is gradually changed in- 
 
 of iron, formed by fufing equal parts of iron and flowers to a liquid acid. For this /purpofe, it is ufual to put 
 
 of fulphur ; and it was extricated by diluted fulphuric fmall pieces of phofphorus on the inclined fide of a glafs 
 
 acid. In a folution of this gas in diftilled water, he di- funnel, through which the liquor which is formed drops 
 
 jrefted iron filings, previoully purified by repeated wafh- into the bottle placed to receive it. From one ounce 
 
 ings with dillilled water. The bottle was filled with of phofphorus about three ounces of acid liquor may be 
 
 the folution, and corked. The iron was prefently aifed thus prepared, called phofphoric acid by deliquefcence. 
 upon ; numerous bubbles arofe, which drove the cork Scheele has contrived another mode of obtaining the 
 
 pliofphoric 
 
 (b) According to Trommfdorf, oxy-niuriatic acid is incapable of combining with magnefia. Ann. de Chim. 
 xxii. 2 1 8. 
 
 ' (c) This is the order of the affinities of nitro-muriatic acid. Many fafts (fome of which Ihall appear after- 
 wards.) concur to prove that the affinities of the oxy-muriaiic acid are the fame, and indeed that they are the 
 fame acids. 
 
 (d) Analyfis of the waters of two mineral fprings at Leminton Priors. Manchejler Memoin, vol. V. fart I ft. 
 
 1
 
 Part ir. 
 
 CHEMISTRY. 
 
 Phofphoric phofphoric add from phofphonis witliout combuftion, 
 
 , ■'^'■ '^- by the mere adioii of the nitric acid on phofphonis*. 
 
 • On Vire ^'" Lavoifier has repeated and dcfcribed tliis procels-f-. 
 § Ixxvii. He put two pounds of nitric acid, the fpecific gravity 
 ^ Mem. A. of which was 1,2989?, into a retort, the contents of 
 tmi. i-jho. ^yluYli were equal to fix or feven French pints, and to 
 whicii a balloon was fitted. Having placed this retort in 
 a fand-bath, and brought the heat of the acid contained 
 in it to 133 J deg he added fucccffively fmall quantities 
 of phofphorus, about 10 or 12 grains at a time, until 
 he had diffolved 2;^ oz. At iiril the tfFervefcence was 
 great, but at laft he was obliged to apply heat to effeiSl 
 the folution. The operation Lifted 17 or 18 hours. A 
 good deal of nitrous acid had paflTed into the receiver. 
 He then poured the contents of the retort into a fmaller 
 retort, and evaporated by means of a llronger heat, un- 
 til the phofphoric acid began to diftil in white vapours. 
 The remaining acid was fo thick that he could not pour 
 it out of the retort, and therefore could not afcertaiii 
 its quantity ; but he fuppofes it might be 8 or 9 oun- 
 ces, in wliich he thinks there were about 2\ oun- 
 ces of phofphorus ; the remaining ^ ounce being fup- 
 pofed to have evaporated. The quantity of oxygen 
 imbibed he reckons at 34^ ounces, and the quantity of 
 water at about 2 ounces. 
 
 Lavoifier computes that phofphoric acid contains ico 
 437 parts of phofphorus and 154 of oxygen. 
 Its proj-er- The colour of this acid is white; it has no fmell, has 
 '*'■ an acid talle ; but is not corrofive (e). 
 
 It is exceedingly fixed. When expofed to the fire in 
 a matrafs with a long neck, it lofcs at firft the greater 
 part of its water ; then an odour of garlic is felt, ow- 
 ing to lome phofphorus, from which it is exceedingly 
 difficult to clear it entirely ; there is likewife a fmall 
 quantity of the acid volatilized along with the water. 
 The liquor then becomes thick and milky: fmall lumi- 
 nous decrepitations take place from time to time, and 
 they continue for fome time after the veflc:l is taken 
 from the fire. If the matter be then put into a cru- 
 cible, and placed among burning coals, it firft boils vio- 
 lently, and gives out a vapour which tinges flame green, 
 and is at lall converted to a v,'hite tranfparent glafs, in- 
 foluble in water. 
 
 The fpecific gravity of this acid in a ftate of dry- 
 \ 'Birgmnn. nefs is 2,687 J, that, of phofphoric acid by deliquef- 
 J Monctiu, cence 1,417 J. It is capable of cryftallizing ; its cry- 
 ftals are quadrangular prilms terminated by quadrangu- 
 lar pyramids. 
 
 Phofphoric acid obtained bv deliquefcence, when mix- 
 ed with an equal quantity of diftilled water, acquired fo 
 little ieat as to raife the thermometer only one degree, 
 as Mr Sage obferved. 
 
 Mr Lavoifier raifed Reaumur's thermometer from S" 
 to 14° or 15*^ by mixing phofphoric acid boiled to the 
 confiftence of a fyrup, with an equal quantity of water ; 
 and from 8'^ to 32° or 33° when the acid was as thick 
 as turpentine 1). 
 
 Phofphoric acid is capable of oxidating iron, tin, 
 lead, zinc, antimony, bifmuch, manganefe. When fu- 
 fed with feveral of thefe metals, as tin, lead, iron, and 
 zinc, it is converted into phofphorus; a proof that they 
 have a ft.ronger af&nity for oxygen. 
 
 3n 
 
 [I Keir's 
 Uiiiiotrary 
 
 45 S 
 ts at'-tioii 
 in other 
 iod:es. 
 
 439 
 Its affini- 
 ties. 
 
 It does not adt tipon gold, platinum, filvcr, copper, Boracic 
 mercury, arfenic, cobalt, nickel. It appears, however, , ^'^"'- _ 
 to have fome aiSlion on gold in the Jry -way, as it is ' 
 
 called; tor when fufed with gold-leaf it affumes a purple 
 colour; a proof that the gold has been oxidated. 
 
 It is capable of combining with alkalies, alkaline 
 earths, alumina, and metallic oxides; and of forming 
 falls known by the name ol phofj>hats. 
 
 Phofphoric acid, by the aflillaiice of heat, is capable 
 of decoinpofing glafs. 
 
 Its affinities are as follows : 
 Lime, 
 Barytes, 
 
 Ktrontites*, « jy„^,_ 
 
 Magnefia, Tranf.E- 
 
 Potafs, dii.ii. 
 
 Soda, 
 Ammonia, 
 Alumina, 
 
 Jargoniaf, \ Vauqur- 
 
 Metallic oxides as in fulphuric acid, ''". ■^'"'- "/' 
 Water. '-^■^"'- ''^"• 
 
 The Phosphorous Acid is formed when phofpho- .' 
 rus is expofed to a flow fpontancous combuftion at the Pt ofpho- 
 temperature of the atmofphere; but it gradually abforbs rous acid. 
 more oxygen, and is converted into phofphoric acid. 
 
 Concerning phofphorous acid nothing of any confe- 
 queiice is at prelent known, except that it contains Icfs 
 oxygen than phofphoric acid. 
 
 Sect. VIII. Boracic Aciil. 
 
 441 
 The word borax fiift occurs in the works of Geber, Bor.i. 
 
 an Arabian chcmift of the loth century. It is a name 
 given to a fpecies of white fait inuch ufed by various 
 artifts. Its ufe in foldcring metals appears to have been 
 known to Agricola. 
 
 Borax Is found mixed with other fubftances in Tiil- 
 bet. It feems to exift in fome lands adjacent to Likes, 
 from which it is extrafted by water, and depolited hi 
 thofe lakes; whence in fummer, when the water is fhal- 
 low, it is extrafled and carried ofl'in large lumps. Some- 
 times the water in theielakes is admitted Into refervoirs, 
 at the bottom of which, when the water is exhaled by 
 the fummer's heat, this fait is found. — Hence it is car- 
 ried to the Eaft Indies, where It Is in fome meafiire pu- 
 rified and cryftallized: in this ftcite it comes to Europe, 
 and Is called tinea!. In other parts ot Thibet, it feems, 
 by accounts received from China, they dig it out of th<; 
 ground at the depth of about two' yards, where they 
 find It in fmall cryftalline maffes, called by the Cliinefe 
 mi pc/uii, houi poun, sndpinpoun; and the earth or ore 
 IS Cidltd poijnxij i, i Kirvau\ 
 
 Though borax has been in common ufe for nearly .'}-'^""'''''"%J'> 
 three centuries, it was only in 1702 that Homberg, by""^'" 
 diftilling a mixture of borax and green vitriol, difcovered nilcovery 
 the boracic acid. He called it narcotic or fedative fait, nf tioracic 
 from a notion of his, that it poifeifed the properties in-^'^'''' 
 dicated by thefe names In his opinion, it was merely 
 a produft of the vitriol which he had ufed ; but Le- 
 mtry the Younger foon after difcovered, that it could 
 likewife be obtained from borax by means of the nitric 
 and muriatic acids. Geoffroi afterwards difcovered, 
 
 that 
 
 (e) We have obferved, however, that when very much concentrated it deitroyed the texture of vegetable fub- 
 ftances, paper for inflance, very completely.
 
 Acid. 
 
 44.1 
 Attempts 
 
 318 ^ C H E M I 
 
 Boracic that borax ContEineJ foda : and at laft Baron proved, 
 
 by a number of experiments, that borax was compofed 
 
 of boracic acid and foda ; that it mi^jht be reproduced 
 
 by combining thefe two fubftanccs — and that therefore 
 
 the boracic acid was not formed during the deconipofi- 
 
 tion of borax, as furiner chemitts had imagined, but was 
 
 a pecuh'ar fubllance which pre-exiited in that fait. 
 
 This conclufion has been called in queftion by Mr Ca- 
 
 to prnve det * ^vho affirmed that it was compofed of foda, the 
 that It does . . ' , , , . , , '^ / J 
 
 not exill in "vitnfiable tartb oj copper, another unknotvn metal, and mu- 
 
 borax ; riatie acid. But this aflcrtion has never been confirmed 
 • Jixtrn-de Jjy 3 fingle proof; Mr Cadet has only proved that bo- 
 -V' '7*^' racic acid fometimes contains copper; and Beanme's 
 experiments are fufficient to convince us that tins metal 
 is merely accidentally prefent, and that it is probably 
 derived from the veflels employed in cryftallizing borax: 
 That boracic acid generally contains a little of the acid 
 employed to feparate it from the foda, with which it 
 is combined in borax : And that crude borax contains 
 a quantity of earth imperfectly faturated with boracic 
 acid : — All which may be very true ; but they are al- 
 together iiifufficient to prove that boracic acid is not a 
 peculiar fubflance, fince it difplays properties different 
 from every other body. 
 And to MelTrs Exfcliaquet and Struve have endeavoured, on 
 
 prove that the other hand, to prove that the phofphoric and ba- 
 it K phof- racic acids are the lame. But their experiments mere' 
 J. oncaui. jy o^j^^ (y,j[ thefe acids refemble one another in feveral 
 particulars ; and though they add confiderably to our 
 knowledge of the properties of the phofphoric acid, they 
 are quite inadequate to eflablifh the principle which 
 thefe chemifts had in view ; fince it Is not fufficient to 
 prove the identity of the two acids, to flicw us a refem- 
 blance in a few particulars, while they differ in many 
 others. Boracic acid mull therefore be confidered as a 
 diftinft fubftance, the component parts of which are en- 
 tirely unknown. 
 
 The eafiell method of procuring boracic acid is the 
 following one : Diffolve borax in hot water, and filter 
 the folution; then add fulphuric acid, by little and little, 
 till the liquor be rather more than faturated. Lav it 
 afide to cool, and a great number of fniall, (hining, la- 
 minated cryitals will form. Theie are the boracic acid. 
 They are to be walhed with cold water, and drained 
 upon brown paper. 
 
 This acid has a fourifli tafle at firft, then makes a 
 bittevilli cooling impreffion, and at laft leaves an agree- 
 able fweetnefs. Its cry dais have fome refemblance to 
 Ipermaceti, and it has the fame kind of feel. 
 
 It changes vegetable blues to red ; it has no fmell ; 
 but when fulphuric acid is poured on it, a tranfient 
 odour of muflc is produced *. The air produces no 
 DcSahSi- change on It. 
 
 " ' ' ' ' According to Rcufs, it is foluble In 10 parts of cold 
 water, eight parts of warm water, and 2,5 of boiling 
 water. According to Wenzel, 960 grains of boiling wa- 
 ter dilTclve 434 of this acid. According to Morveau, 
 one pound of boiling water dilTolves only l<S3 grains. 
 
 It is exceedingly fixed when not combined with wa- 
 ter. When expofed to a violent fire it is converted in- 
 to a white tranfparent glafs; which, however, is foluble 
 in water, and produces the acid again by evaporation. 
 
 Boracic acid is alfo foluble in alcohol 5 and alcohol 
 containing it burns with a green flame. 
 % Kirwan't Its fpecific gravity is 1,470!. 
 ^«r.ii.4. ^ * ' '^'^ + 
 
 445 
 
 Method of 
 
 procuring 
 
 it. 
 
 S T R Y. P.irtlT. 
 
 Paper dipped into a folution of boncic acid bur.ns ilisori; 
 with a green flame. , tl^l. 
 
 Though mixed with fine powder of charcoal, it is ' 
 neverthelefs capable of vitrification ; and with I'vjot it 
 melts into a black bitumen-like mafs, which Is, however, 
 foluble ill water, and cannot be eafily calcined to aflics, 
 but fublimes in part *. * Keir't 
 
 With tlie affiftance of a dillilling heat It dilTu'.ves in Oiaitnary, 
 oils, ef2)ecially in mineral oils ; and with thefe it yields 
 fluid and folid products, which give a green colour to 
 fpirit of wine. 
 
 When boracic acid is rubbed with phofphorus, it does 
 not prevent its inflammation ; but an earthy yellow 
 matter is left behind f . i. //„•/_ 
 
 It is hardly capable of oxidating or diflblvlng any of 447 
 the metals except iron and zinc, and perhaps copper. Ifadion 
 Boracic acid combines with alkalies, alkaline eai-ths, P" ,"' ^"^^ 
 and alumina, and nioft ot the metallic oxides, and forms 
 compounds, which are called borats. 
 Its affinities are as follows : 
 I^inic, 
 Barytes, 
 StrontitesJ, 
 Magnefia, 
 Potafs, 
 Soda, 
 Ammonia, 
 Oxide of zinc, 
 
 — iron, 
 
 . lead, 
 
 tin, 
 
 cobalt, 
 
 copper, 
 
 nickel, 
 
 mercury, 
 
 446 
 Its proper- 
 tici. 
 
 * Reufs 
 
 da I 
 
 443 _ 
 Its affini- 
 ties. 
 
 I Dr Ho^f, 
 Tranf. £. 
 ifrtt, iv. 
 
 Alumina, 
 Jargonia^, 
 Water, 
 Alcohol. 
 
 Sect. IX. Fluoric Acid. 
 
 lin, Arm. A 
 Ch:m. ItiiJi 
 20^. 
 
 449 
 
 Thi! mineral called^r/or or fiijibk /par , was not pro- n;it„very 
 perly dlflinguinied from other fpars til! Margraf pub- of fluoric 
 liflied a differtation on it in the Berlin TranfaAions for acid. 
 1768. He firil proved that it contained no fulphuric 
 acid, as had been formerly fuppofed; he then attempted 
 to decompofe It, by mixing together equal quantities 
 of this mineral and fulphuric acid, and diflilliiig them. 
 By this method he obtained u -while fuhUmate, which he 
 fuppofed to be the fluor itfelf volatilized by the acid. 
 He obferved, with aftonifhment, that the glafs r..tort 
 was corroded, and even pierced with holes. Nothing 
 more was known concerning fluor till Scheele publiflied 
 his experiinents three years after ; by which he proved 
 that it was compofed chiefly of lime and a particular 
 acid, which has been called_/?«3n'c acid. ^.g 
 
 To obtain it, put eight ounces of finely powdered Method tff 
 fluor into a retort, and pour on it an equal quantity of obtaining 
 fulphuric acid, and lute to the retort, as exaftly as pof-"- 
 fible, a receiver containing eight ounces of water. Va- 
 pours immediately appear and darken the infide of the 
 veflTel : Thefe are the acid in the fl;ate of gas. The dif- 
 tillatlon is to be condufted with a very moderate heat, 
 not only to allow the gas to condenfe, but alfo to pre- 
 vent the fluor itfelf from fubliraing. After the pro- 
 
 cefs,
 
 Acid. 
 
 45 1 
 Auempts 
 
 Part ir. 
 
 Fluoric cef!", a cm ft of white earth 
 
 which has all the properties of lilica. 
 
 Scheclc i'lippofed that the filica produced was form- 
 ed of Huoric acid and water, and Bergman adopted the 
 fame opinion. But Wiegleb and liuccholz fliewed, 
 that the quantity of filica was exactly equal to what 
 the retort loft in weight ; and Meyer completed the 
 pioof that it was derived from the glafs, by the follow- 
 ing experiment : He put into each of three equal cylin- 
 drical tin vefltls a mixture of three oz. of fulphuric acid 
 and one oz. of Uuor, which had been pulverized in a 
 mortar of metal. Into the firil he put one oz. of 
 pounded glafs; into the feconJ, the fame quantity of 
 quartz in powder ; and into the third, nothing. A- 
 bove'each of the vedels he hung a fponge moillencd 
 with water; and having covered them, he expofcd them 
 to a moderate heat. The fponge in the fiiil cylinder 
 was covered with the cruft in half an hour ; the fponge 
 in the fecond in two hours ; but no cruil was formed 
 in the third, though it was expofed fcveral days. In 
 confequence of this decifive experiment, Bergman gave 
 up his opinion, and wrote an account of Aleycr's ex- 
 periment to Morveau, who was employed in tranilating 
 his woiks, to enable him to correft the miftake in his 
 notes. 
 
 Soon after the difcovery of this acid, difficulties and 
 to dilprove doubts concerning its exiftence as a peculiar acid were 
 Its fxift. ftarted by fome French chemiils, diiguifcd under the 
 name of Boulanger, and afterwards by Mr Achard and 
 Mr Monnet. To remove thefe objections, Mr Scheele 
 inllituted and publilhed a new fet of experiments; which 
 not only completely cft;iblifhed the peculiar nature of 
 the fluoric acid, but once more difplayed the unrivalled 
 abilities of the illuftnoiis difcoverer. Thefe important 
 particulars we pals over thus flightly, bccaufe they have 
 been partly treated of already in the article Chemistry, 
 RclLted by Encycl. One experiment, however, we cannot omit, 
 bcheele, becaufe it is fufficient of itfelf to deftroy almofl all the 
 objections of his antagonills, which confilied in at- 
 tempting to prove, that the fluoric acid was merely a 
 modification of the acid employed to extraCf it. We 
 /hall give it in Mr Sheele's own words. 
 
 " I melted together (fays he) in a crucible two 
 ounces of finely pulverized fluor fpar with four ounces 
 of potafs. As foon as they were melted, I poured out 
 the mafs, rubbed it, when it was become cold, to a pow- 
 der, and extrafted the alkali from it again by lixivia- 
 tion with water. I evaporated the lixivium to dry- 
 ncfs; and threw away the remaining undilfolved powder 
 (which was only one of the component parts of the fluor, 
 and which diilolved readily, and with efFervefcence, in 
 acids) from its folution, in which it may be precipita- 
 ted by fulphuric acid in the form of felenite (fulphat of 
 lime). Upon a little of the dried alkali, put into a fmall 
 retort, I poured fome fulphuric acid, fitted to it a re- 
 ceiver containing fome water; and even before the retort 
 was become hot, I obferved this water to be covered 
 ever with a pellicle of filiceous earth : a certaia proof 
 that the alkali had extrafted the acid from the fluor 
 during its expofure to the fire with it. Should Mr 
 Achard, agreeably to the opinion which he has adopt- 
 
 CHEMISTRY. 
 
 is found in the receiver, ed, conclude from thfs experiment, that the alkali fe- 
 
 .319 
 
 fluoric 
 Acid. 
 
 452 
 
 parated the \olatile earth f om tiie ilu.ir (f) ; ilill he 
 murt certainly allow this earth oi his to be of an acid** 
 nature, finee the alkali is capable of difengaging it from 
 the calcareous earth. — The remaining portion of the 
 dried alkali I diflolvcd again in water, and faturated the 
 fuperfluous alkali with pure nitric acid. After ixpel- 
 lirig from this faturated folution, by means of heat, the 
 carbonic acid gas, which in fuch cafes is always retain- 
 ed iu the liquor, I dropped foir.c of it into lime-water ; 
 whereupon I obtained a white precipitate, which was a 
 regenerated fluor. I now diffolved fome oxide of lead 
 in vinegar, and continued to add to the ley, which had 
 been laturated with nitric acid, as much of this folu- 
 tion as was requiiite, till all precipiution ceafed. Thus 
 I transferred liie fluor acid from the alkali to the oxide 
 of lead. After walliing the precipitate in cold water, 
 ard drying it, I dropped upon a fmall quantity of it a 
 few drops of fulphuric acid ; a frothing up immediate- 
 ly enfueu', accompanied with an extrication of fluor acid 
 vajiours. But perhaps, in this cafe, the volatile earth 
 of fluor unites with the fulphuric acid, and converts 
 this fixed, or almofl fixed acid into acid gas. I can 
 ealily make allowance to Dr Pricftley for being incli- 
 ned to draw fuch a conclufion, fince this celebrated phi» 
 lofopher does not pretend to be a chemilt; (c). Being 
 defirous of feeing whether luat alone was capable of 
 expelling tills acid from the oxide of lead, I put a little 
 of this fluorated oxide into a fmall retort, the receiver 
 to which contained fome water. The oxide was melt- 
 ed ; but I could not perceive any acid. The bottom 
 of the retort was moreover quite corroded and difl'olved, 
 fo that the whole ran into the fire. Thus the oxide of 
 lead retains this acid in the fire, and will not part with 
 it, unlefs the oxide is combined with fome other fub- 
 flance. I therefore rubbed the remaindtr of my fluo- 
 rated oxide of lead with an equal quantity of charcoal 
 powder, and dlllilled the mixture in an open fire in a 
 fmall glafs retort, to which was adapted a receiver con- 
 taining fome water. As foon as the redudtion of the 
 oxide of lead took place, the neck of the retort became 
 incruiled with a white fublimate, aiid a filiceous pelhcle 
 appeared upon the water. Tlie fublimate had a four 
 taile, becaufe the filiceous earth of which it confifls is 
 penetrated with fluoric acid ; and the acid water in the 
 receiver let fall, on the addition of volatile alkali, a lili- 
 
 ccons earth *." 
 
 * Crelts 
 
 horry are we to add, that fince the death of this t^A- -Journal,'^ 
 mirable man, to ufe the words of Mr Kirwan f, a man 521. Kn'g. 
 as eminent in the chemical as Newton in the mathema-'^''^"''- 
 tical branch of natural philofophy, Mr Monnet t has '^ ''^^'""'''''^ 
 thought proper to renew his attacks in a flyle of haueh-'!"^i'' " ''^'j 
 tmels and acrimony that inlpires infinite dilgufl. The P/,/. xxx. 
 falacy of his reafoning is fufficiently expofed by Mr Le-'5.5- 
 onhardi, in the 6th volume of his late learned edition 453 
 of Macquer's Didionary. And Leon. 
 
 Fluoric acid may be obtained in the form of gas, by 
 applying a moderate heat to fulphuric acid and fluor I'? proper* 
 fpar, and receiving the produA over mercury. ties. 
 
 This gas is the acid in a ftate of purity. It is invi- 
 fible and elaftic like air ; it does not maintain combuf- 
 
 UOQ, 
 
 (f) Mr Achard affirmed that fluor was compofed of a peculiar volatile earth. 
 
 (g) Dr PriefUey at firft advanced tliis hypothefis, but he afterwards gave it up.
 
 32-0 
 
 CHEMISTRY. 
 
 Part it: 
 
 o ! nther 
 
 t n.d. 
 
 Carbonic tion, nor can animals breathe it without death. It has a 
 
 ^"^- piiiigent finell, not unlike that of muriatic acid. 
 
 '^~~ It is heavier tlian common air. It corrodes the (kin 
 
 alniofl inllantly. It combines rapidly with water ; and 
 
 if it lias been obtained by means of glafs vciTels, it dc- 
 
 politcs at the fame time a quantity of lilica. 
 
 Water imprtgnate-d witli this gas docs not freeze at 
 * PritJUey, a higher temperature than i^***. 
 
 it 36J. li, tlic {late of gas this acid does not aft upon nitrous 
 
 . ^^^- e-as nor fulphur Alcohol and ether aljforb it, but it 
 does not alter their qualities f. 
 
 It is capable of oxidating iron, zinc, copper, and arfenic. 
 It docs not att upon gold, platinum, iilver, mercury, 
 lead ? tin, antimony, cobalt. 
 
 It combines with alkalies, alkaline earths, and alumi- 
 na, and metallic oxides, and forms compounds denomi- 
 nated flujts. .... 
 
 It is capable, as we have feen, of dilTolving filica, 
 which is infoluble in every other acid ; accordingly it 
 corrodes glafs. This property has induced feveral inge- 
 nious men to attempt, by means of it, to engrave, or 
 • rather etch, upon glafs. 
 
 The affinities of fluoric acid are as follows : 
 Lime, 
 Barytes, 
 StrontitesJ, 
 Magnefia, 
 Potafs, 
 Soda, 
 Ammonia, 
 Oxide of zinc, 
 manganefe J, 
 
 4i6 
 tesaffinitte 
 
 \ Dr Hcpt. 
 
 5 Lmoificr. 
 
 itn^ Ann. de 
 Chim. xziu 
 30 S. 
 
 457 
 
 Difmvery 
 
 - iron, 
 
 —~— lead, 
 
 tin, 
 
 — — - cobalt, 
 
 — — — copper, 
 
 I — nickel, 
 
 arfenic, 
 
 bifmuth, 
 
 ■' ' — mercury, 
 
 — — — filver, 
 
 gold, ' 
 
 platinum. 
 
 Alumina, 
 Jargonia 1| ? 
 Water, 
 Silica, 
 Alcohol. 
 
 Sect. X. Of Carbonic ylcid. 
 
 Carbonic acid is compofed of carbon and oxygen. 
 According to Lavoifier's experiments, the proportions 
 are 28 parts of carbon and 72 of oxygen. Mr Proiiil 
 informs us that there is alfo a carbonous acid (h) ; but 
 with this acid we are not at prefent acquainted, and 
 cannot therefore defcribe it. ' 
 
 Paracelfus and Van Helmont were acquainted with 
 
 of carbonic jj,g £3,5^^ that air is extricated from folid bodies during 
 acid. 
 
 certain proceffes, and the latter pave to air thus pro- Cnrh nic 
 duced the name of gas. Boyle called thefe kinds of air '^" <'- 
 artificial airs, and fufpefted that they might be diffe- ' 
 
 rent from the air of the atmofphere. Hales afcertaintd 
 the quantity of air that could be extricated from a 
 great variety of bodies, and fliewtd that it formed an 
 efTential part of their compofition. Dr Blaok proved, 
 that the fubftances then called lime, magnefia, and alka- 
 lies, are compounds, confiding of a peculiar ft^c^ies of 
 air, and pure lime, magnefia, and alkali. To this fpe- 
 cles of air he gave the name oi fixed air, becaufe it ex- 
 ifted in thefe bodies in a fixed Rate. This air or gas 
 was afterwards inveftigated by Dr Prieftley, and a great 
 number of its properties afcertained. From thefe pro 
 perties Mr Keir * firit concluded that it was an acid ; « Keir'i 
 and this opinion was foon confirmed by the experiments -Wa^jMr, 
 of Bergman, Fontana, &c. Dr Prieftley at lirft fuf-*"^'- ■^"■• 
 pefted Uiat this acid entered as an element into the com- 
 pofition of atmofphcrical air; and Bergman adopting 
 the fame opinion, gave it the name oi aerial acid. Mr 
 Bewdly called it mephitic acid, becaufe it could not be 
 refpired without occafioning death ; and this name was 
 alfo adopted by Morveau. Mr Keir called it calcareous 
 acid; and at laft Mr Lavoifier, after difcovering its com- 
 pofition, gave it the name of carbonic acid gas. g 
 
 The opinions of chemlfts concerning the compq/ition Theoriei 
 of carbonic acid have undergone as many revolutions as about i(a 
 its name. Dr Prieftley and Bergman feem at firft to '^'"^P°'i" 
 have confidercd it as an element; and feveral celebrated 
 chemifts maintained that it was the acidifying principle. 
 Afterwards it was difcovered that it was a compound, 
 and that oxygen gas was one of its component parts. 
 Upon this difcovery the prevalent opinion of chemifts 
 was, that it confifted of oxygen and phlogifton ; and 
 when hydrogen and phlogifton came (according to Mr 
 Kirwan's theory) to fignify the fame thing, it was of 
 courfe maintained that carbonic acid was compofed of 
 oxygen and hydrogen : and though Mr Lavoifier de- 
 monftrated that it was formed by the combination of 
 carbon and oxygen, this did not prevent the old theory 
 from being maintained ; becaufe carbon was itfelf con- 
 fidercd as a compound, into which a very great quanti- 
 ty of hydrogen entered. But after Mr Lavoifier had 
 demonftrated that the weight of the carbonic acid pro- 
 duced was precifely equal to the carbon and oxygen 
 employed; after Mr Cavendifh had difcovered that oxy- 
 gen and hydrogen when combined did not form carbo- 
 nic acid, but water — it was no longer poffible to hefi- 
 tate that this acid was compofed of carbon and oxygen. 
 Accordingly all farther difpirte about it feems now at an 
 end. At any rate, as we have already examined the 
 obje£tions that have been made to this concluCon, it 
 would be improper to enter upon them here. iS9 
 
 If any thing was ftill wanting to put this conclu- ''* ^""y"^ 
 fion beyond the reach of doubt, it was to decom- 
 pound carbonic acid, and thus to exhibit its component 
 parts by analyfis as well as lynthefis. This has been 
 aftually done by the ingenious Mr Tennant. Into a 
 tube of glafs he introduced a bit of phofphorus and 
 
 fome 
 
 (h) When there are two acids having the fame bafe, but containing different quantities of oxygen, they are 
 diftinijuilhed by their termination. The name of that which contains moil; oxygen ends in ic, the other in ous. 
 Thus fulphuric and fulphurous acids, nitric and nitrous, phofphoric and phofphorous, carbonic and carbonout.
 
 Part 11. CHEMISTRY. 
 
 Carbonic fome carbonat of lime. He then fcalcd the tube her 
 
 321 
 
 Acid. metically, and applied heat. Phofphat of lime was 
 *■ V 'formed, and a quantity of carbon depoiited. Now 
 phofphat of lime is compofcd of phofplioric acid and 
 lime ; and phofphoric acid is compofcd of pholphorus 
 and oxygen. The fubllances introductd into the tube 
 were phofphorus, lime, and carbonic acid ; and the fub- 
 ftances found in it were phofphorus, lime, oxygen, and 
 carbon. The carbonic acid, therefore, mull liave been 
 decompofed, and it mull have confilled of oxygen and 
 carbon. This expcrirrcnt was repeated by Dr Pearfon, 
 who afcertained that the weight of the oxygen and car- 
 bon were together equal to that of the carbonic acid 
 which had been introductd ; and in order to (hew that 
 it was the carbonic acid v'hich had been decompoied, he 
 introduced pure lime and pholphorus ; and inllead of 
 obtaining phol'phat of lime and carbon, he got nothing 
 but phoipiuiret of lime. Thefe experiments were alio 
 confirmed by MefTrs Fourcioy, Vauquclin, Sylvellre, 
 •*Ann.d! and Broigniart (i) *. 
 
 Cii'm. xiii. Carbonic acid may be obtained by pouring fulphuric 
 3"- acid upon chalk, and receiving the product in a pneu- 
 
 matic apparatus. 
 
 It is invifible and elaftic like common air. It extin- 
 guiflies a candle, and is unfit for reipiratiou. It has no 
 fmell. 
 
 Its fpecific gravity is o,ooi8 f ; but this varies ac- 
 cording to its drynefs or moiilure. 
 
 It reddens the tinfture of turnfole, but no other ve- 
 getable colour J. 
 
 Atmofpheric air contains about -rJcr P'"'' of '•'^'^ 
 
 g*^ ('^)- . . . „ . . 
 
 Water abforbs it by agitation, or by allowing it to 
 
 remain long in contaft with it. At the temperature of 
 41" water abforbs its own oulk of this gas. The fpe- 
 cific gravity of water faturated with it is l,coij. This 
 water, at the temperature of 3 ^°, has little tafte; but if it 
 be left a few hours in the temperature of 88'', it affumes 
 an agreeable acidity, and a fparkling appearance ^. 
 
 Ice abforbs no carbonic acid ; and if water contain- 
 ing it be frozen, the whole feparates in the aft of free- 
 
 || PrhJIhy, zing II . 
 
 i no. This gas alfo feparates from water at the boiling 
 
 f UiJ. temperature ^. 
 
 Alcohol and oil of turpentine abforb double their 
 weight of this gas ; olive oil its own bulk. Ether 
 
 « Birgman, mixes with it in the ftate of gas*. 
 
 '*'''• Phofphorus fuffers no change in this gas except it 
 
 f Bri/jni- contains a mixture of oxygen gas f. It has an affinity 
 
 ttlli, S ii:lji>l- {or common air. Bergman left a bottle of it uncorked, 
 and found that in a few days it contained nothing but 
 common air. Common air, indeed, has fo ftrong an af- 
 finity for this gas, that it attrails it from water, as Mr 
 Welter has obferved J. 
 SupPL. Vol. I. Part I. 
 
 460 
 Its proper- 
 ties, 
 
 \ Bergman^ 
 1.9. 
 
 I Uid. 
 
 § IM. 
 
 fins Jour- 
 nal, i. 440 
 
 X Ann. (i^ 
 Grim. iii. 
 JIJ. 
 
 It is abfurbcd by red hot charcoal, as Moroizo and Acctou» 
 
 La Metherie have ihevvn. , ^''^' . 
 
 It is capable of combining with alkalies, alkaline ,(,, 
 
 earths, and alumina, and feveral metallic oxides, and ofCoin- 
 
 fiiiming compounds known by the ndmu of carlionats.\"^^"<^i 
 
 It has no affinity for jargonia, according to Klapioth •; * Jmrn. <U 
 
 but, according to Vauquelin, it iiasf- Pbyf.xxtsi. 
 
 Its affinities, as arranged by Bergman, are as follows: , ^^ . 
 
 Barytcs, t7.,m. xxii. 
 
 Lime, 404. 
 
 Strontites T, 46t 
 
 Potafs, A".'» »*- 
 
 „ ' nines. 
 
 ^oaa. } Dr Hofe. 
 
 Magncfia, 
 
 Alumina, 
 
 MetaUic oxides as \n fulphuric acid. 
 
 Oxygen gas §, § i^j^ ^,/. 
 
 Water, icr. 
 
 Alcohol. 
 
 Sect. XI. Of Acetous Acid. 
 
 Acetous acid or vinegar was known many ages be- 
 fore the difcovery of any other acid, thole only except- 
 ed which exift ready formed in ve^^i jbles It is men- 
 tioned by Mofes, and indeed teems t'j ii.ive been in com- , 
 mon life among the Ifraelites and other eallern nations 
 at a very early period. 
 
 The methods of procuring, purifying, and concen- 
 trating this acid, have beLii already given in the articles 
 Chemistry, Fermentation, and Vi \egar, ^/irj'c/. 
 and cannot therefore be repealed in this place. 
 
 It has been afcertained beyond a doubt, that this 
 acid is compofed of carbon, hydiogen, and oxygen ; 
 but neither the manner in which tliefe fubitances are > 
 
 combined, nor their proportions, have been accurately 
 afcertained. " 463 
 
 Acetous acid, as commonly prepared, is very fluid, Lowitz't 
 
 has a pleafant fmell, and an acid talle. ' It reddens ve- ",'«'';"<* "'' 
 11 1 T 1 • ii • ■ ■ ]• ■ L obtaining 
 
 gctable colours. In this ftate it is mixed vi'itti a gfeat ^j.^ ^^^^ 
 
 proportion of water ; but Mr Lowiiz of Peterfburg has tons acid, 
 difcovered that it may be obtained in a folid cryltalli- 
 zed form. Of this curious and inftruftive procefs we 
 fhall tranfcrlbe his own account ||. 1| Crtll't 
 
 " I have long been accullomed (fays he) to prepare J''""'"'''' 
 concentrated vinegar by congelation in the following'' "'' n. ''^' 
 manner : I freeze a whole barrel of vinegar as much as 
 poffible, then dillil the remaining unfiozen vinegar in a 
 water-bath ; by which means I at firft efpecially coUeft 
 the fpirituous ethereal part ; the vinegar, which next 
 comes over, I freeze again as much as poffible, and af- 
 terwards purify it, by difb'lliiig it again with three or 
 four pounds of charcoal powder. Thus I never fail to 
 get a very pure, fwect-imelling, highly concentrated vi- 
 negar ; the agreeable odour of svhich, however, may be 
 S s ftill 
 
 (i) Count MufPin-Pufchin having boiled a folution of carbonat of potafs on purified phofphorus, obtained 
 carbon. This he coniidered as an inftance of the decompofition of carbonic acid, and as a confirmation of the 
 experiments rchrted in the text. See Hnn. de Chim. xxv. 105. 
 
 (k) At lead near the furface of the earth. Lamanon, Mongez, and the other unfortunate philofophcis who 
 accompanied La Peroufe in his lad voyage, have rendered t not improbable ihat at great heights the quantity 
 of this gas is much fmaller. They could detedl none in the atmofphere at the furamit of the Peak of Teneriffe. 
 See Lamanon' s Memoir at the end of La Peroufi^t Voyage,
 
 322 
 
 Acetous 
 Acid. 
 
 G H E M I 
 
 ftill improved by the addition of a proper quantity of the 
 ethereal h'quor collefttd it the beginning of the firft dif- 
 tillation, but which mult be previoufly dephlegmated 
 by two or three reftificalions. 
 
 " After the diftillatlon in the water-bath was over, 
 that no vinegar might be loft, I ufed to move the retort, 
 with the charcoal powder whicli remained in it, to a 
 fandbatli ; and thus I obtained, by means of a ftrong 
 fire, a few ounces more of a remarkably concentrated 
 vinegar, which was of a yellow colour. 
 
 " Having coUefted about ten ounces of this concen- 
 trated vinegar, I expofed it lail winter in the month of 
 ^December to a cold equal to — 2 2^; in which fituation 
 it {hot into cryftals from every part. I let what re- 
 mained fluid drop away from the cryftals into a bafon 
 placed underneath, lirft in the cold air, and afterwards 
 at the window within doors. There remained in the 
 bottle fnow-white finely foliated cryftals, clofcly accu- 
 mulated one upon the other, and which I at firll took 
 to be nothing but ice : on placing them upon the warm 
 flove, they dilTolvcd into a fluid which was perfeftly as 
 limpid as water, had an uncommonly ftrong, highly pun- 
 gent, and almoft fuffucating acetous fmell, and in the 
 temperature of — JV immediately congealed into a fo- 
 lid white cryftallized mafs, refembling camphor. 
 
 " After I had obferved that vinegar in this ftate is of 
 fuch an extraordinary ftrength and purity as to he in its 
 higheft degree of perfeiStion, I took aO poffible pains to 
 find out a method of obtaining all the acetous acid in 
 the ftate of glacial vinegar. 
 
 " To avoid circumlocution, I (hall denote the ftrength 
 of each fort of vinegar, which it was neceflary for me 
 to know in my experiments, by degrees, which I afcer- 
 tain in the following manner : viz. to one drachm of 
 vinegar I add, drop by drop, a clear 'Solution of equal 
 parts of carbonat of potafs and water, till all at once a 
 cluudinefs or precipitation appears. Although, on the 
 appearance of this fign, the acid is already fuperfatu- 
 rated with the alkali, yet it feems to me to be a more 
 accurate left for afcertaining its ftrength than the cefla- 
 tion of efFcrvcfcence ; for as the point of faturation ap- 
 proaches, the efl"ervefcence becomes fo imperceptible, 
 that it is alinoft impoflible to determine with precifion 
 when it is really at an end. Now, every five drops of 
 the alkaline folution, which I find it neceffary to add to 
 the vinegar till the precipitation takes place, I reckon 
 as one degree. Thus, for example, if a determinate 
 quantity of vinegar requires 25 drops for that cffeft, I 
 denote its ftrength by five degrees. This is about the 
 ftrength of good dillilled vinegar. 
 
 •' 1 call that vinegar which, in confequence of Its 
 concentration, is capable of cryftallizing in a great de- 
 gree of cold, cryjlalitxabh "vinegar ; the cryftals of vine- 
 gar, feparatcd after the cryftallization is completed from 
 the remaining fluid portion, I czW glacial vinegar ; and, 
 laftly, to the fluid refiduum I give the name of mother- 
 ky of vinegar. 
 
 " From a great number of experiments, I have found 
 that vinegar mull have at leaft 24 degrees of concentra- 
 tion before it can be brought to cryftallize by expofure 
 to the mod intenfe cokL Vinegar muft be of the llrength 
 ef 42 degrees at leaft, in order to become glacial vine- 
 gar ; iiiz. in this ftate of concentration it has the pro- 
 perty of cryftallizing in a degree of cold not exceeding 
 that iu which water begins to freeze. 
 
 S T R y. 
 
 Part ir. 
 
 " I have found that charcoal, on being diftilled with 
 vinegar in a water bath, poflcifes the fnigular and hi- 
 therto unknown property of imbibing a certain quan- 
 tity of the acetous acid in a very concentrated ftate, and 
 of retaining it fo ftrongly, that the acid cannot be fe- 
 parated from it again but by the application of a con- 
 iiderably greater degree of heat than that of boiiinj; 
 water. Upon this circumftance is founded the new 
 method which I have difcovered of concentrating vine- 
 gar, fo as to obtain all its acid in the pureft ftate, viz. 
 that of a glacial vinegar. 
 
 " Let a barrel of vinegar be concentrated by freezing 
 in the manner above defcribed, and let the concentrated 
 vinegar thus obtained, free from all inflammable or fpi- 
 rituous parts, be put into two retorts: Add to each of 
 them five pounds of good charcoal reduced to a fine 
 powder, and fubjciSt them to dillillation in a water-bath. 
 When no more drops of vinegar come over, put the 
 diftilled liquor into two frefh retorts ; and after adding 
 five pounds of charcoal powder to each, proceed as be- 
 fore to the diftillation in a water-bath. In the mean 
 while, the two firft retorts are to be placed in a fand- 
 bath,, that, by means of a brifl< fire, the cryftallizable 
 vinegar, which is retained in the apparently dry char- 
 coal powder, may be expelled from it. The heat muft 
 be ftrong enough to make the drops follow one another 
 every two feconds ; and when, in this degree of heat, 
 20 feconds intervene between each drop, the vinegar 
 which has been collefted muft be removed ; for what 
 follows is hardly any thing elfe but mere water. In 
 this manner about fix ounces and a half of cryftallizable 
 vinegar, which is generally of the ftrength of between 
 36 and 40 degrees, may be collefted from each retort. 
 As foon as the diftillation by the water-bath in the two 
 retorts is over, the diftilled liquor is to be poured back 
 again into the firft retorts upon the charcoal powder,- 
 which remauis in them, and which has been already 
 ufed ; and from each of thefe retorts the remaining 
 cryftallizable vinegar (which generally amounts to as 
 much as the firft quantity) is to be abftrafted by diftiU 
 lation in a fand-bath. Thefe operations may be alter- 
 nately repeated till all the acid of the vinegar which 
 had been concentrated by freezing is converted into 
 cryftallizable vinegar ; or until the diftilled liquor, con- 
 ftantly becoming weaker and weaker at every repeti- 
 tion of the diftillation, comes over at length in the ftate 
 of mere water, which, with the above mentioned quan- 
 tity of charcoal powder, generally happens at the fourth 
 cr fifth diftillation. Now, in order to obtain the great- 
 eft part of the pure acid contained in the cryftallizable 
 vinegar in the form of glacial vinegar, it muft be fet to 
 cryftallize in a great degree of cold ; and the mother- 
 ley muft be afterwards thorotighly drained from the gla- 
 cial vinegar, by letting it drop from the cryftals, firft 
 in the cold, and then in the room before the window. 
 The mother-ley may be rendered further cryftallizable 
 by diftilling it with a little charcoal powder ; the weak- 
 er part, which comes over firft, being put afide. But 
 if a perfon wiihes to keep the cryftallizable vinegar for 
 other purpofcs, and without feparating any glacial vine- 
 gar from it, he muft diftil the whole of it again with 
 charcoal powder in a fand-bath. 
 
 " I have found by accurate experiments, that, by 
 means of this curious procefs, ten pounds of vinegar^ 
 concentrated by freezing to the 90th degree, may be 
 
 made. 
 
 Acetous 
 Acid.
 
 Part II. 
 
 Ac^ruu- 
 Acid. 
 
 CHEMISTRY. 
 
 464 
 
 A^ion of 
 acetou' a- 
 cid on o- 
 ther bo- 
 dies. 
 
 465 
 Its aftini. 
 
 li£3. 
 
 made to yield 38 ounces of ciTflallizabk vinegar, from 
 which 20 ounces of ghicial vinegar may be olnaincd. 
 
 " What conllitutes the cxtclleiice of this method is, 
 that the conceiitraiiou and puiilication are effcCltd by 
 one and the fame medium, viz. the cliarcoal powder; 
 in confequence of which, both intentions are lulSUed at 
 the fame time. 
 
 " Lad year, after muc-h reflexion, I was fo happy as 
 to find out another very efFertual method of fepaiating 
 the acetous acid from the other lubftances combined 
 with it, fo as to obtain it at once in the ilate of a gla- 
 cial vinegar of the grcatefl pofTible llrength. The fe- 
 parating medium which I thought of is fulphat of pot- 
 afs fuperfaturated with iulphuric acid ; a fait in which, 
 conformably to my purpole, the fulphuric acid exills in 
 a perfeftly dry and dcplilegmatcd ftate. 
 
 " By means of this fait a highly concentrated glacial 
 vinegar may be obtained in the following manner : 
 
 " Let three parts of acetated foda, prepared with vi- 
 negar diftilled over charcoal, and evaporated to perfeft 
 drynefs, be melted in a ftrong heat ; then pour it out, 
 and rub it to a very fine powder. Mix this powder 
 very accurately with eight parts of fuperfaturated ful- 
 phat of potafs that has been previoufly well dried, and 
 in like manner reduced to a fine powder; put the whole 
 into a retort, and diftil with a gentle heat, in fuch man- 
 ner that, along with the drops, fome vapours alio may 
 be perceived to come out of the neck of the retort ; 
 but by no means fo that the receiver fliall be filled with 
 thcfc vapours. Notwithftanding the moderate heat, the 
 vinegar conies over very fall, and the quantity of gla- 
 cial vinegar, of the ftrength of 54 degrees, which is 
 thus obtained, amounts to nearly two parts." 
 
 Acetous acid is capable ot oxidating iron, zinc, lead, 
 nickel, tin, copper. 
 
 It does not aft upon gold, filver, platinum, mercury, 
 bifmuth, cobalt, antimony, arfenic. 
 
 It combines with alkalies, alkaline earths, and alumi- 
 na, and metallic oxides, and forms compounds known 
 by the name of acetltes. 
 
 Its affinities are as follows : 
 Barytcs, 
 Potafs, 
 Soda, 
 
 Strontitcs ? 
 Lime, 
 Magnefia, 
 Ammonia, 
 Oxide of zinc, 
 -^— — manganefe, 
 
 Alumina *, 
 Jargonia f ? 
 
 iron, 
 
 lead, 
 
 tin, 
 
 cobalt, 
 
 copper, 
 
 nickel, 
 
 arfenic, 
 
 bifmuth, 
 
 mercury, 
 
 antimony, 
 
 filver, 
 
 gold, 
 
 platinum. 
 
 ■iECT. 
 
 Watw, 
 Alcohol, 
 
 XII. Of Acetic Acid. 
 
 Accric 
 Aci.l 
 
 If ncctite of copper be diftilled, an acid comes over 
 of a more pungent tmell than acetous acid, capable of 
 cryilallizing, and having a ftrojiger afiinity for otl.er bo- 
 dies than acetous acid. It is called acelic acid, and is 
 fuppofed to contain a larger proportion of oxygen than 
 acetous acid. This additional dofe it is fuppijfed to re- 
 ceive from the oxide of copper, which during the pro- 
 cefs is reduced to the metallic ilate. It can hardly be 
 doubted that the glacial vinegar of Lowitz, defcribed in 
 the preceding fedion, is really acetic acid, though it 
 would perhaps be difficult to explain its formation. Il» 
 affinities are the fame with thofe of the acetous acid. 
 
 Sect. Xin. 0/ Oxalic MJ. 
 
 Sugar, a well-known fubftance extrafted from the 
 fngar-cane, appears to have been ufed in the Eaft at a 
 very early period ; but it made its way weftward very 
 Howly. As a medicine, it is mentioned by Diofcorides ; 
 but it was not in common ule in Europe till after the 
 14th century. 
 
 It has been proved that fugar is compofed of oxygen, Ccmvofi. 
 carbon, and hydrogen. Lavoifier concluded, from a longtion of fu- 
 feries of delicate experiments, that it confills of 8 parts g'>r. 
 of hydrogi;n, 64 of oxygen, and 28 of carbon. , 
 
 From fugar, by a particular procefs, an acid has been Dn^overy 
 obtained called oxu/ic acid, becaufe it exifts ready form of oxalic 
 ed, as Scheele has proved, in the oxalis acelofella, oratid. 
 wood forrel. At firlt, however, it was called t!ie acid 
 oj fugar, or the ftccharinc acid, 
 
 i\.s the earlitll and bell account of the oxalic acid 
 was publiflied by Bergman, he was for a long time 
 reckoned the difcoverer of it ; but Mr Ehrhart, one of 
 Scheele's intimate friends, informs us, that the world is 
 indebted for its knowledge of this acid to that ilhiftrious 
 chemid*, and Hermftadt and WeJlrum affign the dif- • Ehvart't 
 covcry to the fame author f. The affertions of thefc -Vi,"i'« 
 gentlemen, who bad the beft opportunity of obtaining/'*'' '^^'"*'" 
 accurate information, are certainly fufficient to ellabiidi p^'"; '^^^' 
 the faft, that Scheele was the real difcoverer of oxalic p. 54. 
 
 acid. t keir's 
 
 Bergman gives us the following procefs for obtaining •'■'"'"""'O'- 
 this acid. " Put one ounce of white fugar powdered ,vie1hod of 
 into a tubulated retort, with three ounces of llrong ni- procuring 
 trie acid, the fpecific gravity of which is to that ofit. 
 water as ,561. When the folution is over, during 
 which many fumes of the nitrous acid efcape, let a re- 
 ceiver be fitted, and the liquor made to boil, by which 
 abundance of nitrous gas is expelled. W^hen the liquor 
 in the retort acquires a nddilh brown colour, add three 
 ounces more of niiric acid, and continue the boiling 
 till the fumes ceafe, and the colour of the liquor va- 
 niflies. Then let the contents of the retort be emp- 
 tied into a wide vcffcl ; ami upon cooling, a cryllallj. 
 zation will take place of flender, quadrilateral prifmj, 
 which are often aflixcd to each otiicr at an angle of 450. 
 Thcfe cryitals, collected and dried on blottnig paper, 
 will be found to weigh i| dr. 19 gr. By bo3ing the 
 remaining lixivium with two ounces of nitric acid in 
 the retort, till the red fumes almoil difappear, and by 
 repeating the cryflalirzation as before, -J dr. i^ gr. of 
 folid acid will be obtained. If the procefs be repeated 
 S s 2 once
 
 3H 
 
 CHEMISTRY. 
 
 Oxalic 
 
 Acid. 
 
 * Bergman. 
 t HermJIaJt. 
 
 469 
 Its proper- 
 ties. 
 
 t Bergman ^ 
 
 II Hid. 
 
 § ttid^ 
 
 1 Uid. 
 
 » Jiid. 
 
 f Encyc. 
 MetboJ 
 art. .4«J; 
 Saccharin , 
 
 once more upon the refiJiium, which has now a glutL- 
 nous conlillence, witli the AicccfTive additions of fmall 
 quantities of nitric acid, amounting in all to two oun- 
 ces, a faline brown deliqnelcent inafs will be formed, 
 weighing half a dram, of which about a half will be 
 lofl by a farther purification. The cryilals obtained 
 thus at different times may be purified b-- folution and 
 ci-)ftHllization, and by digciting the lad lixivium with 
 fome nitric acid, and evaporation with the heat of the 
 fun." 
 
 By the fame procefs Bergman obtained It from gum 
 arabic, alcohol, and honey : Schecle, Hermftadt, Wef- 
 trum, Hoffman, &c. from a great variety of other ve- 
 getable produftions ; and BerthoUet from a great num- 
 ber of animal fubilances. 
 
 It is of great confeqiicnce not to ufe too much nitric 
 acid, otherwife the quantity of oxalic acid will be dimi- 
 nifhed ; and if a very great quantity of nitric acid be 
 ufed, no oxalic acid will be obtained at all *. On the 
 contrary, if too fmall a quantity of nitric acid be ufed, 
 the acid obtained will not be the o.\alic, but the tarta- 
 rous-|-. We think we haveobferved, that a confiderably 
 larger proportion of oxalic acid may be obtained by 
 pouring nitric acid on fugar, and allowing thefe fubilan- 
 ces to aft upon each other while cold. When the pro- 
 cefs is condufted in that manner, hardly any thing fe- 
 parates but nitrous gas. 
 
 Oxalic acid is capable of cryflallizatlon, or rather it 
 is generally obtained in that ftate. Its cryilals are qua- 
 drilateral prifms, the ends of which often terminate in 
 ridges J. 
 
 They are foluble in their own weight of boiling wa- 
 ter : water at the temperature of 65,7" diffolves half its 
 weight of them. The fpecilic gravity of the folution 
 is 1,0593 II • ^"'^ hundred parts of boiling alcohol dlf- 
 folve 56 parts of thefe cryilals ; but at a mean tempe- 
 rature only 40 parts §. They are not eafily fuluble In 
 ether. Fixed and volatile oils diffolve them, and they 
 may be again obtained by gentle evaporation. Too vio- 
 lent a heat would fublime the acid itfclf. 
 
 Oxalic acid has a very acrid taile when it Is concen- 
 trated, but a very agreeable acid taile when fufficlently 
 diluted with water <[[. 
 
 It changes all vegetable blues except Indigo to a red. 
 One grain of cryflaUized acid, djffolved in 1923 grains 
 of water, reddens the blue paper with which fugar loaves 
 are wrapt: one grain of it, diffulved in 3600 grains of 
 water, reddens paper ftained with turnfole*. Accord- 
 ing to Morveau, one part of the cryftallized acid is 
 fufficlent to communicate a fenfible acidity to 2633 
 parts of water -f-. 
 
 Its fixity Is fuch, that none of It is fublimed when 
 water containing it In folution is railed to the boiling 
 temperature. 
 
 When this crydallized acid is expofed to heat in an 
 open veffel, there arifes a fmoke from It, which affefts 
 difagreeably the nofe and lungs. The refiduuni is a 
 powder of a much whiter colour than the acid had been. 
 By this procefs it lofes tV^^^ °f ''^ weight ; but foori 
 recovers them again on expofure to the air. When di- 
 ftilled, it firft lofes its water of cryftalllzation, then li. 
 quifies and becjmes brown; a little phlegm paffes over, 
 a white faline cruil fublimes, fome part of which paffes 
 into the receiver ; but the greateft part of the acid is 
 deftroyed, leaving in the retort a mafs -j-gth of the whole, 
 
 Part If, 
 
 which has an empyreumatic fmell, blackens fulphuric Tartarouj 
 acid, renders nitric acid yellow, and diffolves in muria- •^' ^''*- 
 tic acid without alteration. That part of the acid which * 
 fublimes is unaltered. When this acid is dlilllled a fe- 
 cond time, it gives out a white fmoke, which, conden- 
 fmg in the receiver, produces a colourltls uncryftalli- 
 zable acid, and a dark coloured matter remains behind*. * Bergman. 
 During all this diftillation a vail quantity of elalllc va- 
 pour makes its efcape. From 279 grains of oxalic acid, 
 Bergman obtained 109 cubic inches of gas, half of 
 which was carbonic acid and half hydrogen. Fontana 
 from an ounce of it obtained 4^0 cubic inches of gas, 
 one-third of which was carbonic acid, the reil hydro- 
 gen. From thefe fadls, it is evident that oxalic acid Is 
 compofed of oxygen, hydrogen, and carbon ; but the 
 proportions are ftill unknown. 
 
 When nitric acid is frequently dlilllled off oxalic acid, 
 acetous acid is produced f. The fulphuric acid, when f Wejtrum. 
 concentrated, feems to produce the fame effeft. Mu- 
 riatic and acetous acids diffolve oxalic acid, but without 
 altering It J. } Bergt,tan, 
 
 Oxalic acid is capable of oxidating lead, copper, iron, 47° 
 tin, biimuth, nickel, cobalt, zmc, manganele. ^^ other 
 
 It docs not att upon gold, tilver, platinum, mercury, bodies, 
 arfenic ? 
 
 Oxalic acid combines with alkalies, alkaline earths, 
 and alumina, and metallic oxides, and forms falts known 
 by the name of oxalats. 
 
 Its affinities, according to Bergman, are as follows: j,sa^' •_ 
 
 Lime, 
 
 Barytes, 
 
 Strontites J, 
 
 Magnefla, 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Alumina, 
 
 Jargonla || ? 
 
 Metallic oxides as \n fulphuric acid, 
 
 Water, 
 
 Alcohol. 
 
 Sect. XIV. 0/ Tartarous JchL 
 
 § DrHcp?, 
 Tranf, Edw. 
 
 ll emcjue.tr.^ 
 Ann. de 
 Clim, xxii. 
 
 »o3. 
 
 472 
 
 Tartar, or cream of tartar as It is commonly called oifcovery 
 vi'hen pure, has occupied the attention of chemifts for of tartarouj 
 feveral centuries. Duhamel and Groffc, and after thcm^^'*^* 
 Margraf and Rouelle the Younger, proved that It was 
 compofed of an acid united to potafs: but Scheele was 
 the firll who obtained this acid in a feparate ftate. He 
 communicated his procefs for obtaining it to Retzlus, 
 who publilhed it in the Stockholm '1 ranfaftlons for 
 1770. It confiiled in boiling tartar with lime, and 
 in decompofing the tartrite of lime thus formed by 
 means of lulphuric acid. 
 
 This acid, by a gentle evaporation, yields cryftals fo u, proper. 
 Irregular In their figure, that every chcmift who has ties, 
 treated of this fubjedl has given a different defcrlptlon * *'^.f«""'» 
 of them. According to Bergman, they generally con.'"y^°^' 
 fift of divaricating lamellae * ; according to Van Pack- £iT,„f, acidi 
 en, they affume ofteneft the form of long pointed T;r/ari. 
 prifms f ; Spielman and Corvinus J obtained them in -' '^nateSa 
 groups, fome of them lance-fliaped, others needle-form- /p"''''"'''" 
 ed, others pyramidal. Morveau obtained them needle- ^/,,i,y^ 
 form §. They do not experience any change in the air; CA/». i. 
 
 heat 3^3-
 
 Fart Tr 
 
 Citric 
 Ac ill. 
 
 ihiJ lil'.d 
 ii. 4<'5 
 
 3Iid Cctvt- 
 nils, ii>:J, 
 ^ hcii'ifaJt 
 and «•</- 
 
 tll,K. 
 
 I Bergman, 
 i.IiO. 
 
 474 
 Its adion 
 on otlicr 
 buJics. 
 
 CHEMISTRY. 325 
 
 heat ctecompofes them. In tlie open fire tliey buru wards tlie end of the evaporation. The ciyftals alfo Citric 
 witheut leaving any other refuluum than a coal, which were black. By repeated folutions and evaporations, , ^'^'^'- , 
 generally contains a little lime *. In dole vclTels, the this black matter was liparated, and found to be car- " 
 produd is carbonic acid and hydrogen gasf. If the bon. Hence he concluded that mucilage had betn pre- 
 proper quantity of nitric acid be diflilled otf the cry Hals, fent ; for mucilage is compofed of carbon, hydroRen, 
 they are converted into oxalic acid, and the nitric acid, and oxygen ; fulpluiric acid caufes the hydrogen and 
 as ufaal, paffes into the nitrous acid J. Hence it is evi- oxygen to combine and form water, and the carbon re- 
 dent that tartarous acid alfo, like the four former, is mains behind. It is not certain, hoviever, as Mr Ni- 
 compofcd of oxygen, hydrogen, and carbon; but the cholfon remarks very jnftly •, that ihc lulphujic acid • f^ ictol/ca, 
 proportions are equally unafcertaini'd. may not ad upon tiie citric acid itfelf, ai'.d that the'*"'" 
 
 This atid, when in ci7fl.als, diflolves readily in water, carbon may not proceed from tlir d.-compofition of it ; 
 
 Bergman obtained a folulion, the fpccific gravity of at leaft the experiments of Mr Di/c are infufficicnt to 
 
 which was 1,230 J. Morveau oblerved, however, that prove the contrary. In that caie the fmaller the cxcefs 
 
 crylLils formed fpontaneoufly ia a folution, the fpecific of fulphuric acid ufed the better. 4-'7 
 
 gravity of which was 1,084. The cryftals of citric acid are rhomboidal prifms, the '?" P^'P"- 
 
 It has a very lliarp acid tafte, and reddens vegetable fides of which are inclined to each other in angles of""* 
 
 blues. about 120 and 60 degrees, terminat..d at each end by 
 
 Tartarous acid does not oxidate gold, filver, platinum, four trapezoidal faces, wliich include the folid angles "t-.t D!zf, 
 
 They are not altered by expofurc to the air. '*"'■ 
 
 An ounce of diftillcd water, at the temperature of 
 
 lead, bifmuth, nor tin, and hardly antimony and nickel 
 It combines with alkalies, alkaline earths, and alu 
 
 mina, and metallic oxides, and forms falls known by the the atmcfphere, diflolves one ounce and two drams of 
 
 T's affini- 
 ties. 
 
 476 
 Method nf 
 obtaining 
 citric aciJ. 
 
 cryftallized citric acid; and during the folution the tem- 
 perature is lowered 29,750. Boiling water diflolves 
 twice its weight of this acid J. I !J iliJ. 
 
 Citric acid has a very acid talle ; it turns vegetable 
 blues to a red. ,.g 
 
 It is capable of oxidating iron, zinc, tin. It does 't? ae^ioa 
 not atl upon gold, filver, platinum, mercury, bifmuth, °" '^''"^'^ 
 antimony, arfenic. bodies. 
 
 It combines with alkalies, alkaline earths, and alu- 
 
 11 StoMolm 
 
 Tranf. 
 1774- 
 
 ^ Scheele's 
 £J]ays. 
 
 * Scl'tiU. 
 CrcU's Ait- 
 nals, i^SS. 
 t Wcprum. 
 
 X Nkhol- 
 fcnt Jottr- 
 nal, ii. 43. 
 
 name of larlriles. 
 
 The order of its affinities is the fame as that given 
 for oxalic acid ; except that, according to Lavoilier, 
 the oxide of filver comes before that of mercury. 
 
 Sect. XV. Of Citric Add. 
 
 Chemists have always confidered the juice of oran- 
 ges and lemons as a peculiar acid. This juice contains 
 a quantity of mucilage and water, which render the acid 
 
 impure, and fubjed to fpontaneous decompofition. Mr mina, and metallic oxides, and forms falts known by tha 
 
 Georglus took the following method to feparate the name of citrats. 
 
 mucilage. He filled a bottle entirely with lemon-juice. Fire decompofes this acid, converting it into an aci- 
 
 corkcd it, and placed it in a cellar : in four years the dnlous phlegm, carbonic acid gas, and carbonated hy- 
 
 liquid was become as limpid as water, a quantity of inu- drogen gas. Its folution in water is alfa gradually ile- 
 
 cilage had fallen to the bottom in the form of flakes, compofed, if accefs of air be permitted. It is evident, 
 
 and a thick cruft had formed under the cork. He ex- therefore, that this acid is alfo compofed of oxygen, hy- 
 
 pofed this acid to a cold of 2^°, which froze a great drogen, and carbon. 
 
 part of the water, and left behind a ftrong and pretty Scheele faid that he could not convert it into oxa- 
 pure acid ||. It was Scheele, however, that firft point- lie acid by means of nitric acid, as he had done fe- 
 ed out a method of obtaining this acid perfedly pure, veral other acids ; but Weilrum afTums, that this con- 
 He faturated lemon-juice with lime, edulcorated the verllon may be effeftcd ; and thinks that Scheele had. 
 precipitate, which confilled of citric acid and lime, fepa- probably failed from having ufed too large a quantity of 
 rated the lime from it by diluted fulphuric acid, cleared nitric acid, by which he had proceeded beyond the con- 
 it from the fulphat of lime by repeated filtrations and verlion into oxalic acid, and had changed the citric 
 evaporation ; then evaporated it to the confidence of a acid into vinegar; and in fupport of his opinion, he 
 fyrup, and fet it by in a cool place : a quantity of cry- quoteshis own experiments: from which it appeared 
 
 tlals formed, which were pure citric acid «[[. It exifls 
 ready formed alfo in the juices of the following berries : 
 Vaccimum occicoccos, vaccirtium vitis iJo'a, prunus padus, 
 folanum dulcamara, roja can'ina *, cherries •)■ 
 
 that, by treating fixty grains of citron acid with diffe- 
 rent quantities of nitric acid, his produds were very dif- 
 ferent. Thus with 2CO grains of nitric acid he got 30 
 grains of oxalic acid; with 300 grains of nitric acid he 
 Scheele advifes the ufe of an excefs of fulphuric acid, obtained only 1 5 grains of' the oxalic acid ; and with 
 in order to enfure the feparation of all tlie lime ; but 600 grains of nitric acid no veflige appeared of the 
 according to Dize, this excefs is necelTary for another oxalic acid. On dillilling the produds of thefe experi- 
 purpofef . A quantity of mucilage ilill adheres to the ments, efpecially of the laft, he obtained vinegar mixed 
 citric acid in its combination with lime, and fulphuric with nitric acid. 
 
 acid is neceffary to decompofe this mucilage, which, as The affinities of this acid are as follows ^ : Its affinU 
 Fourcroy and Vauquelin have proved, it is capable of Lime(L), . ties. 
 doing. His proof of the prefence of mucilage is, that Barytes, § •''fe Serg- 
 when the folution of citric acid in water, which he had Strontites 11, wun and 
 obtained, was fufRciently concentrated by evaporation, Magnefia, il "or^s* 
 it aiTumed a brown colour, and even became black to- Potafs, Tranf, Edin, 
 Soda/"' 
 
 (l) Mr De Brefley places barytes before lime.
 
 ;2,6 
 
 MulJe 
 Acu'.. 
 
 * La: c/nr. 
 
 CHEMISTRY. 
 
 Part n. 
 
 •f /-/. 
 
 iTJ. 
 
 jimi de 
 Ch'im. Kxii. 
 20g. 
 
 Soda, 
 
 Ammonia, 
 
 Oxide of zinc, 
 
 I — manganefe *, 
 
 iron, 
 
 lead, 
 
 cobalt, 
 
 •^— — copper, 
 
 arfenic, 
 
 mercury, 
 
 antimony f , 
 
 filver, 
 
 gold, 
 
 platinum. 
 
 Alumina J, 
 Jargonia J ? 
 Water, 
 Alcohol, 
 
 XVI. 
 
 4'!o 
 Eifc ivery 
 of ntahc 
 acid. 
 
 481 
 Metho'l of 
 
 -■5 Ibid, 
 
 Of Malic Add. 
 
 ScHEELE difcovered a peculiar acid in the juices of 
 feveral fruits, wliich, becaule it is found nioft abundant- 
 ly in apples, has been called malic acid. 
 
 Hj obtained it by the following procefs : Saturate 
 
 ohtaiiiing the juice of apples with potafs, and add to the folution 
 
 it. acctitc of lead till no more precipitation enfues. Walh 
 
 the precipitate carefully With a fufficient quantity of 
 water ; then pour upon it diluted fulphuric acid till the 
 mixture has a perfeiSly acid talle, without any of that 
 fvvectnefs which is perceptible as long as any lead re- 
 mains rliffolved in it ; then feparate the fulphat of lead, 
 which has precipitated, by filtration, and there remains 
 
 II Sv>idijb behind pure malic acid ]|. 
 
 r'-WA '^'''^ ^'■'"^ '** contained in the berries of the ^ariifw 
 
 nils for ' •vulgaris, the famliucus nigra, the primus fpinofa, the ybr- 
 bus aucuparia, and the prunus domejiica^. 
 
 If nitric acid be diftilled with an equal quantity of 
 fugar, till the mixture affumes a brown colour (which 
 is a fii^n that all the nitric acid has been abftrafled from 
 it), this fubftance will be found of an acid tatte ; and 
 after all the oxalic acid which may have been formed 
 is feparated by lime-water, there remains another acid, 
 which may be obtained by the following procefs : Sa- 
 turate it with lime, and filter the folution ; then pour 
 upon it a quantity ot alcohol, and a coagulation takes 
 place. This coagulum is the acid combined with lime. 
 Separate it by filtration, and edulcorate it with frefli al- 
 cohol ; then diffolve it in diftilled water, and pour in 
 acetite of lead till no more precipitation enfues. The 
 precipitate is the acid combined with lead, from which 
 it may be fepaiated by diluted fulphuric acid. It pof- 
 fefTes all the properties of malic acid *. This acid, 
 therefore, may be obtained from fugar ; and it may be 
 converted into oxalic acid, by diftiUing off it the prp- 
 
 f Hfrw/aA.per quantity of nitric acid f. 
 
 fhyf. chtm. This acid bears a ftrong refemblance to the citric, but 
 differs from it in the following particulars: 
 
 1. The citric acid (hoots into fine cryftals, but this 
 aold does not eryftalllze. 
 
 2. The fait formed from the citric acid with lime Is 
 almoft Infoluble in boiUng water; whereas the fait made 
 with malic acid and the fame bafis Is readily foluble by 
 boiling water. 
 
 3. Malic acid precipitates mercury, lead, and filver, 
 from the nitrous acid, and alfo the folution of gold when 
 
 * Hid. 
 
 4S2 
 
 Its proper- 
 ties. 
 
 diluted v.ith water ; whereas citric acid docs not alter 
 any of tlufc folutions. 
 
 3. Malic acid feenis to have a lefs aflinity than citric 
 acid for lime ; lor wlien a folution of lime in the for- 
 mer acid is boiled one minute with a fait formed from 
 volatile alkali and citric acid, a decompofitlon takes 
 place, and the latter acid combines with the lime and 
 is precipitated. 
 
 The malic acid combines with alkalies, alkaline earths, 
 and alumina, and metallic oxides, and forms falls known 
 by the name of mnlats. 
 
 Its ailliilties have not yet been afcertained. 
 
 Sect. XVII. Of Laaic Acid. 
 
 If milk be kept for fome time It becomes four. The 
 acid wliich then appears in it was firft examined by 
 Schcele, and found by him to have peculiar properties. 
 It is called laQic acid. In the whey of milk this acid 
 is mixed with a little curd, fome phofphat of lime, fugar 
 of milk, and mucilage. All thefe muft be feparated 
 before the acid can be examined. Schecle accomplilhed 
 this by the following procefs : 
 
 Evaporate a quantity of four whey to an eighth part, 
 and then filtrate It: this feparates the cheeiy part. Sa- 
 turate the liquid with lime-water, and the phofphat of 
 lime precipitates. Filtrate again, and dilute the liquid 
 with three times Its own bulk of water; then let fall In- 
 to It oxalic acid, drop by drop, to precipitate the lime 
 which it has diffolved from the lime-water : then add a 
 very fmall quantity of lime-water, to fee whether too 
 much oxalic acid has been added. If there has, oxalat 
 of lime Immediately precipitates. Evaporate the folu- 
 tion to the coniiftence ot iioney, pour In a fufficient 
 quantity of alcohol, and filtrate again ; the acid pafies 
 through diffolved in the alcohol, but the fugar of milk 
 and every other fubftance remains behind. Add to the 
 folution a fmall quantity of water, and diftll with a fmall 
 heat, the alcohol paffes over, and leaves behind the ladlic 
 acid diffolved in water *. 
 
 This acid Is Incapable of cryftalllzing : when evapo- 
 rated to drynefs, It deliquefccs again in the air f. 
 
 When diftilled, water comes over firft, then a weak 
 acid refembling the tartarous, then an enipyreumatic oil 
 mixed with more of the fame acid, and laftly carbonic 
 acid and hydrogen gas — there remains behind a fmall 
 quantity of coal f . 
 
 The combinations which this acid forms with alka- 
 lies, earths, and metallic oxides, are called laHats. 
 Its affinities, according to Bergman, are as follows : 
 
 Barytes, 
 
 Potafs, 
 
 Soda, ^ 
 
 Ammonia, 
 
 Lime, 
 
 Magnefia, 
 
 Alumina, 
 
 Jargonia J ? 
 
 Metallic oxides as in fulphuric acid. 
 
 Water, 
 
 Alcohol. 
 
 Sect. XVIII. Of Sacchokaic Acid. 
 
 La(5lic 
 Acid. 
 
 483 
 'te comb;, 
 nations, 
 
 484 
 Method •! 
 
 o!ua'ninjj 
 iai5iic acid, 
 
 * Srhctli, 
 St ci/jolm 
 Trali/.ljSo. 
 t 'i!d. 
 
 485 
 
 lt= [Topei" 
 ties, 
 t 'liJ. 
 4S5 
 Ccmbina. 
 tions, 
 
 487 
 And aSu, 
 tiss. 
 
 § KauguttlK 
 jinn, de 
 Chtm. xxii. 
 208. 
 
 488 
 
 If a quantity of frefh whey of milk be filtrated, and Sugar <A 
 then evaporated by a gentle fire till It Is of the conlift- niilk, 
 ence of honey, and afterwards allowed to cool, a folid 
 
 mafs
 
 Part II. 
 
 C H E M 
 
 490 
 
 (s proper- 
 'Phi- 
 
 ■•1 
 
 Encyc, 
 Xfetbod. i. 
 90. 
 
 ScheeU. 
 
 II. 
 
 id. 
 
 tnafs is obtained. If this be dllToIved in water, clarified 
 with the white of eggs, fihratcd, and evai)orated to the 
 confillence of a fyrup, it depofites on cooling a niimbtr 
 of brilliant, white, cubic cryll.ils, which have a fweet 
 tafte, and for that reafon have been calledyufar of milk, 
 Fahriciiis Bartholet, an Italian, was the full European 
 who mentioned this fugar. He defcribed it in his En- 
 cyclopedia Hervietico dogmalica, publiflicd at Boulogiiia 
 in 1619; but it fcems to have been known in India 
 long before that period. 
 
 After Mr Scheele had obtained oxalic acid from fu- 
 gar, he wiihed to examine whether |the fugar of milk 
 would furnith the fame product. Upon tour ounces 
 of pure fugar of milk, finely powdered, he poured 12 
 ounces of diluted nitric acid, and put the mixture in a 
 large glafs retort, which he placed in a fand-bath. 
 A violent effervefcence enfuing, he was obliged to re- 
 move the retort from the fand-bath till the commotion 
 ceafed. He then continued the dillillation till the mix- 
 ture became yellow. As no cryilals appeared in the li- 
 quor remaining in the retort, after Handing two days 
 he repeated the dillillation as before, with the addition 
 of eight ounces of nitric acid, and continued the opera- 
 tion till the yellow colour, which had diiappearcd on 
 addition of the nitrous acid, returned. The liquor in 
 the retort contained a white powder, and when cold 
 was obferved to be thick. Eight ounces ot water were 
 added to dilute this liquor, which was then filtrated, 
 by which the white powder was feparated ; which being 
 edulcorated and dried, weighed 7I dr. The filtrated fo- 
 lution was evaporated to the confillence of a fyrup, and 
 again fubjefted to dillillation, with four ounces of ni- 
 tric acid as before ; after which, the liquor, when cold, 
 was obferved to contain many fniall, oblong, four cry- 
 Hals, together with iome white powder. This powder 
 being feparated, the liquor «'as again diftilled with more 
 nitric acid as before ; by which means the liquor was 
 rendered capable of yielding cryilals again ; and by one 
 dillillation more, with more nitrous acid, the whole of 
 the liquor was converted into cryilals. Thefe cryilals, 
 added together, weighed five drams ; and were found, 
 upon trial, to have the properties of the oxalic acid. 
 
 Mr Scheele next examined the properties of the white 
 powder, ami found it to be an acid of a peculiar nature ; 
 he therefore called it the aiid of fugar of milk. It is 
 now called the faccholaSic acid. 
 
 According to Scheele, it is foluble in 60 parts of its 
 weight of boiling water ; but Melfrs Hermlladt* and 
 Morveau-t- found, that boiling water only dilfolved -j^th 
 part : it depofited about 3th part on cooling in the 
 form of cryilals :(:. 
 
 The folution has an acid tafte, and reddens the infu- 
 fion of turnfole §. Its fpecific gravity, at the tempe- 
 rature of 53-7", is i,oot5 ||. 
 
 When dillilled, it meks very readily, becomes black, 
 and frothes ; a brown fait fublimes into tlie neck of the 
 retort, which has the odour of a mixture of amber and 
 benzoin, having an acid talle, eafily lolublc in alcohol. 
 
 I S T R Y. 
 
 with greater difticulty in w.iter, and burning in tlie fire 
 with a llame. There palTes into the receiver a brown li- 
 quid, having fome of this fait dilfolved in it : There re- 
 mains behind a coal *, which Hermlladt found to cim- * Sihielt, 
 tain a fmall quantity of lime. Concentrated fulphuricJi'V/. 
 acid diftilled on this fait becomes black, frothes, and 
 decompofes it f . f IJ. ,iij, 
 
 Mr Hermftadt of Berlin had made fimilar experiments 491 
 on fugar of milk at the fame time with Scheele, and with Htrmftadt 
 fimilar refults ; but he concluded that the while P"'^'-'-4,f,r;7v"it> 
 der which he obtained was nothing elfe than oxalat ofcsiftcce. 
 lime with excels of acid, as indeed Scheele himfelf did 
 at firft. After he became acquainted with Schcelc's 
 conclufions, he publiflied a paper in defence of his own 
 opinion ; but his prools are very far from eilablilhiug it, 
 or even rendering its truth probable. He acknowledges 
 himfelf, that he has not been able to decompofe this fup- 
 pofed fait : he allows that it polfefres jiroperties dillinft 
 from the oxalic acid ; but he afcribes this difference to 
 th£ lime which it contains ; yet all the lime which he- 
 could difcover in 240 grains of this fait was only 20 
 grains ; and if the alkali which he employed was a car- 
 bonat (as it probably was), thefe 20 muft be reduced 
 to n. Now Morveau has ihewn, that oxalic acid, con- 
 taining the fame quantity of lime, exhibits very different 
 properties. Befides, this acid, whatever it is when uni- 
 ted with lime, is feparated by the oxalic, and muil 
 therefore be different from it, as it would be abfurd to 
 fuppofe that an acid could difplace itfelf |:. The fac- t Metvcm, 
 choladlic acid mull therefore be confidered as a dillincl -^"'.v- 
 acid, as it poflefTes peculiar properties. ^ '' ° ' '• 
 
 Its compounds with alkalies, earths, and metallic ^g~ 
 oxides, are denominated _/i;«/;o/j/x. Its com- 
 
 Its affinities, according to Bergman, are as follows : P'^nd* ^r.d 
 
 Lime, 
 
 Barytes,. 
 
 Magnefia, 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Alumina, 
 
 JargoniaJ? ^fauyelin,. 
 
 Metallic oxides as in fu'piuric aciJ,'^""''' 
 
 Water, 
 
 Alcohol. 
 
 * Chim. xxii»> 
 
 20 8. 
 
 493 
 
 Sect. XIX. Of Gallic /Icid. 
 
 There is an excrefccnoe, known by the name of wr/Z-Nut-'alW^. 
 gall, which grows on fome fpecles of oaks. This furv. 
 Ibance contains a peculiar acid, called from thatcircum- 
 {\.Sincit gallic acid, the properties of which were firlt ex- 
 amined with attention by. the commlflioners of the aca- 
 demy of Dijon ;. and the refult of their experiments 
 was publiHied in 1777, in the third volume of their Ele- 
 ments of Chemlllry. In thefe experiments, hou-ever, 
 they employed the infufion of galls, In which the acid 
 is combined with the tanning principle (m). It was 
 referved for Scheele to obtain it in a itate of purity. 
 
 He 
 
 (m) a fubftance lately difcovered by French chemlfts, which exifts alfo in oakbnrk, and aveiy other body 
 which may be fubilituted for that bark in the operation of tanning. It reTembles the relins in many projjertics ;; 
 but Its dillingulfhing property is tb^t of forming with glue a compound Infoluble In water. When a little of< 
 tfee decoftlon of glue is dropped into an Infufion of nut-galls, a white curdy precipitate is inflantly feen : This; 
 is the tanning principle combined with glue. The name tanning principle has been applied to it, becaufe tamiingi 
 eonfills in corabinipg this principle with^X-inf, by which they are coriverted into leather.
 
 tid. 
 
 328 C H F. M 
 
 Gallic He oSfcrvcJ, in an I'nfuilon of galls made with cold 
 
 , ^" ' water, a fcdimcnt, which proved on examination to 
 ^g. have a cryllalline form and an acid tafte. By letting 
 Difcovery an infufiun of galls remain a long time expofed to the 
 ot gallic a- air, and removing now and then the mouldy (1-cin whith 
 formed on Its fnrface, a large quantity of this lediment 
 was obtained ; which being edulcorated with cold wa- 
 ter, rediflolved in hotw;itcr, filtrated, and evaporated very 
 »StoM(ilm (]o„-ly^ yielded an acid fait in cryftals as fine as fand*. 
 itS6 There is a (hortcr method of obtaining this acid in 
 
 4^5 a ftiU purer ftate than Scheelc obtained it. 
 Method of Poui" fulphuric ether on a quantity of powdered galls, 
 obtaining g^j ^Uow it to remain a few hours ; by which time it 
 becomes coloured. Put this tinfture into a retort, and 
 dlPuil off the ether with a fmall heat. The rtfiduum 
 poiTcffes the colour and brittlenefs of a refin, and has 
 all the charafters of Rouelle's refiduous-extraft ; it does 
 not attraft moillure from the atmofphere. Diffblve it 
 in its own weight of water, and add fulphuric acid, 
 drop by drop, till the liquor has become of a manifeilly 
 acid taile. It caufes a white precipitate, which be- 
 comes coloured, and is immediately redilTolved. At the 
 €nd of fome hours a rcfinous matter will have precipi- 
 tated. Decant off the fluid, dilute it with half its weight 
 of water, filtrate ^ii.i evaporate it to |ths in a moderate 
 heat ; add pure barytes till the liquor is no longer ca- 
 pable of decompofmg muviat of harytes ; tlien filtrate 
 it again ; and on evaporation in a moderate heat fmall 
 white prifmatic cryftals of gallic acid are formed on the 
 
 Di-'e 7o'J' '''^" "f '■'"= ^"^''^ t • 
 
 deFb/r.'"'' It appe'iirs from the experiments of Dcyeux, that the 
 
 Dec.'i-Qt. fubilance extrafted from nut-galls by ether does not dif- 
 t y^rn.iie^ fer much from the extraiSl by water J. Probably, then, 
 the only reafon fur employing ether is the imall heat 
 necelFary for evaporating it. 
 
 There is ftill another method of obtaining this acid. 
 Diftil nut-galls In a ftrong heat, a wliite fubftance fu- 
 blimes, which cryftallizes in the form of needles : This 
 is gallic acid. If the cryftals are impure, they may be 
 purified by a feeond fabiimation : but the heat niuft; 
 not be too violent, otherwife the cryftals will melt in. 
 to a brown mafs §. This procefs was difcovered by 
 Scheele. 
 
 But the moft elegant method of obtaining gallic acid 
 is that of Mr Prouil. When a folution of muriat of tin 
 is poured into an infufion of nut-galls, a copious yellow 
 precipitate is inftantly formed, confifting of Xhe tanning 
 principle, combined with the oxide of tin. After di- 
 luting the liquid with a fufficient quantity of water to 
 feparate any portion of this precipitate which the acids 
 might hold in folution, the precipitate Is to be fepara- 
 ted by filtration. The liquid contains gallic acid, mu- 
 riatic acid, and muriat of tin. To feparate the tin, a 
 quantity of fulphurated hydrogen gas is to be mixed 
 with the liquid. Sulphuret of cxide ot tin is precipi- 
 tated under the form of a brown powder. The liquid 
 18 then to be expofed for fome days to the light, cover- 
 ed with paper, till the fuperfluous fulphurated hydrogen 
 gas exhales. After this, it is to be evaporated to the 
 proper degree of concentration, and put by to cool. 
 Cryftals of gallic acid are depofiled. Thefe are to be 
 feparated by filtration, and wafhed with a little cold 
 water. The evaporation of the reft of the liquid is to 
 5 HiJ. Lg repeated till all the eallie acid is obtained from it'll. 
 
 Cfjisi, xvii. 
 8. 
 
 § nij. 
 496 
 
 Prouft's 
 method. 
 
 I S T R Y. Part 11. 
 
 The gallic acid thus obtaired has a very acid tafte, Gallic 
 and reddens vegetable colours. It is foluble In i|- parts ^' - ''^' 
 of boiling water, and in 12 parts of water at the tem- 
 perature of the atmofphere. Alcohol difTolves one-It« (ironcr- 
 fourth of its weight of this acid at the temperature ofii-i. 
 the atmofphere. When boiling hot it diflblvea a quan- 
 tity equal to its own weight. 
 
 When placed upon burning coals, gallic acid takes 
 fire, and at the fame time diffufes a very ftrong odour, 
 which has fomething aromatic in it. When ftrongly 
 heated, it melts, bolls, becomes black, isdiflipated, and 
 leaves a quantity of charcoal behind it. When dillil- 
 led, a quantity of oxygen g is is difergaged, an acid li- 
 quor is found in the receiver, with fome gallic acid not 
 decompofed, and there remains In the retort a quantity 
 of carbon. If what has paiTed into the receiver be 
 again dlftllled, more oxygen gas is obtained, fome gallic 
 acid ftill fublimes, and a quantity of carbon remains in 
 the retort. By repeated diftillations the whole of the 
 acid may be decomjiofed. This decompofition may be 
 more eafily accomplKhed by diftlUIng repeatedly a folu- Ji 
 
 tlon of gallic acid In water. The produfts are oxygen 9 
 
 gas, charcoal, and an acid liquor. 45S 
 
 From thefe experiments, JMr Deyenx, who perform-''^ i:ompoG» 
 ed them, has concluded, that gallic acid Is compofed of"°"' 
 oxygen, and a much larger proportion of carbon than 
 enters into the compofition of carbonic acid. But this 
 conclufion is not warranted by the analyfis ; for Mr 
 Deyeux did not find that the quantity of oxygen gas 
 and carbon obtained was equal to that of the gallic acid 
 decompofed :. and in the acid liquor which came over, 
 there evidently exifted a quantity of water, which 
 doubtlefs was formed during the diftillation. Scheele, 
 by treating gallic acid with nitric acid in the ufual man- 
 ner, converted It into oxalic acid. Now it Is certain 
 that oxalic acid contains hydrogen as well as carbon. 
 It cannot be doubted, then, that gallic acid is compo- 
 fed of oxygen, hydrogen, and carbon, in proportions 
 not yet alcertaiiied. But Mr Deyeux has proved, that 
 the quantity of carbon is very great, compared with 
 that of the hydrogen. 
 
 Gallic acid combines with alkalies, earths, and me- 
 tallic oxides, and forms compounds known by the name 
 ol a allots. 
 
 Its affinities have not yet teen determined; but oxide 
 of iron ieems to have a ftronger affinity for it than for 
 any other fubftance ; for gallic acid is capable of taking 
 it from every other acid. In confequence of this pro- 
 perty, the Infufion of galls is employed to deteA the 
 prtfence of iron In any liquid. As foon as it Is poured 
 in, it iron be prefent, a black or purple colour is pro- 
 duced. 
 
 4Q9 
 
 Sect. XX. Of Benzoic act J. 
 
 Benzoin or benjamin (as it is fometimes called) Is aB^,[^2(,i^, 
 kind of refin brought from the Eaft Indies ; obtained, 
 according to Dr Dryander, from the ftyrax benzoe, a 
 tree which grows In the ifland of Sujtiatra This fub- 
 ftance confifts partly of a peculiar acid, defcrlbed as 
 long ago as i6c8 by Blalfe de Vigenere, in his Trea- 
 tife on Fire and Salt, under the name oijloivers of ben- 
 zoin, becaufe it was obtained by fubllniation. This 
 acid, which is now called the benzoic acid, may be fu- 
 blimcd from benzoin by heat ; or it may be obtained by j 
 
 Scheele's p
 
 c\A. 
 
 CHEMISTRY.' 329 
 
 It is obtained by the fullowiiig proccfs : Fill a retort Camphoric 
 half way witli powdered amber, and cover the powder '^^'^- 
 witli a quantity of dry faiid ; lute on a receiver, and ' 
 diftil in a fand-batli without employing too much heat. Method of 
 There palfes over lirft an inlipid phlej^in ; then a weak'ih'aining 
 fulion of violets ; but it reddens that of turnfole, tfpe- acid, which, according to Scluele, is the acetous * ; then'"'''"'' 
 
 Part ir. 
 
 Succinic Seheele's proeefs, which has been defcribed in the ar- 
 
 ^^ ''^ ^ticie Chemistry, Encycl. 
 
 ' Benzoic acid has little or none of the peculiar odour 
 
 Propertios which diilinguiflies benzoin. Its tafte is not acid, but 
 
 of benzoic fweetilh, and very pungent*. It hardly affcfts the in- 
 
 * °'JJ,y^"'cially if that infulion be hot f . Heat volatilizes this 
 
 thuj. Cbim. acid, and makes it give out a ftrong odour, which ex- 
 
 i. 44. cites coughing. When expofed to the heat of the 
 
 + Licbim- blow-pipe in a fiK-er fpoon, it melts, becomes as fluid 
 
 ■r""' as water, and evaporates without taking fire. It only 
 
 burns when in contact with flame, and then it leaves 
 
 no rellJuum behind. When thrown upon burning coals, 
 
 it rifes in a white fnioke. When allowed to cool alter 
 
 being melted, it hardens, and a radiated crull forms on 
 
 its furfacej. 
 
 It fuffers no other alteration In the air than lofing 
 the little of the odour of benzoin which remained to 
 
 Cold water dlfTolves no fenfible quantity of it ; but 
 it is foluble enough in hot water : 480 grains of boil- 
 ing water diflblve 20 grains of it ; 19 of thefe are de- 
 polited, when the water cools, in long, flender, flat, fea- 
 ther-like cryllals ||. 
 
 Concentrated fulphuric acid diflolves it without heat 
 or any other change except becoming fomewhat brown: 
 when water is poured into the folution, the benzoic acid 
 feparates and coagulates on the furface without any al- 
 teration ^. Nitric acid prefents precifely the fame phe- 
 nomena, and alfo the fulphurous and nitrous acids. Nei- 
 ther the muriatic, the oxy-muriatic, nor the phofphoric 
 acids diflblve it. The acetous, formic, and febacic acidj, 
 when hot, diflblve it precifely as water does ; but it 
 cryttallizes again when thefe acids cool *. 
 
 Alcohol diflolves it copioufly, and lets it fall on the 
 addition ot water -j-. 
 
 Little is known refpeAing its bafe. 
 It combines with alkalies, eartlis, and metallic oxides, 
 nations and and forms falts known by the name of ieiizoiits. 
 
 Its aiiinnies, from the experiments ot Iromniidort, 
 appear to be as follows : 
 
 White oxide of arfenic, 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Barytes, 
 
 Lime, 
 
 Magnefia, 
 
 Alumina, 
 
 Jargon ia:j: ? 
 
 Water, 
 
 Alcohol, 
 
 Sect. XXI. 0/ Succinic /Icid. 
 
 Amber is a well-known brown, tranfparent, inflam- 
 mable body, pretty hard, and fufceptible of polifli, 
 found at fome depth in the earth, and on the fea-coaft 
 of feveral countries. It was in high eftimation among 
 the ancients both as an ornament and a medicine. — 
 When this fubftance is diftilled, a volatile fait is obtain- 
 ed, which is mentioned by Agricola under the name of 
 
 fait of amber ; but its nature was long unknown. Boyle 
 was the firft; who difcovered that it was an acid J. From 
 
 fuccinum, the Latin name of amber, this acid has recei- 
 ved the appellation oifuccinic acid. 
 SUPPL. Voi,. I. Part I, 
 
 X IJtm. 
 
 uu. 
 
 II Lichtai- 
 Jit'ln. 
 
 \Id. 
 
 m Id. 
 
 501 
 
 Irs n,m\- 
 
 affinities. 
 
 t Va:tque- 
 /m, Ann. de 
 Chim. xxii. 
 308. 
 
 501 
 
 Amber. 
 
 $ "Boyle n~ 
 bridged by 
 SbazVf ill, 
 
 3h- 
 
 the fuecinic acid attaches itfelf to the neck of the re-.w' 
 tort ; and it tlie diltillation be contmued, there comes a-o/,, «, 
 over at lall a thick brown oil, which has an acid talle. Scbegcr. 
 
 Tiie fuecinic acid is at firll mixed with a quantity of 
 oil. Perhaps the bell method of purifying it is that 
 recommended by Pott, to diflblve it in hot water, and 
 to put upon the filter a little cotton, previoufly moil- 
 tcned with oil of amber ; this fubftance retains moft of 
 the oil, and aflows the folution to pafs clear. The 
 acid is then to be cryftallized by a gentle evapora- 
 tion. And this procefs is to be repeated till the acid 504 
 be quite pure. The cryllals are white, fliining, and Its propcr- 
 of a foliated triangular prifmatic form: they have an""^'i 
 acid tafte, but are not corrofive : they redden tinfture 
 of turnfole, but have little efft'dl on that of violets. 
 
 They fjblime when expuled to a confiderable heat, 
 but not at tiie heat of a water-bath. In a fand bath 
 they melt, and then fublime and condenfe in the upper 
 part of the veflTel ; but the coal which remains fliews 
 that they are partly decompofed f . | p„ii. 
 
 One part of this acid diifolves in 96 parts of water at 
 the temperature of 50", according to Spielman J, in 24)/,^ Chem. 
 parts at the temperature of 5 2", and in 2 parts ot water at j xii. 
 the temperature of 21 a', according to Stockar de Neu- 
 fornf; but the greatelt part cryftallizes as the water » 73« S»5«. 
 cools. According to Roux, however, it ftill retains morco. 
 of the acid than cold water is capable pf diflblviug ||. u Morveau 
 
 240 grains of boiling alcohol dilFolve i 77 ol tin's acid ; /''/i/. p. 72. 
 but cryftals again flioot as the iolution cools ^. \ IVenzel. 
 
 The combinations of this acid arc ciWiid fuccinats . 5'5 
 
 Its component parts are Hill unkiiov.u. Combma. 
 
 T^ fj. . . • ,. - , f. ,, ■ tjon.s and 
 
 Its ailiiatie.s, accordmg to Morveau, are as toUows i 
 
 Barytcs, 
 
 Lime, 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Magnefia, 
 
 Alumina, 
 
 Jargonia * ? 
 
 Metallic oxides as m fulphuric acid, 
 
 Water, 
 
 Alcohol. 
 
 S E CT. XX II. Of Camphoric Acid. 
 
 Camphor, is a well-known white cryftalline fubftance, Camphor, 
 of a ftrong tafte and frnell, obtained from a fpecies of 
 laurel in the Eaft Indies ; and Mr Prouft has fliewn 
 that feveral volatile oils contain a confiderable quantity 
 of it f . It is fo volatile, that it cannot be melted in f /fm. </« 
 open vefTels, and fo inflammable that it burns even on Cbim, iv. 
 the furface of water. *79' 
 
 When camphor is fet on fire in contaft with oxygen 
 gas, it burns with a very brilliant flame ; much caloric 
 is difengaged, water is formed, the inner furface of the 
 veflel is covered with a black matter, which is undoubt- 
 edly carbon, and a quantity of carbonic acid gas is alfo 
 produced J. Hence it follows, that it is compofed offZaGrawf, 
 hydrogen and carbon, at leaft principally. '<<</. xiiii. 
 
 T t If«". 
 
 affin 
 
 * Viiu^ue.. 
 lin^ Ann' as 
 Chim, uiu 
 
 lOii. 
 
 iof
 
 t^aniphoric 
 Add. 
 
 C H E M I 
 
 If one part of camphor and fix parts of piilverifed 
 clay be mixed together, by mean? of alcohol, in a mor- 
 tar, the mixture made up into balls, and when dry put 
 into a retort, nnd diftilled by a moderate heat — a quan- 
 tity of oil comes over, and there remains in the retort 
 a black fubftance, v.'hich confifts of the clay intimately 
 mixed with a quantity of carbon. If the fire be not 
 cautiouflv managed, a quantity of camphor alfo fub- 
 limes. By this procefs camphor is decompounded, and 
 feparated into oil and carbon. 
 
 12 2,2+S parts of camphor 
 
 produced 45,856 parts of oil 
 and 30,571 of carbon. 
 
 S T R Y. 
 
 Part ir. 
 
 * Ann. de 
 Cbim. xxiii. 
 IS." 
 
 Oi! of cam. 
 phor. 
 
 f./iU:i59. 
 
 308 
 Camphoric 
 acid. 
 ^ Kofegar- 
 
 fiioray &c> 
 
 i Ann, Je 
 Cbim. iUd. 
 
 Its proper- 
 tics. 
 
 H KofegaT' 
 Un. 
 ^J.aCrangt. 
 
 * Kofi:gir. 
 
 tn. 
 
 f bouillon 
 La G range y 
 jAan. ds 
 Chim. iivii, 
 40. 
 
 Total 7(^,427 
 Lofs 45,821 
 
 Carbonated hydrogen gas and carbonic acid were 
 alfo formed *. 
 
 The oil obtained has the following properties : 
 
 It has a fharp cauftic talle, and leaves upon the 
 tongue a fenfe of coldnefs. It has an aromatic odour, 
 approaching to that of thyme or rofemary. Its colour 
 is a golden yellow. 
 
 When expofed to the air, it partly evaporates, and 
 there remains a thick brown matter with a fharp bit- 
 terifli tafte, which at laft alfo evaporates. 
 
 With alkalies, it forms a foap, which poffeffes all the 
 charafters of foaps made with volatile oils. 
 
 Alcohol didblves it entirely ; and when water is add- 
 ed to the folution it becomes milky, but no precipitate 
 is produced \. 
 
 Thefe properties fhew that this is a volatile oil, and 
 confequently it is probable that camphor is compofed 
 of volatile oil and carbon. 
 
 Mr Kofegarten, by dirtilling nitric acid off camphor 
 ei^ht times Tucceffively, obtained an acid in cryftalsj, to 
 which the name of camphoric acid has been given. 
 
 His experiments have been repeated by Mr Bouillon 
 La Grange. He mixed together 122,284 parts of cam- 
 phor with 4^59, 1 36 parts of nitric acid of the fpecific 
 gravity 1,33, and diftilled them. Much nitrous and car- 
 bonic acid gas were difengaged, and part of the cam- 
 phor vyas fublimed ; but part was converted into an 
 acid. He returned the fublimed camphor into the re- 
 tort, poured on it the fame quantity of nitric acid as at 
 firft, and diftilled again. This procefs he repeated till 
 the whole camphor was acidified §. The quantity of 
 camphoric acid obtained amounted to 53,498. The 
 quantity of nitric acid was 21 14,538. 
 
 Camphoric acid thus obtained is in fnow-white cry- 
 ftals, of the form of patallelopipedons||. 
 
 Thefe ci7llals efflorefce in the air^. 
 
 Camphoric acid has a flightly acid bitter tafte, and 
 fmell like that of fafFron. 
 
 It reddens vegetable colours. 
 
 It is foluble in 200 parts of cold water, according to 
 -Kofegarten ; I'l 96 parts of water at the temperature 
 of 60°, according to La Grange. Boiling water dif- 
 folves Tifth of its weight *. 
 
 According to Kofegarten, it is iufoluble in alcohol ; 
 according to La Grange, alcoiiol dilfolves it, and when 
 the folution is left in contadl with the air of the atmo- 
 fphere, the acid cryflaliizes. It is not precipitated from 
 its folution in alcohol by the addition of water f. 
 
 When this acid is placed on ignited coals, it emits a 
 
 denfe aromatic fume, and is entirely diflipated. By a 
 gentler heat, it melts, and is fublimed. If it be put 
 into a heat'Cd porcelain tube, and oxygen gas be patfed 
 through it, the acid docs not undergo any change, but 
 is fublimed. 
 
 By mere dilHllation, it firft. melts and then fublimes ; 
 by which procels its properties are in fome refpedt 
 changed. It no longer reddens the tinfture of turnfole, 
 but acquires a brilk aromatic fmell ; its tafte becomes 
 lefs penetrating, and it is no longer foluble either in 
 water or the fulphuric and muriatic acids. Heated ni- 
 tric acid turns it yellow and dilfolves it. Alcohol like- 
 wife diffolves it ; and if this folution be left in contaft 
 with the air of the atmofphere, it cryftallizes. 
 
 Camphoric acid docs not produce any change in ful- 
 phur ; alcohol and the mineral acids totally dilfolve it ; 
 and fo likewife do the volatile and the fat oils. 
 
 Camphoric acid does not precipitate lime from lime- 
 water. It produces no change on the folution of indi- 
 go in fulphuric acid. jro 
 
 It forms combinations with the alkalies, earths, and'tscombi- 
 metallic oxides, which are called camphorats. nations and 
 
 Its affinities, as far as afcertained by La Grange, are ^ 
 
 as follows * 
 
 Seci 
 
 Lime, 
 
 Potafs, 
 
 Soda, 
 
 Barytes, 
 
 Ammonia, 
 
 Alumina, 
 
 Magnefia. 
 
 XXIII. 
 
 Ann. de 
 Ciim.jixyil, 
 II. 
 
 5'I 
 
 Of Suberic Acid. 
 
 Cork, a fubftance too well known to require any pif^^^gr- 
 defcription, is the bark of a tree which bears the fameof fuberic 
 name. By means of nitric acid, BrugnatcUi converted *cid. 
 it into an acidf, which has been called the/uberic acid,f Cnll't 
 from Suber, the Latin name of the cork-tree. Several ^^"iii/i, 
 chemifts affirmed that this acid was the oxalic, becaufe 'V^?- 
 it pofleffed feveral properties in common with it. Thefe 
 aftertions induced Bouillon la Grange to undertake a fet 
 of experiments on fuberic acid. Thefe experiments, 
 which have been publiihed in the 2^d volume of the 
 Annales de Chimie, completely cllablifh the peculiar na- 
 ture of fuberic acid, by (hewing that it polfeffes proper- 
 ties diff^erent from thofe of every otiier acid. 
 
 To prepare it, a quantity of found cork grated down Method of 
 fmall is to be put into a retort, fix times its weight of preparing 
 nitric acid of the ipecific gravity 1,261 poured upon'"^- 
 it, and the mixture diftilled by means of a gentle heat. 
 Red vapours are immediately difcharged; the cork fwells 
 up and becomes yellow, and as the diftillation advances, 
 it finks to the bottom, and its furface remains frothy. 
 If that froth does not form properly, it is a proof that 
 fome part of the cork has efcaped the action ot the acid. 
 In that cafe, after the diftillation is pretty far advanced,, 
 the acid wliich has paffed into the receiver is to be 
 poured back into the retort, and the diftillation conti- 
 nued till no more red vapours can be perceived ; and 
 then the retort is to be immediately taken out of the 
 fand-bath, otherwife its contents would become black 
 and adhere to it. While the matter contained in the 
 retort is hot, it is to be poured into a glafs veftcl, pla- 
 ced upon a faud-bath over a gentle fire, and coaftantly 
 llirred with a glafs rod. By this means it becomes 
 
 gradually
 
 Part ir. 
 
 CHEMISTRY. 
 
 Suberic gradually thick. As foon as ivhite vapours, exciting 
 '^'^i '• a tickling in the throat, begin to difengagc thcmfelves, 
 "~"^' the vcfTtl is removed from the bath, and the mafs con- 
 tinually ftirred till it is almolt cold. 
 
 By this means an orange-coloured mafs is obtained 
 of the confidence of honey, of a ftrong and Iharp odour 
 while hot, but having a peculiar aromatic fmell when 
 cold. 
 
 On this mafs twice its weight of boiling water is to 
 be poured, and heat applied till it becomes liquid ; and 
 then that part of it which is infoluble in water is to be 
 feparated by tiltration (n). The filtered liquor be- 
 comes muddy ; on cooling it depofites a powdery fedi- 
 ment, and a thin pellicle forms on its furface. The f^- 
 diment is to be feparated by filtration, and the liquor 
 reduced to a dry mafs by evaporating in a gentle heat. 
 This mafs is fuberlc add. It is ftiil a little coloured, 
 owing to fome accidental mixture, from which it may 
 be purified either by faturating it with potafs and pre- 
 cipitating it by means of an acid, or by boiling it along 
 with charcoal powder. 
 
 Suberic acid thus obtained is not cryftallizable, but 
 when precipitated from potafs by an acid, it affumes the 
 form of a powder ; when obtained by evaporation it 
 forms thin irregular pellicles. 
 
 Its tafte is acid and flightly bitter ; and when diffol- 
 ved in a fmall quantity of boiling water it adls upon the 
 throat, and excites coughing. 
 
 It reddens vegetable blues ; and when dropped into 
 a folution of indigo in fulphuric acid {^liquid blue, as it 
 is called in this country), it changes the colour of the 
 folution, and renders it green. 
 
 Water at the temperature of 60° or even 70* diflblves 
 
 only 
 
 part of its weight of fuberic acid, and if the 
 
 Its proper- 
 ties. 
 
 ■57'6 
 acid be very pure, only -rjjth part : boiling water, oji 
 the contrary, diffolves half its weight of it. 
 
 When expofed to the air, it attrafts moifture, efpe- 
 cially if it be impure. 
 
 When expofed to the light of day, it becomes at lall 
 brown ; and tliis effect, is produced much fooner by the 
 dircA rays of the fun. 
 
 When heated in a matrafs, the acid fublimes, and the 
 infide ot the glafs is furroundcd with zones of different 
 colours. If the fublimation he flopped at the proper 
 time, the acid is obtained on the fides of the vefTel in 
 fmall points formed of concentric circles. When ex- 
 pofed to the heat of the blow-pipe on a fpoon of pla- 
 tinum, it firft melts, then becomes pulverulent, and at 
 lalt fublimes entirely with a fmell refembling that of fe- 
 bacic acid (o). 
 
 It is not altered by oxygen gas : — the other acids do 
 not diflblve it completely. Alcohol developes an aro- 
 matic odour, and an ether may be obtained by means 
 of this acid. 
 
 It converts the blue colour of nitrat Sf copper to a 
 green ; the fulphat of copper alfo to a geen; green ful- 
 phat of iron to a deep yellow ; and fulphat of zinc to 
 a golden yellow (p). 
 
 It has no adtion cither on platinum, gold, or nickel ; I's adion 
 but it oxidates filver, mercury, copper, lead, tin, iron,"" "'*^^'' 
 bifmuth, arfenic, cobalt, zinc, antimony, manganefc, and 
 molybdenum. 
 
 With alkalies, earths, and metallic oxides, it forms 
 compounds known by the name oi fuberats. 
 
 Its affinities are as follows (q^) : 
 
 T t 2 Barytes 
 
 5'4 
 
 Itsallinicies, 
 
 (n) When this fubftance is put into a matrafs, water poured on it, and heat applied, it melts ; and when the 
 velfel Is taken from the fire and allowed to cool, one part of it, which is of the confiftence of wax, fwims on the 
 furface of the water, and another part precipitates to the bottom of the vcffel, and afTumes the appearance of a 
 whitifh magma. When this magma is feparated by filtration, and wallied and dried, a white taftelefs powder is 
 obtained, mixed with ligneous threads, foluble in acids and alkalies, 
 
 (o) An acid which (hall be afterwards defcribed. 
 
 (p) Owing perhaps to the prefence of a little iron in the fulphat. 
 
 (,0 The place which the fuberic acid occupies in the affinities of the alkalies, earths, and metallic oxides, as 
 far as this fubjecl has been invelligated by Bouillon La Grange, will appear by the following Tables 4 
 
 Potass. Soda. Barytes. Lime. 
 
 Sulphuric acid, 
 
 Sulphuric acid, 
 
 Sulphuric acid. 
 
 Oxalic acid. 
 
 Nitric, 
 
 Nitric, 
 
 Oxalic, 
 
 Sulphuric, 
 
 Muriatic, 
 
 Muriatic, 
 
 « » * 
 
 # * • 
 
 Suberic. 
 
 Suberic. 
 
 Muriatic, 
 
 Muriatic, 
 
 
 
 Suberic. 
 
 Suberic. 
 
 Alumina. 
 
 Oxide of Tin. 
 
 Oxide of Silver. 
 
 Magnesia as lime. 
 
 
 
 
 Sulphuric acid, 
 
 * « # 
 
 
 
 Oxide of Molybdenum. 
 
 # * * 
 
 Muriatic, 
 Suberic. 
 
 Muriatic, 
 # « * 
 
 
 Oxalic, 
 
 Suberic acid. 
 
 Suberic. 
 
 
 Sulphuric, 
 
 
 
 Oxide of Lead. 
 
 Suberic. 
 
 Oxide of Antimony. 
 
 Oxide of Mercury. 
 
 
 Oxide of Copper. 
 
 
 
 * « * 
 
 % ^ % 
 
 
 
 Sebacic acid, 
 
 Muriatic, 
 
 
 Muriatic, 
 Siiheric, 
 
 • * • 
 
 Suberic. 
 
 * * « 
 
 Nitric, 
 
 
 Sulphuric, 
 
 Manganese the fame. 
 
 Suberic. 
 
 
 Suberic. 
 
 
 OXIDK
 
 * Ann, Je 
 44. 
 
 516 
 
 Itscompofi- 
 (inn. 
 
 j\ 1 ineraiogy 
 of Shetland 
 and Arran^ 
 p. 167. 
 
 Difcovery 
 of white 
 lac. 
 
 C H E M I 
 
 Barytes, 
 
 Potafs, 
 
 Soda, 
 
 Lime, 
 
 Ammonia, 
 
 Magncfia, 
 
 Alumina *. 
 Mr Bouillon La Grange, to whom we are incl-bted 
 for all the fafts relative to this acid, fuppofes that it is 
 compofed of oxygen, hydrogen, and carbon : but Mr 
 Jaraefon, in conlequence of the refult of a feries of ex- 
 periments which he made on charcoal, has been led to 
 fufpeft that it confifts entirely t)f carbon and oxygen. 
 He found, that by the atlion of nitric acid upon char- 
 coal, a brown, bitter, dcllquelcent mafs was formed, 
 foluble in water, alcohol, and alkalies, and which emit- 
 ted, particularly when heated, a very fragrant odour. 
 This matter was more or lefs foluble in water according 
 to the time that it had been expofed to the action of 
 the acid. When the nitric acid ufed was concentrated, 
 and confiderable in quantity, part of the charcoal was 
 converted into an acid, which pofiefTed the characters 
 of the fubericf . 
 
 Thefe fafts are curious, and may extend our know- 
 ledge of the nature of vegetable acids, but they are in- 
 fufScient to prove the abfence of hydrogen in fuberic 
 acid, becaufe charcoal cannot eafily be procured perfeft- 
 ly free from hydrogen, and becaufe feveral of the pro- 
 perties of fuberic acid indicate the prefence of hydrogen 
 in it, its becoming bro^vn, for inftance, when expofed 
 to the light. Mr Jamefon has obferved, that the acid 
 which exifts ready formed in peat poffeffes the proper- 
 ties of fuberic acid. 
 
 Sect. XXIV. Of Laccic Jcid. 
 
 About the year 1786, Dr Anderfon of Madras men- 
 tioned, in a letter to the governor and council of that 
 place, that nells of infefts, refembling fmall cowry (hells, 
 had been brought to him from the woods by the na- 
 tives, who eat them with avidity. Thefe fuppofcd nefts 
 he foon afterwards difcoveredto be the coverings of the 
 females of an undefcribed fpccies of coccus, which he 
 fhortly found means to propagate with great facility on 
 feveral of the trees and flirubs growing in his neigh- 
 bourhood (r). 
 
 On examining this fubftance, which he called 'white 
 lac, he obferved in it a very confiderable refemblance 
 to bees wax ; he noticed alfo, that the animal which 
 fecretes it provides itfelf by fome means or other with 
 a fraall quantity of honey, refembling that produced by 
 our bees ; and in one of his letters he complains, that 
 
 l.accic 
 Acid. 
 
 5IS 
 
 S T R Y. Part II. 
 
 the children whom he employed to gather it were 
 tempted by its fweetnefs to eat fo much of it as mate- 
 rially to reduce the produce of his crop. Small quan- 
 tities of this matter were fent into Europe in 1789, 
 both in its natural ftate and melted into cakes ; and in 
 1793 Dr Pearfon, at the requell of Sir Jofeph Banks, 
 undertook a chemical examination of its qualities, and 
 his experiments were publiflied in the Philofophical 
 TranfaC\ions for 1794. 
 
 A piece of white lac, from 3 to 15 grains in weight, it/^'.jj.fig, 
 is probably produced by each infeft. Thefe pieces are 
 of a grey colour, opaque, rough, and roundifh. When 
 white lac was purified by being ftraincd through muf. 
 lin, it was of a brown colour, brittle, hard, and had a 
 bitteridi tafte. It melted in alcohol, and in water of 
 the temperature of 145^. In many of its properties it 
 refembles bees wax, though it differs in others ; and 
 Dr Pearfon fuppofes that both fubftances are compofed 
 of the fame ingredients, but in different proportions. 
 
 Two thoufand grains of white lac were expofed in 
 fuch a degree of heat as was juft fufficient to melt 
 them. As they grew foft and fluid, there oozed out 
 ^50 grains of a reddifh watery liquid, which (melled 
 like newly baken bread (s). To this liquid Dr Pearfon 
 has given the name of lacc'ic acid* . * Pnr/ont 
 
 It pofTefles the following properties : Trunjl. </ 
 
 It turns paper ftained with turnfole to a red colour, j^j^^ wT 
 
 After being filtered, it has a (lightly faltifh tafte vi'ithturc. 
 bitternefs, but is not at aU four. 519 
 
 When heated, it fmells precifelv like newly baken hot^J;^'^';''^' 
 bread. 
 
 On ftanding, it grows fomewhat turbid, and depo- 
 fites a fmall quantity of fediment. 
 
 Its fpecific gravity at the temperature of 60° is 
 i>=25. 
 
 A little of It having been evaporated till it grew very 
 turbid, aflForded on ftanding fmall needle-fhaped cryftal& 
 in mucilaginous matter. 
 
 Two hundred and fifty grains of it were poured into a 
 very fmall retort and diftilled. As the liquor grew warm, 
 mucilage-like clouds appeared ; but as the heat increa- 
 fed they difappeared again. At the temperature of 
 200°, the liquor diftilled over very faft : A fmall quan- 
 tity of extraftive matter remained behind. The diftil- 
 led liquor while hot fmelled like newly baken bread, and 
 was perfeftly tranfparent and yellowidi. A (hred of 
 paper ftained with turnfole, which had been put into 
 the receiver, was not reddened ; nor did another which 
 had been immerfed in a folution of fulphat of iron, and 
 alfo placed in the receiver, turn to a blue colour upon 
 being moiftened with the folution of potafs (t). 
 
 About 
 
 acid. 
 
 Oxide of Iron. 
 
 Oxide of Bismuth. 
 
 Oxide of Arsenic 
 
 *♦• *•» »«# 
 
 Sulphuric, Muriatic, Nitric acid, 
 
 Suberic. Suberic. Suberic. 
 
 Cobalt and Zinc the fame with arfenic. 
 (r) The Chinefe colleft a kind of wax, which they call pe-la, from a coccus, depofited for the purpofe of 
 breeding on feveral (hrubs, and manage it exactly as the Mexicans manage the cochineal infeft. It was the 
 knowledge of this that induced Dr Anderfon to attempt to propagate his infedl. 
 
 (s) The fame liquid appears on prelfing the crude lac between the fingers 5 and we are told, that when newly 
 gathered it is replete with juice. 
 
 (t) A proof that the acid was not the pruiEc.
 
 Partir. 
 
 Laccic 
 Acid. 
 
 CHEMISTRY. 
 
 About one hundred grains of lliis dillilled liquM be- 
 ing evaporated till it grew turbid, after being fet by 
 fur a night, afforded acicular cryllals, which under a 
 lens appeared in a group not unlike the umbel ot parf- 
 ley. The whole of them did not amount to tile quar- 
 ter of a grain. They tailed only bitterirti. 
 
 Another lOO grains being evaporated to drynefs in 
 a very low temperature, a blaekifli matter was left be- 
 hind, which did not entirely dilappear on heating the 
 fpoon containing it very hot in the naked fire ; but on 
 heating oxahc acid to a much leis degree, it evaporated 
 and left not a trace bchirid. 
 
 Carbonat of lime diiiblved in this diftilled liquid with 
 effervelcence. The ioUition tailed bitterifli, did not 
 turn paper ilained w itli turnfole red, and ou adding to 
 it carbonat of potais a copious precipitation eniued. 
 A little of this folutiou of lime and of allcali being eva- 
 porated to drynels, and the reiiduum made red hot, no- 
 thing remained but carbonat ot lime and carbonat of 
 potais. 
 
 This liquid did not render nitrat of lime turbid, but 
 it produced turbidnels in nitrat and muriat of barytes. 
 
 To five hundred grains of the reddifh-coloured liquor 
 obtained by melting white lac, carbonat of foda was 
 added till the efFervcfcence ceafed, and the mixture was 
 neutralifed ; for which purpofe three grains of the car- 
 bonat were neceffary. During this combination a quan- 
 tity of mucilaginous matter, with a little carbonat of 
 lime, was precipitated. The faturated folution being 
 filtrated and evaporated to the due degree, afforded on 
 ftanding dcliqnefcent cryflals, which on expolure to iire 
 left only a reiiduum of carbonat of foda. 
 
 Lime-water being added to this reddifh-coloured li- 
 quor produced a light purple turbid appearance ; and 
 on ftanding there were clouds juft perceptible. 
 
 Sulphuret of lime occafioned a white precipitation, 
 but no fulphurated iiydrogen gas was perceptible by the 
 fmell. 
 
 Tinfture of galls produced a green precipitation. 
 
 Sulphat of iron produced a purplifh colour, but no 
 precipitation ; nor was any precipitate formed by the 
 addition firlt of a little vinegar, and then of a little pot- 
 afs, to the mixture. 
 
 Acetite of lead occafioned a rcddifh precipitation, 
 which rediffolved on addiiig a little nitric acid. 
 
 Nitrat of mercury produced a whitifh turbid liquor. 
 
 Oxalic acid produced immediately the precipitation 
 of white acicular cryftals, owing probably to the pre- 
 fence of a little lime in the liquid. 
 
 Tartrite of potafs produced a precipitation not un- 
 like what takes place on adding tartarous acid to tar- 
 trite of potafs (u) ; but it did not diflblve again on 
 adding potafs. 
 
 Such were the properties of this acid difcovered by 
 Dr Pearfon. Its dellrudlibility by lire, and its afford- 
 ing carbon, diflinguifh it from all the acids defcribed 
 in this article before the acetous ; and its peculiar fmell 
 when heated, its precipitating tartrite of potafs with- 
 out forming tartar, its bitterifh tafte, and its being con- 
 
 333 
 
 verted into vapour at the temperature of joo^, JIflin- Pyriniu- 
 guilh it from all the acids hitherto examined*. ct-us Acid. 
 
 Sect. XXV. Of Pyromucoui Add. 'Phil. 
 
 PvROMUCous (v) acid is procured by diililling fugarp-sSs. 
 or any of the fweet juices. As they foam very much, -5*° 
 the retort ihould be large, and feveii-eighths of it empty . ^J^^J]"^ 
 A prodigious quantity of carbonic acid and carbonated "lyni'mu- 
 hydrogen gas is difcngaged: A very thin light coal rc-cous acid, 
 mains behind in the retort. Morvcau found the glafs 
 of the retort attacked. The quantity of fugar diftilled 
 was 2304 grains; the coal weighed 9S2 grains. There 
 were 4.28 grains of a brown liquor in the receiver, con- 
 filling moltly of an acid phlegm. This redillilled gave 
 313 grains ot a liquor almoll limpid, the fpecilic gra- 
 vity of which was 1,0115 at the temperature of 77". 
 It reddened blue paper. This acid may be concentra- 
 ted by freezing, or by combining it with fome bafe, 
 potafs, for inllance, and decompoling the compound by 
 a ftrouger acid, as, for example-, the fulphuric. 
 
 It has a very lliarp talle. When expofed to heat in !(,„"„„. 
 open vtffels, it evaporates, leaving a brown fpot. Dil- tics, 
 tilled in dole vefTcls, it leaves charcoal behind it. 
 
 It does not diffolve gold as Schriekcl and Lemery 
 and feveral other ch>:mills affirmed. 
 
 It does nut attack fiiver nor mercury, nor even their 
 oxides f . Ii corrodes lead, and forms flyptic and long). Schriciet. 
 cryflals. Copper forms with it a green folution : With 
 iron it forms green cryflals ; with antimony and zinc 
 greenifli folutions. 
 
 The compounds which it forms are called /yromair/Vi'j. Combina- 
 
 Its afiinities, according to Morveau, are as follows : tion«, and 
 
 Potais, 
 
 Soda, 
 
 Barytes, 
 
 Lime, 
 
 Magnefia, 
 
 Ammonia, 
 
 Alumina, 
 
 Jargonia J:. 
 
 Metallic oxides as lafulfh. acid. 
 
 Water, 
 
 Alcohol. 
 
 afiii.itics. 
 
 yltnu de 
 Chlm, xzii, 
 
 108. 
 
 5»1 
 ■3 Method of 
 
 S E CT. XXVI. Of Pyro-lignous Acul 
 
 It is well known that the fmoke of burning wood 
 exceedingly oHer.livc to the eyes : And chemiils haveobuinmg 
 long ago obfcrved, that an acid might be obtained by PVo-'iR- 
 diftilling wood. nous aiiJ. 
 
 It is to Mr Goettling, however, and to the Dijon 
 academicians, who repeated his experiment, that we are 
 indebted tor what knowledge we pofTel's of the peculiar 
 properties of this acid, which, becaufe it is obtained 
 from wood by means of fire, has been called ihe pyro' 
 itgnous iicid (w). It appears to be the fame from what 
 ever kind of wood it is obtained. 
 
 Mr Goettling filled an iron retort with pieces of 
 birch tree bark, and obtained by dillillation a thick, 
 brown, very empyreumatic acid liquor. This liquor he 
 allowed 
 
 (u) On this addition, tartar, or acidulated tartrite of potafs, is formed, which precipitates, becaufe it is very 
 little foluble in water. The addition of potafs diflblves it again, 
 (v) Morveau called this ac\A fyrupous acid, 
 (w) Goettling calkdit ligneous acid.
 
 i;79- 
 
 334 . C H E M I 
 
 I'yro li;,^- allowej to remain at reft for three months, and then fe- 
 ,"""' ^"^- paratcd from it a quantity of oil which had rifen to the 
 top. Bv diililliiig this lifjuor again, and then fatura- 
 ting it wlrli potals, and tvaporating to di jiicfs, he ob- 
 tained a blown fahne mals ; whieh, by being reditlol- 
 veJ in water, and evaporated, yielded grtyifli white cry- 
 llals : Thefe cryftals were conipol'cd ot pyro-lignous 
 acid and potafs. He poured upon them, by little and 
 little, a quantity of fulphuric acid ; and by applying a 
 gentle heat, the pyro-lignous acid came over in confider- 
 able purity *. 
 
 The Dijon academicians obtained this acid from 
 
 beech wood ; by diftilling ; ^ ounces, they procured 
 
 17 ounces of acid ; which, when rettified by a fecond 
 
 514 dillillation, was of the fpecific gravity 1,02083. 
 
 It5 proper- jt reddens vegetable colours : when expofed to a 
 
 "".'"""'". flronff heat, it takes fire and is dellroyed. It unites 
 Iiitio!is,aiid ° „ • 1 1 1 I 
 
 aflinlties. ■^''^O' ^^^" ^^"" alcohol. 
 
 Its compounds are called pyro-/igriifes. 
 Its affiQitics, as fixed by Mr Eloy Bourfier de Cler- 
 vaux and Mr de ^lorveau, are as follows : 
 Lime, 
 Barytes, 
 Potafs, 
 Soda, 
 Magnefia, 
 Ammonia, 
 Oxide of z.inc, 
 .— — manganefe, 
 
 ■ iron, 
 — — — lead, 
 t — tin, 
 
 cobalt, 
 
 copper, 
 
 ^— — — nickel, 
 
 arfenic, 
 
 ■ — bifmuth, 
 
 mercury, 
 
 — — antimony, 
 
 filver, 
 
 gold, 
 
 platinum, 
 
 Alumina, 
 Jargonia f ? 
 
 Sect. XXVII. Of Pyro-tartarous Acid. 
 
 An acid may alfo be obtained by diftiUing tartar ; it 
 
 is called pyro-tartarous add. 
 
 p ^^-^ • It has an empyreumatic tafte and odour ; reddens the 
 
 of pyro-tar- tinfture of turnfole ; but has no effedt on that of violets. 
 
 tarousacid. Little is known concerning this acid, except that 
 
 many of its properties are the fame with thofe of the 
 
 pyro-lignous ; and Morveau conjettures that, if pro- 
 
 perly purified, it would probably be difcovered to be 
 
 the fame with it. 
 
 The compounds which it forms are called pyro-tar- 
 t rites. 
 
 Its affinities are unknown. Morveau fuppofes that 
 they are the fame with thofe of the pyro-lignous acid. 
 
 liris Ann. de 
 Cbim. xxii. 
 
 aoS. 
 
 S T R Y. Part II. 
 
 they are obtained from vegetable fubftances. We have Vrgctable 
 placed the laftic and facchokftic acids in the fame clafs; ^Acni?. 
 becaufe thty bear a (Irong refcmblance to vegetable * 
 
 acids, and becaufe they are evidently compofed of the 
 fame ingredients with them. 
 
 Vegetable acids are riiftinguiflied from all the acids p|,f|.|.|jj. 
 defcrlbed in the beginning of this chapter, by their de- by fire. 
 flniiSihility by fire. ,-,3 
 
 There is no circumftance in cheroiftry which has at- Cw ert. 
 trailed greater attention than the poflibihty of convert-'''''^' """ 
 ing the various vegetable acids into each other by means'" "">«'•■ 
 of different procefiVs. To explain what pafies during 
 thefe proceffes, it would be neceffary to know exaftly 
 the component parts of every vegetable acid, the man- 
 ner in which thefe acids are combined, and the affinities 
 which exill between each of their ingredients. This, 
 however, is very far from being the cafe at prefent. 
 Though a vaft number of experiments have been made 
 on purpofe to throw light on this very point, the diffi- 
 culties which were to be encountered have been fo great, 
 that no accurate refults have yet been obtained. 
 
 It follows from thefe experiments, that all the vege- Inquiry in- 
 table acids are compofed, chiefly at lead, of oxygen, hy-*° ^^'^ I'ro- 
 drogen, and carbon ; but that the proportions differ i" Fhlir"inp°, 
 every individual acid. We fay chiefly, becaufe it hasjients. 
 been fufpefted from foroe plienomena, that one or two 
 of thefe acids contain befides a little azot. Let us take 
 a view of what is at prefent known of the compofition 
 of thefe acids in their order. 
 
 1. As to carbonic acid, its compofition has been af- 
 certained with tolerable accuracy ; it confifts of about 
 28 parts of carbon and 72 of oxygen. 
 
 2. By diftiUing 7680 grains of acetite of potafs, Dr 
 Higgens obtained the following produfts * : ' Hi^gemca 
 
 5»9 
 
 3862,994 grains, j--,,, 
 '473.564 
 
 1047,6018 
 
 78,0000 
 
 J 80,0000 
 
 340,0000 
 
 726,9402 
 
 J 26 
 
 Vegetable 
 acids. 
 
 The 18 preceding acids are all (except the laftic 
 and faccholattic) denominated vegetable acids, becaufe 
 
 Potafs, 
 
 Carbonic acid gas. 
 
 Carbonated hydrogen gas, 
 
 Refiduum, confifting of carbon. 
 
 Oil 
 
 Water, .... 
 
 Deficiency (x), ... 
 
 This deficiency Dr Higgens found to be owing to 
 a quantity of water and oil which is carried off by the 
 elaftic fluids, and afterwards dcpofited by them. He 
 calculated it, in the prefent cafe, at 700 grains of wa- 
 ter and 26,9402 grains of oil. Now, fince acetite of 
 potafs is compofed of acetous acid and potafs, and fince 
 the whole of the potafs remained unaltered, it follows 
 that the acetous acid was converted into carbonic acid 
 gas, carbonated hydrogen gas, carbon, oil, and water ; 
 all of which are compofed of oxygen, hydrogen, and 
 carbon. 
 
 Now 1473,564 gr. of carbonic acid gas are compofed 
 of 1060,966 gr. of oxygen, and 41 ;,598 gr. of carbon. 
 
 1047,6018 grains of carbonated hydrogen gas, from 
 a comparifon of the experiments of Dr Higgens and 
 Lavoifier, may be fuppofed to confift of about 7 14,6008 
 grains of carbon, and 333,0010 of hydrogen. 
 
 200,9402 grains of oil contain 163,4828 grains of 
 carbon and 43,4574 grains of hydrogen. 
 
 1040 grains of water contain 884 grains of oxygen 
 and 156 grains of hydrogen. 
 
 Therefor? 
 
 (x) For 29,1 grains of oxygen gas had alfo difappeared from the air of the velTels.
 
 Partir. C H £ M 
 
 Vegetable Therefore 3817,006 grains of acetouB acid are corn- 
 Acids, pofgd of ,5,44,966 — 29,1 = 1915,866 grains of 
 *"'""*'"~^ oxygen, 532,4584 grains of hydrogen, and 1 ;68,6Si6 
 grains of carbon. Confequently lOO parts of acetous 
 acid are corapofed of 
 
 50,19 oxygen, 
 13,94 hydrogen, 
 35,^7 carbon. 
 
 100,00 
 Thefe numbers can only be confidered as approxima- 
 tions to the truth ; for the objedl of Dr Higgens was 
 not to afcertain the proportions of the ingredients which 
 compofe acetous acid ; and therefore his experiments 
 were not condufted with that rigid accuracy which 
 would have been necefTary for that purpofe. 
 
 It is extremely probable, that during the acetous 
 fermentation, or the converfion of alcohol into acetous 
 *t!erm/faJi,acid, a quantity of water is formed* ; and it is certain 
 Crtil's Alt- that oxygen is abforbed. It follows from this that 
 mh, j7S6. acetous acid contains more carbon and lefs hydrogen 
 than alcohol. Now we have reafon, from Lavoiiier's 
 experiments, to believe that alcohol is formed of 
 51,72 oxygen, 
 18,40 hydrogen, 
 29,88 carbon. 
 Lavoifier fuppofes that this acid contains alfo azot. 
 
 3. Acetic acid is fuppofed to confift of the fame 
 bafe with acetous acid, combined with a larger propor- 
 tion of oxygen ; we would rather fay, that it is ace- 
 tous acid combined with oxygen. 
 
 4. When oxalic acid is' diftilled with fix times its 
 weight of fulphuric acid, the prodiiiEts are acetous acid, 
 fulphurous acid, carbonic acid gas, and fulphuric acid 
 
 . f'^^ji remains in the retort f . Hence it follows, that oxalic 
 Jour, ,,'f acid contains more carbon than acetous acid ; but that 
 i'i>/ 1785. it is compofcd of the fame ingredients. It has been 
 fuppofed that oxalic acid is compofed of fugar and oxy- 
 gen. Now fugar, according to Lavoifier, is compofcd 
 of 
 
 Hydrogen, - - - - 8 
 
 Oxygen, - - - - 64 
 
 Carbon, - - - - 28 
 
 Thefe proportions are rather unfavourable to that 
 notion ; at lead if any dependence can be put in the 
 compofition of acetous acid as deduced from the expe- 
 riments of Dr Higgens. 
 
 5. Hermlladt dilfolved four ounces of tartarous acid 
 in 16 ounces of water, and kept the folution in a veffel 
 covered with p?per in a warm place. In three months 
 the tafte of the folution was changed, and the air in the 
 upper part of the vcfTel was found to be carbonic acid. 
 In fix montlis the folution was converted into acetous 
 acid. It follows from this experiment, that tartarous 
 acid contains more carbon than acetous acid, and that 
 their ingredients are the fame. If any doubts Ihould 
 remain, the following experiment is fuiScient to remove 
 them. Weftrum mixed ftrong fulphuric acid with tar- 
 tarous acid, and added manganefe ; acetous acid was 
 produced, and a great quantity of carbonic acid gas 
 was difengaged. When nitric acid is dillilled off tar- 
 tarous acid, it is converted into oxalic acid, as Scheele 
 firft proved. Hence it has been fuppofed by fome, 
 that oxalic acid differs from tartarous merely in contain. 
 ing more oxygen : but this is very far indeed from be- 
 
 I S T 11 Y. ZiS 
 
 ing proved. According to HafTcnfratz, tartarous acid Prufljc 
 contains a confiderable quantity of azot. , ' ' . . 
 
 6. When citrat of lime is allowed to remain in a 
 bottle nightly corked along with a little alcohol, the 
 citric acid is gradually converted into acetous acid *.• i/oW. 
 Wellrum converted it into oxalic acid by means of ni- 
 tric acid. 
 
 7. Malic acid was converted into oxalic by means of 
 nitric acid by Scheele. It has been fuppofed to con- 
 tain more oxygen than oxalic acid. Some of it is al- 
 ways formed during the common procefs of converting 
 fugar into oxalic acid. Were we to judge from an ex- 
 periment, which, however, was not performed with- 
 fufficient accuracy, we would conclude that the bafe of 
 malic acid is gum ; for by diililling two parts of weak- 
 nitric acid off one part of gum in a very fmall heat, we 
 obtained a quantity of acid more in weight than the> 
 gum, which exhibited feveral of the diflinguifhing pro- 
 perties of mah'c acid. It was exceedingly light, white, 
 and fpongy, and attrafted water very quickly from the 
 atmofphere, and could not afterwards be brought by 
 evaporation to its former ftate. 
 
 8. Scheele converted ladtic acid into acetous by mere 
 expofure to the atmofphere, and found that a quan- 
 tity of carbonic acid was difengaged. Hence this acid 
 is merely the acetous with a fmaller proportion of car- 
 bon. 
 
 9. The gallic acid, we have feen, contains more car- 
 bon than any of the others. 
 
 10. Nothing is known concerning the compofition of 
 the benzoic and fuccinic acids. Hermlladt fays he 
 converted benzoic acid to oxalic by tneans of nitric acid : 
 but Morvcau did not obferve that any change was pro- 
 duced. 
 
 J I. The bafe of camphoric Isprobably camphor. 
 
 Though thefe eighteen are the only acids which have 
 hitherto been examined with attention, it cannot be 
 doubted that the number of vegetable acids, either ex- 
 illing naturally, or at leall capable of being formed by 
 art, is confiderably greater. Morveau has lately afcer- 
 tained, that the red colours of flowers are owing to 
 acids : This had already been conjeftured by Linnaeus, 
 
 Sect. XXVIII. Of Pmjtc Acid. 
 
 530 
 About the beginning of the prefent century, Dicf-Difeovcry ■ 
 bach, a chemiil oi Berlin, wifhing to precipitate a folu-"f Pf""'^"'' 
 tloii of cochineal mixed with a little alum and fulphat ' 
 of iron, borrowed from Dippel fome potafs, from which 
 that chemill had dijl'illed feveral times his onmul oil. 
 On pouring in the potafs, Dicfbach was furprifed to fee, 
 iniltad of the red precipitate which he had cxpcfled, a 
 beautiful blue powder falling to the bottom of the veffel. 
 By reflcfting on tiie materials which he had employed, 
 he eafily diicovered the method of procuring the blue 
 powder at ))leafure \. This powder was callecl Pnijfmn , r, ii- 
 blue, from the place where it was difcovered. It was ,00 Expe-- 
 announced in the Berlin Memoirs for 17 10; but i^itrmmii. 
 procefs was concealed, becaufe it had become a lucra- 
 tive article of commerce. A method of preparing 't,., •'o'j p 
 however, was publillied by Woodward in the Philofo-prcparinj;-- 
 phlcal Tranfdftions for 1724, which he faid he had got it. 
 from one of his friends in Germany. This method was 
 as follows : Detonate togetiier 4 ounces of nitre and as 
 much tartar, in order to procure an extemporaneous al- 
 kali ; then add 4 ounces ot dried bullock's blood, m'x 
 
 the-
 
 33^ 
 
 C H E M 
 
 531 
 
 Its ciiinpo 
 lition difco' 
 vered by 
 Macquer. 
 
 Pruflle the ingredients well togethei", and put them into a cru- 
 " ' , cible covered with a lid, in which there is a fmall hole ; 
 calcine with a moderate fire till the blood emits no more 
 fmc ke or flame cap:ihle of blackening any white body 
 expofed to it : increafe the fire towards the end, fo that 
 the whole mattf contained in the crucible Ihall be mo- 
 derately but fenlibly red. In this Hate throw it into 
 two pints of water, and boil it for half an hour. De- 
 cant off this water, and continue to pour on more till 
 it come off infipid. Add all thefe liquids together, and 
 boil them down to two pints. Diffolve two ounces of 
 fulphat of iron and tight ounces of alum in two pints 
 of boiling water ; mix this with the former liquor while 
 both are hot'. An efFervefcence 'akes place, and a pow- 
 der is precipitated of a green colour mixed with blue. 
 Separate this precipitate by filtration, and pour muria- 
 tic acid upon it till it becomes of a beautiful blue ; then 
 wafli it with water and dry it. 
 
 Different explanations were given of the nature of 
 this precipitate by different chemiils. All of them ac- 
 knowledged that it contained iron, but to account for 
 the colour was the difficult point. Brown, and Geof- 
 frey, and Neumann, difcovered in fuccefTion, tliat a great 
 many other animal fubllances befides blood communica- 
 ted to alkalies the property of forming Pruflian blue. 
 Macquer undertook an examination of this fubftance, 
 and puhlifhed the rcfult of his experiments in the Me- 
 moirs of the French Academy for 1752. 
 
 He oblcrved that, when alkali is added to a fohi- 
 tion of iron in any acid, the iron Is precipitated of a 
 yellow colour, r.od foluble in acids ; but if iron be pre- 
 cipitated from an acid by an ailoli prepared as above 
 defcribed, by calcination with blood (wliicli has been 
 called a Pri^iav alkali), it is of a green colour. Acids 
 dilFolve only a part of this precipitate, and leave behind 
 an infoluble powder whicli is of an intenfe blue colour. 
 The green precipitate therefore is compofed of two dif- 
 ferent fubftances, one of wliich is Pruflian blue ; the 
 other, as he afcertained by experiment, is the brown or 
 yellow oxide of iron : and the green colour is owing to 
 the mixture of the blue and yellow fubftances. When 
 heat is applied to the iafolubie precipitate, its blue co- 
 lour is dcllroyed, and it becomes exatlly fimilar to com- 
 mon oxide of iron. It is compofed therefore of iron and 
 fome other fubftance, which heat has the property of 
 driving off. If this infohible precipitate be boiled with 
 a very pure alkali, it lofcs its blue colour alfo, and at the 
 fame time the alkali acquires the property of precipita- 
 ting of a blue colour tolutions of iron in acids, or it has 
 become precifely the fame with the PrulTian alkali. 
 Pruffian blue, therefore, is compofed of iron and fome- 
 thing which a pure alkali can feparate from it, fomething 
 which has a greater affinity for alkali than for iron. 
 By boihtig a quantity of alkali with Pruffian blue, it 
 may be completely faturated with this fomething, which 
 we fhall call colouring matter, and then it has loft all 
 its alkaline properties. No acid can feparate this co- 
 louring matter from iron after it is once united with it. 
 When iron diffolved in an acid is mixed with an alkali 
 faturated with the colouring matter, a double decompo- 
 fition takes place, the acid unites with the alkali, and 
 the colouring matter with the iron, and forms Pruflian 
 blue. The reafon that, in the common method of pre- 
 paring Pruffian blue, a quantity of yellow oxide is pre- 
 cipitated, is, that there is not a fui&cient quantity of co- 
 
 Acid. 
 
 5.^3 
 
 I S T R Y. Partll. 
 
 louring matter (for the alkali Is never faturated with it) Pruillc 
 to faturate all the iron difplaced by the alkali; a part of 
 it therefore is mixed with Pruflian blue. Muriatic acid 
 dilTolves this oxide, carries it off, and leaves the blue in 
 a flate of purity. Such were the conchifions wliich 
 Macquer drew from his experiments; experiments which 
 not only difcovered the compofition of Pruffian blue, 
 but threw a ray of light on the nature of affinities, 
 which has contributed much towards the advancement 
 of that important branch of chemiftrv. 
 
 The nature of the colouring matter, however, was ftiU 
 unknown. Macquer himfelf fuppofed that it was pure 
 phlogifton ; but the opinion was untenable. He hrid 
 fhewn that it pofLiTcd the property of forming neutral 
 falts, and therefore Bergman and Morveau (ufpefted 
 that it was an acid. 
 
 Scheele undertook the tafk of examining its nature, 
 and publifiied the refult of his experiments in tlie Stock- 
 holm Tranfaftions for 1782. 
 
 He obferved that the Pruffian allva!!, after being ex- 
 pofed for fome time to the air, loft the property of form- 
 ing Pruffian blue ; the colouring matter mu:l therefore 
 have left it. 
 
 He put a fmall quantity of it into a large glafs globe, Dj^orispo. 
 corked it up, and kept it fome time ; but no changefed by 
 was produced either in the air or the Pruffian alkali. Scheele. 
 Something muft therefore difplace the colouring matter 
 when the alkali is expofed to the open air, wliich is 
 not prefent in a glafs vefTcl. Was it carbonic acid gas ? 
 To afcertaiu this, he put a quantity of Pruflian alkali 
 into a glafs globe tilled with that gas, and in 24 hours the 
 alkali was incapable of producing Pruffian blue. It is 
 therefore carbonic acid gas which difplaces the colour- 
 ing matter. He repeated this experiment with this dif- 
 ference, that he hung in the globe a bit of paper which 
 had been previoufly dipped into a-folution of luiphat of 
 iron, and on which he had let fall two drops of an alka- 
 line lixivium, in order to precipitate the iron. This 
 paper was taken out in two hours, and became covered 
 with a fine blue on adding a little muriatic acid. Car- 
 bonic acid, then, has the property of leparating the co- 
 louring matter from alkali without decompoling it. ,,^ 
 
 He found alfo that other acids produced the fame ef-Thecolour- 
 feft. The cokiuring matter then may be obtained per-'"g matter 
 haps in a feparate ftate. He accordingly made a num- P"^' 
 ber of attempts to procure it, and at laif dilcovered the 
 following procefs : He boiled together for fome minutes 
 two ounces of Pruffian blue in powder, one ounce of 
 the red oxide of mercury, and fix ounces of water ; then 
 pafTcd the whole through a filter, and waftied the reli- 
 duum with two ounces of boiling water. The oxide of 
 mercury has a greater affinity for the colouring matter 
 than the oxide of iron ; it therefore unites with it, and 
 forms with it a fait foluble in water. The iron remains 
 behind upon the filter, and the liquid is a folution of the 
 colouring matter combined with mercury. He poured 
 this folution upon half an ounce of pure iron-filings, and 
 added at the fame time three grains of fulphuric acid. 
 The iron feparates the oxygen from the mercury, in 
 order to combine with the fulphuric acid; the mercury 
 is precipitated in its metallic flate, and leaves behind it 
 a quantity of fulphat of iron and of colouring matter 
 diffolved in water, but not combined, as the colouring ., ir. 
 matter is unable to feparate the iron from the acid '. ^„„ ^ 
 
 He then diftilled in a gentle heat ; the colouring mat- ci>mie, i. 
 
 terao-
 
 Part If. 
 
 C H E M 
 
 PrufTic ter came overly the time that one-fouvth of the liquor 
 Acid. liatJ pnfled into tlie receiver. It was mixed, however, 
 "~^ with a Imall quantity ot'fulphuric acid; from wliich he 
 
 fepavated it by diiliUiiig a i'ccoud time over a quantity 
 of carbonat of lime. The fulphuric acid comlMiits with 
 the lime and remains behind, which the colourinjr mat- 
 ter cannot do, bccaufe carbonic acid has a ilionger affi- 
 nity for lime than it has. Thus he obtained the colour- 
 ing matter in a ftate of purity. 
 
 It remained now to difcover its component parts. He 
 formed a very pui e PrufTian blue, which he dillilled, and 
 increafed the fire till the velTel became red. The Imall 
 quantity of water which he had put into the receiver 
 contained a portion of the blue colouring matter and of 
 ammonia ; and the air of the receiver confilled of azot, 
 carbonic acid gas, and the colouring matter. He con- 
 cluded from this experiment, that the colouring matter 
 was compofed of ammonia and carbon. He mixed to- 
 gether equal quantities of pounded charcoal and potafs, 
 put the mixture into a crucible, and kept it red iiot for 
 a quarter of an hour : he then added a quantity of fal 
 ammoniac in fmall pieces, which he puflied to the bot- 
 tom of the melted mixture, kept it in the fire for two 
 minutes till it had ceafed to give out vapours of ammo- 
 nia, and then threw it into a quantity of water. The 
 folution polTefled all the properties of the Prufllan al- 
 kali. Thus Mr Scheele fucceeded in forming the co- 
 louring matter ; and it was confidered as proved that it 
 was compofed of ammonia and carbon. 
 
 But after the publication of Scheele's experiments, 
 it was difcovered that ammonia itfelf is compofed of 
 azot and hydrogen. It became therefore a queilion. 
 Whether ammonia entered into the compofition of this 
 fubftance, or merely its ingredients? VVIiether it was 
 compofed of ammonia and carbon, or of azot, hydro- 
 gen, and carbon combined in a different manner? This 
 point has been decided by the following experiments: 
 Mr Clouet made a quantity of ammoniacal gas pafs 
 through a red hot porcelain tube filled with charcoal, 
 and by this procefs formed a quantity of the colouring 
 matter *. Here the temperature was fu high that the 
 ammonia mull have been decompofed: and the colouring 
 matter cannot be formed by combining ammonia and 
 charcoal except at a temperature equally high. There 
 is reafon therefore to fuppofe that the ammonia is de- 
 compofed. When oxy-muriatic acid is mixed with the 
 colouring matter, it communicates to it a quantity of 
 oxygen, and caufes it in confequence to alfume very dif- 
 ferent properties. When a fixed alkali or lime is added 
 to it in this ftate, it is immediately decompofed, and 
 converted into ammonia and carbonic acid gas. The 
 colouring matter in this ftate contains all the ingredients 
 neceflary to form thete two iubflances, namely, azot, 
 hydrogen, carbon, oxygen : but in order to induce the 
 ingredients to form thefe two compounds, the affiftance 
 of an alkali or lime to combine with the carbonic acid 
 is neceflary ; juft as fulphur combines more eafily with 
 oxygen when united with an alkali or with iron than 
 when feparate f . 
 
 SuppL. Vol. I. Part I. 
 
 f T>er:lolht, 
 iiiJ. i. 
 
 I S T R Y. 
 
 The colouring matter, then, which we (hall hence- 
 forth call the Prujfic acid, is compofed of azot, hydro- 
 gen, and carbon; but the proportions of thefe ingrcdient.i 
 have not yet been determined. It is confidered as an 
 acid, though the prefence of oxygen has not been proved, 
 bccaufe it has the property of turniing neutral falls with 
 the fame bales as other acids. 
 
 The Pruflic acid is exceedingly volatile, and evident- p,;,j^,i.j 
 ly capable of exilting in a gafeous ftate. It has a pecu- f Hruffic 
 liar odour, not dilagreeable, and which has been com-^''^- 
 pared to the flowers of the peach. It has a fweetifti 
 and fomewhat hot taft^, and excites cough*. * ScheiU. 
 
 It has no affinity for alumina nor for alcohol f. i ^^^ 
 
 This fubftance differs exceedingly in its adtion from 
 all other acids. 
 
 It is capable of combining, like them, with earths, (, 5 "^'^;o„ 
 alkalies, and metallic oxides, and of forming compoundsou otK-r 
 which have been denominated PniJJiats. But it enters'-'O'^'';'- 
 much more readily into triple compounds with alkalies 
 or earths, and metallic oxides, than into combinations 
 with earths or alkalies feparately ; and though its affi- 
 nity appears to be greater for alkalies and earths than 
 for metallic oxides, yet when in a free or gafeous ftate it 
 does not enter into combinations with earths or alkalies 
 without difficulty, and it is ieparated from them much 
 more eafily than from metallic oxides. Mere expofure to 
 the light of the fun, or to a heat of 110°, is fuilicient 
 for that purpofe. 
 
 Its affinities are fuppoied to be as follows :, 53S 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Lime, 
 
 Barytes, 
 
 Magnefia, 
 
 Oxide of zinc, 
 
 ■ — iron, 
 
 ■' manganefe, 
 
 cobalt, 
 
 nickel, 
 
 lead, 
 
 ■ — tin, 
 copper, 
 
 ' bifmuth, 
 
 — — — antimony, 
 — — - — arfenic, 
 
 ■ — fdver, 
 
 mercury, 
 
 gold, 
 
 — platinum (y). 
 
 Sect. XXIX. Of Formk ^cU. 
 
 . In the 15th century feveral botatiifts obfcrved, with r,-/^' 
 aftonifhment, that the flower oi luccory, when thrown „f'f™)''.'7 
 into an ant hill, became as red as blood : But it wasacij. 
 Mr S. Fiflier who firft difcovered that ants poffefl'ed a 
 peculiar acid, which he obtained b) diftiiling thefe ani- 
 mals. His experiments were publiflied in the Philoiophi- 
 cal Tranfaftions for 1670. Though Hoffman afterwards 
 U u repeated 
 
 Its affini- 
 ties. 
 
 (y) We fufpeft that this is not the real order of the affinities of this acid; the metallic oxides ought probably 
 to be placed before the alkalies and earths, and the metallic Pruffiats ought to occupy the pface which is at pre- 
 fent filled by the metaUic oxides. The reafons for this conjefture will appear afterwards. See Part III. chap. ii. 
 {(.&., 23. of this article.
 
 338 
 
 CHEMISTRY. 
 
 Part IF. 
 
 Formic repeated his procefs, little was known concerning tlni 
 ^" ^' nature of this acid till Margraf uiidertohk its examiiia- 
 * tion, and ptiblilhcd his experiments in the Berlin Me- 
 moirs for 1749. 
 
 The fpecies of ants from which the formic acid is 
 obtained is the formica rufa, which reiide mod common. 
 Iv in woods, or at leall in elevated and dry places. 
 They have been found to contain the greatcft quantity 
 of acid in the months of June and July. If at that 
 feafon one of thcfe animals be prcffed upon paper tin- 
 ged with turnfole, it changes the colour of it to a moil 
 lively red: they even fometimes llain it merely by crawl- 
 ^-o ing over it. 
 Methods of There are two methods of obtaining the formic acid, 
 obtaining JJftHlation and lixiviation. 
 
 "• When the firft method is to be employed, the ants 
 
 aie to be wadied clean, dried with ?. gentle heat, put in- 
 to a retort, and diftilled with a moderate heat, gradual- 
 ly increafed till all the acid has come over. It is mix- 
 ed with an empyreumatic oil, from which it is feparatetl 
 by paffing it tln-ough a flraiacr previoufly moiftened 
 with water. By this procefs MelTrs ArdvilTon and 
 Oehrn obtained from a pound of ants yi ounces of acid, 
 the fpeciiic gravity of which, at the temperature of 6o^ 
 
 • Z)//rf<. o» was 1,0075*. Morveau obtained from 49 ounces of 
 tbeAcidof ants 23 ounces of pretty llrong acidf. Margraf added 
 ^"".1777. a quantity of water; but it is evident that thia ferves 
 '"rv'^^J, ««''ely to weaken the acid. 
 
 ^Magnz'iZ When the other method is preferred, the ants are to 
 /»r Art!, be wafhed in cold water, put upon a clean linen cloth, 
 f Encyc. ^ an(j boiling water poured on them repeatedly till it can 
 Mithod.i. extradl no more acid. The linen is then to be fqueezed, 
 and the feveral liquors mixed and filtrated. This me- 
 thod was firft ufed by Ardviflon and Oehrn : they ob- 
 tained from a pound of ants an acid liquor which had 
 more fpecific gravity than common vinegar. It is to 
 be purified from the oil which adheres to it by repeated 
 ' diftillations. After four diftillations the empyreumatic 
 oil ftiU manifefts its prefence by its fmell, but this fmeli 
 vanilhes if the acid be expoied for fome time to the air; 
 a quantity of effential oil, however, ftill remains, which 
 cannot be feparated. The fpecific gravity of the acid 
 X Ardvljfon (hus rcttified is 1,0011 %. 
 
 'h-J ^'^"'' Hermftadt employed a third method. He exprefTed 
 
 " ' the juice of dry ant's, and by this means obtained from 
 
 albs, of thefe animals 21 oz. 2 dr. of juice, which on 
 
 diftillation yielded a clear pure acid, equal in ftrength to 
 
 very concentrated vinegar^. 
 
 This acid feems to be capable of affuming a gafeous 
 form ; at lead Hermftadt obferved, that when he put 
 fome of it into a bottle with a glafs ftopper, the ftop- 
 per was frequently raifed by an elaftic fluid making 
 itsefcape, and that after fome days it had loft its fmell ||. 
 When this acid is boiled with nitric acid, a gas is extri- 
 cated, which renders lime-water turbid, and has a very 
 5^.rf^i^.»,pu''gentodour^. * , r r 11 r 
 
 Hid. This acid has a ftrong but not unpleaiant ImeU, a caui- 
 
 tic tafte, and when much diluted a pleafant acidity. When 
 
 • Hid. "'o'^ concentrated, its fpecific gravity is 1,0453 *• 
 
 One part of this acid, mixed with 75 parts of water, 
 gives a faint red to fyrup of violets ; mixed with 430 
 parts of water, it reddens paper coloured with turnfole; 
 reixed with 1300 parts of water, it produces no efFeft 
 
 ^MorvcM, on the infufion of turnfole f. It mixes readily with al- 
 
 f.Ct. cohol. 
 
 $ CreU's 
 
 17S4. 
 
 J4I 
 Its proper- 
 ties. 
 11 Jiid. 
 
 Sel.acic 
 .Adi. 
 
 It unites readily with the other acids. When boiled 
 with fulphuric acid, it becomes black. White acrid va- 
 pours rife when the mixture becomes hot; and when it "' 
 boils, a gas rifes which unites with difficulty to water 
 and lime-water; the formic acid is again obtained, but 
 its quantity is diminiftied *. * Jtid, 
 
 Nitric acid decompofcs it altogether, and is itfelf 
 converted into lutrous acid. Muriatic acid docs not al- 
 ter it. Oxy-muriatic afts like nitric acidf. f liu. 
 
 Its compounds are called ybrm/af/. J-iz 
 
 Its affinities are the fame with thofe given above for ''* '^°™' 
 r. rt- • , ° ( nurds ani 
 
 ^Ihnities. 
 
 the Prufiic acid. 
 
 Sect. XXX 
 
 54.'! 
 
 Of Seback JclJ. 
 
 Chemists had long fufpefted that an acid could be uifcovery 
 obtained from tallow, on account of the acrid uature of oi Icbacic 
 the fumes which it emitted at a high temperature ; but *'^"^' 
 it was M. Grutzmacher who firft demonftrated this acid 
 in a diflei tation De OJftum Medulla, publiftied in l 74B J. } LmitiardU 
 Mr Rhodes mentioned it in i 753, and .Segner publilbed 
 a differtation on it in 1734, and Crell examined its pro- 
 perties very fully in two diftertations publiflied in the 
 Piu'l. Tranf. for T780 and 1782. It was called at firft 
 acid of fa!, and zht-vw ards febacic acid. 
 
 It may be procured by heating together a mixture of 
 fuet and lime. Sebat of lime is formed, which may 
 be purified by folution in water. It is then to be put 
 into a retort, and fulphuric acid poured on it. Sebacic 
 acid pafTcs over on the application of heat. 
 
 Sebacic acid has an acid, fharp, bitterilh tafte, and a its pioper- 
 very pungent fmell. It reddens tint^ure of litmus. ties, 
 Heat caufes it to aiTume a yellow colour. 
 It oxidates filver, mercury, copper, iron, lead, tin, 
 zinc, antimony, manganefe. 
 
 It does not att upon bifmuth, cobalt, nickel; When 
 mixed with nitric acid it diffblves gold. 
 Its compounds are c^\iA febats. 
 Its affinities, according to Morveau, are as follows 
 Barytcs, 
 Potafs, 
 Soda, 
 Lime^ 
 Magnefia, 
 Ammonia, 
 Alumina, 
 Jargonia §, 
 Oxide of zinc, 
 — — — manganefe, 
 
 — iron, 
 
 . — lead, 
 
 tin, 
 
 I — cobalt, 
 
 — copper, 
 
 nickel, 
 
 arfenic, 
 
 — bifmuth, 
 
 — mercury, 
 
 — antimony, 
 
 filver. 
 
 545 , 
 Cempnunds 
 and affini- 
 ties. 
 
 § Vattqite-^ 
 iin, Ann. de 
 Cbim. xxii. 
 »0S. 
 
 Sect. XXXI. Of Bomlyc JciJ. 
 
 546 
 
 Mr BoissiER DE Sauvages obferved, that the juice jjij-^^^^y 
 of the filkworm, in the difeafe called in France wi//?a- of hombjc 
 dine, was acid ; and Chauffier remarked, that the Clk- acid. 
 worm, after being converted into a butterfly, gives out
 
 fart 11. 
 
 Zoonic aliqiior which turns vegetable blues to a red. He found, 
 ^cul fij^j during the time that tlie animal was forming its 
 ' cocon, the acid was depolited in a rifervoir near the a- 
 nns. By means of a pair of fcifF.irs he collefted fome 
 which reddened blue paper, united with alkalies with 
 effervefcence, and even attacked the icilfixrs. He after- 
 wards coUeftfd it by iiifufiiig tlie chryfalids in alcohol, 
 which diflblved the acid, but left the impurities un- 
 touched. 
 
 This acid has never been examined with attention ; 
 fo that almolt all it.'i properties are unknown. 
 
 C H E INI I S T R Y. 
 
 339 
 
 ^lethml of 
 
 obtaining 
 
 zounic a- 
 
 cid. 
 
 • Ann. f/' 
 
 Cb'in. xxvi. 
 
 54S 
 
 If. prcper 
 Ues. 
 
 \BirthaUct, 
 Ann, dd 
 Chim. Xjvi. 
 
 549 
 Animal 
 icids. 
 
 Sect. XXXII. Of Zoonk /tciJ. 
 
 Mb. Berthollet has obtained a peculiar acid by di- 
 ftilling vegetable and aniiiial fub'.lances, to which he has 
 given the name of the zoonic aciil*. He procured it by 
 dillilling the gluten of wheat, the yell of beer, bones, 
 and woollen rags ; and concludes, therefore, that it may 
 be produced by the dillill.ition of all auiiiLil fubltances. 
 
 To obtain this acid pure, he mixed lime with the di- 
 ftiUed liquid, after having feparaled the oil, which it 
 always, contains (for the produA of the diltillatiou of 
 animal fubftanccs is chiefly oil and carbonat of ammo- 
 nia.) He boiled this mixture till the carbonat ot am- 
 monia was exhaled : he then filtered it, added a little 
 more lime, and boiled it again till the fmell of the am- 
 monia had gone off entirely. The liquor, which now 
 contained only zoonat of lime, he tillered again, and 
 then added a little water impregnated with carbonic 
 acid, in order to precipitate any lime which might hap- 
 pen to be dilTolved in the liquid without being com- 
 bined witli the zoonic acid. 
 
 After concentrating the zoonat of lime, he mixed it 
 with priofphoric acid, and diftilled it in a retort. At a 
 beat ne.uly equal to that of boiling water, the zoonic 
 acid paifes over in a date of purity. 
 
 The zoonic acid has an odour like that of meat when 
 frying, aird it is a6lually formed during that procefs. 
 It has an auftere talle. 
 
 It gives a red colour to paper tinged with turnfole. 
 
 With alkalies and earths it produces falts, which dp 
 not appear capable of cryftallizing. 
 
 It forms a white precipitate in the folutions of ace- 
 tite of lead and nitrat of mercury. 
 
 Part of the zoonic acid feems to be deftroyed by the 
 aftion of heat during the diftillation of the zoonat of 
 lime with phofphoric acid ; for the liquor, which is in 
 ebullition, becomes brown, and grows black at the end 
 of the operation ; hence Mr Berthollet concludes that 
 the zoonic acid contains carbon. The zoonat ot filver, 
 when kept, becomes gradually brown j hence he con- 
 cludes that the acid contains hydrogen. Thefe conclu- 
 fions he draws from a very ingenious theory of his, 
 which has been already dcfcribed in the article Bleach- 
 ing in this Supplenienf\. 
 
 The five preceding acids have obtained the name of 
 animal acids, becaufe they are all obtained from the ani- 
 mal kingdom. It can fcarcely be doubted that a more 
 accurate examination of animal fubftances will add con- 
 fiderably to the number of thefe acids. 
 
 Sect. XXXIII. Of Arfcnic Acid. 
 
 Arsenic acid, which was firft difcovered by Scheele, 
 may be produced by fimply mixing the white oxide of 
 
 arfenic with oxy-murlatic acid, and applying a heat filf- Arfcnic 
 ticient to fublime the muriatic acid. The theory ol ^ . 
 
 this operation is evident : the white oxide has a greater . \ 
 affinity for oxygen than muriatic acid has ; of courfe M 1 A of 
 it combines with it, and is thus converted into arfenic "'"■''''■"S 
 acid, and the muriatic acid is eafily fublimcd by apply-"''''"*' 
 ing heat. 
 
 Landriani has infoimed us, that this acid may be al- 
 fo formed by fubliming feveral times luccelfively the 
 while oxide of arlenic, and taking care every tinx to re- 
 new the air. This proccis is equally fimplc ; the oxide 
 combines at a high temperature with the oxygen of the 
 atmofphere. 
 
 This acid is exceedingly fixed. When expofed to j^, proper, 
 the air it attracts humidity, and at laft becomes li-tics. 
 quid. At the temperature of 60" it difTolves in two- 
 thirds of its weight of water. Its folution may be eva- 
 porated to drynefs, and even converted into a glafs, 
 which attrafts moifture from the air, and adls power- 
 fully on the crucible. 
 
 It is poifonous as well as the white oxide of arfe- 
 
 When expofed to a red heat, it is partly decompofed 
 and converted into white oxide of arfenic f. \U. 
 
 It does not aft upon gold, platinum, filver, mer- 
 cury. 
 
 It oxidates copper, iron, lead, tin, zinc, bifmuth, 
 antimony, cobalt, nickel, manganefe, and arfenic, and 
 in a very ftrong heat, mercury and filver. 
 
 According to Berthollet's experiments, arfenic acid 
 is compofed of eight parts of white oxide of arfeiu'c and 
 one part of oxygen. 
 
 Its compounds are called arfeniats. 
 Its affinities are as follows : 
 Jjime, 
 Barytes, 
 Magnefia, 
 Potafs, 
 Soda, 
 Ammonia, 
 Oxide of zinc, 
 — — — manganefe, 
 — — iron, 
 
 — lead, 
 
 — — — tin, 
 — — — cobalt, 
 
 copper, 
 
 nickel, 
 
 bifmuth,, 
 
 mercury, 
 
 antimony, 
 
 filver, 
 
 gold, 
 
 platinum, 
 
 * ScheeU^ 
 
 Us ct)ni- 
 
 piiindsand 
 
 aflunities. 
 
 Alumina, 
 Jargonia % ? 
 Water. 
 
 ^ Vauqiirlitti 
 Ann. Ji 
 Clim. xxii. 
 
 »0S. 
 
 , Propertici 
 exannncd„f,;;ng(l,j 
 
 Sect. XXXIV. Of Tungstic AciJ. 
 
 TuNGSTic acid, or oxide of tungften, was firfl dif- 
 covered by Scheele ; but the acid which he 
 was not pure, being compofed, as Mr Luyart has (hewn, acid, 
 of nitric acid, amn;onia, and tungilic acid. The real 
 acid is infolublc m A-ater, taftelefs, and incapable of 
 turning vegetable blues red till it has been firft rendered 
 U u 2 folublc
 
 Moiybdlc 
 Acid. 
 
 • Rinaan. 
 
 CHEMISTRY. 
 
 554 
 Its cora- 
 pnunds and 
 alTirities. 
 
 } VaujwHn, 
 jinn, de 
 Cbim. mil. 
 3o8. 
 
 Properties 
 of molyb- 
 <iic acid. 
 { Bergman. 
 
 H Vauqueli> 
 Tb'Ufbphica 
 
 i. >i2. 
 
 foluble by being partly combined with ammonia. It is 
 of a beautiful yellow colour, which becomes bhie when 
 expofed to the light, or heated violently in clofe vefTels. 
 It does not recover its yellow colour except by calcina- 
 tion in the open air, and then increafes in weight. 
 Wlicn put into muriatic acid along with tin, zinc, or 
 iron, the liq-Jor becomes blue *. Treated with acetous 
 acid, it becomes blue. When reduced to a glafs with 
 phofphat of foda, the blTie colour appears and difap- 
 pears according as the blue or yellow part of the flame 
 is direfted to it, as happens to manganefe. Probably 
 this blue fubftance is an oxide of tungften with a (mai- 
 ler quantity of oxygen. 
 
 Its compounds are called iungstats. 
 Its affinities are as follows f : 
 
 Lime, 
 
 Barytes, 
 
 Magnefia, 
 
 Potafs, 
 
 Soda, 
 
 Ammonia, 
 
 Alumina, 
 
 Jargonia $ ? 
 
 S E CT. XXXV. Of BJolybdlc Acid. 
 
 Concrete moIyHdic acid, firll difcovered by Scheele, 
 is white, and has an acid but metallic tafte. Its fpecific 
 gravity is 3,75 J. It is not altered in the air. When 
 heated in a crucible till it is beginning to melt, it ex- 
 periences no alteration. It remains fixed even in a great 
 fire as long as the crucible is covered ; but the moment 
 it is uncovered the acid rifes unaltered in a white fmoke. 
 It dilTolves in 570 parts of water. The folution red- 
 dens turnfole ; nitric acid does not affeft it, but fulphu- 
 ric and muriatic acids diffolve it by the afiiftance of 
 heat. 
 
 It may be prepared by treating the ore of molybde- 
 num with nitric acid, and walhing the acid when form- 
 ed in water. 
 
 When combined with potafs, it forms a colourlefs 
 fait. 
 
 Mixed with filings of tin and muriatic acid, it imme- 
 diately becomes blue, and precipitates flakes of the fame 
 colour, which difnppear after fome time, if an excefs of 
 muriatic aci<l has been added, and the liquor affumes a 
 brownifh colour. 
 
 With the folution of nftrat of lead it forms a white 
 precipitate,, foluble in nitric acid. 
 
 When mixed with a little alcohol and nitric acid, it 
 does not change its colour. 
 
 With a folution of nitrat of mercury, or of nitrat of 
 filver, it givts a white flaky precipitate. 
 
 With the nitrat of copper it forms a greenilh preci- 
 pitate. 
 
 With folutions of fulphat of zinc, muriat of bifmuth, 
 rauriat of antimony, nitrat of nickel, muriats of gold 
 and platinum, it produces white precipitates when thefe 
 folutions do. not contain an excefs of acid. 
 
 When melted with borax, it gives it a bluilh co- 
 lour. 
 
 Paper dipt in this acid becomes in the fun of a beau- 
 ■ tiful blue colour ||. 
 
 Sulphur is capable of partly decompofing it by heat. 
 Its compounds are called molyhdats. 
 Its af&nities are unknown. 
 
 Part II. 
 
 Sect. XXXVI. Of Chrcmlc JciJ. 
 
 In the year 1770, Mr Pallas difcovered in the gold" , 
 mine of Berefof, near Ekatcrimbourg in Siberia, a mi- ^,.jfyf„ ,jf 
 neral of a red colour, with a Ihadeof yellow, cryftallizedthe rcdleid 
 in fmall acute angled quadrangular prifms, fometimes'^' Sibeti*, 
 fmooth, fometimes longitudinally ftreaked, and often 
 hollow. Mr Macquart, proftfTor of medicine at Paris, 
 who in 1783 had been fent to the north by the French 
 government in order to colleft mineralogical informa- 
 tion, brought with him a quantity of this mineral, which 
 has been diftinguifhed by the name of red lead ore of Si- 
 beria, and in i789analyfed four ounces of it along with 
 Mr Vauquelin, They found it to contain, 
 
 Lead - - 36^ 
 
 Oxygen - - 57|. 
 
 Iron 
 
 Alumina - 
 
 '1 
 241- 
 
 2 
 
 100, 
 
 and a little filvtr *. * Ann de 
 
 Mr Bindheim of Mofcow analyfed it foon after, and ^'"'"- '• 
 found it to contain, ^°'' 
 
 Lead 
 
 Molybdic acid 
 Nickel 
 
 Oxide of iron 
 Air and water 
 Silica 
 
 60 
 11,66 
 
 5.66 
 
 I 
 
 5 ■ 
 
 4.5 
 
 87,82 
 
 and a little copper and cobalt f. f Bert. 
 
 Vauquelin examined it again in 1797, and found '5'e* >v, 
 that all the former analyfes were inaccurate. ayii. 
 
 A hundred parts of this mineral, reduced to a fine 
 powder, were mixed with 300 parts of the faturated 
 carbonat of potafs, and about 4000 parts of water ; and 
 this mixture was expofed for an hour to a boiling heat. 
 He obferved, ift, that when thefe matters began to aft 
 upon each other there was produced a ftrong effervef- 
 cence, which continued a long time ; 2d, that the o- 
 range colour of the lead became a brick red ; ^d, that 
 at a certain period the whole matter feemed to dilTolve } 
 4th, that in proportion as the effervefccnce advanced 
 the matter reappeared under the form of a granulated 
 powder of a dirty yellow colour ; jth, that the liquor 
 alTumcd a beautiful golden yellow colour. When the 
 effervefcence had entirely fubfided, and appeared to have 
 no longer any aftion on the fubftances, the liquor was 
 filtered, and the metallic dull coUefted on the paper. 
 After being walhed and dried, it weighed no more than 
 78 parts: the potafs, therefore, had taken fromit22part5. 
 
 He poured upon the 78 parts juft mentioned fome 
 of the nitric acid, diluted in 1 2 parts of water, which 
 produced a briilt effervefcence. The greater part of 
 the matter was diffolved : the liquor affumed no colour, 
 and there remained only a fmall quantity of powder of 
 an orange-yellow colour. The liquor of the refiduura 
 was feparated by the help of a fyphon, the matter wafh- 
 ed feveral times, and the wafhings united with the firft 
 liquor. This reliduum, dried, weighed no more than 
 14 parts : from which it follows, that the nitric acid 
 had dilToived 64. 
 
 He again mixed thefe 14 parts with 42 parts of the 
 carbonat of potafs and the neccffary quantity of water, 
 
 and
 
 Part II. 
 
 S57 
 And difco 
 very of 
 chromic 
 
 Mid. 
 
 C H E M 
 
 and then treated them as before, and the phenomena 
 were the fanne. The liquor, after being filtered, was 
 united to the former ; and the refiduum, walhed and 
 dried, weighed no more than two parti, which were ftiU 
 red lead, and therefore thrown away. 
 
 The two nitric folutions, united and evaporated, pro- 
 duced 92 parts of nitrat of lead, cryftallized in oftahe- 
 dra, perfe(?Hy white and transparent. Thefe 92 parts 
 of nitrat of lead, dilTolved in water, were precipitated by 
 a folution of the fulphat of foda. This produced 81 
 parts of the fuljihat of lead, which were equivalent to 
 56,68 of metallic lead. 
 
 The alkaline liquors were found to contain a fait com- 
 pofed of potafs combined with a peculiar acid, which 
 Mr Vauquelin afterwards called chromic acid. 
 
 Thefe liquors, fubjefted to evaporation until a faline 
 pellicle was formed on their furface, produced, on cool- 
 ing, yellow cryftals ; among which there was a carbonat 
 of potafs, not decompofed. Thefe cryllals, dilTolved in 
 water, and the folution united with the mother-water, 
 the whole was mixed with weak nitric acid until the 
 carbonat of potafs was faturated. The liquor then 
 had a very dark orange-red colour. Being united with 
 a folution of the muriat of tin, newly made, it Crft af- 
 fumtd a brown colour, which afterwards became green- 
 iih. Mixed with a folution of the nitrat of lead, it im- 
 mediately produced the red lead. Lailly, evaporated 
 fpontaneoufly, it produced ruby-red cryftals, mixed with 
 cryftals of the nitrat of potafs. Ninety-eight parts of 
 this mineral, decompofed as above-mentioned, having 
 produced 81 parts of the fulphat of lead, 100 parts 
 would have given 82,65, which are equivalent to 57, t 
 of metallic lead. " But admitting, as experiment proves 
 (fays Mr Vauquelin), that lOO parts of lead abforb, in 
 combining with acids, 12 parts of oxygen, the 57,1 of 
 metallic lead ought to contain in the red lead 6,86 of 
 this principle, and we ought to have for the minerali- 
 zing acid 36,4. 
 
 Chromic acid cryftallizes in the form of elongated 
 prifms of a ruby colour. 
 
 When mixed with filings of tin and the muriatic acid, 
 it becomes at firil yellowifh brown, and afterwards af- 
 fumes a beautiful green colour. 
 
 Wlien mixed with a little alcohol and nitric acid, it 
 immediately affumes a bluilh green colour, wliich pre- 
 ferves the fame fhade even after deficcation. Ether 
 alone gives it the fame colour. 
 
 With a folution of nitrat of mercury, it gives a pre- 
 cipitate of a dark cinnabar colour. 
 
 With a folution of nitrat of filver, it gives a precipi- 
 tate, which, the moment it is formed, appears of a beau- 
 tiful carmine colour, but becomes purple by expofure 
 to the light. This combination, expcfed to the heat 
 of the blow-pipe, melts before the charcoal is iiiflamedj 
 It affumes a blackilh and metallic appearance. If it 
 be then pulverifed, the powder is ftill purple ; but af- 
 ter the blue flame of the lamp is brought in contaft 
 with this matter, it aflumes a green colour, and the fil- 
 ver appears in globules difleminated throughout its fub- 
 ftance. 
 
 With nitrat of copper, it gives a cbefaut red precipi- 
 tate. 
 
 With the folutions of fulphat of zinc, muriat of blf- 
 muth, muriat of antimony, nitrat of nickel, and muriat 
 of platinum, it pruduces yellowifti precipitates whea 
 
 I S T R Y. 34r 
 
 thefe folutions do not contain excefs of acid. With Chromic 
 muriat of gold, it produces a greenilh precipitate. , "^^ • , 
 
 When melted with borax or glais, it communicates * 
 to them a beautiful emerald green colour. 
 
 Paper impregnated with chromic acid affumes in the 
 light a greenilh colour. 
 
 Wiien mixed with muriatic acid, the mixture was 
 capable of diffolving gold like aqua regia ; when this 
 mixture of the two acids is diftilled, oxy-muriatic acid 
 is diiengaged, and the liquor affumes a very beautiful 
 green colour. 
 
 Sulphuric acid, while cold, produces no effeiSl upon it ; 
 but when warmed, it makes it affume a bluilh green co- 
 lour, probablyby favouring the difengagement of oxygen. 
 
 When this acid is heated along with charcoal, it is 
 reduced to the metal called chromum. It is therefore 
 compofed of this metal and oxygen. From Vauque- 
 lin's experiments, it appears to contain one part of 
 chromum and two parts of oxygen. 
 
 Such are the properties of tljis acid, as far as they 
 have hitherto been difcovered. Vauquelin is the only 
 chemift who has examined it ; and from his memoir the 
 above account has been taken *. * Ano.dt 
 
 Cbim. xxir. 
 
 The four laft defcribed acids are called metallic aciJi, phH^jopkkal- 
 becaufe they are compofed of metals and oxygen. Mog^-^im, 
 
 It is believed that moft of the metals, we would ra-'-^?';- ^"d 
 ther fay of the metallic oxides, are capable of being 5^^- 
 converted into acids by being combined with oxygen. Metallic 
 It is certain that this is the cafe with platinum ; andaciJe. 
 Hermftadt, by diftilling nitric acid off tin, converted 
 it into a white mafs, foluble in three parts of water, 
 which has been called y/ann/c acid\. Several -maxi. oi \ Ann. ie 
 the metallic oxides aft the part of acids : But no com- Chim. iv. 
 plete fet of experiments on this important fubjeA has '*^' 
 yet appeared. 
 
 Chap. VI. 0/" Affinitt. 
 
 5 60 
 
 The meaning of the word affinity has been already I'"P"r"nce 
 explained; and it muft appear evident, from the ufe"'^ '''''"''''" 
 which has been made of it in this article, that the con- 
 fideration of the nature of affinity is the moft important 
 part of chemiftry. While its laws are unknown, che- 
 miftry is not a icience, but a wildernefs of fafts with- 
 out beauty or regularity : every thing is equally per- 
 plexing and inGornprchenfible. The chemift, inftead of 
 being able to trace the operations of Nature, is loft in ' 
 an endlefs maze of uncertainty, without a guide to con-- 
 duft him, or a ray of light to illuminate his Iteps. It 
 is the knowledge of affinity which difpels the dark- 
 nefs, I'emoves the confufion, (liews us the order which 
 fubfifts in all the phenonvcna of nature, points out their ' 
 dependence on one another, and enables us to diredl 
 them as we think proper, to make them fubfervient to 
 the improvement of the arts, and thus to render them 
 the minifters of our comforts and enjoyments. j^r 
 
 I. When two bodies are united together by affinity,'' tJiiitcj 
 how fniall a portion foevcr of the compound we exa- ■"!"'"' ''*''"" 
 mine, we (hall always find it to contain both of the in-., I5 " 
 gredie'nts. From this it is evident, that affinity com- 
 bines bodies, particle witii particle. 
 
 By particles we do not mean wliaC philofophers have 
 called atoms, or the fmalleft parts into which it is^pof- 
 fible to divide matter ; but the fmalkft parts which 
 
 nKvke-
 
 343 CHEMISTRY. Part 11, 
 
 Aflini-y. make an integraril of any fubftance. Water, for in- parently in contaft ? or ftippofing that it does a<ft, how Affirity. 
 
 ^■""^""^ ftanctf, confifts of oxygen and hydrogen ; but when we can they account for the phenomena of affinity ? If ■~~V— ' 
 
 fpeak of a particle of water, we do not mean the oxy- barytes be prefented to a compound of fulphuric acid 
 
 gen or the liydrogcii feparately, but the fniallcft pof- and potafs, the acid immediately leaves the alkali and 
 
 fible qir^nlity of thefe comi)iiied in fuch a manner ab to combines with the earth: But had gravitation been 
 
 forra .vater. It is the integrant particles of bodies which the only power acting, ought not the barytes to have 
 
 are united by affinity. Thus fulphuric acid is conipo- united with the fulphat of potiifs without producing 
 
 fed o* fulphur and oxygen combined together ; and any decompofition ? 
 
 amn.oiiia, oi hydrogen and azot combined in the fame Thefe ilriking differences have convinced many phi- 
 
 manner. Now wlun fulphuric acid and ammonia com- lofophers, as they feem to have done Newton liimfelf, 
 
 bine, it is not their elements, fulphur, oxygen, azot, and that gravitation and affinity are difiicre nt fpecies of at- 
 
 hydrogen, which unite together, particle with particle, traftion. Let us not, however, embrace this conelu- 
 
 but the particles of the acid and the alkali as inte- fion vaguely, or without affixing a precife meaning to 
 
 grants. This is evident ; becaufe if thefe fubttances be our words. ^g^ 
 
 feparated from each other by means of a (Ironger af- Gravitation and chemical affinity are faid to be diffe- No pnCtivt 
 
 finity, they are found precifely in the fame itate as be- rent fpecies of attraclion. But what is attraftion ? It P""'" , '' "* 
 
 fore they entered into combination. — When the fub- is merely a general yai9, or that tendency which 'soi}-''^^j ^ 
 
 fiances which combine zre fimph, the ultimate and in- ferved among all the portions of matter towards each 
 
 teo-rant particles are the fame : But we are not certain other, but which exhibits very different appearances un- 
 
 that any of the bodies with which we are acquainted der different circnmftances. The tendency of matter 
 
 rgi is fimplc, in the ftricl and proper fenfe of the word. towards matter &t fciifwle diflances is called gravitation. 
 
 Opinions 2. What is this (j^w;/)' which unites bodies together ? and its laws liave been completely invelligated ; but 
 
 cftheolJ- 'pjjg older chemills thought that all folvents, or fub- neither that tendency, nor thefe laws, have been, or can 
 
 'i"^'' °'i' ft-''ncfs capable of didulvlng others, were compvjfed of be, (hewn to be f^-n/;V// to the exiilence of matter. Che- 
 
 uitv ' particles whicli had the form of wedges or hooks ; that mical affinity is the tendency of particles towards each 
 
 folution conliiled in the infi\iuation of thefe wedges or other at injenfible diflances, or when thefe particles are 
 
 hooks between the particles of the bodies to be diflol- mixed together ; and this tendency appears to be regu- 
 
 ved • and that chemital combination was merely the lated by laws different from thofe of gravitation. Like 
 
 linkino- of the different particles together by means of gravitation, it is merely an ohftrvid j'a£t ; and however 
 
 holes in one fet of particles, into which the hooks or different thefe fafts may appear to be, they are pro- 
 
 the wedges of the other fet were thrufl. Such explana- bably both brought about by the fame forces. It is 
 
 tions, aW'urd as they may appear, were fafiiionable among indeed true, that gravitation is directly as the maffes of 
 
 chemical philofophers till the days of Sir Ifaac Newton, matter, and inverfely as the fquares of the dillances of 
 
 who firll afctibed the chemical union of bodies to an thefe maffes; while the attradion, which is called cbe- 
 
 attradion between the particles themfclves. This ex- mical ajpnily, feenis to oblerve very different rules. But 
 
 planation, after a violent Itruggle on the part of the we have Ihewn eHcwhere (fee Op 1 ics, n*' (<z — 6S, En- 
 
 5, chemifts, has been at lafl unanimoufly adopted. cycl. ; and BoscoviCH in this Suppl.), that the fame 
 
 It is an at- Affinitv, then, is an attraction between the particles forces repel at one diftance and attract at another ; and 
 
 t ration be- of different bodies, by which they arc i/;«a'n towards that they may produce all the variaus phenomena ',f 
 
 ■*""=^"'''- one another, and kept united. This we take for grant- chemical afEnity. 
 
 particles ot ^j^ ^^^^ conlider as a fad, without pretending to ex- The difiBcuities to be accounted for in chemical af- 
 
 plain ho-Tu they come to be poiTeffed of this power, or fmities are their intenfity, their different degrees of 
 
 how they exert it ; both of which are evidently beyond ftrength, and their being eleftive, or, which is the fame 
 
 the reach of the human nnderftanding. thing, the capacity which one body has of difplaf ing 
 
 But though we cannot difcover the manner in which another, 
 affinity afts, we can fee, at leail, that it follows certain How come affinities, it may be aflied, to differ in in- 
 laws, and that tirey are invariable ; for fmiilar pheno. tenfity I Perhaps we might with propriety refer this 
 mena always* C)«fi}j,whei>the circumllances are the fame, querift to the ifudy of Bofcovich's curve; but as our 
 564 Now what are the laws which :iffinity follows ? There modern chemiils are not generally verfant in fuch flu- 
 Wheiher Jj 3 fpecies of attraftion which matter pofl'cfles, called -ijies, we beg leave to obferve, in this place, that we have 
 the fame „,avitation, the laws of which were inveltigated by Sir no proof whatever of abfolute contact between bodies, 
 vitatioir' I'**^" Newton. Is affinity the fume with gravitation, On the contrary, it is highly probable, we had almoil 
 or does it follow different laws ? faid demonffrable, that particles are in every indance at 
 Upon a flight view of thefe two attradlions, their fome diflance from one another. For, on the fuppofi- 
 phenomena appear very different. Gravitation afts at tion that two bodies were in aftual contact, their at- 
 very great diflances ; affinity not until the bodies are traftlon for each other would not only be as great as 
 mixed together : Gravitation adts on the whole mafs ; poffible, but as great as the attraftion of any other body 
 affinity only on the particles : Bodies gravitate to one for either of them could poffibly be : Confequently, it 
 another direttly as their maffes, and inverfely as the neceffarily follows, that, iince bodies chemically com- 
 fquares of their diflances. But how can affinity follow bined fan be feparated, they are not in aftual contaft(A); 
 thefe laws, when it does not ad till the bodies are ap- but if they are not in contad, their dillance from one 
 
 another 
 
 (a) Perhaps the following demonflration, which we borrow from the ingenious Mr Broughman, will render 
 
 Plate ti,is „jor£ evident. In lig. 7. let the body A have foi" P an [attradion which at the diftan^ of AP is propor- 
 XVII. tional
 
 Part FT. 
 
 C H E M 
 
 Affi'iity. anottior may vary in different c:ifes, and the force 
 "'~v~~'of alfinity will vary with the diilance. Here then 
 is a real'on wliy tlie affinity of different bodies va- 
 ries in ftrength. Sulphuric acid, for inllance, has a 
 tlronger affinity for barytes than for lime; becaule 
 when tlie combinations are formed, the diftance between 
 the acid and barytes is iiot fo great as that between the 
 acid and iime. 
 
 But why do the diftances differ? If afKnity be the 
 fame with gravitation, it niuil tend to bring the particles 
 nearer one another : And what then prevents the lime 
 from approaching as near the acid as the barytes does ? 
 We reply, the Ji;;ure of its parlulfs. This anfwer was 
 firll given to the quellion by Bnifon, and it is fully ade- 
 quate to folv.e the dilficulty. The particles of bodies, 
 indeed, are a great deal too nunute for us to difcover 
 their figure by adual infpedion ; but the phenomena 
 of ^ryllallization fhew us that this diil'erence actually 
 exiils. 
 
 The crvftals of every body alTume^a peculiar figure. 
 Now as thefe cryltals are all formed in the fame man- 
 ner, and by the fame law, it is impofTible to conceive 
 ' any other reafon for their variety but the difference in 
 the form of the particles which compofe them. 
 
 But why does one body difplace another ? When a 
 particle of barytes is brought within a certain dillance 
 ot a particle of fulphuric acid and lime combined toge- 
 ther, affinity aits and draws them nearer to one ano- 
 ther ; and the barytes, from its figure, approaches near- 
 er the acid than the lime could, and forms with it a 
 compound, the figure of which is fuch, relatively to that 
 of the lime, that they cannot approach within a fmall 
 enough dillance of each other to counteradl the attrac- 
 tion of the earth. Accordingly no compound is form- 
 ed ; for all that is meant by two particles having form- 
 ed a con\pound, is, that their attraftion for each other 
 is greater than the attraftion of the furrounding bodies 
 for either. 
 
 Having thus feen that none of the phenomena of n/"- 
 
 qusntly It Jimty are inconliftent with their refulting from the fur- 
 
 . ^rj "."^ces which brinsj about the phenomena of gravitation, 
 
 as the/tfir«, we have a riglit to concfude, that it is at ieaft fiigtily 
 
 probable, that all the motions of the corporeal woild are 
 
 produced by the fame power which, though not efTen- 
 
 tial to matter, was imprefled upon every atom of it by 
 
 the Great Creator when he formed this univerie ; and 
 
 that as the effects of this power are modified according 
 
 to the fituation of the bodies on which it acts, they are 
 
 known by the different names of gravity, adhefion, co- 
 
 hefioH, and ajjinity. 
 
 Gravity is the attraflion between bodies fo diflant, 
 that the maffes alone influence the refult, and that the 
 
 586 
 Confe- 
 
 IS TRY. 343 
 
 power may be confidered as placed in the centre of the Affinity, 
 attrafllng bodies. '• " 'v ^ 
 
 Adhesion fuppofes a diflance too fmall for our 
 fenfes. It has been demonllrated to be proportional to 
 the number of touching points, which depends upon the 
 figure of the particles that form the bodies. 
 ' CoHtsiON takes place only between particles of the 
 fame nature. Thefe, inllcad of touching only in one 
 fuperlicics, as In adhefion, touch In every point where 
 their figure will allow contaCl ; confcqueiuly the force 
 of cohefion alfo mull <lepend upon the figure of the 
 particles. 
 
 Affinity unites bodies of a different nature, not 
 merely by one fupeificies, as adhefion does, but particle 
 to particle, like cohflon ; and the tnofl perfccf contaA 
 is formed that tlie figure of the particles will admit. 
 Therefore, in this cale alto, the intenlity depends upon 
 the figure of the particles. ^ 
 
 3. If we- make the attempt, we fhall find that water Saturation 
 will not dilTolve any quantity of common fait that we ^^P'^hx^'^' 
 pleafe. Water which refufcs to take up any more is 
 faid to be fat urate J vith fait. Neither can we combine 
 any quantity of potafs with a given portion of fulphu- 
 ric acid : we may add as much of it as we pleafe, in- 
 deed ; but it we evaporate the liquid, in order to ob- 
 tain the fait In cry Hals, we fliall lind that only part of 
 the potafs has united with the acid, and that the refl 
 has cryflallized feparately. From thefe examples, it 
 muft appear evident, that bodies combine with one an- 
 other by affinity only.in certain proportions ; or, which 
 is the fame thing, that a determinate number of par- 
 ticles of each of the ingredients goes to the formation 
 of an integrant particle of the compound, and that into 
 this integrant no additional particles of either ingredient 
 can be admitted. Let us fuppofe, for inflance, tbat the 
 particles of fulphuric acid are tetrahedrons, and that 
 the particles of potafs are of fuch a form, that one of 
 them can attach itfelf to each of the fides of tlie acid 
 particle : In that cafe an integrrant particle of fulphat 
 of potafs would be compofed of five particles, one of 
 acid and four of alkali ; for it is evident, that jufl four 
 particles of potafs would combine with every particle 
 of acid, and that the acid would then be faturated, or, 
 which is the fame thing, would be incapable of recei- 
 ving any more alkaline particles into combination with 
 it. Let us fuppofe now, that there is jufl as much pot- 
 afs as faturates the acid ; if more acid be poured in, it 
 cannot enter into combination with the potafs, be?aufe 
 all the potafs is already combined with acid. 
 
 Thus it appears evident, from the nature of affinity, 
 that the ingredients in every combination mufl mutual- 
 ly ya/urtjiff each other, and that no more of either can 
 
 be 
 
 tional to PM; then let P move towards A, fo as to come to the fituation P', and let the attraftion here be P'M'; 
 as it is continual during the motion of P to P', MM' is a curve line. Now in the cafe of the attraftion 
 of bodies for one another, PM is lefs than P'M' ; and confequently MM' does not ever return into itfelf, 
 and therefore it mufl: go ad infinitum, having its arc between AB and AC, to which it approaches as 
 afymptotes, the abfcifla always reprefenting the diftance, and the ordinate the attradlion at that diflance. Let 
 P' now continue its motion to P'', and M' will move M" ; and if P" meets A, or the bodies come into perfedi 
 Gontaft, P"M'' will be infinite ; fo that the attraftion being changed into cohefion will be infinite, and the 
 bodies infeparable, contrary to univerfal experience ; fo that P can never come nearer to A than a given Ai^ 
 ftance. Nicholfoii's Journal, I. 555. '
 
 3H 
 
 CHEMISTRY. 
 
 MttheJ. 
 
 i. j6o. 
 
 be admitted into tlie compound than what is neceflary 
 ' to piodiice this faturation. It follows equally, that 
 there can h-j ro union without faturation, except there 
 be a deficiency in fome one of the in^jredionts : For 
 f'tppolniir that there is a fufficient miniber of panicles 
 of potafs, and that every particle, of fulphurlc acid re- 
 quires four of them, as bilore, for faturation, the very 
 fame caufe that produces the union of one, two, or 
 three panicles of potafs with a particle ot acid, muft 
 produce the union of all the four. 
 
 Even w hen there is a deficiency of one of the ingre- 
 dients, faturation muft equally take place ; for tliofe 
 particles of acid that happen to be reared the alkali 
 muft ftill be faturated ; becaufe the affinity of all the 
 acid particles for alkali was originally equal, and the 
 difference of the dlilance mull give the iuperiority to 
 thofe that are neareil ; and thofe particles of acid that 
 are once faturated with potafs cannot be deprived of 
 it bv any of the other particles, otherwife the affinity 
 of fome particles of fulphuric acid for potafs would be 
 greater than that of others ; which is abfurd. 
 
 It will no doubt be objeAed to all this that there 
 are innumerable iuftances of additional portions of fome 
 one of the ingredients being received into a compound 
 after faturation, and that fome fubftances feem to be 
 equally well faturated with different dofes of another. 
 Oxvgen, for inftance, combines with azot in three dif- 
 ferent proportions, and forms nitrous gas, nitrous acid, 
 and nitric acid. The metals, too, form, in the fame 
 manner, different oxides; and a great many inftances of 
 the fame kind occur among the neutral falts. 
 
 But it ousjht to be remembered, that the conclufions 
 againft which thefe objeftions are urged, are conle- 
 quences deduced, we think fairly, from a propofition 
 which we confider as demonflrated, that ajjimty h a 
 fpecies of uttrnSlon (b). Thefe phenomena cannot there- 
 fore be admitted as valid ohjettions, except it can be 
 (hewn that they are really iticompalihle with thefe con- 
 clufions. Now that this is not the cafe, has been fhewn, 
 in the moft fatisfaftory manner, by Morveau*. Thele ap- 
 parent exceptions are owing toan affinity which exifts be- 
 tween the compound as an integrant and one of its ingre- 
 dients, and are not inftances of various degrees of fatura- 
 tion, but of the formation ot new compounds. According 
 to this vei-y ingenious idea, which, we believe, firft ori 
 ginated with Bergman, and was firft feen in its full ex- 
 tent by Morveau, we have formerly explained in what 
 manner the various metallic oxides are formed ; the firft 
 oxide is a compound of the metal and oxygen ; the fe- 
 cond, of the firft oxide and oxygen ; the third, of the 
 fecond oxide and oxygen ; and fo on. In the fame 
 manner we have explained the various combinations of 
 azot and oxygen : and the explanation may eafily be 
 extended to every other cafe. Thefe apparent objec- 
 tions, then, are not incompatible with the above con- 
 
 < 
 
 Partir. 
 
 clufions, but perfe£lly confiftent with them ; and confe- -Aniiit)-. 
 quentiy they cannot be admitted as of any force. """"^ 
 
 There is one phenomenon, indeed, which proves, in- 
 dependent of thefe conclufions, that thefe coinbiiiations 
 are actually formed in the tnanntr we have fuppofed, 
 and which therefore merits particular attention. The 
 phenomcria is, that the affinity between tlie two funplc 
 fubftances is almnjl altvnyT greater than that between 
 the compound and any of its ingredients. The affini- 
 ty, for inftance, between azot and oxygen is greater 
 than that between nitrous gas and oxygen; and the af- 
 finity between nitrous gas and oxygen greater than that 
 between nitrous acid and oxygen : For if nitrous gas be 
 mixed with nitric acid, the whole is converted into ni- 
 trous acid ; but no change whatever is produced when 
 nitric and nitrous acids, or nitrous gas and nitrous acid, 
 are mixed : and every fubftance which is capable of 
 decompofing nitrous gas is capable alfo of dtcompoiing 
 nitrous and nitric acids ; but many fubftances are capa- 
 ble of decompofing nitrous and nitric acids which have 
 no effeft upon nitrous gas. In the lame manner, the 
 affinity between fulphur and oxygen is greater than that 
 between lulphurous acid and oxygen : for when fulphur 
 is mixed with fulphuric acid, the whole is converted 
 into fulphurous acid ; but no change takes place when 
 fulphur and fulphurous acid, or fulphurous and fulphu- 
 ric acids are mixed together. A great many inftances 
 of the fame kind might cafily be produced, if thefe 
 were not fufficient to tfi.ablifli the point. This curious 
 fadf affords a very llrong proof that the bafes, as well 
 as the quantity of oxygen, is different in alr.ioft all the 
 vegetable acids. Did the lartarous, oxalic, and acetous 
 acids, for inflance, confift of the fame bale with various 
 dofes of oxygen ; were the tartarous compofed of the 
 bafe and oxygen ; the oxalic, of tartarous acid and 
 oxygen ; the acetous, ot oxalic acid and oxygen — in 
 that cafe, a mixture of acetous and tartarous acids ought 
 to form oxalic acid; but that this does not happen, any 
 one may convince himftlf by actual experiment. 
 
 We do not mean to affirm that this fa£l, though it 
 is certainly very often true, holds in all cafes ; in fome, 
 perhaps, the reverie may be true,- though we do not 
 recoUeft at prefent any inftance of that kind. ,„ 
 
 4. Since the affinity of almoft every two bodies for Of the 
 each other differs in Jlrenglh from that between every 'tie»gth 
 other two, it becomes an important problem to Jf/^/-- " "''?' 
 mine the Jlrength vf every ojjinity in numbers. The folu- 
 tion of this problem would give a clearnefs and preci- 
 fion to chemiftry equal to that of any other branch of 
 natural philofophy whatever, and enable it to advance 
 with a degree of rapidity hitherto thought unattainable. 
 No wonder, then, that this problem has occupied the 
 attention of fome of the moft eminent philofophers who 
 have dedicated their time to chemiftry. - 
 
 If the obfervations formerly made, in order to fhew Attempts 
 
 that 10 afceruin 
 it. 
 
 (b) Were any farther proof of this propofition required, we would obferve, that cohefion afts as an antagonift 
 to affinity, and may be often rendered fo ftrong as to prevent affinity from afting with efficacy. Thus alumina 
 and jargonia, when fufficiently heated, become infoluble in acids, without undergoing any other alteration than 
 that of an increafe of cohefion by their particles being brought nearer each other ; for deftroy this cohefion, 
 and they become as foluble as ever. Now it follows from this, that if cohefion be attraSion, fo muft affinity. 
 The experiments of Morveau, to be afterwards mentioned, demonftrate, that adhefion and affinity are produced 
 by the fame caufe : Confequently, if adhefion be attraftion, fo muft affinity. 
 
 I
 
 <;7o 
 ByWcnzel 
 
 C H E M 
 
 that the diiTcMcnoe in tlu' ftrenpfth of afRuitics depends 
 ' upon the different forms of the panicles xvhicli have an 
 affinity for eacli other, be conclufive, it is evident that 
 the certain method of learning the ftrengtli of affinities 
 would be to difcover the forms of the parricles of all 
 hjdies. But no method has hitherto been difcovered 
 by whieli it is puffible of becoming acquainted with the 
 figure of the particles of bodies. The experiments in- 
 deed of the Abbe Hauy (afterwards to be defcrlbed) 
 point out a method by which the primsry lignre of 
 cryftals may be inveftigated with a good deal of plau- 
 fibillty ; but this leaves the knowledge of the figure of 
 the particles which compofe theie cryftals lUU uncertain. 
 
 As nobody, therefore, has attempted to take this 
 road, in order to calculate the ftrength of affinities, let 
 us at prefent confider the different methods which have 
 been propofed for that purpofe, that we may fee whe- 
 ther any of them will aniwer the end intended. 
 , Wenzel fuppofed that the time taken by one body 
 to diflblve another is a meafure of the affinity which 
 fubfifts between them. Rut the hypothefis of that in- 
 genious philofopher will not bear the teft of examina- 
 tion ; for the time of folution evidently depends upon 
 circumftances unconnefted with affinity. The cohefion 
 of the body to be diffolved, and the nature of the com- 
 pound formed, mull occafion very great differences in 
 the time of folution of different bodies, even on the fup- 
 pofition that their affinities were all the fame. 
 
 Fourcroy propofed to meafure the affinity of bodies 
 by the difficulty of feparating them after they are com- 
 bined : but we have no method for meafuring this dif- 
 ficulty. LavoiCer and De la Place, indeed, propofed 
 caloric for this purpofe ; but there are many compounds 
 ■which caloric cannot feparate ; and it never produces a 
 feparation except by means of its affinity for one or 
 other of the ingredients of the compound. Before ca- 
 loric, therefore, could be employed as a meafure, it 
 would be neceffary to know exactly the ilrength of its 
 own affinity tor every other fubllance ; which is juft a 
 cafe of the problem to be refolved. 
 
 Macquer fuppofed that the affinity of bodies for one 
 another was in the compound ratio of the facility of 
 their union and the difficulty of their feparation : But 
 as we are in poffeffion of no method of afcertaining ei- 
 ther of thefe, it is evident that this theory, even allow- 
 ing it to be jull (which it certainly is not), could be 
 of no ufe for affifting us to calculate the force of affi- 
 nities. 
 
 Another method has been propofed by the diflin- 
 gulfhed philofophical chemifl Mr de Morveau (c). 
 
 In 1713 Dr Brook Taylor made fome experiments 
 on the adhefion of furfaces ; and concluded from them, 
 that the force of adhefion might be determined by the 
 weight neceffary to produce a feparation. But in 1772, 
 Meffrs La Grange and Cigna, obferving that the fur- 
 faces of water and oil adhere together, and taking it 
 for granted that thefe two liquids repel each other, 
 concluded, in confequence, that their adhefion was not 
 owing to attradion ; and hence inferred, that adhefion, 
 in general, is always owing to the preffure of the at- 
 
 SuppL. Vol. I. Part I. 
 
 I S T 11 Y. Part II. 
 
 mofphere. This conclufion induced Morveau to c:;a- Aflum)-. 
 mine the fnbjefl : he found that adhefion was nut af- » ' 
 fc8e,l by the preffure of the atmofphere ; for it required 
 the" fame weight to feparate a di(l< of glafs (30 lines In 
 diameter) from the furface of m'.rcury in the open air, 
 and under an cxhaulled receiver. He obferved thit 
 the fame diflc adhered to water with a force of 2;S 
 grains, and to the folution of potafs, though denfer, 
 only with a force of 210. This refult not only proved 
 that adhefion was owing to attradlion, but made him 
 conceive the poffibllity of aj)plylng this method to the 
 calculation of affinities: For the force of adhefion be. 
 ing neceffarily proportional to the points of contafl, 
 and this being the cafe alfo with affinity, it is evident 
 that the adhefion and the affinity between the fame fub- 
 ftances are proportional, and that therefore the know- 
 ledge of the one would fiunlffi us with the ratio of the 
 other. 
 
 Struck with this idea, he conftrufted cylinders of dif- 
 ferent metals, perfeftly round, an inch in diameter and 
 the fame in thicknefs, and having a fmall ring in their 
 upper furface, by which they might be' hung exadily in 
 equilibrium. He fufpended thefe cylinders, one after 
 another, to the beam of a balance ; and after counter, 
 poifing them exaftly, applied them to a q\iantity of 
 mercury placed abcut two lines below thcni, making 
 them (lide along its furface, to prevent any air from 
 lodging between them and the mercury. He then 
 marked exaftly the weight neceffary to overcome their 
 adhefion, taking care to change the mercury after 
 every experiment. The table of the refults is as fol- 
 lows : 
 
 Gold adheres to mercury with a force of 
 
 Silver, ...... 
 
 Tin, 
 
 Lead, 
 
 BIfmuth, 
 
 Platinum, 
 
 Zinc, 
 
 Copper, 
 
 Antimony, 
 
 Iron, 
 
 Cobalt, 
 
 446 gr. 
 
 429 
 
 418 
 
 397 
 
 372 
 
 282* 
 
 204 
 
 142 
 
 J 26 
 
 115 
 
 8 
 
 • Morvma, 
 Jinn de 
 dim. XXV, 
 
 10. 
 
 The differences of thefe refults cannot be owing to 
 the preffure of the air, which was the fame in all ; nor 
 do they correfpond to the deniities of the metals ; nor 
 can they be owing to accidental differences in the po- 
 lifli of the cylinders, for a plate of rough iron adheres 
 more itrongly to mercury than one of the fame diame- 
 ter exquifitcly polilhed ; — but they follow precifely the 
 order of affinity, and therefore may be confidered as the 
 meafure of the ftrength of the affinity between thefe 
 different metals and mercury. They furnilh us alfo 
 with a convincing proof that affimiy is atlradion, and 
 the fame fpecies of attraction with adhefion ; and that 
 therefore, if the one be reducible to gravitation, fo mufl; 
 the other. 
 
 Mr Achard, convinced of the importance of Mr Mor- 
 
 vean's obfervations, made a great many experiments on 
 
 adhefion, and publilhed the refult of them in 1780. He 
 
 X X proved 
 
 (c) Now Mr Guyton : we have ufedthe old name all along in the text to avoid ambiguity.
 
 346 CHE M I 
 
 Affinity, proved that the force of adhefion was not affeded by 
 ' " K alterations In the height of the barometer, but that its 
 force became weaker as the heat of the fluid increafed 
 (d) ; and that the temjieralure remaining the fame, the 
 force of adhefion increafed in the fame ratio with the 
 furfaces of the adhering bodies. He made about 6co 
 experiments on the adhefion of different folids and fluids, 
 proved that the force of adhefion did not depend on the 
 denfuies of the adhering bodies, nor on the different 
 cohefive force of the fluids ; and, after a laborious cal- 
 culation, concluded that it depended on the figure of 
 the particles of the adhering fluid and folid. 
 
 Thefe experiments and calculations of Mr Achard 
 are certainly of importance ; and we would have given 
 them here, had not the objeds of them been fubftances 
 which can furnifh but few data for calculating the force 
 of affinities. 
 
 This method of meafuring the force of affinities feems 
 to be an accurate one, and if it could be applied to 
 ever)' cafe of affinity, would, in all probability, enable 
 us to folve the problem whicli we are now confidering: 
 But, unfortunately, its application is very limited, be- 
 ing confined to thofe cafes alone in which one of the 
 bodies can be prefented in a fluid, and the other in a 
 folid ftate. Nor can it be applied indifcriminatcly to 
 all thofe cafes ; for whenever the cohefiori of any li- 
 quid is much inferior to the force of its adhefion to any 
 folid, the feparation takes place in the particles of the 
 hquid itfelf, and confequently we do not obtain the 
 meafure of its adhefion to the folid, but of its own co- 
 hefion, and that, too, imperfeftly. Thus, for inftance, 
 Mr Achard found that fealing-wax adhered to vyater 
 with a force of 92 grains, and to alcohol only with a 
 force of 5?|ths ; yet we know that fealing-wax has a 
 greater affinity for alcohol than for water ; becaufe al- 
 cohol dilfolves it, which water is incapable of doing. 
 The diff'ercnce in the refult in this inftance was evi- 
 > dently owing to the fmaller cohefion of alcohol. Mr 
 
 Morveau's method muft therefore be confined to thofe 
 eafes in which the cohefion of the hquid is ftronger 
 than its adhefion to the folid, which may be known 
 by the furface of the fohd not being moiftened ; and 
 to thofe in which the cohefion is not much inferior 
 to the adhefion ; for then, it is evident, that the force 
 of cohefion will be increafed as tiie force of adhefion. 
 Let us fuppofe, for inftance, that two folids, A and B, 
 are made to adhere to the furface of a liquid, and that 
 A can only form an adhefion with 50 particles of tike 
 liquid, whilft B adheres to 100 ; it is evident that a 
 much fmaller force will deftroy the cohefion of the 50 
 particles to which A adheres with the reft of the li- 
 quid, than what will be required to deftroy the cohe- 
 fion of the '100 particles united to B with the fame 
 
 • Mirvwu, liquid*- r ^, ■.:, 1, u V J 
 
 £„cyc. Mc- The method of Mr Morveau, then, may be applied 
 tbod. Chim. ^Jth accuracy in both cafes ; and luhen they occur can 
 Adhc. ^i^jy ^^ determined by experiment. It cannot, how- 
 ever, be applied indifcriminattly even then ; for unlefs 
 the folid and the fluid be prefented in fuch a ftate that 
 
 S T R y. Part II. 
 
 no gas is extricated when the adhefion takes place, an Affinity, 
 accurate judgment cannot be formed of the force of ad- *"~~v~-~' 
 hefion. Wlien marble (carbonat of lime), for inftance, 
 is applied to the furface of fulphuric acid, there is an 
 extrication of gas, which very foon deftroys the adhe- 
 fion, and prevents an accurate refult. Were it poffible 
 to employ quicklime inrtead of marble, this would be 
 prevented ; or if this cannot be accompllflied, why 
 might not lime be employed, united with fome acid that 
 would not aifume a gafeous form, and at the fame time 
 has a weaker affinity than fulphuric acid for lime ? 
 Wliy miglit not the phofphat of lime, for inftance, be 
 ufed, wliich may be reduced to a ftate of hardnefs fuffi- 
 ciently great for the purpofe ? The extrication of gas, 
 during the application of metals to the furfaces of acids, 
 might be prevented by oxidating their furfaces. It is 
 true, indeed, this could not be done with all the metals, 
 on account of the nature of the oxide, but it might with 
 feveral ; copper, for inftance, and filver. It cannot be 
 doubted, that by thefe methods, and other contrivances 
 that might be fallen upon, a fufficient number of re- 
 fults might be obtained to render this method of the 
 greatcft importance. It is rather furprifing, therefore, 
 that it has never been profecuted. 
 
 Mr Kirwan has propofed another method of folving AndKiO" 
 the problem. While he was engaged in his experiments wan. 
 on the ftrength of acids, he obferved that the quan- 
 tity of real acid neccflary to faturate a given quantity of 
 each of the bafes, was inverfely as the affinity between 
 the refpefiive bafes and the acid ; and that the quan- 
 tity of each of the bafes neceffary to faturate a given 
 quantity of acid was diredlly as the affinity between the 
 bafc and the acid. Thus 100 grains of each of the 
 acids require more alkali for faturation than lime, and 
 more lime than magnefia, as may be feen in the foUow- 
 ins table : 
 
 1 
 
 574 
 
 100 grains fif 
 
 Potafs. 
 
 Soda. 
 
 Lime. 
 
 Anini. 
 
 Mag. 
 
 Alum. 
 
 Sulphuric acid 
 
 215 
 
 165 
 
 110 
 
 90 
 
 80 
 
 75 
 
 Nitric acid 
 
 215 
 
 16? 
 
 96 
 
 87 
 
 75 
 
 65 
 
 Muriatic acid, 
 
 215 
 
 158 
 
 89 
 
 19 
 
 71 
 
 55 
 
 art 
 /an. 
 
 He concluded, therefore, that the affinity between 
 acids and their bafes may be rtlimated by the quantity 
 of bafes neceffary for faturation. Thus the affinity be- 
 tween potafs and fulphuric acid is 215, and that be- 
 tween nitric acid and lime 96 *. ♦?*■/■_ 
 
 We have mentioned formerly, that the principle on Tnsn/.iyi^i 
 which Mr Kirwan calculated the ftrength of the acids 
 was founded on a miftake. It muit follow of courfe, 
 therefore, that the numbers which reiult from it muft 
 alfo be wrong. This Mr Kirwan has acknowledged, 
 and feems to have given up all thoughts of afcertain- 
 ing the ftrength of affinities by this method. But be- 
 fore it be abandoned altogether we wi(h the following 
 obfervations were confidered. ,_- 
 
 Bergman long ago eftabhfhed as a principle, under Attempt « 
 the name of a chemical paradox, that the Jlronger a«)/ remedy thi 
 fah -was, the lefs of any other it required for /aturation.^V Pi 
 Thus, according to him, 
 
 100 
 
 (d) Striftly fpeaking, this is owing not fo much to a decreafe of theTorce of adhefion, as of that of the co- 
 hefion of the fluid itfelf.
 
 Part II. 
 
 Ariii.ity. 
 
 CHEMISTRY. 
 
 100 parts of potafs require 78,5 Sulphuric acid, 
 
 64 Nitric, 
 
 51,5 Muriatic, 
 
 41 Carbonic, 
 177 Sulphuric, 
 135,5 Nitric, 
 125 Muriatic, 
 
 80 Carbonic. 
 
 loo parts of foda 
 
 347 
 
 ted by Morvcau *, evidently rtjfolvea itfelf into ttic two Affi nity. ^ 
 following : * F 
 
 1. A iafi requires t/je more of an acid for faturation ^,^,,^^-^ ' 
 thejlnnger its affuiity for that acid is. Ci/w.i. 597. 
 
 2. An acid requires the more of any bafe for fatura- 
 tlon the greater ajfiiii/y it has for that bafe. 
 
 In order to judge of tlie truth of the tirlt of thcfe pro- 
 pofitions, let us examine the following table, dra« n up 
 
 This propofition, which has been admirably illuftra- from the experiments of Bergman, Wenzcl, and Kirwan. 
 
 1 00 parts of 
 
 Bergman 
 Sul^^huric. N'.tric. 
 
 Muri.itic. 
 
 Wenzel. 
 
 Sulphuric. Nitric. 
 
 Muriatic. 
 
 Suljihuric. 
 
 KlRWAH. 
 
 Nitric. 
 
 Muriatic. 
 
 Barytes 
 
 '5.4 
 
 
 3c,8 
 
 
 
 
 
 
 
 Potafs 
 
 78,6 
 
 6+ 
 
 51.5 
 
 82,4 
 
 107,7 
 
 54 
 
 81,8 
 
 87.1 
 
 78,2 
 
 Soda 
 
 •75 
 
 135.5 
 
 lis 
 
 125,8 
 
 166,6 
 
 83 
 
 129.4 
 
 136,1 
 
 114,2 
 
 Lime 
 
 143.7 
 
 •34.4 
 
 7C.45 
 
 •47.74 
 
 •195,6 
 
 103,6 
 
 141 
 
 180 
 
 86 
 
 Magnefia 
 
 173.67 
 
 159,25 
 
 82,92 
 
 181,8 
 
 257.15 
 
 122,27 
 
 •70.5 
 
 255 
 
 104,275 
 
 Ammonia 
 
 
 
 
 142,42 
 
 201,22 
 
 96,25 
 
 •87.5 
 
 233 
 
 116 
 
 Alumina 
 
 211,11 
 
 
 220,2 
 
 77,7 
 
 68,7 
 
 38,6 
 
 
 
 
 It 13 evident at firft fight, that Bergman's experi- 
 ments correfpond exaftly with the propofition. To fa- 
 turate, according to him, 100 parts ot potafs, requires 
 78i6 of fulphuric acid, 64 of nitric, and 51,5 of mu- 
 riatic acid. There is only one deviation from the pro- 
 pofition in the whole table, and this regards barytes, 
 which, according to him, is faturated with i -,4 of 
 fulphuric and 3", 8 of muriatic acid. But Mr Morveau 
 has (hewn, by ftveral accurate experiments, that bary;. 
 tes requires much more fulphuric acid for Saturation 
 ^ P than Bergman fuppofed *. And Klaproth has fhewn, 
 
 Meilnd. that 100 parts of barytes require 49,2 of Urongfulphuric 
 CiiOT. i. 59i.acid for faturationj-. And Dr Withering's calculation \ 
 \ Chim. agrees almoft exactly with this ; nor does that of Four- 
 -"fr"' croy differ much from it f. Inifead of 15,4 of fulphuric 
 X Phil. acid, therefore, which, according to Bergman, are ne- 
 ?'ri7n,/:i784.ce(rai-y to faturate 100 of barytes, it (hould be 42,8. 
 \ Ann.d! The firft and laft columns of Wenzel and Kiruan's 
 
 ""■"■ •''experiments agree equally well with the propofition, but 
 the fecond deviates from it completely. Wenzel pro- 
 bably might have been mifled by the manner of per- 
 forming his experimentsj but the fame objedlion docs not 
 fccm to lie againft thofe of Kirwan. 
 
 It can fcarccly be doubted, however, to whatever 
 caufe the error is to be imputed, that the numbers in 
 the fecond column of Mr Kirwan's table are too large. 
 The following experiment of Morveau is fufficient to 
 fhew this. 
 
 According to Mr Kirwan's experiments, the propor- 
 tions of acid and alkali in the four following falts are as 
 under : 
 
 Sulpha«f potafs 1^;;^^^^ r'08,7 
 
 Sulphat of lime 
 NItrat of potafs 
 Nitrat of lime 
 
 100 
 80,6 
 
 100 
 
 83.33 
 100 
 
 34.4- 
 
 ("Acid 
 
 |_Lime 
 
 JAcid 
 
 \ Potafs 
 
 fAcid 
 
 [_ Lime 
 Now when fulphat of potafs and nitrat of lime are 
 mixed together, a double decompofition takes place, and 
 fulphat of lime and nitrat of potafs are formed. Let 
 thefe two falts be mixed together ; let the quantity of 
 fulphat of potafs be fuch, that the acid contained in it 
 amounts to 100 ; and let a more than fufficient quan- 
 tity of nitrat of lime be added, to faturate the fulphuric 
 acid with lime. It is evident that for that purpofe 80,6 
 of lime muft be prefent; and the quantity of nitric acid 
 combined with thefe 80,6 muft be 234,4. This quan- 
 tity would require for faturation 195,32 of potafs, but 
 there are only 108,7 in the mixture ; confequently 
 there ought to exill in the mixture, after the mutual 
 decompofition of the falts, 64,87 of nitric acid in a ftate 
 of liberty. Such would be the refult, provided Mr Kir- 
 wan's numbers were accurate ; but the faft is, that no 
 fuch excefs of acid exifts in the mixture f ; and confe-f Ann.d! 
 quently the quantity of nitric acid contained in nitrat of Ci/m. xiy. 
 lime is ftated too high by Mr Kirwan. Although *W' 
 therefore Mr Kirwan's tables do not coincide with the 
 propofition which we are confidering, this is not to be 
 confidered as a proof of its falfehood ; as there is rea- 
 fon, from the experiment above defcribed, to fufpedt 
 fome error in the data from which Mr Kirwan calcula- 
 ted the ftrength of the acids. 
 
 The truth of the fecond propofition may be judged 
 of by the following Tables : 
 
 Xx2 
 
 /fccording
 
 too paits of 
 
 A 
 
 Baryt. 
 
 646 
 
 ccord'mg to B 
 Horafs. Sola. 
 
 127,5 56,5 
 
 148,4 74,4 
 
 194 78 
 
 RRGfJAN. 
 Lime. Magn. 
 
 69,5 578 
 
 74,4 62,8 
 
 141,9 120,5 
 
 Amm. 
 
 42 
 
 Alum. 
 
 Snip, acid 
 Nitric acid 
 
 473 
 40 
 
 Mur. acid 
 
 324.7 
 
 CHEMISTRY. Part. IL 
 
 Table II. ^antUy of At'id netc^tuy to Saturate 100 Affinity, 
 Pulls of the fix Bafts. ' f-^ 
 
 According to Wsnzel. 
 100 parts oflByryf.Potaff. Soda. Lime. Magn. Amm. Alum, 
 
 Sulp. acid 
 
 Nitricacid 
 
 Mur. acid 
 
 120,8 
 
 92.7 
 
 83,8 
 
 79,16 
 
 60 
 
 1 19,2 
 
 67,2 
 
 51. T 
 
 96,5 
 
 55 
 
 38,8 
 
 81,7 
 
 70,2 
 
 49.7 
 103,9 
 
 128 
 
 147.' 
 259 
 
 According to Kirivan. 
 
 TOO part* o\ 
 
 Sulp. acid 
 
 Nitricacid 
 
 Mur. acid 
 
 Baryt 
 
 Potaf'. 
 
 .So.Ij. 
 
 122,2 
 
 77.2 
 
 112 
 
 73.8 
 
 168,6 
 
 '33 
 
 Lime. 
 
 70,4 
 
 55.5 
 
 112,7 
 
 57.3 
 
 39>2 
 89,9 
 
 Amm. 
 
 53.3 
 44.8 
 78,5 
 
 Alum 
 
 It appears that all the table of Bergman agrees with 
 the propofitioD except the numbers which correfpoftd to 
 fulphat of foda, fulphat of alumina, nitrat of h'me, and 
 muriat of foda, which the late experiments of Mr Kir- 
 wan have fufficiently {hewn to be inaccurate. 
 
 Wenzel's table correfponds exaftly, except the co- 
 lumns under ammonia and alumina, which Morveau has 
 proved to be inaccurate. 
 
 Kirwan's table correfponds exaftly, except with re- 
 gard to the quantity of ammonia neceffary to faturate 
 muriatic acid, which does not appear to have been ac- 
 curately determined by experiment. 
 
 Let us therefore take the truth of tbele two propo- 
 fitions for granted, and let us confidcr every deviation 
 from them as an error ; and let us lee whether they 
 will enable us to difcover the abfolute affinity of fal- 
 phuric, nitric, and muriatic acids, for their refpeftive 
 bafes- 
 
 Table I. family ef Bafe neceffary to Saturate 100 
 Parts of the three Acids. 
 
 100 parts 
 
 Bar) t. 
 
 233.3 
 258,4 
 324,7 
 
 Poial.-. 
 123,3 
 148,4 
 188,8 
 
 , Soda. 
 
 78,7 
 95.6 
 126,1 
 
 Lime. 
 68,3 
 
 74.4 
 
 1 r6,7 
 
 Ma>;n. 
 56,8 
 62,8 
 
 97 '3 
 
 Amm. 
 49.3 
 
 54.8 
 78,5 
 
 Sulph. acid 
 Nitric acid 
 
 IVIuriat. acid 
 
 lOo pans 
 
 Sul[-1.. acid. 
 
 Niinc at id. 
 
 Mur. acid. 
 
 Barytes 
 
 42,8 
 
 38,7 
 
 30.8 
 
 Potafs 
 
 81 
 
 64 
 
 52.9 
 
 Soda 
 
 126,7 
 
 101,4 
 
 79 
 
 Lime 
 
 145.7 
 
 134.4 
 
 87.5 
 
 Mngnefia 
 
 176,2 
 
 139.25 
 
 105,4 
 
 Ammonia 
 
 202,6 
 
 182,4 
 
 127,25 
 
 The firft of thcfe tables reprefents the affinity be- 
 tween the fame acid and its various bafes ; and the ie- 
 cond that of the bafes for the different acids. If it were 
 required to know the ratios of the affinity which diffe- 
 rent bafes have for any particular acid, the firll table, 
 fuppofing it accurate, would give it exadlly. In like 
 manner, if it were required to know the ratios of the 
 affinity of the acids for the various bafes, we would find 
 them in the fecond table. - 
 
 But if we wifhed to know what was the affinity he-Andtocen- 
 tween one acid and bafe, compared witli that between ftruifttablef- 
 another aeid and a different bafe; or if we wanted to of affinity, 
 have not the relative but the abfolute affinity between 
 two bodies — it is plain that we could not find it in either 
 of the tables ; for the ablblute affinity muft confift of 
 two things, the affinity which the acid has for the bafe, 
 and the affinity which the bafe has for the acid. Now 
 the firft table gives us the one of thcfe, and the fecond 
 the other ; fo that in order to reprefent affinity in ab- 
 folute numbers, the two tables mull be multiplied into 
 one another. This was the miftake into which Mr Kir- 
 wan fell. His method confifted merely in conftrufting a 
 table like our firft, which (fuppofing the numbers accu- 
 rate) gave only the affinity between the bafes and the 
 fame acid, but left out the affinity between the different 
 acids and the fame bafe ; confequently the different co- 
 lumns could not be compared with each other. 
 
 It is evident, however, that if the tables were multi- 
 plied together in their prefent ftate, they could not pof. 
 ftbly give an accurate table of affinities. For that pur- 
 pofe, it is neceffary to put the iame number in the firfc 
 column of each table, and then to fubftitute other num- 
 bers in the remaining ccJumns, having the. fame ratio to^ 
 one another with the numbers in the original columns. 
 This is done in the following Tables : 
 
 Table I. 
 
 Ratios of ihi Affinity of fix Bafes for three 
 Acids. 
 
 
 B.irytes. 
 
 PotaR 
 52,85 
 
 57.43 
 58,11 
 
 Soda. 
 
 33.73 
 36,98 
 
 38,81 
 
 Lime. 
 29.27 
 
 28,77 
 
 3J.70 
 
 Magn. 
 
 24.34 
 24,28 
 
 29.94 
 
 Amm. 
 21,12 
 
 19.59 
 
 Sulph. acid 
 
 lOOjCO 
 
 Nitricacid 
 
 100,00 
 
 Mur. acid 
 
 100,00 
 
 24.15 
 
 Table
 
 Part ir, 
 
 ^fljnity. ry^^^^ jj_ jj^fi^^ gj- ii^^ /jfinity of three Ac'ids for 
 
 Jlx Bajei. 
 
 iSulph. acifi. 
 
 Nitric acid. 
 
 Mur. aci'. 
 
 Barytcs 
 
 100,00 
 
 90,42 
 
 74.54 
 
 Potafs 
 
 100,00 
 
 79,01 
 
 65,30 
 
 Soda 
 
 1 00,00 
 
 80,03 
 
 62,35 
 
 Lime 
 
 100,00 
 
 92,24 
 
 60,05 
 
 Magnefia 
 
 too, 00 
 
 90.34 
 
 59,68 
 
 Ammonia 
 
 100,00 
 
 90,02 
 
 62,77 
 
 CHEMISTRY. 349 
 
 the fubjeft, for the candour which he has difplayed, Afiiniiy. 
 and for the new rout which he has opened to the che- ' 
 mical philofopher. Though this problem has not hi- 
 therto been folved, and though the difficulties which 
 furround it are almoll infurniountablc, we may hope 
 much from the general fenfe which is at prefciil enter- 
 tained of its importance, and from the zeal and abili- 
 ties of thofe philofophcrs who have particularly turned 
 their attention to it. 
 
 In the mean time, the following Table of the (Ircngth 
 of affinities by Morveau, though the numbers be arbi- 
 
 trary, will be found of very great ufe ' 
 
 Table III. ylffinUy bettueen three yields and fix Bafes 
 
 in AlJoJute Numbers. 
 
 .' Barytes 
 
 Sulph. acf: 
 
 Potafs 
 
 Soda 
 
 Lime 
 
 Magnefia 
 
 Ammonia 
 
 Nitric acid 
 
 lOOOO 
 
 5285 
 
 3373 
 
 2927 
 
 2434 
 
 211 2 
 
 9042 
 
 4537 
 
 2969 
 
 ^(>i3 
 
 *'93 
 
 1763 
 
 Mur. acid. 
 
 7454 
 
 3794 
 
 2419 
 
 2143 
 
 1786 
 
 15 1. 5 
 
 On the fuppofitton that the two pvopofitions men- 
 tioned above were ftriftly true, and that the numbers 
 which we fixed upon were precifely the quantities of 
 acid and bafe neceflary to faturate each other recipro- 
 cally, this lail table would reprefent accurately in num- 
 bers the ftrength of the affinities of the three acids for 
 each of the fix bafes refpedlively. 
 
 We muft acknowledge, however, that the truth of 
 thefe propofitions has not hitherto by any means been 
 fufficiently proved ; but a great number of faifls concur 
 to render them exceedingly probable, and highly wor- 
 thy of the attention of chemical philofophers. And we 
 hope that the method propofcd by Morveau, and which 
 had been prevloudy pradif<"d by Richter, of verifying 
 theoretical calculations of the compofition of the falts, 
 by mixing together two falts which n>utually decom- 
 pofe each other, and afcertaining whether the refult 
 correfponds with calculation, will be followed out, and 
 that it will be the means of enfuring more accuracy 
 than it has hitherto been poffibie to obtain. 
 
 No one will fufpecl that any thing which has here 
 been faid is meant as a reficftion on the ingenious che- 
 inifts who have attempted to folve this molt difficult of 
 all chemical problems, the proportion of the ingredients 
 ■which enter into the compofition of the falts. Mr Kir- 
 wan, in particular, is entitled to the greateft praife for 
 the perfevering induftry with which he has profecuted 
 
 
 Sulph. 
 acid 
 
 Nitric 
 acid. 
 
 Miiriit. 
 acid 
 
 Aceiou- 
 acid. 
 
 28 
 
 Caib.mc 
 acid. 
 
 Barytes 
 
 66 
 
 62 
 
 36 
 
 '4 
 
 Potafs 
 
 62 
 
 58 
 
 32 
 
 26 
 
 
 
 Soda 
 Lime 
 
 58 
 
 50 
 
 3' 
 
 25 
 
 8 
 
 54 
 
 44 
 
 24 
 
 19 
 
 12 
 
 Ammonia 
 
 46 
 
 38 
 
 21 
 
 20 
 
 4 
 
 Magnefia 
 
 50 
 
 40 
 
 22 
 
 17 
 
 6 
 
 Alumina 
 
 40 
 
 36 
 
 18 
 
 15 
 
 2(d) 
 
 • Encye. 
 MetlmJ. 
 CA/ct. i. 773* 
 
 577 
 Morveau** 
 tabic of 
 affinity. 
 
 5. Although every chemical combination is produced - 
 by the fame general law, yet as their phenomena vary 
 fomewhat according to circumftances, affinities have, 
 for the fake of greater perfpicuity, been divided into „■ 
 
 clafies. Thefe clafles may be reduced to three— Jhtiple,-^]^^^^ 
 compound, and difpoftng affinities. claffcsofaf?- 
 
 The^/y? clafs comprehends all thofe cafes in which finity, 
 
 ox\\y two bodies combine together; as, for in (lance, ful-„. ""^ , 
 
 u ■ J 4 .1- J u T-u a: Viz. fimple 
 
 pnuric acid ana potals, oxygen and carbon. 1 he am-.g^^jiy. 
 
 iiities which belong to this clafs are known by the name 
 oi fimple oT Jingle ajjinities. Although one ot the fub-- 
 fta net's to be combined happens to be already united 
 with another body, the combination is lliU reckoned a 
 cafe of fingle affinity. Thus (uppofe the iulphuric acid 
 previoufly co-xbined with magnefia, and forming with 
 it the fait c:.'\tAj'ulphiit of magnefia, as icon as potafs is- 
 prefented, the acid leaves the earth (which is precipi- 
 tated), and unites with the alkali. Even when three 
 bodies combine, it often happens that the union is pro- 
 duced merely by fingle affinity. Thus, when fomc pot- 
 afs is dropped into tartarous acid, part of the acid 
 unites with the alkali, and forms tartrite of potafs ; after 
 this the remainder of the acid combines with the tar- 
 trite juft formed, and compofes a new lalt known by 
 the name of acidulous tartrite of potcfs, or tartar. This 
 is evidently nothing tlfe than two inllances of fimple 
 affinity immediately following each other. - 
 
 When more than three bodies are mixed, decompo-Cnnipound 
 fitiuns and new combinations often take place, which nfiini'y, 
 
 could 
 
 (d) This table, however, does not correfpond quite accurately to all the phenomena. For inftance, accord- 
 ing to it, fulphat of barytes is not decompofed by carbonat of foda, although the contrary takes place ia 
 faft.
 
 350 C H E M I 
 
 Affinity, could not have been produced had the bodies been pre- 
 '~*~v~~-^ fented in a different ftate. If, for inftance, into a fo- 
 lution of fulphat of potafa tliere be poured nitric acid, 
 no decompofition is produced, bceaufe the fulphurio 
 acid has a ilronger affinity for potafs than nitric acid 
 has. For the viry fame realon, ammonia may be pour- 
 ed into the fokition without producing any change. 
 But if nitrat of ammonia be poured in, a decompofition 
 inrtantly takes place, and two new bodies, fulphul of 
 ammonia and nltiat of polafs, are formed. Such cafes of 
 decompofition form the feconil clafs of affinities. They 
 were called by Bergman cafes of double e/e3ive attrac- 
 iion ; a name which is exceedingly proper when there 
 are only four bodies concerned. But as there are often 
 more than four, it is neceffary, as Mr Morveau has ob- 
 ferved, to employ fome more comprehenfive term. We 
 Ihall therefore call the affinities belonging to this clafs 
 compound ajfinitie. (e) ; and comprehend under the 
 term all cafes where more than three bodies are prefent, 
 and produce combinations which would not have been 
 formed without their united aftion. In thefe cafes the 
 affinity of all the various bodies for each other afts, 
 and the refulting combii..;>,on is produced by theaftion 
 of thofe affinities wliich are ftrongeft. The manner in 
 which thefe combinations and decompofitions take 
 place, was firft clearly explained I y Dr Black. Let 
 the affinity between potafs and fulphi'ric acid be =: 62; 
 that uetween nitric acid and ammonia =: 38 ; that be- 
 tween the fame acid and potafs =r 58 ; and that be- 
 tween the fulphuric acid and ammonia =: 46. Now, 
 let ua fuppofe that all thefe forces are placed fo as to 
 draw the ends of two cylinders crofGng one another, 
 and fixed in the middle in' this manner, 
 
 Potafs. 
 
 Nitric acid. 
 
 (too 
 
 46 
 
 Sulph. acid — — Ammonia. 
 104 
 
 It is evident, that as 58 and 46 z=. 104, are greater than 
 62 -f- 38 ■:!: 100, they would overcome the other for- 
 ces and {hut the cylinders. Jull fo the affinity between 
 potafs and nitric acid, together with that between ful- 
 phuric acid and ammonia, overcomes the affinity be- 
 tween potafs and fulphuric acid, and that between nitric 
 acid and ammonia, and produces new combinations. 
 
 In all cafes of compound affinity, there are two 
 kinds of affinities to be confidered ; \J}, Thofe affinities 
 which tend to preferve the old compound, thefe Mr Kir- 
 wan has called quiefcatt affinities ; and thofe which tend 
 to deftroy them, which he has called divellent affinities. 
 
 Thus, in the inftance above given, the affinity be- 
 tween potafs and fulphuric acid, and that between ni- 
 tric acid and ammonia, are quiefcent affinities, which 
 endeavour to preferve the old compound ; and if they 
 are ftrongeft, it is evident that no new compound can 
 take place. On the contrary, the affinity between pot- 
 afs and nitric acid, and that between fulphuric acid and 
 
 S T R Y. Fart II, 
 
 ammonia, are divellent affinities ; ard as they are in this Affinity, 
 cafe ftrongeft, they adually deftroy the former combi. *~"~V""^ 
 nations and form new ones. 
 
 Bergman, who publiflied a great many cafes of com- 
 pound affinities, employed to explain them a method 
 fomewhat difterent from this. He would have rtpre- 
 fented the above cafe in the following manner : 
 
 Nitrat of Potafs. 
 
 Potafs 
 
 Nitric acid. 
 
 Sulphat of 
 Potafs. 
 
 Nitrat of 
 Ammonia, 
 
 Sulph. acid. Ammonia. 
 
 Sulphat of Ammonia. 
 
 At the four corners of an imaginary fquare are placed 
 the four fubftances, fo that one acid (hall be diagonally 
 oppofite to another. On the right and left fide of the 
 fquare are placed the old compounds, each on tlie fide 
 of its own ingredients, and above and below are placed 
 the new compounds. 
 
 Mr Elliot improved this method of Bergman, by ad- 
 ding numbers txpreffive of the affinity of the various 
 fubftances. It is in cafes of compound affinity that 
 the ratios of affinities, if we were pofTefled of them, 
 would be peculiarly ufeful. For it is evident, that if 
 we knew the ftrength of affinities in abfolute numbers, 
 we would be able to determine before hand all the cafes 
 of compound affinity. 
 
 If we knew, for inftance, that the affinity between 
 the muriatic acid and barytes were =: ^61, that between 
 the fame acid and potafs =: 32 ; the affinity between 
 potafs and carbonic acid ^ 9 ; and that between the 
 lame acid and barytes ^ 14 ; — we would be certain, 
 previous even to experiment, tiiat when muriat of bary- 
 tes and carbonat of potais are mixed, a double decom- 
 pofition would take place ; which we know from expe- 
 riment to be actually the cafe. 
 
 Muriat of Potafs. 
 
 Muriat of 
 Barytes, 
 
 Muriatic 
 acid, 
 
 36 
 
 Barytes, 
 
 32 
 
 14 
 46 
 
 Potafs. 
 
 9 C45, 
 
 Carbonic 
 acid. 
 
 Carbonat 
 "of Potafs. 
 
 Carbonat of Barytes. 
 
 Another inftance of decompofition by compound 
 affinities. 
 
 Sulphat 
 
 (e) Morveau caUed them affinite par coiKOurt.
 
 pare II. 
 
 Affinity. 
 
 CHEMISTRY. 
 
 Sulphat of Lime. Sulphat of Magnefia. 
 
 351 
 
 Sulph. acid, 54 Lime. 
 
 Sulphuric ., „ 
 
 acid, 50 Magnefia. 
 
 Affinity. 
 v.. ^ -a 
 
 Sulpliat 
 
 of 
 
 Ammonia, 
 
 46 
 
 lAmraonis 
 
 38 
 92 
 
 44 (9a 
 
 Nitric 
 acid. 
 
 Nitrat 
 
 of 
 Lime. 
 
 SiUpliat 
 of foda,^ 
 
 I Soda, 
 
 100 
 
 40 (98 
 
 50 Nitric acid. 
 
 Nitrat of 
 ' magnefia. 
 
 Nitrat of Ammonia. 
 
 Nitrat of Soda. 
 
 Suppofing Morveau's numbers exaft, it follows alfo, When a new compound is precipitated, a line bent 
 
 even prior to experiment, that no decompofition takes downwards in the middle is to be placed between it and 
 
 place when fulphat of lime and muriat of putafs are the fquare, as in the following fcheme : 
 in'5":d ; Sulphat of Potafs. 
 
 Sulphuric. g p f3_ J ( c , , •. J 
 
 acid, / I Sulph. acid, . 62 
 
 Potafs. 
 
 Sulphat 
 
 of ^ 54 
 Lime, 
 
 Lime, 
 
 20 
 
 82 
 
 Muriat 
 32 (86 )> of 
 
 J Potafs. 
 
 Muriatic \ 
 acid. I 
 
 for the quiefcent aSnIties are 86, and the divellent on- 
 ly 82. 
 
 Nor when acetite of lime and m\iviat of foda are 
 mixed ; 
 
 Acetite 
 
 of 
 Lime, 
 
 Acetous acid, 25 
 
 19 
 
 Lime, 
 
 I 
 
 20 
 
 45 
 
 Soda. 
 
 :8 (47 
 
 Muriatic 
 acid. 
 
 Muriat ■ 
 
 of 
 Soda. 
 
 becaufe the quiefcent affinities are 47, and the divellent 
 only 45. Thefe cafes where no decompofition takes 
 place have been called by Morv^u cafes of inverfe com- 
 pound affinity. 
 
 Morveau has propofed the following improvements in 
 
 ^ _ reprefenting thefe cafes of compound affinities*. 
 
 Method'. When decompofition does not take place, nothing is 
 
 Ci/>».i.555.to be written above and below the fquare, as in the two 
 
 laft examples. When a new compound remains diflbl- 
 
 ved, a ftraight line is to be placed between it and the 
 
 f"quare, as in the following fcheme. 
 
 Sulphat 
 
 of 
 Barytes, 
 
 65 
 
 Barytes, 
 
 14 
 76 
 
 9 {74 
 
 Carbonic ' 
 acid. 
 
 Carbonat 
 
 of 
 Potafs. 
 
 Carbonat of Barytes. 
 
 When a new compound is fublimed, the line between 
 it and the fquare is to be pointed upwards in the middle, 
 thus , 1^ ,• 
 
 When a new compound is partly diffolved and partly 
 precipitated, the line placed between it and the fquare 
 is to aflume the following (hape : , '. 
 
 When it is partly diffolved and partly fublimed, the 
 following is the line to be ufed : ' ,. 
 
 The third clafs of affinities has been called by ^'^ AaAiiita^ 
 Morveau tlifpofmg affinities, becaufe they dlfpofe fub-fing affinity, 
 (lances to combine that would not otherwife have done 
 it. Suppofe, for inftance, that fulphur is prefented to 
 oxygen gas, it does not manifefl any affinity for it ; 
 but combine it previoufly with potafs, and it unites with 
 oxygen with avidity. Its previous union with potafs, 
 in this cafe, d'lfpofcd it to unite with oxygen. The caufe 
 of this curious affinity is not yet well underllood. If 
 we confider what it was that prevented the fulphur and 
 oxygen from combining, we fhall find that it can only be 
 its own attraftion of cohefion, and the affinity between 
 the oxygen and caloric which are combined. What- 
 ever then diminifhes this attra£lion of cohefion, or of 
 aggregation as it has been called, mull facilitate the union 
 
 of
 
 different 
 tempera- 
 -tures to 
 ui.ite, 
 
 352 C H E M 
 
 Afiiiiity. of the fulpliur ivith oxygen. This 13 done in fome mca- 
 '~ V— — j'lirt by tlif potp.fs. Befides, if aifinity depends upon tlie 
 fiifiire of p:irticlc-s, it is evident that there muft be an 
 alfinitv between the new compound and oxyj^en; but the 
 niomeut the oxyf;eii appro;iches within a certain dillaiice 
 •of tlie fiilpluir, it unites u-ith it, as its alfiaity is much 
 greater for that fubllanee than for the compound. 
 
 Tlie following is another iiiilance of this curious afli- 
 nity : Sugar, as Lavoil'ur has proved, is coir.pofeJ of 
 oxygen, hydrogen, and carbon : Now if concentrated 
 fulphurio acid be poured upon fugar, the oxygen and 
 hydrogen Combine, and form water, which unites with 
 the acid, and the carbon is precipitated. In this cafe, the 
 prefence of the acid difpoful the oxygen and hydrogen 
 to con;biiie. In what manner this new combination is 
 produced, it would not be eafy to explain : not by 
 weakening the attraftion of cohefion ; for we do not fee 
 how the acid could produce that effeft. The only ex- 
 planation that can be given, is to fuppofe that the ful- 
 phuric acid, when it approaches within a certain dif- 
 tance of the oxygen and hydrogen, attrafts them ; and 
 that this attraftion, together with the affinity between 
 the oxygen and hydrogen, is greater than that which 
 produces the combination between the ingredients of 
 the fugar themfelves : the confequence of which muft 
 ^gj be decompofitiou. 
 Why bo- 6. We come now to one of the moft difficult quef- 
 
 <lies require tions in cheniiftry — Why do bodies require different 
 temperatures in order to unite ? and why does the pre- 
 fence of caloric in many cafes favour or rather produce 
 union, while it prevents or deftroys it in others ? 
 
 Thefe queftions were propofed at the end of the fe- 
 cond Chapter of this article ; and we referved them for 
 this place, not becaufe we hoped to be able to anfwer 
 them in a fatisfaftory manner, but becaufe no intelli- 
 gible anfwer could be given till the nature of affinity 
 bad been previoufly confidered. Some fubftances, phof- 
 phorus for inftance, combine with oxygen at the common 
 temperature of the atmofphere ; others, as carbon, re- 
 quire a higher temperature ; and others, as hydrogen 
 and azotic gas, do not combine except at a very high 
 temperature. To what are thefe differences owing ? 
 
 In anfwer to this queftion, we obferve, that the at- 
 fraftion of cehejton evidently oppofes that of affinity. 
 Thofe bodies which we prefent to combine together 
 are generally aggregates, or, which is the fame thing, 
 confift of many fimilar particles united by cohefion : 
 for we have no method of feparating bodies into their 
 integrant particles, except affinity. Now we can con- 
 ceive the attraftion of cohefion between the particles of 
 a body to be fo great as to prevent them altogether 
 from obeying the impulfe of affinity. 'J'hat this aftu- 
 ally happens in fome cafes cannot be doubted : for if 
 pure alumina be formed into a pafte, and heated fuffi- 
 ciently, it becomes fo hard that no acid can aft upon it; 
 yet its nature is not in the leafl changed: by proper tri- 
 turation, it may be again rendered foluble ; and when 
 precipitated from this new folution, it has recovered all 
 its original properties. The effeA of the fire, then, was 
 merely to increafe the cohefion, by feparating all the 
 water, and allowing the particles to approach nearer 
 each other. 
 
 It is evident, that whatever diminifhes the cohefion 
 which exifts between the particles of any body, muft 
 tend to facilitate their chemical union with the particles 
 
 I S T R Y. 
 
 Part II, 
 
 of other bodies. This is the reafon thai bodies comhine Afiiiity, 
 more eafily when held iji folution by water, or when ^""V"— 
 they have been prcviou'.ly reduced to a iinc powder. 
 Now caloric poflefles the property of diminiflu'ng co- 
 hefion. And one reafon why fome bodies require a 
 high temperature to caufe thi;m to combine is, that at 
 a low temperature the attrafllon of cohijum is in them 
 fu)>erior to that of afnnity; accordingly, it becomes ne- 
 ceffarv to weaken that attraction by caloric till it be- 
 ct)ines inferior to that of affinity. The quantity of ca- 
 loric neceffary for this purpofe muft vary according to 
 the fliength of the cohefion and of the affinity ; it muft j 
 
 be inverfely as the affinity, and direflly as the cohelion. 
 Wherefore, if we knew preclfely the force of the cohe- 
 fion between the particles of any body, and of the af- 
 finity between the particles of that body and of any 
 other, we could eafily reduce the temperature neceffary 
 to calculation. 
 
 That caloric or temperature afts in this manner can- 
 not be doubted, if we confider that other methods of 
 diminifliing the attraftion of cohefion may be fubfti- 
 tuted for it with fuccefs. A large lump of charcoal, 
 for inftance, will not unite with oxygen at fo low a 
 temperature as the fame charcoal will do when reduced 
 to a very fine powder ; and charcoal will combine with 
 oxygen at a ftlU lower temperature, if it be reduced to 
 its integrant particles, by precipitating it from alcohol, 
 as Dr Prieftley did by palfing the alcohol through 
 red hot copper. And to (hew that there is nothing in 
 the nature of oxygen and carbon which renders a high 
 temperature neceffary for their union, if they be pre- 
 fented to each other in different circumftances, they 
 combine at the common temperature of the atmofphere ; 
 for if nitric acid, at the temperature of 60°, be poured 
 upon charcoal powder, well dried in a clofe crucible, 
 the charcoal takes fire, owing to its combining with 
 the oxygen of the acid * : And In fome other lituations , Pr,ufia, 
 carbon is fo completely divided, that it is capable oi Mor^au, 
 combining with the oxygen of the atmofphere, or, tlncyc- Mr- 
 which is the fame thing, of catching fire at the com-. '' f^&w. 
 mon temperature. This feems to be the cafe with it in 
 thofe pyrophori that are formed by dillilling to dry- 
 nefs feveral of the neutral falts which contain acetous 
 acid -f-. Thefe obfervations are fufficient to fhew that f Morveau^ 
 caloric is in many cafes neceffary in order to diminifh 'i'</. 
 the attraftion of cohefion. 
 
 But there is a difficulty ftill remaining, How comes 
 it that certain bodies will combine with oxygen with- 
 out the affiftance of any foreign heat, provided the com- 
 bination be once begun, though a quantity of caloric 
 is neceffary to begin the combination ? and that other 
 bodies require to be furrounded by a great quantity of 
 caloric during the whole time of their combining with 
 oxygen ? Alcohol, for inftance, if once kindled, burns 
 till it is quite confumed ; and this is the cafe with oils 
 alfo, provided they be furnifhed with a wick. 
 
 We muft obferve, in the firft place, that we would 
 err very much, were we to fuppofe that a high tempe- 
 rature is not as neceffary to thefe fubftances during the 
 whole of their combuftion as at the commencement of 
 it ; for Mr Monge found, on making the trial, that a 
 candle would not burn after the temperature of the air 
 around it was reduced below a certain point. 
 
 All fubftances which continue to burn after being 
 once kindled are volatile, and they burn the eafier in 
 
 proportion 
 
 anS
 
 Part 11. C H E M I 
 
 Affinity, proportion fo that volatility. The application of acer- 
 "*"~Y— — tain quantity of caloric to alcohol volatilizes part of it ; 
 that is to fay, diminifhes the attraftion of its cohefion 
 fo much that it combines with oxygen. The oxygen 
 which enters into this combination gives out as much 
 heat a* volatilizes another portion of the alcohol ; which 
 combines with oxygen in its turn; more heat is given out; 
 and thus the proccfs goes on. Oils and tallow exhibit 
 the very fame phenomena; only as they are lets volatile, 
 it is nccelTary to aflill the proccfs by means of the ca- 
 pillary attraction of the wick, which confines the aftion 
 of the caloric evolved to a fmall quantity of oil, and 
 thus enables it to produce the proper effcft. In (liort, 
 then, every fubftance which is capable of continuing to 
 burn, after being once kindled, is volatile, or capable of 
 being converted into vapour by the degree ot heat at 
 firft applied. The reafon that a live coal will not burn 
 when fufpended infulated in the air, is not, as Dr Hut- 
 • Oti Uglii ton fuppofed*, becaufe its light h diffipated; but becaufe 
 vaiiicat. the coal cannot he converted into vapour by the de- 
 gree of heat which it contains, and becaufe the cohe- 
 fion of its particles is too great to allow it to combine 
 with oxygen without fome fuch change. There are 
 fonie coals, however, which contain fuch a quantity of 
 bitumen that they will burn even in the fituation fup- 
 pofed by Dr Hutton, and continue to burn, provided 
 they be furnifhed with any thing to aft as a wick. It 
 is needlefs to add, that bitumen, like oil, is eafiiy con- 
 verted into vapour. 
 
 But this explanation, inftead of removing our diffi- 
 culties, has only ferved to increafe them : For if ca- 
 loric only afts by dimmilhing the attraction of cohe- 
 fion, and converting thefe fubftances into vapour, why 
 do not all elaftic fluids combine at once without any 
 F.dditional caloric ? why do not oxygen and hydiogen, 
 when mixed together In the ftate of gas, unite at once 
 and form water ? and why do not oxygen and azot, 
 which are conllantly in contaft in the atmofphere, unite 
 alfo and form nitrous gas ? Surely it cann(Jt be the 
 attraction of cohefion that prevents this union. And 
 if it be afcribed to their being already combined with 
 caloric, how comes it that an additional dofe of one of 
 the ingredients of a compound decompofes it ? Surely, 
 as Mr Monge has obferved, this is contrary to all the 
 other operations in chemiftry. 
 
 That the particles of fluids are not deftitute of an 
 attraftion for each other, is evident from numberlefs 
 fafts. The particles of water draw one another after 
 them in cafes of capillary attraftion ; which is proba- 
 bly owing to the attraftion of cohefion. It is owing 
 to the attraftion of cohefion, too, that fmall quantities 
 of water form themfelves into fpheres : Nor is this at- 
 traftion fo weak as not to be perceptible. If a fmall 
 plate of glafs be laid upon a globule of mercury, the 
 globule, notwithftanding the preffure, continues to pre- 
 ferve its round figure. If the plate be gradually char- 
 ged with weights one after another, the mercury be- 
 comes thinner and thinner, and extends itfelf in the 
 form of a plate ; but as foon as the weights are 
 removed, it recovers its globular figure again, and 
 pulhes up the glafs before it. Here we fee the at- 
 SuFPL. Vol. I. Part I. 
 
 S T R Y. zSi 
 
 traftion of cohcrmn, rat only fuperior to gravita- Affiiiitjf. 
 tion, but aftually overcoming an external force *• , j^r" 
 And if the workman, after charging his plate of /fa„i,c^ 
 gldfs with weights, when he is forming mirrors, hap-p. 543. 
 pen to remove thefe weights, the mercury which had 
 been forced from under tiie glafs, and was going to fe- 
 parate, is drawn back to its place, and the glafs again 
 pudu'd up. Nor is the attraftion of cohefion confined 
 to folids and liquids ; it cannot be doubted, thit it ex- 
 ifts alfo in gafes ; at leaft^ it is evident, that there fub- 
 fifts an attraftion between gafes of a different kind : 
 for although oxygen and azotic gas are of different 
 gravities, and ought therefore to occupy different parts 
 of the atmofphere, we find them always mixed toge- 
 h er ; and this can only be afcribed to an attraftion. 
 And were we to allow, with Humbolt and feveral other . 
 chemifts, that thefe two gafes are chemically combined 
 in atmofpherical air, an opinion contradifted by a late 
 experiment in France (f); flill the exiftence of carbo- 
 nic acid gas in every part of the atmofphere can only 
 be afcribed (if the inaccuracy of the expreffion may be 
 tolerated) to a kind of cohefion. And whoever has 
 been accuftomed to pneumatic experiments, muft have 
 obferved that fmall portions of air, as well as water, 
 form themfelves into fpheres, and that the attraftion of 
 cohefion is fo ftrong in gafes, that large globules of 
 them often adhere by a fingle point to the bottom of 
 vefTcls filled with heavy fluids : whereas, had there been 
 no attraftion of cohefion, every part of the globule 
 ought to have afcended to the furface of the fluid, 
 except the particles immediately in contaft with the 
 velfel. Allowing, then, that there is an attraftion of 
 cohefion between the particles of gafes, let us fee whe- 
 ther that will not aflift us in removing the difficulty. 5S3 
 
 It feems evident, in the firft place, that the affinity Eiplained. 
 between the bafes of the gafes under confideration and 
 oxygen is greater than their affinity for that dofe of 
 caloric which produces their elaftic form ; for when 
 they are combined with oxygen, the fame dofe will not 
 feparate them again. Let us take hydrogen for an in- 
 ffance : The affinity of hydrogen is greater for oxygen 
 than for the caloric which gives it its gafeons form ; 
 but the oxygen is alfo combined with caloric, and there 
 exifts an attraftion of cohefion between the particles of 
 the hydrogen gas ; the fame attraftion fubfilts between 
 thofe of oxygen gas. Now the fum of all thefe affini- 
 ties, namely, the affinity between hydrogen and calo- 
 ric, the affinity between oxygen and caloric, the cohe- 
 fion of the particles of the hydrogen, and the cohefion 
 of the particles of oxygen — is greater than the affinity 
 between the hydrogen and oxygen ; and therefore no 
 decompofition can take place. Let the affinity between 
 Oxygen and caloric be - - - 50 
 
 Hydrogen and caloric - • - - 50 
 Cohefion of oxygen .... 4 
 
 Cohefion of hydrogen .... 2 
 
 Sum of quiefcent affinities, - • lo6 
 
 The affinity of oxygen and hydrogen, . 105 
 
 The quiefcent affinities being greater than the divellent 
 
 affinities, no decompofition can take place. 
 
 Y y Let 
 
 (f) Air brought by means of a balloon from a great height in the atmofphere was fouDd to contain lefs oxy- 
 'gen gas than the fame quantity of air oear the grouad.
 
 354 
 
 Affinity. 
 
 C H E M 1 
 
 Let now a quantity of caloric be added to the oxy- 
 gen and hydrogen gas, it has the property of expand- 
 ing them, and of cuurfe of dlminilhing their culiclion ; 
 while its affinity for them is fo fmall that it may be ne- 
 glected. Let us fuppofe that it diniinHhes the coliefion of 
 the oxygen i, and of the hydrogen alfo i, their colieilon 
 will now be ^ and i ; and the quici'ctnt affinities being 
 only 104, while the divellent are 105, the decompofition 
 Would of courfe take place, and a quantity of caloric 
 would thus be fet at liberty to produce the fame effeAs 
 upon the neighbouring particles. 
 
 Thus, then, caloric a>Sts only by diminifhing cohe- 
 Con : And the reafon that it is required fo much in 
 gafeous fubftances, and in thofe combinations into which 
 oxygen enters, is the ftrong affinity of oxygen and the 
 other bafes of the gafes for caloric ; for, owing to the 
 repulfioQ which exilis between the particles of that fub- 
 tile fubftance, an effedt is produced by adding large 
 dofes of it, contrary to what happens in other cafes. 
 The more of it is accumulated, the ftronger is the re- 
 pulfion between its particles ; and therefore the more 
 powerful is its tendency to fly off: and as this tendency 
 ii oppofed by its affinity for the body and the cohe- 
 lion of its particles, it mull diminilh both thefe attrac- 
 tions. 
 
 Though we have thus attempted to explain what has 
 been always confidered as one of the moft difficult pro- 
 blems in chemiftry, we are far from fuppofing that we 
 have removed every difficulty. Much ilill remains to 
 be done before the aftion of light and caloric can be 
 fully underftood ; and there may be other agents, of 
 whofe exillence we have not yet even conceived the 
 idea. 
 
 One difficulty ftill remains to be examined. Heat 
 not only produces the combination of fome bodies, but 
 alfo occaiions the decompofition of others. How does 
 it aft in thefe cafes ? 
 
 That many of thefe decompofitions are produced by 
 
 decomtiofes chemical affinity, will be evident from the following ex- 
 
 '""''"• amples. 
 
 When fulphur and arfenic acid are expofed to heat, 
 
 * f'll'ti'r- fulphuret of arfenic is formed * evidently by a kind of 
 compound affinity. 
 
 Oxygen Gas. 
 A 
 
 584 
 How heat 
 
 Caloric 
 
 Sulphur 
 
 50 
 
 Oxygen 
 
 60 
 
 Arfenic 
 
 > Arfenic 
 Acid. 
 
 Sulphuret of Arfenic. 
 
 It) the fame manner, when nrtrat of potafs and bora- 
 cic acid are expofed to heat, the nitric acid is volati- 
 lized, and borat of potafs is left behind. 
 
 S T R Y. 
 
 Nitric Acid in Vapour. 
 
 A 
 
 Part IL 
 
 Affinity. 
 
 Caloric 
 
 4 Nitric acid 
 
 „ ^Nitrat of 
 ^" / Potafs. 
 
 Boracic acid 55 Potafs 
 
 Borat of Potafs. 
 
 By the fame compound affinity boracic acid and 
 heat decompofes muriat of foda. 
 
 Muriatic Acid Gas. 
 A 
 
 Caloric 10 Muriatic acid 
 
 31 
 
 Muriat of 
 Soda. 
 
 Boracic acid 24 Soda 
 
 Borat of Soda. 
 
 In the fame manner, it would be cafy to explain hovr 
 all the decompofitions by the dry -way, as it is called, 
 are Bfoduced. 
 
 Bat how comes caloric to decompofe water after ha- 
 ving produced the union of oxygen and hydrogen ? 
 The union, we have feen, was probably brought about 
 by the play of oppofite affinities ; but in the feparation, 
 caloric ieenis to aft by its peculiar power, or the re. 
 pulfion which exilis between its particles. When ca- 
 loric combines with an integrant particle of water, this 
 repulfion muft feparate the component parts fomewbat 
 from one another ; confequently it muft weaken their 
 affinity ; for every increafe of diftance produces that ef- 
 feft. Now let us fuppofe that the affinity between 
 oxygen and hydrogen is 10?, and that the affinity be- 
 tween caloric and each of thefe bodies is 50 : as foon 
 as the particles of oxygen and hydrogen are fo far fe- 
 parated from each other that their affinity is lefs than 
 ioo, they will unite with caloric in preference, becaufe 
 the fum of their affinities for caloric is equal to 100 ; 
 confequently, whenever that takes place water will be 
 decompofed. Hence we fee the reafon why more heat 
 is always neceffary to produce the decompofition of bo- 
 dies than what produced their union. 
 
 Caloric poileffes another fmgular property, that of 
 changing the compound affinities of bodies, even when 
 
 it
 
 art II. C H E M I 
 
 vfliiiiiy- it does not appear to enter as an ingredient. Wliatwc 
 
 — "v mean will appear eviHent trom the following examples : 
 
 Miiriit of ammonia, 7 (iecoir.pofo each other at the 
 
 Caviionat of maynelia, J ordinar)- temperature of the 
 
 atniofpheie, ami form miniat of magnelia and earboiiat 
 
 of ammonia: but, on the contrary, 
 
 Miiriat of msgnefia, audi decoinpofe each other at 
 Carbonat of ammonia, J a high temperature ; for 
 indance, at 212°. The products are muriat of ammo- 
 nia and carbonat of magncfia *. 
 
 Again, if muriat of loda and fulphat of magnefia be 
 mixed together at a low temperature, for inilance at 
 zero, they decompofe each other, and muriat of mag- 
 nelia and fulphat of foda are formed ; but no decom- 
 polition takes place at a temperature above 32°. — Mu- 
 riat of foda, and fulphat of alumina, exhibit precilely 
 the fame phenomena f . 
 
 LalUy, fulphat of magnefia and carbonat of ammonia 
 decompofe each other at the ordinary temperature ; but 
 '"""•'"""■at 212" the carbonic acid flies off, and the remaining 
 Fcurcroy, fubftances form a triple fait \ 
 
 inn. de 
 "Mm. ii 
 .91. 
 
 XVtfirum, 
 tun, dc 
 'bim. li. 
 IS. 
 
 nd Grcn 
 inn, de 
 
 The lail of thefe phenomena appears owing to the 
 affinity between carbonic acid and caloric, and the two 
 lirll to the affinity between muriat of ammonia and ca- 
 loric, for that fait is volatilized. 
 
 It would not be fo eafy to explain the mutual decom- 
 
 pofition of muriat of foda and lulphat of magnefia at a 
 
 low temperature. It is probably connetted with the 
 
 alterations in the dillance of the ingredients of chemical 
 
 compounds, which are produced by the prefence and 
 
 .. abfence of caloric. 
 
 )f Count From the important part which caloric afts in chemi- 
 
 tumford's cal combinations, Count Rumford has been lately indu- 
 
 pinion re- ced to fufpecl that this fubtile fluid is the only agent by 
 
 J^^-ng af- ^hich they are produced. 
 
 That caloric is a necejfary agent in all chemical de- 
 compofitions and new combinations, we very readily al- 
 
 nity 
 
 S T R Y. 
 
 low ; brcaufe we know no other caufe except caloric fo -A 
 prevent tiie particles of bodies from ad^ual contadt ; in 
 which cale dccompofilion would be impoffible : and if 
 this be the fenle in wliich that ingenious philofophcr 
 aicribcs chemical combinations to caloric, we very rea- 
 dily agree with him ; but if he fuppofes l!iat caloric is 
 the agetit by which the particles of bodie* are brought 
 near each other, and i\\t force by which tliey adhere to 
 one another, we cannot help thinking that he is iniila- 
 kon : For that bodies, chemically combined, are kept 
 near each other by fome force, cannot poffibly be de- 
 nied. Now, what is that force ? We have laid, after 
 Newton, an allnulion between liij particles themfehes ; 
 acknowledging, at the fame time, that we are 'unable to 
 explain what that is. 
 
 Count Rumford feems to fuppofe that there is no 
 fuch thing as attraftion between the particles them- 
 felves, but that caloric is the agent which keeps them 
 together. If fo, how does caloric perform this office i 
 For our part, we do not pretend to imderftand it any 
 more than the nature of attraftion ; nor do we fee that 
 it is poffible to render it more intelligible. But there 
 is another queftion of Hill greater importance. What are 
 the proofs that caloric is the only agent in all cafes of 
 chemical combinations \ For our part, we can think of 
 no proof that can render this opinion in the fmallelt de- 
 gree plaufible. 
 
 Has this celebrated and candid philofophef confider. 
 ed this fubjeft with his ufual accuracy ? If heat be a 
 body, it cannot furely be the caufe of affinity, unltfs it 
 be pofiefTed of properties which, fo far from being pro- 
 ved, have not even been fufpetled. On the contrary, if 
 it be a property of matter, what property is it i If it 
 be a peculiar motion, as Count Rumford fufpefts, we 
 would alk if it be poffible for any motion whatever, in- 
 dependent of attradtion, to produce the permanent union 
 of two bodies ? 
 
 355 
 
 Part III. Of DOUBLY COMPOUND BODIES. 
 
 THE bodies which confift of combinations of thofe 
 fubftances that have been denominated compound, 
 and which, for that reafon, we have ventured to call 
 doubly compound bodies, may be reduced to three clalFes : 
 Soaps, 
 
 Neutral falts, 
 Hydrofulphurets. 
 Thefe fhall form the fubjedl of the three following 
 Chapters ; and we fhall finifh this part of the article with 
 iorne obfervations on cry/lallization. 
 
 Chap. I. 0/Soaps. 
 
 The compounds into which oils enter without de- 
 compofition have been denominated /o/t/sj. 
 
 Oils are capable of combining with alkalies, earths, 
 and metallic oxides ; they are capable alfo of combining 
 with fcveral of the acids. There are therefore two clalTes 
 of foaps ; I. Alkaline, earthy, and metallic foaps, which, 
 for the fake of brevity, we fhall call alialine foaps ; and, 
 
 2. Acid foaps. Thefe two clafTes form the fubjecl of 
 the two following Sedlions. 
 
 Sect. I. Of Alialine Soaps. 
 
 As there are a great number of oils, all or moft of 
 which are capable of combining with alkalies, earths, 
 and oxides, it is natural to fuppofe that there are as ma- 
 ny genera of alkaline foaps as there are oils. That there 
 are differences in the nature of foaps correfponding to 
 the oil which enters, into their compofition, is certain ; 
 but thefe differences are not of lufficient importance to 
 require very particular defcription. We fliall therefore 
 dclcribe all the alkaline foaps together, and notice, as 
 we go along, fome of the moll important differences re- 
 fulting from the oily ingredients. „ 
 
 I . Soap of foda, or common foap. The word foap Common 
 C/apo, cfxray) firll occurs in the works of Pliny and Ga-hardfoapj 
 len, and is evidently derived from the old German word 
 fepe (g). Pliny informs us, that foap was firll difco- 
 vered by the Gauls ; that it was compufed of tallow 
 Y y 2 and 
 
 (g) Beckmonn's Hijlory of Inventions, III. 2^^. — A fimilar word is ftill ufed by the common people of Scot- 
 land.
 
 35^ 
 
 C H E M 
 
 Alkaline and adies ; and that the German foap was reckoned the 
 . Soaps, beft*. 
 
 • Pliny Soap may be prepared by the following procefs. A 
 
 )ib. xviii. quantity of the foda of commerce, which is a carbonat 
 
 *• 5'- of foda, and which is often called lar'illa from the name 
 
 ■Kt^yJ ^ , of a plant, by burning which it is procured in great 
 
 forminij it- '^''''ntities in Spain, is pounded and mixed in a wooden 
 
 vcfTel, with about a fifth part of its weight of lime, 
 
 flacked and palTed through a fieve immediately before. 
 
 TIpon this mixture a quantity of water is poured, con- 
 
 fiderably more than what is fufficient to cover it, and 
 
 allowed to remain on it for feveral hours. The lime 
 
 attraAs the carbonic acid from the foda, and the water 
 
 becomes ilrongly impregnated with the pure alkali. This 
 
 water is then drawn off by means of a (lop-cock, and 
 
 called the Jir/} ley. Its fpecific gravity (hould be about 
 
 1,200. 
 
 Another quantity of water is then to be poured up- 
 on the foda, which, after (landing two or three hours, 
 is alfo to be drawn off by means of the ftop-cock, and 
 called ihefecond ley. 
 
 Another portion of water is poured on ; and after 
 (landing a fufficient time, is drawn off like the other 
 two, and called the third ley. 
 
 Another portion of water may dill be poured on, in 
 order to be certain that the whole of the foda is ditfol- 
 ved ; and this weak ley may be put afide, and employ- 
 ed afterwards in forming the (ird ley in fubfequent ope- 
 rations. 
 
 A quantity of oil, equal to fix times the weight of 
 the foda ufed, is then to be put into the boiler, together 
 with a portion of the third or -weaiejl ley, and the mix- 
 ture mud be kept boiling, and agitated conftantly by 
 means of a wooden inftrument. The whole of the third 
 ley is to be added at intervals to the mixture ; and after 
 it is confumed, the fecond ley mud be added in the 
 fame manner. The oil becomes milky, combines with 
 the alkali, and after fome hours it begins to acquire 
 confidence. A little of ihe Jirjl ley is then to be added, 
 rot forgetting to agitate the mixture conftantly. Por- 
 tions of the firft ley are to be added at intervals ; the 
 foapy fubdance acquires gradually greater confidency, 
 and at lad it begins to feparate from the watery part 
 of the mixture. A quantity of common fait is then to 
 be added, which renders the feparation much more com- 
 plete. The boihng is to be continued dill for two 
 hours, and then the fire mud be withdrawn, and the li- 
 quor mud be no longer agitated. After fome hours 
 repofe the foap feparates completely from the watery 
 part, and fwims upon the furface of the liquor. The 
 watery part is then to be drawn off; and as it contains 
 a quantity of carbonat of foda, it ought to be referved 
 for future ufe. 
 
 The fire is then to be kindled again ; and, in order 
 to facilitate the melting of the foap, a little water, or 
 rather weak ley, is to be added to it. As foon as it 
 boils, the remainder of the firft ley is to be added to it 
 at intervals. When the foap has been brought to the 
 proper confidence, which is judged of by taking out 
 fmall portions of it and allowing it to cool, it is to be 
 ■withdrawn from the fire, and the watery part feparated 
 from it as before. It is then to be heated again, and a 
 
 1 S T R Y. Partlir. 
 
 little water mixed with it, that it may form a proper Alkaline 
 palle. It is then to be poured into the veffels proper S .aps. 
 for cooling it ; in the bottom of whicii there ou^ht to """^ ' ' 
 be a little chalk in powder, to prevent the foap from at- 
 taching itielf to it. In a few days the foap will have 
 acquired fufficient confidence to be taken out, and form- 
 ed into proper cakes ( h ). 
 
 Tlie ufc of the common fait in the above procefs is 
 to feparate the water from tiie foap ; for coiumon fait 
 has a dronger affinity for water than foap has. 
 
 Olive oil has been found to anfwer bed for making 
 foap, and next to it perhaps tallow may be placed : but 
 a great vaiiety of other oils may be employed fur that 
 purpofe, as appears from the experiments of the French 
 chemids above quoted. They found, however, that 
 lintieed oil and whale oil were not proper for making 
 hard foaps, though they might be employed with ad- 
 vantage in the manufailure o( foft fonps. Whale oil 
 has been long ufed by the Dutch for this lad pur- 
 pofe. 
 
 Soap may alfo be made without the aflidance of 
 heat ; but in that cafe a much longer time and a larger 
 proportion of alkali is neceffary. 
 
 Manufadlurers have contrived various methods of fo-.,, 5 . n.. 
 pnilticating ioap, or or addmg ingredients which in- cation, 
 creafe its weight without increafing its value. The 
 mod common fubdance ufed for that purpofe is water; 
 which may be added in confiderable quantities, efpecial- 
 ly to foap made with tallow (the ingredient uled in this 
 country), without dimini(hing its confiftency. This 
 fraud may be eafily detefted, by allowing the foap to 
 lie for fome time expofed to the air. The water will 
 evaporate from it, and its quantity will be difcovered- 
 by the diminidiing of the weight of the foap. As foap 
 fophifticated in this manner would lofe its water by be- 
 ing kept, manufafturers, in order to prevent that, keep 
 their foap in faturated folutions of common fait ; which 
 do not diffolve the foap, and at the fame time, by pre- 
 ventii.g all evaporation, preferve, or rather increafe, the 
 weight of the foap. Meffrs Darcet, Lelievre, and Pel- 
 letier, took two pieces equal in weight of foap fophifti. 
 cated in this manner, and placed the one in a dry place 
 in the open air, and the other in a faturated folution of 
 common fait. After a month, the firft had loft ^'ao "f 
 its weight, the- other had gained about t'j?^ parts *. •An. * 
 Various other methods have been fallen upon to fophif- ''"'"• *"- 
 ticatc foap ; but as they are not, we hope, generally^'' ' 
 known, it would be doing an injury to the public to 
 defcribe them here. g 
 
 Different chemifts have analyfed foap, in order to af- proportion 
 certain the proportions of its ingredients; but the re- ff its ingre- 
 fult of their experiments is various, becaufe they ufed*^""'*- 
 foap containing various quantities of water. From the 
 experiments of Darcet, Lelievre, and Pelletitr, it ap- 
 pears that foap newly made and expofed to fale con- 
 tains 
 
 9,75 Oil, 
 1,37 Alkali, 
 4,87 Water. 
 
 Soap is foluble both in water and in alcohol. Its 
 properties as a detergent are too well known to require 
 any defcription. j 
 
 It 
 
 (b) See the Memoir of Darcet, Lelievre, and Pelletier, in the Ann. de Chim. XIX. i^'^-
 
 Soaps. 
 Soft foap. 
 
 Part HI. C H E M 
 
 Alkaline It Is decomportd by !in»c, and by compound affini- 
 ty (i) by fiilphat of lime, nitr.it of lijiit, miiriat of litne, 
 and probably all the falls which contain lime. 
 
 2. Soap of potafs. — Potafs may be fubttituted for fo- 
 da in making' foap, and in that cafe precilely the fame 
 procefs is to be followed. It is remark;>ble, that when 
 potafs is ufed, the foap does not adume a folid form ; its 
 confiftencc is never greater than that of hog's lard. 
 This is what in this country is cMed foft/oiij). Its pro- 
 perties as a detergent do not differ materially from ihofe 
 o{ hard foap, but it is not nearly fo convenient for ufe. 
 The alkali employed by the ancient Gauls and Ger- 
 mans in the formation of foap was potafs: hence we lee 
 the reafon that it is defcribtd by the Romans as an un- 
 guent. 
 
 Some perfons have rfSrmed that they knew a me- 
 thod of making hard foap with potafs. Their method 
 is this: After forming- the foap in the manner above 
 defcribed, they add to it a large quantity of common 
 fait, boil it for fome time, and the foap becomes folid 
 when cooled in the ufual way. That this method may 
 be praftifed with fuccefs has been afcertained by McfTrs 
 Darcet, Lelievre, and Pelletier; but then the hard foap 
 thus formed does not contain potafs, but foda: for when 
 the common fait (mun'at of ioda) is added, the potais 
 of the foap decompofes it, and combines with its muri- 
 atic acid, while at the fame time the foda of the fait 
 combines with the oil, and forms h:.rd foap : and the 
 muriat of potafs formed by this double decomjiofitlon is 
 • Ann. ite diflolved in the water, and drawn off along with it*. 
 Chtm,z.ix. Chaptal has lately propofed to fubftitute wool in 
 '*'■ place of oil in the making of foap. The ley is formed 
 
 in the ufual maniier, and made boiling hot, and flireds 
 of woollen cloth of any kind are gradually thrown into 
 it ; they are foon diffolved. New portions are to be 
 added fparingly, and the mixture is to be conilantly a- 
 gitated. When no more cloth can be diflolved, the 
 f UiJ. XX}. foap is madef. This foap is faid to have been tried with 
 '7- fuccefs. It might doubtlefs be fubilitutcd for foap with 
 
 advantage in feveral manufad.ures, provided it can be 
 obtained at a cheaper rate than the foaps at prefent 
 employed. 
 
 Fifl'., too, have been lately fubflituted for oil with 
 equal fuccefs. The only difadvanlage which foap made 
 in this manner is liable to, is a difagreeable fmell, from 
 which it cannot eafdy be freed. 
 
 3. Soap of ammonia. — This foap was firft particular- 
 ly attended to by Mr Bertholltt. It may be formed 
 by pouring carbonat of ammonia on foap of lime. A 
 double decompofition takes place, and the foap of am- 
 monia fwims upon the furface of the liquor in the form 
 of an oil; or it may be formed with ftiU greater eafe by 
 pouring a folution of muriat of ammonia into common 
 foap diflolved in water. We have formed it often by 
 
 J 'BtrihoUei, mixing cauftic ammonia and oil \. 
 
 Mem. Par. It has a more pungent tafle than common foap. 
 Water diflblves a very fmall quantity of it ; but it is 
 eafily dilFolved in alcohol. When expofed to the air, 
 it is gradually decompofed. 
 
 4. Soap of lime. — This foap may be formed by pour- 
 ing lime-water into a folution of common foap. It is 
 
 59' 
 Soap of 
 ammonia. 
 
 1780, or 
 i^khotjon 
 journal., i, 
 170 
 
 Soap of 
 lime. 
 
 I S T R Y. 357 
 
 infoluble both in water and alcohol Carbonat of fixed Alkjline 
 alkali decompofes it by compound affinity *. It melts Suaps. 
 with difficulty, and requires a (Irons heat. «„, ''~~~'^, 
 
 5. boap ot magnelia. — 1 his ioap may be formed by 5^3 
 mixing together folutioiis of conuiion foap and fulphat S^ap of 
 of magnelia. magnefia, 
 
 It is exceedingly white. It is unftuous, dries with 
 difTiculty, and preferves its whitenefs after deficcation. 
 It is infoluble in boiling water. Alcohol and fixed oil 
 didolve it in conliderable quantity. Water renders its 
 folution in alcohol milky. A moderate heat melts it ; 
 a tranfparent mafs is formed, flightly yellow, and very 
 
 6. Soap of alumina. — This foap may be formed by '''"'• 
 mixing together folutioiis of alum and of common foap. qj.^'* . 
 It is a flexible foft fubftance, which retains its fupple-n^ " " 
 nefs and tenacity when dry. It is infoluble in alcohol, 
 water, and oil. Heat eafily melts it, and reduces it to 
 
 a beautiful tranfparent yellowifh mafs|. } Uid. 
 
 7. Soap of barytes refembles almolt exadly the foap^.-SW 
 
 of lime §. ?/w^'"' 
 
 8. Soap of mercury. — This foap may be formed by 596 
 mixing together a folution of common foap and of cor- Of mercu. 
 rofive muriat of mercury. The liquor becomes milky, '')'■ 
 
 and the ioap of mercury is gradually precipitated. This 
 foap is vifcid, not eafily dried, lofes its white colour 
 when expofed to the air, and acquires a flate colour, 
 which gradually becomes deeper, efpecially if expofed 
 to the fun or to heat. It dilTolves very well in oil, but 
 fparingly in alcohol. It readily becomes foft and fluid 
 when heated II . || nu. 
 
 9. Soap of zinc — This foap maybe formed by mix- J97 
 ing together a folution of fulphat of zinc and of foap. °^ ^""^» ' 
 It is of a white colour, inclining to yellow. It dries 
 fpeedily, and becomes friable «|[. H ■'^'''• 
 
 10. Soap of cobalt. — This foap, made by mixing ni-„,-''^? , 
 
 . . r 1 K 1 r ■ r i ii , , ° Of cobalt, 
 
 trat ot cobalt and common foap, is of a dull leaden co- 
 lour, and dries with difSculty, though its parts are not 
 connefted. taa 
 
 Mr BerthoUet obferved, that towards the end of the Of nickel, 
 precipitation there fell down fome green coagula, much 
 more confiflent than foap of cobalt. Thefe he fuppo- 
 fed to be a foap of nickel, which is generally mixed 
 with cobalt *- * IbiJ- 
 
 I I. Soap of tin. — It may be formed by mixing com-„r'°° 
 
 r -1 r 1 • r ■ • • • P Ot tin, 
 
 mon ioap with a lolution er tin in nitromunatic acid. 
 It is white. Heat does not fufe it like other metallic 
 foaps, but decompofes it \. ^ Ibid. 
 
 12. Soap of iron. — Formed by means of fulphat of-,*°' 
 iron. It is of a reddifh brown colour, tenacious, and ' 
 eafily fufible. When fpread upon wood, it finks in and 
 dries. It is eafily foluble in oil, efpecially of turpentine, t ■^^"'■ 
 BerthoUet propofes it as a varnifhj. 
 
 13. Soap of copper. — Formed by means of fulphat 
 of copper. It is of a green colour, has the feel of a 
 refin, and becomes dry and brittle. Hot alcohol ren- 
 dcrs its colour deeper, but fcarcely difiblvcs it. Ether 
 diflblves it, liquefies it, anrirenders its colour deeper and 
 more beautiful. It is very foluble in oils, and gives § •'^"'• 
 them a pleafant green colour^. nt 1 ,< 
 
 14. Soap of lead. — It may be formed by means of ' 
 
 acetite 
 
 60a 
 Of copper, 
 
 (i) In thiB and the following chapter, compound affinity is not taken always in its ftrifk and proper fenfe, but 
 is applied to all thofe decompofitions in which the affinities of more than three, bodies aS,
 
 358 C H E M I S T R Y. 
 
 Alkajiiie arctite of liad. Tt is wnite, tenacious, and very adhe- 
 ^"'l'" live wlicii heated. Wlifn filled, it is traiilparent, and 
 * H-il> >l I becomes fomewliat yellow if the heat be incieafed* 
 
 ii!J. 
 
 Part III. 
 
 6^4 
 Ot iV.vcr, 
 
 C.Oj 
 
 Of gM, 
 
 1 5. Sn.ip of fdver. — It may be formed by means of 
 nitrat of filver. It ip at fiid white, but becomes led- 
 dllh bv expiifuvc to the air. AVIien fufed, its fur^ace 
 btco-.res covered with a very brilhant iris; "beneath tlie 
 furface it i? black -f. 
 
 1 6. Soap of jrold. — It is at firft white, and of the 
 confiftcnee of cream. It gradually afliimes a dirty pur- 
 ple colour, and adheres to the fkin fo that it is difficult 
 to efface the impreffion J. 
 
 17. Soap of manganefe. — It is at firft white, but it 
 afliimes iu the air a reddifli colour, owing evidently to 
 
 Acid 
 
 61- 
 
 UiJ. 
 
 60S 
 Si lap of 
 bLnzoin, 
 
 i in J. 
 606 
 Ai a of 
 lapga Cj^^g abforption of oxygen. It fpeedily dries to a liard 
 brittle fubftance, and by liquefaction affumes a brown 
 blackifli colour J. 
 
 We owe the following refinous foaps to Mr Me- 
 gQy zai7e. 
 Soapcftur- ife. "Soap of turpentine and potafs. — 576 grains of 
 pemine a^Jturpentine were diirolved in 9216 grains of alcohol, and 
 rpotafo. then ^76 grains of potafs ucve added. The alcohol 
 was dilb'lled off at a boiling water heat. There remain- 
 ed in the retort 648 grains of a browiiifh foapy matter, 
 which when fpread on glafs appeared tranfparent. There 
 remained alio nearly the fame quantity of potafs diffol- 
 ved in water. This foap was put in a vefFel for fix 
 weeks ; during which time 72 grains of fulution of pot- 
 afs feparated from it. It bad aflumed the confillence 
 of honey. Its colour was browner. It was completely 
 foluble in water : the folution was milky. It diffolved 
 alfo in alcohol. It had no difagieeable tafte. Vinegar 
 decorapofed it. 
 
 19. Soap of benzoin and potafs. — By treating 9216 
 grains of alcohol, 1728 grains of benzoin, and 576 
 grains of potals, as above, 1728 grains of a foap were 
 obtained, browner than that of turpentine, of an odour 
 a little aromatic. When left in a cellar for fix weeks, 
 it became folld. Its folution in water was yellowhh. 
 Vinegar decompofed it. This compound is the fame 
 §3- with Starkey's foap. 
 Of balm of 20. Soap of balm of Peru and potafs — 1152 grains 
 Peru, of balm, 2304 grains of potafs, and 9216 grains of al- 
 
 cohol, produced a foap of a reddiih colour, and pretty 
 confiltent. 
 
 21. Soap of guaiac and potafs. — 1728 grains of guai- 
 ac was diflblved in 18648 grains of alcohol, and the fo- 
 lution filtered, and to this 1728 grains of potafs were 
 added, and the foap obtained as above. It was folid, of 
 a brown colour at firll, which afterwards became green 
 on the furface, but remained unaltered within. Its fo- 
 lution in water was greenifh. It had no difagreable tafte. 
 It diflblved in alcohol, and formed a green tinfture. Vi- 
 negar decompofed it. 
 
 2 2. Soap of fcammony and potafs. — By the above 
 f^ammony. procefs a foap was obtained with fcammony pretty con- 
 fiif ent, of a brown colour, foluble in water, and not de- 
 compofed by the water of pits from which felenites is 
 obtained. It has no difagreeable tafte. Its folution in 
 alcohol is of a deep amber colour ||. 
 
 S E c T . II . 0/ Acid Soaps. 
 
 Sulphuric acid may be combined with oils in the 
 following manner : Put two ounces of it into a glafs 
 
 610 
 
 Of gbaiac, 
 
 611 
 
 And of 
 
 11 Jtar. dc 
 FhyJ. XV. 
 
 4+1- 
 
 6il 
 Method of 
 foi mir\^ 
 
 »cid foaps. mortar, and add, by little and little, three ounces of the 
 
 oil nearly boiling hot, triturating it coiiftantly. A fub- 
 llani-e is obtained of the confiftence of turpentine. Dif- 
 folvc it in about fix ounces of boiling water, and the 
 f<iap will unite into a mafs as the water cools If it 
 ft ill contain an excefs of acid, diffolve it again iu boil- 
 ing water, and coiiliiiuc thii procefs till the foap is per- 
 fedtlv neutralized. 
 
 1. Soap ot fidphuric acid and lintfeed oil. — It dif. Acid'foa* 
 folves entirely in water. The folution is o)iaqiie, of a of lintfeed 
 bluifli white colour, vifcid, and frothes whiii ai^itated."''' 
 Alcohol diffolves it. The folution is tranfparent and 
 brown. Potals decompofes it, forming fulpliat of pot- 
 afs. The oil fwims on the top, of the confiftence of 
 
 wax. Ammonia decompoles it ; and if too much be 
 added it forms foap ot ammonia. Mauncna, lime, ni- 
 trie acid, and muriatic acid, alfo decompofe it. Dillilled, 
 it yielded a few drops ot water and an oil, which coagu- 
 lated, and W.1S of the confiftence of wax. , 
 
 2. Soap of fulphuric acid and oil of almonds.^ So- Of almond 
 luble in water; folution milky. Frothes. Soluble in oil. 
 alcohol ; folution brown and tranfparent. Potafs, lime, 
 
 nitric acid, muriatic acid, fulphurous acid (the oil fepa- 
 rated aftumed the confiftence of turpentine), tartar, aci- 
 dulous oxalat of potafs, fal ammoniac, muriat of lead 
 and zinc decompofe it. It is not decompofed by vi- 
 negar, boracic acid, acetite of ammonia, borax, copper, 
 tin, nor lead. When diftilled, there pafted over a little 
 water and an oil, u'hich coagulated and fmelt very ran- 
 cid : there remained behmd a coal. 5,^ 
 
 3. Soap of fulphuric acid and olive oil.— It is brown, Of olive 
 and of the confiftence of wax. Solution in hot water°"> 
 wliice, opaque, vifcld ; frothes. Solution in alcohol 
 tranfparent and brown. Potafs, ammonia, magnefia, 
 nitric acid, muriatic acid, vinegar, nitre, fal ammoniac, 
 acetite of lead and white oxide of lead, decompofe it. g , 
 
 4. Soap of fulphuric acid and butter of cocao. — It is Of butter 
 hard, and marbled like Venice foap. Solution in waterof cocao, 
 grey, ojiaque, vifcid; frothes. Solution in alcohol yel- 
 low and tranfparent. Potafs, ammonia, nitric, muriatic, 
 
 and acetous acids, tartar, lal ammoniac, tartrite of pot- 
 afs, acetite of lead, and zinc in powder, decompofe it. 
 When diftilled, there came over water, an oil that coa- 
 gulated, and a few drops of a black oil, which alfo con- 
 gealed : both were rancid. gj. 
 
 5. Soap of fulphuric acid and virax. — It is white, and of wax, 
 becomes very hard. Its folution in water is white, and 
 opaque, aid frothes: Its folution in alcohol is yellow 
 
 and tranfparent. Potafs, ammonia, nitric and muriatic 
 acids, decompofe it. g,g 
 
 6. Soap of fulphuric acid and fpermaceti. — It isOf fperma. 
 brown. It diffolves in water: the folution is milky, "'■> 
 vifcid, and frothes on agitation. It diffolves in alcohol ; 
 
 the folution is tranfparent and yellow. It is decompo- 
 fed by as much alkali as iaturates the acid : if more be 
 added, it unites with the oil, and forms a new foap. 
 Lime and magnefia decompofe it. The oil is alfo fe- 
 parated, and appears in the form of a coagulum on add- 
 ing to the folution nitric acid, muriatic acid, tartar, 
 nitre, nitrat of foda, common fait, and zinc in powder; 
 but not on adding vinegar, tin, lead. 6ij 
 
 7. Soap of fulphuric acid and oil of eggs. — Its folution Of oil <^ 
 in water is white, opaque, vifcid; frothes : that in alco-"^88'' 
 hoi yellow and tranfparent. Alkalies decompofe it ; 
 but if too much be added a new foap is formed. Nitric 
 and muriatic acids feparate the oil of the confiftence of 
 
 wax,
 
 Part III. 
 
 CHEMISTRY. 
 
 359 
 
 Neutril 
 Salts. 
 
 670 
 
 Of turpen- 
 :iiie, 
 
 6ii 
 Ard of am. 
 ber oil. 
 
 * Jnrn. ic 
 
 ftyf.xsi. 
 
 \°9- 
 
 wax, the firft yellow, the !ail a deep brown. Nitre, 
 fal ammoniac, acetite of lead, iron iilings, zinc powder, 
 decompofe it ; vinegar, borax, iilings of lead do not. 
 
 To unite this acid with the efTtntial oils, three ounces 
 were put into a glafs mortar, and four ounces of the 
 oil were added drop by drop, and care taken to pre- 
 vent Its becoming hot : equal parts of water were then 
 poured on, and the whole heated flowly nearly to the 
 temperature of boiling water : on cooling, the foap 
 united into a brown mafs. 
 
 8. Soap of fulphuric acid and turpentine. It is brown, 
 and of the confitlence of foft wax. Its folution in wa- 
 ter is grey, opaque, vifcid ; frothes : Its folution in al- 
 cohol IS brown and tranfparent. Alkalies decompofe it : 
 with too much it forms at the boiling heat a new foap. 
 
 Nitric and muriatic acids feparated the oil thicken- 
 ed, as did alio white oxide of lead, muriat of lead, mu- 
 Tiat of foda and iron filings ; but acetous acid, boracic 
 acid, tartrite of potafs, and tin iilings, produced no fuch 
 effeft. 
 
 p. Soap of fulphuric acid and amber oil. — Its folution 
 in water and alcohol as in the laft foap. Alkalies, mag- 
 nefia, and lime, decompofed it. Nitric and muriatic acids 
 feparated the oil of the confiftence of wax. Tartar, fal 
 ammoniac, muriat of antimony, acetite of lead, iron 
 iilings, decompofed it ; vinegar, acetite of ammonia,, 
 and lead did not. 
 
 Mr Achard, to whom we owe thefe foaps *, could 
 not fucceed in his attempts to form foaps with nitric 
 and muriatic acids. < 
 
 Chap. II. 0/" Neutral Salts. 
 
 6l% 
 Salt ex- 
 lUincd. 
 
 The -worAJalt has been ufed in chemiftry in a very 
 extenfive, and not very detinite fenfe. Every body 
 which is fapid, eafily melted, foluble in. water, and not 
 combullible, has been called z fait. 
 
 Salts were confidered by the older chemifts as a clafs 
 of bodies intermediate between earths and water. Many 
 difpiites arofe about what bo.lies ought to be compre- 
 liended under this clafs, and what ought to be excluded 
 from it. Acids and alkalies were allowed by all to be 
 falts ; but the difficulty was to determine concerning 
 earths and metals. Several of the earths poflefs all the 
 properties which have been afcribed to falts ; and the 
 metals are capable of entering into combinations which 
 poiTcfs faline properties. It is needlefs for us to enter 
 into this difpute at prefent, as we have taken, the liber- 
 ty, in imitation of fome of the bell modern chemifts, to 
 expunge the clafs of falts altogether, and to arrange 
 thofe i'ubordinate claffes, which are ufually referred to 
 J,, it, under diftinft heads, 
 ftutralfalt The word neutral fait was originally applied exclu- 
 iflained. furely to combinations of acids and alkalies, which were 
 confidered as fubftances poffeffing neither the properties 
 of acids nor alkalies, but properties intermediate between 
 the two. But the word is now always taken in a more 
 extenfive fenfe, and fignifies all compounds formed by 
 the combination of acids with alkalies, earths, or metal- 
 lic oxides. In thefe compounds, the earth, alkali, or 
 oxide, is denominated the lafe. Each order of falts is 
 
 denominated after the acid which enters into its compo- Su!phats. 
 fition ; and every individual fait is dillinguilhed by fub- >'"'"" 
 
 joining the name of its bafe. Tluis all the falts into 
 which fulphuric acid enters arc calkdyu.y'/«/j, and the 
 fait formed by the combination of fulphuric acid and 
 potafs is c^Wt:A fulphat of potafs. 
 
 It is evident, then, that there muft be as many orders of- 
 neutral falts as there are acids ; and as many falts in each 
 order as there are alkalies, earths, and metallic oxides,- 
 fuppofing every acid capable of combining with every 
 one of thefe fubftances. But befidcs thefe fimple com- 
 binations of one acid and one bafe, there are others more 
 complex, compofed of two acids combined with one 
 bafe, or two bafes combined with one acid, or a neutral 
 fait combined with an acid or a bafe. Thefe combina- 
 tions have been called triple falts ; and they increafe the 
 number of neutral falts very confiderably. 
 
 In the following feftions we (hall take a (hort view 
 of the properties of the principal neutral falls at pre- 
 fent known ; for this wide and important region of che- 
 miftry is Itill very far from being completely explored. 
 
 Sect. I. Of Sulphats. 
 
 Sulphuric acid is capable of combining with all the 
 alkalies, with alkaline earths, alumina, jargonia, and 
 the greater number of the metallic oxides. The prin- 
 cipal neutral falts which it forms are as follows : 6,4 
 
 I. Sulphat of potafs. — This fait may be formed byS.lphatof. 
 faturating diluted potafs with fulphuric acid, and theuf'-'f'- 
 evaporating the folution gently till cryftals are formed. 
 It feems to have been known at a very early period by 
 chemills, and a great variety of names were given to it, 
 according to the manner of forming it, or the fancy of 
 the operator. Some of thefe names were, fpecijicum 
 purgans, tiitrum fxum, arcanum duplkatum, panacea bol- 
 fatica, fal de duohus, fal polychrtjl glafcri, &c. ; but it 
 was commonly known by the name of vitrhlatfd tartar 
 till the French chemifts called 'w fvlphal of potafs-, when 
 they.fnrmed their new nomenclature in 1787 (k). g 
 
 When the folution of fulpliat of potafs is fufficiently itsjironer-.' 
 diluted, it affords by evaporation hexahedral pyramios, tits. 
 or fliort hexangular prilms, terminated by one or more 
 htxangular pyramids. But tiiefc cryftals vary much in 
 their figure, according to the care with which they are 
 prepared. 
 
 It has a very difagreeable bitter tafte. Its fpecific ' 
 gravity is 2,298*. _ _ * griffon. 
 
 It is foluble in the temperature of GoP m 16 times 
 its weight of water ; in a boiling heat, it is foluble in 5 
 times its weight f. ^ Scr^man, - 
 
 According to Bergman, it is compofed of 40 parts 
 of acid, 52 parts of alkali, and 8 of water; but accord- 
 ing to Kirwan, whofe experiment has been already de- 
 Icribed, it is compofed of 45 parts of acid and 55 of 
 alkali.. 
 
 It fuffers no alteration in the air. 
 
 When placed upon burning coals, it breaks into 
 
 pieces with a noife rcfembiing a number of imall explo- 
 
 fions fucceeding each other at fliort intervals ( l), but 
 
 fuffers no other alteration. In a red heat it melts. 
 
 It has hitherto been applied to little ufe. It is a 
 
 purgative. 
 
 ( K ) Bergman called it allali •uegetah'tlt vitriolalam^ and Morveau vitriol of potafs. 
 (l) This is called decrepitation.
 
 C H E M I 
 
 purgative, but I'n difugreeable ta.le prevents it from 
 being much employed for that purpofe. 
 
 It often has aii excefs of acid, owing, as Mr Berg- 
 man and Morveau have very ingenioully explained, to 
 an affinity which exids between this fait and fulphuric 
 acid. 
 
 It is decompofed by compound affinity by the f(jl. 
 lowing; falts : 
 
 • Xlrxvan. 
 
 J Bergman. 
 § /</. 
 
 jinn, de 
 
 Chim. vi. 
 
 99. 
 
 % Ann. de 
 
 Cb'tm. X. 40. 
 
 646 
 Suiphat of 
 (oda. 
 
 Nitrat of foda (m), 
 lime. 
 
 barytes*, 
 ilrontites f , 
 ammonia, 
 ■ magnefia, 
 mercury. 
 
 Nitrat of filver, 
 
 lead, 
 
 Acetite of barytea, 
 Muriat of lime J, 
 
 lead ^, 
 
 magnefia? 
 
 foda 11 . 
 
 *Tr\Jh 
 
 Tninf. iv. 
 
 It is fometimes luminous in the dark, as Mr Giobert 
 has obferved ^. 
 
 2. Sulphat of foda. — This fait was firft difcovered by 
 Glauber a German chemiil, and for that reafon was 
 long known by the name of Glauber's fait. He him- 
 felf called it fal m'irabik. It may be prepared by fa- 
 turating foda with fulphuric acid, but is more ufually 
 obtained by decompofing common fait in order to pro- 
 cure muriatic acid. 
 
 Its cryilals are tranfparent, and when formed by flow 
 evaporation, are fix-fided prifms terminated by dihedral 
 fummits. 
 
 Its tafte at firft has fome refemblance to that of com- 
 mon fait, but foon becomes very difagreeably bitter. 
 
 It is foluble in 2,67 times its weight of water at the 
 temperature of 60°, and in 0,8 of boiling water. 
 
 It is compofed, according to Bergnia-n, of 27 parts 
 of acid, I 5 of alkali, and 58 of water ; -but, according 
 to the experiments of Kirwan, of 22 parts of acid, 17 
 of alkali, and 61 of water. 
 
 When expofed to the air, it lofes great part of its 
 water, and falls into a white powder (nj. 
 
 When expufed to heat, it firft undergoes the luatery 
 fufion (o), then its water is evaporated, it is reduced 
 to a white powder, and at lall in a red heat it melts. 
 Mr Kirwan has obferved, that part of the acid, as well 
 as the water, is driven off by the application of a flrong 
 heat *. 
 
 This fait is ufed as a piirgative. 
 
 It often combmes with an excefs of acid. 
 
 It is decompofed by compound affinity^ by the fol- 
 lowing fubftances : 
 
 Sulphst of 
 ammonia. 
 
 Nitrat of lime, 
 
 magnefia, 
 
 Muriat of potafs, 
 
 — — — foda, 
 
 — — magnefia, 
 
 lime f , 
 
 3. Sulphat of ammonia.- 
 
 Acetite of barytes, 
 
 potafs, 
 
 lime, 
 
 Carbonat of barytes, 
 potafs. 
 
 •This fait was difcovered 
 by Glauber, and called by him fecret fal ammoniac. It 
 was alfo called •v'ltr'tolated ammoniac. It may be prepa- 
 red by faturating ammonia with fulphuric acid. 
 
 Its cryftals are generally fmall fix-fided prifms, whofe 
 planes are unequal, terminated by fix-fided pyramids. 
 
 Part Ilf, 
 
 Affinity, 
 
 S T R V. 
 
 It has a ftiarp bitter taftei 
 
 It is foluble in twice its own weight of water at the ^"~"V"~^ 
 temperature of 60', and in its own weigfit of boiling 
 water. 
 
 According to Mr Kirwan, it is compofed of 29,7 of 
 alkali, 55,7 of fulphuric acid, and 14,16 of water*. • Jrilh 
 When expofed to the air, it flowly attrafts moifture. Tm/i/. ihid. 
 When heated, it firfl decrepitates, then nieiis.andia 
 clofe veffels fublimes, but with fonie lofs of its alkali f . t Kir-wa»t 
 It has not hitherto been applied to any ufe. Mineml. 
 
 It is apt to contain an excefs of acid. " *■ 
 
 It is decompofed by compound affinity by the fol- 
 lowing falts : 
 
 Acetite of foda, 
 
 — barytes, 
 
 lime, 
 
 magnefia, 
 
 Carbonat of potafs, 
 
 . — foda, 
 
 barytes, 
 
 lime, 
 
 magnefia. 
 
 Nitrat of lime, 
 
 magnt 
 
 fia 
 
 — mercury f 
 
 Muriat of potafs, 
 
 — — foda, 
 
 ■■■ barytes, 
 
 lime, 
 
 — — magnefia. 
 
 • Eirgma»f 
 
 1 
 
 mercury" 
 
 Phofphat of lime f . 
 
 ^Dcliejkamf 
 Ann. de 
 
 Acetite of potafs, 
 
 4. Sulphat of barytes. — This fubltance was firfl dif- "q^I^ ^,_ 
 covered by Scheele. It abounds in nature. It is ge-37. 
 nerally in the form of a hard, very heavy, ftone. 62S 
 
 It is fometimes found cryftalli-.ied ; but the variety of ^"'P*^^' °^ 
 forms is fo great that they bafile all defcriptiou. " 
 
 It is foluble in 43,000 times its weight of water at 
 the temperature of the atmofphere {|. || Kirwan 1 
 
 Sulphuric acid diffolves it when concentrated and •''^"' '• 
 boiling, but it is precipitated by the addition of wa- '-^ ' 
 ter. 
 
 When expofed to heat it melts, and, if the heat be 
 very rtrong, gradually dilTipates. g 
 
 After being heated red hot, it has the property of Bflngiu 
 being luminous in the dark. This was firft obferved fcoue. 
 in a variety of this fubllance known by the name of Bo- 
 logna ftone. Lemery informs us, tliat this property 
 wa« fiHl difcovered by an Italian fhoemaker named Vin- 
 cenzo Cafciarolo. This man found a Bologna ftone at 
 the foot of Mount Paterno, and its brightncfs and gra- 
 vity made him fuppofe that it contained filver. Having 
 expofed it to the fire, doubtlefs in order to extraft from 
 it the precious metal, he obferved that it was luminous 
 in the dark. Struck with the difcovery, he repeated 
 the experiment, and it conftantly fucceeded with him. 
 
 From an experiment of Mr Klaproth, it appears to 
 be compofed of ^5 parts of acid and 77 of barytes. 
 
 It is decompofed by compound affinity by the fol- 
 lowing falts : 
 
 Nitrat of foda, Nitrat of magnefia, 
 
 — — lime, Carbonat of potafs, 
 
 — — ammonia, foda*. \\ Afiwtlha. 
 
 5. Sulphat of lime This fubftance was well known *3o 
 
 to the ancients under the name gypfum ; but the^^'P*^**" 
 compofition of gypfum was not known till Margraf 
 
 and Macquer analyfed it, aud proved that it was com- 
 
 pofed of fulphuric acid and lime. The artificial com. 
 
 pound 
 
 (m) Moft of thefe double decompofitions in this and the following feftions are inferted on the authority of 
 Morveau. See his Table of Affinity, page 360 of this article. 
 
 (n) This is called efflorefcing. 
 
 (o) When fubftances melt by means of the water they contain on the application of heat, they are faid to 
 undergo the watery fufion.
 
 part IIL C H E M 
 
 Siilphats. pound formed by the union of thefe two bodies was for- 
 *■ tT-"— tnerly called /(7i'n(Vi'. 
 
 It is found cryftallized in various forms, fometiraes 
 tranfpaient and lometimes opaque ; and when pure it is 
 of a white colour. 
 
 It has a (lightly naufeous tafte, fcarcely perceptible 
 except by drinking a glafs of water impregnated with 
 * Macqtier. it *. 
 
 It is folnble in ^oo parts of water at the tempera- 
 ture o. 60°, but much more fuluble in boiling water. 
 
 It is compofed, according to Bergman, of 46 parts 
 of acid, 32 of earth, and 22 of water: according to 
 the late experiments of Mr Kirwan, when fo far dried 
 as ftill to retain its glalTy appearance, it contains 48 of 
 acid, 34 of earth, <iiid i8 of water ; which diflcrs very 
 little from the determination of Bergman. 
 
 It is not affeSed by expofure to the air. 
 
 It is foluhle in fulphuric acid. 
 
 When espofed to heat. It undergoes a kind of wa- 
 tery .fufion, but afterwards it cannot be melted by the 
 ftrongeft heat. In a clay crucible indeed it fuies at 
 I :^o^ VVedgewood, owing evidently to the prefence of 
 the clay. 
 
 When heated red hot and cooled, it is called plajler 
 of Paris ; a fubftance fo ufeful for calling moulds, &c. 
 on account of its property of becoming folid almoil im- 
 mediately when reduced into a paile with water. 
 
 By compound affinity it is decompofed by the follow- 
 ing fubftances : 
 
 Acetite of barytes, 
 potafs. 
 
 I S T R Y. 
 
 \(M 
 
 631 
 
 Plafter of 
 Paris. 
 
 Carbonat of potafs, 
 foda. 
 
 Carbonat of barytes, 
 
 ^ Berginart, 
 
 Siil^nat of 
 iliuntices. 
 
 magnefia? 
 alumina-j-. 
 
 6. Sulphat of ftrontites. This fait, firft formed by 
 
 Dr Hope, is a white powder deilitute of tafte. It is 
 
 fohible in 3840 parts of boiling water. Sulphuric acid 
 
 dilfolves it readily when affifted by heat, but it is preci- 
 
 J Dr Hope, pitated by the addition of water to the folution;];. 
 
 Trjnf. EJin. y. Sulpliat of magnefia. This fait was firft obferved 
 
 "■ '°- in the fprings at Epfom in England by Grew in 1675; 
 
 SulDhat nf ^^^ ^'^ Black was the firft who accurately afcertained 
 
 magntlia. its compolition. It has been called Epfom full, fal CU' 
 
 tharticus amarus, and Seydler fait. 
 
 It cryftallizes in quadrangular prifms, whofe plains 
 are equal, furmounted by quadrangular pyramids. 
 It has an exceffively bitter talle. 
 At the temperature of 60° it is foluble in its own 
 weight of water, and in ^ths of its weight of boiling 
 water. The volume of water is increafed jth by add- 
 $ Bergman, ing the fait §. 
 
 It is infoluble in alcohol. 
 
 It is compofed, according to Bergman, of 1 9 parts 
 of earth, 33 of acid, and 48 of water ; according to 
 Mr Kirwan, of 17 parts of earth, 29,46 of acid, and 
 53, J4 of water. 
 
 When cxpofcd to the air it eiBorefces, and is reduced 
 to powder. 
 
 When expofed to heat it undergoes the watery fu- 
 fion, and by increafing the temperature its water is eva- 
 Suppt* Vol. I. Part. II. 
 
 porated, but it cannot be decompofed by means of Sul; liau. 
 heat. ' 
 
 It is fometimes employed as a cathartic, but its chief 
 ufc is to furnifti magnefia by its dccompofition. 
 
 It is decompofed by compound affinity by the fol- 
 lowing falts. \ 
 
 Acetite of lime, 
 
 Carbonat of barytes, 
 
 potafs, 
 
 foda *, » Be 
 
 ammonia (q^). 
 
 Muriat of potafs, 
 
 foda (p), 
 
 lime, 
 
 Acetite of barytes, 
 — — potafs. 
 
 •gman. 
 
 634 
 
 .S. Sulphat of ammonia and magnefia. This triple '''"'p''=>t of 
 fait was difcovered by Mr Fourcroy. Into the folution^"*""""'" 
 of 100 parts of fulphat of magnefia in 500 parts of wa-nenaT*^* 
 ter, 12 parts of ammonia being poured, a very fmall 
 quantity of magnefia was precipitated, and a confider- 
 able quantity more on the addition of another dole of 
 ammonia; but farther additions had no effeft. From 
 the magnefia precipitated, it appeared that 38 pans of 
 the fulphat had been decompofed. There remained, 
 therefore, 62 parts in folution, mixed with a large quan- 
 tity of ammonia. By evaporation, 92 parts of a white 
 tranfparent rhomboidal fait were obtained, evidently 
 compofed of fulphuric acid, ammonia, and magnefia, in 
 the proportions that would have formed 62 parts of fuU 
 phat of magnefia and 30 of fulphat cf ammonia, and 
 probably confifting of a combination of thefe two ful- 
 phatsf. ^^nn.Ji 
 
 9. Sulphat of alumina. This fait m.ay be formed hyCNm. iv. 
 diffblving alumina in fulphuric acid. It has an ailrin-*"; 
 gent tafte, is very foluble in water, and cryftallizes in SulphL of 
 thin plates which have veiy little confil'a-ncef . Little aliimira. 
 attention has hitherto been paid to this fait, which was* ^'"u^'i'^'it 
 never properly diftlnguilhed from alu?n till two memoirs, f""'"' -, 
 one by Vauquellu and another by Chaptal, on the na- aj^^and"* 
 ture of alum, made their appearance in the 22d volume Ch.iptal, 
 of the Annates de Chimie. This fait generally contains'*"'- **+• 
 an excefs of acid, and is not neutralized without con- 
 fiderable difficulty J . ( UtJ. p. 
 
 10. Sulphat of alumina and potafs, or alum. The*^"^" , 
 trrurr.pi^ of the Greeks, and the alumen of the Romans, ^iJn,^ 
 was a native fubftance, which appears to have been 
 nearly related to grnn iiitriol or fulphat of iron ; and 
 which confequently was very different from what we at 
 prefent denominate alum. From the refcarchcs of Pro- 
 feffor Beckmann, it appears that we owe the difcoveiy 
 
 of alum to the Afiatics ; but at what period, or by 
 what means, the difcovery was made, is altogether un- 
 known. 
 
 It continued to be imported from the Eaft till the 
 I ^th century, when a number of alum works were efta- 
 bliihed in Italy. In the 16th century it was manufac- 
 tured in Germany and Spain ; and durliig,Queen Eli- 
 zabeth's reign an alum work was eftabliftied in England 
 by Thomas Chalomer. 
 
 The alum of commerce is ufually obtained from 
 earths containing fulphur and clay, or fulphuric acid 
 and clay. 
 
 The compofition of alum has been but lately under- its compo- 
 Z z ftoodCtion, 
 
 (?) Only below the temperature of 32". Scheele, Gren, ./inn. de Chitn. xxiii. 
 (cl) Only below the temperature of 2ia°. Fourcroy^ jhid. ii. 791.
 
 362 
 
 CHEMISTRY. 
 
 Sulphats. ftood with accuracy. It has been long known, indeed, 
 ' that one of its ingredients is fiilphurie acld(R) ; and 
 the experiments of GeofTroy, Hellot, Pot, Margraf, 
 and Maoquer, proved inconteftibly that alumina is an- 
 other ingredient. But fulphuric acid and alumina are 
 incapable of forming alum : Mjnufafturers knew, that 
 iHt addition of a quantity of potafs, or of ammonia, or 
 of fome fubllance containing thefe alkalies, is almoft al- 
 ways neccfiary ; and it was proved, that in every cafe in 
 which fuch additions are iinnecefTary, the earth from 
 which the alum is obtained contained already a quan- 
 tity of potafs. Various conjectures were made about 
 the part which potafs afts in this cafe; but Chaptal and 
 Vauquelin appear to have been the firft chemifts that 
 afcertained, by decifive experiments, that alum was a 
 triple fait, compiled of fulphat of alumina and of pot- 
 638 afs united together (s) 
 And pro- Alum crylUllizes in large oftahedrons, compofed of 
 perries. ^^^^ tetrahedral jvyraiiiids^ applied to each other at their 
 
 bafes. 
 
 It has a fweetifh and aflringent tafte, and always red- 
 dens the tincture of turnfole. 
 • N!umann j^ j^ foUible at the temperature of 60°, in from 1 o * 
 r^/>Tr^^'''to 15 t t™fs its own weight of water, according to its 
 vid Chaptal.-^anty ; pure alum being mod infoluble. Seventy-five 
 :J Bergman, pgrts of boiling-water diffolve 100 of alum J. 
 
 A hundred parts of alum contain, according to Kir- 
 , r, . wan, 17,62 parts of acid, 18 of earth (and alkali), and 
 i^/B ii.14. 64,38 of water ^. 
 
 When expofed to the air it efflorefces (lightly. 
 When expofed to a gentle heat it undergoes the wa- 
 tery fufion. A ftrong heat caufes it to fwell and foam, 
 and to lofe about 4.4 per cent, of its weight, confiiting 
 l^iii- (.(jiefly of water of cryftallizationll. What remains is 
 called calcined or burnt alum, and is fometimes ufed as a 
 corrofive. 
 / " Alum is of great importance as a mordant in dyeing, 
 
 and is ufed alfo in feveral other arts. 
 
 By compound affinity it is decompofed by the fol- 
 lowing falts. 
 
 Partlir. 
 
 Homberg'fr 
 ryropho- 
 
 Nitr^ of foda, 
 . lime, 
 
 ammonia, 
 
 magncfid, 
 
 Muriat of barytes, 
 
 . potafs, 
 
 foda, 
 
 lime, 
 
 - ammonia, 
 
 ■ magnelia, 
 
 Acetite of barytes, 
 
 Acetite of potafs, 
 
 foda, 
 
 . . . lime, 
 
 ammonia, 
 
 magnefia, 
 
 Carbonat of barytts, 
 
 potafs, 
 
 - ■ foda, 
 
 lime, 
 
 — — — — — ammonia, 
 macrnefia. 
 
 If three parts of alum and one of flour or fugar be 
 
 melted together in an iron ladle, and the mixture dried Suljihatj. 
 till it becomes blackifh and ceafes to fwell ; if it be *— -v— ' 
 then pounded fmall, put into a glafs phial, and placed in 
 a fand-bath till a blue flame iffues from the mouth of 
 the phial, and after burning for a minute or two be al- 
 lowed to coo1(t), a fubllance is obtained known by the 
 name of Homberg's pyrophorus, which has the property 
 of catching fire whenever it is expofed to the open air, 
 efpecially if the air be moift. 
 
 This fubftance was accidentally difcovered by Hom- 
 berg about the beginning of the 18th century, while he 
 was engaged in his experiments on the human fieces. 
 He had dillilled a mixture of human fgeces and alum 
 till he could obtain nothing more from it by means of 
 heat ; and four or five days after, while he was taking 
 the refiduum out of the retort, he was furprifed to fee it 
 take fire fpontaneoufly. Soon after Lemery the Young- 
 er difcovered that honey, fugar, flour, or almoft any 
 animal or vegetable matter, could befubftituted for hu- 
 man fzeces ; and afterwards Mr Lcjoy de Suvigny fliew- 
 ed that feveral other falts containing fulphuric acid 
 might be fubilituted for alum *. Scheele proved, that * See Af^r. 
 alum deprived of potafs was incapable of finrming py. ?""■'' C/a. 
 rophorus, and that fulphat of potafs might be fubilitu- 
 ted for alum \. And Mr Prouft has fliewn, that a num-f Scheeli on 
 ber of neutral falts, compofed of vegetable acids andal-^""'- ""^ '* 
 kalies, or earths, when diftlUed by a fl^rong fire in a ^e- J"'"'^*'"''"' 
 tort, left a refiduum which took fire fpontaneoufly on 
 expofure to the air. 
 
 Thefe facts have thrown a great deal of light on the 
 nature of Homberg's pyrophorus, and enabled us in 
 fome meafure to acjou'nt for its fpontaneous inflamma- 
 tion. It has been afcertained, that part of the fulphu- 
 ric acid is decompofed during the formation of the py- 
 rophorus, and of courfe a part of the alkaline bafe be- 
 comes uncombined with acid, and the carbon, which 
 gives ii its black colour, is evidently divided into very 
 minute particles. It has been afcertained, that during 
 the combuflion of the pyrophorus a quantity of oxygen 
 is abforbed. The inflammation feems to be owing to a 
 d'ljpofng ajintty. Part of the carbon and of the fulphur 
 attraft oxygen from the atmofphere, in order to com- 
 bine with the potafs, and the caloric difengaged pro- 
 duces a temperature fufhciently high to kindle the reft 
 of the carbon. 
 
 Alum is capable of combining with alumina, and of 
 forming what has been called alum faturated 'with its 
 earth, which is an infoluble, taftelefs, earthy-like fub- 
 llance. 
 
 It is capable alfo, as Chaptal informs us, of combi- 
 ning with feveral other bafes, and of forming many 
 triple falts, which have never yet been examined with 
 attention %. f ^„„. a 
 
 II. SulphatCAiw. uii, 
 J93. 
 
 (r.) Rome chemifts have thought proper to call the fulphuric acid, obtained by diftilling alum.^inV of alum. 
 
 (s) This they did in the two memoirs above quoted, and which were firft publiflied in the 22d volume of the 
 Annales deChimie. An account of Vauq\ielin's memoir has been already given under the article Alum in this 
 Subbhmint. Chaptal's memoir is no lefs interelting. This celebrated chemift appears, from the fafts ftated in 
 the 2?d volume of the Annales, p. 222. to have made his difcovery before Vauquelin : who, however, was igno- 
 rant of what Chaptal had done, as he informs us in the Jnn. de Chiin. xxv. 107. that his paper was read to the 
 Inftitute a fortnight before that of Chaptal's came to Paris. He informs us, too, that Defcroifilles bad long be- 
 fore made the fame difcovery, and that he had publiflied it in BerthoUet's Jrt de la Teinlure. 
 
 (t) Care mull be taken not to keep it too long espoftd to the heat.
 
 Part III. 
 
 C H E M 
 
 Sulpliao. 
 
 640 
 Su phat of 
 jargonia. 
 
 ♦ yatiguc' 
 lln, An:!' •/« 
 Cbia. xxii. 
 
 199- 
 
 f Jour. Jc 
 
 fhyf. XXXvi. 
 
 187. 
 
 641 
 Green ful- 
 
 (ihaiof irunc 
 
 ) Lit. ixxiv 
 c. I]. 
 
 j Bergman, 
 
 II. Sulphat fif jargonia (u). In order to combine 
 'jargonia with acids, they fliould be poured upon it while 
 it is yet moilt, after being precipitated from fome of its 
 folvents ; for after it is dry, acids do not aCt upon it 
 without difficulty. By this method fulphat of jarjTo- 
 nia is eafdy formed. It is white, and without fenfiblc 
 tafte. Heat expels the acid from it, and the jargonia 
 remains in a ftate of purity. At a high temperature 
 charcoal converts it into a fulphuret, which is foluble in 
 water, and which, by evaporation, furnifhes cryrtals of 
 hydrofulphuret (t) of jargonia*. 
 
 Klaproth informs us, that with excefs of acid ful- 
 phat of jargonia forms tranfparent ftelllform cryllals, fo- 
 luble in water, and having an afhingent talle \. 
 
 I 2. Sulphat of iron. There are two fulphats of iron, 
 which were firll accurately dlllinguiflied by Mr Prouft. 
 The one contaixis the green oxide, the other the red 
 oxide of iron. We fliall, in imitation of Mr Prouft, de- 
 nominate them from their colours. 
 
 The green fulphat of iron. — This fait, which is com- 
 ■pofed of fulphuric acid and green oxide of iron, is found 
 native, and was known to the ancients. It is mention- 
 ,ed by Pliny under the names of mify,fory, calchantum \. 
 It was formerly called green vitriol. 
 
 It is generally prepared by expofmg native fulphuret 
 of iron, a vei-y abundant mineral, to air and moifture. 
 
 Its cryftals are of a light green colour, and in the 
 form of rhomboidal parallelopipeds. 
 
 It has a Iharp aftringent talle. 
 
 It is foluble in fix times its weight of water at the 
 temperature of 60°, and in |ths of its weight of boil- 
 ing water ^. 
 
 It is infoluble in alcohol. 
 
 According to Bergman, it is compofed of 39 parts 
 
 I S T 11 Y. 36J 
 
 of acid, 2^ of oxide, and 38 of water; but according Sulihati. 
 to Mr Kirwan, of 26 parti of acid, 28 (u) of oxide, ——r-"-' 
 and 46 of water. 
 
 When expofcd to the air, it efflorefccs ; but if it be 
 moillened, it is gradually converted into red fulphat of 
 iron. 
 
 When heated, it firft aflTumes a yellow colour, lofes 
 its water and its acid ; if the heat be increafed, no- 
 thing remains but a yellow powder. 
 
 Tlie Pruflic alkali precijiitates from the folution of 
 this fait a white powder, which gradually becomes blue 
 by attrafting oxygen *. » Preu/t. 
 
 It is ufed in dyeing, and in making ink, &c. 
 It is decompofed by compound affinity by 
 Nitrat of filver, 
 
 Muriat of foda f . ^ b„//^„ ^/ij 
 
 The rfj fuj[that of iron may be formed by expofing Tutlitn, 
 a folution of green fulphat to the air, or by treating it 'f'"'- '''^. 
 with nitric acid. It was formerly called mother ivater of 
 vitriol. 641 
 
 Little is known of its properties, except that it isRedfiiliiliat 
 deliquefcent, incryftallizable, and foluble in alcohol. «iiron. 
 It was firft accurately examined by Mr Proult. 
 The green fulphat of iron generally contains fome of 
 it, which may be feparated by means of alcohol. 
 
 It is alone capable of forming Pruflian bli;t with the 
 Pruffic acid, and of ftriking a black colour with the 
 gallic acid J. t See 
 
 We have obferved, that when it is diluted with w^-Vroufl's p,i. 
 ter, and an excefs of fulphuric acid is poured iji 
 again flowly converted into green iulphat. 
 
 13. Sulphat of zinc. — This fait, according to the 64) 
 beft accounts, was difcovered at Rammelfberg in Ger-Sulphat of 
 many, about the middle of the 16th century. Many^'"'* 
 Z z 2 afcribe 
 
 u isf , „ 
 "I, 
 
 Nuhul. 
 435- 
 
 (u) jfargotiia, or, as the French chemifts call it, xirconia, has been difcovered in great abundance in France by 
 Morveau, who found that the hyacinths of Expailly contained more than half their weight of it. From Vau- 
 quelin's analyfis they appear to be compofed of 
 
 3 2 parts of filica, ' 
 
 64 jargonia, 
 
 2 oxide of iron. 
 
 Jargonia has been examined with great care by thefe two philofophers, the experiments of Klaproth have 
 been confirmed, and feveral new properties of it have been difcovered. Perhaps a more detailed account than 
 we have hitherto given of this new earth may not be unacceptable to our readers. 
 
 Jargonia is a white powder, its fpecific gravity is confiderable, it has a feel refembling that of filica, it has no 
 tafte, and is infoluble in water. When feparated from its folutions by pure alkalies, it retains, when expofed to 
 the air to dry, a pretty confiderable quantity of water, which renders it tranfparent, and gives it a refemblance 
 to gum arabic both in its colour and frafture. 
 
 When expofed to the heat of the blow-pipe it does not melt ; but Vauquelin melted it by expofing it furround- 
 ed with charcoal in a porcelain crucible to an intenfe heat for an hour and a half. Its fpecific gravity was then 
 4,35, its colour was grey, and its hardnefs fuch that it was capable of fcratching glafs. It melts with borax, and 
 forms a tranfparent and colourlefs glafs ; but pholphat of foda and the fixed alkalies do not attack it. 
 
 It is infoluble in the fixed alkalies, has very little affinity for carbonic acid, and is precipitated from its folu- 
 tions together with iron by the Pruffic alkali. 
 
 Its affinities, as far as they have been afcertained by Vauquelin, are as follows : 
 
 Vegetable acids, order unknown, 
 Sulphuric acid. 
 Muriatic, 
 Nitric. 
 See upon this fubjeft the Memoirs of Morveau and Vauquelin, j4nn, de Chim. xxi. 72. and xxii. 179. 
 (t) Thefe curious falts form the fubject of the next chapter. 
 
 (u) Perhaps the quantity of oxide is fomewhat over-rated here ; for before it was examined by Mr Kirwan, it' 
 had afTumed a red colour : it muft therefore have been converted into the brown or red oxide by attracting oxy- 
 gen from the atmofphere.
 
 CHEMISTRY. 
 
 mann's HiJ}. 
 of Inven~ 
 thns, art. 
 
 + Btrgman, 
 
 t UiJ. 
 
 644 
 Sulphat of 
 maiiganefe. 
 
 § SchieU, 
 
 645 
 Sulphat of 
 nickel. 
 
 ^ "Bergmanj 
 ii. 16S. 
 646 
 Sulphat of 
 cobalt. 
 
 647 
 Sulphat of 
 lead. 
 
 * Monntt. 
 
 648 
 Sulphat cf 
 copper. 
 
 afcribe the invention to Julius Duke of Brunfwick. 
 Hciikel and Neumann were the firfl chemitb who 
 proved that it contained zinc ; and Brandt firft. afcer- 
 tained its compofition completely *. It is generally 
 formed for commercial purpofes from fulphurct of zinc 
 or blir.de, as it is called. This fait is called alfo ivhhe 
 vitriol. 
 
 It is of a white colour, and its cryftals are rhomboi- 
 dal prifms, terminated by quadrangular pyramids : there 
 is generally a flight defeA in two of the oppofite an- 
 gles of the prifm, which produces a quadrangular fec- 
 tion f. Its fpecific gravity is 2,000. 
 
 It has a (harp ftyptic tafte. 
 
 It is foluble in 2,28 parts of water at the tempera- 
 ture of 60" ; but in a much fmaller quantity of boiling 
 water J. 
 
 It is compofed, according to Bergman, of 40 (v) 
 parts of acid, 20 of oxide, and 40 of water : Kirwan 
 fuppofes that it is compofed of iz parts of acid, 26,4 
 of zinc, 20 of oxide, 4 T, 6 of water (wj. 
 
 According to Bergman, this fait is not altered in the 
 air; others affirm that it efflorefces. This, no doubt, 
 depends upon the place where it is kept. 
 
 Heat decompofes this fait. 
 
 14. Sulphat of manganefe. — This fait was firft ob- 
 tained by Scheele (x) ; It is compofed of fulphuric 
 acid and white oxide of manganefe. 
 
 Its cryftals are oblique parallelepipeds ; they are of 
 a white colour, and very bitter J. 
 
 Thefe cryftals are decompofed by a ftrong red heat, 
 and the fulphuric is converted into fulphurous acid by 
 the oxide attrafting its oxygen, and being changed 
 into black oxide ||. 
 
 15. Sulphat of nickel This fait, which is compo- 
 fed of fulphuric acid and oxide of nickel, was firft de- 
 fcrib«d by Bergman. Its cryftals are in the form of 
 decahedrons, compofed of two quadrangular truncated 
 pyramids ; they are of a green colour ^. 
 
 I 6. Sulphat of cobalt. — This fait was firft mentioned 
 by Mr Brandt. Its cryftals are of a reddifli colour; 
 but if any nickel be prefent, they are green. 
 
 17. Sulphat of lead. — This fait has been long known: 
 it is compofed of fulphuric acid and white uxide of lead. 
 The cryftals are white, fmall, and moft commonly needle- 
 fhaped: according to Sage, they are tetrahedral prilms. 
 
 It is foluble in 18 parts of water. 
 Heat decompofes it. — It is very cauftic. 
 
 18. Sulphat of tin. — Nothing is known concerning 
 this fait, except that it cryftallizes in fine needles inter- 
 laced with one another*. 
 
 19. Sulphat of copper. — This fait appears to have 
 been known to the ancients. It is generally obtained 
 by evaporating thofe waters which naturally contain it. 
 It is called ullo l/ue •vitriol. 
 
 Its cryftals are of a deep blue colour; they are in 
 the form of oblong rhomboids. Its fpecific, gravity is 
 2,230. 
 
 It has a very ftrong ftyptic tafte ; and indeed is em- 
 ployed as a cauftic. 
 
 It is foluble in four parts of water at the tempera- 
 
 I S T R Y. Part lir» 
 
 ture of 60° ; but in a much fmaller quantity of boiling Sulphats. 
 water *. ' " ' 
 
 It is coinpofed, according to Bergman, of 46 parts "S'"'"' 
 of acid, 26 of oxide of copper, and 28 of water. Kir. 
 wan fuppofes it to contain 27,68 of acid, 35 of oxide, 
 and ■?7,32 of water f. t Mlntr.i'u 
 
 When expofed to the air, it efflorefces, and is cover. ^J- 
 ed with a yellowifti grey powder. 
 
 It requires a very ftrong heat to decompofe it. 
 
 It has the property of communicating a green co- 
 lour to flame. 
 
 It is ufed in the preparation of feveral paints, and for 
 a variety of other purpofes. 
 
 It is decompofed by compound affinity by acetite 
 of lead. • , 
 
 20. Sulphat of bifmuth. — Little is known of this <;y| [,', ^j 
 fait, except that it is with difficulty cryftallized, and is bifmuth, 
 very dehquefcent. ^.^ 
 
 2 1. Sulphat of antimony. — This fait does not cry- Antimony, 
 ftallize. It is eafily decompofed by heat. , 
 
 22. Sulphat of arfenic. — This fait is fcarcely known. Arfenic 
 It does not appear to be cryftallizable. It is decom- 
 pofed by water. ^^ 
 
 23. White fulphat of mercury. — This fait may be wiiite fuU 
 formed by boiling together two parts of mercury andphatof 
 three of concentrated fulphuric acid, and rtop')ing the "'ercury. 
 procefs whenever the mercury is converted into a white 
 
 mafs. This mafs, in order to remove the excefs of 
 acid, is to be w^died repeatedly with fmall portions of 
 water, till it ceafes to redden turnfole. The fulphat of 
 mercury, thus obtained, is very white. Its cryftals ave 
 either fmall plates or prifms. Its tafte is not very cauf- 
 tic. It is foluble in 500 parts of water at the tempe- 
 rature of 55°, and in 287 parts of boiling water. It 
 is compofed of 8 ^ parts of white oxide of mercury, 12 
 of fulphuric acid, and 5 of water J. It is not altered { Fswwoj. 
 by expofure to the air. Heat decompofes ft. ■^'"'- <^i 
 
 This fulphat is capable of combining with a new ''• 
 
 portion of acid : It was in that ftate before it was wafti- 
 ed with water. This fait, which may be called acidu- 
 lous white fulphat of mercury, has a very cauftic tafte, and 
 is corrofive. It reddens vegetable blues. It is foluble 
 in 1 57 parts of water at the temperature of 55% and in 
 33 parts of boiling water {. _ j Fourcroy, 
 
 24. Yellow fulphat of mercury. — This fait may be/'foV. 
 obtained by continuing to boil the preceding mixture of ^ii 
 mercury and fulphuric acid till the mercury aftumes a yel- 1" °^ 
 low colour. It appears to be compofed of yellow oxide merci 
 of mercury and a fmall portion of fulphuric acid. It is 
 foluble in 2000 parts of water at the temperature of 
 
 51;°, and in 600 parts of boiling water. The folution 
 
 is colourlefs. It was formerly called turliih mineral ]| . || Fourcrty, 
 
 25. Sulphat of ammonia and mercury. — This triplci'V. 
 
 fait may be formed by pouring ammonia into a folution , ^|^4 ^ 
 of fulphat of mercury. If only a fmall quantity of am- jj^P^^^^;"' 
 monia be ufed, a copious blackilh precipitate takes j^d mer-. 
 place, part of which is converted into running mercury cury. 
 Ijy expofure to light ; and confequently is black oxide 
 of mercury ; the remaining part is the triple fait. If a 
 large quantity of ammonia be ufed, only the black oxide 
 
 is 
 
 :of 
 - mercury. 
 
 (v) There is evidently fome miftake in this ftatement ; it does not correfpond with what he fays elfewhere. 
 
 (w) Mineralogy, ii. 24. We do not underftand this ftatement. 
 
 (x) Weftfield, indeed, obtained it ; but he miftook it for fulphat of magnefia.
 
 part in. 
 
 CHEMISTRY. 
 
 ^Strgir. 
 
 656 
 Sulphat of 
 urauium. 
 
 6^7 
 Titanium, 
 
 Sulphats. I's precipitated ; for the triple fait 13 rendered much 
 
 •■"■"v^""^ more foliible by an exccfs of ammonia. As this exeefs 
 evaporates, the fait cryllallizes. The cry Hals are poly- 
 gons, very brilliant and hard. It has a Iharp, aultcre, 
 metallic tafte. It has no peculiar odour. It is fcarcely 
 foluble, except with excels of ammonia. It is compo- 
 fed, according to Fourcroy's analyiis, of 18 parts of 
 fulphuric acid, 33 of ammonia, and 39 of oxide of mer- 
 cury. Heat decompjfes it. The produfts obtained by 
 dillilling it are, a little ammonia, azotic gas, a little 
 pure mercury, fome fulphite of ammonia ; and there re- 
 
 • Fcunro); mains yellow fulphat of mercury *. 
 
 iiU. This triple f It may- be formed alfo by pouring am- 
 
 monia upon acidulous lulphat of mercury, or on yellow 
 
 \ liiJ. fulphat of mercury f. 
 
 *?5 26. Snlphat of fdver. — This f.ilt Is formed by pour- 
 
 Siilj hat of ju^ fulphuric acid on o^ide of lilver. Its crylLals are 
 fmall needles. It mtlts when expofed to a llrong heat, 
 but does not fublime. 
 
 It is dccompofed by niuriat of lead J. 
 
 27. Sulphat of gold. — This fait is unknown. 
 
 28. Sulphat of platinum. — Unknown. 
 20. Sulphat of tungllen. — Probably no fucli combi- 
 nation is poflible. 
 
 30. Sulphat of molybdenum — Probably impoffible. 
 
 31. Sulphat of uranium This fait was firll formed 
 
 by Mr Klaproth. He formed it by pouring fulphuric 
 acid on the oxide of uranium. Nothing farther is 
 known of it, except that its cryftals are fmall, and of a 
 ytUow colour. 
 
 32. Sulphat of titanium. — This fait was firfl formed 
 by MrM'Gregor. It does not appear, from Klaproth's 
 
 - „ experiments, to be crylfallizable. 
 
 Tellurium. 33- Sulphat of tellurium. — When one part of tellu- 
 rium is mixed cold in a well-ftopped vcffelwith a hun- 
 dred parts of concentrated fulphuric acid, the latter 
 gradually affumes a beautiful crimfon red colour : when 
 a fmall quantity of water is added, drop by drop, the 
 colour difappears, and the metal is precipitated in the 
 form of black flakes. The folution is deftroyed by 
 heat, the colour difappears, and the metal feparates in 
 the ftate of a white oxide. When fulphuric acid is di- 
 luted with two or three parts of water, and a fmall 
 quantity of nitric acid is added, it diffolves a confider- 
 able quantity of tellurium. The folution is tranfparent 
 and colourlcfs, and is not decompofed by the addition 
 
 5 Xlafirotl, of a larger quantity of water j . 
 
 Mag.i.%0. Sect. 11. Of Sulphites. 
 
 Salts compofed of fulphurous acid united refpec- 
 
 tively with alkalies, earths, or oxides, are calledyii^^i/fj-. 
 
 Thofe hitherto examined are the following : 
 
 Sulphite of '■ Sulphite of potafs. — This fait was firlf formed by 
 
 jutafs. Stahl ; but was firft accurately defcribed by BerthoUet, 
 
 Fourcroy, and Vauquelin. 
 
 It may be formed by pafTmg fulphurous acid into a 
 faturated folution of carbonat of potafs till all effervef- 
 cence ceafes. The folution becomes hot, and cryflal- 
 I Fourcroy, lizes by cooling ||. 
 
 nd Vauque- jjg cryftals are white and tranfparent ; their figure 
 Vj loun '^^' °^ rhomboidal plates. Its cryftallization often pre- 
 . 317. fents fmall needles diverging from a common centre *I. 
 Ibid. Its tafte is penetrating and fulphurous. At the 
 
 common temperature of the atmofphere, it is foluble in 
 its own weight of water, but much more foluble in boil- 
 ing wnter. 
 
 3^5 
 
 When expofed to the air, it efflorefces, becomes Siilphiies. 
 opaque and hard, and is gradually convened \nio fulphat ^— — v— -^ 
 of potafs by abforbing oxygen. 
 
 When expofed to a fudden heat. It decrepitates, lofcs 
 Its water : at a red heat fome fulphurous vapours are 
 emitted ; at lull a portion of fidphur feparates, and the 
 refiduum is fulphat of potafs, with a flieht excefs of al- 
 kali. 
 
 Nitric and oxy muriatic acids convert it into fulphat 
 of potafs by imparting oxygen. 
 
 It dti.ompofes the ojtides of gold, filver, mercury, 
 the red oxide of lead, the black oxide of manganefe, and 
 the brown oxide of iron. When the green oxide of iron 
 and the white oxide of iron are boiled with it in water, 
 and an acid added, a precipitate takes place of thefe 
 bodies united to fome fulphur, and the filt is convert- 
 ed into a fulphat : at the fame time fulphurated hydro- 
 gen gas is emitted. 
 
 By compound affinity it is decompofed by 
 
 All falls with bafe of foda, except the borat and car- 
 bonat ; 
 
 All metallic falts except carbonats ; 
 
 All neutral falts whofe acid has a ftronger affun'ty 
 for potafs than fulphurous acid has*. » 7h\i. 
 
 2. Kulphite of foda. — This fait was firft accurately '>t>° 
 defcribed by Fourcroy and Vauquelin. Sulphite of 
 
 It is white and pcrfedly tranfparent. Its cryftals '^°''*' 
 are four-fided prifms, with two very broad fides and two 
 very narrow ones, terminated by dehedntl pyramids. 
 
 Its tafte is cool and fulphurous. 
 
 It is^ foluble in four times its weight of cold water, 
 but it is more foluble in hot water. 
 
 It is compofed of iS,8 parts of foda, 31,2 of acid, 
 and 50 of water. 
 
 By expofure to air, it e/Horefces, and is flowly con- 
 verted into a fulphat. 
 
 When expofed to heat, it undergoes the watery fu- 
 fion, and afterwards exhibits precifely the fame pheno- 
 mena as the fulphlte of potafs. 
 
 Metallic oxides and falts affeft it precifely as they do 
 fulphlte of potafs. 
 
 It is decompofed by compound affinity by carbonat 
 of potafs, and the other falts which decoinpofe fulphlte 
 of potafs f . j^.j 
 
 3. Sulphite of ammonia. — This fait was firft defcri- aVr 
 bed by Fourcroy and Vauquelin J. sulphite of 
 
 It cryft.dllzes in fix-fided prifms terminated by fix- »n'">onia- 
 fided pyramids. t Fo^rc.oy 
 
 T. 1 n ■ 1 , . ... and ^ui/jirf. 
 
 Its tafte IS cool and penetrating like that of the/;„ NUM. 
 other ammoniacal falts, but it leaves a fulphurous im-/»"'-' J'^rn, 
 prcffion in the mouth. i- 3'7- 
 
 It is foluble in Its own weight of cold water. Its 
 folubllity is increafed by heat. 
 
 It is compofed of 29,07 parts of ammonia, 60,06 of 
 acid, and 10,87 of water. 
 
 When expofed to the air, it attrafts moifture, and is 
 foon converted into a fulphat. 
 
 Heat volatilizes it without decompofition. 
 
 Its habitudes with metallic oxides and falts are nearly 
 the fame with thofe of the above defcribed fulphltes, <u^i*, 
 only it is capable of forming with feveral of them triple bar?u.* " 
 falts §. _ ^ diJ." 
 
 4. Sulphite of barytes.— This fait was firft defcribed " ^"'^ * 
 by BerthoUet II . ctim.ii.c,j. 
 
 It is incryftallizable ; it has no perceptible tafte ; and K«Z. 
 and is pcrfedly infoluble ia water ^, /m. 
 
 It
 
 CHEMISTRY. 
 
 Part 111. 
 
 * M.W. 
 <> ? 
 S'llphite of 
 lime. 
 
 f /inn (/c 
 Cij'ff:- il'iJ- 
 
 tit. 
 
 5 Ibid. 
 664 
 
 Snlphi'e pf 
 magneGa. 
 
 II Fourcrey 
 and Vau(iue- 
 tin. 
 
 665 
 Sulphite of 
 alumina. 
 
 ^ Fourcroy 
 and yauqut- 
 lin. 
 
 666 
 Sul|'hi(e rf 
 iron 
 
 * j4nn. de 
 dim. ii. j 8. 
 
 667 
 Kitre. 
 
 It is compofeJ of 59 parts of barytcs, 39 parts of 
 acid, and ?. of water. 
 
 It dues nut t;ilily Chanel' into a fiilpliat by expofure 
 to air ; but htat produc^:^^ iliis cffcft *- 
 
 5. Sulphite of lime. — This fait was firll defcribed by 
 IJertholltt f. 
 
 Jts cryllals are fix-fided prifms, terminated each by a 
 very long jiyramid;]:. 
 
 It has fcarcely any tafte ; however, when kept long 
 in the mouth, it communicates to the tongue a tafte 
 which is maniftftly iulphurous. 
 
 It is very fparingly foluble in water, except with ex- 
 cefs of acid. 
 
 It is compofed of 47 parts of lime, 48 of fulphurous 
 acid, and 5 of water. 
 
 By contadt of air it is converted into a fulphat, but 
 verv flowly. 
 
 Heat converts it into a fulphat by depriving it of a 
 portion of fulphur. 
 
 It is decompofed by compound affinity by 
 
 Carbonates of alkalies, Fluats of alkah'es, 
 
 Pliofphats of alkalies, Moft metallic falts §. _ 
 
 6. Sulphite of magnefia. — This fait was firft defcri- 
 bed by Fourcroy and Vauquelin. 
 
 Its crvllals are white and tranfparent, and in the 
 form of deprefled tetrahedrons. 
 
 Its tatte is mild and earthy at firft, and afterwards 
 fulphurous. 
 
 It is fparingly foluble in water, except when there is 
 an excefs of acid. 
 
 It is compofed of 16 parts of magnefia, 39 of acid, 
 and 45 of water. 
 
 It becomes opaque when expofed to the air ; is very 
 flowly converted into a fulphat. 
 
 By expofure to heat, it foftens, fwells up, and be- 
 comes duftile like gum ; a ftrong heat decompofes it 
 altogether. 
 
 It is decompofed by 
 
 Alkaline falts. 
 
 Earthy falts, except thofe of alumina ||. 
 
 7. Sulphite of alumina — Firft formed by Berthollet. 
 It does not cryftallize, but is converted into a foft 
 
 duftile mafs. It is not foluble in water, but becomes 
 abundantly fo when there is an excefs of acid. 
 
 It is compofed of 44 parts of alumina, 32 of acid, 
 and 24 of water. 
 
 Heat decompofes it ^. 
 ■ 8. Sulphite of iron. - It was firft formed by Berthol- 
 let. 
 
 Its cryftals are white, and have but very little of the 
 ftyptic tafte of iron falts *. 
 
 Berthollet alfo formed the fulphites of zinc and tin, 
 but he has not defcribed them. 
 
 Sect. III. 0/ Nitrats. 
 
 Those falts, in the compofition of which the nitric 
 acid forms one ingredient, are called nitrats. 
 
 I . Nitrat of potafs, nitre, or faltpetre. — As this fait 
 is produced naturally in confiderable quantities, parti- 
 cularly in Egypt, it is highly probable that the ancients 
 were acquainted with it ; but fcarcely any thing cer- 
 tain can be collefted from their writings. If Pliny 
 mentions it at all, he confounds it with foda, which was 
 known by the names of nitron and nitrum. It is cer- 
 tain, however, that it has been known in the eaft from 
 
 time immemorial. Roger Bacon mcnliuns this fait in Niti-.m. 
 the I ^th century under the name of iiitrf. •' ' 
 
 It-cryllalli/.cs in flender oblong hexagonal prifms, of- 
 ten ftriated, terminated by hexagonal pyramids oblique- 
 ly truncated. Its fpecific gravity is 1,920. 
 Its t.<fte is fliarp, biiterifh, and cooling. 
 It is foluble in levcn times its weight of water at the 
 temperature of 60^, and in nearly its own weight of 
 boiling water '. « B^r^ma,:. 
 
 Accoiding to Bergman, it is compofed of 3 I parts 
 of acid, 61 of potafs, and 8 of water ; but this propor- 
 tion of acid is undoubtedly too fmall. According to 
 Mr Kirwan, it Is compofed of 41,2 of acid, 46,15 of 
 alkali, and 12,63 of water -j-. \ Mineral, 
 
 It is not altered by expofure to the air. "• *?• 
 
 When expofed to a ttrong heat, it melts ; and con- 
 geals by cooling into an opaque mafs, which has been 
 called mineral cryjlal. If the heat be continued, the 
 acid is gradually decompofed and driven off. When 
 the folution of nitre is expofed to a boiling heat, part of 
 the fait is evaporated along with the water, as Wallerius, 
 ICirwan, and Lavoifier, obferved fucctffively. When 
 nitre is expofed to heat along with many combuftible 
 fublla'~.ces, its acid is decompofed ; the combuftible 
 feizes the oxygen, and at the fame time a lively white 
 flame appears, attended with a decrepitation : this is 
 called the detonation of nitre. 
 
 Nitre mixed with charcoal and fulphur in proper 
 proportions forms gunpouu/tr. 
 
 Nitre is decompofed by compound affinities by 
 
 Acetite of barytes. 668 
 
 No phenomenon has excited the attention of chemi-Rep™duc. 
 cal philofophers more than the continual rcproduftion ''"" ""'" 
 of nitre in certain places after it had been cxtrafted from 
 them. Prodigious quantities of this fait are neceffary 
 for the purpofes of war ; and as Nature has not laid up 
 great magazines of it as (he has of fome other falts, this 
 annual reproduAion is the only fource from which it can 
 be procured. It became, therefore, of the utmoft con- 
 fequence, if poflible, to difcover the means which Nature 
 employed in forming it, in order to enable us to imitate 
 her proceffes by ait, or at leaft to accelerate and lacilitnte 
 them at pleafure. Numerous attempts accordingly have 
 been made to explain and to imitate thefe proceffes. 
 
 Stahl, fetting out on the principle that there is 
 only one acid in nature, fuppofed that nitric acid is 
 merely fulphuric acid combined with phlogifton ; and 
 that this combination is produced by putrefaftion : he 
 affirmed accordingly, that nitre is compofed by uniting 
 together potafs, fulphuric acid, and phlogifton. But 
 this opinion, which was merely fupported by very far- 
 fetched analogies, could not ftand the teft of a rigorous 
 examination. 
 
 Lemery the Younger accordingly advanced another ; 
 affirming, that all the nitre obtained exifts previoufly 
 in animals and vegetables, and that it is formed in thele 
 fubftances by the proccfles of vegetation and animali- 
 zation. But it was foon difcovered that nitre exiibs, 
 and is aAually formed, in many places where no animal 
 nor vegetable fubftance has been decompofed ; and con- 
 fequently this theory was as untenable as the former. 
 So far indeed is it from being true that nitre is formed 
 alone by thefe proceffes, that the quantity of nitre in 
 plants has been found to depend entirely on the ioil in 
 which they grow J. t Beuilh 
 
 ' ^ At
 
 Partlir. 
 
 C H E M 
 
 Nitrats. 
 
 At lail by the numerous experiments of fcveral French 
 ""pliilofophcrs, particularly by tliofe of Thouvenel, it was 
 tlifcovered that nothing elfe is neccflary for the pio- 
 <luftion of nitre but a bafis of lime, heat, and an open 
 but not too free communication with dry atmofpheric 
 air. When tliefe circumllances combine, the acid is firit 
 formed, and afterwards the alkali makes its appearance. 
 How the air furnilhes materials for this produttion is 
 eafily explained, now that the component parts of the 
 nitric acid are known to be oxygen and azot. But 
 how lime contributes to their union it is not fo eafy to 
 fee. It is a difpofmg affinity, which, like moft others 
 referred to that lingular clafs, our prefent knowledge of 
 the nature of affinity does not enable us to explain. 
 The appearance of the potafs is equally extraordinary. 
 If any thing can give countenance to the hypothelis, 
 that potafs is compofed of lime and azot, it is this lin- 
 gular faft. 
 
 2. NItrat of foda. This fait was called formerly cu- 
 bic nitre. 
 
 It forms rhomboidal cryftals. Its fpecific gravity is 
 1,870. 
 
 It has a cool (harp tafte, and is fomewhat more bit- 
 ter tlian nitre. 
 
 It is foluble in about three parts of water at the tem- 
 perature of 6a', and is fcarcely more foluble in boiling 
 water. 
 
 It is compofed, according to Bergman, of 43 parts 
 of acid, 33 of foda, and 25 of water. From an expe- 
 riment formerly delcribed, Mr Kirwan concludes, that 
 it contains 57,65 of acid, and 42,35 of alkali; but per- 
 haps the proportion of acid may be fomewhat over-rated, 
 as no direft proof has been brought that the fait con- 
 tains no water. 
 
 When expofed to the air it rather attracts moifture. 
 Its phenomena in the lire are the fame with thofe of 
 nitre, only it does not melt fo eafily. 
 
 It is decompofed by compound affinity by the fol- 
 lowing falts : 
 
 Sulphat of barytes, 
 
 potafs, 
 
 alumina, 
 
 Muriat of barytes, 
 
 potafs, 
 
 lime. 
 
 Muriat of ammonia, 
 Acetite of barytes, 
 
 potafs, 
 
 Carbonat of barytes, 
 potafs. 
 
 3. Nitrat of ammonia. This fait cryftallizes with 
 difficulty into regular needles. It was formerly called 
 nilrum fnnivolatile, and tiitrum Jlummans. 
 
 It has a fharp, acrid, fomewhat urinous tafte. 
 
 It is foluble in about half its weight of boiling wa- 
 ter. 
 
 It is compofed of 58 parts of acid, about 26 of al- 
 ^ Kirwan. kali, and 16 of water*. 
 
 When expofed to the air it deliquefces. 
 
 When expofed to heat, it firft undergoes the watery 
 fufion, afterwards detonates, and is completely decom- 
 pofed. Berthollet has (hewn, that this phenomenon is 
 owing to the hydrogen of the alkali entering into com- 
 bination with the oxygen of the acid, and forming wa- 
 ter, while the acid flies off in a gafeous form. 
 
 By compound affinity it is decompofed by the follow- 
 ing fubftances : 
 
 Sulphat of barytes, Acetite of barytes, 
 
 — — — potafs, — — potafs, 
 
 — — alumina, foda, 
 
 I S T R Y. 
 
 Acetite of lime 
 
 magnefia, 
 
 alumina. 
 
 Muriat of barytes, 
 potafs, 
 
 fo<la. 
 
 Muriat of lime, 
 
 magnefia, 
 
 alumina, 
 
 Nitrat". 
 
 671 
 
 Carbonat of barytes, 
 
 4. Nitrat of barytes. This fait may be formed into Nitrat of 
 hexagonal cryftals, but it requires great addrcfs to pro-''^')'"'- 
 duce them. 
 
 It attracts moifture from the atmofphcre. 
 Heat decompoics it, and leaves pure barytes. The 
 decompofition of this fait by heat is the r->>oft convenient 
 method of procuring ])ure barytes yet known. It was 
 firft propofed by Mr Vauciuelln. 
 
 By compound affinity it is decompofed by 
 Alkaline carbonats, 
 Oxalat of ammonia *. * Sergmon, 
 
 5. Nitrat of lime. This fait forms by cryftalllzation ^^^ *^' 
 fix-fided prifms, terminated by dehedral pyramids, bat|,,J|j'' 
 more commonly fmall regular oflahedral needles. 
 
 It has a ftiarp bitterifli tafte. 
 
 It is foluble in two parts of cold water, and in its 
 own weight of boiling water. 
 
 Boiliiig alcohol diftolves its own weight of it f . t ?"■.?»"'•." 
 
 According to Bergman, it is compofed of 43 parts 
 of acid, 32 of lime, and 25 of water. Kirwan has 
 found, that 100 parts of lime require for faturation 1S0 
 parts of acid f. t Min,r.\l 
 
 Nitrat of lime deliquefces when expofed to the air. ir- 
 Heat decompofes it like all other nitrats. 
 By compound affinity it is decompofed by 
 Sulphat of barytes, Acetite of potafs, 
 
 Carbonat of barytes, 
 
 potafs, 
 
 foda. 
 
 potafs, 
 
 — — foda, 
 
 ■ ammonia, 
 
 alimiina, 
 
 Muriat of barytes, 
 
 potafs, 
 
 ammonia, 
 
 alumina, 
 
 magnefia. 
 
 Acetite of barytes, Tungftat of ammortia (). ^ SchrtU. 
 
 6. Nitrat of ftrontites. This fait, firft formed by Dr' 67? 
 Hope, cryftallizcs readily, but the cryftals are very irre- '^""'. '^^ 
 gular in their (liape : fometimes they are hexagonal '^"""■'^'° 
 truncated pyramids; fometimes oftahedrons, confiding 
 
 of two four-fided pyramids united at their bafes. 
 
 It IS foluble in its own weight of water, at the tem- 
 perature of 60", and in little more than half its weight 
 of boiling water. It has a ftrong pungent tafte. 
 
 In a dry air it elHorefces, but in a moift air it deli- 
 quefces. 
 
 It deflagrates on iiot coals. Subjeded to heat in a 
 crucible, it decrepitates gently, and then inelts. In a 
 red heat it boils, and the acid is diffipated. If a com- 
 bullible fubftatiee be at this time brought Into contact 
 with it, a deflagration with a very vivid red flame is 
 produced II . || }i,p,^ 
 
 7. Nitrat of magnefia. The <;omppCtion of this i-d\tTran/. ILJin 
 was firll afcertained by Dr Black. '*• '*■ 
 
 Its cryftals are quadrangular prifms. It has a very xjj„j*pf 
 bitter tafte. It is very foluble in water. Alcohol dif-niifri.ffia. 
 folves ^th of its own weight of it <[[. 1[ V.^gmnn, 
 
 One hundred parts of magnefia require 255 of nitric "■''''■ 
 acid for faturation *. ^ Kirtv-in 
 
 It deliquefces in the air, according to Bergman; bi\t 
 Dijonval affirms, that he has procured it in cryftals 
 which rather eiflorefce. 
 
 It
 
 368 
 
 CHEMISTRY. 
 
 Part nr. 
 
 Nitrat«. 
 
 It is decompofeJ by heat. 
 
 By campouiid affinity it is Jecompofed by 
 
 675 
 Nitrat of 
 am.n. rii 
 
 Sulpliat of barytes, 
 
 potafs, 
 
 foda, 
 
 —— ammonia, 
 
 alumina, 
 
 Muriat of barytes, 
 
 potafs, 
 
 foda. 
 
 Muriat of lime, 
 Acetite of barytes, 
 
 potafs, 
 
 — — foda, 
 
 - — lime, 
 
 Carbonat of barytes, 
 
 potafs, 
 
 ^-^ lime. 
 
 Its folution is exceedingly cauftic. Wlien placed on Nitrau. 
 burning coals it melts and detonates as it dries. It k * 
 can fcircely be dried without being in fome raeafure de- 
 compofed. 
 
 Chim. iv. 
 
 676 
 Kitiat of 
 alumina. 
 
 ft77 
 Nitra' of 
 jargouia. 
 
 8. Nitrat of rmmonia and magnefia. This triple fait 
 was difcovercd by Mr Fourcroy. Into a faturated lo- 
 
 neCa""^" '"'^'°" '^^ nitrat of magnefia, containing 73 grains of 
 magnefia, he poured ammonia as long as any precipi- 
 tate could be obtained. Twenty-one grains of magne- 
 fia were precipitated, i;2 grains remained combined with 
 the acid and the ammonia. He found that 52 grains 
 of magnefia produced, when faturated with nitric acid, 
 288 grains of nitrat ; and that the quantity of nitric 
 acid neceffiry to faturate 21 grains of magnefia, when 
 faturated with ammonia, produced 84 grains of nitrat 
 of ammonia. He concludes, therefore, though the da- 
 ta are not quite fatisfaClory, that the triple fait is com- 
 pofed of 2S8 grains of nitrat of magnefia, and 84 of ni- 
 trat of ammonia *. 
 
 9. Nitrat of alumina. This feems to have been firll 
 attended to by Beaume. 
 
 Its crylldls are pyramidal. It has a very aftringent 
 tafte. It is foluble in water, and deliquefces in the 
 air. 
 
 10. Nitrat of jargonia. This fait may be eafily 
 formed by pouring nitric acid on newly precipitated 
 jargonia. 
 
 It alwa>s contains an excefs of acid. By evapora- 
 tion a yellowifli tranfparent matter is obtained, exceed- 
 ingly tenacious and vifcid, and which dries with diffi- 
 culty. It h:is an aftringent talle, and leaves on the 
 tongue a vifcid matter, owing to its being decompofed 
 by the faliva. It is only very fparinj^ly foluble in wa- 
 ter ; the greatell part remains under the form of gela- 
 tinous and tranfparent flakes. Like all the other falts 
 into which jargonia enters, it is decompofed by heat. It 
 is decompofed alfo by fulphuric acid, which occafions a 
 white precipitate, foluble in excefs of acid; by carbonat 
 of ammonia, which produces a precipitate foluble by 
 adding more carbonat ; and by an infufion of nut-galls 
 in alcohol, which produces a white precipitate, foluble 
 in an e::cefs of the infufion ; unlefs the jargonia con- 
 tains iron ; in which cafe the precipitate is a greyifh 
 blue, and part of it remains infoluble, giving the liquor 
 a blue colour. This liquor, mixed with carbonat of am- 
 monia, produces a matter purple by tranfmitted light, 
 but violet by refleded light. Gallic acid nifo precipi- 
 tates nitrat of jargonia qi a greyilh blue, but the co- 
 lour is not fo fine. Moll of the other vegetable acids 
 decompofe this fait, and form combinations infoluble in 
 water f. 
 till, Ann. dz J J _ Nitrat of iron. The green oxide of iron decom- 
 Cbim.xxn. ^^f^^^ j^^ ^j^gg j,ot combine with nitric acid. The 
 ^^678 brown oxide forms with it a red or brown folution, 
 Nitrat of which by evaporation may be reduced to a jelly, but 
 will not cryllallize. 
 
 12. Nitrat of zinc. The oxide of zinc combines 
 with nitric acid, and forms with it a fait which cryftal- 
 lizes in compreffed and ftriated tetrahedral prifms, termi- 
 nated by four-fided pyramids. 
 
 f Vauquf 
 
 iron. 
 
 679 
 
 Nitrat of 
 zinc. 
 
 It deliquefces in the air *. 
 
 * Foi 
 
 '•ircroy. 
 
 I 
 
 13. Nitrat of manganefe. This fait, compofed of ^So 
 oxide of manganefe and nitric acid, was firft examined "' °^ 
 by Scheele. Its cryftals are fmall and Ihining, of a ' *" 
 very bitter tafte, and foluble in water f . f ScbcrU on 
 
 14. Nitrat of cobalt. It is of a pale red colour, and-^'"l?'"'c/'> 
 
 cryftallizes in needles. It deliquefces when expofed to,,.''''' , 
 1 ■ TT 1 r ■ TTM • 1 1 • r Nitrat of 
 
 the air. rleat decompoles it. When nickel is prelentjcob^it 
 this fait affumes a green colour. gj 
 
 15. Nitrat of nickel. Its cryftals are of a green CO- of nickel, 
 lour, and in tiie form of rhomboida! cubes. They are 
 dehquefcent, and are gradually decompofed when expo- 
 fed to the air, the acid leaving theiTi|. t Bcnman 
 
 /6. Nitrat of lead. Nitric acid combines with theii. a6S. 
 white oxide of lead. The cryftals of this fait are of a "'^J 
 white colour ; their form an irregular oftagon, or ra- ' 
 
 ther truncated hexahedral pvramid. When expofed to 
 heat it decrepitates, and melts with a yellowiih flame. 
 By compound affinity it is decompofed by 
 
 Muriat of potafs, 
 
 foda, 
 
 ammonia, 
 
 Carbonat of foda §. { Btrgmm, 
 
 17. Nitrat of tin. Tin is converted into an acid hy j.^. ■* 
 nitric acid : it is not probable, therefore, that any per- ' 
 manent nitrat of tin can be formed. gg, 
 
 18. Nitrat of copper. This fait appears to have been Of coppe.-, 
 firft obtained by Macquer. 
 
 Its form, when properly cryftallized, is an oblong pa- 
 rallelogrcioi. It is of a fine blue colour. It is exceed- 
 ingly cauilic. It melts at 77^^11. | 
 
 It is deliquefccnt in a moift air, but in a dry place is 
 covered with a green efflorefcence. It is very loluble in 
 water. Heat decompoies it. 
 
 19. Nitrat of bifmuth. This fait cryftallizes in va- Of bilmuth, 
 rious forms. Fourcroy obtained it in flattened rhom- 
 boids. It. efflorefces in the air. Water deconipofes it. 
 
 It detonates in the fire. ,„ 
 
 20. Nitrat of antimony. Little is known concern- of i,,tin,o. 
 ing this fait, except that it is very deliquefcent, and isny, 
 decompofed by heat. ^gg 
 
 21. Nitrat of arfenic. With white oxide of arfenic Of arfenic, 
 nitric acid forms a fait which cryftallizes. It is very 
 deliquefcent. It does not detonate. , 
 
 22. Nitrat of mercury. This fait may be formed by Qf ^^^^^^ 
 diffolving mercury in nitric acid. It cryftallizes in the^j', 
 
 cold in regular flat 14-fided figures ; but their form dif- 
 fers according to the manner in which the cryftalliza- 
 tion has been performed. 
 It is foluble in water. 
 
 This fait is exceedingly cauftic. It detonates on 
 coals. When heated in a crucible it melts, and is de- 
 compofed. The oxide attracts oxygen from the acid, 
 which flies off in the form of nitrous gas, and red oxide 
 of mercury remains behind. 
 
 It is (lowly decompofed alfo in the air. It is decom- 
 pofed by compound affinity by 
 
 Sulphat of copper, and a great many other fulphats, 
 Phofphat of foda, 
 
 Borax. 6jo 
 
 23. Nitrat of ammonia and mercury. This triple Of ammo- 
 fait may be formed by pouring ammonia into a folution ma an<l 1 
 ' of ""^'"y* .1 
 
 Sa^t. 
 
 686
 
 Part lir. 
 
 CHEMISTRY. 
 
 37- 
 
 691 
 Nitiat of 
 filver, 
 
 692 
 Nitra' of 
 uranium, 
 
 Muri.us. of nit rat of mercury. If only enough of ammonia to 
 ^"■""v—"' laturate the acid be ufed, the triple hilt precipitates in 
 the form of a white powder ; but with an excels ot am- 
 monia it remains dilToived, and forms by evaporation 
 very bright polyhedral cryftals. 
 
 It has a very (harp talle. It is fohiblc in 1200 parts 
 of water at the temperature of 55'-'. Hot water fepa- 
 rates a little ammonia, which renders it llill more info- 
 lublc. It turns vegetable blues green. Muriatic acid 
 dilTolves it. 
 
 According to Fourcroy's analyfis, it is compofed of 
 68,20 parts of oxide of mercury, 16 of ammonia, and 
 15,80 of nitric acid and water. 
 
 When dillillcd it yields ammonia, azotic gas, oxygen 
 • Faurcroy, S^s, yellow oxide of mercury, and pure mercury *. 
 yinti.dr 24. Nitrat of filver. This fait may be formed by 
 
 CiiM.xiv. diiTolving iilver in nitric acid. 
 
 It forms flat tranfparent cryilals compofed of needles. 
 It is exceedingly cauftic. When melted it forms a grey 
 mafs called lapis infernalls, from its great corrofivencfs 
 
 It is very foluble in water. It is not altered by ex- 
 pofnre to the air. Light decompofes it. 
 By compound affinity it is decompofed by 
 The fulphats, 
 The muriats. 
 25. Nitrat of uranium. This fait was firll formed by 
 Klaproth. Its cryftals are hexagonal plates of a green- 
 ilh yellow colour. The largeft were jths of an inch iu 
 \ Khfroth, length and jth in breadth f . 
 
 JPi"7xx)iviI ^^' Nitrat of titanium. It is capable of cryftalli/.ing. 
 jjS 27. Nitrat ot tellurium. The filution of tellurium 
 
 69^ in nitric acid is tranfparent and colourlefs. When eon- 
 Timnium, centrated, it produces in time fmall white light crvllals 
 Tf'lurium '" ''^^ form of needles, which exhibit a dendritic ag- 
 } KUfr.,th, gregauon J. 
 
 ;_3^_ ^ Sect. IV. Of Nitrites. 
 
 The falts which the nitrous acid forms with alkalies, 
 earths, and metallic oxides, are denominated nitrites. 
 Very few of them have been examined ; we Ihall not 
 therefore attempt a defcription of them. 
 
 Sect. V. Of Muriats. 
 
 Salts into which the muriatic acid enters are called 
 muriats. 
 I _. ?' . I. Muriat of potafs. This fait was formerly called 
 
 I Muriat of ^ , ._ ,. „■ r 1 r c 1 • 1 I r r I 
 
 potafs. J^"'''J"S^ °'' "'i 7''i'<'y^" "J jylvius, and regenerated Jea Ja/t. 
 Its cryftals are cubes, but rather irregular. 
 It has a difagreeable bitter tafte. Its fpecitic gravi- 
 I ^ Kirwtin. ty is 1,8:^6 $. 
 
 It is luluble in three times its weight of water at the 
 temperature of 60°, and in double its weight of boiling 
 U Btrgman. water ||. 
 
 It is compofed, according to Bergman, of ^ i parts 
 of acid, 61 of potafs, and 8 of water. Kirwan has 
 found it to contain 36 of acid, 46 of alkali, and 1 8 of 
 V|!^''"«'j'"''\vater ^. 
 
 '"'"' It futfers little alteration from expofure to the air. 
 
 When expofed to heat, it firft decrepitates, then melts, 
 and at laft is volatilized, but without decompofition. 
 The following falts decompofe it by compound affinity: 
 
 569 
 
 2. Muriat of foda, common or fea fait. This fult Munau. 
 
 11. 30. 
 
 Sulphat of foda, 
 
 ■ ammonia, 
 
 alumina, 
 
 Nitrat of foda, 
 
 — — lime, 
 
 Suppt. VoL.I. Parti. 
 
 Nitrat of ammonia, 
 magnefia, 
 alumina, 
 lead. 
 
 has been known, and in common ufe, from the earliell jj" 
 ages. It is fometimcs called alfo/j/^'COT. Muriat of 
 
 Its cryftals are cubes, but they often affume other r,,da. 
 forms. Its fpecitic gravity is 2,1 10 *. * Kirwan. 
 
 Its tafte is univerially known, and is what is ftridtly 
 fpeaking denominatedyjj//. 
 
 It is foluble in 2i4 times its weight of water at the 
 temperature of 60", and in 214- its weight of boiling 
 water f. f Bergman. 
 
 According to Bergman, it is compofed of 52 parts 
 of acid, 42 ot alkali, and 6 of water. According to 
 the late experiments of Mr Kirwan, of 40 parts of 
 acid, 3^ of alkali, and 2 i; of water. 
 
 It is not affedted by expofure to the air. It ought to 
 be obferved, however, that the muriat of foda in com- 
 mon ufe contains, belides other impurities, a quantity 
 of muriat of magnefia, wiiich renders it dellquefcent. 
 
 When heated it decrepitates. Heat volatilizes, but 
 does not decompofe it. 
 
 The following falts decompofe it by compound affi- 
 nity : * Fucit, 
 Sulphat of ammonia, Nitrat of filver n, ,,?"' ■ 
 
 alumi-a, Aceffte ot baiytes, •xg. 
 
 potafs ■*, Pyrolignite of barytes ||,t Balltit, 
 
 iron f , lead ||, '*'''• "'• 
 
 Nitrat of ammonia, Carbonat of potafs \^a), i^'^ ^ 
 
 magnefia. Alum (i), 5 7j,-rcwM.' 
 
 alumina. Red oxide of lead (t). || Murveaa, 
 
 ■a.lf, • ■ 
 
 Ann de 
 . Cli -Ji.xx. 
 
 That the red oxide of lead decompofes this fait is a _ 
 
 well known faft, audit has been conlldered as contrary /,iB„^OTa„ 
 
 to the laws of affinity. Mr Halfenfratz endeavoureil 10(A) CrM, 
 
 account for it bv fuppofin? that the oxide is combined •^''■'•'•'' . 
 
 with carbonic acid, and that therefore it is a cafe of '" ""' 
 
 compound affinity. Mr Curaudau has proved that car-/^) ?,£„/,, 
 
 bonic acid, inftead of promoting, impedes the decom- 697 
 
 pofnion ; and that, in faft, carbonat of lead is inca- Hnw de- 
 
 pable of decompofincr muriat of fod?. He concludes, P'"^Pj '., 
 
 1 r 11^1 , 'by redoiide 
 
 therefore, that the phenomenon cannot be accounted gfi^ajj^ 
 
 for by the commonly received laws of affinity* We » Ann.dc 
 cannot, however, think that the phenomenon is io-^""-''^''' 
 unaccountable as Mr Curaudau fuppofes ; for muriatic'''' 
 acid is capable of decompofing tlie red oxide of lead, of 
 combining with part of its oxygen, and of being convert- 
 ed into oxy-murlatlc acid^ Now if oxy-muriatic and 
 nitromuriatic acids be merely the fame fubftance in a 
 diflFereiit form, as there is the ftrongeft reafon for fup- 
 pofing, the white oxide of lead has a ftronger affinity for 
 it than foda has, and ought therefore to decompofe it. , „ 
 
 3. Muriat of ammonia, or fal ammoniac. This fait ,viiiriat of 
 was known to the ancients, and was called by them ya/ ammonia. 
 ammoniac, becaufe it was found in great quantities near 
 the temple of Jupiter Amnion in Africa f. vu^'""^'- 
 
 It affumes the form of plumole cryftals. The indi- , « 1 
 vidual cryftals are long hexahedral pyramids. Its fpe- s.il Ammo- 
 cific gravity is 1,420 J. nu.;, Encyc. 
 
 It has an acrid, poignant, urinous tafte. t Kirwan. 
 
 It diflblves in about three times its weight of water 
 at the temperature of 60°, and in a much fmaller quan- 
 tity of boiling water. 
 
 It Is compofed, according to Kirwan, of 35 parts of 
 acid, 30 of alkali, and 45 of water ^. 5 KIrvian'i 
 
 In its common form (which is an opaque mafs) it is Mineral. 
 not affedted by the air, but its cryilals are liable to de-"' 34. 
 liquefce. 
 
 3 A Heat
 
 C H E M 
 
 Heat volatilizes without decompofing it. 
 The following falts decompofe it by compound affi- 
 nity 
 
 Sulphat of alumina, 
 Nitrat of foda, 
 
 lead, 
 
 Acetite cf barytes, 
 
 — — potafs, 
 
 — — ^— foda, 
 lime. 
 
 Acetite of magnefia, 
 
 alumina, 
 
 lead, 
 
 Carbonat of barytes, 
 
 potafs, 
 
 magnefia (y) 
 
 Stoi 
 
 &c Paitii 
 
 099 
 Muriat of 
 barytes. 
 
 When this fait is fublimed with gold leaf, there is 
 found in the neck of the retort an amethyil coloured 
 matter, bordering on purple, foluble in water, and form- 
 ing a purple folution. When filtered there remains be- 
 hind a purple powder. This fait feems from this to be 
 capable of oxidating gold *. 
 Crell't Ncru 4. Muriat of barytes. This fait was firft defcribed 
 Bifio-.^irics, fjy Bergman, but it iias been moft paiticularly attended 
 to by Dr Crawford. 
 
 It affords oblong fqnare cryftals. 
 It has an unpleafant a!lringe«t tafte. 
 It is not very foluble in water. It is foluble in al- 
 cohol. 
 
 It is not altered by expofure to the air, nor does heat 
 in all probability decompofe it. 
 
 Dr Crawford wrote a treatil'e on it in 1 790, in which 
 be recommended its ufe internally for fcrofulous com. 
 plaints. Care ought to be taken not to give it in too 
 large quantities, as, like the other compounds of bary- 
 tes, it is poifonous. 
 
 The following falts decompofe it by compound affi- 
 nity (z) : 
 
 Sulphat of foda 
 
 ammonia, 
 
 magnefia, 
 
 alumina, 
 
 Nitrat of lime, 
 
 ammonia, 
 
 magnefia, 
 
 alumina. 
 
 * Dr Ptar. 
 Jen. 
 
 7CO 
 JVIuriat of 
 ammonia 
 and bar^. 
 te«, 
 
 { Ann. di 
 Cbim. iv. 
 S. 
 701 
 
 Phofphat of lime f. 
 
 Nitrat of foda, 
 
 5. Muriat of amjnonia and barytes. This triple fait 
 was firft difcovered by Fourcroy. It may be formed 
 by pouring a carbonat of ammonia into a folution of 
 muriat of barytes. It is eafdy decompofed by heat, but 
 none of the alkalies nor their carbonats are capable of 
 altering it \. 
 
 6. Muriat of lime. This fait was formerly called 
 fixed ammoniac, becaufe it was commonly obtained by 
 
 Miiriat cf decompofiiig fal ammoniac by means of lime., 
 l"™^) Its cryftals are four fided ftriated prifms, term.inated 
 
 by a very {harp pyramid ; but it is not eafily cryital- 
 lized. 
 
 Its tafte is very bitter. 
 
 It is foluble in about i-'- parts of cold water, and in 
 Irfs than its own weight of boihng water. Alcohol 
 difloWcs its own weight of it. 
 
 According to Bergman, it is compofed of 31 parts 
 of acid, 44 of lime, and 25 of water. According to 
 Kirwan, loo parts of lime require for faluration 86 
 parts of muriatic acid.. 
 
 I S T R Y. Part HI. 
 
 It very fpecdily deliqnefces when expofcd to the air. Muriats. 
 By heat it melts into a very hard vitreform fub- "~"V ' '* 
 ftance. 
 
 The following falts decompofe it by compound affi- 
 nity ; 
 
 Carbonat of potafs, 
 — — — — — foda, 
 
 Sulphat of foda, 
 
 ammonia, 
 
 magnefia, 
 
 alumina, 
 
 Nitrat of foda, 
 
 — ammonia, 
 
 magnefia, 
 
 alum 
 
 ina. 
 
 Acetite of barytes, 
 
 potafs, 
 
 foda. 
 
 ammonia*, • Bergman. 
 ■ barytes, 
 • magnefia, 
 
 alumina, 
 
 701 
 
 This fait was firft formed Muriat of 
 Its cryftals are very long, {lender, hexa- Iri^ntites, 
 It has a peculiar, Iharp, penetrating 
 
 t %': 
 
 7. Muriat of ftrontites. 
 by Dr Hope, 
 gonal prifms. 
 tafte. 
 
 Three parts of thefe cryftals are foluble in two parts 
 of water at the temperature of 60°. Boiling water 
 diffolves any quantity of them whatever. 
 
 They contain 42 per cent, of water of cryftalliza- 
 tion- 
 
 They fuffer no change when expofcd to the air ex- 
 cept it be very moift ; in which cafe they deliquefce. 
 
 When heated, they firft undergo the watery funon, 
 and are then reduced to a white powder, A very vio- 
 lent heat decompofes this fait. 
 
 Muriatic acid precipitates this fait from its folution 
 in water. That acid, therefore, has a ftronger affinity 
 for water than the fait has \. 
 
 8. Muriat of magnefia. This fait abounds in [eaTra^f. SJli 
 water. "• '^^-^ 
 
 It is not eafily cryftallized. Bergman's method was Muria, _. 
 to evaporate it by a confiderable heat to the proper de- magnefia, ; 
 gree of concentration, and then to expofe it to a fud- 
 den cold. By this method he obtained it in fmall 
 needles %. ^ { Bergman,, 
 
 It has a very bitter tafte. It is foluble in its own" 383. 
 weight of water ^, and in five parts of alcohol ||. t Fourcroy,. 
 
 A faturated folution of it quickly forms a jelly ; on jj Bergmatif. 
 which if hot water be poured Ipongy mafles are formed"- 3^3- 
 not even foluble in muriatic acid fl. ^ Sirgman^, 
 
 It is compofed, according to Bergman, of 34 parts'""'- 
 of acid, 41 of earth, and 25 of water. According to 
 Kirwan, lOO parts of magnefia require for iaturation 
 104,27.5 of acid *. * Trip 
 
 it deliquefces very fpeedily when expofed to the'^'''"'/- ^''^■ 
 air. 
 
 A ftrong heat decompofes it. When dried in a high 
 temperature, it is very cauftic f. , ;f-,a„aD»,. 
 
 The following fubftances decompofe it by compound ^n^.j'; 
 affinity : dim. ii. 
 
 Sulphat of foda, Acetite of potafs, i35- 
 
 ainmonia, foda, 
 
 alumina, ■ filver :|. 
 
 Nitrat of ammonia. 
 
 t Bergmtiltf 
 
 Carbonat 
 
 (y) Only at the common temperature. At a high temperature carbonat of ammonia decompofes muriat of 
 magnefia. See IVe/lrum, ^Inn. de Chim. ii. 1 18, 
 
 (z) Bergman affirmed, that this fait decompofed all the fulphats, and propofed it therefore as a certain means 
 of difcovering the prefcnce of fulphuric acid, however combined in any folution ; for the fulphat of barytes is al- 
 moft entirely Infoluble in water. But Mr Piffis has obfervcd, that it does not decompofe fulphat of lime nor of 
 potafs. See Ann. de Chim. xv. 3 1 7.
 
 Muiia's- 
 
 Part III. CHEMISTRY. 
 
 Carbonat of foda 
 
 ammonia (v). 
 
 9. Miiriat of ammonia and magntfia. 'I'his ti'ii)lc 
 fait was tirft mentioned, we believe, by Bergman. It 
 
 70+ 
 
 Mliriat of 
 ammonia 
 aji'l nia^- 
 nefia, 
 
 Carbonat of barytca, 
 potjfs, 
 
 may be formed by pouring ammonia into a iolution of 
 muriat oi magnefia. Part of the magncda ii, jnvcipita- 
 ted, but great part of it remains difl'ulved, alid com- 
 bined with the acid and tlie ammonia. This triple fait 
 18 compofed, according to Fourcroy, of 7^ parts of mu- 
 
 • Am. de '"'" °f magnefia and 27 of muriat of ammonia *. 
 
 Chun-iv. 10. Muriat of alumina This fait cryllallizes with 
 
 difficulty. It has an allringent tafte. Its folution is 
 
 and part of the carbonic ati-l combines with the «irih, 
 and renders it eafily luliible in acids though dried. 
 
 Carbonat of ammonia occafions a precipitate, which 
 is molUy diffolved by adding more carbona*. 
 
 Prufliat of mercury produces an abundant precipi- 
 tate, whicli is foluble in muriatic acid; and v;hich con- 
 fequently is not muriat of mercury. 
 
 A plate of zinc, introduced into a folution of muriit 
 of jargonia, occalions a flight effervelcence ; the liqu jr 
 becomes milky, and in a few days becomes a white fe- 
 mitranlparent jelly. 
 
 Alumina decompofes muriat of jargonia with the 
 
 P'luj ut I. 
 
 — ^ — ( 
 
 M 'r°»t of gelatinous, and cannot be filtrated without much dilu- afTillance of a flight heat ; the alumina dilfolves, the Ii 
 
 alumina, ^ion in water. It is deliijuefcent. When evaporated quor becomes milky, and alfumes the form of a jelly. 
 
 to drynefs, it forms a gummy mafs : in a flrong heat it When the muriat contains iron, it remains in the folu- 
 
 is decompofed 
 
 The following falls decompofe it by compound affi 
 nity 
 
 qudin^ 
 
 Nitrat of aminonia, 
 Acetite of barytes, 
 
 potafs, 
 
 — ^-^— foda, 
 lime, 
 
 Acetite of magnefia, 
 Carbonat of barytes, 
 
 potafs, 
 
 — — — foda, 
 
 ammonia. 
 
 tion, and the precipitated jargonia is quite pure. Here, 
 then, is a method of freeing j.irgonia from iron *. ^y 
 
 12. Muriat of iron. — Muriatic acid forms with the ■'in. A 
 green oxide of iron a fait which cryftaHizes in flat '^'''"'- ^'i'. 
 needles. When expofcd to 'lie air, they deliquefce,^~'„'. 
 and the green oxide attrafts oxygen, and is gradually Mii.U of 
 
 converted into a brown oxide, 
 fait 
 
 Heat decompofes this iron, 
 
 ir. Muriat of jargonia. — This fait is eafdy formed 
 by pouring muriatic acid on newly precipitated jargo- 
 
 708 
 
 13. Muriat of zinc. — This fait, procured by dilTol- Muriat o£ 
 ving zinc or its oxide in muriatic acid, does not cryftai.2"'c, 
 
 nia. It is colourlefs; its tafte is very allringent : by lize. Its folution is colourlefs. When heated, it be- 
 
 evaporation it furnilhes fmall tranfparent cryftals in comes of a blackifli brown. By dillillation, a part of 
 
 needles, which lofe their tranfparence in the air. Mu- the acid is feparated, and muriat of zinc remains be- 
 
 riat of jargonia is very foluble in water and in alcohol ; hind of a milk-white colour, folid, and formed of fmall 
 
 to the flame of which it does not communicate any par- radiated needles. It attrafts molfture in the air. -r,n 
 
 ticular colour. Heat decompofes it ; and it is decom- 14. Muriat of mauganefe. — Muriatic acid diffolves Muriat of 
 
 pofed hkewifeby the faliva when taken into the mouth, the white oxide of manganefe. Its folution afl'ords by "'^"K-'n^'e, 
 
 When muriat of jargonia contains a little filica, it evaporation angular fhining cryftals f : They ure deli- tj'''*"'' ?" 
 
 forms cubic cryftals without confiftence, and refembling quefcent and foluble in alcohol f . * ^i^gantj^. 
 
 a jelly. Thefe cryftals, when expofed to the air, gra- M. Muiiat of cobalt. — The folution of oxide of co- M'/'trj/. ii. 
 
 dually lofe their tranfparency, and diminifh in volume, bait in muriatic acid is of a pale red, except it be con-^'- 
 
 and there are formed in the middle of the fait white laminated with nickel or iron, when it is greenidi. It /^^u 
 
 filky needle-fhaped cryftals. 
 
 Muriat of jargonia is decompofed by fulphuric acid; 
 part of the fulphat precipitates, and part remains dif- 
 folved in the muriatic acid. When this acid is driven 
 off by heat, the remainder of the fulphat is gradually 
 
 Cobalt, 
 
 cryllallizes in fmall needles, which are very deliquefcent. 
 Heat decompofes it. 7>i 
 
 16. Muriat of nickel— This fait is deliquefcent, and .'l"^^''' 
 lofes its acid when expofed to the air ^. ,^ iCif''"' 
 
 17. Muriat of lead. — Muriatic acid combines with 
 
 depofited : if the evaporation be ftopped before the mafs oxide of lead eafily enough : but this fait is more readi- 
 
 be reduced to drynefs, it forms a kind of jelly when ly procured by pouring muriatic acid into a folution of 
 
 cold. It is alfo decompofed by the phofphoiic, citric, nitrat of lead ; the muriat immediately precipitates in 
 
 tartarous, oxalic, and faccholaftic acids, which form the form of a white powder. It is foluble in ^o times 
 
 with jargonia infoluble compounds that precipitate in its weight of boiling water ; and the folution yields by 
 
 white flakes. evaporation fmall, flender, brilliant needles in bundles. 
 
 The gallic acid poured into muriat of jargonia pro- It is fomewhat deliquefcent. When expofed to heat, 
 
 duces a white precipitate ; but a green, bordering on it melts into a brown mafs, formerly called corneous 
 
 grey, if the jargonia contain iron ; and this laft pre- lead. 
 
 712 
 llead. 
 
 cipitate becomes, when dry, of a bright black colour, 
 and refembles China ink. The liquid preferves a green- 
 ilh colour ; new portions of gallic acid produce no far- 
 ther precipitation ; but carbonat of ammonia feparates 
 in great abundance a flaky matter of a purplifh colour, 
 not unlike that of the leys of wine. From thefe expe- 
 riments it follows, that gallic acid has a greater affinity 
 for jargonia than muriatic acid has ; and that the gal- 
 iats ot jargonia and iron are ioluble in muriatic acid. 
 
 It is decompofed by compound affinity by 
 
 Sulphatoff.lverll, \\ B^rgma,, 
 
 Carbonat ot loda. 713 
 
 18. Muriat of tin This fait may be formed by dif- Tin, 
 
 folving tin in hot muriatic acid. By evaporation it 
 aftords needle-fhaped crylltds, which are deliquefcent. 
 
 This fall has a flrong affinity for oxygen. It de- 
 compofes oxy-muriatic, nitric, fulphurous, arfenic, mo- 
 
 lybdic, and tungftic acids, the red oxide of mercury, 
 Carbonat of potafs decompofes muriat of jargonia, black oxide of manganefe, oxide of antimony, zinc, iil- 
 
 3 A 2 ver, 
 
 (v) Only at a high temperature. See Muriat of jimmonia.
 
 372 
 
 Muriits. 
 
 * PclUtitr, 
 
 jinn, de 
 Chim. xii. 
 
 .714 
 Muriat of 
 copper, 
 
 ■f" Bergman. 
 
 Ti 
 Muriat of 
 bifmuth, 
 
 716 
 Antimony, 
 
 7>7 
 Arfenic, 
 t Bergman^ 
 il 293. 
 
 718 
 
 Mercury, 
 
 § Bergman. 
 
 719 
 Muilat of 
 ammonia 
 and mer- 
 tur)-, 
 
 }l Fourcny, 
 Ann de 
 Chim. xiv. 
 
 47- 
 
 710 
 Muriat of 
 fiker. 
 
 7»t 
 
 Muriat of 
 titanium. 
 
 C H E M I 
 
 ver, and gold; and by that means is converted Into oxy- 
 muriat of tin. It even abforbs oxygen when expofed 
 to the air *. Thefe compofitions are doubtlels produ- 
 ced by difpofwg affinity. 
 
 19. Muriat of copper. — This fait may be formed by 
 diffolving copper or its oxide in muriatic acid. 
 
 Its cryftals are prifmatic. It is of a beautiful grafs 
 green colour. It has a very aftringent and cauftic tafte. 
 It deliquefces when expofed to the air. A moderate 
 heat is fufficient to melt it; and when cooled it congeals 
 into a mafs. It requires a ftroiig heat to volatilize it. 
 
 It is decompofed by nitrat of filver-|-. 
 
 20. Muriat of bifmuth. — This fait cryflallizes with 
 difficulty. By fublimation it forms a folt fufible fub- 
 ftance, formerly called butler of lifmuth. 
 
 21. Muriat of antimony. — This fait is found native. 
 It cryftallizes in prifms. When heated it evaporates. 
 
 22. Muriat of arfenic. — This fait cryftallizes ; it is 
 very volatile, and not very foluble, in water J. 
 
 23. Muriat of mercury. — This fait may be prepared 
 by pouring diluted muriatic acid into a diluted folu- 
 tion of nitrat of mercury : the muriat of mercury is 
 immediately precipitated in the form of a white pow- 
 der. Common fait may be ufed inftead of muriatic acid. 
 This fait was formerly called •white mercurial precipitate 
 and calomel. 
 
 It cryftallizes ; but the form of the cryftals, which 
 are very fmall, has not been determined. 
 
 It has little tafte. It is almoft infoluble in water. 
 It is ufed as a medicine. 
 
 It is decompofed by fulphat of ammonia §. 
 
 24. Muriat of ammonia and mercury. — This triple 
 fait was firft difcovered by Fourcroy. It may be form- 
 ed by pouring ammonia into a folutlon of corrofive mu- 
 riat of mercury. It has the appearance of a white 
 powder. Its tafte is at firft earthy, afterwards metallic. 
 It is nearly Infoluble In water. According to Fourcroy's 
 analyfis, It Is compofed of 81 parts of oxide of mercury, 
 16 of muriatic acid, and 3 of ammonia. 
 
 Heat decompofes It; producing ammonia, azotic gas, 
 and muriat of mercury. 
 
 Sulphuric, nitric, and muriatic acids decompofe it ||. 
 
 25. Muriat of filver. — This fait may be formed by 
 dilTolvIng oxide of filver In muriatic acid, or, which is 
 better, by pouring muriatic acid into nitrat of filver; 
 muriat of filver Immediately precipitates. It is very 
 little foluble in water ; according to Monnet, one part 
 of it requires 3072 parts of water. 
 
 When expofed to a fmall heat, It melts into a grey fe- 
 mitranfparent mafs, not unlike horn ; hence It was for- 
 merly called luna cornea. A long continued heat de- 
 compofes It. This fait Is very cauftic : it is employed 
 as an efcharotic under the name of lunar caujlic. 
 
 26. .Muriat of titanium has been formed by Mr Kla- 
 proth. 1 
 
 Sect. VI. 0/ Oxy-muriats. 
 
 Those falls, into which the oxy-muriatic acid enters 
 as an Ingredient, are called oxy-muriats. As we confi- 
 der the nitro-muriatic acid to be precifely the fame 
 with the oxy-muriatic, its combinations of courfe muft 
 receive the fame name. 
 
 S T R Y. Part III. 
 
 1. Oxy-muriat 6f potafs. — This fingular fait was dlf- Ox\.mu. 
 covered by Mr BcrthoUet in 1786. It may be formed ■''^'s- 
 by faturatiiig a folutlon of potafs with oxy-muriatic ^ 
 acid gas. By evaporating this folutlon in the dark.OiT.mn- 
 common muriat of potafs is firft obtained : When It Isriatof pot. 
 feparated, and the liquor allowed to cool, oxy-muriat'''^*" 
 
 of potals cryftallizes. 
 
 Its cryftals are rhomboids, of a filvery brilliancy. 
 
 It has an Infipid cooling tafte, refembling that of nitre. 
 It Is foluble in 1 7 parts of water at the temperature of 
 60, and in 2i parts of boiling water *. It does 'not* Mtylt^ 
 deliquefce in the air ; but light converts it into com- !<icbcl/in't 
 mon muriat by feparating oxygen. When heated, it 5'''"'''"'A '•• 
 melts, and gives out oxygen gas; and this is the beft "'*' 
 nethod hitherto difcovered of obtaining that gas in a 
 ftate of purity. According to Mr Hoylc, it contains 
 about half its weiglit of concrete oxygen -j-. | iHif^ 
 
 When mixed with charcoal, iron, and many other 
 comhuftlbles, and heated. It detonates with aftonifliing 
 violence. This property induced the French chemlfts 
 to propofe it as a fubftltute for nitre in the preparation 
 of gunpowder. The attempt was made at Lifons in 
 178S ; but no fooner had the workmen begun to tritu- 
 rate the mixture of charcoal, fulphur, and oxy-muriat, 
 than it exploded with violence, and proved fatal to Mr 
 Letors and Mademoifelle Chevraud. The force of this 
 gunpowder when It is prepared is much greater than that 
 of the common fort of powder ; but the danger of pre- 
 paring it, and even of ufing It after it is prepared, is fo 
 great, that it can hardly ever be fubftltuted with advan- 
 tage for common gunpowder. 
 
 Fourcroy and Vauquelin afcertained by experiment, 
 that this fait exploded when triturated with fulphur, 
 charcoal, antimony, arfenic, cinnabar, fugar, gums, oils, 
 alcohol, ether, and fulphuret of Iron. When thefe fub- 
 ftances were mixed, and ftruck with a hammer, the ex- 
 plofion took place. The theory of thefe explofions 
 was firft pointed out by Mr BerthoUet. The oxygen 
 of the oxy-muriatic acid combines with the combuf- 
 tlble, and at the fame time lets go a quantity of calo- 
 ric ; and trituration or percuffion ails merely by bring- 
 ing the particles which combine within the fphere of 
 each others attraftlon. ^j, 
 
 2. Oxy-muriat of foda. This fait was difcovered atOxy-mu- 
 the fame time by Mr BerthoUet. Its properties are '■'^' o'^ '"'^i 
 the fame with the laft, except that it Is too deliquef- 
 
 cent to be ufed. 
 
 3. Oxy-muriat of ammonia. — This combination is im- 
 poffible. The oxy-muriatic acid and ammonia decom- 
 pofe each other. 
 
 4. Oxy-muriat of barytes. 
 
 J. lime 
 
 6. n^2g; 
 
 7'4 
 'tes. T Thefe fahs were dif-Ojy-mu- 
 Y covered by BerthoUet "at of ba- 
 nefia. 3 alfo. They all poffefs ^f 'Jg"'' 
 the property of detonating with combuftibles, and of 
 being reduced by that means to the ftate of common 
 murlats. Mr Tennant has lately propofed the oxy. 
 muriat of lime as a fubftltute for the other fubftances 
 formerly ufed in the new mode of bleaching ; particu- 
 larly for bleaching printed cottons : And, as far as we 
 can learn, it anfwers the purpofe remarkably well (z). .j, 
 
 7. Oxy-muriat of mercnry. — This fait was formerly Oxy-mu- 
 called corrofi-ue JuUimate, and afterwards corrofive muriat "^t oC mCT' 
 
 (z) We have been informed, that this fait had been ufed by bleachers in Scotland fome years before Mr Ten- 
 Rant propofed it.
 
 Part III. 
 
 t MacjM 
 
 C H E M 
 
 Oxy-mu- of mercury. BerthoIIet firft pointed out the nature of 
 riat-. Jfj compofition. 
 
 """'y^'^ This fait was mentioned by Rhafes in the loth cen- 
 tu\y ; and it feems to have been known in the ealt at 
 a much earlier period (a). The methods of preparing 
 it iifed by the older chemills were numerous, complica- 
 ted, and generally concealed as fecrcts. We fhall not 
 attsmpt, therefore, to give any account of them ; and 
 the methods ufed by later chemiils have been defcribed 
 at eonfiderable length in the article Chemistry f£n- 
 
 cyrl-n" Sis-) 
 
 It may be prepared by diffolving mercury in a fuffi- 
 cient quantity of oxy-muriatic acid, or by diifolving red 
 oxide of mercury in common muriatic acid. 
 
 When carefully cryllallized, this fait affumes the 
 form of cubes or oblique parallclopipeds, or rather qua- 
 drangular prifms, with fides alternately narrower, and 
 terminated by two inclined planes meeting together. 
 
 It has an exceedingly difagreeable metallic talle. 
 
 It is folul)le in 19 times its weight of water at the 
 * Sftilmnn. temperature of 50'*. Boiling water, according to Mac- 
 quer, diffolves half its weight of it. Alcohol, at the 
 temperature of 70", dUTolvcs -jths of its weight of this 
 fait t- 
 
 It does not attraifl moiflure from the air. 
 
 It is foluble in fulphuric, nitric, and muriatic acids. 
 
 When triturated with ^Jths of its weight of mercury 
 and a little water, and then fublimed, it forms a white 
 inCpid fait, called formerly calomel or Jtueet mercury : 
 This, as Scheele has proved, is precifely the fame with 
 conimon muriat of mercury. 
 
 The theory of thefe two preparations is now pretty 
 obvious. The experiments of Adet and Pelletier have 
 (hewn, that oxy-muriatic acid may be obtained from 
 corrofive muriat of mercury ^. We may conclude, 
 therefore, with confidence, that the fait is an oxy-mu- 
 riat. It cannot be prepared by means of cominon mu- 
 riatic acid, except with red oxide of mercury, or fome 
 other fubilance from which it may abforb oxygen. 
 When pure mercury is added to oxy-muriat, it fcizes 
 the oxygen from the oxy-muriat, and the whole is con- 
 verted into common muriat. 
 
 It is decompofed by 
 
 Tartar, 
 Moil metals. 
 
 8. Oxy-muriat of tin. When an amalgam of tin is 
 triturated with its own weight of corrofive muriat of 
 mercury, and the mixture is diftillcd in a glafs retort 
 by means of a very gentle heat, there palTes over a thick 
 white fmoke, which condenfes into a colourlefs liquor 
 that emits copious fumes, and has been called, in con- 
 fequence, fmoLing liquor of Libavius. This liquor was 
 examined by Mr Adet. He found, that when about 
 yd part of water was added to this liquor, it ceafed to 
 fume, and alTumed a cryRalline form ; that then it 
 might even be made red hot without fubliming. It 
 therefore owes its volatility to want of water, or rather 
 to a ftrong attradtion for water. He found that this 
 fubftance was capable of dilTolving, and therefore of 
 oxidating more tin, without the emiffion of any hydro- 
 gen, and confequently without the decompofition of 
 
 } Ann, de 
 Cbim. i. I 
 and xii. 
 
 716 
 Oiy-mu- 
 Tiat of tin. 
 
 I S T R Y. 373 
 
 water; he concluded from this, that it was compofed of P'lu'p*'*"' 
 oxy-muriatic acid and tin *. This has been completely ~~~^ 
 proved by Mr Pelletier, who found that when oxide o( ^.^-^ j 
 tin was combined with oxy-muriatic acid, it formed a 
 compound precifely the fame with the fmoking liquor 
 of Liibavius -f-. f ^nn. it 
 
 This fait may be prepared, as Pelletier has proved, ^-''"'"''•»'>*« 
 by diifolving tin in muriatic acid, and then faturating it'*^' 
 with oxy-muriatic acid gas. 
 
 It is ufed in dyeing. .j- 
 
 9. Oxy-muriat of iron. This fait is deliquefcent ; Oxy-mu- 
 colourlcfs ; of a pure bitter tafte, without any of the riat i^f iron, 
 fweet aftringency of the common falts of iron J. j r.amte. 
 
 Few of the other oxy-muriats have been hitherto ex- MambcJItr 
 amined with attention : Many of the metals, indeed,^'"- ^• 
 have been diffolved in aqua-rcgia ; but in moll of thefe''" '" 
 folutions the fait produced is a common muriat. The 
 nitric acid fupplies oxygen, and the muriatic acid dif- 
 folves the oxide. 
 
 Sect. VII. Of Phofphats. 
 
 Those falts, into which phofphoric acid enters as 
 an ingredient, are called phofphats. This clafs of falts 
 was firft difcovertd by Margraf. «jg. 
 
 1. Phofphat of potafs. This fait cryftalllzes in fliort Phi.fphat 
 tetrahedral prifms, terminated by quadrangular pyra- '^f P"'*'^) 
 mids. 
 
 It is very foluble in cold water, and ftill more fo in 
 hot water. 
 
 It decrepitates on ignited coals like common fait. 
 W.hen a very ftrong heat is applied, it melts into an 
 opaque vitreous mafs, ftill foluble in water. 
 
 The following falts decompofe it by compound affi^ 
 nity : 
 
 Sulphat of lime, Muriat of mercury, 
 
 Nitrat of mercury, Acetlte of lead. 
 
 2. Phofphat of foda. — Dr Pearfon, who firft formed phofphat 
 this fait, gives the following procefs for preparing it ; of foda, 
 
 Diflblve ill a long-necked matrafs 1400 grains of cry. 
 ftallized carbonat of foda in 2100 grains of water at the 
 temperature of 150". Add gradually 500 grains of 
 phofphoric acid of the fpccific gravity 1,85, Boil the 
 liquor for fome minutes ; and while it Is boiling hot,, 
 filtrate it, and pour it into a Ihallow veflcl. Let it re- 
 main In a cool place, and cryftals will continue to form 
 for feveral days. From the above quantities of mate- 
 rials he has obtained from 1450 to 1550 grains of 
 cryftals. 
 
 Its cryftals are rhomboidal prifms, of which the acute 
 angles are 60 , and the obtule angles \20'', terminated 
 by a three-iided pyramid. 
 
 Its tafte is almoft the fame with that of common fait. 
 
 It is foluble in water. When expofed to the air it 
 efflorefces. 
 
 This lalt has been introduced into medicine as a pur- 
 gative, and on account of its pleafant tafte has of late 
 been much ufed. It Is ufually taken in broth, which 
 it is employed to feafon inftead of common fait. 
 
 Hellot remarked a particular fait in urine, different 
 from thofe that had ufually been obferved, in 1737. 
 Haupt defcribed it in 1740 under the name oi fal mi- 
 
 rabile 
 
 (a) If we liften to Junker, the ancients applied the name mcrcurium to this fait ; mercury they called argeti' 
 turn vivum.
 
 374- C H E M I 
 
 I'lu.f, hits. y,,/,;/^^^,.;,,/;,„^ ox wontfcrfiil perlctltcl fa!l. It was call- 
 * fd perhiteil troni the grey, opaque, pearl-like colour 
 
 uhijh it afTumi'd when melted bv tlie blow-pipe. Mar- 
 p-iii deferibcd it in 1741;, and found it would not yield 
 piiofphorus when treated with charcoal, as the other 
 lalts of urine did. Roiielle the Younger analyfed it in 
 1776, and concluded from his experiments that it was 
 a compound of phofphoric acid and foda ; but Mr 
 Proud, being unable to obtain phofphorus from it, con- 
 cluded, that it did not contain phofphoric acid, but 
 •another acid analogous to the boracic. To this fub- 
 iUnce, which Mr Prouft aftually obtained, Bergman 
 gave the name oi perlated add, and Morveau afterwards 
 called it ouretic acid. But Mr Klaproth foon after- 
 wards analyfed it, and proved that it confifted of foda 
 fupcrlaturaled with phofphoric ae.id. Scheele foon af- 
 ter made the fame difcovery. This acid of Mr Prouft, 
 then, is merely phofphat of foda combined with phof- 
 ,^3 phone acid, or acidulous phofphat of foda, 
 
 3. Phofphat of ammonia. — This (alt forms oblong- 
 pointed cryftals, pr, as Mr Lavoifier aflirms, cryftaU re- 
 fembling ihofe of alum. 
 
 It is foluble in water. Heat evaporates it fo eafily, 
 that it is difficult to obtain it in cryftals except by adrl- 
 ing an exeefs of alkali. 
 
 Microcofmic fait, or fait of urine, is merely a mixture 
 of thefe two laft defcribed falts. 
 
 4. Phofphat of barytcs. — This fait is infoluble in 
 water *. 
 
 Of lime, 5- Phofphat of lime. — This fait is taftelefs, and al- 
 
 moft perfeftly infoluble in water. It forms the balls 
 of bones, and is therefore often called earth of bones. 
 Wenzel obferved it cryftallize when held in folution by 
 phofphoric acid. 
 
 It is decompofed by fulphat of ammonia f . 
 Carbonat of potafsj, 
 
 • foda ^ . 
 
 6. Phofphat of ftrontites. — This fait was firft formed 
 by Dr Hope. It is a white powder foluble in 1920 
 
 Phofphat 
 ol auimo- 
 
 731 
 Of "1 arytes 
 
 \ntlhfiamp 
 
 Chim, vi. 
 
 37- 
 
 % Bergman. 
 
 § Id. 
 
 733 
 Of (Iron . 
 ti'es, 
 Dr Ho/,. 
 
 parts of boiling water | 
 
 7. Phofphat of magnefia. — This fait does not cry- 
 ftallize except with exeefs of acid, and then the cry- 
 Tn^y: £</(». ftals are very fmall. Somewhat longer cryftals may be 
 IV. 16. formed by dropping phofphoric acid into acetite of mag. 
 
 nefia. It moft commonly forms by evaporation a gum- 
 
 734 
 Of maj;ne- 
 
 fia, 
 
 ^ Bergman^ 
 ii. 390- 
 * W^snzcl. 
 
 731 
 Of alumi- 
 na, 
 
 Of iron, 
 
 my mafs. It is foluble in alcohol^. 
 
 It is infoluble in nitric acid. It melts by a ftrong 
 heat into a porcelain-like fubftance *. 
 
 8. Phofphat of alumina. — This is a faline powder, 
 infoluble in water. Diflolved in phofphoric acid, it 
 yields a gritty powder, and a gummy folution, which 
 by heat is converted into a tranfparent glafs. 
 
 9. Phofphat of iron. — This fait is merely a dry ad- 
 hcfive mafs, infoluble in water, but foluble in acids. 
 With exeefs of acid, it forms cryftals which do not de- 
 liquefce, and by heat are converted into a garnet-co- 
 loured glafs -f-, 
 
 10. Phofphat of zinc. — It does not cryftallize, but 
 when evaporated becomes a gummy mais, which may 
 be melted into a tranfparent glafs \. 
 
 11. Phofphat of manganefe. — The folution of the 
 
 \Ti. 
 
 737 
 Of zinc, 
 
 738 
 njfg ^ " oxide of manganefe in phofphoric acid is reddifh, but 
 
 -,g becomes white on expofure to the air. 
 Of nickel, 12. Phofphat of nickel 
 S Bergman, cryftallize 15. 
 JU,»68, 
 
 S T R y. Part III. 
 
 17,. Phofphat of nrfenic.-^It cr>ftalHzes in fmall tior^ts. 
 grains hardly foluble in water *. ' v- ■ < 
 
 14. Phofphat of uranium. — Firft formed by KInp-Qf'''° . 
 roth. It does not cryftallize, but afl"umes the appear- * a,.':^wa';,' 
 ance of yellowilh white flakes, diffieultty foluble inii. ago. ' 
 water. ;.)i 
 
 15. Phofphat of antimony and lime. — Dr Pearfon *^^ *"^*' 
 has difcovered, that ihe well known medicine called'""!'' ^ 
 jfames'i Powder is a triple fait, compofed of phofphoric James"? 
 acid, oxide of antimony, and lime. It is very inlolublcP^'WJcf. 
 in water. 
 
 The remaining phofphats are fcarcely known. 
 
 Sect. VIII. Cf Borais. 
 
 The compounds into which the boracic acid enters 
 are called borats. 
 
 1 . Borat of potafs. — This fait, formed by combining Boiat ot 
 boracic acid and potafs, is very little known. Baron put»fs, 
 firft formed it. Borat of potafs cryftallizes, is foluble 
 
 in water, and may be melted into a vitreous mafs, fo- 
 luble in water. .^, 
 
 2. Borat of foda or borax. — This fait is brought Of foda, 
 from the Eaft Indies in an impure ftate under the name 
 
 of tinkal. When purified in Europe, it takes the name 
 of borax. 
 
 Its cryftals are hexangular prifms, of which two fides 
 are much broader than the remainder, terminated by 
 triangular pyramids. It is of a white colour. Its fpe- 
 cific gravity is 1,740. 
 
 Its tafte is ftyptic and alkaline. 
 
 It is foluble in 18 times its weight of water of the 
 temperature of 60°, and 6 times its weight of boiling 
 water. 
 
 It is compofed, according to Bergman, of 17 parts 
 of foda, 39 of acid, and 44 of water. 
 
 When expofed to the air, it efflorefces flowly and 
 flightly. 
 
 When heated, it fwells, lofes about four-tenths of its 
 weight, becomes ropy, and then aflumes the form of a 
 light, porous, and very friable mafs, known by the name 
 ot calcined borax ; it then melts into a tranfparent glafs, 
 ftill foluble in water. 
 
 By compound affinity it is decompofed by 
 
 . Nitrat of mercury f. | Bergman. 
 
 When two pieces of borax are ftruek together in the 
 dark, a flafh of light is emitted J. * Aeevm 
 
 Borax has the property of facilitating the fufion oiNkhotfon'i 
 a great number of bodies. This property renders it 7'""'''«'> "• 
 ufeful in glafs-making, In aflaying ores, and in folder-* 
 ing metals. 
 
 Borax turns fyrup of violets green; it appears there- 
 fore to be fuperfaturated with alkali. 
 
 The real borat of foda, or the fait in which boracic 
 acid and foda faturate each other, has not yet been exa- 
 mined with attention. According to Dr Withering, 
 foda requires twice its weight of boracic acid to fatu- 
 rate it. 
 
 3. Borat of ammonia.- — This fait has been examined of Imm* 
 
 I 
 
 only by Mr Fourcroy. 
 
 Its cryftals are polyhedral pyramids. 
 It has a poignant urinous tafte, and turns fyrup of 
 violets green. It diffolves readily enough in water. , r . 
 
 It isgreenifh, and does not When expofed to the air, it gradually lofes its cryftal-^if^J; 
 Jine ferm and becomes brown §. Pattii. 
 
 4. Borat ch. 4.
 
 Part in. 
 
 Borats. 
 
 746 
 Of lime, 
 
 747 
 Of (Iroll- 
 tites. 
 * Ho/i-, 
 Trarif. Edin. 
 jv. 17. 
 
 4. Borat of baiytes. — Unknown. 
 
 5. Borat of lime. — It is difficultly foluble in water, 
 and did not cryftallize with Beaume. 
 
 6. Borat of llrontites. — This fiilt was firft formed by 
 Dr Hope. — It is a white powder, loKible in about 130 
 parts of boilinj;; water. The folution turns the fyrup 
 of violets green •. 
 
 7. Borat of magncfia. — It aflTumes the appearance of 
 
 CHEMISTRY. 
 
 It ia taftelefs and nearly infoluble in wafer. 
 
 fpecific gravity 
 
 Its 
 
 748 fmall irregular cryftals. It is toluble in acetous and ior- 
 Of magne mic acids. Alcohol decompofes it. It melts eafily in 
 ^^' the fire without Ijting decompofed f. 
 
 ■f ergm It, g Borat of alumina. — It does not cryftallize, and is 
 fcarcely foluble in water. 
 
 o. Borat of iron. — Its cryftals are of a yellow culour, 
 but the fait has never been examined with attention. 
 
 10. Bojat of zinc.-*This fait does not appear to be 
 capable of cryllallizing. By heat, it melts into a light 
 green infoluble flag J. 
 
 J I. Borat of cobalt. — When o.xide of cobalt is melt- 
 ed with boracic acid, a bluifh grey flag is produced. 
 This, by lixiviation and evaporation, yields cryftals of 
 a reddilh white colour and ramified form §. 
 
 12. Borat of nickel. — A faline fubltance difficultly 
 
 jj. 33f. 
 
 749 
 Of alumi- 
 na, 
 
 7^0 
 Of iron, 
 
 751 
 Of 21DC, 
 
 751 
 Cnbalt, 
 
 753 
 
 Nickel 
 
 II Btrg"'"'- foluble 
 
 7i4 
 Lead, 
 
 755 
 Tin, 
 
 756 
 
 3. Borat of lead. — When boracic acid and red oxide 
 of lead are melted together, the produCl is a fine grecn- 
 ifli yellow, tranfparent, hard, infoluble glafs ^. 
 
 14. Borat of tin. — When equal parts of boracic acid 
 and tin filings are melted together, the produft diffol- 
 ved in water yields by evaporation tranfparent white 
 polygonous cryftals. 
 
 15. Borat of copper. — When borax is poured into a 
 folution of fulphat of copper, borat of copper is preci- 
 pitated in the form of a pale light green jelly, which when 
 dikd is with great difficulty foluble in water. It eafily 
 
 m Bergman, melts into a dark red vitreous lubftance*. According 
 to Palm, by long trituration of filings of copper and 
 boracic acid in water, and then digtiling the mixture, 
 it diffolves, and cryftals may be obtained from it. 
 
 16. Borat of bifmuth.— A white powder, which 
 melts into a white tranfparent permanent glafs f. 
 
 17. Borat of arfenic. — White oxide of , artenic and 
 boracic acid form a. fait- foluble in water and cryftjl- 
 lizable J. 
 
 Sect. IX. 
 
 Bifmuin, 
 
 ^ li erfz.eL 
 758 
 
 Arfenic, 
 J Rcuji. 
 
 Of Fluau. 
 
 Those falts into which fluoric acid enters are called 
 Jluats. Thty were firft formed by Schecle. 
 
 1. Fluat of potafs. It forms a gelatinous mafs al- 
 moft without tafte. 
 
 It diffolves readily in water. When expofcd to the 
 ISchceUaa fire it melts without any ebulition § 
 
 fluor. 
 
 759^ 
 
 Fluat of 
 fotaf?, 
 
 760 
 Snda, 
 
 Ib\ 
 Ammonia, 
 ^ lyitgtli. 
 
 761 
 
 BarvtfB: 
 
 2. Fluat of foda. This fait refembles exadfly the 
 fluat of potafs j|. 
 
 3. Fluat of ammonia. It cryftallizes in fmall prifms. 
 It is deliquefcent, and. is partly decompofed by heat<([. 
 
 It is decompofed by 
 
 Nitrat of mercury, 
 
 filver, 
 
 . lead. 
 
 4. Fluat of barytes. A powder which requires a 
 - Birg'/ian. large quantity of water to diflblve it *. 
 
 76.S J. Fluat of lime. This fait abounds in nature. It 
 
 *^'"^' is known by the name of fluor fpar. 
 
 It cryftallizes moft commonly in the form of cubes. 
 
 764 
 
 It is not altered by the air. 
 about 3,1. 
 
 When expofed to a fudden heat it decrepitates. A 
 very violent heat melts it into a white opaque mnfs. 
 
 When reduced to powder and heated it becomes phof- 
 phorefcent ; but it lofes this quality altogether if it be 
 heated red hot. 
 
 6. Fluat of ftrontites. This fait was formed by Dr 
 Hope : but its properties have not been examined. 
 
 7. Fluat of magnefia. — It is not foluble in water ex- l^agneCaj 
 cept there be an exctfs of acid. In that cafe, by fpon- 
 taiieous evaporation, it forms hexagonal prifms, termi- 
 nated by a low pyramid compofed of three rhomboidal 
 
 fides. 
 
 Thefe cryftals are hardly foluble in water. Alcohol 
 diffolves a fmall portion of them. Heat does not de- 
 compofe them *. » n 
 
 b. rluat of alumma. A faline mafs; which is fweet- 'i- 384. 
 i(h, clammy, and gelatinous. 705 
 
 9. Fluat of filica. Little is known concerning this '^'"'^g"^' 
 Angular combination, except that it can cxift in a ga- SiUta, 
 feous form, and that it dcpofites filica in cryftals after a 
 certain time. 
 
 I o. Fluat tf filica and potafs or foda. This triple 
 fait may be formed by pouring fixed alkali into a folu- 
 tion of fiuat of filica. It contains an excefs of acid. 
 On evaporation it yields a kind of jelly, which when ■ 
 dry feparates into gritty particles like fand. It is fo- 
 luble in 96 parts of hot water. In the fire it readily 
 melts into a white mafs. If the heat be continued the 
 acid feparates, and there remains a tranfparent glafs, 
 which is foluble in water, and forms a liquor Jt!icum\. ^ 5^^,,);. 
 
 11. Fluat of iron. It is incryftallizable ; but when rr,/r,7«r. 
 evaporated leaves a haid mafs, ""A i. sc?-. 
 
 12. Fluat of zinc. It refembles that of iron. t"frTraniI. 
 
 13. Fluat of manganefe. It may be formed by pour-MmlUc 
 ing fiuat of ammonia into a folution of oxide of zinc influats. 
 any of the three mineral acids. It cryftallizes. 
 
 14. Fluat of cobalt. A yellow gelatinous mafs. 
 
 15. Fluat of nickel. It affords green cryftals. 
 
 16. Fluat of lead. A fweet tafted powder. 
 
 17. Fluat of tin. A naufeous tafted jelly. 
 
 18. Fluat of cupper.. Blue cryftals ; fome of them'" 
 oblong, others cubic. 
 
 19. Fluat of arfenic. Small cryftals. 
 
 70. Fluat of mercury. A powder. Before the blow. 
 pipe it melts into a yellow glafs, moft of which evapo- 
 rates by a continued heat |. , .W«/.ott ■ 
 Sect. X;. Of Carbonats. ^'"°^- 
 
 The compounds into which the carbonic acid enters 
 are called carbonats. They were firft analyfcd by Dr 
 Black. 
 
 I. Carbonat of potafs. This fait is formed by fatu-o '1 ,, - 
 rating potals with carbonic acid, which is beft done byof potafc^ 
 expoling a folution of potafs fur a coiifideiable time to 
 carbonic acid gas. 
 
 It cryftallizes, according to Bergman, in quadrangular 
 prifms ; the apexes of which are compofed of two in- 
 verted triangles, converging like tiie roof of a houfe ||.i| 
 According to Pelietier they are tetrahedral rhomljoidal 
 prifms, with dihedral funuiiits. The complete cryftal 
 has eight faces, two hexagons, two redanglcs, and four 
 rhombs ^. 
 
 BLrgman, 
 
 It 
 
 * Ann. dt ■ 
 CUm, XT, 
 13.
 
 37« 
 
 G H E M I 
 
 t PlUltitr. 
 
 Carhonati. It hii an alkalin«, hut not « caufti'c taftc, 
 
 ^~~^ It is foluble at the common temperature in about 
 
 J "^'"' io\xr times its weight in water*. Boiling water dif- 
 
 folves |ths of its weight f . Alcohol, even when hot, 
 
 does not dilTolve above xt'bo^ parts of it. 
 
 AccordiiiiJ' to Bergman, it is compofed of 48 parts of 
 
 potafs, 20 of acid, and 32 of water. According to Pel- 
 
 ieticr, of 43 parts of acid, 40 of potafs, and 17 of water. 
 
 Bergman under-rated the quantity of acid from not ob- 
 
 ferving that the fait lofes part of its acid when heated. 
 
 Even fohition in hot water produces a feparation of 
 
 feme acid J. 
 
 It is not altered by expofure to the air. 
 
 Heat deprives it of its water and part of its acid, but 
 
 does not decompofe it completely. The following falts 
 
 deconjpofe it by compound affinity ; 
 
 %U 
 
 ^ Bergman, 
 
 11 /i 
 
 Sulphat of lime, 
 
 — barytcs, 
 
 — — foda, 
 
 — — ammonia, 
 
 magnelia, 
 
 . alumina, 
 
 Muriat of barytes, 
 
 lime, 
 
 ~— — ammonia, 
 
 •^— magnefia, 
 
 alumina, 
 
 foda §, 
 
 Nitrat of barytes, 
 
 foda, 
 
 — ammonia, 
 
 magnefia, 
 
 — • alumina, 
 
 Acetite of barytes, 
 
 I lime, 
 
 . ammonia, 
 
 I magnefia, 
 
 alumina, 
 
 Oxy-muriat of mercury, 
 Phofphat of hme \\. 
 
 769 
 
 Carl>onat 
 of foda. 
 
 Nitrat of lime, 
 When potafs is faturated with carbonic acid it al- 
 ways lets fall a quantity of filica. Mr Pelletier has pro- 
 pofed this faturation as the bell method of purifying 
 potafs from that earth. 
 
 2 Carbonat of foda. This fait may be formed in the 
 fame manner with carbonat of potafs. 
 
 Its cryftals are fivefided prifms, vs'ith one of the an- 
 gles frequently truncated, furmounted by dihedral pyra- 
 mids with rhomboidal faces. 
 
 Its tafle is precifely the fame with that of carbonat 
 of potafs. 
 
 It is foluble in double its weight of cold water. 
 It is compofed, according to Bergman, of 1 6 parts 
 of acid, 20 of alkali, and 64 of water. 
 
 It efflorefces when expofed to the air. Heat is inca- 
 5 Bergman, p^^lg of decoiiipofiiig it completely ^. 
 *■ ' The following falts decompofe it by compound affi- 
 
 nity : 
 
 Sulphat of ammonia, 
 
 barytes, 
 
 . lime, 
 
 magnefia;}:, 
 
 alumina. 
 
 \ Bergman* 
 
 770 
 
 Carbocat 
 of ammo- 
 nia, 
 % Bergman, 
 
 111, 
 
 Muriat of barytes, 
 
 ammonia, 
 
 . lime, 
 
 •^— magnefia, 
 
 alumina, 
 
 Acetite of barytes, 
 
 ammonia, 
 
 lime, 
 
 magnefia, 
 
 alumina, 
 
 Nitrat of ammonia, 
 
 magnefia, 
 
 alumina, 
 
 lead*, 
 
 Phofphat of lime f . 
 This lalt forms oftahe- 
 
 S T R Y. Part lit. 
 
 cold water. Hot waM!" diHfj've? iti own weight of it. C^rbpn^ts, 
 According to Bergman it is compofed of 43 parts of ^— — y-— ' 
 alkali, 45 of acid, and i 2 of water. 
 
 When expofed to the air It becomes fomewhat moift. 
 The fmallell heat is fuiHcient to evaporate it. 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Acetite of barytes, 
 
 lime, 
 
 magnefia, 
 
 — — alumma. 
 
 Sulphat of alumina, 
 Nitrat of lime, 
 Muriat of lime, 
 
 magnefia, 
 
 — — alumina, 
 
 /\. Carbonat of barytes. 
 native. 
 
 This fait has been fouad Carbonat 
 of barytes. 
 
 Its cryftals have been obferved to affume four diffe- 
 rent forms; double lix-fided art*] double four-fided py- 
 ramids, fix-fided columns terminated by a pyramid with 
 the lame number of faces, and fniall radiated cryftals 
 4 an inch in length, and very thin, appearing to be 
 hexagonal prifms, rounded towards the point. 
 
 Cold water dilTolves ^yo^j part, and boiling water 
 ■vTsr P"""' °^ '^'^ ^''''' Water faturated with carbonic 
 acid diflblves -j-fsth part*. * Ftureray, 
 
 According to Dr Withering, who firft difcovered itAnn.Je 
 native, it is compofed of 80 parts of barytes and 2D of ^'-""'- '"• 
 acid. Bergman informs us, that artificial carbonat is *' 
 compofed of 7 parts of acid, 28 of water, and 65 of 
 earth f. f Bergman, 
 
 It is not altered by expofure to the air. i. »i. 
 
 It is decompofed by the application of a very violent 
 heat J. \DrlUfe, 
 
 By compound affinity it is decompofed by the fol- 
 lowing falts : 
 
 Nitrat of alumina, 
 Muriat of lime, 
 
 : — ammonia, 
 
 magnefia, 
 
 alumina. 
 
 3. Carbonat of ammonia. 
 dral cryftals, having for the moft part their two oppofite 
 apexes truniated J. 
 
 Its tafte and fmell, though much weaker, are the 
 fame with thofe of pure ammonia. Like all the alka- 
 line carbonats it converts vegetable blues to green, pre- 
 cifely as pure alkalies do. 
 
 It is foluble in rather Icfs than twice its weight of 
 
 Sulphat of foda, 
 
 lime, 
 
 - — ammonia, 
 
 magnefia, 
 
 alumina. 
 
 Nitrat of foda, 
 
 . lime, 
 
 ammonia, 
 
 magnefia, 
 
 5. Carbonat of lime. 
 
 Acetite of lime, 
 
 — — magnefia, 
 
 alumina. 
 
 771 
 
 This fubftance, under the Carbonat 
 names of marble, chalk, lime Hone, &c. exills in great"^""'*' 
 abundance in nature, varioufly mixed with other bodies. 
 
 When pure, it is of a white colour, and has very 
 little tafte. 
 
 It is infoluble In pure water j but water faturated with 
 carbonic acid dlffolves tt'oo part of it ; from this folu- 
 tion it gradually precipitates as the acid leaves it in 
 the form of fmall rhomboidal cryftals §. t Birgman, 
 
 It is compofed, according to Bergman, of 34 partsi. 11. 
 of acid, II of water, and 55 of lime. 
 
 It fuffers little or no alteration by being expofed to 
 the air. 
 
 When expofed to heat, it firft lofes its water, and 
 afterwards its acid feparates as the heat is increafed : 
 But to feparate the acid completely, a very ftrong heat 
 is required. 
 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Sulphat of alumina, 
 
 7 copper. _ yy^ 
 
 6. Carbonat of ftrontites. This fait, which was firft Carbonat 
 examined by Dr Hope, is infipid, and foluble in 1536°/ ft'on- 
 
 parts''"''
 
 Part III. 
 
 ^ Fouicroy^ 
 jirtn, df 
 Chim. li. 
 
 } Bulini. 
 
 Hid. 
 
 ibiJ. 
 
 Carboiiats. pgrto of hoiling water. It is compofed of 30,2 parts of 
 "' 1 acid, 69,8 of ftrontites. A violent heat decompofes it *, 
 ~ °t'v •• 7. Carbonat of maffnefia. This fait may be formed 
 jv. 5. oy faturating the common magneda or the Ihops with 
 
 774 carbonic acid gas. 
 Carbonat of j( diffulves in water faturated with carbonic acid; 
 magneua. ^^^ forms by evaporation cryllals, which are traiifparent 
 hexagonal prifms, terminated by a hexaj^onal plane ; 
 thefe are partly in groups and partly folitary : their 
 f BK/iMi/z/f length is about fix lines, their breadth two f. They 
 laAlagMp. ^ygrg difcovered by Mr Butiai of Geneva. 
 
 Water at the temperature of 50 diffolves j'-j- part of 
 its weight of this fait \. When in the ftate of powder, 
 and of courfe deprived of its water of cryftallization, it 
 is much more inioliible ; and what is very remarkable, 
 it is more foluble in cold than in hot water, impregna- 
 ted with carbonic acid ^. 
 
 It is compofed, according to Fourcroy, of 50 parts 
 of acid, 25 of magnefia, and 25 of water. 
 
 When expofed to the air, it efflorefces, and falls into 
 
 U Fourcroy, powder||. _ 
 
 When heated, it decrepitates, falls into powder, and 
 is decompofed «(f. 
 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Sulphat of lime, Nitrat of lime, 
 
 ammonia, Muriat of lime, 
 
 alumina, Acetite of lime. 
 
 8. Carbonat of alumina. Carbonic acid is capable of 
 diflblving alumina; for if alum be decompofed by an al- 
 kaline carbonat, fome alumina remains dilfolved in the 
 liquor, and may be precipitated by a heat fafTicicnt to 
 drive off the carbonic acid *. It cannot be doubted, 
 then, that there may be produced a carbonat of alumi- 
 na; but the fait has never been examined with accuracy. 
 
 9. Carbonat of iron. Water faturated with carbo- 
 nic acid diffolves Tsfo^ part of its weight of iron, 
 which gradually precipitates by cxpofure to the air -j-. 
 Ruft of iron is a kind of carbonat, at leaft it always 
 contains carbonic acid. 
 
 10. Carbonat of zinc. Zinc is copioufly diffolved 
 by water faturated with carbonic acid \. As the me- 
 tallic oxides, when faturated with carbonic acid, do not 
 differ materially in their appearance from pure oxides, 
 we fhall not attempt to defcribe any of the metallic car- 
 bonats. We fhall, however, prefent our readers with 
 the following Table, exhibiting a view of the weight 
 which metallic oxides gain by being faturated with this 
 acid. 
 
 By Bergman. By Wenzel. 
 
 1* ccipitateJ by 
 
 C H E M I S T R y. 577 
 
 Quantity of lofs by driving off the gas by folution Acetitcs. 
 according to Weiizel : ' » 
 
 Zinc, - . . . 
 Iron, .... 
 
 Cobalt, 
 Lead, 
 
 Carbonat of 
 -alumina. 
 
 * Bergman ^ 
 
 i. «z. 
 
 776 
 Mctillic 
 carbonats. 
 
 + Bergm.in, 
 '•33' 
 
 t UIJ. 
 
 Carb. of So !a. 
 100 parts of ^y'eiJ;h^. 
 
 Oxide of zinc, ... 160,930 
 
 iron, - - 100,250 
 
 manganefe, - 100,800 
 
 cobalt, - - 100,600 
 
 nickel, - - 100,350 
 
 lead, - - - 100,320 
 
 tin, - - . 100,310 
 
 copper, - . 100,940 
 
 bifmuth, - 100,300 
 
 antimony, - 100,400 
 
 mercury, . 1 00, 1 00 
 
 filver, - - 100,290 
 
 gold, - - - 100,060 
 SVPPL. VoL.I. Part I, 
 
 Carb. of Po'afs. 
 
 Weight. 
 
 100,774 
 
 100,863 
 
 100,304 
 100,345 
 100,884 
 100,224 
 100,395 
 100,062 
 100,288 
 
 ioo,3j6 
 
 Tin, 
 
 Copper, 
 
 Bifmuth, 
 
 Antimony, 
 
 Mercury, 
 
 Silver, 
 
 Gold, 
 
 0,137 
 0,009 
 
 0,3 >2 
 0,157 
 
 0,000 
 
 0,174 
 
 0,056 
 
 0,000 ■ 
 
 0,038 
 
 0,158 
 
 0,144 
 
 rn 
 
 Thefe determinations differ too widely from each 
 other to be exact. It is obvious that part of the weight 
 mull be owing to adhering water, and very probably 
 triple falts are formed, which mud render the determi- 
 nation ftill more erroneous. 
 
 Sect. XI. Of Acetites. 
 
 The compounds which the acetous acid forms are 
 called acetites, 
 
 I. Acetite of potafs. Pliny is fuppofed, but pro- Acet'it'e of 
 bably without any reafon, to have been acquainted withl'o'afe. 
 this fait, becaufe he recommends a mixture of vinegar 
 and vine afhes as a cure for a particular fpecies of tu- 
 mor*. It was firlt clearly defcribed by Raymond Lully. * P/.m/.I, 
 It has received a great number of names ; as, for in- >""''• ^'■''■- 
 ftance, arcanum lartari, fecret foliated earth of tartar, ef.""'""' 
 fentlal fait of ■wine, regenerated tartar, diuretic fait, digef- 
 ti-ve fait of Sylvius. 
 
 Its cryftals are very white, and affume the form of 
 thin plates. 
 
 It has a ftiarp warm taile. 
 
 It is foluble in about ten times its weight of water at 
 the temperature of 6o°f . It is foluble alfo in alcohol, f Bergman, 
 
 According to Wenzel, 240 parts of acetous acid re-"- ?"• 
 quire for faturation 24liths of potafs. And from the 
 experiments of Dr Higgins, it appears that acetite of 
 potafs is compofed of 6j,5 parts of alkali and 38,5 of 
 acetous acid and water J. ) o„ Autout 
 
 When expofed to the air it is very deliquefcent. — AdJ,f.i. 
 When heated, it melts as readily as wax ; and if a very 
 ftrong heat be applied, the acid is decompofed. 
 
 The following falts decompofe it by compound affi. 
 nity : 
 
 Nitrat of ammonia, 
 ■ — magnefia, 
 
 alumina, 
 
 bifmuth. 
 
 Sulphat of foda, 
 lime, 
 ammonia, 
 magnefia, 
 alumina, 
 
 Nitrat of foda, 
 lime. 
 
 mercury, 
 
 Muriat of ammonia, 
 alumina. 
 
 -78 
 
 2. Acetite of foda. This fait was firft: defcribed by Acetite of 
 Mr Baron. '<"*»• 
 
 Its cryftals are ftriated prifms, not unlike thofe of 
 fulphat of foda. 
 
 It has a fharp tafte, approaching to bitter. 
 
 It is foluble in 2,86 parts of water at the tempera- 
 ture of 60" f. ^Bergman, 
 
 According to Wenzel, 440 parts of acetous acid re-'*"'- 
 quire for faturation i57^ths of foda. 
 
 It is not affeAed by cxpofure to the air. 
 
 When hea;ed, it firft lofes its water of cryftallization; 
 3 B in
 
 378 
 
 Acetites. 
 
 179 
 
 Acttitc of 
 
 • M,r:. 
 I'ur.i.-j-jS 
 
 •^ nr(rpin.t 
 o« AccUus 
 yUi.l, p. 
 I88. 
 
 ibji, p. 192. 
 
 5 7i5;</. 
 
 II iX/i. 
 
 U 7ijV. p. 
 
 J93- 
 
 7 So 
 Acetitq of 
 barytcs. 
 
 £ncyc. Mf- 
 il'od. Chin, 
 1.8. 
 
 C H E M 
 
 in a ftrong heat it melts; and in a (lill ftrongcr, its acid 
 is deilroyed. Tills lalt can only be obtained in cry- 
 Itals when there is an cxcefs of a! k ah' in the foluilon. 
 
 The following falls decompofe it by compound affi- 
 nity ; 
 
 Sulphat of ammonia, NItiat of alumina, 
 
 alumina, Muriat of lime, 
 
 Nitrat of ammonia, ammonia, 
 
 magneua, magncfia. 
 
 ?. Acetite of ammonia. This fait was formerly call- 
 ed /j>irit of MiniJtrerus. 
 
 It is too volatile to be eafilv cryftallized : It may, 
 however, by gentle evaporation, be made to depofite 
 iieedle-fhapcd cryftals. Mr de LafTone cryftallized it 
 by fuWimatiou *. When the fubllmation is (low, it 
 forms long, (lender, flatted cryftals, terminating in (liarp 
 points, of a pearl white colour, and about an inch and 
 eight-tenths In length f. 
 
 It imprelTcs the tongue at firft with a fenfe of cold- 
 nefs, and then of fweetnefs, which is followed by a tafte 
 rtfembling that of a mixture of fugar and nitre, in 
 which the fweet does not predominate over the maw- 
 kilh tafte of the nitre J. 
 
 According to Wenzel, 240 parts of acetous acid fa- 
 turate 244 of ammonia. 
 
 It is very deliqucfcent. It melts at 170°, and fu- 
 blimes at about 2^0" §. 
 
 When a watery folution of this fait is diftilled, there 
 comes over firft a quantity of am.monia, next a quantity 
 of acetous acid, and at laft of the neutral fait itfclf. No 
 fuch decompofition takes place when the cryftals are 
 diftilled by a moderate heat ||. 
 
 The following falts decompofe acetite of ammonia 
 by compound af&nity : 
 
 Sulphat of alumina, Carbonat of foda, 
 
 Carbonat of potafs, Nitrat of filver ^. 
 
 4. Acetite of barytes. This fait was firft formed by 
 Mr Morveau. 
 
 It is not eafily cryftallized. Morveau procured it 
 in long prifms in groups. 
 
 It has a pleai'ant, fomewhat acid tafte, and always 
 contains an excefs of acid. 
 
 It is foluble in water, and does not deliquefce when 
 expofed to the air *. 
 
 The following falts decOmpofe it by compound affi- 
 nity : 
 
 I S T R Y. Part III. 
 
 According to Wenzel, 240 parts of acetous acid re- Aceiites. 
 quire for laturation 125 of lime : according to Maret, ^^~v— ' 
 100 parts of acetite of lime contain 50 of lime *. From « En.-yc 
 tne experiments of Dr Higgins, it follows, that ace- MrthoJ. 
 tite of lime is compofed of 35,7 parts of lime and 64,3 "^""- '• S- 
 of acetous acid and water j-. f On Acciout 
 
 It is not altered by expofure to the air; at leaft ^"''. P- 47. 
 Morveau kept fome of it for a whole year merely co- 
 vered with paper, and even quite uncovered for a month, 
 without its undergoing any alteration |. \ Ibid. En. 
 
 Heat dccompofes it, and at the fume time partly de-0'- Mc- 
 compofcs its acid. '* • 
 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Muriat of alumina, 
 Carbonat of barytes, 
 potafs. 
 
 Sulphat of potafs, 
 foda, 
 
 lime, 
 
 . ammonia, 
 
 magnelia, 
 
 alumina. 
 
 Nitrat of alumina, 
 Muriat of potafs, 
 
 loda, 
 
 lime, 
 
 ammonia, 
 
 maguefia, 
 
 alumina. 
 
 Carbonat of potafs, 
 
 foda, 
 
 ammonia. 
 
 1^1 
 Acciite of 
 Jinie. 
 
 + Plinii, I. 
 ixivi. c, a4- 
 
 Nitrat of potafs, 
 
 foda, 
 
 lime, 
 
 . . ammonia, 
 
 magnefia, 
 
 5. Acetite of lime. This fait was firft defcribed ac- 
 curately by CroUius. The ancients, however, ufed a 
 mixture of lime and vinegar in furgery f . 
 
 It cryftallizes in fine needles, of a glofly appearance 
 like falin. 
 
 Its tafte is bitter and four, becaufe it has an excefs 
 of acid. 
 
 It is foluble in water. 
 
 Sulphat of foda, 
 
 ammonia, 
 
 magnefia, 
 
 alumina. 
 
 Nitrat of ammonia, 
 
 magnefia, 
 
 alumina, 
 
 Muriat 6f ammonia, 
 6. Acetite of ftrontitcs. 
 
 foda, 
 ammonia, 
 magnefia, 
 alumina. 
 
 78i 
 
 This fait was firft formed Acetite oi 
 by Dr Hope. It forms fmall cryftals, which are not ^'°'"""- 
 affefted by expofure to the atmofphere. 49 parts of 
 it are foluble in 120 parts of boiling water : It feems 
 to be nearly as foluble in cold water. It renders vege- 
 table colours green ^. § ^^ Ko/f, 
 
 7. Acetite of magnefia. This fait was firft mention- -^^""-^ ^'''"'• 
 ed by Mr Wenzel. 1^3 
 
 It is not cryftallizable ; but forms by evaporation a Acetite of 
 vifcid mafsjl. magnefia. 
 
 It has a fweetifh tafte ; leaving, however, a fenfe of-; .'J?'"'"'' 
 bitternefs^f. _ ^ .W„mb, 
 
 It is very foluble both in water and alcohol *. ioiJ. 
 
 According to Wenzel, 240 parts of acetous acid re- * Brrgman, 
 quire for faturation 1 z^^Jths of magnelia. '' ^ ' 
 
 When expoied to the air, it deliquefces. Heat de- 
 compofcs it. 
 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Sulphat of ammonia, 
 
 alumina, 
 
 Nitrat of ammonia, 
 
 alumina, 
 
 Muriat of ammonia, 
 alumina. 
 
 Carbonat of barytes, 
 
 — — potafs, 
 
 foda, 
 
 ammonia, 
 
 alumina. 
 
 784 
 
 8. Acetite of alumina. This fait can only be form- Acetite ot 
 ed by digefting acetous acid on alumina recently preci-*'""""*" 
 pitated. 
 
 By evaporation needle-ftiaped cryftals are obtained, 
 which are very deliqucfcent. According to Wenzel, 
 240 parts of acetous acid Require 20-Tths of alumina for 
 faturation. 
 
 This fait is decompofed by compound affinity by the 
 following falls : 
 
 Nitrat of ammonia, Carbonat of potafs, 
 
 Muriat of ammonia, foda, 
 
 Carbonat of barytes, ammonia. ^j^ 
 
 g. Acetite of jargonia. This fait may be formed by Acetite of 
 pouring acetous acid on newly precipitated jargonia. J^irgonia. 
 It has an aftrlngent tafte. It does not cryftallize ; but 
 when evaporated to drynefs, it forms a powder, which | Khprott, 
 does not attraft moifture from the air as acetite of alu-Jo^irn.at 
 uiina does t. It is very foluble in water and in alco- ^''yf- xxx»i 
 
 hol.'8^-
 
 Part III 
 
 Acetires. 
 
 Aceiite of 
 zinc. 
 
 C H E M I 
 
 liol. It is not fo ciifily dtcompofed by heat as nitrat 
 of jaigonia, probably becaufe it dots not adhere fo 
 ftrongly to water *. 
 
 10. Acctitc of iron. — This fait was mentioned by 
 Schroedcr and Juntkcr. It is coinpofed ol acetous acid 
 and brown oxide of iron. 
 
 Its folution forms by gentle evaporation fmall oblong 
 cryttals ; but the greattit part of the fait affumes the 
 ■f Wtnzel. form of a gelatinous mafs f. 
 
 It has a fweetifh ftyptic taile. 
 
 According to Werzel, ^^o parts of acetous acid re- 
 quire for faturation l86i of iron. 
 
 Heat decompofes this fait ; and it feems alfo to be 
 gradually deconipof>:d by expofure to the air. 
 
 11. Acetite of zinc. — This fait was firft mentioned 
 by Glauber. 
 
 Its cryllals are rhomboidal, and fometimes hexagonal 
 plates, of a white colour, and the appearance ot talk. 
 
 It is foluble in water. According to VVenzel, 240 
 parts of acetous acid require for faturation I95yths of 
 zinc. 
 
 It is not altered by expofure to the air. Heat de- 
 compofes it. When thrown upon burning coals, it ex- 
 plodes with a blue flame. 
 
 12. Acetite of manganefe. — This fait is not cryftal- 
 lizable ; and when evaporated to drynefs, it deliquefccs. 
 Is it not an acetat ? 
 
 1 3. Acetite of cobalt. — This fult is deliquefcent. Its 
 folution is of a fine red colour while cold; but becomes 
 blue by being heated, and it recovers its former colour 
 on cooling. According to Wenzel, 240 parts of ace- 
 tous acid require for faturation 24iyths of cobalt. 
 
 14. Acetite of nickel. — ['his fait forms rhomboidal 
 cubes of a green colour J : They are not deliquefcent : 
 Their tafte is fweet §. 
 
 I ?. Acetite of lead. — This fait is mentioned by Ifaac 
 
 S T R Y. 
 
 379 
 
 788 
 
 Acetite of 
 cobalt. 
 
 7S9 
 Acetite of 
 nickle. 
 J Bergmtin. 
 § Mound. 
 
 790 
 
 Acente of Hollandus and Raymond Lully. It is compofed of 
 lead. acetous acid and white oxide of lead. 
 
 It was formerly called fugar of lead, fugar of Saturn, 
 fait of Saturn, -vinegar of Saturn, extraH of Saturn, &c. 
 
 Its cryitals are flat parallelopipeds, terminated by 
 two inclined planes approaching each other. 
 
 It has a fweet and fomewhat allringent tafte. 
 
 It is not very foluble in water ; but acetous acid dif- 
 folvcs it abundantly. 
 
 According to Wenzel, 240 parts of acetous acid re- 
 quire for faturation 503 of lead. 
 
 When expofed to the air it becomes yellow, but un- 
 dergoes no other alteration. 
 
 Heat decompofes it by deftroying the acid. When 
 riiftilled, the refidutim takes tire fpontaneoufly on expo- 
 fure to the air. Paper dipped into acetite of lead forms 
 excellent matches, which are not fubjtft to go out, and 
 which bum very flowly. 
 
 The following falts decompofe it by compound affi- 
 nity : 
 
 Muriat of ammonia, Phofphat of ammonia, 
 
 Sulphat of copper, Oxalat of potafs {{, 
 
 Phofphat of fdda, Malat of potals ^. 
 
 16. Acetite of tin. — This fait was firlt dcfcrihed by 
 Lemery. 
 
 Its cryftals are prifmatic needles in groups *. Ac- 
 cording to Wenzel, 240 parts of acetous acid require 
 for faturation j-jV o^ tin. 
 
 791 
 Acetite of 
 tin. 
 
 17. Acetite of copper Thib fait was known to the Acetite. 
 
 ancients, and various ways of preparing it are defcribed * 
 
 by Pliny *. It was formerly known by the names of,\„ti,jof 
 crji^/ials of Venus and verdigrife. copper. 
 
 It is of a deep green colour. Its cryftals are rhom- *Lib.xxxiv. 
 boids. '• "• 
 
 It has a difagreeable coppery tafte. 
 
 It is foluble in water and in alcohol. 
 
 According to Wenzel, 240 parts of acetous acid re- 
 quire i6-|rth of copper ior faturation. 
 
 It efflorefces when expoled to the air. Heat de- 
 compofes it. It is ufcd in painting. 753 
 
 18. Acetite of bifmuth. — This fait feems to have been Acetite of 
 firft mentioned by Geoffroi. He called 'il fugar ofl/fmuth.^''^'^^'''-^- 
 
 It is moll eafily procured by mixing together the fo- 
 lutions of nitrat of bilmuth and acetite ot potaf?. It 
 forms brilliant, talky, filvery cryftals. 
 
 It has a fweetifti tafte. According to Wenzel, 240 
 parts of acetous acid require for faturation ij^-ths of 
 bifmuth. 
 
 It does not deliquefce when expofed to the air. Heat 
 decompofes it. 79+ 
 
 19. Acetite of antimony. — It yields with difficulty '^'-"•'"^ °^ 
 fmall cryftals f . According to Wenzel, 240 parts of, rr"",/' 
 acetous acid require for faturation i |d of antimony. -^^ 
 
 20- Acetite of arfcnic. — This fait forms fmall cry-Acetite of 
 ftals in grains, hardly foluble in water J. arlenic. 
 
 21. Acetite of mercury. — This fait is mentioned by jnh"'"' 
 Schroeder. Acotitc of 
 
 Its cryftals are fmall thin plates. mercury. 
 
 It has a difagreeable tafte, and excites coughing. 
 
 It is hardly foluble in water. According to Wen- 
 zel, 240 parts of acetous acid require for faturation 
 240-Tths of mercury. 
 
 When expofed to the air it becomes black, owing tt> 
 the reduction of the oxide of mercury. Heat decom- 
 pofes it. 797 
 
 2 2 Acetite of filver. — This fait was perhaps firft ^""''"^ 
 defcribed by Margraf. 
 
 It is beft formed by dropping acetite of foda or pot- 
 afs into a faturated folution of nitrat of fdver ^. 5 Mant, 
 
 It forms fmall oblong cryftals, eafily diffolved in wa-""'^- 
 tcr f . It has a (harp tafte. f Margtaf. 
 
 According to Wenzel, 240 parts of acetous acid re- 
 quire for faturation loi^ths of filver. 
 
 Heat decompofes it. It is decompofed by muriat of 
 magnefia ^. f Ber^man^ 
 
 23. Acetite of gold. — This fait is mentioned by 79^ 
 Sehroeder and Juncker. '^""'^ "^ 
 
 24. Acetite of uranium. — This fait was firft formed -nn 
 by Klaproth. Acititc of 
 
 Its cryftals are regul.ir four-fided flender prifms, ter.""'""™- v 
 minated at both ends by regular quadrilateral pyramids: 
 they are tranfparent, and of a beautiful topaz yellow 
 colour. 
 
 Heat decompofes them : and what is Angular, if they 
 be heated gradually red hot, the oxide which remains 
 retains nearly the form of the cryftals *. * '^''•'^''f-'* 
 
 The compounds into which the acetic acid enters are"" ''^'"""• 
 railed rt(-<7(//^. They are fo imperfcilly known at pre- .^g^^^j^s. 
 fent, that we fliall not attempt a defcriptlon of them. 
 
 Sect. XII. Of 0:<alats. 
 
 The compounds of which oxalic acid forms a part 
 3 B 2 are
 
 8oi 
 Oxalat of 
 potafs 
 * Bergman f 
 i. 262. 
 
 Sol 
 Acidulous 
 oxalat of 
 )<otafs. 
 
 t Vi Lifli. 
 
 803 
 Oxaiat of 
 foda. 
 
 S04 
 
 Oxalat of 
 ammonia. 
 
 ^ Bergman, 
 
 ^ Bergman t 
 Hid. 
 
 805 
 Earthy ox- 
 alats. 
 
 II Bergman, 
 ibid. 
 
 ^ Bergman^ 
 ibid. 
 
 * Hope, 
 Tranf. Edin, 
 iv. 14. 
 
 f Bergman y 
 ibid, and ii. 
 3«7. 
 
 C H E M I 
 
 are known by the name of oxa/ah. They were firft 
 defcribed by Bergman. 
 
 1. 0:talat of potafs. — This fait cryftalli7.es with dif- 
 ficulty. It is very foluble in water. When heated it 
 falls to powder *. 
 
 2. Acidulous oxalat of potafs. — The oxali'e acid is 
 alfo capable of combining witli potafs in excefs, and 
 forming another fait, called acidulous oxalat from its acid 
 tafte ; or, to fpeak. more accurately, this fait is formed 
 by the combination of oxalat of potafs with oxalic acid. 
 This fait exills ready formed in o.-<alis acetoftlla or wood- 
 forrcl ; from which it is extradled in fome parts of Eu- 
 rope in great quantities. Hence it was formerly called 
 fait of wood forrel. It is mentioned by Duclos in the 
 Memoirs of the French Academy for 1668. Margraf 
 firft proved that it contained potafs ; and Schcele dif- 
 covered that its acid is the oxalic. A great many in- 
 terefting experiments had been previoufly made on it by 
 Wenzel and Wiegleb. 
 
 It may be forined, as Schcele has (liown, by drop- 
 ping potafs very gradually into a faturated folutlon of 
 oxalic acid and water : as foon as the proper quanticy of 
 alkali is added, acidulous oxalat is precipitated. But 
 care muft be taken not to add too much alkali, otherwife 
 no precipitation will take place at all. 
 
 Its cryftals are fmall opaque parailelopipeds f. 
 
 It has an acid, poignant, bitterifh tafte. 
 
 It is foluble in about ten times its weight of boiling 
 water, but much lefs foluble in cold water. 
 
 It is not altered by expofure to the air. Heat de- 
 compofes it. 
 
 This fait is fold in this country under the name of 
 ejfential fait of lemons. 
 
 3. Oxalat of foda. — This fait agrees very much with 
 oxalat of potafs. Its cryftals are fmall, and foluble in 
 water. 
 
 From Bergman's defcription, oxalic acid appears alfo 
 capable of combining in excefs with foda, and forming 
 an acidulous oxalat. 
 
 4. Oxalat of ammonia. — Its cryftals are four-fided 
 prifms, generally diverging from various points. They 
 redden the infufion of turnfole. 
 
 They arc eafdy foluble in water, but not in alcohol J. 
 It is decompofed by nitrat of barytes §. 
 
 5. Oxalat of barytes. — This fait docs not cryftallize 
 except with excefs ot acid. The addition of potafs, or 
 even of water, deprives it of this excefs, and then it 
 crumbles into powder. It is in foluble in water ||. 
 
 6. Oxalat of lime. — This fait does not cryftallize. 
 It is iufoluble in water, but fomcwhat foluble in acids. 
 It is compofed of 48 parts of acid, 46 of lime, and 6 of 
 water. Heat decompofes it ^. 
 
 7. Oxalat of ftrontites. — This fait was firft formed 
 by Dr Hope. It is a white infipid powder; foluble 
 in 1920 parts of boiling water. Heat decompofes it 
 by deftroying the acid *. 
 
 8. Oxalat of magnefia. — This fait is in the form of 
 a white powder. It is fcarccly foluble either in water 
 or alcohol. It is compofed of 35 parts of magnefia 
 and 65 of acid and water. Heat decompofes it ■]-. 
 
 9. Oxalat of alumina. — It is uncryftallizable ; but 
 furnifties on evaporation a yellowifh pellucid mafs. It 
 is fparingly foluble in alcohol. It has a fweet allrin- 
 gent tafte. It is compofed of 44 parts of alumina and 
 56 of acid and water. 
 
 S T R Y. 
 
 Part III. 
 
 When expofed to the air it deliquefces ; and if it has OxaUts. 
 been previoufly well dried, its weiglit is increafed by \. ^~ 
 
 It reddens turnfole *. 
 
 * Per: 
 
 ■gman, 
 
 \ Ibid. 
 
 Hid. 
 
 10. Oxalat of iron. — This fait forms prifmatic cry-'*"^- 
 
 ftals of a yellowifh "jreen colour. ., ,,. 
 
 n • Metallic 
 
 It has an aftrmgent and fweet tafte. It is very fo-oxalats. 
 
 luble in water. 
 
 It is compofed of 45 parts of green oxide, and 55 of 
 acid and water. When expofed to heat it falls to pow- 
 der f- _ i UiJ. 
 
 From Bergman's defcription, the brown oxide of 
 iron appears alfo capable of combining with oxalic acid. 
 The compound does not cryftallize, and is nearly info- 
 luble in water J. 
 
 1 1. Oxalat of zinc. — It is hardly foluble in water, 
 It is compofed of 75 parts of oxide and 25 of acid. 
 
 12. Oxalat of manganefe. — It is compofed of oxalic 
 acid and white oxide of manganefe. It appears capable 
 ofcryftallizingj. _ _ 5 ;;;^_ 
 
 13. Oxalat of cobalt. — This is a rofe-coloured pow- 
 der, infohible in water, but foluble in oxalic acid ; and 
 capable, by that means, of cryft;dlizing ||. 
 
 1 4. Oxalat of nickel. — This is a green coloured pow- 
 der, hardly foluble in water. It is compofed of two 
 parts of acid and one of oxide "[J. « /^ 
 
 15. Oxalat of lead. — It forms fmall cryftalline grains. 
 They are infoluble in alcohol, and nearly infoluble in 
 water. They contain ^5 parts of oxide and 45 of acid *. * /i;j^ 
 
 16. Oxalat of tin. — This fait forms prifmatic cryftals. 
 It has an auftere tafte. If the folution of this fait be 
 quickly evaporated, it affords a mafs refembling horn, 
 
 and foluble in water -f. | Ji;j, 
 
 17. Oxalat of copper. — This fait is uncryftallizable. 
 It is a bluifti powder, infoluble in water, except with 
 excefs of acid. It is compofed of 21 parts of copper 
 
 and 29 of acid J. j /nj. 
 
 18. Oxalat of bifmuth. — This fait may be formed by 
 dropping oxalic acid into a folution ot nitrat of bif- 
 muth. It forms pellucid polygonous cryftals. When 
 oxide of bifmuth is diffolved by oxalic acid, the refult is 
 
 a white powder, fcarccly foluble in water ^. r ^^y 
 
 ig. Oxalat of antimony. — This fait forms cryftalline 
 grains, with difficulty foluble in water f . f IHJ. 
 
 20. Oxalat of arfenic. — This fait is compofed of oxalic 
 acid and white oxide of arfenic. Its cryftals are prifms 
 very foluble in water and alcohol. It reddens turnfole. 
 
 Heat fublimes it ; and by a ftrong heat it may be de- 
 compofed ^. ^ jiij, 
 
 21. Oxalat of mercury. — A white powder, hardly 
 foluble in water, except with excefs of acid *. « juj, 
 
 27. Oxalat of filver. — This fait may be formed by 
 pouring oxalic acid into a folution of nitrat of filver. 
 It is a white powder, fcarcely foluble in water, and not 
 at all in alcohol ; but foluble in nitric acid. It becomes 
 black by being expofed to the air, owing to the reduc- 
 tion of the oxide -f-. \ Jbid. 
 
 23. Oxalat of platinum. — This fait affords yellow 
 cryftals. 
 
 Sect. XIII. Of Tartrltes. 
 
 The fatts into which tartarous acid enters as an in-- 
 gredient are known by the name of tartritcs. S07 
 
 I. Acidulous oxalat of potafs or tartar. — This fait, Tartar, 
 which is compofed of petals and an excefs of tartarous 
 acid, or rather of tartrite of potafs and tartarous acid, 
 
 has
 
 Part in. 
 
 CHEMISTRY. 
 
 381 
 
 « Jfcnsil. 
 
 808 
 Tartrite of 
 foiafs. 
 
 809 
 Tartrite of 
 poCafs and 
 ioda. 
 
 Tartrites. has been long known. It is obtained in a ftate of im- 
 ^-~-y~~' purity at the bottom, and adhering to the fides of caflcs 
 in which wine has fermented. It is called tartar, fays 
 Paracelfus, hecaufe it produces the oil, water, limellone, 
 and fait, which burn the patient as HJl does. Accord- 
 ing to him, it was the principle of every difeafe and 
 every remedy, and all things contain the germ of it. 
 
 Margraf and Rouelle firll demon{lrate<l that it con- 
 tained potafs ready formed : and Scheele firll obtained 
 tartarous acid from it in a ttate of purity. 
 
 Its cryftals are very fmall and irregular. According 
 to Muntct, they ai-e prifms, fomewhat flat, and mollly 
 with fix fides. It has a itrong acid tafte. It is foluble 
 in about 30 times its weight of boiling water*. Ac- 
 cording to Bergman, it contains 23 parts of alkali and 
 77 of acid. 
 
 It is not altered by expofure to the air. Heat de- 
 compofes it, and at the fame time deftroys the acid. It 
 is capable of forming a great many compounds. 
 
 2. Tartrite of potafs. This fait may be formed by 
 faturating the laft defcribed fait with petals. It was 
 formerly called folttbls tartar, becaufe it is much more 
 folnble in water than the acidulous tartrite of potafs. 
 It cryftallizes moll readily when there is a fmall excefs 
 of alkali in the folution. Its cryftals are fmall oblongs. 
 
 It has an unpleafant bitter taile. It is foluble in 4 
 parts of water at the temperature of 40°. 
 
 3. Tartrite of foda. This fait has never been accu- 
 rately examined. 
 
 4. Tartrite of potafs and foda. This triple fait, for- 
 merly known by the name oi fall of Selgiiette, hecaufe 
 firft formed by Mr Seignette apothecary at Rochelle, is 
 made by faturating tartar with foda. 
 
 Its cryftals are prifms of eight or ten unequal fides, 
 having their ends truncated at right angles. They are 
 generally divided into two in the direftion of their axes, 
 and the bafe on which they ftand is marked with two 
 diagonal lines, fo as to divide it into four triangles. 
 
 It has a bitter tafte. It is almoft as foluble as tar- 
 trite of potafs. 
 
 It efflorefces when expnfed to the air. Heat decom- 
 pofes it. 
 
 4. Tartrite of ammonia. The cryftals of this fait are 
 polygonous prifms, not unlike thofe of the lalt defcribed 
 fait. 
 
 It has a cooling bitter tafte like that of nitre. It is 
 eafily foluble in water. Heat decompofes it. 
 
 5. Acidulous tartrite of ammonia. This fait may 
 be formed by pouring tartarous acid into a folution of 
 tartrite of ammonia. Like acidulous tai trite of potafs 
 it is very infoluble in water. 
 
 6. Tartrite of potafs and ammonia. This triple fait 
 may be formed by pouring ammonia into acidulous tar- 
 trite of potafs. 
 
 Its cryftals, according to Macquer, are prifms with 
 four, five, or fix fides; according to the Dijon academi- 
 cians, parallelopipeds, with two alternate floping fides. 
 
 It has a cooling tafte. It is foluble enough in water. 
 It efflorefces in the air. Heat decompofes it. 
 
 7. Tartrite of barytes. Unknown. 
 . 8. Tartrite of lime. This fait, firft formed by Scheele, 
 
 is a taftelefs and almoft infoluble powder. By heat the 
 acid is decompofed, and the pure lime remains behind. 
 9. Tartrite of ftrontites. This fait was firft formed 
 
 810 
 Tartrite of 
 ammonia. 
 
 811 
 Earthy tar. 
 trices. 
 
 ken at Sate 
 
 This fait does not eryflal-^'" " "" 
 
 by Dr Hope. Itj cryftnls are fmall regular triangular Tartntu 
 tables, having the edges and angles Iharp and well de- * 
 fined. It is infipid. It diflblves in 320 parts of boil- 
 ing water. 
 
 It is not altered by expofure to the air. Heat de- 
 compofes it by deftroying the acid *. * Hofe, 
 
 10. Tartrite of magncfia. This fait is infoluble in ^''"•■'^ '"•'•/• 
 water except there be an excefs of acid prefent. It tiien 
 atfords by evaporation Imall cryftals in the form ot hex- 
 angular truncated prifms f. f Btrgman, 
 
 It has a more faline tafte, and is more fufible, than''- '^83. 
 tartrite of lime J. i ^on Pac. 
 
 Heat firll melts and afterwards decompofes it. 
 
 1 I. Tartrite of alumina, 
 lize, but forms by evaporation a clear tranfparent gum- 
 my mafs. Its tafte is aftringent. It is foluble in wa- 
 ter. It does not deliquefce in the air J. J f'on Pac- 
 
 12. Tartrite of potafs and alumina. This triple fait*'"- 
 is formed by faturating tartar with alumina. It bears 
 
 a very llriking refemblance to the laft defcribed fait. „ 
 
 13. Tartrite of iron. This is a grey powder. When Metallic 
 tartarous acid is poured into a folution of fulphat ofiartrites, 
 iron, fcaly cryftals are formed by evaporation. Thcfe 
 cryftals are doubtlefs compofed of tartarous acid com- 
 bined with fulpliat of iron. This triple fait might be 
 called tartrofulpbat of iron. 
 
 14. Tartrite of potafs and iron. This triple fait was 
 formerly called tarturifed tincture of Mars, chalylealed 
 tartar, and tartarifed iron. It may be formed by boil- 
 ing two parts of tartar and one of iron filings, previouf- 
 ly made up into a pafte, in a proper quantity of water. 
 The liquor by evaporation depofites cryftals, which form 
 the fait wanted. 
 
 15. Tartrite of zinc. This fait is not eafily foluble 
 in water. 
 
 16. Tartrite of potafs and zinc. This triple fait, 
 formed by combining tartar and oxide of zinc, is very 
 foluble in water II . ^ Etcmira. 
 
 17. Tartrite of lead. This fait, which is compofedp^"'"- 
 of tartarous acid and white oxide of lead, is almoft info- 
 luble in water. Nitric acid diffolves it. 
 
 18. Tartrite of potafs and lead. This fait, formed 
 by combining white oxide of lead with tartar, is very 
 foluble in water «. ^ ^f ">«''. 
 
 19. Tartrite or tin. Unknown. The tartrite of pot- 
 afs and tin, compofed of tartar and oxide of tin, is ca- 
 pable of cryllallizing. 
 
 20. Tartrite of copper. This fait is beft formed by 
 pouring tartarous acid into the folutions of muriat or 
 fulph.at of copper ; it precipitates in the form of blue 
 cryftals *. * Birgman. 
 
 This fait forms the beft kind of the pigment called 
 Bnwfivick grem\. t Limhardi, 
 
 21. Tartrite of potafs and copper. This triple fait 
 is alfo in the form of blue cryftals. 
 
 2 2. Tartrite of bifmuth. Small cryftalline grains J. ^ ^'rgnan, 
 
 23. Tartrite of antimony. This fait has never been 
 examined with attention. 
 
 24. Tartrite of potafs and antimony, or tartar emetic. 
 To this fait, which is perhaps the moft powerful emetic 
 known, a great deal of attention has been paid, and a 
 vaft number of methods have been tried to prepare it. 
 Thefe methods have been already defcribed in the En. 
 cyclopsedia. It appears from the experiments of Mr 
 
 Biadhein),.
 
 Chim 
 
 382 C H E M I 
 
 Bi:idhciin, tl.at if this fait he carefully prepared, the 
 difference that refults from the ufe oi different pKides ia 
 • Ann.Jt not l"o jrreat as no'ght have heen expected *. 
 
 It was lirll made known by Adrian in 1631. It is 
 a triple fait, compofed of tartar and white oxide of an- 
 timony. 
 
 It is of a while colour and tranfparent. Its cryftals 
 are trihedral pyramids. 
 
 It diflolvcs in (o parts of cold water, and in a fmaller 
 proportion of hot water. It is decompofed by lime - 
 and alkalies, iron, &c. Care ought therefore to be taken 
 to ufe only diftilled water when it is adminiftered as a 
 medicine. 
 
 25. Tartrite of arfenic. This fait forms prifmatic 
 f Brrgman, cryftals very like tliofe of oxalat of aricnicf. 
 »'• =i'i- 26. Tartrite of mercury. A yellow powder. 
 
 27. Tartrite of potafs and mercury. This triple fait 
 } Moitnei. cryftallizes J. 
 
 Sect. XTV. 0/ Citrats. 
 
 The compounds into which the citric acid enters 
 have been denominated citrats. 
 
 Thefe falts are at prefent very imperfeftly known. 
 Mr Dize has promifed foon to fupply this defeft J. 
 
 1. Citrat of potafs. This fait does not cryftallize. 
 It has a cooling faline tafte, and deliquefces when ex- 
 pofcd to the air. 
 
 2. Citrat of foda. This fait does not deliquefce. It 
 has a mild, pleafant, cooling tafte I|. According to 
 Scheele, it does not ci7ftallize. 
 
 3. Citrat of ammonia. This fait cryftallizes ia thin 
 needles. It has a cooling and moderately faline tafte ^. 
 The ammonia is feparated by the application of heat*. 
 
 4. Citrat of barytes. This fait is fcarcely foluble in 
 water. It afl'umes the form of a white powder f . It 
 is foluble in citric acid. 
 
 5. Citrat of lime. This is a white powder, fcarcely 
 foluble in water J. 
 
 6. Citrat of magnefia. Does not cryftallize. It 
 forms a gummy fahne mafs very foluble in water §. 
 
 7. Citrat of alumina. This fait is fcarcely foluble in 
 water, 
 
 8. Citrat of iron. A folution of a brown colour. 
 
 9. Citrat of copper. A green gummy mafs. 
 
 10. Citrat of mercury. This fait may be formed 
 by pouring citric acid into nitrat or acetite of mercury. 
 It is a flaky fait, of a brickduft colour, more or lefs 
 red 11. 
 
 Sect. XV. Of Malati. 
 
 The compounds into which the malic acid enters 
 are called malats. This clafs of falts was firft difcover- 
 cd by Scheele. They are no better known than the ci- 
 trats. 
 
 1. Malat of potafs. T 
 
 2. Malat of foda. J- Thefe falts are deliquefccnt^. 
 5. Malat of ammonia. J 
 4. Malat of lime. Small irregular cryftals. _ They 
 
 require a large quantity of boiling water for their folu- 
 tion. Wiih excefs of acid they are readily foluble in 
 cold water |. They are infoluble in alcohol J. 
 
 1 Id 5- Malat of barytes. The properties of this fait re- 
 
 fcmble pretty much thofe of malat of lime §. 
 
 ''''■ 6. Malat of magntfia. Dtliquefcent H- 
 
 S T R Y. 
 
 Part III. 
 
 ^ "Journ. dt 
 
 J'hf- ' -94, 
 
 Alkaline 
 citrats. 
 II D, Do- 
 nald Monro, 
 Phil. Irarf. 
 
 SI- 
 
 t Dob/on. 
 
 814 
 Earthy ci- 
 •«ra's. 
 
 \u 
 \IJ. 
 
 J u. 
 
 8>S 
 Metallic 
 utrats. 
 
 I Vi: 
 
 816 
 
 Malat!:. 
 
 zable 
 
 Malat of iron. A brown folution, not ei7ftalli- LaflatJ. 
 
 8. Malat of zinc. This fait forms beautiful cryftalsf. * fj"'''' 
 
 Sect. XVI. Of LaSuts. 
 
 817 
 
 The neutral falts formed by the combination of the Ladtats. 
 laftic acid with various bafes are called Liciats. They 
 were firft; difcovered by Scheele. 
 
 1. I.idat of potafs. A deliquefcent fait, foluble in 
 
 alcohol J. I Srirclt on 
 
 2. Laflat of foda. This fait does not cryftallize. It ^'"• 
 is foluble in alcohol J. , ... , 
 
 3. Laftat ef ammonia. Cryftals which deliquefce. 
 Heat feparates a great part of the ammonia before de- 
 ftroying the acid. 
 
 4. Laaat of barytes. T Thefe falts deliquefce ||. The 1| UiJ. 
 
 5. Laftat of lime. |> laftat of lime is foluble in al- 
 
 6. Laftat of alumina, j cohol 5[. ^ Ibid, 
 
 7. Laftat of magnefia. Small deliquefcent cryftals*. ^ ,,.. 
 
 8. Laftat of iron. A brown folution. 
 
 9. Laftat of zinc. Cryftals f. \ Ibii. 
 Thefe falts have a very ftrong refemblance to malats. 
 
 The only difference which Scheele obferved was, that 
 the malat of lime was infoluble in alcohol, while alcohol 
 diflblved laftat of lime. 
 
 Sect. XVII. Of Saccholais. 
 
 818 
 The compounds into which the faccholaftic acid en- saccholats. 
 
 ters are csWeA facikolats. They alfo were firft difcover- 
 
 ed by Scheele. 
 
 1. Saccholat of potafs. Small cryftals, foluble in 
 
 eight times their weight of boiling water J. j '^chtrl! on 
 
 2. Saccholat of foda. The fame ; foluble in five Sugar of 
 times their weight of boiling water J. Milt. 
 
 3. Saccholat of ammonia. A fait which has a fourifh ? ""'• 
 tafte. Heat feparates the ammonia ^. ^ Ibid. 
 
 4. Saccholat of barytes. "J 
 
 5. Saccholat of lime. (Thefe falts are infoluble 
 
 6. Saccholat of magnefia. fin water*. * liid. 
 
 7. Saccholat of alumina. J 
 
 Sect. XVIII. Of Gallats. 
 
 The compounds into which the gallic acid enters are q-u'? 
 denominated gallats. They were firft attended to by 
 the Dijon academicians and by Scheele. 
 
 1. Gallat of potafs. T We only know that thefe 
 
 2. Gallat of foda. > compofitions are poffible, 
 
 3. Gallat of animbnia. J ''"'^ 'hat their properties 
 are different from thofe of all other falts. 
 
 4. Gallat of barytes. 1 Thefe falts are foluble in wa- 
 ' J. Gallat of lime. J ter, cfpecially when there is 
 excefs of acid. 
 
 6. Gallat of magnefia. This fait is a yellow powder, 
 
 foluble in water and in alcohol *. * * Bartboldl 
 
 7. Gallat of alumina. This fait, according to Bar- yi„„. ji. 
 tholdi, exifts ready formed in nut galls. It is very fo- '.tim. xii. 
 luble in water. ^oi- 
 
 8. Gallat of iron. This fait, which Mr Prouft has 
 difcovered to be formed of gallic acid and brown oxide 
 of iron, is of a black colour, and does not ieem capable 
 of cryftallizing. It is foluble in the three mineral acids, 
 and by that means is deprived of its black colour. It 
 is to this fait that ink partly owes its black colour. 
 Gallat of iron is decompofed by alkalies. 
 
 We ftiall not attempt any farther account of this clafs 
 
 of
 
 Part III. C H E M 
 
 Benzoats. of fait s. Scarcely any adJItJon has yet been made to 
 ' — V ■ the experiinents of ticheele which have been given al- 
 ready in the article CunMiSTRV, Encyrl. 
 
 Sect. XIX. OJ Benxoals. 
 
 The compounds into which the benzoic acid enters 
 have been called len%oats. 
 
 1. Benzoat oF potafs. This fult forms pointed fea- 
 thery cryltals. It has a faline (hnrp taile. It is very fo- 
 luhle in water. It deliquefces when expoied to the air*. 
 
 2. Benzoat of foda. Tlie cryftals of this fait are lar- 
 ger, but its talle is the fame with that of benzoat of 
 potafs. It is alfo very fuluble in water. It cfflorefces 
 in the air f. 
 
 3. Benzoat of ammonia. This fait cryftallizes with 
 difficulty. Its cryftals are feather-fhaped. It deli- 
 quefcesj. 
 
 4 Benzoat of lime. This fait forms white, (hining, 
 pointed cryftals, of a fweetifti tafte, and not eafily fo- 
 
 I S T R Y. 
 
 .38-3 
 
 8ao 
 Alkaline 
 benzoacs. 
 
 
 i liia. 
 
 i UiJ. 
 
 Earth)' 
 bcn7iiits 
 § I.id. 
 
 luble in water ^. 
 
 5. Benzoat of magnefia. 
 
 Feather-fhaped cryftals, of 
 ■}■ Ibid. a fliarp bitter tafte, and eaiily foluble in water -|-. 
 
 Sii 6. Benzoat of alumina, an aftringent fait. 
 
 Metallire 7. Benzoat of iron. This fait forms yellow cryftals. 
 berjzoitf. \[ Jjaj a fvveet tafte. It is foluble in water and alcohol. 
 <[ Trcmmf- It efflorefccs in the air. Heat difengages the acid^. 
 Jf.', " ■ 8. Benzoat of zinc. This fait forms arborefcent cry- 
 ,, ' ftals. It is foluble in water and alcohol. When expo- 
 * IJ.iiid. fed to the air it is diffipated. Heat decompofes it*. 
 
 9. Benzoat of manganefe. This fait, which is form- 
 ed of benzoic acid and white oxide of manganefe, cry- 
 ftallizes in fmall fcales. It difTolves readily in water ; 
 with difficulty in alcohol. It is not altered by expofure 
 + IJ.aiJ. to the airf. 
 \ld.ibU. 10. Benzoat of cobalt. Flat cryftals J. 
 
 11. Benzoat of lead. Very white cryftals, foluble in 
 water and alcohol. They are not altered by expofure 
 
 § IJ.iiiJ. to the air. Heat difengages the acid j. 
 
 12. Benzoat of tin. This fait may be formed by 
 pouring ben/.oat of potais into a folution of tin in the 
 nitro-muriatic acid. The benzoat of tin is precipitated. 
 It is foluble in hot water, but infoluble in alcohol. Heat 
 
 D JJ. ihid. decompofes it ||. 
 
 13. Benzoat of copper. Small cryftals of a deep 
 green colour. They arc with difficulty foluble in wa- 
 
 1 Id. Hid. ter, and not at all in alcohol ^. 
 
 14. Benzoat of biimuth. This fait forms white 
 reedle-ftiaped cryftals. They are foluble in water, and 
 in a very fmall proportion in alcohol. They are not 
 altered by expofure to the air. Heat decompofej 
 
 * Id. Hid. them*. 
 
 15. Benzoat of antimony. Cryftals which efflorefce 
 ■f-IJ ibid, in the air, and are decornpofed by heat \. 
 
 16. Benzoat of arfenic. Small feather-fhaped cry- 
 ftals. It is foluble in hot water, but cryftallizes in the 
 cooling. A moderate heat fublimes it ; a ftrong beat 
 decompofes it. Sulphur decompofes it. It is not de.^ 
 
 \:U.ilid. compofed by alkalies ^i- 
 
 17. Benzoat of mercury. A white powder. It is 
 infoluble in water, but diifolves in a fmall quantity in 
 alcohol. It is not altered by expofure to the air. A 
 fmall heat fublimes it ; a greater decompofes it. It is 
 
 jf.ZJ.iiid. decornpofed by fulphur §, 
 
 i&. Benzoat offilver. This fait is foluble in water, 
 
 and alfo in a very fmall proportion in alcohol. It is Cmipho- 
 
 not altered by expofure to the air, but the rays of the ^ " ""' 
 
 fun render it brown. Heat difengages its acid *. . jj_ ,i,ij_ 
 
 19. Benzoat of gold. Small irregular cryftals, not 
 eafily foluble in water ; infoluble in alcohol. It is not 
 altered by expofure to the air. Heat decompofes it f. ^ Id. ihid. 
 
 10. Benzoat of platinum. This ialt forms fmall 
 brownilli cryftals, with difficulty foluble in water ; not 
 foluble in alcohol. When expofed to heat, it is decorn- 
 pofed, and there remains behind a brown powder J. } IJ.iiid. 
 
 Sect. XX. Of Succinats. 
 
 The neutral falts, formed by the combination of the 
 fuccinic acid with various bafes, have been called /uffi- 
 
 JUllS. 
 
 We ftiall not defcribe thefe falts, as we could not add 
 much to the account given in the Appendix to the ar- 
 ticle Chemistry in the Encycl. That account was ta- 
 ken from Mr Kier's Chemical Dictionary, and tliat 
 gentleman borrowed it from Leonhardi. 
 
 Sect. XXI. Of Camphorais. 
 
 The neutral falts into the compofition of which cam- 
 phoric acid enters, have been denominated camphorati- 
 The only chemift who has hitherto examined them is 
 Bouillon la Grange ; his experiments have been publiffi- 
 ed in the 27th volume of the Annahs de Chimie. 
 
 1. Camphorat of potafs. To prepare this fait, car-,, \ 
 bonat ot potais is to be dillolved in water, and the folu. „f p„t„f, 
 tion faturated with camphoric acid. When the effervef- 
 cence is over, the liquor is to be evaporated by a gentle 
 
 heat to the proper confiftence, and cryftals of campho- 
 rat of potafs will be depofited when the liquor cools. 
 
 Camphorat of potafs Is white and tranfparent ; its 
 cryftals are regular hexagons. Its tafte is bittenTa and 
 (lightly aromatic. 
 
 Water at the temperature of 60° diftblves -' jth part 
 of Its weight of this fait ; boiling water diirolves ^th 
 part of Its weight. 
 
 It Is foluble in alcohol, and the folution burns with a 
 deep blue flame. 
 
 Wlien expofed to moift air, it lofcs a little of its 
 tvanfparency, but in dry air it fuff^ers' no change. 
 
 When expofed to heat it melts, fwells, and the acid 
 is volatilized in a thick fmoke, which has an aromatic 
 odour. Before the blow-pipe it burns with a bhie flame, , 
 and the potafs remains behind in a. ftate of purity. 
 By compound affinity this fait is decompofed by 
 Nitrat of harytes. 
 All the falts whofe bafe h lime, 
 Nitrat of filver, 
 Sulphat of iron, 
 Muriat of tin, 
 
 lead §. { BoailUn 
 
 2. Camphorat of foda. This fait may be formed •^'' '^'"'"'.f'""- 
 precifcly in the fame manner with the camphorat of^f"''^ .. 
 potafs. ^. 
 
 It is white and tranfparent ; Its taft.c is fomewhat Sxi 
 bitter ; its cryftals are irregular. Camphorat 
 
 Water at the temperature of 6g° diflolves lefs than"^ '^"''^" 
 -s-i^th part of its weight of this fait ; boiling water dif- 
 folves -J-tli of its weight. 
 
 It is alfo foluble in alcohol. 
 
 Wiienespofed to the air it lofes its tranfparcncy, and 
 
 eftlorefcrt
 
 CHEMISTRY. 
 
 efflorefces flightly, but is never completely reduced to 
 powder. 
 
 Heat produces the fame effeft upon it as on cam- 
 phorat of potafs : tlie acid burns with a blue flame, 
 which becomes reddifh towards the end. 
 
 Bv compound affinity it is decompoled by 
 
 * Btutllon 
 ia Grange, 
 Jin*, de 
 Ctim.avVl. 
 96. 
 
 815 
 Camphorat 
 of ammo- 
 tiia. 
 
 Nitrat of lime, 
 
 filver, 
 
 Muriat of magnefia, 
 
 barytes, 
 
 alumina, 
 
 Muriat of lime, 
 
 • • iron, 
 
 Sulphat of alumina, 
 iron : and ma- 
 ny other fdks with me- 
 
 •{• 7iiJ. 
 8j6 
 Camphorat 
 of barytes. 
 
 I Bouillon 
 La Grange, 
 ibid. p. ZS. 
 
 Camphorat 
 •flime. 
 
 tallic bafes *. 
 
 3. Camphorat of ammonia. This fait may be pre- 
 pared by diflblving carbonat of ammonia in hot water, 
 and adding camphoric acid flowly till the alkali is fatu- 
 rated. It mull then be evaporated with a very mode- 
 rate heat, to prevent the difengaging of ammonia. 
 
 It is very difficult to obtain this fait in regular cry- 
 ilals. When evaporated to drynefs, there is obtained a 
 folid opaque mafs of a fliarp and bitterith tafte. 
 
 Water at the temperature of about 60' diffolves near- 
 ly Tstfth part of its weight of this fait ; boiling water 
 diffolves yd of its weight : But this and the two falts 
 above defcribed are a good deal more foluble when there 
 is excefs ot bafe. 
 
 ♦It is entirely foluble in alcohol. 
 
 When expofed to the air it attrads moifture, but not 
 in fufficicnt -quanuty to enable it to alTume a liquid 
 form. 
 
 When expofed to hent it fwcUs, melts, and is con- 
 verted into vapour; before the blow-pipe It burns with 
 a blue and red flame, and is entirely volatilized. 
 
 Mod of the calcareous falts form triple falts with 
 camphorat of ammonia. 
 
 It decompofes in part _all the aluminous falts except 
 the fulphat of alumina f . 
 
 4. Camphorat of barytes. In order to prepare this 
 fait, barytes is to be diilblved in water, and camphoric 
 acid added to the folution ; the mixture is then to be 
 boiled, and afterwards filtered and evaporated to dry- 
 nefs. 
 
 Camphorat of barytes does not xrryftallize; when the 
 evaporation is conducted llowly, the fait is depofited in 
 thin plates one above another, which appear tranfpa- 
 rent while immerfed in the liquor, but become opaque 
 whenever they come into contaft with the air. 
 
 It has very little tafte, though it leaves at laft upon 
 the tongue a flight impreffion of acidity mixed with bit- 
 ternefs. 
 
 Water diffolves only a very fmall quantity of this 
 fait, boiling water being c:ipable of taking up only 
 g^Tsth part of it. 
 
 It is not altered by expofure to the air. 
 
 When expofed to heat it melts eafdy, and the acid is 
 volatilized. When the heat is confidcrable, the acid 
 burns with a lively blue flame, which becomes red and 
 at laft white. 
 
 It is decompofed by 
 Nitrat of potafs, foda, lime, ammonia, and magnefia. 
 Muriat of lime, potafs, alumina, and magnefia. 
 All the fulphats. 
 Carbonat of potafs and foda. 
 Phofphat of potafs, foda, and ammonia*. 
 
 5. Camphorat of lime. This fait may be prepared 
 by dropping into lime-water cryftallized camphoric acid. 
 
 ZLim. xivii. 
 
 Part III. 
 
 The mixture is then to be made boiling hot, paffed Caiipho, 
 through a filter, and evaporated to about \\\\% of its "W- 
 volume. On cooling, camphorat of lime is depolited. » ' 
 
 It has no regular fliape ; but if the evaporation has 
 been properly condufled, it is in plates lying one above 
 another. It is of a white colour, and has a taft.e flightly 
 bitter. 
 
 Water at the temperature of 6o» diffolves very little 
 of this fait; boiling water is capable of diifolving about 
 T^^^th part of its weight of it. It is iufoluble in alco- 
 hol. 
 
 It is compofed of 43 parts of lime, 50 of acid, and 
 7 of water. 
 
 When expofed to the air it dries and falls into pow- 
 der. 
 
 When expofed to a moderate heat It melts and fwells 
 up : when placed on burning coals, or when iieated m 
 clofc veffels, the acid is decompofed and volatilized, and 
 the lime remains pure. 
 
 When fulphuric acid is poured into a folution of this 
 fait, it produces an in foluble precipitate; nitric and mu- 
 riatic acids precipitate the camphoric acid. 
 
 It is decompofed by compound affinity by 
 Carbonat of potafs, 
 Nitrat of barytes, 
 Muriat of alumina, 
 Sulphat of alumina, 
 Phofphat of foda *. • Bcu'itln 
 
 6. Camphorat of magnefia. This fait may be pre- i" Grange, 
 pared by pouring water on carbonat of magnefia, and ■f ''"• * 
 then adding cryftallized camphoric acid : heat is then 
 applied, the folution is filtrated, and evaporated to dry- SiS 
 neis. The fait obtained is diffolved in h jt water, paffed Camphorat 
 through 3 filter, and evaporated by means of a mode-"' "'^gne- 
 rate heat till a pellicle forms on the furfice of the folu- 
 tion. On cooling, the fait is depofited in thin plates. 
 
 The fecond folution is to remove any excefs of magne- 
 fia that may happen to be prefent. 
 
 This fait does not cryftallize. It is white, opaque, 
 and has a bitter tafte. 
 
 It is fcarcely more foluble in water than camphorat 
 of lime. 
 
 Alcohol has no aftion on it while cold, but when hot 
 it diffolves the acid and leaves the magnefia ; and the 
 acid precipitates again as the alcohol cools. 
 
 When expofed to the air it dries and becomes cover- 
 ed with a little powder ; but this effect is produced 
 flowly, and only in a warm place. 
 
 When this fait is placed on burning coals, the acid 
 is volatilized, and the magnefia remains pure. Before the 
 blow-pipe it burns like the other camphorats with a 
 blue flame. 
 
 The nitrats, muriats, and fulphats, do not complete- 
 ly decompofe this fait, if we except the nitrat of lime 
 and muriat of alumina f . {Id. ind. 
 
 7. Camphorat of alumina. To prepare this fait, alu- 819 
 mina, precipitated by means of ammonia, and well wafti- *"J'"j'P''?"' 
 ed, is to be mixed with water, and cryftals of campho- 
 ric acid added. The mixture is then to be heated, fil- 
 
 tered, and concentrated by evaporation. 
 
 This fait is a white powder, of an acid bitterifli tafl;e, 
 leaving on the tongue, like moft of the aluminous falts, 
 a fenfation of aftringency. 
 
 Water at the temperature of 60" diffolves about -r^tli 
 part of its weight of this fait. Boiling water diffolves 
 
 it
 
 rart in. 
 
 CHEMISTRY. 
 
 385 
 
 Suherats. 
 
 ** Bouillon 
 ixi GmngCy 
 jimn. de 
 dim. xxvii 
 34- 
 
 Suherat of 
 potal's. 
 
 ■^ v. iby. 
 
 xxii). 52. 
 
 Sulierat of 
 foda. 
 
 } /y. iiU 
 p. 5.!- 
 
 Suberat nf 
 aranionla. 
 
 P-S5. 
 
 i>33 
 Sulieriit of 
 barytes. 
 
 II IJ. ibid. 
 p. 5J. 
 
 834 
 Suberat of 
 lime. 
 
 ^ W. ibiJ. 
 p. 54- 
 835 
 Suberat of 
 magnefia. 
 
 it in confiderable quantities; but It precipitates again as 
 tlie folution cools. 
 
 Alcohol, while cold, difTulves it very fparingly ; but 
 when hot it dilTolves a confiderable quantity of it, which 
 precipitates alio as the folution cools. 
 
 This fait undergoes very little alteration in the air ; 
 but it rather parts with than attradls moillure. 
 
 Heat volatilizes the acid; and when the fait is thrown 
 on burning coals it burns with a blue flame. 
 
 It is decompofed by the nitrats of lime and ba- 
 rytes *. 
 
 Sect. XXII. Of Suherats. 
 
 The falls formed by the fuberic acid have obtained 
 the appellation oi fubtrats. They have hitherto been 
 examined only by Bouillon la Grange. 
 
 1. Suberat of potafs. — This fait ought to be formed 
 by means of cryllullized carbonat of potals. 
 
 It cryftallizes in prifms, having four unequal fides. 
 It has a bitter faltifh talle, and it reddens vegetable 
 blues. It is verv foluble in water. Caloric melts it, 
 and at laft volatilizes the acid. 
 
 It is decompofed by mod of the metallic falts, and 
 by fulphat of alumina, muriat of alumina, and of lime ; 
 nitrat of alumina and of lime ; and phofphat of alu- 
 mina \. 
 
 2. Suberat of foda. — This fait does not cryftallize. It 
 reddens the tinfture of turnfole. Its tafte is flightly 
 bitter. It is very foluble in water and in alcohol. It 
 attrads moillure from the air. Caloric produces the 
 fame effeft on it that it does on fuberat of potafs. 
 
 It is decompofed by the calcareous, aluminous, and 
 magnefian falts |. 
 
 3. Suberat ol ammonia. — This fait cryftallizes in pa- 
 rallelopipeds. Its tafte is faltifti, and it leaves an im- 
 prefGon of bitterncfs : It reddens vegetable blues. 
 
 It is very foluble in water. It attracts moifture from 
 the air. When placed upon burning coals, it lofes its 
 water of cryftallization, and fwells up ; and before the 
 blovv-pipe it evaporates entirely. 
 
 It is decompofed by the aluminous and magnefian 
 falts J. 
 
 4. Suberat of barytes. — This fait does not cryftallize. 
 Heat makes it fwellup, and melts it. It is fcarcely fo- 
 luble in water except there be an excefs of acid. 
 
 It is decompofed by moft of the neutral falts, except 
 the barytic falts and the fluat of lime {|. 
 
 5. Suberat of lime. — This fait does not cryftallize. 
 It is perfectly white : It has a faltifh tafte : It does not 
 redden the tinfture of turnfole. 
 
 It is very fparingly foluble in water except when hot; 
 and as the folution cools moft of the fait precipitates 
 again. 
 
 When placed upon burning coals it fwells up, tlie 
 acid is decompofed, and there remains only the lime in 
 the ftate of powder. 
 It is decompofed by 
 
 The milriai of alumina, 
 
 The carbonats of potafs and foda, 
 
 The fluat of magnefia. 
 
 The phofphats of alumina and foda. 
 
 The borat of potafs, 
 
 All the metallic folutions ^. 
 
 6. Suberat of magnefia. — This fait is in the form of 
 a powder :. It reddens the tinfture of turnfole. It has a 
 
 Suppt. Vol. I. Part I. 
 
 and attrafts fome Piuffiau 
 
 t U itii, 
 
 P-i7- 
 
 bitter tafte : It is foluble in water, 
 
 moifture when expofed to the air, • 
 
 When heated it fwells up and melts : before the 
 blow-pipe the acid is decompofed, and the magnefia re- 
 mains in a ftate of purity. 
 It is decompofed by 
 
 Muriat of alumina, 
 
 Nitrat of lime and alumina, 
 
 Borat of potafs, 
 
 Fluat of foda, 
 
 Phofphat of alumina *. • Bouillon 
 
 7. Suberat of alumina. — This fait does not cryftallize. f^* Grange, 
 When its folution is evaporated by a moderate heat in-^""'* . . 
 a wide veflel, the fait obtained is of a yellow colour, ' 
 tranfparent, having a ftyptic tafte, and leaving an im- g^$ 
 prelTion of bitternefs on the tongue. When too much Suberat of 
 heat is employed it melts and blackens. It reddens the al"n>ina. 
 tinfture of turnfole, and attrafts moifture from the air. 
 Before the blow-pipe it fwells up, the acid is volatilized 
 and decompofed, and nothing remains but the alumina. 
 It is decompofed by 
 
 The carbonats of potafs and foda. 
 
 The fulphat of iron. 
 
 The muriat of iron. 
 
 The nitrats of filver, mercury, and lead \. t '^^ '^''• 
 Suberic acid forms alfo compounds with the oxides of 
 filver, mercury, lead, copper, tin, iron, bifmuth, arfenic, 
 cobalt, zinc, antim(«'iy, manganefe, and molybdenum ; 
 moil of which are incryftallizable, and have an excefj 
 of acid J. 
 
 Sect. XXIII. Of PrufmH. 
 
 The compounds into which the pruffic acid enters 
 are called Prufflals. 
 
 Thefe fubftances, the moft important of which are 
 triple falts, have fomethiiig very peculiar in their affi- 
 nities. The pruflic acid appears to have a ftronger af- 
 finity for alkalies and earths than for metals, at leaft thefe 
 fubftances are capable of decompofing metallic prufliats ; 
 yet acids fcarcely decompole the metallic prufliats, while 
 the weakeft acid known decompofes the prufliats of al- 
 kalies and earths. Thefe phenomena have not yet been 
 fatisfadlorily accounted for. 
 
 1. Pruffiat of potafs. 1 r^^^^^ ^^,^^ ^^^^^ ^_.^ ob- Alkaline 
 
 2. rrumat 01 lona. J pruILats. 
 tained pure by Mr Scheele. They are foluble in wa- 
 ter ; but they are of little ufe, as mere expofure to the 
 
 air decompofes them. 
 
 3. Pruifiat of ammonia. — This fait has the fmell of 
 ammonia. It is very volatile and as eafily decompofed 
 
 as the other two. 838 
 
 4. Pruflidt of lime. — This fait is foluble in water. Earthy 
 It is alfo decompofed by expofure to the air. prufliats. 
 
 5. Pi ufliat of barytes. 
 
 6. Prufliat of magnefia. 
 lublc in water, and decompofed by all acids. 
 
 Pruflic acid does not combine with alumina. 839 
 
 7. Prufliat of iron, or Pruffian blue. — This fubftance Pfultian 
 is compofed, as Mr Prouft has fliewn, of the pruflic 
 
 acid and brown oxide of iron. With the green oxide 
 the pruflic acid forms a white compound, which, how. 
 ever, becomes gradually blue when expofed to the at- 
 mofphere, becaufe the oxide abforbs oxygen, and is con- . 
 verted into brown oxide §. J Nicial- 
 
 Prulfiat of iron is a deep blue coloured powder. It j, ^^^, 
 3 C 16 
 
 ."37 
 
 } 
 
 Thefe falts are alfo fo-
 
 386 
 
 CHEMISTRY. 
 
 Part III, 
 
 Prufliat' 
 
 (40 
 
 An.nities 
 rf the priif- 
 £c acid ex- 
 f'liined. 
 
 S4T 
 
 Pfoferties 
 «f prulTian 
 aliUU. 
 
 is iiifoluMe in Vfater, and fcarcely foiuble in acids. It 
 is compoltd, according to the tnoit accurate experiments 
 hitherto made, of equal parts of oxide of iron and pruf- 
 fic acid. It is not affefted by expofure to the air. Heat 
 dtcompofcs it by deftroying the acid, and the oxide of 
 iron remains behind. 
 
 The Pruflian blue of commerce, befides other impuri- 
 ties, contains mixed with it s great quantity of alumina. 
 Its ufe as a pigment, and the attempts which have been 
 made to introduce it as a dye, arc well known. 
 
 Prufliat of iron may alfo exill in another ftate : It 
 may have a fiiperabundance of oxide ; its colour is then 
 more or lels yellow. '1 o this Hate it may be reduced 
 by digefting it with alkalies or any of the alkaline 
 earths. Thcfe fubftances deprive it of part of its acid, 
 but not of the whole. 
 
 This yellow pruffiat is foiuble in acids. 
 
 Were vfe to attempt an explanation of this, and the 
 other phenomena which the pruflic acid difplays in its 
 combinations, we would conjeAure, that this yellow 
 prufliat is the fubflaiice formed by the direft combina- 
 tion of brown oxide of iron and pruflic acid, and that 
 the blue prufliat is formed of the yellow prufliat combi- 
 ned as an integrant with pruflic acid : That the affinity 
 between the pruflic acid and oxide of iroii is much ftrong- 
 er than that between yellow prufliat of iron and pruflic 
 aeid ; that therefore alkalies and earths have a ftronger 
 affinity for pruflic acid than the yellow pruflTiat has, hut 
 a much weaker afiinity than oxide of iron, and perhaps 
 fvery other oxide ;— hence the apparent fupcriority of 
 alkalies and earths in fome cafes, while in others they 
 appear very inferior. We would fuppofe, then, that 
 the pruflic acid has a much ftronger affinity for oxide 
 of iron, and perhaps for all other oxides, than for other 
 bodies ; that the prulfiats, thus formed, are capable of 
 GombiiiiTig with pruflic acid ; but that their affinity for 
 it is much Icfs than that of the alkalies and earths. This 
 Gonjefture is fupported by all the plienomena at prefent 
 known ; it would remove all the apparent anomalies 
 which the combinations of this fmguJar acid prefent, 
 and reduce the whole of them under the known laws 
 of afiinity. 
 
 S. Prufliat of potafs and iron, commonly called Pruf- 
 Jmn alkali, or PruJJian tejl. This fubllance is a triple 
 fait, compofed of pnifiic acid, potafs, and oxide of iron 
 combined together. To chcmifts and mineralogift:s it 
 is one of the moft important inftruments ever invented ; 
 as, when properly prepared, it is capable of indicating 
 ■whether any metallic fubilance (platinum excepted) be 
 prefent in any foluticn whatever, and even of pointing 
 out the particular metal, and of afcertaining its quan- 
 tity : This it does by means of a compound affinity, 
 which, after what has been faid above, may be eafily 
 underllood. The Pruflian alkali may be conceived to 
 be a combination of two fubftances, prufliat of pot- 
 afs and blue prufliat of iron. Now every metallic oxide 
 has a ftronger afSnity for pruflic acid than potafs has 
 fand, in faft, feems to have a ftronger affinity for it 
 than for any other fubftance). If, therefore, there hap- 
 pen to be any oxide in the folution, it immediately feizes 
 the pruflic acid with which the potafs is combined, and 
 by that means decompofcs the triple fait. A prufliat 
 of the particular metal is formed, and, as moil prufliats 
 of metals are infoluble, it is precipitated ; and it indi- 
 cates by its colour the particular metal, and by its 
 
 weight the quantity of metal that happens to be pre- Prufliatt, 
 feut. At the fame time the blue prufliat of iron is al. ' * * 
 fo precipitated, and its weight muft be deducted from 
 the quantity of the precipitate. 
 
 In order to be certain of the accuracy of thefe re- 
 fults, it is neceffary to liave a Pruflian alkali perfeftly 
 pure, and to be certain before hand of the quantity, or 
 rather of the proportions of its ingredients. To ob- 
 tain a teft of this kind has been the objedt of chemifts 
 ever fince the ditcoveries of Macquer pointed out its 
 importance. It is to the ufe of impure tefts that a 
 great part of the contradiftory refults of mineralogical 
 analyfes by different chemifts is to be afcribed. 
 
 There are two * ways in which this teft may be ren- « See Kir. 
 dered impure, befides the introduftion of foreign in- y"'' Min, 
 gredients, which we do not mention, becaufe it is ob-'"*|7' 
 vious that it muft be guarded againft. i. There may be jja^le to 
 a fuperabundance of alkali prefent, or, which is the impuritief, 
 fame thing, there may be mixed with the Pruflian teft 
 a quantity of pure alkali ; or, 2. There may be contain- 
 ed in it a quantity of yellow prufliat of iron, for which 
 prufliat of potafs has alfo a confiderable affinity. 
 
 If the Pruflian teft contain a fuperabundance of al- 
 kali, two inconveniences follow. This fuperabundant 
 quantity will precipitate thofe earthy falts which are li- 
 able to contain an excefs of acid, and which are only 
 foiuble by that excefs : Hence alumina and barytes will 
 be precipitated. It is to the ufe of impure tefts of 
 this kind that we owe the opinion, that barytes and 
 alumina are precipitated by the Pruffian alkali, and the 
 confequent theories of the metallic nature of thefe earths. 
 This miilake was firft correfted, we believe, by Mr Kla- 
 proth. 
 
 Another inconvenience arifmg from the fuperabun- 
 dance of alkali in the Pruflian teft is, that it gradually 
 decompofes the blue prufliat which the teft contains, 
 and converts ft into yellow prufliat. In what manner 
 it does this will be underllood, after what has been faidi 
 without any explanation. 
 
 On the other hand, when the Pruffian alkali contain*- 
 a quantity of ycllcw pruffiat of iron, as great inconve-^ 
 niences follow. This yellow pruffiat has an affinity for 
 pruffic acid, which, though inferior to that of the pot- 
 afs, is ftiU confiderable ; and, on the other hand, the 
 potafs has a ftronger affinity for every other acid than 
 for the pruffic. When, therefore, the teft is expofed 
 to the air, the carbonic acid, which the atmofphere al- 
 ways contains, affifted by the affinity between the yel- 
 low pruffiat and the pruffic acid, decompofes the pruf- 
 fiat of potafs in the teft; and the yellow pruffiat is pre- 
 cipitated in the form of Pruffian blue : And every other 
 acid produces the fame eff^eft. A teft of this kind, 
 therefore, would indicate the prefence of iron in every 
 mixture which contains an acid (for a precipitation of 
 Pruffian bltie would appear) ; and could not, therefore, 
 be trufted to with any confidence. g,. 
 
 We will not attempt to defcribe the various methods KUproth'*- 
 which diff'erent chemifts have adopted of preparing this method of 
 teft; but (hall fatisfy ouifelves with defcribing the fo^i^S ''■ 
 method of Klaproth, which anfwers the purpofe com- 
 pletely. This we ffiall do nearly in the words of Mr 
 KIrwan. 
 
 Prepare a pure potafs, by gradually proJeAing into a 
 large crucible heated to whitnefs a mixture of equal parts 
 of purified nitre and cryftals of tartar ; when the whole
 
 Part III. 
 
 CHEMISTRY. 
 
 IPiullbts. 
 
 i. 494. 
 
 f Bcrtbdht. 
 
 Prudiat of 
 ammoD'a 
 and iron. 
 
 'J turn, de 
 i'tyf- ixxiv. 
 le:. 
 
 is inje£>ed, let it be kept at a white heat for half an 
 hour, to burn ofi the coal. 
 
 Detacli the alkali thus obtained from the crucible, 
 reduce it to poivdcr, I'prtad it on a muffle, and expofc 
 it to a white heat for half an hour. 
 
 DIflolve it in fix times its weight of water, and filter 
 the fohition while warm. 
 
 Pour this fulution into a glafs receiver, placed in a 
 fand furnace, heated to 170" or 180'', and then gradu- 
 ally add the beft Pruffian blue in powder, injedling new 
 portions according as the former becomes grey, and 
 iupplyiiig water as faft as it evaporates ; continue until 
 the added portions are no longer dilcoloured, then iu- 
 creafe the heat to 212° for half an hour. 
 
 Filter the ley thus obtained, and faturate it with ful- 
 phuric acid moderately diluted ; a precipitate will ap- 
 pear ; when this ceafes, filter off the whole, and wafh 
 the precipitate. 
 
 Evaporate the filtered liquor to about one quarter, 
 and fet it by to cryftallize : after a few days, ycllowifh 
 cryftals of a cubic or quadrangular form will be found 
 mixed with fome fulphat of potafs and oxide of iron ; 
 pick out the yellowifh cryftals, lay them on blotting 
 paper, and rediflblve them in four times their weight of 
 cold water, to exclude the fulphat of potafs. 
 
 7. Effay a few drops of this folution with barytic 
 water, to fee whether it contains any fulphuric acid, and 
 add fome barytic water to the remainder if neceflary : 
 filter off the folution from the fulphat of barytes, which 
 will have precipitated, and fet it by to cryftallize for a 
 few days ; that the barytes, if any (honld remain, may 
 be precipitated. If the cryftals now obtained be of a 
 pale yellow colour, and difcover no bluilh ftreaks when 
 fprinkled over with muriatic acid, they are fit for ufe ; 
 but if they ftill difcover bluilh or green ftreaks, the fo- 
 lutions and cryftallizations muft be repeated. 
 
 Thefe cryftals muft be kept in a well-ftopped bottle, 
 which to preferve them from the air ihould be filled with 
 alcohol, as they are infoluble in it. 
 
 Before they are ufe(}< the quantity of iron they con- 
 tain fhould be afcertained, by heating 100 grains to 
 rednefs for half an hour in an open crucible : the pruf- 
 fic acid will be confumed, and the iron will remain in 
 the ftate of a reddiih brown magnetic oxide, which ihould 
 be weighed and noted : This oxide is half the weight 
 of the Prufiian blue afforded by the Prudian alkali ; its 
 weight muft therefore be fubtrafted from that of me- 
 tallic precipitates formed by this teft. Hence the weight 
 of the cryftals, in a given quantity of the folution, (hould 
 be noted, that the quantity employed in precipitation 
 may be known. Care muft be taken to continue the cal- 
 cination till the oxide of iron becomes brown ; for while 
 it is black it weighs confiderably more than it (hould *. 
 
 9. Pruffiat of foda and iron. The only difcernible 
 difference between this fait and the laft is, that it cry- 
 ftallizes differently f. 
 
 10. Pruffiat of ammonia and iron. This triple fait 
 has alfo been employed as a teft ; but it is not fo cafy 
 to obtain it in a ftate of purity as the other two. It 
 was difcovered by Macquer, and firft recommended by 
 Mej'er. 
 
 It forms flat hexangular cryftals, foluble in water, 
 and deliquefces in the air. Heat decompofes it like the 
 other pruffiats \. 
 
 We ftall not give any defcription of the triple falls 
 
 .1»7 
 
 formed by digeftinjj the alkalin; eurths on pruffiat of Sebst!.. 
 
 iron; they are fufficiently knov.-n, and arc not of any '~~~v ■-' 
 
 ufe except as tefts ; and in that ri-fpedt they are inferior 
 
 to that above defcribed. They are all foluble in water, 
 
 and are moft of them capable of cryftallizing. g;^ 
 
 II. Pruffiat of mercury. This l'<»)t, which was firft I'rnflijt of 
 formed by Schecle, is compofed of the piuffic acid'""'^"')'' 
 combined with the red oxide of mercury. It may be 
 formed by boiling ihc red oxide of mercury with Pruf- 
 fian blue. It cryftallizes in tetrahtdral prifms, termi- 
 nated by quadrangular pyramids, the fides of which cor- 
 refpond with the angles of the prifm. 
 
 This fait is capable of combining with fulphuric and 
 muriatic acids, and forming triple falts, which have not 
 yet been examined *. ' 
 
 Serthtlhf 
 
 Sect. XXIV. 
 
 846 
 
 Of Formats. 
 
 The compounds into which the formic acid enters 
 are cdM^i formats. We fliall nut <iefcribe them, as little 
 has been added to the account already given in the Ap- 
 pendix to the article Chemistry in the Encyclopedia. 
 
 Sect. XXV. Of'Scbats. 
 
 The compounds into which the febacic acid enters 
 are ci\\ed.fcbats. For our knowledge of this clals of 
 falts we are chiefly indebted to the celebrated Crel!, 
 who publifhed a diflertation on the febacic acid and its 
 combinations in the Philofophical Tranfaftions for 1780 
 and 1782. 
 
 1. Sebat of potafs. This fait is of a white colour. A!k-7liiiefe. 
 Its cryftals are quadrangular pyramids, of which two^^'*- 
 oppofite fides are narrower than the others, it has a 
 
 ftiarp faline tafte like muriat of ammonia, but milder. 
 It is foluble in water, infoluble in a'cohol, and does not 
 deliquefce when expofed to the air. Heat decompofes it. 
 
 2. Sebat of fiida. This fait is white. Its cryltals 
 are pyramids, with three or four fides : a very mode- 
 rate heat melts them. 
 
 3. Sebat of ammonia. This fait in tafte and folubi- 
 lity refembles muriat of ammonia, but it differs from it 
 
 in not being capable of fubliming iron. . 
 
 4. Sebat of lime. The cryftals of this fait are hex-Ejrthy fe- 
 agons, terminated by a plane furface ; they have a Iharpbats. 
 acrid tafte ; are very foluble in water, but not in alco- 
 hol : they do not deliquefce. 
 
 5. Sebat of raagnefia. A gummy, faline, uncryftal- 
 lizable mafs. 
 
 6. Sebat of alumina. A gummy faline mafs, which 
 does not cryftallize, and has an auftere aftringeut tafte. - , 
 
 7. Sebat of iron. Ncedle-ftiaped cryftals, which de-Metallicfc- 
 liquefce. Lats. 
 
 8. Sebat of lead. Needle-fhaped cryftals, very fulu- 
 ble in water. 
 
 9. Sebat of tin. A white deliquefcent fait. 
 
 10. Sebat of copper. This fait is capable of cryftal- 
 lizing, but is very deliquefcent. 
 
 11. Sebat of antimony. A cryftallizable fait, which 
 does not deliquefce. 
 
 12. Sebat of arlcnic. Small cryftals. 
 
 13. Sebat of mercury. A white powder, very dif^ 
 ficultly foluhle in water. 
 
 14. Sebat of gold. Yellow cryftals. 
 
 15. Sebat of platinum. Brow i-ilh yellow cryftals. 
 The bonibats or compounds which the bombic acid 
 
 forms are ftill unknown. 
 
 3 C 2 Sect.
 
 388 
 
 Metallic 
 Acid ialts. 
 
 CHEMISTRY. 
 
 Sect. XXVI. Of ArJenmU. 
 The compounds formed by the combination of the 
 
 Part III; 
 
 arfenic acid with bafes are called arfcniUs. This clafs 
 of falts was firfl difcovered by Macquer ; but little ac- 
 curate was known concerning it till Schtele made known 
 the arfenic acid. 
 
 An abftracl of Scheele's experiments has been given 
 in the article Chemistry, Encycl. 
 
 To his dcfcription of arleniats feveral additions might 
 be made, but not of fufficient confequence to warrant a 
 repetition of what has been given in that article ; and 
 without fnch a repetition thefe additions would fcarcely 
 be intclhgible. 
 
 Sect. XXVII. Of Metallk yfci^ Stilts. 
 
 It has been conjeftured that all metals may be con- 
 verted into acids by combining them with a fufficient 
 quantity of oxygen. This conjedlure has been verified 
 in a confiderable number of Inilances. We have feen 
 the arfenic acid, the tungftic acid, the molybdic acid, 
 and the new metallic acid of Vauquclin. BerthoUet 
 Las difcovered that platinum becomes an acid ; and 
 the fame thing has been afcertained with regard to tin. 
 Even thofe metallic oxides which do not pofTefs many 
 of the characters of acids are capable of combining with 
 alkalies and earths, and of forming peculiar neutral falts. 
 Thefe oxides, therefore, perform the office of acids ; 
 and confequently mull be confidered as partaking of 
 their nature, or rather as a kind of intermediate fub- 
 flances between acids ami thofe bodies which unite only 
 with acids. 
 
 Some of thefe neutral falts we fhall proceed to enu- 
 merate. 
 
 1. Aiirat of ammonia, or fulminating gold. This 
 fait is compofed of the oxide of gold and ammonia. 
 This compound may be formed by precipitating gold 
 from nitro-muriatic acid by ammonia. The precipitate 
 is fulminating gold. Bergman was the firll who clear- 
 ly dcmonftrated that this powder is compofed of oxide 
 of gold and ammonia. When heated a little above the 
 boiling temperature it explodes with aftoniiliing vio- 
 lence. Chemills had made many attempts to explain 
 the caufe of this phenomenon, but without fuccefs, till 
 Mr Berthollet difcovered the compofition of ammonia. 
 After making that difcovery, he proved, by a number 
 of delicate and hazardous experiments, that during the 
 fulmination the ammonia is decompofed, that its hydro- 
 gen combines with the oxygen of the oxide and forms 
 water, while the azot flies off in a gafeous form, and 
 occalions the explofion. 
 
 2. Argentat of ammonia, or fulminating filver. This 
 ting filver^ fubilance was difcovered by Mr Berthollet. It may be 
 
 formed by dlffolving oxide of filver in ammonia. It is 
 a black powder. It poffefles the fulminating property 
 much more powerfully than the laft defcribed fubftance. 
 The (lighteit friftion makes it explode with violence. 
 * Btrtbollet, This property, as Mr Berthollet has proved *, is owing 
 to the fame decompofilion of ammonia and formation 
 of water that caufes the explofion of fulminating gold. 
 If a fmall retort be filled with the liquor from which 
 the fulminating filver has been precipitated, and be made 
 to boil, fome azot is difengaged, and fmall opaque cry- 
 ftals are formed confifting of the fame fubftance; which 
 explode when touched, though they be covered with 
 
 849 
 Fulmina- 
 ting gold. 
 
 8^0 
 Fulmina- 
 
 Ann.de 
 Cbim. I 
 
 water. Nitrat and muriat of barytes pre cipitate Clver Hydroful- 
 from this fait. pburcts. 
 
 3. Mercurial of lime. Oxide of mercury boiled with o " 
 lime-water forms, by evaporation, fmall traufparent ycl- Mercuriat 
 low crylldls *. of nn e and. 
 
 4. Mercuriat of ammonia. Oxide of mercury Jif. "f ammo- 
 folves in ammonia in large quantity, and by evapora- ."jj ,. . 
 tion furniflies a white falt-j-. | Laveifur 
 
 5. Cuprat of ammonia. Oxide of copper diflblves '*'■/. 
 
 In ammonia. Mr Sage has defcribed its cryftalll-zation. , ^-5* 
 
 Ii is decompofed by lime and potafs, and cuprat of lime "I"'"?' 
 , 1- r 1 '^ ammonia, 
 
 and potals are lormed. g,, 
 
 6. Stannat of gold. When gold is precipitated by Stannat of 
 tin it unites with it. Vogel and Beauine firit obfervcd K°'''* 
 that the precipitate, which is purple, contained tin. S54 
 
 7. Plumbat of lime. Lime-water boiled on the red P'^pl^t 
 oxide of lead diflolved it. This folution, evaporated in a '""'* 
 retort, gave very fmall tranfparent cryllals, forming prif- 
 matic colours, and not more foluble in water than lime. 
 
 It is decompofed by all the fulphats of alkalies and by ful- 
 
 phurated hydrogen gas. The fulphuric and muriatic 
 
 acids precipitate the lead. It blackens wool, the nails, 
 
 the hair, white of eggs ; but it does not affcCt the colour 
 
 of filk, the flfin, the yoke of eggs, nor animal oil. It is 
 
 the lead which is precipitated on thefe coloured fub- 
 
 ftances in the ftatc of oxide; for all acids can diflolve it. t jjcrtMU* 
 
 The fimple mixture of lime and oxide of lead blackens .i/ji.i/f 
 
 thefe fubllances ; a proof that the fait is eafily formed J. '-'*''»'■ '• 37' 
 
 8. Zincat of ammonia. De Cafione has publifhed a„- 5 
 
 Zincat of 
 antmonia. 
 
 great number of experiments on the property which 
 
 ammonia has of diffolving oxide of zinc. L,ime.water J Id. Hid. 
 
 and potafs alfo dilTolve it §. P- 4*- 
 
 o. Antimoniat of potafs. When antimony is deto- *: 
 ^ . . , . . '^ ... -. 1, . Antimoniat 
 
 nated with nitre in a crucible, part or its oxide unites ^fj^f^ 
 
 with the potafs of the nitre ||. n u.ibid.. 
 
 Chap. III. ©/"Hydrosulphurets. 
 
 8J7 
 
 Sulphurated hydrogen gas, which has been defcri- Properties 
 bed in the firft part of this article, pofleffes almoft all^f f"'p''"- 
 the properties of acids. It combines with water, and"' ^' 
 the folution gives a red colour to vegetable blues. It 
 decompofes foaps and fulphurets, and is capable of com- 
 bining with alkalies, earths, and metallic oxides, and of 
 forming compounds, to which Mr Berthollet, to whom 
 we are indebted for difcovering them, has given the 
 name of hydrofulphurets ff. m j j 
 
 Before giving any account 01 theie compounds, which c/iim.xi.t, 
 we (hall do from the paper of Berthollet jull quoted, 233. 
 we beg leave to make a few previous obfervations, in 
 order to redlify fome inaccuracies into which we have 
 fallen from not being acquainted with the experiments 
 of that philofopher. . - 
 
 Sulphur is capable of combining with alkalies, earths, Remarks 
 metals, and metallic oxides, and forming the compoundson fulphu- 
 known by the name of fulphurets. The alkaline, earthy,"'** 
 and even fome of the metallic fulphurets, can only exilt 
 in a ftate of drynefs: the inftant they are moiftened with 
 water, a quantity of fulphurated hydrogen gas is form- 
 ed, which combines with the fulphuret, and forms a new 
 compound. To thefe triple compounds Mr Berthollet 
 has given the name of hydrogenous fulphurets. AH fo- 
 lutions of fulphurets in water are in faft hydrogenous 
 fulphurets. Were it not for the formation and combi- 
 nation of fulphurated hydrogen, the alkaline fidphurets 
 
 would
 
 Part nr. 
 
 859 
 
 Hydroge- 
 nous ful- 
 phuret of 
 iacrcury. 
 
 kvdroful 
 phurets. 
 
 Hydrnful- would be completely dccompofcd by water, and their 
 phurets. fulp^^ir precipitated; for water has a ftronger afiiiiity 
 ''"-'f—^^ fj,^ jfjg alkalies than fulphur has. This Berthollet pro- 
 ved by the following experiment : To a lohuion of inl- 
 phuret of potafs in water (that is, to hydrogenous ful- 
 phuret of potafs), a quantity of oxy-muriatic acid fu- 
 perfaturated with potafs was added, and the fulphur 
 was immediately precipitated. In this experiment the 
 fulphurated hydrogen was deftroycd by the oxygen of 
 the oxy-muriatic acid ; and the precipitation of the ful- 
 phur (hews that its afRiiity for potafs was not fufficient 
 to keep it diffolved, or, which is the fame thing, that 
 its affinity fur potafs was inferior to that of water. 
 
 The fubftance which we defciibcd in Part I. chap. ili. 
 feft. 4. of this article, under the name of Black Sul- 
 phuret of Mercury, is a hydrogenous fulphuret of mer- 
 cury, and therefore differs from tlie red fulphuret of 
 mercury or cinnabar by containing a quantity of ful- 
 phurated hydrogen. Potafs has a (Ironger affinity for 
 this lall fubftance than the fulphuret ; potafs thereiore, 
 by the affiftance of heat, deprives the black or hydro- 
 genous fulphuret of its fulphurated hydrogen, and re- 
 duces it to the ftate of red fulphuret. This explains 
 the method of forming cinnabar defcribed in the feition 
 above referred to, and points out a much cafier procefs 
 g, for obtaining that ufeful pigment. 
 
 IWcthod of We (hall now proceed to the method of forming the 
 forming hydrofulphurets. Berthollet obtained fulphurated hy- 
 drogen gas from fulphuret of iron in the ufual manner, 
 by means of fulphuric acid. It was made to pafs thro' 
 a velTel filled with water before it entered that in which 
 the combination was to take place. By this method a 
 folution of potafs was impregnated with fulphurated hy- 
 drogen ; and in order to be certain of faturating the 
 alkali completely, the gas was added in exccfs, and the 
 excefs was afterwards driven off by means of heat. By 
 this metfiod hydrofulphurets of potafs, foda, and ammo- 
 nia, may be formed. 
 
 In order to form hydrofulphuret of lime, that earth 
 was mixed with difliilcd water, and fulphurated hydro- 
 gen gas pafTed into this mixture till a fufficient quan- 
 tity cf hydrofulphuret was judged to be formed ; the li- 
 quid, which contained it in folution, was poured off the 
 undifTolved lime, and laturated to excefs with fulphura- 
 ted hydrogen, and this excefs was afterwards driven off 
 by means of heat. 
 
 Hydrofulphuret of magnefia may be formed by dif- 
 folviiig magnefia in water impregnated with fulphura- 
 ted hydrogen gas. 
 
 If a folution of fulphuret of barytes in water, or, 
 more properly, if hydrogenous fulphuret of barytes be 
 evaporated, a great number of confufed cryflals are 
 formed ; if thefe be feparated quickly by iiltration, and 
 placed upon blotting paper to dry, a white cryftalline 
 fubftance is obtained, which is hydrofulphuret of ba^ 
 rytes. 
 
 The afHnities of the alkalies and earths for fulphura» 
 of fulphu- ted hydrogen appear, from the esperiments of Berthol» 
 rated hy- let, to be as follows : 
 ■^"S'"' Barytes, 
 
 Potafs, 
 Soda, 
 Lime, 
 Ammonia,. 
 
 CHEMISTRY. 389 
 
 Magnefia, 
 
 Jargonia. ^^^ 
 
 Almoft all the metallic oxides have a ftronger affiin'ty ''" 
 
 for fulphtiratcd hydrogen than the earths have. ggj 
 
 Hydrcful- 
 ^)hure•t^. 
 
 86r 
 Aflinitict 
 
 When the hydrofulphurats are piepartd with the ne- Properticj 
 ceffary precautions to prevent the oiitadt of atmofphe-o' hydro- 
 rical air, they are colourlefs, bat the a£lioii of the air P"**' 
 renders ihein yellow. 
 
 If they be dtcoinpofed while they are colourlefs, by 
 pouring; upon them fulphuric acid, muriatic acid, or 
 any other acid which dues not ait upon hydrogen, the 
 fulphurated hydrogen gas exhales without the dcpofition 
 of a fiiiglc particle of fulphur ; but if the hydrofulphu- 
 ret has become yellow, fome fulphur is always depofited 
 during its decompolition, and the quantity of fulphur is 
 pioporticjnal to tl'.e deepncfs of tjie colour. 
 
 The yellow colour, therefore, which hydrofulphurets 
 acquire by expolure to the atmoiphere is owing to a. 
 conunencement of deconipofition. Part cf the hydro- 
 gen of the fulphurated hydrogen abandons the fulphur, 
 Combines with the oxygen of the atniofphere, and 
 forms water. By degrees, however, a portion of the 
 fulphur is alfo converted into an acid ; and when the 
 proportion of fulphurated hydrogen is diminiflied, and 
 that of the lulphur increafed to a certain point, the ful- 
 phur and the hydrogen combine equally with oxygen. 
 
 If fulphuric or muriatic acids be poured upon a hy- 
 drofulphuret after it has been for fome time cxpofed to 
 the air, a quantity of fulptuirated hydrogen gas exhales, 
 fulphur is depofited, and after an interval of time fulplui- 
 rous acid is difengaged. It is therefore fulphurous, and 
 not fulpliuiic acid, which is formed while the liydro- 
 fulphuret fpontaneoufly abforbs oxygen. This acid, 
 however, is not perceptible till after a certain interval 
 of time when feparated from the hydrofulphuret by 
 means of an acid ; becaufe as long as it meets with ful-- 
 phurated hydrogen a reciprocal deconipofition takes 
 place. The oxygen of the acid combines with the hy- 
 drogen of the gas, and the fulphur of both is precipi- 
 tated. 863 
 
 Sulphurated hydrogen Is capable of combining with Metalline' 
 feveral of the metals, mercury', for inftaiu-e, aiui filver : Mdroful- 
 
 • • • . iihiirpt^ 
 
 It combines with the greater number of the metallic ox-' 
 ides, and forms hydiolulphurcts, on which the alkalies 
 have no adlion at the temperature of the atmofphere : 
 But concentrated acids combine with the oxides of thefe 
 hydrofulphurets, and feparate the fulphurated hydrogen 
 in the form of gas.. 
 
 In the greater number of thefe metallic oxide hydro, 
 fulphurets, the tendency which oxygen and hydrogen 
 have to combine occafions a partial deconipofition of 
 the fulphurated hydrogen, and brings the oxides nearer 
 to the metallic ftate. In fome of thele hydrofulphurets 
 part of the fulphur alfo combines with oxygen, and: 
 forms fulphuric acid. 
 
 The alkaline hydrofulphurets precipitate all the me- 
 tals from their combination with acids; they are there- 
 fore very valuable tefts of the prefence of metals in any 
 folution, as they do not precipitate any of the earths 
 except alumina and jargonia. The following Table ex- 
 hibits a view of the effeA of hydrofulphuret of potafs, 
 hydrogenous fulphuret of potafs, and water irapregna- 
 ted with fulphurated hydrogen gas, upon various me- 
 tallic folutions. 
 
 MetaUic
 
 590 
 
 CHEMISTRY. 
 
 Mctailic Solutions. 
 
 Solution of Hyt^rrgsnous Sul- 
 ihurci <)( Potdfs 
 
 Water inlp^e^;n^ted with Sul- 
 phuratcl Hydiojjeri Ga-.. 
 
 Hjdrofuljhuret of Potafs. 
 
 Green fulphat of 
 iron. 
 
 A black precipitate, which 
 becomes yellow by the con- 
 tad of the air. 
 
 
 A black precipitate. The 
 potafs feparatcd. 
 
 Red oxide of iron. 
 
 
 Becomes black. The liquor 
 remains very deep coloured 
 if there be an excefs of ful- 
 phurated hydrogen. 
 
 Becomes black. 
 
 Sulpliat of zinc. 
 
 A white precipitate. 
 
 A white precipitate. 
 
 A white precipitate. 
 
 Acetite of lead. 
 
 A white precipitate, which by 
 an addition becomes black. 
 
 A black precipitate. 
 
 A black precipitate. 
 
 Red oxide of lead. 
 
 
 Becomes black. 
 
 The potafs feparated. 
 
 Nitrat of bllmuth. 
 
 
 A black precipitate. 
 
 A black precipitate. 
 
 Oxide of bifinuth. 
 
 
 Becomes black. 
 
 - 
 
 Nitrat of filver. 
 
 A black precipitate. 
 
 A black precipitate. 
 
 A black precipitate. 
 
 Sulphat of copper. 
 
 A brown precipitate. 
 
 A black precipitate. 
 
 A black precipitate. 
 
 Green oxide of cop- 
 per. 
 
 
 Becomes black. 
 
 Separation of the potafs. 
 
 Nitrat of mercury. 
 
 In a great deal of water, a 
 brown colour. 
 
 A brownifh black precipi- 
 tate. 
 
 A browniih black precipi- 
 tate. 
 
 Oxy-muriat of mer- 
 cury. 
 
 A white precipitate, which 
 becomes black by addition. 
 
 A white precipitate, beco- 
 ming black by an addition. 
 
 White, becomes black by ad- 
 dition. 
 
 Red oxide of mer- 
 cury. 1 
 
 
 Blackifh. 
 
 A heat produced which cau- 
 fedthehydrofulphurettoboil. 
 The alkali feparated (a). 
 
 Muriat of tin. 
 
 
 
 A black precipitate. 
 
 Oxy-muriat of tin. 
 
 A precipitation of fulphur, 
 and of the oxide. 
 
 No change. 
 
 A precipitate of white oxide 
 of tin, and a difengagement 
 of fulphurated hydrogen gas. 
 
 White oxide of tin. 
 
 
 No change. 
 
 Difengagement of fulphura- 
 ted hydrogen gas. 
 
 Sulphat of manga- 
 nefe. 
 
 
 No change. 
 
 A white precipitate. 
 
 Black oxide of man- 
 , ganefe. 
 
 
 The odour difappears. An 
 excefs of the water diflblves 
 the oxide. 
 
 Ammonia difengaged. Heat. 
 The liquor boils (a). 
 
 Nitrat of antimony. 
 
 
 
 A reddifh orange precipitate. 
 
 Tartrite of antimo- 
 ny. 
 
 A yellow orange precipitate. 
 
 An orange colour, but no 
 precipitate. 
 
 An orange red precipitate, 
 rediflblved by an excels of 
 hydrofulphuret. 
 
 White oxide of an- 
 " timouy. 
 
 
 Becomes yellow after fome 
 feconds. 
 
 Theliquor lofes its colour(A). 
 
 Fart III, 
 
 HydrofuJ. 
 
 phureiit 
 
 Metallic 
 
 (a) In thefe, hydrofulphuret of ammonia was ufed inftead of hydrofulphuret of potafs.
 
 Part III. 
 
 CryilaUiza. 
 
 CHEMISTRY. 
 
 Table continued. 
 
 391 
 
 CryflaUiw- 
 
 tion. 
 < >r— » 
 
 Metallic Solutions, 
 
 Soluiioii 1)1 Hydrogenous Sul- 
 phuret cf Poufs. 
 
 Water impregnated with Sul- 
 phuraieJ Hydrogen Gas. 
 
 Hydrofulphuretof Fotafs. 
 
 Oxide of antimony 
 lublimed. 
 
 
 Scarcely changes colour. 
 
 
 Solution of oxide of 
 arfenic. 
 
 Sulphuret decompofed as by 
 an acid. 
 
 Becomes fomewhat muddy, 
 and of a yellow colour. 
 
 A yellow colour, but no pre- 
 cipitate. 
 
 Sulphat of titanium. 
 
 
 
 A precipitate of a deep green. 
 
 Molybdic acid. 
 
 
 A brown precipitate. 
 
 A brown precipitate. 
 
 Chap. IV. 0/" Crystallization. 
 
 3«4 
 ery(la!s 
 
 8fiS 
 
 The word cryjlal, in its ftrift and proper fenfe, fig- 
 nifies a tranfparent body pofieiTed of a regular figure. 
 But it is now ufed to denote a body which has affumed 
 a regular figure whether it be tranfparent or not. Cry- 
 Jiati'f^iMtion is the atl by which this regular figure is 
 formed. 
 
 As the greater number of cryftals belong to the clafs 
 of neutral falts, it may not be improper, before we con- 
 clude this part of the article, to make a few obfervations 
 on the phenomena of cryftallization. 
 
 As cryftallization is confeftedly nothing elfe than the 
 regular arrangement of the particles of bodies, it is evi- 
 dent that before it can take place the particles of the 
 body to be cryftallized muft be at feme diftance from 
 each other, and that they muft be at liberty to obey tiie 
 laws of attraftion. They may be put into this fituation 
 by three methods, folution, fufpenfion, and fufion. 
 Farmed by '• Solution is the common method of cryftallizing 
 fblution, falts. They are dilTolved in water : The water is flow- 
 ly evaporated, the faline particles gradually approach 
 each other, combine together, and form fmall cryftals ; 
 which become conftantly larger by the addition of other 
 particles till at lalt they fall by their gravity to the bot- 
 tom of the vefTel. It ought to be remarked, however, 
 that there are two kinds of folution, each of which pre- 
 fents different phenomena of cryftallization. Some tails 
 diffolve in very fmall pi'oportions in cold water, but are 
 very foluble in hot water ; that is to fay, water at the 
 common temperature has little effeft upon them, hut 
 water combined with caloric diflblves them readily. 
 When hot water faturated with any of thefe falts cools, 
 it becomes incapable of holding them in folution : the 
 oonfequcnce of which is, that the faline particles gra- 
 duaUy approach each other and cryftalllze. Sulphat of 
 foda is a fait of this kind. To cryftalllze fuch falts, 
 nothing more is neceftary than to faturate hot ^water 
 with them, and fet it by to cool. But were we to at- 
 tempt to cryftalllze them by evaporating the hot water, 
 we ftiould not fucceed ; nothing would be procured but 
 a ftiapehf? mafs.- Many of the I'alts which follov; this 
 law of cryftallization combine with a great deal of wa- 
 ter ; or, which is the fame thing, many cryftals formed 
 in this manner contain a great deal of water of cryftal- 
 lization. 
 
 There are other falts again which are nearly equally 
 foluble In hot and cold water; common fait for inrtance. 
 It is evident that fuch falts cannot be cryftallized by 
 
 cooling ; but they cryftalllze very well by evaporating 
 
 their folution while hot. Thefe falts generally contain 
 
 but little water of cryftallization. 
 
 2. It appears, too, that fome fubftances are capable g„j-^._ 
 
 of afturaing a cryftalline form merely by having their 
 
 particles fufpended in water, without any regular folu.^ 
 
 tlon ; at leaft it is not eafy, on any other fuppofition, 
 
 to explain the cryftallizations of carbonat of lime foms- 
 
 times depofited by waters that run over quantities of 
 
 that mineral. 
 
 ■I. There are many fubftances, however, neither fo- » j 7. 
 , 1 1 • Li ri • r • 1 .• ■ , , And fu- 
 
 luble in water, nor capable 01 being io mmutely divided f,oii. 
 
 as to continue long fufpended in that fluid; and which, 
 notwithftanding, are capable of afluming a cryftalline 
 form. This is the cafe with the metals, with glafs, and 
 fome other bodies. The method employed to crvftaJ. 
 lize them \% fufion, which is a folution by means of ca- 
 loric. By this method the particles are feparated from 
 one another; and if the cooling goes on gradu^illy, they 
 are at liberty to arrange themfelves in regular cryftals. 
 There are many fubftances, howeirer, which it has been 
 hitherto impoflible to reduce to a cryftalline form, either 
 by thefe or any other method. Whether this be owing . 
 to the nature of thefe bodies themfelves, or to our ig- 
 norance of the laws by which cryftals are formed, as is ■ 
 much more likely, cannot be determined. 
 
 The phenomena of cryftallization feem to have at- ^ n ■,- 
 
 r> ! I I- 1 r L • r 1 • , .1 CrvflaUl--' 
 
 tratted but little or the attention ot the ancient philo- ztif'ion cr- - 
 fophers. Their theory>indeed, that the elements of bb- plained. 
 dies poflefs certain regular geometrical figures, m:iy 
 have been fuggefted by thefe phenomena ; but we are 
 ignorant of their having made any regular attempt to 
 explain them. The fchoolmen afcribed the regular fi- 
 gure of cryftals to their fubftantial forms, without orivlntr 
 themfelves much trouble about explaining the meaning 
 of the term. This notion was attacked by Boyle ; who 
 proved th.at cryftak were formed by the mere aggrega- 
 tion of particles *. But it ftlU remained to explain, . 
 why that aggregation took pjace ? and why the parti- „,l"r)r^„- 
 cles united in luch a manner as to form regular figures Jo/Tormjuri/ 
 Thefe queitions were anfwered by Newton. Accord-^'"''''", 
 ing to him, the aggregation is produced by the at- 
 traction which he had proved to exift between the par- 
 ticles of all bodies, and which afts as foon as tliefe 
 particles are brought within a certain diftance cf each 
 other by the evaporation of the liquid in v.-hich they are 
 diffolved. The regularity of their figures he exp!aine<I 
 by fuppofing, that while in a ftate of folution they were 
 arranged in the lic^uid iu regular rank and file; the con- 
 
 ftc^uencc-
 
 392 
 
 p. 363. 
 
 S69 
 Salts Ho 
 not eaCly 
 cryftallize 
 in clofe 
 wefiels. 
 
 870 
 And why. 
 
 871 
 Variety of 
 forms in 
 cryftals ac- 
 counted 
 for. 
 
 ♦ OftUs, 
 
 t-375- 
 
 C H E M 
 
 fequcnce of whicli, as they are afled upon by a power 
 whiiih at equal diftances is equal, at unequal diftances 
 unequal, will be cryltajs of determinate figures *. 
 
 This explanation, which is worthy of Newton, is 
 now univerfally admitted as the true one, and has con- 
 tributed much towards elucidating tJiis important part 
 of chemillry. 
 
 Still, liowevcr, there remain various' phenomena re- 
 lating to cryllallization, which it is no ealy matter to 
 explain. 
 
 It has been obferved, that thofe falts which crj'ftal- 
 lize upon cooling, do not alTume a cryilalline form fo 
 readily if they are allowed to cool in clofe veffels. If 
 a faturated folution of fulphat of foda, for inltance, in 
 hot water be put into a phial, corked up clofely, and 
 allowed to cool without being moved, no cryftals are 
 formed at all ; but the moment the glafs is opened, the 
 fait cryftallizes with fuch rapidity that the whole of the 
 folution in a manner becomes folid. This phenomenon 
 has been explained by fuppoiing that there is an affi- 
 nity between the fait and caloric, and that while the 
 xaloric continues combined with it the fait does not cry- 
 ftallize; that the caloric does not leave the fait fo readi- 
 ly when external air is not admitted, as glafs receives it 
 very (lowly and parts with it very (lowly. In ihort, 
 the atmofpherical air feems to be the agent employ- 
 ed to carry off the caloric ; a ta(k for which it is re- 
 markably well tltted, on account of the change of den- 
 fity which it undergoes by every addition ^)f caloric. 
 This is con(irmed-by the quantity of caloric which 
 always makes its appearance during tbefe iuddcn cry- 
 ftallizations. This explanation might be put to the 
 tell of experiment, by putting two (olutions of fulphat 
 of foda in hot water in two (unilar veflels; one of glafs, 
 the other of metal, and both clofed in the fame man- 
 ner. If the fait contained in the metallic vefTcl cry- 
 ftallized, which ought to be the cate on account of the 
 great conducting power of metals, while that in the 
 glafs velfel remained liquid, this would be a confirma- 
 tion of the theory, amounting almoil to demonftration. 
 On the contrary, if both folutions remained liquid, it 
 would be a proof that the phenomenon was ftill incom- 
 pletely underltood. 
 
 Not only falts, but water itfelf, which cymmonly cry- 
 ftallizes at 32", may be made to exhibit the fame phe- 
 nomenon : it may be cooled much lower than 152° with- 
 out freezing. This, as Dr Black has completely pro- 
 ved, depends entirely upon the retention of caloric. 
 
 If the regular form of cryftals depends upon the ag- 
 gregation of particles, and if during all cryftallizations 
 this aggregation goes on in the lame manner, why have 
 not all cryftals the fame form ? Some have afcribed 
 thefe differences to a certain polarity which the par- 
 ticles of bodies are fuppofed to poffefs, and which dif- 
 pofes each kind of particles to arrange themfelves ac- 
 cording to a certain law. Sir Ifaac ISIcwton appears ra- 
 ther to have afcribed it to the forms of the particles 
 themfelves f ; and this feems to be the real folution of 
 the problem. For fuppoiing that all particles have the 
 fame form, they muft of courfe poffefs the fame polari- 
 ty; and therefore every cryftal muft have the fame form. 
 It is impoflible, then, to account for the different forms 
 of cryftals without fuppofing that the particles which 
 compofe them have alio different forms. And if the 
 particles of bodies have different forms, their regular 
 
 I S T R Y. 
 
 Part in. 
 
 aggregation muft produce cryftals of various fhapcs ;Crynalliza. 
 and therefore their polarity, which is merely a fuppoli- """ 
 tion founded on this difference in the appearance of ' 
 cry(tals, cannot be admitted. Snppofe, for inftance, 
 that eight cubic particles were regularly arranged iu 
 water, and that by the gradual er'aporation of the li- 
 quid were to approach, and at laft to combine, it is 
 evident that the cryftal which they would produce- 
 would be a cube. Eight fix-lided prifms would alfo 
 produce a fix-fided prifm ; and eight tetrahedrons would 
 form a very difftrent figure. 
 
 But it will be adved, if the (igure of cryftals depends 
 entirely upon the form of the particles that compofe 
 them, how comes it that the fame fubftance does not 
 always cryftallize in the fame way, but prefents often 
 fuch a variety of forms that it is fcarcely poifible to 
 reckon them? We anfwer, that thefe various forms arc 
 f(tmetime8 owing to variations in the ingred^t.ts which 
 compofe the integrant particles of any particular body. 
 Alum, for inilance, cryftallizes in oftahcdions ; but 
 when a quantity of alumina is added, it cryftallizes in 
 cubes ; and when there is an excefs of alumina, it does 
 not cryftallize at all. It the proportion of alumina va- 
 ries between that which produces oftahedrons and what 
 produces cubic cryftals, the cryftals become figures with 
 fourteen fides ; fix of which are parallel to thofe of the 
 cube and eight to thofe of the oftahedron ; and ac- 
 cording as the proportions approach nearer to thofe 
 which form cubes or oftahedrons, the cryftals affume 
 more or lefs of the form of cubes or oftahedrons. What, 
 is ftill more, if a cubic cryftal of alum be put into a 
 folution that would afford oftahedral cryftals, it paffes 
 into an oftahedron : and, on the other hand, an oftahe- 
 dral cryftal put into a folution that would afford cubic 
 cryftals, becomes itfelf a cube *. Now, how difficult a » » •>, 
 matter it is to proportion the diilerent ingredients w\Xh/i„„, dt 
 abfolute exaftnefs, muft appear evident to all. CAira. xiv. 
 
 Another circumttance which contributes much to va- '49- 
 ry the form of cryftals, is the different degree of con- 
 centration to which their folution has been reduced, and 
 the rapidity or flownefs with which they are fonned. 
 For it is too evident to require illuftration, that when 
 cryftals are depofited very rapidly they muft obftruft 
 one another, and mix together fo as very much to ob- 
 fcure the natural regularity of their form. 
 
 Even the nature of the veffel in which the cryftalliza- 
 tion is performed is not without fome influence. 
 
 But, independent of thefe accidental circumftances, p, 7* 
 Mr Hauy has fhewn that every particular fpecies o^niyoioi 
 cryftals has a primitive figure, and that the variations ftals. 
 are owing to the different ways in which the particles 
 arrange themfelves. Of this theory, which is certainly 
 exceedingly ingenious, and even fatisfaftory, we fliall 
 attempt to give a fhort view. 
 
 Happening to take up a hexangular prifm of calca- 
 reous fpar, or carbonat of lime, which had been detached 
 from a group of the fame kind of cryftals, he obferved 
 that a fmall portion of the cryftal was wanting, and that 
 the frafture prefented a very fmooth lurface. Let abcde 
 fgh (fig. 8.) be the cryftal; the frafture lay obliquely as 
 the trapezium /I J u /, and made an angle of 135°, both 
 with the remainder of the bale abcs ph and with tuef, the 
 remainder of the fide i n ef. Obferving that the fegment 
 ps u /in thuscut off had for its vertex in, one of the edges 
 of the bafe abcnih of the prifm, he attempted to detach 
 
 a
 
 Part. 111. CHEMISTRY. 393 
 
 Cryllalliza- a fimilar fepment in the n.irt to which the next edge may alfo be divided by fe£l'ons parallel to the fiiTcs of Cryflj|lu»- 
 '■'""■ ^ c n belonged, employed for that purpol'e the blade of the primitive cryllal. It follows from this, that the , "°"" . 
 * a knife, direfted in the fame degree of obliquity as the parts detached by means of thefe fedlions are finiilar, ' 
 trapezium^ s u t, and afTifted by the ftrokes of a ham- and differ from one another only in fize, which dimini- 
 mer. He could not fucceed : But upon making the flies in proportion to the length that the divjfion is car. 
 attempt upon the next edge be, he detached another ried. But the divifion of the cryftals into fimiiar foljds 
 fegmcnt, precifcly fimilar to the firft, and which had for has a term, beyond which we iTiOuld come to the fmblU 
 its vertex the edge b c. He could produce no effeft on eft particles' of the body, which could not be divided 
 the next edge a b ; but from the next following, a h, without chemical decompofition. It is probable, there- 
 lie cut a fegment fimilar to the other two. The fixth fore, that the form of the integrant particles of a body 
 edge likewife proved refraftory. He then went to the is the fame with the primitive form of its cryftals. Here 
 other bafc of the prifm d efg h r, and found, that the then, we have a method of difcovering the form of the 
 edges which admitted fedlions fimilar to the preceding particles of bodies ; and if this method could be applied 
 ones were not the edges e f, d r, g k, correfponding vi'itli to all fubftances whatever, it would enable us to afcer- 
 thofe which had been found divifible at the oppofite tain the af&nity of all bodies for each other by accurate 
 bafe, but the intermediate edges d e, k r, gf. The tra- calculation. It muft be allowed that feveral objeftiong 
 pezium I qy v reprefents the feftion of the fegment, might be made to the conclufions of Mr Hauy ; but his 
 which had i r for its vertex. This feftion was evident- theory is, on the whole, fo plaufible, that it would cer- 
 ly parallel to the feftion^ s u t ; and the other four fee- tainly be worth while to extend it, and rpply it to the 
 tions were alfo parallel two and two. Thefe fcdions calculation of affinities as far as it is fufceptible of the 
 were, without doubt, the natural joinings of the layers application. If the cryftals obtained by the above pro- 
 of the cryftal. And he eafily fucceeded in making cefs be the primitive forms, it becomes a queftion of 
 others parallel to them, without its being pofllble for fome confequence to determine in what manner the fe- 
 him to divide the cryftal in any other direction. In condary forms are produced. 
 
 this manner he detached layer after layer, approaching According to Hauy, all the parts fuperadded to the 
 
 always nearer and nearer the axis of the prifm, till at primitive cryftals, in order to form the fecondaiy cry- " 
 
 laft the bafes difappeared altogether, and the prifm was ftal, con fift of plates, which decreafe regularly by the 
 
 converted into a iolid OX (fig. 9.), terminated by fubtraftion of one or more rows of integrant particles, 
 
 twelve pentagons, parallel two and two ; of which in fuch a manner, that the number of thefe ranks, and 
 
 thofe at the extremities, that is to fav, ASRIO, IG confequently the form of the fecondarv cryftal, may be 
 
 EDO, BAODC at one end, and FKNPQ^MNPXU, determined by theory (c). 
 
 ZQPXY at the other, were the refults of mechanical To explain this, let us fuppofe that EP (fig. 12.) re- 
 
 divifion, and had their common vertices O, P fituated prefents a dodecahedron, terminated by equal and fimi- 
 
 at the centre of the bales of the original prifm. The lar rhombs ; that this dodecahedron is a fecondary cry- 
 
 fix lateral pentagons RSUXY, ZYRIG, &c. were the ftal, the primitive form of which is a cube : the fitua- 
 
 remains of the fix fides of the original prifra. tion of this cube in the dodecahedron may be conceived 
 
 By continuing feftions parallel to the former ones, from fig. 13. The fmaller diagonals DC, CG GF, 
 
 the lateral pentagons diminilhed in length; and at laft FD, of four fides of the dodecahedron, united round 
 
 the points R, G coinciding with the points Y, Z, the the fame folid angle L, form the fquare CDFG. Now 
 
 points S, R with the points U, Y, &c. there remained there are fix folid angles, compofed of four plains, to- 
 
 nothing of the lateral pentagons but the triangles YIZ, wit, the angles L, O, E, N, R, P (fig. 12.) ; and con- 
 
 UXY, &c. (fig. 10.). By continuing the fame fee- fequently, by making feftions through the fmaller dia. 
 
 tions, thefe triangles at laft difappeared, and the prifm gonals of the fides that form thefe angles, fix fquares 
 
 was converted into the rhomboid a f (fig. ir.). will be made apparent, which are the fix fides of the 
 
 So unexpefted a refult induced him to make the primitive cube, three of which are reprcfented in fig 13 
 
 fame attempt upon more of thefe cryftals ; and he found CDFG, ABCD, BCGH. 
 
 that all of them could be reduced to fimilar rhomboids. This cube being compofed of cubic integrant parti- 
 He found alfo, that the cryftals of other fubftances cles, each of the pyramids, LCDFG for inftance (fiir. 
 could be reduced in the fame_ manner to certain prinii- 13.) which repofe upon its fides, muft alfo, accordin^j 
 tive forms ; always the fame in the fame fubftances, but to the theory, be compofed of fimilar cubic ■jarticles. 
 every fubftance having its own peculiar form. The To make this appear, let us fuppofe that ABFG (fig! 
 primitive form of flnat lime, for inftance, was an oc- 14.) is a cube compofed of 72c; fmall cubes: Each of 
 tahedron ; of fulphat of barytes, a prifm with rhomboi- its fides will confift of Si fquares, being the external 
 dal bafes; of field-fpath, an oblique angled parallelopi- fides of as many cubic particles, which together con- 
 ped, but not rhomboidal ; of adamantine fpar, a rhom- ftitute the cube. Upon ABCD, one of the fides of 
 boid, fomevvhat acute; of blende, a dodecahedron, with this cube, let us apply a fqiiare lamina, compofed of 
 rhomboidal fides ; and fo on. cubes equal to thofe of which the primitive cr'y'ftal con- 
 
 Thefe muft be confidered as the real primitive forms fifts, but which has on each fide a row (.f cubes lefs 
 
 of the cryftals; the other forms which they often af- than the outcrmoft layer of the primitive cube It will 
 
 fume maybe c-<XitA fecondary forms. of courfe be compofed of 49 cubes, " on each fide • fo 
 
 The primitive cryftals obtained by the above procefs that its lower bafe nfg (fig. ly.) Will fall exactly on 
 
 maybe divided by feftions parallel to their different fides : the fquare marked with the fime letters in fig, 1 4.. 
 alUhe matjier which^ furrounded this primitive cryftal Above this lamina let us apply a fccond / m p «'(fig. 
 
 l'^ 16.)'. 
 
 SvFfL. Vol. I. Part I. 
 
 (c) The explanation of Bergman is not very different. See his Opii/c vol. II. di/T. 
 
 I.
 
 594 
 
 CHEMISTRY. 
 
 Cryftalliza- 16.), compofed of JJ cubes ; it will be fituated exadly 
 »'on^ ^ above the fqiiare marked with the fame letters (tig. 
 ' 14.) Upon this fecond let us apply a third lamina 
 
 V X ji a (fig. 17.) confiftiug only of 9 cubes ; fo that 
 its bafe fliall reft upon the letters "y .v ^ z (fig. 14.). 
 LatUy, on the middle fqiiare r let us place the fmall 
 cube r (fig. 18), which will reprefent the lad lamina. 
 
 It is evident, that by this procefs a quadrangular py- 
 ramid has been formed upon the face ABCD (fig. I4.)> 
 the bafe of which is this face, and the vertex the cube 
 r (fig. 18.). By continuing the fame operation on the 
 other five fides of the cube, as many fimilar pyramids will 
 be formed ; which will envelope the cube on every fide. 
 It is evident, however, that the fides j)f thefe pyra- 
 mids will not form continued planes, but that, owing to 
 the gradual diminution of the lamina; of the cubes which 
 compofe them, thefe fides will refemble the fteps of a 
 ftair. We can fuppofe, however (what muft. certainly 
 be the cafe), that the cubes of which the nucleus is 
 formed are exceedingly fmall, almoll imperceptible ; 
 that therefore a vaft number of laniiiis: are required to 
 form the pyramids, and confequently that the channels 
 which they form are imperceptible. Now DCBE (fig. 
 19.) being the pyramid relling upon the face ABCD 
 (fig. 14.), and CBOG (fig. 19.) the pyramid applied 
 to the next face BCGH (fig. 14.), if we confider that 
 every thing is uniform from E to O (fig. 19.) in the 
 manner in which the edges of the lamina of fuperpofit'wn 
 (as the Abbe Hauy calls the lamiiix which compole the 
 pyramids) mutually projed beyond each other, it will 
 readily be conceived, that the face CEB of the firll 
 pyramid ought to be exaftly in the fame plane with the 
 face COB of the adjacent pyramid ; and that therefore 
 the two faces together will form one rhomb ECOB. 
 But all the fides of the fix pyramids amount to 24 tri- 
 angles fimilar to CEB ; confequently they will form I2 
 rhombs, and the figure of the whole cryllal will be a do- 
 decahedron, fimilar to that reprcfented in ng. 12 and 13. 
 If the decreafe of the laminae of fuperpofition took 
 phce according to a more rapid law, if each hmina 
 had on its circumference two, three, or four rows of 
 cubes lefs than the inferior lamina — in that cafe, the 
 pyramids produced being lower, their adjacent faces 
 ■K-ould no longer form one plane; and therefore the fur- 
 face of the fecondary cryftal would confitl of 24 ifo- 
 fceles triangles, all inclined towards each other. 
 
 In this manner Mr Hauy has {hewn, that a variety 
 of fecondary cryftals are formed, and that their forms 
 vary by means of flight variations in the ratio of the 
 decrement. Dodecahedral fulphurct of iron, for inftance, 
 is formed from a cubic nucleus, by the addition of la- 
 minx, decreafing, as in the example given above, with 
 this difference, tliat from every lamina laid upon the 
 face ABCD (fig. 14) only one row of cubes are fub- 
 tracled at the fides AD and BC refpeftively ; whereas 
 two rows are fubtrafted at each of the fides AB and 
 CD. The confequence of this more rapid decrement 
 on two parallel fides than on the other two will be, 
 that the pyramid raifed on the face ABCD (fig. 14-), 
 inftead of terminating in a fingle cube as in the ex.imple 
 given above, will terminate in a range of cubes ; or 
 (fwppofing the cubes infinitely fmall) inftead of termi- 
 nating in a point, it will terminate in a ridge. The 
 pyramid will therefore have for its two fides, contigu- 
 ous to AB and DC, two trapeziums, and for its fides, 
 
 ^ Part lir, 
 
 contiguous to AD and BC, two triangles. Let usCryftalliza. 
 fuppofe alfo, that with regard to the lamins of fuper- ^^_ 
 pofition which arife on the face BCGH (fig. 14.), the 
 decrements follow the fame law, and that each lamina 
 decreafes by two rows of cubes towards the lines BC 
 and HG, and only by one row towards the lines CG, 
 BH : The pyramid, in that cafe, will be placed in a 
 direction oppofite to the pyramid on ABCD, the ridge 
 at the vertex of it running parallel to BC : the vertex 
 of the pyramid raifed upon CDFG muft be parallel to 
 CG: the pyramids on the three other fides of the cube 
 ought to Hand each like that which arifes on the op- 
 pofite face. 
 
 The fides of all the fix pyramids thus formed amount 
 to twelve trapeziums and twelve triangles. Every tri- 
 angle is evidently contiguous and in the fame plane 
 with a trapezium of the ntareft pyramid ; confequently 
 the fecondary cryftal thus formed confifts of twelve 
 fides, each of which is a pentagon. 
 
 Several other examples have been given by Mr Hauy; 
 but thefe are fufficieiit to (liew in what manner the va- 
 rious fecondary forms of cryftals are conftrucled, ac- 
 cording to the theory of that ingenious philofopher. 
 
 In his refearches on this fubjeft, Mr Hauy percei- 
 ved, that fome cryftals aflTumed fecondary forms which 
 could not be accounted for by any decrement whatever 
 along the edges. Thus, for inftance, fome bodies, the 
 primary form of which is cubic, are fometimes found 
 cryftallized in regular oftagons. Mr Hauy explains 
 the formation of thefe fecondary cryftals, by fuppofing 
 that the decrement took place parallel, not to the edges, 
 but to the diagonals of the faces of the primary cubes. 
 In order to comprehend this, let us fuppofe ABCD 
 (fig. 20.) to be the furface of a lamina compofed of 
 fmall cubes, the bafes of which are leprefentcd by the 
 little fquares in the figure. It is evident, that the cubes 
 a, h, f, d, e,f, g, h, i, are in the diredllon of the diago- 
 nal of the fquare ABCD ; that the row of cubes y, v, 
 i, u, x,y, c, is parallel to the diagonal ; as alfo the row 
 n, t, I, VI, p, 0, r, s ; and that the whole figure might 
 be divided into rows of fquares, each of which would 
 be parallel either to the diagonal AC or DB. 
 
 Now wc may conceive that the lair.ina; of fuperpo- 
 fition, inftead of decreafing by rows of cubes parallel to 
 the edges AB, AD, decreafe by rows parallel to the 
 diagonals. 
 
 Let it be propofed to conftruft around the cube AB 
 GF (fig. 21.), confidcrcd as a nucleus, a fecondary fo- 
 lid, in which the laminas of fuperpofition (hall decreafe 
 on all fides by fingle rows of cubes, but in a direftion 
 parallel to the diagonals. Let ABCD (fig. 22.), the 
 fuperiur bafe of the nucleus, be divided into 81 Iquares, 
 reprefeiiting the faces of the fmall cubes of which it is 
 ciimpofed. Figure 23. reprefents the fuperior furface 
 of the firft lamina of fuperpofition ; which muft be 
 placed above ABCD (fig. 22.) in fuch a manner that 
 the points a', V, c' , d', (fig. 23.) anfwer to the points 
 a, b, Cy d, (fig. 22.). By this difpofition the fquares 
 A a, 'Bb,Cc,'Dd (fig. 22.), which compofe the four 
 outermoft rows of fquares parallel to the diagonals AC^ 
 BD, remain uncovered. It is evident alfo, that the 
 borders QV, ON, IL, GF (fig. 23.), projeA by one 
 range beyond the borders AB, AD, CD, BC (fig. 
 .22.), which is neceflary, that the nucleus may be en- 
 veloped towards thefe edges ; For if this were not the 
 
 cafe.
 
 Tart in. 
 
 C H E M 
 
 Cryftalti^a. cafe, re-entd !nj^ angles would be formed towards tlie 
 tion. pa,.ts AB, BC, CD, DA, of the ciyllal; which angles 
 » appear lo be excluded by the laws which determine the 
 
 formation of fimplc crylUls, or, wliich comes to the 
 fame thing, no fuch angles are ever oblervtd in any cry- 
 ftal. The folid mull iucrcafe, then, in thofe parts to 
 which th-' decrement does not extend. But as this de- 
 crement is alone fufiicient to determine the form of the 
 fecondary cryftal, we inay fet afide all the other varia- 
 tions which intervene only in a fubfidiary manner, ex- 
 cept when it is wilhed, as in the prefent cafe, to con- 
 ftruft artificially a folid reprefentation of a cryftal, and 
 to exhibit all the details which relate to its ftruftiire. 
 
 The fnperior face of the fecond lamina will be A' 
 G'L'K' (fiij. 24. )• It miift be placed fo that the points 
 a", i",c", (^", correfpord to the pointsa 1/ c' d (fig. 23. j, 
 •which will leave uncovered a iecond row of cubes at 
 each angrle parallel to the diagonals AC and BD. 
 The folid ftill increafes towards the fides. The large 
 faces of the lamina: of fuperpofilion, which in fig. 23. 
 were oftagoiis, in fig. 24. arrive at that ot a fquare ; 
 and when they pafs that term they dccreafe on all 
 fides ; fo that the next lamina has for its fupcvior face 
 the {'unare B'M L'S' (fig. 25), lefs by one range in 
 every diredlion than the preceding Umina (fig. 24.). 
 This fquare muft be placed fo that the points e',f,g', //, 
 (fig. 25.) correfpond to the points e,f,g, h (fig. 24.). 
 Figures 26, 27, 28, and 29, reprefent the tour lamiiix 
 which ought to rife fucceffively above the preceding ; the 
 manner of placing them being pointed out by corre- 
 fponding letters, as was done with refpeft to the three 
 firll laminjE. The lafl lamina a' (fig. 30. ) is a fingle cube, 
 which ought to be placed upon the fquare a (fig. 29.). 
 
 The iaminx of fuperpofition, thus applied upon the 
 fide ABCl) (fig. 22.), evidently produce four faces, 
 which correfpond to the points A, B, C, D, and form 
 a pyramid. Thefe facts, having been formed by Iaminx, 
 which began by incrcafing, and afterwards decreaied, 
 mufl be quadrilaterals of the figure reprefented in fig. 
 31. ; in which the inferior angle C is the fame point 
 with the angle C of the nucleus (fig. 21. and 22.) ; 
 and the diagonal LQ^reprefents L'G' of the lamina 
 A'G'L'K' (fig. 24.). And as the number of Iaminx 
 compofing the triangle L Q_C (fig. 31.) is much 
 fmaller than that of the Iaminx forming the triangle 
 ZLQ. it is evident that the latter triangle will have a 
 much greater height than the former. 
 
 The furface, then, of the fecondary cryftal thus pro- 
 duced, muft evidently confift of 24 quadrilaterals (for 
 pyramids are raifed on the other 5 fides of the primary 
 cube exaftly in the fame manne"-), difpofed 3 and 3 
 around each folid angle of the nucleus. But in confe- 
 quence of the decrement by one range, the three qua- 
 drilaterals which belong to each folid angle, as C (fig. 
 21.) will be in the fame plane, and will form an equila- 
 teral triangle ZIN (fig. 32.). The 24 quadrilaterals, 
 then, will produce 8 equilateral triangles ; and confe- 
 quently the fecondary cryftal will be a regular oftagon. 
 This is the ftrufture of the oftahedral fulphuret of lead 
 and of muriat of foda. 
 
 Decrements which take place in this manner have 
 been called by Mr Hauy decrements on the angles. 
 
 There are certain cryftals in which the decrements 
 on the angles do not take place in lines parallel to the 
 diagonals, but parallel to lines fituated between the dia- 
 
 39." 
 
 1 S T R Y. 
 
 gonals and the edges. This ik tl-.e cafe when the fub- Cryftalliza- 
 tradfions are made by ranges of double, triple, &c. , "" "- 
 moleculx. Fig. 33. exhibits an inftance of the ftib- '''" 
 trattions in qucftion ; and it is feen that the mole- 
 culx wliieh compofc the range reprefented by that fi- 
 gure are aflorted in fuch a manner as if of two there 
 were formed only one ; fo that we need only to con- 
 ceive the cryftal compofed of parallelopipedons having 
 their bafes equal to the fmall rectangles a I c d, e dfg, 
 h g i I, &c. to reduce this cafe under that of the com- 
 mon decrements on the angles. To this particular 
 kind of decrement Mr Hauy has given the name of in~ 
 iermediale. 
 
 In other cryftals the decrements, either on the edges 
 or on the angles, vary according to laws, the proportion 
 of which cannot be expreffcd but by -the fraftion i. or 
 \. It may happen, for example, that each himina ex- 
 ceeds the following by two ranges parallel to the edges, 
 and that it may at the fame time have an altitude triple 
 that of a fimple molecule. Figure 34. rci)refents a ver- 
 tical geometrical feftion of one of the kinds of pyramids 
 which would refult from this decrement ; the effett of 
 which may be readily conceived, by confidering that AB 
 is a horizontal line taken on the uppei- bale of the nu- 
 cleus, b a ^ r the feftion of the fufl lamina, of fuperpo- 
 fition, gfen that of the fecond, &c. Thefe decrements 
 Mr Hauy has called mixed. 
 
 Thefe two laft fpccies of decreqients occur but rarely; 
 Mr Hauy found them only in certain metallic fubflances. 
 All the mctamorphofes to which cryftals are fubjttt- 
 ed depend, according to Mr Hauy, on the laws of 
 itrudure jult explained, and others of the like kind. 
 Sometimes the decrements take place at the fame time 
 on all the edges; as in the dodecah'-drou having rhom- 
 bufes for its planes, as before mentioned ; 01 on all the 
 angles, as in the odfahedron originating from a cube. 
 Sometimes they take place only on certain edges or 
 certain angles. Sometimes there is an uniformity be- 
 tween them ; fo that it is one fingle law by one, two, 
 three ranges, &c. which adls on the different edges, or 
 the different angles. Sometimes the law varies from 
 one edge to the other, or from one angle to the other; 
 and this happens above all when the nucleus has not s 
 fymmetrical form ; for example, when it is a parallelo- 
 pipedon, the faces of which diflFer by their refpeftive 
 inclinations, or by the meafure of their angles la 
 certain cafes the decrements on the edges concur 
 with the decrements on the angles to produce the fame 
 cryftalline form, it happens alfo fometimes that the 
 fame edge, or the fame angle, is fubjeded to feveral 
 laws of decrement that fucceed each other. In ftiort, 
 there are cafes where the fecondary cryftal has faces pa- 
 rallel to thofe of the primitive form, and which combine 
 with the faces produced by the decrements to modify 
 the figure of the cryftal. 
 
 The cryftals arifing from a fingle law of decrement 
 have been called by Mr H&uy fimple fecondary forms ; 
 tbofe which arife from feveral fimultaneous laws of de- 
 crement he has called compound fecondar^^ forms. 
 
 " If amidft this diverfity of laws (he obferves), fome- 
 times infulated, fometimes united by combinations more 
 or lefs complex, the number of the ranges fubtradled 
 were itfelf extremely variable ; for example, were thefe 
 decrements by twelve, twenty, thirty, or forty ranges» 
 or more, as might abfolutely be poflible, the multitude 
 Dd 3 of
 
 396 
 
 tr)nali;: 
 
 CHEMISTRY. 
 
 Part Iir, 
 
 a of the forms which might exift in each kiiiJ of mineral 
 would be immeiifc, and exceed what could be imagined. 
 "" Bat the power which elTccts the fubt raft ions fecms to 
 have a very limited aftiun. Thefe fubtractions, for the 
 moil part, take place by one or two ranges of molecules. 
 1 have found none which exceeded four ranges; except 
 in a variety of calcareous fpar, forming part of the col- 
 leftionof C. Gillet Laumoiit, the ftrufture of which de- 
 pends on a decrement by fix ranges ; fo th.it if there exift 
 laws which exceed the decrements by foar ranges, there 
 is reafon to believe that they rarely take place in nature. 
 Yet, notwithilanding thefe narrow limits by which the 
 laws of cryftallization are circunifcribed, I have found, 
 by confining myfelf to two of the fimplcll laws, that is 
 to fay, thole which produce fiibtraftions by one or two 
 ranges, that calcareous fpar is fiifceptible of two thou- 
 fand aud forty-four different forms: a number which 
 exceeds more than fifty times that of the forms already 
 known ; and if we admit into the combination decre- 
 ments by three and four ranges, calculation will give 
 8,388,604 poflible forms in regard to the fame fubftance. 
 This number may be dill very much augmented in con- 
 fequence 01 decrements either mixed or intermediary. 
 
 " The itriae remarked on the furface of a multitude 
 of cryftals afford a new proof in favour of theory, as 
 they always have direilions parallel to the projecting 
 edges of the laminae of fuperpofition, which mutually 
 go beyond each other, unlefs they arife from fome par- 
 ticular want of regularity. Not that the inequalities 
 refulting from the decrements muft be always fenfible, 
 fuppofing the form of the cryftals had always that degree 
 of finifhing of which it is fufceptlble; for, on account of 
 the extreme minutenefs of the molecules, the furface 
 would appear of a beautiful polifh, and the flriae would 
 elude our fenfcs. There are therefore fccondary cry- 
 ftals where they are not at all obferved, while they 
 are very vifible in other cryftals of the fame nature 
 and form. In the latter cafe, the aftion of the caufes 
 •which produce cryftallization not having fully enjoyed 
 all the conditions neceffary for perfefting that fo deli- 
 cate operation of nature, there have been ftarts and in- 
 terruptions in their progrefs, fo that, the law of conti- 
 nuity not having been cxaftly obferved, there have re- 
 mained on the furface of the cryftal vacancies apparent 
 to our eyes. Thefe fmall deviations are attended with 
 this advantage, that they point out the direction accord- 
 ing to which the ftris are arranged in lines on the perteft 
 forms where they efcape our organs, and thus contri- 
 bute to unfold to us the real mechanifm of the ftrutlure. 
 " The fmall vacuities which the edges of the lamlnse 
 of fuperpofition leave on the furface of even the moft per- 
 fect fecondary cryftals, by their re-entering and falient 
 angles, thus afford a fatisfaftory folution of the difficul- 
 ty a little before mentioned ; which is, that the frag- 
 ments obtained by divifion, the external fides of which 
 form part of the faces of the fecondary cryftal, are not 
 like thofe drawn from the interior part. For this di- 
 veiCty, which is only apparent, arifes from the fides 
 in queftion being compoftd of a multitude of fmall 
 planes, really inclined to one another, but which, on 
 account of their fmallnefs, prefent the appearance of 
 one plane ; fo that if the divifion could reach its utmoft 
 bounds, all thefe fragments would be refolved into mole- 
 cules fimilar to each other, and to thofc fituated to- 
 wards the centre. 
 
 " The fecundity of the laws on which the variations Ciyftalliza. 
 of cryftalline forms depend, is not confined to the ''""• 
 producing of a multitude of very different forms with " » "* 
 the fame molecules. It otten happens alfo, that mole- 
 cules of different figures arrange themlelves in fuch a 
 manner as gives rife to like polyhcdra in different kinds 
 of minerals. Thus tlie dodecahedron with rhombufes 
 for its planes, which we obtained by combining cubic 
 molecules, exifts in the granite with a ftrufture com- 
 pofed of fmall tetrahedra, having ifofceles triangular 
 faces ; and I have found it in fparry fluor (fiuat of 
 lime), where there is alfo an affemblage of tetrahedra, 
 but regular ; that is to fay, the faces of which are equi- 
 lateral triangles. Nay more, it is poflible that finiilar 
 molecules may produce the fame cryftalline form by dif- 
 ferent laws of decrement. In fhort, calculation has 
 condufted me to another refult, which appeared to me 
 ftill mo*'e remarkable, which is, that, in conlequcnce of 
 a fimple law of decrement, there may exill a cryftal 
 which externally has a perfeft refemblance to the nu- 
 cleus, that is to fay, to a fohd that does not arife from 
 any law of decrement *." * Ann. de 
 
 Cbint. xvii.- 
 
 SucH Is a fhort view of the theory by which Mr**^* 
 Hauy explains the various cryftalline forms of the 
 fame fubftance. We would with pleafure have entered 
 more into detail, had not moft of his examples been 
 deduced from fubftances which belong rather to mi- 
 neralogy than to the elements of chcniiftry. Thij 
 theory, to fay no more of it, is, in point of ingenuity, 
 inferior to few ; and the mathematical flciU and iuduftry 
 of its author are intitled to the greateft applaule. 
 
 But what we confider as the moft important part of 
 that philofopher's labours, is the method which they 
 point out of difcovering the figure of the integrant 
 particles of cryftals; becaufe it may pave the way for 
 calculating the affinities of bodies, which is certainly by 
 far the moft important part of chemiftry. This part of 
 the fuDJeft, therefore, deferves to be inveftigated with 
 the greateft care. 
 
 Mr Hauy has found, that the primitive form of all 
 the cryftals which lie has examined may be reduced to 
 fix; I. The parallelopipedon in general, comprehending 
 the cube, the rhomboid, and all lolids terminated by fijc 
 fides parallel two and two; 2. Tlie regular tetrahedron ; 
 ^. The oftahedron with triangular fides ; 4. The hex- 
 agCTUil prifm ; 5. The dodecahedron bounded by 
 rhombs ; 6. The dodecahedron bounded by ifofceles 
 triangles. Were we to fuppofe that thefe primitive 
 forms are exaftly fimilar to the form of the integrant 
 particles which compofe them, it would follow, that the, 
 integrant •particles of all the cryftals hitherto formed 
 have only fix different forms. This fuppofition, how- 
 ever, is not probable ; becaufe the fame nucleus has 
 been difcovered in different fpecies of minerals, and be- 
 caufe we can eafily conceive integrant particles of diffe- 
 rent forms, combining in fuch a manner as to compofe 
 nuclei of the fame figure, juft as we have feen that dif- 
 ferent primitive forms are capable of producing the fame 
 fecondary form. Still, therefore, in endeavouring todifco- 
 ver the integrant particlea of bodies, there are difficulties 
 to remove, which hitherto, at leaft, have been unfurmount- 
 able. But the theory of Mr Hauy may be confidered as 
 a firft ftep towards the difcovery ; and Sijiep in refearches. 
 of fo difficult a nature is of very great confequence. 
 
 We
 
 Partlir. 
 
 C H E M I 
 
 Con.lufion. We have now fini'died the three firft parts of this av- 
 '—"y' — ' tide, which comprehend all the elementary part ot ehe- 
 miftry. We ought now to proceed to the fourth part, 
 which was to confift of a chemical examination of luh- 
 ilances as tliey exift in nature in the mineral, vegetable, 
 and animal kingdoms; but this, for various reafons, we 
 fhall defer till we come to the words Mineralogy, 
 and Animal and Vegetable Subst/inces. 
 
 We fliall finifli this article with a few remarks upon 
 the chemical nomenclature, which for fome time pafl 
 has been an objeft of ferious attention. 
 
 Chemiftry was unfortunately firft cultivated by a fet 
 of ignorant men, filled with the higheft notions of their 
 own importance, and buoyed up with the mighty feats 
 iner,c!ature.^^,j,j^i, ^jigy ^^yg to perform by their art. The little 
 which they did know they were anxious to conceal; and 
 their anxiety was no lefs to infpire the vorld with high 
 ideas of their knowledge and power. The confequence 
 of this was, that they loaded chemiftry with the moll ri- 
 diculous and whimfical names that can well be conceived. 
 Liver of fulphur, mercury of Ife, horned moon, butler of 
 antimony, the double fecret, the corraline fecrct, the fecret 
 of vitriol, the wonderful fait, the fecret fall, the fait tviih 
 many -virtues, the fill of two ingredients, the foliated earth 
 
 873 
 Remarks 
 on the che 
 niciil no- 
 
 S T R y. ' 397 
 
 1 . livery fubftance ought to have a nsme, and not to Condufion. 
 be denoted by a phrafc. »— y— j 
 
 2. Names ought to be as much as pofiible conformable 
 to the nature of the things lignified by them. 
 
 3. When the character ot a fubftance is not well 
 enough known to determine the denomination, a name 
 which has no meaning is preferable to one which con- 
 veys a falie idea. 
 
 4. In the choice of new words thofe ought to be pre- 
 ferred which have their roots in the dead languages 
 moft generally known, that the word may be eafily fug- - 
 gefted by the ftnfe, and the fenfe by tlie word. 
 
 5. The new words ought to be as fuitablc as poflible 
 to the genius of the languages for which they are formed. 
 
 This nomenclature was approved of by Macquer, and 
 by Bergman, who had himfclf propofed one upon a plan 
 not very different (d). He wrote to Morveau, and ex- . 
 horted him to profecute his undertaking with courage. 
 " Do not fpare (fays he) a fingle improper denomina- 
 tion ; thofe that are already learned will be always fo, 
 and thofe that are not will learn the fooner*." mr .7-', ' 
 
 1 his norrienclature was adopted by leveral chemiits, ci;„, p^,,^ 
 and it was ufed in the greateft part of the firft volume face, 
 of the chemical part of the Encyclopedic Melhodique ; 
 
 ef tartar, were the names by which they diftinguilhed but the new difcoveries in chemiftry had produced a 
 fome of the moft familiar preparations; and, were it more accurate method of reafoning, and had enabled 
 
 ■worth while, a great many more names of the fame 
 ftamp might eafily be added. 
 
 As foon as chemiftry had attrafted the attention of 
 men of fclence, the abfurdity of its nomenclature was 
 felt, and feveral partial improvements were at different 
 times made in it. Macquer, iii particular, difcardcd 
 many of the ancient names, and fubftituted others leis 
 exceptionable iu their place. 
 
 But foon after the publication of the fii ft edition of 
 his Dlftlonary, an evil began to be felt feverely, which 
 never could have occurred to the earlier cliemifts. Hi- 
 therto the number of objefls which had engaged the 
 attention of thofe who cultivated the fcience had been 
 very limited ; the acids amounted only to five, the 
 earths to four, the metals to i 2 or 14, and the neutral 
 falts Icarcclv exceeded 20 or ^o. To remember names 
 for fo fmall a number of bodies, however ridiculous they 
 happened tolae, was no very difficult matter. But about 
 that time, In confequence chiefly of the difcovery of 
 fixed air by Dr Black, which laid the foundation of 
 pneumatic chemiftry, the fcience began to extend itfelf, 
 and to enlarge its boundaries with inconceivable rapi- 
 dity. The number of bodies connetted with it, and 
 which it had to defcrlbe, foon became immenfe; and if 
 every one of them received names not dependant upon 
 one another, the moil retentive memory could not have 
 remembered the thoufandth part of them. 
 
 The difliculty of ftudying chemiftry from that tinn« 
 till the year 1782 muft have been very great : it was 
 even perceived and complained of by the matters of t?he 
 fcience. In 1782 Mr de Morveau, who had undertaken 
 the chemical part ot the Encyclopcdie Methodiqite, pub- 
 liftied in the journal de Phyfique a new chemical no- 
 menclature, and at the fame time invited all thofe per- 
 fons who were fond of chemiftry, and intercfted in its 
 proprefs, to propofe objeftions and improvements. 
 
 This new nomenclature was formed agreeable to the 
 five following rules :. 
 
 Lavoifier to explain the phenomena of the fcience 
 without the alFirtance of the hypothetical principle of 
 phlogifton, which had hitherto been neceflary. As the 
 language, even in its improved ftate, was accommodated 
 to this principle, and prefuppofcd Its exiilence, new 
 changes became evidently neceftary, in order that, ac- 
 cording to Morveau's rule, the words might denote tlie 
 moft eifentlal properties- of the things intended to be 
 fignified.. Accordingly, when Morveau was in Paiis in 
 1787, Lavoifier, BerthoUet, and Fourcroy, agreed to 
 labour in concert with him to bring the chemical no- 
 menclature ftill nearer to perfeftlon. ' Thele pliilofo- 
 phers, aflifted by the mathematicians of the Royal Aca- 
 demy and by feveral chemilfs, formed a new nomencla- 
 ture, which they made public in 1787. 
 
 For fome time little attention v/as paid to this no- 
 menclature by ii»reigu chcmills, and it feemed generally 
 to be dilapproved. The adherents of the phlogiitic 
 fyftem in France, who were exceedingly numerous, 
 viewed it as aji engine artfully formed to undermine and 
 deftroy their favourite theory. They relolved, there-* 
 fore, unanlmoufly, to crufti, it pofiible, this new inftru. 
 ment, which they confidered as 
 
 in nnfiros fibricata machlna muros, ■ 
 
 InfpeSura domos, •uailiiraqtie defuper urbi. 
 
 And for this purpofe they exerted themfelves with a vf- 
 gour, which was only equalled by tho zeal and indefati- 
 gable exertions of their antagonills.- A kind of civil 
 war was thus kindled in the republic of letters, which 
 was carried on with great animofity : And poilcrity ' 
 will fee, with regret, m.cji of undoubted genius at times 
 divefting themfelves of the armour of truth and of can- 
 dour, and endeavouring, to lerve their party, and ftab 
 their adverfaries with darts fteeped in the poifon of ca- 
 lumny and falfehood *. This conteft, however, which ( gee thg 
 was not confined to France, was produftive of good ei-Jouni.dc 
 fctts, which infinitely furpafted all. the bad ones. It^hf-^"^' 
 
 90. 91. fa/' 
 
 occa- 
 
 (o) See his thoughts on a natural hiftory of foflils ia the 4th vol. of his Opufc,
 
 398 
 
 Concrufuni. 
 
 * Confide r a 
 iions on the 
 doSrine of 
 
 pblogiflon , 
 
 Introduc- 
 tion. 
 
 C H E M I 
 
 occafioned an actrumulation of fnfts, produced a rigid 
 examination of theories and opinions, introduced an ac- 
 curacy into chemical experin>ents which has been of the 
 moft eflential fervice, and gave tliat tone and vigour to 
 the cultivators of chcniillry wliich have brought to light 
 the moft fubhme and unlooked for truths. It deferves 
 attention, and the faft is no inconfiderable evidence in 
 favour of the antiphlogilHc theory, that ahvioft all the 
 ilhiftrious chcmifts who at prefent adhere to it declared 
 origir.alK agaiiift it. .Berthollet, Morveaii, Black, Kir- 
 wan, and many other chemifts who are now its ableft 
 defenders, were at firft its moft powerful opponents. 
 •' This fyftem had hardly been publillied in France 
 (favs Dr Prieftley, who ftill continues to adhere to the 
 doctrine of phlogifton) before the principal philofophers 
 and chemifts of England, notwithftanding the rivalftiip 
 which has long fubfifted between the two countries, ea- 
 gerly adopted it. Dr Black in Edinburgh, and as far 
 as I hear all the Scots, have declared themfelves con- 
 verts, and, what is more, the fame has been done by Mr 
 Kirvvan, who wrote a pretty large treatifc in oppofitiun 
 to it. The Englifti reviewers of books, I perceive, uni- 
 verfally favour the new doftrine. In America, alfo, I 
 hear of nothing tlfc. It is taught, 1 believe, in all the 
 fchools on this continent, and the old fyftem is entirely 
 €,xploded. And now that Dr Crawford is dead, I 
 hardly know of any perfon except my friends of the 
 Lunar Society at Birmingham, who adhere to the doc- 
 trine of phlogifton ; and what may now be the cafe 
 with them in this age of revolutions, philofophical as 
 well as civil, I will not at this diftance anfwer for. 
 
 " It is no doubt thne, and of courfe opportunity of 
 examination and difcuflion, that gives ftability to any 
 principles. But this new theory has not only kept its 
 ground, but has been conftantly and uniformly advan- 
 cing in reputation more than ten years, which, as the at- 
 tention of fo many perfons, the beft judges of every 
 thing relating to the fubjeft, has been unreniittingly 
 given to it, is no inconfiderable period. Every year of 
 the laft twenty or thirty has been of more importance 
 to fcience, and efpecially to chemiftry, than any ten in 
 the preceding century *." 
 
 We have endeavoured in the preceding article to ftate 
 the different theiKies which have fucceffively made their 
 appearance in chemijli-y with as much fairnefs as poffible. 
 If we have fucceeded, the reader will be enabled to 
 judge for himfelf which of thefe theories is the moft con- 
 fiftent with truth ; or rather, if we have fucceeded, he 
 will join with us in thinking that the theory of Lavoi- 
 fier is in moft points an accurate account of what takes 
 place in nature. 
 
 This we confider as a fufficient reafon for having 
 adopted the new nomenclature ; for, as Morveau long 
 ago obferved, moft of the objedions that were made 
 to it were rather levelled at the doftrine of thofe who 
 formed it, than at the nomenclature itfelf. Its fu- 
 periority to every other nomenclature cannot be dif- 
 put«d for an inftant ; and the vaft facility which it has 
 
 S T R Y. 
 
 Part III, 
 
 added to the acquifition of chemiftry, niuft be acknow-Coiiclufton, 
 
 ledged by every one who knows any thing about the « "* 
 
 fcience. The Table of the new nomenclature will not 
 
 be expefted here, as it has been already given in tho 
 
 Appendix to the article Chemistry 'in X.\m Encyclo' 
 
 ped'ta. At any rate, it would have been unnecelTary, 
 
 as we have ufed the new names all along; and therefore 
 
 our readers muft by this time be well acquainted with 
 
 them. 
 
 Upon the almoft infinite number of criticifms vihich 
 have been made on the new nomenclature, and the ma- 
 ny new terms which fince its publication have been fuc- 
 ceffively propofed, we do not mean to enter. Few of 
 thefe terms can bear a comparifon with the French no- 
 menclature, and ftill fewer have any claim to be pre- 
 ferred to it ; and the philofophers who perfift in thefe 
 uielefs innovations, are more probably actuated by the 
 dcihe of appearing to have a Qiare in the great revolu- 
 tion which chemiftry has undergone, tlian by any hopes 
 of being able to improve the accuracy or the elegance 
 of its language. How few have difplayed the magna- 
 nimity of an illuftrious pl'iilofophtr of our own country, 
 who, though he had invented a new nomenclature him. 
 felf, exhorted his pupils not to ufe it, but to adopt that 
 of the French chemifts, which was likely foon to come 
 into univerfal ufe. 
 
 Even the etymological remarks which have been made 
 on the new nomenclature, we confider as either of little 
 confequence or as ill-founded. The philofophers who 
 formed it have difplayed a lagacity and a moderation 
 which could not be excelled, and have, upon the whole, 
 formed a language much more fyftematic, and much 
 more perfeft, tlian could have been expefted; and who- 
 ever compares it with the nomenclature propofed in 
 1782 by Morveau, will fee how great a (hare of it is 
 due to that illuftrious philofopher. 
 
 Notwithftanding what we have here faid, we would 
 not be undeiftood to confider the new nomenclature as 
 already arrived at a ftate of fuch abfolute perieflion, that 
 no alteration whatever can be made in it except for the 
 worfe. Such pertettion belongs not to the works of 
 man ; nor if it did, could it be expefted in this cale, if 
 we confider for a moment the prefent ftate of chemiftry. 
 New difcoveries muft occafion additions and alterations 
 in the nomenclature ; but the authors of the new nomen- 
 clature have given u« the rules by which changes and 
 additions are to be made ; and if they are adhered tO) 
 we may expeft with confidence that the language of 
 chemiftry will in its advancement to perfedlion keep 
 pace with the fcience. We have in the preceding ar- 
 ticle ventured in an inftance or two to adopt little im- 
 provements that have been fuggefted by later writers. 
 We have taken the liberty, too, of choofing, from the 
 variety which the BritKh chemifts have propoied, that 
 mode of fpelling each of the terms which appeared to 
 us moft agreeable to the Englifli idiom, and moft con- 
 formable to analogy : Whether or not we have made a 
 proper choice muft be left for others to determine. 
 
 INDEX
 
 rKE>as-rin-. FtATt .ttv-ui
 
 _Viu,.8. 
 
 (•ii!"..sns'ntY i't..viK.->cix . 
 
 Kii";. 10. 
 
 Vij.-.i:i 
 
 S 
 
 — 
 
 n 
 
 1 
 
 n 
 
 
 
 
 1 
 
 
 
 1 ; 
 
 
 
 1 
 
 1 
 
 J 
 
 
 1 
 
 -;» 
 
 Wtr.l 
 
 l'i,ir.-Art. 
 
 F.g.18 
 
 A, ''- 3 A 
 
 V\;<::i:i- 
 
 «- 
 
 
 
 
 
 
 
 1 1 
 
 '•^ 
 
 i 
 
 
 
 
 
 
 
 
 ?- 
 
 /■ 
 
 c 
 
 
 
 
 
 
 
 ^■ 
 
 r 
 
 / 
 
 c/ 
 
 
 
 
 
 
 ■J' 
 
 
 < 
 
 nt 
 
 e 
 
 
 
 
 
 t 
 
 
 
 ti 
 
 /f 
 
 y 
 
 
 
 
 rt 
 
 
 
 
 j- 
 
 ^ 
 
 .^ 
 
 
 
 
 
 
 
 
 .1 
 
 /• 
 
 A 
 
 
 -f 
 
 
 
 
 
 z 
 
 ^ 
 
 /' 
 
 » 
 
 
 
 
 
 
 
 
 c 
 
 I I I I M I J I" 
 
 2- I I f - 
 
 I I I I I I I I Ic 
 
 rf-H — "T 
 
 n 
 _^ 
 
 TZ — ^ ^- 
 
 — / ' «^ 
 
 ll.nii). 
 
 tt- 
 
 .r,sr:i-!. 
 
 Vi^--l3 
 
 l"iV;J+. 
 
 
 
 
 
 
 
 
 
 
 , 
 
 
 
 
 
 
 
 ^ 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■/ 
 
 , 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 *■ 
 
 
 , 
 
 
 
 
 
 
 
 Vi-tr-a. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ■■ 
 
 
 
 
 
 
 
 
 
 
 
 . 
 
 
 
 
 , 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 . 
 
 
 
 
 
 
 
 
 
 
 
 H 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 - 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 J 
 
 
 
 
 ,F 
 
 Ri'-' 
 
 
 
 ' f ! 
 
 1 
 
 
 ! ' 
 
 
 
 ' • 
 
 
 H_ 
 
 ^ 
 
 Tig.'G. 
 
 l-.^o2 . 
 
 / 
 
 - n 
 
 .18. 
 
 , I. 
 
 
 
 
 1 
 
 
 
 1 
 
 
 .\ 
 
 
 / 
 
 ' 
 
 u 
 
 
 V.V.&l- 
 
 T^ 
 
 
 il^J+ . 
 
 L-L
 
 Index. 
 
 CHEMISTRY. 
 
 399 
 
 INDEX. 
 
 JCETATS, n" »co. 
 -^ Jcttitci, 464, and Part III. 
 
 chap, if fed. \ i. 
 Jcetic acid, Part II. chap. v. 
 
 lea. 12. 
 jtcetous acid, Part II. chap. v. 
 
 feft. II. 
 Acid principle, ;488. 
 yldd,i:id\,'in fulphuric acid, 398. 
 
 in nitric acid, 41 2. 
 /ic'td foaps, Part III. chap 1. 
 
 feft. 2. 
 jlc'tds, Part 11. chap. v. 
 Adds, animal, 549. 
 metallic, 559. 
 vegetable, 526. 
 Ac'idum pingue, 374. 
 ./f<//5^on explained, 566. 
 
 experiments on, 577. 
 jierial acid, 457. 
 jEj, meaning of the word, p. 
 
 239, note. 
 ./^nfVyexplained, n"^ 1 3, and Part 
 
 II. chap. vi. 
 jijitt'tty, compound, 580. 
 difpoling, 581. 
 fimple, 579. 
 Jgujl'ma, 239. 
 
 Air, a ron-conduftor of calo- 
 ric, 260. 
 artificial, 457. 
 Alcohol, Part II. ch. il. 
 analyfis of, 353. 
 fubftances, foluble in, 
 
 , . 358- 
 
 Alkalies, Part II. ch. iv. 
 
 Alkali vegetabile vitriolatum, 
 
 p. 359, note. 
 
 Aihaline foaps. Part III. ch. i. 
 
 fea. I. 
 
 Alloy explained, p. 226, note. 
 
 Alum, n" 636. 
 
 fpirit of, p. 362> note. 
 
 Alumen, n° dl^i- 
 
 Alumina, Part I. ch. iv. feft. 6. 
 
 acetite of, 784. 
 
 benzcat of, 821. 
 
 borat of, 749. 
 
 camphorat of, 829. 
 
 carbonat of, 775. 
 
 citrat of, 814. 
 
 fluat of, 765. 
 
 laftat of, 817. 
 
 muriat of, 705. 
 
 nitrat of, 676. 
 
 oxalat of, 805. 
 
 phofphat of, 73?. 
 
 faccholat of, 818. 
 
 Alumina, febat of, n" 847, 
 
 foap of, 594. 
 
 fuberat of, 836. 
 
 fulphat of, 627. 
 
 fulpl\ite of, 665. 
 
 tartrite of, 8n. 
 Amalgam, what, 93. 
 Amber, qo2. 
 Ammonia, Part II. ch. iv. feft. 3. 
 
 acetite of, 779. 
 
 anrat of, S49. 
 
 brnzoat of, 820. 
 
 borat of, 725. 
 
 camphorat of, 825. 
 
 carbonat of, 770, 
 
 citrat of, 813. 
 
 cuprat of, 852. 
 
 fluat of, 761. 
 
 lat^at of, 817. 
 
 malat of, 816. 
 
 mercurial of, 851. 
 
 muriat of, 697. 
 
 nitrat of, 670. 
 
 oxalat of, 804. 
 
 phofphat of, 730. 
 
 prufiiat of, 837. 
 
 faccholat of, 8iS. 
 
 febat of, 8ji6. 
 
 foap of, 591. 
 
 fuberat of, 832. 
 
 fulphat of, 627. 
 
 fulphite of, 66 r. 
 
 tartrite of, 8 1 o. 
 
 zincat of, 855. 
 Animal zcids, 549. 
 Antimony, Partl. ch.iii. feft. 10. 
 
 acetite of, 794. 
 
 benzoat of, 822. 
 
 muriat of, 7 16. 
 
 nitrat of, 687. 
 
 oxalat of, 806. 
 
 febat of, 848. 
 
 fulphat of, 650. 
 
 tartrite of, 812. 
 Anliphlogijlic theory, p. 277. 
 
 note. 
 ylnt.t, acid of. Part II. ch. v. 
 
 feft. 29. 
 Apulum, n" 240. 
 Aquafortis, 407. 
 Aqua-regia, p. 224, note. 
 Arcanum duplicatum, n° 624. 
 
 tartari, 777. 
 Arfeniats, 552, and Part III. 
 
 ch. ii. feft. 26. 
 Arfenic, Part I. ch. iii. feft, 12. 
 acid, 550. 
 acetite of, 795. 
 benzoat of, 822, 
 
 Arfenic, borat of, n" 7 j8. 
 
 fluat of, 767. 
 
 muriat of, 717. 
 
 nitrat of, 688. 
 
 oxilat of, 806. 
 
 phofphat of, 740. 
 
 febat of, 848. 
 
 fulphat of, 651. 
 
 tartrite of, 81 2. 
 Atmofpheric air, compofition of, 
 
 Aurum mufivuni, 1 20. 
 
 Aujlrum, 240. 
 
 A-zot, Part I. ch. ii. feft. 9. 
 
 how combined with oxy- 
 gen, 421. 
 
 B 
 
 Balfam of fulphur, 370. 
 Balm of Peru, foap of, 609. ■ 
 Barytes, Part I. ch. iv. feft. 3. 
 acetite of, 780. 
 •borat of, 725. 
 camphorat of, 826. 
 carbonat, 771. 
 citrat of, 814. 
 fluat of, 762. 
 laftat of, 817. 
 malat of, 816. 
 muriat o.^, 699. 
 nitrat of, 671. 
 oxalat of, 805. 
 oxymuviat of, 724. 
 phofphat of, 731. 
 pruffiat of, 838. 
 faccholat of, 818. 
 foap of, 595. 
 fuberat of, 834. 
 fulphat of, 62S. 
 fulphite of, 661. 
 Barytic, water, 209. 
 Beer, when firll known, 340. 
 Bill metal, 122. 
 Benzoats, 501, and Part III. 
 
 ch. ii. feft. 1 9. 
 Benzoic acid, Part II, ch. v. 
 
 feft. 20. 
 Benzoin, 499. 
 
 foap of, 608. 
 Bergman, charafter of, 1 7 4. 
 Bifmuth, Part I. ch. iii. feft. i i. 
 acetite of, 793. 
 benzoat of, 822. 
 borat of, 757. 
 muriat of, 7 1 5. 
 nitrat of, 686. 
 oxalat of, 806. 
 fulphat of, 649. 
 tartrite of, 812. 
 
 Black, Dr, difcovers latent heat, 
 268. 
 difcovers the compo- 
 fition of the carbo* 
 nats, 200, 373. 
 Black bodies fooneft. lieated by 
 light, 325. 
 lead, 109. 
 Blende, p. 247, note. 
 Blue liquid, n° 513. 
 Boiling point of water, experi- 
 ments on, ^37, 338. 
 Bologna ftone, 629. 
 Bomhyc acid, 546. 
 Boracic acid. Part II. ch. v. 
 
 feft. 8. 
 Borats, 447, and Part II. ch. ii. 
 
 feft. 8. 
 Borax, 441, 744. 
 Barbonium, 240. 
 Brap, 140. 
 
 Brittlenefs, to what owing, 303* 
 Bronze, 122. 
 Brunfviick green, 81 2. 
 
 c 
 
 Cadmea, J 34. 
 Careous acid, 457. 
 Calchanlum, 641. 
 Calcination, 6 1. 
 Calomel, 718, 725. 
 Caloric, Part I. ch. v. 
 
 whether a fubftance, 
 
 241,312. 
 equilibrium of, 246. 
 of fluidity, 269. 
 of evaporation, 270. 
 methods of obtaining, 
 
 292. 
 whether the fame with 
 light, 328. 
 Calorimeter, 265. 
 Calx, 6 1 . 
 Camphor, 506. 
 Camphorats, 5 10, and Part III. 
 
 ch. ii. feft. 21. 
 Camphoric acid. Part. II, ch. v, 
 
 feft. 22. 
 Canton' i pyrophorus, 320. 
 Capacity for caloric explained, 
 
 362. 
 Carbon, Part I. ch. ii. feft. 3. 
 attempts to decompofe, 
 44. 
 Carbonats, 462, and Part III. 
 
 ch. ii. feft. 10. 
 Carbonated hydrogen gas, 42,- 
 
 and Part III. ch. iii. 
 Carbonated azotic gas, 50. 
 
 Carionie
 
 400 
 
 'Curbon'ic acid, 32, and Part II, 
 
 ch. V. fcift. 10. 
 Carbunets, 11° 35. 
 Curiunct of iron, I 39. 
 
 muiigaiictc, 175. 
 ■/.[lie, 139. 
 Cavallo's expcrimcnts'on light, 
 
 34i- 
 
 Ca.'uendijh, Henry, difcovers the 
 coiiipofitioa of wa- 
 ter, :;4 I . 
 and of nitric acid, 
 409. 
 
 Caujltcum acidum, 374. 
 
 Cemfnlalion, 1 13, 
 
 Chalybeated tartar, 8 1 2. 
 
 Charcoal, condufting power of, 
 
 252- 
 Chemtjlry, definition of, I. 
 Chronic acid. Part 11. ch. v. 
 
 feci. 35. 
 Chromum, 189, 
 Cinnabar, 91. 
 Cilrats, 478, and Part III, ch. 
 
 ii. feft. 14. 
 Citric acid, 476. 
 Cobalt, Part I. ch. iii. fe£l. 13. 
 acetite of, 790. 
 benzoat of, 822. 
 borat of, 752. 
 fluat of, 767. 
 muriat of, 7 10. 
 nitrat of, 680. 
 oxaht of, 806. 
 foap of, 598. 
 fulphat of, 646. 
 Cohejion, 570. 
 
 Cold, methodofproducing, 280. 
 why produced by mix- 
 tures, 282. 
 Colour efFefls the heating of 
 
 bodies by hght, 335. 
 Colouring matter of Pruflian 
 
 bhie, v33. 
 Combujlion explained, 293. 
 Common falts, 696. 
 Compound affinity, 583. 
 Compound bodies, Part II. 
 Condenfation dirainifhes fpecific 
 
 caloric, 303. 
 Condu8ing powers of bodies, 
 
 251, 2:^6. 
 CoiilaB, no abfolute, 568. 
 Copper, Part I. ch. iii. fed. j. 
 acetite of, 792. 
 ■benzoat of, 822, 
 borat of, 756. 
 citrat of, 815. 
 fluat of, 767. 
 muriat of, 7 1 4. 
 nitrat of, 685. 
 oxalat of, 8c6. 
 febat of, S48. 
 foap of, 602. 
 lulphat of, 684. 
 
 CHEMISTRY. 
 
 Corh, n" 5ri. 
 
 Corroftve muriat of mercury, 
 72?. 
 fublimate, 7JJ. 
 Corundum, 2*0- 
 Crawford, Dr, hia experiments 
 on fpecific caloric, 
 264. 
 his theory of com- 
 bultion, 297. 
 Cryjlal, rock, 216. 
 CryJlallf:.ation, Part III. ch. iv. 
 Cryjlals, what, 18, 864. 
 Cuprum, when firft. ufed, page 
 239, note. 
 
 D 
 Decrepitation explained, p. 359, 
 
 notes. 
 De Luc's theory of light, 332. 
 Denjity, incr^fafed by hammer- 
 ing, 
 of different mixtures of 
 acidsand water, 397, 
 41 1, 424. 
 Dephlrjgijlicated air, 6. 
 
 muriatic acid, 
 428. 
 Detonation of nitre, 667. 
 Diamond, 38. 
 
 Dige/li've fait of Sylvius, 777. 
 Difpoftng affinity, 584. 
 Diuretic fait, 777. 
 DuaUity, 60. 
 
 E 
 Earthi, Part I. ch. iv. 
 
 properties of, 192. 
 combinations with each 
 other, 205, 217. 
 225. 
 remarks on, J40. 
 EJfer-vefcence, what, page 214, 
 
 note. 
 Efflorefcing explained, n° 626, 
 
 and note. 
 Eggs hatched by eleftricity, 
 
 Ekilrive attraftion, what, J 3. 
 
 Ekaricity, analogy between and 
 caloric, 246. 
 whether an agent in 
 producing heat by 
 friftion, 3.14. 
 
 Emetic tartar, 812. 
 
 Empyreal air, 6. 
 
 Epfom fait, 633. 
 
 Equilibrium of caloric, 246. 
 
 Ether, 355. 
 
 Ethiops mineral, 90. 
 
 Eudiometer, 420. 
 
 Euler's theory of light, 3 1 5. 
 
 Expanjion of bodies, table of, 
 242. 
 
 Extraa of Saturn, 790. 
 F 
 
 Fat, acid of, 543. 
 
 Fea'hers, why a warm cover. 
 
 ing, n° 260. 
 Febrifuge fait of Sylvius, 695. 
 Fire damp, 36. 
 Fixed air, 203, 457. 
 ammonia, 701. 
 oil, 361. 
 Fluats, 455. and Part III. ch. 
 
 ii. kct. 9, 
 Fluids, whether conduiftors of 
 caloric, 256. 
 provedthattheyare, 259. 
 Fluor, 449. 
 Fluoric acid, Part II. ch. v. 
 
 feft. 9. 
 Formic acid, 529, 
 Formica rufa, 539. 
 Franklin's experiments on the 
 heating of bodies by light, 
 
 Friaion, caloric produced by, 
 
 307, 310- 
 Fulminating gold, 849,! 
 filver, 850. 
 Furs, in what their warmth con- 
 
 fifts, 260. 
 Fufible fpar, 449, 
 Fujion, 867. 
 
 G 
 Gallats, 498, and Part III. ch, 
 
 ii. feft. 18. 
 Gallic acid, Part II. ch. v. fed. 
 
 19. 
 Galls, 493. 
 
 Gas explained, 5, 457, 
 Gafeous form of bodies, to what 
 
 owing, 279. 
 Gafes, not heated red hot, 327. 
 Glaf, o,-ii. 
 
 condudlingpowerof, 253. 
 of antimony, 145. 
 Glauber's fait, 626. 
 Glucina, 236, 237. 
 Gold, Part I. ch. iii. feft. r. 
 afted on by nitric acid, 
 
 413- . 
 fulminating, 848. 
 
 acetite of, 79S. 
 
 benzoat of, 822. 
 
 febat of, 848. 
 
 foap of, 605. 
 
 ftannat of, 853. 
 Guaic, foap of, 6ic. 
 Gunpo'wder, 667. 
 Gypfum, 630. 
 
 Hnrtfhorn, 382. 
 
 i/juy's theory of cry ftallization, 
 
 872. 
 Heat, Part I. ch. v. 
 
 makes bodies luminous, 
 326. 
 Hepatic gas, 40. 
 Hot bodies lighter than cold, 
 248. 
 
 i 
 
 Index. 
 
 Houi poun, n" 441 . 
 Hutton'i theory of light, 333. 
 explanation of the ap- 
 parent refle£lion of 
 cold, page 283, note. 
 Hydrogen gas. Part I. cli. ii, 
 
 lea. 4. 
 Hydrogenous fulphurets, 858. 
 Hydrofulphurets, Part III. ch, 
 iii. 
 
 I 
 yames's powder, 742, "^l 
 
 Jargon, 243. _ " 
 
 Jargonia, Pait I. ch. iv. feft, 7. 
 & page 363, note, 
 acetite of, n" 785. 
 muriat of, 706. 
 nitrat of, 677. 
 fulphat of, 640, 
 
 ^^'y 335- 
 
 liiflammahk air, page 2 1 7, 
 Iron, Part I. ch. iii, feft. 6., 
 call, 113. 
 cold fhort, 108, 
 wrought, I II, 
 acetite of, 786, 
 benzoat of, 822. 
 borat of, 750. 
 carbonat of, 776. 
 citrat of, 815, 
 fluat of, 767. 
 green fulphat of, 64 1» 
 laftat of, 817. 
 malat of, 816. 
 muriat of, 707. 
 nitrat of, 678, 
 oxalat of, 806, 
 phofphat of, 736, 
 prufliiat of, 839. 
 red fulphat of, 642. 
 febat of, 848. 
 foap of, 601. 
 fulphite of, 666. 
 tartrite of, 812. 
 Irvine, Dr, his theory of heat, 
 296. 
 theorem to difcover the 
 real zeno, 272. 
 K 
 Kirwan's theory of phlogifton, 
 299. 
 experiments en the 
 flrength of acids, 
 497,511, 
 L 
 Lae, white y 1 7. 
 Laccic acid. Part II. ch. v, feftj 
 
 24. 
 LaBats, 486, and Part III, ch. 
 
 ii. feft. 16. 
 Z«fl(Vacid.PartII.ch.v.feft,l7. 
 Lana philofophica, page, 238. 
 
 note. 
 Latent caloric, n° 269. 
 Lavoifier and La Plage, experi. 
 ments
 
 ments of on fpecific caloric, 
 n« 265. 
 Lead, Part I. ch. ili. fed. 8. 
 acetite of, 782. 
 benzoat of, 822. 
 borat of, 754. 
 fluat of, 767. 
 muriat of, 712. 
 nitrat of, 683. 
 oxalat of, 806. 
 febat of, 8^8. 
 foap of, 603. 
 fulphat of, 647. 
 Lemons, cffential f;ilt of, 802. 
 Light, Part I. ch. vi. * 
 
 Ligneous acid, page 333, note. 
 
 L 
 Lime, Part I. ch. iv. fed. i . 
 acetite of, 781. 
 benzoat of, 821. 
 borat of, 746. 
 camphorat of, 827. 
 citrat of, 814. 
 fluat of, 763. 
 laftat of, 817. 
 malat of, 816. 
 niercuriat of, 851. 
 inuriat of, 701. 
 nitrat of, 672. 
 oxalat ot, 805. 
 oxy- muriat of, 724. 
 phofphat of, 732. 
 plunibat of, 854. 
 priifliat of, 83S. 
 faccholat of, 8 1 8. 
 febat of, 847. 
 foap of, 59Z. 
 fuberat of, 834. 
 fulphat of, 630. 
 fulphite of, 663. 
 tartiite of, 8n. 
 Lime-water, 195. 
 Liquid blue, 5 13. 
 Liquor filicum, 21 5, 377. 
 Lute, what, 7. 
 
 M 
 Macquer'i opinion about phlo- 
 
 gifton, 296. 
 Mdgne/ia, Part I. ch. iv. fed. 2. 
 acetite of, 783. 
 benzoat of, 8ji. 
 borat of, 748. 
 camj)horat of, 8 28. 
 citrat of, 814. 
 fluat of, 764. 
 laftat of, «I7. 
 malat of, 8 1 6. 
 muriat of, 703. 
 nitrat of, 674. 
 oxalat of, 805. 
 oxy-muriat of, 724. 
 phofphat of, 734. 
 prufliat of, 838. 
 faccholat of, 818. 
 febat of, 847. 
 SuppL. Vol. I. Part II. 
 
 CH E M I 
 
 Magnejtii, foap of, n° 593. 
 
 fuberat of, 835. 
 
 fulphat of, 633. 
 
 fulphite of, 604. 
 
 tartrite of, 811. 
 Malats, 483, and Part III. ch. 
 
 ii. fed. 15. 
 Malic acid, 480. 
 Miilleability, 59. 
 Manganefe, Part I. ch. iii. fe£l. 
 
 15- 
 
 benzoat of, 822. 
 fluat of, 767. 
 muriat of, 709. 
 nitr:it of, 680. 
 oxalat of, 8c6. 
 phofphat of, 738. 
 ioap of, 606. 
 fulphat of, 644. 
 Marcaftte of gold, 134. 
 Marks given to metals by the 
 
 ancients, 1 30. 
 Marine acid, 422. 
 MaJfKoi, 125. 
 Menachanite, 186. 
 Mephetic acid, 457. 
 Mercury, Part I. ch. iii. feft. 4. 
 a nonconduftor of ca- 
 loric, 259. 
 acetite of, 796. 
 benzoat of, 822. 
 citrat of, 815. 
 fluat of, 767. 
 hydrogenous fulphu- 
 
 ret of, 859. 
 muriat of, 7 ) 8. 
 nitrat of, 689. 
 oxalat of, 806. 
 oxy-muriat of, 7 2 J. 
 prufliat of, 845. 
 febat of, 848. 
 foap of, 596. 
 tartrite of, 8 1 2. 
 white fulphat of, 651. 
 yellow fulphat of,653. 
 Metallic acids, 559. 
 Metals, Part I. ch. iii. 
 
 expanfion of, 242. 
 condutling power of, 
 254. 
 Miafmata, how deftroyed, 426. 
 Microcofmic fait, 730. 
 yi//nf/-(!/ cryftal, 667. 
 Minium, 1 25. 
 Mi poun, 441. 
 Mify, 641. 
 Molybdena, 180. 
 Molybdenum, Part I. ch. iii. fedl. 
 
 17- 
 Molybdats, ^^^. 
 Molybdic acid, ^^^, 
 Mother ley, explained, page 25 r, 
 
 note. 
 ■ Muriatic acid, Part II. ch. v. 
 
 fea. 5, 
 
 S T R Y. 
 
 Muriatic acid dcpliloglfticated, 
 n" 428. 
 oxygenated, 428. 
 compofition of, 
 
 434- 
 Murials, 425, and Part III. 
 ch. ii. feft. j. 
 N 
 Names given to metals by the 
 
 ancients, 130. 
 Narcotic fait, 442. 
 Newton's theory of light, 315. 
 Niciel, Part I. cli. iii fed. 14. 
 acetite of, 789. 
 borat of, 753. 
 fluat of, 767. 
 muriat of, 711. 
 nitrat of, 682. 
 oxalat of, 806. 
 phofphat of, 739. 
 foap of, 599. 
 fulphat of, 645. 
 Nitrats, 414, and Part III. ch. 
 
 ii. feft. 3. 
 Nitre, 667. 
 
 ads on platinum, p. 312, 
 
 note, 
 cubic, 669. 
 Nitric acid, 51, and Part II. 
 ch ii. fed. 3. 
 its ad Ion on oils, 413. 
 Nitrites, 417, and Part III. ch. 
 
 ii. fed. 4. 
 Nitrous air or gas, 409, 418. 
 acid. Part II. ch, v. 
 fed. 4. 
 Nitro-muriatic acid, 43 1. 
 Nitrum fixum, 624. 
 
 flammans, 670. 
 femivolatile, 670. 
 O 
 Oil of vitriol, 391. 
 Oils, Part II. ch. iii. 
 drying, 365. 
 noncondudois of heat, 
 
 295- 
 Olive, when firft cultivated in 
 
 Europe, 330. 
 Olive oil analyfed, 363. 
 Orichalcum, what, 140. 
 Orpiment, 155. 
 Ouretic acid, 729. 
 Oxalats, 470, and Part III. ch. 
 
 ii. fed. 12. 
 Oxalic acid, Part II. ch. v. fed. 
 
 Oxide and oxydation, 68. 
 Oxides of antimony, 144. 
 
 arfenic, 154. 
 
 bifmuth, 149. 
 
 cobalt, 160. 
 
 copper, 96. 
 
 gold, 71. 
 
 iron, 10 J. 
 
 lead, 125. 
 
 3E 
 
 401 
 
 Oxides of manganefe, n" 173. 
 mercury, 85. 
 molybdenum, 181. 
 nickel, 167. 
 platinum, 81. 
 filver, 74. 
 tellurium, 188. 
 tin, I 19. 
 titanium, i8y. 
 tungllen, 179. 
 uranium, 183. 
 zinc, 136. 
 metallic, remarks on, 
 191. 
 Oxygen, Part I. ch. i. 
 
 gas contains light, 322. 
 caloric it gives out, 
 278. 
 Oxy-muriats, 432, and Part III. 
 
 ch. ii. fed. 6. 
 Oxy muriatic acid, Part II. ch. 
 V. fed. 6. 
 
 P 
 Panacea holfatica, 624. 
 Pe-la, page 33 z, note. 
 PercuJJion produces heat, and 
 
 why, n° 302. 
 Perlaled fait, 729. 
 acid, 729. 
 Peiuter, 14c, 152. 
 Phlogijlon explained, 29J, 20, 
 its exiftcnce difpro- 
 ved, 301. 
 Pblogi/llc theory, page 277, 
 
 note. 
 Phlugijlicated air, n° 52. 
 Phofphats 438, and Part III. 
 
 ch. Ii. fed. 7. 
 Phojphorated hydrogen gas, 41. 
 
 azotic gas, 50. 
 Phofphoric acid, 28, and Part 
 
 II. ch. v. fed. 7. 
 Phofphorous acid, 440. 
 Phofphorus, Part I. ch. ii. fed. 
 2. 
 whether an ingre- 
 dient of fl:eel, 1 15. 
 Phofphuret of antimony, 145. 
 arfenic, 156. 
 bifmuth, 151. 
 cobalt, 162. 
 copper, 100. 
 gold, 72. 
 iron, 108. 
 lead, 127. 
 lime, 197. 
 manganefe, 174. 
 mercury, 92. 
 molybdenum, 
 
 181. 
 nickel, 169. 
 platinum, 82. 
 potafs, 375. 
 lilver, 76. 
 tin, 121. 
 
 Phofphuret
 
 402 
 
 Phofphuret of tungften, no 179. 
 
 zinc, 138. 
 PiSet's experiments on light and 
 caloric, 325, and p. 
 284, note. 
 P'mchleck, 140. 
 Pin poun, 44 1. 
 Plajcr of Paris, 631. 
 Platinum, Part I. ch. iii. fedl. 3. 
 benzoat of, 82i. 
 oxalat of, 8c6. 
 febat of, 848. 
 Plumbago, 109. 
 Pneumatic apparatus, 7. 
 Pomphohx, page 240, note. 
 Potafs, Part II. ch. iv. feft. I. 
 acetite of, 777. 
 acidulous oxalat of, 802. 
 antimoniat of, 856. 
 benzoat of, 820. 
 borat of, 74^. 
 camphorat ot, 823. 
 carbonat of, 768. 
 citrat of, 813. 
 fluat of, 759. 
 laftatof, 817. 
 malat of, 816. 
 muriat of, 605. 
 nitrat of, 667. 
 oxalat of, 801. 
 oxy-muriat of, 722. 
 phofphat of, 728. 
 prufliat of, 837. 
 iaccholat of, 818. 
 febat of, 846. 
 fuberat of, 830. 
 fulphat of, 624. 
 fulphite of, 659. 
 tartrite of, 808. 
 Pounxa, 441- 
 Precipitate per fe, 88. 
 Priejikyi theory of combuftion, 
 297. 
 experiments on ni- 
 nitrous gas, 409. 
 Prince's metal, 140. 
 Prujian blue, 530, 839. 
 
 alkali, 532, 841. 
 Prujiats, 537. 
 
 PruJJic acid, Part II. ch. v. La. 
 28. 
 affinities of, 840. 
 Pyrolignites, 524. 
 Pyrolignous acid. Part II. ch. v. 
 
 feft. 26. 
 Pyromucites, 522. 
 Pyromucous acid, Part II. ch. v. 
 
 feft. 25. 
 Pyrophori, 32"!. 
 Pyrophorus of Romberg, 639. 
 Pyrotartrites, 528. 
 Pyrotartarous acid, Part II, ch. 
 V. feft. 27. 
 
 ^icklime, 193. 
 
 C H E M I 
 
 ^idjilver, Part I. ch. iii. fedl. 
 
 4- 
 
 R 
 Rancidity, n° 364. 
 Realgar, I 55. 
 Red he.Ti.t. explained, 326. 
 
 lead ore of Siberia, page 
 
 299, note, 
 precipitate, n« 88. 
 Redu^icn explained, page 232, 
 
 note. 
 Regenerated tartar, n° 777. 
 Rejtduum, what, 19. 
 Refin explained, p. 299, note. 
 Rock cryftal, 2 1 6. 
 Rujl of iron, lO?. 
 
 S 
 Saccharine acid, 467. 
 Saccholats, 492, and Part III. 
 
 ch. ii. feft. 17. 
 Sal ammoniac, 697. 
 
 catharticus amarus, 633. 
 de duobus, 624. 
 gem, 696. 
 mirabile, 626. 
 
 perlatum, 629. 
 polycrefl Glaferi, 624. 
 Salt of Saturn, 790. 
 Salli, 622. 
 
 neutral, 623. 
 Saturation explained, 571. 
 Scammony, foap of, 611. 
 Scheele, account of, 33 1, and 
 
 note in page 286. 
 Sea fait, 696. 
 Sebats, 545, and Part III. ch. 
 
 ii. fedf. 25. 
 Secret foliated earth of tartar, 
 
 777- , . ^ 
 
 fal ammoniac, 027. 
 
 Selenite, 63O. 
 
 Semimetals, 69. 
 
 Seydler fait, 633. 
 
 Siderum, 108. 
 
 Sidneia, 239. 
 
 Silica, Part I. ch. iv. feft. 5. 
 
 Scheele's theory of the 
 
 formation of, 4J0. 
 fluat of, 766. 
 Sill-, why a warm covering, 
 
 260. ^ 
 
 Silkworm contains an acid, 
 
 546. 
 Silver, Part I. ch. in. feft. 2. 
 fulminating, 850. 
 acetite of, 797. 
 benzoat of, 822. 
 muriat of, 720. 
 nitrat of, 691. 
 oxalat of, 806. 
 ,fuap of, 604. 
 fulphat of, 6jJ. 
 Simple affinity, 582. 
 
 bodies what, 3. 
 Smoiing liquor of Libavius, 726. 
 
 S T R Y. 
 
 ijnow of antimony, 144. 
 Soap, 378._ 
 
 origin of the term, 586. 
 method of forming, 587. 
 hard, ^86. 
 foft, 59;. 
 of wool, 590. 
 of filli, 590. 
 Soaps, Part III. ch. i. 
 Soda, Part II. ch. iv. fed. 2. 
 acetite of, 778. 
 benzoat of, 820. 
 borat of, 744. 
 , camphorat of, 824. 
 carbonat of, 769. 
 citrat of, 813. 
 fluat of, 760. 
 ladat of, 817. 
 malat of, 816. 
 muriat of, 696. 
 nitrat of, 669. 
 oxalat of, 80J. 
 oxy-muriat of, 723. 
 phofphat of, 729. 
 prufliat of, 837. 
 faccholat of, 8 1 8. 
 febat of, 848. 
 fuberat of, 831. 
 fulphat of, 626. 
 fulphite of, 660. 
 Solulle tartar, 808. 
 Solution, 865. 
 
 why haftened by heat, 
 291. 
 Sory, 641. 
 Sparks produced by the colli- 
 
 fion of quartz, 305. 
 Specific caloric, what, 262, 290. 
 
 table of, 267. 
 Specificum purgans, 624. 
 Spelter, 134. 
 
 Spirit of Mindererus, 779. 
 nitre, 407. 
 fait, 422. 
 Stahl's theory of combuftion, 
 
 295- 
 Steam, 336. 
 
 a nonconduftor of calo- 
 ric, 261. 
 Steel, 112. 
 Stibium of the ancients, what, 
 
 142. 
 5/o««,condufting power of,255. 
 Strength of acids, 397, 411. 
 Stronlites, Part I. ch. iv. feft. 4. 
 
 acetite of, 782. 
 
 carbonat of, 773. 
 
 muriat of, 702. 
 
 nitrat of, 673. 
 
 oxalat of, 805. 
 
 phofphat of, 733. 
 
 fulphat of, 633. 
 
 tartrite of, 811. 
 Suberats, 514. and Part III. 
 ch. ii. feft. 2 2. 
 
 Index* 
 
 Suberic acid, Part II. ch. v. 
 
 iett. 23. 
 Succinats, n^ 50J. 
 Succinic acid, Part II. ch. 5, ' 
 
 feft. 21. 
 Sugar, 465. 
 
 acid of, 466. 
 of bifmuth, 793. 
 of lead, 790. 
 of milk, 488. 
 of Saturn, 790. 
 Sulphats, 399. and Part III. 
 
 ch. ii. feft. 1. 
 Sulphites, 405. and Part III. 
 
 ch. ii. feft. 2. 
 Sulphur, Part I. ch. ii. feft. i. 
 Sulphurated hydrogen gas, 40, 
 
 857. 
 Sulphuret of ammonia, 386. 
 antimony, 145. 
 arfenic, 155. 
 barytes, 2 10. 
 bifmuth, 150. 
 cobalt, 161. 
 copper, 99. 
 iron, 107. 
 lead, 126. 
 lime, 196. 
 magnefia, 204. 
 mercury, 90, 9r, 
 
 859. 
 molybdenum, 181, 
 nickel, 168. 
 potafs, 375. 
 filver, 7j. 
 tellurium, 188. 
 tin, 120. 
 tungften, 179. 
 uranium, 183. 
 zinc, 137. 
 Sulphurets, remarks on, 858. 
 Sulphuric acid. Part II. ch. v. 
 
 feft. I. 
 Sulphurous acid. Part II. ch. v. 
 
 feft. 2. 
 Syl-vanile, page 247, note. 
 Syrupous acid, page 333, note. 
 
 T 
 Tanning principle, page 327, n. 
 Tartar, 472, 807. 
 
 emetic, 812. 
 
 Tartarized tinfture of Mars^ 
 
 812. 
 
 iron, 8 I 2. 
 
 Tarlarous acid, Part II. ch. v. 
 
 feft. 14. 
 Tartrites, 474. and Part III. 
 
 ch. ii. feft. 13. 
 Telluriumr Part I. ch. iii. feft. 
 20. 
 fulphat of, 658. 
 Temperature explained, 290. 
 Tennant, Smithfon, decompofes 
 
 carbonic acid, 459. 
 Tenjton of caloric explained, 247. 
 Terra
 
 Index. 
 
 Trrra penderofa, 207. 
 Thermometer, 244. 
 
 how a meafure of 
 temperature, 
 248. 
 ftands higher when 
 its bulb is black- 
 ened, 325. 
 finks in an ex- 
 hauftedreceiver, 
 
 Wedgewood's, 
 224. 
 Tm, Part ch. iii. feft. 7. 
 
 acetiie of, 791. 
 
 benzoat of, 822. 
 
 borat of, 755. 
 
 fluat of, 767. 
 
 niuriat of, 713. 
 
 nitrat of, 684. 
 
 oxalat of, 806. 
 
 oxy-muriat of, 726. 
 
 febat of, 848. 
 
 foap of, 600. 
 
 fulphat of, 647. 
 fin/oil, n8. 
 finplate, n° 128- 
 
 C H E M I S T R Y. 
 
 Vitriolated ammonh, 627. 
 
 tartar, 624. 
 Vitriolic acid, 391. 
 Volatile and •volatilical'ion, what, 
 
 Tincat.'^nr. 
 
 Titanium, Part I. ch. iii. led.. 
 19. 
 muriat of, 721. 
 fulphat of, 6j7. 
 Tombac, white, 157. 
 Tungstats, 5; 54. 
 
 Tungsten, Part I. ch. iii. fed. 16. 
 Tung Stic acid. 553. 
 Turbitli mineral, 653. 
 Turpentine, foap of, 607. 
 Types, printers, compofition of, 
 147. 
 
 U 
 Vegetable acids, 5 26. 
 Venus, cryftals of, 792. 
 Verdigrife, 792. 
 Vermilion, 91. 
 
 Vinegar, Part II. ch. v. feft. 
 1 1. 
 of Saturn, 790. 
 Vital air, 6. 
 Vitriol, blue, 648. 
 green, 641. 
 white, 643. 
 ^/VWo/ of potafs, p. 359, note, 
 mother water of, 642. 
 
 '7- 
 Volatile alkali, 382. 
 
 oils, 369. 
 Uranium, Part I. ch. iii. fedl. 
 £8. 
 acetite of, 799. 
 jihofphat of, 741. 
 fulphat of, 655. 
 W 
 Water, 38, Part II. ch. i. 
 weight of, 334. 
 hillory of its decompo- 
 
 (Ition, 341. 
 proofs of its decompo- 
 
 fition, 342. 
 a nonconduftor of heat, 
 
 256. 
 of nitre, 407. 
 Watery fufion explained, 626, 
 
 and note. 
 Wedgeiuood, Thomas, his expe- 
 riments on light, 325, }yi(i> 
 327.329- 
 
 /rf(7^fwo(»(/'s thermometer, 224- 
 Wikklcs'i experiments on fpeci- 
 
 fie caloric, 263. 
 Wine, effential fait of, 777. 
 ^W.condudling power of,252. 
 
 Y 
 Tttria, 2»8. 
 
 Z 
 Zero, real attempt to difcover, 
 
 271. 
 Zinc, Part I. ch. in. fedl. 9. 
 
 acetite of, 787. 
 
 benzoat of, 822. 
 
 borat of, 750. 
 
 carboHat of, 776. 
 
 fluat of, 767. 
 
 laftat of, 817. 
 
 malat of, 816. 
 
 muriat of, 708. ■• 
 
 nitrat of, 679. 
 
 oxalat of, 8c6. 
 
 phofphat of, 737. 
 
 ioap of, 597. 
 
 fulphat of, 643. 
 
 tartrite of, 81 2. 
 Zirconia, page 363, note. 
 Zoonic acid, 547. 
 
 C tt E 
 
 Cherubim. CHERUBIM were emblematical figures ; of which 
 « an account, a very vague one indeed, has been given in 
 
 the Encyclopedia Britannica. We are far from think- 
 ing ourfelves qualified to improve that account, or to 
 explain emblems in the Jewifh worthip, which even Jo- 
 fephus did not underftand ; and we certainly (hould not 
 have refumed the fubjeft but to gratify a numerous 
 clafs of our readers, and to comply with the requeft of 
 fome highly refptfted friends. 
 
 The followers of Mr Hutchinfon, who are firmly per- 
 fuaded that their mafter brought to light from the 
 writings of the Old Teftament many important doc- 
 trines which had lain concealed from all the piety, all 
 the induRry, and all the learning of 1700 years, be- 
 lieve that, among other things, he and they have been 
 able to afcertain the form and the import of the He- 
 brew Cherubim. Their difcoveries on this fubjedt, as 
 we have been loid by better judges than we pretend to 
 be, are more clearly ftated by Mr Parkhuril in his He- 
 brew Lexicon, than by any other writer of that fchool. 
 We (hall therefore lay before our readers his doftrine 
 refpefting the form of the artificial cherubs, as well as 
 of their emblematical meaning ; arid fubjoin a few re- 
 marks, which the nature of his realoning has forced 
 from us. 
 
 " Firjl, then, as to ihe form of the artificial cherubs 
 in the tabernacle and temple. Mofes (fays our author) 
 was commanded (Exod. xxv. 18, 19.) ' Thou fhalt 
 make two cherubs : of beaten gold flialt thou make 
 them at the two ends of the mercy-ftat. And thou 
 
 CHE 
 
 (halt make one cherub at the one end, and the other Cherubin: 
 cherub at the other end : msan )o, out of the mercy- ' •''—'- 
 feat (Margin Eng. Traflat. of the matter of the mer- 
 cy-feat) fhall ye make the cherubs at the two ends 
 thereof.' All which was accordingly performed (Exod. 
 xxxvii, 7, 8.), and thefe cherubs were with the ark pla- 
 ced in the holy of holies of the tabernacle (Exod. xxvi. 
 33, 34. xl. 20.) ; as thofe made by Solomon were af. 
 terwardc in the holy of holies of the temple (i Kings 
 vii. 23, 27.) 
 
 We may obferve that in Exodus Jehovah fpeaks to 
 Mofes of tire cherubs as of figures well known ; and no 
 wonder fince they had always been among believers in 
 the holy tabernacle from the beginning. (See Gen. iii. 
 24. Wifd. ix. 8. And though mention is made of their 
 faces (Exod. xxv. 20. 2 Chron. iii. 13.), and of their 
 wings, (Exod. xxv. 20. I Kings viii. 7. 2 Chron. iii, 
 II, 12.); yet neither in Exodus, Kings, nor Chro- 
 nicies, have we any particular defcription of their form. 
 This is however very exaftly, and, as it were, anxioufly 
 fupplicd by the prophet Ezekicl, ch. i. 5. ' Out of the 
 midll thereof ( ;'. e. of tiie fire infolding itfelf, ver. 4.) 
 nioT the likenefs of four livings creatures or animals ; 
 ninS Q1N mo-r the likenefs of a man (being) with them.' 
 This lall Hebrew exprefiion cannot mean that thev, 
 t. e, the four animals, had the likenefs of a man, which 
 interpretation would indeed make the prophet con- 
 tradict himfelf (comp. ver. 10.) ; but it imports that 
 the likenefs of a man in glory, called (verfe 26.) 
 aiH PX1D3 mm the likenefs as the appearance of a man, 
 3 E 2 and
 
 CHE [ 404 ] CHE 
 
 Cherabim. and particularly defcribed in that and the following piece of gold as that was' (Exod, xxv. 18, 19. xxxvii. Cl.cmbi'm, 
 
 ^~~^''~~^ verfcs, waswitli them. Ver. 6. ' And there were four p.). Now the mercy-feat, made of gold and crowned, v~-- 
 
 faces to one (nwT or fimilitude), and four wings to one, was an emblem of the Divinity of Chrift (See Rom. ili. 
 
 on'? to thi'm. So there were at lead two compound fi- 25. The cherubs therefore reprefented not the ange- 
 
 gures. Ver. lo- ' And the likenefs of their faces; the lie, but the Divine nature. 
 
 face of a man, and the face of a lion, on the right fide, " ^'Uy, The typical blood of Chrift was fprinkled 
 
 to them four ; and the face of an ox to them four ; and before tlieni on the great day of atonement (compare 
 
 the face of an eagle to them four.' Ezekiel knew (ch. Exod. xxxvii. 9. Lev. xvi. 14. Heb. ix. 7, 12.) : And 
 
 X. I. 20.) that thefe were cherubs. Ver. 2i. ' Four this cannot in any fenfe be referred to created angels, 
 
 faces inub to one (cherub) and four wings to one.' but mud be referred to Jehovah only ; becanfe. 
 
 This text alfo proves that the prophet faw more cherubs " t^thly. The liigh priell's entering into the holy of 
 
 than one, and that each had four faces and four wings, holies on that day, reprefented Chrill's entering with 
 
 And we may be certain that the cherubs placed in the his own blood into heaven ' to appear in the prefence 
 
 holy of holies were of the form here defcribed by the of God for us' (Heb. ix. 7, 24.) And, 
 
 pried and prophet of Ezekiel, becaufe we have already 5'''6'' When God ' raifed Chrid (the humanity) 
 
 feen from Exodus, t Kings, and z Chronicles, that from the dead, he fet him at his own right hand in the 
 
 they likewife had faces and wings, and becaufe Ezekiel heavenly places, far above, 'TnEPANn, all principality 
 
 knew what he faw to be cherubs, and becaufe there and power, and might and dominion, and every name 
 
 were no four faced cherubs any where elfe but in the that is named, not only in this world, but alfo in that 
 
 holy of holies; for it is plain from a comparifon of which is to come (Eph. i. 21.). Angels and antho- 
 
 Exod. xxvi. I, 31. I Kino-s vi. 29, 32. and 2 Ciiron. rities and powers being made fubjeft unto him' (l Peter 
 
 iii. 14. with Ezekiel xli. 18, ig, 20. that the artiiicial iii. 22.) 
 
 cherubs on the curtains and vail of the tabernacle, and " bthly. The prophet Ezekiel faith (ch. x. 20.), 
 
 on the walls, doors, and vail of the temple, had only ' This is the living creature, n'nn (which mud mean 
 
 tv/o faces ; namely, thofe of a lion and of a man. one compound figure, comp. ver. 14.) that .\- faw' nnn 
 
 " For it mud be obferved further, that, as the word indead of, a fubditute of ' the Aleim of Ifrael. nnn, 
 
 ana is ufed for one compound figure with four faces, it is granted, may refer either to fituation or fubditu- 
 
 and D'm3 in the plural for feveral fuch compounds (fee tion, (fee Gen. xxx. 2. 1. 19.) as the fenfe requires. 
 
 Exod. xxv. 18, 19. xxxvii. 8. I Kings vi. 23 — 26 ), Here, notwilhilanding what is faid ver. 19. the latter 
 
 fo is 3113 applied to one of the cherubic animals, as to fenfe is preferable ; becaufe it was the glory of the God 
 
 the ox, Ezek. x. 14.; (compare ch. i. 10.) to the of Ifrael, i. e. the God-man in glory, (compare ch. i. 
 
 coupled cherub, or lion-man, Ezek. xli. 18. ; and D'^tis 26.) not the Aleim (the Trinity) of Ifrael that were 
 
 to feveral of the cherubic animals, as to feveral oxen, 1 over the cherubim ; and the text fays not, tlvfi were 
 
 Kings vii. 36. (compare ver. 29.) to feveral coupled the living creatures, but, this was the living creature, 
 
 cherubs, Exod. xxvi. I. I Kings vi. 32, 35 & al. I which I faw ''n-'ii" 'rhK nnn.' Now the glory was over 
 
 proceed to fhew. both the cherubims, ver. 19. but one compound cherub 
 
 " Seconefly, of wliat the cherubs were emblems, and only was a fubditute of the Aleim. 
 
 with what propriety. " If 't dionld be here afted, Wh)'' then were there 
 
 " That the cherubic figures were emblems or repre- two compound cherubs in the holy of holies ? I anfwer, 
 fentatives of fomething beyond themfelves is, I think, Had there not in this place been two compound che- 
 agreed by all, both Jews and Chridians. But the quef- rubs, it would have been naturally impoflible for them 
 tion is, Of what they were emblematical ? To which I to reprefent what was there defigned ; for otherwife, 
 anfvver in a word, Thofe in the holy of holies were em- all the faces could not have looked inwards toward each 
 blematical of the ever-blefled Trinity in covenant to re- other, and down upon the mercy-feat, and on the inter- 
 deem man, by uniting the human nature to the Second ceding high pried fprinkling the typical blood of Chrid, 
 Perfon; which union was fignitied by the luiion of the (fee Exod. xxy.vii. y.) and at the lame time have look- 
 faces of the lion and of the man in the cherubic exhi- ed outward toward the temple, rraS (Vulg. ad domum 
 bition, Ezek. i. 10. compare Ezek. xli. 18, 19. The exteriorum, to the outer houfe.) 2 Chron. iii. 13. Or, 
 cherubs in the holy of holies were certainly intended to in other words, the Divine Perfons could not have been 
 reprefent fome beings in heaven, becaufe St Paul has reprefented as witnefllng to each other's voluntary en- 
 expreisly and infallibly determined that the holy of ho- gagements for man's redemption, as beholding the la- 
 Ijes was a figure or type of heaven, even of that heaven critice of Chrid's death, typified in the Jewifli church, 
 where is the' peculiar refidence of God (Heb. ix. 24.). and at the fame time as extending their gracious re- 
 And therefore thefe cherubs reprefented either the ever gards to the whole world. _ (See Ifa. liv. 5. and Spear- 
 blefTed Trinity with the man taken into the elfence, or man's Inquiry, p. 382. edit. Edinburgh, 
 created fpiritual angels. The following reafons will, I " The coupled cherub, or lion-roan, on the vail and 
 hope, clearly prove them to be emblematical of the curtains of the outer tabernacle, and on the vail, doors, 
 former, not of the latter : and walls of the temple, accompanied with the emble- 
 
 " I/?, Not of angels ; becaufe (not now to infift on matic palm-tree, is fuch a ftriking emblem of the lion of 
 
 other ci'rcumftances in the cherubic form) no tolerable the tribe of Judah (Rev. v. 5.) united to the man 
 
 reafon can be afllgned why angels diould be exhibited Chrift Jefus, as is eafy to be perceived, but hard to be 
 
 with four faces apiece. evaded. Thefe coupled cherubs appropriate the taber- 
 
 " 2il/y, Becaufe the cherubs in the holy of holies of nacle or temple, and their vails, as emblems of Chrift, 
 
 the tabernacle were, by Jehovah's order, ' made out of and exprefs in vifible fymbols what he and his apoftles 
 
 the matter of the raercy-feat, or beaten out of the fame do in words. See John ii. 19, 21. Heb. viii. 2. ix. 1 1. 
 
 X. 20. 
 
 I
 
 CUE [ 
 
 Clxru'iim. X. 20. comp. Matt, xxvii. ^i. And as the texts _ 
 ' " \i • cited from the New Tellunient afford us divine antliori- 
 ty for afTertiiig that the outer tabernacle or temple was 
 a type of the body of Chrilt, fo they fiirnilli us with 
 an irrefragable argument to prove that the cherubs on 
 their curtains or walls could not rcprcfent angels. For 
 did angels dwell in Chrill's body ? No, furely ; But 
 • in him dwelt all the fulnefs of the Godhead bodily.' 
 (Col. ii.,9.) 
 
 "I gO on to confider the propriety of the animals in 
 the cherubic exhibition reprefenting tht Three Perfons 
 in the ever-blcfled I'rinity. And here to obviate any 
 undue prejudice which may have been conceived againlt 
 the Divine Perfons being iymbolicallv rcprefented under 
 any animal forms wtiatever, let it be remarked that Je- 
 hovah appeared as three men to Aliraliam (Gen. xviii. ); 
 that the ferpent of brafs fct up by God's conjmand in 
 the wildcrnefs was a type or emblem of Chrift, God- 
 man, lifted up oil the crofs (comp. Num. xxxi. i — 9. 
 with John iii. 14, 15.); that at Jcfus's baptifm the Ho- 
 ly Spirit dcfcended in a bodily (hape, like a dove, upon 
 him (Luke iii. 21, 22.); that Chriil, as above intima- 
 ted, is exprefsly called the lion of the tribe of Judah 
 (Rev. V. 5.) ; and continually in that fymbolical book 
 fet before us under the fimilitude of a lamb. All thefe 
 are plain fcriptural reprefentations, each of them admi- 
 rably fuited, as the attentive reader will eafdy obferve, 
 to the particular circumftances or fpecific defign of the 
 exhibition. Why then fhonld it appear a thing incre- 
 dible, yea why not highly probable, that Jehovah Aleim 
 fhould, under the typical ilate, order his own Perfons 
 and the union of the manhood with the efTence to be 
 reprefented by animal forms in the cherubim of glory ? 
 Efpecially if it be confidei-ed that the three animal 
 forms, exclufive of the man (who flood for the very 
 human nature itfelf) are the chief of their refpeftive 
 genera : the ox or bull of the tame or graminivorous ; 
 the lion, of the wild or carnivorous ; and the eagle, of 
 the winged kind. — But this is by no means all : For 
 as the great agents in nature, which carry on all its 
 operations, certainly are the fluid of the heavens, or, in 
 other words, the fire at the orb of the fun, the light if- 
 fuing from it, and the fpirit or grofs air conllantly fup- 
 porting, and concurring to the aiifions and effedls of the 
 other two ; fo we are told (Pfal. xix. i.) that a"'3U'n 
 'rx Tias a'lEco the heavens (are) the means of declaring, 
 recounting, or particularly exhibiting the glory of God, 
 even his eternal power and godhead, as St Paul fpeaks, 
 Rom. i. 2D. And accordingly Jehovah himfelf is fome- 
 times, though rarely (1 prefume for fear of millakes) 
 called by the very name n'ow or X'W heavens in the Old 
 'J'eflament, fee 2 Chron. xxxii. 20. (comp. 2 Kings 
 xix. 14. Ifa. xxxvii. 15.) Dan. iv. 23. or 26.; as he is 
 more frequently expreffed by On^an^ heaven in the New. 
 (See Mat. xxi. 25. Mark xi. 30. 31. Luke xv. 18, 21. 
 xx. 4, 5. John iii. 27.) Yea not only fo, but we find 
 in the Scriptures both of the Old and New Teftament, 
 that the Perfons of the eternal Three and their econo-' 
 
 uft Mai 
 
 c 
 
 Luk i. 
 
 H E 
 
 IV. 2. or III. 20. J-,uk 1. 78. ii. 32. Jchn i. 4 — 9 
 viii. 12. xii. ^5, 36, 46.) The Third Perfou has no - 
 other diftinctivc name in fcripture but """ in Hebrew, 
 and nvjuM-' in Greek (both which words in their pri- 
 mary fenle denote the material fpirit or air in motion), 
 to which appellation the epithet '■'"'P. "J-i" holy, or one 
 of the names of God, i^ ufually added : and the aftions 
 of the Holy Spirit in the fpiritual fyftem are defcribed 
 by thofe of he air in the natural (See John iii. 8. xx. 
 22. AiTts ii. 2.) Thus, then, the fecond and Third Per- 
 fons ot the ever blelTcd Triiiity are plainly reprefented 
 in fcripture by the material light and air. But it is 
 further written, Jehovah thy Aleim is a confuming 
 fire. Dcut. iv. 24. (Comp. Deut. ix. 23. Heb. xii. 
 29. Pfal. xxi. ic. Ixxviii. 21. Nah. i. 2.) And by fire, 
 dtTivtrd either immediately or mediately from heaven, 
 were the typical facrifites confumed under the old dif- 
 penfation. Since, then, Jehovah is in fcripture repre- 
 fented by the maleiial heavens, and even called by their 
 name, and efpecially b) that of fire, and fince the Se- 
 cond and Third Perfons are exhibited refpeftively by 
 the two conditions of light and fpirit, and fince fire is 
 really a condition of the heavenly fluid as much diftindl 
 from the other two as they are from each other, it re- 
 mains that the peculiar einblem of the Firfl Perfon (as 
 we ufually fpeak) of the eternal Trinity, confidered 
 with refpeft to the other two, be th^ fire. 
 
 " Bearing then in mind that tlie perfonality in Jeho- 
 vah is in fcripture reprefented by the material Trinity 
 of nature ; which alio, like their divine antitype, are 
 of one fubftance, that the primary fcriptural type of 
 the Father is fire; of the Word, light ; and of the 
 Holy Ghoft, fpirit, or air in motion ; we lliall eafilv 
 perceive, the propriety of tl'.e cherubic emblems. For 
 the ox or bull, on account of his horns, the curling hair 
 on his forehead, and his unrelenting fury when provo- 
 ked (fee Pfal. xxii. 13.) is a very proper animal em- 
 blem of fire ; as the lion from his ufual tawny gold- 
 like colour, his flowing mane, his fhining eyes, his great 
 vigilancy and prodigious ftrength, is of light; and thus 
 likewife the eagle is of the fpirit or air in aiitlon, from 
 his being chief among fowls, from his impetuous 100- 
 tion (ice 2 Sam. i. 25. Job ix. 26. Jer. iv. 13. Lam. iv. 
 19.), and from his towering and furpriling flights in 
 the air (fee Job xxxix. 27. Prov. xxiii. ;. xxx. 19. Ifa. 
 xl. 31. and Bochart, vol. iii. p. 173.) And the heathen 
 ufed thefe emblematic animals, or the like, fometimes 
 feparate, fom'etimes joined, in various manueis, as repre- 
 fentatives of the material Trinity of nature, which they 
 adored. Thefe particulars Mr Hutchinfon has pro- 
 ved with a variety of ufeful learning, vol. -rnrp. 381, 
 et feq. and any perfon who is tolerably acquainted with 
 the heathen mytiiology will be able to iiicrcafe his va- 
 luable colledfluu with many inflances of the fame kind 
 from modern as well as ancient accounts of the pagan 
 religions., 
 
 " Thus, then, the faces of the ox, the lion, and the 
 eagle, reprefenting at fecond hand the Three Perfons 
 
 Cherubim. 
 
 mical operations in the fpiritual, are reprefented by the of Jehovah, the Father, the Word, and the Holy Spi- 
 
 three conditions of the celeftial fluid and their opera, rit ; and the union of the divine light with man beins 
 
 tions in the material world. Thus the peculiar emblem plainly pointed out by the union of the faces of the 
 
 of the Word or Second Perfon is the vDiy or light, and lion and the man (fee Ezek. i. 10. xll. 18.), we may 
 
 he is and does that to the fouls or fpirits of men which fafely affert, that the cherubim of glory (Heb. ix. c.) 
 
 the material or natural light is and does to their bo- in the holy of holies were divinely inftituted and proper 
 
 dies. (See inter al. 2 Sam. xxiii, 4. Ifa. xlix. 6. Ix. i. emblems of the Three Eternal Perfons in covenant to 
 
 redeem
 
 CHE 
 
 'frheru' im. rcJcciTi man, and of the union of tlie divine and human 
 ' ' 'f~~ nalut-es in the perfon of Chrifl. And we find (Gen. 
 iii. 24 ) that immediately on Adam's expidfion from 
 ]);iiadii'c, and the cefTatioD of the firft u\- paiadifiacal 
 d fpenfation of rchgion, Jehovah Alcim hmilclt let up 
 tbiTe emblom-;, together with the burning flame 
 nssnron niliing upon itfelf, to keep the way to the tree 
 of life; undoubtedly, coiifidering the ferv ices performed 
 before them, iK>t to hinder, but to enable, man to pafs 
 through it." 
 
 I'hus far Mr Parkhurft; and to his difTertation where 
 is the man who will deny the merit of erudition, com- 
 bined with ingenuity ? To the latter part of his rea- 
 foning, however, objeftions obtrude themfelvcs upon us 
 of fuch force, that we know not how to anfvver them. 
 The reader obferves, that, according to this account, 
 the cherubim are only it fecofid hand emblematical of the 
 'Holy Trinity, and that the primary emblem is that fluid 
 which the author conceives to lill the folar fyftem, and 
 to be one fubllance under the different appearances or 
 nioditications oijire, light, and grofs air. But unfortu- 
 nately for this reafoning, we are as certain as we can 
 be of any matter of fa6t, that Jire anti air are not one 
 lubftance ; that the grofi air itfelf is compounded of 
 very different fubifances ; and that even light is a diffe- 
 lent fublfance from that which caufes in us the fenfa- 
 ticn of heat, and to which modern chemifts have given 
 the name of fa/or/'i,- (See C hem isTRY-/n(/fx in this Sup- 
 plement). We admit, that the primary atoms of all 
 matter nw^ be fubitances of the very fame kind, though 
 ■we do not certainly knoiu that they are: but this makes 
 nothing for our author's hypothefis ; becaufe the fun 
 and all the planets muft, in that cafe, be added to his one 
 
 t 406 ] 
 
 CHE 
 
 any propriety, or without the greatcft folecifm, be laid CHeruIi-'i. 
 and dclcrihed to fall down before and worfhip other ' » 
 emblematical reprefentations of the fame divine nature 
 and perfeftioiis : And therefore, whatever thefe beafts 
 were emblems of, they could not be tlierubim in Mr 
 Hutchlnfon's fenle ot that word ; it being as coritrary 
 to the rational explanation of a viiion to fay that one 
 emblem of the divinity fllould worlhip another emblem 
 of it, as it is contrary to the reafon ot mankind, 'and to 
 all our notions either of the Godhead or of worihjp, to 
 fay that the Trinity worfhipped the Trinity, or any 
 one t'trfon in the Trinity." 
 
 This objection is admitted by our learned author to 
 be a very plaufible cue. To us it appears unanfwerable. 
 He aniwers it, however, in the following words : 
 
 " Let it be carefully obferved, that thefe reprefenta- 
 tions in Rev ch. v. and xix. are not only vliional but 
 hieroglyphical, and therefore mull be explained accord, 
 ing to the analogy of fuch emblematical exhibitions ; 
 and as at ver. 6. ' the lamb, as it had been flain, having 
 feven horns and feven eyes, (landing in the midll of the 
 throne, and of the four animals, and of the four-and- 
 twenty elders,' is evidently iymbolical of the Lamb of 
 God now raifed from the dead, and inverted with all 
 knowledge and power both in heaven and in earth ; 
 fo ' the four animals falling down before him' (ver. 8.), 
 and, as it is expreffed (ch. xix. 4.), ' worftipping God 
 who fat upon the throne,' muft, in all reafon, be ex- 
 plained fymbolically likewife, not from any abftraft or 
 metaphyfical notions we may have framed to ourfelves 
 of worfhip in general, but from the fpecific and pe- 
 culiar circumilances of the cafe before us. Thus, 
 likewife, when in i Chron. xxix. 20. ' All the con- 
 
 fubftance, which would no longer appear under a triple gregation worfhipped Jehovah and the king, namely 
 
 form. Could it indeed be proved, that all men from David, the worfhip to both is expreffed by the fame 
 
 Adam downwards, who made ufe of cherubic figures ftrong phrafe — ': ■nnnii* proftrated themfelves to, LXX. 
 
 for the very fame purpofe with the ancient Jews, belie- »p5<r(xi/»>iirav. ; yet furely no one will fay that the people 
 
 ited that fire, air, and light, are different modifications meant to worfhip David as God, but only to acknow- 
 
 of the fame fubftance, their belief, though erroneous, ledge him as king. So Adonijah, who had contefted 
 
 would be a fufficient foundation for our author's reafon- the crown with Solomon, came, innwi and worfhipped 
 
 «Ch.v. 
 six, 4. 
 
 ing ; but of this no proof is attempted, and certainly 
 none that is fatisfaftory could be brought. 
 
 Our learned authcir, indeed, takes much for granted 
 without proof. He has not proved that anywhere 
 the bull was the emblem or hieroglyphic oi Jire, the 
 lion of light, or the eagle of air. We do not, it muft 
 be owned, know that fuch hieroglyphics were not ufed 
 in Egypt and other countries before the introduftion 
 of alphabetical charafters ; but unlefs they were fo ufed 
 by Adam, all that is here faid of the propriety of thefe 
 smbltm.s muft go for nothing: Indeed we fee not their 
 peculiar propriety. The tawny colour, flowing mane, 
 and fiercenefs of the lion, might, for any thing that 
 we can perceive to the contrary, reprefent Jire as fitly 
 as the horns, curling hair, and fury of the bull ; and if 
 ■it be true, as is generally faid, that the eagle can look 
 jleadily on the fun, he feems, of all the three, to be 
 the fitteft emblem of light. 
 
 But there are other objcdlions to this interpretation 
 of the word cherubim. The four animals in the Revela- 
 tion, which were undoubtedly cherubim, as well as the 
 four and twenty elders, fell down before the Lamb, 
 i. and worfhipped God*. Now, fays Dr Gregory Sharp, 
 " it is fcarce to be conceived, if thefe four beafts were re- 
 
 King Solomon (l Kings i. 53.), not as God doubt- 
 lels, but as king, thereby furrenderiiig his own claim to 
 the throne. However ' contrary therefore it may be 
 to the reafon of mankind, and to all our notions either 
 of the Godhead or of worfhip, to fay that the Trinity 
 wovlhipped the Trinity, or any one Perfon of the Tri- 
 nity,' /'. e. with divine worfhip as a creature worfhips 
 his Creator ; yet it is by no means contrary to the ra- 
 tional and fcriptural explanation of an emblematic vi- 
 fion, to fay that the in'croglyphical emblems of the 
 whole ever-bleffed Trinity fell down and worfhipped 
 the hieroglyphical emblem of the God-man, or God 
 who fat upon the throne. Since fuch falling down, 
 proilration, or worfhipping, was the ufual fymboHcal 
 aft, as it ftill is in the eaft, not only of divine worfnip, 
 but of acknowledging the regal power to be in the per- 
 fon fo worfhipped ; and thefe afts of the cherubic ani- 
 mals in Rev. v. 6. xix. 4. meant nothing more than 
 either a ceffion of the adminiftration of all divine power 
 to Chrifl God-man, or a declaration of the divine Per- 
 fons, by their hieroglyphical reprefentatives, that He 
 muft reign till all his enemies were made his footilool. 
 Comp. Mat. xxviii. 18. 1 Cor. xv. 25." 
 
 With every inclination to honour the memory of Mr 
 
 prefeiitativesof the divine jierfons, that they could with Parkhurft, who was certainly a fcholar, and, which is 
 
 of
 
 CHE [ 407 ] CHE 
 
 Cher*, of more value, a pious and a good man, we cannot help horfe ; then the ionl ; and before them all, (onr foot -fol- 
 
 — V— ' confidcrlng this anfwer as mere trilling. In the i8th diers ; but the iotit mud be placed in the angle of the 
 
 Pfalm, the Lord is faid to "ride upon a cherub;" board." 
 
 and in Ezekiel, chap. i. there is faid to have "been " From this palTage (fays the prefident) it clearly- 
 over the heads of the cherubim a throne, and upon that appears, that an army with its four an^js muft be pla- 
 throne the likenefs or appearance of a pwn," whom we ccd on each fide of the board, fince an dtpbant could 
 take to be the Son of God incarnate. But is there not Hand, in any other pofition, on the left hand of each 
 any country in which the regal power of the fovereign li'tg ! an^l RADHACANr (a Pandit) informed mc, that 
 is acknowledged by his riding, not upon his fubjetils, the board confilled, like our's, of 64 fquares, half of thein 
 but upon other co-equal fovereigns ? or, in which it is occupied by the forces, and half vacant. Pie added, 
 the cuftom for the fovereign to place his viceroy (for that this game is mentioned in the oldeft law-books, 
 fuch our Saviour in his human nature certainly is) in and that it was invented by the wife of a king, to amiife 
 his throne above himfelf ? him with an Image of war, while his metropolis was be- 
 We muft therefore confefs, that we know not of fieged, in the fecond age of the world. A Jhi[> or boat 
 what the cherubic figures were emblematical, and that is abfurdly fubftitutcd, we fee, in this complex game for 
 he who labours to eftablifh the doftrine of the ever the rat'h, or armed chariot, which the Bengatefe pro- 
 blefTed Trinity by fuch criticifms and reafonings as thofe nounce rot'h, and which the Perfians changed into rohh ; 
 which we have examined, is either a fccret enemy to whence came the rook of fome European nations ; as 
 that dodtrine, or a very injudicious friend. the vierge zndful of the French are fuppofed to be cor- 
 CHESS, the celebrated game, of which a copious ruptions of ferz and Ji/, the prime mini/ler and elephant 
 
 Chefs. 
 
 llAfialhRi 
 fearcbeiy vol 
 
 a. Mem. 9. 
 
 account has been given in the Encyclopaedia, is affirm- 
 ed by Sir William Jones to have been invented by the 
 Hindoos. " If evidence were required to prove this 
 faft (fays he *), we may be fatisfied with the teftimo- 
 
 of the Perfians and Arabs." 
 
 As fortune is fuppofed to have a great fliare in de- 
 ciding the fate of a battle, the ufe of dice is introduced 
 into this game to regulate its moves ; for (fays the Pu- 
 
 ny of the Perfians, who, though as much inclined as ran) " \i cinque be thrown, the king or a patun muft be 
 
 other nations to appropriate the ingenious inventions of moved ; if qualre, the elephant ; if trois, the horje ; and 
 
 a foreign people, unanimoufly agree that the game was if deux, the boat. The king paffes freely on all fides, 
 
 imported from the weft of India in the fixth century of but over one fquare only ; and with the fame limitation 
 
 our era. It feems to have been immemorially known ihe panvn moves, but he advances ftraight forward, and 
 
 in Hindojlan by the name of Cheturanga, i. e. the four kilis his enemy through an angle. The elephant marches 
 
 anga's, or members of an army ; which are thtfe, ele- in all direftions as far as his driver pleafes ; the horfe 
 
 phants, horfes, chariots, and foot foldiers ; and in this runs obliquely, traverfing the fquares; and the /hip 
 
 fenfe the word is frequently ufed by epic poets in their goes over two fquares diagonally." The elephant, we 
 
 defcriptions of real armies. By a natural corruption of find, has the powers of our queen, as we are pleafed to 
 
 the pure Sanfcrit word, it was changed by the old Per- call the general or minijler of the Perfians ; and thejhip 
 
 fians into Chetrang ; but the Arabs, who foon after has the motion of the piece to which we give the unac- 
 
 took poffeffion of their country, had ncitlier the initial countable appellation of lifhop, but with a rcftriftion 
 
 nor final letter of that word in their alphabet, and con- which muft greatly leffen its value. 
 
 fequcutly altered it further into Shetranj, which found In the Purjn are next exhibited a few general rules 
 
 its way prefently into the modern Perfian, and at length and fuperficial direflions for the conduft of the game, 
 
 into the dialeifts of India, where the true derivation of Thus, " the paiuns and the /Zi/^ both kill and may be 
 
 the name is known only to the learned. Thus has a voluntarily killed ; while the kivg, the elephant, and the " 
 
 very fignificant word in the facred language of the horfe, may (lay the foe, but muft not expofe themfelves = 
 
 Brahmins been transformed by fucceftive changes into to be flain. Let each player preferve his own forces" 
 
 axedrez, fcacchi, echecs, chefs, and, by a whimfical con- with extreme care, fecuring his ling above all, and not 
 
 ourrence of circumftances, has given birth to the Eng- facrificing a fuperior to keep an inferior piece." Here 
 
 lifli word check, and even a name to the exchequer of (lays the prefident) the commentator on the Purjn ob- 
 
 Great Britain." lerves, that the horf, who has the choice oi eight moves - 
 
 It is confidently afferted that Sanfcrit books on chefs from -any central pofition, muft be preferred to thefhip, 
 
 exift in Bengal ; but Sir William had feen none of them which has only the choice of four. But the argument 
 
 when he wrote the memoir which we have quoted. He would not hold in the common game, where the bi/hop 
 
 exhibits, however, a defcription of a very ancient Indian and totver command a whole line, and where a knight is 
 
 game of the fame kind, but more complex, and in his always of lefs value than a tower in afkion, or the bi- 
 
 opinion more modern, than the iimple chefs of the Per- fhop of that fide on which the attack is begun. " It 
 
 ^■ans. This game is alfo called Chaturanga, but more is by the overbearing power of the elephant (continues 
 
 frequently Chatiiraji, or the your kings, lince it is played the Purun) that the king fights boldly ; let the whole 
 
 by four perfons reprefenting as many princes, two allied army, therefore, be abandoned in order to fecure the 
 
 armies combating on each fide. The defcription is ta- elephant. The king muft never place one elephant be- 
 
 ken from a book called Bhainijhya Piiran ; in which the fore another, unlefs he be compelled by want of room, 
 
 form and principal rules of this faAitlous warefare are for he would thus commit a dangerous fault ; and if he 
 
 thus laid down : " Eight fquares being marked on all can flay one of two hoftile elephants, he muft deftroy 
 
 fides, the red army is to be placed to tlie eaft, the green that on his left hand." 
 
 to the fouth, the yellow to the weft, and the black to All that remains of the paflage which was copied for 
 
 the north.. Let the elephant (fays the author of the Sir William Jones relates to the feveral modes in which 
 
 Puran) Hand on the left of the king ; next to him the a partial fuccefs or complete victory may be obtained '. 
 
 by.
 
 CHE [ 408 ] . C H I ~ 
 
 Chefs, by any one of the four players ; fur, as in a difpute be- By the author of the Military Guide, this is faid to be Chicha 
 
 Chevretee. t^yggp (^v„ allies, one of the kings may fometimes af- the raoft ufeful of all the inventions for raifing guns . H 
 
 * fume the command of all the forces, and aim at a fepa- into their carriages; and it ieems thefe inventions have ""ney. 
 
 rate conquell. Firft, " When any one king has placed been many. - ' 
 
 himfelf on the fquave of another king (\vlilc:h advantage CHICHA, the name given by the natives to the 
 
 is cnWed Jiribu/'iinn or the //von:) he wins a ilake, which iHand of Jeflo, which lies to the fouth of Oku-JelFo, or 
 
 is doubled if he kill the adverfe monarch when he feizes Segalian ifland. See Segalian in this Supplement. 
 Ills place ; and if he can feat Uimfclf on the throne of CHIMERE, t!;e upper robe worn hy bidiops in 
 
 his allv, he takes the command of the whole army." church and in the Houfe of Peers, to which the lawn 
 
 Secondly, " If he can occupy fucccflively the thrones fleeves arc generally fewtd. Bciore the Reformation, 
 
 of all the three princes, he obtains the victory, which is and even after it till the reign of C^neen Elizabeth, the 
 
 named cheiuraji; and the ftake is doubled If he kill the chimere was always of fcarlst J'llk ; but bifhop Hooper, 
 
 laft of the thre«, juft before he takes poffeflion of his fcrupling firft at the robe itfclf, and then at the colour 
 
 throne ; but if he kill him on his throne, the Hake is of it, as too liglit and gay for the epifcopal gravity, the 
 
 quadrupled. Both in giving the _y7;;/'<j/(;7;a and x\vi che- chimere was afterwards made of Hack J'atln. Tlie ar- 
 
 turaji the king mull be fupported by the elephants, or chieplfcopal chimere has a long train. 
 by all the forces united." Thirdly, " When one player CHIMNEY, a particular part of a houfe well known, 
 
 has his own king on the board, but the king of his which Profeffor Beckmann has, in our opinion, proved 
 
 partner has been taken, he may replace his captive ally, to be an invention comparatively modern. It would be 
 
 if he can feize both the adverfe kings ; or if he cannot very unfair dealing in us to give even a large abftraft ', 
 
 effeft their capture, he may exchange his king for one of one of the nioft curious diflcrtations of a curious 
 
 of them, againil the general rule, and thus redeem the book, which has been but lately publilhed, and thereby 
 
 allied prince, who will fupply his place." This advan- injure the intereft of him to whom the native of Britain 
 
 tage has the name of nripacrl/ljta or recovered by the is indebted for the plcafure of perufing it in his own 
 
 ■lihtg. Fourthly, " If a pawn can march to any fquare tongue. No man, however, can blame us tor here fta- ."" 
 
 on the oppofite extremity of the board, except that of ting, in fupport of our own opinion, the profeffor's an- i 
 
 the king, or that of the (liip, he affumes whatever fwer to the paflage of Ferrari, which we have quoted 
 
 power belonged to that fquare." Here we find the under the word Chimney in the Encyclopedia, 
 rule, with a lllght exception, concerning the advance- "When the triumviri, fays Appian *, cauicd thofe* O, ;,//,', 
 
 rient of paivns, which often occalions a moll intercii.- who had been profcribed by them to be fought for hy'V'l.hh.'w, 
 
 iag ftruggle at our common chefs; but it appears that, the military, fome of them, to avoid the bloody hands 'i 9|^?" ^'^''' 
 
 in the opinion of one ancient writer on the Indian of their perfecutors, hid themfelves In wells, and others, 
 
 game, this privilege is not allowable when a player has as Ferrarlus trandates the words, in fumaria fub teHo, 
 
 three pawns on the board; but when only uue pawn qua Jcilicet fumus e tedo evohnliir (k). The true tranf- 
 
 a;id one (hip remains, the pawn may advance even to lation, however (fays Mr Beckmann j, isyum(?/ai-««flru/i7. 
 
 the fquare of a king or a thip, and affume the porter of The principal perfons of Rome endeavoured to conceal 
 
 either. Fifthly, According to the people ol Lanee, thcmlelves in the fmoky apartments of the upper ftory 
 
 ■where the game was invented, "there could be neither under the roof, which, in general, were inhabited only 
 
 victory nor defeat it a king were left on the plain with- by poor people ; and this feems to be confirmed by 
 
 out force ; a fituation which they named cacacajljt^ha." what Juvenal \ exprefsly fays, Rarus •uenit in cenacula ^ ^^ j 
 
 Sixthly, " If three (hips happen to meet, and the fourth miles. ver. 17, 
 
 (liip can be brought up to them in the remaining angle, " Thofe paflages of the ancients which fpeak of 
 
 this has the name of vrihannauca ; and the player of fmoke rifuig up from houfes, have with equal impro- 
 
 the fourth feizes all the others." priety been fuppofcd to allude to chimneys, as if the 
 
 The account of this game in the original Sanfcrit is fmoke could not make its way through doors and win- 
 in verfe, and there are two or three couplets ftlU remain- dows. Seneca :{; writes, 'Laft evening I had fomej^.;«g 
 ing, fo very dark, either from an error in the manu- friends w-ith me, and on that account a ftronger fmoke 
 fcript, or from the antiquity of the language, that Sir wasraifed; not fuchafmoke,however,asburftsforthfrom 
 William Jones could not underftand the Pandit's cxpla- the kitchens of the great, and which alarms the watch- 
 ration of them, and fufpects tliat even to him they men, but fuch a one as fignifies that guefts are arrived.' 
 gave very indiftindl ideas. It would be eafy, however, Thofe whofe judgments are not already warped by 
 be thinks, if it be judged worth while, to play at the prejudice, will undoubtedly find the true fcnfe of thefe 
 game by the preceding rules ; and a little practice would words to be, that the fmoke forced its way tiirough the 
 perhaps make the whole intelligible. kitchen windows. Had the houfes been built with 
 
 CHEVRETTE, in artillery, is an engine employed chimney-funnels, one cannot conceive why the watch- 
 to raife guns or mortars into their carriage. It is form- men (hould have been alarmed when they obfcrved a 
 ed of two pieces of wood about four icet long, ftanding ftronger fmoke than ufual arifing from them; but as 
 upon a third, which is fquare. The uprights are about the kitchens had no conveniences of that nature, an ap- 
 a foot afunder, and pierced with holes exactly oppofite prchenlion of fire, when extraordinary entertainments 
 to one another, to receive a bolt of iron, which is put were to be provided in the houfes of the rich for large 
 in, either higher or lower at pleafure, to ferve as a fup- companies, feems to have been well founded ; and on 
 port to a handfpike, by which the gun is raifed up. fuch occafions people appointed for that purpofe were 
 
 ftationed 
 
 (a) £; f.art;iStii vwjfifm, 1 Tin rtyui r»if KifKfiiTt ^vj/ntfcii^
 
 CHI [ 409 ] CHI 
 
 Chimney flationeJ In the neighbourhood to be conftantly on tlic does Juh'iis PolKix, who has colletted with great care Chimney. 
 *—-'v~~' rt-atch, and to be ready to cxtingui(h the tkmes in cal'e the Greek names of every part of 3 dwclhng-houfe ; '~~'v~~-' 
 
 a tire fhould happen. There are many other palTages and Grapahlus, w)io in hiter times made a 
 
 to be found in Roman authors of the hke kind, which 
 * Eclog. i. it is hardly ncceflary to mention ; fv.ch as that of Virgil*, 
 
 ' Et jam funuTia procul villarum culmina fumant,' 
 
 and the following words of Plautusf , defcriptive of a 
 mifer : 
 
 « Quin divum atque hominum clamat continuo fidem, 
 ' Suam rem perilffc, feque eradicaricr, 
 • De fuo tigillo fumus ii qua exit foras.' 
 
 In the fcfj)^ of Ariftophanes, referred to in the En- 
 cyclopedia, old Philocleon wiflies to cfcape through 
 the kitchen. Some one alltj, " What is that wliicli 
 makes a noife in the chimney .'" " I am tlie imoke 
 (replies the old man), and am endeavouring to get out 
 at the chimney." " This pafiage, however (fays the 
 ProfeiTor), which, according to the ufual tranllation, 
 feems to allude to a common chimney, can, in my opi- 
 nion, efpecially when we confider the illuftration of the 
 fcholiatls, be explained alfo by a limple hole in the roof. 
 
 collcclion 
 of tiie Latin terms, has not given a Latin word expref- 
 five of a modern chimney *." « Frmci/ii 
 
 Our author admits the derivation of tiie word chim- Marii Gr,i- 
 r.ey to be as we have given it in the Encyclopa;dia; but /"'■'"'' ;?'"■* 
 (fay he) " Caminus fignified, as far as I have been able J^^^'J "'"^ 
 to learn, firft a chemical or mctallurgic furnace, in 
 which a crucible was placed for melting and refining 
 metals ; fecondly, a Imith's forge ; and, thirdly, a 
 hearth on which portable iloves or fire- pans were pla- 
 ced for warming the apartment. In all thefe, however, 
 there appears no trace of a chimney." Herodotus re- 
 lates (lib. viii. c. 137.), that a king of Libya, when 
 one of his fervants alked for his wages, offered him 
 in jeft the fun, which at that time fhone into tlie houfe 
 through an opening in the roof, under which the fire 
 was perhaps made in the middle of the edifice. If fucli 
 a hole mult be called a chimney, our author admits that 
 chimneys were in ufe among the ancients, efpecially in 
 their kitchens ; but it is obvious that fuch chimneys 
 bore no refemblance to our's, through which the fun 
 
 as Reilke has determined ; and indeed this appears to could not dart his rays upon the floor of any apartment, 
 be more probable, as we find mention made of a top or *' However imperfect may be the information which 
 covering J with which the hole was clofed." can be coUefted from the Greek and Roman authors re- 
 in the Encyclopaedia we have faid, that the inftances fpetling the manner in which the ancients warmed their 
 
 of chimneys remaining among the ruins of ancient build- 
 ings are few, and that the rules given by Vitruvius for 
 building them are obfcure ; but we are now fatisfied 
 that there are no remains of ancient chimneys, and 
 that Vitruvius gives no rules, either dbleure or perfpl- 
 
 apartments, it neverthclefs fnews that they commonly 
 ulcd for that purpofe a large fire-pan or portable ftove, 
 in which they kindled wood, and, when the wood was 
 well h'ghted, carried it into the room, or which tliey 
 filled v/ith burning coals. When Alexander the Great 
 cuous, for building what, in the modern acceptation of was entertained by a friend in winter, as the weather 
 tlie word, deferves the name of a eliimney. was cold and raw, a fraall fire bafon was brought into 
 
 " The ancient mafon-work Hill to be foiuid in Italy the apartment to warm it. The prince, obferving the 
 does not determine .the queftion. Of the walls of towns, fize of the veflel, and that it contained only a few coals, 
 temples, amphitheatres, baths, aquedufts, and bridges, dcfired his hoft, in a jeering manner, to bririg more 
 there are fome though very imperfedt remains, in which wood or frankincenfe ; giving him thus to underftaud 
 chimneys cannot be expedled ; but of common dwell- that the fire was fitter for burning perfumes than to 
 ing-houfes none are to be feen except at Herculaneum, produce heat. Anacharfis, the Scythian philofopher, 
 and there no traces of chimneys have been difcovered. though diijileafed with many of the Grecian cuftoms. 
 The paintings and pieces of fculpture which are prefer- prailed the Greeks, however, becanfe they (hut out the 
 ved afford us as little information ; for nothing can be fmoke and brought only fire into their houfes f . We \ Plutanh, 
 perceived in them that bears the fmallefl refemblance to are informed by Lampridius, that the extravagant \\z-^y'"!'°f- 
 a modern chimney. liogabulus caufed to be burned in thefe ilove?, inlleiid 1^'' ^' 
 
 " If there were no funnels in the houfes of the an- of wood, Indian fpiceries and coftly perfume-; J. It is , ' , ,. 
 cients to carry off the fmoke, the dircdlions given by alfo worthy ot notice, that coals were found in fome ofL,,/ j/,-,^ 
 Columella, to make kitchens fo high that the roof (honld the apartments of Herculaneum, as we are told \i-^ Heliogab. 
 not catch fire, was of the utmoft importance. An Winklemann, but neither ftoves nor chimneys." cap. 31. 
 
 accident of the kind, which that author feems to have It is well known to every fcholar, that the ufeful arts 
 
 apprehended, had almofl.happened at Beneventum, when of life were invented in the eaff, and that the cuftoms, 
 the landlord who entertained Msecenas and his company manners, and furniture of ealtern nations, have remain- 
 was making a ilrong lire in order to get fome birds ed from time immemorial almoft; unchanged. In Per- 
 
 fooner roafted. 
 
 ubi fedulus hofpes 
 
 lib.i. fat. J. 
 
 lia, which the late Sir William Jones feems to have con- 
 fidered as the original country ot mankind, the me- 
 thods employed by the inhabitants for warming them- 
 felves have a great refemblance to thufe employed by 
 the ancient Greeks and Romans for the fame purpofe. 
 According to De la Valle, the Perfians make fires in 
 
 ' Paene arlit, macros dum turdos verfat in igne; 
 ' Nam vaga per veterem dilapfo flamma culinam 
 • Vulcano fummum properabat lambere tedium f.' 
 
 Had there been chimneys in the Roman houfes, Vitru- their apartments, not in chimneys as we do, but in 
 
 vius certainly would not have failed to defcribe their ftoves in the earth, which they call /cnnor. "Thefe iloves 
 
 conftruftion, which is fometimes attended with confider- confift of a fquare or round hole, two fpans or a little 
 
 able difficulties, and which is intimately connefted with more in depth, and in fhape not unlike an Italian cafl<. 
 
 the regulation of the plan of the whole edifice. He That this hole may throw out heat fooner, and with 
 
 does not, however, fay a word on this fubjeft j neither more ftrength, there is placed in it an iron veflel of the 
 
 SuppL. Vol. I. Part II. 3 F fame
 
 C H I 
 
 [ 4 
 
 Chimrey. fatre fizc, which is either filled with burning coals, or 
 * " a fire of wood and other inflammahle fubftances is made 
 in it. When this is done, thty place over the hole or 
 ftove a wooden top, like a fmall lo\v table, and tpread 
 above it a large coverlet quilted with cotton, which 
 hangs down on all fides to the floor. This covering 
 condenfes the heat, and caufes it to warm the whole 
 apartment. The people wlio eat or converfe there, 
 and fome who deep in it, lie down on the floor above 
 the carpet, and lean, with their flioulders againll the 
 wall, on fquare cufhions, upon which they fometimes 
 aifo fit ; for the tennor is conftrufted in a place equally 
 dillarit from the walls or. both fides. Thofe who are 
 not very cold only put their feet under the table or co- 
 vering ; but thofe who require more heat can put their 
 hands under it, or creep under it altogether. By thefe 
 means the ftove diffufes over the whole body, without 
 caufing uneafinefs to the head, fo penetrating and a- 
 greeable a warmth, that I never in winter experienced 
 any thii.g more pleafatit. Thofe, however, who re- 
 quire lefs heat let the coverlet hang down on their fide 
 to the Hoor, and er.joy without any inconvenience from 
 the itove the moderately heated air of the apartment. 
 They have a method alio of llirriug up or blowing the 
 fire when neceffary, by means of a fmall pipe united 
 with the tennor or ftove under the earth, and made to 
 projeft above the floor as high as one choofes ; fo that 
 the wind, when a perfon blows into it, becaufe it has no 
 other vent, adts immediately upon the fire like a pair of 
 bellows. When there is no longer occafion to ufe this 
 ftove, both holes are ciofed up, that is to fay, the 
 mouth of the ftove and that of tiie pipe which conveys 
 the air to it, by a flat ftone made lor that purpofe. 
 Scarcely any appeararce of th-.m is then to be percei- 
 ved, nor do they occafion inconvenience, efpecially in a 
 country where it is always cuftomary to cover the floor 
 with a carpet, and where the walls are plaftered. In 
 many parts thefe ovens are ufed to cook viftuals, by 
 placing kettles over them. They are employed alfo to 
 bake bread; and for this purpofe they are covered with 
 a large broad metal plate, on which the cake is laid ; 
 but ii the bread is thick and requires more heat, it is 
 put into the ftove itfelf." 
 
 Oar learned author having proved, to our entire fa- 
 tisfaftion, that chimneys, fuch as we have now in every 
 comfortable room, were unknown to the moft poiiflied 
 nations of antiquity, fets himfelf to inquire into the era 
 ef their invention ; and the oldeft account of them 
 which he finds is an inlcription at Venice, which relates, 
 that in the year 1347 a great many chimneys were 
 thrown down by an earthquake. It would appear, 
 however, that in fome places they had been in ufe for a 
 confiderable time before that period ; fur De Galaris, 
 lii his Hiftory of Padua, relates, that Francefco de Car- 
 rara, lord of Padua, came to Rome in 1368, and find- 
 ing no chimneys in the inn where he lodged, becaufe at 
 that time fire was kindled in a hall in the middle of the 
 floor, he caufcd two chimneys like thofe which had long 
 been ufed at Padua to be conftrucfed by mafons and 
 carpenters, whom he had brougiit along with him. 
 Over thefe chimnevs> the firll ever feen at Rome, he 
 affixed hio arms, which were ftill remaining in the time 
 of De Gataris, who died of the plague in 14C5. 
 
 Though chimneys have been thus long in ufe, they 
 are yet far enough from being brought to perfeftion. 
 
 10 ] CHI 
 
 There is hardly a modern houfe, efpecially if highly fi- Chimney. 
 
 niflied, in which there is not one room at leaft liable to "~~N 
 
 be filled with fmoke when it is attempted to be heated 
 
 by an open fire ; and there are many houfts fo infefted 
 
 with this plague as to be almoft uninhabitable during 
 
 the winter months ; not to mention other great defects 
 
 in common chimneys, which not being fo obvious have 
 
 attracted lefs attention. ^ Many ingenious methods have 
 
 been propofed to cure fmokey chimneys in every iltua- 
 
 tion (fee Smoke, EncycL) ; but Count Rumford's Ef- 
 
 fay on this fnbjeft contains the moft valuable dired'lions 
 
 that we have feen, not only for removing the inconve- - 
 
 niency of fmoke, but likewife for increafing the heat of 
 
 the room by a diminiflied confumption of fuel. 
 
 To thofe who are at all acquainted with the naturd 
 and properties of elaftic fluids, it mull be obvious, that 
 the whole myftery of curing fmokey chimneys confifts in 
 finding out and removing the accidental caufes which 
 prevent the heated fmoke from being forced up the 
 chimney by the preflure of the cool and therefore hea- 
 vier air of the room. Though thefe caufes are various, 
 yet, fays our author, that which will moft commonly be 
 found to operate, is the bad conftruftion of the chim- 
 ney in the neighbourhood of the Jire-place. " The great 
 fault of all the open fire-places or chimneys for burning 
 wood or coals in an open fire now in common ufe is, 
 that they are much too large ; or rather it is the throat 
 of the chimney, or the lower part of its open canal, in 
 the neighbourhood of the mantle, and immediately over 
 the fire, which is too large." 
 
 To this faujt, therefore, the attention fhould be firft 
 turned in every attempt which is made to improve the 
 conftruftion of chimneys ; for however perfect a fire- 
 place may be in other refpefts, if the opening left for 
 the paflage of the fmoke is larger than is neceflfary for 
 that purpofe, nothing can prevent the warm air of the 
 room from efcaping through it; and whenever this hap- ' 
 pens, there is not only an unneceftary lofs of heat, but 
 the warm air which leaves the room to go up the chim- 
 ney being replaced by cold air from without, draughts 
 of cold air cannot fail to be produced in the room, to 
 the great annoyance of thofe who inhabit it. But al- 
 though both thefe evils may be effectually remedied by 
 reducing the throat of the chimney to a proper fize, yet 
 in doing this feveral precautions will be neceffary. And 
 firft of all, the throat of the chimney ftiould be in its 
 proper place ; that is to fay, in that place in which it 
 ought to be, in order that the afcent of the fmoke may 
 be moft facilitated : now as the fmoke and hot vapour 
 which rife from a fire naturally tend iipiuards, the pro- 
 per place for the throat of the chimney is evidently 
 perpendicularly over thejire. 
 
 But there is another circumftance to be attended to 
 in determining the proper place for the throat of a 
 chimney, and that is, to afcertain its diftance from the 
 fire, or hoiv far above the burning fuel it ought to be 
 placed. In determining this point there are many things, 
 to be confidered, and feveral advantages and difadvan- 
 tages-to be weighed and balanced. 
 
 As the fmoke and vapour which afcend from burn- 
 ing fuel rife in confequence of their being rarefied by 
 heat, and made lighter than the air of the furrounding 
 atmofphere; and as the degree of their rarefaction, and 
 confequently their tendency to rife, is in proportion to 
 the inteofity of their Ueatj and further, as they are hot- 
 ter
 
 C H I 
 
 [ 4 
 
 Chimney, ter near the fire than at a greater diflanee from It — It is 
 
 *— — V ' clear that the nearer the throat of a cliiinney is to the 
 
 fire, the iUonger will be what is commonly called its 
 draught, and the lefs danj^er there will be of its fmoking. 
 But, on the other liand, when the draught of a chim- 
 ney is very ftrong, and particularly when this ftrong 
 draught is occafioned by the tliroat of the chimney be- 
 ing very near the fire, It may fo happen that the draught 
 of air into the fire may become fo ilrong as to caufe the 
 fuel to be confumed too rapidly. There are likewife 
 fevcral other inconveniences which would attend the 
 placing of the throat of a chimney very near the burn- 
 ing fuel. 
 
 The pofition of the throat of a chimney being once 
 determined, the next points to be afcertained are its fize 
 and form, and the manner in which it ought to be con- 
 nedled with the fire-place below, and with the open ca- 
 nal of the chimney above. But as thefe inveftigations 
 are intimately connefted with thofe which relate to the 
 form proper to be given to the fire-place itielf, we muft 
 confider them all together. 
 
 Now the defign of a chimney fire being fimply to 
 warm a room, it is neceflary, firft of all, to contrive 
 matters fo that the room (hally be aftually warmed ; fe- 
 coadly, that it be warmed with the fmalltft expence of 
 fuel poffible ; and, thirdly, that in warming it, the air 
 of the room be preferved perfeftly pure, and fit for re- 
 fpiration, and free from fmoke and all difagreeable 
 fniells. 
 
 To determine in what manner a room is heated by 
 an open chimney fire, it will be neceflary firft of all to 
 find out under luhat form the heat generated in the 
 combuftion of the fuel exilts, and then to fee how it is 
 communicated to thole bodies which are heated by it. 
 
 In regard to the firll of thefe fubjedls of inquiry, it 
 is quite certain that the heat which is generated in the 
 combuftion of the fuel exifts under /•a'o perfeftly diftlnft 
 and very different forms. One part of it is combined 
 with the fmoke, vapour, and heated air which rife from 
 the burning fuel, and goes off" with them into the upper 
 regions of the atmofphere; v/hile the other part, which 
 appears to be uncombined, or, as fome ingenious philofo- 
 phers ha-, e fuppofed, combined only with light, and 
 therefore called radiant heat, is fcnt off^ from the fire in 
 rays in all poffible direftions. 
 
 With refpeft to the fecond fubjeft of inquiry, name- 
 ly, how this heat, exifting under thefe two different 
 forms, is communicated to other bodies, it is highly 
 probable that the combined heat can only be commu- 
 nicated to other bodies by aHual contafl with the body 
 with which it is combined ; and with regard to the 
 rays which are fent off by burning fuel, it is certain that 
 they communicate or generate heat only -when and -where 
 they are Hopped or abforbed. In paffing through air, 
 which is traiifparent, they certainly do not communi- 
 cate any heat to it ; and it feems highly probable that 
 they do not communicate heat to folid bodies by which 
 they are reflefled. 
 
 As it is the radiant heat alone which can be em- 
 ployed in warming a room, when fuel is burnt for this 
 purpofe in an open fire-place, it becomes an objeft of 
 much importance to determine how the greateft quan- 
 tity of It may be generated in the combuftion of the 
 fuel, and how the greateft proportion jjoffible of that 
 generated may be brought into the room. 
 
 II ] CHI 
 
 Now the quantity of radiant heat generited in the Chimiv*y 
 combuftion of a given quantity of any kind of fuel de- '~~~^'~~'^ 
 pends very much upon the management of the fire, or 
 upon the manner in which the fuel is confumed. When 
 the fire burns bright, much radiant heat will be fent off 
 from it ; but when it is fmolhered uj>, very little will be 
 generated, and indeed very little combined heat that 
 can be employed to any ufeful purpofe : inoft of the 
 heat produced will be immediately expended in giving 
 elafticity to a thick denfe vapour <.r fmoke, which will 
 be fecn rifing from the fire ; and the combuftion being 
 very incomplete, a great part oi the inflammable matter 
 of the fuel being merely rarefied and driven up the 
 chimney without being inflamed, the fuel will be waft- 
 ed to little purpofe. And hence it appears of how 
 much importance it is, whether it be confidered with a 
 view to economy, or to clcanlinefs, comfort, and ele- 
 gance, to pay due attention to the management of u 
 chimney lire. 
 
 Nothing can be more perfedlly void of common 
 fenfe, and wafteful and llovenly at the fame time, than 
 the manner in which chimney fires, and particularly 
 where coals are burned, are commonly managed by ier- 
 vants. They throw on a load of coals at once, through 
 which the flame is hours in making its way ; and fre- 
 quently it is not without much trouble that the fire is 
 prevented from going quite out. During ihia time no 
 heat is communicated to the room ; and what is ftill 
 worfe, the throat of the chimney being occupied mere- 
 ly by a heavy denfe vapour, not poffefTed of any confi- 
 derable degree of heat, and confequently not havino- 
 much elafticity, the warm air of the room finds lefs dif- 
 ficulty in forcing its way up the chimney and efcaping 
 than when the fire burns bright. And it happeui not 
 unfrequently, efpecially in chimneys and fire-places 111- 
 conftrudled, that this current of warm air from the 
 room which prelTes into the chimney, crof^no- upon the 
 current of heavy fmoke which rites flowly from the 
 fire, obftrufts it in its afcent, and beats it back into the 
 room : hence it is that chimneys fo often fmoke wheu 
 too large a quantity of frefli coals is put upon the fire. 
 So many coals fhould never be put on the fire at once 
 aa to prevent the free paffage of the flame between 
 them. In fliort, a fire fhould never be fmothered; and 
 when proper attention is paid to the quantity of coals 
 put on, there will be very little ufe for the pocker ; 
 and this circuinftance will contribute very much to 
 cleanlinefs, and to the prefervation of furniture. 
 
 As we have feen what is ireceifary to the generation 
 of the greateft quantity of radiant heat, it remains to be 
 determined how the greateft proportion of that which 
 is generated and fent off from the fire in all direiftions 
 may be made to enter the room, and aflift in v?3rming it. 
 
 This muft be done, firft, by caufing as many as pof- 
 fible of the rays, as they are fent off from t'le fire in 
 ftraight lines, to come direHly into the room ; which 
 can only be etfefted by bringing the fire as far forward 
 as poffible, and leaving the opening of the fire-place a« 
 wide and as high as can be done w ithout inconvenience : 
 and, fecondly, by making the fides and back of the 
 fire-place of (uch a form, and ccn.lruftlng them of fuch 
 materials, as to caufe the dircft rays from the fire, 
 which ftrike againft tlieni, to be lent into the room by 
 icfleftion in the greateft abundance. 
 
 Now it will be found upon examination, that the beft 
 3 F 2 f jrm
 
 CHI [41 
 
 Cliimney. form for the vertical fides of a fire-pkcc, or the covir^^s 
 ' ^ ' (as they are called), is that of an upright plane, ma- 
 king an angle with the plane of the back of the fire- 
 place of about 135 degrees. — According to the prefcnt 
 conftruftion of chimneys, this angle is fometimes only 
 «)0, and very feldom above 100 or 110 degrees ; but it 
 is obvious, that in all thcfe cafes the two fides or co- 
 verings of the fire-place are very ill contrived for throw- 
 ing into the room by refleftion the rays from the fire 
 which fall upon them. 
 
 With regard to the materials which (liouM be em- 
 ployed in the conftrudlion of fire-places, particularly 
 the backs and covings, it is obvious that thofe are to 
 be preferred which alforb the leaj}, and of qourfe re- 
 jleS the greateft quantity of radiant heat. Iron, there- 
 fore, and, in general, metals ot all kinds, are the very 
 worft materials which can pofiibly be employed for the 
 backs and covings of chimneys ; whilil fire-ilone white- 
 waflied, or common bricks and mortar, covered with a 
 thin coating of plafter, and white-wafhed, anfwer the 
 purpofe extremely well. A white colour fhould, in- 
 deed, be always given to the infide of a chimney of 
 whatever materials It be conftrufted ; and black, which 
 is at prefent fo common, fhould be carefully avoided, 
 becaufe white reflefts the moft, and black the lead, ra- 
 diant heat. The grate, however, cannot well be made 
 of any thing elie than iron ; but there is no neceflity 
 whatever for that immeiife quantity of iron which fur- 
 rounds grates as they are commonly fitted up, and 
 which not only renders them very expenfive, but efl'en- 
 tially injures the fire-place. 
 
 To have only pointed out the faults of the chimneys 
 in ufe, without fhevving how thefe faults may be corredl- 
 ed, would have been a work of very little value ; but 
 the Count's Treatife is complete, and contains the plain- 
 eft diredlions for the conftrudlion of fire-places. Thefe 
 direftions are introduced by an explanation of forae 
 technical words and expreG'ions. Thus, by the tl.-rcat 
 of a chimney, already mentioned, he means the lower 
 extremity of its canal, where it unites with the upper 
 part of its open fire-place. 7 his throat is commonly 
 found about a foot above the level of the lower part of 
 the mantle, and it is fometimes contraiSed to a fmaller 
 fize than the reft of the canal of the chimney, and fome- 
 times not. 
 Plate XX. Fig. 1. fliews the feftion of a chimney on the com- 
 mon conftrudtlon, in which d e is the throat. 
 
 Fig. 2. fhews the fedtion of the fame chimney altered 
 and improved, in which di is the reduced throat. 
 
 The brea/l of a chimney is that part of it which is 
 immediately behind the mantle. It is the wall which 
 forms the entrance from below into the throat of the 
 chimney in front, or towards the room. It is oppofite to 
 the upper extremity of the back of the open fire-place, 
 and parallel to it : in ftiort, it may be faid to be the 
 back part of the mantle itfelf. — In the figures i, and 
 2. it is marked by the letter d. The width of the 
 throat of the chimney {^d e fig. i.and di fig. 2.) Is ta- 
 ken from the brcaft ot the chimney to the back, and its 
 lengtli is taken at right angles to its width, or in a line 
 parallel to the mantle [a fig. I. and 2.). 
 
 The bringing- forwaid of the fire into the room, or 
 rather bringing it nearer to the front of the opening of 
 the fire-place, and the diminiftiing of the throat of the 
 chimney, being two objefts principally had in view in 
 
 2 ] CHI 
 
 the alterations in fire-places propcfcd by the Count, it CMmnty. 
 is evident that both thefe may be attained merely by ^— v— — ' 
 bringing forward the back of the chimney. The only 
 queftioii therefore is. How far it (liould be brought for- 
 ward ? The anfwer is fliort, and eafy to be under- 
 ftood ; bring it forward as far as poflibie, without di- 
 mlniihing too much the pafTage which niuft be left for 
 the fmoke. Now as this pafiilge, which in its narrow- 
 eft part he calls the throat of the chimney, ought, for rea- 
 fons which have been already explained, to be imme- 
 diately, or perpendicularly over the fire, it is evident 
 that the back of the chimney muft always be built per- 
 feiSly upright. To determine, therefore, the place for 
 the new back, or how far precifely it ought to be 
 brought forward, nothing more is neceflary than to af- 
 certaln how wide the throat of the ciilmney ought to 
 be left, or what fpace muft be left between the top of 
 the breaft of the chimney where the upright canal of 
 the chimney begins, and the new back of the fire-place 
 carried up perpendicularly to that height. 
 
 Numerous experiments have convinced the Count, 
 that, all circumrtances being well confidered, and the 
 advantages and difadvantages compared and balanced, 
 four inches is the beft width that can he given to the 
 throat of a chin;ney, whether the fire-place be deftined 
 to burn wood, coals, turf, or any other fuel. In very 
 large halls where great fires are kept up, it may fome- 
 times, though very rarely, be proper to increafe this 
 width to four inches and a half, or even to five inches. 
 
 The next thing to be confidered is the width which 
 it will be proper to give to the back of the chimney ; 
 and, in moft cafes, this ftiould be one-third of the width 
 of the opening of the fire place in front. It is not in- 
 deed abfulutely neceflary to conform with rigour to this 
 declfion, nor is it always poflibie ; but it fliould inva- 
 riably be conformed to as far as circumftances will per- 
 mit. Where a chimney, fays the Count, is defigned 
 for warming a room of a middling fize, and where the 
 thicknefs of the wall of the chimney in front, meafured 
 from the front of the mantle to the breaft of the chim- 
 ney, is nine inches, I (hould fet off four inches more for 
 the width of the throat of the chimney, which, fuppo- 
 fing the back of the chimney to be built upright, as it 
 always ought to be, will give thirteen inches for the 
 depth of the fire-place, meafured upon the hearth, from 
 the opening of the fire-place in front to the back. In 
 this cafe, thirteen inches would be a good fize for the 
 width of the back ; and three times thirteen inches, or 
 39 inches, for the width of the opening of the fire- 
 place iu front ; and the angle made by the back of the 
 fire-place and the fides of it, or covings, would be jufl 
 '35 degrees, which is the beft pofitlon they can have 
 for throwing heat into the room. This pofition, in- 
 deed. It may fometimes be impolTible to attain in alter- 
 ing chimneys already built ; but a deviation from it of 
 two or three degrees will be of no great corfequence ; . 
 for the points of by much the greateft importance in al- 
 tering fire-places upon the principles here recommend- 
 ed, are the bringing forward the back to its proper 
 place, and making it of the proper width. 
 
 Provifion, however, muft be made for the paffage of 
 the chlmney-fweeper up the chimney; and this may 
 eafily be done in the following manner : In building 
 up the new back of the fire-place ; when this wall 
 (which need never be more than the width of a fingle 
 
 brick
 
 CHI ^ [ 4 
 
 Chinwey. brick in thicknefs) is brought tip fo lifgli that there 
 ^" "V remains no more than about ten or ilcvcn inches be- 
 
 tween what is then the top of it and tlie inliJe of the 
 mantle, or kiwer eKtrcmitv of the bread ot the chim- 
 ney, an opening or door way, eleven or twelve inches 
 wide, mult be begun in the middle of the back, and 
 continued quite to the top of it, which, according to 
 the height to which it will commonly be neccflary to 
 carry up the back, will make tiie opening abundantly 
 fufficicnt to let the chimney-fweeper pafs. When the 
 fire-place is fini(hed, this door-way is to be clofed by a 
 tile or fit piece of ftone placed in it without mortar, and 
 by means of a rabbit made in the brick-work, confined 
 in its place in kich a manner as that it may be eafily 
 removed when the chimney is to be fwept, and re- 
 flored to its place when that work is over. Of this 
 contrivance the reader v/ili be able to form a clear con- 
 ception from fig. 2. which reprefents the feftion of a 
 chimney after it has been properly altered from what 
 is exhibited in fig. I. In this improved chimney k I is 
 the new back of the fire-place ; It the tile or fione 
 which clofes the door-way for the chimney-fxveepev ; 
 d i the throat of the chimney narrowed to four inches ; 
 a the mantle, and h the Hone placed under the mantle, 
 fuppofed to have been too high, in order to diminifh 
 the height of the opening of the fire-place in front. 
 
 It has been obferved above, that the new back, which 
 it will always be found neceffary to build in order to 
 bring the fire fufficiently forward, in altering a chim- 
 ney conilrufted on the common principles, need never 
 be thicker than the width of a common brick. The 
 fame may be faid of the thicknefs neceffary to be given 
 to the new fides or covings of the chimney ; or If the 
 new back and covings are conftrucfted of Hone, one inch 
 and three quarters, or two inches in thicknefs, will be 
 fufficicnt. Care fhould be taken in building up thefe 
 new walls to unite the back to the covings in a folid 
 manner. 
 
 Whether the new back and covings are conftrufted 
 of flone or built of bricks, the fpace between them and 
 the old back and covings of the chimney ought to be 
 filled up, to give greater folldity to the fbni(i|ure. This 
 may be done with loofe rubbifh, or pieces of broken 
 bricks or llones, provided the work be flrengthened by 
 a few layers or courfes of bricks laid in mortar ; but It 
 will be indifpcnfably neceffary to finifh the work where 
 thefe new walls end, that is to fay, at the top of the 
 throat of the chimney, where it ends abruptly in the 
 open canal of the chimney, by a horizontal courfe of 
 bricks well fecured with irjortar. This courfe of bricks 
 will be upon a level with the top of the door-way left 
 for the chimney-fweeper ; and the void behind the door- 
 way mu(l be covered with a horizontal flone or tile, to 
 be removed at the fame time the door is removed, and . 
 for the fame purpofe. 
 
 From thefe defcriptlons it is clear, that where the 
 throat of the chimney has an end, that is to fay, where 
 it enters into the lower part of the open canal of the 
 chimney, there the three walls wliich form the two co- 
 vings and the back of the fire-place all end abruptly. 
 It is^ of much importance that they fhould end in this 
 manner ; for were they to be floped outward, and rai- 
 fed in fuch a manner as to fwell out the upper extremi- 
 ty of the throat of the chimney in the form of a trum- 
 pet, and increafe it by degrees to the fize of the canal 
 
 ^3 ] 
 
 C H I 
 
 of the chii"ney, this manner of uniting the lower e.\. Chimney, 
 tremity uf tlic canal of the chlnuicy with the throat ' v -^ 
 would tend to afTill the winds, which may attempt to 
 blow down the chimney, in forcing their way through 
 the throat, and throwing the fmoke backward into the 
 room ; but when l he t hi oat of I he chimney ends abrupt- 
 ly, and the ends of the new walls form a flat horizontal 
 furface, it will be much more difficult for any wind 
 from above to find and force its way through the nar- 
 row paffage of the throat of the chimney. 
 
 As the two walls which form the new covings of the 
 chimney are not parallel to each other, but Inclined, 
 prefenting an oblique furface towards the front of the 
 chimney, and as they are built perfeftly upright, and 
 quite flat, from the hearth to the top of the throat, 
 where they end, it Is evident that an horizontal fcftlon 
 of the throat will not be an oblong fquare ; but its de. 
 viaclon from that form is a matter of no confequence ; 
 and no attempts (liould ever be made, by twifling the 
 covings above where they approach the breaft of the 
 chimney, to bring It to that form. All twills, bends, 
 prominences, excavations, and other irregularities of 
 forrn in the covings of a chimney, never fail to produce 
 eddies in the current of air which is continually paffing 
 into, and through, an open fire-place in which a fire is 
 burning ; and all fuch eddies dKlurb either the fire or 
 the afcending current of fmoke, or both ; and not un- 
 frequently caufe the fmoke to be thrown back into the 
 room. Hence it appears, that the covings of chimneys 
 fliould never be made circular, or in the form cf any- 
 other curve, but always quite flat. 
 
 For the fame reafon, that Is to faj-, to prevent ed- 
 dies, the brcafl of the chimney, which forms tlrat fide 
 of the throat that is In front or nearefl to the room, 
 fhould be neatly cleaned off, and its furface made quite 
 regular and fmooth. This may be eafily done by co- 
 vering it with a coat of plafler, which may be made 
 tliicker or thinner In different parts, as may be neceffa- 
 ry in order to bring the brtafl of the chimney to be of 
 the proper form. 
 
 With regard to the form of the breaft of a chimney, 
 this IS a matter of very great importance, and which 
 ought always to be particularly attended to. The worfl 
 form it can have Is that of a vertical plane or upright 
 flat ; and next to this the worfl form is an inclined 
 plane. Both thefe forms caufe the current of warm air 
 from the room, which will, in fpite of every precaution, 
 fometimes find its way into the chimney, to crofs upon 
 the current of fmoke which tifes from the fire in a man- 
 ner mofl likely to embarrafs it in Its afcent, and drive 
 it back. 
 
 The current of air which, pafiing under the mantle, 
 gets into the chimney, fliould be made graihally to bend 
 its courfe upwards ; by which means it will unite quietly 
 with the afcending current of fmoke, and will be lefs 
 likely to check it, or force it back into the room. Now 
 this may be effefted with the greateil cafe and certain- 
 ty, merely by rounding off the breaft oi the chimney or 
 back part of the mantle, inftead of leaving it flat or full 
 of holes and corners ; and this of courfe ought always 
 to be done. 
 
 Having thus afcertained the form and pofitlon of the 
 new covings, the ingenious author next turns his atten- 
 tion to the height to which they fhould be carried. 
 This will depend not only on the height of the mantle, , 
 
 but
 
 C H I 
 
 [ 4'4 1 
 
 C H I 
 
 -Cl.im- ey. but alfo, and more efpecially, on tlie height of the 
 » bread (if the eliimney, or of that part of the chimney 
 
 where the bread ends and the iipriglit canal begins. — 
 The bad; and covings iiuid rife a few inches, five or 
 iix for indarice, higher than this part, othcrwifc the 
 throat ot ilie ciiimncy will not be pro])erly formed ; 
 but no advantage would he gained by carrying them 
 ^hi^he,-._ 
 
 One important circumdance refpefting chimney fire- 
 places Hill remains to be confidered ; and that is the 
 grate. In placing the grate, the thing principally to 
 be attended to is, to make the back of it coincide with 
 the back of the fire place. But as many of the grates 
 now in common ufe will be found to be too large, when 
 the fue pkees are altered and improved, it will be ne- 
 ceffary to diminifli their capacities by filling them up 
 at the back and fides with pieces of fire done. When 
 this is done, it is the front of the flat piece of fire-done 
 which is made to form a new back to the grate, which 
 mud be made to coincide with, and make part of the 
 back of the fire place. — But in diminifhing the capaci- 
 ties of grates with pieces of fire-done, care mud be ta- 
 ken not to make them too narroiu. 
 
 The proper width for grates dcdincd for rooms of a 
 middling fize will be from fix to eight inches, and their 
 length may be diminiflied more or lefs according as the 
 room is heated with more or lefs difficulty, or as th.e 
 weather is more or lefs fevere. — But where the width 
 of a grate is not more than five inches it will be very 
 tlifficult to prevent the fire from going out. 
 
 It frequently happens that the iron backs of grates 
 are not vertical, or upright, but inclined backwards. — 
 When thefe grates are fo much too wide as to render 
 it iiecelTary to fill them up behind with fire-done, the 
 inclination of the back will be of little confequence ; 
 for by making the piece of done with which the width 
 of the grate is to be diminiihed in the form of a wedge, 
 or thicker above than below, the front of this done, 
 which in effeft will become the back ot the grate, may 
 be made perfeftly vertical ; and the iron back of the 
 grate being hid in the folid work of the back of the 
 fire-place, will produce no effeft whatever; but if the 
 grate be already fo narrow as not to admit of any dimi- 
 nution of its width, in that cafe it will be bed to take 
 away the iron back of the grate entirely, and fixing the 
 grate firmly in the brickwork, caufe the back of the 
 fire-place to ferve as a back to the grate. 
 
 Where grates, which are defigned for rooms of a 
 middling fize, are longer than 14 or 15 inches, it will 
 always be bed, not merely to diminifh their lengths, by 
 filling them up at their two ends with fire-done, but, 
 forming the back of the chimney of a proper width, 
 ■without paying any regard to the length of the grate, 
 to carry the covings through the two ends of the grate 
 in fuch a manner as to conceal them, or at lead to con- 
 ceal the back corners of them in the walls of the covings. 
 
 Had thefe direftions been duly attended to by the 
 mafons who in Scotland pretend to alter chimneys on 
 the principles of Count Rumford, we diould not have 
 .obferved fo many of the grates placed by them jutting 
 out beyond the mantle of the chimney ; nor of courfe 
 heard fo many complaints of rooms being rendered more 
 
 fmokcv, and the confumption of fuel increafed by thefe Ct iir.ney. 
 pretended iniprovtmcnts. But when the grate is not " * ' 
 fet in its proper place, when its doping non Lack is 
 retained, when no pains have been taken to make its 
 ends coincide with the covliigs.of the fire-place, when 
 tlie mantle, indead of having its back rounded od, is a 
 vertical plane of iron cutting the column of fmokc 
 which rifes beneath it, and, above all, when the throat 
 of the chimney, indead of four, is made, as we often 
 fee, fourteen inches wide ; let it be remembered, that 
 not one of Count Rumford's direftions has been fol- 
 lowed, and that his principles have as little to do with 
 the condrudlion of fuch a chimney as with the building 
 of the wall of China or the pyramids of Egypt. 
 
 To contribute our aid to prevent thefe blunders for 
 the future, we diall here fubjoin the Count's directions 
 for laying out the work ; not to indruA mafons and 
 bricklayers, to whom we earnedly recommend the dudy 
 of the effay itfelf (b), which contains much valuable in- 
 formation that we have omitted ; but merely to give the 
 country gentleman an opportunity of difcovering whe- 
 ther the workmen whom he employs deviates far and 
 needlcfslyfrom the principles which he pretendstofoUow. 
 
 When a chimney is to be altered, after taking away 
 the grate and removing the rubbidi, firil draw a draight 
 line with chalk, or with a lead pencil, upon the hearth, 
 from one jamb to the other, — even with the front of 
 the jambs. The dotted line A B, fig. 3. may repre- 
 fent this line. 
 
 From the middle c of this line, (A B) another line 
 c d is to be drawn perpendicular to it, acrofs the hearth, 
 to the middle d, of the back of the chimney. 
 
 A perfon mud now dand upright in the chimney, 
 with his back to the back of the chimney, and hold a 
 plumb-line to the middle of the upper part of the bread 
 of the chimney ((/, fig. i.), or where the canal of the, 
 chimney begins to rife perpendicularly ; — taking care 
 to place the line above in fuch a manner that the plumb 
 may fall on the line c d (fig. 3.) drawn on the hearth 
 from the middle of the opening of the chimncv in front 
 to the middle of the back, and an affidant mud mark 
 the precife place e, on that line where the plumb falls. 
 
 This being done, and the perfon in the chimney ha- 
 ving quitted his dation, four inches are to be fet off on 
 the line c d, from c, towards d i and the pointy, where 
 thefe four inches end, (which mud be marked with 
 chalk, or with a pencil), will (how how far the new 
 back is to be brought forward. 
 
 Through f, draw the line g h parallel to the line 
 A B, and this line _f h will fliow the direAion of the 
 new back, or the ground line upon which it is to be 
 built. The line ;:/ will diow the depth of the new 
 fire-place ; and if it diould happen that c f\i equal to 
 about one-third of the line A B, and if the grate can 
 be accommodated to the fire-place, indead of its being 
 neceffary to accommodate the tire place to the grate ; 
 ill that cafe, half the length of the line c f n to be fet 
 off fromy on the line ^y A, on one fide to k, and on the 
 other to /", and the line i k will lliow the ground line of 
 the fore part of the back of the chimney. 
 
 In all cafes where the width of the opening of the 
 fire-place in front (A B) happens to be not greater, or 
 
 not 
 
 (b) It cods but two (liillings ; and he mud be a poor bricklayer indeed who cannot afford to pay that fura for 
 inferufiion in the mod important, as well as mod difficult, part of his bufinefs.
 
 CHI [ 415 1 CHI 
 
 Chimney, not more than two or three inches greater than thi-ee only four inches thick, four inches more adilcJ to it for Chimney. 
 
 i—~-yf—' times the width of the new back of the chimney (i i), the width of the throat would have left tiie depth of '— v— 
 
 this opening may be left; and lines drawn from ; to A, the fnt-place meafnred upon the hearth i c ojily eio-ht 
 
 and from /- to B, will (how the width and pofition of inches, which would have been too little • a niche c 
 
 the front of the new covings ; — but when the opening and e was therefore made in the new back of the firc- 
 of the fire-place in front is ilill wider, it muft be redu- place for receiving the grate, which niche was fiy. inches 
 ced ; which is to be done in the following manner: deep in the centre of it, below la inches wide for 
 
 From f, the middle of the line A B, c a and c b equal in width to the grate,) and 23 inches high ■ fi- 
 muft be fet off equal to the width of the back (i k), nilhing above with a femicircular arch, which in its 
 added to half its width (fi) ; and lines drawn from i to higheil part, rofe fevcn inches above the upper part of 
 a, and from k to b, will fhow the ground plan of the the grate. — The door- way for the chimney-fweepcr 
 fronts of the new covings. which begins juil above the top of the niche may be 
 
 When this is done, nothing more will be necefTary feen diftinctly in both the figures 6 and 7. The fpace 
 
 than to build up the back and covings ; and if the fire- marked g, fig. 7. behind this door-way, may either be 
 place is defigned for burning coals, to fix the grate in filled with Joofe bricks, or may be left void. The man- 
 its proper place, according to the diredtions already ner in which the piece of ftoiic f, fig. 7. which is put 
 given. — When the width of the fire-place is reduced, under the mantle of the chimney to reduce tlie height 
 the edges of the covings a A and b B are to make a of the opening of the fireplace, is rounded off on the 
 finiih with the front of the jambs. — And in general it infide in order to give a fair run to the column of fmoke 
 will be beft, not only for the fake of the appearance of in its afcent through the throat of the chimney, is clear- 
 the chimney, but for other reafons alfo, to lower the ly expreffed in this figure. The plan fig. r. and eleva- 
 height of the opening of the fire-place whenever its tion fig. 6. (how how much the width of the opening 
 •width in front is diminiflied. of the fire-place in front is diminiihed, and how the co- 
 
 A front view of the chimney, after it has been thus vings in the new fire-place are formed, 
 altered, is exhibited in fig. 4.. where the under part of A perfett idea of the form and dimenfion of the fire- 
 the door-way is reprefented, as clofed by the white dot- place in its original (late, as alio after its alteration may- 
 ted lines. be had by a careful infpeftion of thefe figures. 
 
 When the wall of the chimney in front, meafured In chimneys, like that reprefented in figure R, where 
 from the upper part of the breaft of the chimney to the the jambs A and B project far into the room and 
 front of the mantle, is very thin, it may happen, and where the front edge of the marble flab 0, which forms 
 efpccially in chimneys defigned for burning wood upon the coving, does not come fo far forward as the front 
 
 of the jambs, the workmen in conftruciing the new co- 
 vi,igs are very apt to place them, — not in the line c A, 
 which they ought to do,— but in the line c 0, which is 
 a great fault. — The covings of a chimney (hould never 
 range be/jitu/ the front of the jambs, however thofe 
 jambs may projeft into the room ; — bitt it is not abfo- 
 
 the hearth, or upon dogs, that the depth of the chim 
 ney, determining according to the directions here given, 
 may be too I'mall. 
 
 Thus, for example, fuppofing the wall of the chi.m- 
 ney, in front, from the upper part of the breail of th 
 
 chimney to the front of the mantle, to be only fou 
 
 inches, (which is fometimes the cafe, particularly in lutely neceifary that the covings (hould maie a firiiP} 
 
 rooms fituated near the top of a houfe), in this cafe, if with the internal front corners of the jambs, or that 
 
 we take four inches for the width of the throat, this they (liould be continued from the back c, quite to the 
 
 will give eight inches only for the depth of the fire- front of the jambs at ji They may finidi in front at 
 
 place, which would be too little, even were coals to be a and b ; and fmall corners A, 0, a, mav be left for p'a- 
 
 burnt inftead of wood. — In this cafe (fays the Count) cing the (hovels,- tongs, &c. 
 
 I (hould increafe the depth of the fire-place at the Were the new coving to range with th'e front cdec 
 
 hearth to 1 2 or 13 inches, and (hould build the back of the old coving 0, the obhquity of the new covint' 
 
 perpendicular to the height of the top of the burning would commonly be too great ; or the aiiirle d c 
 
 fuel (whether it be wood burnt upon the hearth or would exceed 135 degrees, ivbich it never Jhould do, 
 
 coals in a grate) ; and then, (loping the back by a gen- or at leail never be more than a very fnw degrees. No 
 
 tie incHnation forward, bring it to its proper place, inconvenience of any importance will arife from making 
 
 that is to fay, perpendicularly under the back pur t of the the obliquity of the covings Icfs than what is here re- 
 
 ihroat of the chimney. This flope, (which will bring commended ; but maay cannot fail to be produced by 
 
 the back forward four or five inches, or juil as making it much greater. 
 
 much as the depth of the fire-place is inereafed), Thefe extrads, which we have made fo liberally from , 
 
 though it ought not to be too abrupt, yet it ought Count Rumford's eflay on chimney fire-places, will be 
 
 to be quite finiihed at the height of eight or ten fufRcient, we hope, to bring fully within the conipre- 
 
 inches above the fire, otherwife it may perhaps caufe the henlion of thofe who are acquainted with pneumatics 
 
 chimney to fmoke ; but when it is very near the fire, and pneumatic chemiftry the principles on which chim. 
 
 the heat of the fire will enable the current of rifing neys and fire-places (liould be conftrudted ; but fuch as 
 
 fmoke to overcome the obftacle which this (lope will are in a great meafure (bangers to thefe fcicnces will 
 
 oppofe to its afcent, which it could not do fo eafily do well to confult the efTay ilfelf. With a benevolence - 
 
 were the (lope fituated at a greater dillance iroii" the which does him honour, the ingenious author has c.<- 
 
 burning fuel. preflTed a widi that his dodrines on this important fub- 
 
 Fig. 5, 6, and 7, (how a plan, elevation, and feftion jeft may be widely propagated ; and to encourarre ar. 
 
 of a fire-place conllrufted or altered upon this principle, tills to (ludy them, he has declared to the public ?n ge- 
 
 —The wall of the chimney in frojit at a, fig. 7. being neral," that as he dots not intend to take out himfJf, .
 
 C H I 
 
 [ 4t6 ] 
 
 C H 1 
 
 Clilmnay, q,. to fuffcr others to take out, any patent for any in- 
 
 ■Sviecpeii. y^ntion of his which may be of pubh'c utility, all per- 
 
 * foils are at full liberty to imitate them, and vend them, 
 
 for their own emolument, when and where, and in any 
 
 way they may think proper." 
 
 CniMhEr-Siveepers are a clafs of men who earn their 
 fubfiftence by clearing chimneys of foot, which occa- 
 fions them to fmoke. While chimneys continued to be 
 built in fo limple a manner, and of fuch a width as they 
 are llill oblVrved to be in old houfes, they were fo eafily 
 cleaned that this fervice could be performed by a fer- 
 yant with u wifp of llraw, or a little brudiwood faften- 
 ed to a rope; but after the flues, in order to fave room, 
 were made narrower, or when feveral flues were united 
 together, the cleaning of them became fo difficult, that 
 they required boys, or people of fmall fize, accuiloraed 
 to that employment. The firft chimney-fweepers in 
 Germany came from Savoy, Piedmont, and the neigh- 
 bouring territories. Thefe for a long time we.-e the 
 - only countries where the cleaning of chimneys was fol- 
 lowed as a trade ; and hence Profeffor Beckmann con- 
 cludes with great probability, that chimneys were in- 
 vented in Italy. The Lotharingians, however, under- 
 took the bulincfs of chimney- fweeping alfo ; on which 
 account the duke of Lotharingia was llyled the imperial 
 Jire-majler. The fit ft Germans who condefceuded to 
 clean chimneys were miners; and the chimney-fweepers 
 in that empire ftill procure their boys from theforell of 
 Hartz, where the greateft mines arc wrought. Very 
 lately, and perhaps at prcfent, the greater part of the 
 chimney-fweejjers In Paris wercSavoyards, many of them 
 not above eight years of age, who, for the paltry fum 
 of five fous, which they were obliged to fhare with tlreir 
 avaricious mailer, would fcraii ble, at the hazard of 
 their lives, through a narrow funnel fifty feet in length, 
 and with their bcfoms clean it fiom foot and dirt. 
 At what precife period chimncy-fweeping became a 
 trade in England and Scotland, we have not been able 
 to learn ; but among us, as well as e'lewhere, young 
 boys are employed in this bufinefs, who are faid to be 
 very harlhly treated by fellows who ftole them from the 
 doors of cottages in the country. Tiiat children have 
 been fometimes kidnapped by chimney-lweepers, we can 
 have no doubt ; but that the praflice is frequent, we 
 do not believe. We think however that the bufinefs 
 might be wholly abolilhed ; for a narrow funnel might 
 certainly, if not very crooked, be fwept by a buijdle of 
 ftraw or brulhwood fullencd to a rope, as well as one 
 that is wider: and the bricks which leparate the conti- 
 guous flues we know to be lefs injured by this method 
 of fweeping, when cautioufly gone about, than by fend- 
 ing boys up the chimneys. 
 
 On the 4th July 1796, letters patent were grant- 
 ed to Daniel Davis, of the paiilh ot St Giles, Middle- 
 fex, for his invention of a machine, by which he pro- 
 pofes to fweep and cleanfe chimneys, and extinguifh 
 chimneys on fire, without any perion going up the 
 fame, as is now the pratlice. The machine conlifts of 
 an apparatus of rack-work, of various lengths, which, 
 by means of a hand-turn, is made to afcend the chim- 
 ney. The lengths of the rack-work are joined toge- 
 ther by means of mortices and tenons, with a fpring 
 which holds them faft. In each length is a joint, by 
 which the rack-work will accommodate itfelf to angles 
 or turns in the ilues. To the lirit or uppermofl length 
 
 is fixed a brufli of hair, or wire, or fpunge, or other China, 
 elaftic fubftance as the occafion may require. ' v "' 
 
 This invention is doubtlefs well calculated to anfwer 
 the purpofe intended, and may perhaps be the means of 
 diminifliing the number ot tliofe objedls of mifery, the 
 unfortunate chimney-fweepers. 
 
 CHINA is an empire of fuch antiquity and extent, 
 the laws and culloms of the people are fo fmgular, a-nd 
 the populoufnefs of the country fo very great — that it 
 has attracted much of the attention of Europeans ever 
 fince it was vifited in the 13th century by Marco Paulo 
 the Venetian traveller. Of fuch a country it would be 
 unpardonable not to give iome account in a work of 
 this nature ; but vv'e have not, in truth, much to add to 
 what has been faid of China and the Cisinefe in the 
 Encyclopsdia Britannica. Since the article China in 
 that work was publilhed, the court of Ptkin has indeed 
 been vifited by an embaffy from Great Britain, and the 
 origin of the people, as well as the antiquity of their 
 empire, has been invelligated by Sir William Jones 
 with his uiual diligence ; but from his memoir, pub- 
 lillied in the feoond volume of the Afiatic Refearches, 
 and from Sir George Staunton's account of the embaf- 
 fy, there is not much to be cxtrafted which would be 
 either amufing or inllruClive to our readers. 
 
 We have already obferved from Grofier and others, 
 that the Chinefe not only lay claim to the higheil an- 
 tiquity, but even contend that their firft emperor was 
 the firft man. Both thefe pofitions are controverted by 
 Sir William Jones, who, though he allows the Chinefe 
 empire to be very ancient when compared with the 
 oldeft European ftate, is yet decidedly of opinion that 
 it was not founded at an earlier period than the 12th 
 century before the Chrlftian era ; and that the people, 
 fo far from being aborigines, are a mixed race of Tar- 
 tars and Hindoos. He begins his inveftigaticn with aflc- Jft 
 mg, " Whence came the lingular people who long had ^ 
 governed China, before they were conquered by the 
 Tartars? On this problem (fays he*) four opinions* /^^//c^^ 
 have been advanced, and all rather peremptorily afferted/Jor./jw, 
 than fupported by argument and evidence. By a few *"'•"• 
 writers it has been urged, that the Chinefe are an origi-"*''™' ^' 
 nal race, who have dwelled for ages, if not from eterni- 
 ty, in the land which they now polfefs. By others, 
 and chiefly by the mlirionaries, it is infifted that they 
 iprung from the fame ftock with the Hebreivs and the 
 Arabs. A third affertion is that of the Arabs them- 
 felves, and of M. Pauw, who hold it indubitable, that 
 they were originally Tartan, defcending in wild clans 
 from the fteeps of Imau« : And a fourth, at leaft as 
 dogmatically pronounced as any of the preceding, is 
 that of the Brahmans, who decide, without allowing 
 any appeal from their decifion, that the Chinas (for 
 fo they are named in Sanfcril) were Hindoos of the 
 military caft, who, abandoning the privileges of their 
 tribe, rambled in different bodies to the north-eaft of 
 Bengal; and forgetting by degrees the rites and the re- 
 ligion of their anceftors, ellabllftied feparate principali- 
 ties, which were afterwards united in the plains and val- 
 leys which are now poflefled by them. 
 
 Of thefe opinions, Sir William having very complete- 
 ly demollflied the firft tliree, proceeds to eftabhlh the 
 fourth, which he confiders as interefting as well as nev» 
 in Europe. In the Sanfcrit inftitutes of civil and reli- 
 gious duties, revealed, as the Hindoos believe, by Menu 
 
 the
 
 C 11 I 
 
 [ 41 
 
 ChW.i. tlio fon of Bralima, we fin J (fays In) llic fullowiiig- cini- 
 
 — % ous patTage : ' Many families of tlie military clafs, having 
 
 gradually abandoned the ordinances of the Fiila, and the 
 company of Brahmans, lived in a ftate of degradation ; 
 as the people of Pundraca and Odra, tliofe of Dravira 
 and Ccvtibnja, the Tavanas and Sacas, the Paradus and 
 Piihhmas, the Chinas, and fome other nations.' A 
 full comment on this text (contiiiucis the prefident) 
 would be fuperfluous ; but fiiice the Icllimony of the 
 Indian author, who, though not a divine perfonage, 
 was certainly a very ancient lawyer, moralift, and hifto- 
 rian, is direct and pofitive, diilntercfttd and unfufpeft- 
 ed, it would decide the queilion before us if we could 
 be flire that the word China fignifies a Chhwfe." Of 
 this faft Sir William Jones took the very beft methods 
 to be fatisfied. He confultcd a number of Pandits le- 
 parately, who all alTured him that the word China has 
 no other fignification in Sanfcrit ; that the Chinas of 
 Menu fettled in a fine country to the north-eall of 
 Gaur, and to the eall of Camanip and Napai ; that they 
 had long been, and Hill are, famed as ingenious artiii- 
 cers ; and that they (the Pandits) had themfelves feen 
 old Chinefe idols, which bore a manifell relation to the 
 primitive religion of India. He then laid before one 
 of the beft informed Pandits a map of Afia ; and when 
 liis own country was pointed out to him, the Pandit 
 immediately placed his finger on the north-wellern pro- 
 vinces of China, as the place wliere lie faid the Chinas 
 of Menu firft eftabliihed themfelves. 
 
 In the opinion of Sir William Jones, this is complete 
 evidence that the Chinefe are defcended from an In- 
 dian race ; but he does not believe that the Chinefe em- 
 pire, as we now call it, was formed when the laws of 
 Menu were collefted ; and for his calling this fai5l in 
 queilion, he, offers reafons, which to us are perfectly fa- 
 tisfadlory. By a diligent and accurate comparifon of an- 
 cient Sanfcrit writings, he has been able to fix the period 
 of the compilation of thofe laws at between 1000 and 
 I ioo years before Chrill ; but by the evidence of Con- 
 fucius himfelf, he proves, that if the Cliinele empire was 
 formed, it could be only in its cradle in the 12th cen- 
 tury before our era. In the fccond part of the work, 
 intitled Ltin Tu, Confucius declares, that " although 
 lie, like other men, could relate, as mere leflTons of mo- 
 rality, the liiftories of the fnft and fecond imperial 
 houfes, yet, _/or loan! of evidence, he could give no cer- 
 tain account of them." Now, fays Sir William, if the 
 Chinefe themfelves do not pretend that any hillorical 
 monument exilled in the age of Confucius preceding 
 the rife of their third dynally, about 1 100 years before 
 the Chrillian epoch, we may juftly conclude that their 
 empire was then in its infancy, and did not grow to ■ 
 maturity till fome ages afterwards. Nay, he is inclined 
 to bring its origin (bll lower down. " It was not, fays 
 he, till the eighth century before the birth of our Sa- 
 viour, that a fmall kingdom was erefted in the province 
 of Shenji, the capital of which flood nearly in the 55tli 
 degree of northern latitude, and about five degrees to 
 the weft of Si-gan. That country and its metropolis 
 were both called Chin ; and the dominion of its princes 
 was gradually extended to the eaft and weft. The ter- 
 ritory of Chin, fo called by the old Hindoos, by the 
 Perfians, and by the Chinefe, gave its name to a race 
 ef emperors, whofe tyranny made their memory fo un- 
 popular, that the modern inhabitants of China hold the 
 SuppL. Vol. I. Part II. 
 
 7 ] CHI 
 
 word in al>horrence, and fpcak of themfelves as the China, 
 people of a milder and more virtuous dynaily : but it *~~ 
 is highly probable that the whole nation delcended from 
 the Chinas of Menu, and mixing with the Tartars, by 
 whom the plains of Honan and the more fouthcrn pro- 
 vinces were thinly inhabited, formed by degrees the 
 race of men whom we now Ice in poffeflion ol the no- 
 bleft empire in Alia." 
 
 In fupport of this opinion, which the accomphflied 
 author offers as the refult of long and anxious Inqui- 
 ries, he obferves, that the Chinefe have no ancient mo- 
 numents from which their origin can be traced, even 
 by plaufible conjcdlure ; that their fciences are wholly 
 exotic ; that their mechanic arts have notlung in them 
 which any fet of men, in a country fo highly favoured 
 by nature, iiiiglit not have difcovercd and improved; 
 that tlieir philofopliy feems yet in io rude a ftate as 
 hardly to deferve the ai)pellation ; and that their popu- 
 lar religion was imported from India in an age compa- 
 ratively modern. He then inftitutes 3 comparifon be- 
 tween the mythology of the Chinefe and that of the 
 Hindoos ; of which the refult is, that the former people 
 had an ancient fyftem of ceremonies and fuperftilion3 
 which has an apparent affinity with fome parts of the 
 oldeft Indian worfiiip. " They believed in the agency 
 of genii or tutelary iplrlts, pre fiding over the ftars and 
 the clouds ; over lakes and rivers, mountains, valleys, 
 and woods ; over certain regions and towns ; over all 
 the elements, of whicli, li-je the Hindoos, they reckon- 
 ed five ; and particularly over Jire, the n-.oft bi ill:, nit of 
 them. To thofe deiiies they offered viilims on high 
 places. And the follo.ving pafTage from one of their 
 iacred books, inys Sir Wllh'am, is very much in the 
 ftyle of the Brahmans : ' Even they who perform a 
 facrifice with due reverence, cannot perfeftly affure 
 themfelves that the divine fpirits accept their oblations; 
 and far lefs can they, who sdore the gods with languor 
 and ofcltancy, clearly perceive their facred illapfes.' 
 Thefe (continues the Prefident) are iiiiperleft traces 
 indeed, but they are traces of an affinity between the 
 religion of Menu and that of the Chinas, whom he 
 names among the apoftates from it ; and bcfides them, 
 we dilcover many other very lingular marks of relation 
 between the Ciiinefe and the old Hindoos. 
 
 " This relation (he thinks) appears in the remark- 
 able period of .(32,000, and the cycle of 60 years; in 
 the predilection tor the myftical numbei nine; in many 
 fimilar falls and great feftivals, efpecially at the i'olilices 
 and equinoxes ; in the obfcquies, coufifting of rice and 
 fruiis offered to the manes of their anccltors ; in the 
 dread of dying chlldlefs, left fuch offerings fhould be 
 intermitted ; and perhaps in their common abhorrence 
 of rc^ objetls, which the Indians carried fo far, that 
 Menu himfelf, where he allows a Brahman to trade, 
 if he cannot otherwife fupport life, abiolnti;ly forbids his 
 trading in any fort of red cloths, whether linen, or 
 woollen, or made of woven bark. In a word, lays Sir 
 William Jones, all the circuinflanccs which have been 
 mentioned feem to prove (as far as fuJi i qiiefUui; ad- 
 mits proof), that the Chinefe and Hindoos were origi- 
 nally the fame people ; but having been feparated near 
 4000 years, they have retained few ftrong features of 
 their ancient confanguity, efpecially as the Hindoos 
 have preferved their old language and ritual, whih- the 
 Chinefe very foon loft both ; and the Hindoos have 
 3 G conftantly
 
 China. 
 
 CHI [41 
 
 conftamly intermarried among themfelves, wliile the 
 Chinefe, by a mixture of Tartarian blood from tlie time 
 of their firft ellablifhment, have at length formed a race 
 diHiiiCl in appearance both from Indians and Tartars." 
 Sir George fStaunton, who accompanied the Earl of 
 Macartney on his embafiy to the ILmperor of China, 
 does not indeed dircttly controvert this rcafoning ; but 
 overlooking it altogether, gives to the Chinefe a much 
 higher antiquity than Sir William Jones is inclined to 
 allow them. Taking it for granted that tlieir cycle is 
 t.lieir own, and that it is not the offspring of allronomi- 
 cal fcience, but of repeated obfcrvations, he feems to 
 ^ive implicit credit to thofe annals of the empire which 
 almoU every other writer has confidcred as fabulous. 
 
 "Next to the lludies which teach the economy of 
 life, the Chinefe (fays lie) value moll the hillory o( the 
 events of their own ccnmtry, which is, to them, the 
 globe; and of the celeftial movements which they had 
 an opportunity of obfcrving at the fame time." In re- 
 gard to the former, he tells us, that "from about three 
 centuries before the Chriftian era the tranfaflions of the 
 Chinefe empire have been regularly, and without any 
 intervening chafm, recorded both in official documents 
 and by private contemporary writers. Nowhere had 
 hiftory become fo much an objeA of public attention, 
 and nowhere more the occupation of learned individuals. 
 Every confiderable town throughout the empire was a 
 kind of unjveriity, in which degrees were conferred on 
 the proficient in the hillory and government of the ilate. 
 Hiftorical works were multiplied throughout. The 
 accounts of recent events were cxpofed to the correftion 
 of the witneffes of the fafts, and compilations of former 
 tranfaftions to the criticifms of rival writers." In re- 
 gard to the latter, the movements of the heavenly bo- 
 dies, he thinks that in no country are there llrongcrin- 
 ducements or better opportunities to watch them than 
 in China ; and hence he infers, that the cycle of fixty 
 years is of Chinefe formation. " In a climate (fays he) 
 favourable to aftronomy, the balance of hours beyond 
 the number of days during which the lun appeared to 
 return oppofite to, and to obicure, or to mix among the 
 fame fixed ftai's, might be afcertained in a fhort time-; 
 and occafioned the addition of a day to every fourth 
 year, in order to maintain regularity in the computation 
 of time, in regard to the return of the feafons ; but ma- 
 ny ages mull have pad before a period could h.ive been 
 difcovered, in which the unequal returns of the fun and 
 moon were fo accurately adjuiled, that at its termina- 
 tion the new and full moons (hould return, not only to 
 the fame day, but within an hour and a half of the time 
 they had happened, when the period commenced. The 
 knowledge of fuch a period or cycle could be obtained 
 only by a multiplicity of careful and accuiate obfcrva- 
 tlons. Many revolutions of thofe great luULinavies mull 
 have been completed, and numberlefs conjunftions have 
 pad over, before their returns could be afcertained to 
 happen in the fame day, at the end of nineteen years. 
 The fmall diiference of time between the returning pe- 
 riods of this cycle, was partly Itflened by the interven- 
 tion of another of 60 years, or of 720 revolutions of the 
 moon, which, with the fettled intercalation of 22 luna- 
 tions, were at lull fuppofed to bring a perleft coinci- 
 dence of the relative pofitions of the fun and moon : 
 but even according to this period, every new year was 
 made conftantly to recede, in a very fmall degree, which 
 
 8 ] CHI 
 
 the Chinefe corrcfled afterwards from time to time, ( 
 This cycle anfwercd a double purpofe, one as an era for '"" 
 chronological reckoning, and the other as a regulating 
 period for a luni-folar year. Each year of the cycle is 
 dillinguiihed by the union of two charadters, taken from 
 (uch an arrangement of an unequal number of words 
 placed in oppofite columns, that the fame two charac- 
 ters cannot be found again together for fixty years. 
 The firll column contains a feries often words, tiie other 
 twelve ; which lull are, in faft, the fame that denote the 
 twelve hours or divilions of the day, each being double 
 the European hour. The firft word or chnratltr of 
 the firll feries or column of ten words, joined to the 
 firll word of the fecond feries or column of twelve, 
 marks the firft year of the cycle ; and fo on until the 
 firll feries is exhaufted, when the eleventh word of 
 the fecond feries, combined with the firft of the firft fe- 
 ries, marks the eleventh year of the cycle ; and the 
 twelfth or laft of the fecond ieries, joined with the fe- 
 cond of the firft ieries, ferves for denoting the twelfth 
 year. The third of the firft feries becomes united in 
 regular progrefllon with the firft of the fecond feries, to 
 mark the thirteenth year ; and proceeding by this rule, 
 the firft charadler in the firft and in the fecond feries can- 
 not come again together for fixty years, or until the 
 firft year of the fecond cycle. The Chriftian year 
 1797 anfwers to the 54th year of the 60th Chinefe cy- 
 cle, which afcertains its commencement to have been 
 2277 years before the birth of Chrift ; unlefs it be fup- 
 pofed that the official records and public annals of the - 
 empire, which bear teftimony to it, fhould all be falfi- 
 fied, and that the cycle when firft ellablifhed (hould 
 have been aiitidated ; which is indeed as little probable 
 as that the period, lor example, of the Olympiads Ihould 
 be afl'erled to have commenced many ages prior to the 
 firft Olympic games." 
 
 This is a very pofitive decifion againft the opinion of 
 a man whole talenti and knowledge of oriental learning 
 were fuch as to give to his opinions on fuch iubjefts 
 the greatcll weight. If the ilatements and reafoiiings 
 of Sir George Staunton be accurate, the Chinele em- 
 pire mnft have fubtifted at leaft 3000 years before the 
 Chriftian era ; for he fays exprefsly, that many ages 
 muft have elajiied before the commencement ot that 
 cycle, which, according to him, commenced 2277 years 
 before the birth of Chrift. But furely Confucius was 
 as well acquainted with the ancient annals of his own 
 country, and the credibility which is due to them, as 
 any man of the prefent age, whether Chinefe or Euro- 
 pean ; and we have fecn, that he coiifidered none of 
 them as authentic which relate events previous to the 
 I ith century before our era. Even this is by much too 
 early a period at which to rely upon them with impli- 
 cit confidence, if it be true, as Sir Geoi-ge informs us,. 
 that the tranfadtioas of the empire have been regularly 
 recorded only from about three centuries before the birth 
 of Chrift. With refpedl to the cycle, there is every 
 probability that it was derived from India, where we 
 know that aftronomy has been cultivated as a icience 
 from time immemorial, and where, we have fhewn in 
 another place, that the commencement of the cycle was 
 atlually antedated (fee Philosophy, n'' g.Encycl.) We 
 have therefore no hefitation in preferring Sir William 
 Jones's opinion of the origin of the Chinefe empire to 
 Sir George Staunton's; not merely becaufe we believe 
 
 the 
 
 hi'n.
 
 C H I 
 
 [ 41 
 
 Chin*, the former of thefe gentlemen to have been more con- 
 
 — ^' verfaiit than the latter -.vith Chinei't htcrature, but be- 
 
 caufe we think liis reai'oning more i.onlillcnt with itltlt, 
 and his concluiion move confoiidnt to that oiithne of 
 chronology, which, as he obfervcs, has been fo correctly 
 traced for the lall 20CO years, lliat we iniill be hardy 
 fcipties to call it in qiieflion. 
 
 There is another point very nearly related indeed 
 to this, about whicli thcfe two learned men likcvvile 
 dilfer. Sir George Staunton informs us, that " no ac- 
 counts of a general deluge are mentioned in Chinefe hil- 
 tory." Sir William Jones, on the other hand, in the 
 difcourfe already quoted, fays, " I may afTure you, af- 
 ter full inquiry and confideration, that tlie Chinefe, like 
 the Hindoos, believe this earth to have been wholly co- 
 vered with water, wliieli, in works of undilputed au- 
 thenticify, they deferibe -asjlwiviii^^ uLunclniiily, thenfuL- 
 JiJing, and fcparaliiig liie higher fimn ihc Id'wer ogc y 
 mankind." To which of thefe iiiitiiors (hall we give 
 credit ? The high antiquity which bir George Siaun- 
 ton afTigiis to the Chinefe empire, rendered it neceilary 
 for the perfons from whom he drew his information to 
 get quit by any means of an univerlal deluge. The 
 fyftem of Sir William Jones left him at liberty to admit 
 or rejett that event according to evidence ; and in ad- 
 dition to the authentic records to whicii he appeals, he 
 quotes a mythological fable of the Chinefe, and another 
 of the Hindoos, which, though he lays not upon them 
 any great ftrefs, appear to us, when compared together, 
 not only to corroborate his opinion refpecung the de- 
 fcent of the Chinefe, but likewlfc to fiiew that both 
 they and the Hiirdoos have prelerved a traditionary ac- 
 count of the deluge very limilar to that which is given 
 by Mofes. The Chinefe table is this : " The mother 
 of FoHi was the daitghier of Hcwom, lurnanied i^/oizyfr- 
 ioving ; and as the nympli was walking alone on the 
 briirk of a river w/th a fimilar name, (Ire found herfe'if 
 on a fudden encircled with a rainbow ; loorr aitcr which 
 (he became pregnant, and at the end oi twelve years 
 was delivered of a fon, radiant as herfcif, who, among 
 other titles, had that of Sui, or the Star 0/ ibe Tear." 
 In the mythological fyftem of the Hindoos, " the nymph 
 RoHiNi, who prefides over the fourth lunar manlion, 
 was the favour-ite miftrefs of Soma, or the Moon, among 
 whofe numerous epithets we ilnd CumuJanayaca, or de- 
 lighting in a fpecies of 'water-Jlotuer that blolfoms at 
 night. The ollspriug of RonrNi and Soma was Bud- 
 HA, r-egent of a planet ; and he married Ila, whofe fa- 
 ther was prefcrvcd in a miraculous ark from an uni- 
 verfal deluge." The learned prefideiit (hews, that, ac- 
 cording to the Brahams, the Chineie defceadcd Irom 
 BuDA ; and he mentions a divine perfonage connefted 
 with the Chinefe account of the birth of Fo-Hi, whole 
 name was Kiu-vA. But if all thefe circumllances be 
 laid together, it will appear, we think, pretty evident, 
 that the two ancient natrons have prefcrved the fame 
 tradition of an univerfal deluge, and that the Chinefe 
 RAINBOW and Niu-vA, with the Indian ark, point to 
 the flood of Noah. 
 
 To Sir William Jones's derivation of the Chinefe 
 from the Hindoos, the ftate of their written language 
 may occur as an objeftion ; for iince it is certain that 
 alphabetical charafters were in ufe among the Hindoos 
 before the per-iod at which he places the emigration of 
 the Chinas, how, it may be aflced, came thefe people to 
 
 ] € H I 
 
 drop the mode of writing pradlifed by their anccftors, Clii.is. 
 and to adopt another fovery inconvenient as that which * 
 
 the Chinefe have ufcd from the foundation of their cui- 
 pire ? Tire torce of this oLjcdtion, however, will vanilli, 
 when it is remembered tliat the Chimis were of the mi- 
 litary call ; that they had gradually abandoned the 01- 
 diiidiices of the VeJa, and were in conlequtnee degia- 
 ded ; aud that they laiiibkd from their irutive country 
 in imall bodies. We do not know that the military cail 
 among the Hindoos was ever niuch devoted to letters ; 
 there is the greatcrl reafon to believe that a degi'ade-«l 
 call would negleft them ; and it is certain that Inrali 
 bodies of men, wandering in defeits, would have tlitir 
 time and their attention comj^letely occupied in provi- 
 ding for the day that was paffing over them. That the 
 Chinas (liould have foi'gotten the alphabetical charac- 
 ters of the Hindoos, is therefoi'e fo far irom being an 
 ohjeiStion to Sir William Jones's accoui.t of their de- 
 feerit from that people, that it is the natural coiiftqiiencc 
 of tire manner in which he fays they rambled from Hiil- 
 doltan to the northern provinces of what now confti- 
 tutes the Chinefe empii'C. 
 
 Of the origin of the charafters which are ufed by 
 this Ihigular people, the iiluftrious prefrdent of the Ah- 
 atic Society gives the following account from a Chinefe 
 writer named Li Yang Ping. " The earlleft of them 
 were nothing more than tlia outlines of vifrble objects, 
 earthly and celellial ; but as things merely iiitelledtual 
 could not be cxprelftd by thofe (igures, the gramma- 
 rians of China contrived to reprefent the various opci'a- 
 tions of the mirid by metaphors drawn from the pi'o- 
 duftions of natu^'e. 'I'lius the idea of rouglrnefs and of 
 rotundity, of motion and reft, were conveyed to the eye 
 by iigns repreieiiling a mountain, the (Ivy, a I'iver, and 
 the earth. The (igures oi the fun, the ir.oori, ard (he 
 liars, differently combined, ilood for fmoothnefs and 
 fpleiidour, for any tiling artfully wrought, or v/oven 
 with delicate woiknianfiup. E.\tenrion, growth, in- 
 cr"eale, and many other qualities, werx" painted in cha- 
 -radters taken from the clouds, from the iirmamcnt, and 
 from the vegetable part of the creation. The diflerent 
 ways of moving, agility and (lownefs, idienefs and di- 
 ligence, were expreflcd by various iiifetls, birds, iiflies, 
 and quadrupeds. In this manner palTions and fentiments 
 were traced by the pencil, and ideas not fubjcft to any 
 fciife were exhibited to the light ; until by degrees new 
 combinations were invented, new exprclTrons added, 
 the characters deviated imperceptibly from their primi- 
 tive fhape, and the Chinefe language became not only 
 clear and forcible, but rich and elegant in the higheil 
 degree*." ^ _ * ^f.^tlc 
 
 Of this language, both as it is fpoken and 'wntitn, Rpf ear cbes. 
 Sir George Staunton has given an account fo clear and vol ii. Me- 
 fcientific, that it will undoubtedly' place him high among""''' '3- 
 the moll eminent philologifts of the iStli century. As 
 there is nothing relating to the Chinefe more wonder- 
 ful than their language, which is very little iMidcrdood 
 in Europe, we (hall lay before our readers a pretty co- 
 pious abftradl of what he fays on the fubjeft, referring 
 them for further information to his account of Lord 
 Macartney's Embaffy to China. 
 
 " In the Chinefe tongue (fays Sir George) the 
 
 founds of feveral letters in moll alphabets are utterly 
 
 unknown, and the organs of a native advanced in life 
 
 cannot pronounce them. In endeavouring to utter the 
 
 3 G 2 founds
 
 CHI [ 420 ] . ^. ^ ^ 
 
 China, founds of B, D, R, and X, for inftance, he fiiblUtutes has arifcn, according to him, from the finguhr habits 
 
 < ' 'fome other founds to which the fame organ has been of the people; for though their common tongue be fij 
 
 accuftomed ; L for R, and, as we liavc reafon to think nw/ically accented as to form a kind of recitative, yet it 
 
 from fome cxprefTions of Sir Wilh'am Jones's, F for B. wants thofe grammatical accents without which all hu- 
 
 The nice diftindions between the tones and accents of man tongues would appear monofyllabic. Thus Aniila, 
 
 words nearly refembling each other in foiind, but vary- with an accent on the firft fyllable, means, in the San 
 
 China. 
 
 ing much in fenfe, require a nicety of ear to diihnguilh, 
 and of vocal powers to render them exaftly. Synony- 
 mous words are therefore frequently introduced in Chi- 
 nefe dialogue to prevent any doubt about the intended 
 fenfe ; and if in an intricate difcuffion any uncertainty 
 ftioiild ftill remain as to the meaning of a particular ex- 
 preffion, recourfe is had to the ultimate criterion of tra- 
 cing with the finger in the air, or otherwlfe, the form 
 of the charadter, and thus afcertaining at once which 
 was meant to be exprefied. In a Chinefe fentence 
 there is no marked diftinftion of fubftantives, adjeftives, 
 or verbs ; nor any accordance of gender, number, and 
 cafe. A very few particles denote the paft, the pre- 
 fent, and the future ; nor are thofe auxiliaries employ- 
 
 fcrit language, immeafurable, and the natives of Bengal 
 pronounce it Omito ; but when the religion of Buddha, 
 the fon of Maya, was carried into China, the people of 
 that country, unable to pronounce the name of their 
 new god, called him Foe, the fon of Mo-ye. ; and di- 
 vided his epithet Am'ita into three fyllables Om ITO, 
 annexing to them certain ideas of their own, and ex- 
 prefling them in writing by three diftin£l fynibols. 
 Hence it is that they have clipped their language into 
 monofyllables, even when the ideas expred'ed by there, 
 and the written fymbols for thofe ideas, are very com- 
 plex." 
 
 " In the Chinefe language Sir George Staunton in- 
 forms us, .that there is a certain order, or fettled lyntax. 
 
 ed when the intended time may be otherwife inferred in the fucceffion of words in the fame fentence ; a fuc 
 
 ceffion fixed by cullom, differently in different langua- 
 ges, but founded on no rule or natural order of ideas, as 
 has been fometimes fiippofed ; for though a fentence 
 confills of feveral ideas, to be rendered by feveral words, 
 thefe ideas all exift and are conneded together in the 
 fame inilant ; forming a pidure or image, every part of 
 which is conceived at once. The formation of Chinefe 
 fcntences is often the fimpleft and moft artlefs poflible, 
 and fuch as may naturally have occurred at the origin of 
 fociety. To interrogate, for example, is often at lead 
 A finffle fyllable always expreffes a complete idea. Each to require the folution of a queftion, whether the fub- 
 fyllable may be founded by an European confonant pre- jeft of doubt be in a particular way or the contrary ; 
 ceding a vowel, fometimes followed by a liquid. Such and accordingly a Chuiefe mquirmg about his friends 
 order of words prevents tlie harOmefs of fucceeding health, will fometimes fay, hou, poo hou ? The literal 
 fonants founding ill together ; and renders the Ian- meaning of which words is, " well, not well ?" A fimple 
 as foft and harmonious as the Italian is felt to chavadfr repeated ftands fometimes for more than one 
 
 with certainty. A Chinefe who means to declare his 
 intention of departing to-morrow, never fays that he 
 ■will depart to-morrow ; becaufe the expreifion of the 
 morrow is fufficient to afcertain that his departure mull 
 be future. The plural number is marked by the addi- 
 tion of a word, without which the fingular always is im- 
 plied. Neither the memory nor the organs of fpeech 
 are hurthened with the pronunciation of more founds 
 to exprefs ideas than are abfolutely neceffary to mark 
 their difference. The language is entirely monofyllabic. 
 
 an 
 
 con 
 
 guage „- — 
 
 be, from the rarity of confonants 
 
 (id the frequency of 
 
 its vowel terminations. 
 
 " The names or founds, by which men may be firlt 
 fuppofed to have diih'nguifhed other animals, when oc- 
 cafion offered to defignate them in their abfcnce, were 
 attempts at an imitation of the founds peculiar to thofe 
 beings ; and ftill, in Chinefe, the name, for example, of 
 a cat', is a pretty near refcmblance of its ufual cry. _ It 
 occurred as naturally to endeavour, in fpeaking, to imi- 
 tate the voice, if prafticable, as it was in writing to 
 fketch a rude figure of the objiit of defcription. It is 
 obfervable, that the radical words of moft languages, 
 feparated from the fervile letters which mark their in- 
 fleftions, according to their conjugations or declenfions, 
 are monofyllabic. A part of each radical word is re- 
 tained in compofitlon to denote the meaning and etymo- 
 logy of the compound, which thus becomes poly fy lia- 
 ble ; but the Chinefe grammarians, aware of the iucon- 
 veni'ence refulting from the length and complication of 
 founds, confined all their words, however fignificant of 
 combined ideas, to fingle founds ; and retained only in 
 writing, fome part at leaft of the form of each charac- 
 ter denoting a fimple idea, in the compound charafters 
 conveying complex ideas." 
 
 This is a very plaufible, and perhaps the true, ac- 
 count of the monofyllabic form of the Chinefe language ; 
 but it is proper to ftate the different account which is 
 given of this peculiarity by Sir William Jones. " It 
 
 of the objeds which fingly it denotes, and fometimes 
 for a coUcdive quantity of the fame thing. The cha- 
 rader of moo fingly is a tree, repeated is a thicket, and 
 tripled is a foreft. 
 
 " In Chinefe there are fcarcely fifteen hundred dif- 
 tind founds. In the written language there are at 
 leaft eighty thoufand charaders or different forms of 
 letters, which number divided by the firft gives neai-Iy 
 fifty fenfes or charaders upon an average to every found 
 expreffed ; a difproportion, however, that gives more 
 the appearance than the reality of equivocation and un- 
 certainty to the oral language of the Chinefe. 
 
 " The charaders of the Chinefe language were ori- 
 ginally traced, in moft inftances, with a view to exprefs 
 either real images, or the allegorical figns of ideas : a 
 circle, for example, for the fun, and a crefcent for the 
 moon. A man was reprefentcd by an ered figure, with 
 lines to mark the extremities. It was evident that the 
 difficulty and tcdioufnefs of imitation will have occa- 
 fioned foon a change to traits more fimple and more 
 quickly traced. Of the entire figure of a man, little 
 more than the lower extremities only continue to be 
 drawn, by two lines forming an angle with each other. 
 A faint refemblance, in fome few inftances, ftill remains 
 of the original forms in the prefent hieroglyphic charac- 
 ters ; and the gradation of their changes is traced in 
 feveral Chinefe books. Not above half a dozen of the 
 prefent charaders conSft each of a fingle line ; but moil 
 
 of
 
 C H I 
 
 [ 42^ T 
 
 C H I 
 
 China, of them coiifift of many, and a ftw of fo many as feventy 
 ""■V~~" different ftvokes. The form of tliofe charai'iers has not 
 been fo flux as the found of words, as appears in the in- 
 llante of alnioft all the countries bordering on the Chi- 
 iiefe Sea or Eaftern Afia, where the Chinefe written, 
 but not the oral language, is underftood; in like man- 
 ner, as one form of Arabic figures to denote numbers, 
 and one fct of notes for mufic, are uniform and intel- 
 ligible throughout Europe, notwithftanding the variety 
 ot its hmguages. - 
 
 " A certain order cr connection is to be perceived in 
 the arrangtinent of the written characters of the Chi- 
 nefe ; as if it had been formed originally upon a fyttem 
 to take place at once, a. id not grown up, as other lan- 
 guages, by flow and diilant intervals. Upwards of two 
 hundred charafters, generally conlilling each of a few 
 lines or ftrokes, are made to mark the principal objefts 
 of nature, foniewhat in the manner of Bidiop Wilkin's 
 divifions, in- his ingenious book on the fubjc6l of uni- 
 verfal language, or real charafter. Thefe may be con- 
 fidered as the genera or roots of language, in which 
 every other word or fpecies, in a fyilematic fenfe, is re- 
 ferred to its proper genus. The heart is a genus, of 
 which the reprefentalion of a oirve line approaches 
 fomevvhat to the form of the objeft ; and the fpecies 
 referable to it include all the fentinients, paffions, and 
 affedions, that agitate the human bread. Each fpecies 
 is accompanied by fome mark denoting the genus or 
 heart. Under the genus hand are arranged moll trades 
 and manual exercifes. Under the genus wortl every 
 fort of fpeech, ftudy, writing, underftanding, and de- 
 bate. A horizontal line marks a unit; eroded by an- 
 other line it Hands for ten, as it does in every nation 
 which repeats the units after that number. The five 
 elements, of which the Chinefe fuppofe all bodies in 
 nature to be compounded, form fo many genera, each 
 of which comprehends a great number of fpecies under 
 it. As in every compound character or fpecies, the 
 abridged mark of the genus is difcernible by a ftudent 
 of that language, in a little time he is enabled to con- 
 fult the Chinefe diftionary, in which the compound cha- 
 radlers or fpecies are arranged under their proper gene- 
 ra. The charafters of thefe genera are placed at the 
 beginning of the diiilionary, in an order which, like 
 that of the alphabet, is invariable, and foon becomes fa- 
 miliar to the learner. The fpecies under each genus 
 follow each other, according to the number of ilrokes 
 of which each confills, independently of the one or few 
 which ferve to point out tlie genus. Tlie fpecies want- 
 ed is thus foon found out. Its meaning and pronuncia- 
 tion are given through other words in common ufe; the 
 firll of which denotes its fignifioation and the other its 
 found. When no one common word is found to render 
 exaftly the fame found, it is commiuiicated by two 
 words with marks, to inform the inquirer that the con. 
 fonant of the ftrft word and the vowel of the fccond join- 
 ed together form the precife found wanted. 
 
 " The compofition of many of the Chinefe charac- 
 ters often difplays confiderable ingenuity, and ferves al- 
 io to give an infight into the opinions and manners of 
 the people. The charafler expreflive of happinefs in- 
 cludes abridged marks of land, the fource of their phy- 
 fical, and of children that of their moral, enjoyments. 
 This charafter, embellifhed in a variety of ways, is hung 
 up almoft in every houfe. Sometimes written by the 
 
 hand of the emperor, it is feiit by him is a compliment, Ch ina, 
 which is very highly prized, and luch as he w.is plealed • 
 to fend to tiie cmbaflador. 
 
 " Upon tlie formation, changes, and allufions of 
 compound charafters, the Chinefe have publifticd many 
 thoufand volumes of philulugical learning. Nowhere 
 does criticifm more abound, or is more Itrift. The in- 
 troduftion or alteration of a character is a ferious un- 
 dertaking, and feldom fails to meet with oppofition. 
 The mod ancient writings of the Chinefe are ftill clafli- 
 cal amongd them. '1 he language feenis in no inftance 
 to have been derived from or mixed with any other. 
 The written feenis to have followed the oral language 
 foon after the men who fpoke it were formed into a re- 
 gular focicty. I'hongh it is likely thiit all hieroglyphi- 
 cal languages were originally founded on the principles 
 of imitation, yet in the gradual progrefs towards arbi- 
 trary forms and louiids, it is prob;;ble that every fociety 
 deviated from the originals in a different n-ianner from 
 the others ; and thus for every independent fociety 
 there arofe a feparate hieroglyphic language. As foon 
 as a communication took place between any two of 
 them, each would hear names and founds not common 
 to both ; each reciprocally would mark down fucli 
 names in the founds of its own chara<5lcrs, bearing, 33 
 hieroglyphics, a different fenfe. In that inftance, con- 
 fequently, thofe charafters ceafe to be hieroglyphics, 
 and were merely marks of found. If the foreign lounds 
 could not be expreflcd but by the ufe of a part of two 
 hieroglyphics, in the manner mentioned to be ufed fome- 
 times in Chinefe dictionaries, the two marks joined to- 
 gether become in facl a f) liable. If a frequent inter- 
 courfe ffiould take place between communities fpeaking 
 different languages, the neccffity of ufiiig hieroglyphics 
 merely as marks of found would frequently recur. Tli^i 
 practice would lead imperceptibly to the difcovery that, 
 with a few hicrogl)phics, every found of the foreign 
 language might be exprcffed ; and the hicrdglyphics 
 which anfweied bell this purpolc, either as to exaAnefs 
 of found or fmiplicity of form, would be fclefted for 
 this particular ufe; and lerving as fo many letters, would 
 form ill fafl together what is called an alphabet. TKus, 
 the paflage from hieroglyphic to alphabeiic writing may 
 naturally be traced, without the neceffity of having 
 ' recourfe to divine iiidruClion, as fome learned men 
 have conjeAured, on the ground that the art of writing 
 by an alphabet is too refined and artificial for untutored 
 reafon.' 
 
 " The Chinefe printed charaflcr"is the fame as is 
 ufed in moft manufcripts, and is chicfiy formed of 
 llraight lines in angular politions, as moft letters are in 
 Eaftern tongues, elpecially the Sanfcrit; the charafters 
 of which, in fome inllauccs, admit of additions to their 
 original iorm, producing a modification of the fenfe. 
 A running hand is ufed by the Chinefe only on trivial 
 occafions, or for private notes, or for the eafe and ex- 
 pedition of the writer ; and differs from the other as 
 much as an European manufcript does from print. 
 There are books^ with alternate columns of both kinds 
 of writing for their mutual explanation to a learner. 
 
 " The principal difficulty in the ftudy of Chinefe wri- 
 tings arifes from the general exclufion of the auxiliary 
 particles of colloquial language, that fix the relation be* 
 tween indeclinable words, fuch as are all thofe of the 
 Chinefe language. The judgment mull be conftantly 
 
 exercifed.
 
 C H I 
 
 [ 422 ] 
 
 C H I 
 
 China, exercifed by the ftudent, to fupply the abfence of fuch 
 "~~v affiftaiice. That judgment muft be guided by attention 
 to the manncns, culloms, laws, and opinions of tlie Clil- 
 nefe, and to the events and local circumftances of the 
 country, to which the allufions of language perpetually 
 refer. If it in general be true, that a language is difli- 
 cult to be underllood in proportion to the diftance of 
 the country where it is fpokcii, and that of him who 
 endeavours to acquire it, becaufe in that proportion 
 the -dUufions to which language has continually recourfe 
 are lefs known to the learner, lome idea may be concei- 
 ved of the obftacles which an European may expeft to 
 meet in reading Chinefe, not only from the remotcnefs 
 of fituation, but from the difference between him and 
 the native of China in all other refpefts. The Chinefe 
 charadters are in fa£l flictches or abridged figures, and 
 a fentence is often a ftring of metaphors. The diffe- 
 rent rehitlons of life are not marked by arbitrary founds, 
 fimply conveying the idea of fuch connedtion ; but the 
 -qualities naturally expefted to arife wit of fuch relations 
 become frequently the name by which they are refpeclive- 
 ly known. Kindred, for example, of every degree is thus 
 dillinguilhed with a minutenefsuii known in ether langua- 
 ges That of China has diflinft charafters for every modi- 
 fication known by them of objefts in the phyfical and in- 
 telleftual world. Abflracl terms are no otherwife exprcf- 
 fed by the Chinefe than by applying to each the name of 
 the moil prominent objefts to which it might be applied, 
 wlu'ch is likewife indeed generally the cafe of other lan- 
 guages. Among the Latins the abflratl idea of viitue, 
 for example, was exprcffed under the name of valour or 
 flrength (^villus), being the quality moft elleemed a- 
 mong them, as filial piety is confidered to be in China. 
 Ths words of an alphabetic language being formed of 
 different coinbinations of letters or elemental parts, each 
 with a diflinft found and name, whoever knows and 
 combines thtfe together, may read the words without 
 the leall knowledge of their meaning ; not lo hierogly- 
 phic lai'.guagc, in which each charafler has indeed a 
 found annexed to it, but which bears no certain relation 
 to the unnamed lines or llrokes of which it is compo- 
 fed. Such chara&er is fludied and beil learned by be- 
 coming acquainted with the idea attached to it ; and a 
 diftionary of hieroglyphics is lefs a vocabulary of the 
 terms of one language with the correfpondent terms in 
 another, than an encyelupxdia containing explanations 
 of the ideas themfelves reprefented by fuch hierogly- 
 phics. In fuch fenfe only can the acquifition of Chi- 
 nefe words be juffly faid to engrofs moll of the time of 
 men of learning among them. Tlie knowledge of the 
 fciences of the Chinefe, however imperfect, and of their 
 mod extenllve literature, is certainly fufficient to oc- 
 cupy the life of man. Enough, however, of the lan- 
 guage is imperceptibly acquireii by every native, and 
 may, with diligence, be acquired by fortigr.ers for the 
 ordinary concerns of life ; and further improvements 
 mufl depend on capacity and opportunity." 
 
 Next to ih^ lingular ItriiAure of the oral and writ- 
 ten language of the Chinefe, there is perhaps nothing 
 in their hiftory more furprifing to a native of Europe 
 than the number of the people, and the means by which 
 they contrive to procure fubfiflence, without foreign 
 trade, in a country lo crouded, and at the fame time 
 not everywhere of a fertile foil. In the Encyclopsedia, 
 the population of this vail empire is ftated, from M. 
 
 Grofier, at 200 millions: but great as this la, when com- China, 
 pared with the population of every other extenfive coun- *— nr~- 
 try, it appears to be far fliort of the truth. Sir George 
 Staunton has publiflred a ftateincnt, taken from one of 
 the public offices in the capital, nnd given by a great 
 and reipcftablc manderin to Lord Macartney, in which 
 it is (hewn that China Proper contains not fewer than 
 3^3 millions of inhabitants. As the extent of the coun- 
 try is 1,297,999 fquare miles, there are of cnuric very 
 near 260 inhabitants to every fqi;;;re mile; and of tliefe 
 miles a very confiderable proportion confifts of nothing 
 but barren rocks. Tiiat this account is accurate there 
 can be little dotibt ; for the extent of the pro\inces was 
 afcertained by aflruuomical obfervations, as well as by 
 admeafurement ; and the number of individuals is regu- 
 larly taken in each divifion of a diftrift by a tything- 
 man, or every tenth mailer of a family. Thefe returns 
 are colledted by c.flictrs rcfident fo near as to be capable 
 of corrcdling any grofs millake, and are all lodged In 
 the great regifter of Pckin. 
 
 For this excefiive population cur author fatisfaftorily 
 accounts. Celibacy, fays he, is rare in China, even in 
 the military profeffion ; the marriages are prolific as 
 well as early, and the influence of tiie patriarclial fy- 
 ilesii, to be explained afterwards, is fuch, that a man's 
 children adds to his wealth. It is reckoned a difcredit 
 to be without offspring; and they who have none adopt 
 others, who become theirs excluflvely. In cafe of mar- 
 riage, fhould a wife prove barren, a fecond may be ef- 
 poulcd in the lifetime of the full. The opulent, as in 
 mofl pans of tl-.e Eaft, are allowed, without reproach, 
 to keep concubines, of v.'hom the children are confider- 
 ed as being thofe of the legitimate wife, and partake in 
 all the rights of legitimacy. " Accidents fometimes of 
 e.-itiaordiaary drought, and fometimes of excelTive in- 
 undations, occafionally produce famine in particular 
 provinces, and fainine diieafe ; but there are few drains 
 from moral caufcs either of emigration or foreign navi- 
 gation. The number of manufactures, whofc occupa- 
 tionf are not always favourable to health, whole con- 
 flant confinement to particular fpots, and fometimes in 
 a clofe or tainted atmofphere, mufl be injurious, and 
 whofe refidence in towns expofcs them to irregularities, 
 bears but a very fmall proportion to that of hufband- 
 men in China. In general there feems to be no other 
 bounds to Chinefe popiiloufnefs than thofe which the 
 neceffity of fubfiflence may put to it. Thefe bounda- 
 ries are certainly more enlarged than in other countries. 
 The whole furlace of the empire is, with trifling excep- 
 tions, dedicated to the proJudlion of food for man 
 alone. I'here is no meadow, and very little paflure ; 
 nor are fields cultivated In oats, beans, or turnips, for 
 the fupport of cattle of any kind. Few parks or plea- 
 fure grounds are feen, exccptliig thofe belonging to the 
 emperor. Little land is taken up for roads, which are 
 few and narrow, the chief communication being by wa- 
 ter. There are no commons, or lands fuffered to lie 
 wallc by the negleft, or the caprice, or for the fport of 
 great proprietors. No arable land lies fallow. The 
 foil, under a hot and fertihzing fun, yields annually, in 
 mcfl inflances, double crops, in confequence of adapt- 
 ing the culture to the foil, and of fupplying Its defefts 
 by mixture with other earths, by manure, by irriga- 
 tion, by careful and judicious induftry of every kind. 
 The labour of man is little diverted from that induftry 
 
 to
 
 C H I 
 
 [ 4 
 
 Chin-!- to minifter to the luxiinVs of the opulent and power- 
 — V ' ' ful) or ii] employments of no real life. Even tlie fiil- 
 diers of the Chinefe army, except durmg the Ihort in- 
 tervals of the guards which they are called to mount, 
 or the exercifes. or other occafional fcrvices which they 
 perform, are moftly employed in agriculture. Tlie quan- 
 tity of fubfillence is increafed alfo, by converting more 
 fpecies of animals and vegetables to that purpofe than is 
 ufual iii other countries. And even in the ])rcparation of 
 their food the Chinefe have economy and management." 
 
 The government of Ciiina is defpotic; and It is a cu- 
 rious fpedaole to behold fo large a proportion of the 
 whole hunnn race, conneAed together in one great fy- 
 llem of polity, fubinittiiig quietly, and through io con- 
 fiderahle an extent of country, to one great fovercign ; 
 and uniform in their huvs, their manners, and their lan- 
 guage, but dlifering effeiuially in each of thefe refpefts 
 from every other portion of mankind : and neither de- 
 firous of communicating with nor for.ning any defigns 
 againll the veli of the world. To produce fuch a phe- 
 nomenon, many caufes muftbe conibi.ied ; but perha[)S 
 the principal are to be found in the patriarchal fyftem 
 already mentioned, in the laws and cufloms of the em- 
 pire, and in the belief that the emperor is the vicege- 
 rent of heaven, and guided In all his aftions by divine 
 infpiration. 
 
 The patriarchal fyilem Is founded upon that filial 
 piety which the philofophers of China have uniformly 
 reprefented as the greateft of human virtues. Thefe 
 fagcs, while they fuccefsfuUy Inculcated this duty, have 
 left parental afFettion to its own natural influence ; and 
 hence In China parents are lefs frequently neglefted than 
 infants are expofed. The laws of the empire, to cor- 
 roborate the difpofition to fili.il obedience, furnifli an 
 opportunity for punlfhing any breach of it, by leaving 
 a man's offspring entirely within his own power: and 
 hence it is, that with the poor, marriage, as we have 
 faid, is a meafure of prudence ; becaufe the children, 
 particularly the fons, are bound to maintain their pa- 
 rents. 
 
 A Chinefe dwelling is generally furroundcd by a 
 wall fix or feven feet high. Within this inclolure a 
 whole family, of three generations, with all their refpec- 
 tlve wives and children, will frequently be found. One 
 fmall room Is made to fcrve for the individuals of each 
 branch of the family, fleeping In different beds, divided 
 only by mats hanging from the ceiling. One common 
 room Is ufed for eating. 
 
 The prevalence of this cuftom, of retaining the feve- 
 ral branches of a family under the fame roof, Is attend- 
 ed with Important effefts. It renders the younger tem- 
 perate and orderly in their conduft under the auhorlty 
 and example of the older ;' and it enables the whole to 
 fubfill, like foldlers in a mefs, with more economy and 
 advantage. As the venerable patriarch of each habi- 
 tation prefides over his deicendants with the authority 
 of a maglitrate ; fo the different orders of magillrates 
 are, in their different diftrltts and provinces, looked up 
 to with the veneration due from children to their pa- 
 rents, while the emperor is revered as the grand patri- 
 arch of the whole empire. 
 
 Another thing which contributes much to the per- 
 manency of the government and the internal quiet of the 
 empire is, that in China there is lefs inequality In the 
 fortunes than in the conditions of men. The ancient 
 
 23 ] CHI 
 
 annals of the empire teflify, that fo" along period of China, 
 time, the earth, like the other elements of natuic, was '^~~ 
 enjoyed by Its inhabitants alnoft in common. Their 
 country was divided into fm;Jl equal dlllriift'; ; every 
 dlftrict was cultivated conjointly by eight labouring fa- 
 milies, which compofed each hamlet ; and they enjoyed 
 all the profit of their labours, except a certain (hare 
 of the produce referved for public expcnces. It is 
 true, indeed, that after a revolution, dephred In all the 
 Cninefe hiltories, which happened prior to the Chriftian 
 era, the ufurper granted all the lands away to the part- 
 ners of his viiloncs, leaving to the cnltivitors of the 
 foil a fmall pittance only out of the revenue which it 
 yielded. Property in l.md alfo became hereditary : but 
 In procefs of time, the molt confiderable domains were 
 fubdivldcd Into very moderate parcels by the fucceffive 
 diftribution of the poffeffions of every father equally 
 among all his fons ; the daughters beinj; always married 
 without dower. It very rarely happened that there 
 was but an only fon to enjoy the whole property of his 
 deceafed parents ; and it could icarcely be increafed by 
 collateral fuccelTion. 
 
 From the operations of all thofe caufes, there was a 
 conllant tendency to level wealth ; and few could fuc- 
 ceed to fuch an accunuilatlon of It as to render them 
 Independent of any efforts of their own for Its Increafe. 
 Befides, wealth alone confers in China but little impor- 
 tance, and no power ; nor Is property, without office, 
 always perleflly fecure. There is no hereditary digni- 
 ty, which might accompany, and give it pre- eminence 
 and weight. The delegated authority of government 
 often leans more heavily on the unproteftcd rich than 
 on the poor, who are lefs objefts of temptation. And 
 It Is a common remark among the Chinefe, that for- 
 tunes, either by being parcelled out to many heirs, or 
 by being loll in commercial fpeculatlons, gaming, or 
 extravaga :ce, or extorted by oppreffive mandarines, fel- 
 doni continue to be confiderable In the individuals of the 
 lame family beyond the third generation. To afcend 
 again the ladder of ambition, it Is ncteffary, by long 
 and laborious ilnJy, to excel in the learning of the coun- 
 try, which alone qualifies for pulilic employments. 
 
 There are properly but three clalLs of men In China : 
 men of letter;, from wliom the mandarines a.-e taken ; 
 cultivators of the ground ; and mechanics, including 
 merchants. In Pekni alone is conferred the higheil de- 
 gree of literature upon thofe who, In public exanu'- 
 nations, are found raoft able in the fclences of morality 
 and government as taught In the ancient Chinefe wri- 
 ters ; witii which ftiidies the hltfory of their country I« 
 Intimately blended. Among fuch graduates all the ci- 
 vil offices in the ftate are dillrlbuted by the emperor ; 
 and they compofe all the great tribunals of the empire. 
 The candidates for thofe degrees are inch as have fuc- 
 ceeded In fimilar examinations in the principal city of 
 each province. Thofe who have been chofen In the 
 cities of the fecond order, or chief tf)wn of every dlf- 
 trift in the province, are the candidates in the provin- 
 cial capital. They who fail in the firft and fecond 
 claffes have ftill a claim on fubordinate offices, propor- 
 tioned to the clafs in which they had fucceeded. Ttiofe 
 examinations are carried on with great folemnity, and 
 apparent fairnefs. Military rank is likewife given to 
 thofe who are found upon competition to excel in the 
 military art, and in warlike extrclfes. This diftribution 
 
 of
 
 CHI [42 
 
 China, of offices contributes greatly to the peace of the em- 
 "~~* pire ; for the people cheerfully fubmit to the authority 
 
 of thofe whom tlicy believe to he placed over them by 
 merit alone, and love that conllitution which brings 
 within tlie reach of the nieancll fiibjcft, who has talents 
 and induftry, the hightil llation next to the fupreme. 
 
 " The gi eat tribunals are fituated, for the fake of con- 
 venience, near the fouthern gate of the imperial palace 
 at Pekin. To them accounts of all the tranfaCtions of 
 the empire are regularly tranlmitted. They are coun- 
 cils of reference from the emperor, to whom tiiey report 
 €very bufuiefs of moment, with the motives for the ad- 
 vice which they offer on the occafion. There is a body 
 of doftrine compofed from the writings of the earlicft. 
 ages of the empire, confirmed by fubfequent lawgivers 
 and fovereigns, and tranfmitted from age to age with 
 increafing veneration, which ferves as rules to guide the 
 judgment of thofe tribunals. This doflrine fcems, in- 
 deed, founded on the broadeft bafis of univerfal juftice, 
 and on the pured principles of humanity. 
 
 " His imperial majefty generally conforms to the fug- 
 geftions of thofe tribunals. One tribunal is dlrcited to 
 confider the qualifications of tiie different mandarines 
 for different offices, and to propofe their removal when 
 found incapable or unjuft. One has for objeft the pre- 
 fervation of the manners or morals of the empire, call- 
 ed by Europeans the tribunal of ceremonies, which it re- 
 gulates on the majiinij that exterior forms contribute 
 not a little to prevent the breach of moral rules. Tire 
 moll arduous and critical is the tribunal of cenfors ; 
 taking into its confideration the effeft of fubfifting laws, 
 the conduft of the other tribunals, of the princes and 
 great officers of Hate, and even (jf the emperor himfelf. 
 There are feveral fubordinate tribunals ; fuch as thofe 
 of mathematics, of medicine, of public works, of litera- 
 ture and hidory. The whole is a regular and confiifent 
 fyftem, ellablilhed at a very early period, continued 
 with little alterations through every dyiiailv, and re- 
 vived after any interruption from the caprice or pafiions 
 of particular princes. Whatever deviation has been 
 made by the prefent family on the throne, arlfes from 
 the admillion of as many Tartars as Chincfe into every 
 tribunal." The opinions of the former are fuppofed al- 
 ways to preponderate ; and many of thcin are indeed 
 men of confiderable talents and ftrength of mind, as 
 well as polilhed manners. They are, hovvever, in gene- 
 ral, fitter for military than civil offices. The hardy edu- 
 cation, the rough manners, the aClive fpirit, the v/an- 
 derlng dlfpoiition, the looie piinciples, and the irregu- 
 lar conduct, of the Tartar, fit him better for the pro- 
 feffion, practice, and purluits of war, than the calm, re- 
 gulated, and domeftic habits of the Chincfe. Warriors 
 feem naturally the offspring of Twrtary, as literati are 
 of China; and accordingly, the principal military com- 
 mands are conferred on natives of the former country, 
 as, with many exceptions indeed, the chief civil offices 
 are on thofe of the latter. 
 
 A military mandarin, who was much with Lord Ma- 
 cartney, and was himfelf a dillinguiflied officer, affert- 
 ed that, " Including Tartars, the total of the army in 
 the pay of China amounted to 1,000,000 infantry and 
 800,000 cavalry. From the obfervatlons made by the 
 embaffy in the courfe of their travels through the em- 
 pire, of the garrifons in the cities of the feveral orders, 
 aad of the military polls at fmall dillances from each 
 
 4 1 CHI 
 
 other, there appeared nothing unlikely in the calculi; Chlfls. 
 tion of the infantry ; but they met few cavalry. If the —— v— " 
 number mentioned leally do exifl, a great proportion of 
 them mull have been in Tartary, or on fome fcrvice di- 
 flant from tlie route of the enibafly. 
 
 " Of the troops, efpecially cavalry, a vafl number are 
 Tartars, who have a higher pay than their Chinefe fel- 
 low-foldiers. The principal officers of confidence in 
 the army are Tartars alfo. None of either nation are 
 received into the fervice but fuch as are healthy, (Irong, 
 and fightly. The pay and allowances of a Chinefe 
 horfeman are three Chinefe ounces, heavier than Euro- 
 pean ounces, and three-tenths of an ounce, of filver, 
 and fifteen meafures or rations (the weight not men- 
 tioned) of rice every lunar month. A Tartar horfe- 
 man, feven fimilar ounces of filver, and 20 meafures of 
 rice for the fame period. A Chinefe foot foldler has 
 one ounce and fix-tenths of an ounce of fiKer, and ten 
 meafures of rice ; and a Tartar of the i'ame defcrlption 
 has two ounces of filver and ten meafures of rice every 
 lunar month. Tiie Emperor furnifhes the arms, ac- 
 coutrements, and the upper garment, to all the foldiers. 
 Befidc their ordinary pay and allowances, they alfo re- 
 ceive donations from the Emperor on particular occa- 
 fions ; as when they marry, and when they have male 
 children born. On the death of their parents they ob- 
 tain ' a gift of confolation ;' as do their families when 
 the foldiers thcmfelves die. < 
 
 " The public revenues of China Proper are faid to be 
 little lefs than 200,oco,ooo of ounces of filver, which 
 may i)e equal to about 66,000, coo of pounds flerling ; 
 or about three times thofe of France before the late 
 fubverfion. From the produce of the taxes all the ci- 
 vil and military expenccs, and the incidental and extra- 
 ordinary charj^es, are firtl paid upon the fpot out of 
 the treafurles of the refpeftlve' provinces where fuch 
 cxpences are incurred; and the remainder is remitted to 
 the Imperial treafury at Pekin. This furplus amounted 
 in the year 1792 to the fum of 36,614,^28 ounces of 
 filver, or 12,204,776 pounds flerling, according to an 
 account taken in round numbers. In cafe of infurrec- 
 tions, or other occurrences requiring extraordinary cx- 
 pences, they are generally levied by additional taxes on 
 the provinces adjacent to the fcene of a6lion, or con- 
 nefted with the occafion of tiie expence. 
 
 " In the adminillration of the vail revenue of the ftate, 
 the opportunities oi* committing abufes are not often 
 neglecled; as may be inferred from the frequent confif- 
 catlon to the Emperor in confequence of fuch tranfgref- 
 fions. It is indeed affirmed, that much corruption and 
 oppreffion prevail in moil of the public departments, 
 by which confiderable fortunes are acquired, notwith- 
 llandlng the modicity of the public falaries." 
 
 With fuch a Handing army and fo vaft a revenue, it 
 will no longer appear wonderful that one man fhould 
 govern with defpotic fway even the immenfe multitude 
 of people who inhabit the empire of China, efpecially 
 trained up as thofe people are in habits of filial fubmif- 
 fion to their fuperiors. But there are fome circumflan- 
 ces in the fyltem of Chinefe policy, not yet mentioned, 
 which contribute perhaps more than even thefe habits 
 and that power to preferve the ftabillty of the govern- 
 ment. The Emperor referves to himfelf alone the right 
 of relieving the wants of the poor, produced by famine 
 or any other unforefeen calamity. On fuch occafions 
 
 he
 
 CHI [4 
 
 Cliliiu. hp aUvays comen forward, lie ordors tlic public gra- 
 ■""v— iiavica to be opened ; remits the taxes to thole who are 
 vilited with misfortune; affords afliihnce to enable them 
 to retrieve their affairs; and appears to his fubjefts as 
 flanding almoll in the place of Providence in their fa- 
 vour. He is perfeftly aware by how much a itronger 
 chain he thus maintaius his abfulute dominion, than the 
 mere dread of punilliment would afford. The emperor, 
 to whom the Britifh embaffy was fent, fliewed hirafelf 
 fo jealous of retaining the exclulive privilege of bene- 
 volence to his fubjefts, that he not only rejefted, but 
 was offended at, a propotal once made to him by lomc 
 confiderable merchants, to contribute towards the relief 
 of a fufFering province ; whilft he fcrupled not, at the 
 fame time, to accept the donation of a rich widow to- 
 wards theexpences of a war in which he was engaged. 
 This veneration, excited towards the emperor by his 
 apparent benevolence, is increafed by an opinion zea- 
 loufly inftilled into the people, that he has the faculty 
 of predicting future events of the greatell importance. 
 The Chinefe, given up to the dotages of judicial aftio- 
 logy, are firmly perfuaded that eclipfts of the fun and 
 moon have a powerful influence on the operations of 
 nature and the tranfaftions of mankind ; and the pe- 
 riods of their occurrence become, of courfe, objefts of 
 attention and folicitude. The government of ttie coun- 
 try, ever anxious to eflablifh its authority in the general 
 opinion of its fuperior wildom and conflant care to*- the 
 welfare of the people, employs the European milHon- 
 aries at Pekln (for it is doubtful if any one of the na- 
 tives has fo much foence) to calculate eclipfcs, and 
 then announces them to the people with that iolemnity 
 which is fitted to enfure veneration for the fuperintend- 
 ing power whence fuch knowledge is immediately de- 
 rived to them. Eclipfes of the fun, in particular, are 
 confidered as omenous of fome general calamity ; and 
 as great pains are taken to infpire them with a belief 
 that their profperity is owing to the wildom and virtues 
 of their fovereign, fo they are tempted to attribute to 
 fome deficiency on his part whatever they think por- 
 tentous. To this prejudice the emperor finds it pru- 
 - dent to accommodate his conduct. He never ventures 
 on any undertaking of importance at the approach of 
 a folar eclipfe, but affefts to withdraw himfclf from the 
 prelence ot his courtiers, to examine ftridfly into his 
 late adminiftration of the empire, in order to correft 
 any error, for the commilTion of which the eclipfe may 
 hmve been an admonition. On thtfe occafions he in- 
 vites his fubjefts togive him freely their advice: but it is 
 plain that advice muft be offered with great deference 
 to a being for whofe admonition the motions of the fun 
 and moon are believed to be regulated ; and while fuch 
 notions are implicitly admitted, the perfon of the Chi- 
 nefe emperor, as well as his authority, mufl be looked 
 upon by his fubjeds as fomething more than human. 
 SuppL. Vol. I. Part II. 
 
 25 3 CHI 
 
 This ij in t:\&. the cafe. He is not only approached 
 in perfon witii tcftlmonies of the utmoft refpedt, but is 
 adored when abfent with all the rites and ceremonies 
 whii.h are ufed by the Chinefe in the worlhip of their 
 divinities. On his birth-day, at the new and full moon, 
 and piobably on other feflivals, all the mandarines re- 
 lident in the neighbourhood of any of his numerous pa- 
 laces aflfemble about noon, and repairing to tiie palace, 
 folenmly proflrate thcmfelves uine times before the 
 thror.e, their foreheads llrikiiig the floor each time ; 
 whilft inceufe is burning on trlp(.ds on each fide of it, 
 and offerings are made, on an alter before it, of tea and 
 fruits to the fpirit of the abfent emperor. Over the 
 throne are feen the Cliinefe characters of glory and per. 
 feftlon ; and the name of the Deity is given to the em- 
 peror, who is confidered by his votaries as polTefling in 
 fome fenle the attribute of ubiquity. Mr Barrow, one 
 of the gentlemen of the embalTy, was prefent at Tuc'ti- 
 mln-yuen, one of tiie imperial palaces, when tliefe idola- 
 trous rites of adoration were performed; and lie was af- 
 fured that they took place on that d ly in ail parts of 
 the empire, th^; proltraters being everywhere attentive 
 to turn their faces towards the capital. 
 
 That he who claims adoration in his abfeuce does 
 not appear on his birth-day to receive the compliments 
 of his fubjeds, will not furprilc the reader. The man- 
 ner in which that fellival is celebrated at the palace, 
 where the emperor happens to be refident, is thus de- 
 fcribed by Sir George Staunton, who w-itne.Ted this 
 more than augufl ceremony at the palace of Zhe-hal in 
 Tartary. " The princes, tributaries, ambaffaJors, great 
 officers of ftate, and principal mandarines, were afi'em- 
 bled in a valt hall; and upon particular notice, were in- 
 troduced into an inner building, bearing, at leaft, the 
 femblance of a temple. It was chiefly furnifhed with 
 great Inltruments of mufic, among whicli were fcts of 
 cylindrical bells, fulpend-d in a line from ornamented 
 frames of wood, and gradually diminiiliing in fize from 
 one extremity to the other, and alio triangular pieces 
 of metal arranged in the fame order as the bells. To 
 the found of thefe inftruments a How and folemn hymn 
 was fung by eunuchs, who had fuch a command of tlieir 
 voices as to referable the effett of the mufical glalfcs at 
 a dillance. The performers were directed, in gliding 
 from one tone to another, by the llriking of a fhrill 
 and fonorous cymbal ; and the judges of nuillc among 
 the gentlemen of the embaffv were much pleated with 
 their execution. The whole had indeed a grand eflTcd. 
 During the performance, and at particular lignals, nine 
 times repeated, all the perfons proltrated tliemfelves 
 nine times, except the ambaffador and his fult, wlio 
 made a profound obeifance (a). But he whom it was 
 meant to honour, continued, as if it were in imitation of 
 the Deity, invllible the whole time." 
 
 That the awful imprellion meant to be made upon 
 
 Chi- 
 
 H 
 
 the 
 
 (a) The Chinefe court, which eonfiders all other fovereigns as fubordlnate to their own, exa£ts from foreign 
 minlfters, as well as from natives of the empire, nine proftrations upon their firll introduAlon to the emperor. 
 This demand was made, in the lafl century, of the Dutch, wno inftantly complied with it in hopes of obtainii.g 
 in return fome lucrative advantages ; and the confequence was, that their amballador was treated with negleft, 
 and difmiffed without promlfe of the fmalleft favour. It was likewife made of a Ruffian ambaffador in the pre- 
 fent century ; but he would not complv with it, until a regular agrfjment was made for its return, on a like oc- 
 cafion, to his own fovereign. Lord Macartney, who was repeatedly u-gpd to go through the fame abjeS cere- 
 mony, difplayed fuch firmnefs and addrefs, that after much evalion it was at lafl announced to him, that his im- 
 perial majefly would be fatisfied with the fame form of refpectful obedience that the Engllfh are in the habit of 
 paying to their own fovereign ; and upon thefe lerme his lordfhlp w,as introduced and gracioufly received.
 
 C H I 
 
 [ 426 1 
 
 C H I 
 
 China, the minds of men by this apparent worfliip of a teilovv- 
 ■~~V— ~ mortal might not be too quickly ellaccd, all fcencs of 
 fport and gaiiity w ere poftponed to the next day, when 
 a variety of enteitainmtnts was exhibited in the pre- 
 fence of the emperor, furrounded by his court and tri- 
 butary princes. ' 
 
 Notwithftanding the general veneration of the Chi- 
 iiefe for the perfon and government of their emperor, 
 tlie mandarines afferted that a fed had for ages fubfifl- 
 ed in the country, vvhofe chief principles were founded 
 on an antipathy to monarcliy, and who nourirtied hopes 
 of at laft fiibverting it. Their meetings were held in 
 the ntiTioft fecrecy, and no man avowed any knowledge 
 of tliem ; but a fort of inquifition was faid to be efta- 
 blifhed in order to find them out, and they who were 
 fufpeded of fucli fentiments were cut off, or himted out 
 of fociety. Should the French declaration of the rights 
 of man, which, through the zeal of its authors, has 
 been tranflated into one of the languages of India, find 
 its way into China (of which the court is faid to be 
 much afraid), it would indeed be a powerful engine in 
 the hands of this fccret fed to fap the foundations of the 
 ancient government. The minds of many of the Chinefe 
 are far from fatisfied with their condition, which lays 
 both their perfons and their fortunes at the mercv of 
 the mandarines. No private man in China is exempted 
 from corporal punifhment, which luijy be inftantly in- 
 flifted on him at the nod of a magiftrate; and when he 
 has occafion to fpeak to a great mandarine, he is obhged, 
 by the police of the country, to throw himfelf on his^ 
 knees, and in that pofture to communicate his bufinefs. 
 The mandarine himfelf, on the xither liand, lies under 
 the hardship of being frequently refponfible for events 
 which he could not controul. Upon the general prin. 
 ciple that it is his duty to watch over the morals of the 
 people, he is in many cafes conlidered as a criminal for 
 not preventing crimes which he had not been able to 
 prevent. The mandarines are thus aware of not being 
 guaranteed by good conduA againft difgrace; and feel- 
 ing the chagrin of infecurity, many of them muft doubt- 
 lefs be ripe for a revolt. Fear may keep them quiet du- 
 ring the reign of a fovercign pofiefled of abilities and vigi- 
 lance ; but the maxims which regulate the imperial luc- 
 eeffion are liich, that a firm confederacy could hardly 
 - fail at the death of an emperor to introduce great changes 
 into the conftitution. The throne of Ciiina is neither 
 hereditary nor eleftlve. The choice of a fucceffor is 
 left entirely to the reigning prince, who may exclude, 
 as has been inftanced, even his own offspring and fami- 
 ly. To prevent commotions and fraud, it is no un- 
 common praftice for the emperor, during his lifetime, 
 to declare his fucceffor ; fur when his fuccefGon is fet- 
 tled by a written teftament, the throne is not always 
 filled by him for whom it was dellined. The father of 
 the emperor to whom the Britifh embaffy was fent, is 
 faid to have obtained pofl'effion of the throne by fud- 
 denly entering the palace in the laft moments of his 
 predeceffor, and fubftituting his own name in a tefia- 
 ment intended for the exaltation of another. 
 
 To what has been faid in the Encyclopsedia of the re- 
 ligion of the Chinefe, we have here very little to add. 
 Various deities are worfhipped in the empire by very 
 different rites and ceremonies ; but there is in China no 
 ftate religion. None is paid, preferred, or encouraged 
 by it. The emperor is of one faith j many of the man- 
 
 darines of another ; and the maiority of th-e cornrr.on 
 people of a third, which is that of Fo. The men of let- "" 
 ters venerate rather than adore Confucius; and meet to 
 honour and celebrate his memoiy in halls of a fimple but 
 neat coi.flruttion. The numerous and lower clalTes of 
 the people are Icfs able than inclined to contribute much 
 towards the ereftion of large and. cofVIy edifices for pu- 
 blic worfhip : their attention is almofl wholly engaged 
 by their houfhoid gods ; for every houfe has its altar 
 and its deities. 
 
 " No people are, in faft, more fuperftitious than the 
 common Chinefe. Beiide the habitual offices of devo- 
 tion on the part of the priefts and females, tlie temples, 
 are particularly frequented by the difciples of Fo pre- 
 vioufly to any undertaken of importance ; whether to 
 marry, or go a journey, or conclude a bargain, or 
 change fituation, or for any other material event in life, 
 it is necefTary firlt to confuit the fuperintendant deity. 
 This is performed by various methods. Some place a • 
 parcel of confecrated flicks, differently marked and 
 numbered, which the confultant, kneeling before the 
 altar, fliakes in a hollow bamboo, until one of tliem falls 
 on the ground ; its mark is examined, and referred to a 
 correipondent mark in a book %vhich the piieft holds- 
 open, and fometlmes even it is written upon a fheet of; 
 paper pafled upon the infide of the temple. Polygonal 
 pieces of wood are by others thrown into the air. Each- 
 fide has its particular mark ; the fide that is uppermoft 
 when fallen on the floor is in like manner reientd to 
 its correfpondent mark in the book or fheet of fate. 
 If the firfl throw be favourable, the perfon who made- 
 it proftrates himfelf in gratitude, and undertakes after- 
 wards with confidence the bufinefs in agitation. But 
 if the throw fliuuld be adverfe, he tries a fecond time, 
 and the third throw determines, at any rate, the qucf- 
 tion. In other refpefts, the people of the prefent day 
 feem to pay little attention to their priefls. The 
 temples are, however, always open for luch as choofe 
 to confuit the decrees of heaven. They return thanks, 
 when the oracle proves propitious to their wifhes. Yet- 
 they oftener caft lots to know the iffue of a projccled: 
 enterprife than fup])licate for its being favourable: and 
 their worfhip conhfls more in thankfgiving than in 
 prayer. 
 
 " The Chinefe are feldom faid to carry the objefts to 
 be obtained by their devotion beyond the benefits of 
 this life. Yet the religion of Fo profeffes the doctrine 
 of the tranfmigration of fouls, and promiles happinefs 
 to the people on conditions, which were no doubt ori- 
 ginally intended to confifl in the performance of moral 
 duties ; but in heu of which are too frequently fubfti- 
 tuted thofe of c-ontributions towards the ereftion or re- 
 pair of temples, the maintenance of priefts, and a flrlft 
 attention to particular obfervances. The negleft of 
 tliefe is announced as punlihable by the fouls of the dcr 
 faulters pafhng into the bodies of the meanetl animals, 
 in whom the f'ufferings are to be propo.'tioned to the 
 tranfgreflions committed in the human form." 
 
 Though the Chinefe artifls are very ingenious Es 
 mere workmen, there is hardly any thing which de- 
 fcrves the name of fcience in the whole empire. S» 
 little is the ftudy of mathematics cultivated, that there 
 are few fliopkeepers in China who can perform the or- 
 dinary operations of arithmetic ; but call up their ac- 
 counts by means of an inflrument called /man/iaw (See 
 
 SWAM- 
 
 Chl.
 
 C H I 
 
 [ 427 ] 
 
 C H I 
 
 Chi-11. SwANPAv, Encyei). Though the compofition of ,i;uii. 
 """V——' powder was certainly known in China much e.iiher 
 than in Europe, and thouj!;h the Chiiiefe had employed 
 it from the beginning in blading rocks, and in making 
 a vaft variety of five-works ; yet Sir George Staunton 
 fetms convinced, that they newr thought of tlie inven- 
 tion of guns till they were taught by the Europeans to 
 introduce them into their armies. 
 
 Tlie ftite of phyfic in this vail country is extremely 
 low, being nowhere taught in p\ibiic ichools or colleges. 
 *' A young man who willies to become a phyficlan, has 
 no other way of acquiring medical knowledge than by 
 engaging hinilelf to fome praftitloncr as an apprentice. 
 He has thus the opportunity of feeing his mailer's 
 pratliL-e, of viliting his patients with him, and of learn- 
 ing fuch parts of his knowledge and lecrets as the other 
 choofes to communicate to him. The emoluments of 
 the profefGon feldom exceed the fl<ill of the practitioner. 
 As many copper coin as fcarcely are equal to fix pence 
 fttrling is faid to be the ufual fee among the people ; 
 ■End perhaps quadruple among the mandarines. Medi- 
 cine is not divided in China into diftlncl branches as iu 
 TTioll parts of Europe. The fame perfon afts asphyli- 
 fian, furgeon, and apothecary. The lurgical part of 
 the profefTion is ftlll more backward than the ot|iers. 
 Amputation, in caies of compound fratlure and gan- 
 grene, is utterly unknown ; and deatii is the fpeedy 
 confequence of fuch accidents. The Chinefe method 
 of Inoculation, which was introduced into the empire 
 Ebout-the beginning of the tenth century of our era,' 
 is as follows : When the difeafe breaks out in any 
 diftrift, the phyficians of the place carefully colieft a- 
 ■quantity of ripe matter from puftules of the proper fort ; 
 which being dried and pulverifed, is clolely ihut up in 
 a porcelain jar, fo as to exclude from it the atmofpheric 
 sir ; and in this manner it will retain its properties for 
 many years. When the patient has been duly prepared 
 by medicines, generally of an aperient kind, and Itrlftly 
 dieted for a fhort time, a lucky day ischofen to Ipi inkle 
 a little of the variolus powder upon a fmall piece of 
 fine cotton wool, and to infert it into the nollrlls of 
 the patient. 
 
 " No male phyfician is allowed to attend a pregnant 
 woman, and Hill lefs to pradtife midwifery ; in the in- 
 delicacy of which both fexes feem to agree in China. 
 There are books written on that art for the ufe of fe- 
 tnale pradlltioners, with drawings of the ftate and pofi- 
 tion of the mfant at different periods of geilation ; toge- 
 ther with a variety of dlreftions and prefcriptions for 
 «very fuppofeti cafe that may take place : the whole 
 mLted with a number of fuperllltious obfervances. 
 
 Many praftitioners of phyfic take the advantage, as 
 elfewhere, of the obfcurity in which that art is invol- 
 ved, and of the ignorance and credulity of the people, 
 to gain money by the fale of noftrums and feerets of 
 their own. They diilribute hand bills, fetting forth 
 the efficacy of their medicines, with attelled cures an- 
 nexed to them. And there is one fctt which boldly 
 arrogates to itftlf the pofleffion of a medical fecret not 
 to die! To thofe who had all the enjoyments of this 
 life, there remained unaccomplllhed no other wifli than 
 that of remaining for ever in it. And accordingly fe- 
 vera! fovereigns of China have been known to cherifh 
 the idea of the pofTibility of fuch a medicine. They 
 had put themfelves, in full health, under the care of 
 
 thofe religious empirics, and took large draughts of the C'ini, 
 boalltd beverage of immortality. 'I'he compofition tJhinefe. 
 did not confiit of merely harmlefs ingredients; but pro- ' 
 bably of luch extratts and proportions of the poppy, 
 and of other fublt-anies and liquors, as occ.d'ionlng a 
 temporary exaltation of the imagination, pafTcd for an 
 indication of its vivifying effefts. Thus encouraged, 
 they had recourfe to frequent repetitions of the dofc, 
 which brought on quickly languor and debility of fpi- 
 rits: and the deluded patients otten became vitlims to 
 deceit and folly in the flower of their age. 
 
 '^ There are in China no profen'ors of the fclences 
 connciled with medicine. The human body is never, 
 unlcis privately, difl'eCled there. Boiiks, indeed, with 
 drawings of Its internal ftruilure are fometinies publifh- 
 ed ; but thefe are extremely imperfect, and coufulted, 
 perpaps, oftener to find out the name of the fpirit un- 
 der whofe proteftlon each particular part is placed, than 
 fur oblerving its form and fituation. 
 
 " It is a matter of doubt, whether natural hiflory, na. 
 tural philofophy, or cliemillry, be, as fclences, much 
 more improved than anatomy in China. There are fe- 1 
 veral treatifes, indeed, on particular fubjedls In each. 
 The Chinefe likewife polTefs a very voluminous Ency- 
 clopedia, containing many fadls and obler-.'ations rela- 
 tive to them ; but from the few refearches which the 
 gentlemen of the embaffy had lelfure or opportunity 
 to make during their fiiort vifit to the country, tncy 
 perceived no traces of any general fyilem or dodlrine 
 by which feparate fails or obfervations were conneeled 
 and compared, or the common properties of bodies af- 
 certained by experiment ; or where kindred arts were 
 conduced on fimilar views, or rules framed, or deduc- 
 tions drawn from analogy, or principles laid down to 
 conilitute a fcience." 
 
 Of all people the Chinefe are perhaps the mod eager 
 in their curiolity about foreigners coming among them, 
 and the moil indifferent about the countries of fuch fo- 
 reigners. They have been always in the habit of con- 
 fining their ideas to their own country, emphatically 
 ilyled the middle kingdom. No Chinefe ever thinks of 
 quitting it, except a few of defperate fortunes refiding 
 near the fea-coafl, or fea-faving men, who form a clafs, 
 in a great mealure, apart from fociety. Even foreign 
 commodities confumed iu China remind them only of 
 Canton, whence they received them, as if produced in 
 it ; and thefe commodities they confider, perhaps pro- 
 perly, as of no real benefit to the empire. Regions out 
 of Afia are fcarcely mentioned in their books, or no- 
 ticed in their dillorted maps ; and the great body of 
 the people would be little gratified with accounts of 
 fuch regions, which did not contain tales of vi'onders 
 not performed at home, or of powers exerted bevond 
 the ordiiiary boundaries of nature. 
 
 CHINESE PUMP. See Pump in this Supplement. 
 
 Chinese IFeighfs are fo very different in many refpects 
 from thofe in ufe elfewhere, that it will at lead gratify 
 the curiofity of our readers to take fome notice of them 
 in this Work. Of thefe weights Charles Coquebert 
 has prefented a fpecimen to the Philoniathematical So- 
 ciety in Paris. They are made of copper, and bear a 
 great refemblance in form to the body of a violin. 
 Like that inllrument, they are rounded off at the ex- 
 tremities, and indented on the fides to admit the fingers. 
 The faces are flat and parallel, and have Chinefe cha- 
 3 H 2 raders
 
 Chinefa 
 
 CHI. [42 
 
 raifleis engraven on the upper furface. They advance 
 ' iu a regular decimal progrcfiion, of which Coqucbcrt 
 has difcovered four diiHiift fcries, the units of which 
 are in the proportion of I, 10, 100, lOOO. Iiiftead of 
 employing a combination of one, .two, four, and eight 
 units, or after the new fyftem of one, two, and five units, 
 the Cliinefe have a diftinft weight for every intermedi- 
 ate number between one and ten. Thus they have weights 
 of 1.2, 3, 4> 5, 6, 7, 8, 9, 10, 20, 30, 40, i;o, 60, 70, 
 80, 90, &c. Of courfe, thofe weights which (land re- 
 lated to each other in the proportion of 6 to 7, 7 to 8, 
 8 to 9, 9 to 10, differ fo little in fize, that it would be 
 impofTible to diftinguiih them witliout the help of the 
 charatlcrs which are engraven upon the face. This is 
 confefTedly a defeft in the fyftem. Of the four diffe- 
 rent feries exhibited to the fociety, the higheil bears in 
 China the name of kin, and is nearly of equal value 
 \vith a pound avoirdupois. The kin contains ten times 
 the number of units of the next inferior weight, which 
 the Chinefe denominate hang or loam, and which the 
 Europeans call tufl, Uuile, or Chinefe ounce. This ounce 
 is divided into ten t/'.tn, which anfwers nearly to our 
 drachm. The tfien is again fubdivided into ten fm. 
 The Chinefe extend the decimal fubdivifion of their 
 weights confiderably farther. They have diftinft names, 
 which are all monofjllabic, for nine feries below the fen. 
 Suppofing the kin to Hand for unity, they have, 
 
 000000000000 
 
 8 ] 
 
 C H O 
 
 I, 
 
 - 1* 
 
 000000000 
 
 c:U;>c:c--OOc 
 -^ o £ — 
 
 The Chinefe weights, compared with the greateft 
 precifion, and with the help of the bed inftruments, 
 Kear the following proportion to our weights : The 
 kin is equal to 1 pound iz ounces 2 drachms 24 
 grains; the leang i ounce J drachm 60 grains; the tfien 
 70 grains ts ; the fen 7 grains -rig. Coufequently the 
 lad of this feries, the fun, amounts to no more than o 
 grains 000CO00070S. 
 
 CmNhSE Wheel is an engine employed in the province 
 of Kiang-fee, and probably through the whole empire, 
 for raifing water from rivers to irrigate plantations of 
 fugar canes, on a fandy foil, confiderably elevated above 
 the level of the river. By Sir George Staunton, who 
 iays that it is ingenious in its contrivance, cheap in its 
 materials, eafy in its operation, and effcdtual to its pur- 
 pofe, it is thus defcribed : 
 
 " Two hard wood-pofls or uprights are firmly fixed 
 in the bed of the river, in a line perpendicular to its 
 bank. Thefe polls fupport the axis, about ten feet in 
 length, of a large and durable wheel, confifling of two 
 unequal rims, the diameter of one of which, clofcil to the 
 bank, being about fifteen inches ihorter than that of 
 the outer rim ; but both dipping in the ftream, while 
 the oppofite fegment of the wheel rifes above the eleva- 
 ted bank. This double wheel is connefted with the 
 axis, and is fupported by 16 or 18 fpokes obliquely in- 
 ferted near each extremity of the axis, and crofTing each 
 other at about two-thirds of their length. They are 
 there flrengthened by a concentric circle, and fallened 
 afterwards to the rims : the fpokes inferted in the in- 
 terior extremity of the axis reaching the outer rim, 
 and thofe proceeding from the exterior extremity of the 
 fame axis, reaching the inner and fmaller rim. Between 
 the rims and the croffing of the fpokes is woven a kind 
 
 of clofe bafliet-work, ferving as laddie-boards or floats, 
 which meeting fucceflively the current of the (Iream, 
 obey its impulfe, and turn round the wheel. To both 
 its rims are attached fmall tubes or Ipouts of wood, 
 with an inclination of about 25 degrees to the horizon, 
 or to the axis of the -vhtel. The tubes are clofed at 
 their outer extrenn'ty, and open at the oppofite end. 
 By this pofition the tubes, which happen iu the motion 
 of the wheel to be in the flreani with their mouths or 
 open ends uppcrmoll, fill with water. As that fegment 
 of the wheel rifes, the mouths of the tubes attacli to H, 
 alter their relative inclination, but not fo much as to let 
 their contents flow out till fuch fegment of the wheel 
 becomes the top. The mouths of thofe tubes are then 
 relatively depreffed, and pour the water into a wide 
 trough placed on polls, from whence it is conveyed as 
 may be wanted among the canes. 
 
 " The only materials employed in the conllrudlion 
 of this water-wheel, except the nave or axis, and the 
 polls on which it refts, are afforded by the bamboo. 
 The rims, the fpokes, the laddie-boards or floats, and 
 the tubes or fpouts, and even the cords, are made of 
 entire lengths, or fingle joints, or large pieces, or thin 
 flices, of the bamboo. Neither nails, nor pins, nor 
 fcrews, nor any kind of metal, enters into its conflruc- 
 tion. The parts are bound together firmly by cord- 
 age, alfo of flit bamboo. Thus, at a very trifling ex- 
 pence, is conflrufted a machine which, without labour 
 or attendance, will furnifh, from a confiderable depth, 
 a refervoir with a conftant fupply of water adequate to 
 every agricultural purpofe. 
 
 " Thefe wheels are from 20 to 40 feet in diameter, 
 according to the height of the bank and confequent 
 elevation to which the water is to be raifed. Such a 
 wheel is capable of fuflaining with eafe 20 tubes or 
 fpouts, of the length of four feet, and diameter two 
 inches in the clear. The contents of fuch a tube would 
 be equal to fix-tenths of a gallon, and a periphery of 
 20 tubes, twelve gallons. A ilream of a moderate ve- 
 locity would be fufficient to turn the wheel at the rate 
 of four revolutions in one minute, by which would be 
 lifted 48 gallons of water in that fliort period ; in one 
 hour, 2'6ho gallons ; and 69120 gallons, or upwards of 
 300 tons of water, in a day." 
 
 Sir George, who faw this wheel in motion, thinks it 
 preferable in many refpefts to any machine yet in ufe 
 for limilar purpofcs. He obferves, that, while it ap- 
 proaches near to the Perlian wheel, of which a defcrip- 
 tion and figure is given in the article Hydrostatics, 
 Encycl. it is more fimple than that wheel in its con- 
 trivance, and much lefs expeniive. This is indeed true ; 
 but the fimpleft engine of the kind, and therefore the 
 btfl that has yet been invented, is perhaps that which 
 is employed to throw water into the mofs of Blair 
 Drummond in Perthfhire. See Moss, Encycl. 
 
 CHOPINE, Chop?ine, or Chopeene, a high fhoe, or 
 rather chig, worn 2CO years ago by the Italians. 
 
 Tom Coryat, in his Crudities 161 1. p. 262, calls 
 them chapineys, and gives the following account of them ; 
 "There is one thing uled of the Venetian women, and 
 feme others dwelling in the cities and towns fubjedl to 
 the figniory of Venice, that is not to be obferved, I 
 thinke, amongfl any other women in Chriflendome, 
 which is fo common in Venice, that no women whatfo- 
 ever goeth without it, either iu her houTe er abroad. 
 
 Chinefe, 
 Chopine.
 
 C H R 
 
 ChronoUv 
 
 gic.-:l. 
 
 Chowdry a thing made of wood and covered luith leather of fundry 
 colors, fame ivil/j luhite, fume redde, fame yellow. It is 
 callt-d a cliajjiney, which they wear under their Jhoes. 
 ^ Many of them are cun'oiilly painted ; fome alfo of tliem 
 1 have feeii faiily gilt ; lo uncomely a thiiiy;, in my 
 opinion, that it is pitty this fooh'fli cuftom is not cltane 
 banilhed and exterminated out of the citie. There ,ire 
 many of thefe chapineys of a great height, even half a yard 
 l>igh, which maketh many of their women that are very 
 Jhort feeme much taller than the tailed women we have 
 in England. Alfo I have heard it obferved among 
 them, that by how much the nobler a woman is, by fo 
 inuch the higher are her chapineys. All their gentle- 
 women, and moll of their wives and widowes that are 
 of any wealth, are afliiled eyther by men or women 
 when they walke abroad, to the end they may not fall. 
 They are borne up mod commonly by the left arme, 
 otherwife they might quickly take a fall." 
 
 CHOWDRY, in Bengal, the pofleffor of feveral 
 Taloois. It is alfo ufed as fynonymous with Talookdar, 
 anciently a cojleclor. See Talook in this Supplement. 
 CHRISOM was not, as is faid in the Encyclopedia, 
 a face-cloth or piece of linen laid over the child's head 
 tvhen itwas baptized ; but it was a white vefture or 
 garment, which, immediately after it was baptifed, the 
 prieft put upon it, faying, " Take this white vefture as 
 a token of the innocency, which, by God's grace in 
 this holy facrament of baptifm, is given unto thee, and 
 for a fign whereby thou art admoniilied, fo long as thou 
 livcft, to give thyfclf to innocence of living, that after 
 this tranfitory life thou mayeft. be partaker of life ever- 
 lading. Amen." 
 
 As foon as the pried had pronounced thefe words, 
 he anointed the infant upon the head, faying, " Al- 
 mighty-.God, the Father of our Lord Jefus Chi-ift, who 
 hath regenerated thee by water and the Holy Ghoil, 
 and hath given unto thee the remifilon of all thy fins ; 
 he vouchfafe to anoint thte with the un(3.ion of his 
 Holy Spirit, and bring thee to the inheritance of ever- 
 lafting life. Amen." 
 
 It was from this anointing or chrifm that the white 
 garment got the name of chrifom, which, after being 
 v?orn a few days, was offered to the pried to be kept 
 in the church or vedrv, in order to be produced as 
 evidence againd the perfon whofe chrifom it was, Ihould 
 he afterwards deny the faith in which he had been 
 baptized. Thefe ceremonies were retained, for fome 
 time after the reformation, in the church of England, 
 which ordered the mother of the child (if the child was 
 then alive) to offer, v^hen die was churched, {.he chrifom 
 and other accudomed offerings. If the child died be- 
 fore its mother was churched, the chrifom was not gi- 
 ven to the pried, but employed as a fhroud, in which 
 the body was buried ; and hence it is that chrifoms are 
 now enumerated, mod abfurdly indeed, in the weekly 
 bills of mortality. We (ay abfurdly ; becaufe children 
 who die unb-iptized are called chrifoms, though the chri- 
 fom, when it was ufed, was never put on till baptifm. 
 See Whitbf on the Book of Common Prayer, Isfc. 
 
 CHRONOLOGICAL characteks are charafters 
 by which times are dldinguiihed. Of thefe fome are 
 natural or aftronomical ; others, artificial or hidorical. 
 The natural charadters are fuch as deper.d on tlie mo- 
 tions of the liars or luminaries, as ulipfes, foljlices, equi- 
 
 r 429 ] 
 
 C H R 
 
 noxes, the different afpelts of the planets, &c. The ar- 
 tificial charaders are tliofe that have been invented and 
 edabliflicd by men ; as the folar cycle, the Ivnar cycle, 
 &c. Hillorical chronological ebaraders are thofe fup- v 
 ported by the tellimuny of hilloriaus, uben they fix the 
 dates ui certain events to certain y«r/W.f. Hutlon's Ma- 
 thematical l)iflion,iry. 
 
 CHRONOSCOPE, a word fometimes ufed to de- 
 note a pendulum or machine to meafure time. 
 
 CHUCKIAH, in Bengal, the jurifdiclion of a Fa. 
 gedar. See Fogedar in this Supplement. 
 
 CHURCH is a word which has many different fig- 
 nifications, all fufficiently explained in the Eiicyclopje- 
 dia Britannica, where there is likewife given a concife 
 hi/lory of the Chridian church (fee History, Sett, ii.), 
 defective, indeed, but perhaps not more fo than was to 
 be expeftt d from the limits of the work and the extent 
 of the fubjett;. 
 
 Of the eonditution of the primitive and apodolical 
 chtirch, no man can have a corredt notion who has not 
 taken the trouble to confult the primitive and apodoli- 
 cal writers ; for, as we have elfewhere obferved, all mo- 
 dern compilers of eccleiiadical hiftory are more or lefs 
 prejudiced in behalf of the particular church to which 
 they belong, and wred the language of the original 
 writers fo as to make them bear witiiefs to the antiqui- 
 ty of modes of faith and ecclcf-ajUcal polity, which are not 
 perhaps a hundred years oM. 
 
 On this account we fhall not here attempt to correft 
 what we really think the midakes of him who compiled 
 the fedtion of ecclefiadical hiftory in the Encyclopadia. 
 Moflieim and Sir Peter King, whom he feems to have 
 implicitly followed, were indeed great men ; and it 
 would be folly to deny that the Hiftory oi the former, 
 and the Inquiry of the latter into the Conflitiilion of the 
 Primitive Ckurch, are works of learning and ingenuity 5 
 but it is not perhaps too much to fay, that both au- 
 thors wrote under the influence of prejudice. Our read- 
 ers will difcover how clofcly either the one or the other 
 has adhered to truth, by ftudying the eccleiiadical wri- 
 ters of the fiid four centuries. Such a dudy will make • 
 them acquainted with the dottrines, difcipline, ,Tnd wor- 
 fliip of the church before it was incorporated with the 
 date ; and we know not that kind of knowledge which ' 
 i'i of more importance to the divine, however much it 
 may be defpifed in tills age of alfedcd fcience and real • 
 ignorance. 
 
 Of the priiicipal churches at prefent exiding, a pretty 
 full account is given in the Encyclopsdia, either under 
 their d'fferent denominations, or under the titles of thofe 
 tenets by which they are chiefly didinguiflied ; ib that 
 from that Work alone a reader may form a tolerably 
 accurate notion of the faith, worfhip, eonditution, and 
 dilcipline of the church of Rome, the churches of Eng- 
 land and Scotland, the Lutheran and Calviniltical- 
 churches on the continent of Europe, as well as of the 
 various iects which have arifen in thefe kingdoms du- 
 ring the courfe of the lad and prefent centuries. There 
 is, however, one church which boads of a very high an- 
 tiquity, and is certainly f])rcad over a larger extent of 
 country than all the other churches that we have men- 
 tioned, of which the account given in the Encyclopse- 
 dia is exceedingly defective. Our readers will perceive 
 that the church to which we allude is 
 
 The^ 
 
 Chreno- 
 
 Icoie 
 
 II 
 
 Church.
 
 C 11 u 
 
 [ 430 ] 
 
 C H U 
 
 I 
 
 ;C 
 church. 
 
 Church. The Greek Chvkch, which comprehends in its bo- 
 ' fom (a) a coiiridciahle part of Greece, the Grecian 
 The Greek '<1^*' VValhichia, Moilavia, Egypt, Ab; (linia, Nubia, 
 Lybia, Arabia, Mt-fopotamia, Syria, Cilicia, and Pale- 
 iline, which are all under tlie jurildittion of the patri- 
 archs of Coullaiitinople, Alexandria. Antioch, and Jc- 
 rufalem. If to tlicfc we add the whole of the Ruflian 
 empire in Europe, great part of Siberia in Alia, Al- 
 tracan, Cafan, and Georgia — it will be evident that the 
 Greek church has a wider extent of territory than the 
 Latin, with all the branches which have fprung from 
 it ; and that it is with great impropriety that the church 
 of Rome is called by her members the catholic or uni-- 
 verfal church. That in thefe widely diilant countries 
 the profeifors of Chriitianity are agreed in every minute 
 article of belief, it would l)e rafli to alTert ; but there is 
 certainly fuch an agreement among them with relpecl 
 both to faith and to difcipliue, that they mutually hold 
 communion with each other, and are in fadl but one 
 chuich. 
 
 As the Greek church has no public or eftablifhed 
 articles, like thole of the churches of England and 
 Scotland, we can collect what is its dodrine only from 
 its creeds, from the councils whofe decrees it receives (b), 
 from the different offices in i's liturgies, and from the 
 catechifms which it authorifes to be taught. " The 
 dodrine of the Trinity, and the articles of the Niceiie 
 arid Athanafian creeds, are received by the Greeks in 
 common witli other Chrillians. In one particular, in- 
 deed, they differ from the other churches of Europe, 
 whether Romilh or reformed. They believe that the 
 Holy Spirit proceeds from the father only, and not 
 from the Father and the Son ; and in defence of this 
 opinion ihey appeal to eccle!>alticai hiftory, the ads of 
 councils, the writings of the fathers, ancient maim- 
 fcripts, and efptcially to a copy of the creed of Con- 
 ftantinople, engraven on'two tables of filver, and hung 
 up in the church of St Peter at Rome by order of Eeo 
 III. Of the Nicene or Conllantiuopolitan creed, there- 
 fore, as it is received by them, the eighth article tuns 
 in thefe words, ' I believe in the Holy Ghoft, the 
 Lord and Giver of life, who proceedeth from the Fa- 
 ^ Dalh- THER, and with the Father and the Son together is 
 tojv'j C""- worihipped and glorified :' And the correfponding ar- 
 fanim.pU, .^j j- ^^^ AthamifiaQ ci-fed is of courfe, «' The Holy 
 
 jHnctent and ^ , ^ , „ - 1 j ^ j 
 
 Modirn, Ghoftisof the Father, neither made, nor created, nor 
 and Kings begotten, but proceeding -j-." 
 
 Jtitci andCi- Tfioiiah the bilfiops and clergy of the Greek church 
 ••""""'"■^' abhor th'e ufe of images, which they pretend to be one 
 It admits of caufe of their feparation from the fee of Rome, they ad- 
 pSaures mit into their churches the pidures of famts to inilruft, 
 they fay, th.e ignorant, and to animate the devotion of 
 others.' I'his pradice they conhder as by no means 
 
 The faith 
 of that 
 church. 
 
 bur not of 
 
 graven 
 
 image;. 
 
 contrary to the fecond commandment of the decalogue, Ohin-rh. 
 which, according to them, prohibits only the worlhip- ' v~~ 
 ping of fuch idols as the Gentiles believed to be gods ; 
 whereas their pidures, being ufcd merely as remembran- 
 cers of Chrill and the faints, have written on each of 
 them the name of the perfon whom it \i meant to re- 
 prefent. Dr King aflures us that the more learned of 
 the Ruffian clergy would willingly allow no reprelenta- 
 tion whatever of God the Father ; and that, during the 
 reign of Peter tlie Great, the fynod not only cenlured 
 the ufe of fuch pidures in churches, but petitioned the 
 emperor that they might be everywhere taken down. 
 Peter, however, though he fully -concurred in opinion 
 with the fynod, thought this a meafure for which the 
 minds of his fnbjeds were not ripe, and dreaded, that 
 if carried into execution it would occafion a general in- 
 furredion. Such pidures, therefore, though not more 
 impious than abfurd, aie rtill in ufe; and in many 
 churches, as well ancient as modern, the iigure of Da- 
 niel's Atic'ient of Diiys, together with that of Chrill and 
 a dove, are paiiited in one group to lignify the Holy 
 Trinity. Nay, when our author was in St Peterfburg, 
 not thirty years ago, there was in the ch\nch of St Ni- 
 cholas the pidure of an old man holding a globe, and 
 furrounded with angels, on which God the Father 
 was intcribed ; and we have not heard that the pidure 
 has been fince taken down. 
 
 In the Greek as well as in the Roman church, the i, vocatioi 
 invocation of faints is pra6f ifed, but they are not invo- of faints, 
 ked in either as deities, but merely as interceffors with 
 the Supreme God, " it being more modeft (fay the 
 Greeks), as well as more available, to apply to them to 
 intercede with God, than to addrels ourfelves immedi- 
 ately to the Ahnighty." Plauhble as this reafoning 
 may at firft fight appear, it afcribcs to the faints the di- 
 vine attribute of ubiquity, and is likewife in divtd con- 
 tradidion to the dotlrine of St Paul, who hath taught 
 us, that as " there is one God, fo there is but one me- 
 diator between God and man, the man Chrill Jel'us." j 
 
 The Greek church, at the celebration of the Lord's P.- ayers for 
 Supper, commemorates the faithful departed, and even "'' dead, 
 prays. for the remiflion of their lins ; but flie allows not 
 of purgatory, nor pretends to .determine dogmatically 
 concerning the Hale or condition of depaited fouls. 
 She mull, however, believe that no final judgment is 
 paffed upon the great body of mankind (c) till the 
 conlummatiou of all things, otherwile fuch prayer* 
 could not be oflered without abfurdity ; and in this part 
 of her dodrine (lie is certainly countenanced by all the 
 writeis of the primitive church, if not by fome paffages 
 of the facred fcriptures *. The pradice of praying for.^ Math. 
 the dead is loudly condemned in every Protellaut coun-xxv. 19, 20, 
 try, and yet there is noChrillian wlio does ni.it in efted — 31 — 34- 
 
 pray ^ '^™- >• ^^' 
 ____^___— ^___^-_ iv. 8. 
 
 (a) King's Riles and Ceremonies of the Greek CAaz-cA— Bruce's Travels to the Source of the Nile — and Lobo's 
 
 Voyage to Ah\[finta. . , , . . . , 'm r 1 
 
 Tb) in the'Greek church i^t^iw general councils are -received, and nine provincial ones. i lie leven general 
 councils are, i. The council of Nice, held in the year 325, uilder Conftantiue. 2. The firft council of Conftan- 
 tinople, held A. U. 381, under Theodofius the Great. 3. The council of Ephefua, A. D. 431, in the reign 
 of The'odolius iVIinor. 4. The council of Calcedon, A. D. 4JI, in the reign of'Marcian. 5. The fecond coun- 
 cil ofConllantinople, A. D. 5^3, in the reign of Juftinian. 6. The third council of Conllantinople in Trull, 
 A. D. 680, in the reign of Co'nllantine Pagonatui. 7. The fecond council of Nice, A. D. 787. 
 
 Vc) We fay the great body of mankind, becaufe fhe doubtlcfs believes that Enoch, Ellas, and thoffi faints who 
 rofe with our'Saviuur, have been already judged, and now enjoy their rewvi in heaven.
 
 C H U 
 
 [ 43r ] 
 
 C H U 
 
 Chnrvh. 
 
 Grants no 
 jiidulgeB- 
 cics. 
 
 Predeftina- 
 tion. 
 
 Seven fa- 
 (ramciits. 
 
 9 
 Daily fer- 
 vice of the 
 church, 
 
 pray for Iiis departed friends. This may appear a pa- 
 ' radox, but it is an obvious and a certain truth ; tor 
 where is the man who believes in a general judgment, 
 and does not nulfh that his deccafed wife, or parent, or 
 child, or friend, " may find mercy of the Lord in that 
 day ?" Such a wifli is the eflence of a prayer ; which 
 confills not of the founds in which our fentiments/are 
 cloathed, but in the afpivations of a dtvout heart. 
 
 Supererogation, with its confequent indulgencies and 
 difpcnfations, which were once fo profitable, and after- 
 wards fo fatal to the infcrelts of the court of Rome, are 
 utterly difnllowed in the Greek church, which likewilc 
 lays no claim to the charaitcr of iniallibility. She is 
 indeed, like fome othtr churches, very inconfillent on 
 this lail topic ; for wliilit ibe pretends not to an abfo- 
 lute exemption from error, her clergy fctm to coulidcr 
 their own particular mode of worlhip as that which 
 alone is acceptable to Goil. 
 
 Predellination is a dogma of the Greek church, and 
 a very prevailing opinion amongd the people (jt RiilHa; 
 " and 1 mult do the jullice (fays Dr King) to thole 
 who have written upon it, efpecially the lattll autliors 
 of that country, to fay that they have treated it, as de- 
 pending on the attribute of prefcience in the divine na- 
 ture, with a much better kind of logic than that with 
 which fuch points are generally difculTcd." As our 
 author has not given us the realoning of the Rnflian 
 doctors on this difficult fubjcfl, we cannot lia/ard any 
 opinion of our own on the foundnefs of their logic ; 
 but from the ftate of fcience in that vail empire, as it 
 was reprefented to us by an abler judge than he, we 
 doubt of its being entitled to the praife which he be- 
 llows on it. (See Russia, n" \o^. Ericjcl.) 
 
 In the Greek church there are {evenfacrametits; or, as 
 they are there termed, myjieries, viz. haptifm ; the chr/fm, 
 or baptifmal undtion ; the euchanj} ; canfejfion ; ordina- 
 tion ; marriage; and the myftcry of the holy oil, or eii- 
 cheliiion. By the Greeks a myllery is delined to be 
 " a ceremony or aft appointed by God, in which God 
 givetli or iignifieth his grace ; and ot the feventh which 
 they celebrate, four are to be received by all Chrillians, 
 viz. baplifm, the baptifmal iitiSwn, the cucharij], and con- 
 fejjion. Of thefe, baplifm and the euchariji are deemed 
 the ct.ief ; and of the other three, none, not even the 
 euchclaion, is confidertd as obligatory upon all. 
 
 With refpttl to baptifm,we know not that they hold 
 any peculiar opinions. They confider it indeed as fo 
 abfolutely neceflary to falvation, that in cafes of extre- 
 mity, when a pried or deacon cannot be had, it may be 
 adminiftered by a midwife or any other perfon, and is 
 not to be repeated on any occafion wha-tever. Li this 
 opinion, as well as in the praftice founded on it, they 
 are in perfect harmony with the church of Rome, 
 which, as every perfon knows, has for many ages al- 
 lowed the validity of laybaptifm in cafes of necefnty. 
 The Portuguele Jefuits, who in the laft century vifited 
 AbylTmia in the capacity of miflionaries, have maintain- 
 ed that, once every year, all grown people are in that 
 country baptifed : but Mr Bruce has (liewn, by the 
 moft incontrovertible evidence, that this was a mere 
 fiftion, invented to throw odium upon what the church 
 of Rome calls the eaftern chifm, and abhors perhaps 
 more than pagan ifm it felt. 
 
 The daily fervice of the Qreek church is fo long and 
 fo complicated, that it is impoffible for us to give an 
 
 adequado account of it without fwelling this article far Church, 
 beyond its due proportion. Of this the reader will be " 
 
 convinced, when he is informed that the fcveral books [jj,jjj.^[g 
 containing the church fervice for all the days in the nJ tcJioui. 
 year, amount to more than twenty volumes in folio, 
 belides one large volume called the regulation, which 
 contains the directions how the rell are to be ufed. 
 
 The four golpcls make one volume by themfelves ; 
 and whenever tlie golpel is read in any fervice, the dea- 
 con exclaims ; " \Vifdoii'., Hand up. Let us hear the 
 holy golpel." The prieil then faith, "The IcfTon from 
 the gofpel according to St Maiihew, i.t Mark, &c." 
 The deacon fays again, " Let \is itand." The choir, 
 at the beginning and end of llie gofpel, always fays, 
 " Glory be to thee, O Lord, glory be to thee." From 
 tlic old tellameiit and the epilUes extracts only arc uled 
 in the fervice ; and when they are to be read, the dea- 
 con calld out, " Attend." 
 
 The fervice of this church as it now ftands, and was 
 at fird drawn up in writing, is calculated for the ufe of 
 monalleries ; and when it was afterwards applied to pa- 
 rochial chuiches, many of the offices or forms, which 
 were coinpoftd for different hours of the day and night, 
 were uled as one fervice, without the flighttil altera- 
 tion being made ti.- avoid repetitions. So.^lething of 
 this kind has taken place in the church of England, 
 where the matins, tlic litany, and the communion, 
 which were formerly three ('.illinft fci-vices, read at dif- 
 ferent times of the day, are now run into one fervice ; 
 which by thofe not accullomed to it is therefore deem- 
 ed long, as well as deformed by needlefs repetitions,. 
 
 The fervice of every day, whether it has a vigil or g^ginj j^ 
 not, begins in the evening of what we would call the the even* 
 preceding day, as among the Jews; and for the fame '"g« 
 reafon, becaufe it is faid in the Mofaic account of the 
 creation, that "the eve:^ing and the morning were the 
 firft day." The fcveral feivices, according to the ori. 
 ginal or monkiili inllitulicn, are, I. The vefpers, which 
 ufed to be ctk-bratcd ft little before fun-ftt ; 2. The af- 
 ter-vefpers, anfvvericg to the coniplitorium of the Latia 
 church, which ufed to be celebrated after the monks 
 had fupped, and before they went to bed ; 3. The me- 
 foityeSicon, or midnight fervice ; 4. The matins at break 
 of day, anfwering to the laadcs of the Romitk church ; 
 5. 'i^he. firjl hour of prayer, or prima, at fun-rife; 6. 
 The third-hour, or lertia, at the third hour ot the day ; 
 ^. 'Y\\tftxth hour, or fexta, at noon ; 8. The ninth hour, 
 or nana, in the atternoon at the ninth hour of the day. 
 Thefe are called the canonical hours ; but it is to be 
 obferved, that the ajter-vcfpcrs. were not added till a 
 late period, before which the reafon afiigned for the 
 number of fervices being (even, was, that David faith, 
 " Seven times a-day will I praife thee." When all the 
 pfalms and hymns were fung, thcie daily fervices could 
 not pofubly have been performed in lefb than twelve or 
 fourteen hoars. In the church of RulTia, and probably in 
 other branches of the Greek church, there are at prefent 
 but three fervices in the day: the ninth hour, the vefperj, 
 and the after-vefpers making one ; the mfonye^icon, the 
 matins, and prima, another ; and the third and Jiath 
 hour, with the communion, the lail. In all the fervices, 
 except the communion, prayers and praifes are offered 
 to fome faint ; and to the Virgin Mary, almoll as often 
 as to God ; and in fome of the fervices, after every 
 fiiort prayer uttered by the. deacon or the prieft, the 
 
 choir
 
 C'hnrth. 
 
 Mode of 
 
 a.lminiller- 
 jiigbaftifni 
 
 C H U [43 
 
 clioir chaunts " Lord have mercy upon us," thirty, 
 forty, or fifiy times, lixccflivrly. 
 
 Tlumgh tlic number of forvices is the fame every 
 dav, the fervices thcmiclves are conftantly varying in 
 fome pavticiiLir or other, as there is not a day which, 
 in the Greek church, is not cither a fail or a fellival. 
 Befuk's the f.ints, whofe feftivals are marked in the ca- 
 Itndar, and who are fo very nunerous that there are m6re 
 than one for every day in the year, there are other faints 
 and feltivals, to which fome portion of the fervice for 
 evei-y day of the week is appropriated. Thus, Sunday 
 js dedi.Mted to the refurreftion: Monday, to the angels; 
 Tuefday, to St John Daptill; Wcdnei'Ja) , to the Virgin 
 !ind the crofs; Thurfday, to the apolUes; Friday, to the 
 pafllon of Chrifl ; and Saturday, to the laints and mar- 
 tyrs. For thefe days there are particular hymns and 
 fervices, in two volumes folio, to which there is a fup- 
 plemcnt containing icrvices for the faints and feftivals, 
 as they occur in the calendar thro\ighout the year. 
 Thefe different fervices are mixed together, and adjuft- 
 ed by the dirertions contained in the book of regulation ; 
 and it is the difiiculty of this adjullment which makes the 
 public worfiiip of the Greek church fo very intricate, 
 that, as was faid of the fervice of the Engliili church be- 
 fore the ReformatloH, " there is more bufmcfs to find out 
 what (hould be read, than to read it when found out." 
 
 We have obferved, that the Greeks have no peculiar 
 opinions rcfpefting the nature of baptifm ; but the rites 
 and ceremonies with which that ordinance is admini- 
 ftercd will appear to our unlearned readers very extra- 
 ordinary. On the day that a woman is delivered, the 
 prieft goes to the houfe, and ufes a form of prayer for 
 her and for the child. On the eighth day the child 
 fliould be regularly carried to the church, where the 
 prieft having ligned it with the fign of the crofs on the 
 forehead, on the mouth, and on the breaft, offers up 
 for it a prayer, in which he firft gives it a name, com- 
 monly the name of the faint for that day in the calen- 
 dar ; he then takes it from the midwife, and Handing 
 before the pifture of the blclTed Virgin, he makes the 
 fign of the crofs vTith the infant, uttering a kind of 
 liymn in honour of the Virgin and of Simeon, who 
 held in his bofom the Saviour of our fouls. He then 
 difniifics the company with an exhortation not to delay 
 the baptifmg of the infant, (hould it appear in danger 
 of death before the regular time for its baptifm. 
 
 On the fortieth day after her delivery, the mother 
 fliould attend the church to be purified, and carry the 
 child again to be pvefented, the perfon who is to be 
 fponfor being prefent. Upon their arrival at the church 
 door, the prieft utters fome pious exclamations ; and 
 then, the mother holding the child in her arms and 
 bowing down her head, he makes the fign of the crofs 
 upon her and the child, and laying his hand upon its 
 head, he prays that the woman may be cleanfed from 
 every fin and from every defilement, and that the child 
 rnay be fandified and endued with undcrftanding, with 
 wifdom, and with gentlencfs of manners. He then 
 figns it again, and again prays for it, for its parents, 
 and for its fponfur ; after which, if it has been privately 
 baptifed, he takes it in his arms, and makes with it the 
 
 2 ] C H U 
 
 fign of the crofs before the door of the church, fayinjj, Churen. 
 " N. N. the lervant of Gud, enters into the churcli, in *""->—« 
 the name of tiie Father, and of the Son, and of the 
 Holy Ghoft, now and for ever, even unto ages of ages. 
 .A.men." H." then carries tlie child into the church,- 
 faying, "he Ihttll go into thine h.oufe, and Ihall worfhip 
 toward thy hcrly temple ;" and advancing into the mid- 
 dle of the church, he fays, " In the midft of thy church 
 fliall lie praife thee." I'hen, if the child be a boy, he 
 carries hi:n within the rails of the altar ; but if a girl, 
 only to the door, and fays " Nunc dimitlis (d);" after 
 which he delivers it to the fpoulor, who makes three 
 reverences, and retires. 
 
 This is called the prefentation of the child in the 
 temple, and can only he performed after it has been 
 baptized. In the detail we have given, we have fnppo- 
 fed that it was baptized privately before the purifica- 
 tion of the mother, which is now indeed conimoidy the 
 cafe. Such baptifm, hcvvever, is not regular, being al- 
 lowed only in cafes of neceffity ; and when it has not 
 taken place, the mother and child are dilniiffed as foon 
 as {he is purified, and return at fome other time, not 
 fixed, in order that the child may be publicly baptized. 
 
 Previous to baptifm, the child, though not two 
 months old, muft be folemnly initiated into the church 
 as a catechumen (See Catechumen, EncycL) By 
 thofe whofe religion is a reafonable fervice, fuch initia- 
 tion of an infant will be confidered as a very idle cere- 
 mony; and the rites with which it is performed are not 
 well calculated to give it even a fictitious uiiportance. 
 At the door of the church the prieil unties the girdle 
 of the infant ; takes off all his clothes but one loole gai"- 
 ment ; turns him towards the eall, with his head unco- 
 vered, his feet naked, and his hands held down ; blows 
 thrice in his face ; figns him thrice with the fign of the 
 crofs on the forehead and on the breaft, and lays his 
 hand upon his head, praying that his " amietit error 
 may be put away from him ; that his heart may be fil- 
 led with faith, hope, and charity ; and that he may 
 walk in the ways of God's commandments." The 
 prieft then four times cxorclfes the infant, commanding 
 Satan, in the firft exorcifm, to " tremble, depart, and 
 flee from Chrift's creature, nor dare to return again, 
 nor dare to lurk concealed within him, or to meet him, 
 or to meditate againft him, either in the evening or the 
 morning, at midnight or at noon-day." In the lafl 
 exorcifm he blows thrice upon the child's mouth, upon 
 his forehead, and upon his breaft ; faying, each time, 
 •' Drive away from him every evil and unclean Ipirit 
 that lurks in him, and hath made itfelf a neft in his 
 heart." The child is now becom.e a catechumen, and, 
 being turned t*) the weft, uncovered, without ihoes, and 
 his hands lifted up, the prieft repeatedly afks him if he 
 renounces and has renounced the Devil and all his works ? 
 and receiving from the fponfor the proper anfwer, he 
 fays, " Blow and fpit upon him ;" and having blown 
 and fpit upon the catechumen, he turns him to the eaft, 
 and holding down his hands, afks him repeatedly if he 
 be joined to Chrift, and if he believes in him ? The ca- 
 techumen or his fponfor replies to each queftion, that 
 he is, and has been, joined to Chrift ; and as a proof of 
 
 his 
 
 (0) We quote the words of Dr King. 
 Greek tiymns have Latin defignations ? 
 
 I3 it pofllbk that in the Greek church Latin hymn« are ufed, or that
 
 C H U t 433 3 C H U 
 
 'ch. his faith he repeats, from beginning to end, the NIcene end, the 3:d Pfalm; he then puts upon the baptized Church, 
 
 /~*~' cived. After a repetition of the formerly repeated perfoii a white garment; faying, " N the fervaiit o{^~~~y~~— 
 
 quellions and anfwers, the prieft prays that the cate- God is clothed with the garment of rightcoufnefs, in 
 
 chumen may be called to God's holy fantlification, and the name of the Father, and of the Son, and of the 
 
 receive the g'ace of God's holy baptifm. Holy Gholl, now and for ever, even unto ages of ages 
 
 Baptifm may be celebrated immediately after the (e)." He then prays that lie may be delivered from 
 candidate has been made a catechumen, or on any fub- the evil one, and all his inlidious fnares ; that he may 
 fcqnent day at no great dillance. In the lirft part of be confirmeil in the true faith; and that he may pre- 
 the form there is not much that is fiiigiilar, or with ferve iiis fonl in purity and rightcoufnefs: and proceeds 
 which every Icholar is not acquainted. After praying immediately to anoint him with the ffuiy Chrlfm. ij 
 that the water may be fandlihed, in terms differing little This chrifm is a very diii'erent thing from the oilThebap. 
 from thofe which are ufed in the moll refpeAable Pro- with which he was anointed previous to baptifm, and •''^","' 
 teftant churches, the priell dips his fingers in it, figns which was ufed in the confecration of the baptifmal 
 it thrice with the (ign of the crofs ; and then blowing water. It can be prepared only by a bifhop, and only 
 upon it, fays three times, " Let every adverfe power be on one day in the year, 'uiz,. Thurfday in Fafiion-wtek; 
 confounded under the fign of the crofs." He then fo- and as the anointing with it is fubllituted in place of 
 IcMinly exorcifes it of the dsmon of darknefs and all the apoftolical rite of laying on hands, called confirma- 
 evil fpirits; and prays, that " the pcrfon to be haptifed tlon in the wellern churches, great quantities of it are 
 therein may put off the old man, which is corrupt after of courfe prepared at once, and dillributed through the 
 the lull of fraud, and may put on the new man after different churches of each diocefe. The chriim confilLs 
 the image of Him that made him. After this, he of the following ingredients, which in different prupor- 
 blows thrice into a veffel of oil of olives held by the tions are all boiled together, and afterwards foleuuiiy 
 deacon, figns it thrice with the fign of the crofs ; and confecrated by the bilhop : Fine oil (we fuppofe of 
 prays fervently, that it may " become to thofe who are olives), white wine, ftyrax calamita(F), palm dew, 
 anointed with faith, and are partakers thereof, the unc- rofe-flowers, black palm-gum, Bahl-g\im, marjoram, 
 tion of incorruption, the armour of rightcoufnefs, the thick and thin oil of nutmegs in vei y difiercnt quanti- 
 renewing of foul and body, for turning aiide all niachi- ties, oil of cinnamon, oil of cloves, lignum Rhodii, oil 
 nations of the devil, and for deliverance from all evil." of oranges, oil of marjoram, oil of laveiidar, oil of rofe- 
 He then lings allelujah thrice with the people, and reary, effence of rofemary, cedar, blsck balfdin ol Pe- 
 pours the oil on the top of the water ; and making rn, fandarac, whitcft inaftic, and Venice turpentine. 
 three crofTes with it, fays aloud, " Bleffed be God, who With this holy miKture the baptized perfon is anointed, 
 enlightcneth and fandifieth every man that cometh in- the prieft making with it the lign of the crofs on his 
 to the world, now and forever, even unto ages of ages." forehead, on his eyes, his n<,llrils, his mouth, bo h ears, 
 The perfon to be baptized is then prefented ; and the his bread, his hands, and his feet; faying at each part, 
 prieft, taking fome of the oil with two fingers, and ma- " The feal of the gift of the Holy Gholl. Amen." 
 king the lign of the crofs on his forehead, on his breaft, Then with the fponfor and the child he goes thrice 
 and bctviixt his ftioulders, fays, " N the fervant of God round the font, turning from the right to the left; the 
 is anointed with the oil of gladnefs, in the name of the choir, in the mean time, finging, " As many ot you as 
 Father, and of the Son, and of the Holy Gholl, now are baptized unto Chrift have put on Chrift, allelujah." 
 end forever, even unto ages of ages. Amen." He then Seven days after this ceremony is pertornied, the 
 figns him on the breaft and the middle of the back, child is again brought to the church ; when the prieft, 
 faying, " For the healing of his foul and body ;" then after praying for him, unties his girdle and linen clothes, 
 on the ears, faying, " For hearing the faith ;" then wafhes him with clean water, and, fprinkling him, fays, 
 on the palms of the hands, faying, " Thy hands have " Thou hall been juftified, enlightened, ianttified in 
 made me and faftiioned me ;" then on the feet, " That the name of our I^ord Jefus Chrift, and with the Spirit 
 he may walk in the way of thy commandments." Af- of our God." Then taking a new fponge moiftened 
 ter the whole body is thus anointed, the prieft baptizes with water, he wafhes his face, breaft, &c.; laying, 
 him, ufing the trine immerfion ; which is unqueftionably " Thou haft been baptized, enlightened, anointed, ianc- 
 the moft primitive manner. He takes the child in his tified, waftied, in the name of the Father, and of the Son, 
 arms, and holding him upright with his face towards the and of the Holy Ghoft, now and for ever, even unto ages 
 eaft, he fays, " N the fervant of God is baptized [dip- of ages. Amen." 14 
 ping him the Jirjl time), in the name of the Father, A- Tl»e laft ceremony appended to baptifm is that of The ton- 
 men ; in the name of the -Son {^dipping him again). A- the tonfure, or Ihaving the head of the child in thefure. 
 men ; and of the Holy Ghoft [dipping him the third form of the crofs. At what time this rite crept into 
 nW), Amen, now and for ever, even unto ages of ages, the church it would not be eafy to difcover. Some 
 Amen." After the baptifm, the prieft wipes his hands, think it received its origin from the religious ceremo- 
 and with the people fings thrice, from beginning to nies of the Heathen, who certainly rounded the corners 
 
 SUPPL.VOL. I. Partn. 3 I of 
 
 (e) The reader will perceive, that many of thefe rites and ceremonies are common to the Greek church and 
 the church of Rome in the celebration of the facrament of baptifm. 
 
 (f) We quote the words of Dr King, taking it for granted that our readers will pardon our not giving our- 
 felves much trouble to difcover, on the prefent occafion, what particular fpecies or variety of the ftorax he mean* 
 by this defignation. See Styrax, Encycl.
 
 C H U [ 434 ] 
 
 Chorch. of their heads, and marred their beards, at a very early clare his ge: 
 ■"^ ' period, in honour of their idols (See Theology, n"^ 
 I 55. Encyc!,) ; and fome pious, but foolifh Chrilliaiis, 
 efteemed it highly commendable to transfer to the true 
 God that vvorthip, in a different form, which had been 
 rendered by their anceftors to falfe deities. Others 
 will ^lave the tonfure to typily the dedication of the 
 perfon to the fervice of God ; the cutting off of the 
 hair being always confidered as a mark of fervitude. 
 Be thefe conjeftures as they may, the prieft, after the 
 child is baptized, offers up for him feveral prayers, all 
 
 alluding to the rite to be performed; and then cuts his 
 hair crofswife, faying, " N the fervant of God is (horn, 
 in the name of the Father, and of the Son, and of the 
 Holy Ghoft, now and for ever, even unto ages- of ages. 
 Amen." 
 
 We have given a full account of the manner in which 
 the facrament of baptifm is celebrated among the 
 Greeks, that the reader may have fome notion of the 
 childiili fuperftition of that church, with which certain 
 zealous Proteftants in England were very defirous, at 
 the beginning of this century, to form a union. There 
 is no occafion for dwelling fo long upon their other of- 
 The Greeks fices. For the celebration of the Lord's Supper they 
 have three },ave three liturgies that are occafionally ufed, viz. that 
 of St Chryfoflom, which Is in ordinary daily ufe ; that 
 of St Bafil, ufed on particular days ; and that of the 
 pn-fanSiJied, as it is called, which is ufed on the Wed- 
 nefdays and Fridays during the great fall before Eafter. 
 Between the liturgies of St Chryfoifom and St Bafil 
 there is no effentinl difference; and the office of the pre- 
 fanclified is merely a form of difpenfmg the communion 
 with elements which had been confecrated on the pre- 
 
 if 
 
 commu 
 
 rion-offi- 
 ces. 
 
 C H U 
 
 neration ?" He then thrufts the fpear o- Church, 
 bliqucly into the loaf, lifting it up, and faying, " For '~~*v •* 
 his life was taken away from the earth," After this 
 he lays down the loaf, and cutti.ig it crofswife, fays, 
 " The Lamb of God, which taketh away the fins of 
 the world, is flain for the life and ialvation of the world." 
 All this, and more to the fame purpole, is uiiqueftion- 
 ably modern; but we have no doubt but that the prieft 
 ufes the words of Chryfoflom himfelf, when, in the 
 confccration of the elements, he fays, " We offer untOTheconft. 
 thee this reafonable, this unbloody facrifice ; and wecrationof 
 implore, we pray thee, we humbly befeech thee, to fend '''^ '''- 
 down the Holy Spirit upon us, and thofe oblations"**"'*' 
 prcfented unto thee ; and make this bread the precious 
 body of thy Chrift ; and that which is in this cup the 
 precious blood of thy Chrift, changing them by thy 
 Holy Spirit." 
 
 Dr King obferves, that this invocation of the Holy 
 Spirit upon the elements, which in the eaftern church 
 is always ufed after the wends of Chrift, " This is my 
 body, this is my blood, &c." is incontiftent with the 
 Popifh doftrine of tranfubllantiation : and he is un- 
 doubtedly right ; for the church of Rome teaches, that 
 the chajige is made about the middle of the mafs, when 
 the prieft, taking into his hand iirft the bread and then 
 the wine, pronounces over each feparately the facred ' 
 words of confccration j /. e. the words of Chrift. " It 
 is the office of the prieft, in this and in all other facra- 
 nients (fays a dignitary of that church), only to per- 
 form the outward fenfible part ; but the inward invifible 
 effeft is the work of the great God, who accordingly 
 changes the fubflance of the bread and wine into the 
 body and blood of Chrift the very inftant that the fa- 
 
 ceding Sunday. We would gladly infert the liturgy of cred words of confccration are pronounced by the prieft 
 
 St Chryfoftoni, or at leaft fuch an abftraft of it as we 
 have given of the form of adminiftering baptifm ; but 
 as our limits will not permit us to do fo, we muft refer 
 fuch of our readers as have any curiofity refpefting 
 fubjeCls of this nature to Dr King's Rites and Ceremo- 
 nies of the Greek Church. 
 
 It is proper, however, to obferve here, that many 
 fUperftitious ceremonies have been added to the fervice 
 fince the age of St Chryfoflom, and that no man can 
 compare his genuine works with the liturgy which now 
 goes under his name, and entertain the fmalleft doubt 
 jg but that the latter has been greatly, though gradually, 
 Strange ce- corrupted. Li the offertory there Is a ftrange ceremo- 
 remonyat ny, called the Jlaying of the Holy Lamb, when the prieft, 
 taking into his left hand one of the five loaves which 
 are to be confecrated, thrufts a fpear into the right fide 
 of it ; faying, " He was led as a lamb to the flaugh- 
 ter ;" then into the left iide, adding, " And as a blame- 
 lefs lamb before his fhearers Is dumb, fo he openeth not 
 his mouth :" then into the upper part of the loaf; fay- 
 ing, " In his humiliation his judgment was taken away :" 
 and into the lower part ; adding, " And who fliall de- 
 
 the offer, 
 tory, 
 
 over them." But if this be fo, it would be impious, 
 and we believe that by the church of Rome it is deem- 
 ed impious, to pray afterwards, that God would fend 
 down his Holy Spirit to change into the body and 
 blood of Chrift elements which he had already changed 
 into that body and blood, in confequence of the prieft's 
 pronouncing over them the all-powerful words of Chrift. 
 Yet is it certain, that in the prefent Greek church tran- 
 fubllantiation is as much an article of faith as in the 
 church of Rome ; for now every bifhop at his confe- 
 cration declares, in the moil lolemn manner, that he be- 18 
 lieves and " underftands that the tranfubftantiation ofTranfuh- 
 the body and blood of Chrift, in the holy fupper, is ef.ft^""ation. 
 fedled by the influence and operation of the Holy 
 Ghoft, when the bifhop or prieft invokes God the Fa- 
 ther in thefe words, and make thit bread the precious 
 body of thy Chrijl, &c." This is indeed a different ac- 
 count from that of the Latin church of the time at 
 which this portentous change Is wrought; but fuch dif- 
 ference is a matter of very little importance (g). \T 
 the change itfelf be admitted, the confequence muft be 
 the fame, whether it be fuppofed to take place when 
 
 the 
 
 (g) Mr Bruce feems to doubt whether tranfubftantiation be the doftrlne of the Abyflinlan church, and relates 
 a converfation which he had on the fubjeft with a prieft ; who folemnly affirmed, that he never believed in the 
 •converfion of the fubftance of the bread and wine into the fubftance of our Saviour's body and blood. It muft 
 be remembered, however, that the prieft had at the time a powerful reafon for wlfhing that doctrine not to be 
 true. The Jefults uniformly atteft, that the Abyffinians believe in the real prefence ; though it muft not be 
 forgotten that Ludolf was of a different opinion, and that no maa hadftudied the language of Abyfiinla more 
 fuccefrfully than he.
 
 C H U 
 
 Ofiu^fh- tho pritfV pronounces the words of iiiditution, or aftcr 
 ^■^-~\ he lias invoked tlie dcfcent of the Holy Glioll ; in ei- 
 ther calc it leads to idolatry. It may be proper to mcn- 
 tiim, that in the Greek church it is deemed effential to 
 the validity of this holy facrament, that a little warm 
 water be mixed with the wine ; that the napkin, which 
 is fpread over the holy table, and anfvvers to the cor- 
 ^9. parale of the church of Rome, be confecrated by a bi- 
 rhe laity ^^ ^^^ ^)^^^ -^^ \\^msi fome fmall particles of the re- 
 ;omm"m ,. ' ^ • i • i i i t i 
 
 ■atcinbuthhques 01 a martyr mixed in the web, otnerwile the tu- 
 
 cinds. charift cannot be adminillered. In this church chil- 
 
 dren may receive the communion immediately after bap- 
 tifm ; and the lay communicants, of whatever age, re- 
 ceive both the elements together, the bread being fop- 
 ped in the cup : The clergy receive them feparately. 
 
 We have obferved, that one of the feven myjlerics or 
 facraments of the Greek church is confejfion ; but among 
 the Greeks it is a much more ratiiMial and edifying 
 fcrvice than in the church of Rome. In the (ireek 
 church the end of confeffion is the amendment of the 
 penitent ; in the church of Rome it is to magnify the 
 glory of the prieil. In the former church, the confef- 
 fors pretend only to abate or remit the penance, decla- 
 ring the pardon from God alone ; in the latter, they 
 take upon them to forgive the fin itfelf. The Greek 
 church prefcribes confeffion four times in the year to 
 all her members ; but the laity, for the moft pait, con- 
 fefs only once a year previous to receiving the holy com- 
 munion ; and to this they are in Ruffia obliged by the 
 laws of the empire. 
 
 The ceremonies with which matrimony is performed 
 in the Greek church confift of three diftindl offices, 
 formerly celebrated at different times, after certain in- 
 
 [ 435 ] 
 
 C H U 
 
 nage, is called the office o( miUiiiiiania! coronati.m, fi-om P'>ii''fh- 
 a lingular circuiVitlancc in it, that of rroivning the par- v 
 ties. This is done in token of the triumph of conti- 
 nence ; and therefore it has, in fome places, been omit- 
 ted at fecond marriages. l'"ormerly thele crowns wei'e 
 garlands made of flowers or flirubs ; but now there are 
 kept, in moil churcheB, crowns of filver or fon\e other 
 metal for the celebration of matrimony. At the put- 
 ting of them on, the pried fays, " N, the fervant of 
 God, is crowned for the handmaid of God ; and " N, 
 handmaid of God, is crowned for the fervant of God, 
 \n the name of the Father, and of the Son, and of the 
 Holy Ghofl ;" adding thrice, " O Lord our God, 
 crown them with glory and honour." 
 
 The third ceremony is that of dilTolving the crowns 
 on the eighth day ; after which the bride is conduced 
 to the bridegroom's houfe, immediately to enter on the 
 cares of his family. 
 
 With refpeft to difcipline and government, the Greek Regular 
 church bears a flriking refemblance to that of Rome, atiri fccular 
 In both there is the lame divilion of the clergy intoi-lenjy. 
 regular and fecular ; the fame fpiritual jurifdi(;tion of 
 bifliops and their officials, and the fame diilindion of 
 ranks and offices. lu fome points the difcipline of thi? 
 Greeks differs from that of the Romans. All orders 
 of fecular clergy in the Greek church inferior to biHiops 
 are permitted to marry ; but celibacy, and the alTump- 
 tion of the monallic habits, are indilpenfably requifitc 
 in tliofe who are candidates for the mitre. The regu- 
 lar clergy, fays Mr Dallaway, are generally men of a 
 certain education ; whereas the feculars are of the 
 meaner fort, and illiterate in the extreme. ,, 
 
 In the Greek church there are five orders of clergy Five orJers 
 
 tervals, which now make but one fervice. Firlf, there promoted by the impofition of hands ; but it does iiof' ''"^'gy- 
 
 was a folemn fervice, when the parties betrothed them- 
 felves to each oilier, by giving and receiving rings or 
 other prefents, a<i pledges of their mutual fidelity and at- 
 tachment. The ancient ufage was for the man to re- 
 ceive a gold ring and the woman a filver one, which 
 is Hill alluded to in the rubric, though, in the preftnt 
 praftice, the rings are generally both of gold. At this 
 time the dowry was paid, and certain obligations were 
 entered into to forfeit fums in proportion to it, if ei- 
 ther of the parties fhould refufe to ratify the engage- 
 ment. At this ceremony, called the ^.r^rljov, or record- 
 
 appear that the ordination of the reader, or of the fub- 
 deacon, is confidered as a facrament. The forms ufed 
 in the ordination of deacons, prclbyters, and bilhops, 
 are ferious and fignificant (h), bearing in thcmfelves. 
 evidence of great antiquity. The candidate for the 
 deaconate or priefthood kneels before the holy table, 
 and the bllhop, laying his right hand on his head, faith, 24 
 " The divine grace, which healeth our infirmities, and Form of 
 fupplieth our defefts, promoteth N, the moll pious/j/A- ""*'""""'• 
 dencon, to the order of deacon ;" or, in the cafe of the 
 pricllhood, " The moft pious deacon to the order of a 
 
 ing of the pledges before in'itnejfes, the prieft gives lighted prejhyter ; let us pray fur him, that the Grace of the 
 tapers to the parties to be contratled, making the fign Holy Spirit may come upon him." It docs not ap- 
 of the crofs on the forehead of each with the end of pear, from Dr King's account of thefe offices, that in 
 the taper before he deliver it. the Greek church the attending prelLyters lay on their 
 
 The fecond ceremony, which is properly the mar- hands together with the bifliop at the ordination of a 
 
 3 I 2 prelbyter. 
 
 (h) We mull except thofe ufed in the church of Abyffinia, which, according to Mr Bruce, are fhamefully in- 
 decent. " A number of men and children prefent themfelves at a diftance, and there ftaiid, from humility, not 
 daring to approach the abuna or bilhop. He then allcs who thefe are ? and they tell him that they want to bi: 
 deacons. On this, with a fmall iron crofs in his hand, after making two or three figns, he bli)ws with his muutli 
 twice or thrice upon them ; faying, I^ei them be deacons. I faw once (fays our author) all the army ol Bi ijem- 
 dermade deacons, juft returned from ihedding the blood of 10,000 men. With thofe were mingled about iojO 
 women, who confequently having part of the fame blaft and brandilhment of the crofs, were as good deacons as 
 the reft. In the ordination of priefts a little more ceremony is uled ; for they mull be able to read a chapter 
 of St Mark, which they do in a language of which the abuna underllands not one word. They then give him 
 a brick of fait, to the value perhaps of fixpence, for their ordination ; which, on account of this preient, the 
 Jefuits maintained to be Simoniacal." There is but one bifliop or abuna in AbyfTinian, and lie is always a fo- 
 reigner, fubordinate in his jurifdi£lion to the patriarch of Alexandria.
 
 C H U 
 
 [ 436 ] 
 
 C H U 
 
 45 
 Solemn 
 confetra- 
 tion of 
 biAiops. 
 
 Church, prefbyter, as is praftifed in the church of England ; but 
 » feveral bifhops lay on their hands together with the 
 archbifhop at the confccration of a bifhop. 
 
 This is indeed a very folemn ceremony. The can- 
 didate for the epifcopate, who is always an archiman- 
 (irlle or hieromonachus, i. e. an abbot or chief monk in 
 fome moiiaftery, being named to the vacant fee, and 
 the eledion being confirmed, repairs, at the time ap- 
 pointed, to the church where the confccration is to be 
 performed. Being arrived, he is introduced by the 
 proto-pope (i) and proto-deacon to the archbifhop and 
 bilhops, who are arranged in proper order on a tempo- 
 rary theatre or platform eredcd in the church for the 
 occafion. He there gives an account of his faith ; de- 
 clares folemnly that he has neither given nor promifed 
 money, or any bribe-worthy fervice, for his dignity ; 
 and promifes to adhere fteadily to the traditions and 
 canons of the eaftern church, to vifit his diocefe regu- 
 larly, and to oppofe ftr'enuoufly all innovations and he- 
 refies, particularly the errors of the Latin church. This 
 being done, the arclibifliop fays, " The grace of the 
 Holy Spirit, through my humility, exalts thee N. archi- 
 mandrite or hieromonachus, beloved of God, to be 
 bilhop of the cities N. N. which God preferve." With 
 much ceremony the bifhop eleft is then condufted from 
 the theatre, within the rails of the holy altar, where he 
 kneels down with the other bifhops, who hold open 
 over his head the holy gofpel with the letters inverted, 
 the archbifhop faying aloud, " The divine grace, which 
 always healeth our infirmities, and fupplieth our defedls, 
 by my hand condufteth thee N. archimandrite or hiero- 
 monachus, beloved of God, bifhop eletl of the cities of 
 N. N. which God preferve ! — Let us pray therefore 
 for him, that the Grace of the moil Holy Spirit may 
 come upon him." Then the priefls fay thrice, " Lord 
 have mercy upon us ;" and while the bifliops continue 
 to hold the gofpel, the archbifhop figns the newly con- 
 fecratf d bifhop thrice with the fign of the crofs, faying, 
 " In the name of the Father, and of the Son, and of the 
 Holy Ghoft, now and for ever, even unto ages of ages. 
 Amen." Then all the bifhops putting their right hands 
 on his head, the archbifliop prays that he may be con- 
 firmed in the office of which they have judged him 
 worthy, that his priefthood may be rendered irreproach- 
 able, and that he himfelf may be made holy and worthy 
 to be heard of God. After this, one of the aflifling 
 bifhops reads a fhort litany in a low voice, to be heard 
 only by thofe within the altar, and the other bifhops 
 make the refponfes. At the end of the litany the arch- 
 bifhop, laying his hand again upon the head of the new- 
 ly confecrated bifhop, prays in very decent and devout 
 terms, that Chrill will render him an imitator of himfelf, 
 the true Shepherd ; that he will make him a leader of 
 the blind, a light to thofe who walk in darknefs, and a 
 teacher of infants ; that he may fhine in the world, and 
 receive at laft the great revpard prepared for thofe who 
 contend boldly for the preaching of the gofpel. After 
 this the paftoral-llaff is delivered to the new bifhop, 
 ■with a very proper and folemn exhortation from the 
 archbifhop, to feed the flock of Chriil committed to his 
 care. 
 
 The laft facramcnt of the Greek church is that of Churrfe- 
 the holy oil or euchelaion, which is not confined to per- '~~^ ' 
 fons peruulofe agrolanlibus, et mortis pniculo imminente, 
 like the extreme unftion of the Romilh church ; but is 
 adminiftered, if required, to devout perfons upon the 
 ilighteft malady. Though this ordinance is derived 
 from St James, chap. v. ver. 14, 15. it is by no means 
 deemed ueceffary to falvation, or obligatory upon all 
 Chriflians ; and it is well that it is not, for feven priefls 
 are required to adminifter it regularly, and it cannot be 
 adminiRered at all by Icfs than three. The oil is con- 
 fecrated with much folemnity ; after which each prieft, 
 in his turn, takes a twig, and dipping it in the oil now 
 made holy, anoints the fick perfon crofswife, on the 
 forehead, on the nofVrils, on the paps, the mouth, the 
 breaft, and both fides of the hands, praying that he may 
 be delivered from the bodily infirmity under which he 
 labours, and ralfed up by the grace of Jefus Chrill. if> 
 
 In the Greek, as well as in the Latin church, there '^''^ '^^'P** 
 is a fervice, called the divine lampedium, obferved on the '"'"" 
 Thurfday of paffion-week, in imitation of our Saviour's 
 humility. At Conftantinople Jefus Chriil is, on this 
 occafion, perfonificd by the Patriarch, and everywhere 
 clfe by the bifhop of the diocefe, and the twelve apoftles 
 by twelve regular priefls, when a ludicrous conteft arifes 
 who fhall reprefent Judas ; for the name attaches for 
 life. This office is performed at the wefl end of the 
 church, where an arm-chair is fet at the bottom, facing 
 the eall, for the bifhop ; and on each fide are placed 
 twelve chairs for the twelve priefls, who are to repre- 
 fent the twelve apoflles. The prayers and hymns ufed 
 on this occafion are exceedingly beautiful and appro- 
 priate; and when the firfl gofpel, relating our Savlour's- 
 wafhing of his difclples feet, begins to be read, the 
 bifhop or patriarch riles up, and takes off his pontifical 
 veflments by himfelf without afQllance. He then girds 
 himfelf with a towel, and taking a bafon of water in 
 his hand, kneels down and wafltes one foot of each 
 pried, beginning with the youngefl ; and after having 
 wafhed it he kiffes. it. All this is done as the feveral 
 circumdances are read ; and when he comes to the lall 
 prieft, who is fuppofed to reprefent Peter, that pried 
 rffeth up and faith, " Lord, doft thou wafii my feet ?" 
 &c. The blfliop anfwers in the words of our Saviour ; 
 and having finiflied the whole, puts on his garments a- 
 galn, and fits down; and as the fecond gofpel is read (k), 
 repeats the words of our Saviour, " Know ye what I 
 have done unto you ?" &c. The office is certainly an- 
 cient, and, if decently performed, mud be affedllng. ^y 
 
 Under the word Patriarchs, £«t;yr/. we have gl- The privi* 
 ven a fufBcient account of the rife of the patriarchates, '^K^?"^'''*- 
 as well as of the various degrees of rank and ^u'^o^'ty ^c f-'pIoan» 
 claimed by the bifhops of feveral other fees in the Greek tjnonle. 
 chuch. It may be proper to add here, that after the 
 taking of Conftantinople by Mohammed II. he conti- 
 nued to the patriarch of that city the fame prefent 
 which the Greek emperors had been accuftomed to 
 make — a paftoral daff, a white horfe, and four hundred 
 ducats in gold. To the Greek church and the main, 
 tenance of its clergy he left indeed ample revenues, 
 which they have gradually facrificed to their inconftan- 
 
 (1) In the Greek church all parldi prieds are c?&iA papas or popes ; and the proto-pope is an archprefbytero 
 (k) The firft gofpel is John xiii. 3 — 12. The fecond gofpel is John xiii. I2— 18.
 
 Clinrch, 
 Chufan. 
 
 C H U 
 
 cy, their aml)ition, and their private jealoufy 
 however, the patriarch of Conftaiitinopk- fills a very lu- 
 crative and high office. «' Bciides the power of nomi- 
 nating the otlier three patriarchs, and all epifcopal dij;- 
 nitarles (fays Mr Dallaway ), lie enjoys a molt extcnfivc 
 jurifdidioii,ct)nipriring the chiirchesof Anatolia, Greece, 
 Wallachia, Moldavia, and the Idands of the Archipelago. 
 Since the cUfe of the fixtcenth century, the Ruffian 
 church has claimed a jurifdidion independent of the fee 
 of Ctinftaiitinople ; though appeals have been made to 
 that fee in cafes of extraordinary importance. The in- 
 fluence of the patriarch with the Porte is very extenfive, 
 as far as his own nation is concerned. His memorials 
 are never denied ; and he can, in faft, command the 
 death, the exile, imprifonment for life, depofitioii from 
 offices, or pecuniary fine, of any Greek whom he may 
 be inclined to punilh with rigour, or who has treated his 
 authority with contempt. On the death of the patri- 
 arch the moll eager competition is exerted to fill the 
 vacant throne ; which, as It is obtained by bribery and 
 intrigue, is of courfe a very unliable feat to the fuccefs- 
 ful candidate, (honitl another offer to accept the appoint- 
 ment at a lower falary." For a fuller account of the 
 doftrines, difcipline, and worlhip of the Greek church 
 at prefent, we refer the reader to King's Rites and Ce- 
 remonies of the Greek Church in Rvjjia, and to Dalla- 
 •way's Conjlantinople ancient and modern (publilhed in 
 *797)' f''"'" which two works this abflraA has been 
 moftly taken. 
 
 CHUSAN-IsLANDs, a duller of fmall iflands on the 
 taft coft of China, which were vlfited by Lord Macart- 
 ney in his courfe to Pekin. Molt of thefe Iflands feem 
 to be hills riling regularly out of the fea, and rounded 
 at top, as if any points or angles exilling in their ori- 
 ginal formation had been gradually worn off into a 
 globular and uniform fhape. Many of them, though 
 clofe to each other, are divided by channels of great 
 depth. They rcil upon a foundation of grey or red 
 granite, fome part refenibling porphyry, except in 
 hardnefs. They were, certainly, not formed by the 
 fucceflive alluvian from the earth brought into the lea 
 by the great river at js'hofe mouth they are fituated, 
 like the numerous low and muddy illands at the mouth 
 of the Po, and many others ; but fhould rather be con- 
 fidered as the remains of part of the continent thus 
 fcooped and furrowed, as It were. Into iflands, by the 
 force of violent torrents carrying ofl", further into the 
 fea, whatever was lefs reliltable than the rocks juft men- 
 tioned. Some of them wore a very inviting alpeft ; 
 one in particular, called Poo-too, is defcribed as a per- 
 fedt paradlfe. This fpot was chofen, no doubt, for Its 
 natural beauties, and afterwards embelliflied, by a fet of 
 religious men, who, to the number of three thoufand, 
 poffels the whole of it, living there in a ftate of celi- 
 bacy. It contains four hundred temples, to each of 
 which are annexed dwelling-houfes and gardens for the 
 accommodation of thofe monks. This large monallery, 
 as it may be called, is richly endowed, and its fame is 
 fpread throughout the empire. 
 
 The Englilh Eaft India Company had once a faftory 
 at Chufan, the principal of thefe iflands, from which 
 they were many years ago interdifted. This, accord- 
 ing to the account of a Chlnefe merchant who remem- 
 bered the faftory, was not occafioned by any offence 
 given by the Englifli, but by the avarice of the officers 
 
 [.437 ] C I N 
 
 Still, governing at Canton, who draw large fums from the 
 accumulation of foreign trade in that port. Perhaps, 
 too, the excelfive jealoufy of the Chlnefe government 
 might fancy danger in the unreilrained communication 
 between foreigners and the fubjefts of that empire in 
 feveral of its ports at the fame time. 
 
 Ting-hal, the chief town of Chufan, reftmbles Ve- 
 nice, but on a fmallcr feale. It is furroundcd, as will 
 as interfered, by canals, over which are thrown (letp 
 bridges, afcended by Iteps like the Rialto. The ftreets 
 are narrow, and paved with fquare flat (tones ; but the 
 houfes, unlike the Venetian buildings, are low and moft- 
 ly of one Itory. The ornaments of thefe buildings are 
 confined chiefly to tht- roofs, on the ridges of which are 
 uncouth figures of animals in clay, flone, or Iron. The 
 town is full of fliops, containing chiefly articles of clo- 
 thing, food, and furniture, diiplayed to full advantage. 
 Even coffins are painted in a variety of lively and con- 
 trdllliig colours. The fmaller quadrupeds, including 
 dogs, intended for food, are expofed alive for fale, as 
 well as poultry, and fifli in tubs of water, with eels in 
 fand. When the gentlemen belonging to the embaffy 
 were at Ting-hai, they were itruck with the number of 
 places where tin-leaf and flicks of odoriferous wood 
 were fold for burning in the temples, which indicated 
 no flight degree of fuperflltion in the people. Super- 
 ftltion, however, made them not idle ; for throughout 
 the whole place there was a quick and aftive indullry. 
 Men pafled bufily through the ftreets, while not an in. 
 dividual was feen afliing alms ; and the women were 
 employed in the fliops. At Chufan, the number of 
 valuable harbours, or places of perfedl fecurlty for fliips 
 of any burden, isalmoil equal to the number of iflands. 
 This advantage, together with that of thtir central fi- 
 tuation, in refpedl to the ealtcrn coft of China, and the 
 vicinity of Corea, Japan, Leoo-keoo,- and Formola, at- 
 trafl confiderable commerce, efpecially to Ningpoo, a 
 city of great trade in the aJjoiniiig province of Che-chi- 
 ang, to which all the Chufan iflands are annexed. From 
 one port in that province twelve veflels fail annually for 
 copper to Japan. 
 
 According to Brookes, Chufan is in N. Lat. 30. O. 
 and E. Long, i 24. o. 
 
 CINARA, or Cynara, which we tranflate arti- 
 choke, is, according to Profeflbr Beckmann, the name 
 which was given by the ancients to a plant very diffe- 
 rent from the artichoke of our kitchen gardens, though 
 he admits that they belong to the fame genus. The 
 proofs which he adduces for the truth of his opinion 
 are too tedious to be Introduced Into this Work, efpe- 
 cially as they appear not to us to be abiolutely conclufive. 
 We muft therefore refer the reader to his Hillory of 
 Inventions. The cinara, carduus, and feolymus (fee 
 ScoLYMus in this Supplement), were in his opinion 
 fpecles of the thijlle, of which the roots and young 
 Jhoots, as well as the bottom of the calyx of the laft, 
 were eaten. He has proved indeed, he thinks, that 
 the Greeks and Romans ufed the pulpy bottom of the 
 calyx, and the tendered ftalks and young flioots of ma- 
 ny plants belonging to the thiltle kind, in the fame 
 manner as we ufe artichokes and cardoons, but that 
 thefe latter were unknown to them. 
 
 " It appears probable (fays he) that the ufe of thefe 
 thiftles, at leaft in Italy and Europe in general, was in 
 the courfe of time laid afide and forgotten, and that the 
 
 artr« 
 
 Chbfnn, 
 Cliiara.
 
 C I R 
 
 [ 438 ] 
 
 C O A 
 
 Oiiifiibsr articlioke, when it was firll brought to Italy from the 
 „. I'. Lt-vant, was coiifidered 33 a new fpecics of food. It is 
 [[_^ undoubtedly certain that our articlioke was full known 
 - ia that country in the 15th century. Hcnnolaus Bar- 
 barns, who died in 1494, relates that this plant was 
 rfirll; feen at Venice in a garden in 1473, at which time 
 it was very fcaree. About the year 1466, one of the 
 family of Strozza brought the flrft artichokes to Flo- 
 rence from 'Naples. Politian, in a letter in which he 
 defcribes the diflics he found at a grand entertainment 
 in Italy in 1488, among thefe mentions artichokes. 
 Thty were introduced into France in the beginning of 
 the 1 6th century, and into England in the reign of 
 Henry VIII." 
 
 1 be original country of the artichoke is unknown. 
 Linna;us fays that it grew wild in Narbonne, Italy, 
 and Sicily, as the cardoon did in Crete ; but our au- 
 thoT has proved very fufficiently, that with refpecl to 
 both thefe fafts the great botanift was mifinformed. 
 The artichoke is certainly known in Perfia ; but Ta- 
 vernier fa) s exprefslv, that it was carried thither, like 
 afparagus and other European vegetables of the kitchen 
 garden, by the Carmelite and other monks ; and that 
 it was only in latter times that it became common. 
 
 CINNABAR. See Chemistry in this Supplement, 
 n° 91. 
 
 CIRCLE OF Curvature, or circle of equicurva- 
 ture, is that circle which has the fame curvature with a 
 given curve at a certain point ; or that circle whofe ra- 
 dius is equal to the radius of curvature of the given 
 curve at that point. 
 
 CiRCLKS of Declination are great circles interfefting 
 each other in the poles of the world. 
 
 Circle of Dijfipation, in optics. See Optics, En- 
 
 cychn" 2SS- 
 
 Circle Equant, in the Ptolemaic aitronomy, is a 
 circle defcribed on the centre of the equant. Its chief 
 life is to find the variation of the firft inequality. 
 
 Circles of Excurfion are little circles parallel to the 
 ecliptic, and at fuch a diltance from it, as that the ex- 
 curfions of the planets towards the poles of the ecliptic 
 Tnay be included within them ; being ufually fixed at 
 about I o degrees. 
 
 CiKCLRS of Pnfit'wn, are circles pafling through the 
 common interfeflions of the horizon and meridian, and 
 through any degree of the ecliptic, or the centre of 
 any ftar, or otiier point in the heavens ; and are iifed 
 for finding out the fituation or pofition of any ftar. 
 Thefe are ufually fix in number, cutting the equinoflial 
 into 12 equal parts, which the aftrologers call the celtf 
 t'tal houfes, and hence they are fometimes called circles 
 of the celeflial hotifes. 
 
 CIRCULAR Lines, a name given by fome authors 
 to fuch ftraight lines as are divided by means of the di- 
 v'fions made in the arch of a circle ; fuch as the fines, 
 tangents, fecants, &c. 
 
 Circular Parts, called, from the ufe which he firfl 
 made of them, Napier's circular parts, are the five parts 
 of a right-angled or a quadrantal fpherical triangle ; 
 they are the two legs, the complement of the hypothe- 
 liufe, and the complements of the two oblique angles. 
 
 Concerning thefe circular parts, Napier gave a gene- 
 ral lule in his Logarilhmorum Canonis De/criptio, which 
 is this ; " The redangle under the radius and the fine 
 «f the middle part is equal to the reilangle under the 
 
 tangents of the adjacent parts, and to the rcftnngte iin» 
 dcr the cofincs of the oppofite parts. The right angle 
 or quadrantal fide being iiegledtd, the two fides and > 
 the complements of the other three natural parts are 
 called the circular parts, as they follow each other as it 
 were in a circular order. Of thefe, any one being fix. 
 ed upon as the middle part, thofe next it are the adja- 
 cent, and thofe fartheft from it the oppolite parts." 
 
 This rule contains within itfelf all the particular rules 
 for the folution of right-angled fpherical triangles, and 
 they were thus brought into one general comprchcnfive 
 theorem, for the fake of the memory ; as thus, by 
 charging the memorj' with this one rule alone : All the 
 calcs of right-angled fpherical triangles may be refol- 
 ved, and thofe of oblique ones alfo, by letting fall a 
 perpendicular, excepting the two cafes in which there 
 are given either the three fides, or the three angles. A nd 
 for thefe a fimilar expedient has been devifed by Lord 
 Buchan and Ur MInto, which may be thus expreffed : 
 " Of the circular parts of an oblique fpherical triangle, 
 the rcftangle under the tangents of half the fum and 
 half the difference of the fegments at the middle part 
 (formed by a perpendicular drawn from an angle to the 
 oppofite fide), is equal to the re£fangle under the tan- 
 gents of half the fum and half the difference of the op- 
 pofite parts." By the circular parts of an oblique fphe- 
 rical triangle are meant its three fides and the fupple- 
 ments of its three angles. Any of thefe fix being af- 
 fumed as a middle part, the oppofite parts are thofe 
 two of the fame denomination with it, that is, if the 
 middle part is one of the fides, the oppofite parts arc 
 the other two, and, if the middle part is the fupple- 
 ment of one of the angles, the oppofite parts are the 
 fupplements of the other two. Since evei-y plane tri- 
 angle may be confidered as defcribed on the furface of 
 a iphere of an infinite radius, thefe two rules may be 
 applied to plane triangles, provided the middle part be 
 relinked to a fide. 
 
 Thus it appears that two fimple rules fufifice for the 
 folution of all the poflible cafes of plane and fpherical 
 triangles. Thefe rules, from their neatnefs, and the 
 manner in which they are expreffed, cannot fail of en- 
 graving themfelves deeply on the memory of every one 
 who is a little verfed in trigonometry. It is a circum- 
 ftance worthy of notice, that a perfon of a very weak 
 memory may carry the whole art of trigonometry in 
 his h«ad. 
 
 CIRCULATING Decimals. See Decimals in 
 this Supplement. 
 
 CLOCK, a machine for meafuring time, of which a 
 defcription is given in the Encyclopaedia. For the 
 fcientific principles of clock and watch-making, as well 
 as for a (hort account of the moll valuable conftruftions, 
 fee VJATcn-Making in this Supplement. 
 
 COACH, as we have obferved in the Encyclopsdia, 
 is a very modern invention, if by that word be meant a 
 covered carriage fufpended on fprings. We learn, in- 
 deed, from the laborious refearches of ProfelTor Beck- 
 mann, that coaches of fome kind were known in the be- 
 ginning of the 16th century ; but they were ufed only 
 by women of the firft rank, for the men thought it dil- 
 graceful to ride in them. At that period, when the 
 eleftors and princes did not choofe to be prefent at the 
 meetings of the ftates, they excufed themfelves by in- 
 forming the emperor that their health did not permit 
 
 them
 
 COB 
 
 [ 439 J 
 
 COB 
 
 Coich. them tn ride on horfeback ; and it was confidered as a 
 ■" V 'point eltablilKed, that it was unbecoming for them to 
 ride like women. It is certain, however, that, about 
 the end of the I ;th centyi^y, the emperor, kings, and 
 princes, began to employ covered carriages on journt'ys, 
 and afterwards on public folejnnities. 
 
 The wedding carriage of the iirft wife of the Empe- 
 ror Leopold, who was a Spaniih princefs, coft, together 
 with the barnefs, 38,000 florins. The coaches ufed by 
 that Emperor are thus defcribed by Kink : " In the 
 imperial coaches no great magnificence was to be feen ; 
 they were covered over with red cloth and black nails. 
 The harnefs was black, and in the whole work there 
 was no gold. The pannels were of glafs, and on this 
 account they were called the imperial glafs coaches. On 
 feftivals the harnefs was ornamented with red filk frin- 
 ges. The imperial coaches were diftinguiflied only by 
 their having leather traces ; but the ladies in the impe- 
 rial faite were obliged to be contented with carriages, 
 the traces of which were made of ropes." At the mag- 
 nificent court of Duke Erneft Auguftus of Hanover, 
 there were in the year 168 1 fifty gilt coaches with fix 
 horfes each. So early did Hanover begin to furpafs 
 other cities in the number of its carriages. The firll 
 time that ambaffadors appeared in coaches on a public 
 folemnity was at the imperial commitfion held at Er- 
 furth in 161 5 refpefting the affair of Juliers. 
 
 In the hiftory of France we find many proofs that at 
 Paris, in the 14th, ijtli, and even 16th centuries, the 
 French monarchs rode commonly on horfes, the fervants 
 of the court on mules, and the princeffes, together with 
 the principal ladies, fometimes on afies. Perfons of the 
 firll rank often fat behind their equerry, and the horfe 
 was often led by fervants. Carriages, however, of fome 
 kind appear to have been ufed very early in France. 
 An ordinance of Philip the Fair, iffued in i 294 for fup. 
 prefllng luxury, and in which the citizens wives are for-- 
 bid to ufe carriages (c<7rj), is ftill preferved. Under 
 Francis I. or rather about 1550, fomewhat later, there 
 were in Paris for the firll time only three coaches. 
 
 The oldefl, carriages ufed by the ladies in England 
 were known under the now forgotten name of whirli- 
 cotes. When Richard II. towards the end of the 14th 
 century, was obliged to fly before his rebellious lub- 
 jects, he and all his followers were on horfeback ; his ■ 
 mother only, who was indifpofed, rode in a carriage. 
 This, however, became afterwards fomewhat unfafhion- 
 ihle, when that monarch's queen, Ann, the daughter of 
 the Emperor Charles IV. fliewcd the Englifli ladies how 
 gr;icefully and conveniently (he could, ride on a fide- 
 faddle. Whirlicotes were laid afide, therefore, except 
 at coronations and other public folemnities. Coaches 
 were firil known in England about the year 1580, and, 
 as Stow fays, were introduced from Germany by Fitz- 
 allen, earl of Arundel. In the year 1598, when the 
 Englifh anibaffador came to Scotland, he had a coach 
 with him. Anderfon pLices the period when coaches 
 began to be in common ufe about the year 1605. Tlie 
 eelebrated duke of Buckingham, the unworthy favou- 
 rite of two kings, was the firft perfon who rode with a. 
 coach and fix horfes, in 1619. To ridicule this new 
 pomp, the earl of Northu.mberland put eight horfes to 
 his carriage. 
 
 Refpeding the progrefs of luxury with regard to 
 coaches, the reader will find much curious information 
 
 in the firft volume of ProfefTor Bcckmann'a Hiflory of Cobalf. , 
 Inventions. It is perhaps oiw of the moft entertaining """"" 
 articles in that very learned work. The author, how- 
 ever, with all his labour, has not been able to afcertaia 
 the country in which coaches hung on fprings were firfl 
 ufed ; but he feems inclined to give the credit of the 
 invention to Himgary. 
 
 COBALT (fee CHEMisTKY-/ni/c..-, in this Supple- 
 ment), is a valuable article to potters and dyers. To 
 iit it for their ufe, it is firft roatled and freed from the 
 foreign mineral bodies with which It Is united: It Is then 
 well calcined, and fold either mixed or unmixed with- 
 fine fand under the name of zafter (■^ajfcra) ; or it is 
 melted with filiceous earth and potallies to a kind o£ 
 blue glafs called Jmalt, which when ground very fine is 
 known in commerce by the name of powder blue. All 
 thefe articles, becanfe they are moll durable pigments, 
 and thofe wiilch bed withftand fire, and becaufe one can 
 produce with them every (hade of blue, are employed, 
 above all for tinging cryftal and for enamelling ; for 
 counterfeiting opaque and tranfparent precious llones, 
 and for painting and varnifhing real porcelain and earth- 
 en and potters ware. This colour is indifpenfably ne- 
 ceflary to the painter when he is defirous of imitating 
 the fine azure colour of many butterflies and other na- 
 tural objefts; and the cheaper kind is employed to give 
 a bluelih tinge to new-walhed linen, which fo readily 
 changes to a difagreeable yellow, though not without' 
 injury to the health as well as to the linen. 
 
 Profcflbr Beckmann, In his Hijlory of Invention!, gives 
 the following account of the paint prepared from co- 
 balt. " About the end of the 15th century cobalt ap- 
 pears to have been dug up in great quantity in the 
 mines on the borders of Saxony and Bohemia, difcover- 
 ed not long before that period. As it was not known 
 at firft. to what uie it could be applied, it was thrown 
 afide as a ufelefs mineral. The miners had an averfion 
 to it, not only becaufe it gave them much frnitlcfs la. 
 bour, but becaufe It often proved prejudicial to their 
 health by the arfenical particles with which it was com- 
 bined; and it appears even that the mineralogieal name 
 ccbalt then firll took its rife. At any rate, I have ne- 
 ver met with it before the beginning of the i6th cen- 
 tury ; and Mathefius and Agricola feem to have firft 
 ufed it in their writings. Frifch derives it from the 
 Bohemian word iow, which fignifies metal; but the 
 conjcfture that it was formed from cohalus, which was 
 the name of .a fpirit that, according to the fuperftitlom 
 notions of the times, haunted mines, dellroved the la- 
 bours of the miners, and often gave them a great deal 
 of unnecelTary trouble, is more probable ; and there ij 
 reafyn to think th-at the latter is borrowed from the 
 Greek. The miners, perliaps, gave this name to th<3: 
 mineral out ol joke, becaufe it thwarted tlieni as much 
 as the fuppofed fpirit, by exciting falfe hopes, and ren- 
 dering their labour often fruitlels. It was once cullo. 
 mary, therefore, to Introduce into the church fcrviee a 
 prayer that God would preferve miners and their works 
 from knlolts and fpirlts. 
 
 " RefpeAing the invention of making an ufcful kind' 
 of blue glals from cobalt, we have no better information -. 
 than that which Klotzfch has ijublidied from the papers ■ 
 of Chriftian Lehmunn. The former, author of an hlf- 
 torical work rcfpciiting the upper dillrict of the mines 
 in Mifnia, and a ck-r^>;yRuii at bchcibenberg, coUoftcd
 
 COB 
 
 Cobalt, with great diligence every information tViat refpefted 
 ""■v~~— the hiflory of the neighbouring country, and died at a 
 great age in 1688. According to his account, the co- 
 lour mills at the time wlien he wrote were about loo 
 years nld ; and as he began firft to write towards the 
 e.id of the thirty years war, the invention feems to tall 
 about 1540 or 1560. He relates the circumtlance as 
 follows ; ' Chriftopher Schurer, a glafs-maker at Plat- 
 ten, a place which belongs lUil to Bohemia, retired to 
 Neudtck, where he eftablifhed his bulinefs. Being once 
 at Schnccberg, he coUeclcd fome of the beautiful co- 
 loured pieces of cobalt %vhich were found there, tried 
 them in his furnace ; and finding that they melted, he 
 mixed fome cobalt with glafs metal, and obtained fine 
 blue glafs. At firft he prepared it only for the ufc of 
 the putters; but in the courfe of time it was carried as 
 an article of merchandife to Nuremberg, and thence to 
 Holland. As painting on glals was then much culti- 
 vated in Holland, the artifts there knew better how to 
 appreciate this iir/ention. Some Dutchmen therefore 
 repaired to Y^eudeck, in order that they might learn the 
 proccfs ufed in preparing this new paint. By great pro- 
 mifes they perfnaded the inventor to remove to Magde- 
 burg, where he alfo made glafs from the cobalt cf Schnee- 
 berg ; but he again returned to hig former refidence, 
 where he conllrucled a handmill to grind his glais, and 
 afterwards erected one driven by water. At that pe- 
 riod the colour was worth 7^ dollars per cwt. and in Hol- 
 land from 50 to 60 florins. Eight colour mills of the 
 fame kind, for which roafted cobalt was procured in caflcs 
 from Schneeberg, were foon conftruAed in Holland; and 
 it appears that the Dutch mull have been much better 
 acquainted with, the art of preparing, and particularly 
 with that of grinding it, than the Saxons; for the Elec- 
 tor John George fent for two colour-makers from Hol- 
 land, and gave a thoufand florins towards the enabling 
 them to improve the art. He was induced to make this 
 advance chiefly by a remark of the people of Schnee- 
 berg, that the part of the cobalt which dropped down 
 "while it was loading contained more colour than the 
 roalled cobalt itfelf. In a little time more colour-mills 
 ■were erected around Schneeberg. Haas Burghard, a 
 merchant and chamberlain of Schneeberg, built one, by 
 ■which the eleven mills at Flatten were much injured. 
 Paul NordhofT, a Frieflander, a man of great ingenuity, 
 who lived at the Zwittermill, made a great many expe- 
 riments in order to improve the colour; by which he 
 was reduced to fo much poverty that he was at length 
 forced to abandon that place, where he had been em- 
 ployed for ten years in the colour- manufactory. He 
 retired to Annaberg, ellablilhed there in 1649, by the 
 afliftance of a merchant at Leipfic, a colour-manufafto- 
 ry, of which he was appointed the director; and by thefe 
 means rendered the Annaberg cobalt of utility. The 
 confumption of this article, however, muft have decrea- 
 fed in the courfe of time ; for in the year '6,9, when 
 there were mills of the fame kind at niOre of the towns 
 in the neighbourhood of mines, he had on hand above 
 8000 quintals.' Thus far Lehman n." 
 
 Kofsler fays, that the Bohemian cobalt is not fo good 
 as that of MIfnia, and that its colour is more like that 
 of afhes. We truft, however, that the qualities of fo- 
 reign cobalt fhall foon be a matter of little importance to 
 the Britilh artift, as a rich mine of this mineral has late- 
 ly been difcovered neair Penzance in Cornwal, 
 
 440 ] C O F 
 
 COFFEA, the CoFFFR-Trec, is a plant which has Coffes, 
 been botanically defcribed in the Encyclopaedia Britan- '""> ' "' 
 nica, where fome account is likcwife given of the modes 
 of cultivating it, as well as ofc the qualities of its fruit. 
 Since that account, however, was publifhed, two works 
 have fallen into our hands, from which we deem it our 
 dnty to make fuch extradts as may not only correifb 
 fome miftakes which we had committed, but alfo com- 
 municate ufeful information to the public. 
 
 In our former article we adopted the common opi- 
 nion, that the cofiee produced in Arabia is fo greatly 
 fuperior to that which is raifed everywhere elfe, that it 
 is vain to think of cultivating the plant to any extent 
 in the Weft India iflands. We are happy to find that 
 this is 8 vulgar error. In the year 178^, vvh^-'n the cul- 
 tivation of coffee was not fo well underllood in Jamaica 
 as at prefent, fome famples from that iiland were pro- 
 duced in London, and pronounced by the dealers to be 
 e-qual to the very beft brought from the Eall. " Two 
 of the iamples were equal to the beft Mocha coffee, 
 and two more of them fuperior to any coffee to be had 
 at the grocers (hops in London, unlefs you will pay the 
 price of piiked coffee for it, which is two fliillings per 
 pound more than for that which they call the be/} coi- 
 f?e. All the reft of the famples were far from bad cof- 
 fee, and very little inferior, if at all, to what the gro- 
 cers call bejl coffee *." « Mofdcy'i 
 If this be fo, it furely becomes the leglflature oi Tnuti/i am 
 Great Britain to encourage the cultivation of coffee in '#«• 
 the Weft Indies, efpecially as it thrives beft in foil which 
 is not fit for the fugar-cane, and may be raifed in con- 
 Cderable quantities by thofe who are not able to flock 
 a lugar plantation. The encouraging every article which 
 increafes the intercourfe with our colonies is increafing 
 our commerce. The payment for all the ftapks of the 
 Weft Indies is made in our manufaftures ; the fale of 
 which muft increafe in proportion to the numbers that 
 are employed in the cultivation of what is bartered for 
 them. Our Weft India iflands, without draining us of 
 fpecie or bullion, can fupply us with many of thofe ve- 
 ry articles for which we are drained in other parts of 
 the world, and particularly with coffee. 
 
 To give a detailed account of the introduftion of the 
 coffee-tree into the Weft Indies, would fwell this article 
 to very little purpofe. According to Boerhaave, a 
 Dutch governor was the firft perfon who procured trefti 
 berries from Mocha, and planted them in Batavia; and 
 in the year 1690 fent a plant from thence to Amlter- 
 dam, which came to maturity, and produced thofe ber- 
 ries which have fince furnifhed all that is now cultiva- 
 ted in the Weft Indies. 
 
 In 1714a plant from the garden of Amfterdam was 
 fent by Mr Pancras, a burgomafter and director of the 
 botanic garden, as a prefent to Louis XIV. which was 
 placed in the garden at Marly. In 1718, the Dutch 
 began to cultivate coffee in Surinam; in 1721, the 
 French began to cultivate it at Cayenne; in 1727, at 
 Martinico; and in 1 7 28, the Englifli began to cuhivate 
 it in Jamaica. 
 
 As it has been more cultivated in the French Weft 
 India iflands than in the Britifh, it may be of import- 
 ance to our colonifts to be made acquainted with the 
 praftice of the French planters. Accordingly Dr La- 
 borie, a royalift of St Domingo, has lately publifhed a 
 volume for their inftrudion on this fubjed; In which 
 
 are
 
 ] 
 
 C O F [ 441 
 
 oac3. arc niniiy judicious obfervations, the rcfult of lonj,' txpe- farther 
 
 -V ' rieiice, vcfpeainji the foil fit for a cofl'ee phntatiori ; 
 
 the various ellablifliments neceffary ; the cultivation of 
 the cofTce-trce through the feveral ftages of its growth 
 and duration ; and the management and ufe ot the ne- 
 groes and cattle. 
 
 Witli refpeft to foil, it is a faft, fays he, beyond con- 
 tradidion, that low lands, and even the mountains near 
 
 C O 1< 
 
 but, on tiie contrary, if to the ead or fonth it 
 be light (which it jjenerally i,), plant ftill nearer. Thus 
 if it be proper on a foutli or ea!l expofure to plant at 
 the dlllance of fix feet, it will be necciTary to plant at 
 the dillance of (even on a well or nortli expofurc, if th': 
 ground be of the fame ijuality as in the other fitua- 
 ^ions. 
 
 Though coffee, like all other vegetables, grows from 
 the champaign country, are lefs proper for the produc- the feed, Dr Laborie advifcs, in the forming of large 
 tion of cjffee, than lands which are high and at a di- plantations, to make ufe of faplings reared in nurle- 
 Itance from the Tea. The coffee-tree delights in a com- ries ; and the fitnation littell for a nurfery is a plain, or 
 paratively cool climate, and in an open and permeable at leail a ground of gentle afccnt, where the mould is 
 virgin foil; and is hurt by the parching dellruftive air crumbly. In forming a nurfery, fome plant the whole 
 of the fea. The foil on the mountains of St Domingo cherry ; but our author recommends the taking off the 
 confiils generally of a bed of mould more or lefs deep ; flcin, and wafhing the feparated feeds; in which we fufpcft 
 but which, for the produftion of coffee-trees, ought not that he is miflaken, as his praftice is certainly a devia- 
 to be lefs than four or five feet. If the declivity be tion from nature. The nurfery muft be kept very clear 
 gentle, the fofteft and moil friable earth is preferable to of weeds, and neither corn nor any thing elfe fown 
 all others; but in ilecp grounds a firm though not clayey in it. 
 
 foil, mixed with a proportion of gravel or fniall ftones. The befl feafon for tranfplanting the faplings is du- 
 
 through which the water may find an eafy way, is the ring the genial rains of April and May, when great at- 
 moft defirable. Tiie colour of the ground is of little tention is required, as the tivafures of future harvefls 
 QOnfequence, though fuch as is fomewhat reddifh is ge- are at ftake. Thofe plants are the fitted for being re- 
 nerally to be preferred. With regard to expofure, the moved which, in the language of our author, are 
 north and weft are the moft eligible in low and hot fi- crowned, or have each four little boughs ; and, if the 
 tuations, becaufe thefe expofures are the coolell ; and feeds were frcfh and fown in furrows about an inch from 
 on the higheft mountains the fouth and ead are to be each other, this perfedlion is generally attained in the 
 chofen, becaufe they are the hotteft. On the whole, courfe of a year. I'TTe faplings mull not be pulled up 
 neither the higheft nor the loweft fituations are the beft, by force, but carefully raifed by means of a flat, fliarp, 
 but thofe which are confiderably above the middle of iron fhovel, thrull deep under their roots; and the foon- 
 the mountains. er they are planted, after being taken up, the better. 
 
 Whatever be the planter's circumftances in point of In planting, the firft thing (o be done is to thruft 
 
 fortune, and our author thinks that he ought not to into the ground a dibble, or fhaip pointed ftick, round 
 undertake a fettlement without the command of jcoo which a bole is dug fidin nine to twelve inches in dia- 
 or 4000 pounds fterling, he ought not to fet out with meter, and from fifteen to eighteen in depth. Then a 
 a great number of negroes. If he cannot command a quantity of the mould taken out of the hole is thrown 
 plentiful fupply of viftuals from fome contiguous plan- back into it, till its depth be diminidied about four or fix 
 tation, fix, or at the moft twelve, male negroes, with inches ; and the plant being fupported with tl-.e lefr. 
 
 hand, in the middle of tlie hole, while the end of it! 
 ftraight root, which our author calls its pivot, touches 
 lightly the new bed, the furrounding mould is with the 
 right hand thrown in, to the height of fix inches. Thio 
 being lightly preffed down with both hands, more earth 
 is thrown in and prelfed in the fame manner, care being 
 taken not to hurt, or bend, or difplace the fapling, 
 which muft be fet fo deep that its two inferior branches 
 be rather below the level of the ground. On this ac- 
 count three or four inches of the hole are left open, 
 which, by the time that thefe branches rife above its 
 margin, are filled up by the furrounding earth. The 
 bufinefs is finiflied by finking the fharp-pointed ftick at 
 the upper margin of the hole, where it ferves as a fmall 
 fence to the infant tree. In hot fituations plantain 
 trees are intermingled with the coflee trees for the pur- 
 pofe of (hade and coolnefs. They are ufually placed in 
 every fourth or fixth row, as the trees are more or lefs 
 dillant, and the expofure more or leis hot. 
 
 To the bufinefs of planting very foon fucceeds that 
 
 Colfft. 
 
 one or two women, will be found fufficient to make the 
 firft effay. After building two huts, one for the mailer 
 or overfeer and the other for the tlaves, they arc to com- 
 mence their operations by cutting away the underwood 
 and creeping plants with the bill, and felling the trees. 
 The trees are to be cut as low as polTible, but the roots 
 are to be left in the ground, becaufe they preferve the 
 foil during the firft period of culture ; and in burning 
 this mafs of wood and ihrubs, the only way fometimes 
 of clearing the ground, care mull be taken that the fire 
 be nowhere fo violent as to convert the foil into the 
 confidence of brick, which it is very apt to do if the 
 foil be clayey. Amid the coffee-trees, after they are 
 planted, may be fown beans, maize, and all kinds of ef- 
 culent plants, pot herbs, *-id roots ; but particular care 
 r.iuft be taken to remove from thefe plantations all creep- 
 ing plants, fuch as melons, yams, potatoes, gourds, and 
 more efpecially tobacco, which multiphcs to a vad ex- 
 tent, and exhaufts the ground. 
 
 In St Domingo the mod approved method of plant- 
 ing the coffee-tree is in ftraight rows eroding each other of weeding; for there is hardly any plant to which 
 at right angles, and the didance between the plants is weeds are fo pernicious as the coffee-tree : they caufc 
 regulated by the quality and expofure of the ground, it to grow yellovv, fade, wither, and perifli. Wiiere 
 The richer the ioil, the expofures being the fame, and the ground flopes much, efpecially if the foil be foft 
 the cooler the expofure, the quality of the foil being and friable, the weeds muft be taken up by the hand ; 
 the fame, the farther mud the trees be planted afunder. for if they be rooted out by the hoe, the foil will be fo 
 If on the north and wed the ground be good, plant dill loofened that the rains will fweep it away. Some 
 
 SuppL. Vol. I. Part II. 3 K weedsj
 
 Coffca 
 
 C O F [44 
 
 weeds, however, from the depth of their roots muft be 
 dug up ; and when that is the cafe the earth mull be 
 carefully returned and prelFed down. If,' in weeding, 
 any faplings be found withered, others of the fame 
 fize muft be brought from the nurfery and planted in 
 their ftead, with what our author calls their clod, /'. e. 
 with the earth of the nurfery adhering to their roots. 
 If any fapling be found broken or twifted, it mull be 
 cut clofe by the ground in a (loping direcilion, the cut 
 furface facing the north, and it will foon put forth fuck- 
 ers, of which the bell only need be preferved. In plan- 
 tations of eighteen or twenty months old trees are often 
 found with yellow, withered leaves, of which the caufe 
 is fometimes a premature load of fruit, which mull 
 therefore be inllantly removed or the tree will perifh. 
 If, after this, it begin not in a few days to recover, it is 
 probably eaten at the roots bv a large white worm re- 
 fembling a Aug. In that cafe the tree muft be remo- 
 ved, the worm taken out, and before another tree be 
 planted in its ftead, a large hole muft be made in the 
 ground, expofed to the influence of the fun at leaft for 
 a fortnight. 
 
 The natural height of the coffee tree is from i ^ to 
 l8 feet ; and if left to itfelf it would have the form of 
 moft other trees, I. e. a naked trunk and a branchy head. 
 This is prevented by what the planters C3\\ Jloppiiig ; 
 which is performed by cutting off^ the top of the tree 
 when it has arrived at the proper height, which varies 
 according to circumftances. In the beft foil and moft 
 genial expofure, it is fuff^ered to grow to the height of 
 five feet, and in the worft ftopped at two ; but under the 
 fame afpeft, and on ground of the fame quality, all the 
 trees ought to be ftopped at the fame height. This ope- 
 ration of ftopping is very apt to make the trees put 
 forth fuperfluous branches, which renders them inac- 
 ceffible to the genial warmth of the fun, and, of courfe, 
 deficient jn the powers of fruftification. Thefe muft 
 be plucicii awzy while vet tender; for if they be fuff'er- 
 ed to grow till it become neceffary to cut them, a num- 
 ber of fprouts fucceed ; whereas, when they are pluck- 
 ed, the wound foon cicatrizes, and nothing follows. 
 
 The faw and the knife, however, muft fometimes be 
 ufed ; for when trees grow old their heads are apt to 
 fpoil ; fuperfluous branches may have been left upon 
 them through negledl ; a bough may ha^e been broken 
 \)y accident ; or branches may be fpent by too great a 
 load of fruit. In all thefe cafes recourfe muft be had 
 to pruning, which fliould be performed immediately af- 
 ter crop, and in fuch a manner as that the tree, when 
 it puts forth its newJaranches, may ftill have as much 
 as poffible its natural or former appearance. This will 
 be accompliftied by cutting the withered bough imme- 
 diately above a knot, whence a good fecondary branch 
 is put forth, which may be eafily trained into the pro- 
 per fhape. Our author diredts the cut to be ahvays 
 made fo as that the Hoping furface ftiall face tlft north ; 
 by which expofure it will efcape the injury which it 
 would otherwife receive from the exceflive heat of the 
 fl»ii. This is a good advice ; but it would ftill be an 
 improvement on it to treat the wound with Forfyth's 
 or Hit's _plafter, which we have defcribed elfewhere 
 (See EncycL Vol. XVIIl. page 562). When the tree 
 is completely pruned, the mofs and ofher excrefcences 
 muft be fcraped from the trunk with a wooden knife, 
 great care being taken not to injure the bark. 
 
 2 ] C O F 
 
 After pruning follows what is called n'ipp'ng. Th.is Coffi 
 is nothing more than the removal of thofe fuperfluous v— 
 
 fmall twigs which are fent forth from every cut furface 
 in fuch numbers as would foon exhanft the tree ; and it 
 is called nipping, becaufe they are plucked away by the 
 hand, and not cut by the knife. It is needlefs to ad i, 
 that when the ground begins to be impoveriflied, it 
 muft be enriched by proper manure. This is known 
 to every hulbandman both in Europe and in the Weft 
 Indies ; but it is not perhaps fo generally known that 
 the weedings, and chiefly the red (liins of coffee, when 
 gathered into pits, are, in procefs of time, converted 
 into a black mould, which our author fays makes the 
 very beft manure. 
 
 " The fruit of the coffee, when perfedlly ripe, ap- 
 pears like a fmall oval cherry. Under a red and flnning 
 flcin a whitilh clammy lufcious pulp prefents itfelf, 
 which generally inclofes two feeds. Thefe feeds have 
 one fide flat, the other hemifpherical. The firft is 
 marked with a longitudinal fiffure, and the flat fides are 
 applied to each other. When the feeds are opened, 
 they are found covered with a white, ligneous, brittle 
 membrane, denominated parchment ; on the infide of 
 which is anotlier filver-coloured membrane, exceedingly 
 thin, and feeming to originate from the fiffure of the 
 feeds. Sometimes the cherry has but one feed or grain, 
 which then is in the form of a fmall egg. This is pe- 
 culiar to old decayed trees, or to the extremities of fonie 
 fmall branches." 
 
 The bufinefs of preparation confifts in taking the 
 feed from its covering, in drying, and in cleaning it fo 
 as to have every advantage at market. Our author 
 thinks that the beft method of preparing the coffee is 
 to ftrip the feed of its outer fldn immediately on its be- 
 ing pulled, and to dry it in its parchment. The pro- 
 cefs has been already defcribed in the Encyclopaedia ; 
 but we believe it to be an injudicious one. We have 
 the authority of a very eminent botanift *, well ac- • Or 
 quainted with all the vegetable produflions of the WeftAK/Z^iA. 
 Indies,, to fay, that the improvement which we have 
 there mentioned, as propofed by Mr Miller, is greatly 
 preferable to Dr Laborie's pradlice. Indeed he him- 
 felf admits, that coffee dried in the cherry is more heavy 
 than when dried in parchment, and that it generally 
 has a higher flavour. Nay, he fays exprefsly, that " if 
 a planter wants to have coffee of the firft quality, either 
 for himfelf or for his friends, he muft fet a part a num- 
 ber of his oldefl trees, and not gather the fruit till it is 
 ripened into drynefs. It is in that manner, he believes, 
 that the Arabians in Yemen make their little harvefls ; 
 and he declares, that coffee thus nourilhed on the tree 
 to the laft moment, muft have every perfeftion of which 
 it is capable." His only ijjaufible objeftion is, that 
 the trees are foon exhaulled when the fruit is left fo 
 long upon them ; but doubtlefs this exhauftion might 
 be retarded by proper manure. 
 
 The chemical analyfis of coffee evinces that it pof- 
 feffes a great portion of mildly bitter and lightly aftrin- 
 gent gummous and refinous extraft ; a confiderable 
 quantity of oil ; a fixed fait ; and a volatile fait. — Thefe 
 are its medicinal conftituent principles. The intention 
 of torrefaftion is not only to make it deliver thofe prin- 
 ciples, and make them foluble in water, but to give it 
 a property it does not poffefs in the natural ftate of the 
 berry. By the action of fire, its leguminous tafte and 
 
 the 
 
 i
 
 C O F [ 44.^ ] C O F 
 
 (lie aqueous part of its mucilage are defiioyed ; its fa- There is fcarcely any vegetable infufion or dccoiftion CoffVa 
 ' line properties are created and difengagcd, and its oil vhofe clients differ from its grufs origin more tlian that I' 
 
 is rendered empyrenmatic— From thence arifes the pun- ofwhithweare fptaking. Coffee taken in fuhllance . " '^ "^ "'. 
 gent fmcll, and exhilarating flavour, not found in its na- caufes opprefTion at the llomacii, heat, naufea, and in- 
 tural (late. digollion : confcqucntly a continued ufe of a prepara. 
 
 The ronfting of the berry to a proper decree requires tion of it, in which any quantity of its fulillance is con- 
 great nicttv : Du Four juflly remarks, that the virtue tained, befides being difgulting to the palate, mull lend 
 and ai'reeablenefs of tlie drink depend on it, and that to produce the fame indiipofiiions. The reliduum of 
 both are often injured in the ordinary' method. Ber- the roatted berry, after its virtues are extraded from it, 
 nier fays, when he was at Cairo, where it is fo much is little more than an earthy calx, and mull therefore be 
 \ifed, he was affured by the bell judges, that there were injurious. 
 
 only two people in that great city, in the public way, The want of attention to this circumftance has been 
 
 who underllood the preparing it in perfeftion. It it the caufe ot many ot the complaints againfl coffee, and 
 
 be undcr-doiie, its virtues will not be imparted, and in of the averfion which fome people have to it ; and it is 
 
 ufe it will load and opprefs the iloniaeh : — If it be from this confideration that coffee fhould not be pre- 
 
 overdone, it will yield a flat, burnt, and bitter talle, its pared with milk inftead of water, nor fhould the milk 
 
 virtues will be deilroyed, and in vife it will heat the body, be added to it on the fire, as is fometimes the cafe, for 
 
 and aft as an aflringent. economical dietetic purpofes, where only a fmall quan- 
 
 Fourteen pounds weight of raw coffee is generally tity of coffee is ufed, as the tenacity of the milK im- 
 redaced, at the public roalliug ho\ues in London, to pedes the precipitation of the grounds, which is uecef- 
 cieven pounds by the roailiiig ; for which the deiler fary for the purity of the liquor, and therefore neither 
 pays feven pence half-penny, at the rate of five fliillings the milk nor the iugar fhould be added until after it is 
 for every hundred weight. In Paris, the fame quau- made with water in the ufual wav, and the clariticatiou 
 titv is reduced to ten pounds and an half. But the of it is completed (a). — The milk fliould be hot when 
 roafting ought to be regulated by the age and quality added to the liquor of the coffee, which fhould alio be 
 of the coffee, and by nicer rules than the appearance of hot, or both fhould be heated togctiier, in this mode of 
 the fumes, and fuch as are ufually praftiled : therefore ufmg coffee as an article of failenaii.;e. 
 the reduftion mud confequently vary, and no exaft If a knowledge of the principles of coffee, founded 
 ftandurd can be afcertained. Befides, by mixing dif- on examination and various experiments, added to ob- 
 fereut forts of coffee together, that require different de- fervations made on the extenfive and indifcriminate ui'e 
 grees of heat and roafting, coffee has feldom all the ad- of it, cannot authorife us to attribute to it any par- 
 vantages it is capable of receiving to make it delicate, ticular quality untriendly to the human frame ; if the 
 grateful, and pleafant. This indeed can be cffefted no unerring tell ot experience has contirnied its utility, in 
 way fo well as by people who have it roalled in their mai>y countries, not exciufively produclive of thole in- 
 c'wn houfes, to their own tafte, and frelh as they want conveniences, habits, and difeales, lor which its pecu. 
 it for ufe. The clofer it is confined at the time of roall- liar properties ieem moll applicable — let thofe proper- 
 ing, and till ufed, the better will its volatile pungency, ties be duly conlidercd ; and let us reflei'l; on tne flate 
 flavour, and virtues, be preferved. of our atinolpherc, the food and modes of life of the 
 
 The mode of preparing this beverage for common inhabitants, and the chronical infirmities which derive 
 
 ufe differs in diflerent countries, principally as to the tlieir origin from thefe fources, and it will be evident 
 
 additions made to it. — But though that is gejierally what falutary effefts might be cxpcfted from the general 
 
 underllood, and that tafle, conftitution, the quality of dietetic ufe of coffee in Great Britain, 
 the coffee, and the quantity intended to be drunk, mull COFFER-dams, or Balarilenus, in bridge-building, 
 
 be confulted, in regard to the proportion of coffee to are encloiures formed for laying the foundation of piers, 
 
 the water in making it — yet there is one material point, and for other works in water, to exclude the iurround- 
 
 the importance of which is not well underflood, and ing water, and fo prevent it from interrupting the work- 
 
 which admits of no deviation. men. 
 
 The prefervation of the virtues of coffee, particularly COLCHESTER, the chief town in Eflcx, is de- 
 
 when it is of a fine quality, and exempt from ranknefs, fcribed in the Encyclopaedia Britaunica ; but the de- 
 
 as has been faid, depends on carefully confining it after fcription is in many refpefts erroneous. The following 
 
 it has been roafted ; and not powdering it until the account of it was fent to us by an obliging correlpon- 
 
 time of uiliig it, that the volatile and ethereal princi- dent, who is defirous that the place of his nativity may 
 
 pies, generated by the fire, may not efcape. But all be accurately defcribed in this Supplement, 
 this will lignify nothing, and the befl materials will be Colchefter is pleafantly fituated upon an eminence, 
 
 ufelefs, unlefs the following important admonition is gradually rifing on the fouth fide of the river Coliie. 
 
 flriftly attended to ; which is, that after the liquor is It is the ancient Colonia .CamuloJunum, from which 
 
 made, it fhould be bright and clear, and entirely ex- word Colonia, both the town and the river Colne re- 
 
 empt from the leaft cloudinefs or foul appearance, from ceived their names. The Saxons called it Colneceajer. 
 
 a fufpenfion of any of the particles of the fubftance of That it flourifhed under the Romans, feveral buildings 
 
 the coffee. full of their bricks, and innumerable quantities of coin 
 
 3 K 2 dug 
 
 (a) It Is not to coffee alone that this refleftion is confined ; every article we ufe as a diluter demands the 
 fame attention. Malt liquors, particularly fmall beer, which in this refpeft is much neglefted, ought always to 
 be carefully fined. The feculent matter entangled by the mucilage of the malt is hurtful to digeftion, and de- 
 trimental to health.
 
 COL [ 444 ] COL 
 
 Colchcfler, Jup up in and about it, fully evince. In tlie year 1763, optical phenomennn, which was full, we believe, at- 
 
 Colours. jj curious teflVUated cr imfaic pavement was found in tended to by Bnilon. That philofopher wrote a fhort *■ 
 
 * the garden of the late Mr Barnard, furgeon in the paper on it, which was publifhcd in the Memoirs of 
 
 High Street, now the property of Mr John Wallis, the Academy of Sciences for the year 174.?. 
 
 about three feet under the furface of tlie earth. The If a perfon look lledfalUy and for a confiderable time 
 
 emperor Conllantine the Great was born here, his mo- at a fmall red fqiiare painted upon white paper, he will 
 
 ther Helen being daughter of Cool, governor or king at lall obferve a kind of green-coloured border furround 
 
 of this diftriA under the Romans. She is faid to have the red fquare. If he now turn his eyes to fome other 
 
 found out the crofs of Clirift at Jerufalem ; and on that part of the paper, he will fee an imaginary fquare of a 
 
 ^ account the arms of this town are a crofs regulee be- delicate green bordering on blue, and correfponding ex- 
 
 tween three ducal coronets, two in chief and one in aftly in point of fr/.e with the red fquare. This imagi- 
 
 bafe, the coronet in bafe paffing through the crofs. nary fquare continues vifible for fome time, and indeed 
 
 The walls wherewith the toivn was encompaffed are does not difappear till the eye has viewed fucceffively a 
 
 ftiU tolerably entire on the fouth, eafl, and weft fides, number of new objetts. It is to this imaginary fquare 
 
 but much decayed on the north fide : they are general- that the improper name of accidental colour has been 
 
 ly about nine feet thick. By a ftatute of King Henry given. If the fmall fquare be yelloiu, the imaginaiy 
 VIII. this town was made tlie fee of a fuffiagan bifhop. 
 
 This town is the mod noted in England for making 
 of baize ; it is alfo of fpccial note for candying the crin- 
 go roots, and for oyfters. 
 
 In the conclufion of the civil war 1648, tliis town 
 
 fquare or accidental colour is blue : the accidental co- 
 lour of green is red ; of blue, yellow ; of white, black ; 
 and on the contrary, that of black is white. 
 
 The tirll perfon, as far as we know, who gave a fa- 
 tisfactory explanation of thefe phenomena was ProfefTor 
 
 fuffered a fevere fiege of ten weeks ; and the befieged Scherffer of Vienna, whofe diflertation, tranfiated by 
 
 making a very rcfolute defence, the ficge was turned 
 into a blockade, wherein the garrifon and inhabitants 
 fuffered the utmoft extremity of hunger, being reduced 
 to eat horfe-flefh, dogs, and cats, and were at laft obli- 
 ged to furrendcr at difcrction, when their two valiant 
 chief officers, Sir Charles Lucas and Sir George Lifle, 
 were fhot under the caflle walls in cold blood. Col- 
 c'helUr is a borough by prefcription, and under that 
 right fends two members to pailiament, all their char- 
 ters being filent upon that head. The charter was re- 
 newed in 1763. The town is now governed by a may. 
 or, recorder, iz aldermen, 18 affiftants, and 18 com- 
 mon-council men. Quarter- fefTions are held here four 
 times in the year. 
 
 The famous abbey gate of St John is ftill ftanding. 
 
 Mr Bernoulli, has been publifhcd in the 26th volume of 
 the Journal de Phyllque. 
 
 In order to underftand thefe phenomena, let us re- 
 colledl, in the firrt place, that light confills of feven rays, 
 namely, red, orange, yellow, green, blue, indigo, violet ; 
 that whitenefs confiils in a mixture of all thefe rays: 
 and that thofe bodies which refletl but very little light 
 are black. Thofe bodies that are of any particular co- 
 lour, refleft a much greater quantity of the rays which 
 conftitute that particular colour than of any other rays. 
 Thus red bodies refleiSl moft red rays ; green bodies, 
 mod green rays, and fo on. 
 
 Let us recoUeft, in the fecond place, that when two 
 impreffions are made at the fame time upon any of our 
 organs of fenfation, one of which is ftrong and the 
 
 and allowed to be a furprifing, curious, and beautiful other weak, we only perceive the former. Thus if we 
 
 piece of Gothic architefture, great numbers of perfons examine by the prilm the rays reflefted by a red rofe, 
 
 coming from remote parts to fee it. It was built, to- we (hall find that they are of four kinds ; namely red, 
 
 gether with the abbey, in 1097, and Gudo, fteward to yellow, green, and blue. In this cafe, the impreffion 
 
 King William Rufus, laid the firft Hone. made by the red rays makes that made by the others 
 
 St Ann's chapel. Handing at the eaft end of the quite infenfible. For the fame reafon, when a perfon 
 
 town, is valuable in the efteem of antiquarians as a goes from broad day light into an ill-lighted room, it 
 
 building of great note in the early days of Chriftianity, appears to him at tirft perfectly dark, the preceding 
 
 and made no fmall figure in hiftory many centuries pait. llrong impreflion renderi:Tg him for fome time incapable 
 
 It is now pretty entire. 
 
 St Botoph's priory was founded by Ernulphus in the 
 rfign of Henry I. in the year 1 1 10. It was demolilh- 
 cd in the wars of Charles I. by the parliament army 
 under Sir Thomas Fairfax. The ruins Hill exhibit a 
 beautiful ll<ctcli of ancient mafonry, much admired by 
 the lovers of antiquities. The caftle is ftill pretty en- 
 
 of feeling the weaker Impreffion. 
 
 With the affiilance of thefe two remarks, it will not 
 be difficult to explain the phenomena of accidental co- 
 lours. When a jjerfon confiders attentively for fome 
 time a white fquare lying on any black fubllance (paper 
 for inftafice), it is evident that the part of the retina 
 on which the white fquare is painted, receives a ftronger 
 
 Here is an excel- 
 
 tire, and is a magnificent ftrutture, in which great im- impreffion than any other part ; at leafl the greateft 
 
 number of rays ttrike upon it. A weaker impreffion, 
 therefore, will aft on it with much lefs force than upon 
 the reft of the retina. Confequently, when the eye is 
 turned from the white fquare to fome other part of the 
 black paper, a fquare is perceived of the fame fize with 
 the white fquare, and much blacker than any other part 
 of the paper : this is evidently in confequence of the 
 
 provements have of late been made 
 lent and valuable library. 
 
 The markets, which are on Wednefday and Satur- 
 day, are very well fupplied with all kinds of provifions. 
 There are no lefs than fix diffenting meeting-houks in 
 this town. Colchefter is 51 miles from London. It 
 had 16 parifh churches, in and out of the walls, hut 
 
 now only 12 are ufed, the reft being damaged at the weaker impreffion made by the rays reflefted by the 
 fifge in 1648. black paper upon that part of the eye previoufly fa- 
 
 , COLOURS. See Pigments in this Supplement, tigucd by the cgpious refleftion from the white fquare. 
 
 Accidental Colours, a name given to a very curious For the very fame reafon, if, after looking for a fuffi- 
 
 cie.nt
 
 COL 
 
 Colours, cicnt time at a wliite fqiiare lying on a black ground, 
 *— ~v xye turn our eyes upon a fheet of white paper, we per- 
 ceive a very well defined black Iquare. In tliis cafe, 
 the part of the retina already fatigued is not fo fenfible 
 to the rays rcfletled by the white paper as the other 
 parts of it which have not been fatigued. The reafon 
 then tliat l)/aci is the accidental colour of white is fut- 
 ficiently evident. 
 
 On the contrary, when we look a fufficient time at a 
 black fquare lying upon a white ground, if we turn our 
 eyes to any other part of the white paper, or even upon 
 black paper, we (hall perceive a fmall fquare anfwering 
 to the black fquare, and much brighter than any other 
 part of the paper : evidently becaufe that part of the 
 retina on which the black fquare was painted being lefs 
 fatigued is more fufceptible of impreffions than any 
 other part of the eye. Thus we fee why the accidental 
 colour of black is white, and why that of white on the 
 contrary is black. Thefe fafts, indeed, have been long 
 known, and they have been generally explained in this 
 manner. 
 
 When a perfon has looked for a fufficient time at 
 a red fquare placed on a fheet of white paper, and then 
 turns his eyeS to another part of the paper, that part 
 of the retina on which the red was painted being fa- 
 tigued, the red rays reflefted from the white paper ceafe 
 to make any fenfible impreffion on it, and confequ.ntly 
 there will be feen upon the white paper a fquare finiilar 
 to the red fquare, and the colour of which is that 
 which would refult from the mixture of all the rays of 
 light except the red. In general, therefore, the tiai- 
 Jental colour is the colour which refults from the mix- 
 ture of all the rays of light, thofe rays excepted which 
 are the fame with the primitive colour. 
 
 Now, in order to difcover the accidental colours, 
 let us recolleft the manner which Newton employed to 
 determine the colour which refults from the mixture of 
 feveral others, the fpecies and quantity of wliich are 
 known. He did it by dividing the circumference of a 
 circle, fo that the arches are to one another in the 
 proportion of a firing fhortened by degrees, in order to 
 found one after another the notes of an odlave ; which 
 is nearlv the proportion that the diflerent rays occupy 
 ■when light is decompofed by means of the prifm. Or 
 fuppofe the circumference of the circle, as ufual, divi- 
 ded into 360 degrees, the different rays, according to 
 Benvenut, Ihould occupy the following arches ; 
 
 [ 445 ] 
 
 COL 
 
 Red, 
 
 Orange, 
 
 Yellow, 
 
 Green, 
 
 Blue, 
 
 Indigo, 
 
 Violet, 
 
 45° 
 
 37 
 
 48 
 
 60 
 
 60 
 
 40 
 
 8o 
 
 Let us now compare the aftion of colours on one 
 another with that of different weights; and for that pur- 
 pofe let us fuppofe each colour concentrated in the cen- 
 tre of gravity of its ardi. In order to find the colour 
 refulting from any mixture, we liave only to find the 
 common centre of gravity of the arches which reprefent 
 the different colours : The colour refulting from the 
 mixture will be that of the aich to which the common 
 centre of gravity approaches nearefl;. And if that com- 
 mon centre of gravity is not in the ftraight line which 
 joins tlxe centre of the circle, and the centre of gravity 
 
 of the afch to which it is mofl contiguous, the refult- Colhurf. 
 ing colour will approach more or lefs to the colour of' ' v 
 the contiguous arch towards whicli the line, palTuig 
 through the centre of the ch'cle, and the ctnmion cen- 
 tre of gravity of the arches, falls. And farther, the re- 
 fulting colour will be more or lefs deep according to 
 the dillance of the common centre of gravity from the 
 centre of the circle. 
 
 In the cafe under confideration at prcfent, namely, to 
 determine the different accidental colours, the applica- 
 tion of this method is remarkably eafy ; becaufe only 
 one of the feven primitive colours is excluded, and confe- 
 quentlythe fix colours from the mixture of which we wiflx 
 to know the refulting colour are all contiguous. For it 
 is evident, that the funi of the fix arches, reprefenting 
 thefe l\ii colours, will be divided into two equal parts by 
 the line which paffes through the centre of the circle and 
 their common centre of gravity ; and that if the fame 
 line be produced till it reaches the circumference of the 
 circle on the other fide, it will alfo divide the arch re- 
 prefenting the feventh or omitted colour into two equal 
 parts. Let us fuppofe, for inllance, that the violet is 
 omitted, and that we wanted to know the colour refult- 
 ing from the mixture of the other fix colours, we have 
 only to bifefl the arch reprefenting the violet, and from 
 the point of fedlion to draw a diameter to the circle, the 
 arch of the circle oppofite to the violet through which 
 the dismeter paffes will indicate the colour of the mix- 
 ture. The arch reprefenting the violet being So", let us 
 take the half of it, which is 40", and let us add to it 
 45° for the red, 27" for the orange, and 48° for the yel- 
 low, we fliall have 160°, which wants 20° of half the 
 circumference of the circle. If now we add the 60" 
 for the green, the fum total will be 220°, confiderably 
 more than half the circumference ; confequently the 
 common centre of gravity is neareft the green aich; but 
 it falls 10° nearer the yellow than the llraight line which 
 joins the centre of the c-:rcle and the centre of gravity of 
 the green arch. Hence we fee that the refulting colour 
 will be green, but that it will have a fhade of yellow. 
 
 It is evident, then, that the accidental colour of vio- 
 let muil be green with a fhade of yellow ; and this is- 
 actually the cafe, as any one may convince liimfelf by 
 making the experiment. 
 
 Suppofe, now, we wanted to know the accidental co- 
 lour o{ green, or, which is the fame thing, tlie colour re- 
 fulting from the mixture of all the primitive rays ex- 
 cept the green. The green arch is 60°, the half of 
 which is 30" ; if to this we add 60" for the blue arch, 
 and 40° for the indigo arcli, we iball have 130", or 
 ^0° degrees lefs than a femicircle. If to this we add 
 the violet arch, which is 80", we fhall have 30" more 
 than the femicircle ; confequently the common centre 
 of gravity falls neareft the violet, and it is 10° nearer 
 the red arch than is the centre of gravity of the violet 
 arch. Hence we know that the accidental colour of 
 green will be violet or purple, with a fhade of red ; Ai:d 
 experiment confirms this. 
 
 Bulfon obferved that the accidental colour of blue 
 was reddifli and pale. Let us fee whether we fliall ob- 
 tain the fame refult from our method. Let us fuppofe 
 that Buffon employed a light blue. In that cafe, if to 
 30,. the half of the blue arch, we add 60 for the green,, 
 48 for the yellow, and 27 for the orange, we fhall have- 
 i6j'', or 15" l«fs thau half the circumfLrence of th«- 
 
 cirde. »
 
 COL C 446 ] COM 
 
 J'-'l'^urs. circle : Confeqiiciuly tlie comn.oii centre t^'il! fall neareft that are coiiti'mially takintj place in the lonW of ouf 
 
 " "^ the red arch, but within 1 5' of the orange. The acciden- little fquare ; fometimes it is large, fonietimes fmall ; at 
 
 tal colour miiil thcrtfore be red, with a Ihade of orange ; one time it difappears altogether, and the next moment 
 
 or, which is the fame thing, it nniil be a pale red. makes its appearance again. 
 
 In the fame manner we may difcover, that the acciden- There is another phenomenon connefled with acci- 
 tal colour of indigo is yellow, inclining a good deal to dental colours, which it is not fo cafy to explain; name- 
 orange ; and that the accidental colour of indigo and ly, that if we look at thefe little fquaies for a very long 
 blue together is orange, with a ftrong (hade of red. time, till the eye is very much fatigued, their acciden- 
 Both of which correfpond accurately with experiment. tal colours will appear even after we Ihut our eyes. The 
 
 It would be eafy to indicate, in the fame manner, very fame thing takes place if we attempt to look at 
 the accidental colour of any primitive colour, if what a very luminous objeCl ; as the fun, for inltance. Pro- 
 has been faid were not fufficient to explain the caufe of fefibr ScherfFer thinks that this may be partly owing 
 accidental colours, and to fhow that their phenomena to the light which ilill palfes through the eye-lids, 
 correfpond exaftly, both with the Newtonian theory of That fome liglit pailes through the eye-lids is evident, 
 optics, and with what we know to be laws of our fen- becaufe when we look towards a Itrong light with our 
 fations in other particulars. eye-lids fliut, we fee dilUndtly their colour, derived from 
 
 From the theory above given, which is that of Profeflbr the blood-vefi'els with which they are filled ; and if we 
 
 ScherfFer, the following confequences may be deduced: pafs our finger before our eyes, we fee the fliadow of 
 
 I. The accidental colour of a red fquare, lying upon the finger though our eye-lids b'e (liut, provided our 
 a white or a black ground, ought to be blackifli. if we eyes be turned towards the window. But that this 
 caft our eyes upon a red coloured furface. 2. If the light is not fufficient to explain the phenomenon in 
 furface upon which we look at a red fquare be itfelf queftion is evident from this ciicumllanee, that the fame 
 coloured, if it be yellow, for inftance, the white paper accidental coluurs make their appearance though we go 
 upon which we afterwards caft our eyes will appear immediately into the darkeil place. Perhaps we have 
 blue, with a green fquare in it correfponding to the ori- accounted for the phenomenon clfewhere (See Meta- 
 ginal red fqua'c. And, in general, we ought toper- physics, ^Hfj'tV. n^ 54.) We pafs over the other con- 
 ceive the accidental colour of the ground on which the jetleies of Profeffor ScherfFer, which are exceedingly 
 iquare is placed, as well as the fquare itfelf. 3. If while ingenious, but not fufliciently fupported by fadts to be 
 we are looking at the little fquare we change the fitua- admitted. 
 
 ticn of the eye, fo that its image fliall occupy a diffe- COLUMBA Noachi, Noah\ Dove, a fniall con- 
 rent place on the retina, when we turn our eyes to the ftellation in the fouthern hemifphere, confilting of 10 
 white paper we Ihall fee two fquares, or at leall one un- ftars. 
 
 like the figure of the original one. 4. If the white pa- COMAR, or Khomar, a Zemindar's demefne of 
 
 per on which we look be farther diftant than the little land. 
 
 fquare was, the imaginary fquare will appear confide- COMBUSTION is an operation of nature, which, 
 
 rably larger than the true one. j. If while we are though of the highelt importance, feems not to have 
 
 looking at the little fquare, we gradually make the eye attratlcd much of the attention of philofophers previ- 
 
 approach to it, without altering its fltuation, the ima- ous to the feventeenth century. Since that period in- 
 
 ginary tqnare will appear with a pale border. Thefe, deed, the labours of Bacon and Boyle, and Hooke and 
 
 and many other conftqueuces that might eafily be de- Mayow, together witii thofe of Stahl and Lavoificr, 
 
 ductd, will be found to take place conilantly and accu- ha\e thrown much light on 'the fubjedt ; as the reader 
 
 rately, if any one choofcs to put them to the teft of ex- will find by conlulting the articles Chemistry both in 
 
 periment ; and therefore may be confidered as a com- this Supplement and in the Encyclopaedia. The the- 
 
 plete confirmation of the theory given above of the ory of Lavoifier is l;y far the molt rational that has yet 
 
 caufe of accidental colours. been oftered to the public, and places its author in the 
 
 There is another circumftance refpefting accidental firft ranks of philofophy. He corredls the errors of his 
 
 colours which deferves attention. If we continue look- predeceflors, and has advanced before them one very 
 
 ing ftedfailly at the little fquare longer than is neceffa- important ftep ; but, as we have elfewhere obferved, 
 
 ry, in order to perceive its accidental colour, we fliall many new fteps are ftill wanting to render his theory 
 
 at laft fee its border tinged with the accidental colour of combuftion complete. It explains indeed, in a fatis- 
 
 of the ground on which the fquare is lying. For in- fadfovy manner, why, during the procefs of combuftion, 
 
 ftance, if a while fquare be placed upon blue paper, its the burning body gradually waftes away ; but it gives 
 
 border becomes yellow ; it upon red paper, it becomes no explanation of the conftant emifGon of heat and 
 
 green ; and it becomes reddifh upon green. In like light, though a circumftance as worthy of attention as 
 
 manner, the border of a yellow fquare becomes greenifli the wafting of the body. 
 
 upon a red ground, and that of a red fquare on a green The emiffion of light and heat the French chemifts 
 
 ground becomes purple. feem indeed to have confidered as of no importance ; 
 
 The caufe of this phenomenon feems to depend upon for rather than acknowledge that the theory of their 
 
 the contraftion and extenfion of the image of the fquare juftly admired and ill-fated aflociate is incomplete, they 
 
 painted on the retina. We know for certain, that the have chofen to give a new meaning to the word combus- 
 
 diameter of the pupil changes during our infpeAing the t'wn ; and to make it fignily the combination of a body 
 
 fquare ; at firft it becomes lefs, and afterwards increafcs. luitli oxygen, whether during that procefs light and heat 
 
 And though we cannot fee what palfes in the bottom be evolved or not. Surely fuch conduft is unphilofo- 
 
 of the eye, we can fcarcely doubt that fimilar move- phical ; and yet our own chemifts, with a fervility 
 
 ments are going on there, if we attend to the changes which ill becomes the countrymen of Bacon and New- 
 ton, 
 
 Coloirrt
 
 COM 
 
 Combuf- ton, hnve, for the mofl part, aoquicfctJ in this abfurd 
 
 lion. definition of coinhiillion. 
 ^——Y^— Yiom the tlafs of idolaters of the fcience of the ^-nvj/ 
 n I/ion mud be excepted Dr Thomfon, the aiittiov of 
 the article Chemistry in this Suppkment. Senfihlc 
 that combiifi'wu, in the fenfc ufiially affixed to that word, 
 denotes a plienomenon very different from many of thofc 
 which are incUidcd under the term in its new accepta- 
 tion, he acknowledges the theory of Lavoiiier to be 
 defeftive ; but inlUienccd by that diffidence which is 
 the inleparable attendant on the fpirit of true piiilofo- 
 phy, he has not ventured to complete it in the article 
 to which we have referred. He has indeed formed a 
 theory of his own, and fubmitted it to public difcuf- 
 fion ; but, with great propriety, gives it no place in 
 his Syilem of the Science, till it thall have undergone 
 the examination of other chemifts. 
 
 The conduftor of this work, however, perfnaded that, 
 while gratifying his readers in general, he (hall not in- 
 jure his friend's fame, embraces with pleafure the op- 
 portunity afforded him, by a new edition, of laying be- 
 fore them a conciie view of this very ingenious theory. 
 
 Dr Thomfon, then, admitting the truth and accu- 
 racy of the Lavoiferian theory as far as it proceeds, di- 
 vides the bodies which occupy the attention of chemills 
 into, I. Combuftibles ; 2. Supporters of combujlion ; and, 
 3. Incombtijllblts. 
 
 The COMBUSTIBLES, or thofe bodies which, in com- 
 mon language, are faid to burn, may be divided into, 
 1. S'lmtle combuftibles ; 2. Compound combuftibles ; and, 
 3. Combuftible oxides. ;S;m^/if combuftibles 'Axe, fulphiir, 
 phofphorus, carbon, hydrogen, and all the metals, except 
 perhaps gold, Jilver, and mercury. Compound combuf- 
 tibles conlill of compounds formed by the fimple com- 
 buftibles uniting together two and two ; and combuf- 
 tible oxides are compofcd of one or more iimple combuf- 
 tibles combined with a dole of oxygen. Thcfe oxides 
 may be arranged under two heads : viz. thofe which 
 containing only a fngle hnfe combined with oxygen, 
 may therefore be iitrmiijimp>le combuftible oxides ; and 
 thofe which containing more than one bafe, may there- 
 fore be termed compound combuftible oxides. The 
 fimple combuftible oxides are only four in number ; 
 namely, oxide of fulphur, oxide nf phofphorus, charcoal, 
 and carbonic oxide gas. All the fimple combuftible ox- 
 ides are by combuftion converted into acids. The com- 
 pound combuftible oxides include by far the greater 
 number of combuftible bodies ; for almoft all the ani- 
 mal and vegetable fubftances belong to them, and the 
 double bafe is ufually carbon and hydrogen. 
 
 The SUPPORTERS of combujlion are a fet of bodies 
 which are not of themfelves, ill idly fpeaking, capable 
 of undergoing combuftion, but which are abtolutely 
 neceftary for the procefs. All ttie fupporters known 
 at prefent are fix ; viz. i. O'V^en gas ; 2. Air ; 3. Ga- 
 feous oxide of a%ol ; 4. Nitrous gas ; 5. Nitric acid ; and, 
 6. Oxy-muriatic acid. There are other fubftances, to be 
 mentioned afterwards, to which the author gives the 
 name ol partial fupporters ; but all fupporters contain 
 one common principle, namely oxygen. ,. f.', 
 
 The INC0M3USTIBLE BODIES are neither capable of 
 undergoing combuftion themfelves, nor of fupporling 
 the combuftion of bodies that are. Of courfe, ti^key 
 are not immediately connedled with combuftion ; tjut 
 they are noticed here, becaufe fome of the alkalies ahd 
 
 [ 447 ] 
 
 COM 
 
 earths, which belong to this clafs, poffefs certain pro. 
 perties in common with combuftible-i, and are cap. i)!e 
 of exhibiting phenomena fomewhat analogcnis to com- 
 buftion ; phenomena which the author defciibes under 
 the title oi femi-condujlivn. 
 
 From the preceding obfcrvations it is obvious, that, 
 in every cafe of combuftion, there muft be preient a 
 combujlible and a fupporti-r ; and Lavoifier af'certained 
 beyond a doubt, that, during the procefs, the combuf- 
 tible always unites with the oxygen of the fupporter. 
 This new compound ONr author calls a produH of com- 
 buflion ; and maintains that every fuch produ(!'l is either 
 water, or an acid, or a metallic oxide. He admits, in- 
 deed, that other bodies fometimes make their appear- 
 ance during combuftion ; but affirms that thefe, upon 
 examination, will be found neither to be products, nor 
 to have undergone eombutlion. 
 
 But though the combination of the combuftible with 
 oxygen be a conftant part of combuftion, yet the faci- 
 lity witli which combuftibles burn is not in proportion 
 to their apparent afliiiity for that gas. Phofphorus, 
 for inftance, burns more readily than charcoal ; yet 
 charcoal is capable of abftrafting oxvgen from phof- 
 phorus. The combuftible oxides take fire more rea- 
 dily than fome of the fimple combiiftibles. Thus, char- 
 coal burns moreeafily than carbon or diamond ; and al- 
 cohol, ether, and oils, which are all compound combuf- 
 tible oxides, are exceedingly combuftible ; whereas the 
 metals, which are fimple combuftibles, do not burn, 
 when air is the fupporter, but at a very high tempera- 
 ture. This facility of burning combuftible oxides is 
 probably owing to the weak affinity by, which thiir 
 particles are united ; and to the fame caufe, viz. th.c 
 inferiority of the cohefion of heterogeneous particles, 
 is to be attributed the fa6t, that fome of the compound 
 fupporters occafion combuftion in circumftances when 
 the combuftibles would not be afted on hy fimple ftp. 
 porters. 
 
 None of the products of comhuftion are themfelves 
 combuftible, in the ufual and proper acceptation of that 
 word. This, however, is not owing to their being fa- 
 turated with oxygen, for fevcral of them are capable of 
 combining with an additional dofe of it ; but duriiiT 
 this new combination no caloric nor light is ever emit- 
 ted, and the compound formed differs effentially from 
 a mere produH ofcomhuftion, being by the additional 
 dofe of oxygen converted into afupporlir. 
 
 When thi fupporters, thus formed by the combina- 
 tion of oxygen with producls, are made to fupport com- 
 buffion, they do not lofe all their oxygen, but only the 
 additional dofe which cODilhutcd them fupporters. Of 
 courfe they aie again reduced to their original ftate of 
 produds of combuftion ; and as they owe "their proper- 
 ties as fupporters, not to the whole of the oxygen 
 which they contain, but to the additional dole, the au- 
 thor calls them partial fupporters. 
 
 All the partial fupporters with which we are ac- 
 quainted contain a metallic bafis ; for metallic oxides 
 are the only produfts at prefent known capable of com- 
 bining with an additional dofe of oxygen. The fol 
 lowing oxides, which are produdls ofcomhuftion, com- 
 bined each with an additional dofe of oxygen, are par- 
 tial fupporters : I. Red oxide of iron; 2. Yellow oxide 
 of gold ; 3. White oxide of filver ; 4. Red oxide of 
 mercury ; 5. Arfenic acid ; 6. Red and brown oxides 
 
 of. 
 
 Combuf- 
 
 tio'..
 
 C O M [ 448 j COM 
 
 Cr.nibuf- of lead; 7. Black, oxide of manganeft- ; 8, Acidulous combiiltion : Lut in thef^" C2(ci n nezv comitiJ!l>/e h al- 
 
 ''°"- oxide of antimonv ? 9. White oxide of tin. ways evolved. Tlic prccefs is merely an iiUerchange of 
 
 '~~^''~~' Tlius it :r;ipe:ir's that feveral of the prodiiAs of com- combuiUbility ; for the coinbullible is converted into a ^ 
 
 biiftion are capable of comljininp with oxygen ; and produtt only by mean.; of a produft. Both the oxy- 
 
 hence it foKows that the incombulHbility of produAs is gen and the bafc of the produdt having undergone 
 
 not owing to their want of airinity for oxygen, but to 
 fome other caufe. 
 
 Thongh no mere proilufl of combuftion is capable of 
 fvppori'tn^ cambnftion, this is not occafioned by any 
 \vant of affinity for combullible bodies ; for feveral of 
 thefe prodnAs are capable of combining with an addi- 
 tional dofe of their bafes. By this combination, how- 
 ever, they lofe their properties as produfts, and are 
 converted' into comlujlMcs : wlience it follows that the 
 procefi inuft differ efleiidally from that of combuftion. 
 Tlius fulphuric acid, a/»Wu<7 of combuftion, by com- 
 bining with an additional dofe of fiJphur or its oxide, 
 is converted into fulphurous acid ; a fubftance which. 
 
 combuftion, have loft fomething which is efiential to 
 combuftion. The procefs is merely a double decompo- 
 fition. The produft yields its oxygen to the conibuf- 
 tible, while, at the fame time, the combuftible gives 
 out fomething to the bafe of the produft. The com- 
 buftibility of that bale, then, is reftored by tlie lols of 
 its oxygen, and by the reftoration of fomething which 
 it receives from the other combuftible thus converted 
 into a produtl. 
 
 tiofuppor/ercan be produced by combuftion, or by any 
 equivalent procefs. Now as all the fupporters, except 
 oxygen gas, confift of oxygen combined with a bale, it 
 follows as a coniequence, tiiat oxygen may combine 
 
 from many of its properties, Dr Thomfon concludes to with a bafe, without lofing that ingredient, whatever it 
 be combiijiible. Thus alfo phofphoric acid, a prodnd is, which gives occafion to combuftion. The mere aft 
 of combuftion, is capable of combining with phofpho- of combination of oxygen with a bafc, therefore, is by- 
 rated iiydro<'en, and forming phojphcrous acid, a com- no means the fame with combuftion. 
 buftible body. When this laft acid is heated in con- Several of the fupporters and partial fupporters are 
 tail vvith a fupporter, it undergoes combuftion ; but it capable of combining with combuftibles, without un- 
 is only the additional dofe of the combuftible which dergoing decompofition, or exhibiting the phenomena 
 
 onrns, and the whole is converted into phofphoric acid. 
 Hence we fee that it is not the whole bafis of thefe 
 compounds that is combuftible, but merely the addi- 
 tional dofe ; and therefore the compounds themfelvcs 
 may be termed partial com/tii/Iiiks, to indicate, that pari 
 only of the bafe is capable of undergoing combuftion. 
 
 of combuftion. In this manner the yellow oxide of 
 gold, and the white oxide of filver, combine with am- 
 monia ; the red oxide of mercury with oxalic acid j 
 and oxy-muriatic acid with ammonia. Thus alfo nitre 
 and oxy-muriat of potafti may be combined, or at leall 
 intimately mixed with feveral combuftible bodies, as in 
 
 Now, fmce the products of combuftion are capable of gunpowder, &c. In all thefe compounds the oxygen 
 
 combiniuT with oxygen, but never exhibit the pheno- of the fupporter retains each the ingredients proper to 
 
 mcna of combuftion, except when they are in the ftate itfclf, which render them fufceptible of combuftion ; 
 
 of partial combuftibles, combuftible bodies muft con- and hence the compound is ftill combuftible. They 
 
 tain fome principle, which they lofe during combuftion, burn indeed with amazing facihtjf, not only when heat- 
 
 and to which thev owe their combuftibility ; for after ed, but when triturated or ftruck fmartly with a ham- 
 
 they have loft it, they unite to oxygen without exhibit- mer ; and have received, in coniequence, the name of 
 
 ing the phenomena of combuftion. Jetonaiing or fu/minating bodies. 
 
 Thotigh the produSs of combuftion are not capable Such are the properties of the combuftibles, the fup- 
 
 of fupporling combuftion, they not unfrequently part porters, and the products ; and fuch the phenomena 
 
 with their oxygen juft as fupporters do, give it out to which they exhibit when made to aft upon each other, 
 
 combuftibles, and convert them into produfts ; but du- If -we compare together the fupporters and the produila. 
 
 ring this procefs no heat nor light is ever evolved. Wa- 
 ter", for inftance, gives out its oxygen to iron, and con- 
 verts it into black oxide, a produft ; and fulphuric acid 
 gives out its oxygen to phofphorus, and converts it into 
 phofphoric acid. Thus we fee that the oxygen of pro- 
 dufts is capable of converting combuftibles into pro- 
 dufts, juft as the oxygen of fupporters ; but during 
 
 we lliall find that they refemble each other in feverai 
 refpefts. Both of them contain oxygen as an effential 
 part ; both are capable of converting combuftibles into 
 produfts ; and of both feveral combine with combuf- 
 tibles and with additional dofes of oxygen. But they 
 dilfer widely from each other in the phenomena which 
 accompany their aftion on combuftibles. The fuppor- 
 the combination of thelaft only are heat and light e- ters convert thefe bodies into produfts ; and at the 
 mitted. The oxygen of fupporters, then, contains fome- fame time combuftion, or the emiffion of light and heal, 
 thipf which the oxygen of produfts wants. takes place ; whereas the produfts convert combuftibles 
 
 Whenever the whole of the oxygen is abftrafted from into produfts without any fuch cmiflion. Now as the 
 produfts, the combuftibility of their bafe is reftored as ultimate change produced upon combuftibles by both 
 completely as before combuftion ; but no fubftance is thefe fets of bodies is the fame, and as the fubftance 
 capable of abftrafting the whole of oxygen, except a which combines with the combuftibles is in both cafes 
 combullible or a partial combujlilk \ and when this is the fame, namely oxygen, we muft conclude that this 
 done, the combuftible or partial combuftible lofes its oxygen in the fupporters contains fomething which the 
 own comhuftibihty by the procefs, and is converted into oxygen of the produfts wants ; fomething which fepe- 
 a produft. ''^''^s during the paflage of the oxygen from the fuj)- 
 
 From thefe fafts, which have been all eftabliihed by porter to the combuftible, and occafions the combuf- 
 Stahl, Lavoifier, and our author, it follows that the tion, or emiffion of fire, which accompanies this paflage. 
 produfts of combuftion may be formed without aftual The oxygen of fupporters, then, contains foms ingre- 
 ^ dient
 
 gredi'ent is caloric 
 
 The combiijlihles and the produHs alfo refemble each 
 other in feveral rcfpefts. Both of them contain the 
 fame or a fjmilar bafe ; both frequently combine with 
 combuftibles, and likcwife with oxygen : but they dif- 
 
 
 COM [ 449 3 COM 
 
 A'tent w!iicK the oxygen of prodm^l;^ wanti. Many cir- nomena which have been thought inconfifterit with that ''')|]^J;'''' 
 cumftances concur to render it probable that this in- theory. , 
 
 In the year 179^, the alTociated Dutch chcmifta 
 drew the attention of pliilofophers to a curious pheno- 
 nicnon which accompanies the formation of fome ot the 
 fulphurets. When eight parts of copper, iron, lead, 
 tin, or zinc filins^s, and three parts of flowers of ful- 
 
 fer elfentially in the phenomena which accompany their phur, are mixed together in a glafs^ receiver, and the 
 combination with oxygen. In the one cafe, /fr^ is emit- 
 ted ; in the other, not. If we recolleft that no fub- 
 ftance but a comhuftible is capable of refloringcombnf- 
 tibility to the bafe of a produft, and that at its doing 
 fn, it always lofcs its own combullibility ; and if we rc- 
 coUeft farther, that the bnfe of the produft does not 
 exhibit the phenomenon of combuftion even when it 
 combines with oxygen — we cannot avoid concluding, 
 that all combuftibles contain an ingredient which they 
 lofe when converted into produfts, and that this lofs 
 contributes to the lire which makes its appearance du- 
 ring the converfion. Many circumllances concur to 
 render it probable that this ingredient is liGht. 
 
 If we fuppofe that the oxygen of ftipporters contains 
 caloric as an eiTential ingredient, and that /ighl is a com 
 ponent part of all combujlibles , the phenomena of com 
 
 vefl'el placed upon burning coals, the mixture melts, 
 a kind of explofum takes place, it becomes fudJei.ly 
 red hot, and a glow, like that of a piece of red hot 
 charcoal fanned with bellows, rapidly pervades the 
 whole. When this difappears, the mixture is found in 
 the Hate of folid fulphurct of copper, or iron, Sec. The 
 experiment fucceeds whether the ved'el be filled with 
 air, or with azotic or hydrogen gas, or even with wa- 
 ter or mercury. What is fingular in this experiment 
 is the glowing red heat, or the emifiion of fire, which 
 accompanies the combination of the iulphur and metal. 
 This emiflion being the fame which takes place during 
 combuftion, the procefs has been confidered as a com- 
 buftion, and ftated as fuch, by the German chemifts, 
 as an objedtion to Lavoiiier's theory. But our autlior 
 (hews that no objeftion can be urged from this experi- 
 
 buftion, numerous and intricate. as they are, admit of ment againft the truth of that theory as far as it goes ; 
 
 an eafy and obvious explanation. The component j)arts 
 of the oxygen of fupporters are two ; namely, i. A 
 bafe ; and, 2. Caloric. The component parts of com- 
 buftibles are likewife two ; namely, l. A bafe ; and, 2. 
 Light. During combuftion the bafe of the oxygen 
 combines with the bafe of the combuftible, and forms 
 the produft ; while at the fame time the caloric of the 
 oxygen combines with the light of the combuftible, 
 and the compound flies off in the form of fire. Thus 
 combuftion is a double decompofition ; the oxygen and 
 combuftible divide themfelves each into two portions, 
 which combine in pairs ; the one compound is the pro- 
 dull, and the other the^r^, which efcapes. Hence the 
 reafon that the oxygen of produfts is unfit for com- 
 buftion : It wants its caloric. Hence the reafon that 
 combuftion does not take place when oxygen combines 
 with produfts, or with the bafe of fupporters : Thefe 
 
 and that all the phenomena are fully explained by the 
 additions which he has made to it. Thus, we have only 
 to recoUeft, i . That the fulphur is in a melted ftate, 
 and therefore contains caloric as an ingredient ; 2. That 
 the metals which produce the phenomenon contain light 
 as an effential ingredient ; and, 3. That the fulphuret 
 produced is always in a folid ftate — and the explana- 
 tion is llmple and obvious. 'I'ht: fulphur combines with 
 the bafe of the metal, while the caloric, to which the 
 fulphur owed its fluidity, combines with the li^ht of 
 the metal, and the compound flies off under the form 
 oljire. 
 
 Thus the procefs is exaAIy the fame with combuf- 
 tion, excepting what regards the produCl. The melt- 
 ed fulphur afts the part of the fupporter, while the me- 
 tal occupies the place of the cambujlible. The firft fur- 
 nifhes caloric, the fecond light, while the bafes of both 
 
 bodies contain no light. The caloric of the oxygen of combine together. Hence we fee that the bafe of fuU 
 
 courfe is not feparated, and no yfnr appears. Hence phurets (and the fame thing holds of fome phofphurets) 
 
 alfo the reafon why a combuftible alone can reftore refembles the bafe of produfts in being deftitute of 
 
 combuftibility to the bafe of a produft. In all fuch light, the formation of thefe bodies exhibiting the fe- 
 
 cafes a double decompofition takes place. The oxy- paration of fire like combuflion ; but the produdt, differ- 
 
 gen of the produdl combines with the bafe of the com- ing from a produdl of combuftion in being deilitute of 
 
 buftible, wliile the light of the combuftible combines oxygen, our author propofes to diftinguilh the procefs 
 
 with the bafe of the produft." by the title oi femi-comlnflion, to indicate that it pof- 
 
 Such is the theory of Dr Thomfon, propofed to the felTes one half of the charaCleriftic marks of combuftion. 
 
 public* under the humble title of Reniarh on Comhujlion. 
 As the author completely eftabhfhes the fafts on which 
 his reafoning refts, we can conceive to it but one plau- 
 fible objeftion. Why is not the caloric of the oxygen 
 feparated when that gas combines with bodies deftitute 
 of light ? That there is caloric emitted on many oc- 
 
 but is deftitute of the other half. 
 
 COMPASS, or Mariner's Steering Compass, 
 is an inftrument of fo great value, that every improve- 
 ment of it, propofed by men of fcience or of experience, 
 is entitled to notice. We (hall therefore lay before our 
 readers fome obfervations on the defefts of the compafs 
 
 cafions, when no light appears with it, is incontrover- in common ufe, which have fallen into our hands fince 
 
 tible ; but perhaps the matter of light is chemically 
 combined with all bodies which emit heat, though it 
 never flies off but when the heat is great. If this be a 
 faft, and it is not improbable, the theory before us feems 
 to be eftabliftied ; for it not only completes the theory 
 of Lavoifier, but affords an eafy folution to fome phe- 
 .SuppL. Vol, I. Part. II. 
 
 the article in the Encycloptedia was publilhed. The 
 firft; is by Captain O'Brien Drury of the royal navy, 
 and relates entirely to the needle. 
 
 " Experiance (fays this officer) Ihews us, that the 
 needle of a compafs, as well as all other magnjts, whe- 
 ther artificial or real, perpetually lofes fomething of its 
 3 L magnetic
 
 COM [4 
 
 CnmpaiV. magnetic powers, whicli often produces a JifTerence ex- 
 
 ' ceeding it point; and I am well, convinced that the 
 
 great errors in fhip-reckonings proceed more frequently 
 
 from the incorre&nefs of the compafs tlian from any 
 
 other caufe. 
 
 " Steel cannot be too highly tempered for th« needle 
 of a fea-compafs, as the more it is hardened the more 
 permanent is the magnetifm it receives ; but, to pre- 
 ferve the magnetifm, and confequently the polarity of 
 the needle, I recommend to have the needle cafed with 
 thill, Wcll-politlieJ, foft iron ; or elfe to have it armed 
 at the poles with a bit of foft iron. I have found, from 
 many experiments, that the cafed needle prtferved its 
 magnetifm in a much more perfeft degree than the 
 reedU not cafed ; and I have fomt times thought that 
 the magnetic power of the cafed needle had inreafed, 
 while the magnetic power of the uncafed and unarmed 
 needle always lofes of its polarity." 
 
 This is not an opinion taken up at random, but is 
 the rcfult of what appears to have been a fair and ju- 
 dicious experiment ; for our author placed a caftd nee- 
 dle, an armed needle, and one without either cafe or ar- 
 mour, in a room for three months ; each having at that 
 time precifciy the fame direction, and nearly the fame 
 degree of force. At the expiration of the three months, 
 he found that the cafed needle and the armed needle 
 had not in the leaft changed their direction ; hut the 
 other had changed two degrees, and had loft very con- 
 fiderable of its magnetic power. If there was any 
 change in either of the other needles, it was too incon- 
 fiderable to be perceived. 
 
 Thcfe obfervations feem to be new, and may tend to 
 the improvement of the compafs. But it is not with 
 refpe<ft to the needle only that this inllrument is defec- 
 tive. Mr Bernard Romans of Penfacola well obferves, 
 that, on another account, the heavieft brafs compaflTes 
 now in ufe are by no means to be relied on in a hol- 
 low or high fea. This is owing to the box hanging 
 in two brafs rings, corjining it to only two motions, 
 both vertical and at right angles with each other ; by 
 wliich confinement of the box, upon any fuccuflion, 
 more efpecially fudden ones, the card is always put in- 
 to too much agitation, and, before it can well recover 
 itfelf, another jerk prevents its pointing- to the pole; 
 nor is it an extraordinary thing to fee the card unlhip- 
 ped by the violence of the (hip's pitching. 
 
 All thefe inconveniences are remedied to the full by 
 giving the box a vertical motion at every degree and 
 minute of the circle, and compounding thefe motions 
 •with a horizontal one of the box as well as of the card. 
 By this unconhned difpofition of the box, the effefls 
 of the jerks on the card are avoided, and it will always 
 very fteadily point to the pole. " Experience .(fays 
 our author) has taught me, that the card not only is 
 not in the fmalleft degree affeded by the hollow fea, 
 but that, in all the violent (hocks and whirlings the box 
 can receive, the card lies as ftill as if in a room unafTeft- 
 ed by the leaft motion. 
 
 " Lately a compafs was invented and made in Hol- 
 land, which has all thefe motions. It is of the (ize of 
 the common brafs compaffes ; the bottom of the brafs 
 box, inftead of being like a bowl, mud b« raifed into a 
 hollow cone, like the bottom of a common glafs bottle; 
 the vertex of the cone muft be raifed fo high as to leave 
 but" one inch between the card and th« glafs ; the box 
 
 50 ] COM 
 
 niuft be of the ordinary depth, and a quantity of lead Comp-ift. 
 muft be poured in the bottom of the box, round the '~~~v— — 
 bafe of the cone ; this fecures it on the ftilc whereon 
 it traverffs. 
 
 " Tills ftile IS firmly (ixed in the centre of a fquare 
 wooden box, like the common compafs, except that it 
 requires a thicker bottoin. The ftile muft be of brafs, 
 about fix inches long, round, and of the thicknefs of 
 one-third of an inch ; its head blunt, like the head of 
 a fewing-thlmble, hut of a good polldi : the (lile mull 'J 
 
 ftand perpendicular. The inner vertex o^ the cone mull * 
 
 alfo be well poliflied ; the vertical part of the cone 
 ought to be thick enough to allow of a wcll-polinied 
 cavity, fufficient to admit a fhort ftHe, proceeding from 
 the centre of the card whereon it traverfes. The com- 
 pals I faw was fo conftrufled ; but I fee no leafon why 
 the ftile might not proceed from the centre of the ver- 
 tex of the cone, and fo be received by the card the 
 common way. The needle muft be a magnetic bar, 
 blunt at each end ; the glafs and cover arc put on in 
 the common way." 
 
 A compafs of this kind was fubmitted to our au- 
 thor's examination by the captain of a (loop of war, 
 who aftured him, that in a hard gale, which lafted fome 
 days, there was no other compafs of the fmalleft fervice. 
 Mr Romans was fatlsfied that the officer did not pralfe 
 the apparatus more than it deferved ; and we feel our- 
 felves ftrongly inclined to be of the fame opinion. 
 
 It muft not be concealed, however, that the ingeni- 
 ous Mr Nicholfon feems to think very differently of all 
 fuch contrivances. In a paper publifhed in the ninth 
 number of his valuable Journal, he labours to prove, 
 that the compafs is very little difturbed by tilting the 
 box on one fide, but very much by fudden horizontal 
 changes of place ; that a fcientific provifion againft the 
 latter is therefore the chief requilite in a well made in- 
 ftrument of this kind ; and that no other provifion is 
 requilite or can cafily be obtained, than good work- 
 nianfhip according to the common conftruftion, and a 
 proper adjuftment of the weight with regard to the 
 centres or axes of fufpenfion. The fame author is of 
 opinion, that it would greatly improve the compafs to 
 make the needle flat and thin, and to fufpend it, not, 
 as is moft commonly done, with its flat fide, but with 
 its edge uppermoft ; for it being a well-known faft, 
 that foft fteel lofes its magnetifm fooner than hard. It 
 is obvious, that unlefs both fides of a needle be equally 
 hard (which is almoft impofTible if they be diftant from 
 each other), the magnetic power will, in proccfs of 
 time, deviate towards the harder fide. 
 
 The Chinefe Compass has ioine advantages over the 
 European compafs, from which it differs with refpecl 
 to the length of the needle, and the manner in which 
 it is fufpended. In the co.rpafs of China, the magne- 
 tic needle is feldom above an inch in length, and is lefs 
 than a line in thicknefs. It is poifed with great nice- 
 ty, and is remarkably fenfible, or, in other words, points 
 fteadily towards the fame portion of the heavens. This 
 ileadlnefs is accomplilhed by the following contrivance : 
 " A piece of thin copper is ftrapped round the centre 
 of the needle. This copper is rivetted by its edges to 
 the upper part of a fmall hemifpherical cup, of the fame 
 metal, turned downwards. The cup fo inverted ferves 
 as a focket to receive a fteel pivot riftng from a cavity 
 made into a round piece of light wood or cork, which 
 
 thus
 
 
 COM [ 4j:i ] 
 
 iVmpafs, tliiis fcirms the compafs-box. The furfaccs of the foe- COMPOSITION 
 
 ■ ket and pivot, intended to meet each other, are per- 
 _. fcdly polifhed, to avoid, as much as poflible, all friiflion. 
 The cup has a proportionably broad margin, which, 
 befide adding to its weight, tends, from its horizoiitiil 
 pofition, to keep the centre of gravity, in all fitnations 
 of the compafs, nearly in coincidence with the centre of 
 fufpenfion. The cavity, in which the needle is thus 
 fufpended, is in form circular, and is little more than 
 fufficient to remove the needle, cup, and pivot. Over 
 this cavity is placed a thin piece of tranfparent talc, 
 which prevents the needle from being ailedted by any 
 motion of the external air ; but permits the apparent 
 motion of the former to be eafily obferved. The fmall 
 and fhort needle of the chinefe has a material advantage 
 over thofe of the ufual ilze in Europe, with regard to 
 the inclination or dip towards the horizon ; wliich, in 
 the latter, requires that one extremity of the needle 
 fliould be made fo much heavier than the other as will 
 counteraft the magnetic attraction. This being diffe- 
 rent in different patts of the world, the needle can only 
 be accurately true at the place tor which it had been 
 conftrufted. But in fliort and light needles, fufpended 
 after the Chinefe manner, the weight below the point 
 of fufpenfion is more than fufficient to overcome the 
 magnetic power of the dip or inclination in all iitua- 
 tions of the globe ; and therefore fuch needles will ne- 
 ver deviate from their horizontal polition." 
 
 COMPLEMENT, in general, is what is wanting, or 
 neceffary, to complete fome certain quantity or thing. 
 
 jlrilhmeiical Complemenj, is what a number or lo- 
 garithm wants of unity or i with fome number of cy- 
 phers. It is beft found by beginning at the left hand 
 lide, and fubtrafting every figure from 9, except the lafl, 
 or right hand figure, which mufl be fubtradied from 10. 
 So, tlie arithmetical comp. of tbe log. ^■^'^2g'j\^, 
 by fubtrafting from 9's, &c. is 0-4670286. 
 
 The arithmetical complements are much ufed in ope- 
 rations by logarithms, to change iubtratlions into ad- 
 ditions, which are more conveniently performed, efpe- 
 cially when there are more than one of them in the ope- 
 ration. 
 
 Complement, in aflronomy, is ufed for thediflance 
 cf a ftar from the zenith; or the arc contained between 
 the zenith and the place of a tlar which is above the 
 horizon. It is the fame as the complement of the alti- 
 tude, or co-altitude, or the zenith dillance. 
 
 CoMFLEMRM^ cif the Courfe, in navigation, is the 
 quantity which the courfe wants of 90", or 8 points, 
 viz. a quarter of the compafs. 
 
 CoMTLEMEUT oj the Curtain, in fortification, is that 
 part of the anterior fide of the curtain which makes the 
 demigorge. 
 
 CoM?LEMEKT of the Line of Defence, is the remainder 
 of that line, after the angle of the flank is taken away. 
 CoMFLEMENrs of a Parallelogram, or in a Parallelo- 
 gram, are the two leffer parallelograms, made by draw- 
 ing two right lines parallel to each fide of the given pa- 
 tailelogram, through the fame point in the diagonal. 
 
 CoMviEMENT of Life, z term much ufed, in the doc- 
 trine of life annuities, by De Moivre; and, according to 
 him, it denotes the number of years which a given life 
 wants of 86, this being the age which he confidered as 
 ♦ he utmofl probable extent of life. So 56 is the cora- 
 |)lement of 30, and 30 is the complement of 56. 
 
 CON 
 
 OF TKORORTION, according to Comjinli. 
 the jjtli definition of the ^ih book of Euclid's Elc- •'"" 
 ments, is when, of four proportionals, the fum of the 
 firfl and fecond ii; to the iecond> as the fum of the third 
 and fourth is to the fourth. 
 
 Composition of Ratios, is the adding of ratios to- 
 gether : which is performed by multiplying together 
 their corrcfpunding terms, viz. the antecedents together, 
 and the confcquents together, for the antecedent and 
 conlequent of the compound ratio ; like as the addi- 
 tion of logarithms is the fame thing as the multiplica- 
 tion of their corrcfponding numbers. Or, if the ternii 
 of the ratios be placed fradion-wile, then the addition 
 or compofition of the ratios is performed by multiply, 
 ing the tractions together. 
 
 COMPOUND iNTtRKST. See ALCtnsA, Encycl, 
 and Compound jNTEkkiT \n this Supplement. 
 
 CONCEPTION, a city of Chili in South America, 
 was vifited in 178(1 by the celebrated, though unfortu- 
 nate, navigator La Peroufe, who gives an account of 
 fome particulars relating to it very different from what 
 we have given of it under the article Conception, £n- 
 cycl. So far are the Spaniards trom living in fecurity 
 with refpeft to the Indians, that, accordujg to him, 
 they are under continual alarms of being attacked by 
 thole bold and enterpriling lavages. " The Indians of 
 Chill (fa) s he) are no longer thofc Americans who 
 were inlpired with terror by European wnis. The in- 
 creafe of horfes, which are dilperfed tiuough the inte- 
 rior of the immenfe dtlerls of America, and that of 
 oxen and Iheep, which has alfo been very great, liave 
 converted thefe people into a nation of Arabs, in every- 
 thing refembliiig thofe who inliabit the defcrts of Ara- 
 bia. Conflantly on horfeback, they conlider an excur- 
 fion of two hundred leagues as a very fhort journey. 
 They march accompanied by their flocks ; feed upon 
 their flefh and milk, and fometimes upon their blood ; 
 and cover themfelves with their fl<ins, of which they 
 make helmets, cuiraifes, and bucklers. All their old 
 cufloms are laid afide. They no longer feed upon the 
 faille fruits, nor wear the fame drefs ; but have a more 
 ftriking refemblance to the Tartars, or to the inhabi- 
 tants of the banks of the Red Sea, than to their aiicef. 
 tors, who lived two centuries ago. So decilive an in- 
 fiuence has the introduftion of two domeftic aLimak 
 had upon the maimers of that once timid people. It 
 is eaiy to conceive %vhat formidable enemies they mufl: 
 now be to the Spaniard,s ; for fuppoiing them defeated 
 in battle, how is it poflible to follow them in fuch long 
 e«curiions ? How is it poffible to prevent affeinblagcs, 
 which bring together in a fiiigle point nations fcattered 
 over 400 leagues of country, and thus form armies of 
 30,000 men i" 
 
 Of thefe people M. RoUin, furgeon-major of the fri- 
 gate la BvJJale, gives the following phyiiological parti- 
 culars : " They are, in geneial (lays lie), of lower fla. 
 ture, and lefs robuft, than Frenchmen, though they en. 
 dure with great caurage the fatigues of war and all its 
 attendant privations. There is a great famenefs iu the 
 phyliognomy of mofl individuals. The face is larger 
 and rounder than that of Europeans. The features are 
 more ftrongly marked. I'he eyes are fmall, dull, bhek, 
 and deeply felted. The forehead ii low; the eyebrows 
 black and fhaggy ; the nofe fhort and flattened ; the 
 cheek-bones high ; the lips thick j the mouth wide ; 
 3^2 - and
 
 CON [45 
 
 ConceptJor.and the cKin diminutive. The women are (Kort, ill- 
 * ' * ■ ' made, and with difgulling countenantes. Both men 
 and women bore their nofe and ears, which they adorn 
 with glafs or mother-of-pearl trinkets. The colour of 
 their flcin is a reddilh brown : That of their nails is fi- 
 ' milar, but not fo deep. The hair of both is black, 
 coarfc, and very thick. The men have little beard ; 
 but their arm-pits and parts of fex are well furnifhed 
 with hair, which parts, in moft of the women, have 
 none." 
 
 The military governor of Conception, who was an 
 Irlfhman, returned, while M. de la Peroufe was there, 
 from the frontiers of the Spanifh fettlemeiits, where he 
 had juft concluded a glorious peace with the Indians. 
 This peace was highly neceflary to the people of his 
 government, whofe diilant habitations were expofed to 
 the inroads of favage cavalry, whofe praftice it is to 
 maffacre the men and children, and to make the wo- 
 men prifoners. This amiable man, whofe name was 
 Higgulns (probably Biggins), had fucceeded in gaining 
 the good-will ofthefe favages, and thereby rendered 
 the moft fignal fervice to the nation that had adopted 
 him. For while the Indians and Spaniards are at va- 
 riance, an alliance with the former by any of the mari- 
 time powers of Europe would become fo formidable to 
 the latter, as to induce them, for fear of their lives, to 
 abandon their fettlements in Chili, and retire to Peru. 
 This was clearly feen by Monneron the engineer on the 
 expedition, who, with the true fpirit of a Frenchman, 
 pointed out to his government the method of wrefting 
 from its moft faithful ally one of the moft valuable pro- 
 vinces of the Spanilh empire. 
 
 La Peroufe defcribes the common people of Concep- 
 tion as much addifted to thieving, and the women as 
 exceedingly eafy of accefs. " They are a degenerated 
 and mongrel race (fays he) ; but the inhabitants of the 
 firft clafs, the true bred Spaniards, are polite and obli- 
 ing in the extreme. The bilhop was a mac of great 
 snfe, of agreeable manners, and of a charity of which 
 the Spanifh prelates afford frequent examples." He 
 was a Creole, and had never been in Europe. Of the 
 monks our author gives a very different character. 
 ♦« The misfortune (fays he) of having nothing to do, 
 the want of family ties, the profeffion of celibacy, with- 
 out being feparated from the world, and their living in 
 the convenient retirement of their cells, has rendered, 
 and could not fail to render, them the greateft profli- 
 gates in America. Their effrontery is inconceivable. 
 I have feen fome of them ftay till midnight at a ball ; 
 aloof, indeed, from the good company, and feated among 
 the fervants. Thefe fame monks gave our young men 
 more esadl information than they could get elfewhere, 
 concerning places with which priefts ought to have 
 been acquainted only in order to interditk the entrance." 
 M. de la Peroufe reprefents that part of Chili, which 
 is called the Bi/hopric of Conception, as one of the moft 
 fertile countries in the univerfe. Corn yields fixty to 
 one ; the vineyards are equally produftive ; and the 
 plains are covered with innumerable flocks, which, tho' 
 left to themfelves, multiply beyond all imagination. 
 Yet this colony is far from making the progrefs that 
 might be expefted from a fituation fo favourable to an 
 increafe of population. The influence of the government 
 inceffantly counterafts the climate and the foil. Pro- 
 hibitory regulations exift from one end of Chili to the 
 
 fe 
 
 2 ] CON 
 
 other ; and this kingdom, of which the produftione, if Condorcei, 
 
 carried to their higheft pitch, would feed the half of <e—^ 
 
 Europe ; of which the wool would fulfice for the ma- 
 nufactures of Great Britain and France, even when ma- 
 nufafturcs flourilhed in the latter country ; and of 
 which the cattle, if faked dow.i, would produce an im- 
 menfe revenue — is entirely dellitute of commerce, and 
 its inhabitants funk in lloth and indolence. Unlefs, 
 therefore, Spain change its fyftem entirely. Chili will 
 never reach that pitch of profperity which might be 
 expected from its lituation and fertihty. For the lati- 
 tude and longitude of Conception, fee Encycl. 
 
 CONDORCET ( Jean-Antoine Nicolas Caritat de). 
 was born at Ribemont in Picardy, the 1 7th of Septem- 
 ber I 743, of a noble and very ancient family. At the 
 age of 15 he was fent to ftudy philofophy at the col- 
 lege of Navarre, and had the good fortune to fall into 
 the hands of an able profeffor, who has fince diftinguifh- 
 ed hiralelf by his geometrical works. The young Con- 
 dorcet had no relilli for the bufmefs of the firft courfe, 
 for the quibbles of ontology and pneumatology, and 
 all the wretched appendages of fchool metaphyfics : 
 But in the following year, his lludies, being dircfted 
 to the mathematical and phyiical fciences, were entirely 
 congenial to his talle ; and though there were upwards 
 of 120 fcholars, he diltinguiihed himfelf above them 
 all. At Eafter he held a public thefis, at which Clairaut, 
 D'Alembert, and Fontaine, alfifted. He now returned 
 home, but continued to cultivate geometry. To enjoy 
 more opportunities of improvement, he removed in 
 1762 to Paris ; where he attended the chemical courfe 
 of Macquer and Beaume, and frequented the literary 
 focieties which D'Alembert had formed at the houfe 
 of Mademoifelle de Lefpinaffe. 
 
 In 1765, when only 22 years old, he publiftied a 
 work on the Integral Calculus, which difcovered vaft 
 extent and originality of views. Condorcet was already 
 numbered with the foremoft mathematicians in Europe. 
 "There was not (fays Ea Eande) above ten of that 
 clafs ; one at Peterfburgli, one at Berlin, one at Bafle, 
 one at Milan, and five or fix at Paris ; England, which 
 had fet fuch an illuftrious example, no longer produced 
 a fingle geometer that could rank with the former." 
 It is mortifying to us to confefs that this remark is but 
 too much founded in truth. We doubt not but there 
 are in Great Britain at prefent mathematicians equal in 
 profundity and addrefs to any who have exifted fince 
 the illuftrious Newton i but thefe men are not known 
 to the learned of Europe, becaufe they keep their 
 fcience to themfelves. They have no encouragement, 
 from the tafte of the nation, to publifh any thing in 
 thofe higher departments of geometry which have fo 
 long occupied the attention of the mathematicians on 
 the continent. 
 
 In 1767 Condorcet publifhed his.folution of the pro- 
 blem of three bodies ; and in the following year, the firft 
 part of his Analytical Effays ; in which he entered 
 very profoundly into thole arduous queftions. He was 
 received into the academy on the 8th of March 1 769 ; 
 and from that time till 1773 he enriched their annual 
 volumes with memoirs c:i infinite feries, on partial and 
 finite differences on equations of condition, and on 
 other objefts of importance in the higher calculus. It 
 muft be regretted, that he indulged fpeculation per- 
 haps to excefs ; the methods that he propofes for inte. 
 
 gration
 
 CON 
 
 Cwdorctt gration are fometimes of a nature fo extremely general, 
 *"■— V~-^ as to refufe to be accommodated to pradice. Profe- 
 cuting thole rcfearchee for feveral years longer, he com- 
 pofed an ample Treatife on the Integral Calculus, in 
 five parts, comprifing the doftrines and their applica- 
 tion. It was afterwards copied out for the prcls in 
 1785 by Keralio, formerly governor to the Infant of 
 Parma. Only 128 pages were printed ; but the manu- 
 fcript ftill exiUs ; as does that of an elementary Treatife 
 on Arithmetic. It is to be hoped that both of thefe will 
 yet be given to the public. 
 
 His attention was not, however, entirely ahforbed 
 in thofe recondite ftiulies. He publifhed about this 
 time an anonymous pamphlet, intitled A Letter to a 
 Theologian ; in which he replied with keen fat ire to tlie 
 
 r 453 1 
 
 CON 
 
 the lives of thofe /i/vanfr, who, having died before the Condorcet,' 
 renewal of tlie academy in 1699, did not fall in v.ith'"^ — »— ^ 
 the plan of loritcnelle. The fuppn ffion of the hiltory 
 of the academy, or the regular abllradts of the printed 
 memoirs, which he efieded in I 783, afforded him more 
 leifure. In 1787 appeared, yet without a name, his 
 account of Turgoi ; an intllimable piece, whieh, in 
 developing the beneficial views of a virtuous and euligh- 
 tened miniller, exhibits the neateil abltrad oi the prin- 
 ciples of political economy that is extant in any lan- 
 guage. Nearly about the fame time he compofed that 
 elegant life which is prefixed to the fplcnded edition of 
 the works of Voltaire. Condorcet had been elcfted 
 member of the Aiadetme Frangalfe in 1782 ; and his re- 
 putation as a fine writer was fo well eftabliflied, that 
 
 attacks made by the author of the Three Centuries of bookftllers were folieitous to cover their undertakings 
 
 Literature againll the philofophical feft. "But (fub- ' ■' - '^ 
 
 joins the prudent La Lande) he pu filed the matter 
 
 fomewhat too far; for, admitting the juftnefs of his 
 
 fyftem, it was more prudent to confine witiiin the circle 
 
 of the initiated thofe truths which are dangerous for 
 
 the multitude, who cannot replace by found principles 
 
 what they would lofe of fear, of confolation, and of 
 
 hope." Condorcet was now leagued with the atheifts ; 
 
 and /,a Lande , who wiflies well to the fame fedl, cen- 
 
 fures not his principles, but only regrets his ralhnefs. 
 
 He was indeed, as Mr Burke obfervcd, a fanatic atheift 
 
 and furious democratic republican. 
 
 On the loth of June J 773 he was made fecretary of 
 the academy of fciences ; and that important truil he 
 difcharged through the reft of his life with great ability 
 and uncommon reputation. The duties of his office 
 required him to write the lives of the deceafed acade- 
 micians, which he performed with diligence, judgnaent, 
 and univerfal applaufe : And what ipecies of compo- 
 fition IS capable of being rendered fo extenfively ufeful 
 as biography ? In the moft infinuating form it con- 
 veys inftruAion ; and, beftowing vitality and adion on 
 the rules of conduft and on the leffons of virtue, it fires 
 the breaft with the noblelf emulation. The life of a 
 philofopher muft alfo include a portion of the hiftory 
 of fcience. We there trace the fucceffive ileps which 
 led to difcoveries, and learn to eftimate the value of 
 thofe acquifitions by the efforts that were made, and 
 the obftacles that were furmounted. Tlie literati of 
 France have long excelled in the compofition of Eloges : 
 but thofe of Condorcet are of a very fuperlor caft. Re- 
 plete with information and genuine fcience, they main- 
 tain a dignified impartiality, and difplay vigour of Ima- 
 gination, with boldnefs and energy of ftyle. The intrepi- 
 dity (fay his Panegyrills) with which he uttered the fen- 
 timents of truth and of freedom, could not have been ex- 
 pefted from the mouth of an academician under an ab- 
 iblute monarchy. It ceuld not. Indeed, till the prefent 
 eventful age, have been expefted under any government 
 whatever ; for what he called the fcntlments of truth were 
 the dogmas of debafing irreligion, which would not have 
 been permitted in the far-famed republics of Greece and 
 Rome ; and what he dignified with the appellation of 
 the principles of freedom, experience has fliown to have 
 been the immediate fourcc of anarchy, out of which has 
 fprung a defpotifm, the heavieft under which any people 
 have groaned fince the creation of the world. 
 
 Befides the eloges, which properly belonged to his 
 province, Coiidorcet publilhed in a feparate volume 
 
 with the fanftlon of his name. He promllcd an addi- 
 tional volume to the tranflation of Euler's Letters to a 
 German Princefs ; but it was never finlfiied. The part 
 which was printed, amounting to only 112 pages, con- 
 tains the elements of the calculation of probabilities, and 
 a curious plan of a dictionary, in which objefts (hould 
 be arranged by their qualities merely. A new tranf- 
 lation of Smith's celebrated U^ealth of Nations was 
 likewife announced with the notes of Condorcet, tho' 
 he was never heartily engaged about it. On equally 
 flight grounds, his name was lent to the Bibliotheque de 
 I' Homme Public ; and the facility of his temper laid 
 him but too open, at this period, to fuch difingenuous 
 arts. Indeed difingenuous arts feem to be the natural 
 offspring of the prefent philofophy of France ; for the 
 tricks played by Voltaire to his bookfellers, which are 
 well known, would in this country have funk into dif- 
 grace the greateft genius that ever lived ; and the at- 
 tempt of Diderot to cheat the late emprcfs of RuiTia, 
 by felling to her, at an immenfe price, a library, which 
 he pretended to be one of the moll valuable in Eirrope, 
 when he poffeffed not perhaps one hundred volumes, 
 was difingenuity ingrafted on impudence. But to re- 
 turn from this (liort digreffion. 
 
 Thefe literary purfuits did not entirely feduce Con- 
 dorcet from more profound ftudies. At the inftlgation 
 of Turgot, he fought to apply analyfis to quellions of 
 politics and morality. His firft Memoir on Probabili- 
 ties was read to the academy in 1781, He afterwards 
 extended his refearches to the confideration of eleftlons, 
 fales, and fucceiEons ; and digefting thofe remarks and 
 calculations into a fyftematic fliape, he publifhed in 
 1785 a quarto volume, containing the elements of a 
 new and important fcience. 
 
 It is eafy to conceive the intereft that Condorcet 
 would take in the fuccefs of the revolution. Aware of 
 the prodigious Influence of newfpapers, he contributed 
 largely to the Journal de Paris, and the Chronigue, 
 which acquired great celebrity from the elegance of his 
 pen ; and not very long before his death, he began. In 
 concert with the Jamous Sieyes, a Journal of Social In- 
 ftruftlon. In 1791 he wrote a pamphlet in favour of 
 republican government, which procured him a feat in 
 the Leglflative Affembly, and the academy permitted 
 him Hill to retain the office of fecretary. He drew up 
 a manifefto on the fubjedl of the war menaced by the 
 crowned heads ; and a very ample report on public In- 
 ftruftlon, which has in part been lately adopted by the 
 councils of France, He was an early member of the 
 
 Jacobia
 
 CON r 454 1 
 
 Condovcet. Jacobin clul>, that aftive iiiftrument of the revolution : amelcttc. 
 • but jificciving the progredlve ferocity of its meafures, 
 he foriook it in March 1792. 
 
 On the /jthof Auguft, when the king was conduc- 
 ed to the teinpU-, Condorcet was iii\nicd by the Af- 
 fembly to draw up n juflificatory memorial addrefied to 
 all Europe. At the diifolution of that AfTcmbly, he 
 was chofen deputy to the National Convention, and for 
 fijme time atted a diftinguifiied part in its deliberations. 
 He was at the head of the committee appointed to pre- 
 pare the plan of a republican conftitution. But, in the 
 meanwhile, the fadtion of the Mountain, with a pecu- 
 liar energy of charatler, was rapidly acquiring ftrength. 
 The report of.the committee was coldly received — was 
 even treated with contempt ; and, on the jiil of May 
 I~{)3, Robefpierre completely triumphed. 
 
 Duri.-,g the coiiteft between tiie Mountain and the 
 Briiroti.ies, Condorcet maintained a cautious fdence. 
 For eight months he hardly fpoke in the Convention ; 
 and feems to have been fingularly wary in not rifhing 
 an opinion on any party quettion. At length he was 
 fo far roufed by the indignities which the legifiative 
 body daily endured, that he propofed the diflblution of 
 the Convention, and the calling of a new one. This 
 jjrobably exafperated the Mountain to fuch an exccfs, 
 that in a fubfequent infurreftion his printing-office was 
 dellroyed. He was not, however, included in the lift 
 of profcribed deputies; nor was he one of the members 
 who figned the lamous proteil againlt the proceedings 
 on the 3ifl of May. See Revoh;tion [Encycl), n" 
 159. 
 
 But though he could conquer every fentiment of 
 friendfliip, and ftifle every indignant fenfation at the 
 deftruftion of his party, his vanity as an author pro- 
 pelled him to a fatal exertion. When the conftitution 
 of 1793 was accepted, he publilhed jin Addrcjs to all 
 French Ciltzens ; reprobating the extreme rapidity and 
 want of ccnfideration with which it had b;;en framed 
 and accepted, and detailing the numerous afls of vio- 
 lence by which the prevailing party in the Convention 
 had eftablifhed their influence. This rafh ?ft placed 
 him in the power of the Mountain : Cbabot denounced 
 the publication, and moved for a decree of accufation 
 againll Condorcet ; which was immediately granted. 
 
 He efcaped from the arreft, and concealed himfelf 
 nine months in the houfe of a woman in Paris, who, 
 though (lie knew him only by name, had the generofi- 
 tv to rifli her lite, and fullain all the inconveniences 
 a^ifing from her harbouring fuch a gueft. At length 
 a domiciliary vifit was threatened, and he was obliged 
 to quit his afylum. He had the good fortune, though 
 unprovided with a pafiport or civic card, to efcape 
 through the barrier ; when he went to the country- 
 houfe of a friend on the plain of Mont-Rouge. Un- 
 fortunately his friend was at Paris, and not expelled to 
 return in Icfs than three days ; during which the fugi- 
 tive was obliged to wander about, expofed to hunger, 
 «!old, fufpenfe, and the pain ariiing from a wound in 
 his foot. At length his friend returned into the coun- 
 try, and found him ; but confidering it dangerous to 
 take him to his houfe in the day-time, requefted him to 
 wait till night, when he would receive and conceal him. 
 Condorcet, on that day which his friend had fixed as 
 the end of his miferies, forgot the diftates of prudence, 
 and went to an inn at Chemars, where he ordered an 
 
 CON 
 
 His fqualid appearance, dirty cap, torn Condorcet. 
 clothes, leannefs, and voracity, fixed the attention of '*"~'V " ■* 
 a municipal officer, who alked him whence he came, 
 whither he uas going, and it he had a pafiport ? His 
 confution at thcle interrogatoiies betrayed hmi, and he 
 was initantly apprehended. He was coniined that night 
 111 a dungeon, and in the morning was found dead. He 
 always carried about him a dole ot poilon, with which 
 he terminated his life, to avoid a trial before the revo- 
 lutionary tribunal, and fhun the gradual aj>f road of in- 
 evitable deilruflion. 
 
 Thus miftrably perifhed a philofopher, whofe " ge- 
 nius (fays Madame Roland) was equal to the conipre- 
 heniion of the vaflefl lubjefts ; but he had no other 
 charafteriilic bcfides fear. It may be faid of his under- 
 flanding, combined with his perlon, that it was a line 
 cfiencc abforbed in cotton. No one could fay of him, 
 that in a feeble body he difplayed great courage ; for 
 his heart and his conftitution were equally weak. After 
 having deduced a principle, or demonflrattd a fatl, in 
 the Affembly, he would give a vote decidedly oppohte ; 
 overawed by the thunder of the tribunes, armed with 
 inlults, and prodigal of threats." 
 
 It was during the period of his concealment at Pa- 
 ris, uncertain of a day's exiftence, that he wrote his 
 Sketch of the Progreis of the Human Mind ; a pro- 
 dudlion which undoubtedly difplays genius, though it 
 contains fome of the moft extravagant paradoxes ihat 
 ever fell from the pen ot a philofopher. Among other 
 wonderful things, the author inculcates the poiiibiliiy, 
 if not the probability, that the nature of man maygbe 
 improved to abfolutc perfcftion in body and mind, and 
 his exiftence in this world protrafted to immortality. 
 So firmly does he feem to have been perfuaded of the 
 trntii of this unphilofophical opinion, that he fet him» 
 iclf ieriouily to coniider how men fhould conduit them- 
 felves when the population (hould become too great for 
 the quantity of food which the earth can produce; and 
 the only way which he could find for counteracting this 
 evil was, to check population by proniifcuous concubi- 
 nage and otlier practices, with an account of which we 
 will not fully our pages. Yet we are told by La Lande, 
 that this fketch is " only the outline of a great work, 
 which, had the author lived to complete it, would liave 
 been confidered as a monument eretted to the honour oi 
 human nature ! ! !" La Lande, indeed, ipeaks of the 
 author in terms of high refpedt ; and his abilities are 
 certainly unqueilionable : but what fliall we think of 
 the morals of that man, who hiil puriucd with ma- 
 licious reports, and afterwards hired ruffians to aflafTi- 
 nate *, the old Duke of Rochefoucalt, in whofe houfe ^ ~ 
 he had been brought up ; by whom he had been treat- jd/,^ j 
 ed as a fon ; and at whofe folicitation Turgot created 1791. 
 for him a lucrative office ; and by the power of the 
 court raifed him to all his eminence ? There is a living 
 Englifli writer, who has laboured hard to prove that 
 gratitude is a crime. Condorcet muil furely liave held 
 the fame opinion ; and therefore could not blame thofe 
 low-born tyrants who palled againll him what we muft 
 think an unjuil decree of accufation; for it was in fome 
 degree to his writings that thofe tyrants were indebted 
 for their power. 
 
 About the end of the year '786, Condorcet married 
 Marie-Louile Sophie de Grouchy, whofe youth, wit, 
 and Jaeauty, were kfs attractive in the «yes of a philo- 
 fopher
 
 CON [ 455 1 CON 
 
 Conferva fophcr than the tender and courageous anxiety with in tlie Downs, and wliich had brought with them a CcntigioB^ 
 
 II which (lie watched the couch, and aflfunged the fufFcr- fpecies of fever that might in every fenfe of the word — — v— ^ 
 
 Contaijion. .^^_,^ ^^j- ^y^^ ^^^ ^^ ^j^^ prefident du Paty, who had been be termed an epidemy, it will be allowed, that the fuc- 
 
 ' bitten "by a mad dog. This union, however, we arc ccfs wHiich attended it was fuch that it cannot be too 
 
 told, was fatal to his repofe ; it tempted him into the generally known. 
 
 dangfirous "oad of ambition ; and the i<lea of providing The wards were extremely crowded, and the fick of 
 
 for a wife and daughter induced him to feek for offices every dcfcription lay in cradles, proniifcuoiilly arranged, 
 
 wliich once he would have defpifed. to the number of nearly two hundreil ; of which about 
 
 CONFERV.-l juGALis (fee Conferva, ^no'"^/.) is one hundred and fifty were in diilerent (lages of the 
 
 introduced here merely on account of a curious circum- above malignant fever, which was extremely contagious, 
 
 ftance refpeftina; it, which was communicated, not long as appeared evident from its rapid progrcfs and fata! ef- 
 
 asjo, to the Philomatlc Society at Paris. Citiz.ens feils among the attendants on the fick and the fliip's 
 
 Charles and Remain Coquebert having colledled fome company. 
 
 of this Conferva in the neighbourhood of Paris, afcer- The utenfils and materials provided for the ])rocefs 
 tained, by means of an excellent microfcope, conflruft- vvere the following: A quantity of fine fand, about two 
 ed by Nairne and Bluut, that, in this fpecies, there are dozen quart earthen pipkins, as many common tea- 
 male and female filaments, which unite by an aftual co- cups, fome long flips ot glafs to be ufed as fpatulas, a 
 pulation ; that certain globules contained in the male quantity of concentrated vitriolic (fulphuric) acid, and 
 filaments pafs into the interior part of the female fila- a quantity of pure nitre (nitrat of potafii). 
 ments ; and that by this union there are formed in the The proccfs was conducted iu the following manner: 
 latter feeds, or, if we may ufe the expreiTion, fmall ova, ijl. All the ports and fcuttles were fliut up ; the fand, 
 which reproduce the fpecies. This is the firft inftance, which had been previoufly heated in iron pots, was then 
 in the vegetable kingdom, of a reproduftion abfolutely fcooped out into the pipkins by means of an iron ladle; 
 analogous to that which we find among animals. — Phi- and iit this heated fund, in each pipkin, a fmall tea-cup 
 Jo/ofihical Magazine, N° 3. was immerfcd, containing about half an ounce of the 
 May this fa£l be depended on ! We quellioti not, in fulphuric acid, to which, after it had acquired a proper 
 the flighted degree, the veracity of the editor of the degree of heat, an equal quantity of nitrat of pot a fh in 
 very refpeftable mifcellany from which we have copied powder was gradually added, and the mixture ftirred 
 it ; but we confefs ourfelves inclined to admit the phy- with a glafs fpatula till the vapour arofe from it in con- 
 fiological difcoveries of citizen philofphers with great fiderable quantity (a). The pipkins were then carried 
 hefitation. The faft, if real, is certainly curious, and through the wards by the nur^js and convalefcents, who 
 rnay lead to important conclufions; and we therefore re- kept walking about with them in their hands, occafion- 
 commend an inveftigation of its truth to our botanical ally putting them under the cradles of the lick, and in 
 readers. • every corner where any foul air was fupefted to lodge. 
 CONGELATION. See Chemistry in this Sup- In this manner they continued fumigating, until the 
 plement, n" 180 — 28:5. whole fpace between decks was fore and aft filled with 
 
 CONTAGION (fee EncycJ.) is a fubjeft on which the vapour, which appeared like a thick haze, 
 much has been «-ritten to very little purpofe. Of B*ll The vapour at firfl excited a good deal of coughing 
 
 the attempts which have been made to account for it, among the patients, which gradually ceafed as it bf- 
 
 , there is not one that can be thought fatisfaftory. This, came more generally difFufed through the wards ; part 
 
 however, is not perhaps a matter of great importance, of this effeft, however, was to he attributed to the in- 
 
 if a method could only be difcovered to ftop the pro- attention of thofe who carried the pipkins, in puttiuir 
 
 grefs of contagion where it is known to have place, them too near the faces of the fick; which caufcd them 
 
 Among the many benefits which may be reaped from to inhale the ftrong vapour as it immediately iflued from 
 
 the late difcoveries in chemiftry, even this defideratum the cups. 
 
 promifes to be one ; and we furely need not add one of The body-clothes and bedclothes of the fick were as 
 
 the greateft. Dr James Carmlchael Smyth, phyficlan mucli as pofTible expofed to the nitrous vapour during 
 
 extraordinary to his Majelly, fuggelled, in the year the fumigation ; and nil the foul linen removed from 
 
 1795 "'' '7961 3 proceis for determining the effeft of them was immediately immerfed in a tub of cold water, 
 
 the nitric acid in deftroying contagion; and experi- afterwards carried on deck, rlnfcd out, and hung up till 
 
 ments, according to his directions, were made on board nearly dry, and then fumigated before It was t:iken to 
 
 the Union and other (hips at Sheernefs. the wa(h-houfe : a precaution extremely neceffary in 
 
 The Union was an holpltal (hip, and the experiment every cafe of infeftious diforder. Due attention was 
 
 on board her was condufted,by Mr Menzies, Lite fur- alfo paid to cleanlinefs and ventilation. 
 geon to his Majefty's (loop Difcovery, and by Mr Baf- It took about three hours to fumigate th.e fliip. In 
 
 fan, furgeon of the Union; and when it is confidered about an hour after, the vapour having entirely fubfi- 
 
 that frefh contagion was Ailly pouring into the hofpital ded, the ports and fcuttles were thrown open for the 
 
 from the Ruffian vefTela, wliich were at that time lying admiffion of frcffi air. It could plainly be perceived 
 
 that 
 
 (a) That the fumes of the mineral acids poflefTed the property of flopping contagion was proved by Morveau- 
 as far back as the year 1773, who, by means of the fumes of muriatic acid extricated from the muriat of foda- 
 (fea fait) by the fulphuric acid, purified the air of the cathedral of Dijon, which had been fo mucli infeftcd by. 
 exhumations .hat they were obliged to abandon the building. See Chemistry, n 426. in this Sup^l.
 
 CON [ 456 ] C 
 
 Coma»ion, that the sir of the hofpital was greatly fvvect?ned even which it may be employed 
 •"""' by this fiift fumigatioij. The procefa was repeated 
 again next morning ; and the people employed, being 
 now better acquainted with it, were more expert, and 
 finifhed the whole in abiut an hour's time. In an 
 hour afterwards, the vapour having entirely fubfidi-d, 
 the frefh air was freely admitted into the hofpital as 
 before Fewer pipkins were employed for the evening 
 fumigations than for thofe of the mornings, as the freih 
 air could not be admitted fo freely after the former as 
 the latter. 
 
 The pkafing and immediate eflFeft of the fnmigation 
 in deftroying the ofFenfive and difagreeable fmell, arifing 
 from fo many fick crowded together, was now very 
 perceptible, even to the nurfes and attendants ; the con- 
 fequence of which was, that they began to place fome 
 degree of confidence in its efficacy, and approached the 
 cradles of the infefled with lefs dread of being attack- 
 ed with the diforder : fo that the fick were better at- 
 tended, and the duty of the hofpital was more regular- 
 ly and more cheerfully performed. In fliort, a plealing 
 gleam of hope feemed now to cafl its cheering influence 
 over that general defpondency, which was before evi- 
 dently piftured in every countenance, from the dread 
 and horror each individual naturally entertained of be- 
 ing, perhaps, the next victim to the malignant powers 
 of a virulent contagion. 
 
 It is 3 remarkable fact, that from the 26th of No- 
 vember 1795, when the fumigation was firft reforted 
 to, till the 25th of December, not a perfon on board 
 was attacked with the fever, though, in the three 
 months preceding, more than one-third of all the people 
 in the fliip had been feized with the diftemper, and of 
 thefe more than one in four were carried oft by it ; and 
 the probability is, that the ficknefs and mortality would 
 have gone on, increafing in proportion to the diffufioij 
 of the contagion, and to the increafing defpondency of 
 the people, who confidered themfelves as fo many devo- 
 ted viftims. 
 
 The advantage of the fumigation was not felt by the 
 fhip's company and attendants alone, whom it preferved 
 from the baneful effefts of the fever : the fick and con- 
 valefcents derived almoft an equal benefit from it. The 
 fymptoms of the difeafe were meliorated, and loft much 
 of their malignant appearance ; and the advantage of a 
 pure air, and free from ftench, to convalefcents, may be 
 readily conceived. 
 
 Great confidence is always dangerous. It proved fo 
 on the prefent occafion. On the 1 7th of December 
 they imagined themfelves fo fecure, that they difcon- 
 tinued the cuftom of fumigating morning and evening, 
 thinking that once a day was fufficient. On the 25th, 
 one of the nurfes fuffered a flight attack; and on the 
 26th, a marine, who, for a week before, had been in a 
 ftate of intoxication, was feized with the fever, of which 
 he died. Thefe two accidents gave immediate alarm : 
 they returned again to the praftice of fumigating twice 
 a-day ; and from that time to the extermination of the 
 diforder, there was not an inftance of a perfon fuffering 
 from contagion on board the (hip. 
 
 The fuccefs of the experiment was not confined to 
 the Union : the power of the nitrous vapour to deftroy 
 contagion was equally difplayed on board the Ruffian 
 fliipsin which it was employed. The fafety, too, with 
 
 o 
 
 in any fituatioti, without 
 inconvenience or riflv of fire, is another great recom- 
 mendation in its favour. 
 
 From the dtfcription that has been given of the pro- 
 cefs, no perfon can be at any lofs in refurting to the 
 fame kind of fumigation. It is only neceflary to ob- 
 ferve, for the fake of thofe who may not be verfant io 
 chemical purfuits, that the ingredients ought to be 
 pure, and that metal veffels or rods inuft not be em- 
 ployed. Any kind of metal getting among the ingre- 
 dients would caule the vapour to be very noxious in- 
 ftead of falutary. The fumes that rife (hould be white; 
 if they are of a red colour, there is reafon to fjfpedt the 
 purity of the ingredients. 
 
 The importance of this difcovery need not be infifted 
 on : it is equally applicable to e\ery fpecies of putrid 
 contagion, even to the plague itfelf. It (hould there- 
 fore be ufed in all hofpitals and parifh workhoufes ; and 
 (hould be conftantly relbrted to by the proprietors of all 
 large works, on the firft appearance ot infeitious difeafe 
 among the people employed in them : — Indeed, it (hould 
 be employed even as a preventive in all fituations where 
 a number of people, from the nature of their bufinefs, 
 are obliged to be crowded together, or where, from lo- 
 cal circumftances, there are reafons for fufpefting that 
 the purity of the air is injured by noxious exhalations 
 or other caufes. If there be any circumftances in which 
 its utility may be called in queftion, it can only be in 
 cafes of inflammatory difeafes ; for in fuch fuperoxyge- 
 nation has been found hurtful. 
 
 CONTRA-Harmonical Proportion, that relatioH 
 of three terms, in which the difference of the firft and 
 fecond is to the difference of the fecond and third, as 
 the third is to the firft. Thus, for inllance, 3, 5, and 
 6, are numbers contra-harmonically proportional; for 
 2 : I : : 6 : 3. 
 
 CoNTkA-Mure, in fortification, is a httle wall built 
 before another partition wall, to ftrengthen it, {o that it 
 may receive no damage from the adjacent buildings. 
 
 COOPER, an artificer who makes coops, caflcs, 
 tubs, or barrels, i. e. all kinds of wooden veffels bound 
 together by hoops. See Encycl. 
 
 The art of the cooper appears to be of great anti- 
 quity, and to have very foon attained to all the perfec- 
 tion which it poflfefTes at prefent. This being the cafe, 
 it is obvious that we can communicate .10 inftruftion to 
 the cooper himfelf, and, on the fubjeft of his art, very 
 little that could be interefting to our other readers. In 
 the Encyclopedie Methodique there is a long and vcrbofe 
 account of the tools or inftruments employed by the 
 cooper ; of the kinds of timber proper for the different 
 kinds of cadfs ; of the methods of preparing the wood 
 for his various purpofes ; of the manner in which he 
 ought to hold the plane when dreffing the ftaves ; and of 
 the time when it is proper to put the ftaves together, 
 or, in other words, to mount the caflc. From this de- 
 tail we fliall extraft fuch particulars as appear to us to 
 be leaft generally known, though perhaps of no great 
 importance in themfelves. 
 
 Notwithftanding the antiquity of the art of cq/k- 
 building, there are fome countries in which even now it 
 is wholly unknown ; and others where, though it is 
 fufficiently known, yet, from the fcarcity of wood or 
 fome other caufe, earthen veffels, and ikins lined with 
 
 pitch. 
 
 II 
 
 Cooper.
 
 GOO [ 457 ] cot 
 
 Cooper, pitch, arc prefentd to wooden barrehi for the holding ment of a circle or not, and therefore the eoojrfr vcr^' 
 
 "~~v~— and tianfportiiig of liquors. The Latin word t/o/ium, feldom takes that trouble. 
 
 vsliich wc tranilate " a caflc," was tmplo) cd by the 'I'hc Haves being all dreffed and ready to be arran- 
 Roiiians to denote earthen vcflcis ufed for tliis purpofe ; ged in a ciiciilar form, it might be thought iicceffjr)', 
 though tlie word da/are, from which it is derived, ap- in order to make the feams tight, to trim the thin 
 plies very well to our caflis, which are compoled of fe- edges, vvhieli are to be joined together, in fuch a man- 
 veral pieces of wood hewn from the fame tree, and fit- ner as that a ray paffing trom the outfide of the c.ilk 
 ted by planes before they be joined together. We are through a feam to the centre, (hould touch the conti- 
 indeed certain that caflts of the fame kind with our guous Haves from the exterior to the interior fide; in 
 own were in ufe among the Romans before the Cluif- other words, that the tiu'n edges fhould be doped as tlic 
 tian era ; for both Varro and Columella, in treating of arcliftones of a bridge are Hoped, fo that the contigu- 
 the rural economy of their days, fpeak of veiTels formed ous Haves may be brought into firm contaft throughout 
 of feveral Haves of wood bound together by circles or the whole joint. This, however, is not the praftice of 
 hoops. The merit ot having invented fuch velfels is the cooper. With great propriety he brings the con- 
 given by Pliny to certain people who lived at the foot tiguous Haves into contaft at their inner furfaces only ; 
 of the Alps, and who in his days lined their cafks with fo that by driving the hoops hard, he can maki-. the 
 pitch. joints much clofer than he could poffibly have done had; 
 
 At what period the fabrication of calks was introdii- the edges of the Haves been fo (loped as to permit them 
 
 ced into Britain is unknown to us, though it is probable to touch each other throughout before being drove to- 
 
 that we derived the ait trom the French, vvlio might gether by the comprtfiion of the hoops. This, toge. 
 
 have it from the Romans. ther with giving to the Haves the proper curvature. 
 
 We need hardly inform any of our readers, that a feems to be the only part of the cooper's work which 
 
 calk has the appearance of two truncated cones joined dcferves the name of art ; for the drfving of the hoops 
 
 at their bafes, or that the part where the junction ap- and the forming of the bottoms could certainly be ac- 
 
 pears to be made being the moH capacious, or that of compliHied bv any carpenter, we had almoH faid by 
 
 which the diameter is the largeil, is vulgarly called the any man, though he hud never fccn a hoop driven or a 
 
 belly of the cailc. Thefe cones, however, were they bottom formed. 
 
 completed, would not be regular, but rather conoids, be- In many parts of Scotland, inftead of ale or beer 
 
 ing formed of pieces of timber, or Haves, which are not mugs, they ufe fraall hooped wooden veffcls, of which 
 
 ftraight lines 3£ in the cone, but are curved from the the Haves are feather-edged or dove-tailed into one aii- 
 
 vertex to the bafe. other. This, as the Haves are of different colours, in- 
 
 In choofing his wood, if he can have a choice, the creafes the beauty of the vcfTe!, and to a fuperficial ob- 
 
 cooper prefers old and thick and Hraight trees, from fervcr appears to be an ingenious contrivai.te ; but it 
 
 which he hews thin planks to be formed into Haves ; adds rothing to the Hrength or tightnefs of the feam, 
 
 and in France, where this art is praftifed on a large and catinot be attended with the fniallcft difiiculty. We 
 
 fcale, the winter months are allotted for the prepara- think, indeed, that in a large calk or tub it would 
 
 tion of the Haves and bottoms, and the fummer for put- prove injurious to the feam ; for either thefe dove-tails 
 
 ting them together or mounting the cailc. 'i'he author muH be very thin Hips raifed from the interior edges of 
 
 of the article in the Encyclopedie Methodique dirctls the the Haves, which in many cafes could not be done if the 
 
 cooper, when dreffing the Haves with the plane, to cut wood were thoroughly feafonej ; or if they be cut out 
 
 the wood always acrofs ; a praftice which we doubt like inverted wedges, the contiguous Haves muH be 
 
 not is proper, tliough we think it would not be eafy to brought into contacl from the iutejior to the exterior 
 
 alfign the reafon of it. Plaining is the moH laborious fide previous to the driving of the hoops ; and in that 
 
 and difficult part of the work ; and there are but few cafe, as we have fecn, the feams could not be made 
 
 coopers who plane quickly, and at the fame time well, completely tight. 
 
 In Hiops where the work is diHributed into parts, plain- COPERNICUS (Nicolaus), the reftorer, if not the 
 
 jng is reckoned a great objeA ; and in France, before inventor, of the true fyHem of the fun, holds fo confpi- 
 
 the revolution, a good plainer gained from three fiiil- cuous a place in the republic of feienee, that every man 
 
 lings and threepence Herling to four Hiilliugs and three of a liberal education muH be intcrelled both in the 
 
 farthings a-day. events of his life and in the liiHory of iiis difcoveries. 
 
 In forming the Haves, it muH never be forgotten that Accordingly, in the Encyclopredia, we have given a 
 
 each is to coiiHitute part of a double conoid ; that it fliort Iketch of his hiHory, as well as an account of what 
 
 muH therefore be broadcH at the middle, becoming gra- led him to fuppofe the fun placed in the centre of our 
 
 dually, though not in Hraight lines, narrower towards fyHem (fee Copernicus, and Astkonomy, n° 22. 
 
 the extremities; that the outfide acrofs the v^^ood muH Eniycl.) Since thefe articles were publidied, Dr Adam 
 
 be wrought into the fegment of a circle ; and that the Smith's EJays on Pljilofapljical Suhjids have been given 
 
 Have muH be thickeH near the middle, growing thinner, to the world ; and in that which is intitled The Hijlorj 
 
 by very gentle degrees, towards the ends. To adjuH of JJlronomy, we have an account of Copernicus's dif- 
 
 accurately thefe different curves (for even the narrow- coveries, fo much more perfpicuoiis and I'.itisfaCtory thai 
 
 mg of the Haves muH be in a curve) to the fize and in- any thing which v/c have elfewiitre feen on the fubiecl, 
 
 fended Hiape of the cafic, would require citlier great ex- that we are perfuaded our readers will be pleafcd to 
 
 perience, or a larger portion of mathematical fcience meet with it here. 
 
 than we have reafon to think that many coopers pof- " The confufioii (fays Dr Smitli,) in which the ril.l 
 
 fefs. Witii refpccl to the infidc of the Have, it is of hypothefis rcprefented the heavenly bodies, was, as Co 
 
 little confequence whether it be rounded into the fee- peiiiicui liimfi'.f tells us, what firit f'Ji;gefted to him ih< 
 
 Coi'Orii'ciin. 
 
 SnppL. Vol. I. Part II. 
 
 3M 
 
 he 
 dcfiga
 
 COP 
 
 [ 4J8 ] 
 
 COP 
 
 Copernicus. defign of forming a new fyftem, that thefe, the noblefl 
 ''"""' works of Nature, might no longer appear devoid of that 
 harmony and proportion which difcover themfelves in 
 Iier meancft productions. What mod of all difTatisfied 
 liim was, tlie notion of the equalizing circle, which, by 
 reprelenting the revolutions of the celcilial fpheres as 
 equable only, when furveyed from a point that was dif- 
 ferent from their centres, introduced a real inequality 
 into their motions ; contrary to that moil natural, and 
 indeed fundamental idea, with which all the authors of 
 nllronomical fyilems, Plato, Eudoxus, Ariftotle, even 
 Hipparchus and Ptolemy themfelves, had hitherto fet 
 out, that the real motions of futh beautiful and divine 
 objetls muft neceflfarily be perfectly regular, and go on 
 in a manner as agreeable to the imagination as the ob- 
 jefts themfelves are to the fenfes. He began to confi- 
 der, therefore, whether, by fuppofing the heavenly bo- 
 , dies to be arranged in a difTercnt order from that in 
 
 which Ariftotle and Hipparchus had placed them, this 
 fo much fought for uniformity might not be beftowed 
 upon their motions. To difcover this arrangement, he 
 examined all the obfcure traditions delivered down to 
 us, concerning every other hypothefis which the ancients 
 had invented for the fame purpofe. He found, in Plu- 
 tarch, that fome old Pythagoreans had reprefented the 
 earth as revolving in the centre of the univerfe, like a 
 wheel round its own axis ; and thit others, of the fame 
 feil, had removed it from the centre, and reprefented it 
 as revolving in the ecliptic like a flar round the central 
 fire. By this central fire he fuppofed they meant the 
 fun ; and though in this he was very widely miltaken, 
 it was, it feems, upon this interpretation that he began 
 to confider how fuch an hypothefis might be made to 
 correfpond to the appearances. The fuppofed autho- 
 rity of thofe old philofophers, if it did not originally 
 fuggeft to him his fyilem, it feems at leaft to have con- 
 firmed him in an opinion which, it is not improbable, 
 he had before hand other reafbns for embracing, not- 
 wlthilandlng what he himfelf would affirm to the con- 
 trary. 
 
 " It then occurred to him, that if the earth was fup- 
 pofed to revolve every day round its axis, from weft to 
 eaft, all the heavenly bodies would appear to revolve, in 
 a contrary direftion, from eaft to weft. The diurnal 
 revolution of the heavens, upon this hypothefis, might 
 be only apparent ; the firmament, which has no other 
 fenfible motion, might be perfectly at reft ; while the 
 fun, the moon, and the five planets, might have no 
 other movement befide that eaftward revolution which 
 is peculiar to themfelves. That, by fuppofing the 
 earth to revolve with the planets round the fun, in an 
 orbit, which comprehended within it the orbits of Ve- 
 nus and Mercury, but was comprehended within thofe 
 of Mars, Jupiter, and Saturn, he could, without the 
 embarrafiment of epicycles, conneft together the appa- 
 rent annual revolutions of the fun, and the direft, re- 
 trograde, and ftationary appearances of the planets ; 
 that while the earth really revolved round the fun on 
 one fide of the heavens, the fun would appear to re- 
 volve round the earth on the other ; that while (he 
 really advanced in her annual courfe, he would appear 
 to advance eaftward in that movement wiiich is peculiar 
 to himfelf. That, by fuppofing the axis of the earth 
 to be always parallel to itfelf, not to be quite perpen- 
 dicular, but fomewhat inclined to the plane of her or- 
 
 bit, and confequently to prefent to the fun, the one Crpenicuj. 
 pole when on the one fide of him, and the ether when '— -y-— ^ 
 on the other, he would account for the obliquity of 
 the ecliptic ; the fun's feemingly alternate progreflion 
 from north to fouth, and from louth to north, the con- 
 fequent change of the feafons, and different lengths of 
 days and nights in the different feafons. 
 
 " If this new hypothefis thus connctled together all 
 thefe appearances as happily as that of Ptolemy, there 
 were others which it connefted together much better. 
 The three fuperior planets, when nearly In conjunction 
 with the fun, appear always at the greateft diftance from 
 the earth, are fnialleft, aijd leaft fenfible to the eye, and 
 feem to revolve torward in their direft motion with the 
 greateft rapidity. On the contrary, when in oppofi- 
 tlon to the fun, that is, when in their meridian about 
 midnight, they appear nearcft the earth, are largeft, and 
 moft fenfible to the eye, and feem to revolve backwards 
 in their retrograde motion. To explain thefe appear- 
 ances, the fyftem of Ptolemy fuppofed each of thefe 
 planets to be at the upper part of their feveral epicy- 
 cles In the one cafe, and at the lower in the other. 
 But it afforded no fatisfaftory principle of connexion, 
 which could lead the mind eafily to conceive how the 
 epicycles of thofe planets, whofe fpheres were fo diftant 
 from the fphere of the fun, fhould thus, if one may fay 
 fo, keep time to his motion. The fyftem of Coperni- 
 cus afforded this eafily, and like a more fimple machine, 
 without the affiftance of epicycles, connefled together, 
 by fewer movements, the complex appearances of the 
 heavens. When the fuperior planets appear nearly in 
 conjunftion with the fun, they are then in the fide of 
 their orbits, which is almoft oppofite to, and moft dif- 
 tant from, the earth, and therefore appears fmalleft and 
 leaft fenfible to the eye. But as they then revolve in 
 a direftion which is almoft contrary to that of the 
 earth, they appear to advance forward with double ve- 
 locity ; as a (hip that fails in a contrary direition to 
 another, appears from that other to fall both with its 
 own velocity and the velocity of that from which it is 
 feen. On the contrary, when thofe planets are in op- 
 pofitlon to the fun, they are on the fame fide of the fun 
 with the earth, are neareft it, moft fenfible to the eye, 
 and revolve la the fame direttlon with it ; but ae their 
 revolutions round the lun are flower than that of the 
 earth, they are neceflarlly left behind by it, and there- 
 fore feem to revolve backwards; as a ililp which fails 
 flower than another, though it fails In the fame direct 
 tion, appears from that other to fail backwards. After 
 the fame manner, by the fame annual revolution of the 
 earth, he connected together the direft and retrograde 
 motions of the two inferior planets, as well as the fta- 
 tionary appearances of all the five. 
 
 " Thus far did this new account of things render the 
 appearances of the heavens more completely coherent 
 than had been done by any of the former lyftems. It 
 did this, too, by a niuie fimple and intelligible, as well 
 as mure beautiful machinery. It reprefented the fun, 
 the great enllghtencr of the univerle, whofe body was 
 alune larger thnn all the planets taken together, as efta- 
 blilficd immoveable in tlie centre, iTieddlng light and 
 heat on all the worlds that circulated around him in 
 one uniform direftlon, but in longer or (horter periods, 
 according to tht Ir dlfterent dlftances. It took away 
 the diurnal revolution of the f .,"•;' inent, whofe rapidity, 
 
 upon
 
 c o ^ 
 
 r 459 ] 
 
 COR 
 
 Copenii-us. upon the oIJ Iiypothcfis, wns beynnJ what even thought prejudices of hahft and education, was at firft coldly re- Copper, 
 
 ' could conceive. It not only delivered the imagiiiaiiuii 
 from the emban-afTment of epicycles, but troni the diffi- 
 culty of conceiving thefe tv\-o oppoiite motions going 
 on at the fame time, which the fyllem of Ptoltmy and 
 Arillode beftowed upon all the planets ; I mean, their 
 diurnal wcilward, and periodical eaftward revolutions. 
 
 ceivea, or 
 
 utterly lejected, by every clafs of men. The 
 allroiyanicrs alone favoured it with tlieir notice, thougii 
 rather as a convenient hypotheiis than an important 
 truth. By the vulgar it was conlldered as a ciumera, 
 belied by tlie clearelt evidejice of our fenles ; while the 
 learned beheld it with dil'dain, bteauie it militated 
 
 C'.rlt. 
 
 The earth's revolution round its own axis took away againll the fanciful diltin6lions and the vague erroneous 
 the neceflity for fuppofing the firft, and the fecond was tenets ot tlie Peripatetic pliilofophy, wiiich no one had 
 eafily conceived wiien by itulf. The five planets, which ventured to call in queftion ; and it is aniufing to ob- 
 feem, upon all other fyftems, to be objeds of a fpecies ferve with what dexterity the Cipernieans, Hill ufing 
 by theinfelves, unlike to every thing to wliich the ima- the fame weapons, endeavoured to pany the blows of 
 gination has been accullomed, when fuppofed to revolve their antagoniils. Its real merits and blemilhes tippcar 
 along with the earth round the fun, were naturally ap to have been overlooked by both parties. Brahc 
 prehendtd to be objeCls of the fame kiinl with the earth, framed a fort of inlernicdiatc fyftem ; but this Danilh 
 habitable, opaque, and enlightened only by the rays of allronomer was more, remarkable for his patience and 
 the fun.- And thus this hypothefis, by elalfing them in Ikill in obferving the heavens, than for his talents of 
 the fame fpecies of things, with an objert that is of all philolophical !uvell;gation, 'I'owards the commence- 
 othcrs tlie moll familiar to us, took off that wonder and mcnt ot the i6th century, a new order of things emer- 
 uncertainty which the ilrangenefs and fingularity of ged. The fyftem ot Copernicus became generally known 
 their appearance had excited ; and thus far, too, better and daily made converts. Its reception alarmed the 
 aiifwered the great end of philoiophy. ever-watchful authority of the church, rwufcd her jea- 
 
 " Neither did the beauty and fimplicity of this fyftem loufy, and at length provoked 4ier vindictive artiilerv. 
 alone recommend it to the imagination ; the novelty The ultima ratio ilnologorum was pointed at the head of 
 and unexpeilednefs of that view of nature which it the illuftrious Galileo, whofe elegant genius difcovered 
 
 oi)ened to the fancy, excited more wonder and furprife the laws of motion, extended tiie fcience of mechanics, 
 
 than the ftrangcft of thofe appearances, which it had and added luftre and folidity to the true fyftem of the 
 
 been invented to render natural and familiar, and tliefe univerle. From the ftorms of perfecutioii Copernicus 
 
 fenthnents ftill more en-leared it. For though it is tlie himfelf had been exempted only by a timely death, 
 end of philofophy to allay that wonder which either the COPPER, one of the metals ; for the properties of 
 
 unufual or feemingly disjointed appearances of Nature which, fee Ch tMisruv/nf/cx in this Supplement. 
 
 excite, yet (he never triumphs fo much as when, in or- The Chinefe have a metal which they ciiW. pr-ltw^, but 
 
 der to conneft together a few, in theml'elves perhaps which Sir George Staunton denominates 
 inconhderable objefts, (lie has, if I may fay hi, created White Copre.R. This metal has a beautiful filver- 
 
 a.iother conftitution of things, more natural indeed, and like appearance, and a very clofe grain. It takes a fine 
 
 fuch as the imagination can more ealily attend to, but polilh, and many articles of neat workmanlhip, in imi- 
 
 more new, more contrary to common opinion and ex- tation of filver, are made of it. An accurate analyfis has 
 
 peflation, than any of thofe appearances thcmfelves. As determined it to confiil of copper, zinc, a little 01.- r • 
 
 in the; inftance before us, in order to conneft together and in fome fpecimens a few particles of iron and of 
 
 foine feeniing irregularities in the motions of the pla- nickel have been found. From this account it woiJd 
 
 nets, the moft inconhderable objefts in the heavens, and appear that white copper is not an artificial mixture of 
 
 of which the greater part of mankind have no occalion metals, but is found native in the mine. Yet in the 
 
 to take any notice during the whole courfe of their lives, very fame page and paragraph. Sir George proceeds to 
 
 (lie has, to talk in the hyperbolical language of Tycho fay that Dr Gallan was informed at Canton, that the 
 
 Brahe, moved the earth from its toundations, ftopt the artifts, in making their pe tung, reduce the copocr in- 
 
 revolution of the firmament, made the fun ftand ftill, to as thin ftieets or lamins as polfible, which they make 
 
 and fubverted the whole order of the univerfe. ' red-hot, and increafe the fire to fuch a pitch as to foften 
 
 " Such were the advantages of this new hypothefis, in fome degree the lamina:, and to render them ready 
 
 as they appeared to its author when he firft invented it. almoft to (low. In this ftate they are fufpended over 
 
 But though that love of paradox, fo natural to the the vapour of their pureft tu-te-nag or zinc, placed in 
 
 learned, and tiiat pleafure which they are fo apt to take a fubliming vedel over a briflc fire. The vapour thus 
 
 in exciting, by the novelty of their fuppofed difcoveiies, penetrates the heated laminse of the copper, fo as to re- 
 
 the amazement of mankind, may, notwithftanding what main fixed with it, and not to be eafily difiipated or 
 
 one of his difciplcs tells us to the contrary, have had its calcined by the fucceeding fufion it has to undergo, 
 
 weight in prompting Copernicus to adopt this fyftem ; The whole is fuffered to cool gradually, and is then 
 
 yet when he had completed his Treatife of Revolutions, found to be of a brighter colour, and of a clofer grain, 
 
 and began coolly to confider what a ftrange doftrlne he than when prepared in the Eu -opean way. Surely this 
 
 was about to offer to the world, he fo much dreaded is not the white copper, which confifts of copper, zinc, 
 
 the prejudice of mankind againft it, that, by a fpecies filver, iron, and nickel. 
 
 of continence of all others the moft difficult to a philo- CORK is the exterior bark of a tree which has been 
 
 fopher, he detained it in his clofet for thirty years to- defcribed in the Encyclopaedia. When the tree is about 
 
 gether. At laft, in the extremity of old age, he allow- 15 years old it is fit to be barked, and this can be done 
 
 ed It tn be extorted from him, but died as foon as it fucceffively for eight years. The bark always grows 
 
 was printed, and before it was publiftied." up again, and its quality improves as the age of the 
 
 This noble theory, however, being repugnant to the tree increafes. It is commonly finged a little over a 
 
 3 M a ftrong
 
 COR 
 
 [ a6 
 
 Coniua. ftrong {ireoDglowiqg orals, or laid to Toat a certain 
 """*"■"' time in water ; after w! ich it is pli^ed u:idcr ftoins in 
 order to be prefftd ftraight. We wnc wont to pro 
 cure tfie greater part of our cork from the Dutch, who 
 brought it principal!)' from France ; but they imjWrted 
 foine a!fo from Portugal and Spain. 
 
 This tree, as well as the nice to which its bark is 
 put, was known to the Greeks and the Roman:; ; by 
 the former cf whom it was called ^r*>-f and by the lat- 
 ter Jiil/er. By the Romans, as we learn from Pliny, 
 it was even employed to ftop veffels of every kind ; but 
 its application to tiiis ufe fetms not to have been very 
 common till the invention of glafs bottles, of which 
 Profeflbr Beckmanu finds no mention before the 15th 
 century. 
 
 In later times, fome other vegetable produdions have 
 been found which can be employed inlU'ad of cork for 
 the hiflmentioncd purpofe. Among tkefe is the wood 
 of a tree common in South America, particularly in 
 moid places, which is called there monbin or monbnhi, 
 and by botanl.ls _//^on^/;/;.f /kAvj. Thif wood is brought 
 to England in great abnndarce for that ufe. The 
 fpongy root of a North American tree, known by 
 the name of ri^ifftt, is alfo ufed for the lame end, as are 
 the roots of liquorice, which, on that account, is much 
 cultivated in Sclavonia, and exported to other countries. 
 
 CORNUA Ammonis, in natural hiftory, are foffil 
 (hells, of which a pretty full account is given in the 
 Encyclopaedia. See Cornu Ammonis and Snake- 
 Stones. It was obferved in the laft of thefe articles, 
 that few, if any, of thefe fhells are known in their re- 
 tent ftate, or as occupied by the living animal ; but 
 fome authors have afferted, on the authority of Lin- 
 nseus, that ammonites, with fhells fimilar to all the va- 
 rieties of the fofliloiies, are yet found alive in the depth 
 of the fea. We are much inclined to embrace this opi- 
 nioti ; but it has been controverted by M. de Lamanvn, 
 who accompanied La Peroufe on his voyage of difco- 
 ■very, by fuch arguments as we know not how to an- 
 fwer. This unfortunate naturaiift (fee Lamanon in 
 this Supplement) allows that there are ftill in the fea 
 living (ornua ammonis ; but he thinks that they are in 
 ■very fmall numbers, and materially different from the 
 -greater part of the folTil ones. According to him, thefe 
 Ltd ought to be confidered as a race, formerly the mod 
 numerous of all, of which, either there are no defcend- 
 ants, or thofe defcendants are reduced to a few dege- 
 nerate individuals. That there are no living animals 
 with Ihells of the very fame kind with fome of the folfil 
 tornua ammonis, the follow ir.g obfervations he confiders 
 as a fufEcient proof. 
 
 " The foffil (hells are very light and thin, whereas 
 the (hells of thofe animals that live in very deep water 
 are always thick and ponderous ; belides, the form of 
 the foffil cornua ammonis points out to us, in fome mea- 
 fure, the organization of the animal which inhabited it. 
 The celebrated Jufiieu woved, in 1721, that there ex- 
 ifted a very clofe analogy between the ammonite and 
 
 o ] COR 
 
 nautilus (a). It is well known that the nautilus, by fori 
 
 filling or emptying a part of its (liell, has the power of * 
 
 remaining (tationary in any depth it pleafes : the fame 
 was douhtlefs the cafe with the ammonite ; and if this 
 fpecies ilill abounds in the fea, it would furely be occa- 
 fioiially difcovercd by failors. 
 
 " The waves alfo would throw fragments of it on 
 the (hore ; (i(hermen might fometimes entangle it in 
 their nets ; or, at leafl, there would be fragments (lick- 
 ing to the lead of the founding line when afcertaining 
 great depths. It may alfo be added, that if the am. 
 monites never quitted the abyfs of the fea, thofe which 
 are found petrified vi'Ould not be conftantly met with on 
 the fame level, and in the fame bed, as thofe (hell-fifh 
 that oiily inhabit the (hallows. There are, however, 
 found in Normandy, Provence, Touraine, and a multi- 
 tude of other places, ammonites mixed with turbines, 
 buccina (whelks), and other littoral (hells. They are 
 found, befides, at every degree of elevation from below 
 the level of the fea to the fummits of the higheft moun- 
 tains. Analogy alio leads us to fnppofe, that Nature, 
 who has given eyes to the nautilus, has not rcfufed them 
 to the ammonite : now v.'hat ufe could thefe be of if 
 they remained confined to thofe depths which the light 
 is unable to penetrate ? 
 
 " The extinftion of the ancient race of ammonites is 
 therefore an eftablilhtd faft, which no rational fuppo- 
 fition can deftroy ; and this fa<ft is undoubtedly the mod 
 furprifing of any that is prefented to us in the h'dory 
 of aquatic animals. The difcovery of a few living fpe- 
 cies of cornua ammonis does not dedroy the truth of 
 this, for thefe ammonites are very different from thofe 
 which are found petrified. They are extremely rare, 
 and cannot be looked up to as the reprefentatives of 
 the old ammonites, fo varied in their fpecies, and the 
 number of which in the ancient ocean was probably 
 far more conlidcrable than that of all the other (hells 
 befides." 
 
 To every univolve (liell, rolled in a fpiral, fo as that 
 a horizontal plane will divide it into two equal parts, 
 formed of united fpirals, and bearing a certain propor- 
 tion to each other, our author gives the name of an am- 
 monite. " I thought it ahfolutely neceffary (fays he) to 
 afcertain the precife meaning of the term ammonite, pre- 
 vious to defcribing that which I found during our voy- 
 age round the world. The form of this is almod or- 
 bicular, the long diameter being to the fhort one as 
 three lines to two lines and three quarters. The firfl 
 fpire is by far the largeil, occupying nearly half of the 
 longitudinal diameter. The fummit is placed at the 
 didance of about two-thirds of this diameter ; it is ter- 
 minated on the right fide by a very fmall knob vifible 
 only through a magnifier, thus differing from the am- 
 monite of Rimini, which befides is microfcopical and 
 celled, the infide of this which we are now fpeaking of 
 being entirely plain. The number of fpiral circumvo- 
 lutions is four and a half; they are equally convex on 
 both (ides, and are fixed on a plane, dividing the (hell 
 
 into 
 
 (a) There ares however, fome ftriking internal differences: firlt, the partitions in the (hell of the nautilus 
 are more curved than thofe of the ammonite ; fecondly, the ammonite wants the fmall hole which communicates 
 from one cell to the other.
 
 C O R 
 
 r 4^1 ] 
 
 COR 
 
 Orriina. itito two equal parts : there is on each fide a kind of 
 •-"v— bofs formed by tlic incrcafe of the pcrpcuiliciilar dia- 
 meter of the fpires, in proportion as they recede from 
 the centre. The liirface is fniuoth ; tlie back Is armed 
 with a flat, even, brittle creft, as thin as paper, lur- 
 roundlng it on every fide like a ruff: It is about half a 
 line broad, extends over the fnnimit of the iplns, and 
 ferves to join them tofjethtr. The mouth ct the fliell 
 
 the Ihcll of the ammonite (a facl into which we hnf e Corrfclmn. 
 
 had no opportunity of inquirlnj;), his arguments for — ^ ' 
 
 the extinction of the ancient race are grofs fophlfms, 
 unwortliy of a man either of fcience or of candour. 
 
 CORRECTION-HOUSE is a prifon where idle va- 
 grants are compelled to work, and where perfons guilty 
 of certain crimes fiiffer puniflimcnt and make reparation 
 
 to the put 
 
 Of the foMiicr kind of ten 
 
 is nearly triangular ; its edges projeft in tiie form of pcrliaps enough has been faid in the Encych.p;edia un- 
 
 lips, and are rounded at the border. 1 have olten tound der the title \\'oRK-//«//f ; but oi the latter very little 
 
 this ammonite enclofed in the Itomach of tlie bonetta will be found in that work under the titles Bridewell 
 
 (fcomber pelamis, Linn.), caught in the South Sea, and Idleness. 
 
 between the tropics, where no bottom was found with Perhaps honfes of correftion, as means of puniih- 
 
 a line of more than two hundred fathoms. Thefe ment, are not, in this country, employed fo frequently 
 
 Ihells were covered with a black clayey mud. Their as juftice and expediency feem to require. In tlie oui- 
 
 ilze varies from one to four lines acrofs ; they are con- nion of Dr I'aley, \a hofe opinions aie always worthy of 
 
 fequently the largeft living ammonites that have yet been attention, it is one (jf the greatell deferts uf the laws of 
 
 difcovercd." England (and we may (ay the fame thing of the laws 
 
 It is well known for what purpofc the modern phi. of Scotland), that " lliey are not provided wiih any 
 lofophcrs of France have been fo indefatigable in tiie other puriiihment than that of death, lulhciently terrible 
 ftudy of natural hlftory ; and there can be little doubt to keep offenders in awe. Traniportalion, which is the 
 but that it is to ferve the fame purpufc that Lamanon punifiiment fecond in the order of fev«rity, anjwers the 
 thus reafons for the deftruftion of the ancient race of purpoie of example very imperfedly ; not only becaufe 
 ammonites in feme univerlal convullion of the world, exile is in reality a Uight punifhment to thofc who have 
 But fuppofing his arguments conclutive, they afTeft not neither property, nor friends, nor regular means of iub- 
 the truth of the JewKh and Chrlllian feriptures. It is fillence at home, but bccauie the punilhment, whatever 
 nowhere faid in the Bible, that the marler of this globe it he, is unobferved and unknown. A tranfported con- 
 was brought into being at the moment when Moles re- vidt may fuffer under his fentence, but his fuftVrings are 
 prefents the Creator as beginning to reduce the chaos removed from the view of his countrymen ; his mifery 
 into order; and it is more than infinuated that there is unfeen; his condition ilrikes no terror into the minds 
 will be a new earth after the prefent fyftem of things of thofe for whofe warning and admonition it was in- 
 fliall be dlffolved. That neiv earth will certainly be tended. This chafm in the fcale of punifhment pro- 
 ftored with ibme kind of inhabitants ; and could it be duces alfo two farther imperfettlons in the adminlllra- 
 demonrtrated that there was an old earth, previous to tion of penal juitice ; ot which the firll is that the 
 the era of the Mofaic cofmogany, inhabited by creatures fame punlfhnient Is extended to crimes of very different 
 rational and irrational, and that the toffil cornurt fl/nmonw characters and malignancy; and the fecond that pu- 
 make part of the wreck of that fyilem, the caufe of re- nllhments, feparated by a great interval, are affigned to 
 vtlation would remain uninjured. " Moles, as a real crimes hardly dlillnguiniable in their guilt and mif- 
 plulofopher * has well obierved, writes the hlftory, not 
 of this globe through all its revolutions, but of the race 
 of Adam." 
 
 This fecrct attack, therefore, mads by Lamanon 
 Bgainft that religion of which he once profefTcd to dlf- 
 charge the duties of a priell, is nothing more than te- 
 lum imhelle Jive iHu. Yet it may be worth fome natu- 
 
 chief 
 
 Pcrhap-, this chafm might be properly Hlled up by 
 houfes ot corredion under judicious management, which . 
 might llkewife promote another important purpofe, bet- 
 ter than the punilfimcnts in common ufc. 
 
 The end of punKhment is twofold, anu-ndnuiil and ex~ 
 mriph-. In the firil of thefe, the rifrrnhilion of crimi- 
 
 ralift's while to enquire, whether, though feeble. It has nah., little has ever been effeded, and little indeed feem 
 
 been fairly made. We confels that our own fufpicions 
 of unfair dealing are itrong ; for when a man of fcience 
 contradids hlmtelf in the courfe of two pages, the blun- 
 der mull be attributed to fome other fource than mere 
 inadvertency. M. de Lamanon wifties to prove, among 
 other things, that the ancient ammonites did not inha- 
 bit great depths of the fea ; and that Linnsens was mif- 
 taken when he fuppofed that in great depths they may 
 ftill be found. Yet he himlelf tells us, that he frequent- 
 ly caught ammonites in the South Sea, where no hot- 
 tom was to be found with a line of more than 200 fa- 
 thunu; and to put It beyond a doubt that the animals 
 had been at that bottom, he informs us, that their fliells 
 
 pradicable by the punilhments known to.thelawsof 
 Britain. From every fpecies of punllhment inllided 
 among us, from imprlfonment and exile, f.-om pain and 
 infamy, malefactors return more burdened in their 
 crimes, and more initruded. The cafe we think would' 
 often be different when they returned to the world from 
 a well regulated houfe of corredion. As experience is 
 the only iafe guide in matters of legiflaticm and police, 
 we fliall lay before our readers M. Thouiii'i account of' 
 the houfe of corredion at Amflerdam, which feems to- 
 corroborate our opinion. 
 
 The Amllerdam corrceT:liin houfe, from the employ- 
 ~£nt of the prifoners confined in it, is called \.\\ii rtifpihg. 
 
 were covered with a black clayey mud. It is true thefe houfe, and is delllned to the reception of thofe maTefac- 
 ammonites were but fmall ; while of 300 variedes of tors whofe crimes do not amount to a capital oifence. 
 
 foffil ammonites which he mentions, fome, he fays, have 
 been found ten feet in circumference. But is it certain 
 that thefe large fhells were real cornua ammonis ? If 
 they agree uot exa&ly with our autlior's defcription of 
 
 Iheir puniihment cannot fo properly be denominated; 
 folitary coufinement as a fequeitration from fociety du- 
 ring a limited terin of years. I'he building is iitilatecf: 
 ill a part of the fuburbs to the uorlh-eall of the city.. 
 
 The
 
 COR 
 
 Corr'-Slon The exterior has nothing remarkable, either wi»h re. 
 
 *~"V 'fpeft to form or extent. It is detached from the ftreet 
 
 by a fpacious court, which contains the keeper's lodge, 
 together with apartment^! for the different fervants be- 
 longing to the eftablifliment. Over the gate, which 
 
 I 462 ] 
 
 COR 
 
 which was dcpofitcd in piles in different parts of the Corre(<l.'<j». 
 court. '~"~v~-~' 
 
 The prifoners, amounting to 76 in number, were 
 uniformly habited in coarfe woollens ; wear very good 
 ftockings, large leather flioes, wliite Ihirts, and caps or 
 
 opens from this court into tiie prifon, art placed two hats. They are, by the rules of the houfe, obliged to 
 
 ftitucs, as large as life, reprefcnting two men in the adt frequent ablutions, which greatly contribute to the pre- 
 
 of fawing a piece of logwood. fervation of their health. There was only one fick per- 
 
 The inner court is in the form of a fquare, round fon amongft them ; and, what is not a little remark- 
 
 ■which are arranged the apartments of the prifoners, to- able, almoll all the prifoners had formerly lived in large 
 
 gcther with the necelTary warehonfes. One part of the commercial towns ; very few villagers were amongft 
 
 ground ftory is divided into different chambers ; the them. They had all been fentenced to imprifonment 
 
 other fervcs as a depot for the logwood, and the imple- for theft ; but it depends upon therafelves, by reforma- 
 
 ments errployed in its preparation. tion and good behaviour, to (horten the term of their 
 
 Tiie ke'per, whofe coiinttnance, contrary to the ge- confinement, which many of them frequently do. 
 
 reral cuftoir of perfons of his profcflion, was ftrongly The keeper, whofe humanity to the unfortunate per- 
 
 indicative of urbanity arid gentlcnefs, introduced M. fons committed to his care entitles him rather to the 
 
 Thouin into an apartment where two prifoners were at title of their proteftor than their gaoler (and M. Thou- 
 
 wcrk in fnwing a large log of Campeachy wood. The in informs us, that the priioners generally called him by 
 
 faw is coripofed of four blades joined together, with no other name ih-dw father ), affill.^ thtm with his coun- 
 
 verv ilrong, large, and fharp teeth, which make a fcif- fels and friendly admonitions. He regiilers every week, 
 
 fure in the wood of nearly two inches in breadth The in a book appropriated to this purpofe, both the in- 
 
 operation is repeated, till the pieces become too fmall fiances of good and bad behaviour, which is annually 
 
 to undergo the fav^, when they are ground in mills pe- fubraittcd to the examination ot the magillracy, who, 
 
 culiarly conftruftcd for this purpofe. from this report, abridge or prolong the term of con- 
 
 This employment requires an extraordinary exertion finement, according to the degree of indulgence which 
 
 of (Ireiigth, and is a* (iril; a fevere penance even to ro- each prifoner appears to merit. Cafes frequently ^Happen 
 
 bu't perfons ; but habit, addrefs, and practice, foon ren- where a malefadlor, condemned to an imprifonment of 
 
 der ;t eafy ; and the prifoners in a fhort time become eight years, by his good behaviour procures his enlarge- 
 
 competent to furnifi, without painful exertion, their ment at the expiration of four ; and fo in proportion for 
 
 weekly contingent of 200 lb. weight of fawed pieces, a (horter term. But great attention is paid to difcrimi- 
 
 After completing this tafk, they even find time to fa- nate between aftual reform and hypocritical artifice. 
 
 bricate a variety of little articles in wood and ftraw, The reward of good behaviour is not, however, con- 
 
 which they fell to thofe who vifit the prifon, or Uifpofe fined to, or withheld till, the period of adtual liberation, 
 
 of, by means of agents, in the to.vn. Their reftoration to fociety is preceded by a progref- 
 
 M. Thuuin next infpefted three apartments of dif- five amelioration of their lot. Their work is gradually 
 
 ferent dimenlions, which opened into the inner court, rendered lefs laborious, they are accommodated with fe- 
 
 The one was inhabited by four, the fecond by fix, and parate apartments, and emplojed in the fervices of do- 
 
 the third by ten prifoners. The furniture of the rooms meflic economy. The keeper even entrulls them vvith 
 
 ■confifted in haramockp, with a matrafs, a blanket, and a co'mMiflions beyond the precintls of the prifon ; and 
 
 coverlid to each, tables, chairs, and ftools, glafs, &c. fcarce a fingle inllance has occurred of their abufmg 
 
 ■earthen vcfTcls, and various other articles of convenience, this indulgence. By this prudent management, a con- 
 
 Every thing in thefe apartments was dillinguilhed by fidcrable faving is effected in the expence of the efla- 
 
 neatnefs and propriety ; and notwithflanding the num- bh'fhment, at the fame time that it tends to wear away 
 
 ber of inhabitants allotted to each, was fully adequate prejudice, and to initiate the prifoners by gradual ad- 
 
 to the diinenfions of the rooms ; the fcnfes were not of- vances into the reciprocal duties of focial lite, 
 
 fended with any difagreeable fcent, and the air was in M. Thouin made particular inquiries whether it was 
 
 every refpeft as pure and wholefome as the i'urrounding duftoniary for perfons after their ci'lcharge to be con- 
 
 atmofphere. fined a fecond and third time, as is but too often the 
 
 In an obfcure part of the buiWing are a number of cafe in many countries, for a i-epetition of their offence, 
 cells, in which formerly thofe 'prifoners who revolted He was informed, that fuch inflances very rarely occur ; 
 againlt the proper fubordination of the place, or iU- but the cafe is not without precedent, as he obferved in 
 treated their comrades, were confined for a few days, the perfon of a young Jew, who was then in the rafp- 
 But the keeper affured M. Thouin that thefe cells had ing-houfe for the third time. The cafe of this man is 
 not been made ufc of for upwards of 10 years. They fomewhat extraordinary. During the period of his de- 
 are dark gloomy dungeons, with only a fmall aperture tention, he always conforms, with the moft fcrupulous 
 for the admiffion of hght and air. The fupprefTiou of obfervance, to the rules of the place, and gives general 
 this barbarous and coercive punifhment does honour to fatisfaftion by his exemplary conduft. But fuch, as 
 the hum^uity of government. he hirafelf avowed to our traveller, is his conftitutional 
 
 The ftore rooms are filled with various kinds of wood propenfity to thieving, that no fooner is the term of his 
 
 for the purp.ifes of dyeing ; as the haemotoxylum cam- imprifonment elapfed, than he returns with redoubled 
 
 pechianum, the morus tinftoria, the caefalpinia fappan, ardour to his lawlefs courfes. It is not fo much for the 
 
 &c. They are all exotics, with the exception of the fake of plunder, as to gratify his irrefiftible impulfe, 
 
 Evonymus Europaus. The warehoufes were not of that he follows this vicious hfe ; and M. Thouin adds, 
 
 fuificient extent to contain the quantity of wood, that he recounted his different exploits with as much 
 
 e&uUation
 
 COR [ 463 ] C R A 
 
 reflion. exultation and triumph as a veteran dirplays when re- Wc will not take it upon us to fay that this punifh- Courtefey 
 
 -V— hearling his warlike atehievements. ment is never proper ; but we are fully convinced that ^j'^^_ 
 
 Another falulary regulation in this iuflitution, from it is not often fo ; and tha- flagellation, it it can at all ' _ ' t 
 
 which the bell confeqnences refult, is the indulgence produce any good elfeft, r.uill be adminiliered in pri- 
 
 granted to the prifuners of receiving the vifits of their 
 
 wives and miftrefles twice every week. Proper care, 
 however, is taken to guard again fl. tlie introduftion of 
 difeafe ; and the ladies, in one fenfe, purehafe their ad- 
 niinion by giving a trifling fum of money at the gate, 
 which becomes the perquilite of the aged prlfomrs, 
 whofe wants are of a different nature from their youth- 
 ful comrades. Thus tlie pleafures of one clafs contri- 
 bute to the comforts of the other ; and the entrance 
 money, trifling as it is, keeps away a croud of idle va- 
 gabonds, who have no acquaintance with the prifoners. 
 The ladies at their vifits are permitted to eat and drink 
 with their lovers ; and when the converfation becomes 
 too animated fof a third perfon to be prefent, the reft 
 of the company obligingly take the hint, and leave them 
 to enjoy a tete-a-tde. — By this prudent regulation, many 
 
 vate. It is obferved by Fielding, who well underftood 
 human nature, that failing is the proper punirtiinent cf 
 profligacy, not any punilhment that, like flagellation, 
 is attended wiih fliame. Puniflinient (fays he) that de- 
 prives a man oi all fenfe of honour, never will contri- 
 bute to make him virtuous ; and we believe it is gene- 
 rally admitted by the gentlemen of the army, that a 
 foldier who has fufTered the punifliment of whipping fel- 
 dom proves good for any thing. 
 
 COURTESEYoF Scotland. See Law {Enrjc!.), 
 Tart III. fea. Ix. § 18. 
 
 COWRY-Shells, the lowed money in fome parts 
 of the Eall. See Money [Enryc/.), where they are 
 called lar'u. 
 
 CRANE, in mechanics, a machine ufed for raifing 
 or lowering great weights. For the principles on which 
 
 hurtful confequences attendant on a total feclufion from thefe machines a£l, fee Dynamics in this, Supplement, 
 
 female fociety are guarded againft. and likewife Mechanics, Encyd. where defcriptions 
 
 M. Thonin concludes his account with obferving, are given of fcveral very powerful cranes, 
 that the rafping-houfe at Amfterdam bears a greater re- The crane in common ufe is employed with fome 
 
 femblance to a well-ordered manufaftory than to a pri- danger to thofe who work it ; and therefore a machine 
 
 fon. It were to be wilhed that all fimilar inititutions of this kind, adling upon a fimple and certain piinciple, 
 
 were condufted upon a fimilar plan (a). by which the men walking in the wheel can lower goods 
 
 So fays our author : But though we have admitted with fafety as well as expedition, has long been confi- 
 
 experience to be the only fafe guide in regulating inlli- dered as a great dcfideratum in mechanics. Repeated 
 
 tutio.ns of this kind, we cannot help thinking that the premiums have been offered by the Society for the Encou- 
 
 plan is fufceptible of improvement. We do not fee the ragtment of Arts to induce ingenious men to attempt 
 
 propriety of locking up four, fix, or ten thieves in the the invention of fuch a machine; and various have been 
 
 fame apartment. The uncommon attention to cleanli- the contrivances for accomplifhing fc> defirable a pur- 
 
 nefs, which diflinguilhes all ranks among the Dutch, pofe. A clergyman, who fubfcribes E. C. we fuppofe 
 
 may indeed prevent the room from having an offenfive as the initials of his name, propofes, through the medi- 
 
 fcent ; but what can prevent fuch a number of unprin- uni of the Repertory of Arts, to accomplilh it merely by 
 
 cipled perfons from corrupting each other in Holland, 
 as we know that they do in Great Britain ? The in- 
 troduction of females of loofe charader to felons fufl'er- 
 ing punifhment for their offences in a prifon, is a prac- 
 tice which we trull will be approved only by philofo- 
 phers of the French fchool. The Britifli philofopher, 
 
 introducing the aftion of a woim or fcrew into the crane. 
 Whenever a worm of two threads is introduced into 
 a machine, all retrograde motion is flopped, unlefs that 
 worm receive its reaflion from the firll moving force ; 
 for, powerfully as a worm adts upon a wheel, a \\heel 
 has no power upon a worm, whatever force may be ap- 
 
 whom we have already quoted with approbation, is of plied to it. Suppofe, then, the firft motion in a crane 
 
 opinion, and we heartily agree with him, that " of re- were given by a worm upon the axis of the wliccl in 
 
 forming punifhments, none prorhifes fo nuiih fuccefs as which the man walks, the man would have perfecl com- 
 
 that of folitary imprifonment, or the confinement of mand of the machine, to raiie or lower the goods at 
 
 criminals in feparate apartments. This improvement pleafure, with the remotell pofilbility of being over- 
 
 of the Amfleudam houle of correftion would augment powered by the dcfcending weight. 
 
 the terror of tlie punilliment, w'ould feelude the crimi- " Were I to conllruft (fays the author) a crane upon 
 
 nal from the fociety of his fellow-prifoners, in which fo- this principle, 1 would have the axis of the wheel in 
 
 ciety the worfe are fure tb corrupt the better ; would which the man walks, and tlie axis of the worm, in fe- 
 
 wean him from the knowledge of his companions, and parate parts, and occafionally united ty a coupling-box. 
 
 from the love of thst turbulent pernicious fife in which When goods were to be raifed, the two axes Ihould be 
 
 his vices had engaged him ; would raife up in him re- .connefted ; when jowered, they might be difunited, 
 
 . fleftions on the folly of liis choice, and difpofe his mind and the worm turned by a winch, w^hich would be done 
 
 to fuch bitter and continued penitence, as might pro- much more expeditioufly that way than by the wheel. 
 
 duce a lalling alteration in the principles of his con- For the reafons before fuggefled, the defccnt of the 
 
 duft." weight could be accelerated or flopped at pleafure, at 
 
 In fome houfes of correftion, the prifoners are fub- the difcretion of the perfon turning the winch, 
 
 je&ed to the difcipline of flagellation at Hated intervals. " This contrivance might be not inconveniently ap- 
 plied 
 
 (a) We do not know that M. Thouin's journal of his travels has been yet publifted. Extrafts from it have 
 been inferted into the Decade, a periodical publication at Paris, whence this accoujt of the Amjlerdam houfe of 
 correSion was firft copied into the Monthly Magazine for J^ne J 798,
 
 C R A [ 464 ] C R A 
 
 Crane pllcj to 3 crane already ercfted upon the common pn'n- of 40 guineas was adjudged by the fociety to tlie in- 
 *~'~^~"~' ciplc- : Let there be a wheel put upon any convenient vcntor, are as follows 
 
 -a:;is 111 the machine as it now ftands ; upon this let 
 tliere lie a worm, that can be thrown in or out of gear 
 at pleafure ; and let the lever by which it is done lie 
 within reach of the man's hand in the wheel. The 
 goods being lafteiied to the crane, and raifed off the floor 
 of the warehoufe ready for letting down, the man puts 
 the worm into gear, leaves the wheel, and lets the 
 goods down bv the winch. Provided it can be conve- 
 niently done, it would be advifable to throw the wheel 
 in which the man walks out of gear when the winch is 
 
 I. It is rutijile, conlifting merely of a wheel and axle. 
 2. It has comparatively little friction, as is obvious from 
 the bare infpectlon of the figure. _^. It is durable, as 
 is evident from the two properties above mentioned. 
 4. It is fafe ; for it cannot move but during the plea- 
 fure of the man, and while he is aftually preiling on 
 the gripe-lever. 5. This crane admits of an alniotl in. 
 finite variety of difTorent powers; and this variation is 
 obtained without the leaft alteration of any part of the 
 machine. It, in unloading a veffel, there fhould be 
 
 made ufe of; this, however, I fliould apprehend, would found goods of every weight, from a few hundreds to a 
 
 not be a matter of abfolute necellity." ton and upwards, the man that does the work will be 
 
 Our author is aware of two objections which may be able fo to adapt his llrength to each as to raife it in a 
 
 tirged againft tiie introduction of a worm into a crane fpaca ot time proportionate to its weight ; he walking 
 
 in the manner which he propofes. The firft ai ifes from always with the iamc velocity as nature and his greatcit 
 
 the flownefs of the motion produced by the turning of eafe may teach him. 
 
 a fcrew, which he confiders as unworthy of regard; be- 
 caufe the necefTary fpeed is to be gained by the firft pair 
 of wheels and the diameter of the barrel of the windlafs. 
 To the fecond, arifmg from the fuppofed greater 
 friiition between a worm and wheel, he replies, tliat as 
 the friftion between the teeth of two wheels (if not 
 formed on the true epicycloidal principle) mud, while 
 it lafts, be greater than between a worm and wheel for 
 the fame fpace of time, it feems no unrcafonable fuppo- 
 fition that the aggregate of friftion will, in the two 
 cafes, nearly balance each other ; efpecially if it be 
 taken into the account, that to obtain the power of 
 one worm and wheel, there will be, in moll cafes, re- 
 
 It is a great difadvantage in fome cranes, that they 
 take as long time to raiie the fmajlcll as the largeft 
 weight, unlefs the man who works them turn or walk 
 with fuch velocity as muft foon tire him. In other 
 cranes, perhaps, two or three different powers may be 
 procured ; to obtain which, fome pinion mull be Ihift- 
 ed, or freflt handle applied or reforted to. In this 
 crane, on the fontrary, il the labourer find his load fo 
 heavy as to permit him to alcend the wheel without its 
 turning, let him only move a Hep or two toward the 
 circumference, and he will be fully equal to the taflv. 
 Again, if the load befo light as fcarcely to rtfift the ac- 
 tion of his feet, and thus to oblige him to run through 
 
 * See Mt. 
 117. Eiicycl. 
 
 Plate XX, 
 
 quired two pair of wheels, and two additional axes — all fo much fpace as to tire him beyond neceflity, let him 
 
 which will add to the friftion. But, grafting the ba- move laterally towards the centre, and he will foon feel 
 
 lance of friction to be againft the aftion of the worm, the place , where his flrength will luffer the leall fatigue 
 
 the power to overcome it is greater in proportion than by raiilng the load in qucflion. One man's weight ap. 
 
 to overcome the fridlion of two wheels. plied to the extrcnjity of the wheel would raife up- 
 
 Mr James Whyte of Chevening, in the county of wards of a ton; and it need not be added, that a lingle- 
 
 Kent, whofe improvement in the conftruclion of pullies fheavcd block would double that power. Suffice it to 
 
 has, with due rtfpeft, been noticed elfewhere *, gives, fay, that the fize may be varied in any required ratio ; 
 
 in the TranfaCt'wiis of the Society for the Encouragement of and that this wheel will give as great advantage at any 
 
 jlrts, &c. the following defcription of a new crane for point of its plane as a common walking-wheel of equal 
 
 wharfs: diameter, as the inclination can be varied at pleafure, 
 
 A (fig. I.), a circular inclined plane, moving on a as far as expediency may require. It may be neceflary 
 
 pivot underneath it, and carrying round with it the to obferve, that what in the figure is the frame, and 
 
 axis E. A pcrfon talking on this plane, and preffing fcems to form a part of the crane, mull be Conlidered 
 
 againft. the lever B, throws ofl the gripe D, by means as a part of the houfe in which it is placed ; fince it 
 
 of an iron rod C ; and thus admits the plane and its would be moltly unneccflary fliould fuch cranes be ereil- 
 
 axis to move freely, and raife the weight G by the coil- ed in houfes already built. With refpcft to the hori- 
 
 ing of the rope F round the axis E. zontal part, by walking on which the man who attends 
 
 To fhew more clearly the conflruftion and aftion of the gib occafionally aflifts in raifing the load, it is not 
 
 the lever and gripe, a plan of the circular inclined plane, an elTential part of this invention, where the crane is 
 
 with the lever and gripe, is added (fee fig. 2.), where not immediately contiguous to the gib, although, where 
 
 B reprefents the lever, D the fpiing or gripe. In this it is, it would be certainly very convenient and econo- 
 
 plan, when the lever B is in the fituation in which it mical. 
 
 now appears, the fpring or gripe D prefTes againft the Crane is alfo a popular name for a fyphon, employ- 
 periphery of the plane, as (hewn by the double line, ed in drawing oft liquors. 
 
 and the machine cannot move ; but when the lever B CROSS, in furveying, is an inftrument confifting of 
 
 is prefTed out to the dotted line H, the gripe is alfo a bra& is^ircle, divided into four equal parts by two lines 
 
 thrown off to the dotted line I, and the whole macliine crofTmg each other in the centre. At each extremity 
 
 left at liberty to move. One end of a rope or cord, of of thefe lines is fixed a perpendicular fight, with fmaH 
 
 a proper length, is fixed near the end of the lever B, holes below each (lit, for the better difcovering of dif- 
 
 and the other end made faft to one of the uprights, tant objefts. The crofs is mounted on a ftaff or ftand, 
 
 ferving to prevent the lever moving too far when prefTed to fix it in the ground, and is very ufeful for meafu- 
 
 by the man. ring fmall pieces of land, and taking offsets, &c. 
 
 The properties of this crane, for which the premium Caossjliif, or Forejlaff, is a mathematical inftrument 
 
 of
 
 I'HDO'j'.v rj.ATK yrx: 
 
 Ti.r-V 
 
 Pic. 8 
 
 J-ra<^ Unb} 
 
 ? .■> t i\ .^K./r
 
 C R U 
 
 [ 465 ] 
 
 C R U 
 
 of box or pear-tiee, confifting of a fqnare ftaff t)t iibout long, aiui about half a yard Iruad. round which hangs 
 f . t I • _ 1 £■•. r J.-.' 1.1 i;i... « ^ iV;..,^.. f, u; •! i,_it* .. * ..r _ 1 
 
 three feet long, having each of its faces divided lik' 
 ' line of tangents, and having four crofs pieces of une- 
 qual lengths to fit on the ftaff, the halves of tliefc being 
 aa the radii to the tangent lines on the faces of the 
 fiaff. — The inftrument was ufed in taking the altitudes 
 of the celeftial bodies at fefl. 
 
 CROWN, in aftronomy, a name given to two con- 
 ftellations, the fouthcrn and the northern. 
 
 Crown, in geometry, a plane ring included between 
 two parallel or concentric periphenes of unequal circles. 
 
 Cuon-N-Poji, is a poft in Ibme buildings Handing up- 
 right in the middle between two principal rafters; and 
 
 a fringe foniething more than half a quarter of a yard 
 deep, of which the thread is regularly twilled. 
 
 The women give proofs of their modelly and decen- 
 cy by their drefs. Their phyfiognomy is agreeable, 
 their colour frefli, their cheeks vermilioned, and their 
 hair long ; they plait it together in one long trefs. 
 They wear a long robe of a fmooth (l{in tied round the 
 loins, like that of a nun; it covers them from the neck 
 as low as the feet; the fleeves reach down to the wrills. 
 Upon this robe they put divers Ikins of otters or other 
 animals to defend thenifelves from the inclemency of the 
 weather. Better dreffed, many of tliem might difpul'- 
 from which proceed ftruts or braces to the middle of charms with the moft handfome Spanilh women ; but 
 each rafter. It is otherwife called a kin^-poj}, or iitig's- diflatisfied with their natural charms, they have recourfc 
 piece, or joggle-piece. to art, not to embellifli, but to disfigure themfelves. 
 
 La CRUZ, an excellent harbour on the north-well All the married women have a large opening in the uu- 
 coaft of America, difcovered by the Spaniards in 1779. der lip, and this opening or orifice is filled up by u 
 They were introduced into it by a paflage which they piece of wood cut in an oval fliape, of which the fmall- 
 CdWeA Bucarelli's Entrance, and which they placed in ell diameter is almoll an inch; the more a woman is ad- 
 550 18' N. Lat. and 1390 15' W. Long, from the meri- vanced in years, the more this curious ornament is cx- 
 dian of Paris. There is no good reafon to quellion the tended: it renders them frightful, the old women efpc- 
 exadlnefs of the latitude of this palTage as laid down by cially, whofe lip, deprived of its wonted fpring, and 
 the Spaniards; but the editor of Peroufe's voyage juft- dragged by the weight of this extraordinary jewel, nc- 
 ly concludes, from the furvey made by our celebrated celTarily hangs in a very difagreeable manner. The 
 navigator Captain Cook on the coafls adjacent to the girls wear only a copper needle, which crolTes the lip in 
 entrance of Bucarelli, that this entrance is about 135" the place where the ornament is intended hereafter to 
 20' to the weft of Paris, or very nearly 133" weft of be placed. 
 
 Greenwich. Thefe Indians in war make ufc of cuirafies and 
 
 The Spaniards were not long in the harbour of La fhoulder pieces of a manufafture like that of the whale- 
 Cruz before they received a vifit from the inhabitants bone ftays among the Europeans. Narrow boards or 
 iu its neighbourhood. Bartering took place. The In- fcantlings form, in fome fort, the woof of the texture, 
 dians gave their peltry, and various trifles, for glafs and threads are the warp : in this manner the whole is 
 beads, bits of old iron, &c. By this traffic the Spa- very flexible, and leaves a free ufe to the arms for the 
 niards were enabled to gain a fufficicntly exaft know- handling of weapons. They wear round the neck » 
 ledge of their genius, of their ofFenfive and defenfive coarfe and large gorget which covers them as high as 
 arrar, of their manufaftures, &c. below the eyes, and their head is defended by a morion, 
 
 Their colour is a clear olive ; many among them or fl<ull-piccc, ufually made of the head of fome feroci- 
 have, however, a perfeftly white flcin : their counte- ous animal. From the waift downwards, they wear a 
 
 Th 
 
 ey 
 
 nance is well proportioned in all its parts, 
 robuft, courageous, arrogant, and warlike. 
 
 They clothe themfelves in one or two undrefled flvins 
 (with the fur apparently) ; thefe are the Hcins of otters, 
 cjf fea-wolves, of heiiades (a fpecies of deer), of bears, 
 or other animals, which they take in hunting. Thefe 
 drelTes cover them from the neck to the middle of the 
 
 kind of apron, of the fame contexture as their cuirafs. 
 Laftly, a fine flcin hangs from their flioulders do'wn to 
 the knee. With this armour they are invulnerable to 
 the arrows of their enemies; but tlius armed, they can- 
 not change pofition with fo much agility as if they were 
 Icfs burdened. 
 
 Their ofFenfive arms are arrows; bows, of which the 
 
 leg ; there are, however, many pmong them who wear ftrings are woven like the large cords of our belt muli- 
 
 boots of fmooth flcin, refembh'ng Englifh boots, only cat inftruments ; lances, four yards in length, tongued 
 
 that thofe of the Indians open before, and are laced with iron; knives, ot the fame metal, longer tiian £u. 
 
 tight with a ftring. They wear hats woven from the ropean bayonets, a weapon, however, not very common 
 
 fine bark of trees, the form of which refembles that of among them ; little axes of flint, or of a green ftone, fo 
 
 a funnel or a cone. At the wrifts they have bracelets hard that they cleave the moft conipaft wood without 
 
 of copper or iron, or for want of thefe metals the fins 
 of whales ; and round the neck, necklaces of fmall frag- 
 ments of bones of fillies and other animals, and even 
 copper collars of the bignefs of two fingers. They 
 wear in their ears pendants of mother-of-pearl, or flat 
 pieces of copper, on which is embolfed a refin of a to- 
 paz colour, and which are accompanied with jet beads. 
 Their hair is long and thick, and they make ufe of a 
 comb to hold it together iii a fmall queue from the 
 middle to the extremity ; a narrow ribbon of coarfe li- 
 nen, woven for this purpofe, ferves as a ligament. They 
 wear alfo as a covering a kind of fcarf, woven in a par- 
 
 injury to their edge. 
 
 The pronunciation of their language is extremely dif- 
 ficult ; they fpeak from the throat, with a movement of 
 the tongue againft the palate. Hie little \ilf tlv wo- 
 men make of the inferior lip greatly injures thf dillinc- 
 tivenefs of their language. The Spaniards could neither 
 pronounce nor write the words which they heard. 
 
 From the vivacity of fpirit in thefe Indians, and from 
 tlieir attention amply to furnilh the market eftabliflied 
 in the harbour, it may be concluded that they arc pret- 
 ty laborious. They continually brought lluffs well 
 woven and fhaded by various'colours, the flcins of lan<t 
 
 licular manner, fomething more than a yard and a half and fea wolves, of otters, bear8, and other fmallcr ani- 
 .S'jppL. Vol, I, Part II. 3 N mals ;
 
 C R U [ -166 ] C U L 
 
 Cruz, mals ; of thefe fome were raw, and others drefled. ftrait. As thefe trees cannot ftrike very deep into the 
 
 * ' There were to be found at this market alio coverlets of earth, the violence of the wind often tears them up by 
 
 coarfe cloth, fliaded with white and brown colours, very the roots : they rot and become a light mould, upon ^^ 
 
 well woven, but in fmall quantities : large ribbons of which grows a bulliy thicket ; and in this are found 
 
 the fame linen which might match with that of the nettles, camomile, wild celery, anife, a fpecies of cab- 
 
 Spanilh officers mattreffcs; ilceins of thread fucii as this bagc, celandine, elder, wormwood, forrel ; and without 
 
 cloth was made of; wooden plates or bowls neatly doubt there are other plants along the rivers, 
 worked ; fmall boats, or canoes, painted in various co- The Spaniards taw ducks, gulls, divers, kites, ravens, 
 
 lours, the figures of which reprefented heads with all geefe, llorks, gold-tinches, and other little birds un- 
 
 ■ their parts; frogs in wood, nicely imitated, which open- known to them. 
 
 ed like tobacco boxes, and which they employed to The commerce between the Spaniards and the In- 
 
 keep their trinkets in : boxes made of fmall planks, of dians was quite undilUirbed ; and fo deiirous were the 
 
 a cubical form, being three quarters of a yard on each latter to obtain iron, cloth, and other fluffs, that they 
 
 fide, with figures well diawn, or carved on the outfide, fold their children tor broken iron hoops and othtr 
 
 reprefenting various animals; the covers fabricated like wares. The Spaniards in this manner bought three 
 
 Flanders etwees, with rabbeted edges, formed fo as to young lads, one from five to fix years old, another of 
 
 fhut into the body of the box ; animals in wood, as four, and the third from nine to ten, not to make 
 
 well thofe of the earth as of the air ; figures of men of flaves, but Chriftians of them ; they hoped befides to 
 
 the fame material, with flcull-caps reprefenting the heads derive ul'eful information fi-om them as to the nature of 
 
 of various fierce animals ; fnares and nets for fi/hing ; the country and its inhabitants. Thefe youths were fo 
 
 copper collars for the neck, and bracelets of iron for contented in being with the Spaniards, that they hid 
 
 the wrift, but which they would not part with except themfelves when their parents came on board, from the 
 
 at a very high price ; beak-like inftruments, from which apprehenfion of being again reftored to them. Two 
 
 they drew founds as from a German flute. The prin- young girls were alfo purchafed with the fame view ; 
 
 cipal officers took fnch of thefe merchandizes as were one very ugly, feven years of age ; the other younger, 
 
 moll agreeable to them, and left the remainder to the better made, but fickly, and almoft at the gates of 
 
 fhips crews. death. 
 
 As the Indians difcovered that the Spaniards were At the full and change of the moon, the fea rifes in 
 
 very dainty in their fi(h, they did not let them want for the harbour of La Cruz feventeen feet three inches 
 
 choice : the greatefl abundance was in falmon, and a Englifti ; it is then high water at a quarter after 12 at 
 
 fpecies of fole or turbot three yards and a quarter long, noon : the loweft tides are fourteen feet three inches ; 
 
 broad and thick in proportion ; cod and pilchards were the night tides exceed by one foot nine inches thofe of 
 
 alfo brought to market, and fifhes refembling trout, the day. 
 
 Cruz 
 
 II 
 CuUen. 
 
 CRYSTAL, 
 CRYSTALLIZATION, 
 
 and 
 Rock-CRrsT.iL. 
 CUBIC Hyperbola, is a figure exprelfed by the 
 
 T See Crystal and Cr 
 
 i, I STALLIZATION, Encyi 
 r and Chemistry-ZW. 
 J in this Supplement. 
 
 From all this it may be inferred, that this gu^f is full of 
 iifh; the banks too are covered with fhells. 
 
 The quantity of mother-of-pearl that thefe Indians 
 cut to pieces for making ear rings awakened the curio- 
 lity of the Spaniards : they tried to difcover whether 
 
 thefe people had not in their pofTeflion, or whether their equation xy'-rza, having two afymptotes, and confiding 
 "'' ■ ' ' '" • n of two hyperbolas, lying in the adjoining angles of the 
 
 afymptotes, and not in the oppofite angles, like the 
 Apollonian hyperbola ; being otherwife called by New- 
 ton, in his Enumerai'w L'lnearum Tertli Ordinis, an hy- 
 perbolifmus of a parabola ; and is the 65th fpecies of 
 thofe lines according to him. 
 
 Cubic Parabola, a curve of the fecond order, having 
 
 country did not produce pearls, or fome precious ilones: 
 their rcfearches were fruitlefs ; they only found fome 
 Ilones which they judged to be metallic, and which they 
 carried on board, not having the necelTary means forex- 
 trafting the metal they might contain. 
 
 Thefe Indians feed upon fi(h, frefli or dry, boiled or 
 roafted ; herbs and roots which their mountains yielded 
 
 them, and particularly that which in Spain is called fea two infinite legs tending contrary ways. The curve of 
 parfley ; and, lailly, upon the flefli of animals which this parabola cannot be reflified even by means of the 
 they take in hunting : the produftions of the chafe are conic fetlions. 
 
 undoubtedly abundant, feeing the number of dogs they CULLEN (Dr William) was a man to whom phy- 
 keep for this purpofe. fical fcience is fo deeply indebted, that it has often 
 
 Thefe Indians appeared to the Spaniards to worfhip ftruck us with wonder that no account of him has yet 
 the fun, the earlieil and moil natural of all idolatrous been given to the public, which deferves to be claffed 
 
 worfliip ; and they paid a decent refpeft to the remains 
 of their dead. Don Maurellc, one of the Spanifli offi- 
 cers, in an expedition round the gulf, found in two 
 iflands three dead bodies laid in boxes of a fimilar form 
 to thofe which have been defcribed above, though con- 
 fiderably larger, and decked in their furs. Thefe biers 
 were placed in a little hut upon a platform, or raifcd 
 floor, made of the branches of trees. 
 
 The country is very hilly, the mountains are lofty, 
 and their flope extends almoft every where to the fea. 
 The foil, limeftone ; it is neverthelefs covered with an 
 
 with Britilh biography. We know, indeed, that a life 
 of him has been written by an eminent phyfician well 
 qualified and Itrongly inclined to do juflice to the merits 
 of his revered preceptor ; but that life has been with- 
 held from us by him who has certainly the befl right 
 to confider himfelf as the guardian of the Doctor's 
 fame, and who, we have been told, is to enlarge and 
 publilh it himfelf. In this flate of things our read- 
 ers muft pardon us for laying before them a very im- 
 perfeA account of this eminent man, to whom we were 
 ourfelves almoft ftrangers. There is a charafter of him 
 
 impenetrable foreft of tall fir trees, very large and very in the periodical publication, called The Bee, which we 
 
 fhall
 
 C U L [ 467 ] C U L 
 
 CuUen. (liall appropriate to our own ufe, we arc perfuadcd, with lion of iiis new acquaintance. Receiving inllrudlion from CulL-n. 
 
 ""v-—^ the entire approbation of its author, thougli fomctimcs him in a much more pleafing, and an infinitely eafier '"""v"'**' 
 
 we may exprefs our fufpicions that his praile is exagge- way than he had ever before obtained, the converfation 
 
 rated. of Culkn proved highly interefting to his Grace. — No 
 
 Dr William Cullen was born in Lanarkfhire, In the wonder then that he foon found means to get his favou- 
 
 welt of Scotland, i ith December 1712. His father was rite Dodor, who was already the elleemed acquaintance 
 
 for fome time chief magiitratc of the town of Hamil- of the man through whofe hands all preferniiiils in 
 
 ton ; but though a very refpeftable man, his circum- Scotland were obliged to pafi;, appointed to a place in 
 
 itances were not fuch as to permit him to lay out much the uiilverfity of Gbfgow, where his fingnlar talents for 
 
 money on the education of his fon. William therefore, difcharging the duties of the ftation he now occupied 
 
 after ferving an apprenticefliip to a furgeon apothecary foon became very confplcuous (a). 
 
 in Glafgow, went feveral voyages to the Weft Indies During his refidence in the country, however, feve- 
 
 as a furgeon in a trading veifel from London : but of ral important incidents occurred, that ought not to be 
 
 this employment he tired, and fettled himlclf, at an ear- paffed over in filence. It was during this time that 
 
 ly period of life, as a country furgeon in the parifli of was formed a connedtlon in bufincfs in a very humble 
 
 tihotts, where he ftald a fhort time praftiling among line between two men, who became afterwards emliieni- 
 
 the farmers and country people, and then went to Ha- ly confplcuous in much more exalted llations. William, 
 
 milton with a view to praftlfe as a phyflcian, having afterwards Doftor, Hunter, t'Jie famous ledlurc. on ana- 
 
 never been fond of operating as a furgeon. tomy in London, was a native of the fame part of the 
 
 While he relided near Shotts, it chanced that Archi- country ; and not being in affluent circumftances more 
 
 bald Duke of Argyle, who at that time bore the chief than Cullen, thefe two young men, ftimulated by the 
 
 pdlltieal fway In Scotland, made a vlfit to a gentleman impulfe of genius to profecute their medxal ftudies 
 
 of rank in that neighbourhood. The Duke was fond with ardour, but thwarted by th« narrownefs of their 
 
 of literary purfuits, and was then particularly engaged fortune, entered into a copartnery bufmefs as furgeong 
 
 in fome chemical refearches, which required to be elu- and apothecaries in the country. The chief end of 
 
 cidated by experiment. Eager In thefe purfuits, his their cnntraft being to furnifh the parties with the 
 
 Grace, while on this viiit, found himfelf much at a lofs meins of profecuting their medical ftudies, which they 
 
 for the want of fome fmall chemical apparatus, which could not feparately fo well enjoy, it was ftlpulated, 
 
 his landlord could not furnifh : but happily recollefting that one of them alternately fhould be allowed to ftudy 
 
 young Cullen in the neighbourhood, he mentioned him in what college he inclined, during the winter, while 
 
 to the Duke as a perfon who could probably furnifh it. the other fliould carry 011 the bufincfs in the country 
 
 He was accordingly invited to dine ; was introduced to for their comimon advantage. In confequence of this ' 
 
 liis Grace, — who was fo much pleafed with his know- agreement, Cullen was firft allowed to ftudy in the uni- 
 
 lerlge, his politcnefs, and addrefs, that he formed an ac- verfity of Edinburgh for one winter ; but when it came 
 
 quaintance which laid the foundation of all Dr CuUen's to Hunter's turn next winter, he, preferring London to 
 
 fuliire advancement. Edinburgh, went thither. There his fingular neatnefs 
 
 The name of Cullen bv this time became familiar at in dificth'ng, and uncommon dexterity in making ana- 
 
 every table In that neighbourhood ; and thus he came tomical preparations, his afllduity in ftudy, his nu'ldnefs 
 
 to l)e known, by charafter, to the Duke of Hamilton, of manner, and pliability of temper, foon recommended 
 
 who then relided, for a ftiort time, in that part of the him to the notice of Dr Douglafs, who then read lec- 
 
 country : and that nobleman having been fuddenly ta- tures upon anatomy and midwifery there ; v;ho enga- 
 
 ken ill, the affiftance of young Cullen was called in ; ged Hunter as an afliftant, and whofe chair he after- 
 
 which proved a fortunate circumftance in ferving to pro- wards tilled with {a much honour to himfelf and fatis- 
 
 mote his advancement to a ftation in life more fuited to faftion to the public, 
 
 his talents than that in which he had hitherto moved. Thus was dilfolved, in a premature manner, a copart- 
 
 The ch^^rafter of the DouglafTes, of which name the nery perhaps of as fingular a kind as is to be found in 
 
 family of Hamilton now forms a principal branch, has the annals of literature : nor was Cullen a man of that 
 
 always been fomewhat of the fame ftamp with that of difpofitlon to let any engagement with him prove a bar 
 
 the riftng Cullen. Genius, benevolence, franknefs, and to his partner's advancement in life. The articles were 
 
 conviviality of difpofitlon, have been, with them in ge- freely departed from by him ; and Cullen and Hunter 
 
 neral, very prominent features ; and If to that be added ever after kept up a very cordial and friendly correfpoiid- 
 
 a fplrit of frolic and diffipation, thefe will be accounted ence ; though, it is believed, they never from that time 
 
 as only natural confequences of thofe youthful indul- had a perfonal interview. 
 
 gences that fpring from an excefs of weakh at an early During the time that Cullen praftlft-d as a country 
 
 period of life, and the licence allowed to people of ele- furgeon and apothecary, he formed another connexion 
 
 vated rank. The Duke was therefore highly delight- of a more permanent kind, which, happily for him, was 
 
 ed with the fprightly charafter and ingenious converfa- not dllTolved till a very late period of his life. With 
 
 3 N 2 the 
 
 (a) It was not, however, folely to the favour of thefe two great men that Cullen owed his literary fame. He 
 was recommended to the notice of men of fcience in a way ftill more honourable to himfelf. The difeafe of the 
 
 Duke of Hamilton having refifted the effeft of the firft; applications, Dr Clarke was fent for from Edinburgh ; 
 and he was fo much pleafed with every thing that Cullen had done, that he became his eulogift upon every oc- 
 cafion. Cullen never forgot this ; and when Clarke died, gave a public oration in his praife in the Univerfity 
 of Edinburgh ; which, it is believed, was the firft of the kind in this country.
 
 C U L 
 
 [ 468 ] 
 
 C U L 
 
 CLlltn. the arJour of difpofitlon he pofiined, it cannot be fup- 
 ~~V— ' pofed he beheld the fa> iVx with indifference. Vety 
 early in life he took a Itrong attachment to an amiable 
 woman, a Mifs Johnfton, daughter to a clergyman in 
 that neighbourhood, nrarly of his own age, who was 
 prevailed on to join with him in the facrtd bonds of 
 wedlock, at a time when he had nothing elfe to recom- 
 mend him to her except his perfon and difpofitions ; for 
 as to riches and pofTeffions he had little cf thefe to boall 
 of. She was beautiful, had great good fenfe, equani- 
 mity of temper, an amiable difpofitlon, and elegance of 
 manners, and brought with her a little money, which, 
 though it would be accounted nothing now, was fome- 
 thing in thofe days to one in his fitnation in life. After 
 giving to him a numerous family, and participating with 
 him the changes of fortune which he experienced, fhe 
 peacefully departed this life in fumroer 1786. 
 
 In the year 1746, Cullen, who had now taken the 
 degree of doftor in phyfic, was appointed a lefturer in 
 chemiilry in the univerfity of Glafgow : and in the 
 month of Oftober began his leftures in that fclcnce. 
 His fiiiEjular talents for arrangement, his dillindtnefs of 
 enunciation, his vivacity of manner, and his knowledge 
 of the fcicnce he taught, rendered his leftures intereft- 
 iuT to the (Indents to a degree that had been till then 
 unknown at that univerfity. He became, therefore, in 
 fome mcafure, adored by the ftudcnts. The former pro- 
 feflbrs were ecllpfed by the brilliancy of his reputation ; 
 and he had to experience all thofe little rubs that envy 
 and difappointed ambition naturally threw in his way. 
 Regardlefs, however, of thefe fecret fhagreens, he pref- 
 fed forward with ardour in his literary career ; and, 
 i'upported by the favour of the public, he confoled him- 
 felf for the contumely he met with from a few indivi- 
 duals. His praftice as a phyfician increafed from day 
 to day ; and a vacancy having occurred in the year 
 1751, he was then appointed by the king profeffor of 
 medicine in that univerfity. This new appointment 
 I'erved only to call forth his powers, and to bring to 
 light talents that it was not formerly known he poffef- 
 fed ; fo that his fame continued to increafe. 
 
 As, at that period, the patrons of the univerfity of 
 Edinburgh were conltantly on the watch for the moll 
 eminent medical men to fupport the rifing fame of the 
 college, their attention was foon direAed towards Cul- 
 len ; who, on the death of Dr Plumber, profeffor of 
 chemiftry, was, in 1756, unanimonfly invited to accept 
 the vacant chair. This invitation he accepted : and ba- 
 vin"' refigned all his employments in Glafgow, he be- 
 gan his academical career in Edinburgh in the month 
 of Oftober of that year ; and there he relided till his 
 death. 
 
 If the admiffion of Cullen into the univerfity of Glaf- 
 gow gave great fpirit to the exertions of the ftudcnts, 
 this was ftiU, if poffible, more ftrongly felt in Edin- 
 burgh. Chemiftry, which had been till that time of 
 fmall account in that univerfity, and was attended to by 
 very few of the ftudcnts, inftantly became a favourite 
 ftudy ; and the leisures upon that fclence were more 
 frequented than any others in the univerfity, anatomy 
 alone excepted. The ftudcnts, in general, fpoke of Cul- 
 len with the rapturous ardour that is natural to youth 
 when they are highly pleafed. Thefe eulogiums ap- 
 peared extravagant to moderate men, and could not fail 
 to prove difgufting to his colleagues. A party was 
 
 formed among the ftudcnts for oppofing this new fa- 
 vourite of the public ; and thefe ftudcnts, by mlfiepre- 
 feuting the dodtrincs of Cullen to otlrers who could not 
 have an opportunity of hearing thefe doflrines them- 
 felves, made even fome of the moil intelligent men in the 
 univerfity think it their duty publicly to oppofe thefe 
 imaginary tenets. The ferment was thus augmented ; 
 and it was fome time before the profeffors dlfcovercd 
 the arts by which they had been impofed upon, and 
 univerfal harmony reftortd. 
 
 During this time of public ferment, Cullen went 
 fteadily forward, without taking any part himfelf in 
 thefe difputcs. He never gave ear to any tales refpedt- 
 ing his colleagues, nor took any notice of the doftrines 
 they taught : That fome of their unguarded ftrlftures 
 might at times come to his knowledge, is not impof- 
 fible ; but If they did, they fcemed to make no impref- 
 fion on his mind. 
 
 Thefe attempts of a party of ftudcnts to lower the 
 character of Cullen on his firft outfet in the univerfity 
 of Edinburgh having proved fruitlefs, his fame as a 
 profeffor, and his reputation as a phvficliin, became move 
 and more refpettcd every day. Nor could It well be 
 otherwife : Cullen's profeflional knowledge was always 
 great, and his manner of lefturing fingularly clear and 
 Intelligible, lively and entertaining ; and to his patients, 
 his conduft in general as a phyfician was fo pleafing, his 
 addrefs fo affable and engaging, and his manner fo open, 
 fo kind, and fo little regulated by pecuniary confidera- 
 tions, that it was iHipoftible for thofe w ho had occafion to 
 call once for his medical affiftance, ever to be fatisfied on 
 any future occafion witliout it. He became the friend 
 and companion of every family he vifited ; and his fu- 
 ture acquaintance could not be difpeufed with. 
 
 But if Dr Cullen in his public capacity deferved to 
 be admired. In his private capacity by his ftudcnts he de. 
 ferved to be adored. His crrduft to them was fo at- 
 tentive, and the intereft he took In the private concerns 
 of all thofe ftudents who applied to him for advice, was 
 fo cordial and fo warm, that It was impoffible for any 
 one who liad a heart fufceptible of generous emotions^ 
 not to be enraptured with a conducSl fo uncommon and. 
 fo kind. Among ingenuous youth, gratitude eaiily de- 
 generates into rapture — into refpedt nearly allied to a- 
 doratlon. Thofe who advert to this natural conftruc- 
 tioii of the human mind, will be at no lofs to account 
 for that popularity that Cullen enjoyed — a popularity, 
 that thofe who attempt to weigh every occurrence by 
 the cool ftandard of reajon alone, will be inclined to 
 think exceffive. It Is fortunate, however, that the bulk, 
 of mankind will ever be influenced in their judgment 
 not lefs by feelings and affeftions than by the cold and 
 phlegmatic diftates of reajon. The adoration which, 
 generous conduft excites. Is the reward which nature 
 hath appropriated exclufivelytodlfinterefted beneficence. 
 This was the fecret charm that Cullen ever carried a- 
 bout with him, which fafclnated fuch numbers of thofe 
 who had Intimate accefs to him. This was the power 
 which his envious opponents never could have an op- 
 portunity of feeling. 
 
 The general conduft of CuUen to his ftudents was 
 thus. With all fuch as he obferved to be attentive and 
 diligent, he formed an early acquai':tance, by inviting 
 them by twos, by threes, or by fours at a time, to fup 
 with him, converfing with tbera on thefe occafions with 
 
 the 
 
 Cull
 
 C U L 
 
 the moft engaging eafe, and freely entering with them 
 'on the fubjedt of their ftudies, their amufements, their 
 ilifficiihies, their hopes, and future profpeAs. In this 
 way he ufually invited the whole of his numerous clafs, 
 till lie made himfelf acquainted with their abilities, their 
 private charader, and their olijedj of purfuit. Thofe 
 among them whom he foui.d moll afliduous, bell dif- 
 pofed, or the moll friendlefs, he invited the moll fre- 
 quently, till an intimacy was gradually formed, which 
 proved highly beneficial to them. Tlieir doubts, with 
 regard to their objefts of ftudy, he liilened to with at- 
 tention, and' folved with the moft obliging condefcen- 
 fion. His librar\-, which confided of an excellent af- 
 fortment of the beft books, efpecially on medical fub- 
 je£ls, was at all times open for their accommodation ; 
 and bis advice, in every cafe of difficulty to them, they 
 always had it in their power moll readily to obtain. 
 They feemed to be his family ; and few perfons of dif- 
 tinguifhed merit have left the univerllty of Edinburgh 
 in his time, with whom he did not keep up a corre- 
 fpondence till they were fairly eftablilhed in bufinefs. 
 By thefe means he came to have a moll accurate know- 
 ledge of the (late of every country, with refpcct to 
 praftitioners in the medical line ; the only ufe he made 
 of which knowledge was, to dircft lludents in their 
 choice of places, where they might have an opportuni- 
 ty of engaging in bufinefs with a reafonable prolpeft of 
 fuccefs. Many, very many, able men has he thus put 
 into a good line of bufinefs where they never could have 
 thought of it themfelves ; and they are now reaping the 
 fruits of this beneficent forelight on his part. 
 
 Nor was it in this way only that he befriended the 
 lludents at the univerfity of Edinburgh. Pofleffing a 
 benevolence of mind that made him ever think firlt of 
 the wants of others, and recoUefting the difficulties 
 that he himfelf had had to ftruggle with in his younger 
 days, he was at all times fingularly attentive to their pe- 
 cuniary concerns. From his general acquaintance a- 
 niong the ftudtnts, and the friendly habits he was on 
 with many of them, he found no difficulty in dilcover- 
 ing thofe among them who were rather in hampered 
 circumftances, without being obliged io hurt their de- 
 iicacy in any degree. To fuch perfons, when their 
 habits of ftudy admitted of it, he was peculiarly at- 
 tentive.. They were more frequently invited to his 
 lioufe than others; they were treated with more than 
 iifual kindnefs and familiarity ; they were conducted to 
 his library, and encouraged by the moil delicate addrefs 
 to borrow from it ireely whatever books he thought 
 they had occafion tor : and as perfons in thefe circum- 
 ftances were ufually more fliy in this refpedl than others, 
 books were fomcti.-nes prcfTed upon them as a fort of 
 eonllraint, by the Doftor infilling to have their opinion 
 of fuch or fuch paffagesthey had not read, and defiring 
 them to carry the book home for that purpofe. He, 
 in fliort, behaved to them rather as if he courted their 
 company, and ilood in need of their acquaintance than 
 they of his. He thus railed them in the opinion of 
 their acquaintance to a much higher degree of eilima- 
 tion than they could otherwife have obtained ; which, 
 to people whofe minds were deprefled by penury, and 
 whofe fcnfe of honour was fiiarpened by the confciouf- 
 nefs of an inferiority of a certain kind, was fingularly 
 engaging. T^hus they were infpired with a fecret fenfe 
 •f dignity, which elevated their minds, and excited an 
 
 [ 469 ] 
 
 C U L 
 
 uncommon ardour of purfuit, inlUad of that mclancho- Cullcn. 
 ly inaftivity which is lo naturul in fuch circuniltances, '— v~~~ 
 and which too often leads to defpair. Nor was he kfi 
 delicate in the manner of fuppl) iiig their wants, thuiv 
 attentive to dilcover them. He often found out fomc 
 polite cx'cufe tor refilling to take puyu.ei.t for a firit 
 courie, and never was .it a lofs for one 10 an after courfe. 
 Before they could have an opportunity of applying for 
 a ticket, he would fometimes lead the converfation to 
 fome fubjeCt that occurred in the courfe of hisleftures; 
 and as his ledtures were never put in writing by him- 
 felf, he would fometimes beg the f>iVour to fee their 
 notes, if he knew they had been taken with attention, 
 under a pretext of affilling his memory. Sometimes h; 
 would cxprefs a wifh to have their opinion of a paiticu- 
 lar part of his courfe, and prefented them with a ticket 
 for that purpofe ; and fometimes he rcfufed to take 
 payment, under the pretext that they had not leccivtj 
 his full courfe the preceding year, iome part of it ha- 
 ving been neceflarily ojtiltted for want of t me, which 
 he meant to include in this courfe. By fuch dclicat'; 
 addrefs, in which he greatly excelled, he took care to 
 forerun their wants. Thus he not only gave them thy 
 benefit of his own leftures, but by retufing to takj 
 their money, he alfo enabled them to attend thofe of 
 others that were neceflaiy to complete their courfe of 
 lludies. Thefe were particular devices he adopted to 
 individuals to whom economy was neceflary ; but it 
 was a general rule with him, never to take mor.ey from 
 any lludent for more than two couifes of the fame fet 
 of lecturee, permitting him to attend thefe IcAures as 
 many years longer as he pltafed gral'u. 
 
 He introduced another general rule into the univer- 
 fity, that was diclated by the tame principle of difin. 
 terelled beneficence, that ought not to be here pafTed 
 over in fileuce. Before he came to Edinburgh, it was 
 the cullom of medical profeflbrs to accept of fees for 
 their medical afiillance, when wanted, even from medi- 
 cal lludents themfelves, who were perhaps attending thi; 
 profelTor's own ieftuies at the tinje. But Cullen nevei: 
 would take fees as a phyfician from any lludeut at the 
 univerfity, though he attended them, when called in a,j 
 a phyfician, with the fame affidulty and care as if thev 
 had been perfons of the firll rank, who p^aid him molt 
 liberally. This gradually induced others to adopt a li- 
 milar pradUce ; io that it is now become a general ruir; 
 for medical proftllors to decline taking any fees when 
 their affiftance is neceflary to a Undent. Eor this ufe- 
 fnl reform, with many others, the lludents of the uni- 
 verfity of Edinburgh are iokly indebted to the libciali- 
 ty of Dr Cullen. - ' 
 
 The firll lectures which Cullen delivered 'm\ Edin- 
 burgh were on chemillry ; and for many years he alfo 
 gave clinical leclures on the cafes which occurred in iIik 
 Royal Infirmary. In the month of February I7f'3, 
 Dr Alfton died, after liaving begun his ulual courfe of 
 lectures on the materia m<idica ; and tlie inagiftrates of 
 Edinburgh, as patrons- of that profeffoirhlp in the uni- 
 verfity, appointed Dr Cullen to that chair, requclling 
 that he would finilh the courfe of Icdures thai had bttii 
 begun for that feafon. This he agreed to do;, and 
 though he was under a neceflity of going on with the 
 courfe in a few days after he was nominated, he did nut 
 once think of reading the letlures of his predeceffor, 
 but refolved to deliver a new courfe entirely his own 
 
 The
 
 C U L 
 
 [ 470 1 
 
 C U L 
 
 CuUen. The popularity of CuUen at this time may be guelTed 
 ^ at by the increafe of new ftudents who came to attend 
 his courfe in addition to the eight or ten who had en- 
 tered to Dr Alilon. The new Itudents exceeded ico. 
 All in^peiteft copy of thefe Icftures, thus fabricated in 
 harte, having been pubh'lhed, the Doftor thought it ne- 
 cefTary to give a more correfl; edition ot them in the 
 latter part of his life. But his faculties being then 
 iTiurh impaired, his friends looked in vain for thofe Itri- 
 kin J beauties that charadterifed his literary exertions in 
 the prime of life. 
 
 Some years afterwards, on the death of Dr White, 
 the magiftrates once more appointed Dr Cullen to give 
 ledlures on the theory of phyfic in his ftead. And it 
 was on that occafion Dr Cullen thought it expedient to 
 refign the chemical chair in favour of Dr Black, his 
 former pupil, whofe talents in that department of fcience 
 were then well known, and who filled the chair till his 
 » See Blaci, di-dth with great fatisfaftion to the public*. Soon after, 
 ^"PP'- on the death of Dr Rutherford, who for many years 
 
 had given leftures with applaufe on the praflice of phy- 
 fic, Dr John Gregory (whofe name can never be men- 
 tioned by any one who had the pleafure of his acquain- 
 tance without the warmeft tribute of a grateful refpedt) 
 having become a candidate for this place along with Dr 
 Cullen, a fort of comproniife took place between them ; 
 •by which they agreed each to give kftures alternately 
 on the theory and on the pradlice of phyfic during 
 their joint lives, the longed furvivor being allowed to 
 hold either of the claiTes he (hould incline. In confe- 
 quence of this agreement, Dr Cullen delivered ihejirjl 
 courfe of Icftuies on the praAice of phyfic in winter 
 1766, and Dr Gregory fucceeded him in that branch 
 the following year. Never pcrlinps did a literary ar- 
 rangement take place that could have proved more be- 
 neficial to the lludents than this. Both thefe men pof- 
 fefftd great talents, though of a kind extremely diffimi- 
 lar. Both of them had certain failings or defefts, which 
 the other was aware of, and counterafted. Each of 
 them knew and refpefted the talents of the other. They 
 co-operated, therefore, in the happieft manner, to en- 
 large the underllanding, and to forward the purfnits of 
 their pupils. Unfortunately this arrangement was foon 
 deftroyed by the unexpeAed death of Dr Gregory, 
 who was cut off in the flower of life by a fudden and 
 unforefeen event. After this time, Cullen continued 
 to give lectures on the pradice of phyfic till a few 
 months before his death, which happened on the 5th 
 of February 1790, in the 77th year of his age. 
 
 In drawing the charaAer of Dr Cullen, Dr Ander- 
 fon, to whom we are indebted for this Iketch, obferves, 
 that in fcientific purfuits men may be arranged into 
 two grand claffes, which, though greatly diftcrciit from 
 each other in their extremes, yet approximate at times 
 fo near as to be blended indifcriminately together ; 
 thofe who poflels a talent for detail, and thofe who are 
 endowed with the facuUy of arrangement. The firll 
 may be faid to view objefts individually as through a 
 microfcope. The field of vifion is confined ; but the 
 objefts included within that field, which muft ufually 
 be confidered fingly and apart from all others, are feen 
 with a wondrous degree of accuracy and diftinftnefs. 
 The other takes a fweeping view of the univerfe at 
 large, confiders every objeft he perceives not individu- 
 
 ally, but as a part of one harmonious whole ; His mind to obferve. 
 
 is therefore not fo much employed in examining the fe- Culkn. 
 parate parts of this individual objeft, as in tracing its v ■ 
 relations, connexions, and dependencies, on thofe a- 
 round it. — Such was the turn of Cnllen's mind. The 
 talent for arrangement was that which pecuh'arly dif- 
 tingulfhed him from the ordinary clafs of mortals ; and 
 this talent he poficfled perhaps in r. more dillinguifiied 
 degree than any other perfon of the age in which he 
 lived. Many perfons exceeded him in the minute know- 
 ledge of particular departments, who, knowing tliis, 
 naturally looked upon him as their inferior ; but pof- 
 fefling not at the fame time that glorious faculty, which, 
 *' with an eye wid^e roaming, glances fr^m the earth to 
 heaven," or the charms which this talent can infufe 
 into congenial minds, felt difguft at the pre-eminence 
 he obtained, and aftonidiment at the means by which 
 he obtained it. An Arillotle and a Bacon have had 
 their talents in like manner appretlated ; and many are 
 the perfons who can neither he exalted to fublime ideas 
 with Hoir.er, nor raviihed with the natural touches of a 
 Shakefpeare. S<ich things are wifely ordered, that every 
 department in the univerfe may be properly filled by 
 thoie who have talents exactly fuited to the taflc affign. 
 ed them by heaven. 
 
 Had Cullen, however, poffcfled the talents for ar- 
 rangement alone, fmall would have been his title to 
 that high degree of applaufe he has attained. With- 
 out a knowledge o( faffs, a talent for arrangement pro- 
 duces nothing but chimeras ; without materials to work 
 upon, the llrufturcs which an over-heated imagination 
 may rear up are merely " the bafelefs fabric of a vifion." 
 No man was more fenfible of the jullnefs of this remark 
 than Dr Cullen, and few were at greater pains to avoid 
 it. His v;hole life, indeed, was employed, almoft with- 
 out interruption, in collefting facts. Whether he was 
 reading, or walking, or co;iverfing, thefe were continu- 
 ally falling into his way. With the keen perception of 
 an eagle, he marked them at the firft glance ; and with« 
 out Hopping at the time to examine them, they were 
 llored up in his memory, to be drawn forth as occafion 
 required, to be confronted with other fafts that had 
 been obtained after the fame manner, and to have their 
 truth afcertained, or their falfity proved, by the evidence 
 which ihonld appear when carefully examined at the 
 impartial bar of juftice. Without a memory retentive 
 in a fingular degree, this could not have been done ; 
 but fo very extraordinary was Dr Cullen's memory, 
 that till towards the very decline of life, there was 
 fcarcely a faft that had ever occurred to him which he 
 could not readily recollett, with all its concomitant cir- 
 cumllances, whenever he had occafion to refer to it. Jt 
 was this faculty which fo much abridged his labour in 
 ftudy, and enabled him fo happily to avail himfelf of the 
 labour of others in all his literary fpeculations. He of- 
 ten reaped more by the converiation of an hour than 
 another man would have done in whole weeks of labo- 
 rious lludy. 
 
 In his preleftions, Dr Cullen never attempted to 
 read. His leftures were delivered viva voce, without 
 having been previoufly put into writing, or thrown in- 
 to any particular arrangement. The vigour of his mind 
 was fuch, that nothing more was neccffary than a few 
 fliort notes before him, merely to prevent him from va. 
 rying from the general order he had been accuftomed 
 
 This gave to his difcourfes an eafe, a vi- 
 vacity,
 
 C U L 
 
 vacity, a variety, and a force, that are rarely to be met 
 'with in academical difcuurfes. His Itfliires, by coiifc- 
 quence, upon the fame fubjcft were never exaClly the 
 fame. Their general tenor indeed was not mucli va- 
 ried ; but the particuhir illuftrations were always new, 
 well failed to the circumllances that attratlcd tlie ge- 
 neral attention of the day, and were delivered in the 
 particular way that accorded with the call of mind the 
 preledtor found himfelf in at the time. To tliefe cir- 
 cunillances mull be afcribed that energetic artlefs elo- 
 cutiim, which rendered his ledtures fo generally capti- 
 vating to his hearers. Even thofe who could not fol- 
 low him ill thofe cxtenfive views his penetrating mind 
 glanced at, or vi-ho were not able to underftand thole apt 
 allufions to collateral objects which he could only rapidly 
 point at as he went along, could not help being warm- 
 ed in fome meafure by the vivacity of his manner. But 
 to thole who could follow Inin in his rapid career, the 
 ideas he fuggelled were fo numerous, the views he 
 laid open were fo extenlive, and the ohjecls to be at- 
 tained were fo important — that every aftive faculty of 
 the mind was roufed; and fuch an ardour of enthuiiafm 
 was excited in the profecution of lludy, as appeared to 
 be perfeftly inexplicable to thofe who were merely un- 
 concerned fpeClators. In confequence of this unfhack- 
 led freedom in the compofition and delivery ot his lec- 
 tures, every circumllance was in the nicell unifon with 
 the tone of voice and expreflion of countenance, which 
 the particular call of mind he was in at the time infpi- 
 red. Was he joyous, all the figures inti'oduced for il- 
 luftration were fitted to excite hilarity and good hu- 
 mour : was he grave, the objedls brought under view 
 were of a nature more iolemn and grand : and was he 
 peevilh, there was a peculiarity of manner in thought, 
 in word, and in action, which produced a moft ilriking 
 and interefting efteCl. The languor of a nervelefs uni- 
 formity was never experienced, nor did an abortive at- 
 tempt to excite emotions that the fpeaker himfelf could 
 not at the time feel, ever produce thofe difcordant ideas 
 which prove difgufting and unpler'.lnig. 
 
 It would feem as if Dr Cullen had confidered the 
 proper bufinefs of a preceptor to be that of putting his 
 pupils into a proper train of {ludy, fo as to enable them 
 to profecute thofe iludles at a tuture period, and to car- 
 ry them on much farther than the (hort time allowed 
 for academical prelections would admit. He did not, 
 therefore, fo much llrive to make thole who attended 
 his ledlures deeply verfed in the particular details of 
 objefts, as to give them a general view of the whole 
 fubjedt ; to (hew what had been already attained re- 
 fpedling it ; to point out what remained yet to be dif- 
 covered ; and to put them into a train of llu.dy that 
 fhould enable them at a future period, to remove thofe 
 difficulties that had hitherto obllrucled our progrefs ; 
 and thus to advance of themfelves to farther and far- 
 ther degrees of perfedlion. If thefc were his views, 
 nothing could be more happily adapted to them than the 
 mode he invariably purfued. He llrft drew, with the 
 ftriking touches of a mailer, a rapid and general outline 
 of the fubjed, by which the whole figure was feen at 
 once to Hart boldly from the canvas, dillindl in all its 
 parts, and unmixed with any other object. He then 
 began anew to retrace the pidure, to touch up the lef- 
 fcr parts, and to finifh the whole in as perfcft a manner 
 as the Itate of our knowledge at the time would permit. 
 
 [ 47» ] 
 
 C U L 
 
 Where materials were wanting, the piAiire there conti- Cullen. 
 nued to remain imperfcft. The waists were thus nn- '~~v~-" 
 dered obvious ; and the means of fupplyin^ thefe were 
 pointed out with the molt cartful dilcrimination. The 
 Undent, whenever he looi<ed back to the fubjeft, per- 
 ceived the defedlb ; and his hopes being awakeneu, he 
 felt an irreiiilible impulfe to explore that liitherto un- 
 trodden path which had been pointed out to him, and 
 fill up the chdfni which Hill remained. Thus were the 
 aftive faculties of the mind moil powerfully excited ; 
 and inftead of labouring himfelf to fupply deficiencies 
 that far exceeded the power of any one man to accom- 
 plifh, he fet thoufands at work to fulfil the tafl<, and 
 jnit them into a train of going on with it, when he him- 
 felf Ihould be gone to that country " from whofe dread 
 bourne no traveller returns." 
 
 It was to thclc talents, and to this mode of applying 
 them, that Dr Cullen owed his celebrity as a profefior ; 
 and it was in this manner that he has perhaps done 
 more towards the advancement of fcience than anv 
 other man of liis time, though many individuals might 
 perhaps be found who were more deeply verfed in the 
 particular departments he taught than he himfelf was. 
 Chemillry, which was before his time a moll difgufting 
 purfuit, was by him rendered a (ludy fo pleafing, fo ea- 
 ly, and fo aitraflive, that it is now profecuted by num- 
 bers as an agreeable recreation, who but for the lights 
 that were thrown upon it by Cullen and his pupils, 
 would never have thought of engaging in it at all ; 
 though perhaps they never heard of Cullen's name, nor 
 have at this time the moft dillant idea that they owe 
 any obligations to him ; and the fame may be faid of 
 the other branches of tcicnce which he taught. 
 
 According to a man who knew him well, there arc 
 three things \\'hich eminently dillinguifliLd Cullen as a 
 profefTor. " The energy of his nu'nd, by which he 
 viewed every fuljjeft with ardour, and combined it im- 
 mediately with the whole of his knowledge. 
 
 " The fcientific arrangement which he gave to his 
 fubjeft, by which there was a lucidus ordo to the dulled 
 fcholar. He was the firft perlon in this country who 
 made chemillry ceafe to be a chaos. 
 
 "'A wondertul art ot interclling the ftudents in every 
 thing which he taught, and ot raifing an emulative en- 
 thuiiafm among them." • ■ 
 
 We are well aware that this charafter will by many- 
 be deemed an extravagant panegyric ; but having no 
 opportunity of judging for ourfelves, we would rather 
 adopt from others an extravagant panegyric than an 
 unmerited cenfure. Dr Andcrfon himfelf admits that 
 Cullen's charafter was far from perfect ; and, in the 
 opinion of moll other men with whom we have conver- 
 fed on the fubjeft, and who were at the fame time qua- 
 lified to form an ellimate of his meutal powers, his ima- 
 gination was not balanced by his judgment. Hence 
 the common remark in the univerfity of Edinburgh, 
 that Dr Cullen was more fuccefsful in demolilhing the 
 theories of others than in giving liability to thofe 
 which were reared by himfelf. 
 
 Dr Cullen's external appearance, though ftriking and 
 not unpleafing, was not elegant. His countenance was 
 expreffive, and his eye in particular remarkably lively, 
 and at times wonderfully penetrating. In his perfon he 
 was tall and thin, ftooping very much about the fhoul- 
 ders. When he walked, he bad a contemplative look, 
 
 and
 
 Catfeu 
 CulTo. 
 
 CUR [ 472 1 
 
 aiu! did not fs?m much to regard the objcfts around a palm b 'anch 
 him. 
 
 CURFEU Bell (fee Curfew, Encyd ), called in 
 t lie la*' Latin of tlie middle ages i^nilfg'uim or pyr'ils- 
 f^iiim, and in Frenjh, cwvrefru — was a fignal for all pcr- 
 :fons to extii:guif!i their fires at a certain hour. In thofe 
 Cf^es people made lircs in their houfes i i a hole or pit in 
 the centre of the floor, under an opening formed in the 
 Toof ; and when the fire was Inirnt out, or the family 
 went to bed, tlie hole was fluit by a cover of wood 
 or of earth. This praAice flill prevails among the cot- 
 tagers in fome parts of Scotland, and we doubt not of 
 other countries. In the dark ages, when all ranks of 
 
 CYC 
 
 It is not folid like the gerid of the 
 date tree, but opens in the part that is without leaves 
 about an inch and a half from the bottom, and out of 
 this aperture proceeds the flower. There is a round 
 (lalk, bare for about an inch and a quarter, from which 
 proceed crooked brandies with hngle flowers attached 
 to their ends ; the ftalk that carries thefe proceeds out 
 of every crook or geniculation. The whole duller of 
 flowers has very much the fhape of a duller of grapes ; 
 the ilalks which Aipport it refemble the flalks of the 
 grape ; and a very few fmall leaves are fcattercd through 
 tiie cinder of flowers. 
 
 " The calyx or flower cup is of a greemjh colour, tin- 
 jieople were turbulent, a law was almoft everywhere ged with purple ; when fully blown it is altogether of 
 
 cilabhfhed, that the tire fliould be extingnilhed at a cer- 
 tain time in the evening ; that the cover fliould be put 
 over the fire-place; and that all the family fliould re- 
 tire to reft, or at leaft keep within doors The time 
 vhen this ought to be done was fignified by the ring- 
 ing of a bell, called therefore the curfcU-beH or ignile^him. 
 Tlie law of William the Conqueror, which introduced 
 this practice into England, as has been mentioned in the 
 lincvclopaedia, was aboliflied by Henry I. in 1100. 
 
 The ringing of the curfeu-bell gave rife to the prayer- 
 liell, as it is called, which is ftill retained in fome Pro- 
 teflant countries. Pope John XXII I. with a view to 
 
 a dtep red or purple ; the corolla is •while, and confifts 
 of five petals ; in the midft is a fliort pillil with a round 
 head, farroundcd by eight ftamina, of the fame form, 
 loaded with yellow tarina. The ciip confifts of five pe- 
 tals, which much refemble another flower ; they are 
 rounded at the top, and nearly of an equal breadth 
 every way. The feed is very fmall, fmaller than even 
 the fen-en fantonicum ; and being likewife very bitter it 
 is ufed in Abyffinia as a vermifuge. From its fmall- 
 nefs, however, and its being very eafily ftied, no great 
 quantity of it is ever gathered, and therefore the flower 
 is often fubftituted in its ftead. The AbyfTinians, fays 
 
 avert certain apprehended misfortunes, which rendered our author, of both fexes, and at all ages, are troubled 
 
 his life uncomfortable, gave orders, that every perfon, on with the fort of worm called afcarides, of which every 
 
 liearing the jfn.Vff/uTO, fhould ix peat tlie .<#i'f j'lfaWfl three individual evacuates a large quantity once a-month. 
 
 times. When the appearance of a comet, and a dread The method of promoting thele evacuations is by in- 
 
 cf the Turks, afterwards alarmed all Chriftendom, Pope fufing a handful of dry cuflb flowers in about two Eng- 
 
 Calixtus III. increafed thefe periodical times of prayer, llfh quarts of bouza, or the beer they make of teff (fee 
 
 by ordering the prayer-bell to be rung alfo at noon. Teff, Encycl.), and after it has been fteeped all night, 
 
 Bechmanri' s Hijlory of Invsntions. the next morning it is fit for ufe. 
 
 CURVE OF Equable Approach. It was firft pro- " The bark of the tree is fmooth, of a yellowifli white. 
 
 pofed by Leibnitz, namely, to find a curve, down which 
 a body defcending by the force of gravity fhaU make 
 equal approaches to the horizon in equal portions of time. 
 It has been found by Bernoulli and others, that the 
 curve is the fecond cubical parabola, placed with its ver- 
 tex uppermoft, and which the defcending body muft en- 
 ter with a certain determinate velocity. Varignon ren- 
 dered the queftion general for any law of gravity, by 
 
 interfperfed with brown flreaks, which pafe through the 
 whole body of the tree. It is not firm or hard, but ra- 
 ther ftringy and reedy. On the upper part, before the 
 firft branch of leaves fet out, are rings round the trunk, 
 of imall filaments of the confiftence of horfe hair : thefe 
 are generally fourteen or fixteen in number, and are a 
 very remarkable charafteriftic belonging to the tree." 
 From this dcfcriptiun, which, it muft be confefled, 
 
 i 
 
 which a body may approach towards a given point by is not remarkable for perfpicuity, and from an infpec- 
 
 cqual fpaces in equal times. And Maupertuis alfo re- 
 folved the problem in the cafe of a body defcending in 
 a medium which refifts as the fquare of the velocity. 
 
 CUSSO, or Bas KsiA Abyssinica, is a beautiful and 
 ufeful tree, indigenous to the high country of Abyfllnia. 
 At leaft Mr Bruce, who has given of it the only defcrip- 
 tion which we have feen, fays that lie never faw it in any 
 
 tion of the figure which Mr Bruce has given of the 
 cuflb, we are inclined to rank it with the palms, as a 
 new genus, neareft to the caryota. 
 
 CUVETTE, orCuNETTE, in fortification, is a kind 
 of ditch within a ditch, being a pretty deep trench, about 
 four fathoms broad, funk and running along the middle 
 of the great dry ditch, to hold water ; ferving both to 
 
 other part of Afia or Africa. It feldom grows above keep ofi the enemy and prevent him from niinmg. 
 20 feet high, very rarely ftraight, generally crooked or CYCLE OF Indiction, is a feries of 15 years, re- 
 inclined. Its leaf, which is of a deep unvarniflied green, turning conftantly around like the other cycles, and 
 having the fore part covered v.'ith i^oft hair or down, is commenced from the third year before Chrift ; whence 
 about 2 J inches long, divided by a ftrong rib into two it happens that if ^ be added to any given year of Chrift, 
 unequal divifions, of which the upper is broader and and the fun be divided by IJ, what remains is the year 
 larger than the lower. It is more indented than even of the inditlion. 
 
 the nettle leaf, which it in fome meafure refembles, only CYCLOID (fee Encycl.) is a curve, which is thus 
 
 the leaf of the {]uffo is narrower and longer. generated : Snppofe a wheel or circle to roll along a 
 
 Thofe leaves grow two and two upon a branch, ha- ilraight line till it has completed juft one revolution ; a 
 
 ving between each two the rudiments of two pair of nail or point in that part of the circumference of the 
 
 leaves, which probably are deciduous ; but the branch is circle, which at the beginning of the motion touches 
 
 terminated with a fingle leaf or Jiipula at the point, the ftraight line, will, at the end of the revolution, have 
 
 The end of this ftalk is broad and ftrong, like that of defcribed on a vertical plane a cycloid, 
 
 DAGELET,
 
 D A r 
 
 [ 473 ] 
 
 D A I 
 
 D. 
 
 Dapfler, "P\AGELET, the name given by La Peroufe, the 
 Diiry. X-y celebrated though unfortunate navigator, to an 
 " • ifland on the coaft of Corea (tee Corea, EncycL), which 
 he difcovered in the year 1787. It is h'ttle more-than 
 three leagues in circumference ; and our author ahnuft 
 made its circuit at the dillance of a mile without finding 
 bottom. This finall fpot is very lleep, but covered with 
 the finell trees from the fea-(hore to the fummit. A ram- 
 part of bare rock, like a wall, encircles the whole out- 
 line of it, with the exception of feven little fandy creeks, 
 where it is poflihle to land. In thcfc creeks the Frerk.h- 
 men faw upon the (locks fome boats of a conllruftion 
 altogether Chinefe ; but the light of their Ihips fright- 
 ened the workmen, who fled from their dock-yard into 
 the wood, which was not more than fifty paces dillant. 
 As a few huts were feen, but neither villages nor cul- 
 tivation, La Peroufe concluded that the ifland is with- 
 out inhabitants, and that the men whom he faw at 
 work were Corean carpenters, who during the fummer 
 months go with provifion to Dagelet for the purpofe of 
 building boats, which they fell upon the continent. He 
 places the northeafl point of this illaud in Lat. 37°. 25'. 
 and E. Long. 129". 2'. from Paris. 
 
 DAIRY is a word which fignifies fonietimes the art 
 of making various kinds of food from nulk ; fomttimes 
 the place where milk is manufaftured ; and fometimes 
 the management of a milk-tarm. On the ilairy, in the 
 fiitl and fccond of thefe fenfe«, enough has been faid in 
 the Er.rycloptJia imder the titles Butteh, (!^heese, 
 and Dairy ; on the management of a milk farm that 
 work contains nothing. 
 
 When a dairy is eftablifhed, the undertaker may 
 fometimes think it his intereft to obtain the greatelt 
 poifible quantity of produce; fometimes it may be more 
 beneficial for him to have it of the fined quality ; 'hnd 
 at other times it may be neceflary to have both thefe 
 objedts in view, the one or the other in a greater or leis 
 proportion : it is therefore of importance that he (hould 
 know how he may accomplifh the one or the other of 
 ihefe purpofes in the eafielt and moll diredt manner. 
 
 To be able to convert his milk to the higheil pofTible 
 profit in every cafe, he ought to be fully acquainted 
 with every circumftance refpefting the manufadture both 
 of butter and of cheefe ; as it may in fome cafes hap- 
 pen, that a certain portiori of that milk may be more 
 advantageoufly converted into butter than into cheefe, 
 while another portion of it would return more profit if 
 made into cheefe. 
 
 The firfl; thing to be adverted to, in an undertaking 
 of this nature, is to choofe cows of a proper fort. A- 
 mong this clafs of animals, it is found, by experience, 
 
 SuppL. Vol. I. Part II. 
 
 that fome kinds give milk of a much thicker confid- 
 ence and richer quality than others ; nor is this rich- ' 
 nefs of quality nccelfarily connefted with the fmallnefs 
 of the quantity yielded by cows of nearly an equal li/e ; 
 it therefore behoves the owner of a dairy to be pecu- 
 liarly attentive to this circumftance. In judging of the 
 value of a cow, it ought rather to be the quantity and 
 the quality of the cream produced from the milk of the 
 cow, in a given time, than the quantity of the milk il- 
 fclf : this is a circumftance that will be flicwn hereafter 
 to be of more importance than is generally imagined. 
 The fmall cows of the Alderncy breed aflord the rich- 
 eft milk hitherto known ; but individual cows in every 
 country may be found, by a careful felcillon, that airor<l 
 much thicker milk than others ; thefe therefore ought 
 to be fearched for with care, and their breed reared with 
 attention, as being peculiarly valuable. 
 
 Few perfons who have had any experience at all ia 
 the dairy, can be ignorant, however, that in comparing 
 the milk of two cows, to judge of their refpetlive qua- 
 lities, particular attention mull be paid to the time that 
 has elapfed fince their calving ; for the milk of the fame 
 cow is alwa) s thinner foon after calving than it is «f- 
 terwardS ; as it gradually becomes thicker, though ge- 
 nerally lels in quantity, in propoition to the time lince 
 the cow has calved. The colour of the milk, foon after 
 calving, is richer than it is afterwards ; but this, efpe- 
 cially for the firll two weeks, is a faulty colour that 
 ought not to be coveted. 
 
 To make the cows give abundance of milk, and of a 
 good quality, they niuil at all times have plenty of 
 food. Grafs is the beft food yet known for this pur- 
 pofe, and that kind of grafs which fprings up fponta- 
 neoufly on rich dry foils is the bell of all. If the tem- 
 perature of the climate be fuch as to permit the cows 
 to graze at eafe throughout the day, they fliould be 
 fuff^ercd to range on fuch pattures at freedom ; but if 
 the cows are fo much incommoded by the heat as to 
 be prevented from eating through the day, they ought 
 in that cafe to be taken into cool fliades for proteftion ; 
 where, after allowing them a proper time to ruminate, 
 they fhould be fupplied with abundance of green food, 
 fri _ -cut for the pnrpole, and given to them by hand 
 frequently, in fmall quantities, frefh and frefli, fo as to 
 induce them to eat it with pleafure. When the heat of 
 the day is over, and they can remain abroad with eafe, 
 they may be again turned into the ])ailure, where they 
 (hould be allowed to range with freedom all night, du- 
 ring the mild weather of fummer. 
 
 Cows, if abundantly fed, fhould be milked three times 
 a-day, during the whole of the fummer feafon (a) ; in 
 3 O the 
 
 Dairy. 
 
 (a) If cows be milked only twice in the day (24 hours), while they have abundance of fucculent food, they 
 will yield a much fmaller quantity of milk, in the fame time, than if they be milked three times. Some atten- 
 tive obfervers think a cow, in thefe circumftances, will give nearly as much milk at each time, if milked three 
 times, as if fhe were milked only twice. This faA, however, has not, that we know of, been afcertained by ex- 
 periment. There can be no doubt but they give more, how much more is not afcertained ; nor, whether it 
 would be advantageous, in any cafe, to milk them four times, or oftxiner ; nor, what efFeA frequent milking pro- 
 duces on the quality of the milk.
 
 DAT [ 474 1 DAI 
 
 Dalo'. the morning early, at noon, and in the evening, jull be- The quantity of cream obtained from the firft-drawn Hiapy^ , 
 
 ^ " ' ■ V fore ni"lu-fall. In the choice of p^^rfons for milking cup was, in every cafe, much fmaller than from that i/—. 
 
 the cows, great caution ihould be employed ; for if which was lall drawn ; and thofe between afforded lefs 
 
 that operation be not carefully and properly performed, or more as they were nearer the beginning or the end. 
 
 not only the quantity of the produce of the dairy will It is unnecelTary here to fpecify thefe intermediate pro- 
 
 be greatly diniinifhed, but its quality alfo will be very portions ; but it is proper the reader (liould be inform- 
 
 niuci) debafed ; for if all the milk be not thoroughly ed, that the quantity of cream obtained from the laft- 
 
 . drawn from a cow whc^n ihc is milked, that portion of drawn cup, from fome cows, exceeded that from the 
 
 niilk which is left in the udder feenis to be gradually firft in the proportion of fixteen to one. In other 
 
 abforUed into the fyftem,and Nature generates no more cows, however, and in particular circumftances, the dif- 
 
 than to fnpply the walle of what has been taken away, proportion was not quite fo great ; but in no cafe did it 
 
 If this leffened quantity be not again thoroughly drawn fall (liort of the rate of eight to one. Probably, upon 
 
 off, it occafions a yet farther diminution of the quan- an average of a great many cows, it might be lound to 
 
 tity of mdk generated ; and thus it may be made to run as ten or twelve to one. 
 
 proceed, in perpetual progrefTion from little to lefs, till Secondly, The difference in the quality of the cream, 
 
 ' none at all is produced. In Oiort, this is the praftice however, obtained from thefe two cups, was much 
 
 ju all cafes followed, when it is meant to allovv' a cow's greater than the difference in the quantity. In the firit 
 
 milk to dry up entirely, without doing her hurt. In cup, the cream was a thin tough film, thinner, and per- 
 
 this manner, therefore, the profits of a dairy might be haps whiter, than writing paper; in tiie lall, the cream 
 
 ■wonderfally diminllhed ; fo that it much behoves the was of a thick butyrous conilllence, and of a glowing 
 
 owner of it to be extremely attentive to this circum- richnefs of colour that no other kind of cream is ever 
 
 flance, if he wifhes to avoid ruin. It ought to be a found to poffcfs. 
 
 rule without an exception, never to allovv this important Thirdly, The difference in the quality of the milk 
 
 department to be entruffed, without controul, to the nia- that remained, after the cream was feparated, was per- 
 
 nagement of hired iervants (b). Its importance will be haps Itill greater than either in relpeCt to the quantity 
 
 Hill more mauiteft from what follows. or the quality of the cream. The milk in the firft cup 
 
 It is to Dr James Anderfon that we are indebted for was a thin bluilh liquid, as if a very large proportion of 
 
 thefe judicious obfervations, as well as for the following water had been mixed v/ith ordinary milk ; that in the 
 
 aphorifms which, though they maybe in part known to lail cup was of a thick confiftence, and yellow colour, 
 
 attentive houfewifes, he has reafon.to believe are not more refembling cream than milk both in tafte and ap- 
 
 commonly adverted to as their importance deferves. pearance. 
 
 - , .p " Of the milk that is drawn from any cov? at one time. From this important experiment, it appears that the 
 
 tliat which comes off at the firft is always thinner, and perfon who, by bad milking of his cows, loles but half 
 
 of a much worfe quality, than that which comes after- a pint of his milk, lofes in faft about as much cream as 
 
 wards ; and the richneis goes on continually increafing would be afforded by fix or eight pints at the begin, 
 
 to the very laft drop that can be drawn from the udder ning, and lofes, befides, that part of the cream which 
 
 at that time." alone can give richnefs and high flavour to his butter. 
 
 Few perfons are ignorant that the milk which is laft " If milk be put into a dilh, and allowed to ftand Anhorifitt 
 
 cf all taken from the cow at milking (In this countrj' till it throws up cream, that portion of cream which 2. 
 
 called Jlronkiiigs) is richer than the reft of the milk ; rifes firft to the furface is richer in quality, and greater 
 
 but fewer ftiU are aware of the greatnefs of the difpro- in quantity, than what rifes in a fecond equal fpace of 
 
 portion between the quality of the firft and the laft time ; and the cream that rifes in the fecond interval of 
 
 drawn milk, from the fame cow, at one milking. The time is greater in quantity, and richer in quality, than 
 
 following fafts (fays our author) refpefking this circum- that which rifes in a third equal fpace of time ; that of 
 
 ftance were alcenaincd by me many years ago, and the third than the fourth, and lo on : the creani that 
 
 have been confirmed by many fubfequent experiments rifes decreafing in quantity, and declining in quality, 
 
 and obfervations. continually, as long as any rifes to the furface." 
 
 Having taken feveral large tea-cups, exaftly of the Our ingenious author confeffes, that his experiments 
 fame fize and ftiape, one of thefe tea-cups was fiU.c at not having been made with fo much accuracy in this 
 the beginning of the milking, and the others at regular cafe as in the former, he was not enabled to afcertain 
 intervals, till the laft, which was filled with the dregs the difference in the proportion that takes place in- 
 of the ftroakings. Thefe cups were then weighed, the equal portions of time ; but they have been fo often re- 
 weight of each having been fettled, fo as to afcertain peated as not to leave any room to doubt the faft, and 
 that the quantity of milk in each was preclfely the it will be allowed to be a fact of no fmall Importance in 
 fame ; and from a great number of experiments, fre- the management of the dairy. It is not certani, how- 
 queatly repeated with many different cows, the refult ever, but that a greater quantity of cream may, upon 
 v.'as in all cafes as follows ; the whole, be obtained from the milk by taking it 
 
 away 
 
 (b") Cows (hould always be treated with great gentlenefs, and foothed by mild ufage, efpecially when young 
 and ticklilh, or when the paps are tender ; in which lift cafe, the udder ought to be fomented with waVm water 
 before milking, and touched with the greateft gentlenefs, otherwife the cow will be in danger of contrafting bad. 
 habits, becoming ftubborn and unruly, and retaining her milk ever after. A cow never lets down her milk plea- 
 
 fantly to the perfon fiie dreads or difllkes. The udder and paps fliould always be walhed with clearv water be- 
 fore milking ; but care ftiould be taken that none of that water be admitted into the milking-pail. 
 
 1.
 
 D A I 
 
 [ 475 1 
 
 D A I 
 
 away at ilHtfreiit times ; but tlic prbccfs is fo troublc- 
 ' fomc as not to be counterbalanced by the incrcafcil quan- 
 tity obtained, if indeed an increafed quantity be tiius 
 obtained, which is not as yet quite certain. 
 
 " Thick milk always throws up a fnialler ])roportion 
 of the cream it adually contains to the furtacc, than 
 milk that is thinner; but that cream is »f a' richer qua- 
 lity. If water be added to that thick milk, it will af- 
 ford a confiderably greater quantity of cream than it 
 would have done it allowed to remain pure, but its qua- 
 lity is, at tlie fame time, greatly debafed." 
 
 This is a faft that every perfon attentive to a dairy 
 tnufl; have remarked ; but I have never (fays our author) 
 heard of any experiment that could afcertain, either the 
 prrcife amount of the increafed quantity of cream that 
 might thus be obtained, or of the ratio in the decreafe 
 of its quality. The eflcfts of mixing water with the 
 milk in a dairy are at leall afcertained ; and the know- 
 ledge of this taCl will enable attentive perfonr, to follow 
 that practice which they think will bell promote their 
 own intereft. 
 
 " Milk which is put into a bucket or other proper 
 veffel, and carried in it to any coniiderable diftaiice, (o 
 as to be much agitated, and in part cooled, before it 
 be put into the milk-pans to fettle for cream, never 
 throws up fo much, nor fo rich cream, as if the fame 
 milk had been put into the milk-pans direitly after it 
 was milked." 
 
 In this cafe, it is believed the lofs of cream will be 
 nearly in proportion to the time that has elapfed, and the 
 agitation the milk has fuftained, after being drawn from 
 the cow. But Dr Anderfon fays that he is not yet in 
 poflcfTion of any experiments which fufficiently afcer- 
 tain how much is to be afcribed to the time, and the 
 agitation, taken feparately. On every branch of agri- 
 culture we find experiments wanting, at each Hep we 
 advance in our inquiries ; and it is the duty of every en- 
 quirer to point out, as he goes along, where they are 
 wanted, fince the labours of no one man can poffibly 
 complete the whole. 
 
 From the above fafts, the following corollaries feem 
 to be clearly deducible : 
 
 Fi:^. It is of importance that the cows (hould be 
 always milked as near the dairy as pofTible, to prevent 
 the neceffity of carrying and cooling the milk before it 
 is put into the dilhes ; and as cows are much hurt 
 by far driving, it mull be a great advantage in a dairy- 
 farm to have the principal grafs fields as near the dairy 
 or homeflead as polfible. 
 
 Secondly. The praftice of putting the milk of all 
 the cows of a large dairy into one velfel, as it is milked, 
 there to remain till the whole milking is finifhed, before 
 uiiy part of it is put into the milk-pans — feems to be 
 highly injudicious ; not only on recount of the lofs that 
 is fuftained by agitation and cooling, but alfo, more 
 efpecially, becaufe it prevents the owner of the dairy 
 from dillinguilhing the good from the bad cow's milk, 
 fo as to feparate thefe from each other, wiiere it is ne- 
 ceffary. He may thus have the whole of his dairy pro- 
 duct greatly debafed by the milk of one bad cow, for 
 years together, without being able to difcover it. A 
 better pradlice, therefore, would be, to have the milk 
 drawn from each cow put feparately into the creaming- 
 pans as foon as it is milked, without being ever mixed 
 with any other. Thus would the careful manager of 
 
 the dairy l)e able on all occafions to obfervc the parti- Hiiy. 
 cular quality of each individual cow's milk, as well as """v-—" 
 its quantity, and to know witli precilion which of hiu 
 cows it was his intereft to difpofe of, and which of thcni 
 he ought to keep and breed from. 
 
 Thirdly. If it be intended to make butter of a very 
 fine quality, it will be advifable in all cafes to keep tin- 
 milk that is firft drawn feparate from that which come.) 
 laft ; as it is obvious, that if this be not done, the (jua- 
 lity of the butter will be greatly debafed, v\'ithout muck 
 augmenting its quantity. It is alfo obvious, that if this 
 is doae, the quality of the butter will be improved in 
 proportion to the fmallnefs of the quantity of the lall- 
 drawn milk that is retained ; fo that thofe who wifti to 
 be fingularly nice in this rcfpeft, will do v^ell to rttaiii 
 only a very fmall portion of the lall-drawn milk. 
 
 To thole owners of dairies who have profit only in 
 view, it muft ever be a matter of trial and calculation, 
 how far it is expedient for them to carry the improving 
 of the quality of their butter at the expence of dimi- 
 nilliing its quantity. In different fituations prudence 
 will point out different kinds of practice as moft eli- 
 gible ; and all perfons muft: be left, after making accu- 
 rate trials, to determine for thcmfelves. It is iikewife 
 a confideration of no Iniall importance, to <letermine in 
 what way the inferior milk, that is thus to be fet apart 
 v.-here fine butter is wanted, can be employed with the 
 greatefl profit. In the Miglilands of Scotland they 
 have adopted, without thinking of the improvement of 
 their butter, a very fimple and economical pratlice in 
 this refpeft. As the rearing of calves is there a prin- 
 cipal object with the farmer, every cow is allowed to 
 fuckle her own calf with a part of her milk, the remain, 
 der only being employed in the dairy. To give the 
 calf its portion regularly, it is feparated from the cow, 
 and kept in an inclofure, with all the other calves be- 
 longing to the fame farm. At regular times, the cows 
 are driven to the door of the inclofure, where the young 
 calves fail not to meet them. Each calf is then fepa- 
 rately let out, and runs diredly to its mother, where it 
 fucks till the dairy-maid judges it has had enough ; ihe 
 then orders it to be driven away, having previoufly 
 fhacklcd the hinder legs of the mother, by a very fim- 
 ple contrivance, to oblige her to Hand Hill. Boys drive 
 away the calf with fwitches, and return it to the inclo- 
 fure, while the dairy-maid milks oft' what was left by 
 the calf: thus they proceed till the whole of the cows 
 are milked. They obtain only a fmall quantity of 
 milk, it is true, but that milk is of an cxceedinir rich 
 quality ; which in the hands of fuch of the inhabitants 
 as know how to manage it, is manufaftured into the 
 richcll marrowy butter that can be anywhere met with. 
 This richnefs of the Highland butter is univerfally a- 
 fcribed to the old grafs the cows feed upon in tlieir 
 remote glens ; but it is in fact chiefly to be attribute! 
 to the praftice here defcribed, which has long prevailed 
 in thofe regions. Whether a fimilar practice could be 
 economically adopted elfewhere, our author takes not 
 upon him to fay ; but doubtlefs other fecondaiy ules 
 might be found for tlie milk of inferior quality. 0,i 
 fome occafions, it might be converted into butter of an 
 inferior quality ; on other occafions, it might be fold 
 fweet, where the fituation of the farm was within reach 
 of a market-town ; and on others, it might be convert- 
 ed into cheefes, which, by being made of fwect milk, 
 3 O i would
 
 Dairy. 
 
 D A I 
 
 would be of a very fine quality if careful) 
 ■ Still other ufes might be devifed for its application ; 
 of which the following is worthy of notice. Take 
 common (l<immcd milk, when it has begun to turn four, 
 put it into an upright ftarid churn, or a barrel with one 
 of its ends out, or any other convenient veffel. Heat 
 fome water, and pour it into a tub that is large enough 
 to contain with eafe the veilcl in which the milk was 
 put. Set the veiTel containing tiie milk into the hot 
 water, and let it remain there for the fpace of one 
 ni"-ht. In the morning it will be found that the milk 
 
 [ 476 ] DAI 
 
 made (c). tion of each cow's milk can be fet apart for throwing Da ry, 
 up cream, and when only a fmall proportion of that -""■*"*■ 
 cream can be referved, of the prime quality, it follows 
 (the quantity of milk being upon the whole very iiu 
 conljtierable), that the quantity of prime cream pro- 
 duced would be fo fmall as to be fcarcely worth maini- 
 laCturing ftparately. 
 
 Sixlh/y. From thefe premifes we are alfo led to draw 
 another conclufion, extremely different from the opi- 
 nion that is commonly entertained on this fubjcft, vr/. 
 That it fccms probable, that the very bed butter could 
 be made with economy in thofe dairies only where the 
 
 has feparated into two parts ; a thick cream like fub 
 
 fiance, which occupies the upper part of the vefl'el, and manufatture of cheefe is the principal objett. The rea- 
 a thin watery part that remains at the bottom. Draw ions are obvious : If only a fmall portion of milk ihould 
 off the thin part (called in Scolhnd luigg), by opening be fet apart for butter, all the reft may be made into 
 a ftop-cock, placed for that purpofe cloie above the cheefe, while it is yet warm from the cow, and perfect- 
 bottom, and referve the cream for ufe. Not much lefs ly fweet ; and if only that portion of cream which rifes 
 than half of the milk is thus converted into a' fort of during the firil three or four hours after milking is to 
 cream, which, when well made, feems to be as rich and be relerved for butter, the rich milk which is left after 
 fat as real cream itfelf, and is only diftinguifhable from that cream is feparated, being ftill perfeAly fweet, may 
 it by its fournefs. It is eaten with fugar, and elleemed be converted into cheefe with as great advantage near 
 
 a great delicacy, and ufually fells at double the price of 
 freih unfeimmed milk. It requires praftice, however, 
 to be able to make this nicely ; the degree of the heat 
 of the water, and many other circumftances, greatly af- 
 fefting the operation. 
 
 Fourthly. If the quality of the butter be the chief 
 obieft attended to, it will be necelTary, not only to fe- 
 
 ly as the newly. milked milk itfelf. 
 
 But as it is not probable that many perfons could bi; 
 found who would be willing to purchafe the very finell 
 butter, made in the manner above pointed out, at a 
 price that would be iuf5cient to indemnify the farmer 
 tor his trouble in making it, thefe hiHts are thrown out 
 merely to fhew the curious in what way butter poffef- 
 
 parate the firft from the lall drawn milk, but alfo to fmg this fuperior degree of excellence may be obtained, 
 take nothing but the cream that is firft feparated from if they choofe to be at the expence ; but for an ordi- 
 the beft milk, as it is this firft rifing cream alone that is "ary market, Dr Anderfon is fatisfied, from experience 
 of the prime quality. The remainder of the milk, which and attentive obfervation, that if in general about the 
 •will be ftill fweet, may be either employed for the pur- firft drawn half of the milk be feparated at each milk- 
 pofe of making fweet milk cheefes, or may be allowed ing. and the remainder only fet up for producing cream, 
 to Hand, to throw up cream for making butter of an and if that milk be allowed to ftand to throw up the 
 inferior quality, as circumftances may direft. whole of its cream (even till it begins fenfibly to tafte 
 Fifthly. From the above fads, we are enabled to fourifhj, and that cream be afterwards carefully mana- 
 perceive, that butter of the very beft poffible quality ged, the butter thus obtained will be of a quality great- 
 can only be obtained from a dairy of confiderable ex- ly fuperior to what can ufually be procured at market, 
 tent, judicioufly managed ; for when only a fmall por- and its quantity not confiderably lefs than if the whole 
 
 of 
 
 (c) The making of eheefe has never yet been reduced to fcientific principles, and confequently the reafoning; 
 relating to it is very inconclufive. It is in general fuppofed, that the goodnefs of cheefe depends almoft entirely 
 upon its richnefs, by which is meant the proportion of oily matter, whether natural or extraneous, it contains ; 
 nothing, however, is more certain, than that this opinion is erroneous. Sometimes a very lean cheefe is much 
 better tailed than one that is much fatter; and, which will appear to moft perfons ftill more extraordinary, it 
 frequently happens that a cheefe that tattes foft and fat is much leaner than one that is hard, dry, and fticky. 
 The mode of manufaauring it occafions this, and not the quantity of cream it contains. It is very poffible by 
 art to make poor fl<ira milk cheefe affume the foft buttery tatte and appearance even of cream cheefe. This i"ub- 
 jeft, therefore, defervcs to be more particularly elucidated than it has hitherto been. 
 
 Connefted as they are with the objeft difcufi"ed in the text, we beg leave with our author to fuggeft the fol- 
 lowing- particulars, as proper objefls of examination and experiment, viz. Is the quantity of cafeous matter af- 
 forded by milk neceffarily connefted with the proportion of cream that milk contains, or does it depend upon 
 fome other principle not hitherto inveftigated ? Without pretending to decide this qucftion, Dr Anderfon feels 
 himfelf ftrongly inclined to believe it does not depend upon the quantity of cream. It is well know^n that cow's 
 milk, v,'hich always throws up more cream, and that of a much riclier quality, than ewe-milk, does in no cafe af- 
 ford above one-half the proportion of cheife that ewe-milk does. Nor can this fingular tendency of ewe-milk, to 
 yield a great proportion of' curd, be attributed to its fuperior thicknefs ; for cow-milk can be often had that is 
 thicker and richer than ewe-milk, but it always affords a much fmallcr proportion of curd. From thefe confi- 
 derations, it is not impoffiblc but it might be found, upon a careful invelligation, that the refufe milk, which ought, 
 to be feparated from the other in making the beft butter, might be equally proper, or very nearly fo, for ma- 
 king cheefe, as if no fuch feparation had been made. We therefore recommend this as a proper objeft of expe»^ 
 vimental enquiry.
 
 D A H 
 
 of the milk had been treated alike. Thi') 
 the pnictice that our author tiiinks molt liktly to fuit 
 the frugal farmer, as his butter, though of a fuperior 
 quality, could be afforded at a price that would always 
 eufure it a rapid fale. 
 
 Dr Anderi'on throws out many other ingenious and 
 ufeful obfervations on this important branch of rural 
 economy. In particular, he points out, in the plainelt 
 manner, the requiiites of a good milk-houfe, which, as 
 he truly obferves, (liould be cool in funimer and warm 
 in winter, fo as to prLl\.rvc a tcmpwature nearly the 
 fame throughout the year. But we have treated of 
 this part of the fubjedt elfcwhere, and muft therefore 
 refer fuch as are defuous to know the Doftor's fenti- 
 iiients on it, to The Letters and Papers nf the Bath and 
 IVeJl-oJ-England Society for the encouragement of agri- 
 culture, &c. or to the eighth volume of The Repertory 
 6j' Am and Manufaaures. 
 
 D AH A LAC," the largeft ifland in the Red Sea, is 
 thus defcribed by Mr Bruce. It is low and even, the 
 foil fixed gravel and white fand, mixed with fliells and 
 other marine productions. It is deltitute of all forts of 
 herbage, at Icaft in fummer, unkfs a fmall quantity ot 
 bent grafs, juft fufncient to feed the few antelopes and 
 goats that are on the iflnnd. There is a very beautiful 
 fpecies of this lad animal found here, fmall, fhort -hair- 
 ed, with thill black (harp horns, having rings upon 
 them, and tliey are very iwift of foot. 
 
 This idand is, in many places, covered with large 
 plantations of acacia trees, which grow to no height, 
 feldom above eight feet, but fpread wide, and turn flat 
 at top, probably by the influence of the wind from the 
 fea. Though in the neighbourhood of Abyfhnia, Da- 
 halac does not partake ot its feafons ; no rain falls here 
 from the end of March to the beginning of October ; 
 but in the intermediate months, efpecially December, 
 January, and February, there are violent (howers for i 2 
 hours at a time, which deluge the ifland, and hil the 
 cifterns fo as to ferve all next ftunmer; for there are no 
 hills nor mountains in Dahalac, and confequently no 
 fprings. Thcfe cifterns alone prclerve the water, and 
 of them there yet remain 370, all hewn out ofthefoh'd 
 rock. They lay thtte weie the works of the Pcrlians; 
 it is more probable they were thofe of the firil Ptole- 
 mies. But whoever were the conftruftors of thcfe mag- 
 nificent refervoirs, they were a very different people 
 from thofe that now pofTefs them, who have not induf- 
 try enough to keep one of the ^70 clear for the ufe of 
 man. All of them are open to every fort of animal, 
 and half full of the filth they leave there, after drinkins; 
 and walhing in them ; yet one of thefe cilleriis, cleaned 
 and fliut up with a door, might afford them wholefome 
 fweet water all the year over. 
 
 After the rains fall, a prodigious quantity of grafs 
 immediately fprings up ; and the goats give the in- 
 habitants milk, which in winter is the principal part of 
 their fubfiitence, for they neither plow nor fow ; all 
 their employment is to work the veffels which trade to 
 the different parts of the coaft. One half of the inha- 
 bitants is conflantly on the Arabian fide, end by their 
 labour is enabled to furnifli with dora (millet or Indian 
 corn) and other provifions the other half who ilay at 
 home ; and when their time is expired, they are relieved 
 by the other half, and fupplied with necelfaries in their 
 turn. But the fullenance of the poorer fort is entirely 
 
 [ 477 ] D A H 
 
 therefore, is fhell and other fifli Their wives and daughters are 
 very bold and expert filherwouien. Several of them, en- 
 tirely naked, fwam off to the vcffel before it came to an 
 anchor, begging handfuls of wheat, rice, or dora. They 
 are vi^ry importunate and Ihirdy beggars, and not eafily 
 put off with denials. , Thefe mifcrable people, who live 
 ill the villages not frequented by barks from Arabia, 
 are fometimes a whole year without tailing bread. Yet 
 fuch is the attachment to their place of nativity, they 
 prefer living in this bare, barren, parched fpot, al- 
 moll in want of necelfaries of every kind, efpecially of 
 thefe effential ones, bread and water, to thofe pleafant 
 and plentiful countries on both fides of them. 
 
 There are in Dahalac twelve villages or towns, of 
 which each has a plantation of doomtrees round it, 
 which furnilh the only manufafture in the ifland. The 
 leaves of this tree, when dried, are of a glolfy white, 
 which might very eafily be niiftaken for fattin : of thefe 
 they make balkets of furprifuig beauty and neatnefs, 
 ftaiaiiig part of the leaves with red or black, and work- 
 ing them into figures very artificially. Our author knew 
 fome of thefe, rcfembling llraw-bafkets, continue full of 
 water for 24 hours, without one drop coming through. 
 They fell thtfe at I^^iheia and Jidda, the largeft of them 
 for four commcfh, or fixpence. This is the employment, 
 or rather amulement, of the men who ftay at home ;. 
 for they work but very moderately at it, and all ot 
 them indeed take fpecial care not to prejudice their 
 health by any kind of fatigue from induftry. 
 
 People of the better fort, fuch as the Shekh and his 
 relatioTis, men privileged to be idle, and never expofed 
 to the fun, are of a brown complexion. But the com- 
 mon fort employed in fiftiing, and thofe who go con- 
 ftantly to fea, are not indeed black but red, and little 
 darker than the colour of new mahogany. 
 
 The inhabitants of Dahalac feemed to be a fimple, 
 fearful, and inotfenfive people. It is the only part of 
 Africa or Arabia (call it which you pleafe) where you 
 fee no one carry arms of any kind : neither gun, knife, 
 nor fword, is to be feen in tlie hands of any one. 
 Whereas at Loheia, and on all the coaft of Arabia, and 
 more particularly ?.t Yamboo, every perfon goes arm- 
 ed ; even the porters, naked and groaning under the 
 weight of their burden and heat of the diiy, have yet a 
 leather belt, in which ihey carry a crooked knife, fo 
 monftroufly long, that it needs a particular motion and 
 addrefs in walking not to lame the bearer. This was 
 not always the cafe at Dahalac ; feveral of the Portu- 
 guefe, on their firft arrival here, were murdered, and 
 the ifland often treated ill, in revenge, by the arma- 
 ments of that nation. The men feemed healthy. They 
 told our author they had no difeafes among them, un- 
 lefs fometimes in fpring, when the boats of Yemen and 
 Jidda bring the fmallpox among them, and very few 
 efcape with life that are infeCled. He did not obferve 
 among them a man that feemed to be fixty years old ; 
 from which he inferred that they are not long livers, 
 though the air fliould be healthy, as being near the 
 channel, and as they have the north wind all fummer, 
 which moderates the heat. 
 
 Dahalac, like all the other iflands in the Red Sea, 
 depends upon Mafuah. The revenue of its governor 
 confifts in a goat brought to him monthly by each of the 
 twelve villages. Every vefTel that puts in there for Ma- 
 fuah pays him alfo a pound of coffee, and every one 
 
 froHJ 
 
 Dahilie.
 
 D A H 
 
 Tiali.ilac. from A labia a dollar oi' pataka. 
 
 » my is ciinciit at Dalialac, excepting Venetian glafs- 
 
 btacls, old and new, of all fizes and colours, broken and 
 whole. 
 
 Altlioiigli this is the mifciTdjle (late of Dalialac at 
 pvefent, matters were widely different in former times. 
 The pearl fiHiery flouriflicd greatly here under the Pto- 
 lemies ; and even long after, in the time of the caliphs, 
 it produced a great revenue, and till the fovereigns of 
 Cairo, of the prefent miferiible race of llaves, began to 
 withdraw themfclves from their dependency on the port, 
 Dahalac was the principal ifland that furnilhedthe pearl 
 filhers or divers. It was, indeed, the chief port for the 
 iifiiery on the fouthern part of the Red Sea, as Sua- 
 kcm was on the north ; and the baflia of Mafnah paffed 
 part of every funimer here, to avoid the heat at his 
 place of lefidence on the continent. 
 
 The fiiliery extended from Dahalac and its iflands 
 nearly to lat. 20". The inhabited iflands furniflied each 
 a bark and fo many divers, and they were paid in wheat, 
 flour, &.C. fuch a portion to each bark for their ufe, 
 and fo much to leave with their family for their fubfift- 
 ence ; fo that a few months employment furnifhed them 
 with every thing neceffary for the reft of the year. The 
 fifnery was rented in later times to the baflia of Sua- 
 l?em ; but there was a place between Suakem and the 
 fuppofed river Frat, in lat. 21° 28' north, called Gun- 
 guniiab, which was referved to the grand lignior in par- 
 ticular, and a fpecial officer was appointed to receive the 
 pearls on the fpot and fend them to Conftantinople. 
 The pearls found there were of the largcfl fize, and in- 
 ferior to none in water or roundnefs. Tradition fays, 
 that this was exclufively the property of the Pharaohs; 
 by which is meant, in Arabian manufcripts, the old 
 kings of Egypt before Mahomet, 
 
 In the fame extent between Dahalac and Suakem 
 -was another very valuable fifhery, that of tortoifes, from 
 which the fineft fhells of that kind were produced, and 
 a great trade was carried on with the Eaft Indies (Chi- 
 na efpecially) at little expence, and with very coniider- 
 able profits. But the immenfe treafures in the bottom 
 of the Red Sea have now been abondoned for near 200 
 years, though they never were richer in all probability 
 than at prefent. No nation can now turn them to any 
 profit but the Englifh Eafl India Company, more in- 
 tent on multiplying the number of their enemies, and 
 weakening themfelves by fpreading their inconfiderable 
 force over new conquefts, than creating additional pro- 
 fit by engaging in new articles of commerce. A fettlc- 
 ment upon the river Frat, which never yet has belong- 
 ed to any one but wandering Arats, would open them 
 ~ a market both for coarfe and fine goods from the fouth- 
 ern frontiers of Morocco, to Congo and Angola, and 
 fct the commerce of pearls and tortoife fliell on foot 
 again. All this feftion of the gulf from Suez, as we are 
 told, is in their charter, and twenty fhips might be 
 employed on the Red Sea without any violation of ter- 
 ritorial claims. The myhrrh, the frankincenfe, foine 
 cinnamon, and variety of drugs, are all in the poffef- 
 fion of the weak king of Adel ; an ufiirper, tyrant, and 
 Pagan, without proteftion, and willing to trade with 
 any fupeiior power that only would fccure him a mifer- 
 able livelihood. 
 
 There are neither horfes, dogs, flieep, cows, nor any 
 fort of quadruped but goats, afTes, a few half-llarved 
 
 [ 478 ] DAL 
 
 No fort of fmall mo- camels, and antelopes r.t Dahalac, which laft are very 
 numerous. The inhabitants have no knowledge of fire- 
 arms, and tiiere are no dogs nor bealls of prey in the 
 iflai.d to kill tfiem; they catch indeed fome few of them 
 ill tiapi-. 
 
 The language at Dahalac is that of the fliepherds, 
 though Arabic, too, is fpokcn by moft of them. Our 
 author Itates the latitude of Dahalac to lie between 15" 
 27' 3'j", and 150 ;;4' 30'' north. 
 
 DALRYMPLE (Sir David), was born in Edin- 
 burgh on the 2Hih of Oftober (N. S.) 1726. His 
 father was iiir James Dalrymple of Hailes, Bart, and 
 his mother Lady Chriftian Hamilton, a daughter of 
 the Earl of Hadiiiton. His grandfather Sir David 
 Dalrymple was the youngefl foil of the firft Lord Stair, 
 and is faid to have Ijeen the ableft of that family, fo 
 much diftinguillied for ability. He was Lord Advo- 
 cate lor Scotland in the reign of George I. and his foa 
 Sir James had the auditorfhip of the exchequer for 
 life. 
 
 The fubjecl of this memoir was educated at Eton 
 fchool, where he was diftinguifhed as a fcholar, and long 
 remembered as a virtuous and orderly youth. In that 
 juftly celebrated fcminary he acquired a clalTical taflc, 
 which, though it was once prevalent in Scotland, has 
 in that country been long on the decline ; and formed, 
 befides, friendOiips to perlons and attachments to things, 
 which accompanied him through life. Hence probably 
 fprung his partiality to Englilh manners and cuftoms, 
 which marked both his public conduft and private coa- 
 verfation, and was the fource of much of his dignity, 
 and fome of his littlenefFes. 
 
 From Eton he returned to Edinburgh, whence, after 
 the ufual courfe of a gentleman's fludies in that univer- 
 fity, he went to Utrecht to fludy the civil law ; and 
 remained there till after the rebellion in 1746. Upon 
 his return to his native country, fo promifing were his 
 parts, and fuch his induflry and fobernefs of mind, that 
 very faiiguine expeftations were entertained of his fu- 
 ture eminence; and in fome refpefts thefe expeftations 
 were not fruflrated. To his intimate friends it was 
 well known, that if left to follow the bent of his own 
 inclinations, he would have devoted his time and his 
 talents to the fludy of antiquities and the belles lettres; 
 in both which departments of literature he was emi- 
 nently qualified to excel. On the death of his father, 
 however, he found his affairs fo very much encumbered, 
 that in order to retrieve them, and to provide for his 
 brothers and fillers, he rcfolved to follow the law as a 
 profefiion, in which fome of his anceflors had made a 
 diftinguifhed figure. 
 
 He was culled to the Scotch bar in 1748, where, 
 notwithflanding the elegant propriety of the cafes which 
 he drew, it mufl be confeffed that his fuccefs did not 
 anfwer the expectations which had been formed of him. 
 This was not owing either to want of fcience or to 
 want of induftry, but to certain peculiarities, which, if 
 not inherent in his nature, were the refult of early and 
 deep-rooted habits. He poffefTed on all occafions a fo- 
 vercign contempt, not only for verbal antithefis, but 
 for well rounded periods, and every thing which had 
 the femblance of declamation; and indeed he was whol- 
 ly unfitted by an ill-toned voice and ungraceful elocu- 
 tion, for fhining as an orator. No wonder, then, 
 that his pleadings, which were never addreffed to the 
 
 paiTions,
 
 DAL [ 479 ] DAL 
 
 ■ paflions, rlid not rival thofe of fome of hia opponents, companied him to the bencli, and brought upon him Da'rym. 
 
 who, pofTcfFed of great rhetorical powers, did nut, h'ke the ridicule of the wits about the court (a) : and we 1*'° , 
 
 "him, cinploy flrokes of irony too fine to be perceived all know, that the charafter even of Socrates himfelf ' 
 
 by the bulk of any audience, but cxprctTed tliemftlves was not able to relift the torrent of ridicule. In exte- 
 
 in full, clear, and harmonious periods. Even his memo- nuation of this foible, it may be obftrved, that by fome 
 
 rials, tliough claflically written, and often replete with of the judges of the court of fefllon perliaps too little 
 
 valuable matter, did not on every occafion pleafe the regard has been paid to form ; and that forms, even ap- 
 
 court ; for they were always brief, and fometimes, as it parently trifling, cannot in legal proceedings be wholly 
 
 was faid, indicated more attention to the minutise of difregarded without involving in danger truth and juf- 
 
 forms than to the merits of the caufe. Yet on points tice. Be this as it may, fiich was the opinion which 
 
 which touched his own feelings, or the interefts of truth the other judges entertained of Lord Hailea's accuracy, 
 
 nnd virtue, his language was animated, his arguments diligence, and dignified manners, that, in the abfence of 
 
 forcible, and his fcrupulous regard to form thrown afide. the prefident, they generally voted him into the vacant 
 
 He was fometimes employed as a depute advocate, chair, 
 which gave him opportunities at the circuits of difplay- fn May 1776 he was appointed one of the lords 
 ing that candour and tendernefs of difpofition which fo commiflioners of jufticiary ; and in that ftation he corn- 
 well becomes the public profecutor in a criminal court, manded the refpedf of all mankind. Fully impreffed 
 Of this the following inllaiice may be worth relating, with a deep fenfe of the importance of his office, he 
 On the firli day of the court at Stirling, he was once feemed, in the criminal court, to lay afide his fingulari- 
 accoiled by another advocate in thefe words : " Sir ties. So far from throwing his whole weight into the 
 David, why is there not a trial this forenoon ? I would fcale of the crown, a charge which has been fometimes 
 be getting on." " There are (replied he) fome unhappy brought, we believe unjullly, againft the Scotch judges, 
 culprits to be tried for their ll'ues ; and therefore it is Lord Hailes, like the judges of England, was always 
 proper that they have time to confer with their men of counfel for the prifoner when the king's counfel appear- 
 law." " That is of little confequence (faid the other), ed too ftrong for their opponents, or when there was 
 Lafl year I came to vitit Lord Kamcs when he was any particular intricacy in the cafe. In adminillering 
 here on the circuit, and he appointed me counfel for a the oath to the wituefl'es, he had none of that indeco- 
 man accufed of a rape. Though I had very little time rum which we have elfewhere ceufured in fome of his 
 to p>"epare, yet I made a decent fpeech." " Pray, Sir, brethren (fee Oath, Encycl.^; but rifmg folemnly from 
 (faid Sir David), was your client acquitted or con- his feat, he repeated the words in fo ferious a manner, 
 demned ?" " O (replied the other), moft unjuftly con- as left no doubt in the moft profligate mind but that 
 demned." " That, Sir, (faid the depute advocate) is he was himfelf impreiied with a fenfe of the immediate 
 no good argument for hurrying on trials." prefence of the Supreme Being, and with the firm be- 
 To return from this digreffion, if it be corfidered as lief of a future judgment. When the witnefs appeared ; 
 fuch, it is furely to the honour of Sir David Dalrymple, to be young or ignorant, we have beheld, with the ut- 
 that whatever men thought of his fingularities, his de- moft love and veneration, the pious pains which his 
 traftors concurred with his admirers in believing him Lordfhip took to difcover whether he was duly ac- 
 incapable of mifleading the judge by a falfe ttatement of quainted with the nature and obligation of an oath, be- 
 fadls ; or his clients, by holding out to them fallacious fore he admitted him to fwear; and thoiio-h it is per- 
 grounds of hope. haps impoffible for human vigilance and fagacity to pre- 
 His high i'enfe of honour, and his inflexible Integri- vent perjury altogether in courts of juftici» he mult 
 ty, were indeed univerfally admitted ; and it was witli furely have been a villain uncommonly hardened and art- 
 the warmeft approbation of the public, that in i"65 he ful who could perjure himfelf in the prefence of Lord 
 was appointed one of the judges of the court of feflion, Hailes. In doubtful cafes his Lordlliip inclined always 
 the higheft civil tribunal in Scotland. He took his to the fide of mercy; but when it became his duty tp 
 feat on the bench, according to the ufage of that court, pafs fentence of death upon convicted criminals, he ad- 
 by the title of Lord Hailes, the defignation by which drefl'ed them in a llrain of fuch piety and commlfera- 
 he is generally known among the learned of Europe ; tion, as to draw tears from the. eyes of every beholder, 
 and the expeftations entertained of him were again fan- and was calculated to make a deep and proper impref- 
 guine. His unwearied affiduity in fifting dark and in- fion on the unhappy perfon himfelf. In the difcharge 
 tricate matters to the bottom was well known ; his ele- of this painful duty, we never faw liim furpafled, and 
 gant and conclfe manner of expreffing his fentiments have feldom feen him equalled. 
 
 was admirably fultcd to the charafter of a judge ; and Had Lord Hailes been confpicuous only as a found 
 his legal opinions had been generally found. Yet it lawyer and an able and upright judge, we (liould not 
 muft; be confefled, that as a judge he was neither fo ufe- have thought his life intltled to a place in this Work ; . 
 ful nor fo highly revered as he ought to have been from but he was no lefs eminent as a man of general erudi- 
 the extent of his knowledge, and his unqueilloned in- tion, and as a voluminous author. His n<ill in claflical - 
 tegrity. The fame minute attention <o forms, which learning, the belles lettres, and hiftorical antiquities, 
 had in fome degree obllrutted his rife at the bar, ac- efpecially thofe of his own country, is univerfally admit- 
 ' ted y 
 
 (a) In a fatirical ballad on the court of feflion, Mr Bofwell, alluding to Lord Hailes's fondnefs for verbal cri«- 
 
 ticifm, makes him addrefs the prefident in the following words : 
 
 To judge ot this matter 1 cannot pretend. 
 For juftjce, my Lord, wants an c at the end.
 
 DAL 
 
 C 480 ] 
 
 DAL 
 
 ted ; but it cannot be denied, that the fame fadidiouf- 
 nefs, and the fame microfcopic attention to minutiae, 
 which charaaerifed Tiim as a harritler, prevented him 
 from rifing to that rank in the republic of letters to 
 which his learning and genius would othervvife have in- 
 fallibly carried him. But if he was not one of the mod 
 celebrated writers of the age, he was unqueftionably one 
 of the moil virtuous; if his publications were not al- 
 way . edifying, they were at lead innocent and ingeni- 
 ous ; and fome of them are in the highed degree valu- 
 able. In proof of this aflertion, we need indance only 
 liis Annals of Scotland, and his Inquiry into the Seconda- 
 ry Ciiufes 'which Mr Gibbon has ajftgned for the Rapid 
 Progrcfs of Chrijlianity. Of the former of thefe works, 
 though little calculated to pleafe the common herd of 
 readers, it may with truth be faid, that in refearch and 
 ingenuity it dands unrivalled among the writings of 
 Scotch antiquaries ; and of the latter, it is furely not 
 too much to fay, that it difplays uncommon acumen, 
 clofenefs of reafoning, and zeal for the caufe of truth, 
 without the ufual rancour of theological controverfy. 
 
 His tafte for retirement, which the date of his af- 
 fairs rendered for a while neceffary, grew upon him as 
 he advanced in years. His conditution, of which he 
 was very careful, as well as liis principles and habits, ren- 
 dered him averfe from didipalion of every kind. After 
 ■he was made a judge, he confidered abdradlion from 
 the gay and faftiionable world as connetted with the 
 duty of one whole time was no longer his own ; and 
 when he chofe to unbend his mii'.d, it was in the focie- 
 ty of a few eafy friends, whom he fekcttd as much for 
 their worth and good humour as for their genius or 
 their learning. He had indeed occalionally yuch con- 
 vcrfation with that conftellation of wi'.s and men of 
 fcience who fiourifhed in Edinburgh at the fame period 
 -with hiiiiiclf ; but it was impoflible for frlendfliip or in- 
 timacy to fubfid between men who thought fo difte- 
 rently as he and they thought on the mod important of 
 all iubjeCls. Though an old-fadiluned whig, zealuufly 
 attached to the conllitution, he fcorned to take any 
 fhare In the civil or eccleliadical broils in which lome 
 of his brother judges were warmly engaged for the hrd 
 20 years of the prefent reign ; for he looked on thefe 
 as either frivolous or mifchievous. 
 
 Although hij Lorddiip's conllitution had been long 
 in an enfeebled itate, he prolecuted his ftudies, and at- 
 tended his duty on the bench, till within three days of 
 his death, which happened on the 29th of November 
 J 702, in the 66th year of his age. 
 
 His Lordfliip was twice married ; by his firft wife 
 Anne Brown, only daughter of Lord Coaldon, one of 
 the judges of the court of ftflion, he left ifuie one 
 daughter, who inherits the family cftate. His fecond 
 marriage (of which alfo their is iffue one daughter) was 
 to Helen Fergudbn, younged daughter of Lord Kilker- 
 ran, who has the affliction to furvive him. Leaving 
 no male iffue, the title of Baronet dcfcends to his ne- 
 phew. 
 
 Though the church of Scotland does not much en- 
 courage funeral difcourfes, a very laudable endeavour 
 was made to render the talents and virtues of Lord 
 Hailes a theme of Indruftion to mankind, in a .rnion 
 preached foon after his death In the church of Inverelli, 
 by his learned friend and venerable pallor Dr Carlyle ; 
 
 from which we (hall tranfcribe a fummary view of his 1 
 charafter as a judge, a fcholar, a Chrillian, and a citi- 
 zen. 
 
 " His knowledge of the laws was a<*CHrate and pro- 
 found, and he applied it in judgment with the mod 
 fcrupulous integrity. In his proceedings in the crimi- 
 nal court, the facisfaftion he gave to the public could 
 not be furpafled. His abhorrence of crimes, his tender- 
 nefs for the criminals, his rcfpedl for the laws, and his 
 reverential awe of the Omnifcient Judge, infpired him 
 on fome occaf)ons with a commanding fublimity of 
 thought, and a feeling folemnlty of expreflion, that 
 made condemnation feem jnll as the doom of Provi- 
 dence to the criminals themfulves, and r.ilfcd a falutar^' 
 horror of crimes in the bread of the audience. 
 
 " Confclous of the dignity and importance of the 
 high office he held, he never depaited from the deco- 
 rum that becomes that reverend charafter ; which In- 
 deed It coft him no effort to fupport, becaufe he afted 
 from principle and fentimcnt, both public and private. 
 Affedtlonate to his family and relations, fimple and mild 
 in his manners, pure and confcientious in his morals, en- 
 lightened and entertaining In his converfation ; he left 
 foclety only to regret, tliat, devoted as he was to more 
 important employments, he had fo little time to fpare 
 for intercourfe with them. 
 
 " He was well known to be of high rank in the re- 
 public of letters, and his lofs will be deeply felt through 
 many of her departments. His labours, in illullration of 
 the hiilory of his country, and many other works of 
 profound erudition, remain as monuments of his accurate 
 and faithful refearch for materials, and his found judge- 
 ment in the felection of them. Of his unfeigned piety 
 and devotion, you have very often been wltneifes where 
 we now are. I mud add, however, that his attendance 
 on religious ordinances was not merely out of refpect to 
 the laws and for the fake of example (motives which 
 lliould never fail to have Influence on perfons of fuperlor 
 rank, for the moll obvious reaions), but from principle 
 and convlftion, and the mod confcientious regard to his 
 duty ; for he not only piatllfcd all the virtues and cha- 
 rities in proof of his faith, but he demonllrated the hn- 
 cerlty of his zeal by the uncommon pains he took to 
 illuftrate primitive Chridianity, and by his elaborate 
 and able defences of it agalnft Its enemies. 
 
 " His profound refearches into hiilory, and his tho- 
 rough knowledge of the laws, made him perfectly ac- 
 quainted with the progrefs of the conftitution of Bri- 
 tain, from the fird dawn ot liberty in the common law 
 of the land, and the trial by jury, which precede all 
 written records, and afterwards in the origin and eda- 
 blldiment of parliaments, through all its vicIITitudes and 
 dangers, till at laft, by the bkffiiig of divine Providence, 
 which brought many wonderlul events to concur to the 
 fame end, it was renewed, ilrengthened, and finally con- 
 firmed by the Revolution. 
 
 " It was this goodly and venerable fabric of the Bri- 
 tlfli conditution which the deceafed moll rcfpeftable 
 character contemplated with admiration and delight (of 
 late, indeed, with a mixture of anxiety and fear), as 
 the temple of piety, as the genuine fource of greater 
 happinefs and freedom, to a larger portion of mankind 
 than ever flowed from any government upon earth. 
 " 111 indeed can the times bear the lofs of fuch an 
 
 afFedionate
 
 DAL [ 
 
 afFeAionate patriot and able guardian of the laws of his 
 country. But we nnift not murmur at the will of Pro- 
 vidence, which in its mercy ' may have withdrawn the 
 good man from the evil to come.* In mercy, I fay, 
 to him, whofe righteous fpirit was fo deeply grievtd 
 when ' he faw the wicked rage, and the people imagine 
 a vain thing." 
 
 Such is the memorial which, in the hour of recent 
 forrow, followed this excellent man to the grave ; and 
 we believe it will yet be allowed to be juft by all who 
 had the happinefs of his Lord (hip's acquaintance, and are 
 'what he was, friends to the heft interclls of mankind. 
 
 This (ketch of the life of Lord Hailes would be more 
 imperfeft than even it is, if we could not fubjoin to it 
 a catalogue of his publications, of which the greater 
 part are exceedingly curious. We call them publica- 
 tions, becaufe he employed almoft as much of his time 
 in republlfhing old and ufeful books as in preparing for 
 the prefs his own valuable works. 
 
 Befides his elTays in the papers called The ll^orlj and 
 The Mirror, which are well known and univerfally ad- 
 mired, his Lordfhip publiihed the following works : 
 
 Sacred Poems, or a Colleftion of Tranflations and 
 Paraphrafes from the Holy Scriptures ; by various au- 
 thors, Edinburgh, 1751, • 2mo. Dedicated to Charles 
 Lord Hope, with a preface of ten pages. 
 
 The Wifdom of Solomon, Wifdom of Jefus the Son 
 of Sirach, or Ecelefiafticus, i zmo, Edin. 175 j. 
 
 Scleft Difcourfes (in number nine), by John Smith, 
 late Fellow of Queen's College, Cambridge, i2mo, 
 291 pages. Edin. i']^6; with a preface of five pages, 
 " many quotations from the learned languages tranfla- 
 ted, — ;ind notes added, containing allufion.s to ancient 
 mythology, and to the erroneous philofophy which pre- 
 vailed in the days of the author, — various inaccuracies 
 of ftyle have been corrcdled, and bar(h eKpreffions foft- 
 ened." 
 
 A difcourfe of the unnatural and vile Confpiracy 
 attempted by John Earl of Gowry and his brother, 
 againll his Majefty's perfon, at St Johnftoun, upon the 
 ^th of Aug. 1600. No date of the republication, but 
 the edition and notes fiippoled by Lord Hailes, j2mo, 
 
 A Sermon, which might have been preached In Eaft 
 Lothian upon the 2ijth day of October 1761, on Adls 
 xxviii. I, 2. " The barbarous people fhewed us no 
 little kindnefs." Edin. 1761, pp. 25, izmo. " Oc- 
 cafioned by the country people pillaging the wreck of 
 two velfels, viz. the Betfy, Cunningham, and the Leith 
 Packet, Pitcairn, from London to Leith, call away on 
 the Ihore between Dunbar and North Berwick. All 
 the patTengers on board the former, in number 17, pe- 
 rllhed ; five on board the latter, Oftober 16. 1761." — 
 .A. moll affefting difcourf.', admirably calculated to con- 
 vince the oftenders ! 
 
 Memorials and Letters relating to the Hlftory of 
 Britain, in the reign of James 1. publiihed from the 
 originals, Glafgow, 1762. — Addrefled to Philip Yorke, 
 Vlteount Royllon, pp. 151. " From a coUeftion in 
 the advocate's library, by Balfour of Denmyln." The 
 preface of four pages, figned Dav. Dalrymple. 
 
 The works of the ever memorable Mr John Hales 
 of Eaton, now firft collefted together Id 3 vols, Glaf- 
 gow, 1765 ; preface of three pages. Dedicated to 
 William (Warburton), Biihop of Gioucefter 
 
 So»»i. Vol. L Part IL 
 
 481 ] DAL 
 
 edition fald to be undertaken with his approbation ', Djltytn. 
 obfolete words altered, with correftions In fpelling and 1 
 punckuation." — v— - 
 
 A fpecimen of a book entitled " Ane Cotnpemllous 
 Booke of Godly and Spiritual Sangs, coUetlit out of 
 fundrie parts of the Scripture, with fundrie of other Bal- 
 Lites changed out of propliaine Sanges, for avoydiii;r of 
 Sin and Harlotrie, with augmentation of lundry Gude 
 and Godly Ballates, not contained in the firll edition 
 Edinburgh, printed by Andro Hart." i.'mo. Edi.:. 
 176J, pp. 42 ; with a GlolTary of four pages. 
 
 Memorials and Letters relating to the Hiftory of 
 Britain in the reign of Charks I. publiihed froi.i the 
 originals, Glafgow, 1766, pp. 189. Preface of fix 
 pages, figned Dav. Dalrymple, chiefly collefted by Mr 
 Wodrow, author of the Hiftory of the Church of Scot- 
 land. Infcrlbed to Robert Dundas of Arr.iflon, Lord 
 Prefident of the Court of Seflion. 
 
 An account of the prefervation of Charles II. ^''ler 
 the Battle of Worctiler, drawn up by himfelf ; to 
 which are added, his Letters to fcveral perfons. Glaf- 
 gow, 1766, pp. 190, from the MSS. of Mr Pepys, dic- 
 tated to him by the king himfelf, and communicated by 
 Dr Sandby, mailer of Magdalen College. The letters 
 are coUedlcd from various books ; fome of them now 
 firft publiihed, commur.icated by the tutors of the Duke 
 of Hamilton, by the Earl cf Dundonald, &c. The 
 preface of four pages, figned Dav. Dnlryniple, dedica- ' 
 
 ted to Thomas Holies, Duke of Newcaftle, chancellor 
 
 of the unlverfity of Cambridge. 
 
 The Secret Correfpondence between Sir Robert Ce- 
 cil and James VI. i 2mo, 1766 
 
 A catalogue of the Lords of Seflion, from the In- 
 ftitution of the College of Juftice In the year i;^3, 
 with Hiftorical Notes. Suum cuique- rcpendet pnjleritas. 
 Edin. I7''>7, 4to, pp. 26. 
 
 The Private Correfpondence of Dr Francis Atter- 
 bury, Bilhnp of Rocheller, and his friends, in 1725, ne- 
 ver before publiihed. Printed in 1768, 410. Advcr- 
 tifement, pp. 2. Letters, pp. 10. A fac fimile of 
 the firft from Blfhop Atterbury' to John Cameron of 
 Lochiel, to prove their authenticity. 
 
 An examination of fome of the Arguments for the 
 High Antiquity of Regiam Majejlatem ; and an In- 
 quiry Into the authenticity of the Leges Malcolmi , by 
 Sir David Dalrymple, 4to, pp. 52. Edin. 1769. 
 
 Hiftorical Memoirs concerning the Provincial Coun- 
 cils of the Scottifh Clergy, from the earlieft Accounts 
 to the iEra of the Reformation ; by Sir David Dal- 
 rymple. Edinburgh, 1769, 4to, pp. 41. — Nota, Ha- 
 ving no high opinion of the popularity of his writings, 
 he prefiy.es to this work the following motto : " Si de- 
 leftamur quum fcribimus quis eft tarn invidus qui ab eo 
 nos abducat ? fin laboramus quis eft qui alieua; modum 
 ftatuat induftrls." — Ciceio. 
 
 Canons of the church of Scotland, drawn up in the 
 Provincial Councils held at Perth, A. D. 1242, and 
 1269. Edinburgh, 1769, 4to, pp. 48. 
 
 Ancient Scottlfti Poems, publiihed from the MS. of 
 George Bannatyne, 1568. Edin. 1770, l2mo. Pre- 
 face fix pages; Poems pp. 221 ; veiy curious notes 
 pp. 02 ; gloffary and lifts of paftages and words not 
 underftood, pp. 14. 
 
 The additional cafe of Elizabeth, claiming the title 
 " The and dignity of Countefs of Sutherland ; by her Guar- 
 
 3 P dians.
 
 DAL 
 
 [ 482 ] 
 
 DAL 
 
 Dalrym- dians. Wherein the fadls and arguments in fupport of 
 
 P'^^ ^ her claim are more fully ftated, and the errors in the 
 
 ' additional cafes for the other chimants are detefted, 
 
 4to.^ This fingidarly learned and ahle cafe was fub- 
 
 fcribed by Alexander Wedderhurn (piefent Lord Chan- 
 cellor), and Sir Adam Fergnffon, but is the well-known 
 V'ork of Lord Hailes. It ought not to be regarded 
 merely as a law-p^per of great ability, but as a trcatile 
 t)f profound refcarch into the hiilory and antiquity of 
 many important and general points of fucceJTion and 
 family hiilory. Introduftion, pp. 21 ; the firft four 
 chapters pp. 70 ; the fifth and fixth chapters pp. 177. 
 
 Remarks on the Hlflory of Scotland, by Sir David 
 Dalrymplc. — " Utinam tarn facile vera invenire pofTem 
 quarn falfa convincere," Cicero. — Edin. 177.?, infcribed 
 to George Lord Lyttleton, in nine chapters, pp. 284. 
 12mo. 
 
 Hubert! Langueti Epiftolse ad Philippum Sydneium 
 Equitem Anglum, accurante D. Dalrymple de Hailes, 
 Eq. Edinburgh, 1776, 8vo. Infcribed to Lord Chief 
 Baron Smythe. — Virorum Eruditorum Teftimonia de 
 X.angueto, pp. 7. Epiftolse, pp. 289. Index Nominum, 
 pp. 41. 
 
 Annals of Scotland, from the Acceffion of Malcolm 
 III. furnamed Canmore, to the Acceflion of Robert I. 
 by Sir David Dalrymple. Edin. 1776, pp. 311. Ap- 
 pendix, pp. 51. 
 
 Tables of the Succeffion of the Kings of Scotland, 
 from Malcolm III. to Robert I. their marriages, chil- 
 dren, and time of their death ; and alfo of the Kings 
 of England and France, and of the Popes who were 
 their contemporaries. 
 
 Chronological Abridgement of the Volume, pp. 30. 
 The Appendix contains eight differtatlons : i. Of the 
 law of Evenus and Mercheta Mulierum, pp. 17. 2. A 
 commentary on the 22d ftatute of William the Lion, 
 , pp. 8. 3. Of the 1 8th ftatute of Alexander III. pp. 5. 
 4. Bull of Pope Innocent IV. pp. 6. 5. Of Walter 
 Stewart Earl of Mcntetth, 1296, pp. 7. 6. Of M'Duif, 
 Ilain at Falkirk in 1298, pp. 3. 7. Of the death of 
 John Comyn, loth February, 1305, pp. 4. 8. Of 
 the origin of the houfe of Stuart, pp. 6. 
 
 Annals of Scotland, from the Acceflion of Robert I. 
 furnamed Bruce, to the Acceffion of the Houfe of 
 Stuart; by Sir David Dalrymple, Edin. 1779, 4to, 
 pp. 277. Appendix, pp. 54, containing, T. Of the 
 manner of the death of Marjory, daughter of Robert I. 
 pp. 7. 2. Journal of the campaign of Edward III. 
 1327, pp. 9. 3. Of the genealogy of the family of 
 Seton in the 14th century. 4. Lift of the Scottilh 
 commanders at the battle of Hallidon, 19th July 1383, 
 pp. II. 5. Whether Edward III. put to death the 
 ion of Sir Alexander Seton, pp. 8. 6. Lift of the 
 Scottifh commanders killed or made prifoners at the 
 battle of Durham, pp. 8. 7. Table of kings, p. i. 
 8. Correftions and additions to volume i. pp. 16. Chro- 
 nological abridgement of the volume, pp. 39. 
 
 Account of the Martyrs of Smyrna and Lyons, in 
 the 2d century, 1 2mo, with explanatory tiotes, Edin. 
 1776. Dedicated to Biftiop Hurd, pp. 68. Notes and 
 illuilrations, pp. 142. This is a new and correft ver- 
 fion of two molt ancient cpiftles, the one from the church 
 at Smyrna to the church at Philadelphia ; the other 
 from the Chriftians at Vienna and Lyons to thofe in 
 Afia and Phrygia — their antiquity and authenticity are 
 
 undoubted. Great part of both is extrafted from Eu- 
 febius's Ecclefiaftical Hiilory. The former was firft 
 completely edited by Arclibilhop Ulher. The author 
 of the notes fays of them, witii his ufual and lingular 
 modcfty, " That they will afford little new or intertft- 
 ing to men of erudition, though they may prove of 
 fume benefit to the unlearned reader." But the eru- 
 di ion he poffefled in thefe branches is fo rare, that this 
 notice is unneceifary. They difplay much ufeful learn- 
 ing and ingenious criticifm, and breathe the moll ardent 
 zeal, connefted with an exemplary knowledge of Chri- 
 ftianity. N. B. This is the firft volume of the remains 
 of Chriftian Antiquity. 
 
 Remains of Chriftian Antiquity, with explanatory 
 notes, vol. ii. Edin. 1778, I 2mo. Dedicated to Dr 
 Newton bifhop of Brillol. Preface, pp. 7. This vo- 
 lume contains the trial of Juftin Martyr and his com- 
 panions, pp. 8. Epiille of Dionyfius bilhop of Alex- 
 andria, to Fabius bilhop of Antioch, pp. 16. The 
 trial and execution of Cyprian bilhop of Carthage, pp. 
 8. The trial and execution of Fruftuofus bifhop of 
 Tarracona in Spain, and of his two deacons, Augurius 
 and Eulogius, pp. 8. The maiden of Antioch, pp. 2. 
 Thefe are all newly tranflated by Lord Hailes from Rui. 
 nart, Eufebius, Ambrofe, &C. The notes and illuilra- 
 tions of this volume extend from p. 47 to 165, and 
 difplay a moft intimate acquaintance with antiquity, 
 great critical acumen, both in elucidating the fenfe and 
 detedling interpolations ; and above all, a fervent and 
 enlightened zeal, in vindicating fuch fentiments and 
 Gondutt as are conformable to the word of God, againft 
 the mahcions farcafms of Mr Gibbon. To this volume 
 is added an Appendix of pp. 22, correfting and vindica- 
 ting certain jjarts of vol. i. 
 
 Remains of Chriftian Antiquity, vol. iii. Edin. 1780. 
 Dedicated to Thomas Balguy, D. D. Preface, pp. 2. 
 It contains the Hiftory of the martyrs of Palcftine in 
 the third century, tranflated from Eufebius, pp. 94. 
 Notes and iUuftrations, pp. 135 ; in which Mr Gibbon 
 again comes, and more frequently, under review. — The 
 partiality and mifreprcfentations of this popular writer 
 are here expofed in the calmeft and moft fatisfadlory 
 manner. 
 
 Pity it is that Lord Hailes fliould have printed and 
 publlfhcd thefe valuable volumes, and indeed moft of 
 his other works, at his own expence ; and difperfed 
 them fo liberally to his friends, that they have been 
 little circulated among any other. 
 
 Odlavius, a Dialogue, by Marcus Minucius Felix. 
 Edin. 1781, pp. 16. Preface. — The fpeakers are, Cos- 
 cilius a Heathen, Oftavius a Chriftian ; whofe argu- 
 ments prevail with his friend to renounce Paganifm and 
 become a Chriftian profelyte. Notes and iUuftrations, 
 pp. I 2-. 
 
 Of the Manner in which the Perfecutors died ; a 
 Treatife, by L. C. F. Laftantius, Edin. 1782. In- 
 fcribed to Dr Porteous biftiop of Chefter (prefent bi- 
 fliop of London J. Preface, pp. 37, in which it is pro- 
 ved that Laftantius is the author. Text, pp. 125. 
 Notes and iUuftrations, pp. 109. 
 
 L. C. F. Laftantii Divinarum Inftitutionum Liber 
 Quintus feu de Juftitia, 1777. 
 
 DifquifitioMS concerning -the Antiquity of the Chri- 
 ftian Church. Glafgow, 1783. Infcribed to Dr Ha- 
 lifax biftiop of Gloucefter, pp. 194. — This fmall origi- 
 
 . nal
 
 DAL r 483 1 DAL 
 
 Dsliyra- nal and mod excellent work confifls of fix chapters, rcjeftcd all words and plinifcs of French origin, and r-.Iiyni- 
 
 h'^I Chap I. A commentary on the coiidiiiJi and charaftcr written entirely in the Anglo Saxon dialed. In the l''"' 
 
 "" ' of Gallic. Afts xviii. 5, 12, 17. — Chap. 2. Of the courfe of the notes many obfciirilies of the original^ not """J^- 
 
 time at which the Chriftian religion became publicly 
 known at Rome. — Chap. 3. Caufe of the perlecntion 
 of the Chriftians under Nero. In this the hypothefis 
 of Mr Gibbon, vol. i. 4to, p. 641, is examined. — 
 Cliap. 4. Of the eminent Heathen writers who are 
 faid (by Gibbon) to have difregarded or contemned 
 Chridianity, viz. Seneca, Pliny fen. Tacitus, Pliny jun. 
 Galen, Epittctus, Plutarch, Marcus Antoninus. To 
 
 adverted to by other commentators, are explaiiied. 
 Some ftrange inaccuracies of Mr Gibbon are alio de- 
 tcfted, not included in the mifreprefentatioiis of his two 
 famous chapters. 
 
 Tliis was the laft work of this truly learned, rcfpedl- 
 ablc, and ufefiil man. Whether he left behind liim any 
 tiling elfe finifhed for the prefs, is known only to his 
 friends. We have repeatedly heard tiiat he was enga- 
 
 the admirers of Heathen philolophers, and to thofe ef- ged in examining the authenticity of the books of the 
 pecially who flate between them and the Chrillian doc- New Teftament, and that, with the exception of two 
 trine any confanguinity, this chapter is earneilly rccom- or three, he found every verfe contained in it in the 
 mended. — Chap, 5. llludration of a conjefture by Gib- writings of the firft three centuries. Tliis feems in- 
 bon, refpeifting the filence of Dio Caflius concerning deed to have been an objeft in all his works • for at 
 the Chriftians. In this chapter, with extreme impar- the end of each of his tranflations and editions of the 
 tiality, he amplifies and fujiports an idea of Mr Gibbon primitive Chrillian writers, a table is given of paflages 
 on this head. Chap. 6. Of the circumltance.'; rcfpetl- quoted or mentioned by them. If his Lordfliip com- 
 ing Chrillianity that arc to be found in the Auguilan pleted any work of this kind, it (liould not be with- 
 hiftory. held from the public. We may indeed be told that its 
 
 It feems very probable that the clofe attention which utility is in a great meafure fuperfeded by the laborious 
 Lord Hailes appears to have given to fuch fubjefts, was colle£lions of Lardner (b), and the more elegant work 
 in fome meafure the efFeft of the miftakes and partiality of Paley (c) ; but not to mention the prejudices eene- 
 of Gibbon. In no one work from 1776, the date of rally entertained againft Lardner on account of his evi- 
 Mr Gibbon's firft publication, has he omitted to trace dent bias to Unitarianilm, it would fuiely be proper, in 
 this unfair and infinuating author; but in 1786 he the prefent age of wild opinions, to (hew the multitude, 
 came forth of fet purpofe with the moft able and for- who are guided by authority, how important a fubieft 
 midable reply which he has received, intitled, " An the Chriftian religion was deemed by this learned and 
 Inquiry into the Secondary Caufes which Mr Gibbon accompliftied layman. 
 
 has aftigned for the rapid growth of Chrillianity ; by DARCY (Count), an ingenious philofopher and ma- 
 
 Sir David Dalrymple." Edin. 1786 ; gratefully and thematician, was born in Ireland in the year 172c ; but 
 affedionately infcribed to Richard (Hurd) Biihop of his friends being, like many other great and good families 
 Woreeftcr, 410, pp. 213. In five chapters. at that period, attached to the houfe of Stuart, he was at 
 
 Sketch of the Life of John Barclay, 4to, i 786. 14 years of age lent to France, where he fpent the reft of 
 
 Sketch of the Life of John Hamilton, a Secular his lite. Giving early indications of a genius for fcience, 
 Prieft, 4to (one of the moft favage and bigotted adhe- he was put under the care of the celebrated Claiiaut 
 rents of Popery, who lived about A. D. 1600.) (fee Clairaut, Eiicycl ), under whofe tuition he ira- 
 
 Sketch of the Life of Sir James Ramfay, a general proved lo rapidly in the mathematics, that at 17 years 
 officer in the armies of Guftavus Adolplius king of of age he gave a new folution of the problem concern. 
 Sweden, with a head. ing the curve of equal preffure in a refifting medium. 
 
 Life of George Leflie (an eminent capuchin friar in This was followed the year after by a determination of 
 the early part of the 17th cerrtury, 4to, pp. 24. the curve defcribed by a heavy body, fliding by its own 
 
 Sketch of the Life of Mark Alex. Boyd, 4to. weight along a moveable plane, at the fame time that 
 
 Thefe lives were written and publifhed as a fpecimen the preflure of the body caufes a horizontal motion iu 
 of the manner in which a Biographia Scotica might be the plane. 
 
 executed ; and it is likely that Lord Hailes felefted Though Darcy ferved in the war of 1744, he found 
 purpofely the leaft intereftlng. leifui e, during the buftle of a military life, to fend two 
 
 The Opinions of Sarah Dutchefs Dowager of Marl- memoirs to the academy : the firft of thefe contained 3 
 borough, publifhed from her original MSS. 1788, general principle in mechanics, that of the prefervation 
 l2mo, pp. 120. (with a few foot notes by Lord Hailes, of the rotatory motion ; a principle wjiich he again 
 in which he correfts the fplenetic partiality of her brought forward in 1750, by the name of the principle 
 Grace). of the prefervation of adion. He was taken prifoner 
 
 The Addrefs of Q^ Sept. TertuUian to Scapula Ter- in this war by the Engiifti ; and fuch was either the 
 tuUus, Proconful of Africa, tranflated by Sir David refpeft paid to fcience, or the mercy of the cabinet of 
 Dalrymple, i 2mo. Edin. I 790, infcribed to Dr John St James's, that he was treated, not as an Irifh rebel, 
 Butler, bifhop of Hereford ; preface, pp. 4 ; tranfla- but as a French fubjed fighting for his king and hiit 
 tion, pp. 18 ; original, pp. 13 ; notes and illuftrations, country, 
 pp. 1.^5- In 1760, Darcy- publifhed An Effay on Artillery, 
 
 This addrefs contains many particulars relating to containing fome curious experiments on the charges of 
 the church after the third century. The tranflator has gunpowder, &c. &c. and improvements on thofe of the 
 
 3 P 2 ingenious 
 
 (b) See his Credibility of the Go/pel Hlftory, and other works, in 11 vols 8vo» 
 
 (c) See his Evldencet of the Chri/lian Religion, ia 2 vols 8vo.
 
 DAT 
 
 Darcy, 
 
 Data. 
 
 ingenious Robins; a kind of expeilmcnts whicli ourau- 
 ttior carried on occalionally to the end of his life. In 
 1765, lie gave to the public the mofl ingenious of all 
 his works, his Memoir on the Duration of the Senfa- 
 tion of Sight ; in which he endeavours to prove, and 
 indeed complettly proves, that a body may fomttimts 
 pais by our eyes without producing a fenfatioii attend- 
 ed with confcioufnefs or marking its prefencc, other- 
 wife than by weakening the brightnefs of the ubjcA 
 which it may chance to cover in its paffage. If in 
 this work he lliall be thought to have taken hints from 
 I)r Hartley, it is not perhaps too much to fay, that 
 fome of our mod celebrated writers on viiion have fiiice 
 been beholden to Darcy. No man indeed has caufe to 
 be a(hamed of being indebted to him ; for eU his works 
 difplay in an eminent degree the union of genius and 
 phlloft'phy ; but as he nieafured every thing upon the 
 largeft fc;.!e, and lequired extreme accuracy in experi- 
 ment, neither his time, fortune, nor avocations, allow- 
 ed him to execute more than a very fmall part of what 
 he projefteJ. 
 
 In his difpofilion, Darcy was amiable, fpirited, live- 
 ly, and a lover of indejjendence ; a pafTion to which he 
 nobly facrificed, even in the niidft of literary fociety. — 
 He died of a cholera morbus in 1779, at 54 years of 
 age. He was admitted of the French academy in 1749, 
 and was made penConer-geometrician in 1770. His 
 ciTays, printed in the Memoirs of the Academy of Sci- 
 ences, are various and very ingenious, and are contained 
 in the volumes for the years 1742, 1747, J749> I750j 
 1751, 1752, I7J3' 17^4. '758' i7S9> '760. i765> and 
 iin torn. r. of the Savans Etraiigers. 
 
 DATA OF Euclid, the firft in order of the books 
 that have been written by the ancient geometricians, to 
 facilitate and promote the method of refolution or ana- 
 lyfis. In general, a thing is faid to be given which is 
 cither aftually exhibited or can be found out, that is, 
 which is either known by hypothefis, or that can be 
 demonflrnted to be known : and the propofitions in the 
 book of Euclid's data (hew what things can be found 
 out or known, from thoie that by hypothefis are already 
 known : fo that in the analyfis or inveftigation of a 
 problem, from the things that are laid down as given 
 ur known, by the help of thefe propofitions, it is de- 
 monilrated that other things are given, and from thefe 
 laft that others again are given, and fo on, till it is de- 
 monftrated that that which was propofed to be found 
 out in the problem is given; and when this is done, the 
 problem is folved, and its compofition is made and de- 
 rived from the conipofitions of the data which were em- 
 ployed in the analyfis. And thus the data of Euclid 
 are of the mofl general and neceffary ufe in the folution 
 of problems of every kind. 
 
 Marinus, at the end of his preface to the data, is 
 miilaken in afTerting that Euclid has not uled the fyn- 
 thetical, but the analytical method in delivering them : 
 for though in the analyfis of a theorem, the thing to 
 be demonftrated is affumed in the analyfis ; yet in the 
 demonftrations of the data, the thing to be demonftra- 
 ted, which is, that fomething is given, is never once af- 
 fumed in the dcmonftration ; from which it is manifeft, 
 that every one of them is demonftrated fynthitically : 
 though indeed if a propofition of the data be turned 
 into a problem, the demonltration of the propofition be- 
 
 [ 4«4 1 
 
 D E K 
 
 Siw/fon's Prejact to Dccimri, 
 
 comes I he analyfis of the problem. 
 his Etihion of the Diita. 
 
 Circulating DECIMALS, called alfo recurring 
 or nf eating decimals, are thai^e in whicli a figure or feve- 
 ral figures are continually repeated. Tliiy are diftin- 
 guidicd ihlo Jingle and n:uktph; and thefe again into^«r<; 
 and mixed. 
 
 A purs Jingle circulate 13 that in which one figure 
 only is repeated ; as "2 22, &c. and is marked thus '2. 
 A. pure multiple circulate is that in which feveral fi- 
 gures are continually repeated ; as'232323, &c. marked 
 •23 ; and •524524, &c. marked "524. 
 
 A mixed Jingle circulate is that which confifts of a 
 terminate part, and a fuigle repeating figure ; as 4'222, 
 &c. or 4'2. And 
 
 A mixed multiple circulate is that which contains a 
 terminate part with feveral repeating figures; as 4J'524. 
 That part of the circulate which repeats is called the 
 rcpelend ; and the whole rcpetend, fuppofed infinitely 
 continued, is equal to a vulgar fraftion, whole numera- 
 tor is the repeating number or figures, and its denomi- 
 nator the fame number of nines : fo .2 is = ^ ; anil -23 
 
 is = \i ; and -524- is = 4|4- 
 
 It feems it was Dr Wallis who firft diftinftly confi- 
 dered or treated of infinite circulating decimals, as he 
 himfelf informs us in his Treatife of infinites. Since 
 his time many other authors have treated on this part 
 of arithmetic ; the principal of thefe, however, to whom 
 the art is moftly indebted, are Meflrs Brown, Cunn, 
 Martin, Emerfon, Malcolm, Donn, and Henry Clarke ; 
 in whofe writings the nature and praSice of this art 
 may be fully feen, efpecially in the laft mentioned inge- 
 nious author. 
 
 DEFERENS, or Deferent, in the ancient aftro- 
 nomy, an imaginary circle, which, as it were, carries 
 about the body of a planet, and is the fame with the 
 eccentric ; being invented to account tor the eccentri- 
 city, perigee, and apogee of the planets. 
 
 DEFLECTION, the turning any thing afide from 
 its former courfe by fome adventitious or external caufe. 
 The word is often applied to the tendency of a fhip 
 from her true courfe by reafon of currents, &c. which 
 turn her out oF her right way. It is likewife applied- 
 by aftronomers to the tendency of the planets from the 
 line of their projcflion, or ihe tangent of their orbit.. 
 See Astros OMY in this Supplement. 
 
 DEJECTION, in aftrology, is applied to the planets 
 when in their detriment, as ailrologers fpeak, i. e. when 
 they have loft their force or influence, as is pretended, 
 by reafon of their being in oppofition to fome others 
 which check and counterafl them. Or it is ufed when 
 a planet is in a fign oppofite to that in which it has its 
 greateft effeft or influence, which is called its exaltation. 
 Thus, the fign Aries being the exaltation of the fun, 
 the oppofite fign Libra is its dejeftion. 
 
 DELIACALPaoBLEM.a celebrated problem among 
 the ancients, concerning the duplication of the cube. 
 
 DEMI-Bastion, in fortification, a baftion that has 
 only one face and one flank. 
 
 DENDROMETER, in its ufual acceptation, is the 
 name of an inilrument for meafuring trees, of which 
 the reader will find a defcription in the Encyclopaedia 
 Britantiica. The fame name has been lately given, by
 
 DEN 
 
 [ 485 1 
 
 DEN 
 
 Drndro. WiLLiAM PiTT, Efq; of Pen de ford near Wolvethamp- 
 °"^ '"- ton, to an inftrunicnt propoftd by him for nieafurin^ 
 ' diltances by one obfcrvation. 
 
 The idea of fuch an inllrunient is not new. It has 
 been freqncntly difcufftd, both in converlation and upon 
 paper; but has been generally treated by found mathe- 
 niaticians with contempt, on the fuppofition of its be- 
 ing founded on fnife principles. Of all this our author 
 is fully aware ; but he, notwithftanding, ftrongly re- 
 commends it to the attention of the ingenious niathe- 
 natical inllrument maker. ■ 
 
 To determine diftances by one obfervation, two me- 
 thods may be propofed, founded on different principles; 
 the one on the fuppofition of the obferver being in the 
 centre, and the objeft in the circumference, of a circle ; 
 the other, on the contrary fuppofition, of tlie obferver 
 being in the circumference, and the objeCl in the 
 centre. 
 
 To determine the diftance of any objeft on the firll 
 fuppofition, the bulk or dimenfions of fuch objeft muft 
 be known, either by meafure or eftimation, and the an- 
 gle formed by lines drawn to its extremities being ta- 
 ken by an accurate inllrument, the dillance is eafily cal- 
 culated ; and fuch calculations may be facilitated by 
 tables or theorems adapted to that purpofe. For this 
 method our prtfent inftruments, with a nonius, and the 
 ■whole very accurately divided, are fufficlent ; the only 
 improvement wanting feems to be the application of a 
 micrometer to fuch inftruments, to enable the obferver 
 to read his angle with more minute accuracy, by afcer- 
 taining, not only the degrees and parts of a degree, but 
 alfo the minutes and parts of a minute. 
 
 As in this method the bulk of inacceffible objefts 
 can only be eftimated, the error in diftance will be ex- 
 aftly in the proportion of the error in fuch eftimation ; 
 little dependence can therefore be placed on diftances 
 thus alcertained. For the purpofes of furveying, in- 
 deed, a ftafF of known length may be held by an affift- 
 ant ; and the angle from the eye of the obferver to its 
 two ends being nieafured by an accurate inilrumenr, 
 with a micrometer fitted to afcertafn minutes and parts 
 of a minute, diftances may be thus determined with 
 great accuracy ; the application of a micrometer to the 
 theodelite, if it could be depended upon, for thus dcter- 
 mining the minute parts of a degree, in fmall angles, is 
 very much a defideratum with the praftical furveyor. 
 
 This method of meafuving diftances, though plain 
 and fimple enough, our author illuftrates by an example ; 
 Suppofe A, fig. 1. (fee Plate XXI.) the place of the 
 irftrument ; BC the afliftant's ftaff, with a perpendicu- 
 lar pin at D, to enable the affitlant to hold it in its 
 right pofition ; now, if the angle BAG could, by the 
 help of a micrometer, be afcertained to parts of a mi- 
 nute, the diftance fii;ra A to B, or to C, might be eafi- 
 ly calculated by the rules of plane Trigonometry j 
 for which fee that article in the Encyclopedia. 
 
 But this method of afcertaining diifances cannot be 
 applied to inacceffible objcAs, and it is moreover fub- 
 jeft to the inconvenience of an afiiftant being obliged 
 to go to the objeft whofe diftance is required (an in- 
 convenience almoft equal to the trouble of aftual ad- 
 meafurement) ; therefore the perfedlion of the fecond 
 method propofed, if attainable, is principally to be de- 
 fired ; namely, that of conceiving the obfervation made 
 on the circumference of a circle, whofe centre is in the 
 
 objcA whofe dillance is to be afcertained ; and, none of Uendro. 
 our inftruments now in ufe being adapted to this mode ""='"■• 
 of obfervation, a new conftruftion of a mathematical in- 
 flrument is therefore propofed, the name intended for 
 which is the dendrometer. 
 
 Our author admits, that this name is not now iifed 
 for the firft time, though he thinks that the principle 
 has never been applied in praftice, for the familiar pur- 
 pofe of afcertaining tcrreftrial diftances, in furveying, 
 or otherwife, though the fame principle has been lo ge- 
 nerally and fuccetsfully applied in determining the dif- 
 tance of the heavenly bodies by means of their parallax. 
 The following principles of conftniAion are propo- 
 fed, which may perhaps be otherwife varied and impro- 
 ved. O, fig. 2. the objeft of whofe diftance is requi- 
 red ; ABCDE the inllrument in piano ; BC a tele- 
 fcope, placed exaflly parallel to the fide AE ; CE an 
 arcli of a circle, whofe centre is at A, accurately divi- 
 ded from E in degrees, &c. ; AD an index, moveable 
 on the centre A, with a nonius fcale at the end D, 
 graduated to apply to the diviiions of the arch ; alfo 
 with a telefcope, to enable the obferver to difcriminate 
 the objcft, or any particular part or fide thereof, the 
 more accurately. The whole ftiould be mounted on, 
 three legs, in the manner of a plain table or theodolite, 
 and furniflied with fpirit-tubes to adjuft it to an ho- 
 rizontal pofition. The inftrument being placed in fuch 
 pofition, the telefcope BC muft be brought upon the 
 objeft O, or rather upon fome particular point or fide 
 thereof; w>hen, being there faftened, the index AD 
 muft be moved till its telefcope exadlly ftrikes the fame 
 point of the objeft ; then the divifions on the arch ED 
 mark out the angle DAE, which will be exadlly equal 
 to the angle BOA, as is demonftrated in the XV. 
 and XXIX. propofitions of Euclid, Book I. ; and the 
 fide BA, as well as the angles ABO, and BAO, being, 
 already known, the diftance BO or AO may be eafily, 
 determined. 
 
 As the perfeftion of this inftrument depends altoge-- 
 ther upon its accuracy in taking fmall angles, fo that 
 accuracy mnft depend, not only upon the inftrument's 
 being properly fitted with a micrometer, but alfo in 
 fome meafure upon the length of the line BA in the 
 figure. That line, therefore, might be extended, by 
 the inftrument being conftruAed to fold or flide out to 
 a greater length when in ufe ; upon which principle, 
 connetled with the application of a micrometer, an ac- 
 curate and ufeful irjilrument might certainly be con- 
 ftrudled. To adjuft fuch inftr\in)ent for ufe, let a flaff 
 be held up at a diftance, in the manner of fir. i. exadt- 
 ly equal in leiiglh to the diftance of the two telefcopes, 
 and the index AD being brought exadlly upon the fide 
 AE, if the two telefcopes accurately fliike either end 
 of the ftaff, the inftrument is properly adjulted. 
 
 The conftrudlion of a iimilar inllrument, on the prin- 
 ciples of Hadley's quadrant, for naval obfervations,. 
 would alfu doubtlefs be an acceptable objedl in navi- 
 gation, by enabling the mariner to afcertain the dif- 
 tances of fhips, capes, and other objcdls, at a fingle ob- 
 fervation ; and that, perhaps, wilfi greater accuracy 
 than can he done by any method now in ufe. 
 
 For this purpofe, the following conftrudlion is pro» 
 pofed : ABCDE, fig. 3. the inllrument in piano ; O, 
 the objetl whofe diftance is required ; at A, at C, at 
 E, and at 3, are to be filed fpeculums, properly fra- 
 med:
 
 Denomina- 
 tor 
 
 II 
 Default. 
 
 D E S [ 
 
 med nnd fitted, that at 3 having only Its lower part 
 quickfilvered, the upper part being left tranfparent to 
 view the objcft ; tlie fpeculum at A being fixed oblique- 
 ly, fo that a line A I, drawn perpendicular to its fur- 
 face, may bifeft the angle BAC in equal parts ; that 
 at C being perpendicular to the line C 2 ; thofe at E 
 and 3 being perpendicular to the index E 3, and that 
 at E being furnifhed with a fight ; the arch DC to be 
 divided from D in the manner of Hadley's quadrant ; 
 the movement of the index to be meafured as before liy 
 a micrometer ; and as the length of the line AE would 
 tend to the perfeftion of the inilrument, it may be con- 
 ftrufted to fold -ap in the middle, on the line C 2, into 
 lefs compafs when not in ufe. The inflrument may 
 be adjuited for ufe by holding up a ftaff at a diftance, 
 as before propofed, whofe length is exaftly equal to the 
 line AE. 
 
 To jnake an obfervation by this inftrument, it being 
 previoufly properly adjufted, the eye is to be applied at 
 the fight in the fpeculum E, and the face turned to- 
 wards the objeA ; when the o"bjeft being received on 
 the fpeculum A, is refledted into that at C, and again 
 into that at E, and that at 3 on the index ; the index 
 being then moved till the reflefted objeiS in the fpecu- 
 lum at 3 exaflly coincides with the real objeft in the 
 tranfparent part of the glafs, the divifinns on the arch 
 D 3, fubdivided by the micrometer, v.'ill determine the 
 anii-le DE 3 = the angle AOE ; from which the dif- 
 tance O may he determined as before. 
 
 DENOMINATOR of a Ratio is the quotient 
 arifmg from the divifion of the antecedent by the con- 
 fequcnt. Thus, 6 is the denominator of the ratio 30 
 to 5, becaufe 30 divided by 1; gives 6. It is otherwife 
 called the exponent of the ratio. 
 
 DEPRESSION OF a Star, or of the Sun, is its 
 diftance below the horizon ; and is meafured by an arc 
 of a vertical circle, intercepted between the horizon and 
 the place of the ftar. 
 
 Dbfression of the V'lfible Horizon, or Dip of the Ho- 
 rizon, denotes its finking or dipping below the true 
 horizontal plane, by the obferver's eye being raifed 
 above the furface of the fca ; in confequence of which, 
 the obferved altitude of an odjett is by fo much too 
 groat. 
 
 DEROOriUST, in Bengal, Entire; as an entire 
 diftrift, oppofed to Kismut, which fee. 
 
 DESAULT (Peter Jofeph), furgeon in chief to 
 the Hofpital of Humanity, formerly the Hotel-Dieu at 
 Paris, was born on the 6th of February 1744 at Mag- 
 ny Vernois, a village in the neighbourhood of Lure, in 
 the department of Haute Saone (formerly the pro- 
 vince of Franche Comte). His father and mother were 
 in that fituation of life which is removed from want, 
 and yet does not difpenfe with labour ; he himfelf was 
 the youngeft child of a numerous family. 
 
 At Lure, under the diredion of a private inftruftor, 
 he was taught the firft rudiments of the Latin tongue ; 
 his parents afterwards confided him to the care of the 
 Jefuits, then almoft exclufively entrufted with the edu- 
 cation of youth in the public fchools. This celebrated 
 fociety, prompt in difcovering, as expert at developing, 
 and adroit in appropriating talents, foon diftinguilhed 
 the young ftudent from the crowd ; and he, in his turn, 
 was not difpleafed with the life he led in one of their 
 feminaries. 
 
 486 ] D E S 
 
 On the completion of his fludies, his father, who had rieftatt- 
 deftined him for the church, intimated a wifh that he ' » " ■« 
 fhould apply himfelf to theology ; but his genius had 
 taken a different diredlion, and he was avcrfc to the 
 profeffion of an ecclefiaftic : in (liort, young Default 
 declared that he was determined to betake himfelf to 
 the ftudy of the healing art ; and, after a long and in- 
 effeftual refiftance on the part of his family, he was fent 
 to Befort, in order to ferve an apprentice/hip, as it was 
 then termed, in the military liufpital of that place. He 
 accordingly fpent three years there ; during which he 
 acquired fome knowledge of anatomy, attended to the 
 drefling of the patients, and endeavoured to fupply, by 
 his own obfervations, what was wanting in his inilruc- 
 tion. 
 
 lu the midft of thefe profefllonal labours, his mind 
 frequently rambled towards another fcience but little 
 coniiefted w itli lurgery : this v.'a3 mathematics, the 
 elements of which he had acquired among the Jefuits. 
 His piogrefs in this favourite ihidy was rapid ; but he 
 fell into one of the many errors fo common among the 
 phyficians of that day ; this confiftcd in a falfe apphca- 
 tion of the rules of geometry to the laws of the animal 
 economy. 
 
 He not only perufed with avidity the treatife of Bo- 
 relli De Motu An'imalium, but aftually tranflated the 
 whole of it, and even added a commentary, ftill more 
 abundant in calculation than that of the celebrated pro- 
 felTor of Naples. 
 
 His fuccefs in a branch of phyfiologj- fo much culti- 
 vated at that time, attrafted the attention of one of his 
 fuperiors, a zealous partizan of tlie dodtrine of the me- 
 chanicians, who widied to attach him to his perfon ; but 
 his dcilre of fame required a more extenfive theatre, and 
 liis love of lludy made him folicltous of better means of 
 inftruclion. Paris prefented both thefc advantages; and 
 lie accordingly repaired thither in 1764, at the age of 
 nineteen, in fearch of them. 
 
 Surgery at that period flouriflied in the capital under 
 the aufpices of a Lafaye, a Morand, an Anduuillet, and 
 a Louis. The fight of fuch great mailers excited the 
 genius of thofe who afpired to emulate them : young 
 Default deemed himfelf worthy of equalling men whom 
 other ftudents were content with only admiring. Ani- 
 mated by this fentiment, he entirely refigned himfelf to 
 his ardour ; anatomy became the fpecial object of his 
 labours, and his diffeclions were not confined to the hu- 
 man body, for he inveftigated, by means of his knife, i. 
 prodigious number of animals of all kinds : at iirft, 
 from a difficulty of procuring human fubjetls, and af- 
 terwards on account of the advantages which he expe- 
 rienced from this general method. In order to become 
 intimately acquainted with our own organization, it is 
 neceffary to compare it with whatever has a refemblance 
 to it in other bodies. 
 
 He accordingly fpent the greater part of the day in 
 the amphitheatres. The hours ftolen from his favou- 
 rite labours were employed in attending the hofpitals ; 
 he was the firft at the bed of the patient where an ope- 
 ration was to be performed, and was fure to be prefent 
 at the dreflings, on purpofe to examine the refult. The 
 infirmities of mankind, fterile in refpeft to the vulgar, 
 ferved him as the beil treatife for curing them ; and 
 the great furgeons of all nations have formed their mode 
 of praftice by contemplating the fame book. 
 
 But
 
 D E S r 487 ] D E S 
 
 But hi reckoned too much on a roVitid and vigorous In 1779 he invented the bandage now in ufc for DefauU, 
 
 "'temperament ; for, after two ytars clofe and afiiduous frailures; by means of which, the fragments being kept '"""~V"~" 
 
 spph'cation, he fell into a cachetlical habit of body, in a flate of perpetual contact, become confohdated, 
 
 which had nearly proved mortal, and which colifiiied without the lealt appearance of deformity, an almoll in- 
 
 him for almoft twelve months to his bed ; but at length, evitable confequence of the former mode, 
 
 owing partly to the vigour of iiis youth, and partly to On his appointment to the place of furgeon major 
 
 the attention of his young friend Chopart, his infepar- to the hofpital i/c- la Charite, in 1782, he introduced a 
 
 able companion in his operations, who attended him al- new method of treatment in oblique fraftures of the 
 
 fo during his lad illuefr,, and only furvived him a few thigh-bone ; and he alfo healed, by means of a metho- 
 
 days, he was fo fortunate as to recover. dical compreflion, thofe various ulcers whofe cure had 
 
 Reftored to life, he forgot that an excefs of atten- hitherto been attended with great difficulty. In addi- 
 tion had condufted him to the very gates of death ; a tion to this, he fubftituted new bandages in fraftures of 
 new career opened to his view, and required new ef- the humerus and clavicle, and adopted a new mode of 
 forts on his part. In the winter of 1766 he commen- treating the hare-lip, fuperior to that ufed by Louis, 
 ced a courfe of anatomy, and foon reckoned tjco pupils. He never recurred to amputation but in extreme cafes, 
 moft of them older than himfelf, who were attrafted by when there was a certainty that diffolution would have 
 the clearnefs of his demoidlrations, the methodical ar- followed a negleft of the operation, 
 rangement of his defcriptions, and, above all, by his in- When a premature death carried off Ferrand, chief 
 defatigable zeal in the fcience of inllruttion. furgeon of the Hotel Dieu in Paris, Default was con. 
 
 His fuccefs infpired the privileged profefTors, whofe fidered as the moft proper perfon to fucceed him ; and, 
 fchools became deferted, with jealoufy and revenge ; on the demife of Moreau, the whole charge of the hof- 
 they employed the authority of the corporation againft pital devolved on him. After three years of folicita- 
 him, and would have nipped his efforts in the bud, had tions and difputcs, he at length in 1788 proceeded in 
 it not been for the proteftlon of Louis and Lamarti- his long projefled fcheme of eilablifliing a clinical fchool; 
 niere, who were zealous of protecting a youth of ta- and a fpacious amphitheatre was accordingly eredled for 
 lents, whofe fole reproach was, that he had not wealth that purpofe. Scarcely had his firlt (a) courfe corn- 
 enough to purchafe certain franchifes. After all, had menced, when the number of pupils who flocked around 
 it not been for the permiffion he obtained of borrowing him was really aftonifhing. Foreigners repaired from al! 
 the name of a celebrated phyfician, he muft have aftu- parts, and feveral of the neighbouring Itates fcnt ftu. 
 ally defiiled from his leftures. dents to Paris, exprcfsly for the purpofe of affifting at 
 
 Default's reputation now began to be buzzed about, his demonftrations. More than 600 auditors conftant- 
 
 and a multitude of patients claimed his affiftance ; but ly attended, in order to learn a new fyftem, confiding 
 
 he conftantly refufed to pradlife until he (hould be pla- of a fimple mode of treatment, difengaged from ancient 
 
 ced at the head of fome great eftablifhment. prejudices, and a complex incoherent practice. 
 
 At length, at the repeated folicitations of his friends, A few of his improvements are here fpeciiied. 
 
 he prefented himfelf as a candidate to the corporation i. The method of ligature employed by the ancients 
 
 of furgeons; and they, much to their honour, admitted in the cure of umbilical hernias of children, having been 
 
 him in 1776, on condition of paying the ufual fees generally omitted in the praftice of the moderns, he 
 
 ■when convenient. The following is the title of his the- again introduced and perfected this mode, and demoii- 
 
 (is : " De calculo veficis wiiw/'ue, eoqiie extrnl.vndo, ptie- ftrated, by his fuccefs, its luperiority over conipreflive 
 
 via fiilione, ope inflrumentt Haukenfani eiiiendaU." bandages. 
 
 His public lectures were accompanied with as much 2. He was one of the firrt; men in France to extraft 
 
 celebrity as his private ones. Brilliant difcoveries were the loofe cartilages ( cartilages Jlnttans ) In joints, 
 
 not the objeft of his anatomical labours, which were al- 3. He employed a new treatment, that of a methodi- 
 
 ways connefted with the art of healing : he was, how- cal comprefFion, in refpeft to fchirrofities of the rettum;. 
 
 ever, the firft man in France who taught furgical ana- in order to which he introduced a candle or bougie, 
 
 tomy. the fize of whice he gradually augmented. 
 
 After becoming firft a fimple member, and then a 4. He fimplified, and rendered more commodious, the 
 
 counfellor, of the perpetual committee of the academy redutflon of luxations of tlie humerus 
 
 of furgery, he was appointed chief furgeon to the hof- 1;. Fatal experience having pointed out the danger of 
 
 pital of the college, and confulting furgeon to that of employing the trepan in wounds of the head, he fubfti- 
 
 St Sulpice : neither of thefe added any thing to his tuted another method of treatment (I' itfage de V cine- 
 
 fortune, but they gave him a clear infight into practice, t'lque) now adopfcd by many praflltioners. 
 
 and enabled him to judge of cafes by the indudtions 6. He made feveral very ufeful improvements on chl- 
 
 arifing from his own experience. rurgical inllruments ; fuch as tliofe. employed in the 
 
 cafes 
 
 (a) The hufinefs of the day was condufted in the following routine ; i. A public confultation concerning, 
 
 the indigent out-patients. 2. The young praftitloners belonging to the hofpital read a detailed account of all 
 the interefting cafes of fuch patients as were to be difcharged that day. 3. The operations : each of thefe was 
 preceded by a differtation on the flate of the patient, who was then carried to the amphitheatre, where Default, 
 attended by his afliftants, performed the operation in prefence of all the pupils. 4. Argumentative details, by 
 the profefTor, either on the dangerous maladies exifting in the hofpital, or on the fituation of the patients on. 
 whom operations had been performed during the preceding day. 5. The diifeftion of fubjefts. And, 6. A 
 ■fcfture on fame particular branch of pathology.
 
 D E S 
 
 \ 488 ] 
 
 D E T 
 
 Def-uU. cafL'S of polypus in the womb and noftrils f/a p'mce a 
 gai'nc et des pcrte-tia-jds pour hi ligature da polypes, &c. ;) 
 for cutting through obftruftions in the different cavi- 
 ties (/f tlctome) ; and for theji/lula in arto. In cafes of 
 incifion he introduced the ufe oF the inllrument {le gor- 
 gerct) invented by Marciietti, well known among fo- 
 reigncrs, but almoil totally negledled in France before 
 this period. 
 
 He at the fame time retrenched the ufe of a great 
 number of fuperfluous ones, and banifhed all pradlices 
 attended with greater pain than utility. Avoiding eve- 
 ry thing that was complex, he proved that the art of 
 healing, in imitation of nature, ought to be fimple in 
 Its means, and fruitful in its refources. 
 
 In 1791 he publifhed his Journal de Chirurgerie, 
 ■which was edited by his pupils, and deftined to defcribe 
 the moll interefting occurrences in his fchool, and alfo 
 extraAs from his leAures, which were then dedicated 
 to the inveftigation of the maladies incident to the uri- 
 nary paffages. The treatment of thefe difeafes, hither- 
 to the reproach of practitioners, had been much impro- 
 ved by the affiftance of the artift Bernard. The elaftic 
 ■probes (les fandes elajliques), on their firft appearance, 
 fixed the attention of all profefTional men ; but none 
 knew better than Default how to appretiate their ad- 
 %aiitages By means of them, he introduced a novel 
 mode of cure in contraftions of the urethra, which faved 
 a great number of lives every year in the Hotel- Disu. 
 But he did not confine their ufe to the difeafes of the 
 urethra alone, for he employed them to remove the di- 
 vers obftacles that impede deglutition or refpiration. 
 
 In the midft of fuch a multiplicity of labours, and 
 although he was obliged to attend 400 fick twice a- 
 day, Default neverthelefs employed more than four hours 
 of his time in vifiting private patients. 
 
 Few furgeons ever enjoyed fuch an exclufive fhare of 
 public confidence ; few ever pofTefTed fimilar means of 
 enriching themfelves ; and yet he neglefled for a long 
 time to take advantage of this. Had he been lefs ar- 
 dent for glory, he would have been more favoured by 
 fortune ; but he facrificed all interefled views to the 
 noble ambition of advancing his art. His clinical and 
 anatomical courfes were gratuitoufly opened by him to 
 the world after the year 1790; and while the public 
 fchools languifhed in the midfl of troubles, infeparable 
 perhaps from a miglrty revolution, he was forming the 
 greater part of thofe furgeons employed at this prefent 
 moment in the numerous armies of the republic. Con- 
 iidered under this point of view alone, the fervices 
 which he rendered to humanity are incalculable : too 
 happy if perfecution had not been his fole reward ! 
 
 While out of mere attachment to the public weal, he 
 added to his various funftions that of a member of the 
 council of health, conferred on him in 1792 by the 
 minifter Servan, lie was denounced in the popular focie- 
 tics as an egotijl., an indifferent, &c. and became one of 
 the firil viftims of that profcription which, under Robe- 
 fpierre, extended to nearly every man of talents. 
 
 Chaumctte accufed him to the feftions as having ne 
 glefted the brave men wounded on the loth of .\uguft, 
 while they themfelves were lavifhing their blefllngs at 
 the Hotel Dieu on their faviour. Twice was he brought 
 to the bar of a commune ; defirous of difcovering a pre- 
 text for perfecution, the clamours of the, people were 
 
 unremittingly excited againft him. He was at length Hefault, 
 carried away from his amphitheatre, while in the very Ut^ttrnii 
 aA of haranguing his pupils ; and, in confequtnce of a , ^" 
 
 mandft d'arr t from the revolutionary committee, con- 
 dufted by a body of armed men to the Luxembourg. 
 From this horrid prifon few ever departed but to meet 
 their fate ; luckily, however, his name was not yet en- 
 tered on that bloody lift, iu which thofe of Makfherbes 
 and LavoiJier were inferted. On the contrary, at the 
 end of three days he was liberated, and inilaatly retu- 
 rned all his funftions. 
 
 On the eftablifhraent of L'Ecolede Sante, Default 
 was appointed clinical profeflbr ; and for external mala- 
 dies he foon after obtained from the government the 
 convertion of the Eveche into an hufpital for furgical 
 operations. 
 
 In the midft of thefe plans, the troubles that occur, 
 red in the munth of May unfortunately affefted his 
 mind, and made him dread left the days of profcription 
 (liould return. It was in vain that his friends attempted 
 to foothe his fufferings ; for on the night of the 29th. 
 of May, a malignant fever made its appearance, and a 
 nearly continual delirium enfued until his death, which 
 occurred on the ift of June 1795. on which day he 
 breathed his laft, in the arms of his pupils, at the age 
 of 51. 
 
 The populace were perfuaded that he was poifoned. 
 This ridiculous opiiuon originated in confequence of the 
 epoch of his death, which preceded but a fhort time that 
 of the fon of Louis XVI. whom he had vitlted during 
 his ilinefs in the prifon of the Temple. It is pretended 
 that he fell a vidlim to his conflant refufal to yield to the 
 criminal views entertained againft the life of that child. 
 Default was of a middling ftature. He was well pro- 
 portioned, and pofTcffed an open countenance. His 
 temperament, naturally robuft, had been fortified by his 
 early education, and was never tapped by an excels of 
 pleafures, for to them his heart was always indifferent. 
 His ruling paflion was the love of glory ; his favourite 
 purfuit, the praflice and advancement of his art. He 
 was warm, nay fometimes violent; and his fcholars were 
 not always inclined to praife the fweetnefs of his tem- 
 per. On the other hand, his mind was noble, elevated, 
 and great, even to excefs. 
 
 The French republic, eager to pay homage to his 
 memory, has prefented his widow with a penfion of 2,000 
 livres^fr annum. A fon, Alexis Mathias Default, was 
 the fole fruit of his marriage ; and he has left but one 
 work behind him, in which the name of his friend Cho- 
 part is joined with his own. It Is entitled Traile dei 
 Maladies Chirurgicales et des Operations qui leur convien- 
 nent, 2 vols '^vo. 
 
 DETERMINATE problem, is that which has 
 but one folutlon, or a certain limited number of folu- 
 tions ; in contradiftinftion to an indeterminate problem, 
 which admits of infinite lolutions. 
 
 D-TfRMiN^TB SeSion, the name of a traft or general 
 problem, written by the ancient geometrician ApoUo- 
 nius. None of this work has come down to us, ex- 
 cepting fome extrafts and an account of it by Pappus, 
 in the Preface to the 7th book of his Mathematical 
 Colleftions. He there fays that the general problem 
 was. " To cut an infinite right line in one point fo, 
 that, of the fegments contained between the point of 
 
 fedion
 
 D E T 
 
 (eftion fouglit, and given points in tht faid line, 
 the I'quare on one 
 
 3 R . , , 
 
 of thern, ov the rectangle contained 
 
 by two of them, may liave a given ratio, cither to the 
 rcftangle contained by one of them and a given line, or 
 to the rciftangle contained by two of them." 
 
 DETONATION (fee that word Enrycl.). The 
 aftonilliing violence with which the oxy-niiiriat of pot- 
 afs, when mixed with various fubllances, detonates, has 
 been already noticed in this Supplement under the ar- 
 ticle Chemistry, n" 112, where the theory of th':fe 
 explofions is likewife given. But as fcveral chemills 
 teem to think that this fait, which decrepitates by fric- 
 tion, and fpontaneoufly takes fire when mixed with ful- 
 phur, contains in itfclf the elements and phenomena of 
 thunder, it will not probably be unacceptable to our 
 readers to find, in this place, a diftinc^ account ot the 
 various mixtures which produce its detonations. The 
 following are the principal which have been difcovercd 
 by Fourcroy and Vauquelin. 
 
 1. Three parts of the oxy-muriat of potafs, and one 
 part of powdered fulphur, rubbed together in a metal 
 mortar, produce numerous fucceffive explolions, refem- 
 bling the fmacking of a whip, or even as loud as the re- 
 port of a piftol or a tTiufl<et, according to the rapidity 
 of the motion, and the force of the predure made ufe 
 of. A few grains of the fame mixture, by being flruck 
 fmartly upon an anvil with a hammer, occaiion a report 
 equal to that of a muflcet ; and torrents of purplifh 
 light are feen about the anvil. If this mixture be 
 thrown into concentrated fulphuric acid, it inllantly 
 takes fire, and burns, without nolle, with a flame of a 
 dazzling whitenefs. 
 
 2. A mixture of three parts of this fait, half a part 
 of fulphnr, and half a part of ctrarcoal, caufes llronger 
 explofions than the preceding when rubbed in a mor- 
 tar, and a louder noiie when llruck upon an anvil. Its 
 flame alfo, when the mixture is made to explode, or 
 w hen it is thrown into fulphuric acid, is more rapid, 
 more lively, and of a redder colour, than that of the 
 preceding. 
 
 3. A mixture of equal parts of oxy-muriat of potafs 
 and antimony in powder explodes with noife by per- 
 cuflion ; but produces only reddi(]i fparks when thrown 
 into fulphuric acid. If zinc be fubftituted in the place 
 of antimony, a fimilar explofion takes place, accompa- 
 nied with a white flame. Sulphuric acid has no effeft 
 upon this lad mixture. 
 
 4. With regulus of arfenic, this fait explodes very 
 violently by the Ihoke of a hammer ; it inflames, with 
 fingular rapidity and brilliancy, by the contaft of ful- 
 phuric acid. In this lall experiment there arifes a fmoke, 
 which in the air takes the form of a crown, in the fame 
 manner as phofphorated hydrogenous gas does when it 
 inflames fpontaneoufly in a ilill atniofphere. 
 
 5. Sulphurct of iron or martial pyrites inflames rapid- 
 ly, but without noife, when rubbed in a metal mortar 
 with oxy-muriat of potafs. This mixture, when ftruck 
 upon an anvil, explodes violently, and with a red flame. 
 
 6. The red fulphuret of mercury or cinnabar, and 
 the fulphurated calces of antimony, explode with the 
 oxy-muriat of potafs by percuffion, but they do not in- 
 flame by fulphuric acid. The fame thing happens when 
 charcoal alone is mixed with this fait. 
 
 Any of the following fubfl:ances, namely, fugar, gums, 
 SuppL. Vol. I. Part 11. 
 
 [ 489 ] n I A 
 
 -Mther oils (both fixed »nd volatile), alcohol, ether, when mix- 
 ed with oxy-muriat of potafs, have the property of ex- 
 ploding very violently by the llrokc of a hammer, and 
 all ot them fend forth a briflc flame at the time of their 
 explofion. The liquid combullible fubftances above 
 mentioned are to be mixed with the fait in fuch a man- 
 ner as to form a kind of parte. None of tliefc mixtures 
 explode or inflame by being rubbed in a mortar ; but 
 fome of them inflame by being mixed with concentra- 
 ted fulphuric acid, their combuition being flow and pro- 
 greflivc. 
 
 8. All the fubftances above mentioned, which, being 
 mixed with the oxy-muriat of potafs, take fire and burn 
 inftantly, and with confiderable noife, by the quick pref- 
 fure of the fl:iokcs of a hammer, produce a much llrong- 
 er explofion when they are fo clofely wrapped up in pa- 
 per, two or three times doubled, as to be thereby com- 
 prcffed before they are ftiuck. 
 
 9. An eledtric fliock from a battery of large furface, 
 charged by a Ilrong cleftric machine, caufes all the fore- 
 mentioned mixtures to explode in the fame manner as 
 percuflion, and their explofion is alfo accompanied by a 
 bright light. 
 
 To the above mentioned fafts, the authors add, that 
 it was already well known that gunpowder would ex- 
 plode by a violent blow, or very ftrong prefTure ; but 
 they obferve, that the ft.roke which is necefiary for that 
 purpofe muft be much ftronger than that whf.h fufficcs 
 to produce an explofion in the above-mentioned mix- 
 tures of combuftible fubllances vvith the oxy murlat 
 of potafs ; and that its explofion is by no means fo re- 
 markatje as that which is produced by the help of this 
 new fait. 
 
 DEWAN, under the Mogul government, the recei- 
 ver general and civic governor of a province : in private 
 life a ileward. 
 
 DEWANNY, the revenue department of a pro- 
 vince. 
 
 DIABETES Mellitus (fee Medicine, n» 318, 
 &c. Encycl.), is fo formidable a difeafe, though not 
 very frequent, that it would be unpardonable in us not 
 to mention every method of treating it fuccefsfully 
 which has come to our knowledge. Since our article 
 Medicine was publiflicd, Dr Rollo, furgeon general to 
 the royal artillery, has fiiggefted a method of treating 
 this difeafe, which in various inftances has been crowned 
 with fuccefs. 
 
 The Dodor fuppofes, that in this complaint the ve- 
 getable matter taken into the ftomach has not, from 
 fome defedl in this organ, undergone a fufficient change 
 to form proper chyle ; that in confequence of this, much 
 faccharine matter is evolved, which, when carried into 
 the circulation, proves a general ftlmulus, producing 
 head-aches and quicknefs of pulfe, but that it afts more 
 remarkably on the kidneys, occafioning a conllant and 
 copious fecretion of fweet urine. From this hypotbe- 
 fis, he was naturally led to adopt a plan of cure, which 
 has proved completely fuccefsful. The indications he 
 lays down are : i. To prevent the formation of faccha- 
 rine matter in the ftoinach ; and, 2. To remove the 
 morbidly increafed aftion of this organ, and reftore it 
 to a healthful condition. Thefe indications are to be 
 anfwered by a complete diet of animal food, and by the 
 ufe of fuch medicines as fhall diminifli the iGtion of the 
 3 Q^ ftomach, 
 
 Detnnju 
 
 tiOQ 
 
 . II 
 Diabetes.
 
 D I D 
 
 DiamonJ, ftomach, and at the fame time counterad^ the forma 
 . ■'-''"^ ''"^ tion ot faccharine matter. 'J'hc remedies employed for 
 this purpofe have been emetics, kali fulphuratum, lime- 
 water, hepatized ammonia, and vegetable narcotics. 
 But the principal dependence is to be placed on a total 
 abitinence from all vegetable matttr, which alone can 
 fupply the faccharine principle. By a regular perfeve- 
 raiice in this plan, the firR of two patients was com- 
 pletely cured in four weeks, although the difeafe had 
 been of feven months continuance. The urine, which 
 at the commencement of the treatment was fu'cct, and 
 amounted to 24 pints daily, was at lad reduced to 1^ 
 pint, being at the fame time free from any faccharine 
 impregnation. The fecond patient, from his age and 
 other circumftances, although relieved from the diabe- 
 tic affcflion, did not regain his wonted ftate of health ; 
 but even in this cafe, the etfcfts produced by the treat- 
 ment, when properly attended to, were moil decidedly 
 in confirmation of this plan of cure. 
 
 The Doftor has received feveral comrr -inicalions in 
 confequence of the difperfion of the printed notes on 
 the fiift cafe. The moft important are the refult of 
 two cafes treated in this way by Dr Cieghorn of Glaf- 
 gow, and one by Drs Currie and Gerard at Liverpool ; 
 all of which afford the ftrongefl corroboration of the 
 »:fficacy of this mode of treatment. 
 
 DIAMOND, the moft precious of all the gems; for 
 the nature of which fee Chlmistry, n«33, &c. in this 
 Supplement. 
 
 DIDEROT (-Dionyfius) of the academy of Berlin, 
 the fon of a cutler, was born at Langres in 17x3. The 
 Jefuits, with whom he vv-ent through a courfe of ftudy, 
 were defirous of having him in their order ; and one of 
 his uncles, defigning him for a canonry which he had 
 in his gift, prevailed upon him to take the tonfure. 
 
 His father feems to have known him better ; for per- 
 ceiving that he was not inclined to be a Jefuit, nor fit 
 to be a canon, he fent him to Paris to profecute the 
 ftudy of the law. To the law, however, he paid very 
 little attention, but devoted his time to fcience and ge- 
 neral literature ; which fo offended bis father, that he 
 flopped the remittance of his pecuniary allowance, and 
 feemed for fome time to have abandoned him. 
 
 The talents of young Diderot fupplied him with a 
 maintenance, and drew him from obfcurity. Accord- 
 ing to his friends, his capacious mind embraced phy- 
 fics, geometry, nietaphyfics, ethics, and the belles lettres, 
 from the time that he began to read with refleftion ; 
 and It is certain that he afpired at being a mafler in all 
 thefe departments of literature. His bold and elevated 
 imagination feemed to give him likewife a turn for poe- 
 try ; but he neglefted it for the fciences. He fettled 
 at an early period at Paris, where the natural eloquence 
 which animated his converfation procured him friends 
 and patrons. What firft drew the attention of the pu- 
 blic to him as an author, and gave him a high reputa- 
 tion among a certain clafs of readers, was a fmall vo- 
 lume written againft.the Chriftian religion, and intltkd 
 Penfees Fhilojophiques ; which was I'eprinted afteiwards 
 under the title of Eirennes aux EJprits -forts. 
 
 This book appeared in 1746, 1 2mo. The adepts 
 of the new philofophy compared it, for perfpicuity, ele- 
 gance, and force of diftion, to the Pinfies de Pajcal. 
 But the aim of the two authors was widely different ; 
 Pafcal employed his talents and his erudition, which 
 
 490 ] DID 
 
 was profound and various, to fupport and illuftrate the 
 great truths of our holy religion, which Diderot at-' 
 tacked by all the difuigeniious arts of an unprincipled 
 fophilt. The Ptnf es Pbilvfoph'tques, however, became 
 popular. It contributed to promote the objeft of that 
 coni'piracy which had been for fome time formed againll 
 every thing which ennobles human nature (See Jaco- 
 bins in this Supplement^. It was .therefore applauded 
 by Voltaiie and D'Alembert, and read, of courfe, by 
 every man and woman of tafte in Paris. 
 
 Our author was more ufefully employed in 1746, 
 when, together with Meffrs Eidous and Touijfant,- he 
 publKhed a general DIftionary of Medicine, in fix vo- 
 lumes folio. This work. It muft be confcffcd, has con- 
 fiderable merit ; for though there are in it feveral ar- 
 ticles fuperficial and erroneous, there are many others 
 of fuch deep and accurate difquifition, as defcrvedly re- 
 commended it to men of fclence. 
 
 It was about this time that an Intimacy was formed 
 between Diderot and D'Alembert, and that, under the 
 direftion of Voltaire, they formed the idea of a Dldio- 
 naire Encyclopedique. The great objefts which they 
 had in view when they entered upon this woik are now 
 univerfally known. D'Alembert was a profound ma- 
 thematician, Diderot had confiderable knowledge in the 
 phyfical fciences, more efpecially mechanical phllofo. 
 phy, and Voltaire was a mafter of the belles lettres. 
 
 It is not to be fuppofed that fuch men would pub- 
 ]ifh any thing very defeftlve In thefe departments of 
 fcience ; but an Enryclopsdia muft. treat of religion ; and 
 to every kind of religion they were all Iworn enemies. 
 They engaged, however, a very worthy, though not 
 very acute, clergyman, to furnifh the theological ar- 
 ticles ; and for other branches of knowledge, they were 
 promifed the afhftance of feveral men of letters, and of 
 a variety ot artlfts. 
 
 Diderot took upon himfelf the defcrlption of arts and 
 trades ; one of the moft important departments of the 
 work, and the moft acceptable to the public. To the 
 particulars of the feveral proceflts of the workmen he 
 fometimes added refleftions, fpcculations, and principles, 
 adapted to the elucidation. But bcfides his own de- 
 partment, he furniihed articles ou almoft every other 
 fubjeft. 
 
 By thofe who knew not the great aim of the under- 
 takers of this work, it has been regretted that Diderot 
 was not lefs verbofe, lefs of the differtator, and lefs In- 
 clined to digreflions. He has alio been cenfured for 
 employing needlefsly a fclentific language, and for ha- 
 ving recourfe to metaphyfical doftrines, frequently un- 
 intelligible, which occafioned him to be called the Lyco- 
 phron of philofophy ; for having introduced a number of 
 definitions incapable of enlightening the Ignorant, and 
 which the philofopher feems to have Invented for nd 
 other purpofe than to have it thought that he had great 
 conceptions ; while. In fadf , he had not the art of ex- 
 preffmg perfpicuoufly and fimply the ideas of others. 
 But thefe complaints arife from raiftaking entirely the 
 purpofe for which he wrote. 
 
 It has been completely proved, that one great ob- 
 jeft for which the phllofophers, as they called them- 
 felves, undertook the compilation of the Encyclopedic 
 was to fap the foundation of all religion. This was ta 
 be attempted, not diredlly and avowedly; for bare-faced 
 atheifm would not then have been fuffered in France-
 
 D I D 
 
 A cloak, therefore, was to be worn, and the poifoned 
 ' dagj^er ti> be concealed under it. Whilit tiie will. mean- 
 ing divine was fupporting, by the bed arguments which 
 he could devife, the religion of his country, Diderot 
 and D'Alenibert were overturning thofe ari^uments un- 
 der titles which properly allowed of no fueh dif(]uiri- 
 tions. This neceiVarily produced digrefiions ; for the 
 greateft genius on earth could not, when writing on the 
 laws of motion, attack the myfteries of Chriilianity 
 without wandering from his fubjcft ; but that the ob- 
 jeft of thefe digrefTions might not pafs unnoticed by 
 any clafs of readers, care was taken to refer to them 
 from the articles where the queftion was difcuffed by 
 the divine. That when employed in this way, DIdenjt 
 feems to write obfcurely, is indeed true ; but the ob- 
 fcurity is not his. Hi« atheifm was fo plain, that for 
 the moft part D'Alembert, or fome other leader of the 
 gang, had to retouch his articles, and throw a mift over 
 them, to render their intejition the lefs obvious. 
 
 Even with all this care and ftudied obfcurity, the de- 
 fign of the Encyclopedic was too palpable not to be feen, 
 and too wicked not to give offence. Certain wild po- 
 fitions on government and on religion occafioned the 
 imprcflion to be fufpended In 1752. At that time 
 there were no more than two volumes of the dictionary 
 publiflied ; and the prohibition of the lucceeding ones 
 was only taken off at the end of 1753. Five new vo- 
 lumes then fuccelfively appeared. But in 1757 a new 
 dorm arofe, and the book was fupprelTed. The re- 
 mainder did not appear till about ten years after ; and 
 was then for a while only privately dillributed ; fome 
 copies having been feized by government, and the prin- 
 ters fhul up in the Baftile The merit, however, of 
 fome of the articles is confefledly great; and the firft 
 edition was quickly fold off 
 
 Thus was this great work in the prefs from 1751 to 
 1767 ; during which period, Diderot and D'Alembert 
 were accuftomed to frequent the coffeehoufes of Paris, 
 and to enter with keennefs into religious difputes : the 
 former attacking Chriftianity ; and the latter, under the 
 mafic of piety, defending it ; but always yielding to the 
 arguments of his opponent. This praftice was put a 
 rtop to by the police ; and Diderot, when reproached 
 by the lieutenant with preaching atheifm, replied, " Ce- 
 la eft vrai, je fuis athee, & m'en fais gloire." 
 
 Finding his impiuus converfations interrupted, and 
 the publication of the Encyclopedic rendered tedious by 
 the vigilance of government, he thought of propaga- 
 ting his notions by other vehicles. Alternately ferious 
 and fportive, folid and frivolous, he publiflied, at the 
 very time he was working on the Dictionary of Scien- 
 ces, feveral produftions, which could fcarcely have been 
 expedled from a man fo completely employed. His 
 Bijoux Indifcrets, 2 vols izmo, are of this number — a 
 dilgufting work, even to thofe young people who are 
 unhappily too eager for following after licentious ro- 
 mances. Even here a certain pliilofophical pedantry 
 appears in the very pafTages where it is moil mifplaced, 
 and never is the author more aukward than where he 
 intends to diiplay a graceful eafe. 
 
 The Fils Naturel, and the Pere de Famille, two come- 
 dies in profe, which appeared in 17,-7 and 1758, are not 
 of the fame kind with the Bijoux ludifcrels. They are 
 moral and affe£ling dramas, where we fee at once a ner- 
 Tous ftyle and pathetic fentiments. The former piece 
 
 r 491 1 
 
 D I D 
 
 is a piclure of the trials of virtue, a confliifV betwten in- I'i'lf'ef. 
 tereds and pafTions, wherein love and friendfliip play *— ^/— ~ 
 important parts. It has been faid that Diderot bor- 
 rowed it from Goldoni : but if that be the cafe, th; 
 copy does honour to the original ; and, with the ex- 
 ception of a fuiall number of fcenes, where the author 
 mixes hia philofophical jargon with the fentiments of 
 the heart, and fome fentcnces out of place, the flyle is 
 afrefting and natural enough. In the fecond comedy, 
 a tender, virtuous, and humane father appears, whofe 
 tranquillity is dillurbed by the parental folicitudes, iu- 
 fpired by the lively and impetuous pafTiojis of his chil- 
 dren. This philofophical, moral, and almoft tragical 
 comedy, has produced confiderablc effctls im feveral 
 theatres of Europe. The dedication, to the princcfs 
 of NaiTau Saarbuck, is a little moral traft of a lingular 
 turn, without deviating from nature. This piece, writ- 
 ten with a true dignity of ftyle, proves that the auth.ir 
 pofTefTed a great fund of inoral fentinients and philofo- 
 phical ideas. At the end of thefe two pieces, publilli- 
 ed together under tlie title of Theatre de M. Dideiui, 
 are dialogues, containing profound refledlions and novel 
 views of the dramatic art. In his plays he has endea- 
 voured to unite the charaders of Ariftophanes and Pla- 
 to ; and in his refledions he fometimes difplayj the ge-' 
 nius of Ariftotle. 
 
 This fpirit of criticifm is exhibited, but with too 
 much licence, in two other works, which made a great 
 noife. The former appeared in 1749, izmo, intitled 
 Letters on the Blind for the Ufe of thofe who See. Tiii 
 free notions of the author in this work coft him his li- 
 berty. He underwent a fix months imprilonment at 
 Viorcennes. Having naturally ftrong palTions and a 
 hauglity fpirit, and hnding himfelf on a fudden depri- 
 ved <jf liberty and of all interconrfe with human beings, 
 he was threatened with the lofs of his reafon. The 
 danger was great ; and to prevent it, they were obli- 
 ged to allow him to leave his room, to take frequent 
 walks, and to receive the vifits of a few literary men ; 
 among whom J. J. RoufTeau, at that time his friend, 
 went and adminiftered confolation to hira, which he 
 ought not to have forgotten. 
 
 The letter on the Blind was followed by another 
 On the Deaf and Dumb, for the Ufe of thofe who can 
 Hear and Speah ; 1751 ; 2 vols, i 2mo. Under this 
 title the author dchvered reflections on metaphyfics, on 
 poetry, on eloquence, on mutic, &c. In this efl'^y there 
 are fome good things, among others abiurd znC im- 
 perfeft. Though he ftrives to be perfpieuous, yet he 
 is not always underftood ; and thi:; is more his fault 
 than that of his readers. Of what he has compclcd' 
 on abftraft fubjefts, it has been iaid that it is a chaos 
 on which the light fliines only at intervals The other 
 produftions of Diderot betray the fame defeft of clear- 
 nefs and precifion, and the fame uncouth emphafis, for 
 which he has always been blamed. 
 
 The principal of them are, ) . Principles of Moral 
 Philofophy, J 745, i2mo; of which the Abbe de Fon- 
 taine Ipeaks well, though it met with lu great fnceefs. 
 It was our philofopher's fate to write a great cie d, and 
 not to leave a good book, or at leaft a book we'', -om- 
 pofed. 2. Hiftory of Greece, tranflated from the Ei g- 
 llila of Stanyan. 3 vols, l2mo; an inditicrent trjinfla- 
 tion of an indifferent book 3. Pieces on feveral Ma- 
 thematical Subjefts, 1748. 8vo. 4. Reflections on the 
 3 Qj2 !nt!.T-
 
 DID i: 49 
 
 Diilerot. Interpretation of Nature, 1754, 12mo. This intcr- 
 '' ' preter is very obfcure. ^. Tlit Code of Nnture, 1755, 
 I2mo ; which is certainly not the code of Chrillianity. 
 6. The Sixth Senfe, 1752, irmo. 7. Of PuUic E- 
 ducation ; one of that fwarni ot [nilihcations produced 
 by the appearance of Einclius, and the abohtion of the 
 Jefuits. Thongh all the ideas of this author could not 
 be adopted, yet fome of them are very judicious, and 
 would be highly nfcful in the execution. 8. Panegyric 
 on Richardfon. Full of nerve an<l animation. 9. Life 
 of Seneca. This is the lad woik wliich he acknow- 
 ledged ; and it is one of tliofe by Diderot tliat is peru- 
 fed with mod pleafure, even in reftifying the judgments 
 he paffes on Seneca and other celebrated men. The 
 Abbe Barruel fays, that he was the author of S)Jlenie de 
 ia Nature, which is ufually given to Robir.et ; and it is 
 certain, that if he was not the author, he furnifhed 
 hints, and revifed the whole. Yet the junto of atheilts 
 were themfelves afhamed of the firft edition of that 
 work ; and after all Diderot's care to improve it, the 
 fubfequent editions are, notwithftanding his boaftcd 
 knowledge of the laws of nature, contemptible in the 
 eyes of a real mechanical philofopher. 
 
 When a new edition of the Eiuycloped'ie was refolved 
 on, Diderot, the editor of the former edition, thus ad- 
 drelTes the bookfellers who had undertaken to republifh 
 it. " The imperfeftions (fays he) of this work origi- 
 nated in a great variety of caufes. We had not time 
 to be very fcrupulous in the choice of our coadjutors. 
 Among fome excellent perfons, there were others weak, 
 indifferent, and altogether bad. Hence that motley ap- 
 pearance of the work, where we fee the rude attempt of 
 the fchoolboy by the fide of a piece from the hand of 
 a mafter ; a piece of nonfenfe next neighbour to a fu- 
 blime performance. Some working for no pay, foon 
 loft their firft fervour ; others, badly recompenfed, fer- 
 ved us accordingly. The Encyclopedie was a gulf into 
 which all kinds of fcribhlers promifcuoudy threw their 
 contributions ; their pieces ill conceived, and worfe di- 
 gefted, good, bad, contemptible, true, falfe, uncertain, 
 and always incoherent and unequal ; the reference that 
 belonged to the very parts afligned to a perfon, never 
 filled up by him. A refutation is often found where 
 we fhould naturally expefl a proof. There was no ex- 
 aft correfpondence between the text and the plates. 
 To remedy this defeat, recourfe was had to long expli- 
 cations- But how many uninteUigible machines, for 
 want of letters to denote the plates !" To this con- 
 feffion Diderot added particular details on various parts; 
 fuch as proved that there were in the Encyclopedie fub- 
 jefts to be not only retouched, but to be compofed a- 
 ■frefli : and this was what a new company of literati and 
 artifts fet themfelves to work upon in the Encyclopedie 
 MetLodique. 
 
 This immenfe work is not yet completed ; and there- 
 fore we cannot fpeak of it as a whole ; but it is furely 
 not lefs verbofe than the former edition, nor do the 
 aims of its editors appear to be purer. That it contains 
 much valuable information in chemiltry, and indeed in 
 every department of phyfical fcience, no candid roan 
 -will controvert : but its articles on abftraft philofophy 
 are prolix and obfcure ; and it betrays the fame impie- 
 ty, the fame eager defirc to corrupt the principles of 
 the rifmg generation, and the fame contempt for every 
 
 2 ] DID 
 
 thing which can make mankind happy here or hevcaf- nii'ero!. 
 ter, with the former edition. •~~' 
 
 Not\\itbUanding his numerous publications, Diderot 
 was never rich. Soon after the pul)lication of the lall 
 viilumcs of the Encyclopedic, upon which he had been 
 employed for upwards ot twenty years, his circumflan- 
 ces were fo ftraitened, that an expedient was to be de- 
 vifed for their improvement. He had long correfpon- 
 ded with the late Emprefs of Ruflia, whom he perfua- 
 dcd to confiJer him as the greateft, or one of the great- 
 ell economifts of France. In the courfe of the corre- 
 fpondence he had mentioned his own library as one of 
 the moil valuable in Europe; and when Catharine want- 
 ed to purchafe it ajid make him librarian, lie faid that 
 his coullitution could not fupport the cold climate of 
 St Peterlburgh. She offered to let him keep it during 
 his lifetime in Paris ; and the library was fold for an 
 immenfe price. W^hen her ambaflador wanted to fee it, 
 after a year or two's payments, and the vifitation could 
 be no longer put off, Diderot was obliged to run in a 
 hurry through all the bookfellers (hops in Germany to 
 fill his empty flielves with old volumes. He had the 
 good fortune to fave appearances ; but the trick took 
 air, becaufe he had been niggardly in his attention to 
 the ambaffador's fecretary. This, however, did not 
 hinder him from vifiting his imperial pupil, to whom he 
 told a poor ftory, in hopes of getting his daughter mar- 
 ried with parade, and patronifed by her majefty ; but 
 it was feen through, and he was difappointed. 
 
 In the year 1784 Diderot's health began vifihly to 
 decline ; and one of his domeftics, perceiving that his 
 death was at no great diflance, acq,uainted him with his 
 apprehenfions, and addreded him on the importance of 
 preparing for another world. He heard the man with 
 attention, thanked him kindly, acknowledged that bis 
 lituation required ferioufnefs, and promifed to weigh 
 well what he had faid. Some time after this converfa- 
 tion he defired that a priell might be brought ; and the 
 lame domeftic introduced to him M. de Farfac, Cnrede 
 St Sulpice. Diderot faw this ecclefiaftic feveral times, 
 and was preparing to make a public recantation of his 
 errors. Condorcet and the other adepts now crowded 
 about him, perfuaded him that he was cheated, that his 
 cafe was not fo dangerous as it was faid to be, and that 
 he only wanted the country air to reftore him to health. 
 For fome time he rtfifted their attempts to bring him 
 back to atheifm, but was at kil prevailed upon to try 
 the effeft of the country air. His departure was kept 
 fecret, and he was concealed in the country till the 2d 
 of July, when he died. His dead body was fecretly 
 brought back to Paris, and a report was fpread and be- 
 lieved that he died fuddenly on rifing from the table,, 
 without remorfe, and with his atheifm unfhaken. 
 
 To draw a formal charafter of this wretch is furely 
 fuperfluous. His friends extol his franknefs, his difm- 
 tercftednefs, and his integrity ; but except his grofs 
 avowal of atheifm, which may in France be called frank- 
 nefs, this charafter is belied by every tranfaftion of his 
 life. He married, and had a daughter, as has been al- 
 ready mentioned. M. Bauze, referred to by Abbe 
 Barruel, coming one day into Diderot's houfe, found 
 him explaining to this daughter a chapter of the gof- 
 pel. When he expreffed fome furprife at this conduft, 
 Diderot faid ; " J'entcnds ce que vous voulez dire ; 
 
 niais
 
 D I F 
 
 [ 493 ] 
 
 D r F 
 
 (Terciitiilmaig au fond, quelles meillcmes !e9ons pourroi^-jo lui 
 Ictliocl donnir, on trouvcrai-jf micux V It was a common 
 "'^'~~' alTertlon of Diderot's, that between him and hh dog 
 •' il ii'y avoit de dliftrcnce que habit." In uttering 
 this fcruiment, he reiembkd not Pope's Indian with un- 
 tutored mind, 
 
 " Who thinks, admitted to that equal fl<y, 
 " His faitliful dog (hall bear him company." 
 
 The Indian hopes to carry his dog with him to heaven; 
 but Diderot hoped to die like a dog, and to be as if he 
 had utvcr been. 
 
 DIFFERENTIAL method, is the art of working 
 with the differences of quantities. By this method any 
 term of a feries may be found from the feveral orders of 
 uirterences being given ; or via- ver/a, any differei ce 
 mav be found from having the terms of the feries given: 
 il likewife (hews how to find the fiim of fuch a feries. 
 And it gives rules to und by interpolation any inter- 
 mediate term, which is not exprelfed in the feries, by 
 having its place or pofition given. 
 
 When any feries of quantities is propofed, take the 
 firft term from the fecond, the fecond from the third, 
 the third from the fourth, &c. then all thefe remainders 
 make a new feries, called thejiijl order of differences. In 
 this new feries take the firft term from the fecond, the 
 fecond from the third, the third from the fourth, &C. 
 as before ; and thefe remainders make another feries, 
 called the fecond order of differences. In like manner, 
 in this feries, take the firft term from the fecond, the 
 fecond from the third, &c.; and thefe will make a feries 
 called the third order of differences ; and after this man- 
 Ber you may proceed as far as you will. Thus in the 
 following propofition A, b, c, d, e, &c. is the feries ; 
 B, B", B3, IV, &c. the firft order of differences ; C, 
 C% C\ &c. the fecond order of differences; D, D% &c. 
 the third order; E, Sec. the fourth order, and fo on. 
 But the firft terms of thefe feveral orders of diflerenccs, 
 as B, C, D, E, Sec. are thofe th.^t arc principally made 
 ufe of in calculations by this method. 
 
 Prop. I. If there be any 'tries. A, h, c, d, e, &c. 
 and if there be taken the fivil differences B, B', B', &c. 
 the fccor>d differences C, C% C, &c. the third difleren- 
 ccs D, DN D', &c. and fo on. 
 
 Then if T ttand for the firft term of the nth 
 
 That is, B^3-A, C = c—2b-\.A, D = </— V+a^^'"""^""',''' 
 — A, JL = e~4d + 6c-^l> + \, &c. or -Br: A— i, J^^];^^ 
 + C = A—2b+c, —D = A—^i + ^c—d, +E = A '"""^ 
 — 4i-|-5f — 4'/-<-'', Sec. where, putting T fuccellively 
 equal to B, C, D, E, &c. and nzzi, 2, 3, 4, &c. the 
 prop, will be evident. 
 
 Cor. Hence 
 A=:A, the firft term. 
 B = — A-|-^, the firft difference. 
 C = A— zli + c, the 2d dift'ercnce. 
 D = — A-f 3* — 3r-f-(/, the 3d difference. 
 E =r A — 4ii-j-6c — 4^-|-<', tlie 4th difference. 
 F = — A-f-ji — loc+iod — Jc-J-/, the 5th difference, 
 &c. 
 
 PkOp. II. If A, i, c, d, e, &c. be any feries, a*"^ 
 there be taken B, C, D, E, &c. the firft of the fever^^ 
 orders of differences ; 
 
 Then, the nth term of the feries will be ;= A 
 
 differences, :±zT:=A — » 3 -f- n X 
 d + nx' 
 
 n - 
 
 I 
 
 n — 2 
 
 Ix"- 
 
 2 
 n — 
 
 -nX- 
 
 n — I 
 
 2 
 
 h — &c. that 
 3 .2 3 4 
 
 is, -j- T, when n is even, and — T when n is odd. 
 
 Tlte feveral orders of differences being taken as be- 
 fore dirtifted, will ftand thus. Then, 
 
 ^ B 
 
 ' B3 °^ 
 
 '^ B4 &c. 
 
 feries 
 ift diff. 
 2d diff. 
 3d diff. 
 4th diff. 
 
 » 
 -A 
 
 + - 
 
 , c , a , e, Sec, 
 c — b , d — c , e — d, &c. 
 c — 2i-|-A, d — 2c-\-b, e — zd-\-c. Sec. 
 d—2c+ib—A,e—3d+ic—b, &c, 
 f— 4(/+6f— 44+A, &c. 
 
 I n - 
 
 -B + - 
 
 2 n — I 1 
 
 -c + — -X- 
 
 n — I „n — 2 
 
 x^r:-^x!L=i4E+,&c. 
 
 2 «--9 
 
 — X — - 
 
 3 
 
 ' 2 3 . 4 
 
 For from the equations in the laft Prop, viz B =: i 
 
 — A,C=c — zi-i-A, &c. we have, by tranfpofing, 
 i=A-j-B, =— A-(-2y-f-C= — A + 2A-f 2B + C 
 (expunging b^ ; that is, 
 
 c=A-l-2B-f-C, </=A — 3^ + 3^ + D=A — 3A— 3B 
 4-3A-f 6B-f 3C-t-D (expunging b and c) ; that is, 
 J=A-f3B-|-3C-f D. Alfo^n— A + 4i-6<r-f4^ 
 + E = (expunging /', c, d) — A + 4A+4B — 6A 
 
 — 12B— 6C-f 4A4- i2B.f 12C4-4D-J-E; that is, 
 e = A-f-4B4-6C-l-4l)-f E, &c. 
 
 Then putting A, b, c, d. Sic. for tlie «th term, and 
 n fucceflively = 1,2, 3, 4, '&c. the feries will be evi- 
 dent. 
 
 Cor. I. If d', d>, d"i, &c. he the firft of the f.ift, fe. 
 cond, third order, &;c. of differences ; then 
 
 The nth term of the feries A, b, c, d, &c. will be 
 
 n — i„ n — I n — 2 n — i n — 2 
 
 = A-i- -—</+—- X -— <f" -H 
 
 I n 
 — X — 
 
 x"-^:iJd" 
 
 +^:zix"- 
 
 Sx"- 
 
 — 4 
 
 3 ' 
 
 &c. 
 
 For B = d',C = d" 
 
 di" + 
 
 D = <^"',_&c. And the CO. 
 ith power. 
 
 efficients are the unclas of the n ■ 
 
 Cor. 2. Mence alfo it follows, that any term of a 
 given feries may be accurately determined, if the diffe- 
 rences of any order happen at laft to be equal. 
 
 Cor. 3. Hence 
 A = .A , the firft term. 
 i = A-|-B, the 2d term, 
 c = A-f2B4-C, tlie 3d term. 
 (i=A-f3B-{-3C-f D, the 4th term. 
 f = A-{-4B-}-6C-i-4D-{-E, the 5th term. 
 /=A.j-5B.i-icC-|-ioD-f-5E-{-I% the 6th term. 
 ^=A-i-6B+i5C-t-2oD-t-i5E-l-6F+G, the 7th term, 
 &c. 
 
 Prop. III. If a, b, c, d, e. Sec. be any feries, and d' 
 
 d" , d"', &c. the firft of the feveral orders of differences; 
 then 
 
 The fum of n terms of the feries is =: n a .^. n 
 
 X 
 
 I , n ■ 
 
 —d'+r.X— 
 
 I n — 2 , n 
 
 -X-Tr—'/'+nX 
 
 — I n — 2
 
 Diflratflion 
 
 if 
 
 nircift. 
 
 4 
 &c. 
 
 D 
 
 ■Id"+ny"-=LL 
 
 A I 
 
 n — J, 
 
 X 
 
 « — Sv" — 4 
 
 -* </"' + 
 
 For in the feries of quantities, 
 
 , <2 , a + ^. (J-f-i+f, a + t-^-c-^ti, &c. 
 I ft difF. are a , i , c , J , &c. 
 2d difT i/' , i!'2 , dj, , &c. 
 3d Jitr. Ji , d''i, , &c. 
 4th diir. d''' , &c. 
 
 Therefore (by Cor. 1. Prop. 11.) the n + ith term 
 ofthefcrles, 0, a, a-\-b, a-\-b-l[-c, a-\-l^c-{-d, &c. or 
 the «th term of the feries, a, a-\-b, a-^b-^c, a-\-b-\-c 
 
 -J- d, &c. is=o + na-f.nX 
 X "-^ d" + &c 
 
 d + nX- 
 
 2 ' 2 
 
 But the nth term of the feries a 
 
 a •\-i, a ■\~ b ^ c, &c. is the fum of n terms of the fe- 
 ries, a, b, c, d, S;c. and therefore equal to n a -^ n X 
 
 ■d + nX 
 
 1 n ' 
 -X 
 
 • d" + &c. 
 
 2 ■ 2 3. 
 
 For a fuller account of this method, and its applica- 
 tion to curves, we refer the reader to Emerfon's works, 
 from which thefe three propofitlons are taken. 
 
 DIFFRACTION, a term firft ufed by GrimaJdi, 
 to denote that property of the rays of light which 
 others have called infleclion ; the difcovery of which is 
 attributed by fome to Grimaldi, and by others to Dr 
 Hook. 
 
 DIMINUTION, in mufic, is the abating^ fomething 
 of the full value or quantity of any note. 
 
 DIOPHANTUS, a celebrated mathematician of 
 Alexandria, has been reputed to be the inventor of 
 algebra ; at leaft his is the earlieft work extant on 
 that fcience. It is not certain when Diophantus lived. 
 Some have placed hira before Chrilt, and fome after, 
 in the reigns of Nero and the Antonines; but all with 
 equal uncertainty. It fccnis he is the fame Diophan- 
 tus who wrote the Canon Aftronomicus, which Suidas 
 fays was commented on bv the celebrated Hypatia, 
 daughter of Theon of Alexandria. His reputation 
 muft have been very high among the ancients, fmce 
 they ranked him with Pythagoras and Euclid in ma- 
 thematical learning. Bachet, in his notes upon the 5th 
 book De Ai ithmcticis, has collefted, from Diophantus's 
 epitaph in the Anthologia, the following circumftances 
 of his life; namely, that he was married when he was 
 33 vears old, and had a fon born five years after ; that 
 this fon died when he was j 2 years of age, and that his 
 father did not furvive him above fouryears; from which 
 it appears that Diophantus was 84 years old when he 
 died 
 
 DIOPTER, or DioPTRA, the fame with the index 
 or alhidade of an aftrolabe, or other fuch inftrument. 
 
 DiOPTRA was an inftrument invented by Hipparchus, 
 which fei-ved for feveral ufes ; as, to level water courfes ; 
 to take the height of towers, or places at a diftance; to 
 determine the places, magnitudes, and diftances of the 
 planets, &c. 
 
 DIRECT, in arithmetic, is when the proportion of 
 any terms, or quantities, is in the natural or direft or- 
 der in which they ftand; being the nppofite to inverfe, 
 which confiders the proportion in the inverted order of 
 the terms. So, 3 : 4 : : 6 : 8 direftly ; or 3 : 4 : ; 8 : 6 
 invetfely. 
 
 Ditti 
 
 494 1 DAI 
 
 DIRECTION, in aftronomy, the motion and other DirciSHon 
 phenomena of a planet when direft. 
 
 Direction, in aftrology, is a kind of calculus, by ^ 
 which they pretend to find the time in which any not- 
 able accident ihali hefal the pcrfon whofe liorofcope is 
 drawn. 
 
 DISCRETE Quantity, is fuch as is not conti- 
 nued and joined together. Such, for inftance, is any 
 number. 
 
 DITTON (Humphry), an eminent mathematician, 
 was born at Saiifbury, May 29. 1675. Being an on- 
 ly fon, and his father obferving in him an extraordi- 
 nary good capacity, determined to cultivate it with a 
 good education. For this purpofe he placed him in a 
 reputable private academy; upon quitting of which he, 
 at the deflre of his father, though againft his own incli- 
 nation, engaged in the prcfeflion of divinity, and began 
 to exercife his funftion at Tunbridge in the county of 
 Kent, where he continued to preach fome years; during 
 which time he married a lady of that place. 
 
 But a weak conftitution, and the dcatii of his father, 
 induced Mr Ditl^n to quit that profeffion. And at the 
 perfuafion of Dr Harris and Mr Whifton, both eminent 
 m.uhematicians, he engaged in the ftudy of mathema- 
 tics ; a fcience to which he had always a ftrong incli- 
 nation. In the profecution of this fcience he was much 
 encouraged by the fuccefs and applanfe he received : 
 being greatly efteemed by the chief profeffors of it, 
 and particularly by Sir Ifaac Newton, by whofe inte- 
 refl and recommendation he was eletled mafter of the 
 new mathematical fcliool in Chrift's Hofpital ; where 
 he continued till his death, which happened in 1 715, 
 in the 40th year of his age, much regretted by the phi- 
 lofophical world, who expected many uieful and inge-. 
 nious difcoveries from his affiduity, learning, and pene- 
 traling genius. 
 
 Mr Ditton publifhed feveral mathematical and other 
 trafts, as below. — i. Of the Tangents of Curve;, &c. 
 Philof. Franf. vol. 23. 
 
 2. A Treatife on Spherical Catoptrics, publifhed in 
 the Philof. Tranf. for 1705 ; from whence it was co- 
 pied and reprinted in the Afta Eruditorem 170", and 
 alfo in the Memoirs of the Academy of Sciences at 
 Paris. 
 
 '. General Laws of Nature and Motion, 8vo, 1705, 
 Wollius mentions this work, and fays that it illuflrates 
 and renders eafy the writings of Galileo, Huygens, 
 and the Principia of Newton. It is alfo noticed by 
 La Roche, in the Memoires de Literature, vol, viii. 
 
 P-46. 
 
 4. An Inftitutlon of Fluxions, containing the firft 
 Principles, Operations, and Applications, of that ad- 
 mirable Method, as invented by Sir liaac Newton, 
 8vo, 1706. This work, with additions and alterations, 
 was again publithed by Mr John Clarke, in the year 
 1728. 
 
 5. In 1709 he publifhed the Synopfi Algebraica of 
 John Alexander, with many additions and corrections. 
 
 6. His Treatife on Perfpeftlve was publiihed in 
 1712. In this work he explained the principles of that 
 art mathematically ; and bcfides teaching the meth' ds 
 then generally praftifed, gave the firti hints of the 
 new method aftcrwaids enlarged upon and improved by 
 Dr Brook Taylor; and wUich was pubiiAied in the year 
 1715. 
 
 7. In
 
 Diving- 
 bell. 
 
 D I V [ 495 ] DOM 
 
 7. In 1714, MrDitton puWiHied Tevf ral p*f ces both defray the expences. Of thcfe attempts, and the kind 
 J theological and mathematical; particularly liin Difcourfe of diving bdl ufed in tliem, the reader will find an ae- 
 on the Refurreftion of Jefu-i Chriil ; and The New count in a work printed at Rotterdam in i66g, and 
 Law of Fluids, <u- a Difcourfe concerning the Afcent entitled G. S'mclari Ars ilova et jnagim gravitatis et It- 
 of Liquids, in exaft Geometrical Figures, between two vilatis. In the year 1680, William I'iilpps, a native 
 nearly contiguous Surfaces. To this was annexed a of America, formed a projedl for fcarchinr and unload, 
 trad, to demonttrate the impoflibility of thinking or ing a rich Spanidi (liip Ain'k on the coail of Hlfpaniola ; 
 perception being the refult of any combination of the and rtprefented hi.i plan in fuch a plaufil^le manner, that 
 parts of matter and motion : a fubjeft much agitated King Charles IL gave him a (liip, and furnilhed him 
 about that time. To this work alio was added an ad- with every thing necejary for the undertaking. He 
 vertifement from him and Mr Whifton, concerning a fet fail in the year 1683 ; but belno unfuccefsful re. 
 method for difcovering the longitude, v,rhich it feems turned again in great poverty, though with a firm con- 
 they had publllhed about half a year before. This at- vidlion of the poffibility of his fclienie. By a fubfcrip- 
 tempt probably coft our author his life; for although it tion promoted chiefly by the Duke of Albemarle, the 
 was approved and countenanced by Sir Ifaac Newton, fon of the celebrated Monk, Phipps was enabled, in 
 before it was prefented to the Board of Longitude, and 16S7, to try his fortune once more, having prcvioufly 
 the method has been fuccefsfnlly put in praftice, in find- engaged to divide the profit according to the twenty 
 jng the longitude between Paris and Vienna ; yet that ihares of which the fubfcription confilled. At firft all 
 board then determined againil it : fo that the difappoint. his labour proved fruitlefs ; but at laft, when his pa- 
 roent, together with fome public ridicule (particularly tience was almofl entirely exhaufttd, he was fo lucky as 
 in a poem written by Dean Swift), affefted his health to bring up, from the depth of fix or feven fathoms, fo 
 fo that he died the enfuiog year, 17 15. much treafure that he returned to England with the 
 In an account of Mr Ditton, prefixed to the German value of two hundred thoufand pounds fterliuT. Of 
 tranfliition of his Difcourfe on the Refurreftion, it is this fum he hiiiifelf got about fixteen, others fay twen- 
 faid that he had publifhed, in his own name only, ano- ty thoufand, and the duke ninety thoufand pounds, 
 ther method for finding the longitude ; but which Mr After he came back, fome perfons endeavoured to per- 
 Whillon denied. However, Raphael Levi, a learned fuade tl>e king to feize both the fhip and the cargo, 
 Jew, who had fludied under Leibnitz, informed the under a pretence that Phipps, when he follcited for his 
 German editor, that he well knew that Ditton and majefty's permifficn, had not given accurate information 
 Leibnitz had correfponded upon the fubjeft ; and that refpeding the bufinefs. But the king anfwered, with 
 Ditton had fent to Leibnitz a delineation of a machine much greatnefs of mind, that he knew Phipps to be an 
 he had iiivented for that purpofe; which was a piece of honeil man, and that he and his friends Ihould fhare the 
 roechanifm conftrucled with many wheels like a clock, whole among them had he returned with double the 
 and which Leibnitz highly approved of for land ufe ; value. His majefty even conferred upon him the ho- 
 hut doubled whether it would anfwer on fhip-board, on nour of knighthood, to (hew how much he was fatisfied 
 account of the motion of the (liip. with his conduft. We know not the conitruftion of 
 DIVING-Bell has been already defcribed in the Phipps's apparatus : but of the old figures of a diving- 
 Encychpa-iiia ; but in that work was given no account machine, that which approaches nearell to the diving. 
 of its antiquity or its invention. In the works of Ari- bell is in a book on fortification by Lorini ; who de- 
 
 llotle we read of a kind of kettle ufed by divers to ena- 
 ble them to remain for fome time under water ; but the 
 manner in which ihofe kettles were employed Is not 
 clearly defcribed. " The oldeil information (faysPro- 
 feifor Beckmann) which we have of the ufe of the di- 
 ving bell in Europe, is that of John Talfiiier, who was 
 born at Hainault in r 509, had a place at court under 
 Charles V. whom he attended on his voyage to Africa. 
 He relates in what manner he faw at Toledo, in the 
 
 fcribes a fquare box bound round with iron, whirli is 
 funilhed with windows, and has a ftool af[i>;ed to it for 
 the diver. This ingenious contrivance appears, how. 
 ever, to be older than that Italian ; at kail he does not 
 pretend to be the inventor of it. 
 
 In the year 1617, Francis Kefsler gave a defcriptioa 
 of his water-armour, intended alfo for diving, but which 
 cannot really be ufed for that purpofe. In tlie year 
 1671, WItfen taught, in a better manner than any of 
 
 pretence of the emperor and feveral thoufand fpeftators, his predcceflbrs, the coTiftrudion and ufe of the di 
 two Greeks let themfelves down under water, in a large ving-bell ; but he is much miftaken when he fays that 
 inverted kettle, with a burning light, and rife up again it was invented at Amllerdam. In 1679 appeared, 
 without being wet. It appears that this art was then new for the firil time, Borelli's well known work ^t mor/;* 
 to the emperor and the Spaniards, and that the Greeks anhnatium ; in which he not only defcribed the divlnir- 
 were canfed to make the experiment in order to prove bell, but alfo piopofed another, the impraiticability 
 the poflibllity of it." of which was ihewn by James Bernoulli. When 
 When the Englilh, in 1588, difperfed the Spanifh Sturm publifiicd his Colleg'mm cur'wfum in 1678, he 
 fleet, called the Invincible Armada, part of the ihips propofed fome hints for the improvement of this ma- 
 went to the bottom, near the Ifle of Mull, on the well- chine, on which remarks were made in the Journal 
 frn coaft of Scotland ; and fome of thefe, according to des f^avans. To him fucceeded Dr Halley, whofe bell 
 the account of the Spaniih prifoners, contained great is well known. 
 
 riches. This information excited, from time to time, DODECATEMORY, the 12 houfes or parts of 
 
 the avarice of fpeculators, and gave rile to feveral at- the zodiac of the pri{num mobile. Alfo the 1 2 figns 
 
 tempts to procure part of the loft treafure. In the of the zodiac are fometimes fo called, becaufe they coa- 
 
 year 1665, a perfon was fo fortunate as to bring up tain each the J2th pai-t of the zodiac. 
 fome cannon, which, however, were not fufficient to DOME. Sec Arch in this Supplement. 
 
 DOMINGO, 
 
 Diving. 
 
 Bell 
 
 II ' 
 Doiiie.
 
 Unmingo, 
 Oon. 
 
 DON [ 
 
 DOMINGO, or St Domingo. See Hispanioiia, 
 both in Encycl. and in this Supplement. 
 
 DON Martin de Mayorga, the name given by 
 the Spaniards to a cluilcr of 'iflaiids in the South Sea, 
 difcovered on the 27th of February 1781 by Don F. 
 A. Maurelle, a celebrated pilot of that nation. 
 
 Thofe iflands are defcribed by him as abounding with 
 tropical fruits and roots, as highly cultivated, and as 
 inhabited by a people confiderably poliflied. The fer- 
 tility of the land, fays he, is fuch, that its cultivation 
 cannot fail to promife a favourable harveft. Every 
 where are feen an endlefs number of cocoa-nut trees, 
 beautiful banana trees ranged in lines with the greateft 
 order, and numerous plantations of potatoes, of which 
 he deferibes fome as fifteen feet in length, and of the 
 thicKnefs of a man's thigh. He admired the order with 
 which every thing was difpofed. No weeds were fuf- 
 fered to grow between the plants; and their roads were 
 kept in repair with a diligence deferving imitation by 
 the mod civilized nations. 
 
 Their government appears from his account to be 
 defpotic. The fovereign, who is called the Tubou, is 
 held in the higheft veneration by his fubjefts, vvhofe 
 Ijves and propeities are at his difpofal. Under him 
 there is an order of nobles called Equis, who, though 
 they flirlnk into inf;j^nificauce in the prefence of the 
 Tubou, have great authority over the people. Thefe 
 people are faid by Maurelle to be of great mufcular 
 Arength and large ilature, the ordinary height of the 
 men being fix feet or fix 'feet four inches, while many 
 of them are much taller. It would appear, too, that 
 they delight in gymnaftic exercifes ; for when the 7u- 
 ■boil, by whom he had been treated with great liofpita- 
 lity, wifhed to amufe him and his {hip's coinpaiiy, he 
 exhibited to them feats of vvreiUing and boxir.g, and 
 that as well by the women as by the men. 
 
 Though thefe people put the greateft confidence in 
 the Spaniards, and frequently Raid whole nights on 
 board the frigate, they had yet the common iuch'nation 
 of favages to fteal. " Every time they came on board 
 (fays our author), clothes, iron-work, whatever fell in 
 their way, they confidered as lawful prize. They drew 
 out through tlie port-holes, or the windows, whatever 
 was within their reach. They thieved even to the very 
 chain of the rudder. I made my complaints to the 
 king; he gave me permiffion to kill whomfoever I fhould 
 deteft in the aft ; and 1 was alfmed he had himfelf dif- 
 covered and punifhed with deatli the authors of the 
 complained of theft. Our vigilance was neceflarily cal- 
 led into atlion ; we furprifed the iflands.'rs ftriving to 
 tear away the new rudder chains ; we fired a piftol at 
 them, one of them fell dead on the occafion, and this 
 was an awful leflon for thofe who were either <in board 
 or alongfide of the frigate ; they faid to themfclves, or 
 to one another, chlto (robber)y<7md (dtath)." 
 
 They make of the bark of trees a kind of cloth not 
 unlike that which has been brought trom other iflands 
 in the South Sea ; and our author deferibes the wo- 
 men as being peculiarly neat both in their drefs and in 
 their perfons. They had their mantles or loofe gar- 
 ments adjufted in neat plaits and folds, and becomingly 
 attached by a knot over the left (houldcr. They wore 
 garlands or wreaths on the head, and chaplets of large 
 glafs beads round their necks; the hair was plcafingly 
 difpofed in trefles, and the whole perfon perfumed with 
 
 Oraii 
 
 ] D R A 
 
 an oil of an agreeable odour ; above all, the /Itin w«8 fo DrieatM, 
 exquifitely clean, that they would not have fuffered the 
 fmalleft particle of duft to remain upon it a moment. 
 
 In this archipelago Don Maurcile found a fafe har. 
 hour, to which he gave the name of El Refugio ; and 
 which he places in South Lat. i8". 36'. and W. Lon. 
 177". 47' 45''. of Greenwich. 
 
 DRACCENA Draco (fee Dracoena, Encycl.), is 
 a native of Madeira, though it is there becoming fcarce. 
 The following account of it is by La Martiniere, natu- 
 ralill in the laft voyage of difcovery by La Peroufe. 
 " The idea of the draccena draco (fays he) given by 
 the ihabby fpecimens cultivated in our hot-houfes, is 
 far inferior to that we entertain of it when we have 
 an opportunity of feeing it in its native foil. I met 
 with three in particular, of wliich the trunk was fix or 
 feven feet high, and four and a half, or five in diameter. 
 The ijrinclpal branches, 1 2 or ij in number, and as 
 thick as a man's body, fhoot out a little obliquely, 
 dividing themfclves generally into two, and now and 
 then into three, to the height of 40 or 50 feet, inclu- 
 ding the feven feet of the trunk. The leaves are all at 
 the extremity of the branches, where they are placed 
 in alternate order, and form a duller. This tree pre- 
 fents the moil perfeft regularity to the eye, and tempts 
 the fpeftator to think that the molt ficilful gardener 
 makes it the objeft of his daily care." 
 
 DRAINS. Under this word in the Encyclopa;dia 
 we publilhed Mr Bayley of Hope's method of draining 
 land ; and by a letter from the author, we liave fmce 
 learned, that experience, the beft guide, has fully pro- 
 ved the ufefuhiefs and durability of his drains. With a 
 candour, however, worthy of a man who writes not for 
 fame, but for the good of the public, he informs us of 
 a millake into which he had led us; and requeils us to 
 correct it in this Suppl-ment. 
 
 " I wiih ^fays he) that, in the Supplement to the 
 Encyclop;tdia, due notice may be taken of a very great 
 error into which I was led in my fcheme of making the 
 viain drains. I conjeftured, that where the bottom of 
 the trench was of a h;ird or folid body, as clay or marl, 
 it might not be neceffary to lay it with bricks or ftones; 
 but in this I was quite wrong. By the runs of water, 
 the alternate changes from wet to dry, and the accefs 
 of air, thefe hard bottoms have been rendered friable ; 
 they have crumbled away, and let in all my drains 
 wliich were not fupported by a bottom laid with brick 
 or Hone." For this information we requeft the author 
 to accept of our thanks, and we are perfuaded we may 
 add the thanks of the public. 
 
 As the draining of land is a matter of great impor- 
 tance in agriculture, and as the fubjecf has been again 
 brought before us, we imagine that our agricultural 
 readers will be glad to find here the fubftance of a paper 
 on this fubje£f, for which the author received the filver 
 medal of the Society inftituted for the encouragement of 
 Arts, Manufactures, and Commerce. That au- 
 thor is Mr John Wedge of Bickenhill, near Coventry, 
 who is not only a great farmer himfelf, but had like- 
 wife been employed by the Earl of Alesford in the ma- 
 nagement of feveral eitates. Encouraged by his lord- 
 Ihip's liberality, Mr Wedge informs the fociety, that 
 he had been employed for fome years in draining large 
 portions of land, of which part was in the Earl's occu- 
 pation, and part in his own, as tenant to his lordlhip. 
 
 The
 
 D R A 
 
 r. The principles upon which he proceeded, as well as his 
 —' mode of pioceduie, he ftates in the following terms : 
 
 In every country there are large portions of land 
 that, in wet feafons, have always what may be called a 
 dry Jurfiue, and other portion; of land that liavc always 
 a nioijl or tuet furfacc ; the former of thele admitting all 
 the water which falls upon them to ilnk freely through 
 their pores to various depths, till falling on clay, or 
 fome other unftuous earth, whofe pores will not permit 
 it to pafs through, it is there held up to a height pro- 
 portioned to the quantity of water which comes upon 
 it, and the facility with which that water is diichar- 
 ged. Thus, held up to various heights, it ferves as a 
 fountain to dillribute its water (either by veins of fand, 
 pebbles, or rock), according to the formation of the 
 different under Itrata on the neighbouring lands, and 
 there forms bogs and other varieties of wet furface, 
 on a bafis that will be always found to conlilt of marl, 
 or clay, or fome mixture thereof. The cfFeft of wa- 
 ter thus diftributed may be divided into two clafTes. 
 The firft clafs, where the water is thrown out by a 
 body of marl or clay, &c. upon the furface of defcend- 
 ing ground, and in the valley (there held up by clay 
 alfo) forms bogs or fwamps. The fecond clais, where 
 the water is held up by marl or clay, as before, having 
 above that marl or clay a ftratum of fand, or pebbles, 
 through which the water paffes ; and above thofe fands 
 or pebbles another ftratum of marl or clay, through 
 the weakeft parts of which the water, by a continual 
 preffure from its fountain, forces a pafTage upwards ; 
 and thus, through the weakeft parts of the marl or 
 clay, furnifhes a continual fupply of water on the fur- 
 face, for the formation or growth of bogs, &c. in pro- 
 portion as this water is more or lefs abundantly fupplied 
 by its fountain or head, namely, the higher lands, into 
 which rain-water freely paffes, as before defcribed. 
 There are alfo different foils, under different circum- 
 ftances, which may form a third clafs of land for drain- 
 ing ; fuch as, ftrong deep foils, or open light foils, ha- 
 ving near the furface a body of marl or day. In either 
 of thefe cafes, the water which falls on the furface muft, 
 for reafons which are felfevident, keep fuch lands, in 
 rainy feafons, conftantly wet and cold ; and it (hould be 
 obferved, that a mixture of all the three before-defcribed 
 claffes of wet land fometinies occur in one field, by fud- 
 den alterations of the under ftrata, and thereby perplex 
 the operator, by requiring all the different modes of 
 draining in the fame field. 
 
 If it be admitted that bogs are thus formed and fed, 
 their cure may be effefted with certainty. The firft 
 clafs, by cutting through the ftratum (be it fand, peb- 
 bles, or rock.) that conveys the water to the bog, and 
 carrying off that water by a clofe drain to fome proper 
 place, where the level admits of its difcharge. The fe- 
 cond clafs, by finking a drain to any convenient depth 
 in the upper clay ; and then digging or boring with 
 a large auger, at a fmall diftance on one fide of this 
 drain, through the remaining part, be it (the upper 
 clay) ever fo deep, into the under ilratum of fand, peb- 
 bles, or rock, through which the water palTes ; which 
 will then rufh up into the drain fo made, with a veloci- 
 ty proportioned to the height of the land or fountain 
 whence it is fupplied. As this drain advances through 
 the land, holes muft be dug or bored, as before, every 
 i^even yards, or at fuch diftance as the ftrength of the 
 SuppL, Vol. I. Part II. 
 
 [ 497 1 
 
 D R A 
 
 fprings may require j and the whole of the wafer thus 
 brought up by tapping the fprings, is carried oft' by the ' 
 drain made in the upper clay, which muft be a cl6ie 
 one, to its proper level, and there difcharged. 
 
 By both thefe methods of draining, large trafts of 
 land, under favourable circumftanccs, may be cured with 
 one drain. The beft place for fixing thefe drains is 
 where the ftratum that conveys the water comes neareft 
 to the furface; and the beft method of afcertaining that, 
 is to bore or dig in different parts through the diffe- 
 I'ent under ftrata. 
 
 The third clafs may be eafily cured by clofe drains, 
 at fuch diftances and depths as will beft carry off the 
 furface-water. It may not be improper to obferve, that 
 where the different ftrata or meaUires crop out, that is, 
 become gradually more and more fliallow in fome cer- 
 tain dired;ion (as is often the cafe, till, one after the 
 other, they all prefent themfelves in fuccelTion on the 
 furface of the earth), draining may often be much more 
 eafily and better efFecled by crofing with the drain the 
 different ftrata or meafures where the levels and other 
 circumitances will admit. 
 
 Some of the land drained was part of a common, in 
 the parifti of Church Bickenhill, in the county of War. 
 wick ; part of it was covered with mofs and hng, had 
 a peaty furface about fix inches deep, and produced 
 little or no grafs : in all wet feafons it was filled quite 
 to the furface, and often overflowed, with water. Some 
 of the land was much more unfound, deeper of peat, 
 and covered with mofs, in moft parts nine inches long ; 
 another part was an abfolute bog in all feafons. 
 
 Having dug or bored with a large auger into feveral 
 parts of the land, Mr Wedge found peat, gravel, and 
 fand mixed, and a quick-fand almoft uniformly. The 
 quick-fand in every part, after getting an inch or two 
 into ft, feemed almoft as fluid as water. Judging from 
 this, that no materials for a drain could be laid in tht". 
 quick-fand, but what it would immediately bury, he 
 dug a trench almoft to the quick-fand, leaving gravel, 
 &c. of fufficient ftrength to bear up the materials for a 
 hollow drain ; thefe materials were two fides and a co- 
 verer of ftone, with a peat-turf on the top to keep out 
 the foil. At every feven yards forward, by the fide of 
 this drain, he dug a hole in the quick-fand as deep 35 
 it would permit. From thefe holes the water rofe free- 
 ly into the hollow drain, and was by it difcharged at a 
 proper level. It may be proper to remark, that the 
 ftone made ufe of for this drain, and all others here 
 mentioned, was a red fand and rag-ilone, which eafily 
 fplit into proper fizes for the puroofe, and is very dj- 
 rable ; it cofl about fixpence per ton getting, exclufiva 
 of carriage. The drain thus for;ned ran on the whole 
 rather freely, and made the land dry for a few yards aw 
 each fide thereof, but was far from having the cfTeft he 
 improperly expefted ; for it evidently ajipears that the 
 dram could only take a very fmall portion of the water 
 from fo large a quick-fand, which it did not penetrate 
 more than two inches ; and that it could drain only to 
 its own depth, or, at raoft, to that depth in the foun- 
 tain which fupplied the quick-fand. His purpofe was 
 then defeated ; and his motive for mentioning this error 
 cannot, he hopes, be miftaken. 
 
 He now did what he fays he (light to have done be- 
 fore, that is, examined the ditTercnt ftrata to a greater 
 depth, particularly on the bog, and at the upper edges 
 3 R thereof
 
 D R A [ 498 ]. D R A 
 
 Drains, thereof, and found the bog to be what has teen defcri- their edges on each fide of tlie bottom of the drain, T>tvi 
 """V^—^bed under the liril clafs. He therefore determined to forming two fides of a trough of peat ; then fide ftonts^~~v~ 
 attempt the cure in the manner before prdcribed for about eight inches high, and a Hone coverer, were put 
 that clafs, namely, to cut through the whole of the lira- in upon the ling between the peat- turfs ; a large peat- 
 turn (in this inftance, of quick-fand), through which turf, near two feet wide and four inches thick, was 
 he found the waiter pafs. This he etfefted as follows : then cut and firmly placed over the whole : this left in 
 The fummer being dry, and favourable for the purpofe, the bottom of the drain an open fpace, of more than 
 and having previoully made his main open drain, he began fix inches fquare, for the water to pafs. The whole 
 his main clofe drain the tirll week in June 1791, three was then completed by tilling in the upper part of the 
 feet wide, on the declivity near the edge of the great drain. 
 
 bog. In the firll operation he dug through the peat. In this way the author drained, for about L. 80, 
 
 the hard fand, and gravel, and one fpade's graft (about thirty acres of land, which, from being of no value 
 
 nine inches detp, and feven inches wide) into the quick- whatever, became worth at leaft 14 (hillings per acre of 
 
 fand the whole length of this drain, which was 73 yearly rent. He likcwife hollow-drained nine acres by 
 
 perches, of eight yards to the perch, in length. The the method prefcribed for the third clafs of wet land, 
 
 drain thus dug ran copioufly, not lefs than 60 gallons Theie diaiiis were made a few yards below that part of 
 
 per minute. In this ftate he left it about nine d;iys : each field where the dry and wet land feparate, about 
 
 the effeft of it was rapid, both above the drain and on 22 inches deep, with fides and a coverer of llone, and 
 
 the bog below. Upon examination, he now found about ling on the top of it, to keep the earth from running 
 
 three inches on the top of the fpade's graft, which had in. The length of thefe drains was 88 J yards, and the 
 
 been made into the quick-fand perfeftly dry. He then expence of labour and materials three halfpence per 
 
 dug out thefe three inches of dry fand, to nearly the yard. The drains, in wet weatlier, difcharge a large 
 
 whole width of the drain, three feet ; and at the fame quaitity of water ; and will, he has no doubt, anfwer 
 
 time dug out, as before, another fpade's graft from the the intended purpofe. Thus far relates to land in his 
 
 top of the quick-fand, as near the middle of the drain own occupation. 
 
 as poffible. This was left to run a few days, as before. Nine acres of the land in the earl of Aylesford's occu- 
 and had the fame effeft, namely, three or four inches pation was almoft an entire pulp. This bog was of the 
 more of the top of the quick-fand became dry and hard, fecond clafs, namely, water paffing through a quick- 
 The fame operation was repeated again and again with fand, and confined by a llratum of clay below, and ano- 
 the fame efteft, till the purpofe of getting through this ther ftratum of clay above it. The water thus coii- 
 quick-fand was completed, fo far at leaft as the level of fined, being preiTed by its fountain, and forced up thro' 
 the main open drain would permit. The ftream of wa- the weakeil parts of the clay, had formed a bog of ir- 
 ter continued increafing during the whole operation ; regular thicknefs on the furface, in fome places fix feet 
 the bog below the drain was quite dry, and the land deep, in others not more than two. As there is a con- 
 above perfeftly fo. The drain which was firft made, fiderable fall in this land from eaft to weft, he thought 
 and continued running for fome time during the. pro- it expedient to put two drains into it ; and this appears 
 grefs of the main clofe drain, became gradually dry ; to him to have been neceffary, from a confideration that 
 and has not, fince that drain was finifted, difchargcd both thefe drains continue to run in the fame propor- 
 one fingle drop of water. Great care was neceffary, in tions as when firll opened. The manner in which theie 
 making the main clofe drain, to keep the ftream of wa- drains were executed was, by digging through the dif- 
 ter in the middle of it, otherwife the current would have ferent upper ftrata, and as deep into the clay as the 
 undermined tlie fides, as it fometimes had done, and main open drain would admit ; then digging or boring 
 caufed them to fall in. For this reafon it was necef- through the remaining part of that clay into the quick- 
 fary, when the dry fand was taken from the top of the- fand, at the diftance ot about fix yards in a progrefiive 
 quick-fand, immediately to take out a fpade's graft from r/ianner. 
 
 the middle thereof, in order to divert the current from The water rifing rapidly through thefe holes into the 
 
 the fides. clofe drains, has cifected a complete cure of this land. 
 
 The main clofe drain thus made was three feet wide every part of which will now bear a hoife to gallop 
 
 at top, about nine feet deep on the average, and, bevel- upon it. Thefe drains difcharge 3660 gallons an hour ; 
 
 iing a little from the top, it was about one foot ten which is much lefs than they did at firll, as mull be the 
 
 inches wide at the bottom. The ftone and other ma- cafe in all bogs. This "nind will be worth twenty fliil- 
 
 terials were put into this drain in the following manner : lings per acre. The draining coft twfenty-five pounds ; 
 
 Where the drain went through the quick-fand into and the length of the under-ground drains is eight hun- 
 
 the ftratum of clay below it, as in moft places it did, dred and fourteen yards. 
 
 the bottom, and in fome inftances the fides, wanted no Mr Wedge had juft finifhed (January 1792) drain- 
 particular fecurity (a); but where it did not go quite iiig another piece of land, about forty-three acres. As 
 through the quick-fand, which the level of his main this was intended to anfwer two purpofes, one, to draiii 
 open drain in fome places would not admit, the bottom the land, the other, to give an additional fupply of wa- 
 of the drain was covered half an inch thick with ling ; ter to a mill-pool, and as a circumftance arofe in the 
 then peat-turfs, one foot wide and three or four inches execution of the work which frequently happens in 
 tliick, were cut in convenient lengths, and placed on draining land, namely, a fudden alteration in the po- 
 
 fitiou 
 
 (a) He will probably find in time that he was under the fame miftake with Mr Bayley, and we hope that with 
 Mr Bayley's candour he will acknowledge it.
 
 D R 
 
 fition of tlie under (Irala 
 
 not, we hope, be thought tedious. This dlaiiiing was 
 begun at the level of a mill-pool, and continued, with- 
 out any great difficulty, to tiie dillame of about thirty- 
 two chains, in the manner before defcribtd as a cure for 
 the fecond clafs of boggy land : but at or near that 
 place the under ftrata altered their pufition ; the quick- 
 fand which conveyed the water now became of twice 
 its former thicknels ; and the clay, which had hitherto 
 been above that quick fand, for fonie diftance difap- 
 peajed. From the quick-fund thus becoming- fo much 
 deeper, he could not, witli the level of the null-pool, 
 cut through it ; nor indeed, from the wctnefs of the 
 ftafon, would fuch an operation have been proper. He 
 therefore continued a (hallow drain to fonie diftance, 
 making fide-holes into the quick-fand, which lan freely; 
 but as this could not cure the whole of the bog below, 
 lie branched out another drain ^which was made by the 
 method dcfciibed for curing the fecund clafs of wet or 
 boggy land), by finking a dofe drain through the up- 
 ]ier Itrata into the upper clay, and then, at a fmall dif- 
 tance on one fide of this clofe drain, boring a hole with 
 
 O [ 499 ] . .^ . '^^ A 
 
 •a defcrijition tliercof will (aa quoted by Withering, in hia Arrangement of BrI- DMigi 
 
 tilh Plants,) mentions the cflcfts of this finguhir plant, H . 
 occafioned by the irritation of an aiit, which he placed ,"""""^. 
 on the centre of one of the leaves with a p?ir of pincers. ' 
 The ant, in endeavouring toefcape, was held fad by 
 the vifcous juice of the Imalkr hairs till the large ones, 
 together with the edges of the leaf, clofed in and im- 
 prifoncd it. The ant died in fifteen minutes ; but he 
 obferves, that the effefts followed fooner or later, in dif- 
 ferent experiments, according to tiie Hate of the wea- 
 ther. Dr Whithering has publidicd a fimilar accoiuit of 
 the fenfitive propeities of the fundew, which was com- 
 municated to him by two of his botanical friends, and 
 which he has made very entertaining and interelling. 
 The fame thing is confirmed by a writer in tlie Month- 
 ly Magazine for Augull 1797 > "■''" %**, that when- 
 ever he made experiments on the drofitra with aiita and 
 other diminutive infefts, he commonly found them perifli 
 in a Ihorter time than fifteen minutes. His experiments' 
 were made on the droflera rotundifolia. Rothius, how. 
 ever, obferves, that the longifolia produces the fame ef- 
 feAs, but with greater rapidity. In concluding his ac- 
 
 n a'lger through the remaining part of that clay into count, Dr Withering fuggells this enquiry, " Whether 
 
 the quick-fand ; and at every eight yards, as this clofe 
 drain advanced, flill boring other holes, in the manner 
 before dcfcribed : through many of thefe holes the wa- 
 ter rufhed with great rapidity. The water difcharged 
 by thtfe drains into the mill-pool is 168 gallons per mi- 
 nute, or 3780 hogfheads in a day ; which is after the 
 rate of 1,379,700 hoglheads in a year. 
 
 About fix acres of this land were always found ; a- 
 bout twelve acres on the north fide were an abfolute 
 pnlpj and the remaining twenty fix acres very unfound. 
 The whole is now found, and will, when cultivated, be 
 worth fixtcen fhillings per acre. This land would have 
 been drained at a much lefs cxpence into the main open 
 drain ; but then the water, which was much wanted 
 for the mill, would have been loft.. Thefe clofe drains 
 are in length 1452 yards, and coft L. 100, of which 
 about L. 30 ought to be charged to the mill. 
 
 Important as this fubjeft is, we inull not enlarge this 
 article, or we ihould make large extrafts from Dr An- 
 dcrfon's PraB'ual Trealife on Draining Bogs and Siuam- 
 py Grounds, lately publilTicd. It is proper, however, 
 to inform the public, that the author puts In his claim 
 for being the firft difcoverer of that mode of draining 
 for which Mr Elkington has obtained from Parliament 
 a premium of L. 1000 ; and the reader who (liall turn 
 to the article Drains in the Encyclopa:dia, will per- 
 ceive that his claim is well-founded. 
 
 DROSSERA Anglicana, or the Sundew (fee 
 Drossera, EncycL), is a very minute villous plant, 
 ufually growing entangled with mofs on peat bogs ; the 
 leaves are cuiioully fringed with numerous ftrong red- 
 difh hairs, terminated by fmall pellucid globules of vif- 
 cous liquor, which occafion, by the refledlion of the 
 fun, thr.t peculiar lufl^re from which its name Is derived. 
 
 this deftrudllon of infefts be not neceffary to the welfare 
 of the plant ?" And it is furely worth fome botanilt'g 
 while to take fome pains to anfwer the queftion. 
 
 DRUGS (fee Encycl.) are fo commonly counter- 
 feited, or at lead adulterated, that, in London, the 
 royal college of phyficians, it is well known, has long 
 ago appointed a court of examiners to inveiligate the 
 goodncfs of drugs and medicines in the different che- 
 inlfts and apothecaries (liops. The coujitcrftit, how- 
 ever, is made up with fuch dexterity, that not only the 
 merchaot and drug-broker, but even the man of (kill, Is 
 fomeilnies deceived ; and indeed nothing can deleft this 
 inipo(itlon but a practical knowledge of chemlllry. Wc 
 therefore recommend it to every father of a family to 
 ftudy our Supplementary article Chemistry with this 
 view, if with no other ; for wliatevcr be the faults or 
 that atricle, we have loll much labour if it be not fuHi- 
 ciently perfplcuous to enable every man, not an abfo- 
 lute ftranger to phyfical fcience in all its branches, to 
 detei;t the common impollures of drug- fellers. 
 
 DUFTER, in Bengal, an otHce or departme^it. 
 
 DuFTSR Catici, the place where the office is kept. 
 
 DWARFING OF vegetables, an art invented by 
 the Chinefe, to which the attention of Sir George 
 Staunton was attrafted on the following occafion : 
 
 When the embalfy was at Chafan (See Chusan in 
 this Supplement), the gentlemen who went on (hore 
 were introduced to the governor in his hall of audience, 
 where on feveral tables were placed, in frames filled 
 with earth, dwarf pines, oaks, and orange trees, bear- 
 ing fruit. None of them exceeded in height two feet. 
 Some of thofe dwarfs bore all the marks of decay from 
 age : and upon the furface of the foil were iiiterfperfed 
 fmall heaps of ftones, which, in proportion to the ad- 
 
 It is in thefe hairs that thefe effential properties of the joining dwarfs, might be termed rocks. Thefe were 
 
 plant refide ; for if a fmall infeft fhould fix itfclf on one 
 of the leaves, thefe hairs immediately begin to clofe, 
 one by one, till the Infeft is wholly environed by them, 
 and then the leaf in which it is imprlfoned gradually 
 bends inwards, fo as to reach the bafe : in this ftate 
 the infeft is killed by the operation of the acrimonious 
 juice exuding from the ends of the hairs. Rothius 
 
 honey-combed and mofs-grown, as if untouclied foo- 
 ages, which ferved to maintain the illufioTi, and to give 
 an antique appearance to the whole. This kind of 
 ftunted vegetation leemed to be much rchfiied by the 
 curious in China j and fpecimens of it were to be found 
 in every coufiderable dwelling. To produce them form- 
 ed a part of the gardener's (Icill, and was an art invented 
 3 R a in
 
 D W A t 5 
 
 DAirEng. in that country. Bifjde the mere tnerit of overcoming 
 /""' a d.'fEciilty, it had that of introducing vegetables into 
 common apartments, from which their natural fize mufl 
 cthevwife have excluded them. 
 
 The jrencral method of obtaining vegetable dwarfs is 
 faid to he the following : A quantity of clay or mould 
 is applied to the upper part of the trunk of a tree, from 
 which a dwarf is intended to be taken, and clofe to its 
 divifion into branches. The mould is to be confined to 
 the fpot by coarfe hempen or cotton cloth, and to be 
 carefully kept moid by water. In confequence of this 
 application, continued fometimes above a twelvemonth, 
 fmall tender fibres (hoot down like roots from the wood 
 into the mould. The part of the trunk emitting thofe 
 new fibres, together with the branch rifing immediately 
 above it, is then to be carefully fcparated frr-Ki the reft, 
 of the tree, and planted in new earth, in which the 
 fibres become new roots, while the former branch is 
 now the ftem of the vegetable thus transformed in fome 
 meafure. This operation does not deftroy or alter the 
 produftive faculty which thofe parts enjoyed before their 
 Reparation from their parent root. That which, while 
 a branch of the original tree, bore flowers and fruit, con- 
 tinues to produce the fame, though no longer fupport- 
 ed upon any ftock. The terminal buds of fuch branches 
 of trees as are meant to become dwarfs are torn off ; 
 which circumftance prevents the further elongation of 
 thofe branches, and forces other buds and branchlets 
 from the fides. Thefe branchlets are bent by wires to 
 
 00 ] DYE 
 
 whatever form the operator wifhes : and when the ap- 
 pearance cf age and decay is meant to be given to a 
 dwarf tree, it is repeatedly fmeared with treacle or mo- 
 lafies, which attrafts multitudes of ants, who, in pur- 
 fuit of thofe fweet juices, attack the bark, and, by a 
 gradual corrofion of it, produce the defired effefl. Thefe 
 different proccffes are fornetimcs attempted to be kept 
 fccret by the gardeners, and they vary defignedly in the 
 mode of carrying them on; but the principle on which 
 they are founde^d is fufficiently apparent from what is 
 related here ; and the contrivance argues ingenuity and 
 perfcverance, rather than the praftice does true tafte, 
 which confifts in affifting Nature in its moil favourite 
 works — not in counterafting its operations or diftort- 
 ing its produflions. 
 
 DYEING is an art into which, fince the article in 
 the Encyclopaedia was publilhed, improvements have 
 been introduced of fuch importance, that it would be 
 unpardonable not to notice them in this Supplement. 
 They ought to be noticed under the prefent title ; but, 
 for reafons affigned at the time, we were under the ne- 
 ceflity of poftponing them, in the firll edition, to the 
 title Vegetable, /Inimal, and Dyeing Substances. We 
 might now rettore the article Dyeing to its proper 
 place ; but though we confidently announce this as an 
 improved edition, we doubt whether we can, in juftice 
 to the purchafers of the firfl edition, alter its arrange- 
 ment. We therefore ftill refer the reader to the article 
 Dyeing Substances, 
 
 Hyeing, 
 
 DYNAMICS. 
 
 Definition. 
 
 Objefl f)f 
 dynamics i 
 change of 
 that cond> 
 tion of a 
 thing 
 which we 
 call its ino- 
 
 THIS name marks that department of phyfico-ma- 
 thematical fcience which contains the abftraft 
 doftrine of moving forces ; that is, whatever necef. 
 farily refults from the relations of our ideas of motion, 
 and of the immediate caufcs of its production and 
 changes. 
 
 All changes of motion are confidered by us as the In- 
 sdications, the charafteriftics, and the meafures of chan- 
 ging caufes. This is a phyfical law of human thought, 
 and therefore a principle to which we may refer, and 
 from which we muft derive all our knowledge of thofe 
 caufes. When we appeal to our own thoughts or feel- 
 ings, we do not find in ourfelves any difpofition to refer 
 mere exillence to any cauie, although the beginning of 
 exiftence certainly produces this reference in an inftant. 
 Kad we always obferved the univerfe in motion, it does 
 not appear that we fhould have afcribcd it to a caufe, 
 till the obfervation of relative reft, or fomething leading 
 to it, had enabled us to feparate, by abftraftion, the 
 notion of matter from that of motion. We might then 
 perceive, that reft is not incompatible with matter ; and 
 we might even obferve, by means of relative motions, 
 that abfolute reft might be produced by the concourfe 
 of equal and oppofite motions. But all this requires 
 refietlion and reafoning ; whereas we are now fpeaking 
 of the firft fuggeif ions of our minds. 
 
 We cannot have any notion of motion In abJlraSo, 
 without confideriiig it as a ilate or condition of exiftence, 
 which would remain, if not changed by fome caufe. It 
 is from changes alone, therefore, that we infer any agen- 
 cy in nature ; and it is in tUefe that we are to find all 
 that we know of their caufes. 
 
 When we look around us, we cannot but obferve jvrechanie 
 that the motions of bodies have, in moft cafes, if not relation, 
 always, fome relation to the fituation, the diftance, and what, 
 the difcriminating qualities of other bodies. The mo- 
 tions of the moon have a palpable relation to the earth; 
 the motions of the tides have as evident a relation to the 
 moon ; the motions of a piece of iron have a palpable 
 dependence on a magnet. The vicinity of the one 
 feeras to be the occafion, at leaft, of the motions of the 
 other. The caufes of thefe motions have an evident 
 conneftion with or dependence on the other body. We 
 are even difpofed to imagine, that they are inherent in 
 that body, and that it poireffes certain qualities which 
 are the caufes of thofe modifications of motion in other 
 bodies. Thefe ferve to diftinguifh fome bodies from 
 others, and may therefore be called properties ; and, 
 fince the condition of other bodies fo evidently depends 
 on them, thefe properties exprefs very interefting rela- 
 tions of bodies, and are chiefly attended to in the enu- 
 meration of the circumilances which afcertain what we 
 call the nature of any thing. We do not mean to fay 
 that thefe inferences are always juft; nay, we know that 
 many of them are ill-founded : but they are real, and 
 they ferve abundantly for informing us what we may 
 expeft from any propofed fituation of things. It is 
 enough for us to know, that when a piece of iron is fo 
 and fo fituated in relation to a magnet, it will move in 
 a certain manner. 
 
 This mutual relation of bodies is differently confider- 
 ed, according to the intereft that we chance to take in 
 the phenomenon. The caufe of the approach of the 
 iron to a magnet is generally afcvibed to the magnet, 
 
 which
 
 D Y N A 
 
 vihkh is faid to attraft the iron, becaufe we commonly 
 employ the magnet in order that thefe motions may 
 take place. Tlie limilar approach of a Hone to the 
 earth is afcribcd to the ftone, and we fay that it tends 
 to the earth. In all probability, the procedure of na- 
 ture is the fame in both; for they are obferved, in every 
 in (lance, to be mutual between the related bodies. As 
 iron approaches a magnet, fo the magnet approaches 
 the iroji. The fame thing is obferved in the motions 
 of eleftrified bodies ; alfo in the cafe of the ftone and 
 the earth. Therefore the caufe of the motions may be 
 conceived as inherent in either, or in both. 
 Ftne and The qualities thus inherent in bodies, conftituting 
 /laimiTt their mechanical relations, have been called the mecha- 
 Sgurative [j,cal affections of matter. But they are more 
 w-™[^Q^g" commonly named powers or forces; and the event 
 ^lanifin- which indicates their prefence, is confidered as the ef. 
 feft and mark of their agency. The magnet is faid to 
 ACT on the iron, the earth is faid to act on the ftone, 
 and the iron and the ftone are faid to act on the mag- 
 net and on the earth. 
 
 All this is figurative or metaphorical language. All 
 languages have begun with focial union, and have im- 
 proved along with it. The firft colleftions of words 
 exprefied the moft familiar and the moll interefting no- 
 tions. In the procefs of focial improvement, the num- 
 ber of words did not increafe in the fame proportion 
 with the notions that became interefting and familiar in 
 their turn : for it often happened that relations of certain 
 ideas fo much refembled the relations of certain other 
 ideas, that the word expreffing one of them ferved very 
 well for expreffing the other; becaufe the diflimilar cir- 
 " cumftances of the two cafes prevented all chance of mif- 
 take. Thus we are faid to furmount a difficulty without 
 attaching to the word the notion o{ getting over a lleep 
 5 hill. Languages are thus filledwith figurative exprefTions. 
 
 But the »- Power, Force, and Action, are words which muft 
 nalogy is J^gve appeared in the language of the moft fimjile peo- 
 forcc but P'* ' ^''■'^^ufe the notions of perfonal ability, ftrength, 
 in the df- and exertion, are at once the moft familiar and the moft 
 't&. interefting that can have a place in the human mind. 
 
 Thefe terms, when ufed in their pure, primitive fenfe, 
 exprefs the notions of the power, force, and adlion of 
 a fentient, aftive, being. , Such a being only is an 
 agent. The exertion of his power or force is (exclu- 
 fively) action : But the relation of caufe and effeft fo 
 much refembles in Its refults the relation between this 
 force and the work performed, that the fame term may 
 be very intelligibly employed for both. Perhaps the 
 only cafe of pure unfigurative aftion is that of the 
 mind on the body. But as this is always with the 
 defign of producing fome change on external bodies, 
 we think only of them; the inftrument or tool is over- 
 looked, and we fay that we aft on the external body. 
 Our real aftion therefore is but the firft movement in 
 a long train of fucceffive events, and is but the remote 
 caufe of tlie interefting event. The refemblance to fuch 
 aftions is very ftrong indeed in many cafes of mechani- 
 cal phenomena. A man throws a ball by the motion 
 Oi his arm. A fpring impels a ball in the fame manner 
 by unbending. Thefe two events refemble each other 
 in every circumftance but the aftion of the mind on the 
 corporeal organ — the reft of it is a train of pure nie- 
 chanifm. In general, becaufe the ultimate refults of 
 the mutual influence of bodies on each other greatly 
 
 M I C S. joi 
 
 refemble the ultimate refults of our aftions on bodies, 
 we have not invented appropriated terms, but have con- 
 tented ourfelves with thofe already employed for ex- 
 preffing our own aftions, the exertions of our own 
 powers or forcc.i. The relation of phyfical caufe and 
 effeft is exprefied metaphorically in the words which 
 belong properly to the relation of agent and aftion. 
 This has been attended by the ufual confequences of 
 poverty of language, namely, ambiguity, and fumetimes 
 miftake, both in our refleftions (which are generally 
 carried on by mental difcourfe), our reafonings, and 
 our conclufions. It is neceftary to be on our guard 
 againft fuch miftakes ; for they frequently amount to 
 the confounding of things totally dilferent. Many phi- 
 lofophers of great reputation, on no better foundation 
 than this metaphorical language, have confounded the 
 relations of aftivity and of caufation, and even denied 
 that there is any difference ; and they have affirmed, 
 that there is the fame invariable relation between the 
 determinations of the will and the inducements that 
 prompt them, as there is between any phyfical power 
 and its eff^eft. Otliers have maintained, that the firft 
 mover in the mechanical operations, and indeed through 
 the whole train of any complicated event, is a perci- 
 pient and intending principle in the fame manner as in 
 our aftions. According to thefe philofophers, a particle 
 of gravitating matter perceives its relation to every other 
 particle in the unlverfe, and determines its own motion 
 according to fixed laws, in exaft conformity to its iitu- 
 ation. But the language, and even the aftions ot all 
 men, ftiew that they have a notion of the relation of an 
 agent to the aftion, eafily diilinguiiliable (becaufe all 
 diftinguilli it) from the relation between the phyfical 
 caufe and its eft'eft. The proofs of this faft have been 
 adduced in other parts of the Encyclopajdia Britannica, 
 as, for example, in the article Philosophy, n" 42. and 
 in this Supplement in the article Action. 
 
 Thefe remarks are not made in this place for any phi- 
 lological purpofe, fuch as the mere improvement of lan- 
 guage ; but becaufe this metaphorical language has af- 
 fefted the doftrines of mechanical philofophy, and has 
 produced a difpute about fome of its firft principles; and. 
 becaufe we find that the only way to decide this dilpute 
 is to avoid, moft fcrupuloufly, all metaphorical language,, 
 though at the expence of much circumlocution.. g 
 
 When we Ipeak of powers or forces as refiding In a Dirciltion.T 
 body, and the efft6l as produced by tlicir exertion, the*"'' 'Z'' ^"^ 
 body, confidered as poffeffing the power. Is faid to ACT ,„j.||j,J,',ij^ 
 on the other. A magnet is faid to aft on a piece of analugy, 
 iron ; a billiard ball in motion is faid to aft on one 
 that is hit by it : but If we attempt to fix our atten- 
 tion on this aftion,' as diftinft both from the agent 
 and the thing afted on, we find no objeft of contem- 
 plation — the exertion or procedure of nature in produ- 
 cing the effeft does not come under our view. When 
 we /peak of the aftion as diftinft from the agent, we 
 find that it is not the aftion, properly fpeaking, but 
 the aft, that we fpeak of. In like manner, the action 
 of a mechanical power can be conceived only in the ef. 
 feft produced. 
 
 A man is not faid to aft unlefs he produces fomeAflion 
 effeft. Thought is the aft of the thinking principle ; iiiplies 
 motion of the liinb is the aft of the mind on It. In '•'•i»nR'^; 
 mechanics, alfo, there Is aftion only in fo far as there"'"' "'^"^^ 
 is mechanical effeft produced. I muft aft violently in not aflign. 
 
 order
 
 50a D Y N A 
 
 orJer to begin motion on a fll'Jc : I miift exert force, 
 and this force exerted produces motion. I conceive 
 the produftion of motion, in all cafes, as the exertion 
 of force ; but it requires no exertion to continue the 
 motion along the Aide ; I am confcious of none, there- 
 fore I ought to infer that no force is neCeffary for the 
 continuation of any motion. The continuation of mo- 
 tion is not the produftion of any new effetl, but the 
 permanency of an effeft already produced. We in- 
 deed coniiJer motion as the eflctl of an aftion ; but 
 there would be no efFeft if the body were not moving, 
 g Motion is not the aftion, but the effeft of the atlion. 
 
 Tr/jfion/un. Mechanical aftions have been ufually clafled under 
 fulfun. two heads : they are either Pressures or Impulsions. 
 They are generally coniidcred as of different kinds; the 
 exertions of different powers. Pressure is fuppofed 
 to differ effentially from Impulse. 
 
 Inllead of attempting to define, or dcfcribe, thefe 
 two kinds of forces and aftions, we (hall juft mention 
 fome inftances. This will give us all the knowledge of 
 their diftiniSlions that we can acquire. 
 Examples When a ball lies on a table, and I prefs it gently on 
 of preffion. one fide, it moves toward the other fide of the table. 
 • If I follow it with my finger, continuing my preifure, 
 it accelerates continually in its motion. In like man- 
 ner, when I prefs on ttie handle of a common kitchen 
 jack, the fly be^'ins to move. If I continue to urge or 
 prefs round the handle, the fly accelerates continually, 
 and may be brought into a (late of very rapid motion. 
 Thefe motions are the effefts of genuine prtiuire. The 
 ball would be urged along the table in the fame man- 
 ner, and with a motion continually accelerated, by the 
 unbending of a fpring. Alfo, a fpring coiled up round 
 the axis of the handle of the jack would, by uncoiling 
 itfelf, urge round the fly with a motion accelerating in 
 the fame way. The more I reflecl on the prelTure of 
 my finger on the ball, and compare it with the effeft 
 of the fpring on it, the more clearly do I fee the per- 
 feft fimilarily ; and I call thefe influences, exertions, 
 or aftions, by one name, pressure, taken from the 
 moll familiar inftance of them. 
 
 Again, the vei-y fame motion may be produced in 
 the ball or fly, by pulling the ball or the machine by 
 means of a thread, to which a weight is fufpcnded. As 
 both are motions accelerated in the fame manner, I call 
 the influence or aflion of the thread on the ball or ma- 
 chine by the fame name pressure, and weight is con- 
 fidered as a prcffing power. Indeed I feel the fame com- 
 preffion from the real preffure of a man on my ftioul- 
 ders that I would feel from a load laid on them. But 
 the weight in our example is acting by the intervention 
 of the thread. By its preffure, it is pulling at that part 
 of the thvcud to which it is f.iftcr,ed ; this part is pul- 
 lin"' at the next by means of the force of cohefion ; and 
 this pulls at a third, and fo on, till the moft remote 
 pulls at the ball or the machine. Thus m^y elafficity, 
 weight, cohefion, and other forces, perform the ofScc 
 of a genuine power ; and fince their refult is always a 
 motion beginning from nothing, and accelerating by 
 perceptible degrees to any velocity, this refemblance 
 makes us call them by one familiar name. 
 
 But farther, I fee that if the thread be cut, the 
 weight will fall with an accelerated motion, which I will 
 increafe to any degree, if the fall be great enough. I 
 afcribe this alfo to a prefling power afting on the 
 weight. Nay, ufter a very little refinement, I confider 
 
 M I C S. 
 
 this power as the caufe of the body's weight ) which 
 word is but a diftinguifhing name for this particular 
 inftance of prefling power. Gravitation is therefore 
 added to the lift of preffures ; and, for fimilar reafons, 
 the attraftions and repulfions of magnets or eleftric bo- 
 dies may be added to the lift ; for they produce aftual 
 compreffions of bodies placed between them, and they 
 produce motions gradually accelerated, precifely as gra- 
 vitation does, 'i'herefore all thefe powers may be dif- 
 tinguiftied by this defcriptive name prejjurts, which, in 
 ftriA language, belongs to one of them only. 
 
 Several writers, however, f'.'.bdivide this great clafs Gravirv at. 
 into preffions and folicitations. Gravity is a folicita- trattions, 
 tion ab extra, by which a body is urged downward. ^"<^ r^pul- 
 
 In like manner, the forces of magnetifm and electricitv, "^','"'*, 
 J a ■ . r -I .. /T J 1.- ' conCdertd 
 
 and a vaft variety ot other attractions and repuliions, ^^ prefiions 
 
 are called folicitations. We fee little ufe for this dif- 
 
 tinftion, and the term is too like an affeflion of mind. 
 
 Impulsion is exhibited when a ball in motion puts i:,., ' i 
 another ball into motion by hitting, or (to ipcak meta-of impul- 
 phorically) by ftriking it. The appearances here are Hon. 
 very different. The body that is itruck acquires, in 
 the inftant of impulfe, a fenfible quantity of motion, and 
 fometimes a very rapid motion. This motion is neither 
 accelerated nor retarded after the ftroke, unlcfs it be af- 
 fefted by fome other force. It is alfo remarked, that 
 the rapidity of the motion depends, inter alia, on the 
 previous velocity of the ftriking body. For inftance, 
 if a clay ball, moving with any velocity, ftrike another 
 equal bail which ij at reft, the ftruck ball moves with 
 half t!ie velocity of the other. And it is farther re- 
 nrarkible, that the ftriking body always lofes as much 
 motion as the ftruck body gains. This univerfal and 
 remarkable faft fcems to have given rife to a confufed 
 or indiftlnA notion of a fort of transference of motion 
 from one budy to another. The phraleology in gene- 
 ral uie on this iubject expreffes this in the moft precile 
 terms. The one ball is not faid to caufe or produce 
 motion in the other, but to commmiieatj motion to it ; 
 and the v/hole phenomenon is called the communication 
 of motion. We call this an ituliflinft notion ; for furely cai^rinnim- 
 no one will lay that he has any clear conception of it. cation of 
 We can form the moft diltintt notion of the communi- '""t'o"-""' 
 cation of heat, or of the caufe of heat ; of the communi-^ '^ *■*" 
 cation or laltneis, iweetnels, and a thouiaiid other 
 things ; but we cannot conceive how part of that iden- 
 tical motion which was formerly in A, is now infufed 
 into B, being given up by A. It is in our attempt to 
 form this notion tluit we find that motion is not a 
 thin^, not a fubftance which can exift independently, and 
 is fufeeplible of adlua! transference. It appears in this 
 cafe to be a llate, or condition, or mode of exiftence, 
 of which bodies are iufceptible, which is producible, or 
 (to fpeak without metaphorj caufable, in bodies, and 
 which is the effect and cbaraderijlic of certain natural 
 qualities, properties, or powers. We are anxious to have 
 cur readers imprcfled with clear and precife notions on 
 this fnbjeif, being confident that fuch, and only fuch, 
 will carry them through fome intricate paths of mecha- 
 nical and philofophical refearch. 
 
 The remarkable circumftance in this phenomenon is, - . '" 
 that a rapid motion, which requires for the effetling itforct is the 
 the aftion of a prefling power, continued for a fenfible, diftimftive 
 and frequently a long time, feems to be effefted in an'^haraaeroi 
 inftant by impulfion. This has tended much to fup.""P""'°°' 
 port the notion of the aiftual transference of fomething 
 
 formerly 
 
 \,
 
 D Y N A 
 
 formerly polTo/Ted excliifively by the ftr!kin<j body, in- 
 Iiering in it, but iVparablc, ami now tr;iiistii<ed, into 
 tlie body ftriken. And now room is founa for the 
 employment of metaphor, botli in thought and lan- 
 guage. The flr'iLing body affects the body which it thus 
 impels : It therefore poffcfres the potut:r of impulfion, 
 that is, of conimunicultn;^ motion. It pofielTes it only 
 while it is in motion. This power, therefore, is the 
 tfficient dillinguilhiiig caufe of its motion, and its only 
 o&ce muft be the continuation of this motion. It is 
 therefore called the inherent force, the force inlie- 
 rent in a moviinT body, vis insit.4 carpari moto. This 
 force is transfiilcd Into the body impelled ; and ihcrejure 
 the transference is inftanlancous, and the impelled body 
 continues its motion till it is changed by fome other ac- 
 tion. All this is at firlt fight very plaufible ; but a 
 fcrupulous attention to thofe feelings which have given 
 rile to this metaphorical conception, (hould have pro- 
 duced very different notions. 1 am confcious of exer- 
 tion in order to begin motion on a (lide ; but if the ice 
 be very fmooth, I am confcious of no exertion in order 
 to Hide along. My power is felt only while 1 am con- 
 fcious of exerting it : Theiet'ore I have no primitive 
 feeling or notion of power while I am fliding along. I 
 am certain that no exertion of power is ncccflary here. 
 Nay, 1 find that I cannot think, of my moving forward 
 without effort otherwife than as a certain mode of my 
 exillence. Yet we imagine that the partifans of this 
 opinion did really deduce it in fome fhape from their 
 feelings. We muft continue the exertion of walking in 
 order to walk on ; our power of walking muft be conti- 
 nually exerted, otherwife we fhall flop. But this is a very 
 imperfeit, incomplete, and carelefs obfervation. Walk- 
 ing is much more than mere continuance in progrcfTive 
 motion. It is a continually repeated lifting our body 
 up a fmall height, and allowing it to come down again. 
 * jj This renev.'ed afcent requires repeated exertion. 
 kiid faid to We have other oblervations of importance yet to 
 e infiitite- niake on this force of moving bodies, but this is not 
 r greittr jj^„ moft proper occafion. Mean wliile we muft remark, 
 »n prel- , , - ,i i ,-. • - ■ i • , 
 
 on. that the in'.tantaneous production or rapul motion by 
 
 impulfe liiiS induced the firft mechanicians of Europe 
 to maintain, that the power or force of impulfe is un- 
 fufceptible of any compariiou with a prclTing power. 
 They have atferted, that impulfe is infinitely great when 
 compared with prtffure; not recollefting that they held 
 them to be things totally dlfparate, that have no pro- 
 portion more than weight and fwectnefs. But thefe 
 gentlemen are perpetually enticed away from their creed 
 by the fimllarity of the ultimate refults of prcffure and 
 impulfe. No perfon can find any difference between 
 the motion of two bf.lls moving equally fwift, in the 
 fame direction, one of which is defcending by gravity 
 and the other has derived its motion from a blow. 
 This ftruggle of the mind to maintain its faith, and yet 
 accommodate its doftrlnes to what we fee, has occa- 
 iioned fome other curious forms of expreffion. Preffure 
 is confidered as an ejfort to produce motion. When a 
 ball lies on a table, its weight, which they call ^ power, 
 continually and repeated endeavours (mark the meta- 
 phorical word and thought) to move the ball down- 
 ward. But thefe efforts are ineffecl;ual. They fay that 
 this ineffectual power is dead, and call it a vis mortua; 
 but the force of impulfion is called a vis viva, a living 
 force. But this is very whimfical and very inaccurate. 
 If the impelling ball falls perpendicularly on the other 
 
 M I C S. 
 
 503 
 
 lying on the table, it will produce no motion any 'riore 
 than gravity will j and if the table be annihilated, gra- 
 vity becomes a vu •ui'va. 
 
 We muft now add, that in order to prove that im- Arpumtnts 
 pulie is infinitely greater than preflure, thefe mcchanici-': J'ftin'Sl 
 ans turn our attention to many familiar fafts which plead'''"'!.""""" 
 ftrongly In their favour. A carpenter will drive a nail 
 into a board with a very moderate blow of his hammen. 
 This will require a preffure which fcems many hundred 
 times greater than the iir.peiling eftoit of the carpenter. 
 A very moderate blow will (hiver into pieces a diamond 
 which would carry the weight of a mountain. Seeing 
 this prodigious fujierioiity in the impulfe, how fhall 
 they account for the production of motion by means of 
 preffure \ for this motion of the hammer might have 
 been acquired by its falling from a height ; nay, it is 
 actually acqui."' d by mc.ius of the continued preflure of 
 the carpenter's arm. Tliey confider it as tiie aggregate 
 of an infinity of fuccecding preffiires in etiery inftant of 
 its continuance ; fo that the infignificant fmallncfs of 
 each effort is compenfated by their inconceivable num- 
 ber. 
 
 On the wliclc, we do not think that there is clear Nn diffe- 
 evidence that there are two kinds of mechanical force "'"^^ ''^^ 
 effeiitially difitrent in tiieir nature. It is virtually gf 'ween pref- 
 v.en up by thofe who fay that impulfe is infinitely great- in^puicon, 
 er than preffure. Nor is there any confiderable advan- 
 tage to be obtained by arranging the phenomenon un- 
 der thofe two heads. We may perhaps find fome me- 
 thod of explaining fatisfaCiorily the remarkable diffe- 
 rence that is really oliftrvcd iu the two modes of pro- 
 ducing motion ; namely, the gradual produfllon of mo- 
 tion by acknowledged preflure, and the inftantaneou.=: 
 production of it by impulie. Indeed, we Ihould not 
 have taken up fo much of our reader's attention with 
 this fubjeCt, had it not been for fome inferences that 
 have been made from thefe premifes, which meet us iu 
 our very entry on the confideration of firft principles, 
 and that are of txtenfive influence on the whole fcience 
 of mechanical philofophy, and, indeed, on the whole 
 ftudy of nature. u 
 
 Mechanicians are greatly divided in tlielr opinion',' 'T^'- 
 about the nature of tlie lole moving force in Nature.''"''.'''', 
 Thofe whom we are now fpeaking of, feem to think Q^^tigu j 
 that all motion is produced by preffure : For when 
 they confider impulie ;is equivalent to the aggregate of 
 an infinity of repeated prcffurcs, they undoubtedly fup- 
 pofc any preffure, however infignificant, as a moving , 
 
 force. But there is a party, both numerous and re- 
 fpeCtable, who maintain that impulfion is the fole caufe 
 of motion. We fee bodies in motion, fay they, and we 
 fee them impel others; and we fee that this production of 
 motion is rcgul.ited by fnch laws, that there is but one 
 abfolute quantity of motion in the unlvcrfe which re- 
 mains unalterably the fame. It muft therefore be tranf- 
 fufed in the aCts of coUifion. We alfo fee, with clear 
 evidence, in fome cafes, that motion can ]irodnce pref- 
 fure. Euler adduces fome very whimfical and compli- 
 cated cafes, In which an aCtion, prccifely fimilar to p-ef- 
 fure, may be produced by motion. Thus, two balls 
 connected by a thread, may be fo ftruck that they fhall 
 move forward, and at the fame time wheel round. In 
 this cafe the connecting thread will be ftretched be- 
 tween them. Now, fay the phllofophers, fince we fee mo- 
 tion, and fee that pi-effure may be jiroduced by motion, 
 it is prepofterous to imagine that it is any thing elfe than i
 
 50+ DYNAMICS. 
 
 a refult of certain motions ; and it is' tlie bufinefs of a 
 
 pliilofoplier to inquire and dii'cover what motions pro- 
 duce the prelFuies that we obferve. 
 
 They then proceed to account for thofe prefiing 
 powers, or fulicltations to motion, which we obferve in 
 the acceleration of falling bodies, the attraftions of nnag- 
 netifm and elcdlricity, and many other phenomena of 
 this kind, where bodies, are put in motion by the vici- 
 nity of other bodies, ot-'(in the popular language) by 
 the action of other bodies at a dillance. To fay that a 
 magnet cannot aft on a piece of remote iron, is to fay 
 that it can aft where it is not ; which is as abiurd as 
 to fay, that it can aft 'whm it is not. Nihil movetar, 
 favs Enler, nifi a contiguo et moto. 
 How lines The bulk of thefe philofophers are not very anxious 
 it prndiice about the way in which thefe motions are produced, 
 preflure? • nor do they fall upon fuch ingenious mtthods of pro- 
 ducing prcffure as the one already mentioned, which 
 ■was adduced by Euler. The piece of iron, fay they, 
 is put in motion when brought into the neighbourhood 
 of a magnet, becanfe there is a ftream of fluid iffuing 
 from one pole of the magnet, which circles round the 
 magnet, and enters at the other pole : This ftream im- 
 pels the iron, and arranges it in certain determined po- 
 iltions, juft as a ftream of water would arrange the 
 fiote grafs. In the .ame manner, there is a ftream of 
 fii'id continually moving towards the centre of the earth, 
 which impels all bodies in lines perpendicular to the 
 furface ; and fo on with regard to other like phenome- 
 na. Thefe motions are thus reduced to very fimple 
 cafes by impulfion. 
 Incompa- It is unnecelTary to refute this doftrine at prefent 5 
 tibie with ;^ jg enough that it is contrary to all the diftates of 
 t>h!lofophi°^'^°'"'"°" *^^'"^'^- To/a//>o/c an agent tliat we do not fee, 
 tng. " and for whofe exiftence we have not the fmalleft argu- 
 ment ; with equal propriety we might fuppofe mini- 
 j, ftering fpirits, or any thing that we pleafe. 
 
 Orhira Other philofophers are fo diffatisfied with this notion 
 
 maintain of the produftion of preffure, that they, on the other 
 that pref. j^jn^, affirm that prefl'ure is the only moving force in 
 fofemovinu "ature ; not according to the* popular notion of pref- 
 forte. fure, by the mutual contaft of folid bodies, but that 
 
 kind of preffure which has been cMed fo/icitation ; fuch 
 as the power of gravity. They affirm, that there is no 
 fuch thing as contaft on inftantaneous communication 
 of motion by real collifion. They fay (and they prove it 
 by very convincing fafts (fee Optics, n" 63—68. £n- 
 cycl.), that the particles of folid bodies exert very ftrong 
 repulfions to a fmall diftance ; and therefore, when they 
 are brought by motion fufficiently near to another bo- 
 dy, they repel it, and are equally repelled by it. Thus 
 is motion produced in the other body, and their own 
 motion is diminifhed. And they then ftiew, by a fcru- 
 pulous confideration of the ftate of the bodies while the 
 one is advancing and the other retiring, in what man- 
 ner the two bodies attain a common velocity, fo that 
 the quantity of motion before -collifion remains unchan- 
 ged, the one body gaining as much as the other lofes. 
 They alfo ftiew cafes of fuch mutual aftion between 
 bodies, where it is evident that they have never come 
 into contaft ; and yet the refult has been precifcly fimi- 
 lar to thofe cafes where the motion appeared to be 
 changed in an inftant. Therefore they conclude, that 
 tliere is no fuch thing as inftantaneous comntunication, or 
 transfufion of motion, by contaft in collifion or impulfe. 
 The reafon why previous motion of the impelling body 
 
 is ncceffary, is not that it may have a vis injila forfvi 
 ttiolo, a force inherent in it by its being in motion, but 
 that it may continue to follow the impelled and retiring 
 body, and exert on it a force inherent in itfelf, whetlier 
 in motion or at reft. — According to thefe philofophers, 
 therefore, all moving forces are of that kind which has 
 been named foUcitntion ; fuch as gravity. We (hall know 
 it afterwards by the more familiar and defcriptive name 
 of Accelerating or Retarding force. j^ 
 
 The exertions of mechanical forces are differently ^Slhn, Rr. 
 termed, according to the reference that we make to t hei'''''""'' ^'*- 
 refult. If, in boxing or wreftling, I ftrike, or endea-" ""' 
 vour to throw my antagonift, I am fa id to act ; but 
 if I only parry his blows, or prevent him from throwing 
 me, I am faid to resist. This diftinftion is applied 
 to the exertions of mechanical powers. When one bo- 
 dy A changes the motion of another B, we may coufi. 
 der the change in the motion of B either as the indica- 
 tion and ineafure of A's power of producing motion, or 
 as the indication and mcafure of A's refiilance to the 
 being brought to reft, or having its motion any how 
 changed. The diftinftion is not in the thing itfelf, but 
 only in the reference that we are difpofed, by other 
 confiderations, to make of its effeft. They may be 
 diftinguiftied in the following manner : If a change of 
 motion follow when one of the powers ceafes to be ex- 
 erted, that power is conceived as having refifted. Tlie 
 whole langiiage on this fubjtft is metaphorical. Re- 
 fiftance, effort, endeavour, &c. are words which cannot 
 be employed in mechanical difcuffions without figure, 
 becaufe they all e>:prefs notions which relate to fentient 
 beings ; and the unguarded indulgence of this figura- 
 tive language has fo much affefted the imagination of 
 philofophers, that many have almoft animated all mat- 
 ter. Perhaps the word Reaction, introduced (we 
 think) by Newton, is the beft term for expreffing that 
 mutual force which is perceived in all the operations of 
 nature that we have inveftigated with fuccefs. As the 
 magnet attrafts iron, and in fo doing is faid to all on 
 it ; fo the iron attrafts the magnet, and may be faid to 
 read on it. 15 
 
 With refpeft to the difficulty that has been objefted We need 
 to the opinion of thofe who maintain that all the me- "'^'. f'PPofc 
 chanical phenomena are produced by the agency of ^t-jiftance. 
 trafting or repelling forces ; namely, that this fuppofcs Tendtm'y. 
 the bodies to aft on each other at a diftance, however 
 fmall thofe diftances may be, which is thought to be 
 abfurd, we may obferve, that we may afcribe the mu- 
 tual approaches or receffes to tendencies to or from 
 each other. What we call the attra&icn of the magnet 
 may be confidered as a tendency of the iron to the mag- 
 net, fomewhat fimilar to the gravitation of a ftone to- 
 ward the earth. We furely (at leaft the unlearned) 
 can and do conceive the iron to be affefted by the mag- 
 net, without thinking of any intermedium. The thing 
 is not therefore inconceivable ; which is all that we 
 know about abfurdity : and we do not knowa;iy thing 
 about the nature or effence of matter which renders this 
 tendency to the magnet impoffible. That we do not 
 fee intuitively any reafon why the iron Ihould approach 
 the magnet, inuft be granted ; but this is not enough 
 to entitle us to fay, that fuch a thing is impoffible or in- 
 confiftent with the nature of matter. It appears, there, 
 fore, to be very hafty and unwarrantable, to fuppofe the 
 impulfe of an invifible fluid, of which we know nothing, 
 and of ths exiftence of which we have no proof. Nay , 
 
 if
 
 D Y N A 
 
 if it be true that bodies do not come into contaft, even 
 when one ball hits anotlii-'r, and drives it before it, tliia 
 invilible fluid will not folvc the ditlicuky ; bccaufc the 
 fame ditlicullv occurs in the adion of any jiarticle of 
 the fluid Oil the body. We are obliged to fay, that the 
 produdlion of nuitioii without any clt/rrvcJ confab, is a 
 much more familiar phenomenon than the produftion 
 of motion by impidfion. More motion lias been pro- 
 duced in this way by the gravitation of a fmall llream 
 of water, running ever iincc the creation, than by all 
 the impulfes in the world twice-told. A\'e do not mean 
 by this to fay, tiiat the giving to this obferved mutual 
 relation between iron and a loadltoue the name ten- 
 d..'ncy m:ikes it lefs 'ibi'urd, than when we fay that the 
 loadflonc attrafts the iron ; it only makes it more con- 
 ceivable : It fuggeils a v.'ry familiar analogy ; but both 
 are equally figurative cxprrflions ; at leall as the word 
 tendency is ufed at prefent. In the language of ancient 
 Rome, there was no metaphor when Virgil's hc.o laid, 
 TitiJimus ill Latium. Ttnders verfus fr,hm means, in 
 plain Latin, to approach the fun. The late way of con- 
 ceiving the whole is to fay, that the condition of the 
 iron depends on the vicinity of the magnet. 
 
 When the e.xertions of a mechanical power are ob- 
 ferved to be always direfted toward a body, that body 
 is faid to attratt ; but when the other body always 
 moves ofF from it, it is faid to repel. Thcfe alfo are 
 metaphorical exprefiions. 1 attraft a boat when I pr.U 
 it toward ine by a rope ; this is purely Attraction : 
 and it is pure, unfigurative Repulsion, when 1 purti 
 any body from me. The fame words are applied to 
 the mechanical phenomena, merely becaufe they re- 
 fenible the refults of real attraftion or repulfion. We 
 mult be much on our guard to avoid metaphor in our 
 conceptions, and never allow thofe words to fugged: 
 to our mind any opinion about the manner In which the 
 inechanical forces produce their efTecls. It is plain, 
 that if the opinion of thofe who maintain the exiilence 
 and aftion of the above-mentioned invilible fiuid be 
 jult, tliere is nothing like attraction or repullion in the 
 univerfe. We mull always recur to the limple pheno- 
 menon, the motion to or from the attraction or repel- 
 ling body ; for this is all we fee, and generally all that 
 vi'e know. 
 
 We conceive one man to have twice tlie flrength of 
 another man, when we fee that he can witlilland the 
 united effort of two others. Tlius animal force is con- 
 ceived as a qujintlty, made up of, and meafured by, its 
 own parts. But we doubt exceedingly whether this 
 be an accurate conception. We have not a dlitindt no- 
 tion of one drain added to another ; though we have of 
 their being joined or combined. We want words to 
 cxprefs the difference of thefe two notions in our own 
 minds ; but we imagine that others perceive the fame 
 diflerence. We conceive clearly the addition of two 
 lines or of two minutes ; we can conceive them apart, 
 and perceive their boundaries, common to both, where 
 one ends and the other begins. We cannot conceive 
 thus of two forces combined ; yet we cannot fay, that 
 two equal forces are not double of one of them. We 
 mealure them by the effedls which they are known to 
 produce. Yet there are not wanting many cafes where 
 the aftion of two men, equally ftrong, does not produce 
 a double motion. 
 
 In like manner, we conceive all mechanical forces as 
 meafurable by thei'r efFedls ; and thus they are made 
 SuppL. Vol. I. Part II. 
 
 M 1 C S, 505 
 
 the fuhje6ts of mathenutii\il difcndion. We talk of 
 the propoitions of gravity, magnctifm, electricity, &c. j 
 nay, we talk of the proportion of gravity to magne- 
 tllm : — Yet thife, confidcred in themfelves, are difpa- 
 rate, and do not admit of any propoltion ; but tlicv 
 produce efleC^s, fome of which arc meafuiable, and 
 whole alTumed mealures are fufceplible of compaiiion, 
 being quantities of the fame kind. Thus, one of the 
 cHcCls of gravity is the acceleration of motion in a fall- 
 ing body : magneliim will alfo aceekratc the motion 
 ot a piece of iron ; thcfe two accelerations are compa- 
 rable. But we cannot compare magnetifm with heat ; 
 becaufe we do not know any meafurable efiecls of mag- 
 netifm that are of the fame kind with any cifedts of 
 heat. ' 
 
 When we fay, that the gravitation of the moon is the By their 
 36coth part of the gravitation at the fea-iliorc, wetfFeils. 
 mean that the fall of a llone in a fecond is s'ico times 
 greater than the fall of the moon in the lame time. 
 But we alfo mean (and this exprcdt? the proportion of 
 the tendency of gravitation more purely), tiiat if a Hone, 
 when hung on a fpring lleclyard, draw out the rod of 
 the lleelyard to the mark 3600, the fame ftone, taken 
 up to the dillilnce of tlie moon, will draw it out no 
 further than the mark i. We alfo mean, that if the 
 ftone at the fea-iliore draw out the rod to any mark, 
 it will require Y'-O fuch Hones to draw it out to that 
 mark, when the trial is made at the diltance of the moon. 
 It is not, therefore, in confequence of any immediate 
 perception of the proportion of the gravitation at the 
 moon to that at the furface of the earth that we make 
 fuch an alfertion ; but thefe motions, which we conli- 
 der as its efletts in thefe lituations, being magnitudes of 
 the fame kind, are fufceptible of cumparllon, and have 
 a proportion which can be afcertaincd by obfervation. 
 It is thcfe proportioiis that we contenTplate ; altjiough 
 we fpeak of the proportions of the uiifeen caufes, the 
 forces, or endeavours to defcend. It will be of mate- 
 rial lervice to the reader to perufe the judicious and 
 acute dilTcrtation on quantity in the 45th volume of the 
 Philofophical TranfaCtions ; or he may Itudy the article 
 QUANTITY in the Encychpxdia, where, we trull, he 
 will fee clearly how force, velocity, denlity, and many 
 other magnitudes of vciy frequent occurrence in me- 
 chanical philolophy, may be made the fubjeCts of ma- 
 thematical dilculiion, by means of fome of thofe projier 
 quantities, meafurable by their own parts, wiiich are tn 
 be alfumcd as their mealures. PrelTures are meafurable 
 only by prelfures. When we confider them as mo- 
 ving powers, we ftiould be able to rneafure them by any 
 moving powers, otherwife we cannot compare theni ; 
 therefore it is not as prelTurcs that we then meafure 
 them. This obfervation is momentous. 
 
 One circumftance muA be carefully attended to. 
 That thofe alTumed mealures may be accurate, they 
 mull be invariably connected with the magnitudes which 
 they are employed to meafure, and lo coiinefted, that 
 the degrees of the one mull change in the fame manner 
 with the degrees of the other. This is evident, and is 
 granted by all. But we mull alfo knaiu this of the mea- 
 fure we employ ; we mull lee this conftant and prccife 
 relation. How can we know this ? We do not per- 
 ceive force as a feparate exiilence, fo as to fee its pro- 
 portions, and to fee that thefe are the fame with the 
 proportions of the meafurcs, in the fame manner that 
 Euclid fees the proportions of triangles and thofe of 
 3 S their
 
 SC6 
 
 (cience. 
 
 19. 
 
 their bafes, and that ihefe pTwportions are the fame, 
 when 'he triangles art of equal altitudes. How do 
 we difcover that to every magnitude which we cz\\fort:e 
 is invariably attiched a corrcfponding magnitude of 
 acceleration or defleftion ? — Clearly. In faft, the very 
 exiilence of the force is an inference that we make 
 from the obfervcd acceleration ; and the degree of 
 the force is, in like manner, an inference from the ob- 
 fervcd magnitude of the acceleration. Our menfiires 
 are therefore neccfTarily connefted with the magnitudes 
 which they meafure, and their proportions are the fame ; 
 becaufe the one is always an inference from the other, 
 „ both in fpecies and in degree. 
 Dynamics ^^ '^ ""'^ evident, that thefe difquifitions are fufcep- 
 is a dtmon-tible of mathematical accuracy. Having feleded our 
 ftrative meafures, and obferved certain mathematical relations 
 of thofe meafures, every inference that we can draw 
 from the mathematical relations of the proportions of 
 thofe reprefentations is true of the proportions of the 
 motions; and therefore of the proportions of the forces. 
 And thus dynamics becomes a dcmonilrative fcience, 
 one of the difciflitut accurals. 
 
 But moving forces are confidered as differing alfo in 
 kind ; tlmt is, in dircftion. We affign to the force 
 the direction of the obferved change of motion ; which 
 is not oniv the indication, but alfo the charadteriftic, of 
 the chans;ing force. We call ic an accelerating, retard- 
 ing, deflefllng, force, according as we obferve the motion 
 to be accelerated, retarded, or dtfle&cd. 
 
 Tbefe denominations fhew us inconteftably that we 
 have no knowledsre of the forces different from our 
 knowledge of the effcfts. The denominations are all 
 either defcriptive of the effefts, as when we call them 
 accelerating, penetrating, protrufive, attraftive, or re- 
 pulfive forces ; or they are names of reference to the 
 fubftances in which the accelerating, protrufive, &c. 
 forces, are fuppoied to be inherent, as when we call them 
 ao magnetijm, ehSricity, corpiifcular, &c. 
 Forces are When I ftruggle with another, and feel, that in order 
 flilcovcre ^^ prevent beinj; thrown, I muil e.sert force, I learn 
 iicGtioii to '"St ""y antagoniit is exerting torce. 1 his notion is 
 other lot- transferred to matter; and when a moving power which 
 "'• is known to operate, produces no motion, we conceive 
 
 it to be oppofed by another equal force; the exigence, 
 agency, and intenfity of which is detefled and mea- 
 fured by theft means. The quiefcent ftate of the body 
 is confidered as a change on the llate of things that 
 would have been exhibited in coniequence of the known 
 action of one power, had this other power not aftcd; 
 and this change is confidered as the indication, charac- 
 teriftic, and meafure of another power, detefted in 
 tliis way. Thus forces are recogniied not only by the 
 changes of mglion which they produce, but alio by 
 the changes of motion which they prevent. The co- 
 Lefion of matter in a ilring is inferred not only by its 
 giving motion to a ball which I pull toward me by its 
 intervention, but alfo by its fufpending that ball, and 
 hindering it from falling. I know that gravity is act- 
 ing on the ball, which, however, does not fall. The fo- 
 iidity of a board is equally inferred from its flopping 
 the ball which ftrlkes it, and from the motion of the 
 ball which it drives before it. In this way we learn 
 that the particles of tangible matter cohere by means of 
 moving forces, and that they refill compreffion with 
 force ; and in making this inference, we find that this 
 «orpufcular force exerted between the particles is ^lu- 
 
 DYNAMICS. 
 
 tual, oppofite, and equal : for we muft apply force F'"(^ I.iw 
 equally to a or to b, in order to produce a feparation ° Motion. 
 or a compreffion. We learn their equality, by ohfer- ' | 
 
 ring that no motion enfues while thefe mutual forces 
 are known to aiSt on the particles ; that is, each is op- 
 pofed by another forte, which is neither inferior nor lu- 
 perior to it. 
 
 Of the Laws of Motion. 
 
 Such, then, being our notions of mechanical forces, 
 the cauies of the fenfible changes of motion, there will 
 refult certain confequcnces from them, which may be 
 called axioms or laws of motion. Some of thefe may 
 be intuitive, offering themfelves to the mind as loon as 
 the notions which they involve are prefented to it. 
 Others may be as necclFary refults from the relations 
 of thefe notions, but may not readily offer themfelves 
 without the mediation of axioms of the firft clafs. We 
 fhall fc'ieft thofe which are intuitive, and may be taken 
 for the firft principles of all difcuflions in mechanical 
 phllofophy. 
 
 First Law of Motion. 
 
 Every body continues in a Jlate of rejl, or of uniform rec- 
 tilineal motion, unlefs offeBed by fome mechanical force. 
 
 This is a propofition, on the truth of which the whole 
 fcience of mechanical philofophy ultimately depends. It 
 is therefore to be ellabliflied on the firmell foundation ; 
 and a folicitude on this head is the more jullifiable, 
 becaufe the opinions of philolophers have been, and ilill 
 are, extremely different, both with refpett to the truth 
 of this law, and with refpeft to the foundation on 
 which it is built. Thefe opinions are, in general, very 
 obfcure and unfatisfa&ory ; and, as is natural, they in- 
 fluence the difcuffions of thofe by whom they are held 
 through the whole fcience. Although of contradic- 
 tory opinions one only can be juft, and it may appear 
 iufficient that this one be eftabliflied and uniformly ap- 
 plied ; yet a fhort expofition, at leall, of the red is ne.- 
 ctffary, that the greatell part of the writings of the phi- 
 lofophers may be intelligible, and that we may avail our- 
 felves of much valuable information contained in them, 
 by being able to perceive the truth in the midft of their 
 imperfect or erroneous conceptions of it. 
 
 It is not only the popular opinion that reft is the 
 natural (late of body, and that motion is fomething fo- 
 reign to it, but it has been ferioufly maintained by the 
 greateil part of thofe who are elleemed philofophers. 
 They readily grant that matter will continue at reft, 
 unlefs fome moving force att upon it. Nothing feems 
 neceffary for matter's remaining where it is, but its 
 continuing to exift. But it is far otherwife, fay they, 
 with refpeCt to matter in motion, plere the body is 
 continually changing its relations to other things; there- 
 fore the continual agency of a changing caufe is necef- 
 fary (by the fundamental principle of all philofophical 
 difculhon), for there is here the continual production 
 of an effect. They fay that this metaphyfical argu- 
 ment receives complete confirmation (if confirmation 
 of an intuitive truth be neceffary) from die moft fami- 
 liar obfervation. We fee that all motions, however 
 violent, terminate in reft, and that the continual exer- 
 tion of fome force is neceffary for their continuance. 
 
 Tliefe philofophers therefore affert, that the conti- 
 nual action of the moving caufe is cjenlialty neceffary 
 
 for 
 
 21.. 
 
 Does COD-- 
 tinued mo» 
 tion indi- 
 cate contia 
 nued Ac- 
 
 tion 
 
 2-? 
 Whimficsl- 
 t otion of 
 elemental 
 minds ,
 
 Flrft Law 
 
 if Motion. 
 
 »4 
 ^(ftinn not 
 icceflary 
 or the 
 iontjnu- 
 :nce of 
 notiun. 
 
 for till eoiitlmifliice of the motion : but they differ 
 among tliemfelvcs in their notions and opinions about 
 this canfe. Some maintain, that all the motions in the 
 univerfe are produced and continued by tlie immediate 
 an-cncy of Deity ; otiiers affirm, that in every particle 
 of matter there h inherent a fort of mind, the f""^'? 
 and 'ujTipvJ-u/^n of Aritlole, which they call an Ele- 
 mental Mind, which is the caufe of al! its motions 
 and changes. An overweaning reverence for Greek 
 learning has iiad a great iiiflucnce in reviving this doc- 
 trine of Arillotle. The Greek and Roman languages 
 are affirmed to be more accurate expreffions of human 
 thought than the modern languages are. In thofe an. 
 cient languages, tht verbs which exprefs motion are 
 employed both in the aftive and paffive voice ; whereas 
 we have only the active verb to move, for expreffing 
 both tiie ftate of motion and the adl of putting in mo- 
 tion. " The itone moves down the fiope, and moves 
 all the pebbles which lie in its way ;" but in the an- 
 cient languages the mere ftate of motion is always ex- 
 preffed by the paffive or middle voice. The accurate 
 conception of the i'peakers is therefore extolled. The 
 Hate of motion is exprefied as it ought to be, as the 
 refult of a continual aCtion." Kn'silai, movetur, is equi- 
 valent to " it is moved." According to thefe philo 
 fophers, every thing which moves is mind, and every 
 thing that is moved is body. 
 
 The argument is futile, and it is falfe; for the modern 
 languages are, in general, equally accurate in this in- 
 ilance : " fe mouvoir," in French; '^ Jtch leauegen," in 
 Germnn ; " dvigatfu," in Sclavonic ; are all paffive or 
 refletted. And the ancients faid, that " rarin falls, wa- 
 ter runs, fmoke rifes," juft as we do. i'he ingenious 
 author of Ancient Aletaphyjtcs has taken much pains to 
 gives us, at length, the procedures of thole elementary 
 minds in producing the oftenfible phenomena of local 
 motion ; but it feems to be merely aji abufe of lan- 
 guage, and a very frivolous abufe. This elemental 
 mind is known and charafterifed only by the effeft 
 which we afcribe to its attion ; that is, by the motions 
 or changes of motions. Uniform and unexcepted ex- 
 perience fhews us that thefe are regulated by laws as 
 precife as thofe of mathematical truth. We confider 
 nothing as more fixed and determined than the com- 
 mon laws of mechanifra. There is nothing here that 
 indicates any thing like fpontaneity, intention, pur- 
 pofe ; none of thole marks by which mind was firft 
 brought into view : but they are very like the effeils 
 which we produce by the exertions of our corporeal 
 forces ; and we have accordingly given the name force 
 to the caufes of motion. It is furely much more ap- 
 pofite than the name mind, and conveys with much 
 more readinefs and perfpicuity the very notions that we 
 wifli to convty. 
 
 We now wifh to know what reafon we have to think 
 that the continual action of fome caufe Is neceffary for 
 continuing matter in motion, or for thinking that reft 
 is its natural tfate. If we pretend to draw any argu- 
 ment from the nature of matter, that matter muft be 
 known, as far as is neceffary for being the foundation 
 of argument. Its very exiftence is known onlv from 
 oljfervation ; all our knowledge of it muft therefore be 
 derived from the lame fource. 
 
 If we take this way to come at the origin of this 
 opinion, we lliall find that experience gives us no au- 
 thority for faying that reft is the natural condition of 
 
 DYNAMICS. 507 
 
 matter. We cannot fay that we !nv« ever feen a body Fi'd i-<w 
 
 IJ. 
 
 at rell ; this is evident to every pcrfan who allows the ^*^ M'"o"- 
 validity of the Newtonian phllofopliy, and the truth of 
 the Copernican f)ftem of the fun and planets; all the 
 parts of this fyftem, are in motion. Nay, it appears 
 from many obfervations, that the fun, with his attend- 
 ing planets, is carried in a certain direftion, with a ve- 
 locity which is very great. We have no unqueftionable 
 autliority for faying that any one of the ftars is ab/o- 
 lutely fixed : but we are certain that many of them are 
 in motion. Reft is therefore fo rare a condition of bo- 
 dy, that we cannot fay, from any experience, that it is 
 its natural ftate. 
 
 It is eafy, however, to fee, that it is from obferva- 
 tion that this opinion has been derived ; but the obfer- 
 vation has been limited and carelefs. Our experiments 
 in this iublunary world do indeed always require conti- 
 nued aftion of fome moving force to continue the mo- 
 tion ; and if this be not employed, we fee the motions 
 flacken every minute, and terminate in reft after no 
 long period. Our fiift notions of fublunary bodies are 
 indicated by their operation in cafes where we have feme 
 mtereft. Perpetually feeing our own exertions necellary, 
 we are led to'confider matter as fomething not only 
 naturally quiefcent and inert, but fluggilh, averfe from 
 motion, and pione to reft (we muft be pardoned thii 
 metaphorical language, becaufe we can find no other 
 term). What is expreffed by it, on this occaliou, is 
 precilely one of the erroneous or inadequate concep- 
 tions that are fuggefted to our thoughts by rtafon of 
 the poverty of language. We animate matter in or- 
 der to give it motion, and then we endow it with a fort 
 of moral charafter in order to explain the appearance 
 of thofe motions. 
 
 But more extended obfervation has made men gra- 
 dually defcrt their tiift opinions, and at laft allow that 
 matter has no peculiar aptitude to reft. All the retar- 
 dations that we nbferve have been difcovered, one after 
 another, to have a diftinft reference to fome external 
 circumftances. The diminution of motion is always 
 obferved to be accompanied by the removal of obfta- 
 cles, as when a ball moves through fand, or water, or 
 air ; or it is owing to oppofite motions which are de- 
 ftroyed ; or it is owing to roughnefs of the path, or to 
 friaion, &c. We find that the more we can keep 
 thole things oitt of the way, the lefs are the motion's 
 diminiftied. A pendulum will vibrate but a fliort while 
 in water; much longer in air; and in the cxhauucd re- 
 ceiver, it will vibrate a whole day. We know that we 
 , cannot remove all obftacles; but we are led by fuch ob- 
 fervations to conclude that, if they could he completely 
 removed, our motions would continue for ever. And 
 this conclufion is almoft demonftraled by the motions 
 of the heavenly bodies, to which we know of no ob- 
 ftacles, and which we really obferve to retain their mo- 
 tions for many thoufand years without the fmallcft fen- 
 fible diminution. 
 
 Another fet of philofophers maintain an opinion di- fnaftivit* 
 reftly oppofite to that of the inactivity of matter, and'-f m-vtci- 
 affert, that It is eftentially adive, and conluuially chan-'''^'.''^4 ''V 
 ging its ftate. Faint traces of this arc to be found j,, ^=''^'""' 
 the.writings of Plato, Ariftotle, and their .commenla- 
 tors. Mr Leibnitz is the peifon who has treated this 
 queftion moft fytlematically and fully. He fuppofcs .'t/ona*, 
 every pai'ticle of matter to have a principle of indivi- wl;ut. 
 duality, which he therefcre calls a 2vIonad. This mo- 
 ? S 2 iiad 
 
 %(,. 
 
 J^7
 
 5o8 
 
 This rpi- 
 nion ill 
 iouiidcd. 
 
 aiti^ caule. 
 
 D Y N A 
 
 "pirft Law nad has a fort oi ptrctpl'wn of its fituntion in the univerfe, 
 of Motion. gp(j pf its relation to every other part of this univerfe. 
 '"""'""' Laftlv, he fays that the monad afts on the material 
 particle, much in the fame way that the loul of man 
 atls on his body. It modifies the motion of the ma- 
 terial atom (in conformity, however, to unalterable 
 laws), producing all thofe modifications of motion that 
 we obferve. Matter therefore, or at Icall particles of 
 matter, are continually aftive, and continually changing 
 their fituation. 
 
 It is quite unnecetTary to enter on a formal confuta- 
 tion of Mr Leibnitz's fyfltm of monads, which differs 
 very httle from the fyllem of elemental minds, and is 
 equally whimfical and frivolous ; becaufe it ordy makes 
 the unlearned reader flare, without giving him any in- 
 formation. Should it even be granted, it would not, 
 any more than the aftion of animals, invalidate the ge- 
 neral propolition which we are endeavouring to eila- 
 blifli as the fundamental law of motion. Thole powers 
 of the monads, or of the elemental iiiinds, are the 
 caufes of all the changes of motion ; but the mere ma- 
 terial particle is fubjeft to the law, and requires the 
 exertion of the monad in order to exhibit a change of 
 18 motion. 
 .Some phi- A third feft of philofophers, at the head of which 
 lofophers ^^^ ^^^^ place. Sir Ifaac Newton, maintain the doftrine 
 kw of mo-«'"0""C«d in the propofition. But they differ much in 
 tlon from refpeft of the foundation on which it is built, 
 the want of Some alTert that its truth flows from the nature of 
 a dihrmi- jjjg thing. If a body be at reft, and you affert that it 
 will not remain at reft, it muft move in fome one direc- 
 tion. If it be in motion in any direftion, and with any 
 velocity, and do not continue its equable, reftilineal, 
 motion, it muft either be accelerated or retarded ; it 
 muft turn either to one fide, or to fome other fide. The 
 event, whatever It be, is individual and determinate; 
 but no caufe which can determine it is fuppofed : there- 
 fore the determination cannot take place, and no change 
 will happen in the condition of the body with rcfpett 
 to motion. It will continue at reft, or perfevere in its 
 reflilineal and equable motion. 
 
 But conilderable obj'ftions nay be made to this ar- 
 gument, oi fvjjincitt rciifon, as it is called. In the im- 
 raenfity and perfeft uniformity of fpace and time, there 
 is no, determining caufe why the vifible univerfe (hould 
 exift in the place in which we fee it rather than in an. 
 other, or at this time rather than at another. Nay, the 
 argument feems to beg the queftion. A caufe of de- 
 termination is required as effentially necefi"ary — a deter- 
 mination may be without a caufe, as well as a mution 
 without a caufe. 
 
 Other philofophers, who maintain this doiSrine, con- 
 fider it merely as an experimental truth ; and proofs of 
 its univerfality are innumerable. 
 
 When a ftone is thrown from the hand, we prefs it 
 forward while in the hand, and let it go when the hand 
 has acquired the greateft rapidity of motion that we 
 can give it. The ftone continues in that ftate of mo- 
 tion which it acquired gradually along with the hand. 
 We can throw a ftone much farther by means of a fling; 
 becaufe, by a very moderate motion of the hand, we 
 can whirl the ftone round till it acquire a very great 
 velocity, and then we let go one of the ftrings, and the 
 ftone efcapes, by ccnlinu'ing its rapid motion. We fee 
 it ftill more dlftinftly in (hooting an arrow from a bow. 
 The ftring preffcs hard on the notch of the arrow, and 
 
 49 
 
 Others de- 
 duce it 
 from ex- 
 pericnte. 
 
 M I C S. 
 
 it yields to this prefTuro and goes forward. The ftring Fi'ft I,.nw 
 
 alone would go fafter forward. It therefore continues '^ M. linn. 
 
 to prefs the arrow forward, and accelerates its motion. """^ 
 
 This goes on till the bow is as much unbent as the 
 
 ftring will allow. But the ftring is now a ftraight line. 
 
 It came into this pofition with an accelerated motion, 
 
 and it therefore goes a little beyond this pofition, but 
 
 with a retarded motion, being checked by the bow. 
 
 But there is nothing to check the arrow; therefore the 
 
 arrow quits the ftring, and flies away. 
 
 Thefe are fimple cafes of perfeverance in a ftate of 
 motion, where the procedure of nature is fo ealily tra- 
 ced that we peictlve it almuft intuitively. It is no lefi 
 clear in other phenomena which are more complicated ; 
 but it requires a little reflection to trace the procefs. 
 We have often feen an equeftrian ftiowman ride a 
 horfe at a gallop, ftanding on the faddle, and ftcpping 
 from it to the back of another horfe that gallops along- 
 fide at the fame rate ; and he does this feemlngly with 
 as much eafe as if the horfes were ftanding ftill. The 
 man h3s the fame velocity with the horfe that gallops 
 under him, and keeps this velocity while he fteps to the 
 back of the other. If that other were ftanding ftill, 
 the man would fly over his head. And if a man ftiould 
 ftep from the back of a horfe that is ftanding ftiil to the 
 back of another that gallops paft him, he would be left 
 behind. In the fame manner, a flack wire-dancer toffes 
 oranges from hand to hand while the wire is in full 
 fwing. The orange, fwiuging along with the hand, re- 
 tains the velocity ; and when in the air follows the 
 hand, and falls into it when it is in the oppofite extre- 
 mity of its fwing. A ball, dropped from the maft-head 
 of a flrip that is failing brifltly forward, falls at the foot 
 of the maft. It retains the motion which it had while 
 in the hand of the perfon who dropped it, and follov\s 
 the maft during the whole of its fall. 
 
 We alfo have familiar inftances of the perfeverance 
 of a body in a ftate of reft. When a vefTel filled with 
 water is drawn fuddenly along the floor, the water dafli- 
 es over the potterior fide of the veifel. It is left be- 
 hind. In the fame manner, when a coach or boat is 
 dragged forward, the perfons in it find themfelves ftrike 
 againft the hinder part of the carriage or boat. Pro- 
 perly fpeaking, it is the carriage that ftrikes on them. 
 In like manner, if we lay a card on the tip of the fin- 
 ger, and a piece of money on the card, we may nick 
 away the card, by hitting it neatly on its edge ; but 
 the piece of money will be left behind, lying on the tip 
 of the finger. A ball will go through a wall and fly 
 onward ; but the wall is left behind. Buildings are 
 thrown down by earthquakes ; fometimes by being tof- 
 fcd from their foundations, but more generally by the 
 ground on which they ftand being haftlly drawn fide- 
 wife from under tl.em, &c. .^ 
 
 But common experience feems infnfficient for efta-c'ommon 
 bliftiing this fundamental propofition t/f mechanical phl-exi-erienco 
 lofophy. We muft, on the faith of the Copernican iy- * 
 
 fteni, grant that we never faw a body at reft, or. in uni- 
 form reftilineal motion ; yet this feems abfolutely ue- 
 ceflary before we can fay that we have eftabliftied this 
 pnopofition experimentally. 
 
 What we imagine, in our experiments, to be putting 
 n body, formerly at reft, into lotion, is, in faft, only 
 changing a moft. rapid motion, not lefs, and probably 
 much greater, than 90,00c feet per fecond. Suppofe 
 a cannon pointed eaft, and the bullet difcharged at noon 
 
 day 
 
 iiifufKcienti
 
 D Y N A 
 
 Fiift la'' dny with ^o times greater velocity than we have ever 
 >f M. ti(n,[,^.p„ ^j,1j, ,„ j,j^.g it_ jt would appear to fct out with 
 ^""^ tliis unmeafurablc velocity to the eaftward ; to be gra- 
 
 dually retarded by tlie refiftance of the air, nid at lail 
 l.rought to reft by hittinir the ground. But, by reafon 
 of the earth's motion roiuid the fun, the fail is quite 
 the revcrfe. Immediately before the difcliarge, the ball 
 was moving to the well ward with the velocity of 90,000 
 feet per fecond nearly. By the explofion of the pow- 
 der, and its preflure on the ball, fume of this motion is 
 dellroved, and at the muzzle of the gun, the ball is 
 raovincj {lower, and the cannon Is hurried away from it 
 to the weftward. The air, which is alfo moving to the 
 . weftward f)O,0CO feet in a Iccond, gradually communi- 
 cates motion to the ball, ii> the fame nwnncr as a hur- 
 ricane vi'ould do. At lall (the ball dropping all the 
 while) fome part of the ground hits tlie ball, and car- 
 ries it along with it. 
 
 Other obfcrvations mud therefore be reforted to, in 
 order to obtain an experimental proof of this propofi- 
 tion. And fuch are to be found. Although we cannot 
 nieafure the abfolute motions of bodies, we can obferve 
 and mcafure accurately their relative motions, which are 
 the differences of their abfolute motions. Now, if we 
 can (hew experimentally, that bodies fliew equal ten- 
 dencies to refift the augmentation and the diminution of 
 their relative motions, they, i/fo faSo, fliew equal ten- 
 dencies to refiilthe augmentation or diminution of their 
 abfolute motions. Therefore let two bodies, A and B, 
 be put into fuch a fituation, that they cannot (by rea- 
 fon of their impenetrability, or the aftions of their mu- 
 tual powers) perfevere in their relative motions. The 
 change produced on A Is the efFcft and the mcafure of 
 B's tendency to perfevere in its former Rate ; and there- 
 fore the proportion of thefe changes will Ihew the pro- 
 portion of their tendencies to maintain their former 
 ftatcs. Therefore let the following experiment be made 
 at noon. 
 E»peri- Let A, apparently moving weftward three feet per 
 
 mems po- fecond, hit the equal body B apparently at reft. Sup- 
 per for the pofe^ ly/^ That A impels B forward, without any di- 
 " ° ^' minution of its own velocity. This refult would ftievv 
 that B manifcfts no tendenc)' to maintain its motion un- 
 changed, but that A retains its motion undiminifhed. 
 
 ja'/v, Suppofe that A ftops, and that B remains at 
 reft. This would ftiew that A does not refift a diminu- 
 tion of motion, but that B retains its motion unaug- 
 mented. 
 
 31/1}', Suppofe that both move weftward with the ve- 
 locity of one foot per fecond. The change on A is a 
 diminution of velocity, amounting to two feet per fe- 
 cond. Tliis is the effccl and the irieafure of B'.^ ten. 
 dency to maintain its velocity unaogmented. The change 
 on B is an augmentation of one foot per fecond made 
 on its velocity ; and this is the meafure of A's tenden- 
 cy to maintain its velocity uiidiminiflied. This tenden- 
 cy is but half of the former ; and this refult would 
 ftiew, that the refiilance to a diminution of velocity is 
 but half of the refiftance to augmentation. It is per- 
 haps but one quarter ; for the change on B has produ- 
 ced a double change on A. 
 
 4<M', Suppofe that both move weftward at the rate 
 of I i feet per fecond. It is evident that their tendencies 
 to maintain their ftates unchanged are now ecjual. 
 
 ^thly, Suppofe A = 2 B, and that both move, after 
 the coUiGou, two feet per fecondj B has received an 
 
 M I C S. 509 
 
 addition of two feet per ftcond to its former velocity. Fi''^ l->w 
 This is the ifRft and the mcafure of A's whole ten-"'' Motion. 
 dency to retain its motion undiminifhed. Half of this ' 
 change on B meafurcs the perfevcriiig tendency of the 
 halt of A; but A, which formerly moved with the ap- 
 parent or relative velocity three, now moves (by the 
 fuppolition) with the velocity two, having loft a velo- 
 city of one foot per fecond. Each half of A therefore 
 has loft this velocity, and the whole lofs of motion is 
 two. Now this is the meafure of B's tendency to 
 maintain its former ftate unaugmentcd; and this is the 
 fame with the meafure of A's tendency to maintain its 
 own former ftate undiminidied. The concUifion from 
 fuch a refult would therefore be, that bcdies have equal 
 tendencies to maintain their former ftates of motion 
 without augmentation and without diminution. 
 
 AV'hat is fuppoied in the 4//} and j//j cafes is really 
 the rcfidt ol all the experiments which have been tried ; 
 and fhis law regulates all the changes of motion which 
 are produced by the mutital aAIons of bodies in impul- 
 iions. This afltrtlon is true without exception or qua- 
 lification. Therefore it appears that bodies have no 
 preferable tendency to reft, and that no fait can be ad- 
 duced which lliould make us fuppofe that a motion once 
 begun fhould fi:lfer :;ny diminution without the aftion 
 of a changing caufe. 
 
 But we muft now obferve, that this way of eftablilh-Entcxpe- 
 ing the firft law of motion is very imperfect, and alto-f'^ncr is 
 gether unfit for rendering it the fundamental principle """/^"^P^"* 
 of a whole and extenfive feience. It is fubjeft to allf^o^ „f";f' 
 the inaccuracy that is to be found in our beft experi- axiom. 
 ments ; and it cannot be a])plled to cafes where fcru- 
 pulous accuracy is wanted, and wiicre no experiment: 
 can be made. 
 
 Let us therefore examine the propofition by means 
 of the general principles adojited in the article Philo- 
 sophy, F.ncycl. wliich contain the foundation of all 
 our knowledge of aftive nature. Thefe principles will, 
 we Imagine, give a decifion of this quellion th;it Is fpee- 
 dy and accurate, fhewing the propofition to be an axi- 
 om or intuitive confequence of the relations of thofe 
 ideas which we have of motion, and of the caufes of its 
 produftlon and changes. 
 
 It has been fully denionftratcd that the powers or Logics! 
 forces, of which we fpeak fo much, arc never the imme-P™"^' 
 diate objects of our perception. Their very exiftence, 
 their kind, and their degree, are Inftlntlive inferences 
 froiTi the motions which we obferve and dafs. It evi- 
 dently follows from this experimental and univerfal 
 truth, yl. That where no change of motion is obfer- 
 ved, no fuch inference Is made ; that is, no power is 
 Juppnji-d to act. But whenever any change of motion 
 is oblerved, the Inference Is made ; that is, a power or 
 force is fuppofed to have afted. 
 
 In the fame form of logical conclufion, we muft fay 
 that, 2dly, When no change of motion \i j'uppofid or 
 thought of, no force h fuppofed ; and that whenever we 
 fuppofe a change of motion, we, In fact, though not in 
 terms, fuppofe a changing force. And, on the other 
 hand, whenever we fuppofe the adion of a changing 
 force, we fuppofe the change of motion ; for the adbon 
 of this force, and the change of motion, is one and the 
 fame thing. We cannot think of the adtion without 
 thinking of the indication of that aftion ; that is, the 
 change of motion. — In the fame manner, when we do 
 not thlok of a changing force, or fuppofe tbat there is 
 
 no
 
 eio 
 
 DYNAMICS. 
 
 Kirft Law f(o niSlion of a cliangiiig force, we, in faft, though not 
 "''""• in terms, fiipporo that there is no iiidicttion of this 
 
 It is a lr.-.v 
 
 of luin^:tn 
 
 tlKUgtit, 
 
 •'PI' 
 clianging force ; that is, that there is no change. 
 
 Whenever, therefore, we luppofe that no mtclianical 
 force is aifting on a body, we, in fadl, fuppofr that the 
 body continues in its former condition with refpcft to 
 motion. It wc fnp])o(e that nothing accelerates, or re- 
 tards, or dcliedls tlie motion, wc fuppofe that it is not 
 accelerated, nor retarded, nor deflected. Hence fol- 
 lows tlie pi opofition in exprefs terms ~ ITe fti/>f>oJi that 
 tie loily cor.linues in Us former Jiute of reft or motion, un- 
 hfs ive fuppofe that it is changed by fame meckamcal 
 force. 
 
 Thiis it appears, that this propofition is not a matter 
 of expeiience or contingency, depending on the proper- 
 tics which it lias pleafed the Author of Nature to be- 
 llow on body : it is, to us, a neceffary truth. The 
 propofition dots not fo much exprefs any thing with re- 
 gard to body, as it does the operations of our mind 
 when contemplating body. It may perhaps be effential 
 to body to move in fome particular direftion. It may 
 be eflcntial to body to ftop as foon as the moving caule 
 lias ceafed to aft ; or it may be effential to body to di- 
 niinifh its mction gradually, and finally come to rell. 
 But this will not invalidate the truth of this propofi- 
 tion. Thefe circumftances in the nature of body, 
 which render thofe luodifications of motion effentially 
 neceffary, are the caufes of thofc modifications ; and, 
 in our ftudy of nature, they will be confideied by us as 
 changing forces, and will be known and called by that 
 name. And if we fhould ever fee a particle of matter 
 in filch a fituation that it is affefted by thofe effential 
 properties alone, we fhall, from obfervation of its mo- 
 tion, difcover what thofe effential properties are. 
 And almoft This law turns out at laft to be little more than a 
 an identical {gyfQijjgjj-gl propofition: But mechanical philofophy, 
 "' ' "'as we have defined it, requires no other fenfe of it : 
 for, even if we (hould fuppofe that body, of its own 
 nature, is capable of changing its ftate, this change 
 mufl be performed accordi»g to fome law which charac- 
 teriles the nature of body ; and the knowledge of the 
 law can be had in no other way than by obferving the 
 deviations from uniform reftilineal motion. It is there- 
 fore indifferent whetlier thofe changes are derived from 
 the nature of the thing, or from external caufes : for 
 in order to confider the various motions of bodies, we 
 inufl firfl confider this nature of matter as a mechanical 
 affeftion of matter, operatmg in every inflance ; and 
 thus we are brought back to the law enounced in this 
 propofition. This becomes more certain when we re- 
 fieft that the external caufes (fuch as gravity or mag- 
 rjCtifm), which are acknowledged to operate changes of 
 motion, are equally unknown to us with this eflential 
 original properly of matter, and are, like it, nothing 
 but inferences from the phenojnena. 
 
 The above very diffufe difeuffions may appear fuper- 
 fiuous to many readers, and even cumberfome ; but we 
 trull that the philofophical reader will excufe our anxie- 
 ty on this head, when he. reflefts on the complicated, 
 indiflinft, and inaccurate notions commonly had of the 
 fubjeft ; and more efpecially when he obferves, that of 
 thofe who maintain the truth of this fundamental pro- 
 pofition, as we have enounced it, many (and they too 
 of the firfl eminence), rejeft it in faft, by combining it 
 with other opinions which are inconfiflent with it, nay, 
 -^vhich contradict it; in exprefs terms. We may even 
 
 include Sir Ifaac Newton in the fiumbcr of thofe who Firft Lfw 
 have at leafl intKuiuced modes of exprcifion which mif.of ^"''o"- 
 lead the minds of incautious perions, and fuggefl iiiade- * 
 quale notions, incompatible with the pure do(^trine of 
 the propofition. Although, in words, they d if claim 
 the dodtrine that rell is the natural ftate of body, and 
 that force is uccefl'ary for the continuation of its motion, 
 yet in words they (and moll of them in thought) like- 
 wife abet that dodrine : for they fay, that there nfides 
 in a moving body a power or force, by which it perfe- 
 veres in its motion. They call it the vis in sir A, the 
 
 INHERENT FORCE OF A MOVING BODY. This is furelv 
 
 giving up the quellion : for if the motion is fuppofej 
 to be continued in confequence of a force, that force is 
 
 fuppofed to be exerted ; and it is fuppofcd, that if it 
 were not exerted, the motion would ceafc ; and there- 
 fore the propofition mull be falfe. Indeed it is forae- 
 timcs exprelfed fo as feemingly to ward off this objec- 
 tion. It is faid that the body continues in uniform rec- 
 tilineal motion, unlefs afl'efted by fome external caufe. 
 But this way of fpeaking obliges us, at firfl felting out 
 in natural philofophy, to aflert that gravity, magnetifm, 
 eleftricity, and a thoufand other mechanical powers, 
 arc external to the matter which they put in motion. 
 This is quite improper : it is the bufinefs of philofc 
 phy to difcover whether they be external or not ; and 
 if we affert that they are, we have no principles of ar- 
 gumentation with thofe who deny it. It is this one 
 thing that has filled the ftudy of nature with all the jargon 
 of sthers and other invifible intangible fluids, which has 
 difgraced philofophy, and greatly retarded ils progrefs, 32 
 We mull oblerve, that the terms vis infita, \aherenX. Fi, hfiia, 
 
 forte, are very improper. There is no difpute among ''''>"='^'"' 
 
 philofophers in calling every thinp a force that pro-- '"'^'^° 
 J t_ r • 1 ■ ■ r ■ 1 X- improper 
 
 duces a change or motion, and in interring the action terms in 
 
 of fuch a force whenever we obferve a change of mo- th-ir ufual 
 tion. It is furely incongruous to give the fame name ''."^^P"" 
 to what has not this quality of producing a change, or"""' 
 to infer (or rather to fuppofe) the energy of a force 
 when no change of motion is obferved. This is one 
 among many inllances of the danger of millake when 
 we indulge in analogical difcuflions. All our language, 
 at leafl, on this fubjeft is analogous. I feel, that in 
 order to oppofe animal force, I mufl exert force. But 
 I mull exert force in order to oppofe a body in motion : 
 Therefore I imagine that the moving body poffeffes 
 force. A bent fpring will drive a body forward by un- 
 bending : Therefore I fay that the fpring exerts force. 
 A moving body impels the body which it hits ; There- 
 fore I fay, that the imptlling body poflTefles and exerts 
 force. I imagine farther, that it polfeffes force only 
 by being in motion, or becaufe it is in motion ; becaufe 
 I do not find that a quielccnt body will put another 
 into motion by touching it. But we fliall fuon fin<l this 
 to be falfe in many, if not in all cafes, and that the com- 
 munication of motion depends on lire mere vicinity, and 
 not on the motion of the impelling body; yet we afcribe 
 the exertion of the vis infita to the circuniflance of the 
 continued motion. We therefore conceive the force as 
 arifing from, or as confiiling in, the impelling body's 
 being in motion ; and, with a very obfcure and indif- 
 tinct conception of the whole matter, we call it the 
 force by ivhich the body prcferves itftlf in motion. Thus, 
 taking it for granted that a force refides in the body, 
 and being obliged to give it fome office, this is the on- 
 ly one that we can think of. 
 
 Bu4
 
 33 . 
 
 Motion IS 
 nui the 
 continual 
 
 D Y N A 
 
 Firil Liw But ph!Iofop)iers imagine tint they perceive the ne- 
 of Moion ceffity ot the exertion of a force in order to the conti- 
 " ' ""■ 'miation of a motion. Motion (fay tliey) is a conti- 
 nued adion ; the body is every inftant in a new fitna- 
 tion ; there is the continual production of an cfFedt, 
 tlierefoie the continual attion of a caufe. 
 
 But this is a very inaccurate way of thinking. We 
 have a diftindl conception of ir.otion ; and we conceive 
 that there is fuch a thing as a moving caufe, which we 
 diftinguilh from all other caufes by the name_/brfc. It 
 produces motion. If it does this, it produces the cha- 
 rader of motion, which is a continual change of place. 
 Motion is not action, but the effeifl of an aftion ; and 
 pro u tion ^- jC^Jqj, Jj ^. incomplete in the inftant immediately 
 lucceedmg the begmnuig or the motion as it is a mi- 
 nute after. The fubfequent change of place is the coii- 
 tinuation of an eifeft already produced. Tlie immedi- 
 ate effeft of the moving force is a determina rios, by 
 which, if not hindered, the body would go on for ever 
 from place to place. It is in this determination only 
 that the ftatc or condition of the body can differ from 
 a ftate of reft ; for in any inftant, the body does not 
 ilefcribe any fpace, but has a determination, by which 
 it will defcribe a certain fpace uniformly in a certain 
 time. Motion is a condition, a itate, or mode of ex- 
 illence, and no more requires the continued agency of 
 the moving caufe than ycllownefs or roundnels does. 
 It requires fome chemical agency to change ihe yellow- 
 nefs to greennefs ; and it requires a mechanical caufe 
 or a force to change this motion into reft. When we 
 fee a nwving body ftop ftiort in an inllant, or be gra- 
 dually, but quickly, brought to reft, we never fail to 
 fpecnlate about a caufe of this ceflatiou or retardation. 
 The cafe is no way different in i.tfclf although the re- 
 tardation ihould be extremely flow. We fhould always 
 attribute it to a caufe. It requires a caufe to put a 
 body out of motion as much as to put it into motion. 
 This caufe, if not external, muft be found in the body 
 itlelf ; and it muft; have a felf-determiiiing power, and 
 may as well be able to put itfclf into motion as out of 
 it. 
 
 If this reafoning be not admitted, we do not fee bow 
 any effeft can be produced by any caufe. Every effedl 
 fuppofes fomething done ; and any thing done implies 
 that the thing done may remain till it be undone by 
 fome other caufe. Without this, it would have no ex- 
 jftence. If a moving caufe did not produce continued 
 motion by its inilantaneous aftion, it could not pro- 
 duce it by any continuance of that action ; becaufe in 
 no inftant of that aftion does it produce continued 
 motion. 
 
 Wt muft therefore give up the opinion, that there 
 rciides in a moving body a force by luhich it is kept in 
 motion ; and we inuft find fome other way of explaining 
 that remarkable difference between a moving body and 
 a body at reft, by which the firil caufes other bodies 
 to move by hitting them, wl-.lle the other does not do 
 this by merely touching them. Wc ftiall fee, with 
 the clcarell evidence, that motion is neceftary in the im- 
 pelling body, in order that it may permit the forces in- 
 herent in one or both bodies to continue this preffure 
 long enough for producing a fenfible or conliderable 
 motion. But thele moving forces are inherent in bo- 
 dies, whether they are in motion or at reft. 
 
 The foregoing obfervations fhew us the impropriety 
 cf the phrafe communicatior. of motion. By thus refleiSt- 
 
 M I C S. • 511 
 
 ing on the notions that are involved in the general con- F'rl Law 
 ception of one body being made to move by the Jm, of Moiuin. 
 pulfe of another, we perceive that there is nothing in- ~~' 
 dividual transferred from the one body to the other. Con:muni. 
 The determination to motion, indivd, exifted only In cation of 
 the impelling body before colliliou; whereas, afterwards, "*°'''"' '» 
 both bodies are fo conditioned or determined. But wCp"/"j|'/jjf' 
 can form no notion of the thing transferred. Witli th« 
 fame mctaphylica^ impropriety, we fpeak of the com- 
 munication of joy, of fever. 
 
 Kepler introduced a term inertia, vis inf.rti;e,so is"> 
 into mechanical philufophy ; and it is now in conftantin«K«. 
 ufe. But writers are very carelefs and vague in the no. 
 tlons which tiiey affix to thefe terms. Kepler and New- 
 ton fcem generally to employ it for exprelfirg the fad, 
 the perfeverance of the body in its prefent ftate of mo- 
 tion or reft: but they alio frequently exprefs by it 
 fomething like an indifference to motion or reft, man'i- 
 fejled Ly its requiring the fame quantity of force to make 
 an augmentation of its motion as to make an equal diminu- 
 tion oj it. The popular notion is like that which wc 
 have of aftual reliftance ; and it always implies the no- 
 tion of force exerted by the refifting body. Wc fup- 
 pofe this to be the exertion of the vis iiijita, or the irJie- 
 rent force of a body in motion. But we have the fame 
 notion of refillance from a body at reft which we fet 
 in motion. Now furely it is in direft contradidion to 
 the common ule of the word force, when we fuppofe re- 
 liftance from a body at reft ; yet vis inertia: is a vtxy 
 common exprelTion. Nor is it more abfurd (and it 14 
 vei7 abfurd) to fay, that a body maintains its ftate 
 of reft by the exertion of a -vis inertia, than to fay, 
 that it maintains its ftate of motion by the exertion of 
 an inherent force. Wt ftiould avoid all fuch metapho- 
 rical expreflions as refiflance, indifference, fluggifincfs, or 
 pronenefs to reft (which fome exprefs by inertia)i b.-- 
 caufc they feldom fail to make us indulge in metaplii. 
 rical notions, and thus lead us to mifconceive the modus 
 operandi, or procedure of nature. 
 
 There is no rcjljlance whatever ohferved in thefe phe- 
 nomena ; for the force employed always produces it*. 
 complete effed. When I throw down a man, ami find 
 that I have employed no more force than was fufficient 
 to throw down a fimilar and equal mafs of dead matter, 
 I know by this th it he has not refilled ; but I con- 
 clude that -he has refifted, if I have been obliged to em- 
 ploy much mure force. There is therefore no refill- 
 ance, properly fo c;dled, when the exerted force is oh- 
 ferved to produce its full elfed. To fay that there ;> 
 refiftance, is therefore a real mifconception of the way 
 in which meciianical forces have operated in tlie colli, 
 lion of bodies. There is no more reiiftance in thefe 
 cafes than in any other natural changes of condition. 
 We are guilty, however, of the fame impropriety of 
 language in other cafes, where the caufe of it is more 
 evident. We fay that colours in grain njifl the adion 
 of foap and of the fun, but that PrulTnn bine does not. 
 We all perceive, that in this exprediun tlie v/oid re- 
 fiftance is entirely figurative : and we fliould f;iy that 
 Pruflian blue refjls foap, if we are right in faying tli.it 
 a body refifts any force employed to change its fhte of 
 motion ; for foap mufl be employed to difciiarg-e or 
 change the culour ; and // dues change it. Force mufl; 
 be employed to change a motion ; and it does change it. 
 The impropriety, both of thought and langiuige, 'n plain 
 in the oi;c care, ar.d it is no kfs real in ihc other. Both.
 
 512 
 
 DYNAMICS. 
 
 loi'ce. 
 
 Seco'i'iLaw of the terms, inherent farc» aiul imrtia, may be ufed changes, and that thefe proportione arc the fame j and SecnndLn: 
 
 of Motion. ^j^jj fafety for abbreviating language, if wc be careful from having obferved that this has obtained through °/ M utimi 
 
 ^" * ' ' ' to employ them only for exprefiing, either the Jimpk fa& the whole extent of our lludy of nature. This would * " 
 
 of perfevcrin" in the former Jlats, or the necejjity of em- indeed eftabhlli ic as a phylxal law, an univerlal taft ; 
 
 ployin" a certain deiirminette force, in order to change that and it is, in faft, fo eilablilhcd. But this does not efta- 
 
 36 fiate, and if we avoid all thought of refjlance. blilh it as a law of motion, according to our definition 
 
 Deviations I'lom the whole of this difcuflion, we learn, that the of that term ; as a law of human thought, the rcfult of 
 
 from uni- J^vjations from uniform motions are the indications of the relations of our ideas, as an intuitive truth. Tlie 
 
 Itieal'^mn-' the txiltence and agency of mechanical forces, and that injudicious attempts df philolophers to prove it as a 
 
 tion arc the they are the only indications. The indication is very matter of obfervatlon, have otcalinned the only difpute 
 
 only indica-jjfiiple, mere change of place ; it can therefore indicate that has arileii ia mechanical philofophy. It is well 
 
 nothing but what is very iimple, the fomething com- known that a bullet, moving vith double velocity, pe- 
 
 petent to the produftion of the very motion that we netrates four times as far. Many other fimilar latls 
 
 ohferve. And when two changes of motitm are pre- corroborate this: and the philofophers obferve, that 
 
 clfely fimilar, they indicate the fame thing. Suppofe a four times the foree has been expended to generate this 
 
 mariner's compafs on the table, and that by a fmall tap double velocity in the bullet ; it requires four times as 
 
 with my finger I caufe the needle to turn off from its qui- much powder. Tn all the examples of this kind, it would 
 
 efcent pofition 10 degrees. I can do the fame thing by feem that the ratio of the forces employed has been 
 
 bringing a magnet near it; or by bringing an eletlrified very accurately afcertained ; yet this is the invariable 
 
 body near it ; or by the unbending of a fine fpring reftilt. Philofophers, therefore, have concluded, that 
 
 j)reii 
 
 othi 
 
 fame ; therefore the thing indicated is the fame, nume- is a ilrong confirnKition, to fee that the bodies in mO 
 ly, a certain intenfity and direftion of a moving power, tion feem to poflels forces in this very proportion, and 
 How it operates, or in what manner it exifts and exerts produce eftefts in this proportion ; penetrating four 
 itfelf in thefe inllances, outwardly fo difterent, is not times as deep when the velocity is only twice as great, 
 under confideration at prcfent. Impulfivenefs, intenfity, &c. 
 and dlretlion, are all the circumllances of refemblance 
 
 Qy near 11 . 01 uy uut uuui-nwiug v/i « *»in. i^i.i<>^ i^-iuil. i miui'JlJii'.is, i.ii»-i*_ikyn., naw ^-uuv-iiiuv-vi, i.iit*i- 
 
 Siliag it alide ; or by a puff of wind; or by ieveral moving forces are not proportional to the velocilieswhlch 
 [ler tnethods. In all thefe cafes, the indication is the they produce, but to the fquares of thofe velocities. It 
 
 by which the afleflions of matter are to be charafterifed ; 
 and it is to the difcovery and deternu'nation of thefe 
 alone that our attention is nOw to be diredled 
 directed in this refcarch by the 
 
 Second Law of Motion. 
 
 But if this be a juft eftimation, we cannot reconcile it 
 to the conceffioii of the fame philofophers, who grant 
 that the velocity is proportional to the force imjjvefled. 
 We are in the cafes where we have no previous obfervation of 
 the ratio of the forces, and of its equality to the ratio 
 of the velocities. This is the cafe with gravity, which 
 thefe philofophers always meafnre by its accelerating 
 Every change of motion is proportional to the force imprejfcd, power, or of the velocity which it generates in a given 
 and is made in the direction of that force. time. And this cannot Ijc ref\ifed by them ; for cafes 
 
 This law alfo may almoft be confidcred as an identl- occur, wlierc the force can be meafured, in the molt na- 
 cal propofition ; for it is equivalent to faying, that the tural manner, by the adual preffure which it exerts, 
 changing force is to be meafured by the change which Gravity is thus meafured by the preifiire which a Hone 
 it produces, and that the diredllon of this force is the exert,5 on its fupporls. A weight which at Quito will 
 diredxion of the change. Of this there can be no doubt, pull out the rod of a fpring lleciyard to the mark 312, 
 when we confider the force in no other fenfe than that will pull it to 313 at Spitzl)ergen. And it is a faft, 
 of the caufe of motion, paying no attention to the form that a body will fall 313 inches at Spitzbergen in the 
 or manner of its exertion. Thus, when a pellet of tow fame time that it falls 3 1 2 at Qjjito. Gravitation is 
 is (hot from a pop-gun by the expanfion of the air com- the caufe both of the preffure and the fall ; and it is a 
 preffed by the rammer, or where it is fliot from a toy matter of imexcepted obfervation, that they Irave al- 
 piftol by the unbending of the coiled wire, or vilieii it ways the fame ratio. The philofophers who have fo 
 is nicked away by the thumb like a marble — if, in all llrenuoully maintained the other meafure of forces, are 
 thele cafes. It moves ofi^ in the fame direftion, and with among the moft eminent of thofe who have examined 
 the fame velocity, we cannot confider or think of the the motions produced by gravity, magnctilm, eleftricity, 
 force, or at leall of its exertion, as any how different. &c.; and they never think of meafuring tl:ofe forces 
 Nay, when It is driven forward by the inftantaneous any other way than by the velocity. It is In tills way 
 percuifion of a fmart (Iroke, altliougli the manner of that the whole of the ccleftlal phenomena are explained 
 producing this effecl (If pofiiblc) is eltenllally dliferent in perfeft uniformity with obfervation, and that tlie 
 from what is conceived in tlie other cafes, we mull llill Newtonian philofophy is confidered as a demonltrative 
 think that the propelling force, confidered as a pro- fclence. 
 
 pelliiig force, is one and the fame. In (liort, this law There muil, therefore, be fome defeft in the principle 
 of motion, as thus expreffed by Sir Ifaac Newton, is on which the oiher mealurement of forces is built, or 
 equivalent to faying, " That we take the changes of in the method of applying it. Prefi'ure is undoubtedly 
 motion as the meafures of the changing forces, and the the immediate and natural mcaiure of force ; yet we 
 direftion of the change for the indication of the direc- know that four fprings, or a bow four times as ftrong, 
 tion of the forces :" For no rcfiefting perfon can pre- give only a double velocity to an arrow, 
 tend to fay, that it is a dcduftion from the acknowledged The truth of our law refts on this only, that we affume 
 principle, that effeds are proportional to their caufes. the changes of motion as the meafure of the changing 
 We do not affirm this law, from having obferved the forces ; or, at leaft, as the meafures of their exertions in 
 proportion of the forces and the proportion of the producing motion. In fad, they are the meafures only 
 
 of
 
 38 
 Ch»iij;e of 
 mntiun is, 
 tfclf, a mo 
 .ion* 
 
 5cfrn 1I.1W of a certain circumftance, in whicli the a£lions of very 
 rf M 'tion Jlffereiil natural powers may refemble each other ; name- 
 • Iv, the competency to produce motion. Tlicy do not, 
 
 perhaps, mcalure their competency to produce heat, or 
 even to hend fprings. We can furely confider this a- 
 part from all other circumllanccs ; and it is worthy of 
 feparate confidcration. Let iis fee what can be, an^ 
 what onglit to be, deduced from this way of treating 
 the fubjedl. 
 
 The motion of a body may certainly remain unchan- 
 ged. If the direftion and velocity remain the (anie, we 
 "perceive no circumftance in which its condition, with 
 refpeft to motion, differs. Its change of place or (itu- 
 ation can make no difference ; for this is implied in 
 the very circumftance of the body's being in motion. 
 
 But if either the velocity or direAion change, then 
 furely is its mechanical condition no longer the fame ; 
 a force has afted on it, either intrinfic or from without, 
 eithpr accelerating, or retarding, or deflecting it. Sup- 
 pofing the direftion to remain the fame, its difference of 
 condition can conlift in nothing but its difference of 
 velocity. This is the only circumftance in which its 
 Condition can differ, as it paffes through two different 
 points of its reftilineal path. It is this determination 
 by which the body will defcribe a certain determinate 
 fpace uniformly in a given time, which defines its con- 
 dition as a moving body : the changes of this determi- 
 nation are the meafures of their own caufts ; — and to 
 thofe caufes we have given the name force. Thofe 
 caufes may refide in other bodies, which may have other 
 properties, charadlerifed and meafured by other effc<Ss. 
 Preffure may be one of thofe properties, and may have 
 its oivn meafures ; thefe may, or may not, have the 
 fame proportion with that property which is the caufe of 
 a change of velocity : and therefore changes of velocity 
 may not be a meafure of preffure. This is aqneftion 
 of faft, and requires obfervation and experience ; but, 
 in the mean time, velocity, and the change of velocity, 
 is the meafure of moving force and of changing force. 
 When therefore the change of velocity is the fame, 
 whatever the previous velocity may be, the changing 
 force unift be conlidered as the fame : therefore, finally, 
 if the previous velocity is nothing, and confequently the 
 change on that body is the very velocity or motion that 
 it acquires, we muft f?y, that the force which produces 
 a certain change in the velocity of a moving body, is 
 the fame with the force which would impart to a body 
 at reft a velocity equal to this change or difference of 
 velocity produced on the body already in motion. 
 
 This manner of eftimating force is in perfeft confor- 
 mity to our mod familiar notions on thefe fubjefts. 
 We conceive the weight or downward preffure of a bo- 
 dy as the caufe of its motion downwards ; and we con- 
 ceive it as belonging to the body at all times, and in 
 all places, whetha' falling, or rifiug upwards, or defcri- 
 bing a parabola, or lying on a table ; and, accordingly, 
 we obfcrve, that in every ftate of motion it receives 
 equal changes of velocity in the fame, or an equal time, 
 and all in the direftion of its preffure. 
 
 All that we have now faid of a change of velocity 
 might be repeated of a change of direftion. It is fure- 
 ly poflible that the fame change of diretiion may be 
 made on any two motions. Let one of the motions be 
 confidered as growing continually flower, and termina- 
 ting in reft. In every inftant of this motion it is pof- 
 £uppi» Vol. I. Part XL 
 
 DYNAMICS. . i'.? 
 
 fible to make one and the fame change on it. The '«'""'";** 
 
 i-)- 
 
 AO- 
 
 fame change may therefore be made at the very inftant " '""",' 
 that the motion is at an end. In this cafe, the change 
 is the very motion which the body acquires from the 
 changing force. Therefore, in this cafe alfo, we mnft 
 fay, that a change of motion is itfelf a motion, and that 
 it is I lie motion which the force would produce in a bo- 
 dy (hat was previonfly at reft. , 
 
 The refult of thefe obfcrvatlons is evidently this. How afcer- 
 that we muft afcertain, in every inftance, what is the ""i<^^' >"'l 
 change of motion, and mark it by charafters that are""^'' 
 confpicuous and dlftinguifliing ; and this mark and mea- 
 fure of change muft be a motion : Then we mnft fay, 
 that the changing force is that which would produce 
 this motion in a body previonfly at reft. We muft fee 
 how this is manifcft, as a motion, in the difference be- 
 tween the former motion and the new motion ; and, on 
 the other hand, we mnft fee how_ the motion |)roduce- 
 able in a quiefccnt body may be fo combined with a 
 motion already exifting, as to exhibit a new motion, in 
 which the agency of the changing force may appear. 
 
 Suppofe a (hip at anchor in a llrcam; while one man 
 walks forward on the quarter-deck at the rate of two 
 miles per hour, another walks from ftem to ftcrn at tiie 
 fame rate, a third walks athwart ftiip, and a fourth 
 ftands ftiU. Let the ftiip be fuppofed to cut or part 
 her cable, and float down the ftream at the rate of three 
 miles per hour. We cannot conceive any difference in 
 the change made on each man's motion in abfoliite 
 fpace ; but their motions are now exceedingly different 
 from what they were : the firft man, whom we may 
 fuppofe to have been walking weftward, is now moving 
 eaftward one mile per hour; the fecond is moving eaft- 
 ward four miles per hour ; and the third is moving in 
 an oblique direction, about three points north or fouth 
 of due e.ift. All have fuffcred the lame change of con- 
 dition with the man who had been ftandmg ftiil. He 
 has now got a motion eaftward three miles per hour. 
 In this inftance, we fee very well the circumftance of 
 famenefs that obtains in the change of thele four con- 
 ditions. It is the motion of the Ibip, which is blended 
 with the other motions. But this circumftance is e- 
 qually prefent whenever the fame previous motions arc 
 changed into the fame new motions. We n:jft learn 
 to explfcate this ; which we fliall do, by cor.fidering the 
 manner in which the motion of the fiiip is blended with 
 each of the mens motions. .j 
 
 This kind of conihination has been called the CoMPO-Comp.>fi. 
 siTiON OF MOTION ; becaufe, in every point of the mo-""" of mo- 
 tion really purfucd, the two motions are to be found. '""* 
 
 The fnridaniental theorem on this lubjeft is this; — 
 Two uniform motions in the fides of a parallelogram 
 compoie an uniform motion in the diagonal. 
 
 Suppofe that a point A (fig. l.) defcribes AB uni- Plate XXI. . 
 formly in fome given time, while the line AB is car- 
 ried uniformly along AC in the fame time, keeping al- 
 ways parallel to its firll poiition ;^B. The point A, 
 by the combination of thele motions, will deicribe AD, 
 the diagonal of the parallelogram ABDC, uniformly 
 in the fame time. 
 
 For it is plain, that the velocities in AB and AC 
 are proportional to AB and AC, becauie they are uni- 
 formly dcfcribed in the fame time. When the point 
 has got to E, the middle of AB, the line AB has got 
 into the fituation GH, half way between AB and CD, 
 % T and
 
 5J4 
 
 Second!. aw 
 of Mr.tiiin. 
 
 DYNAMICS. 
 
 43 
 Its mark 
 and mea- 
 lure. 
 
 44 
 Changing 
 force. 
 
 It» effefl. 
 
 and the point E Is in the place e, the niiJdle of GH. 
 Draw Ef L parallel to AC. It is plain that the pa- 
 rallelograms ABDC and AE e G are fimilar ; becaufe 
 AE and AG are the halves of AB and AC, and the 
 angle at A is common to both. Therefore, by a pro- 
 pofition in the El'-mciits, they are about the fdnie dia- 
 gonal, and the point e :s in the diagonal of AD. In 
 like manner, it may be fliewn, that when A has de- 
 fcribed AF, Jths of AB, the line AB will be in the 
 fituation IK, fo that AI is Jths of AC, and the point 
 /', in which A is now found, is in the diagonal AD. 
 It will be the fame in whatever point of AB the de- 
 fcribing point A be fuppofid to he found. The line 
 AB will be on a fimilar point of A.C, and the defcri- 
 bing point will be in the diagonal AD. 
 
 Moreover, the motion in AD is uniform : for A <■ is 
 defcribed in the time of defcribing AE ; ,that is, in 
 half the time of defcribing AB, or in half the time 
 of defcribing AD. In like manner, A/ is defcribed 
 in |ths of the time of defcribing AD, Sic. &c. 
 
 Laftly, the velocity in the diagonal AD is to the 
 velocity in either of the fides as AD is to that fide. This 
 is evident, becaufe they are uniformly defcribed in the 
 fame time. 
 
 This is juftly called a compnfu'wn of the moticns .'\B 
 and AC, as will appear by confidering it in the follow. 
 ing manner : Let the lines AB, AC be conceived as 
 tvpo material lines like wires. Let AB move uniformly 
 from the fitnation AB into the fituation CD, while 
 AC moves uniformly into the fituation BD. It is plain 
 that their interfeftion will always be found on AD. 
 The point e, for example, is a point common to both 
 lines. Confidered as a point of EL, it is then mo- 
 ving in the direftion f H or AB ; and, confidered 
 as a point of GH, it is moving in the direftion e L. 
 Both of thefe motions are therefore blended in the mo- 
 tion of the interfeftion along AD. We can conceive 
 a fmall ring at e, embracing loofely both of the wires. 
 This material ring will move in the diagonal, and 'will 
 really partake of both motions. 
 
 Thus we fee how the motion of the (hip is aftually 
 blended with the motions of the three men ; and the 
 circumftance of famenefs which is to be found in the 
 four changes of motion is this motion of the (hip, or 
 of the man who was (landing ftill. By compofition 
 ■with each of the three former motions, it produces each 
 ©f the three new motions. Now, when each of two 
 primitive motions is the fame, and each of the new mo- 
 tions is the fame, the change is furely the fame. If 
 one of the changes has been brought about by the ac- 
 tual compofition of motions, we know precifely wlr.it 
 that change is ; and this informs us what the other is, in 
 whatever way it was produced. Hence we infer, that, 
 
 When a motion is any how changed, the change is that 
 motion which, iL'hm compounded with the former motion, 
 will produce the new motion. Now, becaufe we alTunie 
 the change as the meafure and charatteriftic of the 
 changing force, we muft do fo in the prefent inftance j 
 and we muil fay, 
 
 That the changing force is that which will produce in 
 a quiefcent body the motion which, by compofition with the 
 former motion of a body, will produce the new motion. 
 
 And, on the other hand, 
 
 When the motion of a body is changed by the adion of 
 any force, the new mclioi* is that which is compounded of 
 
 the former motion, and of the motion which the force waM/rfSero»i![.aw' 
 
 produce in a quiefcent body. . liMoMon. 
 
 When a force changes the direftion of a motion, we p^n.fj: 
 fee that its direftion is tianfverfe in fome angle BAC •,/„,.!. 
 becaufe a diagonal AD always fuppofcs two lides. A» 
 we have didinguidied any change of direftion by the 
 term DtFLtcTioN, we may call the tranfverfe (oice a 
 
 DEFLtCTING FORCE. 
 
 In this way of ellimating a change of motion, all the 
 charafters of both motions are preferved, and it ex- 
 preffes every circumftance of the change; the mcie 
 change of direftion, or the angle BAD, is not enough, 
 becaufe the fame force will make different angles ot 
 defleftion, according to the velocity of the former mo- 
 tion, or according to its direftion : but in this ellima- 
 tion, the full effeft of the deflefting force is feen ; it is 
 feen as a motion ; for when half of the time is elapfcd,. 
 the body is at e iuftead of E ; when three- fourths are 
 elapfed, it is atyinftead of F ; and at the end of the time 
 it is at D inllead of B. In (liort, the body has mo- 
 ved unifcinily away from the points at which it would, 
 have arrived independent of the change ; and this mo- 
 lion has been in the fame direftion, and at the fame 
 rate, as if it had moved from A to C by the changing 
 force alone. Each force has produced its full efftit ; 
 for when the body is at D, it is as far from AC as it 
 the force AC had not afted on it ; and it is as far from 
 AB as it would have been by the aftion of AC alone. 
 
 For all thefe reafons, therefore, it is evident, that if 
 we are to abide by our meafure and charafter of force 
 as a mere producer of motion, we have felefted the 
 proper charafteriftic and meafure of a changing force : 
 and our defcriptions, in conformity to this fel;ftion, 
 mull: be agreeable to the phenomena of nature, and re- 
 tain the accuracy of geometrical procedure ; becaufe, 
 on the other liand, the refults which we deduce from 
 the fuppofed inlluence of thofe forces are formed in the 
 fame mould. It is not even requilite that the real 
 exertions of the natural forces, fuch as prefTure of va- 
 rious kinds, 5:c. (hall follow thefe rules ; for their de- 
 viations will be confidered as new forces, although they 
 are only indications of the differences of the real forces 
 from our hypothefis. We have obtained the precious 
 advantage of mathematical inveftigation, by which vi 
 can examine the law of exertion which charafteriles 
 every force in nature. 
 
 On thefe principles we eftablifii the following funda- 
 mental elementary propofition, of continual and indil? 
 penfable ufe in all mechanical inquiries, ^5 
 
 If a body or material particle be fuljeSled at the fame /;mf Fumlamen- 
 to the aHion of two moving forces, each of which would^^^^^°"^ 
 fcparately cavfe it to dtfcnbe the fide of a paraUelogram 
 iinforrnly in a given time, the body will dijcrde the dia- 
 gonal uniformh in the fame time. 
 
 For the body, whofe motion AB was changed into 
 AD, had gotten its motion by the aftion of fome 
 forte. It was moving along NAB; and, when it reach- 
 ed the point A, the force AC afted on it. The pri- 
 mitive motion is the fame, or the body is in the fame 
 condition in every inftant of the primitive motion. It. 
 may have acquired this motion when it was in N, or when 
 at O, or any other point of NA. In all thefe cafes, 
 if AC aft on it when it is in A, it will always defcribe 
 AD ; therefore it will defcribe AD when it acquires 
 the primitive motion alfo in A ; that is, if the two for- 
 ces
 
 DYNAMICS. 
 
 Compojitlon 
 tfjareest 
 
 4«. 
 
 Refolution 
 f>f fortes. 
 
 3;cnrc!I,a'rce8 ai£l on it at one and tin fame iiil\ant. Tlie dtmon- 
 ot M- 1 1011 jtiation may bt neatly expicflld thus : The change in- 
 ' iluced by cacli force on the motion produced by the 
 
 other, is the motion which it would produjc in the bo- 
 dy if previoufly at veil. Therefore the motion refult- 
 ing from joint action is the motion which is compoimd- 
 c'd oi thefe two motions ; or it is a motion in the dia- 
 gonal of the parallelogram, of which thefe motions are 
 the lldcs. 
 
 This is called the Composition of Forces. The 
 forces which produce the motions alonpj the fides of the 
 parallelogram are called the Simple Fokces, or the 
 CoNSTiTtJENT FoRCEs ; and the force which would 
 alone produce the motion along the diagonal is called 
 the Compound Force, the Ri;sui.ting Forci;, the 
 Eo^uivALtNT Force. 
 
 On the other hand, the force which produces a mo- 
 tion along any line whatever, may be conceived as rc- 
 fulting from the combined a(3iun ot two or more for- 
 ces. We may knoiu or obfcrve it to be fo ; as when «e 
 fee a lighter diagged along a canal by two horfcs, one 
 on e?ch fide. Each pulls the boat directly toward him- 
 felf in the direction of the track-rope ; the boat cannot 
 go both ways, and its real motion, whatever it is, re- 
 fults from this combined adion. This might be pro- 
 duced by a fingle force ; for example, if the lighter be 
 dragged along the canal by a rope from another lighter 
 which precedes it, being dragged by one horfe, aided by 
 the helm of the foremoft lighter. Here the real force is not 
 the refulting, or the compound, but the equivalent force. 
 This view of a motion, mechanically produced, is 
 called the Resolution of Forces. The force in 
 the diagonal is faid to be rtfohed into the two forces, 
 haing the direftions and velocities reprctented by the 
 fides- This praftice is of the moll cxteniive and niul- 
 tifareous ufe in all mechanical difquifitions. It may 
 fiequently be exceedingly difficult to manage the com- 
 plication of the many real forces which concur in pro- 
 ducing a phenomenon ; and by fubftituting others, 
 whofe combined eflTedts are equivalent, our invelligatlon 
 inav be much expedited. But more of this afterwards. 
 We muft carefully remember, that when the motion 
 AD is once begun, all compofition is at an end, and 
 the motion is a fimple motion. The two determina- 
 tions, by one of which the body would defcribe AB, 
 nnd by the other of which it would defcribe AC, no 
 longer co-exijl in the body. This was the cafe only in 
 the hiJJr.iit, in the very a6l of changing the motion AB 
 into the motion BD ; yet is the motion AD equiv.ilent 
 to a motion which is produced by the aSual compofttui 
 of two motions AB and AC ; in which cafe the t«o 
 motions co-exift in every point of AD. 
 
 Accordingly this is the way in which the compofi- 
 tion of forces is ufually illuftrated, and thought to be 
 demonftrated. A man is fuppofed (for inllance) to 
 walk uniformly from A to C on a flieet of ice, while 
 the ice is carried uniformly along AB by the ftrcam. 
 The man's real motion is undoubtedly along AD ; but 
 this is by no means a demonftration that the inftanta- 
 Tieous or fhort-lived aftion of two forces would pro- 
 duce that motion ; the man muft continue to exert 
 force in order to walk, and the ice is dragged along by 
 the ftream. Some indeed exprefs this proof in another 
 way, faying, let a body defcribe AB, while the fpace 
 in which this motion is performed is carried along AC. 
 
 S'^S 
 
 47 
 
 TJfuai de- 
 moiiftra. 
 tion incon 
 cluCve. . 
 
 The ice may be carried along, and may, by friAio;i, or ^•■<^"ndLsw 
 otherwife, drag" the man along with it ; but a fpace "' ''^'°''°"; 
 cannot be removed from one place to another, nor, if ' 
 it could, would it take the man with it. Should a 
 ftiip dart fuddenly forward while a man is walking 
 ucrofs the deck, he would be left behind, and fall to- 
 ward the Hem, We mui\ fupl>ifi a tranfverfe force, 
 and we wuil /til>j>o/e the compof.tion of this force «ith- 
 out proof. This is no demonHratioii. 
 
 We ai'prehciid that the demoiiilrdtion given above 
 of this fundamental propufition is unexce])lionablc, 
 when the terms force and dcfitdi'on arc ufcd in the ab- 
 ftrad fenfe which we have affixed to them j and we 
 ho[>e, by thefe means, to maintain the rigour of mathe- 
 matical difculfiou in all our future difquilitioiis on thefe 
 fubjcAs. The only circunnlance in it wliich can be 
 the fubjccl of difcuflion is, whether we have fdeded 
 the proper meafure and chnrafteriilic of a change of 
 motion — We never met with any objtdion to it. 
 
 But fome have fliU maintained, that it does not evi- objc«ions 
 dently appear, from thefe principles, that the motion tn tlic de- 
 which refults from the joint adion of two natural "."'"'^"" 
 powers, whofe known and mealurable intenfiti^-s I'ave """'"[['^jn 
 the fame proportions with AB and BC, and which alio not srily"to 
 exert themfelves in thofe direftions, will produce a mo- ireffurcj, 
 tion, having the direftion and proportion of AD. They 
 will not, if the velocities produced by thefe forces are 
 not ill the proportion of thofe intenfities, but in the 
 fubdupUcate ratio of them. Nay, they fay, that it 
 is not fo. If a body be impelled along A C by one 
 fpring, and along A B by two fprings- equally llrong, 
 it will not defcribe the diagonal of a parallelogram, of 
 which the fide AB is doniile the fide AC. Nay, they 
 add, that an indefinite number of examples can be gi- 
 ven where a body cJoes not defcribe the diagonal of the 
 parallelogram by the joint action of two forces, which, 
 fcparately, would caufe it to defcribe the fides. And, 
 lailly, they fay that, at any rate, it does not appear 
 evident to the mind, that two incitements to motion, ha- 
 ving the direftions and the fame proportion of intenii- 
 ty with that of the fides of a parallelogram, actually 
 generate a third, which is the immediate caufe of the 
 motion in the diagonal. An equivalent force is not the 
 fame with a refulting force. 
 
 Yet we fee numberlefs cafes of the compofition of 
 incitements to motion, and they feem as determinate, 
 and as fufeeptible of being combined by compofition, 
 as the things called moving forces, which are meaiured 
 by the velocities : we fee them actually fo combined in 
 a ihoufand inflances, as in the example already given 
 of a lighter dragged by two horfcs pulling in different 
 direAions. Nay, expei-imcnt (hews, that this compo- 
 fit ion follows precifely the fame rule as the compofition 
 of the forces which are mcufured by the velocities ; for 
 if the point A (fig. i .) be pulled by a thread, or pref- 
 fed by a fpring, in the diredion AB, and by another 
 in the direction AC, and if the prefluies are prooor- 
 tional to AB and AC, then it will be withheld from 
 moving, if it be pulled or preffed by a third force, act- 
 ing in the direftion A d, oppofite to AD, the prefTure 
 being alfo proportional to AD. This force, afting in 
 the diredion h.d, would certainly withftand an equal 
 force afting in the direftion AD ; therefore we mull 
 conclude, that the two preffures AB and AC really 
 generate a force AD. This uniform agreement llicws 
 3 T 2 , that 
 
 19.
 
 5i6 
 
 Stco-.idl.aw that the compcfition is dediiclb'e from fixed principles ; 
 of Mi>ti.;ii i^^ij jf ^jQ^g ^p( appear that it can be heW as dcinoii- 
 * rtrateil by the arguments employed in the cale ot mo- 
 
 tions. A demon Itration of the compofition of pref- 
 fures is dill wanted, in order to render mechanics a de- 
 monllrative fcience. 
 This com- Accordingly, philofophcrs of the firft eminence have 
 pofition is turned their attention to this problem. It is by no 
 ofmorcdif- miaiiseal'y; being fo nearly allied to firil principles, that 
 ligation "=^ mull be ditficiilt to hnd axioms of greater fimplicity 
 by which it inay be proved. 
 
 ' Mechanicians generally contented themfelves with 
 the folution given by Arirtotle ; but this is merely a 
 compolition of motions : indeed he does not give it tor 
 any tiling elie, and calls it " <rii.5tir.< t^v fu a.." 1 be lirit 
 writer who appears to have confidered it ns different 
 from the mere compofition of motions, was the celebra- 
 ted Dutch engineer Stevinus in his work en S'l^iccs ; 
 but his folution is obfcure. It was fufl'.cicnt, however^ 
 to co-.ivince Daniel Bernoulli of the neceility and the 
 diificuity of the problem. He has given the fijlir com- 
 plete demouftration of it in the firft volume of the Com- 
 ir.entai ies of the Imperial Academy of Sciences at St 
 Feterfburgh. It is extrennely ingenious ; but it is te- 
 dious and intricate, requiring a feries of 15 piopoli- 
 tions to demonltrate that two preffuies, having the di- 
 redtions and magnitudes of the fides of any parallelo- 
 gram, compofe a third, which has the direftion and 
 magnitude of its diiigonal. His firft propofitiou is, that 
 two equal prejfures, aSing at right angles, compofe a third, 
 in the direa'wn of the Juigonttl of a fquare, anil having to 
 tither of the other tiuo the proportion of the diagonal of a 
 fquare to its fides. 
 
 Mr D'Alembert has greatly fimplified and improved 
 this demonftration, by beginning with a cale that is felf- 
 evideuL ; namely, Jf three equal forces are inclined lo each 
 other in equal angles of I 20 degrees, any one of them -will 
 balance the combined adion of the other two. Surely ; 
 fur neither of them can prevail. Therefore t-wo equal 
 forces, inclined in an angle of 120 degrees, produce a 
 third, which has the direftion and proportion of the 
 diagonal of the rhombus ; for this is equal and oppo- 
 iite to one of the three above mentioned. He then de- 
 monftrates the fame thing of two equal forces inclined in 
 «ny angle ; and by a feries of eight propofitions more, 
 de'monftrates the general theorem. This difi'crtation is in 
 the Memoirs of the Academy at Paris for 1769. He 
 jm.proves it ftill farther in a fubfequent memoir. 
 
 Mr RIccati and Mr Fonfenex, in the Commentaries 
 of the Academy of Turin, have given analytical demon- 
 ftrations, which are alfo very ingenious and concife, but 
 require acquaintance with the higher mathematics. — 
 There is another very ingenious demonftration in the 
 Journal dcs Sga-vans for June 1764, but too obfcure 
 for an elementary propofition. It is fomewhat fimpli- 
 fied by Belidor in his Ingenieur' Frangois. Frilius, in 
 his Cofmographia, has given one, which is perhaps the 
 beft of all thofe that are eafily comprehended without 
 acquaintance with the higher mathematics : but we 
 imagine that, although no one can doubt of the conclu- 
 fion, it has not that intuitive evidence for every ftep of 
 ,0 the procefs that feems neceffary. 
 Ccirfffiihii We here offer another, compofed by blending toge- 
 •//"#'"■"■ ther the methods of Bernoulli and D'Alembert ; and 
 we imagine that no objeftion can be made to any ftep 
 
 DYNAMICS. 
 
 of it. We limit it entirely to prefTurcs, and do not atS«-!ndLsw 
 
 all confider nor employ the motions which they may be "' '^'°"°'>> 
 fuppuftd to produce. 
 
 (A) If two equal and oppofite preffures or incite- 
 ments to motion art at once 011 a material particle, it 
 fuffers no change ot motion ; tor it it yields in cither 
 dire6\ion by their joint adlion, one of the preffures pre- 
 vails, and they are not equal. 
 
 Equal and oppofite preffures are faid to balance 
 each other ; and fuch as balance muft be efteemed equal 
 and oppofite. 
 
 ( B) li a and i are two magnitudes of the fame kind, 
 proportional to the inLenfities ot two prefiurcs which aCt 
 in the fame direilion, then the magnitude <j -J- i will 
 meal'ure the intcnfity of the preflure, which is equiva- 
 lent, and may be called equal, to the combined elTort of 
 the other two ; for whe:i we try to form a notion of 
 prcffure as a meafurable magnitude, dilllnrt from mo- 
 tio.T or any other efledt of it, we find nothing that we 
 can rneafure it by but another prefFure. Nor have we 
 any notion of a double or triple prelFure different from 
 a preflure that is equivalent to the joint eflbrt of two 
 or three equal preflures. A preiiure a is accounted 
 triple of a preffure i, if it balances three preffures, each 
 equal to i, aiiling together. Therefore, in all propor- 
 tions which can be cxpreffed by numbers, we muft ac- 
 knowledge the legitimacy of this meafurement ; and it 
 would furely be affedtation to omit thofe which the ma- 
 thematicians call incomtncnfuralle. 
 
 In like manner, the magnitude <? — h muft be ac- 
 knowledged to rneafure that preflure which arifes from 
 the joint adtion of two preffures a and b adding in oppo- 
 fite diredtions, of which a is the greateft. 
 
 (C) Let ABCD and AbCd (fig. A) be two rhora- 
 bufes, which have the common diagonal AC. Let the 
 angles B A b, DA d, be bifcdled hj the ftraight lines 
 AL and AF. 
 
 If there be drawn from the points E and F the lines 
 EG, EH, Ft, Y h, making equal angles on each fide 
 of E A and FA, and if G^, H h be drawn, cutting the 
 diagonal AC in I and L : then AI -\- AL will be 
 greater or lets than AQ_^ the half of AC, according as 
 the angles GEH, gYh, are greater or lefs than GAH, 
 gAh. 
 
 Draw GH, g h, cutting AE, AF, in O and 0, and 
 draw O 0, cutting AC in K. 
 
 Becaufe the angles AEG and EAG are refpedtively 
 equal to AEH and EAH, and AE is common to 
 both triangles, the fides AG, GE are refpedtively equal 
 to AH, HE, and GH is perpendicular to AE, and is 
 bifedled in O ; for the fame reafons, ^/j is bifedled in 
 0. Therefore the lines G^, Oo, H/i, are parallel, and 
 IL is bifedled in K. Therefore AI -(- AL is equal to 
 twice AK. Moreover, if the angle GEH be greater 
 than GAH, AG is greater than EO, and AK is great- 
 er than Kt^ Therefore Al -}- AL is greater than * 
 AQj and it the angle GEH be lefs than GAH, A I 
 + AL is lefs than AQ_^ 
 
 (D) Two equal preffures, adting in the dirertions 
 AB and AC (fig. 2.), at right angles to each other, 
 compofe a preflure in the diredlion AD, which biledts 
 the right angle ; and its intenfity is to the intenfity of 
 each of the conftituent preflures as the diagonal of a 
 fquare to one of the fides. It is evident that the di- 
 redlion of the preflfure, generated by their joint adlion, 
 
 will
 
 DYNAMICS. 
 
 ;f:on-lr.tiw will biTcft the angle formed by their direflions; bicaiife 
 uf MiiJion. ^p real'on can be afligned for the direction inclining 
 ' more to one fide than to the other. 
 
 In tlie next place, fince a force in the direflion AD 
 does, in fad, avife from the joint adion of the equal 
 preflures AB and AC, the predure AB may be con- 
 ceived as ariling from the joint adion of two equal 
 forces fimilarly inclined and proportioned to it. Draw 
 E AF perpendicular to AD. One of thefe forces mull be 
 direded along AD, and the other along AE. In like 
 manner, the preffure AC may aiife from the jpint ac- 
 tion of a prcH'ine in the dircdion AD, and an equal 
 prefTure in the diredion AF. It is alfo plain, that the 
 prefiures in the diredions AE and AF, and the two 
 preDTures in the diredion AD, mult be all equal. And 
 alfo, any one of them mutt, have the fame proportion to 
 AB or to AC, that A B or AC has to the force in 
 the diredion ADy aiiling from their joint adion. 
 
 Therefore, if it be faid that AD does not ineafure 
 the prelTure ariling from the joint adion of AB and 
 
 AC, let At/, greater than AD, be its juit meafurc, 
 and make A^: AB = AB : A^ = AB :" A?. Then 
 A.g and A.e have the fame inchnation and proportion 
 to AB that AB and AC have to A d. \Vc determine, 
 in like manner, two forces A_/"and A^ as conllituents 
 of AC. 
 
 Now A (/ is equivalent to AB and AC, and AB is 
 equivalent to A f and A. g ; and AC is equivalent to- 
 Ay and A^. Therefore A J is equivalent to A e, 
 A/, Ag, and A ^. But (a) Ae and A/ ba- 
 lance each other, or annihilate each other's efFcd ; and 
 there remain only the two forces or preflures A^, A_^. 
 Therefore (b) their meafure is a magnitude equal to 
 twice A^. But if A J be greater than the diagonal 
 AD of the fquare, whofe fides are AB and AC ; then 
 A^ muft be kfs than A I, the fide of the fquare whofe 
 diagonal is AB. But twice A^g is lefs than AD, and 
 much lefs than A (/. Therefore the meafure of the 
 equivalent of AB and AC cannot be a line A </ great, 
 er than AD. In like manner, it cannot be a line A J' 
 that is lefs than AD. Therefore it muft be equal to 
 
 AD, and the propolition is denionftrated. 
 
 (E) Cor. Two equal forces AB, AC, a6ting at 
 right angles, will be balanced by a force AO,. equal 
 and oppofite to AD, the diagonal of the fquare whofe 
 fides are AB and AC ; for AO would balance AD, 
 which is the equivalent of AB and AC. 
 
 (F) Let AECF (lig. 3.) be a rhombus, the acute 
 angle of which EAF is half of a right angle. 'L'wo 
 equal prcfTures, which have the diredions and meafures 
 
 AE, AF, compole a prefTure, having the diredion and 
 meafure AC, which is the diagonal of the rhombus. 
 
 It is evident, in the firft place, that the compound 
 force has the diredion AC, which bifeds the angle 
 EAF. If AC be not its juft meafure, let it be AP 
 lefs than AC. Let ABCD be a fquare defcribcd on 
 the fame diagonal, and make AP : AQr= AE : AO, 
 = AF : A 0. Draw KOG, K og perpendicular to 
 - AE, AF; draw Gl^, OH 0, EG, EK, F^, FK, 
 PF, and PE. 
 
 The angles C.'^B and FAE are equal, each being 
 half of a right angle. Alfo the figures AEPF and 
 AGEK are fimilar, becaufe AP : AO - AE : AO. 
 Therefore FA : AP = KA : AE, and EA : AP = 
 GA : AE. Therefore, in the fame manner that the 
 
 forces AE, AF .ire afTirmed to compofe AP, the forces 
 AG and AK may compofe the force ..\.E, and the forces 
 Ag and AK may compofe the force AF. Therefore 
 (B) the force AP is equivalent to the four forces AG, 
 AK, Ag, AK. But (D) AG and A^ arc the fides, 
 ot a fquare, whofe diagoTial is equal to twice AI : 
 and the two forces AK, AK are equal to, or are rnca- 
 fnred by, twice AK. Therefore the four forces AG, 
 AK, A^, AK, are equivalent to 2 AI + 2 AK, = 
 4 AH. 
 
 But becaufe AP was fuppofed lefs than AC, tlic 
 angle FPE is greater than FAE, and GEK is gieater 
 th;ui GAK, AO is greater than OE, and AH is great- 
 er than HQ^ and 2 AH is greater than AQj and. 
 therefore ^pAH is greater than AC, and much gieater 
 than AP. Therefore AP is not the julb meafure of 
 the force compof'ed of AE and AF. 
 
 In like maimer, it is fliewn, that AE and AF do 
 not compole afoice whofe meafure is greater than AC. 
 It is therefore equal to AC ; and the propofition is de- 
 monftrated. 
 
 (G) By the fame procefs it may be demonflrated,' 
 that if BAD be half a right angle, and EAF be the 
 fourth of a right angle, two forces AE, AF will com- 
 pofe a force' meafured by AC. And the procefs may 
 be repeated fur a rhombus whofe acute angle is ^th, 
 T'o-th, &c. of a right angle ; that is, any portion of a 
 right angle that is produced by continual bifedion. 
 Two forces, forming the fides of fuch a rhombus-, com- 
 pofe a force meafured by the diagonal. 
 
 (H) Let ABCD, A i c d (fig. 4.) be two rhom- 
 bufes formed by two confecutive bii^edions of a riglii 
 angle. Let AECF be another rhombus, whole fides 
 AE and AF bifed the angles BA* and DA d: 
 The two forces AE, AF, compofe a force AC. 
 Bifed AE and AF in O and 0. Draw the perpen- 
 diculars GOH, ^0 A, and the lines Gl^r, OK 9, HL /■, 
 and the lines EG, EH, F^, F k. 
 
 It is evident, that AGEH and A^ F/i arc rhom. 
 bufes ; becaufe AO = OE, and A = F. It is alio 
 plain, that fince b A (/ is half of BAD, the angle GAII 
 is half of i A d. It is therefore formed by a continual 
 bifedion of a right angle. Therefore (G) the forces 
 AG, AH, compofe a force AE ; and A^, A />, com- 
 pofe the force AF. Thefefore the forces AG, AH, 
 A g. Ah, acting together, are equivalent to the forcci 
 AE, AF' ading together. But AG, A^ compofe 
 a force = 2 Al ; and the forces AH, A h compofe a 
 force =: 2 AL. Therefore llie four forces ading to- 
 gether are equivalent to 2 AI -f- 2 AL. or to a; AK. 
 But becaufe AO is i AE, and the lines G^, O 0, H h, 
 are evidently parallel, 4 AK is equal to 2 AQ, or to 
 AC ; and the propofition is demonlhTted. 
 
 (I) Cor. Let us now f'uppofe, that by continual bi- 
 fedion of a light angle we have obtained a very fiiiall 
 angle a of a rhombus ; and let us name tl-.e rhombus bv, 
 the multiple of a which forms its acute angle. 
 
 The propofition (G) is true of a, 2 a, 4 «, &c. The 
 propofition (H) is true of 3 a. In like ma;i! er, be- 
 caufe (G) is true of 4 « and 8 a, propofition (H) is 
 true oi 6 a ; and becaufe it is true of 4 a, 6 a, and 8 a, 
 it is true of 5 a and 7 a- And (o on continually till, 
 we have demonflrated it of every multiple of a that is 
 lefs than a right angle. 
 
 (K) Let RAS (fig. 5.) be perpendicular to AC,. 
 
 5^7 
 
 Secondl.aw 
 of Moiion.
 
 5i8 D Y N A 
 
 SecondLiWgnd ]et ABCD be a rhombiid, whofc acute angle BAD 
 
 of M . tion. jg ^yj^g multiple of 2 ^ tliat is lefs than a right angle. 
 
 Let A b c i/he anoiher rhtnnbus, whofe fides A i, A d 
 
 bifea the angles RAB, SAD. Then tlie forces A *, 
 
 A d compofe a force AC. 
 
 Draw t R, rt'S parallel to B A, DA. It is evident, that 
 AR ^ B and AS d D are rhombufes, wliofe acute angles 
 are multiples of a that are each lefs than a right angle. 
 Therefore ( I) the forces AR and AB compofe tlie force 
 A /', and AS, AD compofe A d ; but AR and AS 
 annihilate each other's efl'cil, and there remains oidy^he 
 forces AB, AD. Therefore A i and A d are equiva- 
 lent to AB and AD, which compofe the force AC; 
 and the propofition is demonftrated. 
 
 (L) Cor. Thus is the corrollary of laft propofition 
 extended to every rhombus, whofe angle at A is fome 
 multiple of a lefs than two right angles. And iince a 
 may be taken lefs than any angle that can be named, 
 the proportion may be conhdeved as demonllrated of 
 every rhombus : and we may fay, 
 
 (M) 7''UJo equal forces, inclined to each other in any 
 angle, compofe a force ivhich is meafured by the diagonal 
 of the rhombus, luhofe fides are the meafures of the conjli- 
 iuent forces . 
 
 (N) Two forces AB. AC (fig. 6), having the di- 
 reftion and proportion of the fides of a rectangle, com- 
 pofe a force AD, having the direftion and propouion 
 of the diagonal. 
 
 Draw the other diagonal CB, End draw EAF pa- 
 rallel to it ; draw BE, CF parallel to DA. 
 
 AEBG is a rliomhus ; and therefore the forces AE 
 and AG compofe the force A B. AFCG is alio a rhora- 
 bus, and the force AC is eciuivalent to A F and AG. 
 Therefore the forces AB and AC, afting togetlier, are 
 equivalent to the forces AE, AF, AG, and AG ac- 
 ting together, or to AE, AF, and AD acting toge- 
 ther : But AE and AF annihilate each other's aCllon, 
 being oppofite and equal (for each is equal to the half 
 of BC). Therefore AB and AC ading together, are 
 equivalent to AD, or compofe the force AD. 
 
 (O) Two forces, which have the direction and pro- 
 portions of AB, AC (fig. 7.) the fides of any paralle- 
 logram, compofe a force, liaving the direction and pro- 
 ■portion of the diagonal AD. 
 
 Draw AF perpendicular to BD, and EG and DE 
 perpendicular to AC. 
 
 Then AFBG is a reftangle, as is alfo AFDE ; and 
 AG is equal to CE. Therefore (N) AB is equivalent 
 to AF and AG. Therefore AB and AC adting to- 
 gether, are equivalent to A F, AG, and AC acting to- 
 gether; that is, to AF and AE aetiiig together ; that 
 is (N) to AD; or the foices AB and AC compofe 
 the force AD. 
 * Hence arifes the moft general propofition. 
 
 If a material particle be urged at once by Inji'O preffures 
 or incitements to motion, ivhofe intenfiiies are proportional 
 incitements'" the Jides of any parallelogram, and ivhich a8 in the di- 
 to motion. reBions of thofe Jides, it is oJfeSed in the fame manner as 
 if it ivert n3ed on by a Jingle force, ivhofe intenfity is mea- 
 fured by the diagonal of the parallelogram, and ivhich alls 
 in its diredion : Or, two prejfurcs, having the direSion 
 and proportion of the Jides oj a parallelogram, generate a 
 prejfure, having the direSion and proportion of the diagonal. 
 
 Thus have we endeavoured to demonilrate from ab- 
 ftradl principles the perfeft firailarity of the compofition 
 
 .St 
 Compofi. 
 
 tion of all 
 
 M I C S. 
 
 of prtlTures, and the compofition offerees r.^fafured by Sccondl.aw, 
 the motions which they product. We cannot help be- ° ^' "'i"n. 
 ing oi tlic opinion, tliat a (epurate denionllration is in- 
 difpenfably necelfary. What may be fairly deduced Seeming 
 from the one cafe, cannot always be aj)plied to the diiJcieiics 
 other. No compofition of preffures can explain the"' ' ."^'""" 
 change produced by a defltfting force on a motion al-moti'mand 
 ready exilting ; for the changi;ig prefTure is the only of prelTure 
 one that exills, and there is none to be compounded 'lifappear 
 with it. And, on the other hand, our notions and ob-"', " '^"*- 
 iervations 01 the CDnipolition or motions will not explain [j^jp^j 
 the compofition of preffures, unlefs we take it for grant- 
 ed that the preffures are proportional to the velocities ; 
 but this is perhajis a gratuitous affumption. At any 
 rate, it is not an intuitive propofition; and \n e have 
 mentioned fome fa-Ss where it leems that they do not 
 follow the fame proportion. The pieffure of four equal 
 fprings produces only a double velocity. It would ap- 
 pear, therefore, that there are circumiiances which ob- 
 lige us to fay, that the exertion of prefTure, as a caufe of 
 motion, is not (always at kail) propoitional to tlie real 
 mcafurahle prefTure, We are therefore anxious to dif- 
 cover in wliat the difference confills ; and in the mean 
 time muft allow, that tlie prefTure exerted on a body at 
 refl. is different from its exertion in producing motion. 
 We cannot indeed flate any immediate comparifon be- 
 tween prefTure and motion, nor have we any clear con» 
 ception of the conneCtiini between them. It is only by 
 our fenfationsof touch that we have any notion of prcl- 
 fure, and it is experience that teaches us that it always 
 accompanies every caufe of motion. We can, however, 
 obferve the proportions of prelTures, and compare tliem 
 with the proportions of motion. We very often ob- 
 ferve them difl'erent ; and therefore it was imlifpeiifably 
 neceflary to invefligate the laws of combined prefiure 
 as v/e did the laws of combined motion in confequeiice 
 of prefTure. Yet we fhould err, if we haffily ailerted 
 that preflures are not proportional to the motions which 
 they produce ; all that we are intitled to call in doubt 
 is, whether the preffures in their exertion, while they 
 actually produce motion, or changes of motion, con- 
 tinue to he the inme as when they do not produce 
 motion, being withltood or balanced by oppofite pief- 
 fures. Confidered as cauies of motion, we ought to 
 think that they do not vary while they produce mo- 
 tion, and that the adtual prefiure, while it produces a 
 double motion, is really double, altliough it may be 
 quadruple when the body exerting it is made to act on 
 a body that it cannot move. We are confirmed in this 
 opinion by obfcrving, that other fadts fhew us, that even 
 while producing motion, the prefTure which we call 
 quadruple, becaufe we have meafured it by four equal 
 preffures balancing it, is really quadruple, confidered as 
 the caufe of motion, and produces a quadruple motion. 
 A bow which requires four times the force to draw it 
 to any given extent, will communicate the fame velocity 
 to a bundle of four arrows that a bow four times cafier 
 drawn communicates to one arrow, and will therefore 
 produce a quadruple motion. Yet it will only produce 
 a double velocity in the arrow that acquired a fimple 
 velocity from a bow having one fourth of the flrength. 
 
 Thefe difcrepancies fhould excite the endeavours of' 
 mechanicians to invefligate the laws obferved in the ac- 
 tion of preffures in producing motion. Had this been 
 done with care and with candour, we fhould not have 
 
 had
 
 DYNAMICS 519 
 
 Wor.dl.a-.v had the nreat difference of opinion, which ftlU divides times weaker how, which giver, the arrow only half the SccomlLaw 
 f Mof'on. pi,|]Q(-„pj,^,r5^ about the meafiires of moving forces. But velocity ; and thjs has the diferepancy between tlic ef- °' ^l""""- 
 ""^ ;i j'pirit of party, which had arifeii from other eaufes, fefts of prellures and of our ablbatt moving forces en- ' 
 gave importance to what was at firft only a difference tirely difappcared. For this circumffance of the diffe- 
 of exprclTion, and made the partifans of Mr Leibnitz rence in the time of acling will be found, on ftrift ex- 
 avail themfelves of the figurative language which has amination, in all tlie cafes of the change of motion by 
 done fo much harm in all the departments of phllofo- prelfures which we meafure by their effedls on a body 
 phy. Notwilhftanding all our caution, it is hardly pof- at rell. AVhen this and the appreciable changes of ac- 
 iible to avoid metaphorical conceptions when we em- tual preffure, during the time of producing the motion, 
 ploy the language of metaphor. The abettors of the are taken into confideration, all diiftrerce vauifhes, and 
 Leibnitziaii mcafure of n'oving forces, or perhaps, to the compofition of prefTures is in perfeC-l harmony with 
 fpeak more properly, the abettors of the I.eibnilz.ian the compofuion of motions, or of ablbaft moving for- 
 meafure of tliat force which i; fuppofed to preferve bo- ces. Dynamics Is thus made a dtmonltrativc fcience, 
 dies in their coiulition of mention — infill, that the force and affords the opportunity of inveiligating, by obfer- 
 which is exerted in producing any change of motion is vation and experiment, the nature of thofe mechanical 
 greater in proportion as tlie motion changed is greater: powers which refide in bodies, and which appear to us 
 and they give a very fpecions argument for their affer- under the form of preiTurc, inducing us to cor.fider pref- 
 tion. Tliey njipeal to tiic exertions which we our- lure as a caufe of motion. 
 
 ftlves make. Here we are confcious of the faiSl. Then In this, however, we arc rather inaccurate. Preffure 
 they give fimilar examples of the aftion of bodies. A is one of the fenfiblc effedls of that property which is 
 clay ball, moving fix feet per fecond, will make the ad- alfo the caufe of motion. It is not the preffure of a 
 dition of one foot to the velocity of an equal clay ball piece of lead, but its htavinefs, that is the reafon that 
 that is already moving four feet per fecond in the fame it gives motion to a kitchen jack. Preffure is merely 
 diredlion. But if tiiis lull ball be already moving ten a generic name, borrowed from a familiar inftanee, and 
 feet per fecond, we mufh follow it with .a velocity of given to moving forces, which have the fame nature, 
 twelve feet in order to increale its velocity one foot, but different names that ferve to mark their connection 
 But, without inlifting on the numberlefs paralogifms with certain fubllanc.;.-., in v% hich they maybe luppoled 
 and inconfiftencies which this way of csnceiving the to relide. Natural philofophy is almoft entirely cm- 
 matter would lead us into, it fufHces to obferve, that ployed in examining the nature of thcfe various pref- 
 the phenomena give us abundant afiTurance that there fures or accelerative forces ; and the general doctrines 
 has been the fame exertion in both thefe cafes. This of dynamics, by afcertaining what is common to them 
 acceleration is always accompanied by a comprefiion of all, enable us to mark with preeifion wh.at is charadter- 
 the balls, and the comprclTion is the fame in both. This illic of each. 
 
 We have now advanced very fir in this in vefligat ion; General co- 
 for we have obtained the criterion by which we learn rollaries. 
 the direftion and the mtpgnitude of every changing 
 force : and, on the other hand, we fee how to ftate 
 what will be the effeft of the exertion of any force 
 
 compreffion is a very good meafure of the force em- 
 ployed to produce it ; and in the prcfent cafe, we need 
 net even trouble ourfelves with any rule for its meafure- 
 ment : for furely when the comprefTion is not different, 
 but the fame, the force exerted is the fame. This is 
 
 farther confirmed by obferving, that it requires the fame that is known or fufpefted to aft. All this we learn by 
 
 the compofition of forces ; and the greatefl pait of me- 
 chanical difquiHtion confifls in the applioation of thij 
 doftrine. For fuch rcafons it merits minute confider- 
 ation ; and therefore we mufl point out iome general 
 conclufions from the properties of figure, which will 
 greatlv facilitate the ule of the parallelogram of forces. 
 
 1. The conflituent and the refaking forces, or the 
 fimple and compound forces, act in the lame plane ; for 
 the fides and diagonal of a parallelogram are in one 
 plane. 
 
 2. The fim.ple and the compound forces are propor- 
 
 force to make the fame pit, or to give the fame mo- 
 tion, to a piece of clay lying on the table of a (flip's 
 cabin, whether the Ihip befalling two miles or ten miles 
 per hour. 
 
 Thu.'i we fee that there are ftrong reafons for belie- 
 ving, that the exertions of preffure in producing motion, 
 or that the preffures aduully exer'ed, are proportional to 
 tiie changes of motion obferved, and that they coincide 
 in this refptit with our abilract conceptions of moving 
 forces. 
 
 But we have ftill better arguments. None of the 
 
 Leibnitzians think of denying the equal exertions of tional to the fides of any triangle wliich are parallel to 
 gravity, or of any of thofe powers which they call_/o/i- their directions. For if any three lines, ab. Id, ad, be 
 citations or accelerating forcis. They all admit, that drawn paralhl to AB, AC, and AD (fig. 7, n"^ z.), 
 
 54. 
 
 55- 
 
 gravity, or any conltant accelerating force, produces 
 equal increments of velocity in equal times, and that a 
 double gravity will produce a double increment in an 
 equal time, and an equal increment in half of the time ; 
 and that a quadruple gravity will produce a double ve- 
 
 they will form a triangle fimilar to the triangle ABD. 
 For the fame reafons they are proportional to the fides 
 of a triangle a't/'d, wliich are refpedftively perpendicular 
 to their direftions. 
 
 3. Therefore each is proportional to the fine of the 
 
 loeity in half the time. All thefe things are granted oppofite angle of this triangle ; for the fides of any tri- 
 
 by them, and their writings are full of reafonings from angle are proportional to the fmes of the oppofite 
 
 this principle. Now from the fadt, acknowledged by angles. 
 
 the Leibnitzians, that the quadruple force of a bow 4. Each is proportional to the fine of the angle con- 
 gives a double velocity to the arrow, in every inftant tained by the direftions of the other two ; for AD is 
 of its adtion, it indifputably follows, that it has afted to AB as the fine of the angle ABD to the fine of 
 on it only for half the time of the aftion of. the four the angle ADB. Now the fine of ABD is the fame 
 
 with 
 
 J6 
 
 57'
 
 52-0 
 
 .Secoiiill.aw 
 of Moii »ii. 
 
 58 
 Sonic fpe- 
 cial uTc^ uf 
 ih^ paral- 
 lel' pram of, 
 forces. 
 
 DYNAMICS. 
 
 59 
 
 'Equivalent 
 of many 
 forces. 
 
 ■piateXXlI 
 
 tfo. 
 
 with the fine of BAC contaiiu'J between the dircftions 
 AB and AC, and the fine of ADB is the fame with 
 the fine of CAD ; alfo AB is to AC, or BD, as the 
 fine of ADB (or CAD) to the fine of BAD. 
 
 We now proceed to the apph'cation of this funda- 
 mental propofition. And we obferve, in the firft place, 
 that fince AD may be the diagonal of an indefinite 
 juimber of parallelognims, the motion or the prefi"in-e 
 AD may rcfult from the joint aftion of many pairs of 
 forces. It may be produced by forces which would 
 fcparately produce tlie motions AF and AG. Tin's 
 -generally jjives us the means of dlfcovcring the forces 
 which concur in 'ts pr(?tiu<ftion. It one of them, AB, 
 is known in direction and intenfity, the direction AC, 
 parallel to BD, and the intenfity, are difcovered. Some- 
 times \vc know the directions of both. Then, by 
 drawing the parallelogram or triangle, we learn their 
 proportions. The force which dcilefts any motion 
 AB into 3 iTiotion AD, is had by fimply drawing a 
 line from the point B (to which the body would have 
 moved from A in the time of really moving from A to 
 D ) to the point D. The defle<Sling force is fnch as would 
 have caufed the body move from B to D in the fame time. 
 And, in the fame manner, we get the compound mo- 
 tion AD, which arifes from any two fimple motions 
 AB and AC, by fuppofing both of the motions to be 
 accomplilhed in fuccelTion. The final place of the bo- 
 dy is the fame, whether it moves along AD or along 
 AB and BD in fucceffion. 
 
 This theorem rs not limited to the compofilion of 
 two motions or two forces only ; for fince the combi- 
 ned atlion of two forces puts the body into the fame 
 ftate as if their equivalent alone had afted on it, we 
 may fuppofe this to have been the cafe, and then 
 the adlion of a third force will produce a cliange on 
 this equivalent motion. The refulting motion will be 
 the fame as if only this third force and the equivalent 
 ©f the other two had aifted on the body. Thus, in 
 fig. 8. the three forces AB, AC, AE, may at* at once 
 on a particle of matter. Complete the parallelogram 
 ABDC ; the diagonal AD is the force which is ge- 
 nerated by ..Band AC. Complete the parallelogram 
 AEFD ; the diagonal AF is the force refulting from 
 the combined aftion of the forces A B, .•\C, and AE. 
 In like manner, completing the parallelogram AGHF, 
 the diagonal AH is the force refulting from the com- 
 bined aftion of AB, AC, AE, and AG, and fo on of 
 any number of forces. 
 
 This refulting force and the refnlting motion may 
 be much more e.v.peditioufly determined, in any degree 
 of compofition, by drawing lines in the proportion and 
 direftion of the forces in fucceffion, each from the end 
 of the preceding. Thus, draw AB, BD, DF, FH, 
 and join AH ; AH is the refulting force. The de- 
 montlration is evident. 
 
 It is to be noticed here, that in the compofition of 
 more than two forces, we are not limited to one plane. 
 The force AD is in the fame plane with AB and AC ; 
 but AE may be elevated above this plane, and AG may 
 lead below it. AF is in the plane of AD and AE, 
 and AH is in the plane of .AF and AG. 
 
 Complete the parallelograms ABLE, ACKE, 
 ELFK. It is evident that ABLFKCD is a paral- 
 Iclopiped, and that AF is one of its diagonals. Hence 
 we derive a more general theorem of great ufe. 
 
 6i. 
 
 Three forces helving the prn^orhon and dlreBhn eif //jf Secondl.riv 
 three fides of a paralUlopifed, compnfe a force having , '^'' "'" ' 
 the proportion and direcVtcn of the diagonal. ^ 
 
 Any number of forces afting together on one par- One force 
 tide ot matter are balanced by a force that is equal and fa) ha. 
 oppofite to their refu!ti;ig force; for this force would ba '^"!^^ manj 
 lance their rekilting force which is equivalent to them in ^, iher"*" 
 aftion. When this is duly confidered, we perceive that 
 each force is then in equilibrio with the equivah-nt of all 
 the others ; for a force can balance only what is equal 
 iind oppofite to it. It appears very readily by the geome- 
 trical conilruftion. If, inftead of the circuit A, B, 
 D, F, H, we t?ke B, D, F, H, A, we have BA for 
 the equivalent of the forces AC, AE, .-\G; but AB 
 is equal and oppofite to BA. Therefore the force AB 
 is in equilibrio with the equivalent of all the others. 
 
 When any number of forces aft on one particle of 
 matter, and are in equilibrio, if they be confijercd as 
 nfting in parcels, the equivalents of thefe parcels are in 
 equilibrio; for let the forces AB, AC, AE, AG, AA, 
 be in equilibrio, and let them be confidered in the two 
 paix-cls AB, AC, and AE, AG, A/-; then AD is the 
 equivalent ot AB, BD (or AC), and DA is the equi- 
 valent of DF, FH, Hi (or A>^) : now AD and DA 
 balance each other. This corollarj' enables us to Am- 
 plify many intricate complications of force; it alfo ena. 
 bles us to draw accurate concliifions from very imper- 
 feft obfervations. In moft of our praftical difcufiions 
 we know, or at lead we attend to, a part only of the 
 forces which are atting on a material narticle ; and in 
 fuch cafes we reafon as if we faw the whole : yet is our 
 mathematical reafoning good with rcfpcft to the equi- 
 valent of all the parcels which we are contemplating, 
 and the equivalents of the fmaller parcels of which it 
 confifts ; and the negleftcd force, or parcel of forces, 
 induces no error on our conclufions. 
 
 In the fpontaneous phenomena of nature, the invefli- Expedition 
 gation and difcovery of our ultimate objeft of fearch is^iethidsfor 
 frequently ver)' difncult, on account of the '""Itiplicity °|^ '^" ^ ''|^. 
 of direftions and intenfitics of the operating forces or int.. motion 
 motions. We may generally facilitate the procefs, by in ci mpli- 
 fubftitutrng equivalent forces or motions afling in con-"'^'^ '•^''^ 
 venient dirtftions It is in this way that the naviga- 
 tor computes the fhip"s place with very little trouble, 
 by fubilituting equivalent motions in the meridional 
 and equatoreal direftions for the real oblique courfes of 
 the fhip. Inftead of fetting down ten miles on a 
 courfe, S. 36. 52. W. he iuppofes that the fliip has 
 failed eight miles due fouth, and fix miles due weft, 
 which brings her near to the fame place. Then, in- 
 ftead of fourteen miles fouth-weft, he fets down ten 
 miles fouth and ten miles wcil ; and he proceeds in the 
 fame way for every other courfe and dillance. He 
 docs this expeditiouflv by means of a traverle table, in 
 which are ready calculated the meridional and equato- 
 real fides of right angled triangles, correfponding to 
 every courfe and diftance. Having done this for the 
 courfe of a whole day, he adds all the fouthings into 
 one fum and all the weftings into another: he confiders 
 thefe as forming the fides of a right angled triangle ; 
 he looks for them, paired together, in his travtrfe ta- 
 ble, and then notices what angle and what diftance cor- 
 refponds to this pair. This gives him the pofition and 
 magnitude of the ftraight line joining the beginning and 
 end of his day's work. 
 
 The 
 
 «,^
 
 D Y N A 
 
 Ci-ironiU-aw Ttie miner pToce«j9 in the fame way when he takes 
 
 t}( Motion, jjij, p[^j, q( fubterraneous workiii;^?, mealuring, as he 
 • goes along, and noticing the bearing of each line by 
 
 the compal's, and fctting down, from his traverfe taUe, 
 the ncihing or fouthiiig, and the calling or weiliiig, 
 for each oblique line : but there is anotlier circumflance 
 which he muil attend to, namely, the Hope of the va- 
 rious drifts, galleries, and other workings. This he 
 does by noting the rife or the dip of each flopiug line. 
 He add"! all thefe into two funis; and taking the riiings 
 from the dips, he obtains the whole dip. Thus he 
 karns how far the workings proceed to the north, how 
 ■far to the call, and how far to the dip. 
 
 The refle^Sling reader will perceive that the line join- 
 ing the two extremities of this progrelTion will form 
 the diagonal of a redlangular parallcloplped ; one of 
 •whofe fides lies north and fouth, the other lies eafl. and 
 weft, and the third is right up and down. 
 
 The mechanician proceeds in the veiy-fame way in 
 the inveftigatitm of the veiy complicated phenomena 
 *-h!ch frequently engage his attention. He confiders 
 every motion as compounded of three motions in fome 
 •convenient direflions, at right angles to each other. 
 He alio confiders every force as refulting from the 
 joint adion of three forces, at right angles to each 
 other, and takes the fum or difference of thefe in the 
 fame or oppofite direftions. From this procefs he ob- 
 tains the three fides of a parallcloplped, and from thefe 
 fomputcE the pofition and magnitude of the diagonal. 
 This is the motion or force refulting from the compoli- 
 tion of all the partial ones. 
 
 Forces may This procedure is called the Estimation or Re- 
 H 1 "' *' Dt;CTioN of motions and forces. 
 
 icduced to -^ motion or force AB (fig. 9.) is faid to be ejli- 
 64 mated in the direftion EF, or to be reduced to this di- 
 
 A Riven di- reftion when it is conceived as compounded of the mo- 
 tions or forces AC, AD, one of which AC is paral- 
 lel to EF, and the other AD is perpendicular to it. 
 This expreflion is abundantly fignificant ; for it is plain 
 that the motion AD neither promotes nor hinders the 
 progrefs along EF, and that AC exprefles the whole 
 progrefs in this direftion. 
 
 In like manner, a force AB (fig. lO. ) is faid to be 
 ejlimated in, or reduced to, a given plane EFGH, when 
 it is conceived as refulting from the joint aftion of two 
 forces AC, AD, one of which is parallel to a line a b 
 drawn in that platic, and the other j\D is perpendicu- 
 lar to it The pofition of the line a b is determined 
 by letting fall B b perpendicular to the plane, and draw- 
 ing i P to the point P, in which BA meets the plane; 
 then A a being drawn parallel to B b, will cut off b a, 
 which is the redudlion of the motion AB to the plane. 
 Drawing • C parallel to a b, and completing the paral- 
 lelogram ACBD, it is evident that the motion AB is 
 equivalent to AD and AC, which is parallel to a b, 
 and the three forces AB, '\C, AD, are, as they Ihould 
 be, in one plane perpendicular to the plane EG. 
 
 If three forces /iB, .AC, AD (fig. 11.), are in 
 equilibrio, and are reduced to any or>e diredlion d A. l,or 
 to one plane EFGH, the reduced forces are alio in 
 equilibrio. 
 
 Fi'Jl, Liet them be reduced to one direftion d / by 
 drawing the perpendiculars B /', C r, D d ; make AL 
 equal to AD, and join BL, CL, and draw the perpen- 
 diculars L /, C £ ; then, becaufe the forcts AB, AC, 
 Suppt. V01-. I. Part II. 
 
 rca. 
 
 «5 
 
 Or a given 
 
 reducrd. 
 
 M I C S. 521 
 
 AD, are in e<jiiih'brio, ABLC mud be a parallelogram, SewTll.a\v 
 and AL is the force equivalent to AD and .-^C com- °^ M..-i'n.^ 
 b'ned ; then, becaufe the lines D d, B b, C c, L/, are 
 parallel, d A is equal to .\ I, and A i to C ff, or \.o c I \ 
 thereftne A / is equal to the lum of A i and A c, which 
 arc the reduAions of AB and AC ; therefore (^ A is 
 eqml to the lame fum, and in equilibrio with them. 
 
 SeromUy, Let them be reduced to one plane EFGH, 
 and let xi, a v., a S, be the reduced forces. The lines D ', 
 A o, B J, C «> L i, are all parallel, being perpendicular 
 to the plane ; therefore the planes AB r- x and CL xk 
 are parallel, and ,,3, , x, are parallel. For fimihr rea- 
 ions ;3 X. a y, are parallel ; theretore a^x, is a parallelo- 
 gram. Alfo, becaufe the linesD /, A a, L a, are parallel, 
 and DA is equal to AL ; therefore s x is equal to « x. 
 But becauie a3x« is a parallelogram, the forces «'?, a «, 
 are equivalent to r >. ; and o / is equal and oppofiie to 
 a \, and will balance it ; and therefore will balance « 5 
 and ay., which are the redutlions of At5 and AC to 
 the plane EFGH, while a f ii the redudion of AD j 
 therefore the propoGtion is demoaftrated. 
 
 The moft ufual and the mod ufeful mode of rednc The n^cft 
 tion is to ellimate all forces in the diredions of three "f'-f"' "•"'• 
 lines drawn from one point, at riiiht anirles to each".' ^"'"'^* 
 other, like the three plane angles of a redangular chelt, th^ir co or- 
 forming the length, the breadth, and the depth of thedmaccs. 
 cheft. Thefe are commonly called the three co crdi- 
 nates. The refulting force will be the diagonal of this 
 paralltlopiped. Th;s procefs occurs in all difquifitions 
 in which the mutual adion of folids and fluids is confi- 
 dered, and when the ofcil'.ation or rotation of detached 
 free bodies is the fubjed of difcuffion. , 
 
 The only other general theorem that remains to be Rci3,i,j 
 deduced from this law of motion is, that if a number morlovs of 
 ofboiliesare moving in any manner whatever, and an '".''"' ""' 
 
 equal force ad on every particle of matter in the fame^"'^'"''^'^ ^^ 
 11 I J- n- 1 • > • • -,, ^ ^ any extra, 
 
 or parallel dnedions, their rclaLive motions wd! fufferreoiu. .qual 
 no change ; for the motion of any body A (fig. i 2.), -n.! parallel 
 relative to another body B, which is alio in motion, is''^'"- 
 compounded of the real motion of A, and the oppofite 
 to the real motion of B ; for lot A move uniformly 
 from A to C, while B defcribes BD uniformly, draw 
 AB, alfo draw AE equal and parallel to BD, join EC, 
 DC, ED. The motion of A, relative to B, confift* 
 in its change of pofition and diftance. Had A defcri- 
 bed AE, while B defcribed BD, there would have 
 been no change of relative place or dillance ; but A is 
 now at C, and DC is its new diredion and dillance. 
 The relative or apparent motion of A therefore is EC. 
 Complete the parallelogram ACFE ; it is plain that the 
 motion EC is compounded of EF, which is equal and 
 parallel to /VC, the real motion of A, and of EA, the 
 equal and oppofite to BD, the real motion of B. 
 
 Now let the motions of A and B fuHain the fame 
 change ; let the equal and parallel motions AG, BH,, 
 be comp(«inded with the motions AC and BD ; or let 
 forces acl at once on A and B, in the parallel diicdi.)ns 
 AG, BH, and with equal intenfitics ; in cither fnppo- 
 fition, the refulting motions will he A c^ B d, the dia- 
 gonals of the parallelograms A G c C, and B H ^ D. 
 Conllrnd the figure as before, and we fee that the re- 
 lative motion is now e c, and that it is the fame with 
 EC both in refped of magnitude and pofition. 
 
 Here we Hill fee the conllant analogy between the 
 
 compofition of motions and the coinpoiition of foicts. 
 
 3U la
 
 522 D Y N A 
 
 SecondLawJn the firft cafe, tlie relative motions of things are not 
 ^'^ J^"'"'"', changed, whatever common motion be compounded 
 ' with them all ; or, as it is ufiidly, but inaccurately, cx- 
 
 prefil'd, although the fpace in which they move be car- 
 ried along \,vith any motion whatever. In the fecond 
 cafe, the relative niotions and adions are not changed 
 by any external force, however great, when equally ex- 
 erted on every particle in parallel directions. 
 
 Thus it is that the evolutions of a fleet in a uniform 
 current are the fame, and produced by the fame means, 
 as in ilill water. Thus it is that we walk about on the 
 furface of this globe in the fame manner as if it neither 
 revolved round the fun, nor turned round its axis. Thus 
 it is that the fame ilrength of a bow will communicate 
 a certain velocity to an arrow, whether it is (hot call, 
 or weft, or north, or fouth. Thus it is that the mu- 
 tual a£iions of fublunary bodies are the fame, in what- 
 ever dircdlions they are exerted, and notwithilanding 
 the very great changes in their velocities by reafon ot 
 the earth's rotation and orbital revolution. I'he real 
 velocity of a body on the earth's equator is about 3000 
 feet per fecond greater at midnight than at midday. 
 For at midnight the motion of rotation nearly confpires 
 with the orbital motion, and at midday it nearly oppofes 
 it. The difference between the velocities at the begin- 
 ning of January and the beginning of July is vailly 
 greater. And at other times of the day, and other fea- 
 fons of the year, both motions of the earth are tranf- 
 verfely compounded with the eafterly or wefterly motion 
 of an arrow or cannor. bullet. Yet we can obferve no 
 £9 change in the effefts of the mutual aftions of bodies. 
 Thisaffords This is an important obfervation ; becaufe it proves 
 a demon- that forces are to be meafnrcd by no other fcale than 
 
 llration of , ^^ motions which they produce. We have had re- 
 the proper- ' , ^ .' '^ , ..„ ,,. 
 
 tionality of pf^ted occahons to mention tlie very ditterent eitima- 
 
 n-oving tion of moving forces by Mr Leibnitz ; and have fliewn 
 forces to how, by a very partial confideration of the aftion of 
 produced"' '^°^'^ natural powers called prejfura, he has attempted 
 by them to prove that moving forces are proportional to the 
 fquares of the velocities; and we Ihewed briefly, in what 
 manner a right confideration of what paffes when mo- 
 tion is produced by meafurable preffures, proves that the 
 forces really exerted are as the velocities prodixed. 
 But the moil copious proof is had from the prefcnt ob- 
 fervation, that, in fail, the mutual aftions of bodies de- 
 pend on their relative motions alone. 
 , J •' •_. The Leibnitzian m.eafure of moving force is altoge- 
 compatible ther incompatible with the univerfal faift now mention- 
 wjth their ed, '!•(=.. that the relative motions of bodies, refulting 
 proportion- f^jj^ their mutual aftions, are not afFefted by any com- 
 fquarcs of ''"'°" motion, or the aftion of any equal and iiarallel force 
 thofe mo- ^n both bodies- for this univerfal faft imports, that 
 »iont. when two bodies are moving with equal velocities in the 
 
 ', fame diieftion, a force applied to one of them, fo as to 
 '■■ . jncreafe its velocity, gives it the fame motion relative to 
 the other, as if both bodies had been at reft. Here it 
 is plain that the fpace defcribed by the body in con- 
 fciiuence of the primitive force, and of the force now 
 added, is the fum of the fpaccs which each of them 
 would generate in a body at reft. Therefore the forces 
 are proportional to the velocities or changes of motion 
 which they produce, and not to the fquares of thofe ve- 
 locities. This meafure of forces, or the pofition that 
 a force makes the fame change on any velocity what- 
 ever, and the dependence of the relative motions on 
 any (notion that is the fame on all the bodies cf a fyf- 
 
 M I C S. 
 
 tem, are counterparts of each other. Since this indc- f'erondl j*^' 
 pendence is a matter of obfervation in all terreltrial bo- "f Mo'icn. ' 
 dies, we are intitled to fay, that the powers which the • ' 
 
 Author of Nature has imparted to natural bodies are 
 no way different from what are competent to matter 
 once called into exiftence. .\nd it alfo follows from 
 this, that we muft always remain ignorant of the abfo- 
 lute motions of bodies. The faft, that it has required 
 the unremitted ftudy of ages to difcover even the rela- 
 tive motions of our folar fyftem, is an argument to prove 
 that the influence of this mechanical principle extendi 
 far beyond the limits of this fublunary world ; nor has 
 any phenomenon yet been exhibited wliich Ihould lead 
 us to imagine that it is not univerfal. 
 
 When we have made ufe of thefe arguments with SnBeircvl- 
 fome zealous partizans of Mr Leibnitz's doftrine, they '»'* deforce 
 have anfwered, that if indeed this independence of the' ,,"'"''• 
 relative motions of terreftrial bodies were obferved to ^Jj^'|',■!^".'* 
 obtain exattly, it would be a conclufive argument. Butfurce. 
 the motion with which all is carried along is fo great 
 iji comparilon with the motions which we can produce 
 in our experiments, that the fmall additions or diminu- 
 tions that we can make to the velocity of this common 
 motion muft oblerve very nearly the proportions of the 
 additions or diminutions of their fquares. The difte- 
 rences of the fquares of 2, 3, and 4, are very unequal ; 
 but the differences of the fquares of 9, 10, 11, are 
 much nearer to the ratio of equality ; and the differen- 
 ces of the fquares of locoooi, ICOOO02, 100Q003, ^'^ 
 not fenfibly deviate from this ratio. But it is not faft 
 that we cannot produce motions which have a very fen- - 
 fible proportion to the common motion. The motion 
 of a cannon ball, dlfcharged with one-third of its weight 
 of powder, is nearly equal to that of the rotation of 
 the earth's equator. When, therefore, we difcharge 
 the ball eaftward, we double its motion ; when to the 
 weftward, we deitroy it. Therefore, according to I^eib- 
 nitz, the aftion in the firft cafe is three times the ac- 
 tion in the fecond. In the firft cafe it changes the 
 fquare of the velocity (which we may call l ) from 1 to 
 4 ; and, in the fecond, it changes it from I to o. But 
 fay the Leibnitzians, the velocity of rotation is but ^'^ 
 of the orbital velocity of the earth, and our obferva- 
 tions of the velocities of cannon bullets are not fuffi- 
 
 ciently exaft to cnfurc us againA an error of ' — r' But 
 
 the later obfervations on the peculiar motions of the 
 fixed liars concur in fhewing, that the fun, with his at- 
 tending planets, are carried along with a very great mo- 
 tion, which, in all probability, has a fenfible ratio to 
 the orbital motion of the earth. Tiiis muft make a 
 prodigious change on the earth's abfolute motion, ac- 
 cording as her orbital motion conlpires with, oppofes, 
 or croflcs, this other motion : the earth may even beat 
 abfolute reft in fome points of its orbit. Thus will the 
 compofition with the motions produced in our experi- 
 ments be fo vaiied, that cafes mujl occur when the dif- 
 ference of the refults of the two meafures of force will 
 be very fenfible. 
 
 But, farther, they have not attended to the agree- 
 ment of our experiments, when the difcharges of can- 
 non are made in a direftion tranfverfe to that ot the 
 common motion. Here the immenfity of the common 
 motion, and the minutenefs of our experimental veloci- 
 ties, can have no effeft in diminifliing the difference ot 
 the refults of the two doftrines. This will appear dif- 
 
 tinftly
 
 otion of 
 fnrcc witli 
 all o.ir ac 
 curate oli- 
 fcrvacii'is 
 of the cx- 
 errion^ ot 
 natural 
 powers. 
 
 D Y N A 
 
 Secnrdtaw u'nAly to every reader who is much converfant in dir. 
 of Motioi. qui'fitii^ns of tills kind ; aTid it is in thefe more innde- 
 ^""^^^"^ rate motions that the complete independence ot the re- 
 lative motions on the common motions mull accurately 
 appears. Pendulum clocks and watches have been of- 
 ten executed whic'u do not deviate from pcrfedt e()uabi- 
 litv of motion one part in 86400. This could not be ob- 
 tained in all directions of the olcillations, if the torces de- 
 viated from the ratio ot the velocities one part in 8(1400. 
 Perfeft a- O" the whole, we inay conhdtfr it as eilablinicd on 
 grccniLMUnf the fureft foundation, that the attion of thofe powers of 
 the abftrad „-^,„-al bodies which we call prcjj'itrc, fiich as the foice 
 of fprings, the exertions of animals, the cohelion of bo- 
 dies, as well as the aftion of tliofe other incitements to 
 iTiotion which we call attralilons and n-piilfoiis, fuch as 
 eravitation, magnetiim, and eletlriclty — is proportional 
 to the change of velocity produced by it. And we 
 miift obferve here, that this is not a mere mode of con- 
 ception, the refult of the laws of human thought, which 
 cannot conceive a natural power as the caufe of motion 
 otherwife than by its producing motion, and which 
 cannot conceive any degiee of moving power dilFercnt 
 from the degree of the motion. This is the abllraft 
 doftrine, and is true whether the preflures are propor- 
 tional to the velocities or to the Iquares of the veloci- 
 ties. But we fee farther, that whatever is the prefTure 
 of a fpring (for example) on a quiefcent body, yet the 
 preffure aftually exerted in producing a double velocity 
 is only double, and not quadruple, as our firil imperfeft 
 obfervatlous make us imagine. 
 
 Sir Ifaac Newton has added another propofition to 
 tiurdl.iw of (jjj, number of laws of motion ; namely, that e-verv ac- 
 fourded on '"" '■'' "-'^'""/"'""''^ by an equal and contrary reaction. 
 But in af}h"mlng this to be a law of nature, he only 
 means that it is an univrrlal fact : And he makes this 
 affirmation on the authority of what he conceives to 
 be a law of human thought ; namely, that thofe qua- 
 lities which we find in all bodies on which we can make 
 experiments and obfervations, are to be confidered as 
 univerfal qualities of body. But we have limited the 
 term /utu of motion to thofe confequeiices that necef- 
 farily flow from our notions of motion, of the caufes 
 of its produftion and changes. Now this third New- 
 tonian propofition is not fuch a refult. A magnet is 
 fald to aft on a piece of iron when, and only when, 
 the vicinity of the magnet is obferved to be accompa- 
 nied by certain m.otlons of the iron. But it by no 
 means follows trom this obfcrvation, that the prefence 
 of the iron fhall be accompanied by any motion, or anv 
 change of flate whatever of the magnet, or any ap- 
 pearance that can fuggefl the notion that the iron at\s 
 on the tnagnet. When this was obferved, it was ac- 
 counted a dlfcovery. Newton difcovercd that the fun 
 afts on the planets, and that the earth afts on the 
 moon ; and Kepler difcovered that the moon reafts 
 on the earth. Newton had obferved that the iron re- 
 afts on the magnet ; that the aftions of eleftrified bo- 
 dies were mutual ; and that every adtion of fublunary 
 bodies was, in faft, accompanied by an equal and con- 
 trary' reaftion. On the authority of his rule of philo- 
 fophizing, he affirmed that the planets reaft on the 
 fun, and that the fun is not at reft, but is continual- 
 ly agitated by a fmall motion round the general centre 
 of gravitation. He pointed out feveral confequences 
 tif this readion. Aftrunomers examiaed the celeftial 
 
 70 , 
 
 [s noc a 
 truili. 
 
 M 1 C S. ^ 523 
 
 motions more narrowly, and found that thofe co;ifc-S;c"ndLaw 
 quences do really obtain, and dillurb all the )jlanetai-y ,"' Moimn.^ 
 motions. It is now found that this reciprocity of ac- * 
 tlon obtains throughout the folar fyftcm with the uttnofl 
 lyrecifion, and that the third Newtonian propofition is 
 really a law of nature, although it is not a law of hu- 
 man thought. It is a difcovery. The contrary in- 
 volves no abfurdity or cotitradiftion. It would Indeed 
 be contrary to experience ; but things nu'ght have been 
 otherwife. It is conceivable, and poihble, thit a ball 
 A Ihall flrike another equal Ijall B, and carry it along 
 with it, without any dimluutlou of its velocity. The 
 faft, that the velocity of A is reduced to one-half, is the 
 indication of a force rcfiding in B, which force changes 
 the motion of A ; and the intenfity of this force is learn- 
 ed from the change which it produces. This is found 
 to be equal to the change produced by A oa B. And 
 thus the reaftion of B is difcovcred to be equal to the 
 aftlon of A. 
 
 It is highly probable, that this univerfality and equa- 
 lity of reaftion to aftlon is the confequence of fome 
 general principle, which v.'e may m time difcover ; 
 meanwhile we are intitlcd to fuppofe it univerfal, and 
 to reafon from this topic in our dilquilitions about the , 
 aftions of bodies on each other. 
 
 Although the celebrated philofophers of Europe (^3„ppr(„, 
 
 have at lall agreed in the reception of the two propofi- N,Leihiiit«, 
 
 tions fo largely difcuffed by us as the laws of motion, 2"^' other 
 
 they have differed exceedingly in their opinion about ^!j"'°,* 
 
 their origin and validity : Some afTerted that they areemertaincfl 
 
 entirely matters of experience; while others affirmed very ioade- 
 
 them to be neceflary truths. The royal academy of'l'.'^'"^ "P'- 
 
 Berlin inade this queftion the fnbieft of their prize dif-"°"? ™",' 
 I- • ■ 1 ««■ ii • ,- I ceniiiig the 
 
 lertation m tlie year 1744. Mr iNlaupertuis, preiident f,,|,|,rja,ion 
 
 of the academy, publllhed a diifcrtation ; in which heofthelav»j 
 endeavoured to prove that they are neceflary truths, only °f motion, 
 becaiife they arc fuch as make the quantity of adion the leafl 
 pojfihle an economy which is worthy of infinite wifdoni ; 
 and therefore certainly direfts the choice of the Au- 
 thor of Nature. On thisiiccount alone are they necef- 
 fary truths. 
 
 But this is not the way to confider a queflion of this 
 kind. We know too httle about infinite wifdom to be 
 able to fay with Meifrs Leibnitz and Maupertuis, that 
 the Deity fhould or fhould not imprels on bodies lav/s 
 different from thoie which are eflfential to matter; and 
 *we are not to inquire whether God could or could not 
 do this. We know from our own experience, that 
 matter, when fubjeiited to the aftion of intelligence, 
 may be moved in a way extremely different from what 
 it would follov>r if left to itfelf, and that its motions 
 may either be regulated by fixed, but contingent, laws, 
 or may be without any conflancy whatever, and vary 
 in every inftance. When we fuppofe the exitlence of 
 matter and motion, a variety of truths are involved in 
 tlie fuppofition, in the fame manner as all the theorems 
 in the third book of Euclid's Elements are involved in 
 the conception of a circle and a flraight line. Our firft 
 employment fhould be to evolve thofe truths. We can 
 do this in no way but by firft noticing the relations of 
 the ideas that we have of the different objefts of Con- 
 templation, and then following the laws of human 
 thought in our judgments concerning thofe relations. 
 This procefs of the mind is expreffed in the train of a 
 geometricid demonftration. The different parts or argu- 
 31/2 mentation*
 
 524 
 
 SecondLaw 
 of Motion. 
 
 DYNAMICS. 
 
 mentations of this train are not the eaufes of our con- changes in the motion ; and it Is not til} all aftion has Of Antre- 
 cliifions, but the means by which we fc.rn our judge- ceafeil that the motion is brought to ilsoftcnfible (late, ''"''''<' and 
 mcnt ; not the rcafons of the truth of our ultimate in which it is the ohjeift of our attention and our fu- "^^"''l 
 conclufion, but the fteps by which wo arrive at the ture dilcufiions. Inftances of the eflefts of fuch con- 'j 
 
 knowledge of it. The young geometer generally thinks tinned and fuch varied actions are to be feen in moil 
 Dtherwife : But that tU'S is the matter of faft is plain of the phenomena of nature or art. The communica- 
 from this, that more than one demonftration, and of- lion of motion by impulfe is perhaps the only inllance 
 ten very different, can be given of the fame theorem, (very frequent indeed) that can be produced where this 
 We muil proceed in the fame manner in the prefent is not neceffary : Nay, we Ihall perhaps find reafon to 
 queilion ; and the firft general truths which we And in- conclude, that this inllance is not an exception, and that 
 volved in the notions of matter, motion, and force, muft even the communication ot motion from one billiard 
 be received as necejfary truths. The fteps by which we ball to another is brought about by an adlion conti- 
 arrive at the difcovery are the laws of human thought ; nued for fomc time, and greatly varied during that 
 and the exprclfion of the difcovery, involving both the time. Much preparation is therefore neccffary before 
 truth itlVlf and the manner of conceiving it, is a necef- we can apply the general laws of motion to the folution 
 fary law of motion. There may be other fafts, perhaps of moll of the qui ftions which come before us in the 
 as general as any of thofe neccrfary laws, but yvhich do courfe even of our elementary difquifitions. We mull 
 not necelfarily refult from the relations of our notions lay down fomc general piopofitlons which determine 
 of motion and of force. Thefe are difcovered by ob- the refults of the continued, and perhaps varied, a6tions 
 fervation only ; and they ferve to charafterife the forces of moving forces ; and we mull mark the different ef. 
 which nature prefents to our view. Thefe fafts are feels of the fimple continuation of aftion, and alfo thofe 
 coni'mgent laws of motion. of the variations in this cojitinued aftion, both in re- 
 
 We apprehend that this method has been followed fpeft of intenfity and oirection. The effedl of a mere 
 
 " " " ' ■ continuance of aftion mull be an acceleration of the 
 
 motion ; or a retardation of it, if the force continue to 
 adl in the oppofite direftion. The tffedl of the conti- 
 nued aftion of a tranfverfc force mull be a continual 
 defleftion, that is, a curvelinral motion. Thefe mull 
 therefore now occupy our attention in their order. 
 
 Of Accelerated and Retarded Motions. 
 
 in treating this article. The firft propofition, termed 
 a laiv of motion, is only a more convenient way of ex- 
 prefiing our contemplation of motion in body as an ef- 
 feft of the general caufe which we term force. The fe- 
 cond propofition does nothing but exprefs more dif- 
 tinftly the relation between this caufe and its effetl ; 
 it expreifes what we mean by the magnitude and the 
 kind of the caufe. The propofition, flating the com- 
 pofition of forces, is but annther form of the fame law. 
 
 All men can perceive, that a (lone dropped from _. '' 
 better fuited to the ordinary procedure in geometrical the hand, or fliding down an uniform flope, has itSji^ntiji jj. 
 difquifitions. motion continually accelerated, and that the motion ofpolkion if 
 
 an arrow rifing perpendicularly through the air is con-".""' concep- 
 These propofitions might have completed the doc- tinually retarded; and they feel no difficulty in concei- "°" " j ' 
 trines of dynamics ; but it appears that, in order to ving thefe changes of motion as the eflefts of the con-^f 3 i,„^y 
 the produftion of a material univerfe which fhould ac- tinual operation of their weight or heavinefs. The falling in refpeift 
 coinplilh the purpofes of the Creator, it was neceffary ftone is in a different condition in rcfpedt of motion into'no"un.. 
 that there be certain charafteriftic differences between the beginning and the end of its fall. In what rcfpeft do 
 the forces inherent in the various colleftions of matter thefe ftates of the body differ? Only in lefpeft to what 
 which compofe this univerfe. The fails or phyfical we call its ve/ocity. This is an affeftion of motion ; it 
 laws (for the above-mentioned laws are metaphyfical) is an expreflion of the relation between the two notions 
 of motion may be different from thofe which would or ideas which concur to form the idea of motion ; 
 have been obferved had matter been left entirely to it- namely, the fpace and the time. Thefe are all the cir- 
 felf. This difference may have introduced other laws cumllances that we obferve in a motion. Time elapfes, 
 of motion as necelfarily refulting from the nature of and during its currency a fpace is defcribed. The 
 
 term velocity expreffes the magnitude of the fpace which 
 correfponds to fome unit of time. Thus, the rate of a 
 fhip's motion is determined, when we fay that it is nine 
 miles in an hour, or nine miles per hour. AVe fome- 
 
 the forces. We have occaiionally itientioned lome in- 
 flances where this appears to obtain, but gave good rea- 
 fons for affirming, that a due examination of all circum- 
 ftances which may be obferved in the produftion or va- 
 
 riation of motion by thofe forces, has demonflrated that times fay (but aukwardly) " The motion is at the rate, 
 
 there are no fuch deviations from the two laws of mo- or with the velocity, of a mile in three days." It is moft 
 
 tion already determined, but that all the mechanical conveniently expreffed by a number of fome given units 
 
 powers of bodies, when confidered merely as eaufes of of length, which completely make up the hne defcribed 
 motion, aft agreeably to the fame laws 
 
 Careful exa^ 
 mination was, however, faid to be nccelfary. 
 
 This examination mull confift in dillinftly noticing 
 the clrcumllances that occur in the produftion of mo- 
 tion by any force whatever. It is by no means enough 
 
 during this unit of time. But the mechanicians ex- 
 prefs it in a way more general by a fraftion, of which 
 the numerator is a number of inches, feet, yards, fa- 
 thoms, or miles, and the denoijiinator is the number of 
 feconds, minutes, or hours, employed in moving along 
 
 to ilate finiplv the intenfity of the force and the direc- this line. This is a very proper expreffion ; for. when 
 tion of its exertion. If a force continue to aft, it con- we fpeak of any velocity, and continue to reaion from 
 tinucs to vary the motion already produced. Should it, we conceive ourfelves to fpeak of fomething that re- 
 the- force change its intenfity or direftion while it is mains the fame, in the different occafions of ufing the 
 afting, thefe circumflances muft induce ftill farther term. Now if the velocity be eonftant, it is indifferent 
 
 how
 
 DYNAMICS. 
 
 ef Acccle- how long the line may he; bccaufe the time of its dc- Axiom. — If A be to B in a ratio that is greater than 
 
 ratcil and jcrjptioi) will be Icngtheiifd in the fame proportion, any ratio lifs than that of C to D, but kfs than any ratio 
 
 Motors '^ ''"■' '' 4^ ^^'^^ ^*^ defcribed in 12 feconds, 36 ftet greater than that of C to D, then A is to B as C to D. 
 
 ■I will be delcribcd in 9 ftconds, i6 feet will be defcribcd Take the ftraight line a t g to reprefent the time of y 
 
 in 4 feeonds, &c. Now H, y*, and '/, are fraiftions the body's motion along ACG, fo that the points a, c, 
 
 of equal value, being equal to 4> or ^, that is, to the f, g, may rejirefcnt the inllants of tine in which the. 
 
 velocity of 4 Itet per iccoiid. The value ot tin's frac- body paffes through the points A, C, F, G ; and the 
 
 tion, or the quotient of tlie number of the units of portions <j r, fy",y"^, of the line « _^, may reprefent the 
 
 length, divided by the number of units of time, is the times employed in defctibing the portions AC, CF, 
 
 number of thofe units of lengtli defcribcd uniformly in FG ; and therefore a c is to a f as the time of defcri- 
 
 one unit of time. b'ng A.C to the time of defcrihing A F. 
 
 Magnitude But how fhall we determine the velocity of any inftant Moreover, let hkno be a line io related to th'j 
 
 of a vcio- or in any point of a motion that is continually clianging? ftraight line a cfg,hy the perpendicular ordlnates a h, 
 
 city of Suppofe that a body has fallen 144 feet, and that we c i,/n,g 0, and the areas a c k h, afn h, agoh, may 
 
 Tve niTac ^'°"i'l afccrtain its velocity in that point of its fall, or be proportional to the portions AC, AF, AG, of the 
 
 tual mea- the velocity which it has in paffing through that point? line deicrlbcd by the moving body ; and let this rela- 
 
 lure. In the next fecond the body falls i 12 feet farther, tion be true with rcfpeft to every point B, D, E, Sec, 
 
 This cannot be the meafure of the velocity at the be- and the conefpondiiig points b, d, e, &c. 
 
 ginning of the fourth or the end of tlie third fecond. It Tlien it is affirmed, that ihe velocity in the point C is 
 
 is too great. The fall during the preceding fecond to the velocity in the point F as c i is t')fn, 
 
 was 80 feet. This is too fmall. The mean of thefie Let the equal lines b c, c d, ef,fg, reprefent equal 
 
 80+112 192 . moments of time, and let B, D, E, G, be the points 
 
 two, or ^ , = — , = 96, IS probably more ex- through which the body is paffing at the inrtants b, d, 
 
 ad. Due attention to the nature of this motion (hews eg- 1'hen the areas b i k c,-c k I d, e m nf,fn g, will 
 
 us, that 96 is the proper meafure, or that the motion reprefent, and be proportional to, the fpaces BC, CD, 
 
 at that inftant is at the rate of 96 feet per fecond. But EF. FG, which are deferibed during the moments b c,. 
 
 it is peculiar to this kind of motion that the half fum ^ '^i ^fyfs- 
 
 of the fpaces deferibed in two" fucceeding equal mo- Draw t p parallel to a g, fo as to make the rcdaiigle 
 ments is the meafure of the velocity in the middle in- btpc equal to the trapezium bike; and draw the lines 
 ftant. Therefore this method will not gtnerally give q ■". " ''j -f •■^'i i" the fame manner, lb that each reftangle 
 an accurate meafure. Yet it is indifpenfably neceflary may he equal to its correfponding trapezium, 
 to obtain fome accurate meafure ; for it Is in tills par- If the motions had been uniform during the mo- 
 tlcular alone that the Hate of the body differs from its ments b c and/^, that is, if the fpaces BC and FG had 
 fimilar flate in another intlant. The difference of place been uniformly deferibed, then the velocity in the poinC 
 makes no dlllinaion ; for if a body continue Its motion C would have been to the velocity in the point F as cp 
 unchanged, its ctnidition in every different inilant of to/j : For lince the reftangles 4 // c and/j .v^f are re- 
 time, or point of fpace, is unchanged or the fame. The fpee'iively equal to the trapeziums bike and/nojj; anil 
 change of place is not a change of motion, but is in- fince b i k c is to f n ^ as BC Is to YG, the reftangle 
 volved In the very conception of the continuation of the btpc is to the redtatigle / s x g as BC to FG. But 
 motion. The change of condition confifts, therefore, becaufe thefe two redangles have equal altitudes b c 
 in the change of velocity . Therefore the change of ve- and f g, they are to each other in the proportion of 
 locity Is the only indication, and the only meafure of their bafes cp and ^x, or c p and/j. Therefore BC is 
 the action (perhaps accumulated) of the changing force, to FG as c p to//. But if BC and FG are uniformly 
 It is therefore the chief objeft of our fearch ; and accu- deferibed in equal times, they are proportional to the 
 
 Of Accele- 
 rated and 
 Retarded 
 Mmionj, 
 ,/— J 
 
 rate meafures of velocity are abfolutely necefTary. 
 
 When the velocity changes continually, there can be 
 no ai9(/rt/ mcafui e ot it. In what then does the mag- 
 nitude of a velocity coufifl, when there is: no actual mea.! 
 fure of it .' It is a certain undefcribaWe determina- 
 TION ; by which, if not changed, a certain fpace would 
 be uniformly deferibed in a given unit of time. Thus 
 we know, that If, when a flone has fallen 16 feet, its 
 motion be directed along a horizontal plane, without 
 
 velocities of thofe unifonu motions. Therefore cp is 
 to f s as the velocity with which BC is uniformly dc- 
 cn'bed to the velocity v/ith which FG is uniformly de- 
 feribed in an equal time. 
 
 But the motion expreffed by the lignre is not uni- 
 form, becaufe the line h I recedes from the axis a g, 
 and the areas, cut off By the parallel ordlnates, increafe 
 in a greater proportion than the correlpon^r.o- parts of 
 the axis ; that is, the fpaces increafe faft.T tiian the 
 times : for the moments b c, c d, eft/g, b' ing all equal, 
 it Is evident that the correfponding flips ul the area con- 
 tinually augment. The motion Is fwifier at the inilant 
 
 diminution, it will move on for ever at the lale of 
 Momenta- ^^ f*^*^' P'^'' '^cond. The fpace which would be thus 
 ry pr«f.or. deferibed is not the veLcIty, but the meafure of the ve- 
 
 tion of ve- locity. But the proportions of thofe fpaces, being the- c than at the inftant b, and the velocity at the inllant c 
 
 '°'^''"' '.^'^'proportions of thole meafures, are the proportions of h gren/er than thai with which the fpace BC would be 
 
 nually the velocities themfclves. We may difcover thefe pro- uniformly deferibed in the fame time. For the fame 
 
 changinjT. F'^ttions in the following manner : reafon, the velocity at the Inflant/is le/s than that with 
 
 Fiir(!ami:n- Let ACG (fig. I-?.) be a line deferibed by a body which the fpace FG would be uniformly delcribcd in 
 
 . '"^'■'''''-' with a motion anyhow continually, but gradually, va-. the fame time. Therefore the velocity at the iullant s. 
 
 chanical '^"^^ ' ^""^ '*t it be required to determine the propor- is. to the velocity at the inftant /in a greater ratio than- 
 
 d fi|uiC. tion of the velocity in any point C to the velocity in that of c p tofs. In the very fame manner, it w;!k 
 
 tioii!. any other point F. appear by comparing the motion during the moment 
 
 c J
 
 526 
 
 Of Acccle. 
 rated ami 
 Retar. ed 
 Moiions 
 
 73- 
 
 D Y N A 
 
 ■(.• d with the motion during the moment ef, that the ve- 
 locity at the inftaut c is to the velocity at the inllant/ 
 in a lefs ratio tlian that o( c q to/r. 
 I Therefore the velocity in the point C is to the velo- 
 city in the point Fin a greater ratio lh»n that of c p to 
 fs, but in a kfs ratio than that of c q \u f r. 
 
 But by continually dimininiing the equal moments, 
 b c, c d, ef-fg'i it is evident that c p and c q continually 
 approacii to equality with c k; and_/V aiiAj's, continual- 
 ly approach to equality witli f n, that wlien c p is Itfs 
 than c l,fs is greater than/n, and when f j is greater 
 than c h, f r is lefs tlian/n. 
 
 Therefore the velocity in the point C is to the velo- 
 city in the point F in a ratio that is greater than the 
 ratio of any line lefs than c i to any line greater than 
 J n, but wiiich is lefs than the ratio of any hr.e greater 
 than f if to any line lefs than f n. Therefore the ratio 
 of the velocity in C to the velocity in F is greater than 
 any ratio that is lefs than that of c i to/n; but it is lels 
 than any ratio that is greater than that of c /• to f ti. 
 Therefore the velocity in the point C is to tlic velocity 
 in the point F as ^ /f to_/"n. 
 
 This important tlieorem may he exprefTed in more 
 general terms as follov.'s : 
 
 If l/je abfi'ilfa 3 g of a line h k o repreftnt the time of 
 any motion, and if the ureas hounded by parallel ordiuates 
 be proportional to the fpaces defcribed, tl>e ordiuates are 
 proportional to the •oelocities. 
 
 Remark. The propriety or aptitude of exprefilng 
 the time by the portions of the axis « eg, will, perhaps, 
 appear more clearly in the following manner. 
 
 Let a c g hi: any Itraight line, ami let i.< /■ ti he ano- 
 ther line, ftraight or curved. Tct the itraight hr.e a b a, 
 perpendicular to a g, be carried uniturmly down along 
 this line, keeping always perpendicular to it, and there- 
 fore always parallel to its firll pohtion a h x. In its 
 various lituations e k %, e m z, &c. it will cut off areas 
 a c k h, a e m h, &c. bounded by the axis by the ordi- 
 uates a h and c t, or by the ordiuates a h aud e m, &c. 
 and by the line h k g. By this motion the moveable or- 
 dinate is faid, in the language of modern geometry, to 
 generate the areas ackb, aemh, &c. At the fame 
 time, let a point A move along the line ACG, fctting 
 out from A at the inttant when the line a a fets out 
 from a ; and let the motion of the point A be io re- 
 gulated, that the fpaces AB, AC, AD, &c. generated 
 by this motion, may increale at tlie fame rate with the 
 areas, ab, ih, a e k h, a d I h, &c. or fuch that we (liall 
 have AB to AC ^s a b i h, X.<i a c i h, &c. It is plain, 
 that the motion along AG is the fame with that defcri- 
 bed in ttie enunciation of the propoiition : for bceaule 
 the motion of the ordinate a s, along the axis a g, is 
 fuppofed to be unifoim, the fpaces a b, a e, a d. Sec. are 
 proportional to the times in which they are defcribed, 
 and mav therefore be taken to meaiure or to reprefent 
 thofe times. 
 
 Cor. I. In a motion continually varied, the -veloeities 
 in the different points of the path are to each other in 
 the limiting or ultimate ratio of the fpaces defcribed in 
 equal times, thofe times being luppoled to diminilh con- 
 tinually : for it is evident, tiiat if the equal moments 
 b c, c d, e f, fg, are fuppofed to diminifh continually, 
 till the inftants b and J coalefce with c, and the inftants 
 t aadg coalefce with/; then the ratio of c i to fn is 
 
 M I C S. 
 
 the hmit of the continually increr.fmg ratio oi c p to//, Of Accel*, 
 or of the continually dmiinifning ratio of c q to//-. Sir g°"'^ ^"^^ 
 Ifaac Newton calls this the ultmiate ratio of c p to fs, M„','|on, 
 or ofc q to/r. Now the ratio of c p to f s is, by con- ' . - - ^ „ j 
 ftruftion, the fame with the ratio of the reclangle btpc 
 to the rcflangle/ J- x g, and tlie ratio of c q to fr is the 
 fame with the ratio of the reilangle i q v d to the rec- 
 tangle e u r f. But the ratio oi the redtangle b t p c to 
 the reftangle// xg is the fame witli the ratio ol the 
 fpace bite to the Ipace/n g ; that is (by hypothefis), 
 the fame with the ratio of the i'pace BC to the ipaoe 
 I'G ; and the ratio of the rectangles c q v d and e u r f 
 is the fame with that of the fpaces CD and EF. There- 
 fore the ratio of the velocity at C to the velocity at F 
 is the fame with the ultimate ratio of the fmall incre- 
 ments BC, FG, or CD, EF of the fpaces generated iu 
 very fmall and equal times. 
 
 It is alfo evident, that bccaufe the ratio of c k to f n 
 is the limit both of the ratio of c p to f s and of the 
 ratio of c q to/r, thefe ultimate ratios are the fame, 
 and that we may fay that the velocity in C is to the ve- 
 locity in Fin the ultimate ratio ot BC to EF, or in the 
 ultimate ratio ot CD to FG. 
 
 ^Ve alfo can eahly perceive, tliat the ratio of the 
 area b i k c to the area e m n/ approaches more near to 
 the ratio of c i tx> f n as we take the moments b c and 
 f /fmaller. Therefore, in many cafes of praftice, where 
 it may be eafy to meafure the ipaces defcribed in the 
 different fmall moments of the motion, but difficult to 
 afccrtain their illtimate ratio, fo as to obtain accurate 
 meafures of the proportions of the velocities, we may 
 reduce the errors of meafurement to fomething very in- 
 fignificant, by taking thcle moments extremely imall ; 
 and we ihall diminilh the error itlll more, by taking the 
 proportion of the half fum of BC and CD to the half 
 ium of EF and FG for the proportion of the velocities 
 in C and F. 
 
 It often happens that we have it not in our power to 
 cotnpare the fpaces defcribed in fmall moments which 
 are precifely equal. Still we can find the exait pro- 
 portion of the velocities, if we can afcertain the ultinjate 
 ratio of the increments of the ipaces, and the ultimate 
 ratio of the moments of time in which thefe increments 
 are defcribed : for it is plain, by conhdering the gradual 
 approach of the points p and r to the points k and n, 
 that the ratio of c k to f n is ftill the ultimate ratio of 
 the bafes of redlangles equal to the mixtilineal areas, 
 whether the altitudes (reprefenting the moments) are 
 equal or not. Now the bafes of two reftanglcs are in 
 the proportion of the reftangles directly, and of their 
 altitudes inverfcly. But the ultiiuate ratio of the alti- 
 tudes is the ultimate ratio of the moments, and the ul- 
 timate ratio of the redangles is the ultimate ratio of the 
 fpaces defcribed in thofe unequal moments. Therefore, 
 in fuch cafes, we have. 
 
 Cor. 2. The velocities arc in the ratio compounded of -j^ 
 the dire£l ultimate ratio of the momentary increments of the 
 fpaces, and the in-verfe ultimate ratio of the increments (or 
 moments) of the times in which thefe increments of the fpa- 
 ces are made. 
 
 If J, V, and /, are taken to reprefent the magnitudes 
 of the fpaces, velocities, and times, and if s, v, and f, 
 arc taken always in the limiting or ultimate ratio of 
 their momentary increments, we fhall have v always in 
 
 the
 
 ratcil and 
 RiUrUcJ 
 Ml ti.11.5. 
 
 D Y N A 
 
 inverfcly. We 
 exprefs this by the proportional equation v =^1., which 
 
 or AcLvle- j^g 'proportiun of s direftly, and of/ 
 
 is equivalent to the analogy V : ^■ zz — : — , or V : -u 
 
 .... T t 
 
 = Hi -.sT. * - 
 
 75. iV. £. Here obfcrve, that tliis is not the only way of 
 
 flating the relation of fpace and time — the ablcilfa may 
 be made the time, and the ordinate the ipaeej then the 
 
 velocity ;=-^_. 
 
 .V 
 
 The couveif>- of tliis propoiition may be thus ex- 
 prefied. 
 
 I J the axis 3 g of ll-ie line li k o repreferU the lime of a 
 •varied motion along the line AG, and ij the ordiiintes a h, 
 b i, c k, lye. be as the •vel'tcilics in the injlanis a, b, c, or 
 ill the points A, B, C ; then the areas a b i h, a c k h, 
 ad 1 h, Sif. are proportimt.d t'j the fpiucs AB, AC, AD, 
 
 This may be demonflrated in the fame way with the 
 former ; but the indiredl demonftration is more brief, 
 and equally ftiicl. 
 
 If the fpaces AC, AF, &c. are not proportional to 
 the areas ackh, afnb. Sec. they are proportional to 
 forae other areas ackh', afri h', &c. which are bound- 
 ed by the fame ordinatcs, and by another line h' k n'. 
 But becaufe the areas a c k h', afn' h'. Sec. are always 
 proportional to the fpaces AC, r\F, &c. defcribed on 
 the line AG, the velocityin the point C is to tlie velo- 
 city in the point F ;:s the ordinate c i is to the ordinate 
 fri. Eut, by hypothefis, the velocity in C li to the 
 velocity in F asii iofn, and fn' is equal to fn ; which 
 IS abfurd. Therefore the fpaces AC, AF, are not pro- 
 portional to any other areas, &c. 
 
 Cor. The ultimate ratio of the momentary increments of 
 the fpaces is compounded of the ratio of the velocities, and 
 the ultimate ratio of the iniremenlj of the times : for when 
 the moments ic, ef, are equal, it is evident thnt the 
 ultimate ratio of the reflangles icp t, efr u is the fame 
 with the ultimate ratio of the increments of the fpaces. 
 But the ultimate ratio of thefe reftangles is the fame 
 with their bafes c p and fr ; that is, the ratio of £ * 
 to fn, that is, the ratio of the velocities. And when 
 the moments are unequal, the ratio of the rcttanglcs is 
 compounded of the ratio of their bafes and the ratio 
 of their altitudes ; thnt is, compounded of the ratio of 
 the velocities and the ultimate ratio of the moments of 
 time. 
 
 We have, therefore, S : j- ::^ VT : v I, and s = v I. 
 
 It moll commonly happens, that we can only obfirve 
 the accumulated rtfults of varied motions; and in them 
 we only obferve a fpace paiild over, ami a certain por- 
 tion of time that has clapfed during the motion. But 
 being able to diftinguifn the portions of the whole fpace 
 which are defcribed in known portions of the whole 
 time, and having made fuch obfevvations in feveral parts 
 of the motion, we difcover the general law that the mo- 
 tion aifecls, and we affirm this law to hold univerfally, 
 even though we have not obferved it in every point. 
 We do this witli a degree of probability and confidence 
 proportioned to the frequency of our obfervation. It 
 is not till we have done this that we can make ufe of 
 
 raici) and 
 Ritarted 
 Motinnm 
 
 78 
 
 M I C S. 527 
 
 the firft of thefe two propofitions, which enables us to Of Accck- 
 afcertaln the velocity of the motion in its different mo- 
 ments. Thus if we obferve, that a Hone in falling d« 
 fcends one foot in the quarter uf a fecond, 16 feet in a . 
 fecond, 64 feet in two feconds, and 144/eet in three 
 fecoEids ; the general law immediately obferved is, " that 
 the fpaces delcribed are as tlie fquarcs of the times ;" 
 for I is to t6 as the fquare of -jth to the fquare of 1. 
 Again, 16 is to 64 as 1' to 3' ; and 16 is to 144 as 1* 
 to 3'. Hence we infer, willi great probability, tliat 
 the (lone would fall 36 feet in a fecond and a half; for 
 ''16 is to 36 as I' to i{-- ; and we conclude in the fame 
 way for all other pans of the motion. 
 
 Tliis immediate oljfervation of the analogy between A good ex- 
 the fpaces and the fquares of the times fuggtfls an eafy^^P''"^ 
 determination of the velocity in this particular kind ofjl'i^^^^'^'^*" 
 motion; and it merits particular notice, being very often thod. 
 referred to. V»'e<'antake a^to rcprcfent the time; 
 and then, becaufe the areas which are to reprefent the 
 fpaces defcribed mull be propoitioned to the fquarts of 
 the portions of a^, we pciteive that the line which 
 con^.es in place of h .i mull be a ftraight line drawn 
 from a. For CNample, the ftraight line a S y. For this 
 is'the only boundary which will give areas aba, ac y, 
 aji, &c. proportional to a i\ a c', ad', &c. And we 
 perceive that any ilraight line drawn from a will have 
 this property. 
 
 Having thus got our reprefentations of the times and 
 the fpaces, we fay, on the authority of our theorem, 
 that the velocity at the inftant b is to the velocity at 
 the inllant d as b I' to d ^, &c. And now we begin to 
 make inferences, purely geometrical, and exprefs our 
 difcovery of the velocities in a very gi.ner.^1 and fimple 
 manner. We rcmaric, that b (i is to ds as ab is to ad; 
 and we make liie fame a31rmation concerning the ma'/-- 
 nitudes reprcfented by thefe lines. We fay that the 
 velocity at the inftant b is to the velocity at the inftant 
 d as the time « i is to the time a d. AVc fay, in terms 
 ftill more general, that the velocities are ])roportional to 
 the times from the beginning of the motion. We more- 
 over perceive, that the fp.ices are alfo proportional to 
 the fquares of the acquired velocities ; or the velocities 
 are as the fquare roots of the fpaces. 
 
 We can farther infer, from the properties of the tri- 
 angle, that the momentary increments of the fpaces are 
 proportional to the momentary increments of the fquares 
 of the times, or of the fquares of the velocities. 
 
 We alfo obferve, that not only tlie vvhole acquired 
 velocities are proportional to the whole elapfed times, 
 but that the increments of the velocities are proper, 
 tional to the times in which they are acquired ; for ^ " 
 is to ;> •? as ^ i: to df. Sec. Equal increments of velocity 
 are therefore acquired in equal times. Therefore fuch 
 a motion may, in great propriety of language, be deno. , 
 
 minated a uniformly accelerated motion; that 
 is, a motion in ivhich we obferve the fpaces proportioned to 
 the fquares of the times, is U motion uniformly accelerated ; 
 and fpaces in the duplicate ratio of the times form the of. 
 tenfible charaiSteriih'c of an uniformly accelerated motion. 
 I^aflly, if we draw , x parallel to the axis a b, we per- 
 ceive that the reilangle a ^ 1 x is double of the triangle 
 /Iff. Now becaufe ae reprefents the time of the mo. 
 tion, and « t reprefents the acquired velocity, the rec- 
 tangle fl f 1 >. will reprefent the fpace which would be 
 uniformly defcribed with the velocity << during the time 
 
 75'
 
 ■^28 
 
 of Ac.eV- 
 
 riting- ard 
 Retard! I g 
 
 1 O'CtS. 
 
 D Y N A 
 
 at. But tlie triangle «« I rcprtfcnts the fpace really 
 defcribcd with the uniformly iicccleratcd motion tldring 
 the Came time. Hence we inter, that the fpace that is 
 defcribed in any tirni.', with a motion iiicrealing- uniform- 
 Jy tVum nothing, i.i onc-lialf of the fpace wliicli would 
 be uniformly defcribed duiiiig tlie fame time with the 
 final velocity. 
 
 Thefe are but a part of the inferences svhich we may 
 draw from the geometrical properties of thofe reprelen- 
 tat ions which we had fckdttJ of the diilerent meafure- 
 able aSedions of motion. We may affirm, with refptft 
 to the motions thcmfclves, ail the inferences which re- 
 late to magnitude and proportion, and thus improve our 
 knowledge of the motions. 
 
 We took the opportunity of this very fimple and 
 perfpicnous axample, to give our young readers a juft 
 conception of the mathemnl'ical method of proiecuting 
 iiRcharcical knowledge, and to make them fenfible ot 
 the itnqueftionaWe authority for every theorem deduced 
 in this manner. 
 
 One of the moR important is, to difcover the accu- 
 mulated refult of a motion of which we only cblerve the 
 momentary increments. This is to be done by finding 
 the area, or portions of the area, of the mixtilineal fpace 
 tig oh ; and it is evidently anak'gous to the inveife me- 
 .thod of fluxions, or the integral calculus. 
 
 In moft cafes, we rauft avail ourfelves of the corolla- 
 ry s = V i, and we obtain the folution of our queftion 
 only in the cafes where our knowledge of the quanti- 
 ties], t, and 11 (confidered as geometrical magnitudes, 
 that is, as lines and furfaces), enables us to difcover 
 s and >. 
 
 Of Accelerating and Rethrdhig Forces. 
 
 Having thus difcovered the proportions of the ve- 
 locities in motions varying in any manner whatever, we 
 can obfcrve the variations which happen in them. Thefe 
 variations are the effefts, and the only marks and mea- 
 fures, of the changing forces. They are the charafte- 
 riftics of their kinds (confidered merely as moving for- 
 ce?) ; that is, the indications of the direftions in which 
 they act; for this is the only difference in kind of which 
 they art fufceptible in this general point of view. If 
 thtv increafe the velocity, their dircftion muft be con- 
 ceived as the fame with that of the previous motion ; 
 becaufc the refult of the adtion of a force is equivalent 
 to the ci mpofition of the motion which that force 
 would produce in a quiefcent body with the motion al- 
 ready exifting : and an increafe of velocity is equivalent 
 ■to the compofition of a motion in the fame direction. 
 
 Havi g no other mark of the force but the accelera- 
 tion, we have no other name for it in the abftraft doc- 
 trines of dynamics, and we call it an acceleratikc 
 FORCE. Had it retarded the motion, we fhould have 
 called it a retarding force. 
 
 In like manner, we have no meafure of the magnitude 
 or inlenfity of an accelerating force, but the acceleration 
 which "it prodr.ces. In order therefore to invelligate the 
 powers which produce all the changes of motion, we 
 mnlf endeavour to obtain mcafures of the acceleration. 
 
 A continua. increafe of velocity is the effect of the 
 continued aftion of accelerating forces. If equal in- 
 crements of velocity jre produced in every fucceeding 
 8(jual moment of time, we cannot conceive that there is 
 
 M I C S. 
 
 any change in the accelcr-iting fore?. Therefore a u.ii- Of Actele. 
 formly accelerated motion is the mark of the unvaried r*''"K »""1 
 adion of an accelerating force, that is, of the continued ';^"""'8 
 
 r c rr !/■• •• i'oices. 
 action 01 a coi;ltant force ; or a force wnole inteniity •' ' ^ 
 
 always the fame. When therefore we obicrvc a body 
 ficfcribe fpacea proportional to the fquarea of the timr-^, 
 we mull inter that it is urged forward by a forct: whole 
 intenfity does not change ; and, on the other IrmJ, a 
 conftant force mull produce a uniformly accelerated mo- 
 tion by its continued aftion. And if any pitvljus cir. 
 cumflances allure us of this continued aftlon of an in- 
 vaiied force, we may make all the inferences which were 
 mentioned under the article of uniformly accelerated mo- 
 tion. 8t 
 That foice muft furely be accounted double which ^I'^f"" of 
 
 produces a double increment of velocity in the fame*"*''^ 
 • 1 ■ T 1,- r 1 „• "nt force, 
 
 time by its uniform action, we can form no ottier elu- 
 
 mation of its magnitude. And, in general, accelerating 
 forces muJJ be accDunted proportional to iht increments of •ue- 
 locity ivhich they produce, by aSing uniformly during the 
 fame or equal times. 
 
 Suppofing tlura to aft on a body at reft. Then the 
 velocity produced is itfclf the increment ; and we muft 
 fay, that accelerbting forces are proportional to the ve- 
 locities which they generate in a body in equal times. 
 And becaule we found (n 79.), that the fpace dtfcri- 
 bed with a uniformly accelerated motion is half the 
 fpace which would be uniformly defcribed in the fame 
 time with the final velocity, which fpace is the direft 
 meafure ot this velocity, and becaule halves have the 
 fame proportion with the wholes — we may fay that 
 ateeleratiiig forces are proportional to the fpaces lhrough-'^"°y^^ 
 which they impel a body from refl in equal times by their '^ " ' 
 tin form aSicm. 
 
 Ttiis is an important remark ; becaufe it gives us an 
 eafy meafure of the force, without the trouble of firft 
 computing the velocities. It alio gives us the only dif- 
 tinft notion that we have of the rocafurement of forces 
 by the motions which they produce. When fpeakiug 
 of the compofition ot forces we dillinguilhed or deno- 
 minated ttiem by the fides and diagonal of a paraltelo- 
 gram Thefe lines mult be conceived as proportional to 
 the fpaces through which the forces urge the body uni- 
 formly during the fmall and infenlible time of their ac- 
 tion, which time is fuppofed to be the lame for both 
 forces ; for the fides of the parallelogram are fuppofed 
 to be feparately defcribed in equal times, and therefore 
 to be proportional to the velocities generated by the 
 conftituent forces. If indeed the forces do not aft uni- 
 formly, nor fimiiarly, nor during equal times, we can- 
 not lay (without farther inveftigation) what Is the pro- 
 portion of the intenfity of the forces, nor can we infer 
 the compofition of their a£lion. We mull at leaft fup- 
 pofe, that in every inftant of this very Imall time of their 
 joint aftion, their direftion remains unchanged, and tiiat 
 their intenfities are in the fame ratio. We ihaLl fee 
 by and bye, that with thefe conditions the fides of the 
 parallelogram are ftiU proportional to the velocities ge- 
 nerated. In the mean time, we may take the fpaces 
 througti which a body is uniformly impelled from reft 
 (that is, with a uniformly accelerated motion) as the 
 meafures of the forces ; yet thefe fpaces are but th» 
 halves of the me.ifures of the velocities. Then, if a bo- 
 dy be moving with the velocity of 52 feet per fecond, 
 and an accelerating force afts on it during a fecond, 
 
 and
 
 D Y N A 
 
 if Acfele- and if this force be fuch that It would impel the body 
 •Qiing.ind ^from a tlate of rcll) l6 feet, it will add to the body a 
 ietardmg velocity of 32 feet per fecond. Accordingly, this is 
 _ the efteft of gravity — the weight of a pound of lead may 
 
 be confidered as a force which does not vary in its in- 
 tenlity. We know that it will caufe the lead to fall 16 
 fee: in a fecond ; but if the body has already fallen 16 
 feet, we know that it is then moving with the velocity 
 of 32 feet per fecond. And the faft is, that it will fall 
 48 feet farther. in the next fecond, and will have acq\ii- 
 rcd the velocity of 64 feet per fecond. It has there- 
 fore received an augmentation of 3.1 feet of velocity by 
 the adlion of gravity during the 2d fecond ; and gravi- 
 ty is in fa£l a conltant force, caufing equal increments 
 of velocity in equal times, however great the velocities 
 may be. ^ It does not atl like a llream of fluid, whofe 
 impulfe or aftiun diminilhes as the folid body withdraws 
 from it by yielding. 
 
 But fuppofing that we have not compared the incre- 
 ments of velocity uniformly accjuired during equal 
 times, in what manner fliall we meafure the accelerating 
 forces ? In fuch a cale, that force muft be accounted 
 double which generates the fame velocity, by afting 
 uniformly during half the time ; for when the force is 
 fuppofed invariable, the changes of velocity which it 
 produces are proportional to the times of its aflion ; 
 therefore if it produces an equal velocity in half the 
 time, it will produce a double velocity in an equal 
 time, and is therefore a double force. The fame may 
 be faid of every proportion ot time in which an equal 
 change of velocity is produced by the uniform aftion 
 of an accelerating force. The force muft be accounted 
 greater in the fame proportion that the time required 
 for the produAion of a given velocity in a body is Icfs. 
 Hence we infer, that accelerating forces are iti'verfely pro- 
 portional to the limes in iv/jic/j a given change of •velocity 
 is produced by their uniform aBion. 
 
 By combining thefe two propofitions we eftablifh this 
 
 g general theorem : 
 
 ileafure ol^^'^'^^'i'^l'^g f"'''^^^ '"'^ proportional to the changes of ve- 
 
 ccelera- locily ivhich they produce in a body by their uniform 
 
 aBion dircdly, and to the times in •which thefe changes 
 
 are produced inverfely. 
 
 If, therefore, A and a are the forces, V and 1/ the 
 changes of velocity, and T' and /' the portions of time 
 in which they are uniformly produced, we iiave 
 
 V' 11' 
 A:a = \-'t':-o'r, = Y':T 
 
 ■u' 
 And a = -r- 
 
 ing force, 
 
 The formula a 
 
 I' 
 
 is not reftrlfted to any parti- 
 
 cular magnitude of 1/ and /'. It is true, therefore, 
 when the portion of time is dimlniflied with(*it end ; . 
 for flnce the adtion is fuppofed unifdrm, the increment 
 of velocity is leffened in the fame proportion, and the 
 
 value of the frafkion -;- remains the fame. The cha- 
 raflers or fymbols v' and /' are commonly ufed to ex- 
 prefs jfn/Vf portions of -u and /. The fymbols v and t 
 are ufed by Newton to exprefs the fame things taken in 
 the ultimate or limiting ratio. They are ufually confi- 
 dered as inde/inilely fmall portions of v and t. We fhall 
 
 abide by the formula a = -r' 
 ■ t 
 SuFfL. Vol. I. Fart II. 
 
 M I C S. ' 52(; 
 
 It muft always be kept in mind, that v and / arc ab- Of Acccle- 
 ftrail numbers ; and that v refers to fome unit of fpace, f '"ng jnd 
 fuch as a foot, an inch, a yard ; and that / refers to i^orce- 
 fome unit of time, fuch as an hour, a minute, a fecond ; r 
 
 au(l ef[)ccially that a is the number of the fame units 8j 
 of fpa.-e, whicli will be unifurmly defcribcd in one unit'*""*''* 
 of the time with the velocity generated, by the force],;.* "'^""* 
 adliiig uniformly during that unit. It is twice the 
 fpace adually defcribcd by the body during that unit 
 when impelled from reft by the accelerating force. It 
 is neceffary to keep hold of thefe clear ideas of the 
 quantities expreffed by tlie fymbols. 
 
 On the other hand, when the meaUire of the accelera- Metfure of 
 ting force is previoufly known, we employ the theorem' '■^'■'/^K'^ "^ 
 a t' =1 v ; that is, the addition made to the velocity*" '"^"^' 
 during the whole, or any part, of the time of the action 
 of the force is obtained by multiplying the acceleration 
 of one unit of lime by the number of fuch units con- 
 tained in /'. 
 
 Thefe are evidently leading theorems in dynamics ;'riif''eraea. 
 becaufe all the mechauical powers of nature come un- ^^^'^*' 
 der the predicament of accelerating or retarding forces. '.^.,'u,(j 
 It is the coUeftion of thefe in any fubjcil, and the man- pan of our 
 ner in which they accomjjany, or are inhereiU in it, knowledge 
 which determine the mechanical charafter of that fub-°'. '''''^'^^''''- 
 jeft ; and therefore the phenomena by which they arCj,.^^ 
 brought into view are the the charafteriltic phenomena. 
 Nay, it may even be queftioned, whether the phenome- 
 na bring any thing more into view. This force, of which 
 we fpeak fo familiarly, is no objedl of diftinft contem- 
 plation ; it is merely a fomething that is proportional 
 
 to — And when we obferve, that the — , found in 
 
 the motions that refult from the vicinity of a body A, 
 
 is double of the J^, which refults from the vicinity of 
 
 t 
 another body B ; we fay that a force refides in A, and 
 that it is double of the force refiding in B. The ac- 
 celerations are the things immediately and truly ex- 
 prefted by thefe fymbols. And the whole fcience of 
 dynaniics may be completely taught without once em- 
 ploying the word force, or the conception which we 
 imagine that we form of it. It is of no ufe till we come 
 to lludy the mechanical hiftory of bodies. Then, in- 
 deed, we muft have fome way of exprelCng the fact, thai 
 
 . ji feet 
 an acceleration = -^ ; — is obferved in every thing on 
 
 the furface of this globe ; and that an acceleration := 
 4! 8 feet , 
 
 V' 
 
 is obferved over all the furface of the fun. Thefe 
 
 fafts are charafteriftic of tliis earth and of the fuu ; and 
 we exprefs them ihortly by faying, that fuch and fuch 
 forces rcfide in the earth and in the fun. It will pre- 
 ferve us from many millakes and puzz-ling doubts, if 
 we reiolutely adhere to this meaning of the tevm force; 
 and this will carry mathematical evidence through the 
 whole of our inveiligations. s^ 
 
 As velocity is not an immediate obiedl of contem-Ai otiier 
 plation, and all that we obferve of motion is a fpace'"' futeof 
 and a time, it may be proper to give an cxprellior 01, . 
 this meafure of accelerating force which involves no 
 other idea. Suppofing the body to have been previ- 
 
 oufly at reft, we have a = — . Multiply both parts 
 
 cce era- 
 ; force 
 
 3X 
 
 of
 
 53^ 
 
 D Y N A 
 
 of accelera- 
 ting force. 
 
 Of Acce'.c-of the fradioi) by t, which does not change its value, 
 rating and ^ ^ 
 
 Retarding and we have J = — . But v t zz s ; and therefore a 
 Farces. • i 
 
 The formula a = -j is equivalent to the proportion 
 
 /» : I = s : a ; and a would then be t}>e fpace through 
 which the accelerating force would impel the body in 
 one unit of the time /. But this is only half of the 
 meafure of the velocity which the accelerating force ge- 
 nerates during that unit of time. For this reafon we 
 did not exprefs the acccleraring force by an ordinary 
 equation, but ufed the fymbol ==. In this cafe, there- 
 fore, of uniform adlion, we may exprefs the accelera- 
 
 2 J- , 
 
 ting force by a zz —r- 
 
 The fcllovi'ing theorem is of (lill more extenfive ufe 
 
 gr in all dynamical difqiiilitions. 
 
 Mod Kent- ylccelerating forces are proportional to the momentary in- 
 
 ral meafure cremeuts of the fquares of the velocities direPdy, and as 
 
 the fpaees along ijhich they are uniformly acquired in- 
 
 •verjely. 
 
 Let AB, A'C, and AD (fig. 14.), be three lines, 
 defcribed in the fame or equal times by the uniform ac- 
 tion of acceleratirtg forces ; the motions along thefe 
 lines will be uniformly accelerated, and the lines them- 
 felves will be proportional to the forces, and may be 
 employed as their meafurcs. On the greateft of them 
 AD, defcribe the femicircle ABCD, and apply the 
 other two lines A'B, A'C as chords AB, AC. Draw 
 EB, FC perpendicular to AD. Take any fmall por- 
 tions B i, C f of AB and AC, and draw i e, cf per- 
 pendicular to AD, and E h and F i parallel to AB 
 and AC. 
 
 Then, becaufe the trian<(les DAB and BAE are fi- 
 milar, we have AD : AE'= AD" : AB'. And be- 
 caufe AD is to A B as the velocity generated at D is 
 to the velocity generated at B (the times being equal), 
 we have AD to AE as the fquare of the velocity at 
 D to the fquare of the velocity at B ; which we may 
 exprefs thus : 
 
 AD: AE = V", D : V", B. 
 For the fame reafons we liave alfo 
 
 AD : AF = V, D : V% C. Therefore 
 AE : AF = VS B : V% C. 
 But becaufe in any uniformly accelerated motion, 
 the fpaees are as the fquai-es of the acquired velocities, 
 we have alfo 
 
 AE: Ae = VSB : V i, and 
 AF : A/ = V, C : V c. 
 Therefore E e is to F/as the increment of the fquare 
 of the velocity acquired in the motion along B i to the 
 increment of the fquare of the velocity acquired along 
 C c. 
 
 But, by fimilarity of the triangles ABD and 'E e h, 
 we have 
 
 AB : AD = E 1; : E A ; and, in like manner, 
 AD : AC zz Yi :¥f. Therefore 
 AB : AC = E^ X Fi : F/X E/j. 
 
 Now AB and AC are proportional to tfie forces 
 which accelerate tfie body along the lines A'B and 
 A'C ; E e and F/ are proportional to the increments 
 of the fquares of the velocities acquired in the motions 
 
 M 1 C S. 
 
 along the portions B I and C c ; and E h and F i are Of Accde. 
 
 equal to thofe portions refpedlively. The ratio of AB '■"tini? and 
 
 to AC is compounded of the dirett ratio of E «• to F/; "p^"'','''^- 
 
 and the inverfe ratio of JL h to T i. The proportion . , ' t 1 
 
 is therefore demonftrated. 
 
 The proportion may be cxprefTed thus : 
 
 Ee Ff . ; 
 
 AB : AC =. p-T : y-,, and may be exprcflcd by 
 
 the proportional equation AB = ^y or, fymbolieal- 
 
 Remark. Becaufe the motion along any of thefe ^.l- is but 
 three hncs is uniformly accelerated, the relation between one-half 
 fpaees, times, and velocities, may be reprefentcd by' "'"* 
 means of the triangle ABC (fig. 15.) ; where AB re-of.^,! 
 prefents the time, BC the velocity, and ABC the fpace. 
 If BC be taken equal to AB, the triangle is half of 
 the fquare ABCF of the velocity BC ; and the triangle 
 ADE is half of the fquare ADEG of the velocity 
 DE. Let D </ and B 3 be two moments of time, 
 equal or unequal. Then D ^^ E and B I c C are half 
 the increments ol the fquares of the velocities DE and 
 BC, acquired during the moments D </ and B b. It 
 was demonftrated, that the ratio of the area T) d e E to 
 the area B i f C is compounded of the ratio of DE 
 to BC, and the ultimate ratio of D ^/ to B I/. But D d 
 and B I are rcfpeflively equal to ( e and « c. There- 
 fore D (/f E is to B 3 £ C, in the ratio compounded of 
 the ratio of DE to BC, and the ultimate ratio of f «• to 
 K c. If we reprefent DE and BC by V and v, then 1 e 
 and « c muft be repreftnted by V' and v , the incre- 
 ments of V and -v ; and then the compounded ratio will 
 be the ratio of VV to v -v' ; and if we take the ulti- 
 mate ratio of the moments, and confequently the ulti- 
 mate ratio of the increments of the velocities, we have 
 the ratio of VV to v -v. If, therefore, V and -v^ re- 
 prefent the fquares of the velocities, VV and v v will 
 reprefent not the increments of thofe fquares, but halt 
 the increments of them. 
 
 We may now reprefent this propoCtion concerning 
 accelerating forces by the proportional equation a == 
 
 ^-2L ; and we mull confider this as equivalent with a := 
 
 s 
 
 V^ — 1>^ 
 — j-^ r ; keeping always in mind, that a, V, and v, 
 
 relate to the fame units of time and fpace, and that a is 
 
 that number of units of the fcale on which S and s are 
 
 meafured, which is run over in one unit of time. 
 
 This will be more clearly conceived by taking an Meafmc of 
 
 example. Let us afcertain the acceleratl-e power ofg'^X'''' 
 
 gravity, fuppofinpf it to adt uniformly on a body. Let*^""' "^ 
 P, r ' , r > • r 1 L ■ ■ r , as an acce- 
 
 the fpaees be meafured in feet and ttie time in feconds. i.-rming 
 
 It is a matter of obfervation, that when a body has fal- force. 
 Icn 64 feet, it has acquired a velocity of 64 feet per 
 fecond : and that when it has fallen 144 feet, it has ac- 
 quired the velocity of 96 feet per fecond. We want 
 to determine what velocity gravity communicated to it 
 by afting on it during one fecond. We have V =: 
 9216, and ■zjJ = 4096 ; and therefore V" — ©•» = 5120. 
 S = 144, and s = 64, and S — s zz 80, and 2 (S — s) 
 
 5120 
 = 160. Now a = ~TKa> ^2'^- Therefore gravi- 
 ty
 
 D Y N A 
 
 jf Aceele- ty has generated the velocity 32 feet per fecond by 
 rating an i j£^;„g unifonnly during one fccoiid. 
 
 The nugmrntdlion of the fquure of the wfncity is pro- 
 pm-tional to the force and to the fpace jointly. I'or, bccaiilc 
 
 Uelariliiig 
 Forces. 
 
 8b. 
 
 — -: — , we have a s :=. vv. 
 
 Theorems 
 refpeiJliiii; 
 relauliijg 
 forces 
 
 Thus we learn, that a given force ailing uniformly 
 on a bodv along a given fpace, produees the fame in- 
 crement of the fquare of the velocitVi whatever the pre- 
 vious velocity may have been. Alfo, in the fame man- 
 ner as we formerly found that the augmentation of the 
 velocity was proportioned to the time during which the 
 force has acted, fo the augmentation of the fquare of 
 the velocity is proportional to the fpace along which it 
 h<is acted. 
 
 It is pretty plain, that all that we have faid of the 
 uniform aftiou of an acccleniting force may be aifumed 
 of a retarding force, taking a diminution or decrement 
 of velocity in place of an increment. A uniformly re- 
 tarded motion is that in which the decrements of velo- 
 city in equal times are equal, and the whole decrements 
 are proportional to the whole times of aftion. Such a 
 motion is the indication of a conftant or invariable force 
 afting in a direftion oppofite to that of the motion. 
 We conceive this to be the cafe when an arrow is fhot 
 perpendicularly upwards ; its weight is conceived as a 
 force continually prcfling it perpendicularly downwards. 
 In fuch motions, however great the initial velocity 
 may be, the body will come to reft ; becaule a certani 
 determined velocity will be taken from the body m 
 each equal fuccedive moment, and foine multiple of 
 this will exceed the initial velocity. Therefore the 
 velocity will be extinguiflied before the end of a 
 time that is the fame multiple of the time in which 
 the velocity was diminiflied by the quantity above men- 
 tioned. It is no lefs evident, that the time in which 
 any velocity will be extinguiflied by an oppoihig or re- 
 tarding force, is equal to the time in which the fame 
 force would generate this velocity in the body previ- 
 oufly at reil. Therefore, 
 
 1. The times in which different initial velocities will 
 be extinguiflied by the fame oppufing force are propor- 
 tional to the initial velocities. 
 
 2. The diltances to which the body will go till the 
 e.Ktinftion of its velocity are as the fquares of the initial 
 velocities. 
 
 3. Tliey are alfo as the fquares of the times elapfed. 
 4 The diilance to which a body, projedted with any 
 
 velocity, will go till its motion be extinguiflied by the 
 uniform aftion of a retardinjj force, is one half of the 
 fpace which it would defcribe uniformly during the 
 fame time with the initial velocity. 
 
 Forces gc- It very rarely happens, that the force which accele- 
 nerally va. rates the body aifts uniformly, or with an unvaried in- 
 their'^imen t^"f'ty- The attraction of a magnet, for example, in- 
 fity. creafes as the iron approaches it. The preffure of a 
 
 fpring diminifhes as it unbends. The impulfe of a ftream 
 of water or wind diminifhes as the impelled furface re- 
 tires from it by yielding. Therefore the effefts of ac- 
 celerating forces are very imperfeftly explained, till we 
 have fliewn what motions refult from any given varia- 
 tion of force, and how to difcover the variation of force 
 from the obferved motion. This laft queftion is per. 
 
 M I C S. 53' 
 
 haps the moll important In tlic ftudy of mechanical na-Of Acceie- 
 ture. It is only thus that we learn what is ufually call- |^^'|.j"f^ii" 
 ed the nature of a mechanical force. This chiefly con- forces. 
 fills in the relation fiiblilling between the inteiifity of i— y— J 
 the force and the diilance of the fublfance in which it 
 refides. Tlius the nature of that power which pro- 
 duces all the planetary motions, is coiifidered as afcer- 
 tained when we have demonftiated that its preffure or 
 intenlity is inverfely as the fpiare of the diilance fron> 
 the body in which it is fupijofcd to refide. 
 
 Acceleration expreffes fome rdatioii of the vcl'icity 
 and time. This relation may be geometrically exprcf- 
 fed in a variety of ways. In figure 13. the uniform 
 acceleration or the unvaried relation between the velo- 
 city and the time is very aptly expreffcd by the con- 
 flant ratio of the ordinates and abfciffes of the triangle 
 rt ? ». The ratio <jf d S to a J is the fame with that of 
 c , to a e, or that of/ f to af, &c.; or the ratio of the 
 increment of velocity ^ ' to the increment of the time 
 ii ^ or b c, or that of i f to i i, &c. This ratio ■^^■■fi ■-■' 
 
 «7- 
 
 88. 
 
 89. 
 
 is equivalent to the fymbol _- 
 
 t 
 
 But when the fpnces dcfcribed in a varied motion 
 are reprefented by the areas bounded by a curve line 
 h k 0, we no longer have that conftant ratio of the in- 
 crements of the ordinates and abfciffis. 50 
 
 Therefore in order to obtain meafurcs of the acce- Their nicv- 
 leratinsr forces, or at leaft of their proportions, let iliefi"-csin 
 
 , . . & ,,- \ r 1 1- ; ; • '"tn cafes 
 
 abfciflaa^^ (hg. 13.) of the line hio again repre-^^^ ^,„^,j,, 
 
 fent the time of a motion. But let the areas bounded ej? Theo- 
 by parallel ordinates now reprefent the velocities, thatrcmsof 
 is, let the whole area increafe during the time a ^ ^^ nioft exteu- 
 the fame rate with the velocities of the motion along 
 the line AG. In this cafe the ordinates hi, c i, d I, 
 Sic. will be as the accelerations at the inftants b, c, d, 
 &c. or in the points E, C, D, &c. 
 
 This is demonftrated in the fame way as the former 
 propofition (n° 72.). If the accelerating force be fup- 
 pofcd conftant during any two equal moments b c and 
 f g, the reftangles b c p t and/^.v s would exprefs the 
 increments of velocity uniformly acquired in equal 
 times, and their bafes c p and/j would have the ratio 
 of the accelerations, or of the accelerating forces. But 
 as the velocities cxprcfTed by the ligure increafe fafter 
 than the times during every moment, the force at the 
 inftant c is to the force at the inftant / in a greater ra- 
 tio than that of c /> to f s ; but, for limilar reafons, it 
 is in a lefs ratio than that oi c q tofr; and therefore 
 (as in the other pro]>ofition) the force at the inftant c 
 is to the force at the inrtant/as c k tofn. 
 
 Cor. Becaufe c p is to f s in the ratio compounded 9'> 
 of the direft ratio of the reftangle c p t b to the reA- 
 angley J x g, and the inverfe ratio of the altitude b c to 
 the altitude fg ; and becaufe thefe reftanglcs are pro- 
 portional to the increments of velocity, and the ulti- 
 mate ratio of the altitudes is the ultimate ratio of the mo- 
 ments or increments of the time — we mutl fay, that tic 
 accelerating forces (that is, their inteti/ities or prejjiires 
 producing acceleration) are dircSly as the incrtmenis 
 of -velocity, and inverfely as the increments of the times : 
 Which propofition may be exprefted, in regard to two 
 accelerations A and a, by this analogy ; 
 
 V V 
 A:<J = ^ : — . 
 T / 
 
 3X2 Or
 
 5^2 
 
 DYNAMICS. 
 
 Fore.-*. 
 
 Of Acccle- 
 
 Taiinij ar.j Q^ j, jj^g proportional eq-.ialion a = -:-. Alfo a t 
 Keurdiiig V I- I- J . ^ 
 
 I ■=^ V, and /ij ; =: ii'. Aud thus do thcfe theorems ex- 
 tend even to the cafes where there cannot be obferved 
 an immediate mearurt, either of velocity or of accelera- 
 tion ; beca\ife neither the fpace nor the velocity in- 
 creafes uniformly. 
 
 See Bar- 
 
 Cjeointtr. 
 
 yallim. 
 
 The theorem « = — r- is employed when we would 
 
 difcover the variation in the i^itenfity of fome natu- 
 ral power. We obferve the motion and reprcfent it 
 by a figure analogous to fig. 13. where the ahfcifl'a re- 
 prefents the times,- and the area is made to increiife at 
 the fanie rate with the fpaces defcribed. Then the or- 
 dinates will reprefent the velocities, or have the propor- 
 tion of the velocities. Then we may draw a fecoiid 
 curve on the other fide of the fame abfciffa, fuch that 
 the srcas of this lail curve (hall be proportioned to the 
 ordinates of the firft. The ordinates of this lad curve 
 are proportional to the accelerating forces. 
 91. On the other hand, when we know from other cir- 
 
 ■ cumftances that a force, varying according to fome 
 known law, adts on a body, we can determine its mo- 
 tion. The intenfily of the force in every inilant being 
 known, wc can draw a line io related to another line 
 reprefenting the time that the ordinates fhall be pro- 
 portional to\he forces: The areas will be proportional 
 to the velocities. Wc can draw another curve to the 
 fame abfcifs, fuch that the ordinates of this Ihall be pro- 
 portional to the areas of the other, that is, to the velo- 
 cities of the motion. The areas of this lecond curve 
 will be proportional to the fpaces defcribed. 
 
 We muft now obferve, that all that has been 
 faid concerning the effecls of accelerating forces con- 
 tinually varying, relates to changes of motion, indepen- 
 dent of what the abfolute motions may be. The areas 
 byvi-hich of the line whofe ordinates reprefent the velocities do 
 "'""'"'"''' not neceffarily reprefent the fpaces defcribed, but the 
 tneJiatelythc'-^^^?,^ made on the fpaces defcribed in the lame time, 
 cperatior. cfnot the motions, but the changes of motion. If, in- 
 natural deed, the body be fuppofed to be at reft when the for- 
 powers. j,gg begin to aft, thefe areas reprefent the very fpaces 
 that are paflcd over, and the ordinates are the very ve- 
 locities. In every cafe, however, the accelerations are 
 the real increments of the velocities. 
 
 This circumftance gives a great extenfion to our the- 
 orems, and enables us to afcertain the difturbances of 
 any fpecies of regular motion, apart from the motions 
 themfelves, and thus avoid a complication which would 
 frequently be inextricable in any other way. And this 
 procefs, which is merely mathematical, is perfeftly con- 
 formable to mechanical principles. It is in faft an ap- 
 plication of the dottrine of the compofition of motion ; 
 a doftrine rigidly demonllrated when we meafure a me- 
 chanical force by the change of motion which it pro- 
 duces. Acceleration is the continual compofition of a 
 new motion with the motion already produced. 
 No finite We may learn from this inveftigation of the value of 
 
 change of ^^ accelerating force, that no finite change of velocity is 
 velocity can _,->.■ ■ n i 1 ci' c 1 • 
 
 beproducel^"'-''^^^'^ m an inltant by the aition ot an accelerating 
 
 inaninftantforce. When the fig. 13. is ufed for the Icale of acce- 
 by any ic- lerations, and they aire reprefented by the ordinates of 
 celera Jig ^^ y^^^ j^ j, ^^ ^-^^ Increment of velocity is reptcfented 
 
 93 
 All thefe 
 theorems 
 relate to 
 cban<res of 
 velocity; 
 
 by an area, that is, by a flip of the whole area ; which 
 flip mntl have fome altitude, or mull occupy fome por- 
 tion of the abfcifl'a which reprefcnts time. Some por- 
 tion of time, however fmall it may be, muft elapfe be- ' 
 fore any meafurable addition can be made to the velo- 
 city. The velocity muft change continually. As no 
 motion can be conceived as inftantaneous, becaufe this 
 would be to conceive, that in one inftant the moving 
 particle is in every point of its momentary palli ; fo no 
 velocity can change, by a finite quantity, in one inftant; 
 becaufe this would be to conceive, that in that inilant 
 the particle had all the intervening velocities. The 
 inftant of change is at once the laft inftant of the pre- 
 ceding velocity, and 'the firft of the fucceeding, and 
 therefore muft beloiig to both. This cannot be con- 
 ceived, or is abfurd. As a body, in pafting from one 
 part of fpace to another, muft pafs in fuccellion through 
 all the intermediate places ; fo, in pafliiig from one ve- 
 locity to anotl.er, it muft in fucceffion have ?.ll the in- 
 termediate velocities. It muft be continually accelera- 
 ted ; we muft not fay gradually, however finall the 
 fteps. 
 
 But to return from this digrefTion : 
 The moft h-equent cales which come under examina- 
 tion do not Ihew us the relation between the forces and 
 times, but the relation between the forces and fpaces. 
 Thus, when a piece of iron is in the neighbourhood of 
 a magnet, or a planet is confidered in the neighbour- 
 hood of the fun, a force is afting on it in every point 
 of Its path, and we have difcovered that the Inteiifity 
 of this force varies in a certain proportion. Thus, a 
 fpring varies in its preffure as it unbends ; gunpowder 
 preffes lefs violently as it expands, &c. &c. 
 
 Our knowledge is generally confined to fome fuch 
 effeft as this. We know, that while a body is moving 
 along a line ADE (fig. 16.), it is urged forward by a 
 force, of which the intenfity varies in the proportion 
 of the ordinates BF, CG, DH, EI, &:c. of the line 
 FGHI. 
 
 To inveftlgate the motion or change of motion pro- 
 duced by the aftlon of this force, let CD be fuppofed 
 a very fmall portion of the fpace s, which we may ex- 
 prefs by s' . E>raw GK perpendicular to DH. Then, 
 if we fuppofe that the force a6ts with the unvaried in- 
 tenlity CG through the whole fpace CD, the reftangle 
 CDKG will exprels half of the increment of the iquare 
 of the velocity (n° 85 ). We may fuppofe that the 
 force afts uniformly along the adjoining fmall fpace 
 Dr with the intenfity DH. The reftangle DH r 
 will in like manner exprefs another half increment of 
 the fquare of the velocity. And in like manner v/c 
 may obtain a fuccefiion of fuch increments. The ag- 
 gregate or fum of them all will be half the difference 
 between the fquare of the velocity at B and the fquare 
 of the velocity at E. 
 
 If we employ f to exprefs the indetermlned or va- 
 riable intenfity of the accelerating force, and i> to ex- 
 prefs the variable velocity, and ■» its increment uniform- 
 ly acquired ; then the reftangle CDKG will be ex- 
 prefTed by f s'. We have feen that this is equal to ■v-J. 
 Therefore, in every cafe where we can tell the aggre- 
 gate of all the quantitiesy J, it is plain that we will ob- 
 tain half the diflerence between the fquares of the ve- 
 locities in B and E, on the fuppofition that the intenfi- 
 ty of the force was conftant along each little fpace, and 
 
 varied 
 
 Of Aceele 
 
 raiirj; and 
 
 Retarding 
 
 Forces. 
 
 . 5* 
 More con* 
 
 venient 
 
 manner of 
 
 confiderirg 
 
 the a(51ion 
 
 of force?, 
 
 and more 
 
 Irtciueiiily 
 
 con'ing in«- 
 
 to view.
 
 l'3f Accele- 
 
 ra'ini; and 
 
 Retariling 
 
 forces. 
 
 95 
 
 Mnft im- 
 portanc 
 theorem 
 / Keiutons 
 
 I. 39-) 
 
 9«. 
 
 C«nverfe. 
 
 D Y N A 
 
 varied by ftarts. Then, by iiicreafing the number, and 
 (limi'iilhiiig the magnitude, of thofe little portions of 
 tiie fpace without end, it is evident that we terminate 
 in the eMprcffion of the real ftate of the cafe, i. e. of a 
 force varying conlinually ; and that in this cafe the ag- 
 gregate of thefe rciJtangles occupies the whole area 
 AEIF, and is equivalent to the fluent of/ J, or to the 
 fynibol Ifs, ufed by the foreign mathematicians to ex- 
 
 prefs this fluent, whicli they indeed conceive as an ag- 
 gregate of fnia'.l reftangles f s. And we fee that this 
 area expreflTes half of the augmentation of the fquare of 
 the velocity. Therefore, 
 
 If the abfciffa AE (fig. l6. ) of a line FGl is the path 
 along "which a body is urged ly any accelerating force, and 
 if the ordinates BF, CG, DH, i^c. are proportional to 
 the forces a&ing on the points B, C, 1), He. the intercepted 
 aieas BCGF, BEIF, i^c. are proportional to the augmen- 
 tations of the fquare of the •ve'ocity. 
 
 Obferve that the areas BCGF and DEIH are alfo 
 proportional to the augmentations made on the fquares 
 of the velocities in B and D. 
 
 Obferve alfo, that it is indifferent what may have 
 been the original velocity. The aftion of the forces re- 
 prefented by the ordinates make always the fame addi- 
 tion to its fquare ; and this addition is half the fquare 
 ot the velocity which thole forces would generate in 
 the body by impelling it from relt in the point A. 
 
 Lailly, on this head, obferve, that we can ftate what 
 conllant or variable force will make the fame augmen- 
 tation of the fquare of the velocity by impelling the 
 body uniformly along the fame fpace BE ; or along 
 what fpace a given force mutt impel the body, in order 
 to produce the fame increafe of the fquare of its velo- 
 city. In the firft cafe, we have only to make a rect- 
 angle BEN f, equal to the area BEIF, and then B f is 
 the intenfity of the conftant force wanted. In the fe- 
 cond cafe, in which the force EO is given, we muil 
 make the rectangle A=<OE equal to the area BEIF, 
 and AE is the fpace required. 
 
 The convcrfe of this propofition, -viz,. If the areas 
 
 M I C S. 5^3, 
 
 to the forces afting at B, D, E, F, &c. ; \ctfhi be Of Accele- 
 another line fo related to ABE, that C^ is to Ei in "^a'ii'B »"<! 
 the inverfe fubduplicate ratio of the area BFGC to '^"orc«'* 
 the area BFIE ; or, to exprcfs it more generally, '"t ■ ' ■ 
 
 the fquares of the ordinates to the Wnefg i be inverfely, 
 as the areas of the line FHI intercepted between thefa 
 ordinates and the firll ordinate drawn through B ; tlien 
 the times of the bodies moving from a ftate of reft in 
 B are as the intercepted areas of the curve fg ,'. 
 
 For let CD and E ^ be two very ftnall portions of 
 the fpace defcribed in equal times. They will he ulti- 
 mately as the velocities in C and E. The area FBCG 
 is to the area FBEI as the fquare of E/ to the fquare 
 of C^ (by conftrudtion) ; but the area FBCG is to 
 FBEI as the fquare of the velocity at C is to the 
 fquare of the velocity at E (by the propofition); 
 therefore the fquare of the velocity at C is to the 
 fquare of the velocity at E as the fquare of E i to 
 the fquare of C^ ; therefore E i is to C g as the ve- 
 locity at C to the velocity at E, that is, as CD to Ee : 
 but fince E i : C^' = CD : E e, we have Ei X Ee = 
 Cg X CD, and the elementary redtangles Cg ID and 
 Ei me are equal, and may reprefent the equal moments 
 of time in which CD and E e were defcribed. Thus 
 the areas of the line fg I will reprefent or exprefs the 
 times of defcribing the correfpouding portions of the 
 abfciffa. 
 
 We may exprefs the nature of this fcale more briefly 
 thus. Let BE be the fpace defcribed with any varied 
 motion, and fgl a curve, fuch that its ordinates are in- 
 verfely as the velocities in the different points of the 
 ablcilTa, then the area will be as the times of defcribing 
 the correfpouding portions of the abfciffa. 
 
 In all the cafes where our mathematical knowledge p^-niples 
 enables us to aflign the values of the ordinates of the fi- of the ap 
 gure i6, we can obtain the law of action of the forces, l'"'^''-''''" <■'- 
 or the nature of the force; and where we can affign ''^ ^•'' 
 the value of the areas from our knowledge of the pro- 
 portions of the ordinates or forces, we can afcertain the 
 velocities of the motion. We ihall give an example or 
 two, which will jhcvi' the way in which we avail our 
 
 are as the increments of the fquare of the •velocity, the or- felves of the geometrical properties of fi'fure, in order 
 j;_-..- -. ,L. r. :. r.i.. j a.._. .i :._ ..l _ ..,. _r ....... ^i. . _ir_ n c . • i .- ° 
 
 , 98 
 
 SMtes of 
 
 force, ve- 
 locity, ac- 
 
 dinates are, as the forces, is eafily demonflrated in the 
 fame way ; for if the elementary areas CDKG and 
 EIM e reprefent increments of the fquares of the velo- 
 city, the accelerating forots are in the ratio compound- 
 ed of the dircdt ratio of thefe rectangles and the in- 
 verfe ratio of their altitudes, becauie thefe altitudes are 
 the increments of the fpace (n° 85.). Now the bafe 
 CG of the rectangle CDKG, is to the bafe EI of the 
 reftangle EIMf in the fame compounded ratio ; there- 
 fore the force in C is to the force in E as CG to EI. 
 
 The line hio (tig. 13.) was called by Dr Barrow 
 (who firft introduced this extenfive employment of mo- 
 tion into geometry), the SCALE ef •uelocitiis ; and the 
 
 ' ' ce/erations. Hermann, in his Phoroncm'ia, calls it the 
 
 We fliall retain this name, and we may 
 13. the fcale o/" accelerations, when the 
 
 *9- 
 
 fcale of forces. 
 call h I of fig 
 
 areas reprefent the velocities. Sir Ifaac Newton added 
 another fcale of very great ufe, viz. a fcale 0/ times. It 
 is conftruiited as follows. 
 
 Let ABE (fig. 16.) be the line along which a body 
 is accelerated, and let FHI be the fcale of forces, that 
 is, having its ordinates FB, HD, IE, &c. proportional 
 
 to afcertain the effefts of mechanical forces. 
 
 1. Let the accelerating force which impels the body 
 along the line AB be conftant, and let the body be 
 previoufly at reft in B ; the line which bounds the or- 
 dinates that reprefent the forces muft be fome line 
 fHN parallel to AB. The area BDH j> is to the area 
 BEN »- as the fquare of the velocity at D to the fqu;ire 
 of the velocity at E. Thefe areas, hnving equal bales ■ 
 DH and EN, are as their altitudes BD and BE ; that 
 is, the fpaces defcribed are as the fquares of the ac- 
 quired velocities. And we fee that this charaiteriftic 
 mark of uniformly accelerated motion is included in this 
 general propofition. ,^, . 
 
 2. Let us fuppofe that the body is impelled from A Hx.uiiple" 
 (fig. 17.) towards the point C, by a fTirce proportional '^'•''^""'' "^ 
 to its diftanee from that point. This force may be re- ~" 
 prefentcd by the ordinates T).\, EB, e b, &c. to the a 
 ftraight line DC. We may take any magnitude of 
 thefe ordinates; that is, the line DC may make anv angle 
 with AC. It will fimplify the inveftigation if we 
 make the firft force AD^^AC. About C defcribe 
 the circle AH n, cutting the ordinate EB in F; let 
 f i be auothev ordiaute, catting the circk in/ very near 
 
 ■ culiar 
 '"ni rrt. 
 ancc. .
 
 SU D Y N A 
 
 Of Accele to V ; draw CH perpendicular to AC, and make the 
 rati.ii; and g^^.^ ^ A - fF, and draw he parallel to HC ; join 
 Force"^ FC and DH, and draw F^ perpendicular to/A. Let 
 * IML be another ordinate. 
 
 The area DADE is to the area DAKL as the 
 fqnare of the velocity at B to the fquare of the velocity 
 at K. But DABE is the exccfs of the triangle ADC 
 above the triangle EBC, or it is half of the exccfs of the 
 fqiiare of CA or CF above the fquare of CB, that is, 
 half the fqnnie of BF. In like manner, the area DAKL 
 is equal to half the fquare of KM ; but halves have the 
 fame ratio as the integers ; therefoie the fquare of BF 
 is to the fquare of KM as the fquare of the velocity at 
 B to the fquare of the velocity at K ; therefore the ve- 
 locity at B is to the velocity at K as BF is to KM. 
 The velocities are proportional to the fines of the arches 
 of the quadrant AFH defcribed on AC. 
 
 Cor. I. The final velocity with which the body ar- 
 rives at C, is to the velocity in any other point B as 
 radius to the fine of the arch AF. 
 
 Cor. 2." The final velocity is to the velocity which 
 ■ the body would acquire by the uniform action of the 
 initial force at A as « to \^2 ; for the reftaugle DA 
 CH exprefTcs the fquare of the velocity acquired by 
 the uniform aflion of the lorce DA ; and this is double 
 of the triangle DaC ; therefore ihe fquares of thele 
 velocities are as i and 2, and the velocities are as ^i 
 and i/2, or as i to i/z. 
 
 C r. 3. The time of defcribing AB is to the time 
 of defcribing AC as the arch AF to the quadrant 
 AFH. 
 101. For when the arch F/ is dirainilhed continually, it 
 
 is plain that the triangle fi F is ultimately fimilar to 
 CFB, by reafon of the equal angles Cii (or CFB) 
 and fi F, and the right angles CBF and/F; ; there- 
 fore the triangles/;- F and CBF are alfo fimilar. More- 
 over, B i is equal to Y g, F/is equal to h H, which is 
 ultimately equal to f C ; therefore fince the triangles 
 J'gF and CFB are fimuar, we have F^ : F/=: FB : 
 FC, •= FB : HC ; therefore B i is to f C as FB to 
 HC, that is, as the velocity at B to the velocity at C; 
 therefore B b and c C are defcribed in equal moments 
 when indefinitely fmall ; therefore equal portions F/, 
 /} H, of the quadrant correfpond to equal moments of 
 the accelerated motion, along the radius AC ; and the 
 aiches AF, FM, MH, Sec. are proportional to the 
 times of defcribing AB, BK, KC, &c. 
 
 Cor. 4. The time of defcribing AC with the une- 
 oially accelerated motion, is to the time of defcribing 
 it uniformly with the final velocity as the quadrantal 
 arch is to the radius of a circle ; for if a point n~.ove in 
 the quadrantal arch fo as to be in F, /, M, H, &c. 
 when the body is in B, b, K, C, it will be moving 
 uniformly, becaufe the arches are proportional to the 
 times of dtfcribing thole portions of AC ; and it will 
 be moving with the velocity with which the body arrives 
 at C, becaufe the arch /} H is ultimately =: C c . Now 
 if two bodies move uniformly with this velocity, one 
 in the arch AFH, and the otlier in the radius AC, the 
 times will be proportional to the fpaces uniformly de- 
 fcribed ; but the time of defcribing AFH is equal to 
 the time of the accelerated motion along AC ; therefore 
 the propofition is manifeft. 
 
 Cor. J. If the body proceed in the line C a, and be 
 retarded in the fame manner that it was accelerated 
 
 M I C S. I 
 
 along AC, the time of defcribing AC unJfonnly with Of Aet«, 
 
 the velocity which it acquires in C is to the time of *■"''"?" 
 - - - . . T °eurdii 
 
 Forces 
 
 defcribing AC a with the varied motion, as the diame- ^"*"'" 
 
 «03. 
 
 ter of a circle to the circumference ; for becaufe thei, 
 momentary retardations at K', B', &c. are equal to the 
 accelerations at K and B, &c. the time of defcribing 
 AC a is the fame with that of defcribing AH a uni- 
 formly with the greateft velocity. That is, to the time 
 of defcribing AC uniformly as AH a to AC, or as 
 the circumference of a circle to the diameter. There- 
 fore, &c. N. B, In this cafe of retarding forces it Is 
 convenient to reprefent them by ordinates K'L, BE, 
 a D', lying on the other fide of the axis AC a ; and to 
 confider the areas bounded by thefe ordinates as fub- 
 traftive from the others. Thus the fquare of the velo- 
 city at K' is expreffed by the whole area DACK'L'D, 
 ihe part C'K'L being negative in refptft of the point 
 DAC. This obiervation is general (See alfo Optics, 
 n" 125, Etirycl.) 
 
 Cor. 6. The time of moving along KC, the half of 
 AC, by the uniform aflion of the force at A, is to that 
 of defcribing AC ti by the varied atlion of the force 
 directed to C, and proportional to the diltance from it, 
 as the diameter of a circle to the circumference; for 
 when the body is uniformly impelled along KC by the 
 conltant force IK, the Iquare of the velocity acquired 
 at C is reprefented by half the rcftangle IKCH, ami 
 therefore it is equal to the velocity which the variable 
 force generates by impelling it along AC (bv the way, 
 an important obiervation). The body will defcribe AC 
 uniformly with this velocity in the fame time tiiat it is 
 uniformly accelerated along KC. Therefore by Cor, 
 5. the propofition is manifeil. 
 
 Cor, 7. if two bodies defcribe AC and KC by the 
 action of forces which are every where proportional to 
 the diltanccs from C, tiieir final velocities will be pro- 
 portional to the dillances run over, and the times will 
 be equal. 
 
 For the fquares of the final velocities are proportional 
 to the triangles ADC, LKC, that is, to ACs KCs 
 and therefore the velocities are as AC, KC. The times 
 of defcribing AC and KC uniformly, with velocities 
 proportional to AC and KC, muil be equal ; and thefc 
 times are in the fame ratio [viz. that of radius to 3th 
 of the circumference) to the times of delcribing AC 
 and KC with the accelerated motion. Therefore, &c. 
 
 Thus, by availing ourfelves of the properties of the 
 circle, v^'e have dilcovered all the prc-perties or charac- 
 ters of a motion produced by a force always dirt died to 
 a fixed point, and proportional to the diltance from'it. 
 
 Some of thcfe are remarkable, luch as the lail corol- 
 lary ; and they are all important ; for there are innume- 
 rable cafes where this law of aftion obtains in Nature. 
 It is nearly the law of aftion of a bow ftiing, and of all 
 elaftic bodies, when their change of figure duriiig their 
 mutual aftion is moderate ; and it has been by the help 
 of this propofition, firit demonilrated in a particular 
 cafe by Lord Brouncker and Mr Huyghens, that we 
 have been able to obtain precife meatures of time, and 
 confequently of aftual motions, and confequently of any 
 of the mechanical powers of Nature. It is for this rea- 
 fon, as well as for the eafy and perfpicuous employment 
 of the mathematical method of proceeding, that we have 
 felefted it. 
 
 Initead of giving aoy more particular cafes, we may 
 
 obferve
 
 pro 
 
 DYNAMICS. S35 
 
 made on the fquare of tlic velocity of both bodies. Of Accele- 
 portional to any power whole index is n — I of the Therefore, if V and U are the velocities before colIihi;i], fafng and 
 
 " • ■■ ' • and -u and B the velocities after colh'lioii, of the two bo- HWt,"'.^ 
 
 i 
 
 Of Accele- obferve in general, that if the intenfity of the force be 
 
 lU'ar.iiMg jiin;,„^.g^ a„j [( ^ be the diftance from the fixed point 
 i_ , at which the body begins to be accelerated, and x its 
 diftance from that point in any part of the motion, the 
 velocity will be =f \^a" — \". This is very plain, be- 
 caiife the increment CGHD of the area of fig. 1 6. 
 which is alfo the increment of the fqnare of the veloci- 
 ty, is == .■e''~'.v, and the area is = .v" ; and the whole 
 area, corvcfponding to the diltancc a, is a". Therefore 
 the portion of the area lying beyond the diftance .v is 
 ./" — .\". Tiiis is as the fquare of the velocity, and 
 therefore tiie velocity is as the iqiiare root V^a" — a" 
 of this quantity. 
 
 burcee. 
 
 Thi:> propolitiim, J" s == vi', or _/" == — r". 
 
 the 
 
 39tli of the tirft book of Newton's Principia, and is 
 perhips the moll important in the whole doftrioe of dy- 
 namics, whether employed for the inveftigation ot forces 
 or for the explanation of motions. It funiilhes the 
 moft immediate data for both purpofes, but more efpe- 
 cially for the laft. By its help .Sir Ifaac Newton w.is 
 able to point out the numerous dlllurbances of the pla- 
 netary motions, and to feparate them from each other ; 
 thus unravelling, as it were, that moft intricate motion 
 in which all are blended together. He has given a moft 
 wondertul fpecimen of its application in his Lunar 
 Theory. 
 
 We now are able to explain all the puzzling fafls 
 which were adduced by Leibnitz, and his partiians in 
 fupport of their mcafure of the forces of bodies in mo- 
 tion. We fee why four fpriiigs, equally bent, commu- 
 nicate but a double velocity, and nine fprings but a 
 triple velocity ; why a bullet moving twice as faft will 
 penetrate an earthen rampart to a quadruple depth, 
 &;c. &c. 
 
 This theorem alfo gives a moft perjpicuous explanation 
 of the famous doftrlne called confervatio virium •vivarum. 
 V/hen perfectly elaftic bodies att on each other, it is 
 found that the Inm of the malTcs multiplied by the 
 fquares of the velocities is always the fame. This has 
 been inbftituted, with great encomiums, by the German 
 philofophers in place of Des Cartes's principle, that the 
 quantity of motion in the univerfe, eftimated in one di- 
 veftion, remains always the fame. They are obliged, 
 however, to acknowledge, that in the ailions of perfedl- 
 ly hard bodies, there is always a iofs of -vis viva, and 
 therefore have denied the exiftence of fuch bodies But 
 there is the fame Iofs in the mutual anions of all loft or 
 duftile, or even imperfeftly ilallic, bodies ; and they 
 are miferably puzzled how to explain the faft ; but 
 both the confirvatio and the am'tjfio are neceflary confe- 
 quences of this theorem. 
 
 In the collifion of elaltic bodier, the whole change of 
 motion is produced during the fliort time that the bo- 
 dies are comprefled, and while they regain their figure. 
 When this is completed, the bodies are at the fame dif- 
 tance from each other as when the mutual aftion be- 
 gan. Therefore the preceding body has been accelera- 
 ted, and the following body has been retarded, along 
 equal fpaces ; and in every point of this fpace the acce- 
 lerating and the retarding force has been equal. Con- 
 fequently the fame area of fig. 17. expreffcs the change 
 
 dies A and B, we nuift have AxV'— 1;= = Bx«' V', 
 
 and therefore A X V -|. B X U' ::: A X i;' -f B X u^ 
 
 But in the other clals of bodies, which do not com- 
 pletely legaln tiieir tignre, but remain ccmprefled, they 
 are nearer to each other when their nmtu.d adion is 
 ended than when it began. The foremoft body has 
 been accelerated along a fliorter Ipacc than that along 
 which the other has bten retarded. The mutual forces 
 have, in every inftant, been equal and oppoiite. There- 
 fore the area which expreflcs the diminution of the 
 fquare of the velocity, muft exceed the area exprefling 
 the augmentation by a quantity that is always the fame 
 when the permanent compreffion is the fame ; that is, 
 when the relative motion is the fame. A X V' — li' 
 muft exceed B X «■— Us and A X V 4- B X U' muft 
 exceed A X -y -f B X B=. 
 
 This fame theorem is of the moft extenfive ufe in all 
 pradical queftions in mechanic arts; and without it 
 mechanics can go no farther than the mere ilatement of 
 equilibrium. 
 
 Hermann, profeffi.r of mathematics at Pavla, one of '"'''^o'T of 
 the ornaments of the mathematical clafs of philofophers, "" ?^' " 
 has given a pretty demonftration of this valuable propo- 
 fition in the Acia ErudUorum Lipfia for 1709; and 
 fays, that having fearched the writings of the mathema- 
 ticians with great care, he found himftlf warranted to 
 fay, that Newton w.is the undoubted author, and boalla- 
 of his own as the firft fynthctical demonftration. The 
 purpofe of this aftcrtion was not very apparent at the 
 time ; but long after, in 1746, when Hermann's papers, 
 preferved in the town-houfe of Pavia, were examined, 
 in order to determine a difpute between Maupertuls and 
 Koenig about the claim to the difcovery oi the principle 
 of haft aSlion, letters of Leibnitz's were found, requell- 
 ing Hermann to fearch for any traces of this prupofi- 
 tion in the writings of the mathematicians of Europe. 
 Leibnitz was by this time the envious detradtor from 
 Newton's i-cpiitation ; and could not but p-.-rccive, that 
 all his contorted arguments for his doftrine received a 
 clear explanation by means of this propolition, in per- 
 feft conformity to the ufual meafure of moving forces. 
 Newton h.id difcovered this theorem long befire the 
 p;iblication of the Principia, and even before the difco- 
 very of the chief propolition of that book in 1666; 
 for in his Optical Lcftures, the materials of which were 
 in his polfelfion in i66.|, he makes frequent life of a 
 propofition founded on this (fee n" 42.) We may 
 here remark, that Hermann's demonftration is, in every 
 ftep, the fame with Dr Barrow's demonftration of it as 
 a theorem merely geometrical, without fpeaklng of mo- 
 ving forces (fee LsS. Geomdr. xi. p. 85. edit. 16 ), 
 but giving it as an inftance of tlie transformation of 
 curves, which he calls scales of velocity, of time, of 
 acceleration, &c. It is very true that Barrow, in thefe 
 mathematical lectures, approached very near to both of 
 Newton's difcoveries, the fluxionary geometry, and the 
 principles of dynamics ; and the junto on the continent, 
 who were his continual detraftors, charge him with im- 
 pudent plagiarifm from Dr Barrow, and even fay that 
 he has added nothing to the difcoveries of his teacher. 
 But furely Dr Barrow was the beft judge of this mat- 
 ters.
 
 104 
 
 Sin liar in 
 |}an[s and 
 jMiints, 
 what ? 
 
 536 D Y N A 
 
 of At«!t. tcr ; and fo far from rcfentinp; ihe ufe which Newton 
 satir.g aiij ^^^^ made of what he had taught him, he was charmed 
 
 Ketsriluig -i, • ri • ■ /■ r, ■ /r i-r.i 
 
 Forces. W'ltn the genius iil the juvaus ipeaatijjwms his Icholar, 
 w— y— and of his own accord gave hiin his profefTorial chair, 
 and ever after h'vcd in the iitmoft. harmony and friend- 
 fhip with him. Nay, it would even appear, from feme 
 exprcflions in fhofe very Icflurcs, that Dr Barrow owed 
 to young Newton the full thought of making fuch cx- 
 teiiiive ufe of motion in geometry. We recommend this 
 work of Barrow's to the ferious perufal of our readers, 
 who willi to acquire clear notions of the Icience of mo- 
 tion, and an elegant tafle in their mechanical difquifi- 
 tions. After all the cultivation of this fcience by the 
 commentators and followers of Newton, after the Pho- 
 rottoniui of Hermann, the Mcchiwica of Euler, the Dy- 
 naniique of D'Alenibert, and the l\Jechaniqtie Analytique 
 of De la Grange, which are undoubtedly works of tran- 
 fcendent merit and utility, the /'rmr/fia of Newton will 
 ftill remain the mofl pleafing, perfpicuous, and elegant 
 fjjccimen of the application of mathematics to the fcience 
 of uiiiverfiil mechanics, or what we call Dynamics. 
 
 TI»e two fundamental theorems f t := v, and f 1 
 := 1)11, enable us to folve every queftion of motion ac- 
 cilerated or retarded by the aftion of the mechanical 
 " powers of nature. But the employment of them may 
 be greatly expedited and fimplified by noticing two or 
 thrte general cales which occur very frequently. 
 
 Thcfe may be ec.UeJfimilar injlants of time, and Jimilar 
 points oj Jpace •which divide gii}cn porlions of time, and of 
 [pace in the fame ratio. Thus the nu'ddle is a iimilar iii- 
 ftant of an hour or of a day, and is the fipiilarly fituated 
 point of a foot or of a yard. The beginning of the 
 2ift minute, and of the 9th hour, are fimilar inflants of 
 an hour and of a day. The beginning of the 5th inch, 
 and of the 2d foot, are fimilar points of a foot and of a 
 yard 
 
 Forces may be faid to aB Jimilarly luhen their ititen- 
 tion5,what?^/(Vj. in Jimilar isjiants of time, or in Jimilar points of 
 fpace, are in a conflant ratio. Thus in fig. 17. when 
 one body is impelled towards C from A, and another 
 from K, each with a force proportional to the diftance 
 of every point of its motion from C, thcfe forces may 
 be faid to adl funilarly along the fpaces AC and KC, 
 or during the times reprefented by the quadrantal arches 
 AJ?H, KNO. The following propofitions on fimilar 
 aftioiis will be found very nfeful on many occafions ; 
 but we muft premife a geometrical lemma. 
 
 If there be two lines EFGl I (fig. 18.), e f g h, fo re- 
 lated to their abfciffes AD, a d, that the ordinates IK, 
 ili, drawn from fimilar points I and i of the abfciffes, 
 are in the conilant ratio of AEtoaf; then the area 
 ADHE is to the area a d h e as the reftangle of AD 
 X AE to the reftangle a d X a e. 
 
 For let each abfciffa be divfded into the fame number 
 of equal and very fmall parts, of which let CD and c d 
 be one in each. Infcribe the rectangles CGID, c g i d. 
 Then becaufe the number of parts in each axis is the 
 fame, the lengths of the portions CD and c d will be 
 proportional to the whole abfciffes AD and a d. And 
 becaufe C and c are iimilar points CG is to r^f as AE 
 is to a e. Therefore CD X. CG : c d y. c g = AD 
 AE : a d y. a e This is true of each pair of corre- 
 fponding reftangles ; and therefore it is true of their 
 Aims. But when the number of thefe reflangles is in- 
 
 lot. 
 
 Similar ao 
 
 Io5. 
 
 M I C S. 
 
 creafed, and their breadth dimiuiflied without end, it JjOf .Afcele. 
 evident that the ultimate ratio of the fum of all the rift- "''"« »»'! 
 angles, fuch as CDHG to tlie fum of all the rcftangles "n,ces^ 
 e d h g, h the fame with that of the area A DUE to tlia ^_-y.^| 
 area a d h e, and the propofition is manifcA. 
 
 If two particles of matter are fmilarly impelled during I07 
 given limes, the changes of 'ociccily are as the times and as 
 the forces jointly. 
 
 Let the times be reprefented by the flraight lines 
 ABC (fig. !().) and c2 i c, and the forces by the ordi- 
 nates AD. BE, CF, and a d, b e, c f. Then if B and 
 b arc fimilar inftants (fuppofe the middles) of the 
 whole times, we have BE : b e z=: AD : a d. There- 
 fore, by the lemma, the area ACDF is to a c f d at 
 AC X AD to a c y ad. But thefe areas are propor- 
 tional to the velocities (no ^2), and the piopofitioii ig 
 demonflratcd. For the fame reafon the change of ve- 
 locity during the time AB is to the change during ai 
 as AB X AD to a b X a d. 
 
 Cor. I. If the ti.nes and forces are reciprocally pro- 
 portional, the changes of velocity are equal ; and if the 
 forces are fnverfely as the times, the changes of velocity 
 are equal. 
 
 If two particles be Jimilarly urged along given fpaces, 
 the changes made on the fquares of the velocities are as ihe 
 forces and fpnces jointly. 
 
 For if .AC (fig. 19.) and a c are the fpaces along 
 which. the particles are impelled, and the forces are as 
 the ordinates AU and a d, the areas ACFD and acfd 
 are as the changes on the fquares of the velocities. But 
 thefe areas are as AC X AD, and ac X ad. There- 
 fore, Sic. 
 
 Cor. 2. If the fpaces are inverfcly as the forces, the 
 changes of the fquares of the velocities are equal ; and 
 if thefe are equal, the fpace- arc inverfely as the forces. 
 
 Cor. 3. If the fpaces, along which the particles have 
 been impelled from a previous flcite of refl, are direfily 
 as the forces, the velocities are alio as the forces. For, 
 becaufe the changes of the fquares of the velocities are 
 as the fpaces and forces jointly, they are in this cafe 
 as the fquares of the forces or of the fpaces ; but the 
 changes of the fquares of the velocities are in this cafe 
 the whole fquares of the velocities; therefore the fquares 
 of the velocities are as the fquares of the forces, and the 
 velocities are as the forces. N. B. This includes the 
 motions reprefented in fig. 17. 
 
 If two particles be Jimilarly Impelled along given 1C9. 
 fpaces, from a Jlate of rejl, the fquares of the times are 
 proportional to the fpaces direltly, and to ihe forces in- 
 verfely. 
 
 Let ABC (fig. 19.) abe be the fpaces defcribed, 
 and AD, a d, the accelerating forces at A and a Let 
 V, B exprtfs the velocity at B, and 1;, b the velocity 
 at b. 
 
 Let GHK and g h khe curves whofe ordinates are 
 inverfely as the velocities at the correfponding points of 
 the abfciffa. Thefe curves are therefore exponents of 
 the times (n° 99 ) Then, becaufe the forces aft fimi- 
 larly, we have, by the lafl theorem, AC X AD : a c 
 X a ^ = V^ B : 1)', b, = h b' : HB\ Therefore HB 
 : h b = X^ ac X ad : \^ ACxAD, and therefore in 3 
 conftant ratio. Call this the ratio of m to n. But, 
 fince the ordinates of the lines GHK, g h i are inverfe- 
 ly as the velocities, the areas are as the times {11° ^g) ; 
 
 2nd
 
 DYNAMICS. 
 
 537 
 
 Of Accede- and fince thefe ordinates are in the conftant ratio of m 
 tatiiij; and (^ „^ tj,g areas are in the ratio of AC Xm to ei cXn. 
 Kctardin); 'i-i,g,.efure (calling the times of the motions T and/), 
 
 liave 
 T ! 
 
 Or T' 
 
 ;/ r:mAC:nac;and therefore 
 ■.l' = m'XAC':n'Xac^. But 
 ;n'= ac Xa^: AC X AD. Therefore 
 : /■ = a f X a (/ X AC : AC X AD X a C, 
 -.1^= ad X AC : AD X a c 
 AC ac 
 
 Or T- : /^ = ^-fs : —j. 
 AD arf 
 
 The attentive reader will obferve that thefe three 
 propofuions give a great extenfion to the theorems 
 which were formerly deduced from the nature of uni- 
 formly accelerated motion, or of uniform aftion of the 
 forces, and were afterwards demonftrattd to obtain in 
 the momentary aftion of forces any how variable. 
 
 The lirft of the three propofitions, V : v = F X T : 
 fX t, is the extenfion of the theorem /X t ■= v. The 
 fecond, V^ : i)" = F X S :/X J, is the extenfion of the 
 
 S / 
 theorem/X J = f t). And the third, T' :'»= P : t' 
 
 is the extenfion of /"= -J—, or of/X (/') = /. Thefe 
 
 theorems hold true of ?A\fmilar aftions ; and only for 
 this reafon, are true of uniformly accelerated motions, 
 or uniform aftions. 
 ^-»rcj,jte There remains one thing more to be faid concerning 
 if many the aftion of accelerating forces. Their magnitude is 
 , 1"^! ^"^'- afcei-taincd by their efFeft. Therefore that is to be 
 conlidered as a double force which produces a double 
 quauiity of motion. Therefore when a body A con- 
 tains twice the number of equal atoms of matter, and 
 acquires the fame velocity from the aflion of the force 
 F that anotlitr body a, containing half the number of 
 atoms, acquires from the aftion of a force f, we con- 
 ceive F to be double ofy. 'I hat this is a legitimate in- 
 ference appears clearly from this, that we conceive the 
 fenfible weight of a body, or that preffure which it ex- 
 erts on its fupports, as the aggregate of the equal pref- 
 fure, of every atom, accumulated perhaps on one point; 
 as when the body hangs by a thread, and, by its inter- 
 vention, pulls at fome machine. Without inquiring in 
 what manner, or by what intervention, this accumula- 
 tion of preffure is brought about, we fee clearly that it 
 refults from the equal accelerating force of gravity act- 
 ing immediatly on each atom. When this weight is 
 thus employed to move another body by the interven- 
 tion of the thread, which is attached to one point per- 
 haps of that body, it puts the whole into motion, gene- 
 rating a certain velocity ii in every atom, by atting 
 uniformly during the time /. We conceive each atom 
 to have fuftained the adlion of an equal accelerating force, 
 
 forces propagated to each atom of the impelled body. Of Accele. 
 ^ rating and 
 
 and meafured by — . If we know that the impelled Kcarding; 
 
 ' / ^ Forces, 
 
 body contains the number m of atoms, the aggregate of ' ■■ v ■■' 
 
 forces is m — , or . 
 
 But fiuce we meafure forces by the quantity of mo. 
 tion which they produce, we mull conceive, that when 
 the fame force is applied to a body « hid. coiifills of n 
 particles, and produces the velocity u, by ading uni- 
 
 a 
 formly during the fame time /, the force n — is equal to 
 
 V 
 
 the force m - 
 
 . Ito 
 
 Sir Ifaac Newton found it abfolutely necefTary, in Movini^ 
 the difquifitions of natural philofophy, to keep this cir-f<rce, mo- 
 
 cumllancc of acceleration clear of all notions of quanti-"." force, 
 . , p . . J ^ . V15 motrit, 
 
 ty of matter, or other coiuidcrations, and to contem-^jj)jj).jp_ 
 
 plate the affeAions of motion only. He therefore con-guithed 
 
 ^ / from acce- 
 
 fidered - as the true original meafure of accelerating lerating 
 
 eratin^ 
 orces. 
 
 whofe meafure is — . 
 
 Without confidering how this 
 
 force is exerted on each atom, or by what it is imme- 
 diately exerted, or how it is diffufed through the body 
 from the point to which the weight of the other body 
 is applied by means of the thread ; we ftill confider it 
 as the aggregate of the aftion of gravity on each atom 
 of that other body. Moreover, attending only to the 
 motion produced by it, and perhaps not knowing the 
 weight of the impelling body, we meafure it, as a mo- 
 ving force, by confidering it as the aggregate ©f the 
 SuppL. Vol. I. Part II. 
 
 force, and m — as an aggregate. He therefore calls the 
 
 aggregate a vis matrix, a moving force, meafured by the 
 quantity of motion that it generates. And he confines 
 
 V 
 
 the term accelerating force to the quantity -, meafured 
 by the acceleration or velocity only. It would be conve- 
 
 V 
 
 nient, therefore, alfo to confine the fymbol/ to m -' 
 
 and to retain the fymbol a for exprefling the accelera- 
 
 • r ■" 
 ting lorce -. 
 
 This appellation of motive force is perfeftly juft and 
 fimple ; for we may conceive it as the fame with the 
 accelerating force which produces the velocity m times v 
 ill one particle, by adling on it uniformly during the 
 time t. This motion of one particle having the velocity 
 m V, is the fame with that of m particles having each 
 the velocity v. 
 
 If therefore a motive force / afls on a body con- 
 fiding of m particles, the accelerating force a is 
 
 ~ m t' 
 
 Therefore the three laft propofitions concerning the 
 fimilar, the uniform, or the momentary aftiona of mo- 
 ving forces, when exprefled in the moil general terms, 
 are, 
 
 v'~A 
 
 • m t 
 
 • /'' • /^' 
 v =-^ — , or vv =: ■' — 
 
 ■ tn tn 
 
 t^-- 
 
 III 
 
 mj' 
 
 T' 
 
 Or Deflecting Forces. 
 When we obferve the direftion of a body to change, Dcflefling 
 we unavoidably infer the agency of a force which ads forces, 
 in a direftion that does not coincide with that of the 
 body's motion ; and we may diftinguifh this circum- 
 ftance by calling it a deflecting force. We have 
 already (hewn how to eftimate and meafure this de- 
 flefting force, by confidering it as competent to the 
 jY pro-
 
 i8 
 
 DYNAMICS. 
 
 Altera! ion 
 of dcfltc- 
 tions are 
 cuntiiiual, 
 and pru- 
 
 III 
 
 Biainple 
 Determina- 
 tion I f the 
 path, 
 
 Of Defleil- produftion of that motion which, when compounded 
 
 ing Ptmes.^jjlj jj^^ former motion,- vvill produce the new motion 
 
 ' (u''44.) Now, as all changes of motion are really 
 
 compohtions of motions or forces, it is evident that we 
 
 fhsU explain the aflion of deflciling forces when we 
 
 fliew this compofition. 
 
 We may almofl venture to fay a priori, that all dc- 
 fleftions muft be continual, or exhibit curvilineal mo- 
 tions : for as no finite velocity, or change of velocity, 
 can be produced in an inftant by the adtion ot an ac- 
 ducc cur- cekrating force, no polygonal or angular defleftion can 
 ■iline.ll jjp produced ; becaufe this is the compofition of a finite 
 notions. y^,ijn,;ty produced in an inlhnt. DefleAive motions are 
 all produced by the compofition of the former motion, 
 having a finite velocity, with a tranfvcrfe motion conti- 
 nually accelerated from a Hate of reft. Of this we can 
 form a very diftinft notion, by taking the fimpltft cafe 
 of fuch accelerated motion, namely, an uniformly acce- 
 lerated motion. 
 
 Let a body be moving in the diredion AC (fig. 20. ) 
 with any conftant velocity, and when it comes to A, 
 let it be expofed to the atlion of an accelerating force, 
 afling uniformly in any other direftion AE. This 
 alone would caufe tlie body to defcribe AE with a uni- 
 formly accelerated motion, fo that the fpaces AD, AE 
 would be as the fquares of the times in which they are 
 dtfcribed. Therefore, if AB be the fpace which it 
 would have defcribed uniformly in the time that it de- 
 fcribec AD by the adion of the accelerating force, and 
 AC the fpace wlu'ch it would have defcribed uniformly 
 while it defcribes AE by the aftion of the accelerating 
 force — nothing more is wanted for afcertaining the 
 real motion of the body but to compound the uniform 
 motion in the diredion AC with the uniformly accele- 
 rated motion in the direction AE. AD is to AE as 
 tlie fquare of the time of defcribing AD to the fquare 
 <if the time of defcribing AE ; that is, as the fquare 
 of the time of defcribing AB to the fquare of the time 
 of defcribing AC ; that is, as AB= to AC^ (by reafon 
 of the uniform motion in AC). This compofition is 
 performed by taking the fimultaneous points B, D, 
 and the fimultaneous points C, E, and completing tiie 
 parallelograms ABFD, ACGE. The body will be 
 found in the points F and G in the inftants in which 
 it would have been found at B and C by the uniform 
 motion, or in D and E by the accelerated motion. In 
 the fanie manner may be found as many points of the 
 real pa'.Ii as we pleafe. It is plain that thefe points 
 will be in a line AFG, fo related to AE that AD : 
 AE = DF' : EG" ; or fo related to the original mo- 
 tion AC, that AB' : AC = BF : CG, &c. This 
 line is therefore a parabola, of which AE is a diameter, 
 DF and EG are crdinates, and which touches AC in 
 A. 
 And of the Having thus afcertained the path of the body, we 
 Bioticn in can alfo afcertain the motion in that path ; that is, the 
 this path, vfijjcity in any point of it. We know that the velo- 
 city in the point G is to the velocity of the uniform 
 motion in the direftion AC as the tangent TG is to 
 the ordinate EG ; becaufe this is the ultimate ratio of 
 the momentary increment of the arch AFG to the mo- 
 mentary increment of the ordinate EG. Thus is the 
 velocity in every point of the curve determined. We 
 have taken it for granted, that the line of projeftion 
 touches the path, and that the direAIoa in every poiot 
 
 113. 
 
 is that of the tangent. To fuppofe that the curve, in Of Deflefl 
 any portion of it, coincides with the tangent, is to fup- "'>^ i' orce; 
 pofe that the body is not defleAed ; that is, is not ac- ' 
 ted on by a tranfvcrfe accelerating force : And to fup- 
 pofe that the tangent makes a finite angle with any 
 part of the path, is to fuppofe that the deflexion is not 
 continual, but by flarts — both of which are contrary to 
 the conditions of the cafe. No ftraight line can be 
 drawn between the direftlon of the body and the fuc- 
 ccedlug portion of the path, otherwife we muft again 
 fuppofe that the defleftion is fubfultory, and the mo- 
 tion angidar. 
 
 But while the inveftigation is fo eafy when the direc- 
 tion and intenfity of the defletting force in every point 
 of the curve are known, the inveftigation of the dffiec- 
 ting force from the obferved motion is by no means 
 eafy. The obferved curvilineal motion always arifes 
 from a compofition of a uniform motion in the tangent 
 with fome tranfvcrfe motion. But the fame curvilineal 
 motion may be produced by compounding the uniform 
 motion in the tangent with an infinity of traafverfe mo- 
 tions ; and the law of aftion will be different in thefe 
 tranfvcrfe motions according as their direftions differ. 
 AVe muft learn, not only the intenfity of the deflefting 
 force, and the law of its variation, but alfo its dire£lion 
 in every point of the curve. It is not eafy to find ge- 
 neral rules for difcovering the direction of the tranfvcrfe 
 force; moft commonly this is indicated by extrinfic cir- 
 cumftances. The deflefting force is frequently obfer- 
 ved to refide in, or to accompany, fome other body. It 
 may be prefiimed, therefore, that it afts in the direc- 
 tion of the line drawn to or from that body ; yet even 
 this is uncertain. The moit general rule for this invef- 
 tigation is to obferve the place of the body at fcveral 
 intervals of time before and after its paffing through the 
 point of the curve, where we are intercfted to find its 
 precife direftion. We then draw lines, joining thofe 
 places with the places of the tangent where the body 
 would have been by the uniform motion only. We (hall 
 perhaps obferve thefe lines of junftion keep in parallel 
 pofitions : we may be alTured that the dIreAion of the 
 tranfvcrfe force is the fame with that of any of thefe 
 lines. This is the cafe in the example juil now given 
 of a parabolic motion. But when thefe lines change 
 pofitlon, they will change it gradually ; and their pofi- 
 tion in the point of contaft is that to which their pofi- 
 tions on both fides of it gradually approximate. 
 
 But all this is deftitute of the precifion requifite in 
 philofophical difcuffion. We are indebted to Sir Ifaac 
 Newton for a theorem which afcertains the diredlion of 
 the tranfvcrfe force with all exaftnefs, in the cafes in 
 which we moft of all wiflt to attain mathematical accu- 
 racy, and which not only opened the accefs to thofe 
 difcoveries which have immortalifed his name, but alio 
 pointed out to him the path he was to follow, and even 
 marked his firft ileps. It therefore merits a very par- 
 ticular treatment. 
 
 If a body defcribes a curve line ABC, DEF (fig. Newton': 
 21.) lying in one plane ; and if there be a point S fofunJamcrj 
 lltuated in tliis plane that the line joining it with the"' '^^"^'j 
 body defcribes areas ASB, ASC, ASD, &c. propor-^|.^io„oji 
 tional tu the times in which the body defcribes thedefleflint 
 arches AB, AC, AD, &c. the force which defleds the force, 
 body from rectilineal motion is continually diretSed to 
 the iixed point S. 
 
 Let 
 
 114
 
 ndicite 
 
 <ntral 
 
 urces. 
 
 )f DctliLl- Ltt us full fiippofe that the body defcribes the po- 
 ng torci.. lygo,, ABCDEF, &c. formed of the chords AB, EC, 
 — ' CD, DE, I'.F, &c. of this curve : and (for greater 
 fiinpli'city of argument) let us coui'ulcr areaa deieribed 
 ill equal fuccedive times ; that is, let us fuppofe that 
 the triangles ASB, BSC, CSD, &c. are equal, and de- 
 fcribed in equal times. Make B f =. AB, and draw 
 f S. 
 i\rea9 = to Had the motion AB fufFered no change in the point 
 he times 3^ tin; body would have defcribed Be in the equal mo- 
 ment futcetding the firft : but it dclcribes BC. The 
 body has therefore been dcflcfted by an external force ; 
 and BC is the diagonal of a parallelogram (n' 45, 46.), 
 of which Be is one fide, and r C is another. The de- 
 flefting force will be difcovered, both in rcfpeit of di- 
 reiflion and intenlily, by completing the parallelogram 
 B c C ^. B i is the fpace vvliich the defletling force 
 would have caufed the body to dcfcribe in the time 
 that it dtfcribes B c or BC. Becaufe B i: is equal to 
 ]5A, the triangles BSc, BSA are equal. But (by the 
 nature of the motion) BSA is equal to BSC. There- 
 fore the triangles BSC and BSc are equal. They are 
 alfo on the fame bafe BS ; therefore they lie between 
 the fame parallels, and Cf is parallel to SB. But c C 
 is parallel to B 6. Therefore B i> coincides with BS, 
 and the defledling force at B is direfted toward S. 
 By the fame argument, the deflefting force at the 
 angles D, E, F, &c. is directed to S. 
 
 Now, let the fides of the polygon be diminifhcd, and 
 their number increafed without end. The demonftia- 
 tion remains the fame; and continues, when the polygon 
 finally coalefces with the curve, and the defleftion is 
 continual. 
 
 When areas are defcribed proportional to the times, 
 equal areas are defcribed in equal times ; and therefore 
 the defleftion is always direfted to S. Q^ E. D. 
 
 The point S may, with great propriety of language, 
 be called the Centre of Deflection, or the Cen- 
 tre OF Forces ; and forces which are thus continual- 
 ly direfted to one fixed point, may be diftinguilhed 
 from other deflefting forces by the name Central 
 j Forces. 
 
 I The line joining the centre of forces with the body, 
 
 j and which may be conceived as a ftiff line, carrying the 
 
 Radius vec- body round, is ufually named the Radius Vector. 
 ' "■• The converfe of this propofition, viz. that if the de- 
 
 '' 'entrd for A'^'^'ng forces be always direfted to S, the motion is 
 : M produce P'^''f^o'"f"fd in one plane, in which S is fituated, and 
 reas pro- areas are defcribed proportional to the times — is eafily 
 ' ortional toj^j^onftrated by reverfing the fteps of this demonttra- 
 '■ tion. The motion will be in the plane of the lines SB 
 and Be; becaufe the diagonal BC of the parallelogram 
 of forces is in the plane of the fides. Areas are de- 
 fcribed proportional to the times ; for C c being pa- 
 rallel to SB, the triangles SCB and S c B are. equal ; 
 and therefore SCB and SAB are equal, Sec. &c. 
 'elocity is ^'"'- ^- When a body defcribes areas round S pro- 
 iverfely a-portlonal to the times, or when it is continually deflec- 
 I le perpeii-ted toward S, or afted on by a tranfverfe force direfted 
 to S, the velocities in the diflerent points A and E of 
 the curve are inverfely proportional to the perpendicu- 
 lars Sr and St, drawn from the centre of forces to the 
 tangents in thofe points; that is, to the perpendiculare 
 from the centre on the momentary direftions of the 
 motion : For fmce the triangles ASB, ESF are equal, 
 
 117. 
 
 ri8 
 
 as 
 
 arc 
 
 .'entre of 
 
 efledtion. 
 
 lentre of 
 
 )rces. 
 
 'entral 
 
 >rce;. 
 
 icular 
 •om the 
 SDtre. 
 
 DYNAMICS. 5;,9 
 
 their bafes AB, EF are inverfely as their altitudes Sr, Of D-.flcft- 
 St. But thefe bafes, being defcribed in equal timcP, '"'• *•'""•; 
 are as the velocities ; and they ultimately coincide with " ' " 
 the tangents at A and E. 
 
 Cor. 2. If B .1 and F' be drawn perpendicular to 
 SA and SE, we have SAxB« = SExF,, and 
 S A : SE = F ■ : B " : For SA X B « is double of the 
 triangle BSA, and SE X F ' is double of the equal 
 triangle SFE. 
 
 Cor. ^. The angular velocity round S, that i.-;, theAn^uUr 
 magnitude of the angle defcribed in equal times by the .''■'^''^'^'''" 
 radius veftor, is inverfely proportional to the fquarc of Jii",q'j;'/r(_ 
 the diftance from S. For when the arches AB, EF.f flu-di;:. 
 are dimiiiifhed continually, the perpendiculars B * and'^' « from 
 F ! will ultimately coincide with arches deicribed round '^' ""trc 
 S with the radii 'SB and SF. Now the magnitude of"' '"""• 
 an angle is proportional to the length of the arch which 
 iTie;i(ures it direftly, and to the radius of the arch in- 
 verfely. In any circle, an arch of two inches long mea- 
 fures twice as. many degrees as an arch one inch long; 
 and an arch an inch long contains twice as many de- 
 grees of a circle whofe radius is twice as lliort. There- 
 fore, ultimately, the angle ASB is to the angle ESF 
 as B « to F !, and as SF to SB jointly ; that is, as B ■^ 1 
 
 X SF to F t X SB. But B „ : F , = SE : SA {Cor- 
 2.) Therefore ASB : ESF = SE X SF : SB X SA, 
 = ultimately SE^ : SB\ 
 
 This corollary gives us an oftenfible mark, in many 
 very important cafes, of the aftion of a dcfltiiing force 
 being always direfted to a fixed point. We are oftra 
 able to meai'ure the angular motion when we cannot 
 nieafure the real velocities. 
 
 Having thus difcovered the chief circumdances which Intimate 
 enable us to alcertain the direftion of the dellefting>:""ii(rdioi> 
 force, we proceed to invcftigate the quantity of this de-' '^.'')"*- 
 fleftive determination in the different points of a ciirvi-"i','e h1°hcr 
 lineal motion. This is a more difficult talk. The mo-gejtnary. 
 mcntary elfeft of the deflefting force is a fmall devia- 
 tion from the tangent ; and this deviation is made with 
 an accelerated motion. The law of this acceleration 
 regulates the curvature of the path, and is to be deter- 
 mined by it. We m.ay be allowed to obferve by the 
 way, that it appears clearly from the form in which 
 Newton has prefented all his dynamical tlicmetTis, that 
 we are indebted to thefe problems for the inimenfe in- 
 provenient which lie has made in geometry by his in- 
 vention of fluxions. The purpoft-s he had in view fuT- 
 gcflcd to his penetrating mind the means for attaining 
 them ; and the conneftion between dynamics and geo- 
 metry is fo intimate, that the fame theorems are in a 
 manner common to both. This is particularly the cafe 
 in all that relates to curvature. Or (liall we fay thiit the 
 geometry of Dr Barrow fuggefted the dynamical theo- 
 rems to Newton? AVc have feen how the curvature of a 
 parabola is produced by a force afting uniformly. The 
 viomentary aftion of all finite forces may be confidercd 
 as uniform ; and therefore the curvature will be that of 
 fome portion of fome parabola; but it will be difficult to 
 determine the precife degree without fiinie farther help. 
 We arc beft acquainted with the properties of the circle, 
 and will have the cleared notions of the curvature of 
 other curves by comparing them with circles. 
 
 The curvature of a circular arch of given length isMeafureof 
 fo much greater as its radius is fliorter ; for it will coii-'"'^^""''' 
 tain fo many more degrees in the fame length ; and 
 3 Y a therefore
 
 540 
 
 Ot Deflf a 
 ing I''orces. 
 
 119 
 
 JE volution 
 and involu 
 tion of 
 curves. 
 
 DYNAMICS. 
 
 Circle of 
 curvature. 
 Equicurvc 
 circle. 
 
 thsrefore the cliange of direftion of its extremities is fo 
 much greater. Curvatures may always be meafuved 
 by the length of the arch diredtly and the radius in- 
 verfely. 
 
 Suppofe a thread made faft at one end of a material 
 curve ABCD (fig 22 ), and applied to it in its whole 
 length. Taking hold of its extremity D, unfold it gra- 
 dnally from the curve DCBA ; the extremity D will 
 dcfcribe another curve D c 1/ a This geometrical ope- 
 ration is called the F.volutiojj of curves, and D c i a 
 is called the Evolu r£ of DCBA, which is called the 
 Involute of D i l"'- Perhaps this denomination has 
 been given from the gcnefis of the area or furface con- 
 tained by the two lines, which is folded up and unfold- 
 ed fomewhat like a fan. When the defcribing point is 
 in b, the thread 3 B is, undoubtedly, the momentary 
 radius of a circle e bf, whofe centre isB, the point of 
 the involute' which i't is juil going to quit._ The mo- 
 mentary motion of i is the fame, whether it is defcri- 
 bing an arch of the evolute paHing through i, or an 
 arch of a circle round the centre B. The fame line 
 tt, perpendicular to the thread I B, touches the circle 
 ebf and the curve D b a in the point /'. This circle 
 e i/muft lie within the curve Dirt on the fide of 3 B 
 toward a; becaufe on this fide the momentary radius is 
 continually increafing. For fimilar reafons,^ the circle 
 e bf lies without the curve on the other fide of i B. 
 Therefore the circle ebf both touches and cuts the 
 curve D ba it\ the point b. Moreover, becaufe every 
 portion of the curve between b and D is defcribed with 
 radii that are fnorter than Z>B, it mud be more incur- 
 vated than any portion of the circle ebf. For fimilar 
 reafons, every portion of the curve between b and a 
 muft be lefs incurvated than this circle ; therefore the 
 circle has that precife degree of curvature that belongs 
 to the curve in the point b ; it is therefore called the 
 Equicurve Circle, or the Circle op Curvature, 
 and B is called the centre, and B* the Radius of 
 Curvaturk. It is eafy to perceive that no circle can 
 be defcribed which fhall touch the curve in b, and come 
 between it and the circle ebf; for its centre muft be 
 in fome point i of the radius b B. If i b be lefs than 
 B b, it muft fall within the curve on both fides of b, 
 and if i b is greater than B b, the circle muft fall with- 
 out the curve on both fides of B b. The circle e bf 
 lies clofer to the curve, has clofer contaft with it than 
 any other, and has therefore got the whimfical name 
 of Osculating Circle; and this fort of contad was 
 called Osculation. 
 
 This view of the gcnefis of curve lines is of particu- 
 lar ufe in dynamical difeulTions. It exhibits to the eye 
 the perfeft fameuefs of the momentary motion, and 
 therefore of the momentary defleftion, in the cun-e and 
 in the equicurve circle, and leaves the mind without a 
 doubt but that the forces which produce the one will 
 produce the other. A great variety of curves may be 
 defcribed in this way. If perpendiculars be drawn to 
 the curve D ia in every point, they will interfed each 
 other, each its immediate neighbour, in the circumfc. 
 rence of the curve DBA: and geometry teaches us how 
 to find the curve DBA which (hall produce the curve 
 J) ba by evolution. See Evolution and Involution, 
 Supphntent. 
 
 It is a matter worthy of remark, that the path of a 
 body that is deflefted from reftilineal motion by a fi- 
 
 nite force, varying according to any law whatever, may Of Dcflcfl. 
 always be defcribed by evolution. This includes alinoft '"-' l'"'>"t8. 
 every cafe of the action of deflefting forces ; none be- • 
 ing excepted but when, by the oppolite adllon of difi'e- 
 rent forces, the body is in equilibrio in one fingle point 
 of its path. 
 
 Our tailc is now brought within a very narrow com- 
 pafs, namely, to meafure the defleftion in the arch ot a 
 circle. 
 
 Had the TTU)tion reprefented in fig. 21. been poly, 
 gonal, it is plain that the deflefting force in the point 
 B is to that in the point E as the diagonal B A of the 
 parallelogram ABC 3 to the diagonal Ei ot the pa- 
 rallelogram DEFi; therefore let ABCZY be a circle 
 pafiing through the points A, B, and C, and let the 
 radius veftor BS cut the circumference in Z ; draw 
 AZ, CZ, and the diagonal AC, which neceflarily bi- 
 fetts and is bifefted by the diagonal B b. The tri- 
 angles bVjC and CBZ are fimilar ; for the angle CAB 
 is equal to the alternate angle ABA or ABZ, which 
 is equal to the ACZ, {landing on the fame chord 
 AZ. And the angle CB b, or CBZ, is equal to C.\Z, 
 ftanding on the fame chord CZ ; therefore the re- 
 maining angle iCB is equal to the remaining angle 
 AZC; therefore Z.\ is to AC as BC to B i, and Bi 
 
 ACXBC 
 
 In like manner E / = 
 
 DFxEF 
 
 AZ D« 
 
 Now let the points A and C continually approach, 
 and ultimately coalefce with B ; it is evident that the 
 circle ABCZY is ulimately the equicurve or coinci- 
 ding circle at the point B, and that AS ultimately coa- 
 lefces with, and is equal to, BS, and that AC X BC 
 is ultimatelv 2 BC' ; therefore ultimately BA : E« = 
 zBC^ . 2EP ._BC.EP 
 "WT ' E^ ' "' ~ \V>Z ■ iEz* 
 
 Now BC and EF being defcribed in equal times, are Meafareo* 
 as the velocities: BA and Ej are the meafures of thedelleding 
 velocities which the defleftlve forces at B and E would fjrce«. 
 generate in the time that the body dtfcribes BC or 
 EF, and are therefore the meafures of thofe forces. 
 Thev are as the fquares of the velocities directly, and in- 
 verfely as thofe chords of the equicurve circles ivhich have 
 the diredions of the deflection. 
 
 Obferve, that BA or Ei is the third proportional to 
 half of the chord and the arch defcribed ; for B A : BC 
 
 = BC:^. 
 2 
 It is evident th»t as the arches AB, BC, conti- 
 nually dimlnifh, AC is ukimately parallel to the tau- 
 ■rent B r, and BO is equal to the aftual deflexion from 
 Uie tangent. The triangles BOC and AOZ arc fimi- 
 
 lar, and BO = -^^ , or ultimately =-^- We may 
 
 meafure the forces by the aftual defledions, becaufe 
 they are the halves of the meafures of the generated 
 velocities; and we may fay that „„ 
 
 The allual momentary dcJlcBion from, the tangent is a third MeiCare o£ 
 
 proportional to the deJeClive chord of the equicurve circle deaeflioo. 
 
 and the arch defcribed during the moment. 
 
 Either of thefe meafures may be taken, but we muft Caution, 
 take care not to confound them. The firft is the 
 moft proper, becaufe the change produced on the body 
 (which is the immediate efFeft and meafure of the force) 
 is the determination, left inherent in it, to move with 
 
 a
 
 D Y N A 
 
 of Dcfltifl a certain Telocity. This is the meafure alfo wl.ich we 
 jug Furco. gijt^d, [jy means of the differential or fluxionary cal- 
 cuhis ; but the other meafure mud be i)lHaliied when 
 our immediate obitft is to mark the aiiliial path of the 
 body. What is now dch'vered coincides with wliat 
 was more briefly dated in Astronomy, Suppl, n° 1 6. 
 and is repeated in this place, becaule the Heps of this 
 demonftration, which is Newton's, fo naturally termi- 
 nate ill the equicuvve circle, and give at once the im- 
 mediate meafure of the defleiling force : at the fame 
 time tho reader n\u(l perceive that this meafure docs 
 not depend on the force being always dirciJted to one 
 centre ';' It is eruingh that the two fides of the polygon, 
 in immediate turceninn, are dcf>.Tibed in equal times. 
 This is neceffary in order that ABC b may be a paral- 
 lelogram, and that the diagonals AC and B b may mu- 
 tually bifeft each other. 
 
 Thus have we obtained a meafure of defledling force, 
 and, in the molt important cafes, a method of difcover- 
 ing its direftion. It only remains to point out the re- 
 lation between the intenfity of the force, the curvature 
 of the path, and the velocity of the motion. Thefe 
 three circumllances have a ncceflTary connection ; for 
 we fee that the intenfity is expreffed bv certain values 
 
 Arch 2 
 
 of the other two in the formula f == -ttt; ;> or f 
 
 •' • 4Chcn-d •' 
 
 2BC , 
 :r T)r^ • The defleflive velocity B ^ is acquired in 
 
 the time that the body defcrihes BC ; therefore the 
 defleftive velocity is to the velocity in the curve as B 3 
 to BC. The velocity B b is acquired by an accelera- 
 ted motion along BO ; for while, by progreflive mo- 
 tion, the body defcribes BC, it deftefts from the tan- 
 gent through a fpace equal to the half of B b, becaufe 
 the momentary aftion of the deflefting force may be 
 confidered as uniform. The progreffive velocity BC 
 may be generated by the fame force, uniformly afting 
 through a fpace greater than BC ; call this fpace x. 
 The fpaces along which a body mull be uniformly im- 
 pelled in order to acquire different velocities, are as the 
 iquares of thofe velocities; therefore Bi': BC^=: 
 B : X ; but B /; : BC = BC : 4 BZ ; therefore B i^ : 
 BC ^ = B /^ : 4 BZ, and B i : i BZ = B o : x, and 
 B i : B «) =: 4 BZ : .V ; but B o is 4 of^B b ; therefore 
 « is J of BZ ; that is, 
 x%i, "^he velocity in any point cf a curviUneal path, is that 
 
 luhich the defleSing forces in that point luould generate in 
 the body by impelling it uniformly along one fourth part of 
 the difleSlive chord of the eqiiiiurve circle. If the velo- 
 city increafe, the chord of ihe equicurve circle muft 
 increafe ; that is, the path becomes lefs incurvated. If 
 the force be increafed, the curvature will alfo increafe, 
 for the chord of curvature will be lefs. 
 
 There is another general obfervation to be made on 
 the velocity of a curviiineal motion, which greatly af- 
 jj fills us in our invefligations. 
 . jmiiari- !f -^l body defcribes a curve by the aiJion of a force 
 
 . n of orbi always direSed to a fixed point, and 'varying according to 
 \ Ith'di'r"'^ ""^ proportion luhatcver nf the diflanccs from that point, 
 j proachto'""' 'f '^noz/jfr body, aded on by the fame centripetal 
 I e centre, forte, move toivard the centre in a flraight line, and if 
 
 in any one cafe of equal diflances from the centre of force 
 the tzuo bodies have equal i-elocities, they luill have equal 
 velocities in every other cafe of equal diflances from the 
 (cntre. 
 
 M I C S. 541 
 
 Let one body be impelled from A (fig. 2^.) toward Of Dcflefl- 
 C along the flraight line AVDEC, and lot another be'"K Forcet 
 defletted along the curve line VI K k. About the ccn- '~~^'^~^ 
 tre C dcfcribe concentric arches ID, KE, very near to 
 each other, and cutting the curve in I and K, and the 
 line AC in D ajid E"; draw IC, cutting KE in K, 
 and draw NT perpendicular to the arch IK of the 
 curve, and complete the parallelogram ITNO. Let 
 the bodies be fuppofed to have eijti.il velocities at I and 
 at D. 
 
 Then, becaufe the centripetal forces are fuppofed to 
 be the fame for both bodies when they are at equal 
 dillaiices, the accelerating forces at D and I may be 
 reprefented by the equal lints DE and IN ; but the 
 force IN is not wholly employed in accelerating the 
 body along the arch IK, but, afting tranfverfely, it is 
 partly employed in incurvaiing the path. It is equi- 
 valent to the two forces 10 and IT, of which only IT 
 accelerates the body. Now IKN is a right-angled tri- 
 angle, as is alfo the triangle INT ; and they are limilar; 
 therefore IN : IT = IK : IN, cr DE : IT = IK : DE; 
 that is, the force which accelerates the body along DE 
 is to the force which accelerates the body along IK as 
 the fpace IK is to the fpace DE ; therefore (n" 86.) 
 the increment of the fquare of the velocity acquired 
 along DE is equal to the increment of the fquare of 
 tlie velocity acquired along IK. But the velocities at 
 D and I were equal, and confequently their fquarcs 
 were equal ; and thefe having received equal increments, 
 therefore the fquares of the velocities at E and K are 
 equal, and the velocities themfelves are equal. And 
 finc« this is the cafe in all the correfponding points of 
 the line AC and the curve VI K, the velocities at all 
 equal diflances from C will be equal. 
 
 It it evident that the conclufion will be the fame, if 
 the bodies, i'nftead of being accelerated by approaching 
 the centre in the flraight liue'AC, and in the curve- 
 VI K, are moving in the oppolite direClions from E to 
 A, or frotri I to V, and are therefore retarded by the 
 centripetal force. 
 
 Cor. Hence it follows, that if a body be projected Retarded 
 from any point, fuch as V, oHhe curve, in a line tend-'^"".'''""^ 
 ing flraight from the centre, with the velocity which itwayrac- " 
 had in that point of the curve, it would go to a diltancecompanied 
 VA, fuch, that if it were impelled along AV by thebyrecefi 
 centripetal force, it would acquire its former velocity in'^'^""' '*'' 
 the point V ; alfo in any point between V and A Jt"^""'- 
 will have the fame velocity iii its recefs from the centre 
 that it has there in its approach to the centre. 
 
 The line BLFG, whofe ordinatcs are as the intenli, 
 ties of the centripetal force in A, V, D, E, or in A, 
 V, I, K, may be called the scale or exponent of 
 force; the arei.s bounded by the ordinates AB, VL,. 
 DF, EG, occ. drawn from any two points of the axis, 
 are as the fquares of the velocity acquired by accelera- 
 tion along the intercepted part of the axis, or in any 
 curviiineal path, while the body approaches the centrCj 
 or which are loll while the body retires from it. When 
 we can compute thefe areas we obtain the velocities 
 (fee n° io2.). 
 
 We are now in a condition to folve the chief pro- 
 blem in the fcience of dynamics, to which the whole of 
 it is, in a great meafure, fubfervient. The problem is 
 this, 
 
 Let a body be projefted with a known velocity from
 
 542 
 Of ocfl a- 
 
 in|r Force-. 
 
 114 
 
 !nv?riepro 
 h'em of 
 fcntripetal 
 fu) c«t. 
 
 DYNAMICS. 
 
 Inverfe pro 
 
 Mem of 
 
 centriijetal 
 
 forces. 
 
 a given point anJ in n given dircflion, and let it be un- 
 der the influence of a mechanical force, whofe diredlion, 
 inteniity, and variation, are all known : it is required to 
 determine its path, and its motion in this path, for any 
 given time ? 
 
 Thh problem is fiifceptible of three diftinft clalTes of 
 conditions, which require different inveftigation. 
 
 t. The force may aft in one conftant direftion ; that 
 is, in paralkl lines. 
 
 2. The force may be always direfted to a fixed 
 point. 
 
 3. It maybe direfled to a point which is continually 
 changing its place. 
 
 I. When the force afts in parallel lines, the problem 
 ia folved by compounding the reftihneal accelerated 
 motion whiih the force would produce in its own direc- 
 tion with the uniform motion which the projeftion a- 
 lone would have produced. The motion mull be cur- 
 vihneal, when the accelc,rating force is tranfverfe, in 
 any degree whatever, to the projeftile motioa ; and the 
 curvilineal path niuft be concave on that fide to which 
 the deflefting force tends ; for the force is fuppofed to 
 aft inceflantly. The place of the body will be had for 
 any time, by finding where the body would have been 
 at 'he end of that time by each force afting alone, and 
 by completing the parallelogram. Thus, fuppofe a bo- 
 dy projefted along AB (fig. 20.) while it is continual- 
 ly afted on by a force whofe diretlion is AD. Let D 
 and B be the places where the body would be at the 
 end of a given time. Then the body will at the end 
 of that time be in F, the oppofite angle of the paral- 
 lelogram ABFD. But it has not defcribed the diago- 
 nal AF ; becaufe its motion has been curvilineal, as we 
 (hall find by determining its place at other inftante of 
 this time. 
 
 The velocity in any point F is found by fifft deter- 
 mining the velocity at D, and making DT to DF as 
 the velocity at D to the velocity at B (that is, the ve- 
 locity of projeftion, becaufe the motion along AB is 
 uniform). Then draw TF. Then AB is to TF as 
 the conilant velocity of projeftion to the velocity at F. 
 We have feen already (no i i 2 — 1 19.) that TF is a tan- 
 gent to the curve in F. Hence we may determine the 
 velocity at F in another way. Having determined the 
 iorm of the path in the way already defcribed, by find- 
 ing its different points, draw the tangent F d, cutting 
 the line DA in d. Then the velocity at A is to that 
 at F as AB to ii¥. Hence alfo we fee, that the velo- 
 cities in every point of the curve are proportional to the 
 portion of the tangents at thofe points which are inter- 
 cepted between er,y two lines parallel to AD. 
 
 Either of thcfe methods for ajcertaining the velocity, 
 in this cafe of parallel deficftions, will in general be 
 eafier than the general method in n' 121. by the tqui- 
 curve circle. 
 
 It was thus that Galileo difcovered the parabolic mo- 
 tion of heavy bodies. 
 
 2 We muft confider the motions of bodies afFefted 
 by centripetal or centrifugal forces, always tending to 
 one fixed point. This is the celebrated inverfe problem 
 of centripetal forces, and is the 42d propofition of the 
 ilft book of Newton's Principia. We fliall give the 
 folution after the manner of its illuftrious author ; be- 
 caufe it is elementary, in the puicll fenfe of the word, 
 
 la;. 
 
 keeping in view the two leading circumflancc!, andOfDfflcft. 
 thcl'e only, namely, the motion of approach and lecefs'"*! Foiccj. 
 from the centre, and the motion of revolution. By v^™' 
 this judicious priicefs, it becomes a pattern by which 
 more refined, iind, in f.mie refpeft:, better iolutions 
 (hould be modelled. At the fame time we Hiall fupply 
 fome fteps of tiic inveftigation which his eletjant concife- 
 nefs has made him omit. 
 
 Let a body, which tends to C (fig. 24 ) with a force 
 proportional to tlie ordinates of the exponent BLFG, 
 having the axis CA, be projefted from V in the direc- 
 tion VQ, witli the velocity which the centripetal force 
 would generate in it by accelerating it along AV. It 
 is required to determine the path or orbit VIKI cf the 
 body, and its place 1 in this orbit, at the end of the af- 
 figned time T ? 
 
 Suppole the thing done, and that I is the place of 
 the body. About the centre C, with the diilances CV 
 and CI, defcribe the circles YV and ID. Draw CIX 
 to the circumference, and draw the ordinate DF of the 
 exponent of forces, producing it toward .v, and produce 
 the ordinate VL toward a. Let V / be the diftance to 
 which the body would go along the tangent VQ iu 
 the time T, and join / C. Let this be fuppofed done 
 for every point of the curve. Let a i it and axy be 
 two curves fo related to the curve VIK, that the ordi- 
 nate DF cuts off an area V a / D equal to the orbital 
 feftor VCI, and an area V a x H equal to the circular 
 feftor vex. 
 
 Then, becaufe the velocity of projeftion is given, 
 the dillance V / is known, and the area of the triangle 
 VC t. But this is equal to the area VCI, by the laws 
 of central forces (n° 115.). Therefore the area Va/D 
 is given. Alfo, becaufe the area VCI increafes in the 
 proportion of the time, the area V a i D increafes at the 
 fame rate. Therefore having thcfe fubfidiary curves 
 a i k, axy, the problem is folved as follows : 
 
 Draw an ordinate D (, cutting off an area V a ;' D 
 proportional to the time, and defciibe a circle DIR. 
 Then draw a line CX, cutting off a fetter VCX, equal 
 to the area V a x D cut off by the ordinate Hix. This 
 line will cut the circle DR in the point I, which is the 
 point of the orbit that was demanded. 
 
 But the chief difficulty of the problem confifts in the 
 defcription of the two fubfidiary curves ai k and a x y, 
 into which the lines VIK and VXY are transformed. 
 We attain this conftruftion by refolving the motion in 
 the arch of the orbit into two motions, one of which 
 is in the direftion of the tranfverfe force, or of the ra- 
 dius veftor, and the other is in the direftion of revolu- 
 tion, or perpendicular to the radius. 
 
 Let V k and IK be two very fmall arches defcribed 
 
 in tqua] moments, and therefore ultimately in the ratio 
 
 of the velocities in V and I (n° 73.). Defcribe the 
 
 circle KE, cutting IC in N. Draw KG and i C, and 
 
 k n perpendicular to VC. 
 
 IC X KN 
 
 The element ICK of the orbit is = , or 
 
 2 ' 
 
 to -J IC X KN. This is equal to the element D i i E 
 
 of the area V a i D, or to D i X DE, or to D / X IN. 
 
 Therefore IN : KN = 4^ IC : D ;", or 2 IN ; KN = 
 
 rr, T. • , ^ ICXKN 
 IC : D /, and D i = tv-t 
 
 2 IN 
 
 Novv let A Ifg h be the exponent of the velocities, 
 
 that
 
 D Y N A 
 
 OfDenefl-that I's (no 86.), let V / ' be to D/' as ABLV to 
 
 ilif^ ABFD,orV/:D/= V'ABLV: a/ABFD. Make 
 
 V V and I ;' in the tangents refpeClively equal to V / 
 
 and Dy. Draw -v u and /' o perpendicular to VC and 
 
 IC, and V m pcrpendiciili.r to LV produced. Let 
 
 m r z be an equilateral hyperbola, having VC, ZC, for 
 
 its aflyniptotes, and cutting FD produced in r. Then 
 
 the ordinates V iti, D r, arc invtrfely proportional to 
 
 CV, CD, or V »; : D r = CD : CV, = CI : CV. But 
 
 becaufe the momentary fedtors VC i and ICK are eq^ual, 
 
 i n : KN = CI : CV. Therefore, 
 
 V ffl : D ,=;(•«: KN 
 
 but y v -.V m = V i : i n 
 
 and i; (or D/) : Vt> = IK : V/5 
 
 therefore I »' : D r = IK : KN 
 
 but I » : «' ;= IK : KN, by iim. triang. 
 
 Therefore D /• = i o, and « o : V m = VC : CI. 
 
 Alfo, by (imilarity of triangles, I o : / a = IN : KN, 
 
 and 2 I : /' = 2 IN : KN. 
 
 Now it was (hewn, that in order that the fpace 
 
 D i i E may be equal to the fpace ICK, wc mud have 
 
 2 IN : KN = IC : D i 
 
 or 2 I : i = IC : D / 
 
 but «■ : V m = VC : IC 
 
 therefore 2 I o : V w = VC : D- « 
 
 ,^. VCXV;« 
 
 and D z = ■ ^f • 
 
 2 I 
 
 Having obtained D i, we eafily get D x ; for the ul- 
 timate ratio of ICK to XCY is that of IC to VC. 
 Therefore make 
 
 1C= : VC^ = D <■ : D AT. 
 
 Thus are the points of the two fubfidiary curves 
 aii, axy, determined. 
 
 The redlangle VC X V m is a conftant magnitude ; 
 and is given, becaufe VC is given, and V m is the given 
 velocity V /, diminilhed in the ratio of radius to the line 
 of the given angle CVQ- 
 
 But the line 2 I o is of variable magnitude, but it is 
 dfo given, by means of known quantities. I o^ is 
 = I n-i o'= D/'— 1) r\ and I o = ^ITf^—Hr'. 
 
 \& X V m"- 
 Moreover, D/' = ABFD, and D''= 
 
 IC^ 
 
 Therefore 2 I 
 
 0= 2 J ■ 
 
 ABFD — —^-^^-l, ex. 
 
 VC=_XV 
 "IC^" 
 
 preflTtd in known quantities, becaufe ABFD is known 
 from the nature of the centripetel force. 
 
 Let the indeterminate didance CI or CD be i= x, 
 and let the ordinate DF, eN.prefGng the force, be j'. Let 
 VC be a, and V m be c, and let a i be a reflangle equal 
 to the whole area of the exponent of force lying be- 
 tween the ordinate AB and the ordinate CZ, fo that 
 
 ah — I y X may reprefent the indeterminate area 
 
 ABFD. 
 
 a c 
 
 We have D i z= 
 
 and D K .= 
 
 y~ . a- c'- 
 
 ab-Jyx --^ 
 
 a ' c 
 ^.J ab-fyx -^ 
 
 Remark. We have hitherto fuppofed that the ve. 
 locity of projeftion is acquired by acceleration along 
 AV. But this was merely for greater fimplicity of ar- 
 
 M I C S. ^^^ 
 
 gument, and that the final values of D i and D x might Of Dcflecft- 
 be eafier conceived. In whatever way the velocity is "'V. ^'urces. 
 acquired, it will (lill be true, that when in any point V ' ' 
 
 ■v/i: make V / to V m as the momentary increment V k 
 of the arch is to the perpendicular /■ n on the radius vec- 
 tor, we (hall have in every other point, fuch as 1, the 
 line D/to the line D r as the increment IK of the 
 arch to KN. And in the final equation D/will (lill 
 be exprclTed hy ^y a b — /' 
 
 Cor. I. The angle which the path of the projeflile ufi, 
 makes with the radius veftor is determined by this fo- 
 lution ; for I i is to i o as radius to the fine of this 
 
 angle ; which fine is therefore := 
 
 Wab—Jy^, 
 
 Cor. 2. When the magnitude is equal to 
 
 */ ab — I'y X, t^ie path is perpendicu'ar to the radius vec- Apfide/de-- 
 tor, and the body is a tone of the apfides of its orbit, and '"■"'"''^ > 
 begins to recede from the centre after having approach- 
 ed to it, or begins to approach after having receded. ,2S 
 
 Cor. 3. The curvature of the orbit VIK is alfo de- Ar\ii curva.- 
 termined in every point; for the curvature of any line'""- 
 is inverfely as the radius of the equicurve circle, and 
 this is to the chord which pafFes through C as radius to 
 the fine of the angl e CI r. Becaufe the velocity in any 
 point I is = V ABFD, and is equal to what the centri- 
 petal force at I would produce, by impelling the body 
 along ^th of the deileftive chord of the equicurve circle, 
 
 . , ABFD 
 
 we have this chord = 4 — Typ — Or we obtain it by 
 
 taking a third proportional to the momentary deflexion 
 and the momentary arch of the curve, or by other pro- 
 ccfTes of the higher geometry, all proceeding on the 
 quantities furnilhed in this invelligatiun. 
 
 Such is the folution of this celebrated problem given I^I^.v^,'n',(,p.. 
 by Sir Ifaac Newton, who may juftly be called the in- inventor, 
 ventor of the fcience of which it is the chief refult, as 
 well as of the geometry, by help of which it is pro- 
 fecuted. For we cannot give this glory to Galileo ; 
 for his fimple problem of the motion of bodici a(fe£\ej 
 by uniform and parallel gravity, however juft and ele- 
 gant his folution may be, was peculiar ; and the fame 
 mull be faid of Mr Huyghens's doClrine of centrifugal 
 forces. Befides, thefe theorems had been invciligated 
 by Newton feveral years before, y"«a mathejl facem prc- 
 fercnte, as corolhries which he could not pafs unnoticed, 
 from his general method. This is proved by letters 
 from Huyghens. Newton's invedigation is extremely, 
 but elegantly, concife, and is one of the bed exertions 
 of his fagacious mind. 
 
 Whether we coiifider this problem as a piece of mercHiftorv cf 
 mathematical (peculation, or attend to its conrequences,this pro- 
 which include the whole of the celedial motions in allb'em. 
 their extent and complication, we mud allow it to be 
 highly intertding, and likely to engage much attention 
 in the period of ardent inquiry wlu'eh clofcd the lalt 
 century. Accordingly, it was no fooner known, by 
 the publication of the Alatljemaiical Princ'iphs of Na- 
 tural Ph'ilof'jphy in 1686, than it occupied the talents 
 of the mod eminent niatheui.iticians ; and many folu- 
 tions were publifiied, fome ot which differ confiderably 
 from Newton's ; fome are more expeditious, and better*' 
 fitted for computation. Of thefe, the mod remarkable .- 
 
 foxx
 
 544- 
 
 DYNAMICS. 
 
 of Dcfleil for originality and ingenuity are thofe of de Moivre, 
 .•"g '•"°"'''; Hermann, Keill, and Stewart. The laft differs moft 
 ' from the methods purfued by others. M'Laurin's pro- 
 pofitions on this fiibjeft, and in that part of his fluxions 
 which treats of curvature, are highly valuable, clading 
 the chief affcdions of curvilineal motions geometrical- 
 ly, as they are fuggefted by the fluxionary method ; 
 and then (hewing, in a very indrndive manner, the con- 
 nexion between thefe mathematical afi"eftions of motion 
 and the powers of nature which produce them. This 
 part of his excellent work is a fine example of the real 
 nature of all inquiries in dynamics ; fhewing that it dif 
 fers from geometry little more than in the language, in 
 which the word force is fubftituted for acceleration, re- 
 tardation, or dejledion. We recommend the careful per- 
 ufal of thefe propofitions to all who wifh to have clear 
 conceptions of the fubjeft. Dr John Keill and Dr 
 Horfeley (bifhop of Rochefler) have given particular 
 treatifes on the motions of bodies deflefted by centripe- 
 tal forces inverfely proportional to the cubes of the dif- 
 tances ; induced by the fingular motions which refult 
 from this law of adlioii, and the multitude of beautiful 
 propofitions which they fugged to the mathematician. 
 Newton, indeed, tirft perceived both of thefe peculiari- 
 ties, and has begun this branch of the general problem. 
 He firll demonllratcd the dtfcriptlon of the logarithmic 
 and hyperbolic fpirals, and indicated a variety of curi- 
 ous recurring elliptical fpirals, which would be defcri- 
 bed by means of this force, and (hewing that they are 
 all fufceptible of accurate quadrature. Several of thofe 
 authors affeft to confider their folutions as more per- 
 feft than Newton's, and as more immediately indica- 
 ting the remarkable properties of fucli motions; and alfo 
 affeft to have deduced them from different and original 
 principles. But we cannot help faying, that their claims 
 to fuperiority are very ill founded ; there is not a prin 
 ciple made ufe of in their folutions which was not 
 pointed out by Newton, and employed by him. The 
 appearance of originality arifcs from their iiaving taken 
 a more particular concern in fome general property of 
 curvillneal motions ; inch as the curvature, the centri- 
 fugal force, &c. and the making that the leading ftep of 
 their procefs. But Newton's is dill the beft ; becaufe It 
 is ftriclly elementary, aiming at the two leading clr- 
 cumftances, the motion to or from the centre, and the 
 motion of revolution round that centre. To thefe two 
 piirpofes he adapted his two iubfidiary curves. This 
 procedure became Newton, pater, el rerum inventor, 
 who was teaching the world, and who might fay, 
 
 jivia Fieri Jum peragro loca, nuIUus ante 
 Trita peile 
 
 Sinffukr Is it not furprlfing, that 25 years after the puhlica- 
 
 boaft of ti'on of Newton's Principia, a mathematician on the 
 n ull ' <^ont'nf"t (hould publiih a folution in the Memoirs of 
 the French academy, and boaft that he had given the 
 firft demonftration of it ? Yet John Bernoulli did this 
 in 1710. Is it not more remarkable that this rtiould 
 be preclfely the folution given by Newton, beginning 
 from the fame theorem, the 40th I. Prin. following 
 Newton in every ftep, and ufing the fame fubfidiary 
 lines ? Yet fo it is. Bernoulli aftually reduces the whole 
 
 a c 
 to two funftions; namely,' 
 
 and 
 
 / a b X* — f f ^* — "^ <:^ • 
 plainly the fame with Newton's 
 
 ^-=.; which lalt IS Ing force. 
 
 Q_y CX' 
 
 A' v'ABDF — Z'J 
 
 ^ oh — ^t t — 
 
 becaufe Newton's-r— is the fame with — ,and Newton's 
 
 -♦ .V 
 
 AVACFD — ZMs the fame with .v' /a i>—/, x 
 
 — a"- c^ 
 
 1 — , which Bernoulli has changed (apparently to hide 
 
 the borrowing) into / a b x* — j p x* x — a' <:» x'. 
 
 This publication of Bernoulli Is perhaps the moft impu- 
 dent piece of literary roblcry, for theft is too mild a term, 
 that has ever appeared; and is the more deferving of 
 fevere reprehenlion, becaufe it is full of lefledllons on 
 the fimple and iupremely elegant method of Newton. It 
 is hardly conceivable that a perlon of Bernoulli's con- 
 funmiate mathematical knowlege was fo much blinded 
 by the mechanical procedure of the fymbolical calculus 
 (which indeed is rarely accompanied by any Ideas of the 
 fubjeft in hand) as not to perceive the perfett famenefs 
 of his folution. No ; he ftiews, from time to time, that 
 the phyfical ideas of motion and force were prcfent to 
 his mind ; for he affefts to fiiew, that all Newton's 
 brighteft difcoverles, fuch as the proportionality of the 
 areas and times, &c. flow as corollaries from his proce- 
 dure. 
 
 Bernoulli's chief boaft in this difTertation is, that new 
 philofopliers may he affured that the planets will always 
 dcfcribe conic fedllcns; a truth of which they had not 
 as yet received any proof: becaufe, fays he, Newton's 
 argument for it in the corollary of the i ^th propofitlon 
 is inconclufive, and becaufe he had not been able to ac- 
 commodate his demonftration of the 41ft and 42d pro- 
 pofitlon to the paiticular cafe of the planetary gravita- 
 tion. Two affertions that border on Infolence. New- 
 ton's demonftration in the corollary of thfe 13th propo- 
 fitlon is juft, founded on the principle on which the very 
 demonftration of the 42d, adopted by Bernoulli, pr»- 
 ceeJs, and without which that demonftration is of no 
 force; namely, that a body in given circumftances of fi- 
 tuation, velocity, diretlion, and centripetal force, can 
 defciibe no other figure than what it really defcrlbes. 
 Newton did not accommodate the demonftration of the 
 42d propofitlon to the planetary motions, becaufe he had 
 already demonftrated the nature of their orbits; but 
 mentions the cafe of a force proportional to the recipro- 
 cal of the cubes of the diftance ; not as a dcduftion from 
 the 42d, but becaufe it 'was not a dedu6tIon from It, and 
 admitted a very lingular and beautiful inveftigation by 
 methods totally and eflentially different. 
 
 Bernoulli alfo fays, that Newton's folution does not 
 give us the notion of a continuous path, as his own does, 
 but only informs us how to afcertain points of this path. 
 This is the boldeft of all his affertions. Bernoulli ufes 
 the differential calculus. It is the ejfential charafter of 
 this calculus that it exhibits, and can exhibit, nothing 
 but detached points. This is undeniable. And this has 
 been objefted to Newton's firft propofitlon. But New- 
 ton's fluxionary geometry, of which the calculus exhibits 
 only elements (being the fame with the differential), 
 
 fuppofes
 
 DYNAMICS. 
 
 545 
 
 'nrclunon.fuppofes the continuity of all magnitudes ; and when fcfTcs to involve no notions but thofe 6f force, and its ConchC, 
 
 - » applied to dynamics, is no fuhftitution whatever, but marks and meafures. >—— y-_ 
 
 tlie (//) corpora. This geometry ofTcred itfclf to the NotwithfUnding thefe great omifiions, we niuft ob- 
 
 mind of Newton, the accompliflicd and darling fcholar ferve that no new principle remains to be confidered. 
 
 of Barrow, whofe geometry fl:\(hed on Newton's mind We have given k11 that are necelfary ; and there is no 
 
 as the torch whicli was to ihcvv him the fteps of this queilion that occurs in the cafesomitted, which cannot be 
 
 yet untrodden path. completely anfwercd by means of the propofitions already 
 
 We truft that our readers will not be difpleafed with eftabliilied. We have taught how to difcover the ex- 
 
 our repeated endeavours to defend our great philofo- illence and agency of a mechanical ("orce, to meafure and 
 
 pher from the_ injurious attacks that have been made charaaerife it, and then to (late what will he its various 
 
 on him. During his own illuftrious life, while he was cffefts, according to the circumftances of the cafe, 
 diffufmg light and knowledge around him, and never Proceeding by thefe principles, men have difco'vered «,*r^a/ 
 
 contended for fame, happy in being the inllrndlor of an univerfal faft, that every action of one body on ano-'-''"?'"'' is a 
 
 mankind, he was injured by thofe who ejivied his repu- ther is accompanied by an equal reaction of that q.'-*"'. ''^^ 
 
 tation, while they derived their chief honours from be- ther on the lirft, in the oppofite direftion ; that is, to'^'"ij"' 
 
 ing his beft commentators. Now, fince he has left this cxprefs it in the language of dynamics, " all the pheno.""" ' 
 
 world, he has been more grofsly injured by thofe who mena which make us infer that the body A poifeffes a 
 
 avail themielves of that very reputation : and who, by force by which it changes the motion of the body li 
 
 crude and contemptible inferences from his doftrine of fliew, at the fame time, that B poiTeffes a foice by 
 
 elailic undulations, and grofs mifreprefentations of his which it makes an equal and oppulite alteration in the 
 
 notions of an efhenal fluid, have pretended to fupport motion of A." This, however, is not a doftrine of ab- 
 
 a fyltem of matcnalifm ; and thus have fet Newton at ilrad dynamics : it does not flow from our idea of 
 
 the head of the atheiRical fed, which he held in abhor- force ; therefore it was not included in oui liil of the 
 
 rence. For our part, we always think with pleafiire on Laws of IVIot.on. It is a part of the mechanic-il 
 
 the vvonderful energy ot that great mind; becaufe it gives hiftory of nature, juft as the law of univerfal gravitation 
 
 us a toretalte of thole pleafures that await the wife and is ; and it miVht be called t" " ---'=■ 
 
 good, when the forrows flowing from the iniirmitieS; 
 the vices, and the arrogant vanity of man, are paft ; 
 
 Utque in hoc InfcUci campo, 
 
 Ubi lu3us regtiat, et pavor, 
 Mortalihus prorfus mn abftt folatium. 
 
 Hujus enhn fcrlpta evoivas, 
 Menlemque tantarum reriim capacem 
 Ccrpori caduco fuperjihem credos. 
 
 ght be called the law of Unive'rsal Re- 
 action. Sir Ifaac Newton has, in our humble appre- 
 henfion, deviated from his accuflomed logical accuracy, 
 when he admits, as a third axiom or law of motion. 
 that reaftion is always equal and contrary to adlion. It 
 is a phyiical law, in as far as it is obfrrvcrl to obtain 
 through the whole extent of the folar fyftem. But.New- 
 ton himfelf did not, in the fubfequent part of his noble 
 work, treat it as a logical axiom ; that is, as a law of 
 i-ii T, , ,, n , , . , ... I'uman thought with refpea to motion : for he labours 
 
 nclufioii. - \l """°t be expeded that, m the narrow limits pre- with much folicitude, and with equal fafracltv, to prove 
 fcribed to a work hke ours, we can proceed to confider hy faB and obfcrn,a,ion, that it really Obtains through 
 the various departments of this celebrated problem, the whole extent of the folar fylk-m ; and it is in this 
 V\ e are only giving the out mes of the general dodrines difcovery that his chief claim to unequalled penetration 
 ot dynamics; and we have beflowed more time on thofe and difcernment appears 
 ' t^l wf" ?r^^ elementary than fome readers may Availing ourfelves of this fad, we, with very little ,„!„Yfi 
 
 think they^deferve. We were anxious to give juft con- trouble, ftate all the laws of impnlfion The body A P " n! 
 ceptionso the fuiidamental principles of dynamics; be- for example, moving to the weftward at the raleo by't; 
 
 nai of ^T a T"f^ '"^^ "". r"^%" '" "" "■°'' ^''' P^-- ■"''"''^' --"kes the double body B 
 '^^^ -^,^<i^^on{ir^U., f-ence, and becaufe we fee nioving at tl,e rate of four feet per minute. What muft 
 
 ndso^t n;1"l"T""'"'"r''r1'S^'""''^'^^"" '"' *'" -"''^'l-nce of their Lnu.l impenetralih y 
 neis or want o. precihon, m feveral elementary works and of the equality and contrariety of adion and re! 
 
 on 
 ncd 
 
 which are put into the hands of perfons entering on the aft 
 ftudy. This leads to errors of more confequ 
 a perfon is apt to think; becaufe they affed 
 ing tlumghts of mechanifm itfclf, and o 
 the intimate nature of the vifible univerfe 
 
 ftadv T1,;q 1^-,^=: t f' r & -■ '— —-'on? Tlieir motions muif be fuch that both fuHain 
 
 i!;„„I l' . .iIk™:''"*^ ™°''f =''"'>q^"'^"ce_th3n equal and oppafite changes. ^ They muft give, in fome 
 
 ,-n,Vtl, „„!,.■ e 1 V . ^ - - -y ^»'-"« 'XJi- lead- way or other, //;« indieation of pofltffing equal and op- 
 
 ng thoughts of mechamfm It elf, and our notions of pofite forces. This will be the cafe if, wll the chan- 
 
 ,^, the in imate nature of the vihble univerfe. g.s are completed. A and B move on^ n contad at the 
 
 fc„3for Lut we mull conclude the article witli this great rate of four feet per minute : for here A hs prod iced 
 
 Ifion,. problem Many very general doftrines of dynamics re- in each half of B a change of motion tl and re 
 
 main untouched; all, namely that relate to the rotative fore a totality of chang^ equal to four This ithe 
 
 motion of rigid bodies, and a 1 that relate to the mutual efl-ed, the mark, the mfafure, of the 
 
 adnm of bodies on each other in the way of impulfe. 
 
 :ie inipiil/i-ve force of 
 
 •pL„ ,„, . ■ ■,,,„.' - ....J. A; tor it is tlie whole impidhon- B has produced in 
 
 i'he rotative motions, with tlip /!/,«,■;„„ „f .„„.,t,„_:_ A a chantre f ' -^ • "f" F'"""*-"-" '" 
 
 P f . ri - -- -— ,, „.^....^ in the oppofite 
 
 ^^:MT:±'}fl'"y'': P'''""- ' ='■"'. "-^^ l"'"P-f<^ t" ■""'■ure, of the repulf.e force of A; for it is the whole 
 
 e rotative motions, wi^th the dodrine of mechanic A a change of motion four,''equal to "th'e for"mer".nd 
 momenta, have been confidered at large in the article in the opp^ofite diredion. Th.sl the effed, mTrk; ^"d 
 
 f our7uVSent"toTh''"rT" Z ''' '''''''''ft,'^ T'l^''"' ^"^^ "''^''^ ^'' *'-' "-' "'^f-ve in the coll,- 
 
 CHAH cs In he an-1. „ ■'" ^m"' " - -•" ^-"" °^ '"° ^"™P' °^ '''^ ' '"'^ '^' oblervation is one 
 
 (uXa% ■ , Impulsion will be contidered of the fads on which the reality of the nhyfical Kw of 
 
 th fpecffi?diff7 '" '"'^ rr> -'^ '"d^P- J"^t of ^^qual adion and readion is founded ' 
 
 SVPPL Vo! I Part II DvN^Mics pro- no farther inference from //. 
 
 fad. 
 
 and we can make 
 
 3Z 
 
 But
 
 54=6 
 
 ConcIuGon 
 
 136 
 Ard rota- 
 tion. 
 
 D'Alem. 
 btrc'sgene- 
 »al princi- 
 ple of d^na' 
 Biici. 
 
 D Y N A 
 
 But the event ^ight have been very different. A and 
 B may be two magnets floating on corks on water, with 
 their north poles fronting each other. We know, by 
 other means, that they really polTefs forces by which 
 they equally repel each other. The dynam.ical prin- 
 ciples already eftabliilied tell us alfo what muft happen 
 in this cafe. That both conditions of equal reaftion and 
 fenfible repulfion may be fulfilled, A muft come to reft, 
 , and B muil move forward at the rate of four feet per 
 minute. The lame thing mult happen in the meeting 
 of perfeftly elaftic bcdies, fuch as billiard balls. If 
 elafticities are known to be imperfeft in any degree, our 
 dynamical principles will ftiil ftate the cffetl of their 
 collifion, in conformity to the law of equal reaflion. 
 
 In like manner, all the motions of rotation are explain- 
 ed or predicted by means of the fame principles of dyna- 
 mics applied to the force of cohefion. This is confider- 
 ed as a moving force, becaufe, when the attraftion of a 
 magnet afts on a bit of iron attached to one end of along 
 lath floating on water, the whole lath is moved, although 
 the magnet does not aft on it at all : fome other force 
 afts on it ; it is its cohefion ; which is therefore a mo- 
 ving force, and the fubjetl of dvnamical difcuffion. 
 
 And thus it appears that thefe fubjefts do not come 
 neceflarily, nor, perhaps, with fcientitic propriety, un- 
 der the category of dynamics, but are parts of the me- 
 chanical hillory of nature. Yet, did a work like ours 
 give room in this place, the ftudy of mechanical na- 
 ture might be conllderably improved by giving a fvftem 
 of fuch genera! doftrines as involve no other notions 
 but thofe of force and its meafures, and the hypothcfis 
 of equal reaction. Some very general, nay univerfal, 
 confequences of this combination might be eftablifhed, 
 which would greatly affift the mechanician in the folu- 
 tion of difficult and complicated problems. Such is the 
 propofition, that the mulual actions of bodies depend on 
 their relat'fo! motions only, and require no Incwledge of 
 their real motions. This principle fimplifies in a won- 
 derful manner the mo.ft difficult and the moft frequent 
 cafes of aiftion which nature prefents to our view ; but 
 at the fame time gives a fevere blow to human vanity, 
 by forcing us to acknowledge that we know nothing 
 of the real motion of any thing in the imiverfe, and 
 never (hall know any thing of it till our intellcftual con- 
 ftitution, or our opportunities of obfervation, are com- 
 pletely changed. 
 
 Mr D'Alembert has made this principle ftill more 
 ferviceable for extricating ourfelves from the immenfe 
 complication of a&ions that occurs in all the fpontane- 
 ous phenomena of nature, by prefenting it to us in a 
 different frm, which more diftlnftly exprefles what 
 may be called the elements of the aftioiis of bodies on 
 each other. His propofition is as follows {^fee Ins Dy- 
 namique, page 73.) : 
 
 " In whatever manner a number of bodies change 
 their motions, if we fuppofe that the motion which 
 each body would have in the following moment, if it 
 were perftftiv free, is decompofed into two others, one 
 of which is the motion which it really takes in confe- 
 quence of their mutual aftions, the other will be fuch, 
 that if each body were imprefled by this force alone 
 (that is, by the force which would produce this motion) 
 the whole fyftem of bodies would he in equilibrio." 
 
 This is almoft felf-evident ; for if thefe fecond confti- 
 tuent forces be not fuch as would put the fyftem in 
 equilibrio, the other conftituent motions could not be 
 
 M I C S. 
 
 thofe which the bodies really take by the mutual adion, Condufi 
 but would be changed by the firft. v— 
 
 For example, let there be three bodies P, Q, R, and 
 let the forces A, B, C, aft on them, fuch as would give 
 them the velocities />, q, r, in any direftions what- 
 ever, producing the momenta, or quantities of motion, 
 PX^, QXy, RXr, which we may call A, B, C, be- 
 caufe they are the proper meafures of the moving 
 force. Let lis moreover fuppofe, that, by ftriking each 
 other, or by being any how connefted with each other, 
 they cannot take thefe motions A, B, and C, but 
 really take the motions a, b, and c. It is plain that we 
 may conceive the motion A impreffed on the body P, 
 to be compofed of the motion a, which it really takes, 
 and of another motion u. In Hke manner, B may be 
 refolved into b, which it takes, and another ^ ; and C 
 into c and «. The motions will be the fame, whether 
 we aft on P with the force A, or with the two forces 
 a and a ; whether we aft on Q_with the force B, or 
 with b and /5 ; and on R with the force C, or with c 
 and K. Now by the fuppofition, the bodies aftually 
 take the motions a, b, and c ; therefore the motions =, 
 /3, and «, mull be fuch as will not derange the motions 
 a, b, and c ; that is to fay, that if the bodies had only 
 the motions «, ^, and «, imprefled on them, they would 
 dcilroy each other, and the fyftem would remain at reft. 
 Mr D'Alembert has applied this propofition with 
 great addrefs and fuccefs to the very difficult queftions 
 that occur in the motions and aftions of fluids, and 
 many other moft difficult problems, fuch as the precef- 
 fion of the equinoxes, &c. The caule of its utility is, 
 that in moft cafes it is not difficult to find what forces 
 will put a fyftem in equilibrio ; and, combining thefe 
 with the known extraneous forces whofe effefts we are 
 interefted to difcover, we obtain the motions which 
 really follow the mutual eftion of the bodies. 
 
 This is not, properly fpeaking, a principle : it is a 
 form in which a general faft may be conceived. In 
 the fame way the celebrated mathematician De la 
 Grange obferved, that a fyftem of bodies afting on 
 each other in any way, is in equilibrio, if there be 
 imprefled on its parts forces in the inverfe proportion, 
 of the velocities which each body takes in coniequencc 
 of their aftion or conneftion ; and he exprcftes this mii- 
 verfal faft by a very fimple formula ; and calling this 
 alfo a principle, he folves every qucftlon with eafe and 
 neatnefs, by reducing it to the inveftigalion of thofe 
 velocities. In this way he has written a complete fyf- 
 tem of dynamics, to which he gives the title of Aleche- 
 riqiie Amilytiqne, full of the moft ingenious and elegant 
 foliitions of very intereftiiig and difficult problems; and 
 all this without drawing a line or figure, but accom- 
 plilhiiig the whole by algebraic operations. 
 
 But thii is not teaching mechanical philofophy ; it is ijjr 
 merely employing the reader in algebraic operations, 
 each of which he perfeftly underftands in its quality of 
 an algebraic or arithmetical operation, and where he 
 may have the fuUeft conviftion of the juftnefs of his 
 procedure. But all this may be (and, in the hands of 
 an expert algebraift, it generally is), without any no- 
 tions, diftinft or indiftinft, of the things, or the pro- 
 ceflTes of reafooing that are reprefented by the fymbols 
 made ufe of. It is precifely like the occupation of a 
 banker's clerk when he carries his eye up and down the 
 columns of pounds fhillings and pence, calculates the 
 compouttd intereftj reverlionary values, &c. 
 
 It
 
 onclurinn. 
 Ifidvau 
 
 D Y N A 
 
 It were well if this were all, although it greatly di- 
 miiiinies the pleafurc which an accoaiplilhcd mathema- 
 tician might receive ; but this total abi'ence of idciis ex- 
 pofes tviii the moll eminent analyft to frequent riilis of 
 paralogifm and phyfical ajjfnrdity. Euler, who was 
 perhaps the moll expert algcbraift of the lad century, 
 making ufe of the Newtonian theorem for alcerf.iining 
 the motion cf a body impelled along a (Iraight line AC 
 (fig. 24 ) by a centripetal force, by compari.ig it with 
 the motion in an ellipfe, of which the fhorter axis was 
 diminiflied till it vaniihed altogether, exprell'es his fur- 
 prife at finding, that when he computes the place of 
 the body for a time fubfequent to that of its arrival 
 at C, the body is back again, and in feme place be- 
 tween C and A ; in Ihort, that the body comes back 
 again to A, and plays backward and forward. He 
 fays that this is fomewhat wonderful, and feems in- 
 co'.ihlteiit wit'a found rcalon : "_/«/ analyji rna^is Jiihn- 
 t!um" It mull: be fo. And he g'ocs on to another 
 problem. 
 
 In like manner Mr Maupertuis, an accomplilhed man 
 and gf'iid philofopher and geometer, finding the iym- 
 bol MVS, or the quantity of matter, multiplied b) the 
 velocity and by the diifance run over during the ac- 
 tion, always prefent itfelf to him as a mathematical mt- 
 7iimum in the adlions of bodies on each other ; he was 
 amufed by the obfervation, and prefumed that there 
 was fome reafon for it in the nature of things. Find- 
 ing that it gave him very neat folations of many ele- 
 mentary problems in dynamics, he thought of trying 
 whether 11 would affift him in accounting for the con- 
 ftant ratio of the fines of incidence and rcfraftion ; he 
 found that it gave an immediate and very neat folution. 
 This problem had, before his time, occupied the minds 
 of Des Cartes and Fermat. Each of thefe gentlemen 
 folved the problem b-y iaying, that the light did not 
 take the Jburhfi way from a point in the air to a point 
 under water, but the f(7//f/? way, in conformity with the 
 acknowledged economy of nature and confummate wif- 
 dom of its adorable Author. But how was this the 
 eafieft way, the courfe that economifed the labour of 
 nature ? One of thefe gentlemen proved it to be fo, if 
 light move fafter in air than in water ; the other pro- 
 ved it to be fo, if light move fafter in water than in air. 
 Both could not be right. Maupertuis was convinced 
 that he had difcovered what it was that nature was fo 
 chary of, and grudged to wafte — it was MVS! There- 
 fore MVS can mean nothing but labour ; nothing but 
 natural exertion, mechanical aftioif ; therefore MVS is 
 the proper m'eafure of aftion. 'He kept this great dif- 
 covery a profound fecret ; and, being Prefident of the 
 Royal Academy of Berlin, he propofed for the annual 
 prize queftiou, " Are the laws of motion necefTary or 
 contingent truths ?" He could not compete for the 
 
 M I C S. 547 
 
 prizei by the Uw8 of the Academy ; but before tbeCnnduCmn. 
 time of decillon, he publilhed at Paris his Di^'itat'ion on » 
 the Principle of the lenjl ASion; in which he pointed out 
 the fmgular taft of MVS being always a minimum; and 
 theretorc, in tart, theobjeft of nature's economical care. 
 He folved a number ol problems by making the mini. 
 
 mum flate of < a condition of the iiroblems ; and, 
 
 »; 
 
 to crown the whole, fhewed that the laws of motion 
 which obtain in the univerfo could not be but whit 
 they are, bec;nife this economy was worthy of infinite 
 wifdom ; and thenj'ure any other laws were impoffible. 
 The reputation of Maupertuis was already ettabliflied 
 as a good matliematician and a worthy and amiable 
 man, and he was a favourite of Frederic. The princi- 
 ple of ieaft aiftion became a mode ; and it drew atten- 
 tion for fome time, till it went out of fafliion. It is 
 no mechanical principle, but a ncceffary mathematical 
 truth, as any perfon muft fee who recollerts that -u is 
 
 the fame with s, and thatyis the fame with in i). 
 
 To avoid fuch paralogifms and fucli whims, we are Great ad- 
 convinced that it is prudent to deviate as little as pof-^^n^ges of 
 fible in our difcufiions from the geometrical method. .^ K^°"'^' 
 This has furely the advantage of keeping the real fub-,}jod. 
 jeft of difcuflion clofe in view ; for motion includes the 
 notion of lines, with all their qualities of magnitude 
 and pofitlon. It is needlcfs to take a reprefcntative 
 when the original itfelf is in our hands, and affords a 
 much more comprehenfible objefl than one of its ab- 
 ftraft qualities, mere magnitude. Let any perfon can- 
 didly compare the lunar theory by Mayer or Euler 
 with that by its illuilrious inventor Sir Ifaac Newton, 
 and fay which of the two is mofl luminous and moit 
 pleafing to the mind. No perfon will deny that thefe 
 later performances are incomparably more adapted to 
 all prartical purpofes, and lead to corredliona which it 
 would be extremely difficult and tedious to inveftigate 
 geometrically ; but it mull be acknowledged, at the 
 fame time, that till this be done, we have no idea what- 
 ever of the deviation of the track which this correftion 
 afcertains from the path which the moon would follow, 
 independent of the difturbaucc exprcded by the cor- 
 rertiou. In like manner, Dan. Bernoulli, by mixing as 
 much as pofTible the linear method with the algebraic, 
 in his differtations on mufical chords, made the beauti- 
 ful difcovery of the fecondary trochoids, and demon- 
 ftratcd the co-exillence of the harmonic founds in a full 
 mufical note. Let the accomplilhed mathematician pufh 
 forward our knowledge of dynamics by the employment 
 of the fymbolical analyfis ; but let him be followed a> 
 clofe as polFible by the geometer, that we may not be 
 robbed of ideas, and that the ftudent may have light to 
 direft his lleps. But, — manum e taluld. 
 
 ■«w*rsRfs^ 
 
 nano- 
 eter. 
 
 D Y N 
 
 DYNANOMETER, an inftrument for afcertaining 
 the relative mufcular ftrength of men and other animals. 
 That It would be defirable to know our relative ftrengths 
 at the different periods of life, and in different ftatcs of 
 health, will hardly be denied ; and there can be no 
 doubt but that It would be highly ufcful to have a 
 portable Inftrument by which we could afcertain the 
 lehtive ftrength of horfes or oxen intended for the 
 
 D Y N 
 
 plough or the waggon. Such an inftrument was invent- 
 ed, many years ago, by Graham, and improved l>y De- 
 faguliers; but being conftruCted of wooden work it was 
 too bulky to be portable, aud therefore it was limited 
 in Its ufe. 
 
 M. Leroy of the Academy of Sciences at Paris con- 
 
 ftrudled a much more convenient Dynanometer than 
 
 Graham's, confiding of a metal tube, 10 or 12 inches 
 
 3 Z 2 in
 
 D Y S [ 548 ] D Y S 
 
 . iti length, placed vertreally on a foot like that of a can- horfes or oxen may be employed to comprcfs the fpring. rij- 
 dltilick, and containlnjr in the infide a fpii'al I'pn'ng, But as any mechanic may devlfe means for this purpofe, '~ 
 having above it a graduated ihank terminating in a we do not think it worth while to tranfciibe that de- 
 globe. This fhank, together with the fpring, fniik into fcription. The Englifh reader will find a full account 
 th'e tube in proportion to the weight aiSing upon it, of the whole apparatus in the 4th number ot the very 
 and thus pointed in degrees tlie llicngth of the perfon valuable mifcellany intitled The Ph'dofoplncal Magazine. 
 ■who pveiTeJ on the b?.ll with his hnnd. The principle of the contrivance confills in the ellipti- 
 This was a very fimple conllruflion, and, we think, cal fpring, of which we confcfs ourftlves unable to per- 
 a good one; but it did not fatisfy Buffon and Gueneau. ceive the fuperiority to the fpiral fpring of M. Lf. oy, 
 
 fentei 
 
 de I* EcMe 
 Polytrcb- 
 ni^ue^ V. a. 
 
 Thefe two philofophcrs wi(hed not merely to afcertain 
 the mufcular force of a finger or a hand, but to efti- 
 mate that of each limb feparately, and of all the parts 
 of the body. They therefore employed M. Regnier 
 to contrive a new dynanometer ; and the account which 
 he gives* of his attempts to fulfil their wifhes is calcu- 
 lated to enhance the difficulty of the enterprize. The 
 
 though the author fees it very clearly. 
 
 DYSENTERY. See MEDiciNE-/n^/«, Encycl.— 
 For the cure of tliis difeafe we have tiie following finipk 
 prefcription by Dr Perkins and Dr B. Lynde Oliver, 
 of the State of Malfachufetts in North America. 
 
 Saturate any quantity of the beft vinegar with com- 
 mon marine fait; to one large table-fpoonful of this fo- 
 
 inftrument, however, which he conftrufted, is not futh lution add four times the quantity of boiling water; let 
 
 as appears to us to have required any uncommon ilvill the patient take of this preparation, as hot as it can be 
 
 In mechanics, or any very great ftretch of thought. It fvvallowedy one fpoonfu! oace in half a minute until the 
 
 confills chiefly of an elh'ptical fpring, 12 inches in whole is drank : this for an adult. The quantity may 
 
 length, rather narrow, and covered with leather that it be varied according to the age, fize, and eonlUtution of 
 
 may not hurt the fingers when compreiTed by the hands, the patient. If neceffary, repeat the dole once in fix or 
 
 This fpring is compofed of the btft fttel well welded 
 and tempered, and afterwards fubjefted to a fti onger 
 effort than is likely to be ever applied to it either by 
 men or animals, that it may not lofe any of its elalli- 
 city by-ufe. 
 
 The effefts of this machine are eafily explained. If 
 
 ecglit liours. Confiderable evacuations I conceive (fays 
 Dr Parkins) to be _not only unneccffary, but injurious, 
 as they ferve to debilitate and prolong the dileafe. A 
 tea of plantain, or fome other cooling fimple drink, may 
 be ufeful; and if a thirft for cyder be difcovered, it may 
 be gratified. Carefully avoid keeping this preparation 
 
 a perfon compreflfes the fprmg with his hands, or draws in vcflels partaking of the qualities of lead or copper, as 
 
 it out lengthwiCe by pulling the two extremities in con- ''- "'" J-- J l- .1 - -«••<. .1 - 
 
 trary direftions, the fides of the fpring approach towards 
 each other; and it has an apparatus (we do not think 
 a very fimple one) appended to it, confifting of an in- 
 dex and femicircular plate, by which the degree of ap- 
 proach, and confequently of effort, employed, is afcer- 
 tained with great accuracy. The author gives a tedi- 
 ous defcription of other appendages, by means of which 
 
 the poifon produced by that means may prove dangerous. 
 The fuccefs of the remedy depends much on prepa- 
 ring and giving the dole as above direfted. — The fim- 
 plicity of this treatment renders it the more valuable, 
 as all perfons have it in their power to avail themfclvts 
 of its life. 
 
 Dr Perkins fays, that he has found it ufeful in agues, 
 diarrhosas, and the yellow fever. 
 
 E. 
 
 larih. 
 
 EAR 
 
 EARTH, in chemiftry. See CHEMISTRY-Zwifw in 
 this Supplement. 
 
 Earth, in aftronomy and geography. See Encydo- 
 picdia. 
 
 Earth, in ancient philofophy, one of the elements, 
 the fubftance of which this globe is compofed. To af- 
 certain the denfity of that fubftance, many experiments 
 have been made; but perhaps none more ingenious than 
 thofe of Mr Caveudilh, which are detailed at full length 
 in Part II. of the Tranfaftions of the Royal Society 
 of London for 1798. They were projefted by the 
 late Rev. John Michell, F. R. S. but he did not live to 
 carry them into effei^. After his death, the apparatus 
 came to the Rev. F. J. H. Wollafton, Jaekfonian Pro- 
 feffor at Cambridge,- who transferred them to Mr Ca- 
 vendidi. The apparatus contrived for making fenfible 
 the attraftion of fmall quantities of matter, and which 
 has been improved by Mr Cavendilh, is very fimple : it 
 
 EAR 
 
 confifts of a wooden arm 6 feet long, fufpcnded by the 
 middle in an horizontal pofition by a flender wire 40 '■ 
 inches long ; to eagh extremity is hung a leaden ball 
 about two inches in diameter; and the whole is inclofed 
 in a wooden cafe to defend it from the wind. 
 
 As no more force is required to turn this balance on 
 its centre t^an is neceffary to twifl the flender fufpend- 
 ing wire, the fmallcfl degree of altraftion of a leaden 
 weight or weights, a few (eight) inches in diameter, 
 brought near to the fmall fufpended ball or balls of the 
 balance, will be fufEcient to move it fenfibly afide. 
 
 To determine from hence the denfity of the earth, all 
 that is neceffary is, to afcertain what force is required 
 to draw the arm afide through a given fpace, and then 
 to have recourfe to calculation. 
 
 To prevent any difturbance from currents that might 
 be produced within the box that contained the balance, 
 by even the difference of temperature that might be oc- 
 
 cafioned
 
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 Eaith. 
 
 EAR [ 549 ] E A U 
 
 cafioncd by heat being communicated by tlic bodies of lent lymptoms of great uncafinefs. If this liquor be 
 
 ' the experimenters to one fide of it more than another, poured into thofe holes in which the earth-worms refide 
 
 it was fupported in the middle of a clofe room; the underground, they immediately throw thcmfelves out 
 
 operators, from adjoining ajiartments, viewed the ope- as if driven by fomc force ; and, after various contor 
 
 ration through holes in the wall by means of telefcopes; tioiiG, either languilh or die. If the leaves of plants or 
 
 and the apparatus had a Ihong light thrown upon its fruit trees frequented by the voracious caterpillars, 
 
 two ends (an opening being left at each end of the box which are lo dellructive to tliem, be fprinkled over with 
 
 for the purpofe) by means of two lamps, alfo in the ad- this liquor, thefe iiifeds fuddenly cortraft their !)odie» 
 
 joining apartments, the rays from which were likewile and drop to the ground. For tiiough Nature has de. 
 
 made to pafs through the holes formed in the wall. fended them tolerably well by tlicir hairy (kins from 
 
 The two large balls were fufpended from a beam any thing that might injure their delicate bodies, yet as 
 
 near the cieling, which could be moved in an hori. foon as they touch witli their feet or mouths leaves 
 
 zontal dircdtion, by means of a firing and pulley, fo which have been moiilened by this liquor, they become 
 
 as to be brought near to the fmall balls of the balance, as if it were ftupified, inllantly contraft themfelves, and 
 
 or made to recede again, without requiring any perfou fall down. 
 
 to be in the room. With regard to plants or corn, thcfe fuiiain no inju- 
 
 rVom this dcfcrlption it will be eafily fetn, that on ry from the liquor, .becaule it has no power over the 
 
 the two large balls being brought near to the two fmall produftions of the vegetable kingdom, as our author 
 
 ones, but on oppofite fides of each, tliat their forces has fully learned from experience ; or if any hurt is to 
 
 way not counteraft each other — the fmall fufpending be fufpedled, all the danger will be removed by the firft 
 
 wive of the balance muft; be twilled by the movements fhower that falls. This liquor may be procured. In a- 
 
 of the arms, occahoned by attraction, which carries the bundance in every place where lime is burnt. ,If the 
 
 fmall towards the large balls ; and that the wire, cndea- lime be frefli, one part of it infufed into about feventy 
 
 vouring to untwift itielf, will again in its turn carry the parts of common water will produce real lime-water, 
 
 fmall balls away from the large ones. Vibrations are The want of the fixed alkali may be fupplied by boil- 
 
 thus occafioned, which would continue a long time be- ing wood-alhes m water, and thickening the ley by 
 
 fore the fmall balls would fettle between the tirll point evaporation. 
 
 of relt and the large balls : but it is not neceffary to 1'his liquor might be employed alfo to kill bugs and 
 wait for this; an ivory fcale at each end of the balance other domeftic inieifts ; but on account of its tlrong 
 enables the experimenters, by means of their telefcopes, lixivious fmcll, M. Socoloff thinks it could not be ufed 
 to fee the two extreme divifions to which the fmall balls with fafety in houfes that are inhabited. Nothing, how- 
 move in their vibrations, and thus to determine tlie ever, more fpeedily or more effcftually deflroys bugs, 
 middle point. The time necelfery for each vibration is as our author lays he has repeatedly experienced, than 
 alfo noticed. the oily pickle that remains in cafks in which faked 
 A full account of thefe experiments, and of the cal- herrings have been packed 
 
 Earth, 
 Hai delucti 
 
 culations founded on them, would be little interelling 
 to the great majority of our readers. We (hall there, 
 lore only mention the refult. By a mean of the expe- 
 riments the dcnfity of the earth comes out 5 '48 times 
 greater than that of water. 
 
 EAU DE Luce, a fragrant alkaline liquor which 
 was fome years sgo in great repute, efpecially among 
 the fair fex, and of which the leading perfection is, that 
 it fhall pofTcfs and retain a milky opacity. 
 
 Mr Nicholfon, in the fecond number of his valuable 
 
 By the experiments made by Dr Ma(l<elyne on the journal, tells us, that being informed by a philofophicul 
 attraftion of the hill Schehallien, the denfity of the friend, that the ufual recipes for making this compound 
 earth was computed to be only 4y times that of water, (fee Chimistry, EncyJ. n°i037.) do not fucceed. 
 The difference of refult, therefore, is almoft one-fifth, and that the ufe of maftic in it has hitherto been kept 
 which no doubt miiR ItiTen our confidence in either fet a fecret, he made the following trials to procure a good 
 of experiments, or in the principle on which they were eau de luce, 
 devifed. 
 
 EARTH-Worm (fee Lumbricus, Encycl.^, is an ani- 
 mal which occafions fuch dellruftion in gardens, by 
 gnawing the tender roots of fhrubs and plants, that va- 
 rious methods have been propofed for remedying this 
 evil. One of the latcft, and that which promiles to 
 prove the moll fuccefsful, is given by M. Socoloff in 
 the fifth volnine of the New Tranfaflioiis of the Impe- 
 rial Academy of Sciences at Peterfburgh. As the dc- 
 
 One drain of the redlified oil of amber was diffolvcd: 
 ill four ounces of the ftrongeft ardent fpirit of the 
 ihops ; its fpccifio gravity being .840 at 60 degrees of 
 Fahrenheit. A portion of the clear fpirit was poured 
 upon a larger quantity of fine, powdered maftic than if. 
 was judged could be taken up. This was occalionally 
 agitated without heat ; by which means the gum refill 
 was for the moll part gradually diffolvcd. One part of 
 the oily folution was poured into a phial, and to this 
 
 flrutlive power of quick lime, heightened by a fixed al- was added one part of the folution of matlic. No opa- 
 kali, which corrodes or dilfulves all the tender parts of city or other cliange appeared. Four parts of ftrong 
 animals, has been long known, it occurred to our au> cauftic volatile alkali were then poured in, and imme- 
 thor that this mixture would be the beft means for ac- diatcly fhaken. The fluid was of a denfe opake white 
 complifliing the objedl which he had in view. He colour, affording a flight ruddy tinge when the light 
 therefore took three pai-ts of quicklime, newly made, was feen through a thin portion of it. In a fecund 
 and two parts of a faturated folution of fixed alkali in mixture,, tour parts of the alkali were added to one uf 
 water, and thence obtained a foniewhat milky liquor the folution of maflic ; it appeared of a lefs denfe and 
 fuiEciently cauftic, highly hoflile and puifonous to earth- more yellowifii white than the former mixture. More- 
 wot ms and other fmall animals; for as foon as it touch- of the gum rcfinous folution was then poured in ; but it. 
 «:d any part of their bodies, it occafioned in them vio. ftiil appeared Icfs opaque lliau tlmt misture. It was 
 
 fjddj
 
 E C L r SS 
 
 l'5\i<Ieliicr ruddy by tranrmittcd liVlit. T'lU' Lill experiment was 
 Ddiat'c ''"^P''"'^'^ ^'"'' tl^"'" "''y fuiution in (lead of liiat i/t"mallic, 
 ^ 'i'he white was much lefs denfc tlian cither of the fore- 
 
 fjoing compounds, and the reqnifite opacity was not 
 given by augmenting the dofe of the oily folution. No 
 luddinefs nor other remarkable appearance was fcen by 
 tranitnitted light. Thefe mixtures were left at repofe 
 tor two days ; no fcparation appeared in either of the 
 compounds containing mallic ; the compound coulift- 
 ing ot tlie oily iohitiun and alkali became paler by the 
 reparation of a cream at tiie top. 
 
 it appears, therefore, tliat the fir ft of thefe three 
 mixtures, luhjccl to variation of the quantity of its in- 
 gredients, and the odorant additions which may be 
 made, is a good eau de luce. 
 
 In a fublequent number of the fame Journal, we have 
 the following recipe by one of the author's correfpon- 
 dents, who had olten proved its value by experience. 
 " Digcft ten or twelve grains of the whittft pieces of 
 maftic, fcledted for this purpofc and powdered, intwo 
 ounces of alcohol ; and, when nearly difi'olved, add 
 twenty grains of elemi (See Amyrik, Encycl.). When 
 both the refms are diffolved, add ten or fifteen drops of 
 redtlfied oil of amber, and fifteen or twenty of efltnce 
 of bergamot : ihake the whole well together, and let the 
 faeces lubfide. The fulution will be of a pale amber co- 
 lour. It is to be added in very fmall portions to the 
 bed ;iqua ammonia pura:, until it aifumes a milky white- 
 iiefs, (Iraking the phial well after each addition, as di- 
 rected by Macquer. Tlie ilrength and caufticity of the 
 ammoniac are uf moll eHential confequence. If, up- 
 on the addition of the fiift drop or two of the tinc- 
 ture,- a denle opaque coagulated precipitate is formed, 
 not much uidike that which appears on dropping a fo- 
 lution of filver into water (lightly impregnated with 
 common fait, it i* too ilrong, and mull be diluted with 
 alcohol. A conliderable proportion of the tinelure, 
 perhaps one to four, ought to be requifite to give the 
 liquor the proper degree of opacity." 
 
 EAVES Board, or EAVts-I.ATH, a thick feather- 
 edged board, ufually nailed round the eaves of a houfe 
 for the lowermoft tiles, flate, or ihingles, to rell upon. 
 
 ECLIPSAREON, an inl'uument invented by Mr 
 Fergufon for fliewing the phenomena of eclipfes ; as 
 their time, quantity, duration, progrefs, &c. 
 
 ECLIPTIC. See Encycl. both under Ecliptic 
 and in AsTRONOMV-//«/f.-c. It was obferved in As- 
 rRONOMY, Encycl. n° 407. that the obliquity of the 
 ecliptic has been found gradually to decreafe. This 
 was obferved, among others, by La Lanrle, who, in the 
 third edition of his aftrouomy, reckoned tlie fecular di- 
 minution of this obliquity at 50 feccnds. From a new 
 examination, however, of ancient obfervations, he has 
 fince found reafon to ellimate it at only 36 feconds ; 
 but whether this be perfeftly accurate, is very doubtful. 
 The mean obliquity was determined for the ill of Ja- 
 nuary 1793, with circular inftruments, by Mcchain at 
 Barcelona, and Piazzi at Palermo, to be 23° 27' 53" .3. 
 Yet the obfervation of the fummer folllice of 1796, by 
 Mecham and Le Frangais, gave 1 1 feconds more; which 
 was jiiftly confidered as a perplexing circumftance. But, 
 as one of the ableft of our literary journalills obferves, 
 might not this difference arife from the uncertainty of 
 our tables of refradlion, as affeifled by the hygrofcopic 
 variations of the atmofphere ? 
 
 EiziFTic Bounds, or Limits, are the greatell diftances 
 
 i|'t!c. 
 
 ] E D Y 
 
 from t!ie nodes at whitli the fun or moon can be ecllp. F.c'i 
 fed, namely, near 18 degrees for the fun, and li de- ''''y 
 grees for the moon. '"""• 
 
 EDYSTONE Rocks, fo remarkable for the hght- 
 houfe built on them, obtained their name from the 
 great variety of contrary fets of the tide or current in 
 their vicinity. They are fituated nearly S. S. W. from 
 the middle of Plynmuth Sound, according to the true 
 meridian. The dillance from the port of Plymouth is 
 nearly 14 miles, and from the promontory called Ram- 
 itacl about 10 miles. They are almoll in the line, hut Smeaion't 
 fomewhat within it, which joins the Start and the Li- '*"'"'' c/" 
 zard points ; and as they lie nearly in the diretlion of'-" ^•'.'•f""' 
 veifels coafting up and down the channel, they were '^' ' 
 neceffarily, before the eftablilhnient of a light houfe, 
 very dangerous, and often fatal to fhips under fuch 
 cireumitances. Their fituation, likewile, with regard 
 to the Bay of Bifcay and Atlantic ocean, is fuch, that 
 they lie open to the fwello of tlie Bay and ocean from 
 all the fouth-weilern points of the compafs : which 
 Iwells are generally allowed by mariners to be very 
 great and heavy in thofe feas, and particularly in the 
 Bay of Bifcay. It is to be obferved, tliat the found- 
 ings of the fea from the fouth-wcllward toward the E- 
 dyftone are from ^o fathoms to 40, and everywhere till 
 you come near the Edyllone the fea is full 30 fathoms 
 in depth ; fo that all the heavy feas from the fouth- 
 weft come uncontrouled upon the Edyftoiie rocks, and 
 break on them with the utmoft fury. 
 
 The force and height of thefe feas is increafed by 
 the circumftance of the rocks ftretching acrofs the 
 Channel, in a north and fouth direftion, to the length 
 of above 100 fathoms, and by their lying in a doping 
 manner toward the fouth-weil quarter. This_y?;D;n^ of 
 the rock, as it is technically called, does not ceaie at 
 low water, but ftill goes on progrelfively ; fo that, at 
 i;o fathoms wcilward, there arc 12 fathoms water; nor 
 do they terminate altogether at the diftance ot a mile. 
 From this ccnfiguration it happens, that tiie feas are 
 fwelled to fuch a degree in ftorms and liard gales of wind, 
 as to bici'k on the rocks with the utmoft violence. 
 
 The efteft of this flope is likewife fenfibly felt in mo- 
 derate, and even in calm weather ; for the libration of 
 the water, caufed in the Bay of Bifcay in hard gales at 
 fouth-weil, continues, in thofe deep waters for many 
 days, though fucceeded by a calm; infonuich, that when 
 the fea is to all appearance fmooth and even, and its 
 furface unru.*Hcd by the flightell breeze, yet thofe li- 
 brations ftill continuing, wliieh are called the oround- 
 f<we/I, and meeting the ilope of the rocks, the fea breaks 
 upon them in a frightful manner, fo as not only to ob- 
 ftru£l any work being done on the rock, but even the 
 landing upon it, when, figuratively iptaking, you might 
 go to fea in a walnut ihell. A circumftance which ftill 
 farther increafes the difficulty oi working cm the rock 
 is, there being a hidden drop of the furface of the rock, 
 forming a ftep of about four and a half, or five feet 
 high ; fo that the feas, which in moderate weather 
 come fvvelling to this part, meet fo fudden a check that 
 they frequently fly to the height of 30 or 40 feet. 
 
 Notwithftanding thefe difficulties, it is not furprifing 
 that the dangers to which navigators were expofed by 
 the Edyftone rocks (hould make a commercial nation 
 defirous of having a light-houie on them. The won- 
 der is, that any one fhould be found hardy enough to 
 undertake the building. Such a man was firft found 
 
 in
 
 E D Y [55 
 
 ■ in tlie perfon of Henry W'mjlanley of Littlebury in Ef- 
 
 ■Tex, Gent, who, in the year 1696, was furnirlied by 
 
 the tnafter, wardens, and adlftants, of" the Trinity-houfe 
 
 <if Dcptiord-ftrond with the necetFavy powers to carry 
 
 the dciltjn into execution. 
 
 Mr Winftanky had diltinguifhed himfelf in a certain 
 branch of mechanics, the tendency of which is to raile 
 wonder nnd furprife. He had at his lioiife at Little- 
 bury a fct of contrivances, fuch as the following : Be- 
 ing t:ikcn into one particidar room of his houfe, and 
 there obfcrving an old flipper carelefsly lying on the 
 floor ; if. as was natural, you gave it a kick with your 
 foot, up ftarted O- gk'J} hefo/e you. If you fat down in 
 a certain chair, a couple of arms would immediately 
 dafp you in, fo as to render it impofTible to difentant;le 
 youiftlf till your attendant fet you at liberty. And if 
 vou fat down in a certain arbour by the ilde of a canal, 
 you were forthwith fcnt out cfhat to the middle of the 
 canal, from whence it was impoffible for you to efcape 
 till the manager returned you to your former place. — 
 Whether thofe things were (hewn to ftrangers at his 
 houfe for money, or were done by way of amufement to 
 thofe that came to vilit the place, is uncertain, as Mr 
 Winllanley is faid to have been a man of fome proper- 
 ty; but it is at leaft certain, that he eftablifhed a place 
 of p\iblic exhibition at Hyde Park. corner, called IVin- 
 Jlatiley's ivater-ivorLs, which \vere fhewn at dated times 
 at one lliilling each perfon. The particulars of thofe 
 water works are not now known ; but, according to 
 the tafte of the times, we mull naturally fuppofe a great 
 variety oi jets d'eau, &c. 
 
 Thefe particulars are at prefent of no other impor- 
 tarice than that they ferve to give a fkctch of the ta- 
 lents and turn of mind of the original undertaker, and 
 to account for the whlmfical kind of buildings which he 
 erefted on the Edyftone ; from the defign of which, it 
 feems as if it were not fufUcient for his enterpriling ge- 
 nius to ereft a building on the fpot, where, of all others, 
 it was leaft likely to ftand unhurt ; but that he would 
 alfo give it an elevation, in appearance the moft liable 
 to fubjecl it to daiiiage from the violence of the wind 
 and waves. 
 
 This ingenious man entered upon his great undeita- 
 king in 1696, and corrpleted it in fomething more than 
 four years. The tirll tummer was occupied with ma- 
 king 12 holes in the rock, and in fadening f2 great 
 irons, which were to hold the work that was afterward 
 to be done. The next fummer was fpent in making a 
 folid body, or round pillar, 12 feet high and 14 feet in 
 diameter. In the third year, the atorefaid pillar or 
 work was made good at the foundation, from the rock, 
 to 16 feet in diameter ; and all the work was raifed, 
 which, to the vane, was 80 feet high. Being all finiih- 
 ed, with the lantern, and all the rooms that were in it, 
 we "ventured (fays Mr Winllanley) to lodge there 
 foon after midfummer, for the greater difpatch of this 
 work ; but the iirll night the weather came bad, and 
 fo continued, that it was eleven days before any boats 
 could come near us again ; and not being acquainted 
 with the height of the feas rifing, we were almoft all 
 the time drowned with wet, and our provifions in as 
 bad a condition, though we worked night and day, Ss 
 much as polfible, to make fhelter for ourfelves." 
 
 Mr Winftanley, however, fucceeded in fetting up the 
 light on the 14th of November in that year (169S) ; 
 but lie was detained till within three days of Chriftmas 
 
 I ] E D Y 
 
 before he could return to rtiore, being almoft at the lafl Eiyftotif. 
 extremity for want of provifions. -— v— ' 
 
 In the fourth year, oljlerving the effects that the fea 
 produocd ou the houfe, burying the lantern at times, 
 although more th^n 60 teet higli, Mr Winllanley en- 
 compalfed the atorefaid building early in the fpring 
 with a new work of four feet thickuefs from the foun- 
 dation, making all iolid for near 20 feet high ; and ta- 
 king down the upper part of the firll building, and en- 
 larging every part in its proportion, he railed it 4c feet 
 higher than it was at tirll : Ytt, he obferves, " the fea, 
 in times of ftorms, flies in appearance one hundred feet 
 above the vane, and at times doth cover half the fide of 
 the houfe and the lantern as if it were under water." 
 
 No material occurrences concerning this building 
 happened till November 1703, v\hcn the fabric, needing 
 fome repairs, Mr Winftanley went down to Plymouth 
 to fuperintend the work. And " we mull not wonder 
 (fays Mr Smeaton), it, from tlie preceding accounts of 
 the violence of the feas, and the ftrudture of the light- 
 houfe, the common fciife of the public led them to fup. 
 pofe this building would not be of long duration. The 
 following is an anecdote which I received to the fame 
 effect from fo many perions that I can have no doubt 
 of the truth of it : Mr Winftanley being among his 
 friends previous to his going off with his workmen 011 
 account of thofe reparations, the danger being intima- 
 ted to him, and that one day or other the light-houfe 
 would certainly be ovcrfct ; he replied, " He was fo 
 very well afl'ured of the ftrength of his building, he 
 fhould only widi to be there in the greateft ilorm that 
 ever blew under the face of the heavens, that he might 
 fee what efFeft it would have on the ftiutture." — It 
 happened that Mr AVinftanley was but too amply gra- 
 tified in this with ; for while he was there with his 
 workmen and light-keepers, that dreadful ftorm began 
 which raged moll vic^lently on the 26th of November 
 170;;, in the night; and of all the accounts of the kind 
 which hiftory furnifties us with, we have none that has. 
 exceeded this in Great Britain, or was more injurious 
 or extenfive in its devaftation. The next morning, No- 
 vember 27th, when the violence of the ftorm was fo 
 much abated that it could be feen whether the hVht- 
 houfe had fuffercd by if, nothing appeared Handing,. 
 but, upon a nearer infpiflion, fome of the large irons 
 by wiiich the work was fixed upon the rock ; nor were 
 any of the people, or any of the materials of the build- 
 ing, ever found afterwards, fave only part of an iron 
 chain, which had got fo faft jambed into a chink of 
 the rock, that it could never afterwards be difengaged 
 till it was cut out in the year 1756." 
 
 Thus pcriftied Mr Winftanley, together with his 
 building: but fo great was the utility of that building 
 while it ftood, that the public could not tail to be de- 
 firous of havmg another in its place. Acccidingly, in 
 1706, an aft of pailiameut of the 4th of Qutcn Anne 
 was patfed, for the better enabling the matlir, &c. of 
 the Trinity-houfe of Deptford-ftrond to rebuild the 
 fame. By this aft, the duties payable by thipping paf- 
 fmg the light-houfe were vefted in the corporation of 
 the Trinity-houfe, who were empowered to grant a 
 leafe to fuch undertaker or undertakers as they tliould 
 approve. In confequeiice, they agreed with a Captain 
 Lovel or Lovel for a term of 99 years, commencing 
 from the day on which a light fliould be exhibited, and 
 continuing fo leng as that exhibition fliould laft during 
 
 the
 
 E D Y 
 
 [ 55 
 
 ■Edjftore. ihe faiJ term. On this foundation Captain Lovet en- 
 — gaged Mr Julni Rudyerd to be his engineer or arclii- 
 tecl and fuiveyor. 
 
 It does not appear tliat Mr Rudyerd was bred to 
 any mechanical bulinefs or fclentilic profedion, being at 
 tliat time a lilk mercer on Ludgate-hill; nor is it known 
 that, in any other itiUancc, he had diftlnguifiied himlclf 
 by any mechanical pcrfoimance before or after. His 
 want of perfonal experience, however, was in a degree 
 alfiited by Mr Smith and Mr Norcutt, both (hipwrights 
 in the Jving's yard at Woolwich. 
 
 It is not, as Mr Smeaton obferves, very inaterial in 
 what way this gentleman became qiiahfied for the exe- 
 cution of his work ; it is fufficient that he direfted tiie 
 performance in a mafterly manner, and fo as perteftly 
 to anfwer the end for which it was intended. He faw 
 the errors in the former building, and avoided them ; 
 -inllead of a polygon he chofe a circle for the outline of 
 his building, and carried up the elevation in that form. 
 His principal aim appears to have been ufe and Jimpli- 
 cify ; and indeed, in a building fo fituated, the former 
 .fould hardly be acquired in its full extent without the 
 latter. He feems to have adopted ideas the very re- 
 verie of his pfedeceffor; for all the unwieldy ornaments 
 ■nt top, the open gallery, the projecting cranes, and o- 
 •ther contrivances, more for ornament and plcaiure than 
 life, Mr Rudyerd laid totally afide. He faw, that how 
 beautiful foever ornaments might be in themfelves, yet 
 when they are improperly applied and out of place, by 
 r\ffecling to (hew a tatle, they betray ignorance of its 
 firll principle, j;<^mf«/; for whatever deviates from pro. 
 priety is erroneous, and at bcil infipid. 
 
 "it is impoflible for us to give an accurate account of 
 the conllrudion of Mr Rudyerd's light-houfe. We 
 can only fay, in general terms, that it was altogether 
 built of wood i for the courfes of moorftone, which Mr 
 Rudyerd, adverting to the maxim, that 'weight is bell 
 refifted by weight, introduced into the fulid part of his 
 building, mud be confidered as being of the nature of 
 ballaft i the weight of thefe amounted to above 270 
 tons. The main column of the building coniilled of 
 ore fnnple figMre, being an elegant fruftum of a cone, 
 unbroken by any projefting ornament, or any thing on 
 •which the violence of the llorms could lay hold; mea- 
 furino-, exclufively of its floping foundation, 22 teet and 
 riwht inches on its largeft circular bafe ; 61 feet high 
 above that circular bafe; and 14 feet and three inches in 
 diameter at the top : fo that the circular bafe was fome- 
 what greater than one-third of the total height, and 
 the diameter at the top was lefs than two-thirds of the 
 bafe at the greateft circle. On the flat roof of this 
 main column, as a platform, Mr Rudyerd fixed his lan- 
 tern, which was an odagon of ten feet and fix inches 
 diameter externally The mean height of the window- 
 frames of the lantern above the balcony floor was near- 
 ly nine feet ; fo that the elevation of the centre of the 
 light above the higheft fide of the bafe was 70 feet ; 
 that is, lower than the centre of Mr Winftanley's fe. 
 cond lantern by feven feet, but higher than that of his 
 firft by 24 feet. The width of Mr Rudyerd's lantern 
 was, however, nearly the fame as that of Mr Winftanley's 
 fecond : but inftead of the towering ornaments of iron- 
 work, and a vane that rofe above the top of the cupo- 
 la no lefs than 21 feet, Mr Rudyerd judicioufly con- 
 tented himfelf with finifliing his building with a round 
 ball of two feet and three inches diameter, which termi- 
 
 2 ] E D Y 
 
 nated at three feet above the top of his Cupola. The E'!y(lan«,i 
 
 whole height of Mr Rudyerd's liglit-houle, from the ^"""v"""' 
 
 lowed fide to the top of the ball, was 92 feet, on a bafe 
 
 of 2^ feet and four inches, taken at a nicJium between 
 
 the highed and lowed part of the rock that it covered. 
 
 The whole building wa^ completed in the year 1709, 
 
 three years from its conunencemcnt. 
 
 This great work, after having braved the eknients 
 for forty-fix years, was burnt to the ground in 175^. 
 On liic :d of December of that year, when the I'ght- 
 keeper, then on the watch, went, about two o'clock in 
 the morning, into the lantern, to fnuff the candles ac- 
 cording to cudom, he fiKind it in a fmoke; and in fpite 
 of all that he and his companions could do, the whole 
 edifice was on fire in the compafc of little more than 
 eight hours, and in a few days was burnt to its founda- 
 tion. The three light-men were with much difficulty 
 got on rtiore, when one of them immediately ran off, 
 and has never fince been heard of. Another, who had 
 been dreadfully burned by melted lead, of which, ac- 
 cording to his own account, he had I wallowed a quan- 
 tity, lingered in agony for twelve days, and then expi- 
 red. His ftomach being opened, there was found in it 
 a folid piece of lead of a fiat oval form, which weighed 
 feven ounces and five drachms ; and thus was verified 
 an afftrtion which, to the furgeort and others who at- 
 tended him, appeared altogether incredible, iiiz. that 
 any human being could live alter receiving melted lead 
 into the domach. 
 
 On the deftruftion of Mr Rudyerd's light-houfe, Mr 
 Smeaton (fee Smeaton in this Supplement) was re» 
 commended by Lord Macclesfield, then prefident of the 
 Royal Society, as the fitted perfon in England to burld 
 another. It was with fome difSculty that he was able 
 to perfuade the proprietors that a done building, pro- 
 pel ly condrudted, would in all refpe£ls be preferable to 
 one of wood ; but having at lad convinced them, he turn- 
 ed his thoughts to the lliape which was mod fuitable to 
 a building fo critically fituated. Refietting on the drnc- 
 ture of the former buildings, it ieemed a material im- 
 provement to procure, if poffible, an enlargement ol the 
 bafe, without incrcafing the fize of the luaiji, or that 
 part of the building which is between the top of the 
 rock and the top of the foK"d work. Hence he-thought 
 a greater degree of ftrength and iliffnefs would be gain- 
 cd, accompanied with lels refidance to the afting 
 power. On this occafion, the natural figure of the 
 waid or bole of a large fpreading oak occurred to Mr 
 Smeaton. 
 
 " Let us (fays he) conficler its particular figure. — 
 Connefted with its roots, which lie hid below ground, 
 it rifes from the furtace with a large ivvelling bafe, 
 which at the height of ore diameter is generally redu- 
 ced by an elegant curve, concave to the eye, to a dia- 
 meter lefs by at lead one third, and fometimes to half 
 its original bafe. From thence, its taper diminifliing 
 more (lowly, its fides by degrees come into a perpcndi- 
 cular, and for fome height form a cylinder. Atter 
 that, a preparation of more circumference becomes ne- 
 cefTary, for the tlrong infertion and edablilliment of the 
 principal boughs, which produces a fwelllng of its dia- 
 meter.— -Now we can hardly doubt but that every lec- 
 tion of the tree is nearly of an equal ftrength in pro- 
 portion to what it has to refift ; and were we to lop off 
 its principal boughs, and expofe it in that date to a ra- 
 pid current of water, we Ihould find it as capable ot 
 
 refifting
 
 E D Y [ 553 1 E D Y 
 
 dyrtone veAfting the aftion of the heavier fluid, when divefted was ovevfct alio'-rethcv, and that it had torn up a pnr- F.!yftii!t. 
 
 ""V"— ' of the greater part of its clothing, as it was that of tion of the rock itfelf, as far as the irons had been fait- '~~'^'™~' 
 
 the hVhter, when all its fjiieadinj; ornaments were ex- ened in it. With regard to the (lips, which were faid 
 
 pofed to the fury of the wind: and hence we may derive tohave been cut in tlie rock by Mr Rudyerd, the tra- 
 
 an idea of what the proper Ihape of a column of the ces of only-iwe were remaining ; thefe were faintly cut, 
 
 greateft ftahility ought to be, to refift the action of ex- and without much regularity. It was-next tried in 
 
 ternal violence, when the quantity of mailer is given what degree the rock was workable ; and Mr Smeaton 
 
 of which it is to be compofed." 
 
 The next thing to be conlidercd was, how the blocks 
 of Hone could be bonded to the rock, and to one ano- 
 ther, in fo firm a manner as that not only the whole 
 together, but every iidividual piece, when connefted 
 with what preceded, llioiild be proof agaiuft the greateil 
 \ioler.ce of the fea. For tiiis purpofe, cramping was 
 the fiiil idea, but was rejedled on account of the great 
 quantity of iron which was ncceffary, and from the 
 trouble and lofs of time which would attend that ope- 
 ration. In its place was lubilituted the metliod ot 
 
 had the fatisfaftion of linding every thing fucceed to 
 his wilhes. 
 
 Having thus determined that there was no impracti- 
 cability in fixing a (lone building, it bee ime of the 
 greatell importance to fccure a more fafe and certain 
 landing on the rock ; as it would frequently happen, 
 while tlie veffels were Iving i tf the rock, waiting for a 
 favourable time to enter th; gut, that tides inight 
 change, ground I'wells come on, winds Ihift, and (lonns 
 arife, which would of courfe make it defirable to re- 
 turn to Plymouth, if poflible, though the purpofe 
 
 dovetailing. From fome fpecimens wliich Mr Smeaton of the voyage was unperformed. In addition to this, 
 had feen in Bclidor's dclcription ot the Hone floor of when veflels had got with fome facility into the gut, 
 the great fluice at Cheiburgh, (where the tails of the they frequently could not get out again without ex- 
 upright headers are cut into dovetails for their infertion treme danger: for as the larger fort liad not room to 
 into the mafs of rough mafimry below,) he was led to turn in it, they were in reality obh'ired to go out ftern 
 think, that if the blocks themfelves were, both infide forward ; the Sugar-loaf roek being fo critically placed, 
 and outfide, formed into large dovetails, they inight be with (liallow water on both fides of it, that it prohibits 
 managed fo as to lock one another together, being pri- a thorough paifage. It was true, indeed, thdt by the 
 marily engrafted into the rock ; and in the round or Ihill and expertnefs of thnl'e feamen who had frecpiently 
 entire courfes aliove the top of the rock, they might all attended the fervice of the Edvftone. n.it only row boats, 
 proceed from, and be locked to, one large centre ftone. but the attendant veflels, after having deliveied their 
 Thefe particulars being digelled in his own mind, he cargoes, had been carried quite through, at the top of 
 explained his defign by the help of drawings ; with an high tide, with a fair wind and fmooth water : but 
 which, after mature deliberation, the proprietors were this was not an experiment to be commonly repeated, 
 perteftly fatisfied ; and declared, that the fcheme was The two voyages which Mr Smeaton had made were 
 not only in itfelf prafticable, but, as appeared to them, in a fmall failing veffel of about ten or twelve tons bur- 
 the only ineans of doing the bufinefs effeftually. den, which was built for the fervice, and called the 
 During this time Mr Smeaton had never vifited the Edyftone Boat. It occurred to him, that while the 
 rock on which he was to be employed : he therefore re- light houfe was Handing, if the boat had been (laved on 
 folved to go to Plymouth early in the fpring of 17^6, the rocks while lying in the gut, there was a poflibility 
 that he might lofe no opportunity of vieiving it. At of the men being faved by getting into the houfe, as 
 Plymouth he met Mr Jofias Jeffop, to vs'hom he was the light-keepers would have been ready to throw out 
 referred for information and affiftance, and who after- a rope to their aillllance : but that if any accident of 
 
 wards proved of great fervice : he was not only an ap- 
 proved workman in his branch as a iliipwright, but a 
 competent draughtfman and an excellent modeller ; ' in 
 which lill (fays the author) he was accurate to a great 
 degree : he therefore appeared to be a very fit perfon 
 to overlook the exaft execution of a defign given.' 
 Mr Jeffop, like others, expreflTed his doubts that a fl;one 
 
 the kind were to happen now that the houfe was down, 
 and no proteftion nor flielter to be had, there was little 
 chance of their eleape ; — and thefe confiderations being 
 likely to caft a damp on every exertion to land, he de- 
 termined to go out no more without anotlier failing 
 boat to attend. 
 
 The weather being unfavourable for vifiting the rock. 
 
 building could ftand on the Edyftone : but they were all exertions were ufed to forward the work on fhore ; 
 
 removed by the propofed mode of its contlrudlion. — aid, firil, a work-yard was chofen in a field adjacent to 
 
 As Mr Smeaton was impatient to go to the rock, he Mill Bay, about a mile weft from Plymouth. The 
 
 fcized the firft opportunity that feemed to promife any next objeft was to procure inoor ftone, or granite ; and 
 
 chance of landing on it. On the 2d of April he got with this view the author vifited Hingftone Downs, 
 
 within a ftone's throw of it, but could not land: on and obferved the manner of working the ftone, which 
 
 the 5th he was more fortunate ; he now landed, and is curious. He next went to Lanlivery, near Fowey 
 
 ftaid on the rock for two hours and a half. This time harbour, from which place the ftone-work for the late 
 
 was employed in taking a general view of the whole, light-houfe had been furriifhed. 
 
 No remains of the houfe could be perceived either on During this time he had made five voyages to the 
 
 the rock, or about it, except the greateft part of the rock with little fuccefs : the event of thelaft had ftrong- 
 
 irou branches that had been fixed by Mr Rudyerd ; ly pointed out, that the much greater tonnage of the 
 
 and fome of the moorftones were difeerned lying in the ftone which muft be neceflary to be carried out and 
 
 bottom of the gut. Such traces were alfo obferved fixed, in cafe of a ftone building, than was requitite in 
 
 of the fituation of the irons fixed by Mr Winftanley, the compofitions of his predeceftors, would make the 
 
 as to render it no very difficult taflc to make out his uncertainty and delay which they had defcribed as be- 
 
 plan, and the pofition of the edifice ; whence it ap- ing attendant on their voyages, in order to fix their 
 
 peared very probable, that Mr Winftanley's building work, bear far heavier on the fcheme ; and would thus 
 
 SupPL. Vol. I. Part II. 4 A occafion
 
 E D Y 
 
 [ 554- ] 
 
 E D Y 
 
 Edyftone. occafion the whole time of the performance to be 
 f lengthened. It appeared, therefore, that had a veflcl been 
 fixed within a quarter of a mile, or fume fuch competent 
 diilance from the rocks, and which fhould be capable 
 of lodging the workmen, all their tools and loofc ma- 
 terials, the feveral pieces of wrought Hone only except- 
 ed, that then the workmen mi!;;ht, by means of fmall 
 jowbcatsor yawls, have ctfefted alanding both of them- 
 fclves and of their materials, and have been at work on 
 the rock during tlie greateft part of thofc days wljich 
 otherwife, as voyagers, they would have loll in fruitlefs 
 endeavours to get to the place of aftion. Agreeably 
 to this opinion, it was propofed to build a ftroag and 
 very well found floop of about fifty tons, with iron 
 chains for mooring her on the rocky ground near the 
 Edyllone. A veffel was in (aft afterward moored in 
 this fituation : but it was one not built for the fervice, 
 but originally intended to have been ftationed as a 
 teiiiporary floating light during the rebuilding of the 
 light-houfe. 
 
 Mr Smeaton now made a fixth voyage to the rock, 
 on which he employed himfelf for nineteen hours in ta- 
 king fuch dimenfions as would enable him to make an 
 accurate model of its furface. He likcwife attempted 
 a feventh voyage : but being unable to reach the Edy- 
 ftone, he bore away for Falmouth, in order to examine 
 the moor (lone works at Conllantine in that neighbour- 
 hood. From the difficulties which occurred here, as 
 v/ell as at other places, he was convinced that a fuffi- 
 cient quantity of moor-flone could not be readily and 
 expeditioufly procured, in order to complete the whole 
 building ; and that he muil therefore confine the moor- 
 ftone to the outfide, as being more durable, and con- 
 tent himfelf with the ufe of Portland, or fomc other 
 free-working (lone, for the infide work. In confe- 
 quence, after making three more voyages to the rock, 
 and completing all the obfervations which he was de- 
 firous of taking there, he vifited the iile of Portland in 
 his return to London, and made the necelfary agreements 
 for carrying on his work. 
 
 On his arrival in London, Mr Smeaton again met 
 
 the proprietors, from whom he experienced the greateft 
 
 liberality a\id confidence : they declared, that as he was 
 
 \ now apprized of what was to be done, they left both 
 
 the time and the means of its accomplhhment to him. 
 
 » On this occafion (he obferves), I found myfelf to- 
 tally unfettered ; and perhaps no refolution of the pro- 
 prietors ever more conduced to the ultimate fuccefs of 
 the work than this, which fet me fo much at liberty. 
 Had they been of the fame temper and difpofition of 
 by far the greatell part of thofe who have employed 
 me, both before and fince, their language would have 
 been, Get on, Get on, for God's fake get on ! the 
 public is in expeftation ; get us fomething fpeedily to 
 fliew, by which we may gain credit with the public ! — 
 This, however, was not their tone, which I looked upon 
 as a happy earned from the proprietors in the outfet.' 
 
 During his (lay in London, he refolved, as an abfo- 
 lutely necelfary preliminary (lep, to form models of the 
 rock, both in its prefent (late and as cut to the intend- 
 ed (hape for receiving the building. Conncfted with 
 the laft was a model of the building itfelf, (hewing di- 
 ftinftly how the work was to be adapted to each (epa- 
 rate (lep in the afcent of the rock, and particularly ex- 
 hibiting the condruftion of the firft entire courfe after 
 riling to the level of the upper furface of the rock : to 
 
 this a folid being fitted, the model (hewed the external Edyftone 
 form of the whole building, including the lantern ; """V""- 
 while, by a feclion on paper, the whole infide work was 
 reprcfented. Thcfe models, as well, indeed, as moll 
 of the material parts of the bufinefs, were the entire 
 work of Mr Smeaton's own hands. After exhibiting 
 thefe to the Lords of the Admiralty, who exprelTed 
 their warmed approbation, he returned to Plymouth on 
 the 2^d of July 1^56. 
 
 On his arrival at Plymouth, he found that Mr JelTop 
 had completely fitted up, for prefent fervice, the floop, 
 which had before been ufed as an attendant ; as well as 
 the Edyllone boat, and a large yawl, with fails and 
 oars. Another feaman was now taken into the fervice, 
 which made the number of the crew fix. The Nep- 
 tune Bufs, which had been built for the purpofe of ex- 
 hibiting a temporary light, but which was afterward 
 moored near to the rock, was arrived : but as her defti- 
 nation was not known, all orders for mooring-chains 
 were fufpended, and Mr Smeaton was obliged to con- 
 tent himfelf with preparing cables in the bell manner 
 that he could for mooring the floop in that fituation. 
 As the weather was unfavourable, he had but one op- 
 portunity of vifiting the rock ; he therefore applied vi- 
 goroufly to prepare every thing on (hore. The firft 
 bufinefs was to edablifh the working companies, which 
 were to confid of two complete fets of hands, to relieve 
 each other by turns ; fo that, whenever winds and tides 
 would permit, the work might be purfued by day and 
 night. In his diftribution and management of thefe 
 people he appears to have ailed with great judgment. 
 He made choice of, and agreed with, Mr Thomas 
 Richardfon, a mafter mafon of Plymouth, to aft as 
 foreman of one of the companies ; and alfo with Wil- 
 liam Hill, who had been fome time foreman to another 
 mafter mafon of the fame place, to aft as the other 
 foreman. He likewife entered three mafons, and nine 
 tinners (Coi nifh miners), as a company, to go out with 
 Mr Richardfon to take the firft turn, or week, com- 
 mencing from Saturday the 31ft of July. Mr JelTop 
 was appointed general affiftant. The wages of the 
 foremen, while at fca, were to be 5 s. per day certain ; 
 and for every hour fpent on the rock, the farther pre- 
 mium of I s. — but when employed in the work-yard or 
 otherwife on fhore, their wages were to be 3 s. 6 d. per 
 day. The wages of the mafons were to be 2 s. 6 d. per 
 day certain at fea, with a premium of 9 d. per hour ; 
 and the tinners were to have 2 s. per day certain at fea, 
 and 8 d. per hour. In the work-yard, or at (hore, the 
 mafons were to have 20 d. and the tinners i8d. per day, 
 and to be paid for over-time when required to work ; 
 — and that the feameii might not want inducement to 
 do their utmoft in landing the workmen at the Edy- 
 ftone as early as poffible at every opportunity, and in 
 fupplying them with what was necelfary for keeping 
 them at work, over and above their weekly wages, 
 which were fettled at 8 s. per week, they were all to 
 receive a premium for every landing on the rock ; the 
 madcr feamen having 2S. 6 d. and the ordinary men 2s. 
 to make their advantage equivalent to that of the other 
 workmen, in whatever fervice the feamen, who were 
 condantly on duty, were employed. Mr Jeffop, as ge- 
 neral alfiftant, was to have 10s. 6d. per day at fea, and 
 5 s. per day on land ; and every one was to fupply him- 
 felf with viftuals. — Mr Smeaton likewife agreed for 
 half an acre of ground on the weft fide of Mill-bay for 
 
 a
 
 E D Y [ 555 ] E D Y 
 
 Eclyllone. a work-yard, asbefore mentioned, which he marked out, employed in weighing the Biifa's moorings. To pre- ,^'^^f''"'''-, 
 — V ' and ordered to be fenced with boards. At this time vent the nccefTuy of this, however, it was an objec\ of 
 arrived Mr John Harrifon, who was to ad as clerk to the confideration, whether tliey could not difpenfe with 
 Edyllonc works, with whom a plan was digelled for that operation, and thereby have a little more time for 
 keepin"- the accounts and correfpondence ; and for the work on the rock. Mr Smeaton's contrivance for this 
 ditlincl noting of fo great a variety of articles, it was purpofc was admirable ; but it v.'as rendered vain by- 
 found expedient to open fourteen different books. the bad failing of the bufs. After overcoming many 
 
 Matters being thus fettled on fliore, and the weather difficulties, the bufs with Mr Smeaton on board was 
 having become more promifing, Mr Richardfon and his driven at a great rate towards the hay of Bifcay, in dan- 
 company embarked in the Hoop, with her ground ger every hour of being fwallowed up by the waves or 
 tackle on board, attended by the author and Mr jefTop, dalhed in pieces on the rocks of SciUy. At laft, on Friday 
 and having the yawl alfo properly manned. Having morning the 26th of November, they reached Ply- 
 landed on the rock, Mr Smeaton proceeded to fix the mouth Sound, and relinquiftied all thoughts of return, 
 centre, and to lay down the lines of the intended work ing to their work on the rock that feafon. 
 on its furface ; and being followed by Mr Richardfon, The winter therefore of 1756, and the following 
 he, with (harp picks, left indelible traces of thofe lines, fpring, were employed in preparing materials for the 
 fo as that the workmen might proceed on them when outwork : the mafonry particularly required great at- 
 ever they fhould be able to land. The roughnefs of tention. It was a dcfirable objeft to ufe large and 
 the fea, however, foon rendered it advifable to return heavy pieces of ftone in the building; yet their fize 
 to the Hoop ; and from the fame caufe it was thought muft neceffarily be limited by the practicability of land- 
 unfafe to attempt to moor her that evening. On the ing them with fafety. Now fniall veflcls only could 
 next day, the wind continued to blow very frefh ; but deliver their cargoes alongfide of this hazardous rock ; 
 on the following they were able to moor the floop : and thefe could not deliver very large ftones, becaufe 
 and every one being anxious to make a beginning, the the fudden rifmg and falling of the vefTels in the gut 
 whole company landed on the rock, and immediately amounted frequently to the difference of three or four 
 began the work, which was purfued for about four feet, even in moderate weather ; fo that in cafe after a 
 hours, when they were driven off by the fea. On the ftone was raifed from the floor of the vtfTcl, lier gun- 
 following day, all hands landed before fun-rife, and wale (hould take a fwing, fo as to hitch under the 
 worked,"during that tide, for fix hours ; and in the af- ftone, one of a very large magiutude mull, on llie vef- 
 ternoon's tide they again landed, and continued the fel's riling, infallibly fink her. From this confideration, 
 work, by the help of links, till ten o'clock at night, it was determined that fuch ftones fliould be ufed as 
 They purfued this courfe for fome time with very little did not much exceed a ton weight ; though occafion- 
 interruption, working, at an average, for about five ally particular pieces might amount to two tons. That 
 hours in each tide. they might attain a certainty in putting the work to- 
 
 The weather had now been fair from Auguft 27th gether on the rock, the ftones of each courfe were tried 
 to the 14th of September; and in this fpace they had together in their real fituation with refptd to each 
 worked for 177 hours on the rock. During this in- other; and they were fo exaftly inarked, that every 
 terval, alfo, Mr Jeftbp had prevented a weft Indlaman ftone, after the courfe was taken afunder, could be re- 
 homeward bound, and a man of war's tender, from dri- placed in the identical pofition in which it lay on the 
 ving on the rocks, to which they were approaching, platform, within the fortieth part of an inch :— nor was 
 though they themfelves were not aware of it. On the this judged fufficient ; for every courfe was not only 
 l6th, the work on the rock was in the following fitua- tried fingly together on the platform and marked, but 
 tlon : The loweft new ftep (the moft difficult to work, the courfe above it was put on it, and marked in the 
 becaufe the loweft), with its dovetails, was quite com- fame way ; fo that every two contiguous courfes might 
 pleted. — The fecond ftep was rough bedded, and all its fit each other on the outfide, and prevent an irregulari- 
 dovetails fcapelled out.— The third ftep (being the ty in the outline. This degree of accuracy might feeni 
 loweft in Mr Rudyerd's work) was fmooth bedded, and fuperfluous : but as the nature of the building required 
 all the dovetails roughed out. — The fourth was in the the workmen to be in a condition to refill a ftorm at 
 like ftate.— The fifth was rough bedded, and its dove- every ftep, it became neceffary to i\x. the centre ftone 
 tails were fcapelled out ; and the fixth was fmooth bed- firft, as being leaf): expofed to the ftroke of the fea ; 
 dtd, and all the dovetails roughed out. — Laftly, the top and in order to have fure means of attaching all the 
 of the rock, the greateft part of the bulk whereof had reft to this, and to one another, it was indifpenfable 
 been previouOy taken down as low as it could be done that the whole of tlie two courfes fliould be tried to- 
 with propriety, was now to be reduced to a level with gether ; in order that, if any defe<St appeared at the 
 the upper furface of the fixth ftep ; the top of that ftep outfide, by an accumulation of errors from the centre, 
 being neccftarily to form a part of the bed for the it might be reftitied on the platform, 
 fevcnth or firft regular courfe : fo that what now re- Another circumftance, to which Mr Smeaton was 
 mained, was to bring the top of the rock to a regular particularly attentive, and concerning which his remarks 
 floor by picks ; and from what now appeared (as all are very valuable, was to afcertain the moft proper com- 
 the upper parts that had been damaged by the fire were pofition for water cements. In making mortar for ^ 
 cut off) the new building was likely to reft on a bafis buildings expofed to water, larr.is had been moft 
 even more folid than the former llghthoufes had done. efteemed : but ftiU there were objections to its ufe. Mr 
 
 The equinoftial winds that were now reigning, af- Smeaton was therefore induced to try the terra pu'z- 
 
 forded little profpeft of doing much more work on the zolana, found in Italy, as a fubftitute for larras. For. 
 
 rock for this feafon : for though a more moderate in- tnnately there was a quantity of it in the hands of a mer. 
 
 terval of weather might be expefted, yet that muft be chant at Plymouth, which had been imported as a ven- 
 
 4 A a tore
 
 E D Y [5 
 
 Eilyftone. tiire from Civita Vecchia, when Wcftniiiiftcr-brldge was 
 • building ; and wln'ch lie exptfttd to have lolJ for that 
 
 work to a good advantage, but failed in his fpeculation : 
 for having found that tarras anfwered their purpofe, 
 neither cominiffioners, engineers, nor contraftors, would 
 trouble thcmfelves to make a trial of the other material. 
 'J'his was found in every relpeft equal to tcirriu, as tar 
 as concerned the hardening of water-mortar, it not pre- 
 ferable to it ; and if made into a mortar witii lime pro- 
 duced irom a Hone found at Aberthaw, on the coall of 
 Glamorgaiifliire, it exceeded, in haninefs, any of the 
 compofitions commonly ufed in dry work ; and in wet 
 and dry, or wholly wet, was far fuperior to any which 
 Mr Smeaton had feen, infomuch that he did not doubt 
 its making a cement that would equal the heil merchant- 
 able Portland (lone in folidity and durability. 
 
 Thefe preliminary arrangements being lettled, they 
 proceeded, on the 3d of June 1757, to carr> out the 
 Neptune bufs, and to begin the work. After getting 
 lip the moorings (a work of no fmall difficulty and foine 
 danger), and after fixing the fender-piles, the ihears, 
 windlafs, &c. the firll ilone was landed, got to its place, 
 and tixed, on Sunday the i 2th of June ; and on the 
 next day the firll courfe was coinpleted. On the 14th, 
 the fecond courfe was begun : but, in confequtnce of a 
 frefh gale, the workmen were obliged to quit tlie rock, 
 after fccuring every thing as well as poffible. Such was 
 the violence of the gale, that it was li.iprafticable for 
 the boats to get out of the gut, otherwife than by paf- 
 fing the Sugar-loaf rock, in which they providentially 
 iucceeded. On the 18th, they were again as fuddenly 
 driven from their work, and feveral pieces of ftone were 
 wafhed away by the violence of the fea. In the night 
 of the 6th of July, the watch on the deck of the bufs 
 efpied a fail on the rocks, and one of the yawls was fent 
 to her relief, which brought back the whole crew, feve- 
 ral of whom were in their fhirts, and in great diilrefs. 
 It was a fnow of about 130 tons burthen, which was 
 returning in ballail from Dartmouth ; but not know- 
 ing exadly. where they were, they had miftaken the 
 rocks for to many fiihing-boats, till it was too late to 
 clear them ; ar.d on the veffel's Ilriking, flie filled fo 
 quickly, that the boat floated on deck before they could 
 get into it. 
 
 During this tim.e the building went on, though its 
 progrefs was retarded by various interruptions ar.d ac- 
 cidents ; till, at the latter end of Augull, when the 
 feventh courfe was nearly finifhed, a violent ilorm arofe, 
 which carried away the Ihears and triangles, together 
 with two of the largetl Hones which had been left 
 chained on the rock 1 yet notwithllanding thefe and 
 various other difBculties, the ninth courfe was comple- 
 ted by the end of September. 
 
 " Being now arrived at the eve of Oftober (fays Mr 
 Smeaton), I maturely confidered our fituation ; and 
 finding that we had been 18 days in completing the 
 lall courfe, whereas the former one was begun and fi- 
 niflied in five, though the weather, both on (hore and 
 above head, had remained to all appearance much the 
 fame ; I from thence concluded it to be very probable, 
 we might not get another courfe completed in the com- 
 pafs of the month of Oftober : So that when I refleft- 
 ed on the many difafters that we had fuffered lall year 
 by continuing out to the month of November, and how 
 little work we in reality did after this time, it appear- 
 
 56 ] 
 
 E D Y 
 
 ed to me very problematical whether we might be able, E<"yftor< 
 with every pofilble exeitiou, to get another courfe fi- '~~*~" 
 nithed this ieafon ; and coiifidering how very ineligible 
 it was to have a courfe lie open during the winter in 
 this llage of the work, and that we bad now got three 
 complete courfes elLiiifhed above the top of the rock, 
 the fum of wholi height was four feet iix inches ; and 
 that we could not leave the work in a more defenfibie 
 ftate, whether as relative to the natural violence of the 
 fea, or the puflibility of external injuries— from thefe 
 conCderations, it appeared to me highly proper to put 
 a period to the outwork of the prelcni ieafon." 
 
 At the commencement ot the following year, 1758, 
 the weather proved very tempeftuous till Maich ; and 
 on vifiting the rock, they difcovered that the great buoy 
 on the moorings had been carried away ; nor were the 
 mooring chains, though fought with the greatell perle- 
 verance, recovered till the middle of May. In confe- 
 quence of this delay, and from other accidents, the 
 tenth courle ot the building was not completed till the 
 jth of July. From this time, the progrefs was with- 
 out any very material inteiruption ; fo that on the 26tli 
 of September the 25th courfe, being the firll of the 
 fuperllruflurc, was finifhed. The work was now fo far 
 advanced, that Mr Smeaton made a propolal to the 
 Trinity Board and to the proprietors, of exhibiting a 
 light during the enfuiug winter ; and for this purpofo 
 he continued his operations longer than he otherwife 
 would have done, in order to complete the firll room, 
 and make it habitable ; but foul weather coming on, 
 he was obliged to quit the rock, and returned to Ply- 
 mouth. A Ilorm enfued ; and, on the next morning, 
 looking out with his telefcope, he could difcern the 
 houfe with the tea breaking over it, bjt nothing of the 
 bufs. On the following day, the air being more clear, 
 he had a dillintl view of the building ; but the bufs 
 was really gone. This was a day of double regret, as 
 it likewile brought a negative on his propolal for exhi- 
 biting a light from the houfe during the winter. The 
 bufs had run into Dartmouth harbour; fhe was brought 
 home ; and the work on the reck being fecured agair.it 
 the winter, the operations ot the third fealon were 
 clofcd. 
 
 During the early part of 1759, Mr Smeaton was 
 employed in London in forming and making out the 
 necelTary dcfigns for the Iron rails of the balcony, the 
 call iron, the wrought iron, and the copper works for 
 the lantern, together with the plate glafs work. It was 
 not till the 22d of June that he arrived at Plymouth. 
 As the moorings had been again loil, new chains 
 were provided, and the buls was once more fixed in 
 her fituation. On the jlh of July he landed on the 
 rock, and found every thing perfectly found and firm, 
 without the leail perce])tible alteration, excepting thLt 
 the cement, ufed in the firil year, now in appearance 
 approached the hardnels of the moorflone ; and that 
 ufed in the lafl year had the full hardnefs of Portland ; 
 but on hauling up the ilones for the next circle from .^ 
 
 the flore-room, where they had been depofited, he had 
 the mortification to find only feven inllead of eight. 
 It was imagined that a body of falling water, making 
 its way through the open ribs of the centre, had waih- 
 ed this ftone out of the ftore-room door, though it 
 weighed between four and five hundred weight. 
 
 'I he progrefs of the work, however, was now fuch,. 
 
 that
 
 E D Y 
 
 [ 557 ] 
 
 E D Y 
 
 that a whole room, with its vaulted cover, was built 
 complete in feveii days. 
 
 On the 17th of Aiignit the main column was com- 
 pleted. 
 
 On the 27th Mr Richardfon and his company left 
 the Ed) Hone, and gave an account that they had lived 
 in it lince the 2^d, having found it much more warm 
 than the buis's hold and cabin. 
 
 They had now finilhed every thing belonging to the 
 mafonry. The work of the cupola was going on briflc- 
 )y in the yaul at Mill-hay, though it was retaidtd by 
 the fucccflivc ilhielics of the two principal copperfmiths. 
 However, by the exettions of Mr Sineaton, who was 
 himfclf ready to work at every bufineis, all matters 
 were put in fuch forwardnels, that by the 8th of Sep- 
 tember there was nothing to prevent the frame of the 
 lantern from being hxtd in its place but bad v% cat her. 
 It was not till the 1 i;th that the weatiier permitted the 
 boats to deliver their cargoes. The i6th was remark- 
 ably fine ; fo that by the evening the whole frame of 
 the lantern was fcrewed togetlici, and fixed in its place. 
 On tlie 17th, which was alfa exceedingly fine, the cu- 
 pola was brought out, and the (hears and tackle wtre 
 fet up for hoiiling it. 
 
 " This (fays Mr Smeaton) perhaps may be account- 
 ed one of the moft d'fKcuIt and hazardous operations of 
 the whole undertaking ; not fo much on account of 
 its weight, being only about 1 1 cwt. as on account of 
 the gicdt height to which it was to be hoilled clear of 
 the building, and fo as, if pcflil;le, to avoid fuch blows 
 as might brin'fe it. It was alfo required to be hoifted 
 a cor.fiderable height above the baliony floor ; which, 
 though the largeft bafe that we had for the (hears to 
 (land on, was yet but 14 feet within the rails, and there- 
 fore narrow in proportion to their height. About 
 noon the whole of our tackle was in readinefs ; and in 
 the afternoon the Wefton (boat) was brought into the 
 gni, and in lefs than half an hour her troublefonic car- 
 go was placed on the top of the lantern without the 
 leaft damage. During the whole of this operation it 
 pleafed God that not a breath of wind difcompofed the 
 furface of the water, and there was the leall fwcll about 
 the rocks I had obferved during the feafon. 
 
 " Tuefday, September 18th, in the morning, 1 had 
 the fatisfaiflion to perceive the Edyftcne boat, on board 
 of which I cxpciited the ball to be ; and which be- 
 ing double gilt, I had ordered the carriage of it to 
 be carefully attended to. The wind and tide were 
 both tmfavourable to the velTd's getting foon near us ; 
 therefore, beirg dcfirous to get the ball fcrewed on 
 before the (hears and tackle were taken down, one of 
 the yawls was difpatched to bring it away. This be- 
 ing done, and the ball fixed, the (hears and tackle were 
 taken down, which took up nearly as much time as was 
 employed in fctting them up ; that is, near 12 liours 
 each, in the whole, to do the work of an hour. — I muft 
 obferve, that by choice I fcrewed on the ball with mine 
 own hands, that in cafe any of the fcrews had not held 
 quite tight and firm, the circumftance might not have 
 been flipped over without my knowledge ; being well 
 aware, that even this part would at times come to a- 
 confiderable ftrefs of wind and fea, and which could' 
 not be replaced without fome difficulty in cafe any 
 thmg lliould fail. — It may not be amifs to intimate to 
 
 filled of four boards only, well nailed together, at fuch EdyOone. 
 dillaiiccs as to permit it to be lifted over the ball when » 
 
 done with. It relied on the cupola, encom.pafiing its 
 neck ; and Roger Cornthwaitc, one of the mafons, pla- 
 ced him(elf on the oppofite fide upon it, to balance me 
 while I moved round to fix tlic fcews." 
 
 Reipetting the difpofition of the internal part of the 
 edifice, Mr Smeaton fixed the beds in the uppermoft 
 rooin, and the fire- place, which conllitiited the kitchen, 
 in the room below it ; wlicreas, in the late houle, the 
 upper room was the kitchen, and tiie beds were placed 
 in ons of the rooms below : the confeCjiience ot which 
 was, that the beds and bedding were generally in a very 
 dam]) and difagieeable ftatc. The prefent dilpofition has 
 perfecUy anfwered-the end propo(ed, as nothing can be 
 more completely dry than the two habitable rooms. 
 
 On the ill of October, every tiling being finilhed,. 
 and the (handeliers hung, th.ere was nothing to hinder 
 a trial by lighting the ctuidlcs in the day-time. Ac- 
 cordingly 24 candles were put into their proper places, 
 and were continued burning (or three hours, during 
 which time it blew a hard gale ; and a fire being kept 
 at the iaine time in the kitchen, they both operated 
 without any interference ; not any degree of finoke ap- 
 pearing in the lantern nor in any of the rooms : and 
 by opening the vent-holes, which had been made in the 
 bottom of the lantern for occafional ule, it could be 
 kept quite cool ; whereas, in the late light-houlc, it 
 ufed to be fo hot, efpecially in the fummcr, as to give 
 much trouble by the running of the candles. 
 
 All being thus in readinefs, and a condudlor, in cafe 
 of lightning, being adapted to the building, notice was 
 given to the Trinity-houfe that the light would be ex- 
 hibited on the 16th of Oftober 1759- The feafon of 
 the year being now advanced to that which was always 
 very precarious, the Neptune bufs was unmoored, and 
 on the gth of Ofiober llie came to an anchor in Ply- 
 mouth harbour. — " And thus (fays Mr Snieaton), af- 
 ter innumerable difiiculties and dangers, was a happy 
 period put to this undertaking, without the lofs oi hie 
 or limb to any one concerned in it, or accident, by which 
 the work could be faid to be materially retaided." 
 
 With regard to fubfequent occurrences, it is truly 
 obfeived, that the bell account is, that alter a trial of 
 40 years, which have elapfed fince the linidiing of the 
 building, it ftill remains in its original good conilition. 
 A few particulars are however inttrcl'ing. On the icjth 
 of October Mr Snieaton, with Mr Jelfop, &c. vifited 
 the houfe, and, landing, found all well. Henry Ed- 
 wards, one of the light-keepers, gave ?n account that 
 they lighted the houle as they were diicdted, and found 
 the lights to burn lleadily, r.otwithllanding it blew very 
 hard ; that they had the greated feas on tlie days im- 
 mediately preceding the lighting ; and that then the 
 waves broke up fo high, that had they not been thrown 
 oif by the cove courfe, they would have endangered 
 breaking the glafs in the lantern ; that when the feas 
 broke the higheft, they had experienced a fcnfible mo- 
 tion ; but that, as it was barely perceptible, it had oc- 
 cafioned them neither fear nor furprife. 
 
 During his (lay at Plymouth, in the times of ftormy 
 weather, Mr Smeaton took feveral opportunities of 
 viewing the light-houfc with his telefcope from the 
 Hoa, and alfo from the garrifon ; both which places 
 
 thofe who may in future have to perform the fame ope- were fufficiently elevated to fee the bafe of the building, 
 ration, that the fcafibld on which this was done coo- and the whole of the rock at low water in clear wea- 
 ther. J
 
 E D Y 
 
 C 558 ] 
 
 E D Y 
 
 EJyftrr.e. tlier ; and thnugli he had many occafions of viewing tlon that nothirg but ii'ootl could refift the fea npoti Edyftor.* 
 """"""^ ' /- n , ■ , , , ■ , ., the Edy (lone rocks ; who laid, that though they allow- , II 
 
 ed it was built very ftrong, yet it fuch a ftornias had ^'"^^"'"« 
 dcftroyed Winftaiiley's light-houfe wa8 again to hap- 
 pen, they doubted not but it mull fhare the fame fate. 
 The year 1762 waa ufliercd in with ftormy weather, 
 and indeed produced a tenipeft of the firft magnitude ; 
 
 the unfmilhcd building when buried in the waves in a 
 ftorm at fouth weft, yet having never before had a 
 view of it under this circumflance in its finifhed ftate, 
 he was alloniihed to find that the account given by Mr 
 Winftanley did not appear to be at all exaggerated. 
 At intervals of a minute, and iometimes of two or three. 
 
 when a combination happened to produce one over- the rage of which was fo great, that one of thofe who 
 
 grown wave, it would ftrike the rock and the building had been ufed to predift its downfal was heard to fay, 
 
 ■conjointly, and fly up in a white column, enwrapping it If the Edyftone light-houfe is ftanding now, it wili 
 
 like a flieet, rifing at leaft to double the height of the ftand till the day of judgment. And, in reality, from 
 
 houfe, and totally intercepting it from the fight ; and this time, its exiftcnce has been fo entirely laid out of 
 
 this appearance being momentary, both as to its rifing mens minds, that whatever ftorms have happened fince, 
 
 and tailing, he was enabled to judge of the comparative no inquiry has ever been made concerning it." 
 
 lieight very nearly by the comparative fpaces, alternate- For the length of this detail we cannot bring our- 
 
 Iv occupied by the houfe and by the column of water felves to make any apology. If there be a few of our 
 
 in the field of the telelcope. readers to whom it may appear tedious, we are per- 
 
 The year J 759 concluded with fome very ftormy wea- fuaded that there are many more to whom it will be 
 
 ther; and in January i 760, Mr Jeftbp vifited the houfe, in a high degree interefling ; while fuch of them as arc 
 
 but could not land. He got a letter, however, from engineers will derive inftruflion even from this very 
 
 Heniy Edwards, acquainting him that there had been abridged hiftory of the Edyftone light-houfe. 
 
 fuch very bad weather that the fea frequently ran over EFFECTION, denotes the geometrical conftruftion 
 
 the houfe ; fo that for 12 days together they could not 
 open the door of the lantern nor any other. He faid, 
 " the houfe did ftiake as if a man had been up in a 
 ^reat tree. The old men were almoft frighted out of 
 their lives, wiihing they had never feen the place, and 
 curfing thofe that firft perfuaded them to go there. 
 The fear feized them in the back ; but rubbing them 
 with oil of turpentine gave them relief." He farther 
 
 of a propofition. The term is alio ufed in reference to 
 problems and praflices, which, when they arc deducible 
 from, or founded upon, fome general propofitions, are 
 called the geometrical effeSion of them. 
 
 ELASTICITY. In addition to the article in the 
 Encyclopedia, fee, in this Supplement, the view of Bos- 
 covich's theory of natural phiiofophy, n° 26. 
 
 ELECTIONS, or Choice, fignity the feveral dif- 
 
 mentioned, that on the 5th of December, at night, they ferent ways of taking any number of things propofed, 
 
 had a very great ftorm ; fo that the ladder, which was either feparately, or as combined in pairs, in threes, in 
 
 bfhed below the entry door, broke loofe, and was wallied fours, &c. ; not as to the order, hut only as to the 
 
 away. Alfo, on the 13th, there was fo violent a ftorm of number and variety of them. Thus, of the things a, b, 
 
 wind that he thought the houfe would overfet ; and at c, d, e, &c. the eleflions of 
 
 midnight the fea broke one pane of glafs in the lantern, one thing are (a,) 1 = 2' 1, 
 
 They had a very melancholy time of it, having alfo had 
 a great deal of thunder and lightning. — " The ftorms 
 (obferves Mr Smeaton) which the building has now 
 fuftained without material damage, convince us, and 
 every one, of the ftability of the ftone light-houfe, ex- 
 cept thofe (who are not a few) who had taken a no- 
 
 two things are [a, b, at,) 3 =r 2' — I, 
 three things are [a, b, c, ah, ac, be, abc,) 7 = 2' — i, 
 &c. ; and of any number n, all the elections are 2° — i ; 
 that is, one lefs than the power of 2 whofe exponent is 
 n, the number of fingle things to be chofen, cither fe- 
 parately or in combination. 
 
 ELECTRICITY. 
 
 ■f XrE cannot but be fomewhat furprifed that, among 
 ' '^ the many attempts which have been made by 
 the philofophers of Britain to explain the wonderful 
 phenomena which are clafled under this name, no author 
 of eminence, befides the Hon. Mr Cavendifh and Lord 
 Mahon, have availed themlclves of their fufceptibillty of 
 mathematical difcufiion ; and our wonder is the great- 
 er, bccaufeit was by a mathematical view of the fubjeft, 
 in the phenomena of attraction and repulfion, that the 
 celebrated philofopher Franklin was led to the only 
 knowledge of eleftricity that deferves the name of fci- 
 ence ; for we had fcarcely any leading fafts, by which 
 we could clafs the phenomena, till he publiftied his the- 
 ory oi pofitive and negative, or plus and minus, eleftrlcity. 
 This is founded entirely on the phenomena of attraftion 
 and repulfion. Thefe furnifh us with all the indications 
 of the pretence of the mighty agent, and the marks of 
 its kind, and the meafures of its force. Mechanical 
 force accompanies every other appearance j and this ac- 
 
 companiment is regulated in a determinate manner. 
 Many of the effefts of eledtricity are ftriflly mechanical, 
 producing local motion in the fame manner as magne- 
 tifm or gravitation produce it. One (hould have ex- 
 pefted that the countrymen of Newton, prompted by 
 his fuccefs and his fame, would take to this mode of ex- 
 amination, and would have endeavoured to deduce, from 
 the laws obferved in the aAion of this motive force, an 
 explanation of other wonderful phenomena, which are 
 infeparably connefted with thofe of attra&ion and re- 
 pulfion. 
 
 But this has not been the cafe, if we except the la- 
 bours of the two philofophers above mentioned, and a 
 few very obvious pofitions^ which muft occur to all the 
 inventors and improvers of eleftrometers, batteries, and 
 other things of meafurable nature. 
 
 This view has, however, been taken of the fubje6t 
 by a philofopher of unqueftioned merit, Mr .^pinus 
 of the Imperial Academy of Sy Peterfburgh. This 
 
 gentleman.
 
 ELECT 
 
 gentleman, ftruck with the reremblance of the eleftrici- 
 cal properties of the tourmalin to the properties of a 
 macjnet, which have always been confidered as the fiib- 
 jeft of mathematical difculRon, fortunately remarked a 
 wonderful fimilarity in the whole feries of eleftrical and 
 magiietical attraftiors and repulfions, and fet himfelf 
 ferioufly to the claflification of them. Having done 
 this with great fiiccefs, and having maturely refledled 
 on Dr Franklin's happy thought of plus and minus elec- 
 tricity, and his confequent theory of the Leyden phial, 
 he at laft hit on a mode of conceiving the whole fiibjeifl 
 of magnetifm and eleftricity, that bids fair for leading 
 us to a full explanation of all the phenomena ; in as far, 
 at lead, as it enables us to clafs them with precifion, 
 and to predift what will be the refult of any propofed 
 treatment. He candidly gives it the modeft name of 
 a hypothefis. 
 
 This was publiihed at St Peterfburg in 1759, under 
 the title of Theorla EltSritatis et Magnetifmi, and is un- 
 cueftlonably one of the mod ingenious and brilliant 
 performances of the eighteenth century. It is indeed 
 moft furprifrng that it is fo little known in this coun- 
 try. This, we imagine, has been chiefly owing to the 
 very flight and almoft unintelligible account which Dr 
 Prieftley has given of it in his hiftory of eleftricity ; a 
 work which profeffes to comprehend every thing that 
 has been done by the philofophers of Europe and Ame- 
 rica for the advancement of this part of natural Icience, 
 and which indeed contains a great deal of inftrudlive in- 
 formation, and, at the fame time, fo many loofe conjec- 
 tures and infignificant obfervations, that the reader (e- 
 fpecially if acquainted with the Doftor's charafter as 
 an unwearied bookmaker) reafonably believes that he 
 has let nothing (lip that was worthy of notice. We do 
 not pretend to account for the manner in which Dr 
 Prieftley has mentioned this work, fo much, and fo do- 
 fervedly celebrated on the continent. We cannot think 
 that he has read it fo as to comprehend it ; and imagine, 
 that feeing fo much algebraic notation in every page, 
 and being at that tln>e a novice in mathematical learn- 
 ing, he contented Iiimfelf with a few fcattered para- 
 graphs which were free of thofe embaraffments ; and 
 thus could only get a very imperfeft notion of the fyf- 
 tem. The Hon. Mr Cavendifh has done it more juf- 
 tice in the 6ifl volume of the Philofophical Tranfac- 
 tions, and confiders his own moft excellent dlfTertation 
 only as an extenfion and more accurate application of 
 jEpinus's theory. Tha' we have not an account of this 
 expofition of the Franklinian theory of eledtricity in our 
 language, is a material want in Briti(h literature ; and 
 we trull, therefore, that our readers will be highly plea- 
 fed with having the ingenious difcoveries of the great 
 American philofopher put into a form fo nearly ap- 
 proaching to a fyftem of demonftratlve fcience. 
 
 We propofe, therefore, in this place, to give fuch a 
 brief account of jEpinus's theory of eleftricity, as will 
 enable the reader to reduce to a very fimple and eafily 
 remembered law all the phenomena of eleftricity which 
 have any clofe dependence on the mechanical effefts of 
 this powerful agent of Nature ; referring for a demon- 
 flration of what is purely mathematical to Sir Ifaac 
 Newton's Principia, and the DilTertation by Mr Ca- 
 vendifh already mentioned, except in fuch important 
 articles as we think ourfelves able to prefent in a new, 
 and, we hope, a more familiar form. We do not mean. 
 
 R f C I T Y. 559 
 
 in this place, to give a fyftem of philofophical eleftri- 
 city, nor even to narrate and explain the more remark- 
 able phenomena. Of thefe we have already given a 
 vaft colleftion in the article Electric Try, £n<r^i:/. We 
 confine ourfelves to tiie phenomena which may be called 
 mechanical, producing meafurable motion as tlieir imme- 
 diate effeft i and thus giving us a piinciple for the ma- 
 thematical examination of the caiife of eieftrical plieno- 
 mena. We fhall confidtr the reader as acquainted with 
 the other phyfical effefts of eleftricity, and fhall fre- 
 quently refer to them for proofs. 
 
 Moreover, as our intention is merely to give a fynop- 
 tical view of this elaborate and copious performance of 
 Mr jEpinus, hoping that it will excite our countrymen 
 to a careful perufal of fo valuable a work, we fhall omit 
 moll of the algebraic inveftigations contained in it, and 
 prefent the conclufions in a more familiar, and not Icfs 
 convincing form. At the fame time we will infcrt the 
 valuable additions made by Mr Cavcndilh, and many- 
 important particulars not noticed by cither of thofe gen- 
 tlemen. 
 
 Hypothesis of jEpinus. 
 
 r 
 The phenomena of eleftricity are produced hy a fluid Hypotheffr. 
 of peculiar nature, and therefore called the electric 
 FLUID, having the following properties : 
 
 1. Its particles repel each other, with a force decrea- j. 
 fing as the diilances increafe. 
 
 2. Its particles attraft the particles of fome ingre- , 
 dient in all other bodies, with a force decreafing, accord- 
 ing to the fame law, with an increafe of diflance ; and 
 
 this attraftion is mutual. 
 
 ■f. The eleftric fluid isdifperfed in the pores of other ^ 
 bodies ; and moves, with various degrees of facility, 
 tlirough the pores of different kinds of matter. In 
 thofe bodies which we call non-elef}rics, fuch as water or 
 metals, it moves without any perceivable obflruftion ; 
 but in glafs, rofins, and all bodies called eleBrics, it 
 moves with very great difficulty, or is altogether im- 
 moveable. 
 
 4. The phenomena of eleftricity are of two kinds ; S^ 
 I. Such as arife from the aftual motion of the fluid 
 from a body containing mure into one containing lefs 
 of it. 2. Such as do not immediately arife from this 
 transference, but are inftanccs of its attraftion and re- 
 pullion. 
 
 Thefe things being fuppofed, certain confequenccs ne- 
 ceffarily refult from them, wlitch ought to be analogous 
 to the obferved phenomena of eleftricity, if this hypo- 
 thefis be complete, or fome farther modification of the 
 affumed properties is neceffary, in order to make the 
 analogy perfeft. 
 
 Suppofe the body A (fig. I.) to coiitaln a certain ft.. 
 quantity of fluid. Its particles adjoining to the fur P'af- 
 face, fi|^^ as P, are attrafted by the particles of com^^^^"' 
 
 mon mwter in the body, but repelled by the other par- 
 ticles of the fluid. The totality of the attraftive forces 
 afting on P may be equal to the totality of the repul- 
 five forces, or may be uiicqual. If thele two fums are 
 equal, P is in equilibrio, and has no tendency to change 
 its place. But there may be fuch a quantity of fluid 
 in the body, that the repulfions of the fluid exceed 
 the attraftions of the common matter. In this cafe, P 
 has a tendency to quit the body, or there is an expul- 
 ijvc force afting oa it, and. it will quit the body If it be 
 
 moveablca
 
 560 
 
 EEECTRICITY. 
 
 moveable. Becauf* tlie fame muil be admitted in rcfpeft 
 of every other particle of moveable flairl, it is plain that 
 there will be an efflux, till the attraAiiin of the com- 
 mon matter fcr the particles of fl;iid is equal to the rc- 
 pulfion o*" the remaining fluid. On the uther hand, if 
 tlie primitive vepiillioii of the fluid acting on tbe particle 
 P be lefb than the attractions of the common matter, 
 tl'.ere will be the fame, or at Icalt a fimilar, fuperiority 
 of attraction afting on the fluid refiding in On circum- 
 ambient bodies ; and tliore will be an in.lux from all 
 . hands, till ar ec 'lilibrium be reltored. 
 
 Natural Hence it follows, that there may always be affigned 
 
 quantity, to gi^y [jo^y fu^h a quantity of fluid that there fliall be 
 w ylocal' ^^ tendency either to efflnx or influx. But if the quan- 
 tity be incrcafed, and nothing prevent the motion, the 
 redundai/t fluid will flow out ; and if the pioper quan- 
 tity be diminiflied, there will be an influx of the fur- 
 rounding fluid, if not prevented by fome external force. 
 This may be called the tody's natural «itiANriTy ; 
 becaufe the body, when left to itfclf, will always be re- 
 duced to this ftate. 
 
 8. If tv^'o bodies A and B, contain each its natural 
 quantity, they will not exert any fenfible aftion on each 
 other ; for, becaufe the fluid contained in B is united 
 by attraflion to the common matter, and is alfo repel- 
 led by the fluid in A, it necefiarily follows that the 
 whole body B is repelled by the fluid, in A. But, on 
 the other hand, the matter in A attrafts the fluid in 
 B, and coniequently attrafts the whole body B : Simi- 
 lar action is exerted by B on A. Thcfe contrary for- 
 ces are either equal, and deftroy each other, or unequal, 
 and one of them prevails. This equality or inequality 
 evidently depends on the quantity of fluid contained in 
 one or both of the bodies (n° 7.) Now it is known 
 that bodies left entirely to themfelves neither attraft 
 nor repel ; and it follows from the hypothetical proper- 
 ties of the fluid, that if there be either a redundancy or 
 deficiency of fluid, there will be an efflux or influx, till 
 the attraftionscind repulfions balance each other. There- 
 fore the internal fl:ate of two bodies which neither at- 
 trafl nor repel each other, is that where each contains 
 its natural quantity of eleClric fluid. 
 
 9. In order, therefore, to conceive dlftinftly the ftate of 
 a body containing its natural quantity, and to have a 
 diftinft notion of this natural quantity, we muft fuppofe 
 that the quantity of fluid competent to a particle of 
 matter in A repels the fluid competent to a particle of 
 matter in B, jufl; as much as it atti-afts that particle of 
 matter ; and alfo, that the fluid belonging to a particle 
 of matter in A, repels the fluid belonging to a particle 
 of matter in B, juil as much as the particle of matter 
 in A attrafts it. Thus the whole flnid in the one re- 
 pels the whole fluid in the other as much as it attracts 
 the whole matter. 
 
 Since this muft be conceived of every particle of com- 
 mon matter in a body, we muft admit, that when a body 
 is in its natural ftate, the quantity of eleftric fluid in it 
 ' is proportional to the quantity of matter, every particle 
 being united with an equal quantity of fluid. This, 
 however, does not neceffarily require that different 
 kinds of matter, in their natural or faturated ftate, {hall 
 contain the fame proportion of fluid. It is fufiicient 
 that each contains fucli a quantity, uniformly diftribu- 
 ted among its particles, that its repulfion for the fluid 
 in another body is equal to its attraftion for the com. 
 
 mon matter in it. It is, however, more probable, for 
 reafons to be given afterwards, that the quantity of elec- 
 tric fluid attached, or competent, to a particle of all 
 kinds of matter is the fame. 
 
 We ftiall now conlider more particularly the imme- 
 diate refuks of this hypothecs, in the moll limple cafes, 
 from which we may derive lome elementary propoli- 
 tions. 
 
 Since our liypothcfis is accommodated to the faft, Eleflric 
 that bodies ia their natural ftate, havi.ig their natural ph'"riiticr 
 quantity of electric fluid, are altosrether inactive on each*", 'l"'"' 
 other, by making this natural quantity lucb, that its^,, (icficie, 
 mutual repulfion exactly balances its attraction for thecy in flu c 
 common matter— it follows, that we muft deduce all the'" alorj-a 
 electric phenomena from a redundancy or deficiency of"^ 
 ele>^n'c fluid. This accordingl,- is the Frankliuian 
 doctrine. The redundant ftate of a body is called by 
 Dr Fra.iklin positive or plus electricity, and the 
 deficient ftate is called negative or minus electri- 
 city. 
 
 A body may contain more than its natural quantity, 
 or lei's, in every part, or it may be redundant in one 
 place and deficient in another. Thefe dl.'"";rent condi- 
 tions will exhibit different appearances, which muft be 
 confidered firft of all. ,j 
 
 Let the body (fig. i.) be fuppofed in its natural Atflion of 
 ftate throughout, which we fliall generally exprefs by '''^ ''^''i" 
 faying that it is saturated ; and let us exprefs the ^1' "' 
 
 • r n • 1 ■ J r • r • i i r ^ matter 
 
 quantity of fluid required for its faturation by the fym-howconv 
 bol Q^ Let P be a fuperficial particle of the fluid. It touted, 
 is attrafted by the common matter of the body (which 
 we fliall in future call Amply the mutler), and it is re- 
 pelled equally by the fluid. Let us call the attraction 
 II, and the repulfion r. Then the force with which the 
 fuperiicial paiticle is attraCl;ed by the body, muft be 
 =: a — r, and a — r muft be rr o, becauie a r= r. Let 
 the quantity^of fluid be added to the body, and uni- 
 formly diftributed through its fuhftance. Then, be- 
 caufe we muft admit that the adtion is in proportion 
 to the quantity of afting fluid, and this is now Q__+y> 
 
 we hav 
 
 -c:l=Q_+/=-^^--;- 
 
 Q_ 
 
 d therefore 
 
 P ie repelled by the whole fluid with the fori:e_St-i — > 
 
 or r -|- ; 
 
 But it is attrafted by the 
 
 :=a — I -7^. Bute — r = o. Therefore the whole 
 
 --''': that is, P is repelled with the 
 
 common matter in the fame manner as before, that is, 
 with a force =: a. Therefore the whole a6tion on P is 
 
 q: 
 
 aftion on P is : 
 
 fr 
 force -pr. 
 
 This will perhaps be as diftinflly conceived by recol- 
 lecting, that as much of the fluid as was neceflliry for 
 faturation, that is, the quantity (3 , puts the particle P 
 in equilibrio ; and therefore we need only confider the 
 adlion of the redundant fluid _/". To find the repulfive 
 
 force of this, fay Q:f:= r :<—, and prefix the fign 
 
 — ; becaufe we are to confider attraftions as pofitive, 
 and repulfions as negative, quantities. 
 
 Unlefs, therefore, the particle P be withheld by fome o- 
 
 ther
 
 ELECTRICITY. 
 
 l« ther force, it will quit the body, being expelled by a foice the redundancy or Jeficicncy is fuperfici.il, follows from 
 
 te«ofa /•;. . . this hypothcfis ; for when the fiirface is ovtrcharirtd 
 
 ■'^ And as every fuperfic.al particle is in a f.m.Iar ^^ th^ .ncans employed for exciting, the impermeabili- 
 
 iituation, we fee tliat there will be an efflux from an ty of the eledric per ft prevents this redundant fluid 
 
 overcharged body, till all the redundant fluid hus quit- *rom penetrating to any depth ; and wlien ihe furface 
 
 ted it. This efflux will indeed gradually diminilh as has been rendered deilcient in fluid, the fame inipermca- 
 
 56» 
 
 ly CaU- 
 
 r efflux 
 
 »3- 
 
 fr... 
 the expelling force pr- dimlniflies ; that is, as / dim:- 
 
 niflies, but will never ceafe till/ be reduced to nothing. 
 But if there he either an external force afting on the 
 fupcrficial fluid in the oppnfite diredtion, or fome inter- 
 nal ubftruAion to its motion, the efflux will (lop when 
 the remaining expelling force is ju(l in equilibiio with 
 this external force, or this ohftruilion 
 
 On the other hand, if the body contains lefs than its 
 natural quantity of fluid, there will be an influx from 
 without ; for if there be a deficiency of fluid — f, the 
 
 hility prevents the fluid from expanding from the inte- 
 rior parts, fo as to contribute to the replenifhing the 
 fuperficial ftratum with fluid. If, indeed, we could fall 
 on any way of overcharging the interior parts of a glafs 
 ball, or of abllrafting the natural quantity from them, it 
 is highly probable, that it would continue to attraft or 
 repel even after it had been jilunged in water. Although 
 the furrounding water would inftantly take off the fluid 
 redundant contained in the very furface, the repulfion 
 of the fluid in the internal parts would fliU be fenlible; 
 nay, if a very fmall permeability be fuppofed, the body 
 would again become overcharged at the furface; jufta3 
 we fee, that when we plunge a red-hot ball of iron into 
 water, and take it out again immediately, it is black on 
 the furface, and may be touched with the finger ; but 
 in half a minute after, it again becomes red hot. Per- 
 haps this may be acconiplilhed with a ;;lobe of fealing 
 wax, which is permeable while liquid, by eleftrifying it 
 in a particular way wliile in that flate, and allowing it 
 to freeze. But the reader is not far enough advanced 
 
 particle P will be repelled with the foice S— —-^ ' 
 
 f r 
 
 = ;• — — . It is attrafted with the force a ; and tliere- 
 
 fr fr 
 
 fore the whole aftion is = a — r ■\- pr-, =: -{- -r- (be- 
 
 caufe a — r = o) ; that is, P is attraded with the force 
 
 fr --. ._. ^... 
 
 ^ Fluid will therefore enter from all quarters, as ;„ the hypothefis to undcrdand the procefs which mull 
 
 long as there is any deficiency of the quantity necef- '^'^ followed. He cannot but recoiled, however, many 
 fary for faturation, unlefs it be oppofed by fome exter- examples in coated glafs, &c. where the cledricity is 
 nal force, or hindered by fome internal obilrudion. "'"''^ pertinacioufly retained by a furface in very clofc 
 
 When there is a deficiency of fluid, there is a redun- contad with condudors. 
 dancy of matter, fuch that its attradion for external . ^'^'^ "^ ""^^ fuppofe a body NS (fig. 2.) contain- Cnnfeqnen- 
 fluid is equal to the repulfion of a quantity/of fluid, '"g '" ''"= ^'^•f NA a quantity/ of redundant fluid, «s of une. 
 This confirms the affumption in n» lo, that the aiiion "nd in the half AS let there be a deficiency g of fluid ! (^^"hmion' of 
 of a body on the ekaric fluid depends entirely on the re- ^^^^ 's, let there be a quantity of matter unlaturatcd.fluij '°"a°. 
 
 and fuch as will attrad fluid as much as the quantity _i,'tioii on ex- 
 of fluid would repel it. Let the fluid neccflary for theteinal fluid, 
 faturation of each half of NS be Q^ as before. Let 
 the attradion of the whole matter of NA for a par- 
 ticle of fluid at N be a ; and let r be the repulfion 
 exerted on the fame particle N by the whole uni- 
 formly diftributed fluid in NA, and let r' be the repul- 
 fion exerted by the fume quanlity of fluid in the re- 
 mote part SA. Then the force with which the par- 
 cumft^ance alone, therefore, is fufficient to conllitute the ^"^'"^ N or S is attraded by the merely faturated body 
 
 ,. dundant fluid, or the redundant matter of the body. 
 wboiies The efllux or influx may be prevented, either by fur- 
 ideo- rounding the body with fubilances, through the pores 
 "^1"*"^ of which the fluid cannot move at all, or by the body 
 ^ itfelf being of this conflitution. And thus we fee, that 
 
 the very circumftance of being impervious to the fluid, 
 or completely permeable, renders the body capable or 
 incapable of permanently exhibiting eledrical pheno- 
 mena, if furroimded by permeable bodies. This cir 
 
 I.? 
 
 difference between eledrics per fe, and non-eltflrics. — 
 Here, then, is a numerous clafs of phenomena, which 
 receive an explanation by this hypothetical conflitution 
 of the eledric fluid. All electrics per fe are bodies fit 
 for confining eledricity in bodies which are rendered 
 capable (by whatever means) of producing eledrical 
 phenomena ; and no.condudlor, or fubRance which al- 
 lows the eledricity to pafs through it, can be made 
 eledric by any of the means which produce that eftcd 
 in infulators. And it is well known that the eledricity 
 of eledrics is vaftly more durable than that of non-elec- 
 trics in fimilar fituations. It is true, indeed, that an 
 
 NS muft be :2 a — r — r. This is evidently no- 
 thing, if the body be in its natural ftate. But as NA 
 contains the redundant fluid/, and SA is deficient by 
 
 the quantity g, the whole adion muft be a — '"}^I— 
 
 , Q_ 
 
 — -== — ~ '- But becaufe a 
 
 Q^ 
 
 — r' = 0, the 
 
 g r — / r 
 adion becomes = g- , or becaufe r is greater 
 
 than r, the particle N is repelled with the force ^77'^ 
 
 eledric, which has been excited fo as to exhibit eledric I" I'^e manner the particle S is attraded with the 
 
 phenomena with great vivacity, lofes this power very , g'' — f'' 
 
 quickly if plunged into water, or any other conduding °^^^ Q~ " 
 
 body. But this is owing to the redundancy or defi- In the mean time, a particle C, fituated at the mid-i. Action 
 
 ciency being quite fuperficial, fo that the parts which die, muft be in equilibrio, if the body be in its natural"" '•'^ '""- 
 
 are difpofed to give out or to take in the fluid are in ftate, being equally attraded, and alfo equally repelled, "'"^'^'''''^* 
 
 immediate contad with the conduding matter. That on both fides. But as we fuppofe that NA is overchar! 
 SoppL. VoL.I. Part II. ^g ^j
 
 i62 
 
 ELECTRICITY. 
 
 ged with the quantity/, C muft be repelled in the di- is overcharged at one end, and undercharged at the 
 
 reftion CS with the. force rr-. And if we alfo fuppofe 
 that AS 13 deficient by the quantity^, C is attraAed in 
 the dlreftion CS with a force — . Therefore, on the 
 whole, it is urged in the direction CS with the force 
 
 «7 
 V will be 
 unif' irmly 
 cltffuied, 
 uulcfs oh- 
 Urudted. 
 
 IS 
 
 Nature of 
 
 theobftruC' 
 
 tion. 
 
 other, and capable of retaining this Ilate, is applicable, 
 in every particular, to two conducing bodies NA and 
 SA', having a non-coiidutting body Z interpofed be- 
 tween them, aa in fig. ^. All the formulas, or cxpref- 
 fions of the forces which tend to expel or to draw in fluid, 
 are tlie fame as before. Perhaps this is the bcft way of 
 forming to ourfelves a diftindl notion of the body that 
 is redundant in fluid at one end, and deficient at the 
 other. And we perceive, that the ftate of the two bo- 
 dies, feparated by the eleftric Z, will be more perma- 
 nent when one is overcharged, and the other under- 
 charged, than if both are either over or undercharged. u 
 
 It muil be remarked, that the quantities/ and g were A body 
 taken at random. They may be fo taken, that tlie""?'^'" 
 nilarly diftribut .d, and equally divided, be- force with which the flnld tends to efcape at N, or to „j. Jj^^']" 
 two halves of NS. Therefore a ftate like enter at S, may be nothing, or may even be changed where it i 
 
 to their ojjpofite. Thus, in order that tliere may be'"eJ"'"lant 
 no tendency to efcape from N, we have only to fuppofe °'" 
 
 fr 
 g r' — / r =r c, or g :f =z r : r' , and g =. — r. In this 
 
 cafe, the particle at N is as much attraftcd by the re- 
 dundant matter in SA as it is repelled by the redun- 
 dant fluid in NA. 
 
 When the extremity N is rendered inaftive in this Q^jdj,;,,,, 
 manner, the condition of the other extremity S is con- necclT:iry 
 
 />■ +gr f + gXr 
 — Q— , or — (^. 
 
 Hence we learn, that as long as there is any redun- 
 dancy in AN, and deficiency in AS, there is a tenden- 
 cy of the redundant fluid to move from N toward S ; 
 and, if the body be altogether permeable by the elec- 
 tric fluid, we cannot have a permanent ftate till the 
 fluid 13 fim 
 tween the 
 
 that affumed in this example cannot be permanent in a 
 conducing body, unlefs an external force act on it ; 
 but it may fubfift in a non-condu6tor, and in a leficr de- 
 gree, in all imperfeA condiiflors. 
 
 It is necefl"ary, in this place, to confider a little the 
 -nature of that refiftance which muft be afiigned to the 
 motion of the ekaric fluid through the pores of the 
 body. If it refemble the refiftance oppofed by a per- 
 feft fluid, arifirg folely from the inertia of its particles, 
 thfen there is no inequality of force fo minute but that flderably changed. To difcover this condition, putforthis. 
 
 operate a uniform diftribution of the fluid, or at f r , 
 diftribiition which will make the excefs of the -~ in pli 
 
 ace of ^ in the formula • 
 
 -fr' 
 
 CL, 
 
 which expref- 
 
 19. 
 
 not be followed by an equable diftribution of the fluid. 
 In every part there will remain fuch an inequality of 
 diftribution, that the want of equilibrium between the 
 eleftric attraftiuiis or repulfioDS is balanced by the te- 
 nacity of the parts. 
 
 We learn farther from the foregoing proportions, that 
 a particle at N is lefs repelled than if the part AS were 
 overcharged as AN is : for in that cafe, it would be ex- 
 
 fXr + r' , . , . , 
 
 pelled by a force "^ ^ , which is much greater 
 
 for th( 
 
 it will 
 
 ieaft a 
 
 mutual attradions and repulfionsprecilelyequal and op- ^^^ ^^^ attraftion for a particle at~S, and we obtain 
 
 pofite to the external force which keeps it in any Itate ^ ,; 
 
 of unequal diftribution. But it may refemble there- jJlL__L-. 
 
 fiftance to the defcent of a parcel of fmall ftiot difTemi- Qf 
 
 iiated among a quantity of grain, or the refiftance to On the other hand, we may have the redundancy 
 
 motion through the pores of a plaftic or duftile body, and defieiency fo balanced, that there ftiall be no ten- 
 
 fuch as clay or lead. Here, in order that a particle dency to influx at S. For this purpofe, we muft make 
 
 may change its place, it muft overcome the tenacity of fr' . o .1. a.- » m 
 
 1. J- • ° .-1 r »i,» k„p„' ThprefnYP vuhpn s = — • WhcH this obtams at b, the action at N 
 
 the adjoining particles 01 the body. 1 nereiore, wnen 6 ,. » 
 
 an unequal diftribution has been produced by an exter- ^i\i ]^g j^^j ^y putting ■'— in place of g in the formula 
 
 nal force, the removal or alteration of that force will j.^ ^^ r f%7^- 
 
 J 2_, and this will give us-' — 
 
 force repelling a particle at N. 
 
 When the tendency to efl3ux or influx is induced in 
 this manner, by a due proportion of the redundancy and 
 deficiency of eleftric fluid, the part of the body where 
 this obtains is by no means in its natural ftate, and may 
 contain cither more or lefs than its natural quantity. 
 But it neither afts like an overcharged nor like an un- 
 dercharged body, and may therefore be called neu- 
 tral. The reader, who is converfant with eleftrical 
 experiments, will recollcft numberlefs inftances of this, 
 and will alfo recoUeft that they are important ones. 
 Such, for example, is the cafe with the plates and co- 
 vers of the eletlrophorus. Thefe circumftances, there- 
 
 14. 
 
 *5- 
 
 
 And, in like manner, the particle S 
 
 than 
 
 is attraftcd with lefs force than it would be if NA were 
 
 equally undercharged with SA. 
 
 The condition of the body now defcribed may be fore, claim particular attention, 
 
 changed by different methods. The redundant fluid As the quantities/ and ^ may be fo chofen, that the 
 
 in AN may flow into AS, where it is deficient, till the appavtus ihall be neutral, either at S or at N ; they may 
 
 whole be uniformly diftributed ; or fluid may efcape likewife be fo, that either end fl\all exhibit either the • 
 
 from AN, and fluid may enter into AS, till the body appearance oi redundancy or dejictency. Thus, inftead of 
 
 be in its natural ftate. The firft method will be fo ncutrahty at N, we may have repulfion, as at the firft, 
 
 much the flower as the body is lefs permeable, or more . . »i, /'" if «o »!,. 
 
 remarkably deark fer Je ; and the Lond method will by "taking . lefs m any degree than -j. If, on the 
 
 be flov;er than if the whole body were overcharged or contrary,^ be greater than-LT, the extremity N, tho' 
 
 undercharged. , ■„ o. n C t i-i t 
 
 What v?e have been now faying of a body NS that overcharged, will attrad fluid. In hke manner, it £ 
 
 !«..
 
 ELECTRICITY. 
 
 be lefs than -LI, the extremity S, although undcrchar- 
 »• 
 
 ged.will repel fluid.— We may make the following ge- 
 neral remarks. 
 
 1. Both extremities N and S cannot be neutral at 
 the fame time : for fince the neutrality arifes from tlie 
 increafed quantity of redundancy or deficiency at the 
 otlier extremity, fo as to compenfate for its greater di- 
 ftance, the aftivity of that extremity mull be propor- 
 tionably greater on the fluid adjoining to its lurlace, 
 whether externally or internally. When an overcharged 
 extremity is rendered neutral, the other extremity at- 
 tradls fluid more (Irongly ; and when a deficient extre- 
 mity is rendered neutral, the other repels fluid more 
 flrongly. All thefc elementary corollaries will be fully 
 verified afterwards, and give clear explanations of the 
 moft curious phenomena. 
 
 2. We have been fuppofing that the redundant fluiil 
 is uniformly fpread, and that the body is divided into 
 equal portions ; but this was merely to limplify the 
 procedure and the formulse. The reader muft fee that 
 the general conclufions are not afi'efted by this, and 
 that fimilar formula will be obtained, whatever is the 
 difpofition of the fluid. We cannot tell in what man- 
 ner the redundant fluid is difpofed, even in a body of 
 the fimplcft form, till we know what is the variation of 
 its attraction and repulfiou by a change of diftance; and 
 even when this has been difcovered, we find it difficult 
 in moft cafes, and impoflible in many, to afcertain the 
 mode of diftribution. We fhall learn it in fome im- 
 portant cafes, by means of various phenomena judiciouf- 
 ly felefted. 
 
 A body may be confidered in many divifions, in fome 
 of which the fluid is redundant, and in others deficient. 
 We may exprefs the repulfion of the whole of this body 
 in the fame way as we exprefs that of a body confidered 
 in two divifions, ufing the letters/, g, h, &c. to exprefs 
 the quantities of redundant or deficient fluid in each 
 portion, while Q_exprefles the quantity neceflary for 
 faturating each of them ; and the repulfion at different 
 difl;ances may be exprefled by r, r, r", r"', &c. as 
 they are more and more remote ; and we may ex- 
 prefs their aflion as attraftive or repulfive by prefix- 
 ing the fign -f- or — . Thus the attradlion may be 
 (fr — g r' ^ h r" — :' r'") 
 
 S^3 
 
 30. 
 
 19 
 
 ; nfible ac' 
 ' ms of 
 
 . dies. 
 
 Q_ 
 
 -', &c. 
 
 . Having obtained the expreflions of the invifible ac- 
 tions of eleftrified bodies on the fluid within them, or 
 furrounding them, let us now confider tlieir fenfible ac- 
 tions on other bodies, producing motion, or tendencies 
 to motion. 
 
 Here it is obvious that the mechanical phenomena 
 exhibited are what may be called remote effects of the 
 afting forces. The immediate eff"eas, or the mutual 
 aftions of the particles, are not obfcrved, but liypothe- 
 tically inferred. The tangible matter of the body is 
 put in motion, in confequence of its connexion with 
 tlie fluid rcfiding in the body, whicli fluid is the only 
 fubjeft of the aflion of the other body. 
 
 In confidering thefe phenomena, we fliall content 
 ourfelves with a more general view of the artions which 
 take place between the fluid or tangible matter of the 
 one body, and the fluid or matter of the other, fo as to 
 gain our purpofe by more fimple formula; than thofe hi- 
 therto employed. They were premifcd, however, be- 
 
 caufe we mt//? have recourfe to them on many very im- ■ 
 portanl particular occafions. 
 
 Let there be two bodies, A and B, in their natural 
 ftate. Let the tangible matter in A be called M, and 
 let the fluid necefiary for its faturation be called F, and 
 let m and /be the tangible matter and the fluid in B. 
 Let the mutual aftion between a fingle part'cle of fluid 
 and the matter necefi"ary for its faturation be exprclTed 
 by the indeterminate fymbol x, bccaufe it varies by a 
 change of diftance. 
 
 The a(aions are mutual and equal. Therefore when 
 the motion of B by the aftion of A is determined, the 
 motion of A is alio afcertained. We fliall therefore on- 
 ly confider how A is afl^efted. i. Every particle of fluid 
 in A tends toward every particle of matter in B with 
 the force 2. The whole tendency of A toward B may 
 therefore be exprefled by z, multiplied by the produill 
 of F and m. 2. Every particle of fluid in A is repelled 
 by every particle of fluid in B, with the fame force s. 
 3. Every particle of matter in A is attrarted by every 
 particle of fluid in B, with the fame force. We may 
 exprefs this more purely and briefly thus : 
 
 1. F tends toivard m with the force -f- Fmz 
 
 2. F tends /rem /with the force — F/ z 
 
 3. M tends toward f \n\k\\ the force -j- M/z 
 
 Therefore the fenfible ten dency of A to or from B will 
 be = z X F w -I- M/— Ty. But, by the hypotl-.tfis, 
 the attraftion of a particle of the fluid in A for a par- 
 ticle (if the matter in B, is equal to Its repulfion for the 
 particle or parcel of the fluid attached or competent to 
 that particle of matter. Therefore the attraftion Fmz 
 is balanced by the rcpulfioji F/z. Therefore there re- 
 mains the attradlion of the matter in A for the fluid in 
 B unbalanced, and the body A will tend toward the 
 body B with the force M/z, or B attrafts A with the 
 force M/z. A muft therefore move toward B. And, 
 by the 3d law of motion, B muft move toward A with 
 equal force. 
 
 But the faft is, that no tendency of any kind Ts ob-Comple- 
 ferved between bodies in their natural ftate. The hy. ''"""f "^e 
 pothefis, therefore, is not complete. If we abide by it, ^'V^'^'"'^ 
 as far as it is already exprefll-d, we muft farther fuppofe, "*''"""*■ 
 that there is fome repulfive force exerted between the 
 bodies to balance the attraftion of M for/. Mr ^pi- 
 nus, therefore, fuppofcs, that every particle of tangible 
 matter repels another particle as much as it attrads the 
 fluid necefl'ary for its faturation. The whole aftion of 
 B on A will now be = z X i: m — Vf — M m -j- M/. 
 Ymz is balanced by F/z, and Mmz by M/z, and 
 no excefs remains on either fide. 
 
 ./Epinus acknowledges that this circumflance appear- oljeffions 
 ed to himfelf to be hardly admifllhle ; it feeming incon-anfwaeA 
 ceivable that a particle in A fliall repel a particle in B, 
 or tend from it, eledlrically, while it attracts it, or tends 
 toward it, by planetary gravitation. We cinnot con- 
 ceive this ; but_ more attentive confideration (hewed 
 him, that there is nothing in it contrary to the obferved 
 analogy of natural operations. We muft acknowledge, 
 that we fee innumerable inftanccs of inherent forces^of 
 attraftion and repulfion ; and nothing hinders us from 
 referring this lately difcovered power to the clafs of pri- 
 mitive and fundamental powers of nature. Nor is there 
 any difficulty in reconciling this repulfion with univer- 
 fal gravitation ; for while bodies are in their natural 
 4^5 ftate.
 
 564 ELECT 
 
 ftate, the eleAric attraflions and rcpulfions precifely ba- 
 lanee each other, and there is nothing lu uilhub the 
 phenomena of planetary gravitation ; and wlieii bodies 
 are not in their natural elcArical Hate, it i«i a fail that 
 their gravitation is difturbed. Although we cannot 
 conceive a body to have a tendency to another body, 
 and at the fame time a tendency from it, when we de- 
 rive our notion of thefe tendencici entirely from our 
 own coi\fcioiifneff. of effort, endeavour, cimatits, nijvs ac- 
 ceJendi feu recedituh, nothing is niore certain thaa that 
 bodies exhibit at once the appearances which we endea. 
 Tour to exprefs by thefe words. We can bring the 
 north poles of two magnets near each other, in which 
 cafe they recede from each other ; and if this be pre- 
 vented by fome obftacle, they prefs on this obftacle, and 
 feem to endeavour to feparate. If, whde they are in 
 this ftate, we elcftrify one of them, we find that they 
 win now approach each other ; and we have a diftinft 
 proof that both tendencies are in aftual exertion by va- 
 rying their diftances, fo that one or other force may 
 prevail ; or by placing a tliird body, which fhall be af- 
 fefttd by the one but not by the other, &c. We do 
 not underlland, nor can conceive in the lead, how ei- 
 ther force, or how gravity, refides in a body ; but the 
 effefts are pall contradiction. It muft be granted, 
 therefore, that this additional circumflance of jEpinus's 
 hypothefis has nothing in it that is repugnant to the 
 obferved phenomena of Nature. 
 
 N. B. It is not necelTary to fuppofe (although Mr 
 JEpinus does fuppofe it), that every atom of tangible 
 matter repels every other atom. It will equally explain 
 all the phenomena, if we fuppofe that every particle 
 contains an atom or ingredient having this property, 
 and that it is this atom alone which attradls the parti- 
 cles of eleftrical fluid. The material atoms having 
 this property, and their correfponding atoms of fluid, 
 may be very few in comparifon with the number of 
 atoms which compofe the tangible matter. Their mu- 
 tual fpecific aftion being very great in comparifon with 
 the attraftion of gravitation (as we certainly obferve in 
 the aftion of light), all the phenomena of eleftricity 
 ■will be produced without any fenfible effeifl on the phe- 
 nomena of gravitation, even although neither the clcitric 
 fluid nor its ally, this ingredient of tangible matter, 
 fhould not gravitate. But this fuppofitlon is by no 
 means neceflary. 
 
 Since we call that the natural eleftrical ftate of bo- 
 dies in which they do not aft'eft each other, and the 
 hypothetical powers of the fluid are accommodated to 
 this condition, we may confider any body that has 
 more than its natural quantity as confiding of a quan- 
 tity of matter faturated with fluid, and a quantity of 
 redundant fluid fupevadded ; and an undercharged body 
 may be confidered as confiding of a quantity of matter 
 Xuperaddtd. The faturated matter of thefe two bodies 
 ■will be totally ir.aftive on another body in its na.tural 
 ttate, and will neither attraft nor repel it, nor be at- 
 trafted nor repelled by it ; therefore the aftion of the 
 overcharged body will depend entirely on the redundant 
 fluid ; and that of the undercharged body will depend 
 entirely on the redundant matter; therefore we need 
 only confider them as confiding of this redundant fluid 
 or mptter, agreeably to what was faid in more vague 
 terms in n" 10. and 13. This will free us from the 
 complicated formulae which would otherwife be necef- 
 fary for eapreffing all the aftions of the fluid and tan- 
 
 R I C I T Y. 
 
 gible matter of two bodies on each other. The refulu 
 will be fufHciently particular for diftinguifhing the fen- 
 fible aftion of bodies in the chief general cafes : but in 
 fome particular and important cafes, it is abfoliitely ne- 
 ceflary to employ every term. ,, 
 
 1. Suppofe two bodies A and B, containing the '^'"eral e> 
 quantities F and/' of redundant fluid, it is plain that f r'"""" . 
 their mutual aftion is exprcflcd by F X/' + a, and that Li) "oftht 
 it is a repulfioii ; for fince every particle of redundant mutual ag. 
 fluid in A repels every particle of redundant fluid in B '''"'• 
 with the force s ; and fince F' andy"' are the numbers 
 
 of luch particles in each, the whole repulfion muft be 
 exprcfled by the produ6\ of thefe numbers. 
 
 2. In like manner, two bodies A and B, containing 34- 
 the redundant matter M' and m , will repel each other 
 with the force M' m %. 
 
 3. And two bodies A and B, one of which A con- 3;. 
 tains the redundant fluid F', and the other B contains 
 
 the redundant matter m', will attraft each other with 
 the force F ni z. 
 
 4. It follows from thefe premifes, that if either of 36. 
 the bodies be in Its natural ftate, they will neither at- 
 traft nor repel each other ; for, in fuch a cafe, one of 
 
 the faftors F', or _/"', or M', or m', which is neceflary 
 for making a produft, is wanting. This may be per- 
 ceived independent of the mathematical formula ; for if 
 A contain redundant fluid, and B be in its natural 
 ftate, evei7 particle of the redundant fluid in A is as 
 much repelled by the natural fluid in B as it is attrafted 
 by the tangible matter. 
 
 The three firft propofitions agree perfeftly with thes^jn,;' 
 known phenomena of eleftricity ; for bodies repel psradoi. 
 each other, whether both are pofitively or both are 
 negatively eleftrified, and bodies always attraft each 
 other when the one is pofitively and the other negative- 
 ly eleftrified. But the fourth cafe feems very incon- 
 fident with the mod familiar phenomena. Dr Frank- 
 lin and all his followers aflTcrt, on the contrary, that 
 eleftrified bodies, whether pofitlve or negative, always 
 attraft, and are attrafted, by all bodies which are in 
 their natural ftate of eleftricity. But it will be clearly 
 fhewn prefently, that they are miftaken, and that 
 Franklin's theory neccflTarlly fuppofcs the truth. of the 
 fourth propofition, otherwife two bodies in their na- 
 tural ftate could not he neutral or inaftive, as any one 
 may perceive on a very flight examination by the 
 Fiankliaian principles. It will prefently appear, with 
 the fulleft evidence ; and, in the mean time, we proceed 
 to explain the aftion of bodies which are overcharged 
 in fome part, and undercliarged in another. -j 
 
 Let the body B (fig. 4.) be overcharged in the part Aiflion of 
 B II, and undercharged in the part B s, and let/' and ^.'""'y ha- 
 m' be the redundant fluid and common matter in thofe^'"? ' ' 
 parts; let A be overcharged, and contain the redun-quably (li£ 
 dant fluid F; let z and z' exprefs the intenfity of ac-jxifcd. 
 tion correfponding with the diftances of A from the 
 overcharged and undercharged parts of B ; the part 
 B n repels A with the force T' f z, while the part B J- 
 attrafts it with the force F' m' z: A will therefore be 
 attrafted or repelled by B, according as F' m z' is 
 greater or lefs than ¥' f z' ; that is, according as m' z' 
 is greater or lefs than /' a. This, again, depends on 
 the proportion of _/"' to rn , and on the proportion of 
 s to z'. The firft depends on many external circuni- 
 ftances, which may occafion a greater or lefs redundan- 
 cy or deficiency of eleftrical fluid ; the fecond de- 
 pends
 
 ELECTRICITY. 
 
 pends entirely on the law of eleftric attraftion and re- to an overcharged body, the other end ftrongly aftrafls 
 
 pulliun, or the change produced in its iiiteniity by a it; and when the undercharged end is rendered neutral 
 
 change of dillance. As we are, at prefent, only aim- to the fame body, the overcharged end ftrongly repels it, 
 
 ing at very general notions, it is enough to recolleft, Similar appearances are exhibited when A is under- 
 
 that all the eledlric phenomena, and indeed the general charged. 
 
 analogy of nature, concur in fliewing tiiat the inteniity Thcfe cafes are of frequent occurrence, and are im- 
 
 of both forces (attratiion and repullion) decreafcs by portant, as will appear afterwards. 
 
 an increafe of dillance; and to combine this with that It is eafy now to fee what changes will be made on 
 
 circumftaiice of the hypolliefis which ftates the icpul- the aftion of B on A, by changing the proportion of 
 
 fion to be equal to the attraftion at the fame dillance ; ,, , i ic , . , , f z . .,, , 
 
 , , , ^, (• k ,1 f I 1 I,, „ /'andm. II m be made greater than •' , A will be 
 
 theiefure both forces vary by the lame law, and we have •' a 
 
 z always greater than a . The xilible adlion of B on attrafted in the fituation where it was formerly neutral; 
 
 A (which, by the 3d law of motion, is accompanied by and if m' be made lefs, A will be repelled, &c. &c. 
 a limilar adtion of A on B) may be various, even with Therefore, when we obferve B to be neutral, or at- 
 
 one pofition of B, and will be changed by changing this traftive, or repullive, we mull conclude that m is Cf^ual 
 pofition. fz 1 /- 1 • 
 
 I. We may fnppofe that B contains, on the whole, ^° •^' °'' gi'^^ater or lefs than it, &c. 
 
 its natural quantity, but that part of it is abftracl:ed -iir^ 1 ,„^ ■ ^_„ .!,,_■ » .i, » .u j 
 
 ' ,, ^, ■ ' , , ■ ^ -r, 'PL- ■ We have been thus minute, that the reader may per- 
 
 from lis, and is crowded into tin. I his is a very „„;,.„ ,1, ^ . .„„ .u . -i.- ji- i j 
 
 ' r A Mr r 1 i • ni ceive t he agreement between this aftion On a body con. 
 
 common cale, as we ihall lee prelcntly, and it will be ,_,•„•„ ^ \° j , a -j j .u n- .l r r 
 
 _. , . ' ,- , , ^ , . ;.' , 1 . taming redundant fluid, and the aftion on the fuperfi- 
 
 exprelied in our lormula by makinff /' := m'. In this „• ,1 a -i j- . 1 rj 1 • ,> 
 
 f"-' ! &J , T , cial fluid riinntrly coniidered in n" 21, 22, 2i, 24. 
 
 cafe, thereioie, we have r / z crieatcr than t m' z, ■\r-,r\.^„ .i,„r .1 • .. j j n. ti 1 ■ 
 
 , ' ' ■ , ■' A °-ii L <: 1 When theie things are attended to, we (hall explain, 
 
 becaufe z is g-re&ter than %'. A will therefore be re- ,„■,;, . r \i ..i, ■ l r l 1 
 
 , 1 . L T3 ^ J -11 1 ■• J u li- nv. with great eale, all the curious phenomena of the elec- 
 
 pcUcd by B, and will repel it; and the repullion will be ,ronli°ri- 
 
 S^S 
 
 41. 
 
 F'/'X a — z'. 
 
 It is evident that if A be placed on the other fide 
 of B, the appearances will be rcvcrfed, and the bodies 
 will attraft each other with the force Y'f'Xz — z'. 
 
 It is alfo plain, that if A be as much undercharged 
 as we have fuppokd it overcharged, all the appearances 
 will be reverfed ; if on the undercharged fide of B, it 
 
 At 
 
 trophorus 
 
 'I here is another circiimflance to be attended to here, Neutrality- 
 which will alfo explain fome eleSiical appearances thatS'^"<^""y 
 feem very puzzling. We limited the inadivity of B''™i!f.^j°(_* 
 to a certain preclfe dillance of the body A. This in-^nce.^ Im- 
 
 adivity required that ,„' Hiould be =:-Cl. If A beH'^'JlU"' 
 
 , 1 ,, ,, . ^,,,., obtained 
 
 Drought nearer, both z and s are incresfed. If they fjom this. 
 
 will be repelled ; and if on the overcharged fide of B, arc both increafed in the fame proportion, the value of 
 
 it will be attrafted. » -n l u r , r ,,,,«■,.. 
 
 2. If the redundancy and deficiency In the two por- "- ^'U ^^ ^he fame as before, and the body A will iiei- 
 
 tions of B be inverftly proportional lo the forces, fo ther be attraded nor repelled at this new dillance. But 
 
 lodies ocU' 
 ral at one 
 lid are 
 lore ac- 
 'ie at tiie 
 
 that F : m' = z' : z, we (hall have /'z = ra' z, and to' jf ^ Increafe fafter than z', we fliall have / a greater 
 
 = r^. In this cafe thcfe two aftions balance each ''"" "''-'' ^"'^ ^ will be repelled; and if z increafes 
 z' _ _ more flowly than z', A will be aitrafled by bringing it 
 
 other, and A is neither attraded nor repelled when at nearer. The contrary tffcits will be obfervcd if A be 
 this precife dillance from the overcharged fide of B. removed farther from the ovtrclnrged end of B. This 
 B may be faid to be neutral with refpcft to A, al- explains many curious phenomena; and thofe pheuome- 
 though A and the adjoining fide of B are both over- na become inllruclivc, becaufe they enable us to difco- 
 charged. ver the law of eleftric adlioii, by {hewing us the man- 
 
 But if A be placed at the fame diftance on the other ner in which it diminirties by a change of dillance. E- 
 fide of B, the effetl will be very different ; For be- ledricians cannot but recolkdl many inllanccs, in which- 
 
 the motion of the cleSromtter appeared very caprici- 
 ous. I'he general faft is, that when an overcharged 
 pith ball is fo fituated near the overcharged fide of the 
 eledrophorus as to be neutral, it is repelled when 
 brought nearer, but attradied when removed to a great- 
 er dillance. This fhews that a increafes faller than z' 
 when A is brought nearer to B. Now, fiuce the bo- 
 dies may be again rendered neutral at a greater dillance 
 than before, and the fame appearances are Hill obfervcd, 
 it follows, that the law of adion is fuch, that dvcry di- 
 minution of dillance caufes z to increafe faller than a'. 
 We fiiall find this to be valuable information. 
 
 caufe m'=: — —, and m'z' is now changed into m z, and 
 /■' a into /z', we have the aftion on A = T^ v '-' 
 
 = ^xf-^ 
 
 _/.^'), = F/X. 
 
 ; that is, A is ftrongly at- 
 
 traded. 
 
 In like manner, f and m' may be fo proportioned, 
 that when A, containing redundant fluid, is placed near 
 the undercharged end of j- B, it lliall neither be attradl- 
 ed nor repelled, B becoming neutral with regard to A 
 at that precife dillance. For this purpofe m' muft be 
 
 43 
 :lion 
 
 Let us, in the laft place, inquire into the fenfible ef- Aiftic 
 And if A be now placed at the fame diftance fed on A when it alfo is partly overcharged and partly when the 
 L L ri TT, • M. . .,,.,,,- undercharged. This is a much more complicated cafe,''"''' '* ""* 
 
 on the other fide of B, it will be repeUed with the force and ,3 fufceptible of great variety of external appearan-^l'"'"'.'''*"^ 
 
 J- . 1 1 r 1 1 ^ . . ^ poled m 
 
 s, according to the degrees of redundancy and defi- botli bodlts. 
 
 F'/' X ±r^ 
 
 ciency, and according to the kind of cledricity (pofi- 
 Thus, when tKe overcharged end 13 rendered neutral live or negative) of the ends which front each other. 
 
 Firft,,
 
 ^<56 ELECTRICITY. 
 
 Firft, then, let xhf overcliarged end of A (fig. 5.) fliall prefently get full proof th.\t this is the cafe here j 
 
 fron the undercharged end of 6, they being overchar- but we preniiie this gcneiul view of the fubjeft, tliat 
 
 ged in N and n, but undercharged in S and s. Let F we may avoid the ijiore tedious, but more pliiKjf iphical, 
 
 and/be the quantity of fluid natural to each ; and let procefs of deducing the nature of the curve from the 
 
 F' and/' be the redundancy in N and n, and M' and m' phenomena now under coniideration. 
 
 the deficiency in S and j. Moreover, let Z and Z re- 
 prefent the intenfuy gf aftions of a particle in N on a 
 particle in h and j- ; and let z and z', reprefent the ac- 
 tions of a particle In S on a particle in n and in s ; or, 
 in other words, let Z, Z', 2, c', reprefent the intenfity 
 of adion between particle and particle, correfponding 
 to the diftances N /, N n, S j, S n. 
 
 Proceeding in the fame manner as in the former ex- 
 amples, \\e eafily fee, that the adion of B on A is = 
 F' p,' Z — F/' Z' — M' m' z -J- Mf z ' 
 
 4< 
 
 F/ 
 
 the attrac- 
 
 tions are confidered as pofitive quantities, having the 
 fign + prefixed to them, and the repuhions are nega- 
 tive, having the fign — 
 
 This action will be either attraftlve or repulfive, ac- 
 cording as the fum of the firft and laft terms of the nu- 
 merator exceeds or falls (hort of the fum of the fecond 
 and third : And the value of each term will be greater 
 or lefs, according to the quantity of redundant fluid and 
 matter, and alfo according to the intenfity of the elec 
 
 This conihntiion evidently makes the pair of ordi-Ger.eral 
 nates P />, Q^j, equidilldUt with the pair R r, T //J""^ 
 Alfo, P f>, Rr, andQ_9, T t, are equidiftant pairs, ^^oftlearie 
 is no lefs clear, that tlie fum of P /i and T / cxceedsforce. 
 the fum of Q^g and R r. For if C z be bifcfted in V, 
 and V V be drawn perpendicular to it, cutting the 
 flraight lines PT and Q^ in x and y, then x -u is 
 the half fum of P p and T /, and _y ii is the half fum 
 of Q^q and R r. Moreover, if Q_m and T n are 
 drawn parallel to the bafe, we fee that P m exceeds 
 R r ; and, in general, that if any pair of equiftant or- 
 dinates aie brought nearer to C, their difference increa- 
 fes, and vi/:e •verfa. Alfo, if two pairs of equidiftant 
 ordinatcs be brought nearer to C, each pair by the 
 fame quantity, the difference of the neaicft pair will in- 
 creafe more than the difference of the more remote 
 pair. And this will hold true, although the firft of the 
 remote pair (hould ftand between the two ordinates of 
 the firft pair. If the reader will take the trouble of 
 confidering thefe fimple confequences with a little at- 
 
 tric aaion. It would require feveral pages to ftate all tention, he will have a notion of all the effeds that are 
 
 ' ' ' to be expedtcd in the mutual aftions of the two bodies, 
 
 fufficiently precife for our prefent purpofe. We fhall 
 give a much more accurate account of thefe mathema- 
 tical truths in treating the article Magnetism, where 
 precifion is abfolutely neccflary, and where it will be 
 attended with the greateft fuccefs in the explanation of 
 
 thofe poflible varieties. We Ihall therefore content 
 ourfelves at prefent with ftating the fimplcft cafe ; be- 
 c.iufe a clear conception of this will enable the reader 
 to form a pretty diftlnft notion of the other poflible 
 cafes ; and alfo, becaufe this cafe is very frequent, and 
 is the moft ufcful for the explanation of phenomena. 
 
 We (hall fuppofe, that the redundant part of each phenomena 
 
 Ufeful re- 
 preCenta- 
 tion of the 
 rnutual 
 forces by 
 ordinate^ 
 to a curve. 
 
 body Is juft as much overcharged as the deficient part 
 is undercharged ; fo that F = M', and/' = m. In this 
 
 F'/' ( Z— Z' — z-f z- 
 cafe, the formula becomes ^-7 
 
 Here we fee that the fenfible or external effect on 
 A depends entirely on the law of eleftric aftlon, or the 
 variation of its intenfity by a change of <iiftance. If 
 the fum of Z and ri' exceed the fum of Z' and z, A 
 will be attraCled ; but if Z -t- z' be lefs than Z' -1- z, 
 A will be repelled. This circumftante fuggefts to us a 
 very perfpieuous method of exprefling thefe aftions be- 
 tween particle and particle, fo that the Imagination 
 fnall have a ready conception of the circumftance vyhich 
 determines the external complicated effeft of this mier- 
 nal atftion. This will be obtained by meafuring off 
 from a fixed point of a ftralght line portions refpedtive- 
 ly equal to the diftances N x, N n, S j, and S n, between 
 
 46, 
 
 47. 
 
 48. 
 
 Now let us apply this to our prefent purpofe. FirJ}, 
 then. When the overcharged end of A is turned to. 
 ward the undercharged end of B, A mull be attraiSled; 
 for P ;> -f- T / is greater than Q_y -f- R r. 
 
 Scooniily, This attraftion niuft Increafe by bringing 
 the bodies nearer; for this will increafe the difference 
 between P m and R n. 
 
 Thirdly, The attradllon will increafe by increafing 
 the length either of A or of B (the diftance N s re- 
 maining the fame) ; for by Increafing the length of A, 
 which is reprefented by ^r or j /, R r is more diminiih- 
 ed than T t is. In like manner, by increafing B, whofc 
 length Is reprefented hy J> g or r t, we diminifti Q_y 
 more than T /. 
 
 On the other hand, if the overcharged end of B front Ufe of this 
 
 the overcharged end of A, their mutual aftlon will beP'*^"''"'^ 
 
 F/ ( -Pp + Q^g + Rr-T,), '^" ^°'"'- 
 
 ¥/ 
 
 49 
 
 the points of the two bodies A and B, where we fup 
 
 pofe the forces of the redundant fluid and redundant and A will be repelled, and the repulfion will increafe 
 
 matter to be concentrated, and eredl ordinates having or diminifti, by change of diftance or magnitude, pre 
 
 the proportion of thofe forces. If the law of aftion be 
 known, even though very Imperfefkly, we ftiall fee, 
 with one glance, of which kind the movements or ten- 
 dencies of the bodies will be. Thus, In fig. 5. draw- 
 ing the line C z, take C/> = Nj, Cj = Nn, Cr=Sj, 
 and C / = S «, and erecEl the ordinates P f, Q^, R r, 
 and T t. If the eleftric aftion be like all the other 
 attraftlons and repulfions which we are famlHarly ac- 
 quainted with, decreafing with an increafe of difbnce, 
 and decreafing more (lowly as the diftances are greater, 
 thefe ordinates will be bounded by a curve PQR TZ, 
 which has its convexity turned toward the axis. We 
 
 cifcly in the fame manner that the attractions did. It 
 is hardly neceffary to obferve, that all thefe confe- 
 quences will refult equally from bringing an apparatus 
 fimilar to that reprefented in fig. 3. near to another of 
 the fame kind ; and that they will be various according 
 to the pofition and the redundancy or deficiency of the 
 
 two parts of each apparatus. , 
 
 Tr , ■ ■ r. r ■ ,•. . phenomeM 
 
 li the body B of lig. 5. is not at liberty to approach „,j,jj.|, 
 
 toward A, nor to recede from it, and can only turnftiould re- 
 round its centre B, it will arrange itfelf in a certain f"lf fro"" 
 determinate pofition with refpeft to that of A. F°'' '{'.ecl'^r^ 
 example, if the centre B (fig. 7.) be placed in the linej^^nbliog ' 
 
 pai&ng magDetifis 
 
 50 
 Curious
 
 ELECTRICITY. 
 
 raffing through S and Nof the body A, B will arrange trafts the redundant fluid in A more than the more re. 
 
 itfclf in the fame ftraight line : for if we forcibly give mote redundant fluid in n repels it, bccaufe r.' is lefs 
 
 it another poiition, fuch as j B //, N will attract s and than z. This tends to conftipate the redundant fluid 
 
 repel n, and thefe aftions will concur in putting B into of A in the nearer parts, and render N more rcdun. 
 
 the poiition s' B n'. S, however, will repel s and at- dant, and S lefs redundant in fluid th,in before. It is 
 
 traft It ; and thefe forces tend to give the contrary po- plain that this muil iucreafe their mutual adtion, with- 
 
 fition. But S being more remote than N, the former out changing its nature. It can be llridly demonilra- 
 
 forces will prevail, and B will take the poiition s' B «'. ted, that however fmall the redundanry in A may be. 
 
 If the centre B be placed fomewhere on the line it can never be rendered deficient in its remote extre- 
 
 AD, drawn through a certain point of the body NAS mity by the aftion of the unequally difpofed fluid in B, 
 
 (which will be determined afterwards), at right angles if the fluid in B be no more nor lefs than its natural 
 
 to NAS, the body B will alTume the pofition n' B j', quantity. It is alfo plain that this change in the dif- 
 
 567 
 
 parallel to NAS, but fubcontrary. For if we forcibly 
 give it any other pofition n Id s, it is plain that N re- 
 pels n and attrafts j, while S attrafts tt and repels s. 
 Thefe four forces evidently combine to turn the body 
 round its centre, and cannot balance each other till B 
 aflume the pofition n' B j', where n' is next to S, and 
 j' is next to N. 
 I rm of If the centre of B have any other fituation, fuch as 
 
 jielefiricB', the body will arrange itfelf in fome fuch poiition 
 
 51 
 
 nfe- 
 
 ence 
 tnda- 
 
 pofition of the fluid in A muft increafc the fimilar 
 ciiange in B. It will be Hill more rarefied in /, and 
 condenfed in n ; and this will go on in both till all 
 is in equilibrio. When things are in this Hate, a par- 
 ticle ot fluid in B is in eqtillibrio by the combined ac- 
 tion of feveral forces. The particle B is propelled to- 
 ward n by the adtion of the redundant fluid in A. But 
 it is urged toward S by the repulfion of the redundant 
 fluid on the fide of n, and alfo by the attradlion of the 
 as n' B' s'. It may be demonitrated, that if B be infi- redundant matter on the fide of j ; and the repulfion of 
 nitely fmall, fo that the aftion of the end of A on each the redundant fluid in A mull be conceived as balan- 
 of its extremities may be confidered as equal, B will cing the united adlion of thoie two forces refiding in B. S3 
 
 arrange itfelf in the tangent BT of a curve NB'S, Hence we may conclude, that the denfity of the fluid '^''""^''". 
 
 fuch that if we draw NB, SB, and from any point T in B will increale gradually from s to n. It will be ex- th^ ff,rj(.j 
 of the tangent draw TE parallel to BN, and TF pa- tremely difficult to obtain any more precife idea of itsdilpofitiou 
 rallel to B'S, we fliall have BE to BF, as the force of denfity in the different parts of B, even although w^oi t]cS.nc 
 S to the force of N. This arrangement of B will be knew the law of aclion between fingle particles. fiuul in a 
 
 ftill more remarkable and dillinft if N be an over- This inurt depend very much on the form and dinien- 
 
 charged fphere, and S an undercharged one, and both fions of B; for any individual particle fuflains tlie fcnfible 
 be infulated. We muft leave it to the reader's reflec- aftion of all the redundant fluid and redundant matter in 
 tion to fee the changes which will arife from the ine- it, fincc we fuppofe it affefted by the more remote fluid in 
 quality of the redundancy and deficiency in A or B, or A. .A.11 that we can fay of it in general is, that the den- 
 both, and proceed to confider the confequences of the fity in the vicinity of x is lefs than the natural denfity ; 
 mobility, of the elcftric fluid. Thefe will rertlove all the but in the vicinity of « it is greater; and therefore there 
 difficulty and paradox that appears in fome of the fore- mufl be fome point between s and n where the fluid will 
 going propofitions. have its natural denfity. This point may be called a Neutral 
 
 Let the body A (fig. 4.) contain redundant fluid, neutral point. We do not mean by tiiis that a par-i'°int- 
 
 tide of fuperficial fluid will neither be attraft.ed nor re- 
 pelled in this place. This will not always be the cafe 
 (although it will never be greatly otiierwife}-, nor will 
 
 and let B be in its natural Hate, but let the fluid in A 
 
 ntal) of be fixed, and that in B pertcftly moveable ; it is evident 
 
 : nioliili. that the redundant fluid in A will repel the moveable 
 
 of the fluid in B, toward its remote extremity n, and leave it the variation of the denfity in the different partsof B be 
 la in the J 1 , ■ - - - - - - - 
 
 undercharged 111 
 
 res uf bo 
 
 The fluid will be rarefied in s, proportional to the force of A on thofe parts. Some 
 and conftipated in n. We need only confider the nui- eminent naturalifts have been of this opinion ; and, ha-' 
 tnal aftions of the redundant fluid and redundant mat- ving made experiments in which it appeared to be other- 
 ter. It is plain that things are now in the fituation wife, they have rcjcfted the whole theory. But a little 
 defcvibed in n" 15. : A mufl be attrafted by B, becaufe refleftion will convince the mathematician, that the fuin 
 f zr fli', and 2 is greater than z'. The attraftive of the internal forces which tend to urge a particle of 
 force is Y' f' X (z — z'). fluid from its place, and which, are balanced by the ac- 
 diescon- Thus we fee that the hypothefis is accommodated to tion of A, are not proportional to the variations of den- 
 ning the the phenomena in the cafe in which it appeared to differ fity, although they increafc and decreafe togetiier. We 
 ""^ . fo widely from it. Had the fluid been immoveable, fhall take the proper opportunity of explaining thofe 
 natural '^^ "^"''■'^' '"^'°"s "'"'^^'^ '^•'■'^ fo balanced each other experiments; and will alfo confider fome fimple, but 
 ;e, at- that no external effedts would have appeared. But now important cafes, where we think the law of diflribulion 
 a and the greater vicinity of the redundant matter prevails, A- of the fluid afcertained with tolerable preciiion. 
 
 attrail • 
 
 B» 
 
 , J is attrafted by B, and, the afrions being all mutual, 
 1 ied bo- '^ attrafted by A, and approaches it. 
 I >, We have fuppofed that the fluid in A Is immoveable ; 
 
 is* but this was for the fake of greater fimplicity. Sup- 
 i i{j,^"o/ P"^'^ '' moveable.. Then, as foon as the uniform diflri- 
 
 fj to bution ot the fluid in B is changed, and B becomes un 
 
 If we fuppofe, on the other iiand, that A is under, 
 charged, the redundant matter in A will altraft the 
 moveable fluid in B, and will abftraft It from the re- 
 mote extremity, and crowd it into the adjacent extre- 
 mity. Moreover, the fluid novv^ becoming redundant 
 in the nearer extremity of B, will adt more llrongly on 
 
 1 i, whiihdercharged at s, and overcharged at n, there are forces- the moveable fluid in A than the more remote redundan 
 
 I '"fes afting on the fluid in A, and tending to change its- m.itter of B ; and thus fluid will be propelled toward' 
 
 I '•lun- jJate of diftribution. The redundant matter in S at- the remote fide of A, which will become now under-' 
 
 sharped.:
 
 568 ELECTRICITY. 
 
 charged in its neater fidu, anJ lefu undercharged in Ita n C, and NB attradls iC ; and on this account the bo- 
 remote iide than if B were taken away. This muft in- dies tliould approach : but the ciilances of the attrad- 
 creafe the inequabih'ty of dllhibmijn of the fluid in B, ing parts being greater than thofe of the repelling parts, 
 and both will be put farther from their natural (late ; the repulfions mull prevail, and the bodies mult really 
 but A will never become overcharged in its remote ex- feparate. 
 
 tiemity. It is equally clear that the very fame fenjil'te appear. 
 Tilings being In this (late, it Is plain that A and B ance will refiilt from briiiging an undercliaigcd body- 
 will mutually attrail each other in the fame manner, near the ends of B and C, although the internal motions 
 and witli the fame force, as when A was as much over- are jull the oppolite to the former. 
 
 54 
 Eledlric at- 
 mofphere is 
 not ade- 
 quate t . the 
 expiana- 
 tion of tie 
 pheuome- 
 
 charged as It is now undercharged. 
 
 Thus, then, we fee liow the attraftlon obtains, whe- 
 ther A be over or undercharged. A fa£l which Dr 
 Franklin could never explain to his own fatislaftion ; 
 nor will it ever be explained confiftently with the ac- 
 knowledged principles and obferved laws of mechanics 
 by any perfon who employs elallic atmofpheres for this 
 purpole. It is indeed a fuificlent objedlion to the em- 
 
 . 55 
 
 Induced 
 
 eleiftricity. 
 
 If another body D, clcClnfied In the fame way with 
 A, be brought near the oppofite ends of B and C, it 
 will pre\eiit or diniliiifh the internal motions, and it 
 fliould therefore prevent or dinunll]; the external efftdls. 
 If another conduifting body be brought near to the 
 end J of C that fronts A, it will be affefted as C is, 
 and the end f will repel s ; but if it be brought near 
 the remote end, as is the cafe with the body F, it will 
 plovment of fueh eleftric or othtr atmofpheres, that attraft this remote end. As the body A, containing 
 the fame extent of attraillon and repulfion between the more or lefs than its natural (have of elcftric fluid, af- 
 partlcles of the atmofphere is neceffary, as is employed fefts every other body, while they do not (when out of 
 here betveeen the particles of the fluid reliding in the its neighbourhood) a(fet1 each other, it is ufually faid 
 body; and therefore they ceafe to give any explanation, to be the eledlriiied body, and the others are faid to be 
 even although their fuppofed aClions were legitimately eledlriiied by It ; and lince thefe bodies, when perfeft 
 deduced from their conllitution. This is by no means conduftors, cannot retain their power of exhibiting clec- 
 the cafe. Let any perfon examine ftrioufly the vwJus trical appearances (fee n^ 17.), it will be convenient to 
 operandi of the eletftrlc atmofpheres employed by Lord dlftingullh this luft eledrical (late by a particular name. 
 Mahon (the only perfon who has written mathema- We Ihall call it electricity by position, or indu- 
 tically on the fubjctl^ and he will fee that the whole CED ELECTRicirv. It is induced by pofitlon with re- 
 is nothing but figurative language, without any dif- gard to the permanently eleftrical body. - 
 tinft perception of what is meant by thele atmofpheres. We have fuppofed, in thefe lail propofitions, that Confcqut 
 as dilliiift from the fluid moveable In the conducting the fluid was perfedlly moveable In B, and, at lall, alfo,cesofob 
 bodies, or any perception how the unequal denfity of in A : but let us examine the confequences of fome ob-'^r"'3'<"" 
 thefe atmofpheres protrudes the fluid along ihe con- llrutllon to this motion. Without entering into a mi- 
 dudor. Bcfides, it Is well known that a condufiing nute enquiry on this head, we may ftate the obflruftion 
 wire becomes pofitlve at one end, and negative at the as uniform, and fuch that a certain Iniall force is ne- 
 other, by the mere vicinity of an overcharged or under- cefl"ary for caufing a particle of fluid to get through be- 
 charged body, and this in an inilant, although it be tween two paitielcs of the common matter, jull as we 
 furrounded with fealing-wax, or other non-condudors,to conceive to happen In tenacious bodies of uniform tex- 
 anv thicknefs : in this cafe there can be no atmofpheres ture (fee 11° iS.). 
 
 to'operate on the included fluid. To this we may add It is evident, that when an overcharged body A (fig. 
 Dr Franklin's judicious experiment of whirling an elec- 4. or j.) is brought near fueh an imperfcft conduftor 
 trifled ball many times round his head, with great ra- B, the fluid cannot be fo coploufly propelled to the re- 
 pldity, by means of a filk line, without any fenfible di- mote extremity n. We m.ay conceive the Hate of dif- 
 minution of its eleftrlclty. It Is not conceivable that tribution by taking a conilant quantity from the inten- 
 an eleftrlc atmofphere could remain attached to the fities of the force of A at every point of B. This clr- 
 ball • nor could it be inftantaneoufly formed round the cumllance alone fliews us that there will not be fo 
 ball, In every point of its motion, fo as to be operative unequable a diftribution of the fluid, and therefore 
 the moment he (lopped It and tried it ; for this would there •will not be fuch a jlrong attradhn letixieen imperfea 
 have exhaulled or greatly diminllhed the eleftricity of as between perfect couduaors. But befides this, we fee 
 the ball) ; whereas that fagaclous philufopher affirms that an Incomparably longer time muft elapfe before 
 (and any perfon will find it true), that when the air is things come to a (late of equilibrium. Eacii particle 
 dry, he did not obferve the cledilclty more dimlnlflied of fluid employs time to ovcrcnme the obdacle to Its 
 than that of another ball which remained all the whIU motion, and it cannot advance till .^fter the fucceed- 
 in the fame place. ing ones, each efcaping in its turn, have again come 
 Let the overcharged body A (fig. 6.) be brought up with the foremoll. An Important confequence re- 
 near the ends of two oblong condutlors B and C in fults from this. The neutral point, where the fluid is 
 their natural (late, and lying parallel to each other ; the of the natural denfity, will not be fo far from the 
 fluid will be propelled toward their remote ends N, n, other body as it would have been without thefe ob- 
 where it will be condenfed, while it will be rarefied in llrudlions ; and this point will be a conliderable while 
 the ends S and s, adjacent to A. Both will be at- of advancing along the Imperfeft conduftor. At the 
 traded by A, and will attradl it. But the redundant fir(l approach of the overcharged eledric, the near 
 fluid in NB will repel the redundant fluid In n C ; and extremity of the imperfeft condudor becomes a little 
 the redundant matter in SB will repel the redundant undercharged, and the neutral point advances from the 
 matter in j C. For this reafon the bodies B and C very extremity a fmall way, the difplaced fluid being 
 will repel each other, and will feparate; but SB attrads crowded a little before it, and giving way by degrees
 
 ELECTRICITY. 569 
 
 as its foixrroft pavtu-les get paft the obftniflions. Tlie at one dillanctf, repelKd when this diftance is I'ncreafed, 
 
 niotion forward tiikes place over a conliderablc extent aud again altrac'ltd when at a llill greater dillaiice, &c. 
 
 at the very tirft ; nnmcly, in that part of the condiiaor &c.^ 
 
 where the propelhiig power of the neighbouring ekdric Suppofe the obftruaion not to be confiderable: The 
 is iuft able to pu(h a particle over the obllniaion. As immediate operation of the neighbouring overcharged 
 the propuHion goes on, the neutral point inuft gra- body will be the produr.tion ot an undercharged pai t :n 
 dually advance, and at laft reach a certain diltance, de- the adjoining extremity, an overciiarged part beyond 
 termined by the degree of the obflrudion. It is plain, this, an undtrtharg d portion farthi;r on, &c. In a 
 that the final accumulation at the remote end of the httle while tlicli: will fhitt along the conductor; (\ne af- 
 imperfed condudor will be hfs than in a perftd con- ter another will difuppcar at the farther end, and the 
 dudor, and the neutral point will be nearer to the other body will have at lail but one neutral point. A greater 
 gjjjj > obltruction will leave the body, finally, with more than 
 There is another remarkable confequence of the ob- one neutral point, and their ultimate number will bt- 
 ftrudion. It mud always happen tliat, at the beginning greater in proportion as the obllruition to the lluid'a 
 of the action, the grealcR eonlllpation will not be to- motion is fuppoied greater. ^j 
 wards the rcincte extremity, but in a place much nearer Now, let the overchaiged body, the caufe of this un- induced e- 
 to the difturbing caufe. Bevond this, the conitipatiou equal dillribution, be remuved. We have feen, n" 17. Icilricity, 
 viU dimiiiifli. As time elapfis during this operation, tliat when a body contains its natural quantity "^ fl>''d, 7J^j|^"-^',';ert 
 this conftipated fluid ads on the fluid beyond it by re- but unequally dillributed, there is a force acting on''" 
 puUion, and may do this with fufficicnt force to dif- every particle, and tending to rellore the original eqna- 
 place fome of it, and render a part of the imperfedt ble dillribution ; and that inch a force rem.nms as- lung 
 conduftor deficient, with a fmall conftipation beyond as there is any inequality in this refpeCt. If, therefore. 
 it. This may, in like manner, produce a rarefa. lion there be no»obllruction, the uniform diRributiou will 
 farther on, followed by another condeiifation ; and this take place immediately ; for it is well known, thit the 
 may be frequently repeated when the obftruAion is very fpeed with which electricity is propagated is immenfe. 
 great, and the repullion of the overcharged body very The elafl;icity, or the attrattive and repullive forces, 
 great alfo. This can be ftrialy demonftrated in' fome mull be very great indeed when compared with any 
 very iimple cafes, but the demonllration is very tedious: that we know, except, perhaps, the force which impels 
 As'the refult, however, is of the firft importance in the the particles of light. The tlearicity, therefore, of a 
 theory of eltdricity, and ferves to explain fome of the perfeft condudor, that is, its power of ading on other 
 moil abftrufe phenomena, we wiih the reader to have bodies in the fame way that an original elettiic ads on 
 fome llionger ground of confidence than the above bare thern, muft be quite momentary, and ceafe as foon as 
 alfertion. He may obferve fimilar effeds of caufcs pre- the inducing cauie is removed. The conductor is elec- 
 cifcly fimilar. If we dip the end of a flat ruler into trical merely in confequence of its pofition. Hence 
 water, and if, after allowing the water to become per- the propriety of our denominations. Nothing materia 
 fealy ftill, we move the ruler gently along in a direc- is fuppofed in this theory to be communicated from tlie 
 tion perpendicular to the face, we fliall obferve a fingle overcharged body : Nay, this theory teaches, that the 
 wave heap up before the ruler, and keep before it, all feniible ele.-lricity of the overcharged body is augment- 
 the rell of the water before it remaining llill : but if ed in fome rcfpctts ; for it becomes more overcharged 
 we do the fame thing in a veffel of clammy fluid, efpe- in the part neareft to the condudor. Indeed it bc- 
 cially if the clammy part is fwimming on the fntface of comes lefs overcharged on the other end, and will act 
 a more perfeft fluid, like a cream, we (hall obferve a fe- lefs forcibly on that fule than if the conductor were a- 
 ries of fuch waves to curl up before the ruler, and form way. It may be remarked here (It Ihould have beer, 
 before it in fucceflion ; and if we have previoufly fputted mentioned in n*^ 5 .) that when F is prefented in the 
 the furface of the cream, we (hall fee that it is not the manner (hewn in fig. 6. the body B becomes more 
 fame individual waves that are puflied before the ruler, llrongly overcharged at the end remote from A, and 
 but that they are fuccefiively formed out of different more llrongly undercharged at the end next to A, than 
 parts of the furface, and that the particles which, at when F is away. The contrary may happen, by pie- 
 one time, form the fummit of a wave, are, immediately fcnting a body in the manner of E. We wi(h thefe 
 after, at the bottom, &c. In like manner, when a can- particulars to be kept hi mind. In the mean time, ail 
 lion is fired in clear air, at no great dillance, we hear a thefe circumltances are neceflary confequences of the 
 fingle fnap ; but, in a thick fog, we hear the fnap both fuppofition, that nothing is communicated from A to 
 preceded and followed by a quivering noife, refembling B or C. The eleftricity induced on perfect conduc- 
 the ruiliing of a fluttering wind, which lafts perhaps tors is momentary, requiring the continual pretence of 
 half a fecond. A flight refledion on thefe farts will fliew a body that is eledrified in fome way or other. 
 that they are necefi'ary refults of the mechanical laws of But the cafe is quite otherwife in imperfcd conduc- 
 fuch obllruetion. tors. When the overcharged, or otherwife eledrical 
 The confequence of this mode of adion muft be, body A is removed, the forces which tend to rcftore 
 that an imperfed condudor may have more than one the uniform dillribution of the fluid immediately ope- 
 reutral point, and more than one overcharged and rate, and mull refl;ore it in part. They cannot, how- 
 undercharged portion, fo that its adion on diftant bo- ever, do it completely : For when the force which ur- 
 dies may be extremely various. The formula of n° 28. ges any particle from an overcharged to an underchar- 
 was accommodated to this cafe, and will be found to ged part, is juft in equilibrio with the obllrudion, it 
 have very curious refults. Another body may be pla- will remain, jull as a number of grains of fmall Ihot may 
 ced in the diredion of the axis, and will be attraded lie, uniformly mixed with a mafs of clammy fluid, or, 
 Sup?L. Vol.. I. Part II. 4 C as
 
 570 
 
 59 
 imperfeiSl; 
 conduijtois 
 arc receiTa. 
 lily idio- 
 cleci^rics. 
 
 ELECT 
 
 as fi:cli fliiiils retain heavy mud, in a ftate of equable 
 or juequablc diffiilion. If the refinance arife merely 
 from the inertia of the tar.gible matter, there is no force 
 fo fmall but it will in time reftore the uniform diHri- 
 bution. But this cannot be the cafe in folid bodies. 
 Their particles exert lateral forces, by which they main- 
 tain themfelves in particular lituations : thefe mull be 
 overcome hy fiiperior forces. 
 
 We fhouid therefore expeft, that imperfeft conduc- 
 tors will retain part of their inequable conftitution ; 
 and, In confequence of this, their power of affefting other 
 bodies like eledtrics ; that is, their Elictricitv. 
 For we muft obferve (having neglected to do it in the 
 beginning), that the term ekBrkity is as oftsn uftd to 
 exprel's this power of producing cleArical phenomena 
 as it is ufed for expreffing a fubftance fuppofed to be 
 the original caufe of all thefe appearances. It is necef- 
 fary to keep this dillinflion in mind ; becaufe there are 
 many phenomena which clearly indicate the transfe- 
 rence of this caufe, and they muft not be confound- 
 ed with otiiers, where the exhibition of eleftric pheno- 
 mena is evidently propagated to a diftance. We muft 
 pot always fuppofe, that when the eledtric appearances 
 are exhibited in an inftant at the far end of a wire 
 4t miles long, the fame numerical particles of the elec- 
 tric fluid have moved over this fpace. We muft diftin- 
 guifh thofe cafes where this muft be granted from thole 
 in which it certainly has not happened. Of thefe there 
 are innumerable inltances. 
 
 We have now to obferve, that by this theory the 
 fingle circumftance of perfeft and impcrfeft conducing 
 power is fufficient for eftablilhing the whole difference 
 between idio-eleftrics and non-eleftrics. The idio- 
 eleftrics are fufceptible of excitation in various ways, 
 and retain their eleftricity ; and this may be done in 
 any part of them without affefting the reft in any re- 
 markable degree. This annot be done in perfeft con- 
 duftors, plainly becaufe they are perfeS conduSors. Any 
 inequality of diftribution of the eleftric fluid, which is 
 all that is neceflary for rendering them eledric, is im- 
 mediately deftroyed by its uniform diffiilion. We can 
 have no direiSt proof of their incapability of excitation ; 
 but if they can be excited, they cannot fhew it. We 
 doubt, however, their excitability ; becaufe the appear- 
 ances in the excitation of eleftrics feem to indicate, that 
 oppoiite ftates of two bodies are neceffary previous to 
 the appearance of eletlricity. This is impofTible in per- 
 feft conduftors. By this theory, therefore, perfeft 
 conduftors are necefTarily non-eleftrics ; and non-con- 
 duftors are necefTarily (if excitable) idio-cleftrics. 
 
 With refpeft to the particular phenomena which may 
 be expefted on the removal of the original eleftric ; it 
 may jnft be remarked, that the eleftric appearances of 
 the imperfeft eonduftor will go off in the contrary or- 
 der to that of their indication. The accumulation and 
 deficiency will diminifh gradually, and the neutral point 
 or points will gradually approach the end which had 
 fronted the original eleftric. The imperfeft eonduftor 
 will be finally left with one or more neutral points, ac- 
 cording to the magnitude of the obftruftions, and the 
 force which had been employed in its eledrification : 
 And their final ftate will be fo much the more inequa- 
 ble, and confequently they will retain fo much the 
 greater eleftric powers, as they are lefs perfeft conduc- 
 tors. 
 
 R I G I T Y. 
 
 The laft obfervation which we fhall make on this 
 head at prelent is, that whether eleitrified by induc- 
 tion, or by friftion, or moft other modes of excitation, 
 the eleftrification will be nearly fuperficial in bodies 
 which conduft very imperfeftly ; and bodies which are 
 altogether impervious (if there be any fuch) muft have 
 the accumulation or deficiency altogether at their fur- 
 face. If a glafs globe be fuch a body, it will hardly be 
 poffible to tleftrify it to any depth; and all that we can 
 expeft is alternate ftrata of overcharged and underchar- 
 ged glafs. If thefe ftrata are once formed, they tendgreat- 
 ly to make the body retain its fuperficial eleftricity. A 
 fuperficial ftratum of redundant fluid, tending, by the 
 mutual repulfion of its particles, to efcape, is retained by 
 the ftratum of redundant matter immediately below it •- 
 And the almoft infuperable obftruftion prevents the 
 fluid of the ftratum beyond this from coming up to fup- 
 ply the vacancy. If we can fall on any contrivance to 
 produce fuch deficient ftrata within the glafs, we fhall 
 make it much more retentive and capable of holding 
 faft a much greater quantity. We have already men- 
 tioned fomething of this in n° 14. and we recommend 
 the cafe to the attentive confideration of the reader. 
 
 Thus have we given a fl<etch of the leading doftrlnes 
 of this elegant theory of Mr iEpinus, all legitimately 
 deduced from the circumftances afTumed in the hypo- 
 thefis concerning the mechanical properties of that fub- 
 ftance which he calls the eleBric Jlu'id. Let us now fee 
 with what fuccefs this hypothefis may be applied to ac- 
 count for the phenomena. It would have been more 
 philolophical to have arranged the phenomena, and 
 from the comparifon to have deduced the hypothefis. 
 But this would have required much more room than 
 caii be afforded in a Work like ours. 
 
 We prefume, that many of our readers, namely, all 
 fuch as aie already converfant with eleftrical phenome- 
 na and with eleftric experiments, have feen, as we went 
 along, the perfeft agreement of the hypothefis with the 
 various phenomena of attraftion and repulfion, and all 
 thofe which are ufually claffed under the name of elec- 
 tric atmoipheres : and we are confident, that when they 
 compare the confequences that fhouid neceffarily refult 
 from fuch a fluid with the legitimate confequences of 
 the mechanical aftion of elaftic atmofpheres, they will 
 acknowledge the great fupcriority of this hypothefis in 
 point of fimplicity, perfpicuity, and analogy with o- 
 ther general operations of nature. To fuch readers it 
 would not be neceifary to ftate any farther comparifon ;. 
 but there are many who have not yet formed any dif- 
 x'\aQ. fyfleviat'ic view of the appearances called eleHrical. 
 We do not know any way of giving fuch a view of 
 them as by means of this hypothefis ; and we may ven- 
 ture to fay, that it will enable the ftudent of Nature to 
 clafs them all, with hardly a fingle exception. After 
 which, the hypothefis may be thrown afide by the faf- 
 tidious philofopher ; and the ufeful clafiification, and ge- 
 neral laws of the eleftric phenomena, will remain ready 
 foundations for a more perfeft theory. For the fake 
 of fuch readers, therefore, we fhall take a fhort reviev^ 
 of thofe general appearances which are accompanied by 
 attradions and repulfions, and compare them with this 
 .^pinian theory. 
 
 We fhall not at prefent confider the various modes of 
 excitation,, although this theory alfo affords much in- 
 
 ftruftion 
 
 ho 
 tlc(aric» 
 are only 
 fuperfici- 
 ally fo. 
 
 6f 
 
 Compari- 
 fon of the 1 
 theory wicb J 
 experi- I 
 
 ment. ' 
 
 \
 
 ELECTRICITY. 
 
 ftruftion on the fubjcfl, but confine ourfclves entirely 
 to tlie facts which are moll immediately dependent on 
 it, and (hould be employed to fupport or overturn it ; 
 and we (hall fuppofc the reader aequainted with moil 
 parts of the common apparatus ; fuch as eleftrometers, 
 iijfulation, Sec. We alio prefumc that he knows, that 
 when a fmall pith-ball has been eleCtrilied by touch- 
 ing a piece of glafs whicii has been excited by rubbing 
 with dry flannel, it will repel another body fo eleftrifi- 
 ed ; and that balls, which have received their eiedlricity 
 in this manner from fealing-wax excited by the fame 
 rubber, alfo repel each other ; but that balls, thus elec- 
 trified by glafs, attraft thofc which are eleftritied by 
 fealing-wax. 
 
 The following fimple apparatus wljl ferve for all the 
 experiments which are ueceffary for eflabliihing the the- 
 ory : 
 
 1. Two flender glafs rods A (fig. 8.), having a 
 brafs ball B at the end, about a quarter of an inch in 
 diameter, fufpending a very fmall and delicate pith-ball 
 eleftromcter C. 
 
 2. Some eleftrometers (fig. 9.), confiding of two 
 pieces of ru(h pith, about four inches long, nicely fuf- 
 pcnded, and hanging parallel, and almoft in contadt 
 with each other. It is proper to have them as fmooth as 
 pofTible, and neatly rounded at the ends, to prevent un- 
 neceflary difiipation. 
 
 3. Some pith-ball eleftrometers (fig. 10.), whofe 
 threads are of fillc, about four inches long, and fome 
 with flaxen threads moillened with a folution of fome 
 dcliquefcent fait, that they may be always in a good 
 conducing (late. 
 
 4. Several brafs conduftors (fig. 11.), each fupported 
 on an infulating flalk and foot. They (hould be about 
 an inch and half or two inches long, and about three- 
 fourths of an inch in diameter, with round ends, and 
 well polilhed, to prevent all diffipation. The foot mud 
 be fo narrow as to allow them to touch each other at 
 the ends. 
 
 5. Two balls (fig. 12.^, one of glafs, and the other 
 of glafs coated with fealing-wax, each furnilhed with 
 an infulating handle, the other end of which may be 
 occafionally lluck into a foot, or into the fide of a 
 block of wood, which can be Aid up or down on a 
 wooden pillar, and fixed at any height. Thefe balls 
 fliould be about three inches in diameter. They muft 
 be excited by rubbing with dry warm flannel. 
 
 6. Some little pieces of gilt card (fig. 13.), about 
 two inches long, half an inch broad, and rounded at the 
 ends, and made as fmooth as poflible. Each muft have 
 a dimple ftruck in the middle with a poliflied blunt 
 point, fo that it will traverfe freely like a mariner's 
 needle when fet on a glafs point, rounded in the flame 
 of a lamp. More artilicial needles may be made of fome 
 light wood, having fmall cork balls at the ends, all gilt 
 and poliflied, and turning, in like manner, on glafs 
 ftalks : alfo ionie fimilar needles made of fealing-wax, 
 one end of each being black, and the other red. 
 
 The mechanical phenomena of eledlricity may be ex- 
 prefled in a few fimple propofitions. The moft general 
 faft that we know, and from which all the refl; may be 
 deduced, is the following : 
 
 If any body A is eleftrified, by any means whatever, 
 and if another body B is brought into its neighbour- 
 hood, the laft becomes eleftrical by pofitioii. 
 
 571 
 
 Set the brafs condu<Elor3 in a row, touching each 6- 
 other, as reprcfented in fig. 11. by A, B, C; and lei a -^ ^'^"^"'''' 
 pith-ball electrometer, having filk threads, be fet nezr ^'.'^'g^^- i,j. 
 one end of the condudlors. Excite one of the globes, caufe rtn 
 by rubbing it with dry flannel. When this is brought dcrcd dec. 
 near the end of the condudlor, tlie pith-ball will ap- ""' -^j*' ''' '"' 
 proach the other end. But the globe mull not be "'^ '""' 
 brought fo near as to caul'e the pith-ball to ftvike a- 
 gainll the other end. On removing the globe, the pitli- 
 ball will move oflF and hang perpendicularly. The fame 
 effeft is produced by both globes. ' 
 
 Thus the mere vicinity of the eleftric renders the 
 condudor eleftric, and the eleClrioity ceafcs on remo- 
 ving the globe. This is perftttly conformable to the 
 theory, whether we fuppofe the fluid to be made re- 
 dundant or deficient at the remote end of tlie conduc- 
 tor. If one ihould afcribe the approach of the pith- 
 ball to the immediate aftion of the globe, it is fufiicicnt 
 to obferve, that if the ball be fufpended near the Jit/f of 
 the condudtor, it will approach the condudlor, fliewing 
 that it is affedled by the conduftor, and not by the 
 globe. 
 
 Let the globe be held in the pofition D (fig. 12 ),S-atcnfdir- 
 about fix inches from the conduClor, and a little above 'p'""''"" . 
 the line of its axis. Take the glafs rod (fig. 8.), and|!xpjrrmea- 
 bring its knob into contaft with the under fide of thetaliy. 
 remote end c of the conduftor. The balls of the elec- 
 trometer will fcparate, (hewing that they are eledrified 
 in the fame manner, and repel each other. Slide the 
 brafs knob along the under fide of the conduftors, quite 
 to the end a. The balls will gradually coUapfe as the 
 knob approaches a point near the middle of the conduc- 
 tors, where they will hang parallel. Faffing this point, 
 they will again feparate, and moll of all when the knob 
 is at a. In this fituation they will deviate toward the 
 globe, and will be direfted llraight toward it, if it be 
 held too near, or in the direftion of the axis. This 
 would difturb the experiment, and mull be avoided. 
 Thele phenomena are conformable to the account given 
 of the diipofilion of the fluid in the conduftor. The 
 eleftrometer may be confidercd as making a part of the 
 conduftor ; and when its threads hang parallel, it is in 
 its natural (late, having its fluid of its natural denfity. 
 This, however, cannot be ft:riftly true, according to 
 the theory ; becaufe the balls of tlie eleftrometer mud 
 be confidered as more remote from the eleftric, and 
 their eleftrical ftate muft correfpoiid to a point of the 
 conduftor more remote than that where the knob of 
 the eleftrometer touches it. This will be more remark- 
 ably the cafe as the threads are longer. Accordingly, 
 an eleftrometer with very long threads will never col- 
 lapfe. The place of the neutral point cannot be accu- 
 rately afcertained in this way. Lord Mahon imagined Lord Ma- 
 that its fituation B was determined (in his experiments''""'*'^'''*''" 
 with a long conduftor) to be fuch, that D ^ was har- J^'^"^';°[;^f 
 monically divided in B and a ; and he finds this to bepnjnr not 
 agreeable to the refult of an eleftric atmofphere whofe larranted 
 denfity is inverfely proportional to the fquare of the dif- ^y ^"*'^- 
 tance. But we cannot deduce this from his narration^''*"*"""' 
 of the experiment. He gives no reafon for his felec- 
 tion of the point D, nor tells us the form and dimen- 
 iions of the eleftric employed, nor takes into account 
 the aftion of the fluid in the long conduftor. It is 
 evident that no computation can be inftituted, even oti 
 his Lordfliip's principles, till all this be done. Wc have 
 4 C 2 always
 
 57^ 
 
 64 
 Conftant 
 diftintilions 
 «f rciliin- 
 riancy and 
 deficiency. 
 
 ELECT 
 
 alwavs found that the neutral point was farther from 
 the cleflric, in proportion as the conduiftor was fmnllfr, 
 and when the elcftriclty was ftronger ; and that the dif- 
 ferences in tliis refpeft were lo very confiderable, that 
 no dependence could be had on this experiment for de- 
 terminin;; the law of aftion. It fhoiild be fo, both ac- 
 cording to Lord Mahon's and Mr ^pinus's theory. 
 But to proceed with our examination : 
 
 Having touched the end c of the conduftor with the 
 knob of the eleftrometer, bring it away. The balls 
 will continue to repel each other, and they are attraA- 
 cd by any body that is in its natural ftate. Touch the 
 fame end with the knob ol the other tledtromcter, and 
 bring it alfo away ; the balls of the two eledrome- 
 ters will be found to repel each other : but if one has 
 touched the condut^or at c, and the other has touched 
 it at a, the eleftrometers will ftrongly attradl each o- 
 ther. All this is quite conformable to the theory. If 
 the fluid has been comprefTed at c, and therefore the 
 balls of that eleftrometer are overcharged, they muft 
 repel each other, and repel any other body eleftrified 
 in the fame way. They mull; attratl and be attrafted 
 by any natural body. But the balls of the other elec- 
 trometer having touched the condudlor at a, muft be 
 undercharged, and the redundant iluid of the one muft 
 attraft the redundant matter of the other. 
 
 If the conductor has been elettrilicd by the vicinity 
 of excited glafs, the eledrometcr which touched it in 
 the remote end c, will be repelled by a piece of ex- 
 cited glafs, but attrafted by excited fealing wax. The 
 eleftrometer which touched the conduftor in ti will be 
 attrafted by excited glafs, and repelled by excited feal- 
 ing- wax. The contrary will be obferved if the conduc- 
 tor has had its electricity induced on it by the vicinity 
 of the globe covered with fcaling-wax. This is a com- 
 plete proof that Mr Dufuy's doftrine of vitreous and 
 refinous eleftricity is unfounded. Both kinds of elec- 
 tricity are produced in a conducing body, without any 
 material communication, by mere juxta-polition to a 
 body poffefTed of either the vitreous or the refinous elec- 
 tricity. 
 
 V/e have not yet mentioned any reafons which in- 
 dicate which end of the conduftor is elertrical by the 
 redimdancy of eleftric fluid, nor is the reader prepared 
 for feeing their force. It is generally believed that the 
 remote end of a conduftor which is eleftrified by glafs, 
 excited by rubbing it wiih flannel or amalgamated lea- 
 ther, is eleftrical by redundancy. No difference has 
 been obferved in the attradions and repulfions. But 
 there are other marks of diftinftion which are conftant, 
 and undoubtedly arife from a difference in the mode of 
 aftion of thofe of mechanical forces. If, while the ex- 
 cited glafs globe remains at D, a glafs mirror, foiled as 
 ufual with tin-k-af, be made to touch the remote end of 
 the condnftoi", and flowly drawn tranfverfely, fo that 
 the conduftor draws a line 3S it were acrofs it — this 
 mirror being laid down with the foiled fide undermoft, 
 the duft, which fettles on it in the courfe of a day or 
 two, will be chiefly collefted along this line, fomewhat 
 in the form of the fibres of a feather. But if the con- 
 duftor was rendered eleftrical by the globe covered 
 with ftaling-wax, the duft will be collefted along this 
 line in little fpots like a row of beads. The appear- 
 ances will be reverfed if the mirror has been pafted acrofs 
 the end of the conduftor which u neareft to the excited 
 
 R I C I T Y, 
 
 eleftric. In fhort, in whatever way the drawing point 
 has been eleftrified, if it repel a ball which has touched 
 excited glafs, the lijie will be feathered ; but if it at- 
 traft fuch a ball, the line will be fpotted. There are 
 many ways of making this appearance much more re- 
 markable (fee Electricity, £/«j'i:/. Scft. viii. n" 48.) 
 than this ; but we have mentioned it on this occafion, 
 becauic the circumftances which occafion the difference, 
 whatever it is, are the moft fimple poflible. Nothing 
 is communicated; and therefore the effeft muft arife 
 from the unnatural ftate of a fubftance or power refi- 
 ding in the body. If it be a fubftance /u( generis, the 
 eleftric aftion muft arife from a different diltributlon cf 
 this fubftance ; from a redundancy and deficiency of it 
 in the different portions of the conduftor. Without 
 pretending as yet to fay which is redundant, we fliall 
 fuppofe, with Dr Franklin, that the eleftricity of ex- 
 cited glafs is fo ; and we fhall ufe the words reJumiant 
 and pufitive to diftinguifh this eleftricity from the other. 
 This is merely that we may, on many occafions, con- 
 fiderably abbreviate language. 
 
 The different eleftrical ftates of the different por. 
 tions of the conduftor may be feen in another way, 
 which is perhaps more fimple and unexceptionable than 
 that already narrated. While the globe remains at D, 
 take the two extreme pieces A and C afide ; or, if on- 
 ly two pieces have been ufed, draw the remote piece 
 farther away. Now remove the excited globe. When 
 we examine A feparately, we fhall find it wholly nega- 
 tive, or undercharged, flrongly repelling a ball eleftri- 
 fied by fealing-wax, and attrafting a ball eleftrified by 
 glafs. The other piece C exhibits pofitive eleftricity, 
 attrafting and repelling what A repelled and attrafted. 
 If only tliree pieces of the conduftor have been employ- 
 ed, the middle piece B is generally pofitive ; but this 
 in a very faint degree. 
 
 If all the pieces be again joined, they are void of 
 eleftricity. If, inlfead of fuch conductors, a row of 
 metal balls, fufpended by filk lines, are employed, one 
 of them may generally be found without any fenfible 
 elettrlcity, when feparated from the reft, having been 
 the neutral part of the row while united. 
 
 Thefe very fimple fafts fhew, as completely as can 
 be wiflicd, that if the eleftric phenomena depend on a 
 fluid moveable in the pores of the body, the conftitu- 
 tion given it by Mr .ffipinus is adequate to the explana- 
 tion. We may now venture to afTert, that every other 
 phenomenon of attraftion and repulfion will be found 
 in exaft conformity with the legitimate confequences of 
 this conftitution of the electric fluid. 65 
 
 That nothing is coirniunicated from the eleftric will'"^""', . 
 appear ft ill more forcibly by the following experiment :gij^ri|.iiy ' 
 Let a conduftoi be rendered eleftrical in the way noW|,othing is 
 defcribed, and touch either extremity of it with theconimuni- 
 little eledromcter, and obfervc attentively the divergen-"'^*^- '"* 
 cy of its threads. Now approach its remote extreir.i- ^^"„ ^^j 
 ty with another condufting body, fuch as a fiugle piece excited, 
 of thofe conduftors, it will be rendered eleftrical ; as 
 may be difcovered by a delicate eleftrometer- Obferve 
 carefully whether the electrometer in contaft with the 
 firft conduftor be affefted : — it will generally be found 
 to fpread its threads wider. It will certainly be thus 
 affetted if the other conduftor be very long and bulky, 
 or touched by the hand ; or if, inftead of this fecond 
 conduftor, we approach the firft with the extended 
 
 palia
 
 65 
 
 e forced 
 
 fluid is 
 
 ■.etc ' by 
 
 er elec- 
 
 :d bo- 
 
 eftric 
 edlespo- 
 ityand 
 rucity. 
 
 ELECT 
 
 palm of ihe hnn(^. As tlie iVcor.d conduAor was rtii- 
 tlcred cleflriciil, fo, undoubtejiy, is iKc hand alio : and 
 its clcftrificatioi) has not deprived the tii ll condudor 
 ot any of its tleftnc power, but, on the coiitt;iiy, has 
 inciealcd it. And tlils augmentation of its power is 
 equally fenfible at both ends : For an elertrorncter at 
 the other end will alfo diverge more when the hand is 
 brought near the remote end. This theory explains 
 this in the mod fatisfatlory manner. The firlt conduc- 
 tor renders the fecond elcftric, by propelling its fluid 
 to a greater diltance. The fecond coiiduftor now a6ts 
 on the fluid that is moveable in the firft, and caufes 
 a greater accumulation in its end which is farthcft from 
 the eleAric ; that is, renders it more eleftric. 
 
 Suppofe that, inllead of i inploying an excited globe 
 of glals, we had made ufe of a condudtiiig body, flightly 
 overcharged. Thus if we employ the conduftor A, over- 
 charged, to induce tlcflvicily on C ; this will produce the 
 fame general efFeCl on our let of condudors. But it we 
 have previoufly examined the force of the redundant bo- 
 dy, by fufpending a pith-ball near it, and obferving its 
 deviation from the perpendicular, we may fometimes be 
 led to think that it has imparted fomething to the other 
 body. For if the other body and the pith-ball be on 
 oppofite (ides of the redundant body, the pith-ball will 
 fall a little ; indicating a diminution of eleftric force. 
 But this Jhonlil happen according to the theory ; for it 
 ■was fliewn, in n° 52. that the conftipation in the re- 
 mote end of the overcharged body will be dimmifhed, 
 and along with this, its aflion on the pith ball. We 
 fhould find the eleftricity of the other end, next the 
 conduftor, increafed, could we find an eafy way of ex- 
 amining it ; but an eleclrometer applied there will be too 
 much affected by tiie conduiior. 
 
 The iame conclufions may be drawn from the fol- 
 lowing faCls : Hang up a rufh-pith eledromcter. Ap- 
 proach it below with a body flightly eledlrified. The 
 legs of the eleftrometer iminediately diverge, though 
 Etirafted by the eleiSrified body. Hold the hand above 
 the cleftrometer, and they will diverge Hill more ; touch 
 the top of it,' and they Ipread yet farther. Hold the 
 ele&riried body (very weakly electrified) above the 
 tleftrometer, fo that its legs may diverge a little. Hold 
 the hand above the elcftrificd body ; the legs of the 
 cleftro'-ieter will come nearer each other. 
 
 Thefe appearances are obfcrved whether the clcftric 
 be pofitive or negative. We need not take up lime in 
 explaining this by the theory, its agreement is fo ob- 
 vious. 
 
 Laftly, on this head, if, in place of a fixed conduc- 
 tor, we ufe one of the needles of gilt card, fet on its 
 pivot, and if we then approach it with another con- 
 dueling body, in the manner reprefented by E and C 
 of fig. 6. we fhall obferve that end of the needle to 
 avoid the other body ; but if we bring them together, 
 in the inanner reprefented by F and B, they will at- 
 traft each other. The attraftion will be greater when 
 the body F is long ; and motl of all when it commu- 
 nicates with the ground. Tiiefe phenomena are there- 
 fore in perfeft conformity with the theory ; but it may 
 fometimes happen that E will attraft the end of C that 
 is neareft to A, and E will be eleftrified pofitivcly if 
 A be pofitive. This feems inconfif^ent with the theory ; 
 and, accordingly, it has been adduced by Volta againft 
 Lord Mahon's account of the eleftrical ftate of a cod. 
 
 573 
 
 R I C I T Y. 
 
 dudor in a fituation fnnibr to that of C. But the theo- 
 ry of yEpinus llicws the poflibility of this cafe. Whco 
 E is very long, or when it is held in the hand, it is 
 rendered much more inidercharged than the adjacent 
 part of C ; and the fluid in the remoter, but tiot much 
 remoter, part of C is llrongly attraifcd by the toplous 
 redundant matter in the near end of E, ai.d is brought 
 back again, and pafiVs over into E, in the way to be 
 deicribcd immediately The cafe is rare, and it will 
 not happen at any conliderable diltance from the neutral 
 point of C If, indeed, E touch the near end of C 
 before A is brought near, the appro ich of A will caufe 
 fluid to pafs into E immediately, and C will be left un- 
 dercharged on the whole. 
 
 The reader, who is at all converfant with eleArical 
 experiments, will be fenfible, that thefe experiments are 
 delicate, requiring the gieateft drynefs of air, and every 
 attention to prevent the dilfipation of elcdricity during 
 the performance. This, by changing the ftate of the 
 conduftors and eleftrometers, will frequently occafion 
 irregularities. The eledtrometers are mo(t apt to change 
 in this relpeft, it being fcarcely pofuble to make them 
 perfeftly fmooth and free from (harp angles. It may 
 therefore happen, that when the conductors have af- 
 feited them yiryorac <rW, by the action of the diflur- 
 bing elediric, the removal of this cleftric will not caufe 
 the eleftromcters to hang perpendicular; they will often 
 be attrafted by the conduftois, and often repelled; but, 
 the intelligent experimenter, aware of thefe circum. 
 itances, will know what allowances to make. 67 
 
 The theory obtains a ilill more complete fupport Phf"""™* 
 from a comparifon with iimilur c>.perim(.hts made with J? ,1'"^"" 
 imperfeft condudlors. It, in place of the feries A, B, juitors 
 C, of metalline condiidlors, we employ cylinders of preariycor- 
 glafs or fealing wax, or even dry wood or marble, and roberate 
 eleftrometers wich filk threads in place of the rufh-pith^ ^^'y- 
 eleftromcters, we (hall find all the appearances to be 
 fuch as the theory enables us to prediil. If, for ex- 
 ample, we ufe a fingle cylinder A of glafs, we fliall 
 find that the neighbourhood of the eleftric D fcarcely 
 induces any ekdtricity on A. The electrometer will 
 hardly exhibit the fmalleft attratlion, and its motions 
 will be ahnoft entirely fuch as arife from the immediate 
 influence of the eledlrlc body D. A cylinder of very 
 dry wood will be more affe-'ed by the eleftric D; and 
 a circumllance of theoretical importance is very dillinft- 
 ly obferved, namely, the gr:H!n:d (liifting of the neutral 
 ])oint. It will be found to advance along the cylinder 
 for a very long while, when every circumllance is very 
 favourable, the air very dry, and the wood almoft a 
 nonconduilor ; and its final fituation will be found 
 much nearer to the eleftric than in the brafs conduftor. 
 Several inftruftlve experiments of this kind may be 
 found in a treatlfc publlfhed in 1783 by Dr Ttiomas 
 Mihier at Maidflone in Kent, entitled, " Experiments 
 and Obfervations on Eleftrlcity." The author does 
 not protefs to advance any new doftrines, but only to 
 exhibit experiments fcientifically arranged for forming 
 a fyllem. He fupports the Franklinian fyftem as it 
 was generally underftood at that time ; but is much 
 embarrafTed for the explanation of the repulfion of ne- 
 gative eleftrics. The jEpinian correftion of this theory 
 did not offer itfelf to his mind. g. 
 
 We need not go over the fame ground again with Irrcgula- 
 iroperfeft conduftors. It is well known that fuch bo. rities. 
 
 dica.
 
 E C T R 1 
 
 held 
 
 574 E L 
 
 tlies nre more weakly attraiTtcJ and repelled ; that the 
 
 balls of ail eleftromcter with llnea threiuls diverge vaft- 
 
 ly more when an eleftrified body is held below it, than 
 
 if the threads are fdken : that fuch eleftrometers tie- 
 
 quenlly exhibit very capricious appearances from the 
 
 i\i)w but real progrefs of tlie eledlricity along the 
 
 threads. TheU" anomalies will be better uuderftood 
 
 when we exjjlain the diffipatiun of eleftricity along im- 
 
 f,n perfefb coiiduftors. 
 
 Induced e- A very effential deduftion from the theory is, that 
 
 Ijclncity off{j(, eleflricity induced on an imperfeft conduftor muft 
 
 "^^'I A^. have fume permanency. This is fully confirmed by 
 
 conduiitors . 1 •' ,,,-n ru- 
 
 is really cxpermicnt. Jout tlie remarkal)le inllaiices or this par- 
 
 [ermauent. ticular cannot be produced till we be better acquainted 
 with the methods of producing great accumulations of 
 fluid. It is enough to obferve at prefent, that a per- 
 manent, elcdlricity may always be obferved at the junc- 
 tion of the conduftors with their infulating ftalks. The 
 brafs coiiduftor A ceafes to be eleftric as foon as the 
 excited globe is removed; but the very top of the glafs 
 jlalk on which it is fupportcd will fenfibly aifeA a de- 
 licate eleftrometer for a long while after. The follow- 
 ing pretty experiment fliews this permanency very di- 
 ilin&Iy. Set one of the feallng-wax needles on its pivot, 
 and place it between two infulated metal fpheres of 
 conliderable fize, at fuch a diflance from both as not 
 to receive a fpark. Eleftrity ihefe balls moderately, 
 one of them pofitively, and the other negatively, and 
 keep them thus eledtrified for fome hours by renewing 
 their electrification. The needle quickly arranges it- 
 fclf in the line adjoining the two fpheres, juft as a mag- 
 netic needle will do when placed between two magnets 
 whofe difTiniilar poles front each other. Any gentle 
 force will derange the needle ; but it will vibrate like a 
 magnetic needle, and finally fettle in its former pofition. 
 When this has been continued fome time, that end of the 
 needle which pointed to the pofitive globe will be found 
 negative, and the other will be found pofitive, if exa- 
 mined with an eleftrofcope. And now, if the two 
 -globes be removed, this little needle will remain cleftri- 
 cal for entire days in dry frofty weather, and its ends 
 will approach any body that is brought near it (taking 
 rare not to come too clofe) ; and the end which point- 
 ed to the pofitive globe will avoid a piece of rubbed 
 fealing wax, but will approach a piece of rubbed glafs j 
 but the other end will be afFefted in the oppofite way. 
 In fhort, it proves an eleftric needle with a pofitive and 
 negative pole. 
 
 If two fmall infulated balls are moderately eleftrified, 
 and placed about fix inches afunder, this needle, when 
 carried round them, will arrange itfelf exaclly as a mag- 
 netic needle does when carried round a magnet of the 
 fame length. If the fame trial be made with the needle 
 of gilt card, it will arrange itfelf in the fame manner 
 that a foft iron needle arranges itfelf near a magnet, but 
 either end will turn indifferently to either globe, 
 sneftr'cal If a thin glafs plate, coated with red fealing wax, be 
 meridians, fg)- q„ jl,e pofitive and negative globes, and we fprinkle 
 (from a confiderable height) a fine powder of black 
 fealiiig wax, and then pat the plate gently with a glafs 
 rod fo as to agitate it a little, the particles of wax pow- 
 der will gradually arrange themfelves into curve lines, 
 diverging from the point over one of the globes, and 
 converging to the point over the other, precifely like 
 the curves formed by iron-filings fprinkled on a paper 
 
 CITY. 
 
 over a magnet. Each little rag of wax becomes 
 eleflrical by polition, acquires two poka, and the pofi- 
 tive pole of one attrafts the negative pole of another ; 
 and they adhere in a certain determinate pofition, near- 
 ly a tangent to the curve, which was mentioned in 
 n" 50, and indicates the law of magnetic adtion. When 
 in this ftate, if a hot brick be held over the plate till 
 the wax loften a little, the particles of black wax will 
 adhere to the red coating, and give us a permanent fpe- 
 cimen of the adlion. 
 
 It is well known that liquid fealing wax is a con- jj, 
 duftor. The writer of this article filled a glal'j tube 
 with powdered fealing \<'ax, and melted it, and then ex- 
 pofed it, in its melted flate, to the influence of a pofi- 
 tive and a negative globe, licping to make a powerful 
 and permanent elettric needle, which fliould have two 
 poles, and exhibit a fet of phenomena refembling thofe 
 of magnctifni. Accordingly he, in fome meafuie, fuc- 
 ceeded, by keeping the globes continually electrified 
 for feveral hours, till the wax was quite cold. It had 
 two difl:indl poles, and preiervcd this property, even 
 though plunged in water, and ivhlle immerfed in the wa- 
 ter ; but he was greatly difappointed as to the degree 
 of its eledlricity. It juft afFefted a fenfible eleftrometer 
 at the diftance of fix inches from either pule. It was 
 confiderably ftronger than if it had not been melted 
 during the impregnation, but by no means in the de- 
 gree that he expefted. It retained fome eleftricity for 
 about fix weeks, although lying neglefted among con- 
 dufting bodies. After its pov.'er feemed quite extinft, 
 he was melting it again in order to renew it. Some 
 light fibrous things chanced to be near it. While it 
 was foftening, it became vei-y ferfibly eleftrical, caufing 
 thefe fibres to bend towards it, and even to cling to the 
 tube. We (hall fee by and bye, that he was miftaken 
 in expefting more remarkable appearances, and that the 
 theory, when properly applied, does not promife them. 
 Having thus eftablilhed (as we think) this theory on 
 fufficient foundations for making it a very pcrfpicuous 
 way of explaining the phenomena of induced eleftri- 
 cily, we proceed to compare it with the fecond general 
 fact in electricity. 
 
 Prop. II. When an infulated body B is brought j;ig^„£;, 
 very near an electrified body A, a fpark is obferved toby comm 
 pafs between them, accompanied with a noife (which nidation 
 we fhall call the eledtric Snap), and B is now eledtri- 
 fied permanently, and the eleflricity of A is dimi- 
 nifhed. 
 
 Although this be one of the moft familiar fadts in 
 eleflricity, it will be proper to confider its attending 
 circumftances in a way that connetts it with what we 
 have now learned concerning ele<5}ricity by pofition. 
 
 Let the infulated body A (fig. 14.) be furnifhed 
 with a cork-ball, hanging by a filk thread from a glafs 
 ftalk connected with A ; let B be fitted up in the fame 
 manner ; let A be cledtrified weakly, and its degree of 
 electricity be eftimated by the inclination of the ball 
 towards A : fince B is not eleftrified, its eleftrometer 
 will hang perpendicular ; but when it approaches A 
 (keeping the eledrometers on the remote fides of both), 
 its elettrometer will approach it, and the eledtrometer 
 of A will gradually approach the perpendicular. When 
 the bodies are brought very near, a fpark is feen be- 
 tween them ; and, at that inftant, the elettrometer of 
 
 B coBies
 
 ift hap. 
 
 -,brup£. 
 
 1. 1. 
 
 7»' 
 
 n 
 
 1! .arted 
 tricity 
 li.ces 
 ;uil re 
 ioo. 
 
 ELECT 
 
 B comes much nearer to it, and that of A drops farther 
 from it. If they be now ftparated, their elediometers 
 will retain their new pofitions with very little change, 
 and B will now manifcll the fame kind of electricity 
 with A. 
 
 Such is the appearance when A has been but weakly 
 elciflrified. Bringing B near A, the fluid in B is drawn 
 to the remote fide, if A be overcharged, or drawn to 
 the fide nearelt to A, if A has been undercharged. B 
 ai3s on its eledlrometer in confequence of the change 
 made in the difpolition of its fluid. The eleftrometer 
 is attrafted. In the mean time, the change made in 
 the difpofition of the fluid in B affefts the moveable 
 fluid in A. If A was overcharged, the adjacent fide 
 of B becomes undercharged, and its redundant matter, 
 attrafting the fluid in A, condenfes it in the adjacent 
 fide, abftrafting part of the redundant fluid from that 
 fide which is next to the pith-ball. Then the joint ac- 
 tion of the whole redundant fluid in A on the pith-ball 
 is diminidied. 
 
 As there is now an attradion in the redundant fluid 
 in A for the redundant matter on the adjacent fide of 
 B, it is reafonable to fuppofe that when this attrac- 
 tion, joined to the repulfion of the redundant fluid be- 
 hind it, is able to overcome the attraftion which con- 
 reits it with the fuperficial particles of the matter, it 
 will then elcape and fly into B: but this will not hap- 
 pen gradually, but at once, as foon as the expelling 
 force has arifen to a very confiderable intenfity. We 
 cannot fay what is the precife augmentation that Is ne- 
 ceflary ; but we can clearly fee, that however great the 
 attraftion for the adjoining particles may be, while the 
 particle is furrounded by them on all lides, it will yield 
 to the fnialleft inequality of force, becaufc the particles 
 before it attraft as much as thofe behind it; but when 
 it is juft about to quit the lail or fuperficial particles of 
 A, a much greater force is now necefliiry. It can he 
 firiSly oemonftrated, that when the mutual tendency is 
 inveriely as the fquare of the diftance, the aflion of a 
 particle placed immediately without a iphere of fuch 
 matter is double of its aftion when fituated in the very 
 furface*. A. fiilltis of this kind muft obtain whatever 
 be the law of eleftric attraftion. We {hall fee other 
 caufes alfo which fliould prevent the efcape of redun- 
 dant fluid, and alfo its admiffion, till the impelling force 
 is encreafcd in a certain abrupt degree. 
 
 Thefe obfervations mull lufBce at prefent to explain 
 the deiultory nature of this tranferencc, if there be 
 really a transference. That this has happened, may be 
 confidently inferred from the fudden diminution of the 
 tleftricity of A, indicated by the fudden fall of its 
 eleftrometer ; but it is more exprefsly eftaLliihcd, that 
 there has been a transference by the change produced 
 on B. It is now permanently eleftrified, and its elec- 
 tricity is of the fame kind with that of A, pofitive or 
 negative according as A is poutive or negative. And 
 now we are enabled to explain the third general fiid In 
 eleflricity. 
 
 Prop. III. When a body has imparted cleflriclty to 
 another, it conftantly repels, it, unlefs that other has 
 afterwards imparted all its electricity to other bodies. 
 This faft, from which there is no exception, is an im- 
 mediate confequence of the theory. Before the trans- 
 ference fuppofed by it, B was in its natural Hate; after 
 
 575 
 
 R I C I T Y. 
 
 the transference, both bodies contain redundant fluid, 
 or redundant matter ; therefore they muft mutually re- 
 pel. 
 
 AVe may now take another form of the experlmentj 
 which will be much more convincing and inftruftlve. 
 Let A be eleflrified pofitively, or by redundancy, and 
 let its eleftrometer be attached to it by a condu£\ing 
 fl;alk, and have a flaxen thread; let this be the cafe alfo 
 wiih the eledrometer of B ; then the appearances fliould 
 happen in the following order: When A is made to 
 approach B, the eleiSrometcr of B muft gradually rife, 
 diverging/rom B ; becaufc the fluid condenfed on the 
 fide remote from A, and in the eleftrometer, will aft 
 more ftrongly on it than the deferted matter on the 
 other fide of B ; and when the fudden transference is 
 made, and B is wholly overcharged, its eleftrometer 
 will immediately rife much higher, and muft remain at 
 that height, nearly, when A is removed. On the other 
 hand, the eleftrometer attached to the remote fide of 
 A muft defcend, by reafon of the change made in the 
 difpofition of the fluid in A by the induced eleflrlcal 
 ftate of B : and when a confiderable portion of the re- 
 dundant fluid in A partes into B, the eleftrometer of A 
 muft fiidenly fink much lower, and remain in that ftate 
 when B is removed. 
 
 Many circumftances of this phenomenon corroborate Transfer- 
 our belief of a real transference of matter. The caufe'''^^ "f » 
 of eledtric afllon refided formerly in A alone ; it nowj?""'"^'' 
 refides alfo in B. The larger that B is, the gi eater is MehWp^, 
 the diminution of A's eledtric power, and the fmallerbable. 
 is the power acquired by B. It perfedly refembles, 
 in this refpeft, the communication of faltnefs, fweet- 
 nefs, &c. by mixing a folution of fait or fugar with 
 difl'erent quantities of water ; and the evidence of a 
 transference of a fubftance, the caufe of eleftric attrac- 
 tions and repulfions, is at leaft as cogent as the evidence 
 of the transference of heat, when we mix hot water 
 with a quantity of cold, or when a hot fulid body is 
 applied to the fide of a cold one. We alfo fee fo manj- 
 chemical and other changes produced by this commu- 
 nication of eleftricity, that we can hardly refufe ad- 
 mitting that yowf material fulijlancs paffes from one body 
 to another, and,- in its new fituation, exerts its attraftions 
 and repulfions, and produces all tlielr efFeds. 
 
 We may deduce the following corollaries; all of which 
 are exaftly con fornribk to the phenomena, fervinv Hill 
 more to confirm the juftnefs of the theory. 
 
 1. A certain quantity of what polfcfles thefe powers Degrees of" 
 of attradion and repulfion Is neceflary for giving a de- vivacity 
 termined vivacity to the appearances. Another fpark l'™P"''J""'* 
 muft pafs between the bodies, only if they be I'roi'gbt Jl'dl '^J^^^^^ 
 nearer, and their electrometers muft rife and fall ftdl far- in.jartcil. 
 ther. For by the firft transference of eiedric ihiid iii- 
 
 to B, the expelling power of A is dimiiilflied, and the 
 fuperior attradion of the redundant matter in the adja- 
 cent fide of B is alfo counteracted by the repulfion of 
 the fluid which has entered into it; therefore no more: 
 will follow unlefs thefe forces be encreafed, at leaft to 
 their former degree. V/hen this addition lias been made 
 to B, and this abftradion from A, their refpeftive elec- 
 trometers muft be affetlcd. All this is in perfed con- 
 formity to experience. jj 
 
 2. All the phcno.mena of communicated eleftricity Commtfii- 
 muft be more remarkable in proportion to the con- ''ai'o- niolt 
 duding power of the bodies. A very imperfed con- ,„ conJu^, 
 
 Uuttcrj f,rs..
 
 57'^ 
 
 ELECT 
 
 duftor, fnch as phfs or fc-ilnig wax, will impart or re- 
 ceive fluid only bi-'twecii the very neareR parts ; whereas 
 a metaliine body is inflantly afTefted through its whole 
 extent. This dcduflioa is perfeftly agreeable to the 
 whole train of tle^ric experiments. The finger receives 
 a ftrong fpark. from a large metalline ekclrified body, 
 which "dilcharges every part of it of a portion of its 
 eledilcity. But an excited globe, which fliews, by its 
 aftion on a dillant body, as great a degree of_ elcAri- 
 city, will give only a very fmall fpark ; and it is found 
 rot to be aff u d at any corfiderable diftance from the 
 point of its fiiif.ice from which the transference was 
 made. The whole eleilricity of a perfedl conduftor is 
 difcharged by touching it ; but a nonconduftor will 
 fuccefiively give fparks, if touched in many different 
 parts ; and it may be feen by a nice eleftrometer, that 
 each contad takes away the elcftricity only from a 
 very fmall fpace round it : and it is further highly de- 
 ferving of notice, that fome time after a fpark has been 
 obtained from a particular fpot of the ele<ftric, a fecond 
 fpark may be obtained from it, the eleftricity of the 
 neighbouring parts having been gradually diffufed 
 ^^ through it. 
 Infulation 3- If an ekaHfied condufting body toucTj any thing 
 neccflarv communicating with the ground by perfedl conduftors, 
 for eledric j,]i j^j eleitricity nmft difappear, and none can appear 
 appeafin- .^ ^j^^ ^^^^ touched by it ; for the mafs of the earth 
 bears fuch an unmeafnrable proportion to that of the 
 greatefl body that we can cleilrify, that when the re- 
 dundancy or deficiency is divided between them, it mull 
 be imperceptible in both. 
 77> Hence the necefiity of infulation, as it is called, or 
 
 the furrounding by non-conduAors every body which 
 we would have exhibit cledlric .appearances. We mud 
 refer the reader to the article Electricity in the En- 
 cycl. for all the obfervations on this head, and the rca- 
 fons of preference given to certain fubllances to be em- 
 ployed for infulating fupports. But we mull confider, 
 in its proper place, the manner in which the eledric 
 fluid is dilTipated by imperfeftly infulating fubllances ; 
 a fubjed intimately conne«ed with the theory. 
 Andeilri- 4- Any unelctlrified body will be firft attracted by 
 fiedbody an eleftrified body, will touch it, and will then be re- 
 attra(5l-andpp]lgj_ The neutral body is rendered eleiftrical by in- 
 then repels (J^^;op, Jt is, in confiqueKce of this, attracted, comes 
 any uuelec ""^' ' ■'ri .u-.. j 
 
 trifled bo- "^ar enough to receive a fpark, or even touches it, and 
 dy. is then electrified by communication ; and, in confe- 
 
 quence of this, it is repelled. This is confirmed by an 
 endlefs train of experiments. It was firll taken notice 
 of (we think) by Sir Ifaac Newton. Otho Guericke, 
 a gentleman of Magdeburgh, to whom we owe the air 
 pump, mentions many inttances of the repulfion, but 
 did not obferve that it was an univerfal law. Newton 
 was fo ftruck with it as to engage in a confiderable 
 train of experiments in the early part of his lite, while 
 meditating on the power of gravity ; but even his fa- 
 gacious mind did not obferve the whole procefs of na- 
 ture in his experiments. He obi'erved, that the light 
 bodies which rofe and adhered to the rubbed plate of 
 glafs were foon after repelled by it ; but did not ob- 
 ferve that the fame piece would again rife to the glafs 
 after it had touched the table. This fadt h now the 
 foundation of many experiments, which the itinerant 
 eleftriclans vie with each other in rendering very amu- 
 fing. We may render them inftruftive. Take away 
 
 19 ' 
 
 R I C I T Y. 
 
 the middle condudlor B (fig. ii), and hang m its 
 place a cork ball by a long filk thread. As foon as the 
 electric Sody D Is brought near to A, the ball is at- 
 trafted by its remote end, comes into contatt, is re- 
 pelled by it, and attraded by the adjacent end of C, 
 touches it, is faintly repelled by it, and agaui attraHcd 
 by A ; and the operation is repeated feveral times. 
 When all has ceafed, remove C, and alio the ele trie D. 
 C is found to have the fame eleclricity with D, and 
 A has the oppofite eledlrlcity. The procefs is too ob- 
 vious to need any detailed applleatiun of the theory. 
 The cork ball was the carrier of fluid from A to C if 
 D was eledlric by redundancy, or from C to A if D was 
 undercharged. If inltead of removing C when the vi- 
 brations of the ball have ceafed, we bring D a little 
 nearer, they will be renewed, and alter lome time will 
 again ceafe. The reafon i-> plain. The carrier ball had 
 brought the condudlor A into a ll.^.te of equilibrium 
 with the adlion of D. But this aftion is now increa- 
 fed, and the effects are renewed. If we now rtmove 
 D, the ball will vibrate between A and C with grcr.t 
 rapidity for a confiderable time before the vibrations 
 come to an end ; and we fliall find their number to be 
 the fame as before. The caufe of this is alfo obvious 
 from the theory. We may fuppofc A to be negative, 
 and C pofitive. One of them will attraft the ball into 
 contact, and will repel it, having put it into an electric 
 (late oppofite to that of the other conduftor. It now 
 becomes a carrier of fluid trom the pofitive to the ne- 
 gative conduClor, till it nearly reftore both to their pri- 
 mitive ftate of neutrality. 
 
 There is frequently a feeming capricloufnefs in thofe |,j.j'^i„' 
 attraftions and repulfions. A pith ball, or a down fea-tie> fre- 
 ther, hung by filk, will cling to the conductor, or other- <1 '•^'"^ — 
 wife electrified body, and will not fly off again, at lead >"• 
 for a long while. This only happens when thofe bo- 
 dies are fo dry as to be almoil non-conduclors. They 
 acquire a pofitive and negative pole, like an iron nail 
 adhering to a magnet, and are not repelled till they be- 
 come almoft wholly pofitive or negative. It never hap- 
 pens with conducting light bodies. . 
 
 5. It (hould follow from tlu- theory, that the eledtric jji^^fi,. ; 
 attractions and repulfions will not be prevented by the ti'in, tike 
 intervention of non-condufting fubltances in their neii-eravitatii 
 tral Itate. Accordingly, it is a fact, that the interpo-'^ ""'';" 
 fition of a thin pane of glafs, let it be ever fo extenlive, ,,',g j[„gr 
 does not hinder the electrometer from being affeCttd. | olition i 
 Alfo, if an infulated eleCtric be covered with a glafs'" "n-*^""- 
 bell, an eledtrometer on the outfide will be affected. ''^'^^*"''" 
 Nay, a metal ball, covered to any thicknels with fealing 
 wax, when electrified, will affect an electrometer in the 
 fame way as when naked We cannot fee how thele 
 fafts can be explained by the aftion of electric atmo- 
 fpheres. It is indeed faid, that the atniofphere on one 
 fide of the glafs produces an atmofphere on the other ; 
 but we have no explanation of this production, if the 
 interpofed plate be a non-conductor, how does the one 
 atmofphere produce the other ? It mull produce this 
 effeft by afting at a dillance on the particles which are 
 to form this atniofphere. Of what ufe, then, is the 
 atmofphere, even if thofe atmofpheres could effeft the 
 obferved motions of the eleftrometer in confiftency 
 with the laws of mechanics i The atmofpheres only 
 fubftitute millions of attraftions or repulfions in place 
 of one. We muft obferve, however, that the motions 
 
 of
 
 ELECTRICITY. 
 
 of the ek'ftrometer arc modified, and fometimes greatly the nibbed furfaces will fly back to tbe other, being ur- 
 changed, by the interpofed lion-conducing plate ; but (t-^J l^*^''' ^Y '''^' "ttradtion of the redundant matter and 
 this is owing to the clearicity induced on the plate, the repnlfion of its own particles. But the cleano, be- 
 
 577 
 
 If the cleftric is pofitive, the adjacent fiirface ot the 
 plate befonies faintly negative, and the fide next the 
 eleftrometer flightly pofitive. This afl'efts the eleftro- 
 meter even more than the more remote eleftric does. 
 That this is the canfe of the difference between the 
 ftate of the eleftrometer when the plate is there and 
 when it is removed, will appear plainly by breathing 
 gently on the glafs plate to damp it, and give it a imall 
 conducing power. This will make fome change in the 
 pofitioii of the eleftrometer. Continue this more and 
 more, till the plate will no longer infulaje. The chan 
 ges produced on the eleftrometer's poiition will form a 
 regular feries, till it is feen to airiime the very poiition 
 
 ing (lettric becaufc, and only becaufe, it is a non-con- 
 dudor, mull retain fome, or will remain deprived of 
 fome, in a flratum a little within the fuiface. The two 
 plates mull therefore be left in oppofitc Hates, and the 
 condufting, or noii elcftric plate, if infulated before fc- 
 paration, mull now exhibit eleftrlc adtion. 
 
 All this is exaftly agreeable to fad. We alfo know 
 that elcdlrics may be excited by nibbing on each other; 
 and if of equal extent, and equally rubbed, they exhi- 
 bit no eleftric powers while joined together; but when 
 parted, they are always, in oppofitc ilates. The fame 
 thing happens when fulphur is melted in a metal difli, 
 or when Newton's njetal is melted in a glafs difii. While 
 
 which it would have taken had the plate been brafs. joined, they are mofl perfc-aly neutral ; but manifelt 
 Then, confidering thofe changes in a contrary order, very ftrong oppofite ekaricities when they are fcpara- 
 and fuppofing the feries continued a little farther, we ted. This completely difappears when they are joined 
 
 :rong e- 
 (ftricity 
 ay be ex- 
 ted witli- 
 it appear. 
 
 ppoling _ 
 
 Jhall always lind that it leads to the "poiition which it 
 would have tsken when no plate whatever is interpofed. 
 We confider this as an important fart, (hewing that the 
 eleftric aaion is fimilar to gravitation, and that there 
 is no more occafion for the intervention of an atmo- 
 fphere for explaining the ])henomena of elearitity than 
 for explaining thofe of gravitation. 
 
 6. .Since non-elearics are conduftors, and fnice elec- 
 trics may be excited by friction with a nunelcaric, it 
 
 acrain, and reappears on their feparation, even after be- 
 ing kept for months or years in favourable circumitan- 
 ces. We have obfcrved the plates of t^lc, and other 
 laminated foflils, exhibit very vivid eleftricity \vhcn fplit 
 afunder. 8i 
 
 Attention to thefe particulars enables us to coufliua Pii.ici'plcs 
 machines for quicklv exciting vivid elearlcily on the "f '- "= ''"'" 
 furface of bodies, and tor alterwards exhibitir.g it wuli ^.^^-(ric 
 continued difpatch. The whirling globe, cylinder, orniaclunes. 
 
 follows, that if this non-eleclric be infulated, and fepa- plate, firll employed by Mr Haukfbee, tor the folitary 
 rated from the elearic, it will exhibit figns of ekarici- purpofe of CKamining the elcftricity of the globe, was 
 ty ; but when they are together, there mull not appear mod ingenioufly converted by Haufen, a German pro- 
 any marks of it, however llrong the excitation may be. feflbr, into a rapid coUeaor and difpenfer of elearicity 
 
 "■ ' to other bodies, by placing an infulated prime conduc- 
 tor dole to that part of the furface of the globe which 
 had been excited by friaion. Did our limits give us 
 
 We do not pretend to comprehend dillinftly the man 
 ncr in which friaion, or the other modes of exc.tation, 
 operate in changing the conneaion between the parti- 
 
 cles of the fluid and thofe of the tangible matter ; nor 
 is this explained in any eledric theory that we know : 
 but if we are fatisfied with the evidences which we have 
 for the exiflence of a lul*!lance, whofe prefence or ab- 
 fence is the caufc of the eleftric phenomena, we mull 
 
 room, we fhould gladly enlarge on this fubjea, which 
 is full of moft curious particulars, highly meriting the 
 attention of the philofopher : But it might eafily oc- 
 cupy a whole volume ; and we have Hill before us the 
 moll interelting parts of the mechanical departir.cnt of 
 grant that its ufual connedion with the tangible matter ekaricity, and {hall hardly find room for what is eflen- 
 of bodies is changed in the ad of excitation, by fridion, tially requilite for a clear and ufeful comprehenfion of 
 or by any other means. In the cafe of fridicn produ- it. We mull therefore requeft our readers to have re- 
 cing pofitive eledricity on the furface of the elediic, courlc to the original authorB, who have confidered the 
 we muft fuppofe that the ad of friaion caufes one body excitation by fridion minutely. And^ve particulaily 
 to emit or abforb the fluid more copioufly than the recommend the very careful perufal of Beccaria's I)i(- 
 other, or perhaps the one to emit and the other to ab- fertations on it, comparing the phenomena, in every 
 forb. V.'hichever is the cafe, the adjoining furfaces ftep, with this theory of.ffilpinus. Much valuable in- 
 mull be in oppofitc ilates, and the one rouftbe as much formation is alfo obtained from Mr Nicholfon's Obfer- 
 overcharged as the other is undercharged. When the vations, of which an abftrad is given in the article E- 
 bodies (which we may fuppofe to have the form of lectriCitv in the Encyclopedia Brihwiiica. The jE- 
 plates) arc joined, and the one exadly covers the other, piuian theory will be found to conned many things, 
 the aflemblage muft be inadive; for a particle of move- which, to an ordinary reader, mufl appear folitary aiui 
 able fluid, fituated anywhere on the fide of the over- accidental. ^j 
 
 charged plate, will be as much attraaed by the under- Seeing that this very fimple hypotheCs of vEpinusE.iJjnccs 
 
 charged furface of the remote plate as it is repelled by fo perfeSly coincides in its legitimate confequences with" t e""- 
 the overcharged fuiface of the near plate. The fur- all the general phenomena of attradion and ■'epulfion, j]^^^^^j'^^i.jj 
 faces are equal, and equally eledric, and ad on either and not only with thofe that are fimple, but even fuch flui^ 
 fide with equal intenlity ; and they are coincident, gg are compounded of many others — we may lillen, 
 
 ~~' -■ ■ ' ^yftjjQyt: the imputation of levity, to the other evidences 
 
 which may be offered for the materiality and moblLty 
 of the caufe of thofe mechanical phenomena. Such 
 evidences are very numerous, and very perfuafive. We 
 have laid that the transference of eledvicity is defulto- 
 
 Therefore their adions balance. The adionis expref- 
 
 fed by the formula of n' 4.:; ; namely, ¥' m'Xz — z' ; 
 and z — a' is = o, by reafon of the equal diftances of 
 thefe furfaces frtom the particle of exterior fluid. 
 
 But let the plates- be feparated. Part, and probably 
 the greateft part, of the redundant fluid on one of ry, and that the change made in the eledric ilate of the 
 
 St;ppL. Vol. I. Part II. 4 D fo^"-
 
 5/8 
 
 ELECTRICITY. 
 
 Snap, 
 
 Spark, and 
 lieat. 
 
 Chemical 
 cSe&t. 
 
 This 19 
 
 therefore 
 
 aiTumed. 
 
 84 
 
 fjiflrlhii- 
 tion of it 
 depends on 
 its law of 
 
 communicating bodies is always confiderable. It appears 
 to keep fome fettled ratio to the v.hule elcftric power 
 of the body. When the form of t}je parts where the 
 communication takes p!ace, and other circi:mil:inccs, 
 remain the fame, the transference increafes with the fize 
 of the bodies; and all ;he phenomena are more vivid in 
 propoition. When the conduflor is very large, the 
 fpark is very bright, and the fnap very loud. 
 
 1. This fnap alone indicates fome material agent. It 
 IS occr.fioiied by a fonorous undulation of the air, or of 
 fome claftic fluid, vvhidi fuddenly expands, and as fud- 
 denly collapfes again. But fuch is the rapidity of the 
 undulation, that when it is made in clofe veffels it does 
 not cxifl long enough, in a very expanded ttate, to af- 
 feA the column of water, fupported in a tube by the 
 elafticity of the air, for the purpofe of a delicate ther- 
 mometer or barometer ; jnil as a mufket ball will pafs 
 through a loofe hanging fheet of papci- without caufmg 
 any lenfible agitation. 
 
 2. The fpark is accompanied by intenfe heat, which 
 will kindle inflairmable bodies, will meltj explode, and 
 calcine n'.etals. 
 
 3. The fpark produces fome very rem<>rk;ible chemi- 
 cal cfFcfts. It calcines metals even underwater or oil; 
 it renders Bolognan phofphorus luminous: It decom- 
 pofes water, and makes new compofitions and decom- 
 pofitlons of many gazlform fluids; it affects vegetable 
 colours ; it blackens the calces of bifmuth, lead, tin, 
 luna cornea; it communicates^ a very peculiar fmell to 
 the air of a room, which is diflinft from all others; and 
 in the calcination of m?tals, it changes rc.markablv the 
 fmells with which this operation is ufually accompanied: 
 it affefts the tongue with an acidulous talte; it agitates 
 the nervous fyftem. — When v;e compare thefe appear- 
 auiies with fimilar chemical and phyfiological phenome- 
 na, which naturah'fts never hefitate in afcrlbing to the 
 aftion of material fubllanccs, transferable from one bo- 
 dy, or one flatc of combination, to atiother, we can fee 
 no greater reafon for hefitating in afcrihing the eledric 
 phenomena to the aftion of a material fubftance ; which 
 we may call ajluid, on account of its conneftcd mobili- 
 ty, and tie Aettrtc Jlu'idy on account of its dittinguifhing 
 effcfts. We arc well aware, that thefe evidences do not 
 amount to demonftration ; and that it is pofhble that 
 the elcflric phenomena, as well as many chemical chan- 
 ges, may rel\ilt from the mere difference of arrange- 
 inent, or pofition, of the ultimate particles of bodies, 
 and may be conlidered as the refiilt of a change of 
 modes, and not of things. But in the inftances we have 
 mentioned, this is extremely improbable. 
 
 We therefore venture to aiTume the exiftence of this 
 fubftance, which philofophers have called the eteilricjiuid, 
 as a propofitiou abundantly dcmoiiitrated ; and to af- 
 firm, on the authority of all the above-mentioned fadts, 
 that its mechanical chara£ler is fuch as is exprefled in 
 Mr yEpinus's hypothelis. 
 
 We proceed, therefore, to explain the moft intereft- 
 ing phenomena of eleftiicity from tf.efe principles. 
 
 We have feen that, in a perfeft conduftor, in its na- 
 tural Hate, the eleflric fluid is uniformly diftrihuted, 
 and cannot remain in any other condition. We are 
 particularly intercfted to know how it is diftributed in 
 an overcharged or undercharged body, and how this is 
 affcdled by the circumambient non-conduding air. It 
 
 is evident that much depends on this. The tendency 
 to cfcape, and particularly the tendency to transference 
 from one body to another, inuil be greateft where the 
 fluid is mod conftipcited. We know that it tends re- 
 markably to difiipate from all protuberances, edges, and 
 long bodies, and that it is impolfible to confine it in a 
 body having very acute far-projefting points; and, what 
 is more jjaradoxical, it is hardly poffible to prevent its 
 entering into a body furniflied with a fharp point.. The 
 fmallett rcfle<ftion muft fuggeft to our imagination, that 
 a perfcdlly moveable fluid, whofe particles mutually re- 
 pel, even at confiderable diftanccs, and which is con- 
 fined in a vefFel from which it cannot efcape, mull be 
 compreffed againll the fides of the velfel, and be denfer 
 there than in the middle of the veffel. But in what 
 proportion its denfity will diminifh as we recede from 
 the walls of the veffel, muil depend on the change of 
 (kftric repulfion by an increafe of diftance. The in- 
 tenfity varies in the proportion of fome funftion of the 
 diftance, and may be expreffed by the ordinatcs of a 
 curve, on whofe axis the diftances are meafurtd. But 
 we are ignorant of this funftion. We mull therefore Procefs for 
 endeavour to dlfcover it, by obferving a proper lohition d fcovering 
 of phenomena. Having made iome approximation to '*"' '"'*• 
 this difcovery, fuch as fhall give rife to a probable con- 
 jeHure concerning the funftiou which expreffes the in- 
 tenfity of eleftric repulfion, mathematics will then en- 
 able us to fay how the fluid muft be diftributed (at 
 leaft in fome limple and inftruftive cafes) in a perfeiSly 
 condufting body furrounded by the air, and what will 
 be its adtion on another body. Thus we fhall obtain 
 oftenfible refiilts, which we can compare with experi- 
 ments. The writer of this article made many experi- 
 ments with tbis view above 30 years ago, and flatters 
 himfelf that he has not been unfuccefsful in his attempts. 
 Thefe were condufted in the moft obvious and iimple 
 manner, fuggefted by the reafoniiigs of Mr jEpinus ; 
 and it was with fingubr pleafure that, fome years after, 
 he perufed the excellent diflertation of Mr Cavendilh in 
 the Philofophical Tranfaflions, vol. 61. where he ob- 
 tained a much fuller conviftion of the truth of the con- 
 clulion which he had drawn, in a ruder way, from more 
 familiar appearances. Mr Caveudifh has, with fingular 
 fagacity and addrefs, employed his mathematical know- 
 ledge in a way that opened the road to a much farther 
 and more fcientific profecution of the difcovery, if it 
 can be called by that name. After this, Mr Coulomb, 
 a diftinguifhed member of the French Academy of Sci- 
 ences, engaged in the fame refearch in a way Hill more 
 refined ; and fupported his conclufions by fome of the 
 moft valuable experiments that have been offered to the 
 public. We fhall now give a very brief account of this 
 argument : and have premifed thefe hiftorical remarks; 
 becaufe the writer, although he had eftablifhed the ge- 
 neral conclufion, and had read an account of his invelli- 
 gation in a public fociety in 1769, in which it was ap- 
 plied to the moft remarkable fafts then known in elec- 
 tricity, has no claim to the more elaborate proofs of the 
 fame doftrine, which is given in fome of the following 
 paragraphs. Thefe are but an application of Mr Ca- 
 vendifh's more cautious and general mathematical pro- 
 cedure, to the fuuftion which the writer apprehends to 
 be fufficiently eftablifhed by obfervation. 
 
 The moft unexceptionable experiments with which 
 we can begin, feera to be the repulfioiis obfervable be- 
 tween
 
 ELECTRICITY. 
 
 tvi'fen two /■««// fpheres. Whatever be the law of dif- 
 tiibution of the particles in a fphere, the general aflion 
 of its particles on the particles of another fphere will 
 follow a law which will not differ much frorn the law 
 of aflion between two particles, if the diamettrs of the 
 fpheres be fmall in proportion to their diftance from 
 each other. The inveftigation was therefore begun with 
 them. But the fubjeft required an eleftromcter fufccp- 
 tible of comparifon with others, and that could exhibit 
 abfolute meafures. The one employed was made in the 
 following manner; and we give it to the public as a va- 
 85 luable philofophical inftrument. 
 Compara- Fig rj. reprefents the electrometer in front. A is 
 bleelearo-a polidied brafs ball, ^th of an inch in diameter. It is 
 fixed on the point ot a needle three inches long, as flen- 
 dcr as can be had of that length. The other end of 
 the needle pafles through a b;ill of amber or glafs, or 
 other firm non-conduaing fubftancc, about half or 
 three-fourths of an inch in diameter ; but the end mufl 
 not reach quite to the furface, although the ball is com- 
 pletely perforated. From this ball rifes a (lender glafs 
 rod FEL, three inches long from F to E, where it 
 bends at right angles, and is continued on to L, im- 
 mediately over the centre of the ball A. At L is fix- 
 ed a piece of amber C, formed into two parallel checks, 
 between which hangs the ftalk DCB of the eleftrome- 
 ter. This is formed by dipping a llrong and dry <ilk 
 thread, or fine cord in melted fealing-wax, and hold- 
 ing it perpendicular till it remain covered with a thin 
 coating, and be fully penetrated by it. It mull be 
 kept extended, that it may be very ftraight ; and it 
 mud be rendered fniooth, by holding it before a clear 
 fire. This Ilalk is faftcned into a fmall cube of amber, 
 perforated on purpofe, and having fine holes drilled in 
 two of its oppofite fides. ■ The cheeks of the piece C 
 are wide enough to allow this cube to move freely be- 
 tween them, round two fine pins, which are thruft thro' 
 the holes in the cheeks, and reacli about half way to 
 the ftalk. The lower part of the ftalk is about three 
 inches long, and terminates in a gilt and burnifhed cork- 
 ball (or made of thin metal), a quarter of an inch in 
 diameter. The upper part CD is of the fame length, 
 and paffes through (with fome friftion) a fmall cork- 
 ball. This part of the inftrument is fo proportioned, 
 that when FE is perpendicular to the horizon, and 
 DCB hangs freely, the balls B and A juft touch each 
 other. Fig. 16. gives a fide perfpeftive view of the 
 inftrument. The ball F is fixed on the end of the glafs 
 rod FI, which pafles perpendicularly through the centre 
 of a graduated circle GHO, and has a knob handle of 
 boxwood on the farther end I. This glafs rod turns 
 ftiffly, but fmoothly, in the head of the pillar HK, &c. 
 and has an index NH, which turns round it. This in- 
 dex is fet parallel to the line LA, drawn through the 
 centre of the fixed ball of the eleftrometer. The circle 
 is divided into 360 degrees, and o is placed uppermoft, 
 and 90 on the right hand. Thus the index will point 
 out the angle which LA makes with the vertical. It 
 will be convenient to have another index, turning iliffly 
 on the fame axis, and extending a good way beyond the 
 circle. 
 
 This inftrument is ufed in the following manner : A 
 conneftion is made with the body whole cleftricity is 
 to be examined, by flicking the point of the conneft- 
 ing wire into the hole at F, till it touch the end of the 
 
 needle ; or, if we would fli;-v"!y cleArify the bniN A 
 and B, and then leave them iriGilatcd, we have only to 
 touch one of them with an eleftrified body. Now, 
 take hold of the handle I, and turn it to the n'ejht till 
 the index reach 90. In this pofition, the line LA is 
 horizontal, and fo is CB ; and the moveable bail B is 
 refting on A, and is carried by it. Now eleftrify the; 
 bulls, and gently turn the handle backwards, bringing 
 the index back toward o, 6ic. noticing carefully the 
 two balls. It will happen that, in fome particular po- 
 fition of the index, they will be obferved to feparate. 
 Bring them together again, and again caufe tlum to 
 feparate, till the exaft pofition at feparation is afcer- 
 tained. This will (liew their repulfive force in contaft, 
 or at the diftance of their centres, equal to the fum of 
 their radii. Having determined this point, turn the in- 
 (b-ument ftill more toward the vertical pofition. The 
 balls will now feparate more and more. Let au affift- 
 ant turn the long index fo as to make it parallel to the 
 ftalk of the eledlrometer, by making the one hide the 
 other from bis view. The mathematical reader will fee 
 that this eleftrometer has the properties afcribed to it. 
 It will give abfolute meafures: for by poizing the ftalk, 
 by laying fome grains weight on the cork-ball D, till 
 it becomes horizontal and perfc<fUy bala'iced, and com- 
 puting for the proportional lengths of BC and DC, we 
 know exactly th.' number of grains with which the 
 balls muft repel each other (when th.e ftalk is in a ho- 
 rizontal pofition), in order nuTe/y to feparate. Then a 
 very fimple computation will tell us the grains of repul- 
 fion when they feparate in any oblique pofition of the 
 ftalk ; and another computation, by the rcfolution of 
 forces, will fliew us the repulfion exerted between theni 
 when AL is oblique, and BC makes any given angli; 
 with it. All this is too obvious to need any fartlicr 
 explanation. The reafon for giving the conneftion be- 
 tween A and C fuch a circuitous form, was to avoid all 
 aftion between the fixed and the moveable p?.rt of tlie- 
 eleftrometer, except what is exerted between the tw<» 
 balls A and B. The needle AF, indeed, may acl a 
 little, and might have been avoided, by making the ho- 
 rizontal axis FI to join with A : but ?,s it was wanted 
 to make the inftrument of more general ufe, and fre- 
 quently to conneft it with an eleftrical machine, a bat- 
 tery, or a large body, no mode of conncttion oflcred it- 
 felf which would not have been more faulty in this re- 
 fpeft. The ueateft and nioft compendious form would 
 have been to attach the axis FI to C, and to make 
 CA and CB ftift" metalline wires, in the fame manner 
 as Mr Brookes's eleftrometer is made. But as the 
 whole of their lengths would have adlcd, this conftruc- 
 tion would have been very improper in the invtftiga- 
 tion of the law of eleSric repulfion. As it now Hands, 
 we imagine that it has confiderable advantages over Mr 
 Brookes's conilruftion ; and alfo over Mr De Luc's 
 comparable eleflrometer, defcribed in his Effays on Me- 
 teorology. It has even advantages over Mr Coulomb'* 
 incomparably more delicate eledlromcter, which is 'tii- 
 fible, and can meafure rej)ullioiis which do not exceed 
 the 50,000 of a grain ; for the inP>'-umeiit which we 
 have defcribed will meafure the attradior.s of the oppo- 
 fitely eleftrified bodies ; a thing which Mr Coulomb 
 could not do without a great circuit of experiments. 
 For inftead of making the ball B above A, by inclining 
 the inftrument to the right hand, we may inchne it to 
 4 D 2 the 
 
 579
 
 58o 
 
 ELECTRICITY. 
 
 tTie left ; and then, by clcflrifyiiig one of the balls po- 
 fitively, and the other negatively, when at a great dif- 
 tance from each other, their mutual attraftion will 
 caufe them to approach; CB will deviate from the ver- 
 tical toward A ; and we can compute the force by 
 means of this deviation. 
 
 We raufl remind the perfon who would make obfcr- 
 vations with this iiiftrument, that every part of it miift 
 be fecurcd airainft diffipation as much as poffible, by 
 varnifhing all its parts, by having all angles, points, and 
 roughnelTes removed, and by choofing a dry itate of the 
 air, and a warm room ; and, becaufe it is impoffiblt to 
 prevent diffipation altogether, we muil make a previous 
 courfe of experiments, in a varitty of circumftances, in 
 order to determine the diminution per minute corre- 
 fponding to the circumftances of the experiments that 
 are to be made with further views. 
 
 We truft that the reader will accept of this parti- 
 cular account of an inftrument which promifes to be of 
 coniiderahle fervice to the curious naturaliil ; and we 
 now proceed with an account of the conclufiuns which 
 have been drawn from obfervations made with it. 
 
 Here we could give a particular narration of fome of 
 the experiments, ami the computations made from them ; 
 but we omit this, becaufe it is really unnccefTary. It 
 fufEces to fay, that the v/riter has made many hundreds, 
 with different inftruments, of different fizes, feme of 
 them with balls of an inch diameter, and radii of iS 
 inches. Their coincidence with each other was far be- 
 yond his.expeftation ; and he has not one in his notes 
 which deviate from the medium -^^th of the whole force, 
 and but few that have deviated -r'xth. The deviations 
 were as frequently in excefs as in defefl. Kis cuftom 
 was to meafure all the forces by a linear fcale, and ex- 
 prefs them by ftralght lines ercfted as ordinates to a 
 bafe, on which he fet off the diftances from a fixed 
 point ; he then drew the moft regular curve that he 
 could through the fummlts of thefe ordinates. This 
 method {hews, in the moft paljjable manner, the coin- 
 84 cidence or irregularity of the experiments. 
 Spheres, The refult of the wliole was, that the mutual repul- 
 
 when clec- f^^^ ^f ^^^.^ fn^eres, eleftrified pofitlvely or neffatively, 
 pel with a "'^ "^'■y nearly m the mverfe propoition ot the Iquares 
 force pio- of the diftances of their centres, or rather in a propor- 
 (.ortional ^ I 
 
 I tion fomewhat greater, approaching to 7^. No dii- 
 
 ference was obferved, although one of the fpheres was 
 much larger than the other ; and this circumftance 
 enables us to make a confiderable improvement on the 
 eledlrometer. Let the ball A be made an inch in dia- 
 meter, while B Is but jth of an Inch. This greatly dimi- 
 iilfhes the proportion of the irregular adions of the reft 
 of the apparatus of the whole force, and alfo diminlflies 
 the diDipatlon when the general intenfity Is the fame. 
 AnJattrad When the experiments were repeated with balls ha- 
 iccordi-g vlng oppofite eleftrlclties, and which therefore attrac- 
 tn the fame ted each other, the refults were not altogether fo re- 
 gular, and a few irregularities amounted to ^^th of the 
 whole ; but thefe anomalies were as often on one fide of 
 the medium as: on the other. This ferics of experi- 
 ments gave a refult which deviated as little as the for- 
 mer (or rather lefs) from the Inverfe duplicate ratia of 
 the diftances ; but the deviation was in defeil as tlie 
 other was in excefs. 
 
 We therefore think tliat it may be concluded, that 
 the a£Uoa between two fpheres is exaftly in the inverfe 
 
 law. 
 
 duplicate ratio of the diftance of their centres, and that 
 this difference between the obferved attraftions and re- 
 pullions is owing to fome unperceived caufe in the form 
 of the experiment. gg 
 
 It mull be obferved alfo, that the attraAions and Attracflionj 
 rcpulfions, with the fame denlity and the fame diftances, ""^ repul- 
 were, to all fenfc, equal, except in the forementioned "'"'I'* 
 anomalous experiments. The mathematical reader will qual dif. 
 fee that the above-mentioned irregularities arc imper- tances. 
 feiftlons of experiment, and that the gradations of this 
 funftion of the diftances are too great to be much af- 
 fected by fnch fmall anomalies. The indication of the 
 law is preclfe enough to make it worth while to adopt 
 it, in the mean time, as n hypothefis, and then to fcledt, 
 with judgment, fome legitimate confequences which will 
 admit of an exa£t comparifon with experiment, on fo 
 large a fcale, that the unavoidable errors of obfervation 
 fhall bear but an infignlficant proportion to the whole 
 quantity. We ftiall attempt this: and it is peculiarly 
 fortunate that this obferved law of aflion between two 
 fpheres gives the moft eafy accefs to the law of aftion 
 between the particles which compofe them ; for Sir Ifaac 
 Newton has demonftrated (and It is one of his moft preci- 
 ous theorems), that If the particles of matter aft on each 
 other with a force which varies in the inverfe duplicate 
 ratio of the diftances, then fpheres, confiftlng of fuch 
 particles, and of equal denfity at equal diftances from 
 the centre, alfo aft on each other with forces varying 
 in the fame proportion of the diftances of their centres. 
 He demonftrates the fame thing of hollow fpherical 
 fltells. He demonftrates that they aft on each other 
 with the fame force as if all their matter were collefted 
 in their centres. And, laftly, he demonftrates, that if 
 the law of aftlon between the particles be different from 
 this, the fenfible aftlon of fpheres, or of hollow Iphcrical 
 fhells, will alfo be dllferent (fee Prindpia, I. Prop. 74, 
 &c. alfo Astronomy, Encycl. 307.) g. 
 
 Therefore we may conclude, that the law of eleftficEIecirk ^c. 
 attraftion and repullion is fimllar to that of gravitation,""" ■* '"- 
 and that cich of ihofe forces diminifties in the fame pro-Xf"^ « y a* 
 portion that the iquare ot the diftance between the par-f,f ,he dif- 
 ticles Increafe. We have obtained much ufeful Informa-tance. 
 tion from this difcovery. We have now full confirmation 
 of the propofitions concerning the mutual aftlon of two 
 bodies, each overcharged at one end and undercharged 
 at the other. Their evidence before given amounted 
 only to a reafonable probability ; but we now fee that 
 the curve luie, whole ordinates reprefent the forces, is 
 really convex to the abfcifla, and that Z -f- ss' is always 
 greater than Z' + a ; from which circumftance all the 
 reft follows of courfe. 90 
 
 Let us now enquire Into the manner in which thel^''P"''''°'* 
 redundant fluid, or redundant matter, is diftrlbuted '"fiuM'when 
 bodies; the proportion in which it fubfifts in bpdieSredundant 
 communicating with each other; the tendencies to or deficient, 
 efcape ; the forces which produce a transference, &:c. &c. 
 
 In the courfe of this enquiry, 3 continual reference 
 will be made to the following elementary propofition : .j 
 
 Let ABD (Gg. 17.) be the bafe of a cone or pyra- Lemma, 
 mid, whofe vertex is P, and axis PC ; and let abd be 
 another feftion of it by a plane parallel to the bafe ; let 
 thefe two circles, or fimilar polygons, confift of matter 
 or fluid of equal and uniform denfity ; and let P be a 
 particle of fluid or matter ; the attraftion or repulfion 
 of this particle for the whole matter or fluid in the fi- 
 gure ABD is equal to its attraftion or repulfion for 
 
 the
 
 ELECTRICITY. 
 
 581 
 
 ifie whole mstter ot fluid in a i d. For the attraftion 
 for a particle in ABD is to the attradion for a particle 
 fiinilarly placed in <? * J as P c' to PC ; and the number 
 c.f particles in ABD is to that of thofc in a b t/ as PC 
 to Pf'; therefore the whole attraflion for ABD is to 
 that for a Alias Pc'y. PC to PC X P c', or in the ra- 
 tio of equality. 
 
 Cor. I. The fame will lie true of the aib'on of plates 
 of equal tliicknefs aiul equal denfity ; or, in general, 
 having fuch thicknels and denfity as to contain quan- 
 tities of matter or lluid propoitional to their areas. 
 
 2. The aftion of all fuch ftdions made by parallel 
 planes, or by planes equally inclined to their axis, are 
 tqiial. 
 
 3. The tendency of a panicle P to a plane, OT plate 
 of uniform thickncls and denfity, and infinitely extend- 
 ed, or to a portion of it boundid by the fame pyramid, 
 is the fame, at whatever dillance it lie placed trom the 
 plate, and it is always perpendicular to it. 
 
 4. This tendency is proportional to the denfity and 
 thicknefs of the plate or plates jointly. 
 
 It is only in two or three fimple cafes that we can 
 
 propofe to ftate with piecifion what will be the difpo- 
 
 fition and aftion of the eltdric fluid in bodies ; but we 
 
 fliaii feleft thofe that are mod iiillruftive, and connected 
 
 01 with the moil remarkable and important phenomena. 
 
 DJfp.ifiiion Let A a dH (fig. 18.) and E c i H reprefent the 
 
 in parallel fedlions of a part of two infinitely extended parallel 
 
 plates (which we fliall call A and E), confiding of folid 
 
 conducing matter, in which the eltftric fluid can move 
 
 without anyobitruftion,but from which it cannot efcape. 
 
 When both Fir/I, Let them be both overcharged, A containing 
 
 the quantity r cf redundant fluid, and E containing 
 
 the quantity s, and let r be greater than s. 
 
 The fluid will be difpofed in the following manner: 
 
 1. There will be two ftrata, A c i B and G g /} H, 
 
 adjoining to the remote furfaces, in each of which 
 
 r -f- J 
 the quantity will be crowded together as clofe as 
 
 poffiblc. 
 
 2. Adjoining to the interior furface (that is, the fur- 
 face nearell to E) of the plate A, there will be a ftra- 
 
 . r — s 
 turn C c d D, containing the quantity crowded 
 
 together. 
 
 3. The adjacent fide of E will have a ftratum E efY, 
 
 , r — s 
 juft fuflicient for containing the quantity at its 
 
 natural denfity. This ftratum will be entirely exhaufted 
 of fluid. 
 
 4. The fpaces B 3 c C and F/^ G will be in their 
 natural fi:ate. 
 
 For a particle of fluid in the fpace B i c C is urged 
 
 r + s 
 
 in the direftion a ^ by the force • (n° 91, 3.), 
 
 with the force 
 
 Thefe make a force r which ba» 
 
 flates. 
 
 are over- 
 
 thar^cd, 
 
 lances the repulfion r of the other plate. No other dif- 
 pofition will b« permanent } for if a particle be taken 
 out from either ftratum Aab^ or QcdT> into the 
 fpace between them, the repulfion trom that ftratum 
 which it quitted is leflened, and ; he repulfion of the 
 trppofite ftratum. joined to that of the other plate, will 
 drive it back again. The lame thing holds with refpedt 
 to the fluid in the other plate. 
 
 Cor. 1. If the two pkites be equally overcharged, all 
 the redundant fluid will be crowded on the remote fur- 
 faces, and the adjacent furfaces will be in the natural 
 ftate. 
 
 In the yfront/ place, let the plates be undercharged, 
 and let r be the fluid wanting in A, and s the fluid 
 wanting in E, and let s be greater th.in ;■ ; then, 
 
 1. The ftrata adjoining to A a and H h will be 
 
 completely exlvaufted of fluid, and the rcdu.idant mat- 
 
 /• + f 
 
 ter in each will be fuch as would be faturated by . 
 
 ' 2 
 
 2. The ftratum Q, c dT) will contain redundant fluid 
 
 , crowded clofe. 
 
 2 
 
 3. The ftratum Y. efY will be deprived of fluid, and 
 
 J- — r 
 the quantity- abftrafted is . 
 
 4. The fpaces B i «• C and Yfg G are in the natu- 
 ral ftate. 
 
 The demonftration is the fame as in the former cafe. 
 
 Thirdly, Let A be overcharged, and E underchar- 
 ged, A containing the redundant fluid r, and E want- 
 ing the fluid J- ; and let r be greater than /. Then, 
 
 I. The ftrata A a i B and G^ 16 H contain the re- 
 
 . r — J 
 dundaut fluid , crowded clofe. 
 
 n- 
 
 94 
 
 When they 
 are under- 
 charged. 
 
 95 
 When they 
 are in op- 
 
 pofuc dates, 
 
 r +, 
 1 
 
 z 
 
 2. The ftratum C c d D contains the quantity 
 
 crowded clofe. 
 
 3. The ftratum E e/F is exhaufted, and wants the 
 
 . r + s 
 quantity . 
 
 4. The reft is in the natural ftate. 
 
 Cur. 2. If the redundant fluid in A be juft fufflcient 
 to faturate the redundant matter in E, the two remote 
 furfaces will be in their natural ftate, all the redundant 
 fluid in A being crowded into the ftratum C c d D, 
 and ail the redundant matter being in E efV. 
 
 This difpofition will be the fame, whatever is the 
 diftance or thicknefs of the plates, unlefs the redundant 
 fluid in A be more than can be contained in the whole 
 of E when crowded clofe. 
 
 When the two plates arc overcharged, the fluid 
 
 96. 
 
 and in the direftion d a hy the force , therefore 
 
 it is, on the whole, urged in the direftion a i/with the 
 force s, which will balance the r<pulCon of the redun- 
 dant fluid in the other plate. A particle of fluid in 
 the fpace F fg G is repelled in the diieftion A ? by a 
 
 force — - — by the fluid in G ^ A H, and it is attradled 
 in the fame direAion by the redundant matter in E <r/F, 
 
 preflTes their remote furfaces with the force 
 
 r + s 
 
 , and 
 
 would efcape with that force if a paflage were opened. 
 It would enter the remote furfaces of two undercliar- 
 ged plates with the fame force ; and, in either cafe, 
 
 it would run from the inner furface of one to the ad- 
 
 3 
 
 jacent furface of the other, with the force . 
 
 97 
 Preffure 
 and ten- 
 dency to ۥ 
 fcape. 
 
 If one be overcharged and the other undeicharged, 
 fluid wotild «fcape from the remote furface with the 
 
 forge
 
 582 
 
 ELECTRICITY. 
 
 and would run through a canal between 
 
 them with the force 
 
 r + / 
 
 'tions. 
 
 98 
 Difpnlitirtn 
 in afpherc. 
 
 They repel or attraft each other with the force r -^ s 
 acGordiiii^ as they are both over or undercharged, or as 
 one is overcharged and the other undercharged. 
 
 This example of parallel plates, infinitely extended, 
 is the fimplett that can be fuppofed. But it cannot 
 obtain under our obfervation ; and in all cafes which 
 we can obferve, the fluid cannot be uniformly fpread in 
 any llratum, but mull be denfer near the edges, or near 
 the centre, as they are overcharged or undercharged. 
 
 Let ABD (fig. 19.) reprefent a fphcre of perfeftly 
 conducing matter, overcharged with eleftric fluid, 
 which is perftftly moveable in its pore.i, but cannot 
 efcape from the fphere. Let it be furrounded by cou- 
 • duftin.o- matter faturated with moveable fluid. _ It is re- 
 quired to determine the difpoiuion of the fluid within 
 and without this fphere. 
 
 Sir Il'aac Newton has demonftrated {Print-. I. 70.) 
 that a particle/, placed anywhere within this fphere, 
 is not affefted by any matter that is without the cpn- 
 rentric fpherical furface/> y r in which itfelf is lituated, 
 therefore not affefted by what is between the furfaces 
 ABD and/ g r. He alfo demonftrates, that the mat- 
 ter within the furface/ g r aifts on the particle/ in the 
 Tame manner as if the whole of it were coUefted in the 
 centre C. 
 
 Hence it follows, that the redundant fluid will be 
 all conftipated as clofe as poflible within the external 
 furface of the fphere, forming a fliell of a certain mi- 
 nute thicknefs, between the fpherical furfaces ABD 
 and al/d ; and all that is within this (that is, nearer 
 the centre C) will be in its natural ftate. 
 
 With refpeft to the diftribution of the fluid in the 
 furrounding matter, which we fuppofe to be infinitely 
 extended, we muft recoUedl that this Ihell of conftipa- 
 ted redundant fluid repels any external particle of fluid 
 in the fame manner as if all were colkaed at C. Hence 
 it is evident, that the fluid in the furrounding matter will 
 be repelled, and, being moveable, it will recede from 
 this centre ; and there will be a fpace all round the 
 Jphere ABD which is undercharged, forming a fliell 
 between the concentric furfaces ABD and « « J. This 
 fnell will contain fuch a quantity of redundant matter, 
 that its attraction for a particle of fluid is equal to the 
 repulfion of the fliell of fluid crowded internally on the 
 furface ABD. All beyond this I'urface « /3<f will be in 
 its natural ftate ; for this redundant matter adfs on a 
 particle of fluid, fituated farther from the centre, in the 
 fame manner as if all this redundant matter were col- 
 ledled in the centre C. So does the redundant fluid 
 in the conftipated fliell. Therefore their aftions ba- 
 lance each other, and there is no force exerted on any 
 particle of fluid beyond this deficient fliell. This de- 
 ficient fliell will not aff'eft the fluid in the fphere a b d 
 by Newton's demonftration. No other difpofition will 
 be permanent. But farther : This undercharged fliell 
 n.uft be completely exhaufted : for a particle of fluid 
 placed between ABD and ""5 <r will be more repelled 
 by the fluid in the crowded fliell within the furface 
 ABD, than it is attrafled by the redundant matter of 
 Its own fliell that is lefs remote from the centre ; and 
 
 79 
 
 it is nut iidcdled by what is more remote from the 
 centre. Therefore the fluid without the fpheic ABI> 
 cannot be in equilibrio, unlcfs the fticll between ABD 
 and » /5 ■? be not only rarefied, but altogether exliaufted 
 of fluid. 
 
 If the fphere be undercharged, the fpace between 
 ABD and a b d will be entirely exhaufted of fluid, and 
 there will be a fliell ^ f> ^ o{ redundant matter lurround- 
 ing the fphere. r\ll within a b d, and all without ''•3'*'. 
 will be in its natural ftate. It is unneccffary to repeat 
 the ftcps of the fame demonftration. 
 
 This valuable propolition is by the Han. Mr Caven- 
 difli. 
 
 This would be the dilpofition in and about a glaf» ConP quen. 
 globe filled and furrounded with an ocean of water, '".''' "f '^''' 
 and having redundant fluid within it, on the fuppofition"'''^^'"''"'*"' 
 that glafs is impervious to the eleclnc fluid. But it 
 would nut aflfett an eledrometer, even fuppofing that 
 the movements of the eleftrometer could be eifeded 
 under water. Suppofe the globe of water to be fur- 
 rounded with air, and that the fluid is diipofed in both 
 in the manner here dtfcribed ; it will be perfedlly neu- 
 tral in its action on any elcftrometer fituated in the air. 
 But, by reafon of the almoft total immobility of the fluid 
 in pure dry air, this ftate cannot foon obtain; and, till it 
 obtain, the conftipated fliell within the glafs muft repel 
 the fluid ill an eleflrometer more than the partially ra- 
 refied fliell of air, which lurrounds the glafs, attradfs it. 
 By the gradual retiring ot the fluid in the furrounding 
 air from the globe, the attraftion of the deferted mat- 
 ter will come nearer to equality with the repulfion of 
 the conftipated fliell within the glafs, and the globe will 
 appear to have loft fluid. Yet it may retain all the re- 
 dundant fluid which it had at the firft. Therefore wc 
 are not to imagine that a body fimilar to this globe has 
 no redundant eleftric fluid, or only a fmall quantity, 
 becaufe we obferve it inactive, or nearly fo. 109 
 
 Thus we fee, as we proceed, that the iEpinian theo-Veiilied 
 rv is adequate to the explanation of the phenomena. ^^ '''^ P"** 
 But we lee it much more remarkably in a very tamiliar £ijjCjfi|. 
 and amufing experiment, uiually called the electric Well ex- 
 WELL. See Electricitt, Encycl. Seft. x. 4. plained. 
 
 To fee it in perfei^lion, make a glafs veflel of globu- 
 lar Ihape, with a narrow mouth, futficiently wide, bow- 
 ever, to admit an cledfromeier lulpendtd to the end of 
 a glafs rod of a crooked form, fo that the eleftrometer 
 can be prefented to any part of the infide. Smear the 
 outfide of the globe with fome tranfparent clammy 
 fluid, fuch as fyrup. Set it on an infulating ftand (a 
 wine glafs), and eledrify it pofitively. Hold the elec- 
 trometer near it, anywhere without, and it will be 
 ftrongly affedled. Its deviations from the perpendicu- 
 lar (if the ball of the eleftrometer has alfo been eletlri- 
 fied) will indicate a force inverfely as tlie fquare of the 
 diitance from the centre of the globe, pretty exaAly, 
 if the thread of the eleftrometer is of filk. Now let 
 down the eleftrometer into the infide of the globe. It 
 will not be affefted in any fenfible degree, nor approach , 
 
 or avoid any body that is lying within the globe. The 
 eleftrometer may be held in ail parts of the globe, and 
 when brought out again, is perfeftly inaftive and neu- 
 tral. But if the balls of the eleftrometer be touched 
 with a wire, while hanging free within the globe, they 
 will, on withdrawing the wire, repel each other ; and 
 when taken out, they will be found negatively eleftri- 
 
 fiftd.
 
 ELECTRICITY. 
 
 fietl. The experJmetit fiiccee'!s as well with a metal for beginning the computation at the extremity of the 
 jrlobe ; nay, even although the mouth be pretty wide ; prime conduftor. It certainly (hould not have been 
 iu which cafe, there is not a perfcft bnlance ol aftion ^ *' ■• " ■' *' " i.a. _ i .. 
 
 583 
 
 lol 
 
 EleiaHc 
 bodies are 
 
 from the extremity. Had the prime condu6lor been a 
 fmgle globe, it (hould have begun from the centre of 
 this globe. If it was of tiie iilual fi>rm, with an out- 
 ftr.nding wire, terminated by a large ball, the aftion of 
 the body of the conduftor fliould certainly have been 
 taken into the account. In (hort, almoi't aijy point of 
 the long conduftor might have been accommodated to 
 his Lordfhip's theory. 
 
 We might now proceed to inveftigatc the didribntion 
 of the eleftric fluid in bodies expolcd to the aftion of 
 others, and particularly in the oblong conduftors made 
 ufe of in our preparatory propolitioas. The problem 
 
 in every diredtion. The cleitrometer may be made to 
 touch the bottom of the globe, or anywhere not too 
 near the mouth, without acquiring any fcnfible eledri- 
 city J but if we touch the oiilfide with the eledtrome- 
 ter, it will inftantly be eledrified and ftrongly repelled. 
 Deep cylinders, and all round veflels with narrow 
 mouths, exhibit the fame fiiintncfs of cleftricity within, 
 
 except near the brims, although llrongly eledric with- We might now proceed to invefligatc the dillribution 104. 
 out ; and even open metal cups have the interior elec- 
 tricity much diminillied. 
 
 Refletting on this valuable propofition of Mr Caven- 
 
 dif^' ^'^ f"^"^ clearly why an overcharged eleftric is only is determinate, when the length and diameter of cylin- 
 
 mlyfyil'e!- fuperhcially fo ; and that this will be the cafe even al- dric conduftors are given ; but even when the eleftric 
 
 fcially fo. though we attempt to accumulate a great quantity of employed for inducing the elcftricity is in the form of 
 
 eleftricity in it, by melting it in a thin glais globe, and a globe, we mud employ funftions of the diftances that 
 
 eleftrifying it while liquid, and keeping up the accu- are pretty complex, and oblige us to have recourfe to 
 
 mulatino- force till it becomes quite cold. TThe prefent fecond fluxions. The mutual aftions of two oblong 
 
 writer, not having confidered the fubjeil with that ju- conduftors, of confiderable diameters, give a problem 
 
 dicious accuracy that Mr Cavendifli exerted, had hopes that will occupy the firll mathematicians; but which is- 
 
 of producing a powerful and permanent eleftric in this quite improper for this fcanty abftraft. Nor is a minute 
 
 way, and was mortified and puzzled by the difappoint- knowledge of the difpolition of the fluid of very im- 
 
 ment, till he faw his miftake on reading Mr Cavcndilh's portant fervice. We may therefore content ourfelves 
 
 diflertation. with a general reprefentation of the ftate of the fluid in 
 
 Cautions in Thefe obfervations alfo point out a thing which the following manner, which will give us a pretty di- 
 
 certain ex- {hould be attended to in our experiments for difcover- ftinft notion how it will aft in mod cafes : 
 
 penments. ^^^ ^^le eieftricity excited in the fpontaneous operations Let A (fig. 20.) be an overcharged fphere, and BC General re- 
 of nature, as in chemical conipofition and decompofi- a condufting cylindric or prifraatic body ; draw ic pa-1;'"''^'"'^- 
 tion, congelation, fufion, evaporation, &c. It has been rallel to BC, and ereft perpendiculars B *, C c, P />. dj'fpofiti'nn 
 ufual to put the fubftances into glals, or other non- &c. to reprefent the equable deniity of the fluid, when ^,( the fluid, 
 condufting veflels, or into vefl"els which conduct very the conduftor is in its natural ftate ; but let B il, C r, 
 imperfectly. In this laft cafe cfpecially, the very faint P s, Sec. reprefent the unequal denfities in its different 
 cleftricity which is produced, inftantly forms a compen- points, while in the vicinity of the overcharged fpiiere. 
 fation to itfelf in the fubllance of the veff'el, and the Thefe ordinates muft be bounded by a line tin r, which . / 
 apparatus becomes almofl. neutral, although there may will cut the line lie in the point « of the perpendicular, 
 have been a great deal of eleftricity excited. It will drawn from the neutral point N of the conduftor. The 
 be proper to confider, whether the nature of the expe- whole quantity of fluid in the conduftor is reprefented 
 riment will admit of metalline veflels. In the experi- by the parallelogram BC c b ; which muft therefore be 
 yments on metalline folutlons, the beil method feems to equal to the fpace BC rn d / the redundant fluid in 
 be, to make the veflel itfelf the fubftance that is to be any portion CP or PN is reprefented by the fpaces 
 diflolved. c-r fj>, or I pn ; and the redundant matter, or deficient. 
 E!«iftricity For fimilar reafons we may coUeft, without a more fluid, in any portion BQ_^ is reprefented hy d v q. 
 more near- minute examination, th.at bodies of all fliapes, when The aftion of this body on any body placed near it, 
 lypropor- overcharged, will have the redundant fluid much denfer depends entirely on tiie area contained between this 
 ihTfurface "'^^■' ^^^ furface than in the Interior parts ,- and denfer curve line and its axis lie. The only circumftance that 
 thantotlie in all elevations, bumps, projeftions, angles, and near we can afcertain with rcfpeft to this curve is, that the 
 quantity of the ends of oblong bodies; and that, in general, the i>arlntions of curvu/ure in every point are proportionaJ 
 matter. quantity of redundant fluid, or redundant inatter, will to the forces exerted by the fphere A ; and are there- 
 be much more nearly proportional to the furfaces of fore inverfcly as the iqiiares of the diilances from A. 
 bodies than to their quantities of matter. All this is This property will be dcnionftrated by and bye. ThS 
 iully proved by experience. The experiment of the place ot n, and the magnitude of the ordinates, will va- 
 eleftrified chain is a very beautiful one. Lay a long ry as the diameter of the conduftor varies. We Ihall 
 metal chain in an infulated metal difli furniflied with an confider this a little more particularly in fome cafes 
 eleftrometer. Let one end' be held an inch or two which will occur afterwards. We may confider the 
 above the coil by a filk thread. Eleftrify the whole, fimplell cafe that can occur ; namely, when the conduc- 
 and obferve the divergency of the eleftrometer ; then, tor is, like a wii-e, of no fenfible diameter, nay, as con- 
 gradually drawing up the chain from the coil, the elec- taining only one row of particles. 
 
 trometer will gradually fail lower, and lowering the. Let AE (fig. 21.) be fuch a {lender condufting ca- In a very 
 
 chain again will gradually raife it. tial ; and let B b, C c, E e, &c. reprefent the denfity "'-'"''"■ '** 
 
 We now fee with how.little reafon Lord Mahon con- of the fl^uid which occupies it, being kept in this Hate „''. ! ^ _• 
 
 eluded that th.e point of his conduftor, obferved to be of inequable denfity by the repullion tor fome over- 1.^ al,„oft 
 
 neutral, correfponded with his theory ; namely, one of charged body. A particle in C is impelled in the di- equally di- 
 
 thc media of a harmonic divifion. We fee no reafon reftion CE by all the fluid on the lide of A, and in the IributeJ. 
 
 direftii)^ 
 
 103.
 
 584 ELECTRICITY, 
 
 direi5ion CA by all the fluid on the fide of E. The running of water in a fyphon by the pi'e,T;ire of the air, 
 moving force, therefore, arifes from the difference of While the repulfion of the redundant fluid in A allows 
 thefe repulfions. When the diameter of the canal is 
 
 conftant, this arifes only from the difference of denfuy. 
 The force of the clement adjacent to E nny therefore 
 be expreiTed by the excefs of D d above C c, and ir.e 
 aftion at the diftance CD jointly. Therefore, draw- 
 ing /3 c I parallel 10 AE, tlw's force of the element E 
 
 the bend of the fyphon neareft to A to retain fluid, a 
 current ihould take place from B along the ihort leg, 
 in confequence of the Uiperior attion on the fluid in 
 the long leg. But if the lepnlfion of A can drive tlie 
 fluid out of the bend between B and F, Mr Cavtndifh 
 thinks, that it does not appear that fluid will come 
 up from B in oppofition to the repullion of A, and 
 
 will be expreffed by — x, repelling the particle in the ^),g„ ^un along to"D. But fluid does not move, in ei 
 direftion CA. If CF be taken equal to CD, the force 
 of the element at F will be expreffed by — j x, or -jj- x, 
 alfo impelling the particle in the direftion CA. The 
 joint adion of thefe two elements therefore is jj — *. 
 
 I{ i c e were a ftraight line, we (hould have d ^ +/? al- 
 ways proportional to c ^ ; and it might be expreffed 
 
 ther of thefe cafes, on the principle of a fyphon ; bc- 
 caufe there is nothing to hinder the fluid fiom expand- 
 ing in the part EDF. /^nd we are rather diipofcd to 
 think, that it will always move from B, over the bend, 
 to C ; T"or even if the fluid can be completely driven 
 out of the bend EF, it mull be done by degrees, and 
 the fluid in the long leg will, from the very beginning 
 of the action of A, be more moved from its place tlian 
 that in the fliort leg ; and therefore will yield to the 
 
 \ 
 
 by mXc i ; m being a number exprefiing what part of comprefhon, which ads tranfverfely, and, by thus yield 
 
 c^ the fum oi d i and^> amounts to (perhaps -r^th, or ~ ' ■ ~ 
 
 ,'j5-th, or -r^ith, Sec). But in the cafe expreffed in the 
 
 figure,//" does not increafe fo fall as c J, and/j. iu- 
 
 creafes fallcr than c s. However, in the immediate 
 
 neighbourhood of any point C, we may exprels the 
 
 III L o * 
 
 acceleratincr force tending towards A by x, with- 
 
 out any fenfible error ; that is, by m 
 
 that is, by 
 
 the fluxion of the area of a hyberbola HD'G, haying 
 CC and CK for its affvmptotes ; and the whole ac- 
 tion of the fluid between F and D, on the panicle C, 
 will be exprelTed by the area C'CDD'H. Hence it 
 follows, that the aftion of the fmallell conceivable por- 
 tion of the canal immediately adjoining to C on both 
 fides, or the difi"L-rence of the actions of the two ad- 
 
 ing more toward F than toward E, the fluid will rulh 
 through the contracted part, and go into C. We do 
 not fay this with full contidence ; but are thur. particu- 
 lar, on account of an important ufe that may be made 
 of the experiment. For if the body A be underchar- Propofal 
 ged, fluid will certainly be attrafted from C, and pafsfordilct.ver- 
 over the bend into B, however great the action of A '''2 reiiun- 
 may be. Perhaps this may be fo contrived, therefore, o!"j ' " 
 as to decide the long agitated quellion, IVhe/her (he elec- 
 tricity ef excited glaj's be plus or minus ? If it be found 
 that this apparatus, being prefented to the rubber of 
 an eletlrical machine, diminifhes the politive eleclricity 
 of C, and increafes tii.u of B ; but that, prefeiiting tiie 
 fame apparatus to the prime conductor, makes little 
 change — we may conclude, that the electricity of the 
 prime conductor is pofitive. We have tried the expe- 
 
 loS 
 Communi- 
 catnn and 
 -transfer- 
 ence by 
 canals. 
 
 nment, paying attention to every circumit.ince that 
 joining elements, is equal to the action of all beyond it. feemed likely to infure fuccefs ; but we have aKvavs 
 This fhews, that the ftate of compreflion is hardly af- fQ^^J hitherto, that the app.ir;.tus was equally aff'tdted 
 
 by both elcdtricitics. 
 
 We mufl now confider the aftion of electrified bo- 
 dies on the canals of communication ; becaufe this will 
 give us the caficll method of alcertaining the propor- 
 tion in which the expelling fluid is diltributed between 
 them. For when tv/o bodies communicate by a canal, 
 and have attained a permanent Hate, we mull conceive 
 that their oppofite aC\ions on the fluid moveable along 
 this canal are in equilibric, or are equal. This will 
 generally be a much eaher problem tliaii their aftion on 
 each other, fince we have feen a little ago, that the 
 fluid in a flender canal is of uniform denlity very near- 
 ly. A very few examples of the molt important of 
 the fimplc cafes mult fulFice. i^g 
 
 Therefore let AC a (tig. 24.) reprefent the edge of Aftion of a 
 a thin conducting; circular plate, to which the flender p!ate on a 
 
 fefted by any thing that is at a fenlible diftance from 
 C ; and that the denfity of the fluid, in ar. indcflnit<.ly 
 {lender canal, is, to all fenfe, uniform. The geometer 
 will alfo fee, that the fecond fluxion of D 1/ is propor- 
 tional to the force of the diilant body. We learn, 
 therefore, fo much of the nature of the curve b c e. — 
 ^Coulomb). 
 
 We are now in a condition to examine the commu- 
 nication of eleftricity by means of conducting canals 
 (which is one of the moll important articles of the ftu- 
 dy,) having found that the fluid, in a very flender ca- 
 nal, is very nearly of uniform denfity throughout. 
 
 There can be no doubt but that, if a body C (fig. 
 22.) be overcharged or undercharged, any other body 
 C, which communicates with it by a condufting canal, 
 will alfo be overcharged or undercharged. It is as evi- 
 dent, that if a body, in any Hate of eleftricity, be in 
 the neighbourhood of an overcharged or undercharged 
 body A, while it communicates with C by a canal lead- 
 ing from the fide moil remote from A, fluid will be 
 driven from B into C, or abllracled from C into B. 
 By crooked It is not, however, fo clear, that when the canal 
 eanale. leads from the fide neareft to A (as in fig. 23.), fluid 
 will be driven from B into C. AVe conceive the fluid 
 to be moveable in the body and in this canal, but not 
 to efcape from it. Its motion, therefore, in this cafe, 
 .fhould, in the opinion of Mv Cavendilh, referable the 
 
 109. 
 
 canal CP is perpendicular in the centre. It is required "'^^'.'■'^ 
 to determine the adtion of the matter or fluid, uniform- 
 ly fpread over this plate, on the fluid moveable in the 
 canal PC ? 
 
 I. Required the adtion of a particle in A on the 
 fluid ill the whole canal? Join AP ; and call CP .v, 
 AP y, and AC r ; and lety exprefs the intenfity of ac- 
 tion at the diilance 1, or the unit of the fcale on which 
 the lines are meafured. 
 
 / 
 
 The adtion of A on P, in the direftion AP, is — . 
 
 This,
 
 ELECT 
 
 This, wlien eftiniated in the direftion CD, is reduced 
 to-=^X — ; and is therefore =/-3-. Therefore the 
 fluxion of the aftion, in the direftion CP, on the whole 
 canal, is / — k = A^ ( becaufe x iy := y ; x) = />i 
 
 y y 
 
 ^. The variable part of the fluent is =:/~II—, and 
 
 585 
 
 the complete fluent is =:/(C — — ), where C 
 
 y / 
 
 13 a con- 
 
 ftant quantity, accommodated to the nature of the cafe. 
 Now, the adllon mull vjjnidi when the canal vanilhes, or 
 
 I 
 
 r 
 
 when X = o, and y = r. Therefore C — — = 0, and 
 C = — ; and the general expreflion of the aftion is / 
 
 lal. 
 
 ), =:f^ , exprefling the aftion of a par- 
 
 / , y ' , ^y 
 
 tide in the circumference of the plate on the fluid in 
 the whole canal CP. 
 
 2. Required the aftion of the plate, whofe diameter 
 
 ,,0 is A a, on the particle P ? 
 
 :. On a fin- Let a reprefent the area of a circle, whofe diameter 
 
 n't hTc?-'*^ is = I . Then a r' is the area of the plate, and 2 a r r 
 
 is the fluxion of this area: becaufe r :y =z y : r, zarr 
 
 is = 2 ay y. Therefore the fluxion of the adion of 
 
 X 
 
 the plate on the particle P is /X 2 ayy X -y =z 2 fa 
 
 X X ^. The fluent of this has for its variable part 
 
 J'' 
 
 2 f a xY. (for when the particle P is given, x does 
 
 ^ y ,. . —X 
 not vary). This is = 2fay. . To complete this 
 
 fluent, we rouft add a conftant quantity, which (hall 
 make the fluent = o when the particle P is at an in- 
 finite diftance ; and therefore when x =: y. Therefore 
 
 i = o, or r — — = o, or C = I ; and the com- 
 
 y y y 
 
 plete fluent for the whole plate is 2/ a ( i — —]. 
 
 y' 
 
 III. The meaning of this expreflion may not occur to the 
 
 reader : For i — - is evidently an abftraft number ; fo 
 
 y 
 is a. Therefore the expreflion appears to have no refe- 
 • rence to the fize of the plate. But this agrees with the 
 obfervation in n° 91. where it was fliewn that, provided 
 the angle of the cone or pyramid remained the fame, 
 the magnitude of the bafe made no change rn its at- 
 traftion or repulfion for a particle in the vertex. 
 
 . X 
 
 It will appear by and bye, that i — - is a meafure 
 
 or fun£lion of a certain angle of a cone. 
 
 Cor. If PC be very fmall in proportion to AC, the 
 a£lion is nearly the fame as if the plate were infinite : 
 
 For when the plate is infinite, — is =: o, and the ac- 
 
 , . y 
 
 tion is = I, whatever is the dillance (fee n°Qt — 93.) 
 Therefore, when x is very fmall in coraparifon of r, and 
 
 confequently oi y, i is very nearly = 1. 
 
 Surn-. Vol. I. Part II, 
 
 in 
 
 2. On 'he 
 w'lole ca- 
 nal. 
 
 R I C I T Y. 
 
 3. To find the aftion of the plate on the whftle co- 
 lumn ? 
 
 The fluxion of this muft be = 2/ a X (i — ~ ) •» 
 
 or 2 f a [x — "^j, or i f a X ( » — y) ; becaufe ji = 
 — ; — The fluent of this has for its variable part 2fn 
 
 y 
 
 X (x — y)- A conftant quantity muft be added, 
 whicli ftiali make it = o when the column = o j th.it 
 is, when y =: r, and .v := o ; that is, C — r = o, and 
 C =: r. Therefore the complete fluent is =r zfu (.v -f- 
 
 '■"•''■ , . ' "J 
 
 Thus we have arrived at a moft fimple expreflion ofOeomrtri- 
 
 the attraftion or repullion of a plate for fuch a c',>lumn,<;a! cxprcf- 
 or for portions of fuch a column. And it is moft ea-lT." ""''''' 
 fily conftrufted geometrically, fo as to give us afenfible 
 image of this attion of eaiy (./-nception and remem- 
 brance. It is as follows: Produce PC till CK = CA, 
 and about the centv? P di^fcrib^ the arch AI, cuttniir 
 CK in I. Then 2 fa X IK is evide;.''y the giometn- 
 cal expreflion of the attraction or rejjlfion. This ij 
 plainly a cylinder, whole radius is a unit of the fcale, 
 and whofe height is twice IK. 
 
 In like manner, by defcribing the arch A« round the 
 centre p, we have 2 fa X i K for the aflion of the plate 
 on the fmaU column C/> ; and ifaY. I/' is the adtion 
 of the plate on the portion P^. 
 
 The general meaning of the expreflion 2 fa X IK is, 
 that the aftion of the wliole plate on the column PC 
 is the fame as if all the fluid in the cylinder a X 2 IK, 
 were placed at the diftance i from the afting par- 
 ticle. 
 
 From this propofition may be eafdy deduced fome 
 very ufeful corollaries by the help of the geometrical 
 conftruftion. 
 
 1 . If PC be very great in comparifon with AC, the 
 aftion is nearly the fame as if the column were infinite- 
 ly extended ; for in this cafe IK is very nearly =: CK, 
 the difference being to the whole nearly as AC to twice 
 AP. 
 
 2. If, in addition to this laft condition, another co- important 
 lumn/>C be very fmall in comparifon of AC, then the corollary. 
 a£lion on PC is to that on / C vei-y nearly as ^ C to 
 
 AC. For it will appear that < K : IK = /> C : AC very 
 nearly. It is exaftly fo when CP : CA = CA : C/) ; 
 and it will always be in a greater proportion than that 
 of/CtoIK. 
 
 This will be found to be a very important obferva- 
 tion. 
 
 The redundant fluid has hitherto been fuppofed to 
 be uniformly fpread over the plate : but this cannot 
 be ; becaufe its mutual repulfion will caufe it to be 
 denfer near the circumference. We have not determi- 
 ned, by a formula of cafy application, what will be the 
 variation of denfity. Therefore let us confider the re- 
 fult of the extreme cafe, and fuppofe the whole redun- 
 dant fluid to be crowded into the circumference of the 
 plate, as we faw that it muft be on the lurface of a 
 gl^be. ^^^ 
 
 In this cafe, the aftion on the fluid in the canal will A'ition oC 
 
 r' \ a circum- 
 
 be/a (r -y For the area of the plate is a r", and fc ence on 
 
 114. 
 
 "5 
 
 4E 
 
 the 
 
 a :an!>!.
 
 586 
 
 ELECTRICITY. 
 
 the aftion of a particle in the circumference on tlie 
 whole canalwas fhewn(n">i09.)to be//-!^ j. There- 
 
 fore the aftion of the whole fluid crowded into the cir- 
 
 ed at K on the column CP, is eafily had by taking 
 C / = KP. It is equal to the adion of ihc fame fluid 
 placed in A on the column C /. 
 
 Cor. 1. The aftion of all the fluid uniformly fpread, 
 exerted on the colunm CP, is to the aftion of the fame 
 fluid collefted in K, exerted on the column CL, as 
 zIKtoCD. 
 
 If the column CP is very great in proportion to AC, 
 the half breadth of the plate, the aftion in the firft cale 
 is very nearly double of the aftion in the other cafe. 
 Therefore the aftion is rcprefented by/mul- and is exactly in this proportion if CP is of infinite ex- 
 tent. 
 
 cumference lif a r' X- 
 
 r=fa> 
 
 It may 
 
 ry y 
 
 be reprefented as follows: Defcribe the quadrant Ci BE, 
 cutting A? and Ap in B and b. Dnw BD and b d 
 parallel to PC. Then PB = jp — r, and \:>C =. r 
 
 y — 
 
 IX J. 
 
 114 
 
 "7- 
 
 Cor. 3. If CNO be a fpherical furfaee or (hell of the Adion oj il 
 fame thicknefs and diameter as tiie plate A a, and con- P ^ 
 taininp- redundant fluid of the fame uniform denfity, thepj^n^ ^r fo. 
 aftion of this fluid on the column CL is double of theliJ.on ihe 
 aftion of the fluid uniformly fpread over the plate on fmie canal, 
 the column CP, and quadruple of the aftion of the fluid 
 collefted in the circumference : for the aftion is the 
 fame as if all were collefted in the centre K, and the 
 
 tiplying 3 cylinder, whofe radius is i and height is DC. 
 In like" manner, dC is the height of the cylinder corre- 
 fponding to the column^ C, and D d the height corre- 
 fponding to V p. 
 
 Cor. I. When CP is very great in comparifon with 
 CA, the point D is very near to A, and I is very near 
 to C, and CD is to IK nearly in the ratio of equality. 
 In this cafe the aftion of the fluid, uniformly fpread 
 
 over the plate, is nearly double of the aftion of the furfaee of the fphere is four times that of the plate, and 
 
 fame fluid crowded round the circumference ; for they therefoi;e they are as IK to 2 CD. 
 
 are as cylinders, having the fame bafes and heights in Let us now conlider the comparative aftions of uif- 
 
 the ratio of 2 IK to DC, which is nearly the ratio of fcrcnt plates or fpheres on the canals. 125 
 
 2 to I. If two circular plates, DE, dc (fig. 25.), or two A(5lion of 
 
 "8. 2. On the other hand, when the column / C is very fpherical fhells, ABO, a bo, of equal diameters and '"''"' P'^'"> 
 
 fhort, the aftion of the fluid fpread uniformly over the thicknefs with the plates, and containing redundant ?^j^^^°^_ ^^, 
 
 ' . plate is to its attion, when crowded round the circum- fluid of equal denfity, communicate with infinitely ex-a,their'ilia- 
 
 fercnce, nearly in the ratio of 4 AC to/C. For thefe tended fl:raight canals OP, op, paffing through theirmeteis,_ j 
 
 aftions are in the ratio of zfa X i K to if a X dC, or centres perpendicular to their furfaces, alfo containing when the 1 
 
 as 2JKtO(/C, or nearly as 2/C to dC, or more fluid uniformly diltributed and of equal denfity — ^^the"g^°^^y 
 
 nearly as 2 ^^to JC. "Siat C d -.b d = b d : b A. + Ad, repulfions will be as the diameters. For the repulfion |(j„g_ 
 
 or nearly = b d:2QA. Therefore Cd: zbd = pQ : of the fpherical furfaces is the fame .-s if all the fluid 
 
 4 CA nearly. were collefted at their centres; and the repulfionof 
 
 119. Hence we fee that the aftion on fliort columns Is the fluid uniformly fpread over the furfaces of the plates 
 
 much more diminlflied by the recefs of the redundant is double of its repulfion if colletfed at the centres of 
 
 fluid toward the circumference than that on long co- thefe fpheres ; it follows, that the repulfions of the 
 
 lumns. Therefore, any external eleftvic force which plates are proportional to thofe of the fpheres. But 
 
 btcaufe the itpulfion of a plate whole radius is r was 
 
 tends to fend fluid along this canal, and from thence to 
 fpread it over the plate, will fend into the plate a great- 
 er quantity of fluid than if the fluid remained ultimate- 
 ly in a ft.ate of uniform difl:ribution over its furfaee ; 
 and that the odds will be greater when the canal is 
 fliort. 
 Equivalent Llftb^ on this fubjeft. If KL be taken equal to 
 centre of AP, or PL be equal to KI, the repuUion which all the 
 aflion. fluid in the plate, collefted in K, would exert on the 
 fluid in the canal CL, is equal to the repulfion which 
 the fame fluid, confliipated in the circumference, w oiiM 
 exert on the column CP. For we have feen that the 
 aftion of a particle in A, on the whole column PC, 
 
 when eftimated in the diieftion PC, is •' ; ,and it 
 
 k well known that the aftion of a particle in K for the 
 
 column CL is 
 
 KC 
 
 I 
 KL' 
 
 There- 
 
 fliewn to lie = 2 a X r + * —y, and when th e column 
 is infinitely extended, x is equal to ^, and r + x — y 
 = r, it follows, that the repullions of the plates are as 
 2 rf X R and 2aXr, or proportional to their diameters. 
 Therefore the repulfions of the fpheres are in the fame 
 proportion. 
 
 Cor. 1. If tlie canals are very long in proportion to 
 the diameters of the plates or fpheres, the repidfions are 
 nearly in the fame proportion. __^ 
 
 Cor. 2. But as the lengths of the canak diminilh, tht rhe pro- 
 repulfions approach to equably ; for it was fliewii, that portion of 
 when the canal was very fmall, the repulfion was to'^f gr^'efl 
 that for an infinite column as the length ot the cana. to^^^j.^j^ |£ 
 the radius of tiie plate. Therefore if the radius cr the the canals 
 greater plate be (for examplt) double of that of theare ftiort. 
 fmaller, and the little column be ^'^th of the radius, it 
 will be To-th of the radius of the fmaller plate. Now 
 
 ii6. 
 
 IJ7 
 
 fore the aftion of the whole fluid, collefted in the cir- ^^_^]^ of half the repulfion is equal to V^th of the double 
 
 repulfion. Alfo, in the cafe of the fpheres, the repul- 
 
 fton of a particle at the furfaee is as the quantity of fluid 
 diijeftly, and as the fquare of the radius inverfely ; but 
 when the denfity is the iame in both fliells, the quan- 
 tity is as the furfaee, ov as the fquare of the radius. 
 Therefore the repulfions are equal. 
 
 Cor. 3. If the denfity of the fluid in two fpherical 
 ftjells be' inverfely as the diameters, the repulfions for an 
 
 infinitely 
 
 cumference, on the column CP, is equal to that of the 
 fame fluid, collefted in K, on the columns CL- 
 
 Cor. I. If the column CP Is very long in proportion 
 to AC or KC, the aftions of the fluids iu thefe two 
 different fituations are very nearly the fame. The ac- 
 tion of the fluid collefted in K exceeds its aftion when 
 collefted in A only by its aftion on the fmall and re- 
 mote colama LP. The aftion of all the fluid colleft-
 
 ELECTRICITY. 
 
 lit iiifim'tclv extended column of fluid arc equal; for each 
 A<Si ns of repels as if all the fluid was colleflcd in the centre, 
 **'"'^P''7^i Therefore, if the denfitv, and confequently the quan- 
 the .'tiifity '^'fy' ''* varied many proportion, the repullion will vary 
 beinverfely in the fame proportion. The repullions will now be 
 psthe.lia- J , .... 
 
 ineicr.s; as CO X k7^ to c o X — , or Ml the ratio of equality. 
 
 Or it the Cor. 4. When the quantities of redundant fluid in 
 
 q"si''|'y "f two fpherts are proportional to their diameters, their 
 redundant repulfions for an infinitely e.xtended canal are equal : 
 the didinc- f""" 'f ^l""" redundant fluid is coiiftipatcd in the furfaccs 
 ters. of the fphercs, as it always will be when they confilt of 
 
 conducing matter, the dcnfiti>.-s are as the diameters in- 
 verfely, beeaufe the furfaces are as the fquares ((f the 
 diameters. Therefore, by the laft corollary their ac- 
 tions on an infinitely extended canal are equal. But 
 in fnhrres of noncondiitting matter it may be different- 
 ly difpofed, in concentric fliells of uniform deniity. 
 This makes no change in the aftion on the fluid th^it 
 is without the fphere, Lecaufe each fliell adts on it as if 
 it were all collefted in the centre. Therefore the re- 
 pulfioiis are ftill equal. 
 _ Cor. J. Two overcharged fpheres, or fpheiicAl flails, 
 
 fplieres OAB, oab (fig. -26^, communicating by an infii.itely 
 overchar- extended canal of conducing matter, contain quant:- 
 ged in this tj,;^ ^f ijtdundant fluid proportional to their diameters ; 
 f^"'. ^ u'-^"'^ their aftions on the fluid in the !nterja>.ent canal 
 librl'i if mud be in tquilibrio, and therefi>re equal. This will 
 conimuiii- be the cafe only v.hen the quantities of fluid are in the 
 catinir liy apro]iorlion of their diameters. 
 
 ver) ui g When the canals are very long in proportion to the 
 diameters of the fpheres, the proportion of the quanti- 
 ties of redundant fluid will not greatly differ from that 
 of the diameters, 
 j,j_ Cur. 6. When the fpheres of coiidufling matter are 
 
 thus in equilibrio, the pvelfures of the fluid on their 
 furfaces are iuverfcly as their diameters ; for the repul- 
 fion of a particle at the furface is the fame with the 
 tendency of that particle from the centre of the fphere, 
 the aclions being mutual. Now this is proportional to 
 the quantity of redundant fluid direftly, and to the 
 fquare of the dlfl;ance from the centre inverfely, that is, 
 to the diameter direftly, and to the fquare of the dia- 
 meter inverfely, that Is, to the diameter inverfely. 
 Tendency Hence it follows, that the tendency to efcape from 
 of the fluid the fpheres Is Inveiitly as the diameter, all other cir- 
 toefcjjeis cumflances being the fame: for in as far as the efcape 
 
 'I]'"^y '^ '^ "' proceeds from mere eledlric reiiulCon, it muft follow 
 the dia- t- . T. , * . , r r , 
 
 lae'.er. '"'^ proportion, ijut there are evident proofs or tlie 
 co-operation of other phyfical caufes We obferve che- 
 mical compofitions and decompofitions accompanying 
 the efcape of clefirlc fluid, and its Influx into bodies : 
 we are Ignorant how far, and in what manner, thefe 
 operations are afifeiftcd by dlllance. Bofcovich fliews 
 moll convincingly, that the adllon of a particle (of 
 whatever order of compofition), on external atoms and 
 particles, is furprifingly changed by a change In the 
 diftance and arrangement of its component atoms, A 
 conft;ipaLion, therefore, to a certain determined degree 
 and lineal magnitude, may be neceflary for giving oc- 
 cafion to fome of thofe chemical operations that accom- 
 pany, and perhaps occafion, the efcape of the eleftric 
 fluid. If this be the cafe (and it Is demonjlrable to be 
 ^ poflible, if the operations of Nature be owing to attrac- 
 
 tions and repullions), the efcnpf mu/l be defultory. It 
 is dftually lo ; and tin's confirms the opinion. 
 
 587 
 
 The public is indebted to Mr Cavendifli for the pre- 
 ceding theorems on the aftion of fpheres jnd eircnl.ir 
 plates. He has given them in a more abflradt and ge- 
 neral form, apphcablc to any law of electric aftion 
 which experience may warrant. We have accommo- 
 dated them to tlie Invcrfe duplicate ratio of the dif- 
 tances, as a point tiitfieiently cltablilhed ; and we hope 
 that we have rendtred tiiem more fimple and perfpieu- 
 ous. We have availed ourielves of Mr Cuulunib's de- 
 monftratlon of the unitoriii denfity in the canal, with- 
 out which the theorems could not have been demon- 
 ftrated. The minute quantity of t'ue fluid in the ca- 
 nal can have no leiifible cfteil on the dilpofitlon or pro- 
 portion of the fluid in the plates or fpheres. 
 
 It may be thought that the lall corollary, refpefting rhispropo- 
 the equilibrium of two fplieres, is not agreeable to hy-tii ion agrees 
 drollatical principles, whicli require the equality of the •'■"'^ **''" 
 two forces which balance each other at the oriiiccs of/' ' *'"^ 
 the (lender cyliudric caiiai ; whereas, in that corollary, 
 the forces at the extremities ot the canal are iiivi iltly 
 as the diameters of the fplieres 01 plates. Tiiis would 
 be a valid objection, it tlie comprtlnng forces afted on- 
 ly on the extremities of the canals; but they aft on 
 every particle through their whole length. It is not, 
 therefore, the pivlfuie at one end of the canal that Is 
 in equilibrio with the preflure at the other end, by the 
 interpofition of th>: fluid. It is the prefTuve at one 
 end, together with the fum of all the intermediate pref- 
 fures in that dirc^ion, that is in equilibiic with all the 
 prefl"ure in the oppolite diredion. The prefliires at the 
 ends are only parts of tiic whole oppofite preffures ; 
 they are the firlt In each ace lunt. In this manner 
 a (lender J^ipe, having a ball at each end, may be kept 
 filled with mercury, while l)ing horizontal, if the air 
 In each ball is of equal deiinty. But if it be laifed per- 
 pendicular to the horizon, it cannot remain filled Irom 
 end to end, unleis the air of the ball below be made fo 
 elaftic by condcnfatlon, that Its preflTure on the lower 
 orifice of the pipe e>;ceed the prelfure of the air in the 
 upper ball on the other orifice by a force equal to the 
 weight of the raeicury, that is, to the a"-gieL;3te of the 
 aiSIon of gravity on each particle jf mercury in the 
 pipe. Therefore the repullions of the fpheres that we 
 are ("peaking of are in equilibrio by the itterventiou of 
 the fluid in the canal, in perfeft coiiilltency with tiie 
 laws ot hydrullatical prelfure. 
 
 Mr Cavendifli has purlued,this fubjeft much fahher, 
 and has confidered the mutual aftioii of more than two 
 bodies, communicating with each other by caiuds of 
 moveable fluid unitormly denfe. But as we have not 
 room for the whole of his valuable propofitions, we fe- 
 ledted thofe which were elementary and leading theo- 
 rems, or fuch as- will enable us to explain the moft Im- 
 portant phenomena. They are alio fuch, as that the 
 attentive reader will find no difticulty in the iiiveiliga- 
 tlon of thole which we have omitted. 
 
 Mr Cavendilh's mofl; general propofition Is as follows: General 
 
 When an overcharged body cotrimunlcates, by a ca-prnn fuion 
 nal oi very great length, llraight or crooked, with two* ''"■*■ • 
 oi-" more (lir.i)ar bodies, alfo at a very great dlflance n,'"'^' "/ '''' 
 from each other, and all are In eleftric equilibrium, and communi- 
 4 E I confequently eat.ng bo- 
 
 dica.
 
 i88 
 
 ELECTRICITY. 
 
 ^33 .^ 
 It is indif- 
 ferent ^Ahe 
 th.er the ca' 
 r.l W 
 ftraj^;hr or 
 crooked. 
 
 134 
 Curious 
 iv.d very 
 iniportsnt 
 cafe of fou 
 plate.*. 
 
 confequently each body overcharged in a certain deter- 
 mined proportion, depending on its rriagnitude, if any 
 two of thefe bodies are made to communicate in the 
 fame manner, their degrees of elcflricity are fuch, that 
 no fluid will pnfs from one to the other, tlieir mutual 
 aftions on the fluid in tiiis canal being alfo in equilibrio. 
 He brings out this by induftion and combination of 
 the fingle cafes, each of uhich he denionftrates by means 
 of the following theorem : 
 
 The aftion of an overcharged fphere ACB (fig. 25.) 
 on the fluid in the whole of a canal <// P that is ob- 
 lique, tending to impel the fluids in the direftion of 
 that canal, is equal to its aftion ou the fluid In the 
 whole of the rcftilineal canal CP. Let h i be a mi- 
 nute. portion of the ftraight canal, and fd the portion 
 of the crooked canal which i».equidifl.ant from the cen- 
 tre C of the fphere ; draw the radii Cf, C d, and the 
 concentric arches h f, i d, cutting/ C in g ; and draw 
 g e perpemiicular to fd ; the force a<fting on / i, impel- 
 ling it toward P, may be reprefentcd by hi. The 
 fame force afting on df, in the direftion c /, mull there- 
 fore be expreffed by g f. This, when eftimated in tlie 
 diredtion of the canal d f, is reduced to ef; but it is 
 exerted on each particle of df. Now df: gf := gf: 
 tfy. and df%efz=. gf, =. gfxhi; therefore the 
 whole force on df, in the diredtion d f, is equal to the 
 force on / h, in the direftion i h. Hence the truth of 
 the propofition is maniftil. 
 
 We bef the curious reader to apply this to the cafe 
 in hand, and he will find that the moft complicated 
 cafes may all be reduced to the fimple ones which we 
 have demonftrated to be ftriftly true when the bodies 
 are fpheres or plates, and the canah infinitely long, and 
 which are very nearly true when the canals are "uery 
 long, and the bodies iimilar : And we now proceed to 
 one compound cafe more, which includes all the moft 
 remarkable phenomena of eleftricity. 
 
 Let HK, AB, DF, and LM (fig. 27.). be four 
 parallel and equal circidar plates, two of which, HK 
 rand AB, communicate by a canal GC of indefinite ex- 
 tent, joining their centres, and perpendicular to their 
 planes ; let DF and LM be conneAed in the fame 
 manner, and let the two canals be in one ftraight line ; 
 let the plate HK be overcharged, and the plate LM 
 juil faturated. It is required to determine the difpofi- 
 tion and proportion of the eleftric fluid in the plates 
 which will make this condition of HK and LM pof- 
 fible and permanent, every thing being in equilibrio ? 
 
 The plate HK being overcharged, and communica- 
 ting with AB, AB muft be overcharged in the fame 
 manner ; and being alio equal to HK, it muft be over- 
 charged in the fame degree, containing an equal quan- 
 tity of redundant fluid difpofed in the fame manner. 
 To Amplify the inveftigation, we fhall firft fuppofe that 
 the redundant fluid is uniformly fpread over the furfaces 
 of both. 
 
 When the plates HK and AB are in this ftate, let 
 the plates DF and LM be brought near them, as is re- 
 prefented in the figure, CE being the diftance of the 
 centres of AB and DF. It is evident that the redun- 
 dant fluid in AB will aft on the natural moveable fluid 
 in DF, and drive fome of it along the canal EN, and 
 render LM overcharged. Take off this redundant 
 fluid in LM. This will diminifh or annihilate the re- 
 pulfion which it was beginning to exert on the canal 
 
 EN ; therefore more fluid will come out of DF, and 
 again render LM overcharged. The redunAmt fluid 
 ill LM may again be taken off, in lefs quantity than 
 before, as is plain. Do this repeatedly till no more can 
 be taken off. But this will undoubtedly render DF 
 undercharged, and it v.'ill now contain redundant mat- 
 ter. This will aft on the fluid in the canal GC, and 
 abftraft it from G ; therefore fluid will come out of 
 HK into AB. HK will be lefs overcharged than be- 
 fore, and AB will be more overcharged. But tiie now 
 increafed quantity of redundant fluid in AB will aft 
 more ftrongly on the moveable fluid in DF, and dri\e 
 more out of it. This will leave more redundant matter 
 in it than before, and this will aft as before on the 
 fluid in the canal GC. This will go on, by repeated- 
 ly touching LM, till at laft all is in equilibrio. Or 
 this ultimate ftate may be produced at once by al- 
 lowing LM to communicate with the ground. And 
 now, in this permanent ftate of things, HK contains a 
 certain quantity of redundant fluid ; AB contains a 
 greater quantity ; DF contains redundant matter; and 
 LM contains its natural quantity. The demaiid of the 
 problem therefore is to determine the proportion of the 
 redundant fluid in HK to that in AB, and the pro- 
 portion of the redundant fluid in AB to the deficiency 
 of fluid in DF. The dynamical confiderations which 
 determine thefe proportions are, ijl. The repulfion of 
 the redundant fluid in AB, for the fluid in the canal 
 EN, muft be precifely equal to the attraftion of the re- 
 dundant matter in DF for the fame fluid in the canal ; 
 for LM, being faturated, is neutral. 2d, The repul- 
 fion of the redundant fluid in HK, for the whole fluid 
 in the canal GC, muft balance ths excefs of the repul- 
 fion of the redundant fluid in AB above the attraftion 
 of the redundant matter in DF for the fame. 
 
 Let the redundant fluid in AB be =: f. 
 the redundant matter in DF := m. 
 the redundant fluid in HK = F. 
 
 Becaufe HK and AB are equal, there can be no 
 doubt but that the fluid in thofe plates would be finii- 
 larly difpofed; and it is highly probable, that if AB 
 be very near DF, the redundant fluid in AB, and the 
 redundant matter in DF, will alio be difpofed nearly 
 in the fame manner. This will appear plainly when we 
 coniider with attention the forces afting between a very 
 fmall portion of AB and the correfponding portion of 
 DF. The probability that this is the cafe is fo evi- 
 dent, that we apprehend it unncceifary to detail the 
 proofs. We ftiall afterwards confider fome circum- 
 ftances which ftiew that the difpofition in the three 
 plates will (though nearly fimilar) be nearer to a ftate 
 of uniform diftribution than if only AB and HK had 
 been in aftion, Afluming therefore this fimilarity of 
 diftribution, it follows, that their aftions on the fluid 
 in the canals will be fimilar, and nearly proportional to 
 their quantities. 
 
 Therefore let i be to » as the repulfion of the fluid 
 in AB, for the fluid that would occupy CE, is to its 
 repulfion for the fluid in EN or CG. 
 
 Then the aftion of AB on EN is/X n — i, and 
 the aftion of DF on EN is m n ; therefore, becaufe 
 the plate LM is inadlive, the aftions of AB and DF 
 on EN muft balance each other, andy X n — i = ?n n, 
 
 andm=/X^. ^j,^
 
 The repulfion of /^for the fii uM in CG hfn. The 
 attraftion of m for it is m X ti — i j and becaufe m 
 
 -, the attraftion of m for the fluid in CG 
 Therefore the repulfion oi f 
 
 h/X- 
 
 X « 
 
 is to the attraftion of m as fn to _/" X 
 
 ELECTRICITY. ' ^gg 
 
 and AB is very near to DF, the difference from this 
 determination is inconfiderable. We fliall note thefe 
 differences when we confidcr the remarkable phenomena 
 that are explained by them. 
 
 In the mean time, wc (hall jiiil mention fome fnnple 
 confequences of the prefent combination of plates. 1,8 
 
 Suppofe AB touched by a body. Eleftrlc fluid will Method 
 be communicated ; but by no means all the redundant T' ''eftroy. 
 
 -, or as 
 
 Call the repul- 
 
 jundaut 
 luid; 
 
 /«' toy X n — I , or as n' to n — i 
 fion oifr, and the attraftion of m a. 
 We have r : a zn n"- x n — 1 
 
 and r : r — a — ri'-.n'' — {n — I )* = n> ; in — i. 
 
 Therefore, becaufe the repulfion of F is equal to this 
 excefs of r above a, vsre have n' : 2n — 1 =:_/": F, and 
 
 ? = /"• J — ,or/'=F . Therefore, ifn^is 
 
 much greater than 2 n — i, the quantity of redundant 
 fluid in AB V9ill be much greater than the quantity in 
 
 .35 "^^- .... 
 
 Prodigious Now, when the eleftric aftion is inverfely as the 
 
 Kcumula- fquare of the diitance, and EC is very fmall in compa- 
 
 ijon of re- rifon with AC, we have feen (n'-' 11 c.) that 1 : n near- 
 
 ly = C£ : CA, or that n is nearly iprp. When this is 
 
 the cafe, and confequently n is a confiderable number, 
 
 ■we may take the number for without any 
 
 great error. In this cafe / is equal to F X — very 
 
 nearly. Suppofe CA to be fix inches, and CE to be 
 
 ijlh of an inch ; this will give n := 1 20, and_/" =: 60 F ; 
 
 — "' 14,400 
 
 or, more exactly, F =: = ; := 6o4. 
 
 ' '' 2« — I 239 ' * 
 
 If, inftead of the plate HK, we employ a globe of the 
 
 fame diameter, / will be but half of this quantity, ory 
 
 = FX ^(n'123, 124.) 
 
 It alfo appears, that when the plates AB and DF 
 are very near to each other, and conlequently « a large 
 rumber, the deficiency in DF is very nearly equal to 
 the redundancy in AB. In the example now given, 
 
 Knd evacu. 
 uiun : 
 
 59 
 
 m is 7" of/, being —fy,n — i . 
 
 fee no very Yet this great deficiency in DF does not make it 
 ferfible ap- eleftrical on the fide toward LM. It is juft fo much 
 pearance. evacuated that a particle of fluid at its furface has no 
 tendency to enter or to quit it. 
 
 Laftly, this great quantity of fluid collefted in AB 
 does not render it more eleftvical than HK. 
 
 In general, things are in the condition treated of in- 
 n° 22, 23, &c. 
 
 The attentive reader will readily fee, that this account 
 of the apparatus of four plates is only an approxima- 
 tion to the condition that readily obtains under our ob- 
 fervation. Our canals are not of indefinite length, nor 
 occupied by fluid that is diftributed with perfedl uni- 
 formity; nor is the fluid uniformly fpread over the fur- 
 face of the plates. He will alfo fee, that the real ftate 
 of things, as they occur in our experiments, tends to 
 diminiih the great difproportion which this imaginary 
 ftatement determines. But when the canals are very 
 long in cojsparifon with the diameters of the plates. 
 
 fluid contained in AB : only as much will quit it asjj'j.fjt''" 
 will reduce it to a neutral ftate, if the body which n.uLi!""' 
 touches it communicates with the ground ; that is, tilli.Uyde- 
 the attraflion in the redundant matter in DF attnidsK''"'^ 
 fluid on the remote fide of AB as much as the redun- 
 dant fluid left in AB repels it. When this has been 
 done, DF is no longer neutral ; for the repulfion of 
 AB tor the fluid in EN is now diminiflicd, and there- 
 fore the attraftion of DF will prevail. If we now 
 touch DF, it may again become neutral with refpeft to 
 EN; but AB will now repel again the fluid in CG, 
 and again be eleftric on that fide by redtmdancy. 
 Touching AB a fecond time takes more fluid from it, 
 and DF again becomes eleftric by deficiency, and at- 
 tracts fluid on thr.t fide, — And thus, by repeatedly 
 touching AB and DF alternately, the great accumula- 
 tion of fluid in AB may be exhauftcd, and the nearly 
 equal deficiency in DF may be made up. 
 
 But this may be done in a much more cxpeditiousi. a,! at 
 way. Suppofe a flender condufting canal a b d brought cnce. 
 very near to the outfides of tht plates, the end a being 
 near to A, and the end d to D. The vicinity of a 
 to A caufes the fluid in a 3 to recede a little from a 
 by the repulfion of the redundant fluid in AB. This 
 will leave redundant matter in a, which will ftrongly 
 attraft the redundant fluid from A, and a may receive 
 a fpark. But the coniequence, even of a nearer ap. 
 proach of the fluid to the outward furface of A, will 
 render the corrtfponding part of DF more attraftive, 
 and the retiring of fluid from a along a b will pufli 
 fome of its natural fluid toward d ; and thus A becomes 
 more difpofed to give out, and a to take it in, while d 
 is difpofed to emit, and D to attraft. Thus every c:r- 
 cumftance favours the paflTage of the whole, or almoffc 
 the whole, redundant fluid to quit AB at A, to go 
 along aid, and to enter into DF at D. j.,. 
 
 It is plain that there muft be a ft;rong tendency in The plate* 
 the fluid in AB to go into DF, and that the platesOron-ly ac-- 
 muil ftrongly' attraft each other. A particle of fluid'""^"''' 
 fituated between them tends toward DF with a force," ""^* 
 which is to the fole repulfion of AB nearly as twice 
 the redundant fluid in it to what it would contain if 
 tleftrified to the fame degree while ftanding alone.. 
 
 With this particular and remarkable cafe of induced' 
 eleftricity, we fliall conclude our explanation of M." 
 iEpinus's Theory of Eleftric Attraftion and Rupulfion.' 
 The reader will recolleft, that we began the confide- 
 ration of the difpofition of the eleftric fluid in bodies,, 
 in order to deduce fuch legitimate confequences of th.* 
 hypothetical law of aftion as we could compare with 
 the phenomena. 
 
 Thefe comparifons are abundantly fuppHed by the Method of - 
 preceding paragraphs, particularly by n° 74, yj, ^6 ;exiim;ninK • 
 by n" 130, and by n° 134, the validity- 
 
 Let a fmooth metal fphere be eleftrified pofitively°[ '•''"'''^^ 
 in any manner whatever, and then touch it with a fmall" 
 
 one
 
 59« 
 
 one in Its natural ftate 
 between them in a proportion which tlic theory deter- 
 inines with accuiacy. By the theory alfo the redun- 
 dant fluid in both aifls as if collected in the centre. 
 '1 herefore the proportion of the rcpulfions is determi- 
 ned. Thcfe can be examined by our eltftrometer. 
 But as this menfuration may be faid to depend on the 
 trii'h oi the theory, we may examine this independent 
 of it Let the balls be equal. Then the redundant 
 fluid is divided equally between the bodies, whatever be 
 the law of aClion. Therefore obferve the cleftrometer, 
 as it is affefted by the eledritied body, both before and 
 after the communication. This will give the pofitions 
 of the tlettrometer which corrcfpond to the quantities 
 
 i4» ^ ^^^ '• 
 Graduation Take off the eleftricity of one of the balls by toiich- 
 
 ofele'^lro- ing it, and tVitn touch the other ball with it. This 
 meter. virill reduce to i the original quantity 4, and therefore 
 to jtli of the original quantity. This will determine 
 the value of another polition of the eledrometer. In 
 like manner, we obtain ^ih, j\lh, &:c. &c. Then, by 
 touching a ball containing i with a ball containing 4> 
 wt get a pofition for i, I, ■{, &c. Proceeding in this 
 way, vTe graduate our eleArometer independently of all 
 theory, and can now examine the eledlricity of bodies 
 with confidence. The writer of this article took tliis 
 method of examii.ing his eleftroineter, not having then 
 feen Mr Cavtndifli's diflirtation, which gives another 
 mode of meafurenient. He liad the fatisfaflion oi ob- 
 ferving, in the firit place, that the pofitions ot the in- 
 ilrument, which tniqutftionably indicated i, t,t, &c. 
 vere precifcly ihofe which fhould indicate them if elec- 
 tric repulfion be inverfcly as the fquares ot the diilances. 
 Having thus examined the electrometer, it was eafy to 
 give to balls any propi fed degree, oi eleftricity, and 
 then make a communication between balls of veiy dif- 
 ferent diameters. The eleiitrometer informed us when 
 the repeated abftrnCtions by a fmall ball reduced the 
 eledlricity of a large ball to J, 3, &c. This fliewed 
 the proportion of electricity contained in balls of dif- 
 ferent diameters. This was alfo found to be fiich as 
 refulted from an aftion in tlie inverfe duplicate ratio of 
 the diftances. 
 
 Long after this, Mr Cavendifli's invelligation point- 
 ed out the piopoition of the redundant elcitric fluid in 
 balls of diflcreut lizes joined by long wires ; in n" 130, 
 &c. thefe were examined — and found to be fuch as were 
 fo indicated liy the electrometer. 
 
 Anel, laltly, the mode of accumulating great quanti- 
 ties of fluid by means of par.iUel plates, gave a third 
 ■way of confronting the hypothetical law with experi- 
 ment. The argument was no lels fatisfnflory in this 
 cafe ; but the examination required attention to parti- 
 culars not yet mentioned, which made the proportions 
 between the fluid in HK and AB (fig 27.) widely dif- 
 ferent from thole meiitioued in the preceding para- 
 graphs. Thefe circumllanccs are among the molt curi- 
 ous and important in the whole lludy, and will be con- 
 fidered in their place. 
 
 We red therefore with confidence on the truth of 
 The'law ff the law of c!e£tric aftion, alfumcd by us as a principle 
 elefli'c >c- of explanation and invelligation. It is quite needlefs 
 tiv iswfl.p,;^ iinpn.fitable to give any detail of the numerous 
 de'f'on- expcrunenis in uliich we contronted it with the pheno- 
 mena. The fcrupulous reader will get ample fatisfac- 
 
 ELECTRICITY. 
 
 The redundant fltiid Is divided tion from the excellent experiments of Mr Coulomb 
 
 M3- 
 
 14-)' 
 
 145 
 
 ned. 
 
 with his delicate electrometer. He will find them in the 
 Memoirs of the Academy of Sciences of Paris for 1 784, 
 178}, 1786, and 1787. Some of them are of the fame 
 kind with thofe employe<l by the writer of this article; 
 others are of a different kind ; and many are direited 
 to another objeA, extremely curious and importaiit in 
 this lludy, namely, to difcover how the cledtric fluid is 
 difpofed in bodies ; and a third fet are directed to an 
 examination of the manner in which the elettric fluid is 
 diflipated along imperfeft conductors. 
 
 But we have already drawn this article to a great 
 length, and mult bring it to an end, by explaining fome 
 very remarkable phenomena, namely, the operation of 
 the Leyden phial, the operation of the eletlrophorus, 
 and the diffipation of eletlrlcity by fliarp points and by 
 imperfeft conductors. 14^ 
 
 The obfervations of Mr Watfon on the necefllty ofOf''"j^^T' 
 connecting the rubber of an ele^:!rical machine with the ' 
 ground, might have fuggetled to philofophers the doc- 
 trine of f/us and minus eleClricity, efpecially after the 
 valuable difcoveries of Mr Symmer and Cigna. A fe- 
 rious confideration of thefe general fails would have 
 led to the theory of coated giafs ahnofl; at its firll ap- 
 pearance. But the hillorical faCt was otherwife; and a . 
 confiderable time elapfed betwen the firll experiments 
 with charged glals by Klelll, and the clear and fatif- 
 faCtory account given by Dr Franklin, of all the elTen- 
 tial parts of the apparatus, and the probable procedure 
 of nature in the phenomenon. The impermeability of 
 glafs by the eleClric fluid, and the conlequent abllrac- 
 tion of it from the one fide while, it was accumulated 
 on the other, fuggellcd to his acute mind the lesding 
 principle ot eleClrical philofophy ; namely, that all the 
 phenomena arile from the redundancy or deficiency of 
 clctlric fluid, and that a certain quantity of h n fides 
 naturally in all bodies in a ftate of uniform dillribu- 
 tion, P.nd, in this ftate, produe-.s no fenfble eifeCt. 
 This was, in his hands, the inlet to the whole fciencc ; 
 and the greatelt part of w hat has been fince added i» a 
 more dittinCt explanation how the redundancy or defi- 
 ciency of eieCtric fluid produces the obfcrved pheno- 
 mena. Dr Franklin deduced this leading principle 
 from oblerving, that as fail as one fide of a glals plate 
 was electrified pofitivcly, the other iide appeared nega- 
 tive, and that, unltfs the elcClricIty of that fide was 
 communicated to other bodies, the other fide could be 
 no farther electrified. Having formed this opinion, the 
 old obfervations of Watfon, Symmer, and Cigna, were 
 ttphined at once, and the explanation of the Leydeu 
 phial would have come in courfe. It is for thefe rea- 
 lons, as much as for the important difv'overy of the, 
 famenefs of eleClricity and of thunder, that Dr Frank- 
 lin Hands fo high in the rank of philofophers, and is 
 jullly confidered as the author of tlu's department of 
 natural fcience. Whatever credit may be due to the 
 chemical fpeculations of De Luc, Wilcke, Winkler, 
 and many others, who have attempted to aflbciatc elec- 
 tricity with other operations of nature, by refolving the 
 eleCtric fluid into its conllituent parts, all their expla- 
 nations prefnppofe a mathematical and mechanical doc- 
 trine conceining the mode of aCtion of the ingredients, 
 which wiU either account for the total inactivity of the 
 compound, or which will explain, in the very fame 
 manner, the aClion of the compound itfelf : yet all feem 
 
 to
 
 ELECTRICITY. 
 
 147- 
 
 148 
 Theory of 
 charged 
 glafs com- 
 pleted by 
 Mr Caven 
 difti. 
 
 to content themfelves with a vague and indiftiuA 110- 
 'tion of this prehmiiiiiry ftep, and have allowed thi;ni- 
 felvcs to fpeak of elMrical atmofpheres, and (pht^res of 
 adtii'ity, and fuch other creatures of the mind, without 
 once taking the trouble ot conlidering whether thole 
 affnmptions afforded any real explanation. How dif- 
 ferent was Newton's conduft. When he difcovered 
 that the planets attradlcd each other in the inverfe du- 
 plicate ratio of the diilances, and that terreltrial gravity 
 was an inilance of the lame force, and that therefars 
 the deflcftion of the earth was the effecl of the accu- 
 mulated weight of all its parts ; he did not radily affirm 
 this of the planets, till he examined what would be the 
 cfTcft of the accumulated, attradtion in the abovemen- 
 tloncd proportion, 
 
 Mr ^pinus has the honour of firft treading in the 
 fteps of our ilhiftrious countryman ; and he has done 
 it with fingular fuccels in the explanation of the phe- 
 nomena of attraftion and repulfion, as we have already 
 feen. In no part of the iludy has his fucctfs been lo 
 confpicuous as in the explanation of the curious and 
 important phenomena of the Leyden phial. It only re- 
 mained for him to account for the accumulation of fuch 
 a prodigious quantity of this agent as was competent 
 to the produftion of cffefts whicii feenied to exceed the 
 fimilar effeCfs in other cafes, out of all j)roportion. In- 
 deed, the difproportion is fo great, as to make them ap- 
 pear to be of a different and incomparable nature. Dr 
 Wilfon's experiments in the pantheon are therefore pre- 
 cious, by fhewing that nothing was wanted for the 
 produftion of all the effects of the Leyden phial but a 
 fnrface fufficiently extentive for containing a vail quan- 
 tit\f of fluid, and fo perfeiJtly conducting as to admit 
 of^its iimultaneous and rapid transference. Therefore 
 we affert that one of the chief merits of Mr iEpinns's 
 theory is the fatisfaftory explanation of the accumula- 
 tion of this vaft quantity of fluid in a fmall fpace. ^Vc 
 triift, therefore, that our readers will penife it with 
 plealure. But we mull liere ubferve, th.it Mr jEpinus 
 has not exprefsly done this in his work which we have 
 already made fo much life of, nor in any other that 
 we know of. He has gone no farther than to point 
 out to the mathematicians, that his hypothefis is ade- 
 quate to the accounting for any degree of accumulation 
 whatever. This he does in, that part of his work which 
 contains the formulx of n° 38, 39, 40, 41, &c. And 
 he afterwards Ihews, that all the phenomena of attrac- 
 tion and repuliion which are obfervtd in the charged 
 jar are precifcly fuch as are neceflary coiifequenccs of 
 his theory. 
 
 It is to the Hon. Mr Cavendifh that we are indebt- 
 ed for the fatisfaclory, the complete {and we may call 
 it the popular), explanation of all the phenomena. 
 Forming to himfelf the fame notion of the mechanical 
 properties of the ele<ftric fluid with Mr TEpinus, he 
 examitsed, with the patience, and much of the addrefs, 
 of a Newton, the aftion of fuch a fluid on the fluid a- 
 round it, and the fenfible efftfts on the bodies in which 
 it refided ; the difpofition of it in a confiderable varie.ty 
 of cafes ; and particularly its aftion on the fluid con- 
 tained in (lender canals and in parallel plates ; — till he 
 arrived at a fituation of things fimilar to the Leyden 
 phial. And he then pointed out the precife degree of 
 accumulation that was attainable, on difl"erent fuppofi- 
 tions concerning the law of eleftric aftion in general. 
 
 591 
 
 149. 
 
 j-fphercs. 
 
 We have given an abflrafl of this inveftigstion accom- 
 modated to the invcrlc duplicate ratio of the diftances. 
 From this it apjicars (n" 135), th&t whatever quan- 
 tity of eledtric fluid we can put into a circular plate 
 12 inches in diameter, by fimple communication with 
 the prime conductor of an electrical machine, we can ac- 
 cumulate fio times as much in it by bringing the plate 
 within 15th qf an inch of another equal plate which 
 communicates with the ground ; and it appears in n*' 
 139, that all this accumulated fluid rr:ay be transferred 
 in an iiiilant to the other plate (which is ihcwn to be 
 almoil equally deprived of fluitlj, by connefting the 
 two jilates by a fmall wire. 
 
 But as it was alio fh;wn in that paragraph, that the 
 force with which the accumulated fluid was attrafted 
 by the redundant matter in the other plate was exceed- 
 ingly great, and confequently its tendency to efcape 
 w.is proportionably increafed ; this accumulation can- 
 not be obtained unlets we can prevent this fpontaneous 
 transference. ,,. 
 
 Here the non-condufting power of idio-eleftrics, Inexpfica- 
 witliout any diminution, thc^adion of the eledtiic fluid '''•^.''y "^a. 
 on fluid or matter on the other fide of them, comes to!.^/^'''Jj'^""°* 
 our aid, and we at once think of interpofing a plate of ' 
 glafs, or wax, or rofin, or any other eleifric, between 
 our conducing plates. Such is the immediate fug- 
 geftion of a perfon's mind who entertains the .£pinian 
 notion of the eleftric fluid ; and fuch, we are convin- 
 ced, is the thought of all who imagine that they under- 
 ftand the phenomena of the Leyden phial. But thofe 
 who attempt to explain eleftric aftion by means of 
 what they Ciill cleftric atmofphere of variable denlity 
 or intenljty, are not intitled to make any fu( h inference, 
 nor to expe6l any fuch phenomena as the Leyden phial 
 exhibits. Elcdrlcity, they lay, acts by the interven- 
 tion of atmofpheres : Therefore, whatever allows the 
 propagation of this aAion (conceive it in any manner 
 whatever), allows the propagation ef thefc agents ; and 
 whatever does not conduct clediic aftion, does not 
 couduft the agen's. Interpofed glafs fiiould therefore 
 prevent all aftion on the other plate. Tiiis is true, 
 even although it were pofTible (which we think it is 
 not) to form a clear notion of the free pafTage of this 
 material atmofphere in an !nft.ant, and this without 
 any diminution of its quantity, and confequently of its 
 aftion, by the difplacement' of fo much of it by the fo- 
 lid matter of the body which It penetratcj. Yet with- 
 out th's undimjniflicd aftion of the eledtrified plate on 
 the fluid, and on the mittcr, beyond the glafs, and on 
 the canal by which its fluid may be driven off into the 
 general mafs--no fuch accumulation can tak^ place; 
 and if the phenomena of the Leyden phisl are agree- 
 able to the refults of the iEplnran hypothefis, all ex- 
 planation by atmofpheres inull be abandor.ed. Indeed 
 when the partifans of the atmofpheres attempt to ex- 
 plain thtir conceptions of them, they do not appear to 
 differ from what are called j^''^-''"''''-' "f atliviiy (a phrafe 
 firft ufed by Dr Gilbert of Colcheller, in his celebrated 
 work De Alngnefe et Corporilnis Ma^nelicis ) : and fpheres 
 of aftivity will be found nothing more than a figurative 
 cxprefTion of fome indiftinft conception of a3ion In 
 every direBion. When we ufe the words allraSion and 
 repulfion, we do not fpeak a whit more figuratively than 
 when wc ufe the general word aH'ion. Thefe terms are 
 all figurative, only attra&kn and repulfion have the ad- 
 vantage.
 
 592 E L E C T R 
 
 vantage of fpeclfying the dirfO'ion in which we conceive 
 the atlion to be exerted. 
 
 It therefore becomes flill more interefling to the phi- 
 lofopher to compare the jihenomena of charged glass 
 with tbeiEpinian theory. They afford an expennwiilum 
 151 cruets in the queftlon about eleftric atniolpheres. 
 Phennmr- J^gt; G ((ig;. :S.) rcprtfent the end of a prime con- 
 "Xi^tu' duftor, fwrnlliied with Henley^s ekarometer. Let AB 
 erplSned. reprefent a round plate of tinfoil, palled on a pane of 
 glafs which exceeds the tinfoil about two inches all 
 round. The pane is fixed in a wooden foot, that it 
 may ftand upright, and be fliifted to any diftance from 
 the conduftor. DF reprcfents another plate of the 
 fame dimenfions as AB, in the centre of which is a 
 wire EN, having a fmall ball on the end N, to which 
 is attached a Canton's electrometer. This wire pafles 
 through the wooden ball O, fattened to the infulating 
 iland P. The glafs pane mud be very clean, dry, and 
 warm, Conneft the conducEfor G with AB by a wire 
 reaching to the centre C. Turn the cylinder of the 
 eledlrical machine (lowly, till the eleftrometer rife to 
 30°'0r 40°, and note the number of turns. Take off 
 the eleftricity ; a'.id having taken away the connecting 
 wire GC, turn the machine again till the eleftrometer 
 rife to tlie fame height. The difference in the number 
 of turns will give fome notion of the expenditure of 
 fluid neceffary for eleftrifying the plate of tinfoil alone. 
 This will be found to be very trifling when the eleftri- 
 city is in fo moderate a degree. It is proper, however, 
 to keep to this moderate degree of electrification, be- 
 caufc when it is much higher, the diffipation from the 
 edges of the plate is very great. Replace the wire, and 
 ■ again raife the electrometer to 30°. Now bring forward 
 the plate DF, keeping it duly oppofite and parallel to 
 AB, and taking care not to touch it. It will produce 
 no fenfible change on the pofition of the eleCtrometer 
 till it come within four or three inches of the glafs pane; 
 and even when we bring it much nearer (if a fpark do 
 not fly from the glafs pane to DF), the eleCtrometer 
 HG will fink but two or three degrees, and the eleCtro- 
 meter at N will be little affeCted. Now remove the 
 plate DF again to the diftance of two or three feet, and 
 attach to its ball N a bit of chain, or filver or gold 
 thread, which will trail on the table. Again, raife the 
 eleCtrometer to 30°, and bring DF gradually forward 
 to AB. The electrometer HG will gradually fall 
 down, but will rife to its former height, if DF be with- 
 drawn to its firft fituation. It is fcarcely neceffary to 
 fhew the conformity of this to the theory contained 
 in n° 134, T35, &c. As the plate DF approaches, 
 the redundant fluid in AB aCts on the fluid in DF, 
 and drives it to the remote end of the wire EN, as was 
 fhev^n by the divergency of the balls at N; and then an 
 accumulation begins in AB, and the eleCtrometer HG 
 falls in the fame manner as if part of the fluid in the 
 prime conductor were communicated to AB. When 
 DF communicates with the ground, the eleCtrometer 
 at N cannot (hew any cleClricity, but much more fluid 
 is now driven out of DF, in proportion as it is brought 
 nearer to AB. Indcad of connecting AB immediate- 
 ly with the prime conductor, let the wire GC have a 
 plate at the end G, of the fame dimenfions as AB, ha- 
 ving an eleCtrometer attached to the fide next to AB. 
 Let this apparatus of two plates be eleCtrified anyhow, 
 and note the divergency of the ekftrometer at H, be- 
 
 I C I T Y. 
 
 fore DF, communicating with the ground, is brought 
 near it, and then attend to the changes. We (hall find 
 the divergency of this eleCtrometer correfpond with the 
 diftance of DF very nearly as the theory requires. j.. 
 
 While the plates AB and DF are near each other, State of ih« 
 efpecially when DF communicates with the ground, if'uatings. 
 we hang a pith-ball between them by a filk thread, it 
 will be ftroiigly attraCled by the plate which is neareft 
 to it, whether DF or AB j and having touched It, it 
 will be brl(l<ly repelled, and attracted by the glafs pane, 
 which will repel it after contaft, to be again attraCted 
 and repelled by DF ; and thus bandied between the 
 plates till all eleCtricity difappear in both, the eleCtro- 
 meter attached to H defcending gradually all the 
 while. • 
 
 As all thefe phenomena are more remarkable in pro- ^Sl- 
 portion as the plates are brought nearer, they are moft 
 of all when DF is applied cloie to the glafs pane. And 
 if, in this fituation, we take any accurate method for 
 meafuring the intenfity of the eleCtricity in the plate 
 HG, before the approach of DF, we (hall find the di- 
 minution, occafioned by its coming into full contaCt 
 with the pane, confiderably greater than what is point- 
 ed out in n" 135. When we employed plates of 12 
 inches diameter, parted on a pane one fortieth of an inch 
 in thicknefs, we found the diminution not lefs than 
 199 parts of 200 ; and we found that it required at 
 leall zoo times the revolution of the cylinder to raife 
 the electrometer to the fame height as before. This 
 comparifo!! is not fufceptible of great accuracy, by rea- 
 fon of many circumftances, which will occur to an elec- 
 trician. But in all the trials we have made, we are cer- 
 tain that the accumulation greatly exceeded that point- 
 ed out by the iEpinian theory as improved by Mr Ca- 
 vendifh. And we muft here obferve, that we found 
 this fuperiority more remarkable in fome kinds of glafs 
 than others, and more remarkable in fome other idio- 
 eleCtrics. We think that, in general, it was moft re- 
 markable in the coarfe kinds of glafs, provided they 
 were uniformly tranfparent. We found it moft re- 
 markable in fome common glafs which had exfoliated _ 
 greatly by the weather ; but we alfo found that fuch a 
 glaffes were very apt to be burft by the charge. The *• 
 hardeft and beft London crown-glafs feemed to accu- 
 mulate lefs than any other ; and a coloured glafs, which 
 when viewed by reflection feemed quite opake, but 
 appeared brown by tranfmitted light, admitted an ac- 
 cumulation greatly exceeding all that we have tried ; 
 but it could not be charged much higher without the 
 certainty of being burft. This diverfity in the accumu- 
 lation, which may be made in different kinds of glafs, 
 hinders us from comparing the abfolute accumulations 
 aifigned by the theory with thofe which experiment 
 gives us. But though we cannot make thiscomparifon, 
 we can make others which are equally fatisfaCtory. We 
 can difcover what proportion there is between the accu- 
 mulation in glafs of the fame kind, as it may differ in 
 thicknefs and in extent of furface. Ufing mirror glafs, 
 which is of uniform and meafurable thicknefs, and very 
 flat plates, which come into accurate or equable con- 
 tact — we found that the accumulation is inverfely as the 
 thicknefs of the plates ; but with this exception, that 
 when two plates were ufed inftead of a plate of double 
 thicknefs, the diminution by the increafe of thicknefs 
 was not nearly in the proportion of this increafe. In- 
 ftead
 
 ELECTRICITY. 
 
 liiiir, it was more than difchari.'inpr wire ; firft, negative eleflricitv on tTi« end 
 
 593 
 
 roiiji at- 
 a^iuii be- 
 ;een 
 cm. 
 
 that ai)))ic);iclic3 A, and, in tlic fame inllaiit, ojjpofitc 
 elcftricitiis at D and tlie adjoininff end ot the wire. ,fi^ 
 
 The fiillowing obfcrvatioii of Piofeflor Richinann ofBeautifuI 
 St l\tt'r(biirgh (tlie gentleman who fell a facn'firc to""! ''f ''"c- 
 
 I- 
 
 ftead of being rctliictil to one 
 
 two-thir(1s ; and in the kind called Duieh plate, the di- 
 minution was inconfidcrable. 
 
 The experiments with the Dutch and other double 
 plates, fugjfelled another inllrndtive and pretty experi- 
 ment. Obftrviiig thcfe plates to cohere with con lider- eletlrical ftudics by a thunder llrokt from his appaia- '' "^ ^'[P'" 
 able force, it was thought worth while to meafure it ; tus) is extremely inftrudfive and amuilng. Let a i^hils i'vfjf'ij-jp 
 which was attempted in this manner; Two very flat pane be coated on botli fides, and furnillied with a Iniall Richmiiin, 
 brafs plates AB, DF (fig. 29.) funiiflied witii wires eleiilrometer attached to the coatings. It is reprefent- 
 and bidls, were fiifpcnded. about three inclies afunder, ed as if feen edgcvvife in fi;^. ^ ;. Let it be charged po. 
 by filk threads, as reprefented in the figure. At G iitively (ihat is, by redundancy) by the costing AB, 
 was attached a very fine filver wire, which hung very while DF comnuinicates with the ground The ekc- 
 loofe between it and the prime condudlor, without eo- trometer A a will Hand out from the plate, and D /i 
 niing near the table. ,-inotlier was attached 10 N, will hang down, dole by its coating, as long as DF 
 which tv)uched the table. A plate of mirror glafs was 
 fet between them, as lliewn by Q_R.. When this appa- 
 ratus was elettrified, the threads of fufpenfiou imme- 
 diately began to deviate from the perpendicular, and 
 the plates to approach the glafs pane and each other. 
 The pane was carefully (liifted, fo as to be kept in the 
 txaclf middle between them. This refult (hewed very indicating not angles, but mt 
 
 communicates with the ground. But as tlu- eledtriclty 
 gradually diffipates by cominnnication to the coiitigu- 
 oiiv air, the ball a will g;adually, but very fljwly, fall 
 down. We may judge of the intenfity of the remain- 
 ing eledricity by the deviation of the eletlrometer, and 
 we may conceive this deviativ)u divided into degrees, 
 
 ;iliti 
 
 plainly the preifure of the fluid on one of the plates, 
 and the mutual attradlion of the redundant matter and 
 redundant fluid. This increafed as the accuuiulation 
 increafed ; and it was attempted to compare the at- 
 tradlion with the accumulation, by cpmpaiing the devi- 
 ation of the fufpending threads with thai of the elediro- 
 nieter attached to the prime coiiduAor ; but we could 
 not reconcile the feries (which, however, was extremely 
 regular) with the law of eleftric aftion. This harmo- 
 
 wl 
 
 iicti we con- 
 
 )ifcharge 
 ow it is 
 (Tcdled. 
 
 ceive as proportional to the redundancy or deficiency 
 which occafiou them. 
 
 If we take away the communication with the ground, 
 we fliall obferve the ball ,7 fall down very fpeedily, and 
 then more llowly, til! it n ach about halt of i:s firll ele- 
 vation. The ball a' will at the fame time rife to nearly 
 the fame height ; the a\vy\- between the two dearome- 
 ters continuing nearly the fame as at firll. V/hen a has 
 ceafed to rife, both bills will very flovvly defceni, till 
 i)y was probably diilurbed by the force employed in the charge is loll by diffipation. If we touiJi DF du- 
 raifiiig the iilver wires. When more flexible filver threads ring this defcent, (/will immediately fall down, and a 
 were ufed, much was loll by diflipation from the rough- will as fnddenly rife nearly ;ib miich ; the angle between 
 nefs of the thread. We did not think of employing a the cledrometers^ contiuuing nearly the fatue. Re- 
 fine flaxen thread moillened : but, indeed, an agree- move the finger from DF, and a will fail, and tl will 
 ment was hardly to be expefted; becaufe theory teaches rife, to nearly their former places; and the flow de- 
 us, that the dillributlon ot the redundant fluid in AB fcent of both will again continue. The fame thiiur 
 will be extreuiely different from the diflribution of the will happen if we touch AB ; a will fall down clofe to 
 redundant matter in DF, till the plates come very near the plate, and J will rife, &e. And this'alterrate 
 each other. The accumulation in AB depends greatly touching of the coatings may be repeattd feme hur.- 
 on the law of diflribution, being lefs (v^'ith any degree dreds of times before tlie plate be dilcharged. If we 
 of redundancy ) when the fluid is denfer near the centre fufpend a crooked wire vm a, havino- two pith balls v 
 of the plate. Other circumftances concurred to diilurb and » from an infulated point m above the pljtc, it will 
 this trial; but the theory was abundantly confirmed by vibrate with great rapidity, the balls llrikingthe coat- 
 the experiment, which Ihewed the ftrong attradlion ari- ings alternately ; and thus relloring the equilibrium by 
 fing from the accumulation. This was fo great, that al- ileps. Each flroke is accompanied by a fpark. 
 though the plates were only three inches in diameter, and All thefe phenomena are not only confeqnences of ri,eory of 
 the glafs pane was -j-V of an inch thick, and the threads the theory, but their meafures agree precifely with the-'- 
 deviated about 18 degrees from the perpendicular — it computations deduced from the formulse in n" 22 2? 
 required above an ounce weight, hung on the wire EN, 24, accommodated to the cafe by means of n" 1 1 c and 
 to feparate the plates trom the glafs. . 136, as we have verified by repeated trials. But it 
 
 The experienced eleflrician need not be told, that by would occupy much room to trace the a'rreeir.ent here 
 bringing the two ends of a bent wire in contaA with and would fatigue fuch readers as are not familiarly 
 the two plates (firll touching DF with it) dilcharges converfant with fiuxionary calculations. The i..n'>ifi. 
 the apparatus, ar.d caufes the plates to drop off from live reader will get full convidtion by perufing Epinns's 
 the pane. But he may farther obferve, that if there EfTay, Appendix i. A very diftiindf notion mjv be 
 be attached to each end of the difcharging wire a conceived of the whole procefs, by fuiipofing that in a 
 downy feather, and if he firll bring the end near the plate minute AB lofes -i^jth of the unbalanced redundaucv 
 DF, and obferve the feather to be not at all, or but a actually in it, and confcquently diminiflies i.^ ir.ucii in 
 very httle, affedled, and if he then bend round the other its adiion. It will be proved afterwards, that the diffi- 
 end toward the plate AB, both feathers will immediate- pations in equal times are really in proportion to the 
 ly ftretch out their fibres to the plates, and cling fall to fuperncial lepulfions then exerted. We may alio fup- 
 them, long before the difcharging fpark is feen. This pofe, that the adlion of the redundant fluid, 01 redun- 
 is a fine proof of the procefs of difcharge, which be- dant matter, in either coating, on the external fluid con- 
 gins by the indudlion of eledlricity on the ends of the tiguous to it, is to its aflion on the fluid contiguous to 
 SuppL. Vol. I. Part II. . 4 F the
 
 594 
 
 ELECT 
 
 the other coating in the conftant proportion of lo to 
 p. We Weft this proportion for the fimplicity of the 
 compntation. Then the difference of thefe attions is 
 always ^'^th of the full aftion on the fluid contiguous 
 to it. This is alfo an exnci fiippolition in iome parti- 
 cular cafe, depending on the breadth of the coaling 
 ar.d the thicknefs of the pane. 
 
 Now, let the primitive unbalanced repulfion between 
 AB and the contiguous fluid ot the tlcarometer be lOO, 
 ^\;hile DF commanic.ites with the ground. The ball <2 
 will ftand at too; the ball (/will hang touching DF. 
 Then a, hy lofing Vijth, retains only 90, and would 
 fink to 90'': But as this deftroys the equilibriuiti on 
 the other fide, fluid will enter into DF, fo as to reduce 
 the deficiency Totl»- Therefore nine degrees of fluid 
 will enter ; and its aftion on a will be the fame as if 
 tV^^s of y, or 8,1 had been reftored to AB. There- 
 fore a will rife from 90 to 58, 1 ; or it will fink in one 
 minute from 100 to g^ff- 
 
 But if we have cut off the communication of DF 
 with the ground, this quantity of fluid cannot come into 
 DF ; and the quantity v/hich really comes into it from 
 tlie air will h; to that which efcapei from A as the at- 
 traaion on the fide of DF to the repulfion on the fide 
 of AB. By the diminution of the repulfion r'oth, and 
 the want of 9 degrees of fluid in DF to balance it, DF 
 acquires an attraftion for fluid which may be called y. 
 Therefore, fince -,Vh of the primitive repulfion of AB 
 has difTipated 10 meafures of fluid in the minute, 
 the attradion of DF will caufe it to acquire -f^th of 
 9, or 0,9, from the air in the fame minute. At the 
 end of the minute, therefore, there remains an unba- 
 lanced attraftion for fluid = 8,1 ; and confequently an 
 unbalanced repulfion between the redundant matter in 
 DF, and that in the ball d. Therefore d will rife to 
 8,1. But a cannot now be at 98,1 ; becaufc DF has 
 not acquired 9 meafures of fluid, but only T%ths of one 
 meafure. Therefore a, inftead of rifing from 90 to 
 98,1, will only rife to 90 + -/oths X tV^s ; that is, 
 to 90,81. 
 
 At the clofe of the minute, therefore, a is at 90,81, 
 and d is at 8,1, and their dift;ance is 98,91. In the 
 next minute, AB will lofe -f'gth of the remaining unba- 
 lanced elearicity of that fide, and DF will now acquire 
 a greater proportion than before ; becaufe its former 
 unbalanced attradion gets an addition equal to Troths 
 of the lofs of AB. This will make a larger compenfa- 
 tion in the aftion on a, and a will not fall fo much as 
 before. And becaufe in the fucceeding minutes the at- 
 traaion of DF for fluid is increafing, and the repul- 
 fion of AB is diminllhing, the compenfation in the ac- 
 tion on a, by the increafed attradion of DF, conti- 
 nues to increafe, and the defcent of a grows continually 
 flower ; confequently a time ^ufl; come, when the re- 
 pulfion of AB for fluid is to the attradion of DF for 
 it, nearly in the proportion of 10 to 9. When this 
 ftate obtains, d will rife no more ; becaufe the receipt 
 of fluid by DF, beina; now xsths of the lofs by AB, 
 it will exadly compenfate the additional attradion of 
 DF for fluid, occafioned by that lofs. The next lofs 
 by AB not being fo great, and the next receipt by 
 DF continuing the fame, by reafon of its undimiiiiflied 
 attradion, there will be a greater compenfation in the 
 adion on a, which will prevent its defcending fo faft ; 
 and there will be more than a compenfation fur the ad- 
 
 R I C I T Y. 
 
 ditional attradion of DF for fluid : that is, the fluid 
 which has now come into DF will render it, and alfo 
 the ball d, lefs negative than before ; and therefore they 
 will not repel fo ftrongly. Therefore d mufl now de- 
 fcend. It is evident, that fimilar reafons will ftill fub- 
 fift for the flow defcent of a, and the flower defcent of 
 (/, till all redundancy and deficiency are at an end. 
 
 This maximum of the elevation of d happens when a 
 has delceiidtd about one half of its elevation ; that is, 
 when the unbalanced repulfion of AB is reduced to 
 about one-half. For if one-half of the unbalanced fluid 
 be really taken out of AB, and if DF can get no i'up- 
 ply whatever, it muft acquire an attradion correfpond- 
 ing to t'^ths of this ; and if the fupply by the air be 
 now opened to it, things will go on in the way already 
 defcribed, till all is dlfchargcd. 
 
 This account of the procefs is only an approxima- 
 tion ; becaufe we have fuppofed the changes to happen 
 in a defultory manner, as in the popular way of explain- 
 ing the acceleration of gravity. The rife of d is not 
 at an end till the attradtion of DF for fluid is to the 
 repulfion of AB a? 19 to 20. 
 
 But if we interrupt this progrefs in any period of it, 
 by touching DF, we immediately render it neutral, 
 and d falls quite down, in confequence of receiving a 
 complete fupply of fluid. But this muft change the 
 ftate of AB, and caufe it to rife To-ths of the defcent of 
 d. As a and (/were nearly at an equal height before 
 DF was touched, it is plain that a v/ill rife to nearly 
 twice its prefent height ; after which, the fame feries 
 of phenomena will be repeated as foon as the finger is 
 removed from DF. 
 
 If, inftead of touching DF, we touch AB, the fame 
 thinirs muft happen ; a muft fall down, and d muft rife 
 to nearlj' twice its prefent height, and all will go on as 
 before, after removing the finger. LalUy, if inflead of 
 allowing either fide to touch the ground alternately, 
 we only touch it with a fmall infulated body, fuch as 
 the wire with the balls v and u, the ball attached to 
 the fide touched finks, till the eledricity is fliared be- 
 tween the coating and the wire with balls. The ball 
 attached to the other coating rifes -j%ths of the finking 
 of the firft ball. The crooked wire ball is now repel- 
 led by the coating which it touched, and the other ball 
 is brought near to the other coating, and muft be at- 
 traaed by it, becaufe the eleaHcities are oppofite. 
 This operation evidently tends to transfer the redun- 
 dant fluid by degrees to the fide where it is deficient.. 
 It needs no explanation. We fhall only mention a thing 
 which we have always obferved, without being able to 
 account for it. The vibration of the wire acquires a 
 certain rapidity, which continues for a long while, and 
 fuddenly accelerates greatly, and immediately afterwards 
 ceafes altogether. 
 
 This pretty experiment of FrofefTor Richmann will 
 be found very inftruaivc ; and will enable us to under- 
 ftand the operation of the elearophorus, and to fee 
 the great miftake of thofe who fay that it is perfeaiy 
 fimilar to a difcharged glafs plate. j.. 
 
 Thus, then, we fee, that all the claffes of phenome-Eledtrac at- 
 na, conneaed with attradion and repulfion, are precile-tiontrfZ/Jcn- 
 ly fuch as would refult from the.aaion of a fluid fo'I'^^T"" 
 contlituted. The complete undiminilhed adion ot the ' 
 caufe of thofe phenomena on the other fide of the inter- 
 pofed non-condudor of that caufe is demonltrated, and 
 
 aU
 
 ELECT 
 
 «11 explanation by the mfchanical aftion of material 
 ehillic atmoiplieres of vaiiiiblc dciifity imill be abaii 
 doiied, and the infinitely fimplcr explanation by the 
 attraiSive and rcpulilve forces of the fluid itftlf niuil 
 ■ be preferred. 
 
 So liappily does the Fraiililfnian theory of pofitive 
 and negative eleftricity explain the phenomena, when 
 a fuitable notion is formed of the manner of aClion of 
 this fluid. We cannot bnt think that this is attained, 
 when, to the general doftrlne of jEpinns, we add the 
 fpecificatlon of the law of aftion, fo fully verified bv 
 tlie experiments of Mr Coulomb, which are in the 
 hands of the pubh'c, and are of that fnnple nature that 
 any careful experimenter can convince himfelf of their 
 accuracy (See n" 144.) We may therefore proceed 
 with fome confulence, and apply this doflrine even to 
 cafes where experiment does not offer itfelf for proof. 
 Frsiihfin ^'' Franklin affirms that eleftric fluid cannot be 
 
 mifiaken in thrown into one fide of the coated pane unlefs it be 
 furpolinK abltradled from the other; and that therefore the char- 
 that a i Inr- ^^^ glafs contains no more than it did before charging^, 
 contains its ^^^ indeed find that we cannot charge the infide, if the 
 natural outfidc do not communicate with the ground. He 
 quantity of proves it alfo by faying, th.rt if a perfon, when infula- 
 ted, dilcharges a glafs through his own body, he is not 
 found elcftrified : And he infers, as a necelfary confe- 
 quence of this, that a fenes of any number of jars may 
 be charged by the fame turns of a machine, if we make 
 the outiide of the firft communicate with the inlide of 
 the fecond, and the outfide of the fecond v. ith the in- 
 
 (iide of the third ; and fo on ; and the outiide of the 
 lall communicate with the ground. Having made the 
 trial, and having found that more turns of the machine 
 were neceflary, he attributes this to diffipation into the 
 air by the communication. But our theory teaches us 
 otherwife. We learn from it, that the redundant mat- 
 ter in the plate DF is lefs than the redundant fluid in 
 AB, in the proportion of n — 1 to n; and therefore 
 the redundant fluid in the overcharged fide of tlie next 
 plate is no greater. The charge or redundancy in the 
 
 »?ith jar of the feries will therefore be 
 
 Thus, 
 
 jf n, or the charge of the firft jar, be 60, the charge of 
 the iGth jar will be nearly 51. Although a coated 
 plate cannot be charged unlefs one of the coatings com- 
 municate with the ground, it may be ekHrified as much 
 as one of the coatings can be alone. ^\nd this is feen 
 in our attempt to charge it; For as foon as we attempt 
 to eleftrify one fide, the other is eledrified alfo ; for 
 it gives a fpark which no uneleftrified body will do. 
 Alfo, when we difcharge a jar by an infulatcd difchar- 
 ger, we always leave it tleftrical in the fame way with 
 the body from which it was charged. If a man is not 
 found eleftrified after having difcharged a jar through 
 his own body, it is owing to the great furface of iiis 
 body, which reduces the fimple clcftrification of a fide 
 J of the jar to a very iufignifieant and infeafibie quantity, 
 
 tiflake of Wilcke (and we believe Franklin before him) main- 
 'ilcke's. tains, that when the jar has been charged, by conneft- 
 ing one fide with the prime conduftor, and the other 
 with the rubber, it is neutral ami inaftive on both fides. 
 But this is not fo ; and a flight reflcftion might have 
 convinced them that it cannot be f o : if it were, the 
 jar eould not be difcharged. Each fide, while con- 
 
 ^ of another. 
 
 161 
 
 R I C I T y. 595 
 
 neded with the machine, tfiud be in the condition of 
 the part with which it is connected, and in a difpofitiou 
 to take or give. If the trial be carefully made, it will 
 be found to be equally allive on both fides; and the dif- 
 charging rod, having down on its endp, will fiiew this 
 in an unequivocal manner, and ihew that its condition 
 differs in this refpeft from that of ajar charged in the 
 ordinary way. It is in the ma>;imum ilate of Richmann's 
 piate, dcfcribed in n" 1 56. when </ rifea no more. ,^g 
 
 In difcharging a jar A, if iiillead of the outfide com- C!'.ar«c one 
 municating with the infide by a wire, we make it com-j'/ I'V the 
 municate with the infide of a fecond jar B, while the'';.'^''^''F'_ 
 outfide of B is made to communicate with the infide of 
 A, we fliall find be charged by the difcharge of A; 
 and that the dilclKirge of A is not complete, the charge 
 2^ always remainnig, whatever may have been the mag- 
 nitude ot n. 
 
 We may infer from this experiment, that when a important 
 fhock is given to a number of perfons n, b, c, Sec. we infereoce. 
 are not to conclude, that the fluid which comes into 
 the deficient fide of the jar is the fame which came out 
 of the redundant fide. The whole, or perhaps only a 
 part, of the moveable fluid in tlie perfon a goes into fi, 
 replacing as much as has palfed from b into c, &c. In- 
 deed, where the canal is a (lender wire, we may grant 
 that great part of the individual particles of fluid which 
 were accuinulated on the infide of tlie jar have gone in- 
 to the outfide. Perhaps the quantity transferred, e\en 
 in what we call a -very great difcbargc, may be but a 
 fniall proportion of what naturally belongs to a body. 
 This may be the reafon why a charge mil not melt 
 more than a certain length of wire. Mr Cavendifli 
 afcribes this to the greater obftruttion in a longer wire ; 
 but this does not appear fo probable. A greater ob- 
 ftrudion would occafion a longer delay or the tranf- 
 ference ; and therefore the aftion of the fame quantity 
 would be longer continued. He proves, that a metal 
 wire conducts many hundred times faller than water ; 
 yet, when water is dilfipated by a difcharge, it is found 
 to have adtually sondudted a muci] gr-eater proportion of 
 the whole charge. We afcribe it chiefly to this, that, 
 in a fiiort wire, the quantity transferred exceeds the 
 whole quantity belonging to the wire. j6» 
 
 It is furely needlcfs to prove that the theory of theLeyden 
 Leyden phial is the fame with that of the coaled pane.r''"^"''^* 
 The only diflrrence is, that we are not fo able to tellp^^"^ 
 the difpofition of the accumulated fluid, and the evacua- 
 ted matter, in every figure. When the phial is of a 
 globular form, and of uniform thicknefs, with an ex- 
 ceedingly fmall neck, we then knew the difpofitiou 
 more accurately than in a plate. The redundant fluid 
 is then uniformly diilributed. If we could infure the 
 uniformity of thicknefs, fueh a phial would be an ex- 
 cellent UNIT for meafuring all other charges by ; but 
 we can neither infure this (by the manner of working 
 glafs), nor inealure its want of uniformity : whereas 
 we can have mirror plate made of precifcly equal thick- 
 nefs, and meafure it. This, therefore mull be taken as 
 our unit. jjj 
 
 And here we remark, that this gives us the mcflEKeUent 
 perfedt of all methods for comparing our theory with""^''"'.''^'"' 
 experiment. We muft take two plates, of the 'ameV"^'"^ 
 glafs and the fame thicknefs, but of diff'erent dimen- 
 lions of coated furface. We mull charge both by very 
 long conducing wires on both ^\^tif and then meafure 
 4 F 2 hpw
 
 ;g6 
 
 ELECTRIC! Y. 
 
 Low often the charge of the one is contained in tlie 
 other. Mr Cavendilh has given an unexceptionable me- 
 thod of doing this independent of all theory. As it 
 applie's equally to jars, however irregular, we (hall take 
 it altogether. 
 Meafurecf When a jar is charged, obferve the eleftrometer con- 
 * charge nefred with it, and immediattly commnnicatc the charge 
 to another equal jar (the pci feft equality being pievi- 
 cufly afcertaiued by the methods, which will appear 
 immediately). Again note the eleitromcter. This will 
 give the elevation, which indicates one-half, independent 
 of all theory. Now eleftrify a jar, or a row of equal 
 jars, to the fame degree with the firft, and comaumi- 
 cate the charge to a coated mirror plate, difcharging 
 the plate after each communication, till the eleftronietcr 
 reaches the degree which indicates one-half. This Ihews 
 liow often the charge of the plate is contained in that 
 of the jar or row of jars. 
 
 Let the charge of the plate be to that of the jars as 
 X to I. Then, by each communication, the eleAricity 
 is diniiniflied in the proportion of i -)- x to j. If m 
 commuin'cations h»ve been made, it will be reduced in 
 the proportion of i -J- x" to i. Therefore i -f- w™ 
 =: 2, and I + .v = "'V 2, and r =: "y^T — I. 
 
 When x is fmall in proportion to i, we fhall be very 
 near the truth, by multiplying the number of communi- 
 cations by 1,444, and fubtrading 0,5 from the pro- 
 duft. The remainder (hews how often the charge of 
 
 the plate is contained in that of the jars, or — • 
 
 Thu? may the perfeft equality of two jars be afcer- 
 taincd ; and the one which exceeds, en trial, may be 
 reduced to equality by cutting off a little of the coat- 
 ing. An eleftrician 'Ihould have a pair of fmall jars or 
 phials fo adjufted. It will ferve to difcover in a mi- 
 nute or two the mark of one-lialf cleftricity for any 
 electrometer, and for any degree ; as alfo for meafuring 
 jars, batteries, fliocks, &c. much more accurately than 
 any other method : becaufe fuch phials, conftruiftcd as 
 we (hall dcfcribe imn-,cdiately, may be made fo neutral, 
 and fo retentive, that the quantity which difiipates du- 
 ring the handling becomes quite infignificant in propor- 
 tion to the quantity remaining; whereas, in all experi- 
 ments with electrometers, condructed with the moil cu- 
 rious attention, the difiipations are great in proportion 
 to the whole, and are capricious. 
 164. It was chiefly by this method that the writer of this 
 article, having read Mr Cavendirti's paper, compared 
 the mtafures given by experiment with thole which re- 
 fult from an aftion in the inverfe duplicate ratio of the 
 diftance. When the charges were moderate, the coin- 
 cidence was perftft ; when the charges were great, the 
 large plates contained a little more. This is plainly 
 owing to their being lefs difpufed to dilhpate from the 
 
 ,65 ^'^g^'- 
 Maxims for We may now follow with fome confidence the prac- 
 conftruift- tieal maxims deducible from the theory for the con- 
 ftruftion of this accumulating apparatus. The theory 
 prefcribes a very conducting coating, in clofe and unin- 
 terrupted contaft : It prefcribes an extenlive furface, 
 and a thin plate of idio-eleftric fubftance. According- 
 ly all thete are in faft attended by a more pow/erful ef- 
 left. Metal is found to be far preferable to water, 
 ■which was firil employed, having been fuggefted by the 
 
 ^g jars, 
 
 batteries, 
 
 &c. 
 
 original experiments of Gray, Klcift, and Cunseus. A 
 
 continuous plating is prefcrihed, in preference to foir.c 
 
 methods commonly practifcd ; fuch as filling the jar 
 
 with brafs dull, or gold leaf, or covering its furface 
 
 with tilings ftuck on with gum water, or coating the 
 
 iiifide with an amalgam of mercury and tin. This lai'l 
 
 appears, by reflection from the outfide, to give a very 
 
 continuous coating ; but if «e hold the jar bt-tween 
 
 the eye and the light, we may perceive that it is only 
 
 like the covering with a cobweb. Yet there are cafts 
 
 where thefe imperfedl coatings only are practicable, I 
 
 and fome rare ones where they are preferable. In the Hit:t for i 
 
 medical exhibition of eleftricity, where the pwpofe in- nietlica' etj. 
 
 tended is fuppofcd to require the transfufion of a great .','''.'" °' \ 
 
 quantity of the ekftric fluid, any thing that can dimi- 
 
 ni(h the irritating tmartnefs of the fpark is defirable. 
 
 This is greatly effcfted by thofe imperfcdl coatings. 
 
 Small (hocks, which convey the fame quantity of fluid 
 
 with the iharp pungent and alarming fpark from a large 
 
 furface, are quite ioft and inoffenlive, greatly ret'em- 
 
 bling the fpafmodic quivering, fometimes felt in the lip 
 
 or eye-lid, and will not alarm the mofl fearful patient. ,55 
 
 Clofe contaft of the metallic coating is obferved to How to 
 increafe the efTeft of the charge. But it is alfo found ?■■";«"' '•" 
 that it greatly increafes the rifk of burfting the glafs-'"^'^f,'?|i°j 
 by fpontaneous difcharge through its fubftance. AnJ^ij^^ges, 
 experienced eleftrician (we think it is Mr Brookes of 
 Norwich) fays, that fince he has employed paper co- 
 vered with tinfoil, with the paper next the glafs, inflead 
 of the foil itfelf, he has never had a jar burft ; whereas 
 the accident had been very frequent before. The theo- 
 ry juftifies this obfervation. Paper is aa imperfecl con- 
 dutlor, even when foaked with flour pafl.e ; and the 
 transfufion, though rapid, is not inltantaneous nor de- 
 fultory, but begins faintly, and fwells to a maximum. 
 It operates on the glafs, like gradual warming, inftead 
 of the ludden application of great heat. jf,^ 
 
 Mr Cuthbertfon, an excellent artift in all electrical ap-Very cur:, 
 paratus, and inventor of the befl air-pump, has made a""*"'''^" 
 curious obfervation on this fubiett. He fays that he 1;^""','/ 
 has uniformly obltr\eQ, that jars take a much greater ij^rtfon. 
 charge (nearly one-tliird), it the inlide be confiderabiy 
 damped, by blowing into it with a tube reaching to tlie 
 bottom (Niiholfon's Journal, 'b-lAvch. 1799). — We muil 
 acknowledge, that we cas form no diHinil conception 
 of what Mr Cuthbertfon calls en undulation of the claJTtc 
 atmojjjhere. We do nof know whether he means that 
 the atmofphere is actually undulating as water, or as 
 air in the production of found, as its parts being in a re- 
 ciprocating motion ; or whether he only means that 
 this atmcfphere confills of quiefcent ftrata, alternately 
 denier and rarer. Nor can we form any notion how 
 either of thefe undulations contributes to the explofion, 
 or prevents it. We are really but very imperfectly ac- 
 quainted with that part of the fcience which fliould de- 
 termine the precife accumulation that produces the de- 
 fultory transference. We mentioned one neceflary con- 
 fcquence of the aSion inverfely as the fquare of the 
 diftance, which has fome relation to this queilion, i>is. 
 that a particle, making part of a fpherical furface, is 
 twice as much repelled when it has jufl quitted the fur- 
 face, as when it made part of it, provided its place be 
 immediately fupplied. And another circumilance has 
 been frequently mentioned, ^'(2. that a greater, and per- 
 haps much greater, force is necefliry for enabling a 
 
 particle
 
 ELECTRICITY. 
 
 particle of fluid to quit tlie lafl ferles of partitles of the 
 I'ulid matter tlian for producing alnioft any couibpution. 
 Uiit we arc not certain that liiefe circiimilnnces are of 
 liiiHcient indncnce tp explain the whole of the event. 
 yuleant qunnltim valere po/Jinl. Yet we are of opinion 
 that Mr Cuthbertfon has afligned the true caufe, name- 
 ly, the imperfect coating of the inlide of the glals. 
 When we come to the explanation of the efcapc of elec- 
 tricity along imperfeA condnftors, we hope that it will 
 appear, that the rtifjiofition to efcape mull be greatly 
 diminifhed by a charge, which dilpofes the fluid lo, 
 that in no place the conftipation is remarkably greater 
 tlian in another part very near it, and the dtnfity chan- 
 t6S S^^ everywhere (lowly. 
 Bed forms With refpect to the form of the coated glafs, the 
 for jart, ice. theory prtTcribcs that which, will occafion fuch a dillri- 
 bution of the elettric fluid as fliall make its rcpuliion 
 for the fluid in the canal which conncfls it with the 
 prime conduftor as little as pofliblc. In this refpeCt 
 it would feem that a plate is the befl:, and a globe the 
 word; but if both are very thin, the difference cannot 
 be confiderable. Our experience, however, feems to in- 
 dicate the oppofite maxim as the mod proper. We 
 have uniformly found a globe to be far preferable to a 
 plate of the fame thicknefs, and that a plate was ge- 
 nerally the weakcfi: form. It mull be owned that Vv'e 
 ^ have not yet been able to afcertain by the theory what 
 
 Wb is the exa& diftribution of the redundant fluid in :! 
 
 plate. In a fphcre it muft; be uniformly fpread over 
 fhe furface. We muft alfo afcribe part of the inferio- 
 rity of the plate to its greater tendency to difiipation 
 from the edges. If a plate be coated in a ftar like 
 H. form, with (lender projctking points, we fliail obferve 
 
 597 
 
 a fufficient border uncoated for prevfntinT a fpontane- 
 ons dilcharge ; let each of them have a narnnv flip of 
 tinfoil a reaching from the coating to the ed"e on one 
 fide, and a ("imilar flip c leading to the oppofite edge on 
 the other fide. Lay them on each other, fo that the 
 flips of two adjoining plates may coincide. Conneft 
 all the ends, of thefc (lips on one fide together by a flip 
 of the fame foil, or a w ire which tcuiches them all. 
 Then, connecling one of thefe collec'ting flips with the 
 prime condudlor, and the otiier with the ground, we 
 may charge and difcharge the whole together. If the 
 panes be round, or exadl fqnares, we may etr>ploy as 
 few of them together as we pleafe, by (ttting the whole 
 in an open frame, like an old-falhioned plate-warmer ; 
 and then turning the fet which we would employ to- 
 gether at right angles to the reft. This evidently de- 
 taches the two parcels from each other. This battery 
 maybe varied in many wa)£; and if the whole is always 
 to be employed together, we may make it extremely 
 retentive, by covering the uncoated border of the plate 
 with melted pitch, and, while it is foft, prefllng down 
 its neigiibour on it till the metallic coatings touch. 
 For greater variability this iray be done in parcels of 
 the whole. 
 
 On the fame principle, a nioft compendious baltery Anothw. 
 may be made by alternate layers of tinfoil and hard var- 
 nifli, or by coating plates of very clear and dry Muf- 
 covy glafs. But thefe muft be ufed with caution, left 
 they be burft by a fpontaneous difcharge ; in which 
 cafe we cannot difcover where the flaw has happened. 
 They make a furprifing accumulation, without (hewing 
 any vivid eleftricity. 
 
 We have made a very fine eleftric phial for carry- ?„„'/' 
 
 them luminous in the dark, almoft at the beginning of ing about, by forming tin-plate (iron pl'at.e tinned) intojar." 
 the accumulation ; and the plate will difcharge itfelf by fomewhat of a phial fliape, with a long neck. We 
 
 then covered this with a coating of fine fealing wax, 
 about ^'jth of an inch thick, quite to the end of the 
 neck, and coated the fealing wax, all but tlie neck, with 
 tinfoil. It is plain that the fealing w^ax is the coated 
 idio-eleclric, and that the tin-plate phial fervts for an 
 inner coating and wire. The di.Tipation is almoft no- 
 thing if the neck be very fm.all ; and it only requires a 
 little caution to avoid burftlng by too high' a chargt. 
 Even this may be prevented by coating the fealing wax 
 lo near to the end of the neck, that a fpontaneous dil'- 
 charge muft happen before t!ie accumulation is too 
 great. 
 
 thefe points, over the uncoated part, before it has at- 
 tained any confiderable ftrength. Thofe formis are leail 
 expofed to this deterioration which have the leaft cir- 
 cumference to the fame quantity of furface. We have 
 always found that a fquare coating will not receive a 
 more powerful charge wiilinnt exploding than a circu- 
 lar one of the fame breadth, although it contains a 
 fourth more furface; and this although any vifible efcape 
 from the angles be prevented by covering the oiitline 
 with fealing wax. Of all forms, therefore, a globe, 
 with a very narrow, but long neck, is the moft reten- 
 tive. But it is very difficult to coat the infide of fuch a 
 veffel. The balloons uftdin chenucal diflillations make 
 I xcellent jars, and can be eafily coated internally when 
 fhe neck will admit the hand. The thinnell of tinfoil 
 may be ufed, by firft parting it on paper, and then ap- 
 plying it either with the foil or the paper next the glais. 
 ft fliould be cut into guflet--, as in the coverini; of tcr- 
 reftrial globes ; and they (hould be put on overlapping 
 about half an inch. The middle of the bottom is then 
 coated with a circular piece. The great bottles for 
 holding the mineral acids are alfo good jars, but inferior 
 to the balloons, becaufe they are very thick in the bot- 
 tom, and for fome diftance from it. A box of balloons 
 contains more efFeclive furface than an equal box of jars 
 of the fame diameter and height of coating. 
 
 The moft compendious battery may be made in the 
 oBs battery. following manner: Choofe fonTe very flat and thin 
 panes of the beft crown glafs, coat a c\rc\i {ab c d), 
 (fig. 31.) in the middle of both furfaccj, fo as to leave 
 
 t6g 
 Compend: 
 
 It IS well known that the difcharge happens when importance 
 the difcharging balls are at a confiderable diftance from "f " clofe 
 each other ; therefore only -yi much is difcharged as'^''^'''="'g^- 
 correfponds to that diftance. This is one caufe of the 
 refiduum of a difcharge which fometimes is pretty con- 
 fiderable. Some experiments require the very ntmoft 
 force of the charge. It ii therefore proper to make the 
 dilcharge aj clofc and abrupt as poJTible. But the moft 
 rapid approach that we can make of tlic difchnrger is 
 nothing in comparifon with the velocity with which the 
 fluid feems to fly oft", and will therefore have but fmall 
 influence in making a more inflantaneous and complete 
 difcharge. Theory points out the following method : 
 Let a very thick plate of glafs (half an inch), of feveral 
 inches diameter, be put between the difcharging balls, 
 which fliould, in this cafe, be fmall, and let t'hefe balls 
 be ftrongly preffed againft it by a fpring. While the 
 charge is going on, a very fmall part of the glafs plate, 
 
 round
 
 5y8 
 
 ELECTRICITY. 
 
 I"? 
 
 [ iofioa. 
 
 174 
 Pre] < fal 
 
 wh»c}i i*: 
 
 redundant 
 eltdlricity. 
 
 rciuid the points of conta5;, will receive a weak and 
 iiftlefs charge ; but this will not hinder the battery 
 from acquiring the fame intenfity of charge. When this 
 h completed, let the intervening glafs plate be brlfkly 
 witl-.drawn. The difcharge will begin with an intenfi- 
 ty which is unattainable in the ordinary manner of pro- 
 ceeding. 
 
 Much has been faid of the lateral expl.jfion. It ap- 
 pears, that in fome of the prodigious transferences of 
 eleiStrieity that have taken place in the difcharge of great 
 furfacts througii vvirts barely fniRcicnt to conduft them, 
 flalhes of light are thrown eff laterally ; but the moll de- 
 licate eleftrometer, it is faid, is not affeSed. The faft 
 is not accurately narrated ; we have always obferved a 
 very delicate eletlrometer to be affefted. The pafiage 
 of fuch a quantity of fluid is almoft equivalent tn the 
 CO exiilence of it in any given feiftion of the wire ; but 
 it remains there for fo (hort a time, that, ading as an 
 accelerating force, it cannot produce a very fcniible mo- 
 tion. It is like the difcharging a pillol ball through a 
 Ikctt of paper hanging- loofdy. It goes through it with- 
 out very fenfibly agitating it. 
 
 It has fometimes appeared to us probable that, by 
 means of this lateral explofion, the direflion of the cur- 
 rent-may be difcovered. Let the jar ab (fig. 32.) be 
 difcharged by a wire a c d eb, interrupted at c d by the 
 coating of a very thin plate of talc; let the coating alfo 
 be very thin. There muft be fome obltruftion to the 
 motion, which muft caufe the fluid to prcfs on the fides 
 or furfaces of the coating, juft as the obftruiElion to the 
 motion of water in a pipe (arifing from friftion, or even 
 from material obftacles in the pipe) caufes the water 
 to prefs on the fides of the pipe. Therefore if a wire 
 X , connect the other coating with the ground, we 
 ihould expeft that fluid will be expelled along this 
 wire, and a charge be given to the plate of talc. Now 
 whether the courfe in this apparatus be from b to a, or 
 from a to b, if any charge be acquired by c d, it will 
 probably be pofitive in c d, and negative in ,.s; for it is 
 eledric fluid that is fujjpofed to pafs : _ therefore we 
 iliould always have one fpecics of eleftricity, whether a 
 has been charged by glafs or by fealing wax ; and thi« 
 fpecies will indicate which is pofitive. We have faid 
 ^^ probably" — for it is not impoflible that it may be 
 otherwife. If the abftraftion at d be fuppofed more 
 powerful than the fupplying force at c, the fame ob- 
 firuftion may perhaps keep the plate c dm an abforbing 
 ilate, juft as water defcending in a vertical pipe, into 
 which it is preffed by a very fn\all head of water in the 
 ciftern, infl.ead of prefiing the fides of the pipe, rather 
 draws them inwards, as is well known. This feems, at 
 any rate, an interefting experiment ; for we muft ac- 
 -knowledge, that there ftill hangs a myfterious curtain 
 before a theory which deduces fo much from the pre- 
 fence of a fubftance which we have never been able to 
 exhibit alone, and where we do not know when it 
 abounds and when it is deficient. It is like the phlo- 
 gifton of Stahl, or the caloric of Lavoifier. It will 
 be proper to ufe the thinneft plate of talc to be 
 charged, and to conned it with another coated plate 
 of half the diameter, or lefs, in order to increafe 
 the accumulation. It feems by no means a defperate 
 cafe. 
 
 The theory of coated glafs now explained, might 
 have been treated with more prctifion, and the formula 
 
 deduced in the beginning of this article hiight have 
 
 been employed for Ibting the lum. total of the afting 
 
 forces, and thus denionftrating with precifion the truth 
 
 of tl'.e general refnit ; and indeed it was with fuch a 
 
 view that tliey were premifed : but they would have 
 
 been confidcubly complicated in the prtfent cafe ; for 
 
 however thin we fuppofe the tinfoil coatings to be, it 
 
 is evident from n' 92, &c. that each coating wi'l con- 
 
 fift of three ftrata ; of which the two outermoft arc ' 
 
 adive, and muft have their forces ftated, and liie ftate- 
 
 meiit of tiie force of each ftratum would have conlifti-d 
 
 of three terms. This would have been very enibarraflino- 
 
 to fome readers j and the force of the concJufion would 
 
 not, after aU, have been much more convincing than 
 
 v.'e hope the above more loofe and popular account har 
 
 •been. 
 
 W^e have hitherto confidered the non-eleftric coat-r> ''■•. 
 Ill 111 I Uoes the 
 
 mgs only, and tiave not attended to what may chance charge re- 
 to obtain in the fubftance of the coated eleftrics them fide in the 
 fclves. May not part, at leaft, of the redundant fluid f°^''"gsof. 
 be lodged in one Superficial ftratum of the glafs? or, if"]af,> 
 it do not penetrate it, may it not adhere to the furface, 
 and drive off from the other furface, or ftratum, a part 
 of what naturally adheres to it ? Till Dr Franklin's 
 notions on the fubjed became prevalent, no perfon 
 doubted this. The eledric was fuppofed to contain or 
 to accumulate in its furface ail the eleflricity that we 
 know. But the firft luggeftion of Dr Franklin's ex- 
 periments certainly was, that the tledric plate or veflel 
 aded merely as an obftacle, preventing the fluid from 
 flying from the body where it was redundant to that 
 where it was deficient. It is therefore an important 
 queftion in the fcience, whether the glafs or eledric 
 concerned in thefe phenomena ferve any other purpofe 
 befides the mere prevention of the redundant fluid from 
 flying to the negative plate ? 
 
 Now it appears, at the very firft, that this is the cafe.jt jg^ j],^ 
 For if a glafs be coated only on one fide, and be elec-glafs. 
 trifled on that fide, wc obtain a ftrong fpark from the 
 other fide by bringing the knuckle near it : and this 
 may be obtained for fom^e time from one fpot of that 
 furface ; and after this we get no more from that fpot, 
 but get fparks, with the fame vivacity, and in the fame 
 number, from any other fpot that is oppofite to the 
 coating on the lUher fide. In this manner we can ob- 
 tain a fucceflion of fparks from every inch of lurface 
 oppofite to the coating, and from no other part. But 
 VI hat puts this queftion beyond all doubt is, that if we 
 now lay a metal coating on the furface. from which the 
 fparks have been drawn in this manner, and make a 
 communication between the two metallic coatings, by 
 means of a bent wire, we obtain a perfed dilcharge. 
 To coinplete the proof, we need only obferve that this 
 experiment fucceeds whether the glals has been eledri- 
 fied by excited glafs or by excited fealing-wax. There- 
 fore the coated furface may receive the eleftric fluid 
 by the coating, as we fee plainly that it is abftraded by 
 the coating. The ufe of the coatings may be nothing 
 more than to ad, as condudors to every part of the 
 furface of the eledric. None of thefe thoughts efcaped 
 the penetrating and fagacious mind of Dr Franklin. 
 He immediately put it to the teft of experiment ; and, 
 laying a moveable metallic coating on both furfaces, he 
 found the glafs charge perfedly well. He lifted off 
 the coatings ; which operation was accompanied by 
 
 fiafhes
 
 ELECTRICITY. 
 
 178. 
 
 flafhes of light liefween the metallic coverings and the 
 glals from which he feparated them. Having removed 
 the coatings, he applied others, completed the cirele, 
 and obtained a perteft difcharge, not diftingiiifhable 
 from what he would have obtained from the firft coat- 
 ings. 
 
 Thus it was demonftrated, that the glafs plate itfelf 
 acquired by charging a redundant ftratum on one fide, 
 and a deficient ftratum on the other fide ; and we now 
 fee, at once, the reafon why the accumulation turns out 
 greater than what is determined by the theory. The 
 diftance between the redundant and deficient ftratum is 
 lefs than the thicknefs of the glafs ; and this, perhaps, 
 is an unknovvn proportion. 
 
 This precious experiment of Dr Franklin was repeat- 
 ed by every cleftrician, and varied in a thoufand ways. 
 No philofopher has carried this refearch farther than 
 Beccariti ; and he has given ground for a moft impor- 
 tant difcovery in the mechanical theory, namely, that 
 the charged glafs has feveral ilrata, of inconceivable 
 thinnefs, alternately redundant and deficient in eleftric 
 fluid ; and that by continuing the eleftrification, thefe 
 ftrata penetrate deeper into the glafs, and probably in- 
 creafe in number. We have not room here to give even 
 an account of his experiments, and mud refer the phi. 
 lofophical and curious reader to that part of his valu- 
 able Treatii'e where he treats of what he calls vindica- 
 iii:g or recovering elemlricity ; as alfo to a paper by Mr 
 Henly in Phil. Tranf. for 1766, giving account of ex- 
 periments on Dutch plates by Mr Lane. The general 
 form of the experiment is this. He puts two plates to- 
 gether ; he coats the outer furfaces, and charges and 
 difcharges them as one thick plate. Their inner touch- 
 ing furfaces are found ftrongly eleftrical after the dif- 
 charge, having oppofite electricities, and changing thefe 
 eleftricities, by repeated feparations and replacings, in 
 a way ieemingly very capricious at firft fight, but which 
 the attentive reader will find to be according to fixed 
 laws, and agreeably to the fuppoiition that the ftrata 
 gradually fhift their places within the glafs, very much 
 refembling what we obferve on a long glafs rod v.'hich 
 we would render eleftric by induction. In this cafe, as 
 was obferved in n° 57. there are obferved more than 
 one neutral point, he. 
 
 Mr Cavendiih endeavours to give us fome notion of 
 the difpofition of the fluid in the fubftance of the glafs 
 in tlie following manner : Having feparated the coated 
 plate from the machine and from the ground, fuppofe 
 a little of the redundant fluid in B /? J D (fig. 33.) c- 
 qiial to the fluid wanting in E ' ?■ F. jf we now fuppofe 
 all the redundant fluid to be lodged in b f> ^ d, and e ' ff 
 to hold all the redundant matter, and the two coatings 
 to be in their natural ftate, a particle p, placed in the 
 middle of the furiace b d, will be nearly as much at- 
 trafted by i efp as it is repelled by b fi ^ d (exattly fo 
 if the plates were infinitely extended) ; and if the coat- 
 ing be removed, keeping parallel and oppofite to the 
 furface that it quits, there will be very little, if any,, 
 tendency to fly from the glafs to the coating : there 
 will rather be fome difpofition in the fluid to quit the 
 coating and fly to the glais ; becaufe the repulfion of 
 iH^ d is more diminillied than the attraftion of ' e/T. 
 (n°42.) But the difference will be very fmall indeed. 
 (N, B. the refult would be very different if eleftric ac- 
 
 599'' 
 
 tion followed a difTerent law. Were it as — n' thecoatins; 
 
 would be much overcharged ; and were it as — , i 
 
 d 
 
 would be very much undercharged). Now the fatl is, 
 that when the coating is carefully removed, it is pof- 
 feffed of very little clcflricity, not mure ih.^n may rea- 
 fonably be fuppofed to run into it liy bringing away 
 one part before another. It is impofTibie to keep it ma- 
 thematically parallel. 
 
 Hence we may conclude that the greateft part of 
 the redundant fluid is lodged in the glafs if the plates 
 be thin, and the redundant fluid bear but a fmall pro- 
 portion to the natural quantity. Similar reafoni.ig flitws 
 that the greateft part of the deficiency is in the other 
 fide of the glafs ; and that therefore the coatings are 
 very nearly in their natural ftate, and merely ferve the 
 purpofe of condufting. 
 
 We have employed coatings of confiderable thieV- 
 nefs, having holes through them, oppofite to which was 
 fome- gold leaf of the heavieft fort, and almoft free of 
 cracks. We have examined the ftate of the bottom of 
 thole pits in Mr Coulomb's manner, and always found 
 them void of eleftricity. 175 
 
 Thus we learn that' glafs, and probably all other e-C-'<"'j<;<5f uie- 
 leftrics, acquire redundant and deficient ftrata as well asi* "^ '^^ 
 the moft perfeft conduttors, at the fame time that they j^'J.^ '"^ ° 
 may be impervious to the fluid; and we get fome mode 
 of conceiving how the rupture happens by a ftrong 
 charge. This may very probably happen when the 
 ftrata have formed, in alternate order, fo deep in the 
 glafs, that a ftratum, in which the fluid is crowded clofe 
 together, may become contiguous to one deprived al- 
 together of fluid. We cannot, however, fay with con- 
 fidence, whaty/jo«A/ be the effect of this ftate of things ; 
 or of one conftipated ftratum coming in contaft with 
 another. 
 
 This vie\y of the condition of charged glafs explains 
 (we think) feveral phenomena which Teem not well un- 
 derftood by eleftricians. jjg- 
 
 The reliduum of a difcharge is frequently owing to Several 
 a charge extending beyond the coating, where the ;ic.t'''f"oniera 
 tion is confiderably irregular, or different from what ft ^ ''?'■""'*►• 
 would be if the plates were infinitely extended. This 
 outline charge is taken up by the coated part after a 
 very little while, and may again be difcharged. But 
 it alio frequently arifes from another ftratum (much 
 thinner, as it will always be) than the exterior one, co- 
 ming to the furface fome time after the firft difcharge, 
 and being now in a condition for being difcharged. It 
 explains the fparkling that is perceived in fuccejfian be- 
 tween the parts of ajar that is coated in fpots, during 
 the charge, and the very ferfible rtfiduum of the charge 
 of fuch a veffel. It explains the phenomena of Bec- 
 caria's Elcdricitas Vindex (fee Electricity, Lncycl. 
 n'^ 48.), and the great difference that may be found in 
 the different kinds of glafs in this refpeft. It explains 
 the great difference between the fenfation oceafioned by 
 a fpark from a perfectly condndiing furface of confi.* 
 derable extent, and that oceafioned by a fliock, which 
 conveys the fame quantity of fluid accumulated in a - 
 fmall furface of glafs. The difcharge of the firft is al." 
 moft inftantaneous, while that of the laft requires a 
 faiall moment of time, and is therefore Icfs defnltory
 
 6oo 
 
 ELECTRICITY. 
 
 and ahrupt. The or.f is pungent and (lartling ; but 
 thr other is fofter in tlie firll inllant, and fvvclls to a 
 maximum. Therefore, in the medical employment of 
 eleftricity, when the purpofe is to be affcfted by the 
 transfufKiii of a great quantity cf electric fluid, we 
 fhcjuld rcciimmcnd very fmall fhocks from a very large 
 furfjte ot cjoatcd glafs, very faintly electrified, in place 
 ui lhoi:g fparks. Patieats of irritable coidb'tutioiis are 
 frequently alarmed by the quicknefs and pungency of 
 llrong fparks : hut if the balls of Lane's fhock-mea- 
 furer be ftt fo clufe as to give four or five (h jcks in 
 each turn of a fevcn inch cylinder, the fhocks are not 
 even difagreeable. The balls ihould be made uf tine 
 cupelled lilver : in which cafe, the furface will never be 
 hurt by the greateft difcharge ; whereas the dilcharge 
 of four fquare feet of coated glafs will raife fuch a rough- 
 nefs on the furface of brafs as will caufe it to fputter, 
 and dcftroy entirely the regularity of the expenditure 
 of fluid. The fame confideration fliould make us prefer 
 a jar coated entirely with amalgam. This cob-web 
 coating gives a greater foftnefs to the (liock. Lallly, 
 we fee why a powcrlul and permanent elcAriciiy was 
 not produced in the tube filled with melted Ualiiig wax, 
 and treated as mentioned in n" loi. The redundancy 
 and deficiency intended to be produced could only be 
 fuperficial. And becaufe the wax cooled by degrees 
 from the furface to the axis, and the wax is a conduc- 
 tor while liquid, it muft have taken a charge at lail ; 
 and theref(>re muft appear but faintly elcdtrical. 
 i8i. This account of the ftate of charged gLifs promifes 
 us fome afliftance in our attempts to conceive what 
 pafTes in the excitation of glafs by frittion. It ap- 
 pears from Beccaria's exptrirncnts, tiiat the redundant 
 fluid is lodged in the fame manner in both cafes ; for 
 by rubbing one fide of a glafs tumbler, while points 
 were prefented to the oppofite fiutace, and were con- 
 neiled with a wire that communicated with the ground, 
 iSa he gave it a powerful charge. 
 The quan- It is obferved, that when tlie laminx of a piece of 
 
 !"y ',''^1""'Mufeovv ulafs are feparated, by pulling them afunder 
 in a body . , • r ■ -a \. i. . »i .u 
 
 n,3yf,ggjj. without liiferting any inttrunLent between tliem, ttiey 
 
 ceedine are eleftrical when feparated ; one being pofitivc, and 
 greit. the other negative. Mult we not conclude from this, 
 
 that when conjoined they were in the (tate of charged 
 glafs ? If we take this view of it, a body may contain 
 a prodigious quantity of elettric fluid without exhibit- 
 ing any appcaranre of it. Mr Nicholfon found, by a 
 very fair computation from his experiments, that a cubic 
 inch of talc, when fplit into plates of o, oil of an inch 
 in thicknefs, and coated with gold leaf, gave a ihock 
 equal to the emptying 45 condudors, each feven inches 
 in diameter and three feet long, eleftrified fo that each 
 gave a fpark at nine inches diltance. Now, the whole 
 of this was moveable fluid, and no more than what the 
 talc contains when uncledtrified : for no more comes in- 
 to the pofitive fide than goes out of the negative fide. 
 Nay, there is no probability that the quantity move- 
 able in our experiments bears a confiderable proportion 
 to the natural quantity. The quantity of moveable 
 fluid in a man's body is therefore very great : and Lord 
 Mahon is well authorifed to fay, that the fudden dif- 
 placing of this quantity in a returning Jroke, which has 
 been occafioned by a difcharge of a cloud in a very 
 diftant place, is fully adequate to the produftion of the 
 moft violent effefts. But his Lordfliip has not attend- 
 
 ed to the circuniftance, that no fuch difplacement csn 
 happen. The accumulation that can be made in thcj 
 human body is only fup-rficial ; and therefore, altho' 
 the whole fluid of a man's body may change its place, 
 it will not change it with the rapidity that feeni.s ne- 
 ceflary for the violent elTefts of elettricity, except in 
 the very points of communication with the lurrounding 
 bodies, 
 
 We have now feen in what fenfe the idinclciftrics lEj. 
 may be faid to be impervious to the elettric fluid. It is 
 moved in them only to very fma',L^t:d imperceptible 
 dlllances. When a confidcrable lliatuni is difcliarged, 
 the fluid does not come from the extremity of it to th« 
 point of difcharge through the glafs, but through the 
 coating. And when alternate ftrata of redundant fluid 
 and redundant matter are formed, the particles in each 
 fhift their_ places very little, moving perpendicularly to 
 
 the Itratum. 
 
 184 
 
 Even this degree of obltrudion has been denied by The im^icr. 
 forrje very adtlve eleftritians, who have multijilled ex-"^^^'"'")' 
 periments to prove that the fluid paffes freely through'- -f, ['" 
 ghls, and that the theory of coated eleftrics is totally f,„ne. 
 dilFerent from what Franklin imagines. Mr Lyons of 
 Dover has publiflied a nunierous lilt of fingular experi- 
 ments, which he has made with this view, with much 
 trouble, and no fmall expence. They may all be re- 
 duced to this : A wire is brought from the outfide cf 
 a phial, charged by the knob, and terminates in a fliarp 
 point at a imall diltance from a thin glafs plate (it is 
 commonly introduced into a glafs tube, having a ball 
 at the end, and the point of the wire reaches to the 
 centre of the ball) ; and another wire is connetted with 
 the difcharging rud, and alfo comes very near (and fre- 
 quently diolc) to the other fide of the glafs, oppofite 
 to the pointed wire. With this apparatus he obtains a 
 difcharge ; and therefore lays that the glafs is perme- 
 able to electricity. But he does not narrate all the 
 circumitances of tlie experiment. We have repeated 
 all of them that have any real difference (for moll 
 of them are the fame fa£t in difierent forms), and we 
 have obtained difcharges : But they were all very in- 
 complete, except when the glafs was perforated, which 
 happened very frequently. The difcharge was never 
 made with .a full, bright, undivided fpark, and loud 
 fnap ; but with fputtering, and trains of fparks, conti- 
 nued for a very fenfible time ; and the phial was never 
 deprived of a confidcrable part of its charge : and 
 (which Mr Lyons has taken no notice of) the glafs is 
 found to be charged, negative on the fide connected 
 with the pofitive fide of the phial, and pofitive on the 
 other. This charge was communicated to the glafs 
 over a pretty confiderable furface roiuid the points im- 
 mediately oppolite to the wires. This is quite con- ■ 
 formable to the experiments of Dr Franklin and Bec- 
 caria, who diarged a tumbler by grafping it with the 
 hand, and prefenting the infide to-a point electrified by 
 the prime conduftor. The whole experiment is ana- 
 logous to the one narrated in n° 176. iSj 
 
 We may conclude our obfervations on coated glafs Bars tnuch- 
 with mentioning a curious experiment. A flat flick ol . 
 
 fine fealing wax, warmed till it bent pretty readily, was^j'^^"j^£i,y, 
 rendered permanently eledrical, with a pofitive and ne- 
 gative pole, in a manner analogous to the double touch 
 of magnets. A fmall jar was taken, having a hemi- 
 fphere on the end of its infide wire, and another on the 
 
 end
 
 ELECTRICITY. 
 
 60 1 
 
 itnonie- 
 thcreof. 
 
 «iJ of a flifTwirc projcftiiig from the outer coating, 
 and then turned up parallel to the hifide wire ; To that 
 the two hemifphercs ilood equally high, and about 
 three inches afunder. This jar was eleftrified fo weak- 
 ly, as to run no rifle of a fpontaneous difcharge. The 
 flat faces of the two hetnifpheres were now applied to 
 the flat fide of the fealiiig wax, and were moved to 
 and fro along it, ovcrpafling both ends about an inch 
 with each hemifphere. The experiment was very 
 troublefome ; for the phial often difcharged itfclf along 
 the furface of the fealing wax, and all was to begin 
 again. But, by continuing this operation till the feal- 
 ing wax grew quite cold and hard, it acquired a very 
 fenfible eleiSlricifm, vhich lafled feveral weeks when 
 kept with care ; hut ftill it was not much more fenfible 
 than that of the fealing wax, which congealed between 
 two globes oppolltely eletlrified. 
 
 After this application of the theory to the plieiio- 
 mena of coated glafs, it will not be neceffary to employ 
 much time in its application to the eleftrophorus. The 
 general propofitions from n"" 14. to 25. and their com- 
 panions in n'^ 38 — 43, will enable us to ftatc with pre- 
 cifion (when combined with the law of eledric adion) 
 the aftions of every part of this apparatus ; and confi- 
 derable affillance will be derived from a careful confide- 
 ratioii of our analyfis of Profelfor Richmanirs experi- 
 ment in n" 156. But we mufl; content ourfclves with 
 a general, popular view of tliefe particulars, which 
 may be fufficient for making us underftand what will 
 be the kind, and fomewhat of the inlenfity, of the ac- 
 tion of its different parts. 
 
 The eledlrophorus confifts of three parts. The chief 
 part is the cake ABCD (fig. 34.) of fbme eledtric ; 
 fuch as gum lac, fealing wax, pitcl), or other refinous 
 compofition. This is melted on fome conducing plate, 
 DCFE, and allowed to congeal ; in which ftate it is 
 found to be negatively eleftric. Another condufting 
 plate GHBA is laid on it, and may be raifed up by 
 iilk lines, or any infulating handle. We Ihall call 
 ABCD the CAKE, DCFE the sole, and GHBA the 
 
 COVER. 
 
 The general appearances not having been fo fcientJ- 
 fically clafled in the article Electricity as could be 
 wiflitd, we fliall here narrate them, very briefly, in a 
 way more fuited to our purpofe. In comparing the 
 theory with obfervation, it will be proper to make all 
 the three parts of confiderable thicknefs, and of no 
 great breadth. Although this diminifhes greatly the 
 mod remarkable of the adions, it leaves them fufficient- 
 ly vivid, and it greatly increafes the fmaller changes 
 which are inftruttive in the comparifon. The general 
 fafts arf, 
 
 1 . If the fole has been iufulated during the congela- 
 tion of the eledlrlc, till all is culd and hard, the whole 
 is found negatively elcflric, and the finger draws a fpark 
 from any part of it, eipecially from the fole. If allow- 
 ed to remain in this fituation, its electricity grows gra- 
 dually weaker, and at lalt difappears : but it may be 
 excited again by rubbing the cake witli dry warm 
 flannel, or, which is the befl, with dry and warm cat 
 or hare fur. If the cover be now fet on the cake by 
 its infulating handle, but without touching the cover, 
 and again feparated from the cake, no eleftricity what- 
 ever is obferved in the cover. 
 
 2. But if it be touched while on the cake, a fharp 
 SuppL. Vol. I. Part II. 
 
 pungent fpaik is obtained from it j and if, at tlie fame 
 time, the fole betouchcd with the thumb, a very fenfi- 
 ble (hock is felt in the finger and thumb. 
 
 3. After this, the cltflrophorus appears quite in- 
 aftive, and is faid to be dead ; neither fole nor cover gi- 
 ving any fign of eleftricity. But, 
 
 4. When the cover is raifed to fome diftancc from 
 the cake (keeping it parallel therewith), if it be touch- 
 ed while ill this fituation, a fmart fpark flies, to lomc 
 diflance, between it and the finger, more remark- 
 ably from the upper fide, and ftill more from its edge, 
 which will even throw off fporks into the air, if i*^ be 
 not rounded off. As this diininiflies the defired effects, 
 it is proper to have the edge fo rounded. This fpark 
 is not fo fiiarp as the former, and refembles that from 
 any eleftrified condudfor. 
 
 5. The eleftricity of the covci', while thus raifed, is 
 of the oppofite kind to that of the cake, or is pofitive. 
 
 6. The eleftricity of the cover while lying on the 
 cake is the fame with that of the cake, or negative. 
 
 7. The appearances n'^ 2, 5, 4, may be repeated for 
 a very long time without any fenfible diminution of 
 their vivacity. The inllrumcnt has been known to re- 
 tain its power undiminifliod even for months. Thig 
 makes it a fort of mag-azine of eieflricity, and we can ' 
 take off the eledlricity of the cake and of the cover a» 
 charges for feparate jars, the cover, when raifed, char- 
 ging like the prime conduilor of an ordinary tleiSrical 
 machine ; and, when let on the cake, cliarging it like 
 the rubber. This caufcd the inventor, Mr Volta, to give 
 it the name of Electrohhorus. 
 
 8. If the fole be infulated before putting on the 
 cover, tbe fpavk obtained from the cover is not of that 
 cutting kind it was before : but the fame (hock will be 
 felt if both cake and cover be touched together. 
 
 p. If the cover be again raifed to a confiderable height, 
 the fole will be found eleftrical, and its elettricity is 
 that of the cake, and oppolite to that ol the cover. 
 
 10. After touching both cover and fole, if the cover 
 be railed and again iet down, without touching it while 
 aloft, the whole is again inartive. 
 
 11. If both cover and fole be made inactive when 
 joined, they (hew oppolite eleflricities when feparated, 
 the fole having the eleftrlcity of the cake. 
 
 12. If both cover and fole be made inaftive when 
 feparate, they both fliew the oppofite to the eledtricity 
 
 of the cake when joined. j»_ 
 
 Let us now attend to the difpofition of the eleftricalDifjorition 
 fluid in the different parts of the inilrument in their va- of the fluid 
 rious fituatlons, and to the forces which operate mutually 
 between them. A''. B. Experiments for examinilig this > 
 inilrument are beft made by (etting the three jdates 
 vertically, .'"upported on glafs Ibilks, with leaden feet, 
 to fleady them. A very fmall elefkrometer may be at- 
 tached to the outer furfaces of the cover and fole. 
 
 If the extent of the plates were inconiparablv greater 
 than tiieir thicknefs, we mav infer from n"' 92, See. tl;at 
 the redundant fluid and matter v."ould be dilpofed in 
 parallel ftrata, and that the aftions wou^d be the fame 
 at all diftances. But fince this Is not the cafe, the dif- 
 pofition of the fluid will be fomewhat different ; anil 
 whatever it is, the aftion of any ftratnm will be cimt- 
 nilhed by an increafe of dillancc. The following de- 
 fcription cannot be very different from the truth : 
 I. The cake grows negative by cooling ; and if it 
 4 G vveio
 
 602 
 
 ELECTRICITY. 
 
 iss 
 
 Explana- 
 tion of the 
 primitive 
 Jfite. 
 
 189 
 
 190. 
 
 were alone, !t would have a negative fuptrficial ftratura 
 on both fides, of greater tliicknefs near the edges ; and 
 the fluid would probably grow deufer by degrees to the 
 middle, where it would have its natural denlity. This 
 (lifpofitlou may be it)ferred from n" 92, 9^, and 98. 
 But it cools in conjuuition with the iole, and the at- 
 traftion of tlie redundant matter in the cake ; for the 
 moveable fluid in the fole difturbs its uniform ditfufion 
 in the fole, and caufes it to approach the cake. Anil 
 becanfe this, in all probability, happens while the cake 
 is Hill a conduftor, the difpofuion of its fluid will be 
 different from that defcribcd above, and the final difpo- 
 fuion of tl\e fluid in the cake and fole will refemble that 
 defcribed in n°9J, where the plates E and A reprefent 
 the cake and fole. But becaufe we do not know pre- 
 cifely the gradation of derjiity, and aim only at general 
 notions at prefent, it will be fufficient to confider the 
 take and fole as divided into two flrata only ; one re- 
 dundant in fluid, and the other deficient, neglefting the 
 neutral ilratum that is iuterpofed between them in each. 
 The cake, then, confifl;s of a ilratum AB^aA contain- 
 ing redundant matter, and a Ilratum abQ,V) containing 
 redundant fluid : and the fole has a ftratum DC n m 
 containing redundant fluid, namely, all that belongs 
 naturally to the fpace DCFE, and a ftratum m n FE 
 containing redundant matter. This may be called the 
 PRIMITIVE STATE of the cake and iole ; and if once 
 changed bv communication with untleftrified bodies, it 
 can never be recovered again without fome new excite- 
 ment. 
 
 II. If the fole be touched by any body communica- 
 ting with the ground, fluid will come In, till the repul- 
 fioa of the redundant fluid in the fole for 3 fuperficial 
 particle^ is equal to the attraftion of ;he redundant 
 matter in the cake for the fame particle. What has been 
 faid concerning infinitely extended plates rendered neu- 
 tral ou one fide, may fuflice to give us a notion of the 
 prefent difpofition of the fluid in the fole. The under 
 furface will be neutral, and the fluid will increafe in den- 
 fity toward the furface DC. The fole contains more 
 than its natural quantity of fluid, but is neutral by the 
 balance of oppofite forces. Let it now be infulated. 
 This difpofition of fluid may be called the comman Jiate 
 of the eledlrophorus. 
 
 III. Let the cover GHBA be laid on it. The par- 
 ticle %, at the upper furface of the cover, mud be more 
 attraftedby the redundant matter in the ftratum ABcrt 
 than it is repelled by the redundant fluid in the remoter 
 ftrata ; for the fluid in the cake is lefs than what be- 
 longs to it in its natural Hate, and therefore 2; is attrac- 
 ted by the cake. The redundant fluid which has come 
 into the remote fide of the fole is lefs than what would 
 faturate the redundant matter of the cake^ becaufe it 
 only balances the excefs of the remote aftion of this 
 matter above the nearer adlion of th.e compreffed fluid 
 in the fole ; and this fmaller quantity of redundant fluid 
 afts on z at a greater diilance than that of the redun- 
 dant matter in the cake. On the whole, therefore, the 
 particle 2, lying immediately within the furface GH, 
 is attrafted ; therefore fome will move toward the cake, 
 and its natural ilate of uniform diffufion through the 
 cover will be changed into a violent itate, in which it 
 will be compreflcd on the furface AB, being abftrafted 
 from the furface GH. It will now have a ftratum 
 OgpYl, containing redundant matter, and another 
 
 191. 
 
 191 
 
 ^/BA, containing redundant fluid. But this will dii'- 
 turb the arrrangcment which had taken place in the 
 fole, and had rendered it neutral on the under furface. 
 We do not attend to the fluid in the cake, but confider 
 it as immoveable ; for any motion which it can get will 
 be fo fmall, that the variations of its adlion will be al- 
 together iiifignificant. The particle v, fituated in that 
 furiacc, will be more repelled by the comprefled fluid 
 in the (Iralum ^/i CA than it is attrafted by the equi- 
 valent, but more remote redundant matter in GH^^. 
 Fluid is therefore difpofed to quit the furface EF, and the 
 fole appears pofitively eleftric ; very little indeed, if the 
 cover be thin. AU this may be obferved by attaching 
 a fmall Canton's eledlromcter to the lower furface of 
 the fole, or by touching the fole with the elettronieter 
 of fig. 8. and then trying its eleftricity by rubbed wax 
 or glafs. 
 
 IV. A particle of fluid z, placed immediately with- 
 out the furface GH, will'be more attratled by the de- 
 ficient Ilratum G\\ p g and by A.Yila than it is repel- 
 led by the redundant ftrata beyond them, and the cover 
 muft be Icnfibly negative. This is the common ftate of 
 the whole inftrument after fettinor on the cover. It is 
 flightly pofitive on the lower furface of the fole, and 
 much more fenfibly negative on the upper furface of the 
 cover. A fmart fpark will therefore be feen between 
 it and the finger, fluid will enter, till the attradlion of 
 the redundant matter in ABia is balanced by the re- 
 pulfion of the redundant fluid in DCFE. 
 
 V. A fpark will now be obtained from the fole, be- DeadjUi: 
 canfe it was faintly pofitive before, and there has been 
 added the atlion ot the fluid which has entered into the 
 cover. The fluid in the fole is therefore difpofed to fly 
 
 to any body prefented to it. But when this has hap- 
 pened, the equilibrium at the furface GH is deftroyed. 
 and that furface again becomes negative, and will at- 
 traft fliiid, although the cover already contains more 
 than its natural quantity. A fmall fpark will therefore 
 be feen between the cover and any condufling body 
 prefented to it. By touching it, the neutrality or equi/- 
 librium is reftored at GH ; but it is deftroyed again at 
 EF, which wilt again give a pofitive fpark, which, in 
 its turn, again leaves GH negative. This will go ou 
 for ever, in a feries of communications continually di- 
 minilhing, fo as foon to become infcnfible, if the three 
 parts of liie electrophorus be thin. This makts it pro- 
 per to make them otherwife, if the inftrument be in- 
 tended for illurtrating the theory. 
 
 At laft the equilibrium is completed at the furfaccs 
 GH and EF, and both are neutral in relation to fur- 
 rounding bodies, although both the cover and fole con- 
 tain more than their natural Ihare of eltclric fluid. We 
 may call this the neutral or dead ftate of the elec- 
 trophorus. 
 
 This ilate may be produced at once, inftead ot ^'■"^^ ciured 
 it by thele alternate touches of GH and EF. If wttjiatc^ 
 touch at once both thefe furfaces, we have a bright, 
 pungent fpark, and a fmall ftiock. If this be the ob- 
 ject of the experiment, the ftate N° IV. which gives oc- 
 cafion to it, may be called the charged ftate of the 
 eleitrophorus. 
 
 When the inftrument has thus been rendered neutral 
 in relation to furronnding bodies, it is plain that it may 
 continue in this ftate for any length of time without 
 any diminution. of its capability of producing the other 
 
 phenomena.
 
 T9 + 
 
 ELECT 
 
 pTifHi jrena. provldtd onlv tliat no fluid pafs from the 
 cover to the cake. We (Jo wA fully uiidcrilaiui what 
 prevents this communication, nor indeed what prevents 
 the rapid efcape from an overcharged body into the air. 
 This caufe, whatever it be, operates here ; and the bell 
 way of preventing tlie thffipation, or the ablorption by 
 the calit, is to keep the elcciiopliorus w itli its cover on. 
 It will come into this iientral tlate by difiipiition from 
 the fole, and ablorption by the cover, in no very lonjr 
 time ; and after this, will remain neutral, retaining its 
 power with great obftinacy, elpecially if tlie cake and 
 phtes are very thin. 
 •yrj-ii^or ^"l- If the cover be now removed to a dill.mce, botli 
 anej'tats. parts of the apparatus will (hew ftrong marks of electri- 
 city. The cover contains much redundant fluid, and 
 muft appear (Irongly pofitive, and will give a bright 
 fpark, which r.iay be employed for any purpofe. It may 
 be employed for charging a jar poiltively by the knob, 
 if we jult touch the cover with the knob. The fole 
 will attract fluid, or be negative, although it contain 
 more than its natinal quantity of flni<l, and it will take 
 a fpaik. The fole therefore, in the abfencc of the co- 
 ver, may be employed to charge ajar negatively by the 
 knob. By touching it with the linger, or wiili the knob 
 of a jar held in the hand, it is reduced to the common 
 ftate defcribed in N^ II. ; ajid now all the former ex- 
 periments may be repeated. We niLiy c.iU this the ac- 
 TivF. or the charging Itate. 
 U&ro- This ftite of tlic apparatus has caufed it to get the 
 
 horu* rot name Lhdrophorus. Volta, its undoubted inventor, 
 magazrie called it EhP.roforo perpctuo ; for it appeals, as has been 
 ty hi t a 3'''^3dy obfervcd, to contain a magazine of eledtricity. 
 )lle<fting The cover, when removed, will charge a jar held in the 
 lachine. hand pofitively ; and having done this fervice, it will 
 charge a jar negatively when again fet on the cake. 
 The folc, in the abfence of the cover, will charge a 
 third jar negatively ; ai'd then, when the cover, after 
 being touched, is fet down again, it will charge a fourth 
 jar ])ufitively. It will not be difficult to contrive a 
 fimple mechanifm, conntfted with the motion of the co- 
 ver, which fhall connect the joined parts with two jai s, 
 and (hall conneft them, when feperated, vvith two 
 others ; and thus charge all the four with great expe- 
 dition. AU this is done without any new excitation of 
 the eleftrophorus. But it is by no means a nmgazine 
 of electricity which it gradually expends : it is a COL- 
 LKCTOR of electricity from the furrounding bodies, 
 which it afterwards imparts to others, and may be em- 
 ployed to difcharge jars in the fame gradual manner as 
 to charge them, 
 ipj. VII. If the elcftrophorus is not Infulated, a fliock 
 
 may flill be obtained, by firft touching the folc, and 
 then, without removing the finger, touching the cover : 
 but tin's will not be fo fmart as when the negative cover 
 is touched at the fame time that we touch the fole, 
 more higlily pofitive than when it communicates with 
 the ground. The difference muft, however, be almoil 
 imperceptible when tiie pieces are thin. 
 jng VII. If the electrophorus is not infulated, the cover, 
 
 when put on, will give a fpark in -the manner already 
 mentioned, and it will be fomewhat flrongerthan when 
 it is infulated ; becaufe the fluid is allowed to efcape 
 from the fole, and does not obftrudt the entry into the 
 cover. If we then, without removing the finger from 
 the cover, touch the fole, nothing is felt ; but if we firft 
 
 R r C 1 T Y. 603 
 
 touch the fole, and, witliout removing the finger from 
 it, touch the cover, v,'C obtain a fhock. This is evi- 
 dent from the theory. By this fcriea of alternate 
 touches, the period of the eleftrophorus is compk'ted. 
 The eledroiiliorua is charged, or rendered neutral, by 
 touching the plates when joined ; then, by touching 
 botli when feparated, the wliolc is reduced to the com- 
 mon Hate. When leparated, from being in the neutral 
 ftate, they have oppolite electricities, the fole fhewing 
 that of the cake When brought together, each iu 
 the common ftate, they have oppufite electricities, the 
 cover Ihewing that <if the cake. 197 
 
 IX. Wlien, by long e-spofine to the air without its How it 
 cover, the electrophorus has loft its virtue, it may |,t "'^V be re- 
 brought again into an aftive ftate in a variety of ways.'^'^'^''^''" 
 Its furface may be rendered negative by friction with 
 dry cat or hare (kin, or warm flannel. It may be i-en- 
 dered negative by Ltting on it ajar charged negatively 
 en the irdide, and then touching the knob with any 
 thing conmiunicating with the ground. This is the 
 moll cxpediticus method, and will y-ive it a hisjli dej/rec 
 of excitation, it the jar be of lize, and it the eleclro];ho- 
 rus be covtied with a plate of tinfoil which comes ii.io 
 contact all over its furface Tiiis however requirtstiie 
 previous charging of the jar ; therefore it will be :;s ex- 
 peditious and efFeftual to conneft this furface with the 
 rubber of an electrical inacliine. Vv"c had almoft for- 
 gotten to remark, that the cfTeifts of bringing the cover 
 edgewife to the cake follow clearly from the theory, as 
 will appear to the attentive reader without further ex- 
 planation. 
 
 The electrophorus has been compared to a charged j, ;'^^,t (^. 
 plate of coated glafs. It is true that it may be broH^ht mWir ioi 
 into an external Hate which very much refe.nbhs a char- charged 
 ged pane ; namdy, when the cover, in its natural fti.tejP*'"^' 
 is fet on tl;e elc6trophor-us in its natural ftate : and ac- 
 cordingly it gives a (hock, and the two exterior fu. faces 
 become neutral ; but the internal conftitution, and tlie" 
 ading forces, are totally and eJentiaUy different. I'he 
 t\vo coatings of the pane would not, when fcparat;:'!, 
 exhibit the appearances of the eleCtrophurus ; nor, when 
 touched in their disjoined ftate, will they produce the 
 fame cficds when joined. In the operation of coatt J 
 glafs, the conftant or invariable part, the glafs is not the 
 ogent, it is n.erely the occajion of the action, by alknvinT 
 the accumulation. In the cleftrophorus, the electric, 
 which is the .:onftaiit invariable part, is the agent hroc'u- 
 cing the accumulation. The electrophorus is an origi- 
 nal, and a very ingenious and curions eledtrical ma- 
 chine. Nothing has fo much contributed to I'preaJ 
 fome general, though flight, acquaintance with the me- 
 chanical principles of electricity. Ihe numerous dab- 
 blers in natural knowledge had been diverted from fci- 
 entific purfuit by the variety of the lingular and amu- 
 fing effects of eleflricity, and had really attained very- 
 little connected knowledge. The effects of the elec- 
 trophorus ybrff^/ this knowledge on them ; becaufe no 
 ufecan be made of it without a pretty clear conception 
 of the dlipofition of the electricity, and the kind and 
 inteiility of the aftions. It is therefore moft ungrate. 
 ful in the experimenters who have attained better views, 
 to attempt to rob Mr Volta of the real merit of difcove- 
 ry, by (hewing that its effects are fimilarto thcfe of Mr 
 Syminer's ftockings, or of Cigna's plates, or of Frank- 
 lin's charged or difcharged glafs panes. And the at. 
 4 G 2 tempt
 
 6c4 
 
 199 
 
 Condenfator 
 of cleilrl- 
 
 SCO. 
 
 E E E C T R I C I T Y. 
 
 tempt deftroys itfelf : for it fliiws the ignorance or in- eleftric, we mny elcftrify the cpver again, while fo near 
 
 attention of its authur ; for the fmiilaiity is not real, tht metal plate, to the dcgvee 6, before it will ftreaiti 
 
 as will appear char to iiiiy pcrfon who will exaitjine ofl into the air. If it be now removed from the lying 
 
 tHings minutely and fcientiFically, proceeding in this plate, the fluid would ralfe the clcdtrumeter to 10, did 
 
 fxaraiiiation on fuppofitions fimilar to thofe which we it not immediately llream off ; and an elcdric excite- 
 
 employed in the analyfis of Richirann's experiment. It mcut of any kind which could only raife this body to 
 
 was indeed in fubfervfency to thi^ examination ihat we the degree 6 by its iiitrnfity, will, by this apparatus, 
 
 entered into the detail of that experiment, it being a raife it to the degree 10, if only copious enough in ex- 
 
 iimpler cafe. The accurate examination of Richmann'a tent. If we dp the fame thing when the wire is taken 
 
 experiment requires the fluxionary calculus in its refined away whicli conne(Sts the lying plate with the ground, 
 
 form. In the prefent tjuellion five afting ftrata are to we know that tl'.e fan-.e diminution of the electricity of 
 
 Le confidered, which renders the formulie very conipli- the other plate cannot be produced by bringing it down 
 
 cated, and indeed intraftable, iinlefs we make the plates into the neighbourhood of the lying plate (lee n" 134, 
 
 extremelv thin ; which, fortunately, is th'e beft form of &c. 151, &c:) 
 
 the inftruinent. We have completed this mathematical Here we fee the whole theory of Mr Volta's conden- Theory 
 
 analyfis ; and the popular view here given is the refult fer. He feems to have obfcured his conceptions of it'''"'-'uf. 
 
 of tint computation. by having his thoughts running upon the elcflrophorus 
 
 The eleftriclans are no lef3 obliged to Mr Volta for lately- invented by him, and is kd into fruitleis attempts 
 another machine, or ir.itrumcnt, from which the iludy to explain the advantages of the imperfett conduttor 
 of Nature's operations has derived, or may derive, im- gbove the perfcft infulator. But the apparatus is alto- 
 menfe advantages. We mean the condenser or col- gether different from an eleftrophorus, and is more ana- 
 LECTOR of electricity. We refer to the article Elec- logons in its operations to a coated plate not charged 
 TRiciTY ill the EncycJopjiUa for a defcription of the nor infulated on the oppofite fide ; and fuch a coated 
 inftrumeiit, and fome account of its effeifts and proper- plate lying on a table is a complete condenfer, if the 
 ties. The general effeft is to render feufible an acci- upper coating be of the fame fize with the plate of the 
 mulatlon or deficicncv of eleflric fluid fo flight tliat it condenfer. All the direftions given by Mr Volta for 
 will not affeft the moft delicate ckcfrtmieter ; and it the preparation of the imperfect conduftors (liew, that 
 produces (at lead in the opinion of Mr Volta) this ef- the efFetl produced is to make them as perfefl conduc- 
 feiS, by employing for the fole of an eleftrophorus a tors as pofiible for any degree of eleftricity that exceeds 
 bcdv which is an imj erfeft conduftor, fuch as a plate a certain fmsll intenfity, but fuch as fhall not fufferthis 
 of well dried maible, or well dried, but not baked, very weak cleAricity to clear the firll flep of the con- 
 wood ; or even a condufting body, covered with a bit duit. The marble muil be thoroughly dried, and even 
 of dry taffety or other filk. Mr Volta, Cavallo, and heated in an oven, and either uicd in this warm ftate, 
 others, who have written a great deal on the fubjeft, or varnifhed, fo as to prevent the reabforption of moif- 
 h^ve attempted to fhew how thefe fubftances are pre- ture. We know that marble of (lender dimenfions, fo- 
 ferable (and they certainly are preferable in a high de. as to be completely dried throughout, will not conduft 
 grte) to more perftft infulators : but not having taken till it has again become moift. A thick piece of marble 
 pains to form precife notions of the difpofilion and ac- is rendered fo, fuperficially only, and llill conducts in- 
 tion of the eleftric fluid in the fituations afforded by ternally. It is then in the bell poffible flate. The 
 tf»e inftniment, their.j;eafonings have not been very clear, fame maybe faid of dry unbaked wood. Varnifiiing 
 We think that an adequate conception of the effentials the upper furface of a piece of marble or wood is equi- 
 of the propofed inftrument may be acquired by meaHs valent to laying a thin glafs plate on it. Now this me- 
 of the following confiderations : thod, or covering the top of tlie marble, or of a book,, 
 
 Furnifli the cover of an eleftrophorus with a gra- or even the table, with a piece of clean dry filk, makesi 
 duated eleftrometer, which indicates the proportional them all the moft perfeft condenfators. This juft view 
 degrees of eleSricily ; eleflrify it pofitively to any de- of the matter has great advantages. It takes away the 
 gree, fuppofe fix, while held in the hand, at fome di- niyfterious indiilinftnefs and obfcurity which kept the 
 ftance, right over a metal plate lying on a wine glafs inftrument a quackilh tool, incapable of improvement, 
 as an iniul.Hting {land, but communicating with the We can now make one incomparably better and more 
 ground by a wire. Bring it gradually down toward fimple than any propofed by the very ingenious inven- 
 the plate. Theory teaches, and we know it by expe- tor. We need only the fimple moveable plate. Let 
 rimeut, that the eleftrometer will gradually fubl'ide, this be varnifhed on the under fide with a moderately 
 and perhaps wilt reach to 2- before the eleftricity is thick coat of the pureft and hardeft vernis de Marlin,. 
 communicated in a fpark. Stop it before this happens, or coach-painters varnifh ; and we have a complete con- 
 In this ftate the attraftion of the lying plate produces denfator by laying this on a table. If it be conneftedl 
 a compenfation of four degrees of the mutual repulfion by a wire with the fubflance in which the weak ai>d' 
 of the parts of the cover, by conflipating the fluid on imperceptible eleftricity is excited, it will be raifed,; 
 its under furface, and forming a deficient ilratum above, (provided there be enough of it of that fmaU intenfity )i 
 This needs no farther explanation after what has been in the proportion of the thicknefs of the varnifli to the- 
 faid on the charging of coated glafs plates. Now we fourth part of the diameter of the plate. This degree 
 can fuppofe that the efcape of the fluid from this body of condenfation will be procured by detaching the coa- 
 into the air begins as foon as elcftrified to the degree nefting wire from the infulating handle of the condcj). 
 6, and that it will fly to the lying plate with the de- fer, and then raifing the condenfer from the table. It: 
 gree 2, if brought nearer. If we can prevent this will then give fparks, though the original eleftricity 
 »:oaimunica.tion to the lying plate, by interpofing an could no,, fenfibly affeft a flaxen fibre^ 
 
 It;
 
 ELECT 
 
 It muft be particularly noted, that it can produce 
 this condenfation only when there is fluid to condenfc ; 
 that is, only when the weak tledtricity is diffnfed over 
 a greater fpsce than the plate of the ccrdenfer. In 
 this way it is a mod excellent collector of the weak at- 
 inofiiiiLTic electricity, and of all (liffufed elcftrlcity. Cut 
 to derive the fame advantage from it in ma>:y very li:te- 
 rijling cafes, fuch as the inquiry into the elcdtricity ex- 
 cited in many operations of N;iture ou fmaU quantities 
 of matter, we mull have condenfers of various fizes, 
 fome not larger than a filver penny. To cnnftrudl thefc 
 in perfeiSion, we mull; ufe the pureft and hardeft var- 
 nifh, of a kind not apt to crack, and highly coercive. 
 This requires experiment to difcover it. Spirit varnifhes 
 are the moil coercive ; but by their difference of con- 
 trartion by cold from that of metals, they foon appear 
 frofly, and when viewed through a lens, they appear all 
 fiiivered : They are then ufclefs. Oil varnlfl>e3 hav£ 
 the requifite tonghnefs, but are much inferior in coer- 
 cion. We have found amber varnilh inferior to copal 
 ■varnilh in this relpcft, contrary to our expectation. 
 On the whole, we (hould prefer the finell coach-painters 
 varnilh, new from the (hop, into which a pencil has ne- 
 ver been dipped : and we muft be particularly careful 
 to clear our pencils of moifture and all condufting mat- 
 ter, which never fails to taint the varnifh. We fcarcely 
 need remark, that the coat of varnilh on thefe fmall con- 
 denfers (hould be very thin, otherwife we lofe all the 
 advantage of their fmallnefs- 
 
 Mr Cavallo lias ingenioufly improved Volta's con- 
 denfer by connefting the moveable plate, after removal, 
 with a fmaller condenfer. The efiift of this is evident 
 from n" i^o. But the fame thing would have been 
 generally obtained by ufing the fmnll condenfer at firil, 
 or by ufing a ftiU thinner coat of varnilh. 
 
 It will readily occur to the reader, that this inftru- 
 ment is not inftantaueous in its operation, and that the 
 application muft be continued for fome time, in order 
 to colleft the minute electricity which may be excited 
 in the operations of nature. He will alfo be careful 
 that the experiment be fo condufted that no ufelefs ac- 
 cumulation is made anywhere el(e. When we expeft 
 eleftricity from any chemical mixture, it never (liould 
 be made in a glafs vefTel, for this will take a charge, 
 and thus may abfoib the whole excited electricity, ac- 
 cumulating it in a neutral or infenfible ftate. Let the 
 mixture be made in vefTtls of a condufting fubftance, iu- 
 fulated with as little contaft as polFible with the infula- 
 ting fupport ; for here v/iU alfo be fomething like a 
 charge. Sufpend it by filk, threads, or let it reft on 
 the tops of three glafs rods, &c. 
 
 After this account of the I^eyden phial, eleftropLo- 
 rus, and condenfer, it is furcly unneceffary to employ 
 any time in explaining Mr Bennet's moft ingenious and 
 ufeful inftrumcnt called the doubler of ele&rk'ity . The 
 explanation offers itfelf fpontaiieouily to any perfon who 
 underftands what has been faid already. Mr Cavallo 
 has with induilry fearched out all its imperfeitions, and 
 has done fomething to remove them, by feveral very 
 ingenious conftruftions, minutely deicribed in his Trea- 
 life on Eleftricity. Mr Bennet's original inftrumenc 
 may be freed, we imagine, as far as fecms pofiible, by 
 ufing a plate ot air as the intermedium between the three 
 plates of the doubler. Stick on one of the plates three 
 very fmall fpheruks made from a capillary tube of glafs, 
 
 R I C I T Y. 60 j; 
 
 or from a thread of fealing wax. The other plate be- 
 ing laid on them, rcfts on mere points, and can fcarce- 
 ly receive any friftion which will dillurb the experi- 
 ment. Mr Nicholfon's beautiful niechunifm lor expe- 
 diting the multiplication, lias the inconveniency of bring- 
 ing the plates towards each other edgewife, which will 
 bring on a fpark or communication fooner than may 
 be dcfired : but this is no inconvenience whatever in 
 any philofophical rrfearch ; becaufe, before this hap- 
 pens, the elettricity has become very dilUnguiihable as 
 to its kind, and the degree of multiplirati'jn is little 
 more than aa amufcmcnt. The. fpark may even (ervc 
 to give an indication of the original intcnijy, by means 
 of the number of turns neceffary for producing it. If 
 the fine wires, which form the alternate conncftions in 
 fo ingenious a manner, could be tipped with little balls 
 ^o prevent the diffipation, it would be a great improve- 
 ment indeed. An alternate motion, like that of a 
 pump-handle, might be adopted with advantage. This 
 would allow the plat«s to approach each other face to 
 face, and admit a greater multiplication, if thought ne- 
 ceffary. 
 
 One of the moft remarkable fafts in eleftricity is the DiTiration 
 rapid dilTipation by (liarp points, and the impolfibility of eki51ri- 
 of making any confiderablc accumulation in a body '''X '^rora 
 which has any fuch, projefting beyond other parts of •'^^ 
 its furface. The diflipation is attended with many re- 
 markable circumftanccs, which have greatly the appear- 
 ance of the aftual efcape of fome material fubftance. 
 A ftream of wind blows from fuch a point, and quick- 
 ly eleftrifies the air of a room to fuch a degree, that an 
 eleftrometer in the fartheft corner of the room is affeft- 
 ed by it. This diffipation in a dark place is, in many 
 inllances, accompanied by a bright train of light di- 
 verging from the point like a firework. Dr Franklin 
 therefore was very anxious to reconcile this appearance 
 with his theory of plus and minus eleftricity, but does 
 not exprels himfelt well fatisfied with any ex|jlanatiou 
 which had occurred to him. From the beginning, he 
 faw that he could not confider the ftream of wind as a 
 proof of the efcape of the elcftric fluid, becaufe the 
 fame ftream is obferved to ilfue from a fliarp negative 
 point ; which, according to his theory, is not difperfing, , 
 but abforbing it. Mr Cavendifli has, in our opinion, , 
 given the firll fatisfattory account of this phenomenon. 
 
 To fee this in its full force, the phenomenon itfelf iij. - 
 muft be carefully obferved. The ftream of wind ii 
 plainly produced by the efcape of fomething from the 
 point itfelf, which hurries the air along with it ; and 
 this draws along with it a great deal of the furround- 
 ing air, efpecially from behind, in the fame manner as 
 the very lltuder thread of air from a blow-pipe hurries 
 along with it the furrounding air and flame from a coii- 
 fiderable furface on all lides. It is in this manner that 
 it gathers the whole of a large flame into, one mafs, 
 and, at laft, into a very point. If the fmoke of a little 
 rolin thrown on a bit of live, coal be made to rife quiet- ■ 
 ly round a point projefting from an eleftrified body, 
 continually fupplied from an eleftrical machine, the 
 vortices ot this fmoke may be obferved to curl in from 
 all fides, along the wire, forming a current of which 
 the wire is the axis, and it goes oft" completely by the 
 point. But if the wire be made to pais through 3 
 cork fixed in the bottom of a wide glafs tube, and if 
 its point projeft not beyond the mouth of the tube,. 
 
 th«.
 
 Co6 * E L E C T R I C I T Y, 
 
 the afflux of the air from behind is prevented, and we 
 have no flream ; but if the ci)rk be removed, and the 
 wire Hill occupy the axis of the tube, but without 
 touching the fides, we have the ftream very dilliiidtly ; 
 and fmuke which riles round the far end of the tube is 
 drawn into it, and goes of at the ];oint of the wire. 
 Now it is of importance to obferve, that whatever pre- 
 vents the formation of this llreani of wind prevents 
 the diihpation oi elettricity (for we (hall not fay efcape 
 of eletbic fluid) from the jjoint. If the point projedt 
 a quarter of an inch beyond the tube, or it the lube be 
 open behind, the ilream is llrong, and the dillipation fo 
 rapid, that even a very good niacliine is not able to raife 
 a Hcnly's eleftrometcr, {landing on the conduttor, a 
 very few degrees. If the tube be flipped forward, fo that 
 the point is juft even with its moutli, the diffipation of 
 eletlricity is next to notliing, and does not exceed what 
 might be produced by inch air as can be collcfted by a 
 fuperficial point. If the tube be made to advance half 
 an inch beyond the point which it furrounds, the diffipa- 
 tion becomes infenfibk. All thefe fafts put it beyond 
 a doubt that the air is the caule, or, at lead, the occa- 
 fion of the diffipation, and carries the elettricity off with 
 it, in this manner rendering eledlrical the vihole air ot 
 a room. The problem is reduced to explain !iow the 
 air contiguous tg a fharp electrified point is elettrihed 
 and thrown off. 
 Theory cf It was deinonftrated in n" 130, that two fpheres, 
 
 union which takes place between the cleftric fluid and »l-(? 
 a correfponding ingredient of the air. In this flatc of '"^''''''7 
 cciiiliuation, almoft completely furrpunded by the air, ""''.',*'■ "* 
 the little mats of fluid niuft attradl and be attracted u,;i, Jr 
 
 connefted by an inJinilely extended, but flender con- 
 ducing canal, are in electrical equilibrium, ii their fur- 
 faces contain fluid in the proportion of their diameters. 
 In this cafe, the fuperficial deiility of the fluid and its 
 tendency to elcape are inverfely as the diameters (n" 
 130). Now if, in imagination, we gradually diminilh 
 the diameter of one of the Iphercs, tiie tendency to 
 efcape will increale in a greater proportion tlum any 
 that we can name We know, that when the prime con- 
 dudlor of a powerful table-machine has a wire of a tew 
 inches in length prujeding from its end, and termina- 
 ting in a ball of half an inch in diameter, we cannot 
 eleftrify it beyond a certain degree ; for when arrived at 
 this degree, the eleftricity flies off in fuccefTive burlls 
 from this ball. Being much more overcharged than any 
 other part cf the body, the air (urrounding the ball be- 
 comes more overcharged by communication, and is re- 
 pelled, and its place fupplied by other air, not fo much 
 overcharged, wliich furiounded the other parts of the 
 body, and is prefTed forwards into this fpace by the ge- 
 neral repuliion of the condutlor and tlie confining pref- 
 fure of the atmofphere ; otlierwife, being alio overchar- 
 ged, it woidd have no tendency to come to this place. 
 Half a turn of the cylinder is i-.fficient to accumulate 
 to a degree fufiicient for producing one of thefe explo- 
 fions, and we have two of them for every turn of the 
 cylinder, A point may be compared to an incompa- 
 rably f mailer ball. The conllipation of the fluid, and 
 its tendency to efcape, muil be greater in the fame un- 
 meafurable proportion. This denllty and mutual re- 
 pulfion cannot be diminiflied, and mull even be increa- 
 fed, by the matter of the wire forming a cone of which 
 the point is the apex ; therefore, if there were no other 
 caufe, we muft fee that it is alraofl impolTible to confine 
 a coUeftion of particles, mutually repelling, and confli- 
 jpated, as thefe are in a fine point. 
 
 But the chief caufe feems to be a certain chemical 
 
 with very great force, and more readily overcome the 
 force which keeps the eleitriticd fluid attached to tl.c 
 lafl feries of particles of the wire. It unites with the 
 air, rendering it eledtric in the highefl degree of redun- 
 dancy. It is therefore flrongly repelled by the niafs of 
 confUpated fluid which fucceeds it within the point. 
 Thus is the eleftrllied air continually thrown oft, in a 
 flate of eletliification, lliat mufl rapidly diminifli tlie 
 cleftricity of the conductor. Hence the uninterrupt- 
 ed flow, without noiie or much light, when the point is 
 made very fine. When the point is blunt, a little ac- 
 cu:'.iulation is ueceffary before it attains the degree ne- 
 cclfary for even this minute explofion ; but this is loon 
 done, and thefe little explofions fucceed each other ra- 
 pidly, accompanied by a fputtering nolle, and trains of 
 bright fparks. The noife is unduubtedly owing to the 
 atoms ot the highly electrified faiid. Thefe arc, in all 
 prubability, rarefied of a luddcn, in the atl of eleCtrifi- 
 cation, and immediately coUapfe again in the aCt of 
 chemical union, which caufcs a fonorous agitation 
 of the air. This electrified air is thus thrown oft, and 
 its place is immediately fipphed by air from behind, not 
 yet eleftrified, and therefore flrongly drawn forward to 
 the point, from which they are thrown off in their 
 turn. This rapid expanfion and fubfequent coilapfinjj 
 of the air is verified by the experiments of Mr Kinner- 
 fly, related by Dr Franklin, and is feen in numberlefs 
 experiments mnde with other views in later times, and 
 not attended to. Perhaps it is produced by the great 
 heat which accompanies, or is generated In the transfer- 
 ence of electricity ; and it is of the fame kind with what 
 oecafions the burfling of ftones, fplitting of trees, ex- 
 ploding of metals, &,c. by eleciricity. ■ The expanfion 
 is cither inconfidcrable, qr it is iiiccefiively jjroduced in 
 very fmall portions ot the fubftance expanded; tor when 
 metal is exph>ded in clofe vefl'els, or under water, there 
 is but a minute portion of gazeous matter produced; 
 and in the dillipation by a very fine point, fufficiently 
 great to give full employment to a powerful machine, 
 the flream of wind is but very faint, and nine-tenths 
 of this has been dragged along by tfie really elettiified 
 thread of wind in the middle. 
 
 From a collation of ail the appearances of eleiTtricity, 
 we muft form the fame conception of the forces which 
 operate round a point that is negatively electrified, not 
 dilperling, but drawing in eledtric fluid. It is more 
 completely undercharged than any otlier part of a body, 
 and attradts the duid in the furrounding air, and the 
 air in which if is retained, witli incomparably greater 
 force. It therefore deprives the contiguous air of its 
 tluid, and then repels it, and then produces a flream like 
 the overcharged point- 
 
 If a conducting body be brought near to any part 
 of an overcharged body, the fronting part of the firfl 
 is rendered undercharged ; and this increafes the charge 
 of the oppofite part of the overcharged body. It be- 
 comes more overcharged in that part, and fooner at- 
 tains that degree of conllipation that enables the fluid 
 to quit the fuperficial feries of particles, and to eleC^rify 
 ftrongly the contiguous air. The explofion is there- 
 fore made in this part in preference to any other ; and 
 
 the
 
 ELECT 
 
 the -i'.v tlim exploded !s ftrongly attrafted by the fioiit- 
 h'T part of the other body, and mull fly thither in prc- 
 ferc.ice to any other point. If, moreover, the fronting 
 ]) irt of A be promiiici.t or pointed, this tlFccft will be 
 produced in a iiiperior degree ; and tlw: current of 
 eleftritiw-d air, which will begin very early, will increafe 
 this difpofition to transference in tiiis w ly by rarefyinj^ 
 the air ; a changj which the whole conrfe of elcAric 
 phenomena Ihews to be highly favourable to this trans- 
 ference, although we cannot perhaps form any very 
 adequate notion how it contributes to this effeft. 
 This feems to be the reafon why a great explolion and 
 fii ip, with a copious transference of electricity, is ge- 
 nerally preceded by a hifling iioife like the rulhing of 
 wind, which Uvclls to a maximum iu the loud fnap 
 itfelf. 
 
 If two prominences, preciftly fimilar, and eleArlfied 
 in the contrary way to the fame degree, are prefentcd 
 to each other, we cannot fay from which the current 
 fliould take its commencement, or whether it fhoi'lJ 
 not equally begin from both, and a general difperfion 
 of air laterally be the efFeA ; but fiich a fituation is 
 barely poffible, and mult he infinitely rare. The cur- 
 rent will begin from the fide which has fome fuperiority 
 of propelling force. We are difpofed to think that this 
 current of material eledrified fubilancc niuft futFer great 
 change during its paffage, by mixing with the current 
 in an oppofite eledlrical flate coming from the other 
 body. Any little mafs of the one current muft ftrong- 
 ly attraft a contiguous mafs of the other, and certain 
 changes fhould furely arife from this mixture. Thtfe 
 may, in their turn, make a great change in the mecha- 
 nical motions of the air ; and, fnftead of producing a 
 quaqua vfrj'um difperfion of air from between tlie bo- 
 diep, as fhould refult from the meeting of oppofite 
 ftreams, it may even produce a co'lapfing of the air by 
 the mutual (Irong attraftions of the little maffes. Many 
 valuable experiments offer themfclves to the curious in- 
 qiirer. Two little balls may be thus prt tented to each 
 other, and a fmoke may be made with rofm to occupy 
 the interval between them. Motions may be obferved 
 which "nave certain an^.logies that would- afford iifcful 
 information to the mechanical inquirer. There mufl be 
 fomething of this mixture of currents in all fuch trans- 
 icrenccs, and the moft minute differences in the condi- 
 tion of a little parcel of the air may greatly affeiTl the 
 future motions. The moll promifing form of f'lch ex- 
 periment would be to u'e two points of the fame fub- 
 llance, fhape, and fize, and elcttrified to the fame de- 
 gree in oppofite fenfes. 
 
 After all care has Ijeen taken to infwre (imilarity, there 
 remains one eflential difference, that the one cum ii I is re- 
 dundant ill dedric Jluid, and the oilier deficient. This cir- 
 'cumilance mujl produce cUarafterillic differences of ap- 
 ])earance. And are there not fuch differences? Is not the 
 pencil and the ftar of light a charatlerilb'c difference ? 
 And does not thiswell-fupported fadl greatly corroborate 
 the opinion of Dr Franklin, that the eleilric phenomena 
 relult from the redundancy and deficiency of one fub- 
 ftance, and not from two diftintl fubllances operating in 
 a fimilar manner ■' For the diilindtiou in appearance is a 
 mechanical diftinttion. Motion, diredlion, velocity, are 
 perceivable in it. Locomotive forces are concerned in 
 it ; but they are fo implicated with forces which proba- 
 bly referable chemical af&aities, hardly operating be- 
 
 R I C I T Y. 
 
 yond contaft, that to extrtc ate t!)e!r eiTedls from the 
 complicated phenomenon feems a defperate problem. 
 There is (ome hitherto inexplicable chemical compolition 
 and decompofition taking place in the transference of 
 eledtricity. Of this a numerous train of obfervations 
 made fince the dawn of the pneumatic chemiftry leaves 
 us no room to doubt. Tlie emerfiou or production 
 ot light and heat is a remarkable figu and proof. Now 
 this takes place' alon^ the •whole path of transference ; 
 therefore the procels is by no means completed at the 
 point from which the a6tivo caufe proceeds ; and al- 
 though there be certain ajipcarances that are pretty re- 
 gular, they are ilill mixed with others of the mod ca- 
 pricious anomaly. The zigzag form of the mod ton- 
 denfed fpark, totally unlike, by its ffiarp angles, to any 
 motions producible by accelerating forces, which mo- 
 tions are, without exception, curvilineal, makes us 
 doubt exceedingly whetlier the luminous lines which we 
 obterve sre fuccefllve appearances of the fame matter in 
 different places, or whether they be not rather fimulta- 
 neous, or nearly fimultaneous, corufcations of different 
 parcels of matter in dilferent places, indicating chemical 
 compofitions taking place almoff at once ; and this be- 
 comes more probable, when we refli;£t on what has been 
 faid already of the jumbling of O'.ipofiie currents ; fuch 
 mixtures ftiould be expeftcd. We have feen a darted 
 fladi of lightning which reached (in a direction nearly 
 parallel to the horizon) above three miles from right to 
 left ; and it feemed to us to be cocxijlent ; we could not 
 fay at which end it began. The thunder began with 
 a loud crack, and continued with a moil irregular 
 rumbling noife about 15 fcconds, and feemed equal on 
 both hands. We imagine that it was really a fimulta- 
 neous fnap, in the whole extent of the fpark, but of 
 different ftrengtli in diiHreiit places ; different portions 
 of the fonorous agitation were propagated to the ear iu 
 fncceffion by the fonorous undulations of air, caufing 
 it to leem a lengthened found. 8uch would be the 
 appearance to a perfon ftanding at one end of a loiiir- 
 line of foldiers who difeharge their firelocks at one in- 
 flant. It will feeni 3 running fire, of ditTereiit ttrength 
 in dliferent parts of the line, if the mufkets have been 
 unequally loaded. It is inconceivable that this long 
 zigzag fpark can mark the track of an individual mai's 
 of tleflrified air. The vehicity and momentum would 
 be enormous, and would fweep off every thing in its 
 way, and its path could not be angular. The faire 
 muff be afferted of the itreams of light in our experi- 
 ments. The velocity is fo uumeafurable that we car.not 
 ttll its direCt'on. There may be very little local mo- 
 tion, jutt as iii the propagation of found, or of a wave 
 on the Inrtace of water. ^Fhat jiarticular change of 
 mutual fituation among the adjoining atoms which oc. 
 cafions chemical folutiou or precipitation may be pro- 
 duced iu an inltant, over a great extent, as we know 
 that a parcel of iron filings, lying at random on the 
 furface of quickfilver, will, in one inffant, be arranged 
 in a certain manner by the mere neighbourhood of a 
 magnet. Is not this like the fimultaneous precipitation 
 of water along the whole path of a difeharge ? 
 
 But ilill there muft be fome caufe which gives thefe 
 fimultaneous corufcations a fituation with refpeft to 
 each other, that has a certain regularity. Now the lu- 
 minous trains (for they are not imiform lines of light) 
 of almoft continuous fgarko which are arranged between 
 
 607
 
 €o8 
 
 ELECTRICITY. 
 
 a pofitive and a negative point, fcem to us to indicate 
 emanation from the politive, and reception by the ne- 
 gative ])oint. The general h'ne lias a confiderable re- 
 femblance to the path of a body projefted from the po- 
 litive point, repelled by it, and attra6tcd by the nega- 
 tive point. This will appear to the mechanician on a 
 very little refleftion. It the curve were completely vi- 
 liblc, it would foniewhat refenible thoie drawn between 
 1' and N in tig. 35. PABN overpafTcs the point N, 
 and comes to it from behind; Fab N lies within the 
 other, and arrives in a direftion nearly perpendicular to 
 the axis ; P " 15N defcribes a flraight line, and arrives 
 in the direftion PN. As the chemical compofition ad- 
 vances, the light 13 difengaged or produced, and there- 
 fore the appearances are more rare as we advance far- 
 ther in the direftion in which they are produced ; and 
 tltere would perhaps be no appearance at all at the 
 point where the motion ends, were it not that the few 
 remaining parcels, where the compofitions or decompo- 
 fitions have not been completed, are crowded together 
 at the negative point, incomparably more than in any 
 other part of the track. We think that thefe confide- 
 rations offer fome explanation of tlie appearance of the 
 pencil and liar, which are fo uniformly charafterilfic of 
 the pofitive and negative eleftricities ; but we fee many 
 grounds of uscertainty and doubt, and offer it with 
 ,Q due diffidence, 
 lichten- The curious figures obferved by Mr Lichtenberg, 
 
 berg's c'.cc- formed by the dull which fettles on a line drawn on 
 '*''i? "'■'''■'Bthe face of a mirror by the pofitive and by the nega- 
 tindive " '^"^ knobs of a charged jar, are alfo uniformly charac- 
 marks of terillic of the two eleftricities. Thefe are mechanical 
 ■4- and — diftinftions, indicating certain differences of accelerating 
 forces. We muil refer the curious reader to Lichten- 
 berg's Diflertations in the Gottingen Commentaries ; to 
 the Publication of the Haarlem Society ; to the Gotha 
 Magazine ; to Dijfertations by Spath at AltdorfF, and 
 other German writers. 
 CifTipation It only remains for us to take notice of the general 
 cf elcdrici-laws of the difllpation of eleftricity into the air, and 
 -ty into the a]o„g imperfeft infulators. On this fubjeft we have 
 air IS \M- f valuable experiments of Mr Coulomb, publifhcd 
 
 ■porrionalfo. ,_- . ri a 1 r.^- ro- 
 
 tlipdenfity. in tl>e Memoirs of the Academy ot Sciences ot i'aris 
 
 for 1785. 
 
 Thefe experiments were made with the alTillance of 
 an elcftrometer of a particular conftruftion, which fliall 
 "be defcribed under the article Electrometer. 
 
 The general refult of Mr Coulomb's experiments 
 was, that the momentary difllpation of moderate degrees 
 of eleftricity is proportional to the degree of eleftri- 
 city at the moment. He found that the diffipation 
 is not fenfibly affefted by the Hate of the barometer 
 or thermometer ; nor is there any fenfible difference 
 in bodies of different fizes or different fubftances, or 
 even different figures, provided that the eleftricity is 
 very weak. 
 Sii. But he found the diffipation greatly affefted by the 
 different ftates of humidity of the air. Sauffure's hy- 
 grometer has its fcale dlilinftly related to the quantity 
 of water diffolved in a cubic foot of the air. The fol- 
 lowing little Table fhews an evident relation to this in 
 the diffipation of eleftricity ; 
 
 Hygrometer. Grains wnter in DlftipafioB pM 
 
 cubic foot. minute. 
 
 69 6,197 .... ^v 
 
 75 7.29J . • . . 3T 
 
 83 8,0+{ . . . . I'y 
 
 S7 . . . . . 9,221 . . _. . t'i 
 
 Hence it follows, that the diffipation is very ne:irly in 
 the triplicate ratio of the moiilure of the air. Thus if 
 
 *° be confidered as r: -~~ we have m =z 2,764 
 
 6,iHo 
 
 60 
 
 _ ».o4; 
 
 6, 1 80 
 
 _ 9,220 
 
 gives 
 
 gives 
 
 m = 2,76 
 m =: 3,61 
 
 6,i8c 
 Hence, at a medium, m = 3,40. 
 
 We (honld have obferved, that the ingenious author 
 took care to feparate this diffipation by immediate con- 
 taft with the air, from what was occafioned by the im- 
 perfeft infulation afforded by the fupports. ,,, 
 
 It muil alfo be remarked here, that the immediate Diminution 
 objeft of obfervation in the experiments is the diminu-of re['ulfion 
 tion of repulfion. This is found to be, in any given'' ''""''!^ °' 
 itate ot tlie air, a certain proportion or the whole re-^j^jj^ 
 pulfion at the moment of diminution: but this is double 
 of the proportion of the denf.ty of the eleftric fluid s 
 for it mufl be recollefted, that the rcpulfions by which 
 we judge of the diffipation are mutual, exerted by every 
 particle of fluid in the ball / of Coulomb's elcftrometer, 
 on every particle in the ball a. It is therefore propor- 
 tional to the eleftric denfitv of each; and therefore, du- 
 ring the whole diffipation, the denfities retain their pri- 
 mitive proportion ; therefore, the diminution of the re- 
 pulfion being as the diminution of the produfts of the 
 denfities, it is as the diminution of the fquares of either. 
 If therefore the denfity be reprefented by '/, the mutual 
 repulfion is reprefentable by </', and its momentary di- 
 minution by the fluxion of ^' ; that is, by 2 J J, or 2d 
 Xd. Now ZflfXi/ is to d' as 2d is to d'; and there- 
 fore the diminution of repulfion obferved in our experi- 
 ment bears to the whole repulfion twice as great a pro- 
 portion as the diminution of denfity, or the quantity of 
 fluid diffipated bears to the whole quantity at the mo- 
 ment. For example, if we obfervc the repulfion dimi- 
 nlflied -j'q, we conclude that -^'5 of the fluid has efcaped. 
 Mr Coulomb has not examined the proportion be- 
 tween the diffipatlons from bodies of different fizes. A 
 great and a fmall fphere, communicating by a very long 
 canal, have fuperficial denfities, and tendencies to efcape, 
 inverftly proportional to the diameters. A body of 
 twice the diameter has four times the furface ; and tho' 
 the tendency to efcape be twice as fmali, the furface is 
 four times as great. Perhaps the greater lurface may 
 compenfate for the fmaller denfity, and the quantity of 
 fluid aftually gone off may be greater in a large fphere. 
 This may be made the fubjeft of trial. 
 
 It mufl be kept in mind, that the law of diffipation p.ifipatjon 
 afcertained by thefe experiments, relates to one given depcntiso" 
 flate of the air, and that it does not follow that int'-e C»'« " 
 another ftate, containing perhaps the fame quantity of ^ ' 
 vrater, the diffipation ftiall be tii« fame. The air is fuch 
 
 a hete- 
 
 ii4. 
 
 ite;
 
 117 
 Theory 
 thereof. 
 
 a heterojTfneous and variable compouii'l, that it ni.iy 
 have very ditfeieiu affinities vvilli tlic cleiiiit fluid. Mr 
 Couhimb thoiiij;ht that he iliould infer from his mmie- 
 rolls experiments, tiiiit the diffipation did not iiicreafc in 
 the ratio of tlie cube of the water diflTolved in the air, 
 linlefs it was n>;arlv as much as it could difTolve in that 
 temperature This indeed is coiiforni.dile to general 
 ohfervation : for air is tliought dry when it dries quick- 
 ly anv thinor expnfed to it ; that is, when not nearly fa- 
 turatcd with moilture. Now it is well known, that what 
 is thougiit dry air is favourable to electricity. 
 
 The difilpation along imperfett infulators is brought 
 about in a way fomewluu different from the manner of 
 its efcaping by tleArifying the contiguous air and go- 
 ing off with ir. It fetms to be chiefly, if not folely, 
 along the furtVcc of the i;i.fulating fupport that the elec- 
 tricity is difliifed, and that the difl'ufion .is produced 
 there chiefly by the moillure which adheres to il. It 
 is not very eafy to foi m a clear notion of tlie manner, 
 but Mr Coulomb's explanation feems as fatisfaftory as 
 any we have ften. 
 
 Water adheres to all bodies, (licking to their fur- 
 faces. This adhtlloa prevents it from going off when 
 tleitrilied ; and it is therefoie fufceptible of a liigher 
 degree of eledirification. If we fupnofe that tlje particles 
 of moifture are unitorn^ly difpofed .ilong the furiace, 
 leaving fpaces between them, the eleftricity commuiiica- 
 ted to one particle mull attain a certain denfity befoie it 
 can fly acrofs the infnlaling interval to the next. There- 
 fore, when fuch an imperfeft condudlor is eledlrified at 
 one end, the eleitrjclty, in paffing to the other, will be 
 Avcakencdat every (tep. If wetake three adjacent particles 
 a, li, c, of this condiifting matter, we learn, from ii° 105, 
 that the motir.:i of i is fenfibly affefted only by the dif- 
 ference of a and i ; and therefore that t!\e pafTage of elec- 
 tricity from ^ to f requires that this diflerence be (upenor 
 or equal to the force necefTary for clearmg this coercive 
 interval. I.,et a j>avticle pafs over? Tlie eleflric den- 
 fity of the particle bof condu6ling matter is diminilhed, 
 while the denfity of the particle on the other fide of a re- 
 mains as before. Therefore fome will pafs from a to /',and 
 from the particle preceding atoa; and fo on, till we come 
 to the elcclrilied end of this imperfcdt infulator. It is 
 plain from this confideration, that we mull arrive at laft 
 at a particle beyond c, where the whole repuUlou of the 
 preceding ])article is jull fufficient to clear this interval. 
 Some will come over, whofe repulfion, now atling iu the 
 oppofite diredlion, will hinder any fluid from fupplying 
 its place iu the jinrlicle which it has quitted. Here the 
 transference will flop, and beyond this the infulation is 
 complete. There is therefore a mathematical relation 
 between the infulating power and the length of the ca- 
 nal, which may be afcertained by our theory ; and thus 
 another opportunity obtained for comparing it with ob- 
 fervation. That this inveftigation may be as timple as 
 .poffible, we may take a very probable cafe, namely, 
 where the infulating, or, to name it more graphically, 
 the coercive, interval is equal in every part of the canal. 
 
 Let R be the coercive power of the infulator ; that 
 13, let li be the force necefTary for clearing the coercive 
 interval. Let a ball C (lig. 36.) be fufpended by a fdk 
 thread AB, and Itt C reprefent the quantity of its re- 
 dundant fluid ; and let the denfity in the different points 
 of the canal be as the ordinates AD, P d, &c. of fome 
 curve line D </ B, which cuts the axis in D where the 
 
 SurPL. Vol. I. Part II. 
 
 ELECTRICITY. 
 
 thread begins to infulite corr.pletcly. Let P/> be an 
 clement ot the axis. Draw the ordinate ff, the tan- 
 gent d/F, and the normal f/E, and _/"<■ prpcndicubr 
 to P d. Let AC be = r, AP = x, P </ = y. 'Iheu 
 Pp =: X, and de = — y. We liave feen tlial the 
 only fenfible acftiou on the particle of fluid in P is — 
 
 (JO9 
 
 '-i (fee n 105), when the adtion of the redundant fluid 
 
 Therefore we have -^^i ::: 
 .ipo. 
 
 fui 
 
 in tile globe on the particle P, having the denfity j, is 
 rcp.-efeiited by 12 
 
 {r + .y 
 
 R, the coercive power of the thread. This is 
 
 fed to be cunftant. Therefore r, is equal to 
 
 I/. ^ , 
 
 fome conilant line R. But F/>, or fe id e =. I'd: PE. 
 
 Tliereiore the lubnormal PE is a conilant line. But 
 
 tliis is the property of the parabola alone; and the curve 
 
 of denfity D (/ B is a parabola, of wliich the parameter 
 
 is 2 PE, or 2 R. jis 
 
 Cor. 1. The denfitles in diiTerent points of an im- Vavlatioii 
 
 perfttl infulator are as the fquare roots of their diftance ''^ (''enfi'? 
 
 from the point of complete iiil'iilation : For PJ' : AD" j", " ' 
 
 = BP : BA. ;,9 
 
 2. The length of canal required for infulating dif- Length ne- 
 
 ferent deufiiies of tlcclricitv are as tlie fquares of the'^^''">'.f<"' 
 A-i-Cx mUilation 
 
 denfities. For AB = -p^ ; and PE has been fiiewn =i J'="''iy '• 
 
 to be a conilant quantity. Indeed we fee in the de- 
 monllration, that BP would infulate a ball, whofe elec- 
 tric denfity is P d, and BA : BP = AD- : P d ^. no 
 
 3. The length neceffary tir infulation is inverfcly asAlfo -^ 
 the coercive force of the canal, and may be reprefented__i___ 
 
 D' ^ ^ „ . DA' D' foercon. 
 
 generally by -g-. For AB is = -p|j. = — -. 
 
 Mr Coulomb has verified thefe conclufiors by a very 
 fatisfadlory feries of experiments, by the afTiiiance of 
 his delicate ek Urometer, which is admirablv fuited for 
 this trial. The fubjeft is fo intertih'ng to every zea- 
 lous lludeiit of electricity, that Mr Canton, Dr B.VVi!- 
 fon, Mr Waitz, Wilcke, and others, have made exjieii- 
 ments for efl:ililifiiing fome meafure of the conducting 
 powers of diifei-ent lublinnces. It was one of the liilt 
 things that made the writer of this article fuppofe that 
 electric aClioii was iu the inverfe duplicate ratio of the 
 diflances : for, as early as 1763, lie had found tliat 
 the lengths of capillary tubes nectflary for infulatiou 
 were as the fquares of the rcpulfions of the ball which 
 they infulated. I'he moite of reafoning offers of itfelf, 
 and the flu.xionary expreflion of the infulating power, 
 
 t/s. — led immediately to a force proportional to 
 
 X «'• 
 
 Numerous experiments were made, which we do not 
 give here, becaufe the public are already pufTcfTed of 
 thofe of Mr Coulomb. 
 
 This difcuffion explains, in a fatisfadlory manner, the KxpUna- 
 operation of the condenfer, as defcribed by Mr Voha. 'i"" "f the 
 The weak degrees of cledlricity, which are rendered^'""' 
 fufiiciently fenfible by the infulation of the plate "f <i«'y j/J,/>r 
 marble, are completely infulated by the perhaps thin 
 ftratum that has been fufficicntly dried, while the reft 
 condudls with an efficacy fufficient for permitting the 
 accumulation. 
 
 4H When
 
 6io 
 
 ELECT 
 
 »tl. Vfliea we refleft on tlie theory now delivered, we 
 fie that the formuli determine the diitribution of the 
 Huid along an itnpeifeft coiiduftor in a certain manner, 
 tin the fuppofition that a ctrta'ni determinate doie has 
 been imparted to the b?ll : Bccaufe this dofe, by dif- 
 fuling iiftlf from particle to panicle of the condiidting 
 matter,- will dilfufe i felt all the way to B, in fiich a 
 manner that the repulficn (hall everywhere be in cquili- 
 brif. with the rnaxlmum of the coercive force of th'c iii- 
 lulatiiig iiitt! val. But it muft he farther noticed, that 
 this rcfiflance is not n3ive, but coercitive, and we may 
 compare it to fiiftion or vifcidity. Any repiilfinn of 
 ekftric fluid, which falls (hort of this, will not diftnrb 
 the liability of the fluid fprcad along the canal, accord- 
 ing to any law whatever. So that if AD reprefent 
 the electric denfity of the globe, and remain conftant, 
 
 any curve of denfity will anfwer, if — be everywhere 
 
 X 
 
 lefs than R. It is therefore an indeterminate problem to 
 aflign, in general, the difpofition of fluid in the canal. 
 The denfity is as the ovdinates of a parabola only on 
 the fuppuhtion that the maximum of R is everywhere 
 the fame. And, in this cafe, the diilances AB is a 
 jninimum : for, in other caies of denfity, we muft have 
 
 -;- lefs than R. If, therefore, we vary a fingle ele- 
 
 X 
 
 ment of the curve T) dB, in order that the {lability of 
 the fluid may not be difturbed, having d conftant, we 
 
 muft ncceflarily have x larger, that -^ may ftill be lefs 
 
 than R ; that Is, we muft lengthen the axis. 
 
 We fee alfo, that to afcertain the diftribution in a 
 
 conducing canal is a determinate problem ; whereas, in 
 
 imperfett coiuluiflors, it is indeterminate, but limited 
 
 by the ftate of the fluid, when it is fo difpofed that in 
 
 every point the aftion of the fluid is in equilibrio with 
 
 the maximum of refiftance. This confideration will be 
 
 «a applied to a valuable purpofe in the article Magnetism. 
 
 Explana- This doftrine gives, in our opinion, a very fatisfac- 
 
 tionofa (-Qry explanation of the curious obfervations of Mr 
 
 curious ardg,^ and Mr Cuthhertfon, mentioned in n'^ 167. 
 
 important . , • rj r . j ■ J- • 
 
 fail; aid namely, that damping the inlide 01 a coated jar oimi. 
 
 method of nifties the riflt of explofion, and enables it to hold a 
 increafing ),Jglier charge. We learn here, that there is no den- 
 a charge, g^^ ^^ great but that the leaft impcrfeft conduftor 
 ■will infulate it, if long enough ; and that the coercive 
 quahty of an imperfeS coiiduflor may be conceived fo 
 conftituted from A towards B, that the denfities ftiall 
 diminifti in any ratio that we pleafe, fo that the varia- 
 tion of denfity (the caufe of motion) may everywhere, 
 even to the infulating point B, be very fniall. How- 
 ever great the conftipation at the edge of the metallic 
 coating may he, an imperftft conductor may be conti- 
 nued outward from that edge, and may be fo conftitu- 
 ted, that the conftipation ftiall diminifti by fuch gentle 
 gradations, that an explofion ftiall be impofiible. An 
 uniform dampnefs will not do this, but it will dimi- 
 nifti the abruptnefs of the variation of denfity. The 
 ftate of denfity beyond the edge of the coating of a 
 charged jar, very clean and dry, may be reprefented by 
 the pa-abolic arch T)ia. This may be changed by 
 damping, or properly dirtying (to ufe Mr Brookes's 
 fbafe}, to P/B ; which is evidently preferable. We 
 
 R 1 C I T Y. 
 
 think it by no means difiicult to contrive fuch a contf- 
 nuatiou of impcrfeftly conducing coating. Thus, if 
 gold leaf can be ground to an impalpable powder, it 
 may be mixed with an oil varnilh in various proportions. 
 Zones of this gold varnifti may be drawn parallel to the 
 edge of the coating, decreafing in metal as they recede 
 from the edge. By fuch contrivances it may be pof- 
 fible to increafe the retentive power to a great degree. 
 
 This Joftrine farther teaches us, that many precau- Cautions in 
 tions muft be taicen when we are making experiments deducing 
 from which meafures are to be deduced ; and it points ™'^^'^"'''5 
 them out to the mathematician. In particular, when .°'" ^''f'^* 
 bodies, fupported by infulators, are eleftrified to a high 
 degree, the lupports may receive a quantity of fluid, 
 which may greatly difturb the refulta ; and this quan- 
 tity, by exerting but a weak a£lion on the parts of 
 the canal, may continue for a very long time, and not 
 be removed but with great difliiculty. In fuch cafes, 
 it will be neceflary to ufe new fupports in every expe- 
 riment. Not knowing, or not attending to this cir- 
 cumftance, many erroneous opinions have been formed 
 in fome delicate departments of eledlrical refearch. 
 
 Mr Coulomb's experiments on this fubjeft are chiefly 
 valuable for having Itated the relation between the in- 
 tcnftty of the eleftricity, or, as he expreftcs it, the elec- 
 tric denfity, and the lengths of fupport neceffary for 
 the complete infulation. But, as the abfolute intenfities 
 have all been meafured by his eleftiometer, and he has 
 not given its particular fcale, we cannot make much 
 ufe of them till this be done by fome cleclrician. 
 
 Mr Coulomb found that a thread of gum lac was Infulating 
 the moft perfeft of all infulators, and is not lefs than powers of 
 ten times better than a ftlk thread as dry as it can be r YA""^ 
 made, if we meafure its excellence by its Ihortnefs. In 
 a confiderable number of experiments, he found that a 
 thread of gum lac, of 1,5 inches long, infulated as well 
 as a fine filk thread of 15 inches. When the thread 
 of filk was dipped in fine fealing-wax, it was equal to the 
 pure lac, if fix inches long, or four times its length. If 
 we meafure their excellence by the intenfities with which 
 they infulate, lac is three times better than the dry thread, 
 and twice as good as the thread dipped in fealing-wax ^ 
 fo that a fibre of filk, even when included in the lac, 
 diminiflies its infulating power. We alfo learn that the 
 diftipation along thefe fubftanees is not entirely owing 
 to moifture condenftd or adherent on their furfaces, but 
 to a fmall degree of conducing power. We have re- 
 peated many of thefe experiments, and find that the 
 conducing power of filk thread depends greatly on its 
 colour. When of a brilliant white, or if black, its con- 
 ducing power feems to be the greateft, and a high 
 golden yellow, or a nut brown, feemed to be (he bcft 
 infulators ; doubtkfs the dyeing drug is as much con- 
 cerned as the fibre. 
 
 Glafs, even in its dryeft ftate, and in fituations where 
 moiftuie could ^' .e no accefs to it, viz. in veftels cqn- 
 taining cauftic alkali dried by red heat, or holding 
 frefti made quicklime, appeared in our experiments to 
 be confiderably better than filk ; and where drawn in- 
 to a flender thread, and covered with gum lac (melted), 
 infulated when three times the length of a thread of lac j 
 but we found at the fame time, that extreme finenefs 
 was neceffary, and that it difiipated in proportion to 
 the fquare of its diameter. It was remaikably hurt by 
 having a bore, however fine, unlefs the bore could alfa 
 
 be
 
 ELECT 
 
 he onated witK he. Human hair, when completely 
 fr^ed from every thing that water could wafli out of it, 
 Rnd then dried by lime, and coated with lac, was equal 
 to filk. Fir, and cedar, and larch, and the rofe-trec, 
 when fplit into filaments, and firft dried by lime, and 
 afterwards baked in an oven which juil made paper be- 
 come faintly brown, feemcd hardly infciior to gum lac. 
 
 The 'zvl'ilf woods, as they are called, and mahogany, 
 ■were mucli inferior. Fir baked, and coated with melt- 
 ed lac, feems therefore the btft fupport when ftrength 
 h required. The lac may be rendered lels brittle by a 
 minute portion of jjure turpentine, which has been 
 cleared of water by a little boiling, without feufbly in- 
 creafing its conducing power. Lac, or feaiing wax, 
 diflblved in fpirits, is far inferior to its liquid (late by 
 heat. 
 
 Thefe obfervations may be of ufe foi- the conftruc- 
 tion of ele(ftrical machines of other eledtrics than glafs. 
 
 General re. We have now given a comparifon of the hypothefis 
 flecflions. of Mr .£pinus with the chief faAs obferved in elec- 
 tricity, diverfified by every circumltance that feemed 
 likely to influence the refult, or which is of importance 
 to be known. We truil that the reader will agree 
 with us in faying that the agreement is as complete as 
 can be expetled in a theory of this kind; and that the 
 application not only feems to explain the phenomena, 
 but is praftically ufeful for directing us to the proce- 
 dures which are likely to produce the effedl we wifh. 
 Thus, (hould our phyfiological opinions fugged that co- 
 pious transference of fluid is proper, our hypothefis 
 points out the moft effeftual and the moft convenient 
 methods for producing it. We learn how to conftipate 
 the fluid in a quiefcent ftate, or how to abftraft as 
 much of it as poflible from any part of a patient ; we 
 can do this even in the internal parts of the body. We 
 had once an opportunity of feeing what we thought 
 the cure of a paralyfis of the gullet. Eledlricity was 
 tried, firft in the way of fparks, and then fmall ihocks 
 taken acrofs the trachea. Thefe could not be tolerated 
 by the patient. The furgeon wifl^ed to give a (hock 
 to the oefophagus without afl^edling the trachea. We 
 recommended a leaden piftol bullet at the end of a 
 ftrong wire, the whole dipped in melted feaiing wax. 
 This was introduced a little way, we think not more 
 than three inches, into the gullet, which the paify per- 
 mitted. A very flight charge was given to it In a few 
 feconds ; and the firil fhock produced a convulfion in 
 the mufcle, and the fecond removed the diforder com- 
 pletely. Here the ball formed the inner, and the gul- 
 let the outer, coating of the Leyden phial. 
 The theory Notwithftanding the flattering teilimony given by 
 
 ? ,P"'"^ the great conformity of this doftrine with the pheno- 
 ls only a ^ n -n i / r ■ 1 1 ■ 1 r 
 
 hypothtfis ''^*"'>> "'f "'" cnooie to preient it under the title ot a 
 hypothefis. We have never fcen the eleiflric fluid in a 
 feparate ftate ; nor have we been able to fay in what 
 cafes it abounds, or when it is deficient. After what 
 we have feen in the late experiments of that philanthro- 
 pic philofopher Count Rumford on the produdion of 
 heat by frid^ion, we think that we cannot be too cau- 
 tious on what grounds we admit invifible agents to per- 
 form the operations of Nature. We think that all muft 
 acknowledge that thofe experiments tend very much 
 
 11 1 C I T Y. 6ii 
 
 to ftaggcr our belief in tlie e-<'ll;.iee of a fluid y;y/\ff«#- 
 ris, a fire, heat, caloric, or wliat we pleafe to call it ; 
 and all will acknowledge, that no better proofs can be 
 urged for the exiftence of an elcAiIc fluid. jj, 
 
 y\rcordingIy, many acute and ingenious peifons have The rtality 
 rejefled the notion of the exifli^nce of an tleftric fluid, ol/>" <:1''C; 
 and have attempted to Ihew that the phenomena pro-V"^. j " 
 cecd, not from the prefence of a pcculiar_/i//'//«(;ff, but 
 from peculiar modes ; as we know that found, and fome 
 concomitant motions and other mechanical appiarances, 
 are the refults of the elaftic undulitions of air ; and as 
 Lord Bacon and others have explained the effcfts of 
 fire by elaftic undulations of the integrant particles of 
 tangible matter. 
 
 We have feen nothing, however, of this kind that Reqnifiiei 
 appears to give any explanation of the motl'ins, pref-*^"''' J"'' 
 fares, and other mechanical appearances of elciStricity, '^''' 
 We peremptorily require, that every do61riiie which 
 claims the name of an explanation, ftiall be perfeftly 
 confident with the acknowledged laws of mechanifm ; 
 and that the explanation fliall confift in pointing out thofe 
 mechanical laws of wliicli the fafts in iledtricity are 
 particular inftances. It is no difficult matter to pre- 
 fent an intricate or complex phenomenon to our view. 
 In fuch a form that it fliall have fome refcmblance to 
 fome other complex ph\ fical faft, more familiar, per- 
 haps, but not better underltood. The fpicious appear- 
 ance of fimilarity, and the more familiar acquaintance 
 with the other phenomenon, difpofe us to cmilidcr the 
 comparifon as a fort of explanation, or, aflcall, an il- 
 luiliation, and to have a fort of indolent acquiefcencc 
 in it as a theory. 
 
 But this will not do in the prefent queftlon : For we 
 have here felefted a particular circumftance, the obferved 
 motions occafioned by eleftricity, and called otlraRiant 
 and repulfioiis — a circumftance which admits of the molt 
 accurate examination and compari!"on with any exjJa- 
 nation that is attempted. In fuch a cafe, a vague pic- 
 ture would fpeedily vanifli into air, and prove to be 
 nothing but figurative expreffions. lafi 
 
 Many phllofophers, and among them fome refpeft- N" a>ivan« 
 able mathematicians, have fupported the dodtrine of '''>-'^"'''^'"* 
 Du Fay, Symmer, Cigna, &lc. who employ two fluids j.jpotheiis 
 as agents in all eleftrical operations. It muil be grant- of two 
 ed that there are fome appearances, where the explana-fl""^-' 
 tion by nicans of two fluids feeins, at firft fight, more 
 palpable and eafier conceived. But whenever we at- 
 tempt to obtain wcafitres, and to fay what will be the 
 preciie kind and degree of the aClion, we find ourfclves 
 obliged to afiign to the particles of thofe fluids aflua- 
 ting mechanical forces precifely equivalent to thofe af- 
 figned by ./Eplnns to his fingle fluid. Then we have 
 to add fome myfterious unexplained conneftions, both 
 with each other and with the other particles of tangible 
 matter. If we except Mr Prcvoft, in his EJpii fur les 
 Forces Magneliqucs et EieSriques, we do not recollect 
 an author who has ventured to fubjeft his fyftem to 
 ftridl examination, by pointing out to us the laws of 
 aflion according to which he conceives the particles 
 influence each other. We fliall have a proper oppor- 
 tunity, in the article MAGNErisM, to give this au- 
 thor's theory the attention it really merits. We ven- 
 ture to fay, that all the chemical theories of eledricity 
 labour under thefe Inconvc lienccs, and have iicqtiiied 
 their influence merely from the inattention of their par- 
 4 H 2 tifan*
 
 6l2 
 
 ELECTRICITY. 
 
 tifnns to tlie laws of niedianical motion, and require, in 
 order to reconcile th^'m with thcfe laws, the adoption 
 of powers fintiilar to iEpiniis's attractions and repul- 
 fioMs. Slight refeniblances to phenomena, which iland 
 equally in need of explanation, have contented the par- 
 tilans of fuch theories, and h^nrative language and me- 
 taphorical conceptions have taken place of precife dif- 
 221 cuffion. It would be endlefs to examine thetn all. 
 Hypothcfis The mod fpecious of any that we know was pub- 
 tit Proft.irorjjj.jy ^^j,j jj, ji^g univevfity of Edinburgh by the late 
 *■ ■ Mr James RulTel, ProfefTor of natural philofophy; a pcr- 
 fon of the moft acute difcernment, and an excellent rea- 
 foner. It was delivered to his pupils, not as a thcnry, 
 but as a conjeSiire, founded on Lord Karnes's theory 
 of fpontaneous evaporation, which had obtained a very 
 general reception ; a conjefture, faid the Proteffor, 
 founded on fuch refemblances as made a fimilarity of 
 operation very probable, and was an incitement and di- 
 rcflion to the pbilofopher to a proper train of experi- 
 mental difcuffion. We fay this on the authority of his 
 pupils in the years 1767, 1768, and 1769, and of forae 
 notes in his own hand-Vvriting now in our poffeffion. 
 
 Mr Ruffel confidered the eleftrical phenomena as the 
 refults of the aftion of a fubftance which may be called 
 the ekSrkal Jluhl, which is connefted with bodies by 
 attractrve and repulfive forces afting at a dillance, and 
 diniinifhing as the diilanre increafes. 
 
 Mr Rufiel fpeaks of the eleflrio fluid as a compound 
 of feveral others; and, particularly, as containing ele- 
 mentary fire, and deriving from it a great elafticity, or 
 mutual repuliion of its particles. This, however, is 
 different from the elallicity or mutual repulfion of the 
 particles of air, becaufe it afts ;it a diftance ; whereas 
 the particles of air aft only on the adjoining panicles. 
 By this conftitution, bodies containing mure eleftric 
 fluid than the fpaces around them repel each other. 
 
 The particles of this eleftric fluid attraft the particles 
 of other bodies with a force which diminifhes by diflance. 
 
 The charafteriftic ingredient of this fluid is blectri- 
 Ciir properly fo called. This is united with the elaflic 
 fluid by chemical affinity, which Mr Ruffel calls eleflive 
 attraSion, a term introduced into chemiilry by Dr Cullen 
 and Dr Black. This extends to alldillances, but not pre- 
 cifely by the fame law as the mutual repuUion of the par- 
 ticles of the other fluid, and in general, it repreffes the 
 repulfions of that fluid while in this Hate of compoiitron. 
 This eleClricity, moreover, attrafts the particles of other 
 bodies, but with certain eleftions. Noneleftric or con- 
 dufting bodies are attrafted by it at all diftances, but 
 eleftrics aft on it only at very fmall and infenfible dif- 
 tances. At fuch diftances its particles alfo attraft each 
 other. 
 
 By this conftitution, the compound eleftric fluid 
 repels its own particles at all confiderable diftances, but 
 attrafts at very fmall diftances. It attrafts condufting 
 bodies at all diftances, but non-conduftors only at very 
 fmall diftances. The phenomena uf light and beat are 
 confidered as marks of partial decoi.ipofition, and as 
 proofs of the prefence of elementary tire in the com- 
 pound : the fmell peculiar to elcftricity, and the eifeft 
 on the organ of talle, are proofs of decompolition and 
 of the complex nature of the fluid. 
 
 Bodies (couduftors) containing eleftric -fluid, repel 
 each other at confiderable diftances, but, if forced very 
 iiear, attraft each other. Eleftrics can contain it only 
 
 in confequence of the eledrldty in the compound. Part 
 of this eleftricity muft be attached to the furface in a 
 non-claflic ftate ; becaufe when it is brought fo near as 
 to be attrafted, its particles are within the iphercs of 
 each other's aftion, and this redoubled attraftion over, 
 comes the repulfion occafioned by its union with tlie 
 other ingredient ; and the eleftric fluid is partly de- 
 compofed, and the if/if<2nViV)i, properly fo called, adheres 
 to the furface of the eleftric, as the •water of damp air 
 adheres to a cold pane of gliifs in our ivindotus. Alfo, 
 by this conftitution, eleftric fluid may appear in two 
 flates ; ehftic, like air, when entire; and unelaltic, like 
 water, when partly decompofed by the attiaction of 
 eleftrics. 
 
 Electricity may be forced into this unelaftic union by 
 various means ; by friftion, which forces the eleftric 
 fluid contained in the air into clofe contaft, and thus 
 occafions this decompofition of the fluid and the union of 
 its f/fSWi'/'/y with the furface. This -operation is com- 
 pared by Mr Ruffel to the forcible wetting of fome 
 powders, (uch as lycoperdon, which cannot be wetted 
 without fome difficulty and niechanical comprefllon ; 
 after which it adheres to v .cer flrongly. It may be 
 thus united in fome natural operations, as is obferved 
 in the melting and freezing of fome fubftances in con- 
 taft with eleftrics ; and it may be thus forced into 
 union by means of metallic coatings, into which the 
 eleftric fluid is forced by an artful employment of its 
 mutual repulfions. This operation is compared to the 
 condcnfation of the moifture of damp air by a cold pane 
 of the window; and the evacuation of the other lide of 
 the coated pane is compared to the evaporation of the 
 moifture from the other iide of the window, pane iu 
 confequence of the heat which muft emerge from the 
 condenfed vapour. We find in the Pi'ofeffor's notes 
 above-mentioned many fuch partial analogies, employed 
 to fhew the ftudents that fuch things are feen in the ope- 
 rations of Nature, and th'at his conjefture merits at- 
 tention. 
 
 The intelligent reader will fee that the general re- 
 fults of this conftitution of the eleftric fluid will tally 
 pretty well with the ordinary eleftrical phenomena ; 
 and, accordingly, this conjeclure was received with great 
 fatisfaftiou. ■ We remember the being much plcafed 
 with it, as we heard it applied by Mr RutTel's pupils, 
 many of whom will recolleft what is here put on re- 
 cord. But the attei,tive reader will alio fee, that all 
 this intricate combination of different kinds of attrac- 
 tion and repulfion is nothing but mere accommodations, 
 of hypothetical forces to the phenomena. How in- 
 comparably more beautiful is the Jimple hypothefis of 
 jEpinus, which, without any fuch accommodations 
 tallies fo precifrly with all the phenomena that have yet 
 been obferved ? Here no dillinftion of aftion is necel- 
 fary, and all the varieties are confequences of a circum- 
 rtaiice perfeftly agreeable to general laws; namely, that 
 the internal ftrufture of fome fubftances may be fuch as 
 obftrufts the motion of the eleftric fluid through the 
 pores — Nothing is more likely. 
 
 Several years after the death of the Scotch Pro-j, , -, 
 fellor in 1 773, a theory very much refembling this^f j^Xr ili 
 acquired great authority, being propolcd to the phi-l,uc. 
 lofophers by the celebrated naturalift Mr de Luc. This 
 gentleman having long cultivated the lludy of me- 
 teorology with unwearied aifiduity and great fuccefs, 
 
 and 
 
 4i8
 
 ELECT 
 
 ajid having been fo familiar!)- corverfaiit with cxpaiifne 
 fluids, and the affinities of their compounds, was dilpo- 
 ied to U-e their operations in almoft all the changes on 
 the furface of this globe. Eledricity was too biify 
 an after in onr atmofphere to efcape his paiticular no- 
 tice. While the mechanical pUilofophers endeavoured 
 to explain its effeAs by accelerating forces attrafting 
 and riptliing, Mr de Luc endeavoured to explain them 
 by means of the expanlive properties of aeriform fluids 
 and gafes, and by their chemical affinities, compolitions, 
 and Jecompolitions. He had formed to hiniicU a pe- 
 culiar opinion concerning the contlitution of our atmo- 
 fphere, and had explained the condcnfatioa of moifture, 
 whether of (leani or of damp aeriform fluids, in a way 
 riuch more refined than the liiiiple theory of Dr 
 Hooke, viz. folation in air. He confidtrs the com- 
 pound of air and fire as the carrier of the water held in 
 foiution in damp air, aod the fire as the general carrier 
 of both the air and the moiilure. 'E.venjire is confider- 
 cd by him as a "vapour, of ^vhich light is the carrier. 
 When this damp air or fleam is applied to a cold furface, 
 tuch as that of a glafs pane, it is decompofed. The wa- 
 tfr is attracted by the pa.^.by chemical affinity, and at- 
 taches itfelf to the furface. The fire, thus fet at liberty, 
 atls on the pane in another way, producing the equili- 
 brium of temperature, and the expanfion of the pane. 
 Afting in the fame manner on the moiilure which chances 
 to adhere to the other fide, in a proportion fuited to its 
 temperature, it deflroys their union, enters into chemi- 
 cal combination with the moifture, and fits it tor uni. 
 ting with the air on the other fide, or carries it off. 
 Having read Mr Veka's theory of elcClric influences, by 
 ■which that philofopher was enabled to give a fcientific 
 narration and arrangement of the phenomena of the elec- 
 trophorus newly invented by himlelf, and which is called 
 an explanation of thofe phenomena, Mr de l.uc ima- 
 gined that he faw a dole analogy between thofe in- 
 Jiuences on the plates of the ekcirophorus and the hy- 
 ^rofcopic phenomena of the condenfation and evapora- 
 tion of moifture. In fiiort, he was ftruck with the re- 
 femblance between the condenfation of moifture on one 
 fide of a glafs pane, and its evaporation from the other; 
 and the accumulation of eleftric fluid on one fide of a 
 coated pane, and the abftradion of it from the other. 
 Subfequent examination pointed out to him the fame 
 analogy between all other hygrofcopic and electric pheno- 
 , mena. 
 
 |§ He therefore immediately formed a fimilar opinion 
 
 '' roncerning the eleclric operations. It may be exprefled 
 
 briefly as follows : 
 439. The elcftrical phenomena are the operations of an 
 
 expanfive fubftance, called the eleftricjhiJ. This con- 
 fifts of two parts: i. EleSric matter, which is the gra- 
 vitating part of the compound ; and elsSric deferent fluid, 
 or carrying fuid, by which alone the eledric matter 
 feems to be carried from one body to another. The 
 refemblance between the hygrofcopic and eledlrical phe- 
 * See AVwnomena are affirmed to be*. 
 
 fur la Me. j ^^ Watery vapour or fteann is compofed of fire. 
 t jc;6. &c. deierent fluid, and water, the gravitating part, fo 
 
 eleSTic fuid is compofed of the eledric deferent fluid, and 
 eleSric matter. 
 
 2. As -vapcurs are partly decompofed when too denfe 
 for their temperature, and then ihek Jeferenl fuid ke. 
 comes free, and fliews itfelf as fre ; fo eleHric fluid 
 
 R I C 1 T Y. 
 
 that is too denfe is decompofed, and its deferent JJuul 
 manih.lts itfelt in \!t\t phojphoric and fery phenomena of 
 eledricity. 
 
 ^. As fre quits the ifiiter of -vapour, to unite itfelf 
 with a body lefs warm ; fo the eleilric deferent quits the 
 eleilric waiter, in part, to go to other bodies which have 
 proportionally Icfs of it. 
 
 In this analogy, however, there is a diftinftion. Fire, 
 in quitting the ivater in •vapour, remains attuated by 
 nothing but its expanllve force ; remains free, and ex- 
 tends itfelf till the equilibrium of temperature is rcfto- 
 red ; but the eteBric deferent, when difengagcd from 
 elearic nu:tter, in order to reftore its peculiar equilibrium, 
 is aituated by l,ndericies to dillincl bodies, and afts by 
 this tendency io thus reftoring the elettric equililirium ; 
 and it is only in confequence of this lendenry that it 
 quitted the eleSric matter. I'his ttnUeucy is then dirtft- 
 ed to fome body in the vicinity. 
 
 4. As ihefre of vapour pervades all bodies, to re- 
 ftore the equilibrium of temperature, depofiting the ivater ; 
 fo the elcf.ric defrent quits the elettric matter, to reftore 
 the eledric eqmlilrium in an inftant, and for this pur- 
 pofe pervades all bodies, t'epofiting on t!;em the cltRric 
 matter which it carried, but cifl'erently, according to 
 their natures. 
 
 5. A.%fire and water, whi'e compofing -vapour, retain 
 their tendaicics and ajfinities by which they produce the 
 hygrofopic phenomena ; fo the ingredients of the eleSric 
 
 fluid, even in their ftate of union, retain their tendencies 
 and ajinities, wlu'cb produce the grcateft part of the 
 elednc phcncmena. 
 
 6. In particular, thi eleSric matter reXz'mihi tendencies 
 and affinities ; and farther, the elellrk ajjinities are, like 
 the hygrofopic, without any choice. 
 
 Here, however, there is a farther diftinftion. The 
 affinities of ivater refpeft only hygrofopic fubftances ; 
 but thofe of tlearic matter refptif all (ubftanccs, and 
 therefore refpeCf the common atmofpheric fluids. 
 
 7. Whew fre quits the water of vapour, to form the 
 equilibrium of temperature, it remains in the place where 
 ■vapour moil abounds, but is partly latent, not exerting 
 its powers ; fo in the reftoration of the equilibrium of 
 the cleiJric deferent among neighbouring bodies, thofe 
 wliich have proportionally moiX. eleSric matter alfo retain 
 moll deferent f aid, but in a latent ftate. 
 
 8. As two maifes of -vapour may be in expan/i-ve equi. 
 librium (which others caU Lalancing each others clafti- 
 city), although the -vapours contain very diiferent pro- 
 portions uifre and luater ; {■:, two mafil-s of ekSric fluid 
 may be in txpanfve equilibrium, although one contains 
 much more elcHric ma:ter in The fame bulk, provided 
 that the eledric defennt be alfo more cojjious. 
 
 _ The chief diftinifion that mingles with thefe analo- 
 gies is, that the ajinily of ivater to hygrojccpic fub- 
 ttances operates only in contaft, whereas eleSric matter 
 tends to diftant bodies ; and thefe diftances are very dif. 
 ferent in regard to different bodies. 
 
 Such is the refemblance which has appeared fo ftrong 
 to Mr de Luc. It is evidently the fame which furnilh- 
 ed the conjefture to Mr Ruflel, and which he confider- 
 ed mechanically, in order to explain the phenomena of 
 eleftric motions to ftudents of mechanical philofophy. 
 The only refemblance feems to us to appear in the con, 
 denfation of moifture contained in damp air. 
 
 Mr de Luc, led by the habits of his former ftudies, 
 
 attempts. 
 
 613
 
 6i4 
 
 attempts to explain every thing by the relations which 
 were noil famih'ar to him, iijfinit'tes and expanjsve foiies. 
 Let us attend a little to the manner in which he ex- 
 plains one or two of the moft general fafts. 
 
 I. Tlie conditions of condudors and non-condu8ors, 
 sjo. This dilHnftion depends on the differences in the tsn- 
 dcr.cy Xo diilant bodies: there are great differences in 
 thefe diftaiiccs according to the nature of the bodies; 
 and from tliis ariie great diilcrences of phenomena, in- 
 dependent of iniulation or non-infulation, which are 
 onlv the fenfible dilliiiC\ions of thefe claffes of bodies. 
 Ele&ric matter tends to conduilors at great diftances ; 
 but having reached them it does not adhere, and re- 
 mains tree to move round them, being dragged by the 
 deferent jluid ; but its tendency to non-condiidors is only 
 at fmall and infenlibledillances ; and having come into 
 contatt, it adheres, and can no longer be dragged by 
 tlie deferent fluid. 
 
 Hence the operation of conduSors and non conduBors ; 
 and there is no other foundation for the notion of idio- 
 eledr'ics and non-ele3rics, or eleftrics by comm.imication. 
 A part of a tion-conduSor takes as much eleSric matter 
 as it can from the fubilance farni(hing it ; but cannot 
 communicate it to another part, except very flowly ; 
 therefore, to communicate it to the whole furface, we 
 muft cover it with a conductor (Surely this is a dif- 
 riiiClion in the body, independent of the diftance of mu- 
 tual tendency !). 
 
 Hence, too, the property of non-conductors by which 
 the eleftric fluid is benumbed {^engourdi) or cramped ; 
 therefore we can accumulate a great deal in them ; and 
 it will remain long, being benumbed ; and if it be deter- 
 mined to quit them at once, the current will be much 
 more denfe than when quitting an equal conducing 
 furface. 
 
 Since conduSors do not fix the ehdric JIuld, it mtifl 
 circulate round them. It is urged to this motion by its 
 expaufme power, by which it would difperfe from a body 
 with inconceivable velocity, and perhaps the rapidity of 
 its motion would decompoie it, and caufe fome light to 
 emerge ; but it is at the fame time impelled by its ten- 
 dency to bodies. Thus, by thefe two forces, it runs to 
 a conditSing body, and muft circulate round it as the 
 planets do round the fun. In this circulation, if it 
 come to any great projection, it cannot follow the out- 
 line, becaufe fo abrupt ; it therefore flies off at all 
 joints and protuberances. It will be the more diffi- 
 cult to keep to an abrupt outline as the ftratum in cir- 
 culation is more copious or deeper, becaufe a greater 
 mafs is with greater difficulty turned round a fliarp angle. 
 It is more inclined to efcape if another body be near, 
 and it immediately becomes a fatellite to that body. 
 
 Thus all bodies get a fliare of eledtric fluid, circula- 
 ting round conductors, and benumbed or cramped in non- 
 conduSors. Bodies of this laft clafs receive their por- 
 tion by the air as hygrofcopic fubflances receive their 
 water by \}n.tfire. 
 
 All the differences in the tendencies to bodies pro- 
 ceed from the cledric matter The deferent fluid follows 
 other laws ; namely, i. Its tendency to all fubflances 
 is greater than that of the eleSric matter to any one. 
 2. The tendency (and alfo that of the eleSric matter) 
 is always from the body which contains moft of it to 
 that which contains leaft. 3. The body which contains 
 
 ELECTRICITY. 
 
 moft of the one alfo contains tpoft of the other. 4, 
 
 The deferent fuid has a particular affinity (chemical) 
 with the elefiric matter. 5. All thefe tendencies are lef- 
 fened by an increafe of diftance. 6. The eharic matter, 
 when compofing etedric fluid, has more or lefs expan/ive 
 farce as it is united to more or lefs deferent Jiuid. 
 
 Explanation of Charged Plates. 
 
 Mr de Luc fays (f 286.), that his System was f-ig- 
 gefted by Volta's Theory of Eharic Injiier.ces. Tlitfe 
 (fays he) had been pretty well generaliled before, but 
 with little improvement to the fcience, till Mr Voltadif- 
 covered a circumftance which, in his opinion, coniieftcd 
 by a general theory many phenomena which had formerly 
 no obferved relation to any thing. This was, that luhett 
 a body elcBrifed pofitively brings a neighbouring body com- 
 municating ivith the ground into the negative f late, its oivit 
 pofitive electricity is weakened while it remains in that neigh • 
 bourhood, hut is recovered when the ether bodv is remo- 
 ved. " Such is the diftinguiftiing law of Mr Volta's 
 theory, which brings all the phenomena of eletlric in- 
 fluences under his theory, beginning with thofe of coat- 
 ed glafs, which were formerly fo obfcure, becaufe they 
 were not referred to their true caufe, &c. 
 
 " My Systlm (Mr de Luc fays) concerning the 
 nature of the eharic fluid explains the laws of Mr Vol- 
 ta's theory ; and of confequcnce explains, like it, all 
 the phenomena which it comprehends : but it reaches 
 much farther, feeing that more general laws compre- 
 hend a greater number of phenomena. 
 
 " In the phenomena of coated glafs, I plainly fawr 
 one of the procedures of watery vapour. Suppofe a 
 glafs pane, moiftened on botii iides, and having the 
 temperature of the iurrounding bodies. Suppofe that 
 warmer vapour comes to one fide. It is condenfed on 
 the furface ; that is, it is decompofed, the water ad- 
 heres to the furtace, and X.)\i: Jire penetrates the glafs, 
 heats it, and increafes the evaporation from the other 
 fide, by entering into combination with the water, and 
 carrying it off with it. More -vapour is condenfed on 
 the fide A ; more Jire reaches the fide B, and carries 
 off more water. But as this happens only becaufe the 
 Jire alfo raifes the temperature of the pane, jjt is evident 
 that the condenfation on the fide A, and the evapora- 
 tion from B, muft gradually flacken, and the maximum 
 of accumulation in A, and of evaporation from B, will 
 take place when the temperature of the pane is the 
 fame with that of the hot vapour. 
 
 " The eleftrical phenomena of coated glafs are per- 
 fedly fimilar. The ekaric fluid reaches the fide A, is 
 decompofed, and the eharic matter is there benumbed 
 and fixed. The deferent fluid penetrates the pane, and 
 carries off the eharic matter from the fide B. This 
 goes on, but flackens ; and the maximum of accumula- 
 tion and evacuation obtains when the fide A has ac- 
 quired the fame intenfity of electricity with the char- 
 ging machine. More is accumulated in A than is ab- 
 ftraCled from B ; becaufe B is farther from the lource 
 (he might have added, that part of the fire is expend- 
 ed in raifing the temperature of the pane) : but the 
 accumulation is inadlive, becaufe the eharic matter is 
 benumbed and fixed. Though the eharic matter is 
 much diminidied in B, yet the eharic fluid in its coat- 
 ing has as much cxpanfive force as that of the ground ; 
 
 becaufe 
 
 iji.
 
 ELECT 
 
 becaufe it lias a furplus of deferent fluid. The abfolute 
 quantity of ekaric matter in both fides isfomewliat aug- 
 mented." 
 131. This explanation of the LcyJen phial comprehends 
 the whole of Mrde Luc's tlieory; and the conllitution 
 of the eleftvic fluid, and its various affinities, txpanfive 
 powers and tendencies, are all afligned to it in fiibfcr- 
 viency to this explanation, or deduced from thofc phe- 
 nomena. As the author, in all his writings, claims iome 
 fuperiority over other naturalifts for more general and 
 comprehenfive views, and for more fcrupulous attention 
 to precifion and meafurement, and particularly for more 
 folicitude that no natural agent be omitted that has any 
 (hare in tlie procedure — he furely will not be offended, 
 although we (hould ftate fuch difficulties and objettions 
 as occur to us in the confideration of this System (as 
 he choofes to call it) of eleftricity. 
 
 We wifh that it had been exprcffcd in the plain and 
 precife language of mechanical and chenn'cal icience; for 
 he reafons entirely from the nature of cxpanlive forces, 
 tendencies, and affinities. His language will appear to 
 fonie readers, as it does to us, rather to exprefs the con- 
 duft of intelligent beings, acting with choice, and for a 
 purpofe, than the laws of lifelefs matter. His account 
 would have been lefs agreeable, it is true, but more in- 
 ftruttive, and lefs apt to be miftaken. Metaphorical 
 language is feldom ufed without the ri/k of metaphori- 
 cal conceptions ; and the reader is very apt to think 
 that he has acquired a notion of the fubjedt, while he 
 is really thinking of a thing of a different nature. We 
 apprehend that a great deal of this happens in this in- 
 ftance, and that when the narration is (hipped of its fi- 
 gurative language, it will be found without that con- 
 nexion and analogy which it feems to puffefs. 
 
 We alfo wifh that the explanation had been derived 
 from fome well-eftablifhed principle. The whole of it 
 is profejfedly founded on a refemblance between the 
 phenomena of eleftricity, and fome things faid of wa- 
 tery vapour; but thefe are not the phenomena of wa- 
 tery vapour, but Mr de Luc's hypothej'u (he will par- 
 don us the term, which we prefer to JyJIem) concern, 
 ing iwatery •vapours. We do not think it philofophi- 
 cal to explain one hypothefis by another. Our illuf- 
 trious countrymen, Bacon and Newton, difapproved of 
 this praftice; and their rules of philofophifing have ftill 
 currency among philofophers. Explanation, in our opi- 
 nion, is the pointing out fome acknowledged general 
 faft in nature, and fhewing that the particular pheno- 
 menon is an example of it. We do not fee this in Mr 
 de Luc's explanation ; becaufe we do not fee the fads 
 in fhe cafe of watery vapours to which the phenomena 
 of eleftricity are faid to have a refemblance. The phe- 
 nomena we mean are chiefly the motions, and the transfe- 
 «nffj of the powers producing fuch motions ; we do 
 not fpeak of the light, and fome other phenomena, be- 
 caufe Mr de Luc does not fpeak of them in this ex- 
 planation. We fhall even admit the transference as a 
 phenomenon, although we do not fee any tubflance trans- 
 ferred : but we fee a power of producing certain mo- 
 tions where that power did not formerly appear ; and 
 the appearance of this power is alt the authority addu- 
 ced, even by Mr de Luc, for the transference. We mull 
 
 R I C I T Y. 
 
 now add, that the eleiftric phenomena, which Mrde Luc 
 calls like the phenomena of watery vapour, are ^ fup- 
 pofu'ions; and tiiat therefore the explanation is a fyileni 
 of fuppofitions, framed fo as to be like tlie fyflem of 
 watery \T.pour. For Mr de Luc will grant, that, on 
 the one li md, we fee nolhiiig like the water in the elec- 
 tric phenomena ; and, on the other hand, there is no- 
 thing in watery vapour like the motions of the elettro- 
 meters, which arc the only phenomena from v.'hich Mr 
 de Luc profeffes to reafon. 
 
 We alfo fear that the very curious experiments of 
 Count Rumford on the melting of ice, and the propa- 
 gation of heat through liquids, will oblige Mr de Luc 
 to change the talks of tli» ingredients, both of vapour 
 and of cleElric fluid. Water, and not jire, feems to be 
 the carrier or deferent fluid ; and we think that Frank- 
 lin and iEpinus have made it highly probable that elec- 
 tricity, and not air, is the carrier. 
 
 We have alfo grc.it dilficulty in conceiving (indeed 
 we cannot conceive) how the deferent fluid, irom which 
 the ekilric matter has been detached by its fuperior af- 
 finity with the fide A, can overcome the fame fuperwr 
 affinity of the electric matter with the fide B ( a), and car- 
 ry it off; how the deferent fluid penetrates the non-con- 
 dufting pane, in order to carry off the eledric matter in 
 the form of fluid ; and how it cannot do this, except 
 by means of a conduSing canal, into which it is expreff- 
 ly faid that it does not penetrate. It mufl not be faid that 
 it runs along the iurface of this canal : for the fmalleil 
 wire will be a fufficieut conduftor, covered a foot thick 
 with fealing wax. This indeed, according to Mr de 
 Luc, allows the deferent_y?«;V/ to pais; but it muff alfo, 
 according to him, ftrain it pretty clear of all eleSric mat- 
 ter. For we cannot help thinking, that the proccfs 
 (although purely ideal) has a clofer refemblance to what 
 we ihould obferve in a ftream of muddy water poured 
 on a ftrainer, both fides of which are previoufly foul. 
 If we were difpofed to amufe ourfelves with a figura- 
 tive hypothefis, we could give one on the princijile of 
 filtration that is very pretty, and p^t ti» the purpofe, of 
 glafs coated, and charged and difcharged by conduttinj; 
 canalp. 
 
 With refpeft to the fuggcllion of this theory by Vol- 
 ta's theory of eleftric influences, and the ignorance of 
 naturalifts before that time ot the true llatc of things, 
 we muft obferve, that Mr Ruifel propofed the fame 
 analogy to the confideration of his hearers many years 
 before ; and it was very generally known. The elec- 
 tric influences had been fully detailed by .(Epinus and 
 Wilcke in 1759, ^"'^ applied with peculiar addrefs and 
 force of evidence by Mr Cavendifli before 1771 ; and 
 they were defcribed nearly in the fanif; way by Lane, 
 Lichtcrberg, and others. 
 
 And vv'itli refpett to Mr Volta's general principle, 
 which Mr de Luc prizes fo highly, and by which he 
 explains every thing, we mult obferve, that it is not true 
 as a phenomenon in ele3ricity ; but, on the contrary, the 
 pojitive flnte of a body is r endered Jlronger, or mure remark' 
 able, by inducing the negative fiate on a neighbouring body. 
 See n' j2. and 66. — Mr Volta was mifled by the appear- 
 ances of the eletfrophorus, winch had engaged all his 
 attention, and modelled all his notions on thefe fubjefts- 
 
 His- 
 
 €15 
 
 (a) We may here allc, How comes there to be fuch a quantity of eleftric matter already lodged in B ?- 
 kcDucobed ] or in what fiate is it ? 
 
 -Is ;«L
 
 6i(i ^ . ELECT 
 
 His obfervations had been confined to dilka ; and though 
 theie are excellent iiiftruments fur prodi.iciiig very fen- 
 fible effects, they arc quite unfit for examining- the ge- 
 neral nature of eledrfc influences. Even without much 
 knowledge of dynamics, a perfon iniilt perceive that the 
 aftion of their different parts on the eletlrometer may 
 be very different, by reafon of their different pofitions 
 and dilhinces fronj it. Befides, the eleftrometcrs of the 
 apparatus defcribed by Mr de Luc in feA. 443. SiC. did 
 not indicate the real condition of the dilks to which they 
 were attached, but the condition of the remote ends of 
 overcharged coiidiiftors of confidtrable length. There- 
 fore, although all the eleftrometers fell lower when the 
 other group of difl<s was '». night near, the pofitive 
 ftate of the neareft difl< was greatly augmented. The 
 moft unexceptionable apparatus for this purpofe would 
 be a row of polifhcd balls on infulating (lauds, placed 
 in contart, the whole charged pufitive ; and when ano- 
 ther fuch group, or a long body, is brought near, let 
 the balls be feparatcd at once, and examined apart by 
 a verv fmall eleftrometer, made in the form of our fi- 
 gure 8. We prelume to fay that, if the other group 
 is properly managed, and made to communicate tho- 
 roughly with the ground, the pofilive electricity of the 
 bails nearell to it will be found greatly augmented, and 
 that every one of them will be found in that precife 
 ftate of elercrification that is pointed out by the ^pi- 
 nian theory. Mr ile Luc has made and narrated the 
 experiments with the diilv's, and the curious figures oh- 
 ferved by Lichtenbergh, with great judgment and ii- 
 delity ; a';d they are claffical and valuable exjjeriments 
 for the examination of the theory. We may here men- 
 tion a very neat wiy of executing the apparatus of balls, 
 which wjis praftil^ed by a young friend, who was io 
 kind as to make the experiments for us, when our 
 thoughts were turned to Mr de Luc's theory. Each 
 ball was momiteJ on a (lender glafs rod varniihed. The 
 lower cad of the ftalk was fixed in a little block of 
 wood which had a Iquare hol^ through it, by which it 
 Aided fteadily along a horizontal bar of mahogany, iup- 
 poi ted at the ends about an inch from the table. The 
 balls were •.■■.lade to feparate at once, and equally, from 
 each other, by a chequer jointed fran'ie, fuch as is feeu 
 in the toyfiiops, carrying a company of foot ioldiers, 
 who open and clofe their ranks and filfes by pulling or 
 pufhing the ends of the frame. Taking out the pins of 
 the middle joints of this chequered frame-work, and 
 widening the holes for receiving the glafs ftalks, it is 
 plain that ^11 the balls will feparate at once, in the very 
 ftate of eledricity in which they were when in the 
 neighbourhood of the non-infulated group. This ap- 
 paratus confiiled of fix balls. We found the ball next 
 the other group much more ftrongly pofitive than be- 
 fore bringing that group near; and it was generally the 
 third ball which fcemed equallv eledtric in both fitua- 
 tions. We added nine balls more, connecling the whole 
 by a fimilar contrivance; and found it a moil inftruc- 
 tive apparatus for the theory of the dilbibution of the 
 eleftric fluid. We wifli that it had occurred to us when 
 the n" 62, &c. were under confideration. 
 
 With refpedl to the condition in which the eleftric 
 matter is faid to be lodged in the fide A of the coated 
 pane, where Mr de Luc fays that it is fixed, engourdi, 
 in the non-condu3'ing furface (which condition Mr de I.t c 
 confiders as charafteriftic of fuch fubftances), we muft 
 
 R I C I T Y. 
 
 fay that the defcription of its ftate is by no means agree- 
 able to what we have obuived. The powers of this 
 elitTriL- imfter are no more i^numled or enervated (it is a 
 very unphilofophieal phrafe), than if it were in a con- 
 du3ln_^ body at the fame dillance from the oppofite coat- 
 ing. If coatings be applied to a block of glafs of two 
 or three inches m thicknefs, and if the eledriTicatiou be 
 fo moderate that it would not fly from the one coating 
 to the'olher when the glafs is removed — no feufible dif- 
 ference will be found between the electricity of the 
 two coatings with or without the glafs. The electric 
 matter in the fide A has not its powers engourdi; they 
 are balanced bv the pov.crs of the fide B. 
 
 But how will Mr de Luc explain the charging a pane 
 negatively.' How will he bring off a quantity oi /-ledric 
 matter, greater (^according to his own account) than 
 what will be benumbed on the other fide ? Nay, we muft 
 a(l<, where does he find it ? Is there a quantity already 
 benumbed there ? What is to revive it ? 
 
 Let us now coiifider a little the co.iftitution of the 
 ingredients of this eledric fluid, by which ail thefe 
 things are brought about. And in doing this, let 
 us banilh, when poffible, all figurative language ; and, 
 iu the precife and dry phr.iicology of dynamics, let us 
 ipeak of the motion of finglc particles of the elcdric 
 JJaid, deferent Jluid, and e/edric matter. By expatijlve 
 power, mull certainly be meant fuch a power as that by 
 which air, gafes, inilamed gunpowder, fteam, and the 
 liliC, enlarge their bulk, and which is clearly manifefted 
 as a mechanical prtffure, by burlling veffels, impelling 
 bullets or piitons, &c. as well as by the attual enlarge- 
 ment of the bulk of the fluid. We have no other in. 
 dications of its being a force; and therefore our notions 
 of its mode of a£Ving mull be derived folcly from what 
 we underjland of tiiis power in air or the other fluids. 
 Newton's Pr'wc'tpia arc our authority for laying that all 
 that we know of it is, that it a£ts as a number of cor- 
 pulcles would art, which repel each other with a force 
 inverfcly proportional to their diilances; tliis aclion not 
 extCiiding beyond the adjoining corpufcle, not even to 
 the fecond. We know a good deal of the propagation 
 of prelfure and progreffive motion through fuch a fluid, 
 when it is confined in a velfel, or fyllem of veffcls, of 
 any form, and fome few fimple circumflances which 
 take place in the elallic undulations which may be ex- 
 cited and propagated through it. We have but a "very 
 indi/linS notion ot the motions which one mafs of fuch 
 a fluid will produce in another mafs, when both are at 
 liberty to expand. This is very indilliridl ; but we are 
 certain that it will be like the motion of two maffes of 
 air blown or driven againll each other. Now thefe 
 eleftric fluids, by their expanfivc powers, mull aft like 
 thofe others with wliich we are more familiarly ac- 
 quainted. And here we venture to fay, that the ajipear- 
 ances in eleftricity are io far from being like thefe, 
 that we cannot imagine any thing more remarkably dif- 
 ferent. We (hall mention but one thing. Every mark 
 that we have hir the prefence of eleSric fluid obliges us 
 to grant, ttiat in an overcharged body it is crowded in- 
 to the external furface, fo that the quantity has little 
 or no relation to the quantity of matter in any body, 
 but merely to its furface. This is quite unlike air, or 
 any other expanfive fluid, which is uniformly diftribu- 
 ted through the whole fpace comprehended by the 
 furface which bounds it. We never faw any thing 
 
 like
 
 ELECTRICITY. 
 
 like ftreams of tin's «/f(9r/V^«(W, Impelling or any way aifl- It is not enough to fay that it is fo ; 
 
 this would only 
 
 617 
 
 ingon each other, except in the tranifeience by fparksj be coiitiiving a thing to fuit a purpofe ; a reafon fhould 
 
 and tliere it was indeed like the motions of air, for it was be given if we pretend to explain. Now the tendency 
 
 not elcflric fluid, aox ekflric maikr, but c/ti3ri/hti air. to a didant body is to the matter in that body, without 
 
 Let us next confider the tendencies by which the re- any relation to the fluid in it, or in the body from 
 
 lations of tJicfe expanfive fluids to other bodies are pro- which it came. 
 
 diiced, and the eleftric motions are faid to be explained. On the whole, we cannot think this theory is any 
 
 We obferve that Mr de Luc avoids the ufe of the words thing but telling a ftory of ideal beings, in very figura- 
 
 attradicn and rcpulfi;ii, fo much employed l)y the Bri- tive language, wliich gives it fome animation and intc- 
 
 tlfli philofophers. He confiders thefe tendencies as de- reft. The different affinities, tendencies, and powers, 
 
 terminate impulfions, and adopts the doftrine of Le are only ways of exprefiing certain yu/>/;o/''(y events, and' 
 
 8(igc of Ginevii, who IiHS not only laid Newton under fuitcd to thofc evcnt.s : but it gives no explanation of 
 
 great obligations, by a mechanical explanation of gra- the obfervcil mechanical phenomena of eledrieity, Ihewiug 
 
 vity, but has alio explained exjianfion, clallicity, che- from acknowledged principles that they muft^ be fo. 
 mical affinity, and all fpecific tendencies, to the fatif- AVhat a diflcrence between this laboured and intrl. 
 
 failion of the moil eminent malhematicians. To fuch cate mechanifm, and the fimple, perfpicuous, and dif- 
 
 only Mr de Luc profeiTes to a<ldrefs himfelf, who are tindl theory of jEpinus ! Even Mr Rufl'tl's explana- 
 
 not contented with a dotlrine which fuppofes bodies to tion is more inttlligible, and more ajiplicible to the ?no- 
 
 aft where they are not. But, unfortunately, Mr le tionj which are really oblerved. That gentleman faw 
 
 Sage has never obliged the world with this explanation, the neceffity of confidering them as the fubjed^s of mc- 
 
 We are not moil eminent mathematicians; but we are chanical difcujfton, and that all that was wanted was to 
 
 able to prove, that Mr le Sage's favourite theorem, men- find out what law of dlilant aifllon would tally with the 
 
 tioned by Mr de Luc in ^ 157, 1^8, as demonttrated phenomena. The Scotch phllofopher was careful to 
 
 by Mr Prevoft, the editor of Lucrcce Neulomen, is a warn his hearers th<it he only propofed a conjeHure. The 
 
 complete dereli£lion of the firil principles of Mr le Swede calls his performance Tcnlamtn Tbeorix, &c.and 
 
 Sage, and is alfo incompatible with mechanical laws, begins and concludes it with exprefsly facing, that it is 
 
 Mr de Luc fhould have given a demonftratlon of the only a hypclhefu. The Englidi nobleman calls his dif- 
 
 theorem on which all his iyflem refled ; othervvife it is fertation an Attempt to explain fome of the phenomena, 
 
 only reviving " dixit philofophus, ergo veruin." &c. None of thefe philofophers call their works a SYS- 
 
 But let us fee what thefe tendencies perform. Mr tem, which comprehends all theories, whether tliat of 
 
 de Luc fays, that the fluid, fetting out from a body by Volta or of any other fuccefsful inquirer, 
 its expanfive power, would move in a ftraight line with We hope to be excufed for treating fo largely of this 
 
 inconceivable velocity, and would immediately defert fubjedl. It llruck us as a very proper example of the 
 
 even this globe, were it not defleAed by its tendency to bad confequences of indulging in figurative language, 
 
 other bodies. We do not fee whence this immenfe ve- It mufl: be very feducing, when fo fcrupulous and fo 
 
 locity is derived. But let it go off; it is deflected from eminent a phllofopher as Mr de Luc is led aftray by it. • 
 its reAilineal courfe by its tendency to fome coudufting 
 
 body, which it reaches, but cannot, nor does not enter; We conclude this long article by obferving, that 
 
 and therefore mujl cotitinualJy circulate round it, as the whatever may be the fate of Mr iEpinus's hypothetical 
 
 planets circulate round the fun, following its outline, if theory, his clafhlication of the fails, and his preciie de- 
 
 not too abrupt, but flying off from all points in the di- termination of the mechanical phenomena, to be expefted 
 
 redion of the axis of the point, &c. Here we are at from any propofed fituation and condition of the fub- 
 
 home ; for this is a plain dynamical problem of central llances, will ever remain, and be an nncrriiiD- dircitlun 
 
 forces. All that we fliall fay on this head is, that Mr de in future experiments ; and the whole is an illu'.lrious 
 
 Luc has certainly not confidered the planetary motions fpecimen of ingenuity, addrefs, and good reafoninr. 
 
 with attention, when he hazarded this very comprehen- We hope to make this ftill more evident, when we ap. 
 
 five propofition. If he will take the trouble to do this, ply it to the quiet and manageable phenomena of Mao- 
 
 lie will fee that every part of it is inconfiftent with the netism 
 
 acknowledged laws of mechanifm, and that the motions 
 are abfolutely impoffible. Befides, we know that it 
 will not fly off from a hundred points placed together, 
 which is a ilill more abrupt line, if they do not projeft 
 beyond the brim of a pit in which they fland ; yet this 
 pit only makes the outline more abrupt. We farther 
 believe, that, no perfon can form to himfelf any dllliuft 
 notion of fuch circulations round every condnfting bo- 
 dy ; they will be more numerous, and infinitely more 
 
 Pondere ei mcnfurd.. 
 
 APPENDIX; 
 
 CONTAINING AN ABSTRACT OF MR COI'LOMb's 
 EXPERIMENTS. 
 
 Mr Cot; LOME '\nt\e Mem. de P/lcad. de Paris for 
 
 confufed and jarring, than all the vortices of Des Cartes. 1786, relates feveral experiments made for afcertainins 
 
 How can fuch motions take place round a bunch of the difpofition or diflribution of the eleftric fluid in aa 
 
 brafs wire buried in fealing wax ? Yet he muft grant overcharged body. Their genera! refults were, 
 
 that they really happen there ; or what prevents the 1. That the fluid is dift;ributed among bodies accord- 
 
 eleSricJluid from htmg Jlrained clear of all eledric mat- ing to their figure, without any eleftive affinity to any 
 
 ter in paffing through the air ? kind of fubilance. 
 
 We would alfo afli, why the tendency is always /rom For when a ball, or body of conducing matter, and 
 
 the body containing mojl of thejiuid to that (ontaining Itafi f of aoy fhape, is eledrified to any particular degree, as 
 
 SurpL. Vol. I. Part H. 4 1 indicated 
 
 »33-
 
 6i8 ELECTRICITY. 
 
 indicated by his eleflrometer, if it be touclied by ano- The preceding propofitions are quite analogous to 
 
 ther equal and fimilar body, (imilaily fituated in rcfpeft propofitions in Mr Cavendilh's difTertation in the Phi- 
 
 of the touching points, the eledlricity is always reduced lofophical Tranfadlons for 1771. 
 
 to 4- t'l the Memoirs of the fame Academy for 1787, Mr 
 
 2. In an overcharged condufting body, the fluid dif- Coulomb endeavours to afcertain the denfity of the fluid 
 
 fufes itielf entirely along the furface, without penetra- in different bodies which touch each other. When the 
 
 ting into the interior parts. bodies do not differ extremely in magnitude, he deter- 
 
 The conducing body AB (fig. 37.) had pits a, b, mines this by the immediate application of them to the 
 &c. made in various parts of its furface. They were eleftrometer ; but when one is extremely fmall in corn- 
 half an inch in diameter, and fome of them Tsth, others parifon with the other, he firft determines the force of 
 x'o'hs, others To^hs, &c. in depth, c reprefents the the large body, and then touches it 20 or 40 times 
 edge of a fmall circle of gilt paper, -fth ot an inch in with the fmall one, till the force of the large body is 
 diameter, fixed perpendicularly on the end of a fine reduced to i, y, -f, &c. The general refult was, that 
 thread of gum lac. The body was eleftrified and when the furfaces of the fpheres had the proportion ex- 
 touched will) this little elcftrofcope, by fetting it flat jireffed in the firll column of the following Table, then 
 down on the furface. The circle c was then prefented the denfity in the fmall one had the proportion cxpref- 
 to an eleftrometeV which moved 90 degrees by a force fed by the numbers of the fecond column, and never at- 
 not exceeding yy-os^h of a French grain. When this tained the magnitude 2. 
 
 contatt was made with the even furface of the con- 1 1 
 
 duftor, it was ilrongly ekdrified, and pari icularly when 4 1,08 
 
 it touched any eminence, or the ends of long cylinders, 16 ...... . 1,3 
 
 &c. The paper being exceedingly thin, and placed in 64 1,65 
 
 full contaft, it may be fuppofed to bring off with it Infinite 2 
 
 the quantity of fluid correfponding to that part of the This is extremely different from the proportions 
 furface, or rather a greater quantity. But when it was which obtain when the two fpheres communicate by 
 made to touch the bottom, even of the flialloweft of thtfe ver^' long flender canals, which he found exaiitly con- 
 pits, it did net affeft the tleftrometer in the leall. formable to the determinations of the theory : but in 
 
 He demonftrates the following elementary theorem : Mr Coulomb's experiments the fpheres touched each 
 
 The attraftion or repulfion being fuppofed to be pro- other, and had no other communication. 
 portional to the inverfe of any power m of the diftance; He then endeavours to afcertain the denfity of the 
 I . r, a.- fluid in the different parts of the furface of thefe touch- 
 that is, being as — : if m be greater than 3, the aftibn j^^ fpheres, in order to obtain fome experimental know- 
 
 of all the ir.affes of fluid which are at a finite dift;ance is ledge of the dillrlbution. He touched them (while in 
 
 nothing in ccmparifon with the adion in contaft ; and mutual contaft) with the little paper circle, and exami- 
 
 therefore the fluid mnft be uniformly diffufed, in the ned its elettricity by his eleftrometer, and made his ef- 
 
 fame way as if each particle aflcd only on the adjoining timation on the fuppofition that it brought off one-half 
 
 particles. of the eleiSriclty of the touched part. 
 
 But if m be lefs than 3, for example, if m be ?, as When the globes were equal, he found the denfity 
 fecms to be the cafe in rleftricity, the aftion of all the to be o in the point of contaft, and fcarcely fenfible 
 maffes at a finite diftance is not infinitely fmaU in com- till he took the paper 30 degrees from the point of 
 • parifon with tlie aaion in cont3«, and' the redundant contafl. From this it incrcafcd rapidly to 60°; (low- 
 fluid muff go toward the furface, and no redundant fluid )y from thence to 90°; and from thence to 180" it was 
 will be retained in the interior parts. The demonftra- almoft uniform. The denfities were nearly 
 tion is to this effeft. o .... at ... . 0° 
 
 Let AaBF (fig. 38.) be a perfeftly conducing "bo- i . . . . — .... 30 
 
 dy of any fliape, and let i/dir be a thin flice feparated 4 . . . . — . ■ . . . 60 
 
 from the reft by the plane de ; let dee be precifely 5 . . . . — .... 90 
 
 equal and fimlhir to rfac, and let a ^f be perpendicular 6 . . . . — .... 180 
 
 to the feparating plane ; then the adlion of all the par- He alfo found, that the more the globes differed in 
 
 . tides in the thin (lice due (when eftimated in the di- bulk, the mor& is the denfity changed in the fmall globe, 
 
 reftion a b) on the particle b, mull balance the aftion and it is the more uniform in the gieat one, increafing 
 
 of all the reft of the fluid in the body ; for b is fuppo- rapidly from o, at the point of contact, to about -j", and 
 
 fed to be at reft. Now, as the law of continuity will beyond this being fenfibly uniform, 
 
 be obferved in any diftrlbution of the fluid, through the Hence we may conclude, that the elcftriclty is dif- 
 
 nvhole body, it is plain that, by taking ab fufficiently fufed with almoft pcrfeft uniformity in a globe com- 
 
 fmall, the difference of denfity at a and at c may be infi- municating with another at a great diftance by a flcn- 
 
 iiitely fmall ; therefore the aftion of the fluid in daevi\\\ der canal (as Mr Cavendifli has demonftrated) ; while, 
 
 be infinitely near to an equilibrium with the aftion of from the reafoning employed before, it is probable that 
 
 dee ; and the aftion of the fluid in the reft of the body it is alfo uniformly diffufed all along the canal ; and 
 
 on the particle b will be infinitely fmall. This cannot therefore, that tlie quantities in tv/o fuch globes are very 
 
 be, when the aftion of a mafs of fluid at a finite diftance nearly as the diameters, and the denfities inverfely as the 
 
 is not infinitely fmall in comparlfon with the aftion in diameters, as Mr Cavendllh demonftrated, on the fup- 
 
 contaft, ui.lcfs we fnppofe that the quantity of fluid at a pofitlon that the fluid in the canal is incompreffible. 
 
 finite diftance is alfo infinitely fmall, or nothing ; that He found that a fmall globe, placed between two 
 
 is,unlcfs the whole redundant fluid is conftlpated on the equally large ones, ftiewed eleftricities of the fame kind 
 
 furface, and the Intcrioi" parts are mcrtly faturated. with that of the other two, whea the radius of the 
 
 great
 
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 Fl^r 
 
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 -V*- 
 
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 Ye 
 
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 1 1. 1.1 /.J i-i. --./■'«//,
 
 ELECT 
 
 great one wasi not more than five times that of the mid- 
 dle one, but fhewed no eleClricity when the dilpropor- 
 tion was greater. 
 
 When three equal globes were in contadl, the denfi- 
 
 ty of fluid inthe middle globe was of that of the 
 
 ' " 1,34 
 
 ether two. A fmall globe being removed to a very 
 fmall diftance from an overcharged great one, after ha- 
 ving been in cnnlad, (liewed oppofite eleftricity in the 
 fronting point ; when a little farther off, it was neutral ; 
 and beyond this, it was overcharged- 
 
 The diameters being 1 1 and 8, the fronting point of 
 the fmall one was negative till the dillance was i ; 
 here it was neutral, and when it was removed farther, it 
 was pofitive. When the diameters were I r and 4, the 
 fmall globe was negative till their diftance was z, where 
 it was neutral. When the diameters were 11 and 2, the 
 diftance which rendci-cd the fmall globe neutral in the 
 fronting point was i\. 
 
 All thefe fafts are perfectly conformable to a mathe- 
 matical deduftion, from the fuppofition that the redun- 
 dant fluid is fpread over the furfacc, and that the in- 
 terior points are neutral. If any fort of doubt (hould 
 remain in the minds of thofe who are not convcrfant in 
 fuch difcufiions, it muft be greatly removed by the fa6t, 
 that it is quite indifterent whether one or both globes 
 be folid, or be an extremely thin fhell. 
 
 When an eleftrified body is touched with a long 
 wire, and by another of equal diameter and length, 
 coated to any thicknefs with lac or fealing wax, the 
 
 R I C ! T Y. 
 
 two wires take off precifely the fame quantity of elec- 
 tricity. Tin's was demonftrated by touching a globe re- 
 peatedly till the elertricity was reduced to \ 
 
 Hence we muft conclude, that the cleftric fluid does 
 not form a6b"ve atmofpheres around bodies, by the 
 atliou of whofe particles in contad (mathematical or 
 pliylical) the phenomena of attraftion and repulfion are 
 produced, but by the aftion of the fluid in tiie body, 
 agreeable to tlie theory of iEpiuus. 
 
 Such are the obfervations of Mr Coulomb Tliey 
 are extremely valuable, becaufe they confirm in the 
 completeft manner the legitimate confcqucnces of the 
 theory. 
 
 We think that the materiality of that which is 
 transferred from place to place in the exhibifion of 
 eleftric phenomena, is greatly confirmed by fome obfer- 
 vations of Mr Wilfon's in the Pantheon. When a 
 fpark was taken from the whole of the long wire ex- 
 tended in that vail theatre, the fenfatiou was fo different 
 from a fpark which conveyed even a much greater 
 quantity of fluid from a pretty large, but compaft, fur- 
 face, that they could hardly be compared. Tiie laft was 
 like the abrupt twitch with the point of a hooked pin, 
 as if pulling off a point of the Hcin ; the. fpark from the 
 long wire was more like the forcible piercing with a 
 needle, not very ftiarp, breaking the (Ivin, and pufhin'-r 
 it inward. We had this account from the Doflor in 
 converfation. He afcribed it, with feeming juftice, to 
 the momentum acquired by the fluid accelerated along 
 that great extent of wire. 
 
 619 
 
 •w»f!**;S"^i^KVSN»'»" 
 
 learicity, 
 
 ledrome- 
 ter. 
 
 \ 
 
 E L E 
 
 Animal Ehicniicirr. See Galvanism, in this Sup- 
 plement. 
 
 ELECTROMETER, is an inflirument which mea- 
 fnres the quantity of elcftricity in any eledlrified body. 
 The moft common eledlrometers are defcribed in the 
 article Electricity (EiicycL), n° 27, and 182 — 233. 
 A very valuable one is likewife defcribed in n" 85. of 
 the article Electricity in this volume ; but there are 
 (lil! two eledlrometers, of which we have hitherto given 
 no account, though they are of fuch value, that to pafs 
 them unnoticed would be unpardonable. The firft, which 
 is incomparably the moft accurate and delicate inftru- 
 ment of the kind that we have feen, was invented by Mr 
 Coulomb, and is adapted to afcertain the fmalleil quan- 
 tity of redundant eledlricity. The fecond is a late in- 
 vention of Mr Cutlibertfon, the ingenious improver of 
 the air-pump, and is employed only to meafure' the 
 charge of large jars and batteries. 
 
 Electromiter, by Mr Coulomb of the Royal A- 
 cademy of Sciences at Paris, defcribed in the Memoirs 
 for 1 785. 
 
 Mr Coulomb had made fome experiments in exami- 
 nation of Dr Hook's theory of fprings " «; laifto ftc 
 •vis ;" and found, that it was furprifingly exaft, in re- 
 gard to the force neccffiry for tvvifting claftic wires. 
 Having iuipended a nicely turned metal cylinder by a 
 fine wire in the direftion of its axis, and having given 
 it feveral turns, and left it to regain its natural pofition, 
 he obferved, that it performed all its revolutions of un- 
 twifting and twifting in times precifely equal, whether 
 thefe ofcillations were of a few degrees, or confifted of 
 
 E L E 
 
 feveral revolutions. He thence concluded, that the Eiedtrome. 
 force with which the wire endeavoured to regain its ' tir. 
 natural pofition was exadly proportional to its diftance'— v—' 
 from it. Engaged, foon after, by order from the Mi- 
 nifter of Marine, in an examination of the phenomena 
 of the mariner's compafs, he took this method of fuf- 
 pending his needles, in order to obtain exaft meafurea 
 of the forces which caufed them to deviate from the 
 magnetic meridian. He made fome obfervations with 
 needles fo fufpended ; which are highly valuable to the 
 philofopher engaged in that ftudy. When his fuccefs 
 in this refearch had fully gratified iiis wifiics, he turned 
 his thoughts to the examination of the law of elcftric 
 adlion by the help 'of an elcftrometer fufpended in the 
 fame manner. It is conftructed as foFlovvs : 
 
 ABDC (fig. 1.) reprefents a glafs cylinder, i2Plate 
 inches in diameter and in heiglit. This is covered by ^^^'f- ■ 
 a glafs plate fitted to it by a projei'ting fillet on the un- 
 der lurface. This cover is pierced with two round 
 holes of i|th inches in diameter. One of ihem/is in 
 the centre, and it receives the lower end of t~lie glafs 
 tube/Zi, of 24 inches height, which is fixed in the hole 
 with a cement made of fealing wax, or other elcdric 
 fubftance. The top of this tube receives the brais 
 collar H (fig. 2. n° 3.), bored truly cylindrical, and 
 having a fmall fhoulder, which refts On the top of the 
 tube. 'I'hiscollur is fattened with cement, and receives the 
 hollow cylinder 'f (fig. 2. n" 2.), to which is joined the 
 circular plate a b, divided on the edge into 360 degrees. 
 It is alfo pierced with a round hole G in the centre, 
 which receives the cylindrical pin i (fig. 2. n^ 1.), having' 
 4 I I »
 
 E L E 
 
 [ 62 
 
 Eleflrome- a milled head b, and an index i 0, wliofe point lb bent 
 '"■• down, fo as to mark the divilions on ti»e circle a b. This 
 ~~'^' ^pin turns ftiiHy in the hole G, and the cylinder "t> 
 turns fteadily in the collar H. To the lower end of the 
 centre pin is faftened a little pinctr q, formed like the 
 end of a port crayon, and tightened by the ring q, fo 
 as to hold fall the fufpenfion wire, the lower end of 
 which is grafped by a fiiialar pincer P (iig. ?. ), lighten- 
 ed by the ring f . The lower end i o\i cylindrical, and it 
 is of fiich weight as to ftrain the wiie perfcftly llraight, 
 but without any ri(l< of breaking it. It may be made 
 half of the weight that will jnft break it. 
 
 This pincer is enlarged at C, and pierced with a hole, 
 which receives tightly the arm g Q. q of the elcdrome- 
 ttr. This is eight inches long, and confifts of a diy 
 fdk thread, or^ender ftraw of fome grafs completely 
 dried, and dipped in melted giim lac or fine fealing 
 wax, and held upright before a clear fire, till it form 
 a (lender cylinder of about y'^th of an inch in diamtter. 
 This occupies fix of the eight inches, from ^ to y : 
 the remaining two inches is a fine thread of the lac or 
 fealing wax, as it drains ofT in forming the arm. At a 
 is a ball of pith of elder or fine cork, one-fourth or one- 
 half of an inch in diameter, made very fmooth, and gilded. 
 It is balanced by a vertical circle^ of paper, of large di- 
 menfions, ftiffened with varnifh. The rtfillance of the 
 air to this plane foon checks the ofcillations of the arm. 
 
 The whole is feen in its place in fig. I. where the 
 arm hangs horizontally about the middle of the height 
 of the great cyhnder. In its ofcillations the ball a 
 moves round in a circle, whofe centre is in the axis of 
 the whole inftrument. Its fituation is indicated by a 
 graduated circle Z O Q^ drawn on a flip of paper, and 
 adhering to the ghifs with varnifh. The eledtrified bo- 
 dy, whofe aition is to be obfen,'ed, is another fmall ball 
 of cork /, alfo gilt, or a brafs ball well poliflied. This 
 is canied by a flalk of gum lac m ?, inclofing a dry filk 
 thread. This flalk is grafped by a clamp of cleft deal, 
 or any fimilar contrivance which lies firm on the glafs 
 cover. When this ball is let down through the hole 
 m, it (lands fo as to touch the ball a on the arm when 
 that ball is oppofite on the graduated circle. 
 
 To eleftrify the ball /, we employ the infulating 
 handle, fig. 4. which is a {lender flick of fealing wax or 
 lac, holding a metal wire that carries a fmall pollfhed 
 metal ball. We touch with it fome eleftrified body, 
 fuch as the prime conduftor of a machine, the knob of 
 ajar, S:c. Introduce this elcflrified ball cautioufly in- 
 to the hole m, and touch the ball / with it. The ball a 
 is immediately repelled, and goes to a diflance, twitting 
 the fufpenfion-wire, till the force of twill exerted by the 
 wire balances the mutual repulfion of the balls / and a. 
 
 Such is the procefs for examining the law of elec- 
 tric aftion. But when we would examine the aftion of 
 different bodies in different Hates, another apparatus is 
 wanted. This is reprcfented by the piece c h. d (fig. 
 5.), confining of a ping of fealing wax A, w4iich fits 
 tight into the hole m, and is pierced by the wiie c d, 
 hooked at c, to receive a wire connecting it occafionally 
 with an eleftrified body, and having below a pohfhed 
 metal ball d. 
 
 The inftrument is fitted for obfervation in the follow- 
 ing manner : Turn the milled button b at top, till the 
 twift-indcx ;' is on the mark of the twill circle. Then 
 turn the whole iu the collar H, till the ball a ilands 
 
 o ] E L E 
 
 oppofite to the mark of the paper circle % OQ_»^and at Elcdromf, 
 tlie fame time touches the ball / or d- "^f- 
 
 The obfervation is made thus: The ball /is elec- v "" "J 
 trifled as already faid, and a is repelled, and retires 
 from /, twilling the wire, and, after a few ofcillations, 
 fettles at a diflance correfponding to the repulfion. Now 
 turn the twift-index, fo as to force the ball a nearer to 
 /. We ellimate the force of this new repulfion by add- 
 ing the motion of the twifl-indcx to the angle at which 
 the ball fiill refted. By turning the twill-index Hill 
 more, we bring the balls flill nearer, and have a mea- 
 fure of another repulfion. — And thus may we obtain 
 as many meafures as we plcafe. 
 
 In this way Coulomb afcertained the relation be- 
 tween the repulfion and the diflance to be the iuverfe du- 
 plicate ratio of the dillances. He difcovered the law- 
 of diffipation by air in contaft, and the relation which 
 this bears to the primitive repulfion, liy obferving the 
 gradual approach of a to / as the electricity diffipates 
 from both, and by flackening the twill-index till the 
 ball a retires to its primitive dillance. He afcertained 
 the diflipation along imperfeft conduSors and the 
 length neceffary for infulation, by completely infulating 
 the hall /, and obferving the lofs by air in contact with 
 it, and then fiiding a metal rod down the infulating 
 ftalk, till the difT.pation began to exceed what took 
 place by the air alone. He examined the proportion 
 of redundant fluid in communicating bodies, by con- 
 nefting them alternately with the piece, fig. 5. ; as alfo 
 by eleftrifyingone ball, and obferving its repullive force, 
 and then fliaring its eleftricity with another, and ob- 
 ferving the diminution. He examined the graduation 
 of his eleflrometer, by fharing the eleftricity of one 
 ball with an equal ball, which gave him the pofition 
 that indicated one-half; and, by repeating this, for one- 
 fourth, &c. in the fame manner as we praftifed and re- 
 lated in Electricity [SuppL), n'* 141, &c. 
 
 An example of one or two of thofe trials will give a 
 clear conception of the conclufions deduced from thefe 
 obfervations. 
 
 The ball / was introduced and eleftrified ; a was re- 
 pelled, and fettled at 40^ ; the index was twilled 140°, 
 which brought « to 20 ; and the time was noted. The 
 eL'Aricity gradually diifipattd, and a came nearer to t. 
 The index was untwiftcd 30", and a retired a little be- 
 yond 20'' ; but on waiting a few feconds, it flood ex- 
 aftly at 20^. The time was again noted. The inter- 
 val was exaOly three minutes. The conclufion from the 
 experiment was as follows : 
 
 When the ball was brought to 20°, the repulfion was 
 evidently 140 -H 20, or i6o. Three minutes after- 
 wards it was 210 -}- 20, or 130 ; and 30° were loft in 
 three minutes, or 10° per minute. The mean force was 
 145. Therefore the mean lofs per minute was -r^T- 
 Obferve alfo, that the primitive force correfponding to 
 the diflance was 40 ; and the force correfponding to 
 20 was 160, or inverfely as ro' to 40^. 
 
 But obferve, that the dillances were not meafured 
 by the angles, but by the chord of the angles. The 
 obliquity of aftion mull alfo be accounted for ; and the 
 real lever is lefs than the arm, in the proportion of ra- 
 dius to the cofine of ^ the angle. 
 
 The wire ufed by Coulomb in his firfl experiments 
 en the law of aftion was of fuch flrength, that -j-iTyth 
 of a French grain, applied at the point a, held it fall 
 
 till
 
 E L E 
 
 [ 6 
 
 Elc<flroiii«.t III the twift-index was turned 360"; fo that <iiio dc- 
 ''■^_^ gree correfponded to -j-,^'j;riy of a grain. A foot of 
 this wire weighed tV'' "' <• grain. Experience having 
 Piiwn that this was a fenfibilitv far exceeding what was 
 iiccffTary for the ir.eafuvej that he had in view, and 
 nvule the iifirument too delicate for common ulcs, he 
 fiihlHtnted mnch itronger and lliorter wires, and recom- 
 mends much f.maller dimenfions for the wliole inlbument. 
 We have made two of only <ive inches in diameter and 
 14 inches high ; the arm ag being 2 -j- inches, and the 
 fiif|)en(ion a fingle fibre of filk, carrying 30 grains. 
 It is far more feniible tlian Bennet's gold leaf elec- 
 trometer. The fame inltrume it, with a filver wire fuf- 
 penfion, and a thread of lac projecHng from the end g, 
 as an index to coincide more clofely with the fcale, is 
 fnfficiently nice for all experiments of meafiirement. It 
 is always proper to have the diameter of the cylinder 
 double the length of the arm, that the aftion of the 
 glafs may not dilturb the polition of the arm. It is 
 greatly improvf d by having a ronnd hole in the bottom 
 of the inllrument, in whivh the cylinder C of the 
 lower pincer may hang freely : this prevents much tedi- 
 ous ofcillation. For ordinary experiments, for nieafur- 
 ing charges of batteries, and the like, a much lefs deli- 
 cate inllrument, with a fufpcnfion-wire drained at both 
 ends, is abundantly delicate, and vallly more manage- 
 able. The wire ftould extend as far below the arm as 
 above it, and fliould be grafped below, by a pincer turn- 
 ing by a milled head in a hole at the end ef a flender 
 fpring. This enables us to adjuil the inllrument fpeedi- 
 ly. Having placed the twiil-index at c, turn this lower 
 button gently till the ball a points exa<Sly to o on the 
 paper circle. Even in this coarl'ell ftate we have found 
 it more delicate, and much more exaft, than the electro- 
 meter defcribed in Electricity {^Suppl.), n° 85. which 
 was much more coilly, and liable to accidents. Cou- 
 lomb's eleftrometcr has the great advantage of wailing 
 very little elefln'city ; whereas Henly's, or Brookes's, 
 or de Luc's, wafte it very fall when it is intenfe. 
 
 We improved it greatly by taking away the appara- 
 tus with the ball /, and fubftituting the piece, fig. 5. 
 for it, after changing its condrudlion a little. Inilead 
 of the wire c il, we ufed the fmalleft glafs tube that we 
 could varnifli on the inlide, by drawing through it a 
 filk thread dipped in varnifh. Having varnidied it with 
 lac both within and without, a brafs ball d was fixed 
 
 »on its lower end, and a fine wire, with a ball at top, 
 was put down into the tube, fo as to touch the ball be- 
 low. When the plug was fitted into the hole m once 
 for all, the fituation of the ball il fuftertd no alteration. 
 When delicate experiments are to be made, the upper 
 ball c is touched by the charger, fig. 4. which eleftrifies 
 </. C is immediately drawn out with a glafs forceps ; 
 and thus J is left completely infulated. When externi-.l 
 cleClricity, fuch as the faint eledtrieity of the aimo- 
 iphere is to be examined, the wire is allowed to re- 
 main in the tube. — A''. B. A fcrupulous experimenter, 
 who may objeft to the draining fpring recommended 
 above, may fubditute a fmall weight, which will be con- 
 daiit in its aftion. 
 
 The reader will obferve, that this eleftrometer, as 
 hitherto managed, meafures only repulfions. It is not 
 fo eafy to meafure attraftions with it ; and Mr Cou- 
 lomb was obliged to take a very circuitous method, du- 
 ring which a great deal of eleftricity was diflipated. 
 la this refpeft, the eleftrometer defcribed in the article 
 
 21 ] E L E 
 
 Electricity (•?«///.) has the advantage ; but in everv EleArome. 
 other refpedt, Mr Coulomb's is the fined elearomctc'r ^"• 
 that has yet been publidied, giving nbfolute meafures, and * ' ' 
 
 this with great accuracy. The Hon. Mr Cavendiih 
 h.is employed the condruilion in his mod valuable ex- 
 periments on the force of gravity (Phil. Tranf. 1798, 
 Part 11.); an experiment wiiich Newton would have 
 been delighted with obferving. 
 
 Ciithlerlfon's EifcrKOME-TRR is thus defcribed by 
 himfelf in the lad number of the fecond volume of Nt- 
 cho/fon's Ph'ilofophkal Journal. GH (fig. 6.) is an 
 oblong piece of wood, about 18 inches in length and fix 
 in breadth, in which arc fixed three glafs liipporters, 
 D, E, F, mounted with brafs balls, a, c, b. Of thefe 
 fupporters E and F are cxaftly of the fame length ; 
 but D is four inches diortcr. Under the brafs ball a 
 is a long brafs hook ; the hnll c is made of two hemi- 
 fpheres, the under one being fixed to the brafs mount- 
 ing, and the upper turned with a groove to duit upon 
 it, fo that it can be taken off at pleafure. The ball b 
 has a brafs tube fi.xed to 4t, about three inches long, 
 cemented on the top of F, and the fame ball has a hole 
 at the top, of about one-half inch diamater, correfpond- 
 ing with the infide of the tube. AB is a draight brafs 
 vyire, with a knife-edged centre in the middle," placed a 
 little below the centre of gravity, and equally ba!ance<! 
 with a hollow brafs ball at each end, the centre, or 
 axis, reding upon a proper (haped piece of brafs fixed 
 in the infide of the ball c ; that fide of the hemifpherc 
 towards c is cut open, to permit the end c A of the ba- 
 lance to defcend till it touches the ball a, and the upper 
 hemifphere C is alfo cut open to permit the end c B to 
 afcend ; /' \s a weight, weighing a certain number of 
 grams, and made in the form of a pin with a broad 
 head ; the ball B has two holes, one at the top, and the 
 other at the bottom ; the upper hole is fo wide, as to 
 let the head of the pin pafs through it, but to dop at 
 the under one, with its diank hanging freely in b ; i is 
 a common Henley's quadrant eleihometer; and when in 
 ufe it is fere wed upon the top of r. 
 
 It is evident, from the condruftion, that if the foot 
 dand horizontal, and the ball 15 be made to touch b, it 
 will remain in that pofition without the help of the 
 weight ;■ ; and if it diould by any means receive n very 
 low charge of eleftric fluid, the two balls b, B, will re- 
 pel eachoiner ; B will begin to afcend, and, on account 
 of the centie of gravity being above the centre of mo- 
 tion, the afcenfion will continue till A red upon n. If 
 the b.dance be fet again horizontal, and the pin i be 
 put into its place in B, it will caufe B to red upon b, 
 with a predurc equal to that weight, fo that more elec- 
 tric fluid mud be communicated than formerly before 
 the balls will feparate ; and as tiie weight iu B is increa- 
 fed or diminifhed, a greater or lefs quantity of eleiflric 
 fluid will be required to ed'ecl a feparatioii. 
 
 When this indrument is to be applied to a jar, or 
 battery, one end of a wire L mud be inferted into a. 
 hole in b, and the other end into a hole of any ball pro- 
 ceeding from the infide of a battery, as M. A chain, 
 or wire, or any body through which the charge is to 
 pafs, mud be hung to the hook at m, and carried from 
 thence to the outfide of the battery, as is reprefented 
 by the line N. i mud be fcrewed upon c, with its in- 
 dex towards A. The reafon of this indrument being 
 added, is ta diew, by the index continuing to rife, that 
 the charge of the battery is increafing, becaufe the 
 
 other
 
 E L E [62 
 
 !Elcfli ome- other part of the iiiftrument does not aft till the battery 
 has received its rccjuircd charge. 
 
 It is almoft needlcfs to obferve that this inftrument 
 coiifiih of three ekftrometers, viz. Henley's elcflrome- 
 ter, Lane's difi:lnrging electrometer confiderably im- 
 proved, and Brookts's lletlyard eleClronieter improved 
 likewife. By this combination and thele improvements, 
 we pofTcis ail that can be required in an eleftromcter 
 •for batteries and large jars ; for, by /?■, we fee the pro- 
 grefs of the charge ; by the fcpavalion of B b, we have 
 the repullive power in weight ; and by the ball A, the 
 difcharge is caufed when the charge has acquired the 
 ilrcnglh propofcd. 
 
 Ill the journal from which this abflraft is taken, the 
 reader will find fome curious experiments made with 
 batteries by means of this eKclrometer ; but one will 
 be fufiicltnt to explain its ufe. Prepare the eledho- 
 meter in the manner (hewn in the figure, wiihthejar 
 M annexed, which contains tbout i6;> fquare inches of 
 .coating. Take out the pi;i in B, and obferve whether 
 the ball B will remain at reft upon b; if not, turn 
 the adjulling fcrew at C till it juft remains upon A. 
 Put into B the pin, marked/, weighing 15 grains; 
 take two inches of watch-pendulum wire, fix to each 
 end a pair of fpring tongs, as is rcprtfented at G m, 
 -hcok one end to m, and the other to the wire N, com- 
 tRunicating with the outfide of the jar; let the uncoat- 
 ed part of the jar be made very clean and dry ; and let 
 the prime condutlor of an eleiftrical machine, or a wire 
 proceeding from it, touch the wire L ; then, if the ma- 
 chine be put in m.otion, the jar and eleftrometer will 
 charge, as will be feen by the rifing of the index of i ; 
 and when charged high enough, B will be repelled by 
 b, and A will defcend and dilcharge the jar through 
 the wire which was confined in the tongs, and the wire 
 will be fufed and run into balls. The ingenious author, 
 by breathing through a glafs pipe into the jar, damped 
 it a little in the infide. Then loading B with a pin of 
 30 grains, he obtained fuch a charge as fufed eight 
 inches of watch pendulum wire, difpoied exaftly as the 
 two inches were difpofed In the former experiment. By 
 repeating and varying his experiments, he found that 
 ■ double quantities of eleftrical fluid, in the form of a 
 difcharge, will melt four times the length of wire of a 
 certain diameter. 
 
 ELECTROPHORUS. See Electricity in this 
 
 Slipplt'ment. 
 
 ELEPHAS, the Elephant. See Encyclopurlia ; 
 where the natural hiflory of this huge and fagacious 
 animal is detailed at confiderable length. Since that 
 article was publilhed, we have feen the third volume of 
 the Afiatic Refcarches, in which fome important quef- 
 tions, which we were then obliged to leave in uncer- 
 tainty, feem to be decided by John Corfe, Efq. They 
 relate, 17?, To the mode in which elephants copulate ; 
 which Buffon aflerts (and in proof of his aflertion ad- 
 duces the ftrufture and pofition of the generative organ 
 in the female) to be performed while that female re- 
 mains recumbent on the back ; but which Mr Coile in- 
 fills from ocular evidence, takes place alter the manner 
 in which the horfe copulates with the mare. 2(1, To 
 the method of receiving nouridiment from the mother ; 
 which is not, as Buffon avers, by the trunk, but by the 
 mouth, which fucks the dug, while the trunk of the 
 young aninjal grafps it round to prefs out the milk. 
 ^(L, To the period of their going with young ; which 
 
 ] 
 
 ELL 
 
 Mr Corfe conceives cannot be lefs than two y?ars ; Elcjluntl 
 whereas Buil'on and Pennant affigu only nine months 
 for the gcfldtion of their voung. His reafons for this 
 fuppofition are unanfwerable, and (hall be given in his 
 own words. 
 
 " As far as I know, the exaft time an elephant goes 
 with yoLiug Ins not yet been afcertaiued ; but it cannot 
 be Icfs than two years, as one of the elephants brought 
 forth a young one, twenty one montiis and three days 
 after (he was taken. She was obferved to be with 
 young in April or May 1788, and (he was only taken 
 in January preceding ; fo that it is very likely (he mull 
 have had connection with the male fome months before 
 Hie was fecuied, othei-wifc they could not have difco- 
 vcred tiiat (he was with young, as a fcetus of lefs than 
 fix months cannot well be fuppofed.to make any alte- 
 ratif)n in the fize or f.iape of fo large an animal. The 
 young one, a male, was produced Ottober 16, 1789, 
 and appeared in every refpett to have arrived at its full 
 time. The gentleman to whom it belongs examined 
 its mouth a few days after it was brought fortli, and 
 found that one ot its grinders on each fide had partly 
 cut the gum." 
 
 When Mr Corfe wrote his memoir, the young ele- 
 phant was at^ve and well, and beginning to eat a little 
 grafs. In Africa the Hottentots feed on the elephant ; 
 and M. Vailant declares, that an elephant's foot, when 
 baked in their manner, is a moft delicious morlel. 
 
 ELEPHANTIASIS (fee Medicine, n" 352. En- 
 cycl ) is one of the moft dreadful maladies with which 
 the human race is anywhere a(Bi(Eled. It is not indeed 
 common, if it be found at all, iu the temperate climates 
 of Europe ; but it is frequent in the Eaft and Weft In- 
 dies, where it too often baffles the fkill of the ablell 
 phyficians. In the fecond volume of tlie Afiatic Re- 
 fearches we have the following prefcriplion for its cure : 
 
 " Take of line frefti white arfenic one tola, or 105 
 grains ; of picked black pepper fix times as much : let 
 both be well beaten at intervals for four days fuccelllve- 
 ly in an iron mortar, and then reduced to an impalpa- 
 ble powder in one of ftone with a ftone peftle, and thus 
 completely levigated, a little water being mixed with 
 them. Make pills of them as large as tares or fmall 
 pulfe, and keep them dry in a (hady place. One of 
 thofe pills muft be fw allowed morning and evening with 
 fome betel leaf, or in countries where betel is not at 
 hand, with cold water : if the body be cleanfcd from 
 fouhiefs and obftrudlions by gentle cathartics and bleed- 
 ing before the medicine is adminiftefed, the remedy will 
 be fpecdier." 
 
 This prefcription, we are told, is an old fecret of the 
 Hindoo phyficians, which they confider as a powerful 
 remedy againft all corruptions of the blood, whether 
 occafioned by the elephantiafis or the venereal difeafe, 
 which they call the Pcrfian fire, and which they apply 
 likewife to the cure of cold and moift diftempers, or 
 palfy, diftortions of the face, relaxation of the nerves, 
 and fimilar difeafes. As the Hindoos are an ingenious 
 and fcientific people, it might be worth fome European 
 phyfician's while to make trial of this ancient medicine 
 in the Weft Indies, where the elephantiafis or kindred 
 difeafes prove fo frequently fatal. 
 
 ELEVATION, in architecture, denotes a draught 
 or defcrlption of the principal face or fide of a building ; 
 called alfo its upright or orthography. 
 
 ELLIPSE, or Ellipsis, is one of the conic fec- 
 
 tionsj
 
 Ta^ECTJlfrME-El^K . ELVTi: JQCVH
 
 E N A [6 
 
 tions, popularly called an oval ; being called an elUpfe 
 or ellipjis by Apollonius, the firft and principal author 
 on the conic ieftions, btcanfe in this figure the fqiiares 
 of the ordinates are IcJ's than, or dcfcillvs of, the rec- 
 tangles under the parameters and ablciiTes. See Conic 
 ScSions, Encycl. 
 
 ELLIPSOID, is an elliptical fpheroid, being the 
 folid generated by the revolution of an ellipfe about 
 either axis. 
 
 ELLIPTOIDE, an infinite or indefinite ellipfis, de- 
 fined by the indefinite equation ay'"'^" = i»".a — .\" 
 when m or n are greater than i : for when they are 
 each = I, it denotes the common ellipfe. 
 
 There are feveral kinds or degrees of elliptoides, de- 
 nominated from the exponent m -{- n of the ordinate y. 
 As the cubical elliptoide, exprefled by ay^ ^ b .■«* 
 .(/ — .V ; the biquadratic, or furfolid ay^ = 3.v'.a — .t' ; 
 Ccc. 
 
 EMINENTIAL equation, a term ufed by fome 
 algebrairts, in the inveiligation of the areas of curvili- 
 neal figures, for a kind of afi'umed equation that con- 
 tains another equation eminently, the latter being a par- 
 ticular cafe of the former. 
 
 ENAMELLING of Vessels for the Kitchen. 
 In the year 1779 the Society of Emulation in Paris 
 propofed as a prize, queftion, " To difcover a compofi- 
 tion -fit for making kitchen utenfils which fhould be 
 free from the difadvantages attending copper, lead, tin- 
 ned veflels, glazed earthen-ware, &c. which fhould be 
 as ftrong as.pofiible, lefs coflly than the veffels ufed at 
 prcfent, and which fhould be able to bear the highell 
 degree of kitchen fire, and the mod fudden changes 
 from heat to cold." 
 
 In confequence &f this propofal, Mr Sven Rinman of 
 the Royal Academy of Stockholm, without any inten- 
 tion of being a candidate for the premium offered by 
 the Society of Emulation, inftitutcd a fct of experi- 
 ments on imall velTels of copper and hammered iron, 
 with the view of giving to them a coating of what 
 may properly be called enamel, which fiiould not have 
 the defefts of tinning, and which, when applied to iron, 
 fhould take from it the inconveniency of rulling, and 
 of blackening many forts of viduals when they are 
 dreffed in it. Thefe experiments he fubmltted to the 
 academy, of which he v/as a member ; and as we think 
 them important, we fiiall lay the fubftance of them be- 
 fore our readers. 
 
 The mod common, and the cheapeft, kind of white 
 fnamel that is to be met with in the fliops (which is an 
 opaque white glals, compofed of powdered quartz, of 
 gliifs of lead, and of calx of tin), was tried for coat, 
 inp kitchen-utenfils ; and he found that it was excellent- 
 for the purpofe, as It produced a coating, which was 
 not only clean and agreeable in its appearcnce, but pof- 
 fefied llkewife all the power of refilling the attlon of 
 fire and of acids that could be defired. But, as it is 
 •very difficnk to apply, is very dear for common ufe, 
 and is belides coiilidered as not being capable of refid- 
 ing violent blows or falls, he made various experiments 
 with fubdances of lefs price; of which the following are 
 certainly worthy of being related. 
 
 I. The white feml-tranfparent fluor fpar was reduced 
 into a fine powder, with an equal quantity of unburnt 
 gypfum, and afterwards calcined in a drong fire with a 
 •white heat ; the whole being, from lime to time, care- 
 
 23 ] E N A 
 
 fully dirrcd. The vefTel which he inten ded to coat, Enamel- 
 having fird been wetted by dipping it in water, had as '^' 
 much of the aforefaid powder applleil to its infide, by ' 
 means of a very fine filk fieve, as would ailhere to it of 
 itfelf, or could be made to do fo by prtfTing it with 
 the finger. After this vefTcl had been dried and gra- 
 dually heated, it was expofcd to a fudden and violent 
 heat, partly in a coal-fire, kept up by a jiair of l)ellows 
 (the veffel being at the fame time covered, fo that no 
 coals or afhes could fall into it), and partly in an affay- 
 ing furnace. 
 
 In the coal- fire, and with a heat as violent as is com- 
 monly ufed to make copper-folder run, the mixture was 
 melted, in about the fpace of a minute, into an opaque 
 white enamel, which evenly covered the furface of the 
 copper, and fixed itfelf pretty firmly to the metal ; it 
 alfo bore hard blows without breaking, and refided the 
 trials made by boiling things in it, and by applying 
 acids to it. The forementloned mixture was alfo rcdii- 
 ced into a fine powder in a glafs mortar, and made into 
 a fort of thin pade with water ; it was then applied to 
 the velTel with a fmall brufli, an operation as eafy as 
 that of applying any other wet colouring matter. He 
 llkewife tried this parte, by covering veflels with it in 
 the fame way the potters apply their common glazing 
 for done-ware. By botli the above-mentioned procelTes 
 he obtained a very fmooth coating, particularly by the 
 latter, which is more quickly performed. When the pafle 
 is applied, the veffel fliould be made a little warm, fo 
 alfo fhould the pade itfelf. 
 
 If the conditueiit parts of thefe two fubdances be con- 
 fidered (that is to fay, that gypfum is compofed of calca- 
 reous earth faturated with vitriolic (fulphurlc) acid, and 
 fluor fpar of a particular acid united to filiceous earth ; 
 alfo, that the whole, when put into the fire without the 
 addition of any other fubftance, is, of all earthy or llony 
 mixtures, that which the mcll eafily melts into an o- 
 paque white glafs, not very brittle), and if, on the 
 other hand, the aAion of acids be attended to — we fliall 
 eafily conceive thefe fubdances mud attach thenifelves 
 droiigly to copper, and that the varnlfh formed by them 
 cannot afterwards be dlllolved or afted upon by acids. 
 
 The greated difficulty attending on this finiple mix- 
 ture is, the drong and fudden heat neceffary to apply It 
 with effect, that heat being greater than Is commonly 
 to be obtained in an alfaying furnace. On that ac- 
 count, M. Rinman endeavoured to render it more fu- 
 fible by the addition of fome other fubftance. 
 
 Of his experiments made with this view, fome failed, 
 and others fucceedcd. We fliall record only futh as were 
 f'uccefsful, and at fame time attended with fuch mode- 
 rate expence as not to preclude them from commiiu ule. 
 
 2. With the fubdances employed in his liril expeii- 
 ment, which, with the author, we lliall henceforth ciiU 
 n** I. he mixed an equal quantity of what is called /«- 
 Jible glafs (•uitriim fujiblh), compofed of fix parts of 
 lime, four of fluor fpar, two of quartz reduced into a 
 fine powder, and one tenth of a part of manganefe ; 
 the whole having been calcined, and ground with wa- 
 ter in the manner colours are ground, he fpread it on 
 the vefi'el with a brufh. This mixture ran pretty well 
 upon the copper in the coal fire ; it alfo attached itfelf 
 very drongly to it, and produced au enamel which was 
 firm and hard, and feemed likely to bear wear; but. 
 it was of a dark grey colour, auJ without any brillian-
 
 ■ U.10-. 
 
 E N A [62 
 
 cy. The mixture did not melt more readily in the af. 
 faying furnace. 
 
 Two parts of n" i. with one part of the fufible glafs, 
 and a quarter of a part of tnanganefe, had nearly the 
 fame efteft. This lall mixture, indeed, was rather more 
 eafily milted, but it had a darker colour. 
 
 3. Eight parts of n^ I. with one half of a part of 
 borax, one quarter of a part of nitre, and half a part 
 of manganefe, were melted, in the fpace often minutes, 
 into a brown liver-coluured glafs ; which, in the af- 
 faying furnace, produced upon the copper veflel a black 
 enamel, wiiich had a dull furface. In other refpefts it 
 was firm, evt-n, and hard; but it did not fufficiently co- 
 ver the vtfTel by a fingle application, nor was it capable 
 of refilling the acllon of acids. 
 
 4. One part ot the brown glafs mentioned in the laft 
 experiment, with three parts of n" 1. became in the 
 affaying furnace with a red heat, almoll as fluid as the 
 laft, and held an even and fmooth furface; but it was of 
 a dark colour, and had not any brilliancy. It was not 
 fenfibly afled upon by vitriolic (fulphuric) acid. 
 
 5. Four parts of n° 1. mixed with one half of a part 
 of litharge, were melted in a crucible, with the help of 
 the bellows, in five minutes, fo as to become as fluid as 
 ■water. This mixture, during the fufion, emitted a 
 fmell of fulphureous acid, and formed an opaque glafs 
 of a ftraw colour ; which, after being ground, as ufual, 
 and fpread upon a copper veflel, produced an enamel 
 which covered the veflel very evenly, and was with- 
 out bubbles. It was likewifc, perhaps, the hardeft of 
 all, but could not be melted in the aflaying furnace, 
 requiring a ftronger fire kept up by the bellows. It 
 preferved its ftraw colour, but without any lullre, and 
 refifted the aftion of acids better than the cunimon gla- 
 zing of the potters. 
 
 6. Mr Rinman mixed together equal quantities of 
 gypfum, fluor fpar, and what the potters call rvh'ile 
 hod (a,), and which frves for the bafis of their glazing. 
 This mixture, after being calcined, melted in five mi- 
 nutes, with the afliftance of a pair of bellows, into a 
 very white, hard, and opaque enamel, which was very 
 eafily poured out of the crucible. This enamel, treat- 
 ed like the others, ran very freely, equally, and with- 
 out bubbles, by the heat of the affaying furnace. It 
 was alfo pretty hard and ftrong, but without any luftre, 
 and had green and yellow fpots, occafioned by the acids 
 of the gypfum and flour fpar, which had afted upon 
 the copper during the fufion of the enamel. It, how- 
 ever, bore melting two or three times, and then ap- 
 peared 01 a white colour ; it was but very little affefted 
 by other acids. 
 
 7. Equal parts of fluor fpar, of gypfum, of litharge, 
 and of pure flinc glafs, powdered and mixed together, 
 melted in five minutes, by the help of a pair of bellows, 
 and produced a wliite and hard glafs, very like that of 
 the laft experiment, but rather harder. After being 
 applied on the veflel in the ufual manner, it formed, 
 with the greateft heat of an aflaying furnace, an ena- 
 mel of a yellowifli white colour, firm and hard, but 
 without luftre. In order to avoid the formation of 
 bubbles, care was taken (as ought always to be done 
 
 4 ] E N A 
 
 in enamelling) to remove the veflel from the (ire aa foon EnaireU 
 as it had acquired a brilliant appearance therein, or as ''"?• 
 foon as the enamel was completely melted. •f"^ 
 
 8. Twelve parts of glafs uf lead, or of litharge, with 
 eight parts of flint glafs, and two of flowers of zir.c, 
 were melted, in the fpace of feven minutes, into a clear 
 yellow glafs, which, when ufed for enamelling, was dif- 
 pofed to form bubbles; but, by continuing the heat for 
 
 a longer time, the bubbles were difperfed, and be ob- . 
 tained a pretty good enamel, of a yellow brown colour 
 with a green illi caft, very hard and firm. It refifted 
 the aftion of the vegetable acids, like the enamels al- 
 ready fpoken of, but it was a little attacked by the mi- 
 neral acids. 
 
 9. He powdered and mixed together five parts of flour 
 fpar, five parts of gyplum, two parts of minium, one 
 half of a part of borax, two parts of flint glafs, one half 
 of a part of calx of tin, and only one twenty- fifth of a 
 part of calx of cobalt. This mixture was melted in a 
 crucible in fix minutes, by help of the bellows, and pro- 
 duced an opaque glafs of a pearl colour, a little incli- 
 ning to blue, on account of the calx of cobalt. It 
 was pretty hard, and, after being ground with water 
 in the ufual way, it became of a very good confiftence, 
 fo as to be very fit for fpreading over veflcls, to which 
 it adhered very ftrongly. If any bubbles formed on 
 the veflel during its drying, they might be rubbed down 
 with the finger, and the whole furface rendered fmooth 
 and even. After being warmed, and gradually heated, 
 it was put into an aflTaying furnace made very hot with 
 birch charcoal, which had been juft kindled under the 
 muffle. After a minute it melted, and began to appear 
 brilliant ; fo that he found it neceflTary to take out the 
 velTel very quickly, which was already very evenly coat- 
 ed with a thick, and fufficiently hard, enamel, the fur- 
 face of which, however, had no brilliancy. 
 
 The colour remained always inclining to green, be- 
 caufe the copper had been a little attacked by the acids 
 of the gypfum and flour fpar during the fuiiun ; but 
 in other refpefts this enamel was very firm, was very 
 little hurt by flight blows, and bore very well fudden 
 changes of heat and cold. Weak acids had no action 
 upon it; but he had fomc reafon to think that it would, 
 in length of time, have been afted upon, to a certain 
 degree, by vitriolic (fulphuric) acid. Its colour, ex- 
 cept the forementioned fliade of green, was white, with 
 a dull, and rather changeable furface. 
 
 The calx of cobalt which has been juft mentioned, 
 and which Mr Rinman made ufe of merely with the in- 
 tention of obtaining a fine colour, was prepared by fa- 
 turating a folution of cobalt in aquafoitis (nitric acid) 
 with common fait, and evaporating to dryncfs ; by 
 which means he obtained a fine rofe-eoloured calx. . A 
 very fmall quantity of this calx, when mixed with any 
 fufible glafs, gives it a beautiful blue colour. 
 
 Of the various fpecies of enamel, which had been 
 defcribed in the courfe of thefe experiments, and which 
 may be all applied, with more or lefs advantage, to 
 kitchen utenfils, the leaft expenfive are n°' i, 2, and 
 5 ; but they are alfo thofe which require the greateft 
 heat. On the other hand, n" 9. may be recommended 
 
 as 
 
 (a) This fubftance is itfelf a mixture, being compofed of four parts of lead and one of tin.
 
 E N A [6 
 
 Enamel- as the mod eaTy of fiifion, and, at the fam« time, very 
 '"'S- durable when ulVd for coating veflels in which viftuals 
 • are to be drcflcd, vvlitch is here the principal objeft, and 
 
 is of far greater importance than the brilliant appear- 
 ance refuking from the enamel generally ufed by artifts, 
 which however may be employed when the faving of 
 expence is not regarded. 
 
 The enamels hitherto dcfcribed are not applicable to 
 velFcls made of iron, though they may be employed to 
 cover copper with great advantage. Iron will not in- 
 deed bear the common praftice of enamellers, namely, 
 to be put into the fire and taken out again feveral times ; 
 for the fparks which fly from iron, when in a hot 
 •fire, detach and carry off the enamel from the parts 
 contiguous to thofe where the fparks are formed. The 
 acids, too, of the gypfum and fluor fpar, made ufe of 
 in the enamels already mentioned, afied upon the iron 
 during the fufion of the enamel, from which refulted 
 bubbles and bare fpots, which entirely fpoiled the ap- 
 pearance of the work. Our author therefore continu- 
 ed his experiments with a view to difcover a proper 
 enamel for vefTcls made of this metal. 
 
 10. He reduced into a very fine powder, and ground 
 together, nine parts of minium (red oxide of lead), 
 fix parts of flint glafs, two parts of pure potalh, two 
 parts of purified nitre, and one part of borax. This 
 mixture was put into a large crucible, which it only 
 half filled ; he covered the crucible fo that no coals 
 could fall into it, and gradually increafed the fire under 
 it. When the effervefcence had entirely ceafed, he 
 caufed the mixture to melt, by ufing the bellows for 
 four or five minutes ; by thefe means he obtained a 
 clear and compaft glafs, which he poured out of the 
 crucible upon a piece of marble. Having quenched it 
 in water, and reduaed it to a very fine powder in a 
 glafs mortar, he ground it with water to the confiftence 
 of a very thin pafte. He then covered an iron vefTel 
 with it on both fides, which, after having dried and 
 heated it by degrees, he put under a muffle well heated 
 in an aflaying furnace. The enamel melted very readily 
 in the fpace of half a minute, and with a very brilliant 
 appearance. He immediately withdrew the veffel, and 
 let it cool : it was found to be entirely coated with a 
 beautiful enamel of a black colour ; which colour ap- 
 peared to be caufed by a thin layer of calcined iron, 
 which might be feen through the traufparcncy of the 
 enamel. 
 
 A copper vetTel having been covered wit-h the fame 
 enamel, the fine colour of the copper was vifible through 
 the thin coat of glafs ; and it was as well defended from 
 ruft by this coating as it would have been by an enamel 
 of a llronger kind. 
 
 11. To hinder the colour of the metal from being 
 feen through the coating, he added to the mixture, ufed 
 in the preceding experiment, only one hundredth part 
 of the calx of cobalt dcfcribed in n° 9. The whole 
 was melted into a beautiful blue glafs ; it was prepa- 
 red for enamelling, and applied in the manner before 
 defcribed, upon another iron vefTel. The enamel pro- 
 ved to be fmooth, thick, and brilliant, like the prece- 
 ding, but it covered the veffel more perfectly ; it was 
 of a fine blue colour, with fome black fpots in thofe 
 parts where it had been mofl thinly applied. 
 
 12. The glafs of n" 10. reduced into powder, and 
 ground with potters white lead, of which mention has 
 
 Sup-PL. Vol. I. Part II. 
 
 25 1 E N F 
 
 already been made, melted with the fame facility ; it 
 produced a very (inooth enamel, of a grey colour, but 
 move firm and hard than the former, and, on ^iccount of 
 the addition made to it, ot a flill lefs price. By mixing s 
 with the fame glafs a fmall quantity of crocus martis, he 
 oljtaincd a very fine enamel, oi a dark red colour, not 
 to mention other colours in it ilill more beautiful. The 
 crocus martis he ufod in this experiment was prepaud 
 from a folution of iron in aqua rcgia (nitroniuriatic 
 «cid), which was evaporated todryneis, and the matter 
 thus edulcorated and calcined. 
 
 13. In order to render the forementioned enamel 
 more folid, and to give it what is called body, he melt- 
 ed together a mixture of twelve parts of flint glafs, 
 eighteen parts of minium, four parts of potafh, four 
 parts of nitre, two parts of borax, three jtarts of calx 
 of tin, and one eighth part of calx of cobalt, obfcrving 
 always the uiual precautions. He obtained a glafs of 
 a light blue colour, which, after having been ground 
 with water, and fpread upon fmall iron bafins, or tea 
 cups, produced, by means of a briflc fire in an afTiying 
 furnace, an enamel which was fmooth and even, and ot 
 a pearl colour. The coating was of a proper thicknef?, 
 to obtain which requires a certain degree of dexterity 
 and praftice. He alfo tried to paint upon this enamel 
 with what is called mineral purple (purpura miiienili.! ) , 
 which he ufed with a little powdered quartz, nitre, and 
 borax ; it produced a very beautiful red colour. 
 
 Though this lafl: mentioned compofition is more beau- 
 tiful when applied upon iron, and more even than the 
 preceding, it has the difadvantage, on account of the 
 lalts which it contains, of not refilling the aftion of the 
 flronger vegetable acids, and flill lels that of the mine- 
 ral ones. l)Ut as a vefTel when coated with this ena- 
 mel bears, without any injury, fudden changes of heat 
 and cold, and alfo to have any greafy mixtures baked 
 or boiled in it (even thole which are of a caullic alka- 
 line nature, or thofe which contain the ufual weak acids 
 which are ufed in the preparation of our food), it may 
 be applied to veflels of various kinds, among others, to 
 tea cups ; particularly as it is neither brittle nor fub- 
 jeft to crack, provided it is not expofed to violent 
 blows. It is hardly neceffary to fay, that this enamel 
 can only be applied upon veffels made of hammered 
 iron, and not upon thofe of call iron, thefe laiT being 
 always too thick to be healed with fufficient quicknels; 
 for the greater is the fpace of time neceffary to make 
 the vefTels red hot, the greater is the quantity of fcalcs 
 formed upon them, and, of courfe, the enamel becomes 
 more injured. 
 
 Our author makes fome other judicious obfervations 
 on the enamel for iron, of which he has defcribed the 
 compofition, and fays, that, independent of its ufe for 
 coating kitchen utenfils, it might be made to ferve 
 many other purpofes, fuch as preferving thinars made 
 of that metal, not only from ruft, but alfo, as he proved 
 by experiment, to a certain degree, from calcination. 
 
 ENCAUSTIC Painting. See Painting in this 
 Supplement. 
 
 ENFIELD (William, L. L. D.), well known In 
 the learned world by feveral ufeful and elegant publi- 
 cations, was born at Sudbury, on March 29. O. S. 
 I'74i, of parents in a humble walk of life, but of very 
 refpeftable charaflers. His amiable difpofition and 
 promifing talents early recommended him to the Rev. 
 4 K Mr 
 
 ling 
 
 II 
 Enfi'ld.
 
 E N F 
 
 [ 62 
 
 Er.fieM. Mr Hextall, the difienting minider of lliat place, who 
 ^~^ took great care of his education, aii<i infulid into his 
 
 young mind that tafte for elegance in compofition which 
 ever afterwards diltinguilhed iiini. 
 
 In his i-th year he was fcnt to the academy at Da- 
 ventry, then under the direction of the Rev. Dr Alh- 
 worth, where he pafTed through the ufiial courfe of in- 
 ftrudion preparatory to the office of the miniftry ; and 
 with fuch fuccefs did he cultivate tlie talents of a 
 preacher, and of an amiable man in fociety, that, on 
 leaving the academy, he was at once chofen, in 1763, 
 miniftei of the very refpeftable congregation of Benn's 
 Garde 1 in Liverpool. 
 
 In thit agreeab'e town hepafied i^even of tlie happieft 
 years of his life, very j.t -.lernlly beloved and eftcemcd. 
 He married, in 1767, the daughter of Mr Holland dra- 
 per in Liverpool, with whom he pafled all the reft of 
 his chys in mod cordial union. His literary reputation 
 ■was es'tended, during his rtfidence in this place, by the 
 publication of two volumes of fermons, wliich were very 
 well ri-ceived, and have ferved to grace many pulpits 
 befides that in which they were originally preached. A 
 colleftion of hymns and of family prayers, which he 
 alfo publifhed at Liverpool, did credit to his tafle and 
 judgment. 
 
 About 1770, he was invited to take a (hare in the 
 conduft of the academy at Warrington, and alfo to oc- 
 cupy the place of minifter to the diffenting congrega- 
 tion there, both vacant by the death of the Rev. Mr 
 Seddon. His acceptance of this honourable invitation 
 was a fource of variety of mixed fenfations and events 
 to him, of which anxiety and vexation compofed too 
 large a fhare for his happinefs. No affiduity on his 
 part was wanting in the performance of his various du- 
 ties ; but the difeafes of the inllitution were radical and 
 incurable ; and perhaps his gentlenefs of temper was ill 
 adapted to contend with the difHculties, in matter of 
 difcipline, which feem entailed on all diffenting acade- 
 mies, and which, in that fituation, fell upon him, as the 
 domeftic refident, with peculiar weight. lie always, 
 however, pofreifed the refpeft and affeftion of the beft 
 difpofed of the ftudents ; and there was no reafon to 
 fuppofe that any other perfon, in his place, could have 
 prevented that diflolution which the' academy urider- 
 
 went in 178^ 
 
 During the period of his engagement there, his 
 indefatigable induftry was exerted in the compofi- 
 tion of" a number of works, moftly, indeed, of the 
 clafs of ufeful compilations, but containing valuable dif- 
 plays of his powers of thinking and writing. The mod 
 confiderable was his " Inflitutes of Natural Pliilolo- 
 phy" (quarto, Johnfon, 1783) ; a clear and well-anan- 
 ■Tgd compendium of the leading principles, theoretical 
 and experimental, of the fciences comprifed under that 
 head. ' And it may be mentioned, as an extraordinary 
 proof of his diligence and power of comprchenfion, 
 that, on a vacancy in the mathematical department of 
 the academy, which the ftate of the inftitution render- 
 ed it impofTible to fupply by a new tutor, he prepared 
 himfelf, at a fhort warning, to fill it up ; and did fill it 
 with credit and utility, though this ablfrufe branch of 
 fcience had never before been a particular objedt of his 
 iludy. He continued at Warrington two years after the 
 academy had broken up, taking a few private pupils. 
 
 In 1785, receiving an invitation from the principal 
 
 6 ] E N F 
 
 diffenting congregation at Norwich, he accepted it, ErficM. 
 and lirfi. fixed his refidence at Thorpe, a plealant vil ^~~V—" 
 lage near the city, where he purfued his plan of taking 
 a limited number of pupils to board in his houfe. He 
 afterwards removed to Norwich itlclf ; and, at length, 
 fatigued with the long cares of education, entirely cea- 
 fcd to receive boarders, and only gave private inftruc- 
 tions to two or three feledt pupils a few hours in the 
 morning. This too he at lall difcontinued, and devo- 
 ted himfelf folely to the duties of his congregation^ and 
 the retired and independent occupations of literature. 
 Yet, in a private way and fmall circle, few men had 
 been more fiiccefsful in education, of which many Itri- 
 king examples might be mentioned, and none more fo 
 than the members of his own family. Never, indeed, 
 was a father more dciervedly happy in his children ; but 
 the eldeft, whom he had trained with uncommon care, 
 and who had already, when juft of age, advanced in his 
 profeffional career fo far as to be chofen town-clerk of 
 Nottingham, was moil unfortunately fnatched away by 
 a fev'er a few years fince. 
 
 This fatal event produced effefts on the dodlor's 
 health which alarmed his friends. The fymptoms were 
 thofe of angina peSoris, and they continued till the ufual 
 ferenity of his mind was rcftored by time and employ- 
 ment. Some of the laft years of his life were the moft 
 comfortable : employed only in occupations which were 
 agreeable to him, and which left him matter of his own 
 time ; witnefiing the happy fettlement of two of his 
 daughters ; contradled in his living within the domellic 
 privacy wiiich he loved ; and connefled with fome of 
 the moft agreeable literary companions, and with a fet 
 of the moft cordial and kind-hearted friends that per- 
 haps this ifland aflovds, he leerned fully to enjoy lite as 
 it flowed, and indulged himfelf in pleaiing prolpefts for 
 futurity. Alas ! an unfufpefted and incurable dlfeafe 
 was preparing a fad and fudden change : a fchirrous 
 contradtion of the reftum, the fymptoms of which were 
 miftaken by himfelf for a comm.on laxity of the bowels, 
 brought on a total ftoppage, which, after a week's 
 ftruggle, ended in death. Its gradual approach gave 
 him an opportunity to difplay all the tendernefs, and 
 more than the ufual firmncfs of his nature. He died 
 November 3. 1707, amidlt the kind offices of mourn- 
 ing friends, and his laft hours were peace ! 
 
 Befides the literary performances already mentioned, 
 Dr Enfield completed, in 1791, the laborious taflv of 
 an abridgment of " Brucker's Hiflory of Philofophy," 
 which he comprifed in two volumes quarto. It may 
 be truly faid, that the tenets of philofophy and the 
 lives of its profeffors were never before dilplayed in fo 
 pleaiing a form, and with fuch clearnefs and elegance 
 of language. Indeed it was his peculiar excellence to 
 arrange and exprefs other mens ideas to the utmofl ad- 
 vantage. Perhaps, at the time of his deceafe, there 
 was not in England a more perfeft mafter of what is 
 called the middle ftyle in writing, combining the qua- 
 lities of eafe, elegance, perfpicuity, and corredlnefs, en- 
 tirely free from afFeftation and iingularity, and fitted for 
 any fubjeft. If his caft of thought was not original, 
 yet it was free, enlarged, and manly. What he was in 
 the capacity of a teacher of religion, his feveral congre- 
 gations will teftify with grateful and affeftionate re- 
 merabrance. Few miniflers have paid fuch unremit- 
 ting attention to the perfection of their pulpit compo- 
 
 fitions ;
 
 E N G 
 
 fitions ; nor was it only by detached difcourfes that he 
 iiiculcateJ the truths of morality and religion, hut by 
 methndical plans of inftrudion, drawn up \t'ith great 
 <care and comprehcafion. The valuable llores of this 
 kind which he left behind him will not be coiifigned 
 to oblivion ; but, it is hoped, will iirform ami improve 
 numbers to whom the voice of the preacher could never 
 have extended. In delivery, his manner was grove and 
 imprtfllvc, depending rather on the weight of jull enun- 
 ciation than on the arts of oratory. Little need be 
 added to this (ketch of the moral qualities of the excel- 
 lent man above commemorated. If moderation, com- 
 
 [ 627 1 
 
 E P I 
 
 of Orang^ee and Lemons or Citrons, whereby is proJu- Enncalec*- 
 ced an individual Fruit, half Orange and half I^emon, .. 
 
 growing together as one Body upon the fame Tree." Scotch 
 We have here orange trees (faith the intelligence E|Mfc .(la- 
 from Florence) that bear a fruit which is citron on one ''•' ""• 
 fi Je and orange on the other. They have been brought ^ 
 hither out of other countries, and they are now much 
 propagated bv cngiafting. This was confirmed to us 
 (fays the editor of the Tranfadlions of the Royal So- 
 ciety) by a very ingenious Engllfli gentleman, ivho af- 
 ferted, that himfelf not only had feen, but bought of 
 them, anno i66d, in Paris, whither they had been fent 
 
 pliancy, and gentlenefs were ever prevalent in him to a by Genoa merchants ; and that on fomc trees he had 
 
 degree of excefs, who that knew him will blame an ex- found an orange on one branch and a lemon on ano- 
 
 eel's which opened his foul to every emotion and office ther branch (which is not fo remarkable as what fol- 
 
 of afFeiftion and friendrtiip ? lows) ; as alfo, one of the fame fruit, half orange and half 
 
 This account of Dr Enfield, which is taken from the lemon ; and fometimes three quarters of one and a quar- 
 
 M'Jiithly Maginzinf, is acknowledged by its author to ter of the other. 
 
 be the elfufion of fritndihip ; but we believe that the 
 panegyric, though high, is in general jiilt. It is our 
 duty, however, to warn our readers againll placing im- 
 plicit confidence in the Dotlor's reprefentation of an- 
 cient philofophy; for though we have frequently found 
 him correft, and have therefore quoted him with ap- 
 probation ourfelves, we have likewife found him fome- 
 times miftaking the fenfe of his authors. In a work 
 like his, miftakes were indeed unavoidable ; for when 
 he refolved to conprefs the fnbftance of Brncker's five 
 
 In the third part of the Reports of the Board of 
 Agriculture, among the foreign communications, we 
 fee, with equal pleafure and allonirtiment, an account of 
 the American apple, which, by a peculiar mode of l)',id- 
 dinglA), is half fweet and half four, half white and 
 half red, without the lead confufion of the relpeftivc 
 lialves. 
 
 At Mr Mafon's, florlil, Fleet-llreet, oppofite the 
 Bolt and Tun, there is a produftiou now, September 
 1798, to be feen half peach and half neclarine. It has 
 
 volumes within the compafs of two, he could not avoid all the foftncfs and yellow down of tlie peach, and the 
 
 fometimes giving what he thought the fenfe of the an- fleek red fmoothnefs of the neftarine ; fiippofed to be 
 
 cients, whin accuracy required their very tuorJs to be a liifus natur.t, but probably is rather the iportings of 
 
 given. This we believe to be the fource of thofe errors art than of nature, and which perhaps will be the caule 
 
 in his elegant hiilory, which we have heard others un- why we Ihall in future fee many other fuch vegetable 
 
 juilly attribute to defign ; for had it been his ihfigti to wonders, which, as we fee, were known to our-an- 
 
 deceive, he would not fnrely have (lored his margin ceftors. 
 
 with references to enable every reader to detett the de- 
 ceit. 
 
 ENGINEER, Is the appellation of him whofe pro- 
 feflion it is to contrive or make any kind of ufeful en- 
 gine or machine. He is denominated either a civil or 
 military engineer, according as the objedls of his pro- 
 ftffion refpeft civil or military purpofes. See Forti- 
 fication, Encycl. and Machine in this Supplement. 
 
 ENGONASIS, in ailronomy, the fame as Hercules, 
 one of the northern conftellations. 
 
 ENGRAFTING. See Grafting, Encyrl. where 
 
 ENNEADECATERIS, in chronology, a cycle or 
 period of iQ-folar years, being the fame as the golden 
 number and lunar cycle, or cycle of the moon. 
 ENSETE. See MusA, £«ryf/. 
 EOLIPILE. See jEolipile, Encycl. 
 EPAULE, or EsPADLE, in fortification, the fhoul- 
 der of the ballion, or the angle made by the face and 
 flank, otherwife called the angle of the epaule. 
 
 EPISCOPACY, the government of the church by 
 diocefcn bifliojis. See Enc\rl. 
 
 ScorcH EPISCOPALIANS, are a focIetyofChrif. 
 it is faid that there is little hope of producing mixed tians, certainly as refpedfable, if not fo numerous, as 
 fruits by engrafting one tree upon another of the fame any other in tlie kingdom which diiTents from the wor- 
 clafs. We confefs ourfelves to be unwilling to relinquilh Ihip and dlfcipline of the ellablithed church. For many 
 this opinion ; but it would be very unfair to withhold years, however, the pubhc worfliip of that fociety was 
 from the public any fad which feems to militate againll profcribed by the legiflature ; and there is reafon to 
 it, and has come to our knowledge. We fliall therefore fufpcd that its real principles are not yet univerfally 
 tranfcribe from the Phi/ofephieal Magazine the following underllood. If this be fo, it furely becomes the editors 
 communication from Dr Thornton, lefturer on medical of a work in which fome account is given of almoft eve- 
 botany at Guy's Hofpital, refpefting a fuppofed liifui ry denomination of Chriflians down to the novel feet 
 naturte, which he confiders as the confequence of en- which ftyles its members Bereans, to do juilice to the , 
 
 grafting. venerable remains of what was once theeftablidicd church 
 
 In the firft volume of the Ph'ilofoph'ual Tranfetaions, of their native country. I 
 
 N" 29. publiflied November 1667, you have the follow- That the reformation from popery was. In Scotland, F'"abli(h- 
 ing communication, intltled, tumultuous and irregular, is known to all Europe; and ^* 
 
 " Some Hortulan Experiments about the engrafting very few of our readers can be ignorant that there ^'"'^jq "I'^HmJ^ 
 
 4 K 2 neither 
 
 (a) the manner in which the extraordinary neftarine-peach firft produced in this country was effedled, was 
 by inierting the bud of one fruit upon the flock bearing a different fort.
 
 Scotch 
 Epirc-; a 
 
 lia.is. 
 
 No licurgy 
 
 E P I [6 
 
 neither order fn the reformed church, nor decency in 
 her worfhip, till James VJ. with mtich addrefs, accom- 
 . pliihed the cftabhihment of ;i very moderate epilcopacy. 
 To this form of chiirch-f^overnmeiit the better part of 
 the nation w:'.s fufficiently attached ; and it continued to 
 be the ecelefi^ftical polity, fupporltd by the fiate, till 
 the grand rebellion, when it was overthrown by the par- 
 tizans of the tiational covenant. It was rellored, how- 
 ever, in 1662; and again aboliihed in 1689 by that con- 
 vention which placed the Prince and Princefs of Orange 
 on the ancient throne of the Scoltilli monarchs. 
 
 Thefc events are fo univerfally known, that it is fuf- 
 ufed in the ficient in this place barely to mention them ; but there 
 J°^'y^ 3'"e probably many of our readers who do not know 
 ' that, during the whole period of her legal eftahliifiment, 
 the Scotch cpilcopal church had no public liturgy. It 
 appears indeed, that the hrft reformers made ule of the 
 Eriglifli book of common prayer ; and there is on re- 
 cord fufficient evidence that John Knox himfelf, though 
 lie dilappvoved of fome things in that book, had no ob- 
 jection either to dated forms of prayer in general, or 
 to a fubordinatiou among the miuillers of the gofpel ; 
 but his fucceifor Andrew Melvil, who pofleiTed neither 
 his learning nor his worth, had influence enough to in- 
 troduce into the church a perfeft parity of minillers, 
 and to excite among the people a very general abhor- 
 rence of liturgical worship. So rooted indeed was that 
 abhorrence, that, as every one knows, an attempt to in- 
 troduce into the church of Scotland a Look of common 
 prayer, copied with fome alterations from that of Eng- 
 land, produced xhe folcnin league and covenant, which in- 
 volved in one common ruin the unfortunate Charles and 
 his darling Epifcopacy. At the reftoration of the mo- 
 narchy, the Epilcopal conftitution of the church was 
 3 reilored, but no new attempt was made to eftablifh the 
 
 jEiccpt at yfp jjf g public liturgy ; and except at the ordinations 
 'of the clergy, when the Englifh forms were ufed, no 
 fervice book was feen in a Scottidi church. 
 
 For fome years after Epifcopacy had ceafed to be the 
 religion of the ftate, the deprived clergy made no al- 
 teration in their modes of fecial wor(hip. Having re- 
 fufed to transfer to King AVilliam that allegiance which 
 they had fworn to King James, they were treated, du- 
 ring his reign, with fuch Icvtrlty, that on the Lord's 
 day they durft not venture further than to officiate " in 
 their own hired houfes, where they received fuch friends 
 as chofe to come in unto them ;" and in thofe fmall 
 congregations, if congregations they may be called, 
 they continued to pray, if not extempore, at lead with- 
 out book, till the acceflion of Anne to the throne of 
 her anceftors. The attachment of that Princefs, not 
 only to the conftiiution, but alfo to the worfliip of the 
 church of England, was well known to them; and they 
 very reafonably thought, that they could not mor« ef- 
 feftually recommend themfelves to her proteftion than 
 by adopting the ufe of the Englifh liturgy, which the 
 mod enlightened among them had long profeffed to ad- 
 mire. It was accordingly introduced by degrees into 
 Scotland; and an aft of parliament being paflisd on the 
 ^ 3d of March 1712, "to prevent the diilurbing of thofe 
 
 ttiiirodtic- of the Epifccpal communion in that part of Great Bri- 
 tionofthe tain called Scotland, ia the exercile of their religious 
 Enjjlifli li- ^yQrdiip, and in the ufe of the liturgy of the church of 
 England," that liturgy was univerfally adopted by the 
 Scotch Epifcopaliaas ; and public chapels, which had 
 
 S.-otch 
 
 li)'il,:o|iil-. 
 
 liaiii. 
 
 turg)-.. 
 
 28 ] E P I 
 
 hitherto been prohibited, were everywhere built, and 
 well frequented. 
 
 That thofe who had refufed allegiance to King Wil- 
 
 liam and Q_ueen Anne iliould fcruple to pay it to a 
 new family, clogged as it was by fo many oaths, can 
 excite no wonder ; nor is ft at all wonderful that, for 
 their attachment to the abdicated family, the public 
 worfhip of the Scotch Epifcopalians was, after the in- 
 furrcftion of 17 1 5 and 1 7 16, laid under fome redraints. 
 Thefe, however, were neither rigoroufly fevere, nor of 
 long duration ; and by the year 1720, their congrega- 
 tions were as numerous as formerly, confdling, efpecial- 
 ly in the northern counties, of men of all ranks, even 
 fuch as held ofiices of trud under the ei^ablillicd govern- 
 ment, who frequented the Epifcopal chapels in prefe- 
 rence to the parifh churches. 
 
 Hitherto the Epifcopalians had been fafely conduft- 
 ed through all dangers and difficulties by the prudence 
 of Dr Role, the deprived bilhop of Edinbutgh; but foon 
 after his death, which happened on the 20th of Ivlarch 
 172c, divifions broke out among them, which threaten- 
 ed to prove more fatal to their church than any perfe- 
 cution to which they had yet been fubjefted. For rea- 
 fons which will be feeii afterwards, it is proper to trac« 
 thofe divifions from their fource. r 
 
 No native of Britain, who knows any thing of the Source's of 
 
 hidory of his country, can be ignorant that Dr San-'*'^''^"" ^- 
 
 croft, the archbifhop of Canterbury, and five other bi- c"'?*v'ii^ 
 /!_ 1 f> 1 • 1 • , r 1 • r ■ Scotch Er 
 
 inops, were at the Kevolution deprived or tiieir fees bynifcoiiaU- 
 
 an aft of parliament ; becaufe, like the Scotch bifhops, ans, 
 they could not bring themfelves to transfer to King 
 AVilliam and Queen Mary that allegiance which they 
 had fo lately fworn to King James. As thofe prelates 
 were extremely popular for the vigorous oppofition 
 which they had given to fome of the Popifh projefts of 
 the late king, and as a number of inferior clergymen, 
 of great eminence for piety and learning, were involved 
 in the faine fate with them — it need not excite great 
 furprife, that a fweeping deprivation, which, in all its 
 circumdances, was perhaps without a precedent in ec- 
 clefiadical hidory, produced a fchifm in the church of 
 England. The deprived clergy, confidering the bilhops 
 who were placed in the fees thus vacated as intruders, 
 and all who adhered to them as fchifmatics, opened le- 
 parate chapels under the authority of the primate and 
 his nonjuring fuffragans; and contended, that they and 
 their adherents condltuted the only orthodox and ca- 
 tholic branch of the church in England. 
 
 Both churches, however, made ufe of the fame litur- 
 gy ; and during the lives of the deprived prelates, there 
 was no other apparent difference in their worfliip than 
 what neceffarily refulted from their paying allegiance to 
 different fovereigns. But this uniformity was not of 
 long duration. The bidiops, who had been pofleffed of 
 fees before the Revolution, were fcarcely dead, when 
 their fucceffors, being under no civil redraint, found, in 
 the principles which they had brought with them from 
 the tdabllfhmenl, the means, not only of dividing their 
 own little chufch, but h'kewife of fowing the feeds of 
 diffenfion among their brethren in Scotland. 
 
 It has been obferved elfewbere*, that in the church* 3r»ri» 
 
 of England there are three opinions reipeftinsr the na-of '''' „ 
 
 1 , r 1 T J. o L • i_ • r Lnrd,£«» 
 
 ture and end of the Lords Supper, whicti, in oppoli-^ . ' 
 
 tion to each other, have been all patronifed by men of 
 
 great eminence for Uieological learning. It appears, 
 
 indeed.
 
 E P I [ 629 ] E P I 
 
 Scotch indeed, from the firft liturpy fet forth by authority in wife to the moft ancient liturgies extant, as well as to Sn>tth 
 Epifcnpa- thg reign of King EJward VI. that the reformers of what the fathers of the firfl three centuries have taught ■^P'''"P»- 
 ''*"'■ that church from the errors of popery uuanimoully concerning the nature of the Lord's Supper. The con- 1 \ f 
 ' lield the Lord's Supper to be a aichariilical facrifice ; fequence was, that fucli of them as were frholars foon 
 and this opinion, which has been adopted by great difcovcred. that the Scotch communion office approach- 
 numbers in every age fmce, ftems to have been the moll ed much nearer to the moft ancient oflices than tlie 
 prevalent of the three among tbofe clergy who were Engllfh ; and a powerful party was formed for reviving 
 deprived of their livings at the Revolution. It is in- the ufe of it in Scotland. 
 
 deed countenanced by fevera! palfages in the prefent or- Had tliofe men aimed at nothing farther, it is pro- 
 
 der for the adnr'niilration of the Lord's Supper ; and bable they would have met with very little oppofition. 
 
 therefore, though there are other things in that order Their opponents, who, in general, were lefs learned 
 
 which cannot be cafily reconciled to it, archbi(hop San- than they, were {o flrongly attached to the houfe of 
 
 croft and his fufFragans, whatever their own opinions Stuart, that they would have adoj)ted almoft any thing 
 
 might be, chofe not to widen the breach between them- fanftioned by the royal martyr's authority ; but the 
 
 felves and the eftablifhment, by deviating in the fmalleft advocates for the Scotch office knew not where to flop. 6 
 
 degree from the form in which they had been accuftom- They wiflied to introduce fome other ufages of the pri- Revival nf 
 
 ed^to celebrate that facrament. Their fucccflbrs, how- nu'tive church ; fuch as the commemoration of the faith-* """"'"'' 
 
 ever, in office, were men of different difpolitions. Con- ful departed, and the mixture of the euchariftic cup^'"" 
 
 fidering themfelves as totally uncoimefted with the (See SurptR of tie Lord, n* 2. and 3. Encycl.) ; and 
 
 ftate, and no longer bound by the aft of uniformity, their brethern, perceiving no authority from Charles I. 
 
 one party, at the head of which was bifhop Collier, for thefe things, and being accullomed to confider them 
 
 the celebrated ecclefiaflical hillorian (a), judged it pro- as Popifh jiraCtices, a violent controverfy was ready to 
 
 per to make fuch alterations in the communion office burfl forth about what every enlightened mind mull 
 
 as miglit render it more fuitable to their own notions confider as matters of very little importance, 
 of the Lord's Supper, and bring it nearer, both in mat- That the euchariftic cup was in the primitive church 
 
 ter and form, to the moll ancient liturgies of the Chri!- mixed with a little water, is a faft incontrovertible; 
 
 . tian church. that the practice was harmlefs and decent, it is wonder- 
 
 Of the propofed alterations, fome were perhaps pro- ful that any man fhould deny ; but that fuch 3 mix- 
 
 per in their circumflances ; whlHl others, to fay the ture is ejpniial to the facrament, we cannot believe, for 
 
 heil of them, were certainly needlefs, if not inexpedient, the reafons affigned in the article referred to ; and 
 
 They were accordingly all oppofed by another power- therefore it ought furely to have been no objecl of con- 
 
 ful party of nonjurors ; and the queflions in difpute tention. 
 
 were referred, firil to Dr Rofe, the deprived bifhop of That the faithful departed were commemorated in 
 
 Edinburgh, and afterwards to Dr Atterbury and Dr the primitive church long before the invention of pui- 
 
 Potter, the bifhops of Rochetter and Oxford. What gatory, is known to every fcholar ; that in thofe days 
 
 judgment the two Englifli prelate"! gave in this contro- fuch a commemoration tended to invigorate the faith 
 
 verfy we know not; but that of bifhop Rofe did him and the charity of Chrlflians, it would, in our opinion,, 
 
 much honour. Declining the office of umpire between be very ealy to prove ; and that at prefent every Chrif- 
 
 the parties, he recommended mutual forbearance and tian prays in private for his decealed friends, we have- 
 
 occafional communion with each other, according to proved elfewhere by arguments, of the confutation of- 
 
 either form ; and employed a gentleman, well veried in which we are under no apprchcnlion (See G re t.K- church ^ 
 
 ecclefiaflical literature, to prove t!iat fuch a complianca in this SuppUmeni) : but we lee not the neccjjity of in.. 
 
 of bifhop's with each others innocent prejudices was troducing fuch prayers into public woriliip atany pe- 
 
 not uncommon in the purell times. riod ; and we perceive impropriety in doing it at a pe- 
 
 Thef* difputes among the Englifh nonjurors, and the riod when, from various circumflances, they may caiife 
 
 appeal which was made to Dr Rofe, drew, more clofe- weak brethren to err. But thofe who pleaded fc^r the 
 
 ly than hitherto it had been drawn, the attention of the revival of this praftlce in the beginning of the current 
 
 Scotch Epifcopal clergy, not only to their own liturgy, century, were blinded by their very erudition (b) ; and' 
 
 which had been authorifed by King Charles L but like- thofe who oppofed it feem not to have been acuuaiuted: 
 
 with-. 
 
 (a) This very learned, though violent man, of whom the reader will find fome account in the Encychptdiai 
 was, with Dr Hickes and others, confecrated by the deprived piclates, for the purpofc of prtferving the Epifi 
 copal fucceffion in what they confidered as the true church of England. 
 
 (b) Paradoxical as this afrtrtion may at firfl fight appear, nething is more certain than that erudition, and 
 even fcience, if partially cultivated, is as likely to blind as to enlighten the underflanding. When a man de. 
 votes all his time, and all his attention, to .jOTpurfuit, he contracts fuch a fondnels for it, as gradually to confi- 
 der it as the only valuable purfuit, which will infallibly lead to truth, and to nothing but truth ; and in this dif- 
 pofition of mind, he. is ready to embrace the moft extravagant abfurdity to which it may conduit him. Of thij 
 the reader will find one very flriking inlfance in page 547 of this volume, where the celebrated Euler ajipears 
 fo devoted to his darling analyfis, as to place implicit confidence in it, even when he himlclf feems fenfible that 
 it had led him to a conclufion contrary to common fcnfe, and the nature of things. That Dr Bentley was a 
 very eminent phllologift, is univerfally known ; that his emcndatory criticifms on the Claffics are often happy, 
 no man will deny ; and yet, mifled by his favourite purfuits, he never pronounces more dogmatically than wher» 
 the dogma whi;h he utters is untenable. We appeal to his criticifms on Milton. Ptrjiapi there is not a mai 
 
 aliv.*--
 
 Scotch 
 
 BpU'cops 
 
 lians. 
 
 E P I [6. 
 
 with the workings of a benevolent and dsvoiit mind, or 
 indeed to have known in what the fdtncc of a prayer 
 , conliils. 
 
 The ancient ufages, however, were not the only fiib- 
 jefts which, on the death of bifliop Rofc, furnifhed 
 matter for controverfy among the Scotch Epifcopalians. 
 That excellent prelate, together with the deprived arch- 
 bilhojj of Ghifgow, and the deprived bifliop of Dun- 
 blain, had, from time to time, as they faw occafion, 
 raifed to the Epifcopal dignity fome of the moll defer- 
 ring Prefbyters ot the church ; hvit it was refolvod, for 
 wh;it reafon we. do not very well know, that none of 
 the new bifhops fliould be appointed to vacant diocefes 
 during the life of any one prelate who had poiTclTed a 
 legal cftablifliment ; fo that bifhop Rofe, who furvived 
 all his brethren, was for feveral years the ecclefiailicaJ 
 governor of the whole Epifcopal church in Scotland. 
 On his death, therefore, though there were four bifhops 
 in Scotland, and two Scotch bilhops reiiding in Lon- 
 don, there was not one of thofe prelates who could 
 claim to himfelf the authority of a diocefan over any 
 portion of the Catholic church. This they at firft una- 
 nimoufly acknowledged ; and one of them, in the name 
 of himfelf and his brethren, recommended to the clergy 
 of the diocefe of Edinburgh to eled, after the primitive 
 plan, a fuccefTor to their late venerable diocefan. The 
 advice was followed ; the eleftion was made, and ap- 
 proved by the bifiiops : and Dr Fullarton, the bifliop 
 chofen, became bifliop of Ediriburgh, by the fame means 
 and the fame authority as, in the primitive church, St 
 Cyprian became bifhop of Carthage, or Cornelius bi- 
 ihop of Rome. 
 
 The clergy in other diftriets, following the example 
 of thofe in Edinburgh, diocefan Epilcopacy was about 
 to be revived throughout all Scotliind upon principles 
 purely ecclefiaflical, when fame of the bifhops, whom 
 Dr Rofe had left behind him merely for prcferving the 
 Epifcopal iucctirion, conceived a new and very extra- 
 - ordinary conftitution for the Scotch Epifcopal church. 
 
 CoUetre of Whether they were envious of their colleagues, and of- 
 bilhops. fended that none of the clcftiona had fallen upon them; 
 whether they were fo ignorant as not to know that di- 
 ocefan Epilcopacy had lubfilted long before the con- 
 verfion of the Roman empire, in abfolute independence 
 on the ftate ; or that they were actuated, as there is 
 reafon to fufpeft, by tome political principle which 
 they could not with fafety avow ; — fo it was, that they 
 oppofed diocefan Epilcopacy of every kind, and pro- 
 posed to govern the whole Scotch church by a college 
 
 30 ] E P I 
 
 of bifhops. Againft this unprecedenteJ feheme the Sc. t.li 
 more learned bifhops oppofed all their influence j and. ^r'i"^'ti<«» 
 being exceedingly difagreeable to the inferior clergy, , ["'|*^ 
 it was very foon aba-.doned by its authors themlclvtj, ' 
 who, after fome acrimonious controverfy, were glad to 
 come to an agreement witii their diocefan brethren. 
 
 Of this agreement, or concordate as it was called, the There divl. 
 following were the principal articles: i. "That the-')^l^ htal- 
 Scotch or Englifli liturgy, and no other, might be '-■''• 
 indifferently uied in the pubh'e fervice ; and tiiat the 
 peace of the church fhould not be dilturbed by tlie in- 
 troduftion of any of the ancient ufages which had late- 
 ly excited fuch difTenhons. 2. That no man flituld 
 thenceforward be confecrated a bifhop of the Scotch 
 church without the confe.it and approbation of the ma- 
 jority of the bifhops. ^. That the bifliops, by a ma- 
 jority of voices, fhould choofe one of their number to 
 prefide in the meetings of his brethren, and to convo- 
 cate fuch meetings when he judged them neeeffary : 
 that this prelidcnt fhould be fUled Primus Epifcopus, 
 or more fliortly Primus ; but that he fhould not pof- 
 fefs metropolitical power, or claim any kind of jurifdic- 
 tion without the bounds of his own diocefe or diltriit, 
 4. That upon the vacancy of any diocefe or diflriit, 
 the prefbyters fhotdd ncitlier eleft, nor fubmit to, ano- 
 ther bilhop, without receiving a mandate by the Pri- 
 mus, iffued with the confent of the majority of his col- 
 leagues." 
 
 This concordate was in 1731-2 fubfcribed by all the 
 bifliops then in Scotland, who immediately became dio- 
 cefans, and thought no more of the college lyflem. It 
 was afterwards, with a few additions, for afcertaining 
 more precifely the prerogatives of the Primus ; for re- 
 gulating the conduit of fynods ; for exempting biihops 
 from the jurifdiflion of other bilhops, in whofe diftriils 
 they might chance to refide ; and for preventing infe- 
 rior clergymen from deferting their congregations, or 
 removing from one diltridl to another, without the con- 
 fent of the bilhops of both — thrown into the form of 
 canons ; and thefe canons have continued to be the' 
 code of the 6cotch Epifcopal church down to the pre- 
 fent day. 
 
 The members, and more efpecially the clergymen of p, i;,,(.al 
 this church, had always been confidcred as unduly at opinioiis, 
 tached to the family of Stuart ; and though there was 
 undoubtedly at firft fome ground for that fufpicion, 
 the writer of this article knows, from the moft incon- 
 trovertible evidence, that it was continued too long, 
 and carried by much too far. Jacobitifm was impu- 
 ted 
 
 alive who will refufe to Dr Warburton the praifc of learning and ingenuity. The addrefs with which he de- 
 tedls the double doitrines of the ancient philofophers, is fomciimes almoll altonifhing ; yet, mifltd by his own 
 ardour in this purfuit, he difcovers hidden meanings everywhere, and has found a rational fyflem of religion in 
 fome of the ancient myfleries, where there is every reafon to believe that nothing in reality was to be found but 
 atheifm and vice. Jufl fo it is with the ardent reader of the Chriftian fathers. If he devote all his time to 
 the ftudy of their writings, he not only becomes enamoured of his employment, but acquires gradually fuch a 
 veneration for the charafter of his mafters (and venerable they undoubtedly are) as renders him afraid to quef- 
 tion any thing which they advance, and unable, to diflinguifli between their teffimony, which is deferving of all 
 credit, and their reafonings, which are often inconclufive. We trufl it is needlefs to difclaim any wifli to dif- 
 courage, by this note, the ftudy either of the Chriftian fathers, the Greek philofophers, philological criticifm, 
 or the modern analyfis ; we only wifh to difTuade men of letters from devoting their whole time to any one pur- 
 fuit whatever ; for they may depend upon it, that inch partial ftudies contradl the mind. One of the moft emi- 
 nent mathematicians at prefent in England is reported to have declared his contempt of the Paradife Lojl, be- 
 caufe he found in it nothing demon/lraled .'
 
 E P I 
 
 [ 6 
 
 Scotch te>1 to the fociety as its diiiftingtiiftiinjT tenet ; ln\t the 
 
 El.ik. I'J- ,rt.,nhers of that i'ociety have at nil times contcndej, that 
 ''^"li; ttielrdiftinguifliing tenets were tlie apollt)lical inllitiition 
 
 ~ * of Epircopacy, and in the exercife of thofe powers which 
 
 are purely fpiritual, the independency of the chiivcli upon 
 the (tale. In politics, indeed, they have unaiilinoufly 
 maintained, tliat the only ruler of princes or legif.aluyes 
 is God, and not the people. They are, of courfe, no 
 friends to ttie falhionable docSrine of refiilance, which 
 they believe to be not only condemned in exprels terms 
 by Chrifl and two of his apolUcs, but to be alfo the 
 fource of that anarchical lyrajiny which lately de- 
 luged Europe with blood. They conlider a limited 
 monarchy, like that of Britain, as t)ie moll perfect form 
 of civil government which the world has everfeen; and 
 hereditary monarchy is inliuitely preferable to one that is 
 eledive : and v\'ilh refpcifl to the title of the monarch, 
 when they take a retrofpcilive view of the origin of all 
 civil governments, they cannot but look upon a per- 
 manent andunqueftioned cftablifhment as an indiciti(/n 
 of the plan and determination of Providence furnifliiiig 
 the belt: right to a crown which any modern fovereign 
 can claim. 
 
 Petfetution Surely thefe are harmlefs opinions; and yet the worfliip 
 of thofe who held them was, in 1746 and 1748, laid un. 
 dcr fuch reilraints as were calculated to produce difalFec- 
 tion where it did not previoufly e.sift. Two laws were 
 then enafted againft the Scotch Epifcopalians ; which, 
 under the pretence of eradicating their attachment to the 
 houfe of Stuart, were fo contrived as to preclude fuch 
 of their clergy as were willing to pay allegiance to the 
 reigning fovereign, and to pray for the royal family by 
 name, from reaping the Imalled beneiit from their loyal- 
 ty. The experiment was tried bv fome of them ; of 
 whom one venerable perfon, who was iiever fufpefted of 
 undue attachment to the houfe of Stuart, isflill alive; hut 
 he, and his complying brethren, had their chapels burnt, 
 and were themfelves imprifoned, as if they had been 
 the moft incorrigible Jacobites. This was a kind of 
 perfecution which, fince the Reformation, has had no 
 precedent in the annals of Britain. A prieft of the 
 church of Rome, by renouncing the errors of Popery, 
 has at all times been qualilied to hold a living in Eng- 
 land ; a dilTenting minifter, of whatever denomination, 
 might at any time be admitted into orders, and riie to 
 the htgheft dignities of the Englifh church; — but while 
 the laws of 1746 and 1748 remained in force, there 
 was nothing in the power of a Scotch Epifcopal clcr- 
 fryman to do from which he could reap the fnialleft be- 
 nefit. By taking the oaths to government, he was not 
 qualified to hold a living in England, or even to enjoy 
 a toleration in Scotland ; and liis clerical charafter be- 
 ing acknowledged by the EnglHh Bifliops, he could not 
 by thofe prelates be canonically reordained. 
 
 Upon the clergy, however, thofe laws of uncommon 
 
 rigour were not long rigoroufly executed. After a few 
 
 years, the burning of chapels, and the imprifoning of 
 
 J J miniilers, were occurrences far from frequent ; but the 
 
 rolcration. laws to which we allude affeiTted likewiie the political 
 privileges of fuch laymen as frequented the Epifcopal 
 chapels : and in that part of their operation, thofe laws 
 were never relaxed till 1792, when they were wholly 
 repealed, and the Epifcopalians in Scotland tolerated 
 like other well affefted diffenters from the national efta- 
 bliHimeat. 
 
 31 ] E P I 
 
 While Epifcopacy was the eftabliflied form of church Scotch 
 gover. ment in Scotland, the clergy of that church fub- '-P'"°P*' 
 fcribed a confeflion of faith fummtd up In tweiuylive 1 ' ■ 
 
 articles, which the rtader will find in the nillory altri- u 
 buted to John Knox. It is fiifiicient to obfcrve in thisF^i'hof 
 place, that in ed'entials it diflcrs little from the articles'''' ^"''i'* 
 of mofl other rtfoimed churches; and in Yvci^y thing j.||y^£|^ 
 which does not immediately relate Xo papijlry, it is mo- 
 derate and unexceptionable ; perhaps more fo than tlic 
 prefent confelfion of either of the Britlfli churches. 
 During the period which intervened between the Re- 
 volution and the year 1792, no fubfcription was in- 
 deed required from Scotch E])IfcopaIlan clergymen to 
 any fummary of Chrilh'an dodrine ; but at their ordi- 
 nations, thofe clergy folemnly profefRd their belief of 
 all the canonical books of the Old and New Tefta- 
 ments ; declared their ])erfualicn that thofe books con- 
 tain fufficiently all doctrines necefiary to falvation, 
 through faith in Jefus Chriil ; and were obliged to 
 read daily in their chapels the Englilli book of Com- 
 mon Prayer, which contains the Apoflles, Nicane, and 
 Athanafian creeds. But now thofe clergymen are en- 
 joined by adt of parliament to fubfcribe the 39 ar- 
 ticles of the church of England ; fo that the princi- 
 ples of their faith are well known. No doubt there 
 are differences of opinion among them about the fenfe 
 of fome of thofe articles; and it is -well known that 
 there are fimilar differences among^the Englilli clergy 
 themfelves: but there is every reafon to believe, that 
 the faith of the Scotch Epifcopalians has, in every 
 important point, been at ail times orthodox. 
 
 We are aware, that they have been repiefented as 
 unfriendly to the Englllh fervice ; hut inch a reprefcn- 
 tation appears to be either a wilful faluiiood, or the 
 offspring of ignorance. The only reformed liturgy 
 that ever had the fanftion of a civil eftabliihment in j, 
 Scotland, is the Book of Common Prayer, and ylJmini- Their wor- 
 Jiration of the Sacranterts, and other parts of Divine Ser- f^'P- 
 •vice authorifed by King Charles I. In that book, the 
 order of adminiilration of the Lord's Supper differs ia 
 fome particulars from the Englifh order, and is unquef. 
 tionably better adapted to the opinions of thofe who 
 conlider that holy ordinance either as an eueharillical fa- 
 crilice, or as a feail upon a facrifice. In the one or 
 other of thefe lights, the Lord's Supper is viewed by a 
 great majority of the Scotch Epilcopalians ; and of 
 courfe the Scotch communion office is ufed in a great 
 majority of their chapels : but it is not ufed in them 
 all. Their bifhops, who, when in England, communi- 
 cate with the eftablifhed church, leave the inferior clcr. 
 gy at liberty to ufe either the Englifli or the Scotch 
 form, as is moil agreeable to themfelves and to the 
 people among whom they minifter; and to filence the 
 clamour of fymbolizing with the church of Rome, 
 which was fome years ago either ignorantly or malici- 
 oufly ralfed againd them, they altered the arrangtmctit 
 of tlie Scotch prayer of confecration, fo as not only to 
 bring it nearer to the moft primitive forms, but alfo to 
 make it abfolutely inconilftent with the real prefence, 
 as taught either by the church of Rome or by the Lu- 
 theran churches. On this fubjcft, fee GreekCHURCR, 
 n° 17. in this Supplement. 
 
 Thus have we given a lliort view of the diftinguifh- Entrlilh 
 ing principles of what muft furely be confidercd as a clerpj'nien 
 very rcfpeftable fociety of Chriftians, and the only re- '" ScodanJ. 
 
 formed .
 
 II 
 F.rkoom. 
 
 E R K [ 
 
 formed T.pijcopal fociety in that part of Great Britain 
 called Scotland. There arc, indeed, chapek in Scotland 
 , dillinft from the church of which we have been treat- 
 ing, where the Englifh liturgy is read by clergymen 
 who have received Epilc()])al ordination either in Eng- 
 land or in Ireland ; but thofe chapels being all inde- 
 pendent of each other, and under the intpection of no 
 'l)ifhop, th.c perfons who frequent them fecm to be ra- 
 
 ■ ther Congrcgationalilh than Epifcopalians, and certain- 
 ly do not conllitute what can, with any propriety, be 
 called an Ep)f:opal church. 
 
 EQUANT, in allronomy, a fanciful circle, intro- 
 
 ■ tluced into fcience to remove fome of the defefts of the 
 Ptolemaic fyilem of the univerfe. In this artificial 
 fyltem of epicycles and eccentric circles, the idea ol cir- 
 cular and equable motion was by no means abandoned ; 
 but while each of the heavenly bodies revolved in its 
 own orb, the centre of that orb was fuppoied to be car- 
 vied at the fame time round the circumference of ano- 
 ther circle. The more obvious inequalities were thus 
 
 -explained with a geometrical precifion. With all its 
 nice combination, however, of circles, the fyilem was 
 ■loon found to have defcfts ; to remove which, the fine 
 .contrivance of the equant was introduced. Though 
 the angular motion of a planet viewed from the earth 
 was confetTed to be unequal, a point could be conceived 
 .from which it would be feen to move with perfett uiii- 
 -f'ovmity. That point was made the centre of the e- 
 quant, and lay at the fame diftance from the centre of 
 the eccentricity on the one fide, as the earth was re- 
 moved on the other. " Nothing (fays Dr Smith, 
 from whom this account of the equant is taken) can 
 ■more evidently fliew how much the repofe and tranquil- 
 .1 
 ■phy 
 
 EQUATION OF A CURVE 
 lyd.) Part III. chap. ii. 
 
 Secular Equation, in aftronomy. See Astronomy 
 in this Supplement, no 25 — 38. 
 
 EQUICURVE CIRCLE, the fame with Circle of 
 Curvature, which fee in this Supplement. 
 
 ^^r^rn 1 Two Abyflinian flirubs of 
 
 ERGETT EL KRANE / the genus Mimosa, which 
 
 .ERGETT v'D.MMO,^ fee L.;-./. 
 
 ERKOOM, an Abyflinian bird, part of a large tribe, 
 
 <■<■ in which (fays Mr Bruce) the greateR variety lies in 
 
 his beak and horn. The horn he wears fometimes upon 
 
 the beak and fometimes upon the forehead above the 
 
 root of the beak." This bird is by naturaliils called the 
 
 Indian crow or raven ; and our author, thoiigh he 
 
 feems to think this claffification improper, admits that 
 
 he has one charefteriftic of the raven ; he walks, and 
 
 does not hop or jump in the manner that many others 
 
 of that kind do ; but then he at times runs with very 
 
 .great velocity, and, in running, very much refembles 
 
 the turkey or buftard when his head is turned from 
 
 The colour of the eye of this bird is of a dark brown, 
 t>r rather reddilh, cad, but darker ftiU as it approaches 
 " the pupil ; he has very large eyelafhes, both upper and 
 lower, but efpecially his upper. From the point of 
 the beak to the extremity of the tail is three feet ten 
 inches ; the breadth, from one point of the wing to 
 the other extended, is fix feet, and the length twenty. 
 tvM) inches j the length of the neck ten inches, and its 
 
 ty of the imagination is the ultimate end of philofo- 
 hy, than the invention of this equalizing circle." 
 
 See Algebra {En- 
 
 Q>li ^ E T O 
 
 thicknefa three inches and a half; the length of the 
 beak, meafviring the opening near the head llraight to - 
 the point, ten inches; and from the point of the beak 
 to the root of the horn, Icveii inches ard three eighths. 
 The whole length ot the horn is three inches and a half. 
 The length of the horn, from the foot to the extre- 
 mity where it joins the beak, is four inches. The 
 thickiicis of the beak in front of the opening is one 
 inch and feven eighths. The thicknefs of the horn in 
 front is one inch and live eighths. The horn in height, 
 taken from the upper part of the point to the beak, 
 two inches. The length of the thighs feveu inches, 
 and that of the legs fix inches and ftve eighths. The 
 tlnckuefs in profile feven lines, and in front four lines 
 and a half. It has three toes before and one behind, 
 but they are not very ftrong, nor feemingly made to 
 tear up carcafes. The length of the foot to the hinder 
 toe is one inch fix lines, the innermoll is one inch 
 feven lines, tlie middle two inches two lines, and the 
 lall._ outer one two inches one line. This' bird is all of 
 a black, or lather black mixed with foot-colour ; the 
 large feathers of the wing are ten in number, milk- 
 white both without and within. The tip of his wings 
 reaches very nearly to his tail ; his beak and head mea- 
 fured together are eleven inches -and a half, and his 
 head three inches and a quarter. At his neck he has 
 thofe protuberances like the Turkey-cock, which are 
 light blue, but turn red upon his being chafed, or in 
 the time the hen is laying. 
 
 The erkoom, though not eafily raifed, flies (fays 
 our author) both flrong and far. It has a rank fmell, 
 and is faid in AbyfTinia to '^eed upon dead carcafes. 
 This, however, he thinks a millakc, as he never faw it 
 following the army, nor approaching a dead carcafe j 
 and as often as he had occafion to open this bird, he 
 found in its llomach nothing but the green fcarabeus 
 or beetle. It builds in large thick trees, always, if it 
 can, near churches ; has a covered neft like that of a 
 magpie, but four times as large as the eagle's. It places 
 its neil iirm upon the trunk, without endeavouring to 
 make it high from the ground : the entry is always on 
 the eail fide. 
 
 ETON i3 a place which, on account of its college, 
 fhould not be omitted in a repofitory of arts, fciences, 
 and literature ; and as no notice is taken of it in the 
 Encyclopudia, we (liall deviate for orrce from the plan 
 which we had laid down for this Supplement, and 
 which is, not to admit into it defcriptions of places in 
 our own ifiand that may be vifited by the greater part 
 of our readers with little trouble. 
 
 Though in a different county, namely, Buckingham- 
 fliire, Eton may be laid to be one and the fame town 
 with Windfor, for which fee Encycl. It is pleafantly 
 fituated on the banks of the Thames, in a delightful 
 valley, which is of a remarkably Wealthy foil. Its col- 
 lege was founded by Henry VI. for the fupport of a 
 provolt and feven fellows, one of whom is vice-provolt, 
 and for the education of feventy King's fcholars, as 
 thofe are called who are on the foundation. Thefe, 
 when properly qualified, are elefted, on the firft Tuef- 
 day in Auguft, to king's college Cambridge, but they 
 are not removed till there are vacancies in the college, 
 and then they are called according to feniority ; and 
 after they have been three years at Cambridge, they 
 claim a fellowfbip. Befidet thofe on the foundation 
 
 tkere 
 
 Eton.
 
 IL T O [63 
 
 tliciT are felJom Icfs than ibiee hundred fcholars, and 
 'often many more, who board at the mailers hmifes, or 
 within the boiuids of the college. 'I'he fchool is divi- 
 dod into upper and lower, and each of thefe into three 
 cLiffes. To each fchool there is a malb r and fo\ir 
 afhilants or ufliers. Tlie revenue of the college is about 
 L. 5000 a-year. Here is a noble library, and in the 
 great court is a fine ftatue of the founder, ereCled at 
 the expence of a late provolt Dr Oodolphin dean of 
 St Paul's. The chapel is in a jrood (lyle of Gothic ar. 
 chitecture. The fchools and other parts, which arc'in 
 the other flyle of building, are equally well, and feem 
 like the defign of Iiiigo Jones. 
 
 At Eton there is a fingular, and we think a laudable, 
 felb'val called the Mctitsm, celebrated triennially (for- 
 merly duennially) by the fcholars of the fchool upon 
 Whit-Tuefday. The following account of this feih'val, 
 taken from the Monthly Magazine, will probably be 
 acceptable to many of our readers. 
 
 It commences by a number of the fenior boys taking 
 polt upon the bridges or other leading places of all the 
 avenues around Windfor and Eton ioon after the dawn 
 of day. Thefe youths fo polled are chiefly the beft 
 figures, and the molt adlive of the (Indents ; they are 
 all attired in fancy drefles of fdks, fatins, &c. and fome 
 richly embroidered, principally in the habits or falhion 
 of running footmen, svith poles in their hands; they 
 are ciilled f ah- tea irrs, and demand fait, i. e. a contribu- 
 tion from every pafTenger, and will take no denial. 
 
 When the contribution is given, which is ed libitum, 
 
 a printed paper is delivered with their motto and the 
 
 date of the year, which pafles the bearer free through 
 
 all other falt-bearers for that day, and is as follows, viz. 
 
 " Pro more et monte, 
 
 1799' (a) 
 Vivant Rex et Regina." 
 
 Thefe youths continue thus coUetling their fait at 
 all the entrances for near feven miles round Windfor 
 and Eton, from the dawn of day until about the clofe 
 of the procelTlon, which is generally three o'clock in 
 the afteriioon. 
 
 The procefiion commences about twelve o'clock at 
 noon, and confifts of the Queen's and other bands of 
 mufic ; feveral ftandards borne by different ftudents ; 
 all the Etonian boys, two and two, drefTed in officers 
 uniforms ; thofe of the king's foundation wearing blue, 
 the others fcarlet uniforms, fwords, (Sec. 
 
 The Grand Standard-bearer. 
 
 The Captain, or Head Boy of Eton School. 
 
 The Lieutenant, or Second Boy. 
 
 His Majefty, attended by the Prince of Wales, and 
 ether male branches of the royal family on horfeback, 
 with their fuife. 
 
 The Queen and Princefles in coaches, attended by 
 their fuite. 
 
 Band of mufic, followed by a great concourfe of the 
 Nobility and Gentry in their carriages and on horfe- 
 back. 
 
 The procefiion commences in the great fquare at 
 Eton, and proceeds through Eton to Slough, and round 
 to Salt Hill, where the boys all pafs the king and 
 queen in review, and afcend the Montem : here an ora- 
 
 SuppL.. Vol. 1. Part II. 
 
 3. ;i . ^ ^ ^ . . 
 
 tion is delivered, and the grand ftandard ia difplayed 
 v/ith much grace and adlivity by the flandard bearer, 
 who is generally fcle£led from among the fenior boys. 
 
 There are two extraordinary falt-bearers appointed 
 to attend the king and qut;en, who are aKvays attired 
 in fanciful hibits, in manner of the other falt-bearers 
 already dcfcribed, but fuperbly embroidered. Thefe 
 fail-bearers carry each an embroidered bag, which no* 
 only receives the royal fait, but alfo whatever is collect- 
 ed by the out-ftattoned falt-bearers. The donation of 
 the king and queen, or, as it is called upon this occa- 
 fion, the royal fait, is always fifty guineas each ; the 
 Prince of Wales thirty guineas ; all the other princes 
 and princelTes twenty guineas each. As foon as this 
 ceremony is performed, the royal family return to 
 Windfor. Tlie boys are all fumptuouOy entertained at 
 tlie tavern at Salt Hill ; and the beautiful gardens at 
 that place are laid out for fucli ladies and gentlemen as 
 choofe to take any refrediments, the dilTerenl bands of 
 mufic performing all the time i'l the gardens. 
 
 About fix o'clock in the evening all the boys return 
 in the fame order of proccflion as in the morning (with 
 the exception only of the royal family), and, marching 
 round the great fquare in Eton fchool, are difmifTed. 
 The captain tl\en pays his refpefts to the royal family 
 at the queen's lodge, Windfor, previous to his depar- 
 ture for King's College, Cambridge ; to defray which 
 expence, the produce of the montem is prefented to 
 him; and upon Whit-Tuefday, in the year 1796, it 
 amounted to more than 1000 guineas. Tiie day con- 
 cludes by a brilliant difplay of beauty, rank, and ta. 
 (hion, a promenade on Windfor Terras, bauds of mufic 
 peiforming, &c. and the fcene highly enlivened and en- 
 riched by the affable condefcenlion of the royal family, 
 who iudifcriminately mix with the company, and pa- 
 rade the Terrace till nearly dark. 
 
 Spontaneous EVAPORATION. See Weather, 
 no 17, &c. Encycl. 
 
 EUDIOMETER, an inllrument for afcertaining 
 the purity of the atinofpherieal air. Many have been 
 the contrivances of chemlils for this purpofe (fee Eu- 
 diometer, Encycl.) ; but perhaps the beil eudiometer 
 is that of Morvcau (or Guyton, as he now choofes to 
 call himfelf), of which mention has been made in Chu- 
 MiSTRV, n"4zo. in this Supplement. The h)iUiAing 
 fliort defcription will make the nature and ufe of this 
 inftrument plain to every reader. 
 
 AB, (Plate XXVIli. ) leprtfents a fmall glafs retort 
 with a long neck ; its whole capacity being from leven 
 to nine folid inches. It muil be chofen of fuch a cur- 
 vature that, when tlie neck is fet upright, the bulb may 
 form at its lower part a cavity to retain thv; matters in- 
 troduced. The extremity of the neck of this retort 
 is ground with emery to enter the ghifs tube CD, 
 which is open at both ends, and about i 2 or 15 inches 
 in length. The retort then clofes the tube in the man- 
 ner of a ground Hopper, and intercepts all ekternal com- 
 munication. A cylindrical glais veffel F is provided, 
 of the form of a common jar, in which the glafs tube 
 CD may be entirely plunged beneath the level of the 
 water. Laftly, the fulphuret of potafli is pr<;pared and 
 broken into pieces fufficiently fmall to be iutioduceJ 
 4 L ifi'.o 
 
 Hen, 
 
 udininr- 
 ter. 
 
 (a) Or whatever the year may be.
 
 E U D [6 
 
 Eudlome- Jnto the retort. Thefe are to be inclofed, dry and even 
 hot, in a bottle for ufe. Tiiefc coniliiute the whole 
 , apparatus and preparation ot materials. 
 
 When it is required to examine an aerifornfi fluid, by 
 feparating its oxygen, two or three pieces of the ful- 
 phuret, of the fize of a pea, are put into the retort. It 
 is then filled with water, taking care to incline it fo that 
 all the air may pafs out from the bulb. The orifice of 
 the retort is then to be clofed, and inverted into the 
 pneumatic tube, in order that the gas propoftd for exa- 
 mination may be transferred itito it in the ufual manner. 
 By an eafy manoeuvre of alternately inclining the re- 
 tort in different directions, all the water is made to flow 
 out of the bulb in which the I'ulphuret remains. When 
 this is done, the retort is placed in the vertical fituation, 
 and its extremity introduced into the tube of glafs CD, 
 which mull always be under water. A fmall lighted 
 taper is then to be placed under the bulb. To fupport 
 the retort in its pofition, the jar is provided with a 
 wooden cover, in which there is a notch to receive it. 
 
 The firll impreffion of the heat dilates the gafeous 
 fluid fo much that it defcends almoll to the bottom of 
 the tube, which is difpofed cxprefsly for its reception ; 
 otherwife the partial efcape would prevent an accurate 
 determination of its change of bulk. But as foon as 
 the fulphuret begins to boil, the water quickly rifes, not 
 only in the inferior tube, but likewife in the neck of 
 the retort, notwlthllandlng the application, and even 
 the increafe of the heat. 
 
 If the fluid be abfolutely pure vital air, the abforp- 
 tion is total. In this cafe, to prevent the rupture of 
 the veffel by too fudden refrigeration, the afccnt of the 
 v/ater niuft be rendered flower, either by removing 
 the taper, or by increafing the perpendicular height ; 
 which will not prevent the abforptlon from continuing 
 while any gas remains which is proper to fupport com- 
 bnftion. 
 
 If the fluid be common air, or oxygen mixed with 
 any other gas, the quantity of water which has entered 
 the retort mud be accurately meafured after the cooling. 
 It reprefents the volume of air abforbcd. Care muft be 
 taken to inclofe the remaining gas under the fame pref- 
 fure, by plunging the retort to the level of the line at 
 which the inclofed water refts, before the orifice is 
 Hopped. 
 
 This operation of meafuring, which Is very eafy when 
 meafuring vefltls are at hand, may be habitually per- 
 formed by a flip of paper pafted on the neck of the re- 
 tort, upon which dlvifions are drawn from obfervation, 
 and which muft be covered with varnilh to defend it 
 from the aftion of the water. 
 
 EUDOXUS of Gnidus was a celebrated philofopher 
 of the fchool of Pythagoras. His firtl preceptor was 
 Archytas, by whom he was inftruAed in the principles 
 of geometry and philofophy. About the age of twenty- 
 three he came to Athens ; and though his patrimony 
 was fmall, by the generous affillance of Theomedon a 
 phyficlan, he was enabled to attend the fchools of the 
 philofophers, particularly that of Plato. The liberality 
 of his friends afterwards fupported him during a vifit to 
 Egypt, where he was introduced by Agefilaus to king 
 Nedanebis II. and by him to the Egyptian priefts. It 
 has been faid that he accompanied Plato into Egypt ; 
 but this is inconfifl:ent with chronology ; for Neftane- 
 bis II. reigned in Egypt from the fecond year of the 
 
 3+ ] EVE 
 
 hundred and fourth Olympiad, to the fecond year of EveOion 
 
 the hundred and feventh ; and it was before Plato open- H 
 
 ed his fchool, that is, before the ninety-eighth Olym- , ^''"^" ''^^ 
 
 plad, about the fortieth year of his age, that he vlfited 
 
 Egypt. Eudoxus is highly celebrated by the ancients 
 
 for his llclll in aftronomy ; but none of his writings on 
 
 this or any other fubjedt arc extant. Aratus, who has 
 
 defcribed the ceieillal phen^^mena in verfe, is faid to 
 
 have followed Eudoxus. He fiouriflied about the nine- 
 
 ty-feventh Olympiad, and died in the fifty-third year 
 
 of his age. Enfield's Hijl. of Philofophy. 
 
 EVECTION is ufed by fome allronomers for the 
 libratlon of the moon, being an inequality in her mo- 
 tion, by which, at or near the quadratures, flae is not in 
 a line drawn through the centre of the eaith to the fun, 
 as flie is at the fyzygles, or conjunftion and oppofition, 
 but makes an angle with that line of about 2° 5 l'. The 
 motion of the moon about her axis only is equable ; 
 which rotation is performed exaftly In the fame time as 
 flie revolves about the earth ; for which reafon it is that 
 flie turns always the fame face towards the earth nearly, 
 and would do fo exactly, were it not that her monthly 
 motion about the earth, in an eliptic orbit, is not e- 
 quable ; on which account the moon, feen from the 
 earth, appears to llbrate a little upon her axis, fome- 
 times from eaft to v/eft, and fometimes from weft to 
 eafl; ; or fome parts in the eaftern limb of the moon go 
 backwards and forwards a fmall fpace, and fome that 
 were confpicuous are hid, and then appear again. 
 
 The term eveSion is ufed by fome aftronomers to 
 denote that equation of the moon's motion which is 
 proportional to the fine of double the dlftance of the 
 moon from the fun, diminiflied by the moon's anoma- 
 ly. 'I'his equation is not yet accurately determined ; 
 fome ftate it at 1" 30', others at 1" 16', &c. It is the 
 greateft of all the moon's equations, except the equa- 
 tion of the centre. Hutlori's DiBionary, 
 
 EVENLY EVEN NUMBER. See Number, Encycl. 
 
 EysMr Odd Nvmher. See Number, Encycl. 
 
 EVOLVENT, in the higher geometry, a term ufed 
 by fome writers for the involute or curve refulting from 
 the evolution of a cui-ve, in contradlftinftion to that 
 evolute or curve fuppofed to be opened or evolved. See 
 EvOLUTE and Involute, Suppl. 
 
 EVOLUTE, in the higher geometry, a curve firfl, 
 propofed by Huyghens, and fince much lluditd by ma- 
 themallcians. It is any curve fuppofed to be evolved 
 or opened, by having a thread wrapped clofe upon it, 
 faftened at one end, and beginning to evolve or unwind 
 the thread from the other end, keeping the part evol- 
 ved or wound off tight Itretched ; then this end of the 
 thread will defcribe another curve, called the involute. 
 Or the fame involute is defcribed the contrary way, by 
 wrapping the thread upon the evolute, keeping it al- 
 ways Itretched. For the Involution and Evolu- 
 tion of Curves, fee Involution in this Supplement. 
 
 Imptrfeil EyoiuTE, a name given by M. Reaumur 
 to a new kind of evolute. The mathematicians had 
 hitherto only confidered the perpendiculars let fall from 
 the Involute on the convex fide of the evolute : but if 
 other lines not perpendicular be drawn upon the fame 
 points, provided they be all drawn under the fame an- 
 gle, the effeS will ftiil be the fame ; that is, the oblique 
 lines will all interfett in the curve, and by their inter- 
 feftions form the infinitely {jnall ildes of a new curve, 
 
 to
 
 E P [ 
 
 Euphon, to wliieh they would be fo many tangents. Such a 
 ^r-\r— curve is a kind of evolute, and has its radii ; but it is 
 an imperfccl one, fince the radii are not perpendicular 
 to thf firll curve or iiivohlte. 
 
 EUPHON, a mufical inftrument invented lately by 
 Dr Chladni of Wittenberg, well known by his various 
 publications on philoiophieal fubjccfts, cfpccially rhe the- 
 ory of mufical iounds. The euphon confills of forty- 
 two immoveable parallel cylinders of glafs of equal 
 length ana thicknefs ; but its conilrudfion, tone, and 
 the method of playing it, are totally different from thofe 
 of the harmonica, with which indeed it has notiiing in 
 common but the glafs. See Harmonica, Encycl. 
 
 Dr Chladni gives the following account of his inven- 
 tion. In his 19th year he began to learn to play the 
 harpfichord ; and he afterwards read a great many of 
 the principal works on the tlieory of mufic, by which 
 be found that the ph) fico mathematical part of that 
 fcience was tar more defective than other branches of 
 natural philofophy. Being therefore pud'elTed with an 
 idea that his time could not be better employed than 
 in endeavouring to make difcoveries iu this department, 
 he accordmgly tried various experiments on the vibra- 
 tions of ftring.s and the different kinds of vibration in 
 cylindric pieces of wood, iirfl difcovertd, through cal- 
 culation, by the elder Euler; and found, tliat though 
 a great deal had been laid on the nature of thefe elaftic 
 bodies, yet the manner of vibration and the proportion 
 of tones in other claflic bodies, which do not proceed, 
 as in the former, in ftraight lines, but depend on the 
 vibration of whole furfaces, were totally unknown, and 
 that the little which had been written on that fubjeft, 
 by fume authors, did not correfpond with nature. He 
 had already long remarked, that every plate of glafs or 
 metal enu'tted various tones according as it was held 
 and llruek in different places ; and he was deliroiis to 
 difcover the caufe of this difference, which no one had 
 ever examined. He hxed in a vice the axle of a brafs 
 plate which belonged to a polifhing machine, and found, 
 that by drawing the bow of a violin over it, he produ- 
 ced very difltrer.t tones, which were ftrongcr and of 
 langcr duration than thofe obtained merely by ftri- 
 king it. 
 
 The obfervation, that not only firings but alfo other 
 elaftic bodies may be made to produce founds by draw- 
 ing a violin bow over them, Dr Chladni docs not give 
 as a dilcovery of his own ; as the fo called iron violin 
 has been long kno«n. and as he had read of an inftru- 
 Inallpro-ment conllrutled in Italy*, where glafs or metal bells 
 ability the ^yerg piade to found by means of two or more violin 
 
 I at nan tea - 
 
 f the Able''"™'' drawn over them. But the idea of employing 
 'lazzuchi. 'his inftrument to examine vibrating tones was firfl en- 
 tertained by himfclf. Having accurately remarked the 
 tones produced by the abovementioncd metal plate, he 
 found that they gave a progreffion which correfponded 
 with the fquares of 2, ^, 4, &c. 
 
 Not long before he had read, in the Tranfaftions of 
 the Royal Society of Gottengen, the obfervations of 
 Mr Lichtenberg on the phenomena produced by ftrew- 
 ing pounded refin over a glafs plate or cake of refin, 
 and he repeated many of his experiments. This led 
 him to the idea that, perhaps, the various vibratory 
 movements of fuch a plate would be difcovered by a di- 
 verfity of phenomena, if he ftrewed over it fand or any 
 thing of the like kind. By this experiment there was 
 
 6iS ] E U P 
 
 produced a flar-formed figure ; and the author, having Enplion. 
 continued his rcfeaiches, publillied the refult of them in • ^ 
 a work entitled, Difcoveries rcfpedting the Theory of 
 Sound, printed at Leiplic in 1787. 
 
 Whilfl he was employed in thefe inveftlgations, he 
 refolved to invent a new mufical inftrument; and he be- 
 gan to conlidcr whether it might not be pofTible bv 
 rubbing glafs tubes in a ftraight line, with the wet fin- 
 gers, to produce founds in the fame manner as is done 
 in the harmonica by rubbing them circularly. That 
 glafs tubes, like thofe in his euphon, would not merely 
 by fuch rubbing emit any tones, he had long known 
 by theory and experience ; and he therefore ajiplied 
 liimfelf to the fblution of the difficult queftion, in what 
 manner the inftrument ought to be conftrudted to an- 
 fwer the intended purpofe .' After various fruitlefs at- 
 tempts for a year and a half, during which his imagi- 
 nation was fo full of the idea, that fometimcs in his 
 dreams he thought he faw the inftrument and beard its 
 tones, that is, like thofe of the harmonica, but with 
 more diftintlnefs and lefs confulion, he at lenjrth, in a 
 ftate between fleeping and waking, obtained a folutiou 
 of the problem which had given fo much employmeu;; 
 to his thoughts. On the fecond of June 1789, beiig 
 tired with walking, he fat down on a chair, about nine 
 in the evening, to enjoy a fliort flumber ; but fearcelv 
 had he clofed his eyes when the image of an inftru- 
 ment, fuch as he wifhed for, feemed to prefent itfelf 
 before him, and terrified him fo much that he awoke as 
 if he had been ftruck by an cledtric fhock. He imme- 
 diately ftarted up in a kind of enthufiafm ; and made a 
 feries of experiments, which convinced him that what he 
 had feen was perfedly right, and that he had it now in 
 his power to carry his defigu into execution. He made 
 his experiments and contlrudcd his hift inftrument iu 
 fo private a manner, that no perfon knew any thing of 
 them. On the 8th of March 1790 his firft inftrument 
 of this kind was completed ; and in a few days he was 
 able to play on it fome eafy pieces of mufic. It was 
 now neceffary to give to this inflrument, as it was en- 
 tirely new, a new name ; and that of euphon, which iig- 
 rifies an inftrument that has a pleafant found, appeared 
 to him the moft proper. 
 
 It was not, however, brought to perfeftion at once, 
 for he made a fecond inflrument which was an improve- 
 ment of the fiill, and a third which was an improve- 
 ment of the fecond. In found, indeed, and particularly 
 in the higher tones, the firft was equal to either of the 
 other two ; but the copflrutlion was deficient in 
 ftrength, fo that every week fome hours were neceffarv 
 to keep it in proper repair ; and it was impoflible to 
 convey it the diflance of a mile without almoft totally 
 dellruying it. Dr Chladni alfo, for want of better 
 tubes, employed thofe ufed for thermometers, and mark- 
 ed the whole and half tones by a coating of fealing-wax 
 on the under fide ; but as the wax, owing to the moi- 
 fture and vibration, often cracked and flew off, it was 
 attended with danger to the eyes. It was therefore 
 extremely difficult to give to the conftrudion of the 
 inftrument fufficient ftrength ; but this the inventor at 
 length accomplifhed, fo that his new euphon cannot be 
 injured or put out of tune either by playing or by car- 
 riage. The third inftrument was fomewhat different 
 from the firft and fecond; as the fore part, which in the 
 two former rofe upwards with an obhque angle, ftood 
 4 L 2 at
 
 E U P 
 
 [ 636 ] 
 
 E X C 
 
 Euphon, 
 Euphorbia. 
 
 XXVIII. 
 fig. r. 
 
 St rijrht anglep, fo that it could be tranfported witli 
 eafe in a particular carriage made for that purpofe. In- 
 ftead of the tlierinonieter tubes ufrd in the firll, the 
 Doftiir now employs tubes of diffcr'.-nt colours. In the 
 fecond inllrument tliofe for the whole tones were of 
 dark gree!i glafs ; but he ufed for the half tones, in 
 both, a milk white kind of glafs. In a word, the 
 euphon has fome refemblance to a fmall writing-deflc. 
 When opened, the abovementioned glafs tubes, of the 
 thicknefs of the barrel of a quill and about 16 inches 
 long, are feen in a horizontal pofition. They are wet- 
 ted with water, by means of a fponge, and ilroked with 
 the wet fingers in the direction of their length, fo that 
 the increafe of the tone depends merely on the llronger 
 or weaker prelTure, and the (lower or quicker move- 
 ment of the finger?. The number of tubes at prefent 
 is forty-two. In the back part there is a jierpendicnlar 
 founding-board divided in the middle, through which 
 the tubes pafs. It appears therefore that the euphon 
 ought not to be confidered as an altered or improved 
 harmonica, hut as a totally new and different inllru- 
 ment. In regard to fweetnefs of found, it approaches 
 very near to the harmonica; but it has fcveral advantages 
 which no unprejudiced perfon, who examines both iii- 
 llruments, will deny. 
 
 I. It is fimpler, both in regard to its conftruflion and 
 the movement necefiary to produce the found, as nei- 
 ther turning nor (lamping is required, but merely the 
 movement of the finger. 2. It produces its found 
 fpeedier ; fo that as foon as it is touched you may have 
 the tone as full as the inftrument is capable of giving 
 it ; whereas, in the harmonica, the tones, particularly 
 the lower ones, muft be made to increafe gradually. 
 3. It has more diflinftnefs in quick pafTages, becaufe 
 the tones do not refound fo long as in the harmonica, 
 where the found of one low tone is often heard when 
 you wifh only to hear the following tone. 4. The uni- 
 fon is purer than is generally the cafe in the harmonica, 
 where it is difficult to have perfeft glaffcs, which in 
 f \Fery part give like tones with mathematical exaftnefs. 
 It is however as difficult to be tuned as the harmo- 
 nica. 5. It does not affeit the nerves of the performer; 
 for a perfon fcarcely ?eels a weak agitation in the fingers; 
 v/hercas in the harmonica, particularly in concords of the 
 lf)wer notes, the agitation extends to the arms, and even 
 through the whole body of the performer. 6. The ex- 
 pence of this inftrument will be much lefs in future than 
 that of the harmonica. 7. When one of the tubes 
 breaks, or any other part is deranged, it can be foon 
 repaired, and at very little expence ; whereas, when one 
 of the glaffes of the harmonica breaks, it requires much 
 time, and is very difficult to procinc another capable of 
 giving the fame tone as the former, and which will cor- 
 refpond fufficiently with the feries of the reft. 
 
 EUPHORBIA (See Encycl.). Of this plant three 
 new fpecies were difcovered by Le Vaillant during his 
 laft travels into the interior parts of Africa. The firft, 
 which he calls the Cucumder-Euphorbia, adheres to 
 the earth no otherwife than by a few /lender roots. It 
 rifes to the height of nine or ten inches only ; and ex- 
 actly refembles a cucumber, of which it has the bent 
 fhape. It contains abundance of milky juice, which 
 appeared to him as cauftic as that of the great euphor- 
 bia. Its colour, which is a yellowifh-green, tinted with 
 3 beautiful fhade of violet towards tlie root, gives it a 
 
 veiT attradlive appearance : but woe betide the man who EupKorBia 
 fhould be tempted to eat of it ! as it is a virulent poifon. II 
 
 The fecond, to which he gave the name of the Melon- .^'"^''"""•. 
 RIBBED Euphorbia, does not rile m.ore than three orpig j, 
 four inches from the ground, to which it adheres by a 
 colleftion of fibrous roots, ifl'uing from feveral tubercle* 
 dilpoled in the manner of a crown. The ilem forms a 
 flatted globe excavated at the fumniit, and has ribs like 
 the apple which in France is called cahille blanche. 
 Thefe ribs are elevated, thick, and convex, have a 
 greenifh colour, and are marked with brown tranfverfal 
 bands. From the fummit of the ribs iffuc feveral little 
 tufts of pedunculate flowers. The third he called the 
 Caterpillar-Euphorbia, becaufe when he firll found p;- .^ 
 it, he thought he perceived on it feveral beautiful cater- 
 pillars. The defcription of it in a few words is as fol- 
 lows: From a very large tuberous root, which here and 
 there throws out a few thready fibres, ifliie feveral ilalks 
 almoft of the length of the finger: they creep along the 
 ground, are twifted, woody, dcilituie of leaves, and fur- 
 nlfhed with feveral rows of round tubercles, each guard- 
 ed by two prickles. 
 
 All thefe kinds of euphorbia are to be dreaded, the 
 laft two in particular ; becaufe being low and mixed' 
 with the herbage like muflirooms, animals, as they feed, 
 run the nn< of eating them with their pafture. Our 
 author confirms the account which has been given in 
 the Encyclopedia of the favages poifoniug the refervoirs 
 of water with this plant, in order to procure the game 
 which fhall drink of it. To effeft the death of the 
 animal, it is neceffary that the poifon reach the blood 
 and mingle with it. Yet, unconceivable as it may be, 
 the animal, though poifoned, is not the lefs wholefome 
 food, as our author lays he has experienced. However . 
 great may be the proportion of euphorbia thrown into a 
 pond of water, he is perfuaded that it never diflufes itfelf 
 through the whole mafs. It is his opinion, that the 
 poifon is a refinous juice, which, being from its nature 
 incapable of combining with water, fwims on the fur- 
 face, and theve forms a fhining greenilh oil, which with 
 a little attention may be difcerned by the naked eye 
 when the furface is fmooth. I tried (fays he) the qua- 
 lities of this oil on myfelf, taking with a ftraw, from 
 the furface of the bafin, a Cngle drop, which I put upon 
 my tongue ; and it gave me that kind of burning pain- 
 which a cauftic occafions. I then took up fome water 
 from the refervoir in the hollow of my hand, and blow, 
 ing ofl^ the oily fluid which fwam on the furface, I dip- 
 ped the end of my tongue into the rerriainder, but could 
 not perceive in it the flighteil tafte different from that 
 of water itfelf. He feeirre to think that milk is an an- 
 tidote to the poifon of euphorbia ; becaufe he fqueezcd 
 fome of the juice into a bafoQ of milk and gave it to 
 an ape, which fwallowed part of it without the leaft 
 injury. He confefles, however, that the dofe was 
 trifling. 
 
 EUSTYLE, is the beft manner of placing columns, 
 with regard to their diftance ; which, according to Vi. 
 truvius, ftiould be four modules, or two diameters and 
 a quarter. 
 
 EXCENTRIC, or Excentric Circle, in the an- 
 cient Ptolomaic aftronomy, was the very orbit of the 
 planet itfelf, which it was fuppofed to defcribe about the 
 earth, and which was conceived excentric with it ; called 
 alfo the deferent. 
 
 Inftead
 
 EXP [ 637 ] EXT 
 
 Jjcenfric Inftcad of thefe excentric circles round the earth, the aperfon of a given age may, upon an equality of chance, Etponen. 
 II moderns make the planets defcribe elliptic orbits about expeit to enjoy. tial, 
 
 tfon * '^'"^ ^^" ' '^^''"<^'' accounts for all the irregularities of their By the expeftation or (hare of life, fays Mr Simpfon ^""■^"f'' 
 ' motions, and thtir various diftauces from the earth, S:c. (5'f/f<7 Exsrc'iJ'es, p. 27^), is not here to be underftood ■ " "'^ 
 
 more juftly and naturally. that particular period winch a pcrl'on hath an equal 
 
 Ext ENTRic, or ExcenlrU Cirdt, in the new adrono- chance of lurviving ; this lad being a diflcrcnt and more 
 my, is the circle defcribed from the centre of the orbit Ample conlideration. The expeftation of a life, to init 
 of a planet, with halt the grtateft axis as a radius; or it it in the mod familiar light, may be taken as the num- 
 is the circle that circumfcribes the elliptic orbit of the ber of years at which the purchaie of an annuity, grant- 
 planet, cd upon it, without difcount of money, ought to be va- 
 EXCHANGE. See Encycl. imder that word, and hied. Which number of years will differ more or kfs 
 likewife under Bins of Exchange, where the antiquity from the period abovemeniioned, accoi-ding to the dif- 
 of fuch bills, efpecially among the Chinefe, is mention- ferent degrees of mortality to which the feveral ftaees 
 ed. In ProfefTor Bcckmann's Hiftory of Inventions the of life are incident. Thus it is much more than an. 
 reader will find an ordinance of the year i ^^94 concern- equal chance, according to the table of the probability 
 ing the acceptance of bills of exchange, and alfo copies ot the duration of life which the fame author has jriven 
 of two bills of the year 1404, which fufficiently prove us, that an infant, jull come into the world, arrives 
 that the method of tranfafting bufinefs by bills of ex- not to the age of ten years ; yet the expeftation or 
 change was fully eftablillied in Europe fo early as the /liare of life due to it, upon an average, is near twenty 
 fourteenth century; and that the prefent form and years. The reafon of which wide difference is the "-rtdt 
 terms were even then ufed. The ordinance, which was excefs of the probability of mortality in the firfl tender 
 ilTued by the city of Barcelona, decreed that bills of ex- years of life, above that rcfpefting the more mature and 
 change iTiould be accepted within twenty-four hours flronger ages. Indeed if the numbers that die at every 
 afterthey were prefented, and that the acceptance fliould age were to be the fame, the two quantities above fne- 
 be written on the back of the bill. cified would alfo be equal ; but when the faid numbers 
 But there are quellions relating to bills of exchange become continually lels and lefs, the expedtaticn muft 
 of much greater importance than their antiquity ; and of conl'equence be the greater of the two. 
 thefe queflions are not yet decided. For indance, EXPONENTIAL Calculus, the method of dif- 
 Ought a bill of exchange to be confidered by the law ferencing, or finding the fluxions of exponential quan- 
 merely as a depnfit belonging to the drawer, and fuccef- tities, and of funiming up thofe differences, or finding 
 lively confided to the remittees I or fhould it be confi- their fluents. 
 
 dercd as transferable ^rO|ft«n!)', at all times abfolutely Exponential Cur7.'f, is that whofe nature is defined 
 
 vefl:ed in the holder, whofe negleft therefore, when it or exprefTed by an exponential equation ; as the curve 
 vitiates the value, falls wholly on himfelf ? denoted by a" = y, or by x" =r y. 
 
 In a work puhlidied 1798 by ProfefTor Bufch of Exponential Equation, is one in which is contain- 
 Hamhurgh, entitled, /Idd'itions to the Theoretical and ed an exponential quantity : as the equation a^ — b, or 
 Prattical Delineation of Commerce (a), the reader will x" zzab, &c. 
 
 find fome arguments, which, to fay the leail of them, Expc^nential ^lanlity, is that whofe power is a 
 
 are certainly plauflble, to prove that bills of exchange variable quantity ; as the expreffion a^, or x^. Expo- 
 ought to be at all times confidered as the abfolute pro- nential quantities are of feveral degrees and orders ac- 
 pcrty of the holder. This theory is then applied to cording to the number of exponents or powers, one over 
 the difficult and ftill unfetlled cafe of the holder of a another. 
 
 bill having many indorfements, where the drawer, EXTRA-Constellary Stars, fuch as are not 
 drawee, and early indorfers, have all failed. It is evi- properly included in any condellation. 
 dent that, if the holder proves under each bankruptcy ExTRA-Alundune Space, is the infinite, erripty, void 
 
 the wholi* amount of the hill, he will receive much more fpace, which is by fome fuppofed to be extended be- 
 than his due. May he make his election where to yond the bounds of the univerfe, and confequently in 
 prove the whole demand,- and where to prove the refl- which there is really nothing at all. The phrafe extra- 
 due ? or ought he not (which feems moft equitable) to mundane fpace has been fo long in ufe among our bed: 
 be compelled to prove his debt againfl his immediate writers, that it is now impofTible to banidi it from the 
 predecelTor only ? — the adlgnees of that predecedor language ; and yet it has been the fource of fome ex- 
 proving in their turn, in like manner (each party once travagant miflakes. Many philofophers confider fpace 
 only), back to the drawer. This is a cafe of great as fomcthing rra/, didin6t both from body and mind ; 
 importance to difcounters, and the reader will find and no lefs a man than Dr Clarke confidered it as an 
 fome judicious obfervations on it in the Profeflbr's attribute of the Deity. Yet we think nothing more 
 ■work. evident, than that if body had never exifled, fpace would 
 
 EXEGESIS, or ExEGETicA, in algebra, is the never have been thought of; and if this be fo, extra- 
 finding, either in numbers or lines, the roots of the e- mundane fpace, indead of denoting any rca/ tiling, or 
 quation of a problem, accoi'ding as the problem is either attribute iuHnitely extended, can mean nothing more 
 numeral or geometrical. than the pojjilility of enlarging the corporeal univerfe, . 
 
 EXPECTATION of Life, in the doftrine of li.^e however widely extended it may be. See Metaphysics, , 
 annuities, is the /hare, or number of years of life, which Encycl. Part II. ch. iv. 
 
 EX. 
 
 (a) Profenbr Bufch. publillied in 1792 a work entitled A Theoretical, and PraBical Dtimeai'ion of Commerce, .
 
 Ejtremes. 
 
 EXT [ 6j 
 
 EXTRADOS, the outfide of an arch of a bridge, 
 vault, &c. See Arch in this Supfknitnt, 
 
 EXTREMES Conjunct, and Extremes Disjuna, 
 in fpherical trigonometry, are, the formt r the two circu- 
 lar parts that lie next the affumefi middle part ; and the 
 latter are the two that lie remote from the middle part. 
 Thcfe were terms applied by Lord Napier in his iiiii- 
 verial theorem for reiolving all right-angled and quad- 
 rantal fpherical triangles, and publilhed in his L"garith- 
 morum Cannnis Defcripio, ann. 1614. In this theorem, 
 Napier condcnfes into one rule, in two parts, the rules 
 for all the cafes of right angled fpherical triangles, 
 
 8 ] EXT 
 
 which had been feparately demonftrated by Pitjrctis, Entremn. 
 
 Lanfbergiua, Copernicus, Regiomontanus, and others. v — ~ 
 
 In this theorem, negleAing the right angle, Napier culls 
 the other five parts circular parts, which are, the two 
 legs about the right angle, and the complements of the 
 Other three, viz. of the hypothenufe, and the two oblique 
 angles. Then taking any three of thele five parts, one 
 of them will be in the middle between the 01 jar two, 
 and thefe two are the extremes conjunct when they are 
 immediately adjacent to that middle part, or they are 
 the extremes disjundl when they are each feparated Ironi 
 the middle one by another part. 
 
 F. 
 
 Face, TT'ACE or Facade, in architefture, is fometimes iifed 
 Falconry. -*- for the front or outward part of a building, which 
 *" V ■ immediately prcfents itfclf to the eye ; or the fide where 
 the chief entrance is, or next the ftreet, &c. 
 
 FALCONRY, is a fpecies of f])ort, about the an- 
 tiquity of which there has been feme difpute. Un- 
 der the word Hawking, Encycl. we have deduced what 
 we thought fufficient evidence of its being praftifed 
 among the Thracians, and likcwife among the Britons 
 before the invafion of this ifland by the Romans. Fla- 
 vius Blondus, however, and Laurentius Valla, both wri- 
 ters of the l5tVi century, and the latter, one of the molt 
 learned men of his time, affirm that no nation or pecjple 
 were accullomcd to catch either land or water fowls 
 with any rapacious bird trained tor the purpofe. 
 
 We were plcafed to fee our own opinion, fo different 
 from this, completely eftabliflied by the learned Lbours 
 of Profeflbr Beckmann. So early (fays he) as the time 
 of Ctefias (and he refers to the page and edition of his 
 author) hares and foxes were hunted in India by means 
 'KJi Alt:- of rapacious biids. The account of Ariftotle *, how- 
 ma/, lib. ix. ever, is ftill more to the purpofe, and more worthy of 
 ^^P" ^' notice. " In Thrace (lays he) the men go out to 
 catch birds with hawks. The men beat the reeds and 
 buflies which grow in marfhy places, In order to raife 
 the fmall birds, which the hawks purfue and drive to 
 the ground, where the fowlers kill them with poles." 
 The fame account is to be found m another book afcri- 
 bed alfo to Ariftotle ; and which appears, at any rate, 
 to be the work of an author not much younger. Re- 
 fpefting Thrace, which is fituated above Amphipolis, 
 a wonderful thing is told, which might appear incredi 
 ble to thofe who had never heard it before. It is faid 
 that boys go out into the fields, and purfue birds by 
 the affiftance of hawks. When they have found a place 
 convenient for their purpofe, they call the hawks by 
 their names, which immediately appear as foon as they 
 hear their voices, and chafe the birds into the buflies, 
 where the boys knock them down with iticks and 
 feize them. What is flill more wonderful, when thefe 
 hawks lay hold of any birds themfelves, they throw 
 them to the fowlers ; but the boys, in return, give 
 
 them fome fhare of the prey. De mirabilllus aufcultat. Palconrv. 
 cap. 128. V— y— Ij 
 
 In this pafFage, there are two additions which render 
 the circumflance ftiil more remarkable. The firil is, 
 that the falcons appeared when called by their names ; 
 and the fecond, that of their own accord they brought 
 to the fowlers whatever they caught themfelves. No- 
 thing is here wanting but the fpaniel employed to find 
 out game, the hood which is put upon the head of the 
 hawk while it flands on the hand, and the thong ufed 
 for holding it, to form a fliort dcfcription of falconry 
 as Ih'll prattifed. Our falconers, when they have taken 
 the bird from the hswk, give him, in return, a fmali 
 fliare of it ; and in the like manner the L'hracian hawks 
 receive fome part of their booty. 
 
 Other writers after Ariilotle, fuch as Antigonus, 
 Ji^A\iu, Pliny, and Phile, ha\e alio given an account of 
 this method of fowling. /Elian, who feldom relates 
 any thing without fome alteration or addition, fays, that 
 in Thrace nets were ufed, into which the birds were 
 driven by the hawks ; and in this he is followed by the 
 poet Phile. iEhan, alfo, in another place defcribts a 
 mannerof hunting with hawks in India, which, as we are 
 told by feveral travellers, is ilill pratlifed in Perfia, where 
 it is well uiiderftood, and by other eaftern nations. 
 
 The Indians (fays he) hunt hares and foxes in the 
 following manner : They do not employ dogs, but 
 eagles, crows, and, above all, kites, which they catch 
 when young, and train for that purpofe. They let 
 loofe a tame hare or fox, with a piece of flefh failened 
 to it, and fuffer thefe birds to fly after it, in order to 
 feize the flefh, which they are fond of, and which, on 
 their return, they receive as the reward of their labour. 
 When thus inftrufted to purfue their prey, they are 
 fent after wild foxes and hares in the mountains ; thefe 
 they foUow in hopes of obtaining their ufual food, and 
 foon catch them and bring them back to their mafters, 
 as we are informed by Ctefias. Inllead of the flefh, 
 however, which was fattened to the tame animals, they 
 receive as food the entrails of the wild ones which they 
 have caught. 
 
 It feems, therefore, that the Greeks received from In- 
 dia
 
 F A L [6 
 
 rii.i r.nd Thrace the firft information rcrpr£\ing the me- 
 thod of fowling with birds of prey ; but it docs not ap- 
 pear that this praftice was introduced among them at 
 a very early period. In Italy, however, it nuilt have 
 been very common, for Martial and Apuleius fpcak. of 
 it as a thing every where known : the former calls a 
 hawk the fowler's fervant. 
 
 The Profefior traces the hiftory of this art with great 
 learning down to the prcfent time. It was carried to 
 the higheft perfection at the principal courts of Europe 
 (he fays) in the 1 2th centurv, when the ladies kept 
 liawks, which were as much fondled by thufe who 
 widied to gain their favour as lap dogs are at prefent. 
 Among "le oldeft wiiters on falconry, as an art, he 
 reckons Demetrius, who about the year i 270 was phy- 
 fician to the Emperor Michatl Pjlcologus. His book, 
 written in Greek, was lirll printed at Paris in 1612 
 vith a Latin tranflation ; but its precepts (fays our au- 
 thor) would be thought of very little value at prefent. 
 For an account of tlie modern art of Falconry, fee 
 Enc\<cloj>itMa. 
 
 FALK (John Peter), known to the world as one of 
 the fcieiitinc travellers employed by the late Emprefs 
 of RulTia to explore her vail dominions, was bora in 
 Wellrogothia, a province in Sweden, about the year 
 1727. He ftudied medicine in the univerfity of Upfal, 
 and went through a courfe of botany under the cele- 
 brated Linna:us, to whofe fon he was tutor. He pub- 
 licly defended the differtation (a) which that famous 
 botanill had compofed on a new fpecies of plants, which 
 he called aflromsr'ia. 
 
 In the year 1760, he was fo deeply affefted with de- 
 preflion of fpirits, that M. de Linnc, in the view of obli- 
 gmg him to take e.xerclle and diflipation, fent him to 
 travel over the iiland of Gothland, to make a colleiSlion 
 of the plants it produces, and the various kinds of corals 
 and corallines which the fea leaves on its ihores. This 
 voyage was attended with no diminution of his dlftem- 
 )ier, which found a continual fupply of aliment in a fan- 
 guine melancholy temperament, in a too fedentary way 
 of life, and in the bad Hate of his finances. 
 
 Profeflbr Forfiael having left Upfal for Copenhagen 
 in 1760, Falk followed him thither, in the dcfign of 
 applying, by the advice of M. de Linne, to be appoint- 
 ed afliftant to M. Forflcael in his famous journey thro' 
 Arabia ; but notwithflanding all the pains that M. CE- 
 der, and feveral other men of literary reputation at Co- 
 penhagen, took in his behalf, his application failed, as 
 the focitty that were to go on that important expedi- 
 tion was already formed. OMi.^jed, with much difcon- 
 tent, to return, he herborifed as he travelled, and en- 
 riched the Flora Suecica with feveral new difcoveries. 
 
 A man in ofEce at St Peterlburgh having written to 
 M. Linnc to fend him a director for his cabinet of na- 
 tural hiftory, M. Falk accepted the poll, which led him 
 to the chair of profefTor of botany at the apothecaries 
 garden at St Peterfburgh, a place that had been long 
 ■vacant. His hypochondriac complaint dill continued 
 to torment him. When the Imperial Academy of Sci- 
 ences was preparing in 1768 the plan of its learned ex- 
 peditions, it took M. Falk into its fervice, though his 
 health was tinceitain. He was recalled in 1771 ; but 
 
 39 ] F A L 
 
 having got only to Kafan in 177.V he there obtained 
 permiflion to go and ufe the baths of Kifliar, from "" 
 which he returned again to Kafan at the end of the 
 year, wilh iiis health apparently better. 
 
 But his difeafe foon returned wilh redoubled vie. 
 Icnce. From the month of December 1773 he had 
 never quitted his bed, nor taken any other nouriihment 
 than bread dried in the Swedifli manner (kn^kebrced), 
 of which he fcarcely took once a day fome mouthfuls 
 dipped in tea. At hrft he receivid the vifits of a few 
 friends ; but afterwards denied hiniielf to them, and 
 was reduced to the (Iriftell folitude. When M. Geor- 
 gi, member of the fociety of natural hillory at BerUn, 
 who had been deiUned to afllll and relieve the profeflor 
 in the duties of his expedition, went to fee him on this 
 occafion, nothing feemed left of him but a fl-;eleton of 
 a wild and terrifying afpeft. The few words he drew 
 from him confilled in complaints, occafioned by a boll 
 of dileaies which kept his body in torture, and threw 
 him into the moll cruel lleeplefTnefs. The lafl evening 
 M. Georgi kept him company till midnight. He fpoke 
 little, and faid nothing that could give reafon to iul- 
 ptft the defign he was meditating. His hunter, and 
 at the fame time his trufty fervant, ofl'cred to fit up 
 with him the night ; but he could not be perfuaded to 
 confent. 
 
 M. Georgi being requefted the next day, March 31, 
 to come to the lodging of the unfortunate gentleman, he 
 found him lying before his bed, covered witli blood ; 
 befide him lay a razor, with which he had given hiiri- 
 felf a flight wound in the throat, the fatal plilol, and a 
 powder-horn ; all together prefenting a tremendous fpec- 
 tacle. He had put the muzzle of the piilol againil his 
 throat, and, rclling the pommel upon his brd, he dil- 
 charged the contents in fuch a manner, that the ball, 
 having gone through his head, had iluck in the ciehng. 
 His foldier had fecn him ftiU fittting up in his bed at 
 four o'clock, at which time he ufually fell into a fliort 
 (lumber. In his chamber was found a note written the 
 evening before, betraying throughout the diltiaAed 
 Rate of his mind, but nothing declaratory of his dcfign, 
 or that was of any importance. 
 
 M. Falk, like all hypochondriac perfons, was not ve- 
 ry communicative, and on certain occalions was dillruft- 
 ful. But, at the fame time, he was of a fedate temper, 
 complaifant, and upright, wliich made it a very eafy 
 matter to bear with him, and fecure to him the indul- 
 gence of all his acquaintance. His extreme fobricty 
 liaJ enabled him to make fome favings from his pay, 
 though he was very beneficent ; it was not, therefore, 
 indii'ence tiiat drove him to this aft of violence. He 
 was of a cold conftitution, preferring iolitude and quiet 
 to fociety, to the company of his friends, and to ordi- 
 nary amufements, which yet he did not (liun, except 
 in the latter period of his life. As to religion, he (hew- 
 ed on all occafions more refpeft for it than any (Irong 
 effufions of zeal. It was folely to be afcribed to the 
 violence of his dillemper, and the weaknefs of mind 
 which it brought on, that led him to put a period to 
 his days. The fate of this unfortunate fcholar was ge- 
 nerally and jullly lamented. 
 
 His papers were found in the greateft diforder. They 
 
 contain, 
 
 Falk. 
 
 (a) In the coUeAion known under the title of Linnti /inneintaUs /icadmk*.
 
 FAR 
 
 [ 640 ] 
 
 FAR 
 
 iFmncr. rontaiii, however, very ufeful and important relations. 
 '■ ' He particularly made it his bufiiiefi to inquire about 
 
 the Mirguifes, and other Tartarian nations; and as he 
 frequently remained for the lj)ace of nine months toge- 
 ther in the fame place, he was enabled to procure fatis- 
 faftory notions concerning the objefls of his invelliga- 
 tions. Tlie Imperial Academy, in 1774, appointed 
 ProfelTor Laxmann to arrange his manufcripts in order 
 for publication ; which vas done accordingly, 
 
 FARMER (Richard, D. D.), fo well known as one 
 of the comn:ientators on Shakefpeare, was a man of fuch 
 pleahng, tliough fingular manners, that we regret the 
 very iinpcrfeft account which we mull give of his life. 
 One of us, who had the pleafure of being a little known 
 to him, has be-cn fo much delighted with the natural 
 eafe and pleafantry of his conveffation, that we made 
 a'l the inquiries which we judged requilite to enable us 
 to draw up fuch a biographical (ketch of this agreeable 
 man as might be acceptable to our readers, and not un- 
 worthy of "his character ; but thcfe inquiries were made 
 in vain. Thofe to whom we applied knew little more 
 of the incidents of his life than what we had previouily 
 found in a mifcellany, of which the writers fccm to 
 confider it as a principle of duty to vilify the charafter 
 , *>f every perfon who, like Dr Farmer, is the friend of 
 
 order, and the enemy of fudden or rapid innovations. 
 To that mifcellany, therefore, we muil be beholden for 
 luany fads; but we fhall certainly copy none of its ma- 
 levolence. 
 
 Dr Farmer was born at Leicefter 1735 ; but what 
 was the ftation of his father we have not learned. Of 
 his fchool education he received part, perhaps the whole, 
 in his native town; and from fchool he was removed to 
 the univerfity of Cambridge, where he devoted himfelf 
 chiefly to claflical learning and the belles lettres. In 
 1757 he was admitted to the degree of bachelor of arts; 
 in 1760 to that of mailer of arts; a bachelor of divini- 
 ty in 1767, and a doftor of divinity in 1775; hi which 
 year he was alfo elefted mailer of Emanuel on the de- 
 ceaie of Dr Richardfon, and principal librarian on the 
 deceafe of Dr Barnardifton. 
 
 The dillurbances in America having by this time be- 
 come ferious, the univerfity of Cambridge, with num- 
 berlefs other loyal bodies, voted an addrefs to the king, 
 approving of th^ meafures adopted by government to 
 reduce the faftious colonills to their duty. The ad- 
 drefs, however, was not carried unanimoufly. It was, 
 of courfe, oppofed by Jebb, fo well known for his free 
 opinions in politics and religion, and by fome others, of 
 whom one man, a member of the caput, carried his 
 oppofition fo far, as actually to refule the key of the 
 place which contained the feal neceffary on fuch occa- 
 sions. In this emergency, Dr Farmer, who was then 
 vice-chancellor, is faid to have forced open the door 
 with a fledge-hammer; an exploit which his democrati- 
 cal biographers affedl to ridicule, by calling it his court- 
 ly teal, and the occafion ot all his fubfequent prefer- 
 ments. 
 
 If it be indeed true that he broke the door in pieces 
 with his own hands, his conduft muft be acknowledged 
 to have been not very decorous ; but if the office which 
 he filled be taken into confideration, we apprehend it 
 would be as difficult to prove that condudl clFentially 
 wrong, as to vindicate the obftinate arrogance of him 
 who occafioned it. The feal was the property- of the 
 
 univerlity, of which this outrageous fupporter of the Farmer' 
 bill of rights was but an individual member. The uni- "~~v— 
 vcrfity had refolved that it (hould be employed for a 
 certain purpofe, which it was the duty of the vice chan- 
 cellor to carry into effeift ; aad fince the fea! was re- 
 fuled to him, he had no alternative but to get poffef- 
 fion of it by force. We hope, however, that he em- 
 ployed a lervant to break the door; and, indeed, as 
 vice-chancellor, he mull have had fo many fervants at 
 his command, that it is not conceivable he would wield 
 the fledge hammer himfelf. 
 
 Some time after this he was made a prebendary of 
 Canterbury, we believe through the recommendation of 
 Lord North, then premier ; and it was at Cmterbury 
 that the writer ot this (ketch had the happincfs of be- 
 ing introduced to him, and witnelhng his hofpitality. 
 After enjoying his prebend for feveral years, he refign- 
 ed it on being preferred, by the prefent premier, to a 
 refidentiarylhip of St Paul's ; and we have reafon to 
 believe that .he declined a bilhoprie, which was offered 
 to him as a reward for the conltitutional principles 
 which he was at pains to propagate, not only in his 
 college, but, as far as his influence went, through the 
 whole univerfity. 
 
 It has been faid that the delights of the pipe and the 
 bottle in Emanuel parlour outweighed, in his edima- 
 tiou, the dazzling fplendor of the mitre ; but he had 
 other and better reafons for preferring a private to a 
 public llation. In early life, at lead before he was ad- 
 vanced in years, he had felt the power of love, and had 
 fuflered luch a difappointment as lunk deep in his mind, 
 and for a time thnatened his undevftanding. From 
 that period, though he retained his faculties entire, he 
 acquired fome peculiarilie*s of manner, of which he was 
 fo tar confciousas to be fenfible that they would hardly 
 become the charaiiier of a bilhop: being likewife ftrong- 
 ly attached to dramatic entertainments, which, if we 
 miilake not, the Englifli bifhops never witncfs, and de- 
 lighting in clubs, where h,e could have rational conver- 
 fation without llate or ceremony of any kind — he very 
 wifely preferred his relidentiarylhip to the higheil dig- 
 nity in the church. At the time of his death, which 
 happened in the autum of 1797, he was a fellow of the 
 Royal and Antiquarian Societies, mafter of Emanuel 
 college, principal librarian of the public library in the 
 univerfity, one of the canons relidentiary of St Paul's, 
 chancellor of the diocefe of Lichfield and Coventry, 
 and prebendary of Worceller. 
 
 Tliough a good claffical fcholar, Dr Farmer has been 
 celebrated only for that kind of literature which is con- 
 neCled with the Englifh drama ; and having a ftrong 
 predileftion for old Englilh writers, he ranked high 
 among the commentators upon Shakefpeare. His ' Ef- 
 fay upon the Learning of Shakefpeare,' dedicated to 
 Mr Cradock, the intelligent refident of Gumley-Hall 
 in Lcicellerlhire, has paffed through feveral editions. 
 This elTay was, in faft, the firft foundation of his fame, 
 which an unconquerable indolence prevented him from 
 carrying to that height to which the exercife of his li- 
 terary talents could not have failed to raife it. So great 
 indeed was his love of eafe, that after having announced 
 for fubfcriptions a hillory of Leicellerlliire, and adtual- 
 ly begun to print it, rather than fubmit to the fatigue 
 of carrying it through the prefs, he returned the fub- 
 fcriptions, and prefented the MSS. and plates to Mr 
 
 Nichols,
 
 FAR 
 
 t 641 1 
 
 FAS 
 
 Nichols, the rcfpeiSable printer of the Gentleman's 
 Magazine, who has fincc carried on the hiftory with a 
 degree of fpirit, ability, and induftry, perhaps unprece- 
 dented in this department of literatnre. 
 
 Indolence and the love of cafe were indeed the Doc- 
 tor's chief charaAerillics ; and to them, with the dif- 
 appointment already mentioned, may be attributed a 
 want of propriety in his external appearance, and in 
 the ufual forms of behaviour belonging to his ftation. 
 The prevailing features of his charadler diftinguiihed 
 
 individual ; and, with all his eccentricities, his death 
 was a lofs to that learned body, which, in the opinion 
 of fonie of its members, will not foon be made up. 
 
 A fliort time before his death, his charadler was thus 
 juitly and ably drawn by the celebrated Dr Parr: 
 
 " Of any undue partiality towards the matter of 
 Emsnuel College, I (haU not be fufpeftcd by thofe per- 
 fons who know how little his fentiments accord with 
 mine, upon fome ecclefiaftical, and many political mat- 
 ters. From rooted principle and ancient habit he is a 
 
 thcmfcKcs by fevcral oddities : There were three things, tory ; I am a whig ; and we have both of us too much 
 
 it was faid, which the mailer of Emanuel loved, -vrz. 
 old port, old clothes, and old books ; and three things 
 which no one could perfuade him to perforin, viz. to 
 rife in the morning, to go to bed at night, and to fettle 
 an account. When in Cambridge, if an old houfe 
 were pulled down, the mailer of Emanuel was always 
 there in an old blue great coat, and a rufty hat. When 
 in London, he was fure to be found in the fame garb 
 nt an old bookllall, or (landing at the corner of a dirty 
 lane, poring through his glafs at an old play-bill. 
 
 This charafter is not drawn by a friendly pencil ; 
 but it is neverthelefs not unjuft. His inattention to 
 the common decencies of drefs and behaviour was noto- 
 rious, inlomuch that, in the company of ftrangers, the 
 eccentricity of his appearance and of his manners made 
 him fometimes be taken for a perfon half crazed. The 
 writer of this flcetch faw him one morning at Canter- 
 bury drefled in (lockings of unbleached thread, brown 
 breeches, and a wig not worth a ihilling ; and when 
 a brother prebendary of his, remarkable for elegance of 
 manners, and propriety of drefs, put him in mind that 
 they were to attend on the archbilhop, Dr Farmer re- 
 plied, that it had totally efcaped him ; but he went 
 home, and drefled himfelf like a clergyman. That he 
 fat late reading, and occahonally drinking brandy and 
 water, cannot be denied ; and it is literally true, that 
 he could not eafily be prevailed upon to fettle his ac- 
 counts. His accounts with fome of his pupils, when 
 tutor of his college, were never fettled to the day of 
 his death ; and the young gentlemen not unfrcquently 
 took advantage of this \inconquerable indolence to bor- 
 row of him confiderable fums, well knowing that there 
 was little chance of a demand being ever made upon 
 their parents. One gentleman, in particular, told a 
 friend of ours, who was himfelf a penfioner of Emanuel, 
 that when he left that college, he was near fifty pounds 
 in debt to Dr Farmer; " a debt (faid he) which I 
 would have fcrupuloufly paid^ but, after repeated foli- 
 citations, I could get no bill from him." 
 
 Having been a warm partizan of government du- 
 ring the American war, it will readily be believed that 
 Dr Farmer was the determined enemy of levellers and 
 anarchifts. He was fuch a whig as thofe who placed 
 King William on the throne ; and of courfe deemed a 
 violent tory by our prefent republicans, of whom, to 
 fay the truth, he could h.ardly fpeak with temper. By 
 his enemies he is admitted to have been a man of gene- 
 rofity. As he obtained money eafily, fo he parted with 
 It eafily. W^hilft he was always ready to relieve diftrefs, 
 his bounty was frequently bellowed on the patronage 
 of learned men and learned publications. He was, ac- 
 cordingly, a favourite with all good men who knew 
 him. In his'own college he was adored ; in the univer- 
 fity he had, for many years, more influence than any other 
 Suppi.. Vol. I, Part II. 
 
 confidence in each other, and too much refpeft for our- 
 felves, to diffemblc what we think, upon any grounds, 
 or to any extent. Let me then do him the juilice which, 
 I am fure, that he will ever be ready to do to me. His 
 knowledge is various, extenfive, and recondite. With 
 much feeming negligence, and periiaps, in later years, 
 fome real relaxation, he underftands more, and remem- 
 bers more, about common and uncommon lubjeils of 
 literature, than many of thofe who would be thought 
 to read all the day and meditate half the night. In 
 quicknefs of apprehenfion, and acutencfs of dilcrimina- 
 tion, I have not often feen his equal. Through many 
 a convivial hour have I been charmed by his vivacity : 
 and upon his genius I have reflected, in many a ierious 
 moment, with pleafure, with admiration, but not with- 
 out regret that he has never concentrated and exerted 
 all the great powers of his mind in fome great work, 
 upon fome great fubjeft. Of his liberality in patroni- 
 fing learned men I could point out numerous inllances. 
 Without the fmalleil propenfities to avarice, he poflef- 
 fes a large income ; ar.d, without the mean fubmiffion 
 of dependence, he is rifen to a high flation. His am- 
 bition, if he has any, is without infolence ; his munifi- 
 cence is without ollentation ; his wit is without acri- 
 mony ; and his learning without pedantry." 
 
 FASCINATION, the art of bewitching, enchant- 
 ment, an unfeen inexplicable influence Under the 
 title Serpens {^Encycl. n° 22.) we have mentioned fe- 
 veral inftances of the fafcinating power of the rattle- 
 fnake, which were related by men of charafter, and 
 certainly gained fome degree of credit among men of 
 fcience. In Vaillant's New Travels into the Interior 
 Parts of Africa, an account is given of finiilar inllances 
 of fafcination by African fervants, fome of them wit- 
 nefled by himfelf, and others reported to him by men 
 of veracity. 
 
 On the confines of the European colony, at a placf 
 called Sivnrt-larid, our traveller faw a ilirike on the 
 branch of a tree, tremble as if in convulfions, whilil it 
 uttered the molt piercing cries of dillrefs. Clufer at- 
 tention led him to difcover upon the next branch of 
 the fame tree a large ferpent, that, with llretchedout 
 neck, and fiery eyes, though perfedlly dill, was gazing 
 on the poor animal. He fliot the ferpent ; but, in the 
 mean time, the bird had died. Having meafurcd the 
 diftance between the place where the flirike was feen 
 in convulfions and that occupied by the ferpent when 
 it was (hot, he found it to be three feet and a half ; 
 which convinced him and his attendants that the bird 
 had not died cither from the bite or the poilon of its ene- 
 my. Indeed he ftripped it before the whole company, 
 and made them obferve that it was untouched, and had 
 not received the flighteft wound. — In another diilrift 
 of Africa, during the courfe of the fame travels, he 
 4 M law
 
 Fardna- 
 
 tion 
 
 FAS [ 642 ] ^\^ ^ 
 
 faw a fmall moufe die in conviiUions. occnfioned by the " The fnake, whatever its fpecies iray be, lying at F-rda. 
 
 fafcinatliiff power of a ferpent, at the dillance of two the boltom of the tree or bufli upon wliich the bin! '" ' "■ 
 
 ' yards from it ; and when he confulted his Hottentots or fquirrel fits, fixes its eyer, upon the animal it dcfigns ' 
 
 upon this incident, they cxjireffed, he fays, no fort of to fafcinate or enchant. No fooner is this done, than 
 
 alloiiilhment, but aifured him that the ferpent had the the unhappy animal is unable to make its cfcape. It 
 
 faculty of attrafting and fafcinating fuch animals as it now begins to utter a moil piteous^cry, which is well 
 
 wiflied to devour. ~ known by thofe who hear it, and underlUnd the whole 
 
 We have already had occafion to remark how regard- machinery of the bufiuefs, to be the cry of a creature en- 
 
 lefs this autlior is of inconfiftencies in his narrative ; and chanted. If it is a fquirrel, it runs up the tree for a (hort 
 
 we perceive fomething like an inconfiftency in the nar- dillance, comes down again, then runs up, and, laftly, 
 
 ratives before us. Though his Hottentots expreffed comes lower down. « On that occafion (fays an honell, 
 
 no furprife at the fafcination of the moiife, and decla- but rather credulous writer*), it has been obfcrved, that « Pr^./rfor 
 
 red that nothing was more common, he fiiys expreMy, the fquirrel always goes down more than it goes up.' Pucr Kalm. 
 
 that to thofe who witncfl'ed the fafcination of the lh\ike, The fnake Hill continues at the root of the tree, with 
 
 the facl appeared fo extraordinary, that they couKl its eyes fixed on the fquirrel, with which its attention 
 
 hardly believe it, even after they had feen it. is fo entirely taken up, that a perfon accidentally ap- 
 
 The moft wonderful inftance of fafcination which preaching, may make a confiderable noife without the 
 
 we have anywhere met with, was that of a Captain in fnake's fo nuch as turning about. The fquirrel, as 
 
 the Dutch fervice at the Cape, who, after alFuring our before mentioned, comes always lower, and at lad leaps 
 
 traveller that it is an event which happens very fre- down to the fnake, vihofe mouth is already wide open 
 
 quentiv, proceeded thus : " My teftimony ought to for its reception. The poor little animal then, with a 
 
 have the more weight, as I had once nearly become my- piteous cry, runs into the fnake's jaws, and is fwallow- 
 
 felf a viclim to this fafcination. While in garrifon at cd at once, if it be not too big ; but if its fize will not 
 
 Ceylon, and amufing myfelf, like you, in hunting in a allow it to be fwallowed at once, the fnake licks it fe- 
 
 marfh, I was, in the courfe of my fport, fuddenly fei- veral times with its tongue, and fmoothens it, and by 
 
 zed with a convulfive and involuntary trembling, diffe- 
 
 veral times with its tongue, and fmoothens it, 
 that means makes it fit for fwallcwing." 
 rent from any thing I had ever experienced, and at the From Dr Barton's memoir, it appears that the North 
 fame time was llrongly attracted, and in fpite of myfelf, American Indians are by no means of one opinion re- 
 to a particular fpot of the marfh. Direfting my eyes fpefting the fafcinating power of the rattle-fiiake. Some 
 to this fpot, I beheld, with feelings of horror, a fer- intelligent friends of his, well acquainted with the man- 
 pent of an enormous fize, whofe look inilantly pierced ners, religious opinions, and fuperflltious prejudices of 
 me. Having, however, not yet loft all power of motion, thofe people, informed him, that though they had of- 
 I embraced the opportunity before it was too late, and ten heard the Indians fpeak of the ingenuity of thefe 
 faluted the reptile with the contents of my fufee. The reptiles in catching birds, fquirrels, &c. they did not 
 report was a talifman that broke the charm. All at recolleft having ever heard them fay that fnakes charm 
 once, as if by a miracle, my convulfion ceafed ; I felt birds. On tlie other hand, however, a Mohegan In- 
 mvfelf able to flv ; and the only inconvenience of this dian told the Doftor himfclf, that the Indians are of 
 extraordinary adventure was a cold fneat, which was opinion, that the rattle-fnake can charm, or betwitch, 
 doubtlefs the eflecl of my fear, and of the violent agi- fquirrels and birds, and that it does this with its rattle, 
 tation mv fenfes had undergone." which it (hakes, thereby inviting the animals to defcend 
 
 This inftance of fafcination differs in one very mate- from the trees, after which they are eafily caught. Ac- 
 rial circumftance from the two fomewhat fimibr inftan- cording to this Indian, his countrymen do not think 
 ces mentioned in the Encycloptdia. In both thefe, that the fnake, in any manner, acco.xplifties the bufi- 
 the eyes of the perfons fafcinated were fixed on the nefs with its eyes. A Choktah Indian allured the Doc- 
 eyes of the fnake ; but her^ the Dutch Captain was tor, that the rattle fnake does charm birds, &c. ; but 
 ftronglv attrafted towards the ferpent before he faw, or he was honeft enough to confefs, that he did not know 
 even'fufpeaed, that fo formidable an enemy was in his in what manner it docs it. The interpreter,^ through 
 neighbourhood. If the ftorj' therefore be true, the ef- whom the converfation was carried on with this Indian, 
 feft which he defcribes could not poflibly have been faid that the fnake charms by means of its rattle, 
 the effe6t of fear, but of fome unfeen influence on his This opinion of the interpreter was the opinion of 
 whole nervous fvftem. Dr Mead. That eminent naturalill, controverting. 
 
 The fubjeft has of late attracted tlie attention of about fifty years ago, the common opinion, that Provi- 
 
 men of fcience, whofe local fituation gives them an op- dence has furnirtied the rattle-fnake with its rattle to 
 
 portunity of making experiments upon dlflFerent fer- give warning to travellers, was the firft who afferted 
 
 pents, with a view to afcertain whether they really pof- that this fingular appendage is given to the animal to 
 
 fefs or not this moft unaccountable of all powers. In terrify fquirrels and Imall birds, which are then fo ftu- 
 
 the year 1796 was printed at Philadelphia, a Memoir pified by the fight of fo formidable an enemy, that at 
 
 concerning the Fafcinnting Faculty luhkh has been afcri- length they drop down, and become its prey ;^and that 
 
 bed to the Rattle fnake, and other American Serpents, by this is what the Indians call fafcination. The fame 
 
 Benjamin Smith Barton, M. D. ProfelTor of natural opinion has been adopted by profeftbr Blumenbach of 
 
 biftory and botany in the univcrfity of Pennfylvania. In Gottingen, who, in his Manual of Natural Hiftoiy, 
 
 this memoir, the manner in which the fafcinating. power thus expreffes himfelf on this curious fubjeft : 
 is fuppofed to be exerted is tluos Hated by the inger.i- " That fquirrels, fmall birds, &c. fall down fponta- 
 
 " ~ neoufly from trees into the mouth of the rattle-fnake, 
 
 lyintT 
 
 ous profeffor :
 
 Fiffi'na. 1 
 
 yivg 
 
 bfl.i 
 
 FAS r 
 
 them, 13 an undiTputed faft ; and ia 
 
 ^"'"_ Icfs fiirpriiing, as the like phenomena have been re- 
 ""^ marked in regar<l to other fnakes, and alfo toads, hawks, 
 
 and eats; all of which, in certain circunillances, as ap- 
 pears, have the power of drawing towards them fmall 
 animals, merely by fixing their eyes (ledfailly on them. 
 In regard to the raltle-fnake, this cffetl is produced by 
 the rattle in its tail, the hilFing noile of which makes 
 fquirrels, &e. whether through curiofity, millake, or 
 terror, feem to approach the animal as it were fponta- 
 iieoufly. At any rate, I know, from the information 
 of intelligent eye-witneffts, that it is a common ilrata- 
 gcm of tlie young favages in America to conceal them- 
 felvcs in ihe bulhes, where they imitate the hilhng noife 
 C'f the rattle- Inake, and by thcle means attracil fquirrels, 
 which they are then enabled to catch." 
 
 To this opinion Dr Barton oppofcs an infuperable 
 objeftion. It is, that this fafciiiating power is by no 
 incans peculiar to the rattle-fiake. With regard to 
 the llratagcm of the favages, he thinks that l)r Blu- 
 menbach has been impofed upon ; as neither lie, nor 
 any other perfon of whom he made the inquiry, ever 
 heard of fuch a ilratagem. The young Indians, he 
 fays, place a reed crols-wife in their mouth, and by a 
 tremulous motion of the lips, imitate the cry of young 
 birds; by which means they entice the old ones, fo that 
 they can eafily (hoot them : And this praflice may have 
 given rife to the (lory of their imitating the hiffing 
 noiTe of the rattle-fnake. 
 
 Some have fuppoled that ferpents, under certain cir- 
 cumftances, emit from their bodies a ftupifying vapour ; 
 and that it is this vapour which produces the efFedl 
 called fafciti'-tion : But againft this opinion Dr Barton 
 alleges the following argtuiients : " 1 know, indeed 
 (fays lie), that in feme of the larger fpecies of ferpents, 
 inhabiting South America and other countries, there 
 is evolved in the ftomacli, during the long and tedious 
 procefs of digedion in thefe animals, a vapour or a 
 gas, whofe odour is iiitenfely fetid. I have not, how- 
 ever, found that this is the cafe with the rattle-fnake, 
 and other North American ferpents, that I have exa. 
 mined. But my own oblervations on this head have 
 not been very minute. I have made inquiry of fome per- 
 fons (whofe prejudices againd the ferpent tribe are not 
 fo powerful as my own), who are not afraid to put the 
 heads and necks <if the black fnake, and other ferpents 
 that are deftitute of venemous fangs, into their mouths, 
 and have been informed, that they never perceived any 
 difagreeable fnicll to proceed from the breath of thefe 
 animals. I have been prefent at the opening of a box 
 which contained a number of living ferpents ; and al- 
 though the box had been fo clofe as to admit but a 
 very fmall quantity of frefh air, although the obferva- 
 tion was made in a fmall warm room, I did not per- 
 ceive any peculiarly dilagreeable effluvium to arife frorrj 
 the bodies of thefe animals. I am, moreover, inform- 
 limcrican '^^ ^Y ^ member of this fociety *, who has, for a confi- 
 i/o/hfiical derahle time, had a rattle-fnake under his immediate 
 "O'- care, that he has not obferved that any difagreeable va- 
 pour proceeds from this reptile. On the other hand, 
 however, it is aflerted by fome creditable perfonsof my 
 acquaintance, that a moft offenfive odour, fimilar to 
 that of flefh in the laft ftage of putrefaftion, is conti- 
 nually emanating from every part of the rattle-fnake, 
 and fome other fpecies of ferpents. This odour ex- 
 
 Fafcira. 
 tioii. 
 
 643 ] FAS 
 
 the tcndfl, undtr certain clrcumflancci, to a confiderable 
 didance tVom the body of the animal. Mr William 
 Bartrain afl'ures me, that he has obferved ' horfes to be ' 
 lenfiblc of, and greatly agitated by it, at the ditlancc of 
 forty or tifty yards from the fnake. They fiiewed (he 
 fays) their abhorrence by fnorting, winnowing, and 
 llarting from the road, endeavouring to throw their ri- 
 ders, in order to make their efcape." This fad, rela- 
 ted by a man of rigid veracity, is extremely curious ; 
 and, in an efpecial manner, deferves the attention of 
 thofe writers who imagine that this fetid emanation 
 from ferpents is capable of alfec^'ling birds, at fmall dif- 
 tances, with a kind of afphyxy. It even g'lves/ome co- 
 lour of probability to the Itory related by Metrodorus, 
 and preferved in the Natural Hillory of I'liny *." * Lit. jg, 
 
 Some experiments, however, which were made in'^''/''4 
 Philadelphia a little before the Doftor conipofcd his 
 incmoir, feem to have been decifive not only as to the 
 fetor, but as to every thing which rcfenibles fafcina- 
 tion in the rattle-fnake. Birds which were put into a 
 cage which contained a rattle-fnake, flew or ran from 
 the reptile, as though they were fenfible of the dai.ver 
 to which they were expofed. The fnake made many 
 attempts to catch the birds, but could feldom fucceed. 
 When a dead bird was thrown into the cage, the fnake 
 devoured it immediately. He foon caught and devour- 
 ed a living mole, an aninial much inorc nuggi(h than 
 the bird. Df Barton himfelf faw a fnow-bird (fee Em- 
 BERizE, Encycl.) in a cage with a large rattle Inake. 
 The little animal had been thus imprifoned for feveral 
 hours when he firll faw it, but it exhibited no (igns of 
 fear. It ho])ped about from the floor of the cage to 
 its rocif, and frequently perched on the fnake's back. 
 Its chirp WHS nowife tremulous, but perfettly natural. 
 It ate the feeds which were put into the cage ; and by 
 its whole actions moll evidently demonllrated that its 
 fituation was not uneafy. 
 
 Having thus difpofed of the doftrines of fome of his 
 predeceffors, Dr Barton proceeds to fay : " The refult 
 of not a little attention to the fnbjeCl has taught me, 
 that there is but one wonder in the inifinefs ; — the won- 
 der that the ftory (hould ever have been believed by a 
 man of underdanding and of obfervation." Fafcina- 
 tion, we arc informed, is almod entirely limited to birds 
 that build low, and " in almod every indanee, I found 
 that the fuppofed fafcinating faculty of the Icrpent wi.i 
 exerted upon the birds at the particular feafon of their 
 laying their eggs, of their hatching, or of their rearin •>■ 
 their young, dill tender and defcncelefs. I now began 
 to fufpett that the cries and fears of birds fuppofed to 
 be fafcinated originated in an endeavour to protect their 
 neft or young. My inquiries have convinced me that 
 this is the cafe." 
 
 The rattle-fnake, which is the lazleft of all the fer^ 
 pent tribe, never moves in a fpiral manner or climbs up 
 trees ; but the black-fnake, and fome other fpecies of 
 the genus coluber, do. When impelled bv hunger, and 
 incapable of fatisfying it by the capture of animals on the 
 ground, they begin to glide up trees or bufhcs upon 
 which a bird has its ned. The bird is not ignorant of 
 the ferpent's objedl. She leaves her ned, whether it 
 contains eggs or young ones, and endeavours to oppofe 
 the reptile's progrefs. In doing this, (he is aftuated by 
 the ftrength of her inftinAive attachmeot to hei eggs, 
 or of affeftion to her young. Her cry is melancholy, 
 3 M z her
 
 F E 
 
 her motion!^ are tremulous. 
 
 moll imminent danger. Sometimes fiie approaches fo 
 near the reptile that he feizes her as his prey. But 
 this is far from being univerfally the cafe. Often Ihe com- 
 pels the ferpent to leave the tree, and then returns to 
 her ne(l. 
 
 It is a well known faft, that among fome fpecles of 
 birds, the female, at a certain period, is accuftomed to 
 compel the young ones to leave the neft ; that is, when 
 the young have acquired fo much ftrcngth that thev 
 are no longer entitled to all her care. But they ftill 
 claim fome of her care. Their flights arc aukward, 
 and foon broken by fatigue. They fall to the ground, 
 where they are frequently expofed to the attacks of the 
 ferptnt, wiu'ch attempts to devour them. In this fitua- 
 tion of affairs, the mother will place herfelf upon a branch 
 of a tree or bufli, in the vicinity of the ierpcnt. .She will 
 dart upon the ferpent, in order to prevent the deitruc- 
 tion of her young : but fear, the inflinft of felfpreier- 
 vation, will compel her to retire. She leaves the fer- 
 pent, however, but for a rtiort time, and then returns 
 again. Oftentimes (lie prevents the deilruftion of her 
 voung, attacking the fnake with her wings, her beak, 
 or her claws. Should the reptile fucteed in capturing 
 the young, tlie mother is expofed to leis danger ; for, 
 whilft engaged in fwallowing them, he has neither in- 
 clination nor power to feize upon the old one. But 
 the appetite of the ferpent tribe is great : the capacity 
 of their ftomachs is not lefs fo. The danger of the 
 mother is at hand when the young are devoured. The 
 fnake feizes upon her : and thi^ is the cataflrophe, which 
 crowns the tale of fafcination ! 
 
 FAUSSE Braye, in fortification, an elevation of 
 earth, about three feet above the level ground, round 
 the foot of the rampart on the outfidc, defended by a 
 parapet about four or five fathoms diftant from the up- 
 per parapet, which parts it from the berme and the 
 edge of the ditch. The fauffe-braye Is the fame with 
 what is otherwife called Chem'm des rondos, and Bajfe en- 
 ceinte ; and its ufe is for the defence of the ditch. 
 
 FEATHER-EDGED, is a term ufed by workmen for 
 fuch boards as are thicker on one edge^or fide, than on 
 the other. 
 
 FELTING, the method of working up wool or 
 hair into a kind of clolh or Huff, without either fpin- 
 ning or weaving it. In this country felting it little 
 praftifed except in hat-making ; and as nine-tenths of 
 thofe who are errployed in the manufafturing of hats 
 know nothing of the principles on which they proceed, 
 the following oblervations on the mechanifm of felting 
 muft to them be both agreeable and ufeful. They are 
 by M. Monge, and taken from the AnnaUs de Chemie. 
 
 If we examine, in a microfcope, human hair, wool, 
 the hair of a rabbit, hare, beaver, &c. however great 
 the magnifying power of the inftrument may be, the 
 furface of each hair appears perfcftly fmooth and even ; 
 or at lead, if any inequalities are to be perceived, they 
 feem rather to arife from fome difference in the colour 
 and tranfparency of particular parts of thefe fubftances 
 than from the irregularity of their furfaces ; for their 
 image, when viewed by a folar microfcope, is termina- 
 ted by even lines, without any roughnels. The fur- 
 face of thefe objefts, however, is by no means fmooth; 
 on the contrar)', it appears to be formed either of la- 
 tntlle which cover each other from the root to the 
 
 L [ 644 } F E L 
 
 She expofes herfelf to the point, pretty much in the fame manner as the fcales of Fcltir.g^ 
 
 a fidi cover the animal from the head to the tail ; or, » 
 more probably, of zones placed one over the other, like 
 what is obfcrved in the ftrufture of horns : to this con- 
 formation it is that the fubftances here treated of owe 
 their difpofitinn to what is called felting. 
 
 If, with one hand, we take hold of a hair by the 
 root, and draw it between two fingers of the other, 
 fiom the root towards the point, we are hardly fenfible 
 of any friflion or refiftance, nor can we diftinguifh any 
 found ; but if, on the contrary, we hold the hair at the 
 point, and draw it between the fingers, from the point 
 toward the root, we are fenfible of a refiftance which 
 did not exift in the former cafe ; a fort of tremulous 
 motion is likewife produced, which is not only per- 
 ceptible to the touch, but may alfo be diftinguifhed by 
 the ear. 
 
 It is evident, therefore, that the texture of the fur- 
 face of a hair is not the fame from the root towards the 
 point as from the point towards the root ; and that a 
 hair, when grafped, muft offer more refiftance in Aiding 
 or moving progrelTively towards the point than towards 
 the root ; x. e. in moving with its point foremoft. 
 
 If a hair, after being taken hold of by the fore-fin- 
 ger and thumb, be rubbed by them, in the longitudinal 
 direftion of the hair, a progrefiive motion takes place, 
 and this motion is always towards the root. This effedt 
 does not at all depend on the nature of the llvin of the 
 fingers or its texture ; for if the hair be turned, fo that 
 the point is placed where the root was, the movement 
 then becomes contrary to what it was before; that is to 
 fay, it is always direfted towards the root. 
 
 What is obferved, in the above inttance, is entirely 
 analogous to what happens when country children, by 
 way of fport, introduce an ear of rye or barley between 
 the wrift and the Ihirt, the points of the beards of which 
 are diieAed outwards. By the various motions of the 
 arm, this ear, fometiires catching againft the (hirt, 
 fomctimes againft the Ikin, takes a progreflive motion 
 backwards, and foon gets up to the arm- pit. It is 
 very clear that this effcft is produced by the beards of 
 the ear, and indeed chiefly by the afperities upon thofe 
 beards ; which, being all direfted towards the point, 
 do not permit the ear to move in any other direftion 
 than towards that part to which it was united to the 
 ftalk. There is no doubt that it is the fame with re- 
 fpeft to hair ; and that its furface is befet with afperi- 
 ties, which, being laid one upon the other, and turned 
 towards the points, permit no motion but towards the 
 root. 
 
 A tight knot, made in the middle of a hair, is very 
 difficult to untie by the ufual means, on account of the 
 extreme thinnefs of the hair ; but if we place the hair 
 in the bend of the hand, fo that the knot is in a line 
 with the little finger, and, after grafping the hair by 
 clofing the hand, we ftrike the fift feveral times againft 
 the knee, the afperities of one end of the hair being 
 now in a contrary direftion to thofe of the other, each . 
 of the ends recedes a little, one of them one way, the 
 other the contrary way ; the knot is thereby opened,, 
 and, by introducing a pin into the eye which is formed, 
 it is very eafy to finifh untying it. 
 
 Thefe obfervations, which it would be ufelefs to mul* 
 tiply, relate to long hair, that having been taken as an 
 example ; but they apply with equal propriety to woo! j 
 
 furs.
 
 F E L 
 
 fiirs, and in general to every kind of animal hair 
 ■' fuvface of all thefe is therefore to be confidered as com- 
 pofed of hard lamelU placed one upon another, like 
 tiles, from the root to the point ; which LimelU allow 
 the progrefTive motion of the hair towards the root, but 
 prevent a iimiiar motion towards the point. 
 
 From what has been faid, it is eafy to explain why 
 the contaft of woollen (luffs Is rough to the (l<in, while 
 that of linen or cotton cloths is fmooth ; the reafon is, 
 the afperities upon the furface of the fibres of the wool 
 (notwithftanding the flexibility of each particular fibre), 
 by fixing themfelves in the flcln, produce a difagreeable 
 fenfation, at leall: till we are accuftomed to it ; where- 
 as the furface of the fibres of hemp or flax, of which 
 linen is made, being perfedlly fmooth, do not caufe any 
 fuch fenfation. It is alfo evident, that the injury arifing 
 to wounds or fores, from the application of wool, does 
 not proceed from any chemical property, but is occa- 
 fioned folely by the conformation of the furface of the 
 fibres : the afperities of which attach themfelves to the 
 raw and expofed flefh, which they ftimulate and irritate 
 to fuch a degree as to produce inflammation. 
 
 This conformation is the principal caufe of that dlf- 
 pofition to what is called felting, which the hair of all 
 animals in general poflefles. 
 
 The hatter, by ftriking the wool with the ftring of 
 his bow (fee Hat, Encyc!.), feparates the hairs from 
 each other, and caufes them to fpring up in the air ; 
 the hairs fall again on the table, in all poflible direc- 
 tions, fo as to form a layer of a certain thicknefs, and 
 the workman covers them with a cloth, which he prefies 
 with his hands, moving them backwards and forwards 
 in various direftions. This pren"ure brings the hairs 
 againil each other, and multiplies their points of con- 
 ta£l ; the agitation of them gives to each hair a pro- 
 greffive motion toward the root ; by means of this mo- 
 tion the hairs are twilled together, and the lamella of 
 each hair, by fixing themfelves to thole of other hairs 
 which happen to be direfted the contrary way, keep 
 the whole in that compaA ftate which the prcffure 
 makes It acquire. In proportion as the mafs becomes 
 compafl, the prefTure of the hands (liould be increafed ; 
 not only to make it more clofe, but alfo to keep up the 
 progreliive motion and twilling of the hairs, which then 
 takes place with greater difficulty : but tliroughout the 
 whole of this operation, the hairs fix ihemfelvcs only 
 to each other, and not to the cloth with which tliey 
 are covered, the fibres of which, as we have already 
 faid, are fmooth, and" have not that difpofition to felt- 
 ing which we have defcrlbed above. 
 
 It may not be amifs here to explain why that hair 
 •which is intended for making hats is always cut ofF^ 
 with a fharp inllvument (although that cannot be done 
 without lofing a part of its length), and not plucked 
 out by the roots, 2S might be done after foftenlng the: 
 fkin: the reafon is, the bulb of the hair, which in the lat- 
 ter cafe would come out with it, v/ould render that end 
 ■which was fixed in the (Icin thick and obtufe : and it 
 would confequently be lefs difpofed to introduce itfclf 
 among the contiguous hairs, and to contribute by its 
 progrefs motion to the contexture of the mafs. 
 
 The above deferibed conformation of the furface of 
 hairs and wool is not the only caufe which produces 
 their difpofition to felting. It is not fufficient that 
 every hair pofleffes the forementioncd tendency to move 
 
 [ 645 "J F E R 
 
 The progreffively towards the root, and that the inclined la- Feltmfr, 
 mella, by hooking themfelves to each other, prefervethc retgvflun. 
 mafs in that ilate to which comprcfiion has Iw'ought it ; 
 but it is alfo neceffary that the hairs (liould not be 
 ftraight, like needles ; if they were fo, prcffing and rub- 
 bing them together would merely caufe them to conti- 
 nue their progrelTive motion, without changing their 
 direftion ; and the eflfeft of thofe operations would only 
 be to make thfm move from the centre of the mafs, 
 without producing any compaftnefs in it. Every hair 
 muft therefore be twlftcd or curled in fuch a manner 
 that the extremity which is towards the root may be 
 dllpofed to change its direiSIon perpetually, to twifl 
 itlelf about other hairs, and to incline towards itfelf a- 
 galn, in cafe it fhould be determined thereto by any 
 change in the pofitlon of the reft of its length. It is 
 becaufe wool has naturally this Crooked form that it is 
 fo proper for felting, and that it may be made ufe of 
 for that purpofe without undergoing any previous pre- 
 paration. 
 
 But the hairs of the beaver, the rabbit, the hare, &c. 
 being naturally ftraight, cannot be employed alone in 
 felting till they have undergone a preliminary operation ; 
 which confifts in rubbing or combing them, before they 
 are taken off the (kin, with a brufh dipped in a folution 
 of mercury in aquafortis (nitric acid). This liquor, 
 a&ing only on one fide of the fubllance of the hairs, 
 changes their direftion from a right line, and gives 
 them that difpofition to felting which wool naturally 
 poffeffes. 
 
 When the hairs are not intended to enter into the 
 body of the mafs, but are only to be employed in ma- 
 king a fort of external coating, fuch as is fometinics 
 given to the outer furface of hats, the operation juft 
 mentioned need not be performed ; but the felt on 
 which they are to be fixed being finifhed ; the hair ir, 
 uniformly fpread upon the furface tovvlnch the coating 
 is to be applied ; and, being covered with a cloth, it is 
 preffed with the hands, and agitated l"or a certain time. 
 By thefe means, the hairs introduce "iiemfelves, by the 
 root, a certain depth into the felt, and are there fixed 
 by their lamelLs in fuch a manner as not to be eafily ex- 
 trafted. A particular direction is afterwards given to 
 them by means of a brufh, and they are made to keep 
 this diiedtion by having a hot iron paffed over them. 
 If the agitation were continued for a longer time, thefe . 
 hairs, not having their ftraightnefs deftroytd by the ope- 
 ration before deferibed, would pals entirely through 
 the felt, going out at the oppofite furface, as eac U 
 hair follows exatlly the dii'etliou it acquired at the be- 
 ginning. 
 
 It is owing to the very fame circumftances which. 
 make wool and hair capable of felting, that woollen 
 cloth is thickened by tuUiug. See Fulling in this- 
 Supplement. 
 
 FERGUSSON (Robert), who at an early period of 
 life obtained a confiderable degree of celebrity as 3 
 Scottilli poet, was born at Edinburgh on the 5th of 
 September 1750, according to a manufcript account of 
 him with which we have been favoured by a relation. 
 In the biographical Iketch prefixed to the Perth edition 
 of his poems he is faid to have been born in 1751. 
 
 His father William Fcrguffou poffeired, as well as 
 hlmfelf, fome talents for poetry ; but, marrying early, 
 and being wiler than his Ion, he abandoned the mufes.- 
 
 fur-
 
 F E R [64 
 
 Fi;-i;u(r<n. for tra<1i?, and was tmployt.(l in (IKTcTent mercantile 
 
 '~"v»— houfes, firft in Aberdeen and afterwards in Edinburgh. 
 
 At the time of his death he was an accountant in the 
 
 Britifli Linen Hall ; but never acquired any thing like 
 
 opulence. 
 
 During the years of infancy and childhood, the con- 
 ftitution of our poet was fo weak, that little hopes were 
 cntertai:ied of his arriving at manhood. By the care, 
 however, and attention of his parents, he gradually ac- 
 quired ftrength, and at the age of fix was put to an 
 Englifh fchool, where his proficiency in reading and re- 
 citing was uncommonly great. At the age of fevcn he 
 was feiit to the high fchool of Edinburgh, where lie 
 continued four years, and with very little labour made a 
 rapid progrefs in the knowledge of the Latin tongue ; 
 but for fume reafon or other he was removed from the 
 high fchool to the grammar fchool of Dundee, whence, 
 after two years, he was fent to the univerfity of St An- 
 drew's. A gentleman of the name of FergufTon had 
 left burfaries in that univerfity for the education of two 
 boys of the fame name ; and Mr William FergufTon ha- 
 ving with difficulty obtained one of them for his fon, 
 was induced to educate him at St Andrew's in prefe- 
 rence to Edinburgh. 
 
 Though at no period of his life a fevcre ftudent, our 
 poet's attainments in fcience were fnch as to keep alive 
 in the univerfity the hopes which had been ioimcd of 
 him at fchool ; and he was confcfTedly the firft mathe- 
 matician of his ftanding. On this account we are told 
 that he became the favourite of Dr Wilkie, who was 
 then profeflbr of natural philofophy in the univerfity of 
 St Andrew's; but it is not improbable that the Doctor 
 valued him as much for his poetical genius as for his 
 fkiU in geometry ; for Wilkie was a poit hinifelf, and 
 Mr Ferguflou had already written fcveral fma!l poems 
 which attracted confiderable notice, as well from the 
 profeflors as from his fellow-iludents. Bi:t whatever 
 was the bond of union, Dr Wilkie patronifed the youth- 
 ful poet ; and the poet fliewed afterwavds that he was 
 not ungrateful. Upon the Doftor's death, he pub- 
 liflied, in the Scottilh dijlecl, a beautiful eclogue to his 
 memory, in which the peculiar merits of that eccentric 
 genius are appreciated with great judgment. See Wil- 
 kie, in this Supplement. 
 
 During the lail winter that he refided in St Andrew's, 
 our poet had collefted materials for a tragedy on the 
 death of Sir William Wallace, and hod even com])leted 
 two afts of the play ; but having leen a fimilar work 
 on the fame fubjecl, he abandoned his delign ; " be- 
 caufe (faid he to a friend) whatever I publKh fiiall be 
 original, and this tragedy might be confidered as a 
 
 Having finifiied his ftudies at the univerfity, he re- 
 turned to Edinburgh without refolvliig on any perma- 
 nent employment. His father had defigned him for 
 the church ; but he was now dead, and our author 
 turned a deaf ear to the intreaties of his mother, and 
 of every other friend who endeavoured to perfuade him 
 to fulfil his father's intention. He was then advlfed to 
 ftudy phyfic; but he declined It, becaufe, he faid, that, 
 when reading the defcription of dlfeafcs, he fancied that 
 he felt the fymptoms of them all in himfelf. To the 
 law, however, he could not dart the fame objedlion ; 
 and he began to ftudy it, but made no progrefs. At 
 this his relation and the editor of his poems exprefs no 
 
 6 ] 
 
 F E R 
 
 furprife ; for, according to them, it was a ftudy the FyruufTin. 
 moft Improper for him, as it could not be expected that ■""■>— —< 
 a genius fo lively would fubinit to the drudgery of that 
 dry and fedentary profeflion. 
 
 That the law was a very improper profeflion for a 
 man of his narrow fortune Is indeed true ; but we trull 
 that his two biograpliere will not confider us as Intend- 
 ing any offence to them, it we embrace the prelent op- 
 portunity of c.xpofing the folly of a very <:ommon re- 
 mark, that a lively genius cannot fubniit to what is ab- 
 furdly called a dry iludy. We might Inftance different 
 lawyers at our ov.-n bar, who, with great poetical ta- 
 lents in their youth, have rifen to the fummit of their 
 profeffion ; but to avoid perfonal diftinitions at home, 
 we (hall take our examples from England. The genius 
 of the late Earl of Mansfield was at leaft as lively as 
 that of Mr FergufiTon, and if he had pleafed he could 
 have been equally a poet ; yet he fubmitted to the 
 drudgery of fludylng a law ftill drier than that of Scot- 
 land. To the fine tafte of Atttrbury bifiiop of Ko- 
 chctter, and to bis clafiical compofitions both In profe 
 and verfe, no man is a ilranger who Is at all converfant 
 in Englifti literature: yet that elegant fcholar and poet, 
 after he had rifen to the dignity of Dean of Carlille, 
 lubmitled to the drudgery of Itudying, through the 
 medium of barbarous Latin, the ecclcfiaftical law of 
 England from the earlicft ages; and declared, that by 
 dint of perfeverance he came in time to relifh it as much 
 as the ftudy of Homer and Virgil Whatever be 
 thought of Milton's political principles, no man can 
 read his controverfial writings, and entertain a doubt 
 but that he could have fubmitted to the drudgery of 
 ftudying the law. 
 
 The truth Is, a:id It is a truth of great Importance, 
 that a man of real vigour of mind may bring himfelf to 
 delight in any kind of ftudy which is ufefiil and ho- 
 nourable. Such men were Lord Mansfield, the BIlliup 
 oi Rochefter, and Milton; but, whether through fome 
 radical defedt In his nervous lyfteni, or in confequenee 
 of eaily dilTipatlon, MrFeigufijn, with many elllmable 
 qualities, was fo utterly dcftituce of this mental vigour, 
 that rather than fubmit to what his friends call drud- 
 gery, he feems to have looked with a wiftiful eye to 
 fome finecure place. 
 
 With this view he paid a vifit to an uncle who lived 
 near Aberdeen, a man of great learning and in opulent 
 circumftauces, in hopes that, by his iutcrell, he might 
 be fettled in a poft fuitable to his merit : But how de- 
 lufive were his hopes I His uncle indeed received him 
 with every mark of affection ; but his fondnefs gra- 
 dually cooled, and at the end of fix mouths he ordered 
 him abruptly to leave his houfe, without having endea- 
 voured to procure for him any fettlement. 
 
 To a mind like Ferguffon's, feelingly alive, fuch treat- 
 ment from fo near a relation, to whom he had always 
 behaved with becoming refpefl, mult have been dread- 
 fully galling. Stung with indignation, he returned to 
 his mother's at Edinburgh; and as loon as he recovered 
 from a fevere illnefs, brought upon him by difappoint- 
 inent and the fatigue of his journey, he compofed two 
 elegies ; one on " The Decay of Frlendfiilp," and the 
 other " Againft Repining at Fortune," both occafion- 
 ed by his adventure in the North. How much he felt 
 the dafhing of his hopes, is apparent from the following 
 pathetic lines in the Decay of Friendftiip : 
 
 But,
 
 FKjrl.flVin. 
 
 F E R [ 
 
 But, ah! thefe youthful fportive honrp are Bed, 
 Thde fcenes of jocund inirtli are now no more j 
 
 No hcah'ng flinnbcrs 'tend mv humble bed, 
 No friends condole the forrows of the poor. 
 
 And what avail the thoughts of former joy ? 
 
 Wiiat comfort bring they in the adverfe hour ? 
 Can they the canker-worm of Care dellroy. 
 
 Or brighten Fortune's difcontented lour ? 
 
 Fermcnta. 
 tion. 
 
 647 ] F E R 
 
 fed as by the hand of death ; and " 011 his countenance Feiguffon 
 fat horror plum'd." 
 
 From tliis (late of gloomy defpondtncy, however, he 
 began gradually to recover; and, except that a fettled 
 melancholy was vifible in his countenance, his health 
 was completely rellorcd, when one evening he fell and 
 cut his liead fo dveadfully, that from the lofs of blood 
 he became delirious. In this deplorable ftatc he conti- 
 nued for feveral months, till, being quite exhauftcd by 
 
 So deftitute was he at this period, that he fubmitted want of fleep and conttant fpeaking, he expired on the 
 
 to copy papers in the commiitary clerk's offic'?, we be 
 lieve at fo much the Iheet ; but not liking the employ- 
 ment, and quarrelling with the commiffary clerk-depute, 
 he foon left the ufiice in difgull. 
 
 Hitherto he had lived rather in obfcnrfty ; and hap- 
 py had it been for him if in that obfcurily he had been 
 
 l6th of Oftober 1774. He was interred in the Canon- 
 gate churchyard, where his friends erefted a monument 
 to bis memory, which has been iince removed to make 
 way for a larger and more elegant monument by his 
 enthufiaftic admirer tlie late poet Burns. 
 
 Tims died Robert Ferguifju, a young man of the 
 
 iuifered to remain ; happy had it been for hiui, had bis brighteft genius and of the bell heart, who, had he 
 
 converiation been lefs falcinating, and his company lefs joined prudence to his nticommon talents, mull have 
 
 courted by the frolic and the gay. PofTefling an inex- rifen to great eminence in tlie republic of letters ; but, 
 
 lianftible fund of wit, the belt good rjature, much mo- as a late juveiu'le poet has obfervcd of him 
 
 dellv, and great gfoodnefs of heart, he was viewed with ^ , ,-i • , i . • 
 
 ah.- u II • I, 1 1 u .. I • Complete alike in head and heart, 
 
 attention bv all to wnom lie was known; but his powers -d • • 1 , 
 
 r 1- ' J 1 n ■ II J » 1 . r „■„• 1 -tSi't wanting in trie prudent l>art, 
 
 or loii':r, and almolt unrivalled talents tor imimickry, -,^ , , " , '^ « ' 
 
 1 J i-^ ,- • . »i r.u r u -n j rle prov'd a poet s lot. 
 
 led nim ortener into the company 01 thole who wilhca ' ' 
 
 for him merely to enliven a fecial hour, than of fuch as Of his poems no general charaifler can be given. The 
 
 by their virtue were inclined, and by their influence were fubjeds of them arc fometimt-s uncommon and generally 
 
 able, to procure him a competent fettlement for life, local or temporary. Tiiey are of courfe very unequal. 
 
 The conieqiience of this was great laxity of manners. But fuch ot them as are in the >Scotti(h dialeft have 
 
 His moral principles indeed were never corrupted, nor, been univerfally admired by his countrymen; and when 
 
 as we have reafon to believe, his faith in revelation (lia- it is confidered that they were compoftd aniidtl a round 
 
 ken; but there is no doubt but that, courted as he of difiipation, they will be allowed to furniih complete 
 
 was by the fyren voice of pleafure, he yielded to many evidence of his genius and his taile. 
 
 temptations, and in the hours of ebricty commilted ac- FERMAT (Peter), who was counfellor of the par- 
 
 tions wliich, in his cooler moments, he refit fled on with liament of Toulonfe in France, flouriflicd in the 17th 
 
 abhorrence. century, and died in 1663. He was a man of great 
 
 His confcience was indeed frequently ronfcd. Being talents, and a very general fchol.ir ; but being contem- 
 
 on a vifit to a friend at Haddington, and fauntering one porary and intimately connecled with Des Cartes, Mer- 
 
 day near the churchyard, he was accofted by a clergy- fenne, Torricelli, ami Huygens, he was naturdlly led to 
 
 man, who fcemed to be no flranger to the kind of life devote much of his time to the mathematical fciences. 
 
 which he led. This judicious divine contrived to draw He was (fays Dr Hutton) a rirll rate mathematician, 
 
 his attention to the Ihortnefs of time, the length of <ind pofFi (u d the lintft talle for pure and genuine geo- 
 
 eternity, death and judgment, and the awful (late that metry, whieli he contributed greatly to improve, as 
 
 awaits the wicked in an unfeen world ; and the conver- well as algebra. 
 
 fation made a deep impreffion on his mind. It feemed, Fermat whs author of, i. A Method for the Oua- 
 
 however, to be effaced from his memory by the diifipa- drature of all forts of Parabolas 2. Another on Maxi- 
 
 tion of Edinburgh, till it was recalled with double effeifl mums and Minimums : which ferves not only for ihc 
 
 by the following accident : determination of plane and folid problems, but alfo for 
 
 In the room adjoining to that in which he llept wr.s drawing tangents to curve lines, finding the centres of 
 
 a flarling, which being feized one night by a cat that gravity in folids, and the refollition of quellions con- 
 
 had found its way down the chimney, awaked Mr Fer- cerning numbers: in fhort, a method very fimilartothe 
 
 guffbn by the moll alarming fcreams. Having learned fluxions of Newloii. — 3. An Introduftion to Geome- 
 
 the caufe of the alarm, he began ferionfly to refitd how trie Loci, plane and folid 4. A Treatife on Spheri- 
 
 often he, an immortal and accountable being, had in cal Tangencies : where he demonltratcs in the folids the 
 the hour of intemperance fet death at defiance, though fame things as Vieta demonllrated in plaiies. — 5. A Re- 
 it was thus terrible in reality even to an unaccountable itoration of Apollonius's two Books on Plane Loci. 
 
 and finlefs creature. This brought to his recolledlion 6. A General Method for the dimenlion of Curve 
 
 the converfation of the clergyman, which, aided by the Lines. Befides a number of other fmaller pieces, and 
 
 folemnity of midnight, wrought his mind up to a {litch many letters to learned men ; feveral of which are to be 
 
 of remorfe that almoft bordered on frantic defpair. found in his Opera Farla MutLematua, printed at Tou- 
 
 Sleep now forfook his eyelids; and he rofe in the morn, loufe, in folio, 1679. 
 
 ing, not as he had formerly done, to mix again with FERMENTATION is a chemical procefs which 
 
 the focial and the gay, but to be a reclufe from fociety, has been already confidered in the Encyclopedia, and 
 
 and to allow the remembrance of his pad follies to prey will be again refumed in /this Supplement under the title 
 
 upon his vitals. All his vivacity now forfook him ; yinimal and Vegetable Subsiances. In this place we 
 
 thole lips which were formed to give delight, were do. mean nothing more than to give fuch diredions, prin- 
 cipally
 
 rinii. 
 J 
 
 F E R [ 648 ] FEZ 
 
 cipally f.om Mr Ricliardfon of Hull, for the proper Flt- " In order to maintain a due regulation of tlie fer- 
 
 mentation of malt liquors as have not been fully detail- menling power, and to anfwer the feveral purpofes of ' 
 
 ed in the aiticle Brewing (EncycL). the operation, a fcrupulous attention to the degree of 
 
 This author controverts, we do not think ver\' fiic- heat at whiili the aftion commences, and a particular 
 cefsfuUy, the conclulions drawn by Mr Henry from the regard to the quality and quantity of the ferment em- 
 experiments, of which the reader will find an account ployed, are iiulifpenfably necelTary." The degree of 
 in the article Fermentatioh [Encycl ) ; but it is not heat muil be afcertained by the thermometer, and regu- 
 his therjry with which we are at prefent concerned, but lated by experience : the quantity of yeaft can be af- 
 his praftice as that of an experienced and enlightened certained only by the intention of the artill. 
 brewer. Having treated of IVorts, and the proper me- FEZZAN is a kingdom in the anterior of Africa, 
 thod of boiling them, for which fee AVort in this Sup- placed in the vaft wildernefs as an iiland in the ocean. 
 .■phnunt, and having given an hiftorical view of the pro- The following account of it was given to Mr Lucas 
 cefs of fermentation, of which a pretty accurate abridge- the African traveller by an old fhereef, a native of Fe/.- 
 jnent is inferted in the articles Br.ewing and Fer.- zan ; and that account was confirmed by the governor 
 MENTATION [EncycL), he proceeds thus : of Mefurata, who had himfelf viUled Fezzan, and who, 
 
 " The agency of air, in the bufinefs of fermentation, having treated the traveller witli great kindnefs, ought 
 
 is very powerful ; but as all fermentable fubjefts have an not to be fuipefted of having wantonly deceived him. 
 ■abundant fupply, we are rather to provide for the egrefs According to this account, Fezzan is iituated to the 
 
 r)f their own, than to fuffer the admiffion of the exter- fouth of Mefurata (fee Mesurata in this SuppL), and 
 
 nal air, by which a great number of the fine, volatile, the traveller from the latter place to the former arrives 
 
 oleaginous parts of the fubjeft would be carried off, in eight days at Wadan, where refrefliments are procu- 
 
 and a proportionate injury in flavour and fpirituofity red for the caravan. From thence in five hours they 
 
 fufi;ained. Hence fuch a covering fiiould be provided reach the defart of Soudah, where no vegetable is feen 
 
 for the gyle-tun as would barely allow the efcape of the to grow but the talk, a tree from which the lemon-co- 
 
 common air produced by the operation ; whilll the gas, loured wood is taken which forms handles for tools, 
 
 or fixed air, from its greater denfity, refting upon the The paiTage of the defart takes up fome days, when 
 
 furface of the beer the whole depth of the curb, pre- 
 vents the aAion of the external air, and confequently 
 the efcape of thofe fine and valuable parts juil men- 
 tioned. 
 
 " But towards the conlufion of vinous fermentation, 
 
 •this aerial covering begins to lofe its efficacy ; which 
 points out the neceffity of then getting the beer into 
 calks as foon as poffible, that the confequences may be 
 prevented, of expofing fo large a furface, liable to fo 
 copious an evaporation. Amongft thefe, a lofs of fpi- 
 rituofity is not the lead ; for this evaporation is more 
 and more fpirituous, as the aftion approaches the com- 
 pletion of vinous fermentation ; and that once obtained, 
 the lofs becomes ftill more confiderable, if ftill expofed 
 to the air ; whence it might be termed the diftillation 
 of Nature, in which (he is fo much fuperior to art, that 
 the ethereal fpirit rifes pure and unmixed, whilil the 
 higheft rectification of the ftill produces at beft but a 
 compound of aqueous and fpirituous parts. 
 
 " Nor is this entirely conjefture. Experience teaches 
 us, that we cannot produce fo ftrong a beer in fummer, 
 
 .ceteris paribus, as in winter ; the reafon is, not becaufe 
 the aftion of fermentation does not realize fo much fpi- 
 rit in warm weather, but becaufe the fermenting liquor 
 
 the traveller finds a milerable village, producing nothing 
 but dates, brackifh water, and Indian corn ; from this 
 village a day's journey condiuSts to the town of Sehbah, 
 where are the remains of an ancient caftle, and other 
 venerable ruins, and in four days more he reaches Mour- 
 zouk, the capital of Fezzan. 
 
 This city is fituated on the banks of a fmall river, 
 furrounded by a high wall for defence, and is diftant 
 from Mefurata 390 computed miles. Eaftward of 
 Mourzook is the town of Qu^eela, in which are the re- 
 mains of ancient buildings ; the fize of the cifterns, and 
 the conftruftion of the vaulted caves, exhibit inftances 
 of ancient fplendour. South of which place is Jermah, 
 diftinguilhed by numerous and majeftic ruins, on which 
 are many infcriptions. Tefibuwa lies eaftward, near 
 which was a river which the (hereef remembers, but is 
 now overwhelmed in the moving fands. N. E. from 
 Mourzouk, diftant about 120 miles, is the large town 
 of Temmifwa, where the caravans of pilgrims from Bor- 
 nou and Nigritia, by way of Cairo to Mecca, provide 
 their ftores for the defart. 
 
 In the town or province of Mendrah is a large quan- 
 tity of trona, a fpecies of foffil alkali, that floats on the 
 furface or fettles ou- the banks of its fpreading lakes, 
 
 after the perfeftion of vinofity, continues fo long in a great quantity of which is fent to Tripoli, and fliipped 
 
 ilate of rarefaftion, that the fpirituous parts are difiipa- for Turkey, Tunis, and Morocco ; at the latter place it 
 
 ted in a much greater degree at that time than at any is ufed as an ingredient in the red dye of the leather, 
 
 other, in a fimilar ftate of progreffion. And this doc- Mendrah is about 60 miles fouth of Fezzan. The ter- 
 
 -trine of natural diftillation feems to account for that in- ritory of Fezzan extends but little wcftward, being 
 
 creafe of ftrength obtainable from long prefervation, in confined by barren mountains. The fmaller towns of 
 
 ■well clofed cafl'CS, and, more particularly fo, in glafs this kingdom are faid to be about one hundred ; thefe 
 
 bottles ; for Nature, in her efforts to bring about her towns are chiefly inhabited by huft)andmen and ihep. 
 
 "■rand purpofe of refolviag every compound into its firft herds ; in every town a market is regularly held ; mut- 
 
 principles, keeps up a perpetual internal ftruggle, as ton and goat's fle(h are fold by the quarter, ufually from 
 
 well as an external evaporation ; and if the latter be thirty-two to forty grains of gold, or from four to five 
 
 effeftually prevented, the former muft be productive of fliillings Englifti. The flelh of camels is dearer, and 
 
 additional fpirituofity, fo long as the aftion keeps with- divided into fmaller parts. 
 
 in the pale of vinous fermentation. The houfes are of clay, with flat roofs compofed of 
 
 branches
 
 FEZ [ 649 ] FEZ 
 
 hrancJiCB of trees, c!^ which earth is laid ; tlu's is fuffi- The revenue it compofcd of a tax on towns and vil- F.zziin. 
 cient in a climate wlicrc it ntver rains. The heats in lages, a tax on every camel load of goods (except pro- ^~'"^''~~' 
 fiiinmer, from April to November, are intenfe, and the vilionG) which enters the capital, fines lor ofTinces, 
 liot winds blow from the fouth-eaft, foiitli, ai.d fouth- lands of pcilons dying without heirs, and a tax on par- 
 weft, with fuch violence as to threaten fiifTocation ; dens and dale trees. Gold duft by weight is the chief 
 when it changes to the weft or north-weft a reviving medium of payment ; but for convenience they are tnr- 
 
 frtftinefs enfnes. 
 
 Tlie drcfs of the inhabitants is like that of the Moors 
 of Barbary, cori lifting of a large pair of trowlers, a 
 ihirt which hangs over the trowlers, a kind of vvaiftcoat 
 without fleeves, and a jacket with tight fleevcs ; over 
 the jacket is a loofe robe which reaches below the knee, 
 a girdle of crimion, and a long cloth called a iarrokon 
 or ii//jiiii-que^ like a highland plaid, is worn ; ftockings 
 of leather, laced like half-boots, and flippers ; on the 
 
 nidied with fmall papers of gold dnft of diffirent va- 
 lues, from two xartes or one ;.'.d a half upwards ; for 
 fnidUer articles corn or flour are ufcd as a mLdium. One 
 grain of gold is equal to i-Jd. fterling. I'he I'ezzan 
 grain is the fame as in Englan^. « 
 
 The jnftice of the fovcrcign is highly extolled ; fmall 
 offences are puniftud by the baftinado, and the punifti- 
 ments increafe to fine, imprifonment, and death. Truft- 
 ing to their natural defence, their towns arc without 
 
 head a red cap and turban ; fometimes over the whole guard, and they have no ftanding forces. Tin 
 they throw a long cloak with a hood, called a 6ur- war the ftiereef remembered was undertaken againft a 
 tioa/h. In funimer they throw off all but the fnirt and people inhabiting the mountains of Tibefti, which is 
 
 feparated from the people of Fezzan by a wide and 
 fandy defart. Thefe people are wild and favage, and 
 had plundered a caravan belonging to the king, who 
 fcnt an army of between 3 and 4:00 men againft and 
 fubdued them. The country of thefe people produces 
 much fenna. The vales of Tibefti are laid to be fertile 
 
 the cap. 
 
 The people bear very high degrees of heat, but any 
 cold affeiSs them fenfibly. Their difeafcs are chiefly 
 of the inflammatory and putrid kind ; the fmall pox is 
 common. Their old women are their principal phyfi- 
 cians. For pains in the head they cup and bleed ; for 
 
 thofe in the limbs, they bathe in the hot lakes. They in corn and pallure for cattle, particularly camels, 
 have a multitude of noxious and loathfome animals ; the The people live in huts, and profefs various religions, 
 air is crowded with mofquitos, and their perfons are fo;ne the Mahomedan, others are attached to their an- 
 over-ruu with the vermin which affeft the beggars of cient idolatry. 
 Europe. The people of Fezzan carry on a confiderable trade 
 
 In their perfons they incline to the negro, of a deep with Tripoli, Bornou, Nigritia, &c. At the end of 
 fwarthy complexion, with curly black hair; they are Oftober, when the heats are abated, the caravans de- 
 tail, but indolent, iniiftive, and weak. In their com- part from Mourzouk in fmall parties of ten or twelve, 
 mon intercourfe, diftinftion of rank fcems to be for- unlefs in time of war. 1'hey lay in provifions of dates, 
 gotten ; rich and poor, maffer and man, converfe, eat, meal, and mutton faked, dried in the fun, and boiled in 
 and drink together ; they are, however, gi'nerous and oi! or fat. The merchants have agents in the chief 
 
 towns, to whom they fend the (laves they purchafe. 
 
 The caravans to Tripoli carry the tromi, fenna, gold 
 
 and flaves brought from the foutheru countries ; and in 
 
 return bring back cutler)-, woollen, filks, dollars, cop- 
 
 hofpitable. 
 
 An cxtenfive plain compofes the kingdom of Fezzan : 
 the foil is generally a light fand, the fprings are abun- 
 dant, and few regions in Africa exhibit a richer vege- 
 tation. The land produces the talk, the white thorn, per, and brafs. 
 date trees, the olive and lime, apricot, pomegranate, That to Bornoa carries brafs and copper, for the 
 and fig : Indian corn and barley are the favourite ob- currency of the country, imperial dollars, and various 
 jefts of cultivation ; of wheat there is little raifed. The manufaftures ; but of their own produce only a prepa- 
 tame animals are, the fheep, cow, goat, and camel ; ration of dates, and meal of Indian corn ; and thev take 
 and the wild are, the oftrich, antelopes of various kinds, in return flaves, gold duft, and civet. 
 one of which is called the huadee, which when chafed To Cafhna, an empire in Nigritia, they carry cow- 
 plunges with addrefs from a precipice, and hghts on its ries, brafs to make rings and bracelets, horfes, fevcrai 
 hams. kinds of manufadfures, and the Gooroo nuts ; and in 
 
 The food of the lower dafs confifts of flour of In- return take gold dnft, flaves, cotton cloth, dyed goats 
 
 dian corn, feafoned with oil and fruit ; thofe of fuperior flcins, hides, fenna, and civet, for the countries fouth of 
 
 rank eat wheat bread and flefli. Fezzan producer, the Niger, where alfo they convey fabre blades and 
 
 much fait ; the water has in general a mineral tafte, but Dutch knives, coral, brifs beads, looking glaft^es, dollars, 
 
 the favourite beverage is a liquor from the date tree, &c. and receive back gold duft, flaves, cotton cloths, 
 
 which acquires, when fermented, an intoxicatingftrength. goat fl<ins, Gooroo nuts, cowries, and ivory. 
 
 In religion they are rigid Mahomedans, but tolerant. A caravan of pilgrims fets out likewife in the autumn 
 
 Their government monarchical ; their prefent king is of every fecond or third year from Mourzouk, the 
 
 defcended from one of the fliereefs of Tafiilet, who capital of Fezzan, to Mecca. Tiiey proceed to Te- 
 
 about 401 years fiiice obtained the crown. Till the mefia, over the mountain of Ziltan, and thence to Sib- 
 
 prefent century the kingdom was independent, when bul, a place fubjcft to Tripoli ; and thence nearly in a 
 
 the Baftiaw of Tripoli conquered and made it tributary ; line with the Mediterranean fea to Cairo, and thence 
 
 the reigning fovereign has nearly thrown off this yoke, to Mecca by the cuftoniary route. 
 
 In Fezzan, the defcendants of the prophet are highly As not one celeftial obfervation has been taken to 
 
 privileged, their property and perfons are inviolable; determine any latitude between Benin and Tiipoli, all 
 
 they are exempt from certain punifliments. This clafs the pofitions are fixed by eftimation, reckoning fifteen 
 
 are in general either princes or merchants. or fisteen miles for a day's journey. Mr Rennell places 
 
 SufPL. Vol. I. Partll. 4N Mourzook,
 
 F I G 
 
 [ 6jo ] 
 
 rioiiirate. Mourzouk, the capital of Fezzan, in Lit. 27'. 20', or 
 ' ' 'v 260 miles from Mafurata. 
 
 FIGURATE NUMBF.Rs are fuch as do or may re- 
 prefeiit fome geometrical figure, fuch as a triangle, 
 pentagon, or pyramid, &c. Thcfe numbers are treated 
 of at great length by Macburin in his Fluxions ; Sim- 
 fon in his Algebra ; and Malcolm in his Arithmetic ; 
 but the following accoT'snt of them by Dr Hutton is as 
 perfpicuous as any that we have feen : 
 
 Figurate numbers are diftingiilfhed into orders, ac- 
 cording to their pkce in the fcale of their genaration, 
 being all produced one from another, viz. by adding 
 continually the terms of anyone, the fucceffive funis are 
 the terms of the next order, beginning from the firfl 
 order, which is that of equal units i, ', I, l, &c. ; then 
 the fecond order confifts of the fuccedive fums of thofe 
 of the firft order, forming the arithmetical progreffion 
 1, 2, 3, 4, &c. ; thofe of the third order are the fuc- 
 oefTivc iums of thofe of the fecond, and are the triang'i- 
 .lar numbers l, 3, 6, ic, Ij, &c ; thofe of the fourth 
 order are the fucceflive fums of thofe of the third, and 
 are the pyramidal numbers 1,4, 10, 20, 35, &c. ; and 
 fo on, as below : 
 
 F I L 
 
 Pentagons. 
 
 Order. Name, 
 1. Equals, 
 
 Arithmelicals, 
 Triangulars, 
 Pyramidals, 
 2d Pyramidals, 
 3d Pyramidals, 
 
 2. 
 
 3- 
 
 4- 
 
 5- 
 6. 
 
 Numbers, 
 
 1, 1, I, I, I, &c. 
 
 1. 2, 3, 4, 
 
 6, 10, 
 
 10, 20, 
 
 '5' 35. 
 21, 
 
 28, 
 
 I. 
 1. 
 
 56. 
 
 5, &c. 
 
 J 5' -^c. 
 
 35, &c. 
 
 70, &c. 
 
 126, &c. 
 
 3. 
 4. 
 5. 
 
 7. 4th Pyramidals, I, 7, 28, 84, 210, &c. 
 
 The above are all confidered as different forts of tri- 
 angular numbers, being formed from an arithmetical 
 progreffion whofe common difference is i. But if that 
 tommon difference be 2, the fucceflive fums will be 
 the feries of fquare numbers : if it be 3, the ferics will 
 be pentagonal numbers, or pentagons ; if it be 4, the 
 feries will be hexagonal numbers, or hexagons ; and fo 
 on. Thus : 
 
 jirlthmeti- 
 
 'ijl Sums, or 
 
 
 2d Sums, or 
 
 cats. 
 
 Polygons. 
 
 
 2d Polygons. 
 
 1. 2, 3' 4 
 
 Tri. I, 3, 6, 
 
 10 
 
 1, 4, 10, 20 
 
 J. 3. 5. 7 
 
 Sqrs. I, 4, 9, 
 
 16 
 
 I. 5' 14. 30 
 
 ], 4. 7> 10 
 
 Pent. 1, 5, 12, 
 
 22 
 
 I, 6, 18, 40 
 
 I. 5' 9. 13 
 
 Hex. I, 6, 15, 
 
 28 
 
 1, 7, 22, 50 
 
 &c. 
 
 
 
 
 And the reafon of the names triangles, fquares, pen- 
 tagons, hexagons, &c. is, that thofe numbers may be 
 placed in the form of thefe regular figures or polygons, 
 as here below ; 
 
 Triangles. 
 
 156 10 
 
 Squares. 
 9 
 
 16 
 
 o o 
 o o 
 
 12 
 
 000 
 
 , O C J 
 O O 
 
 FictTate, 
 
 FilUT. 
 
 Hexagons. 
 
 o o 
 
 o o 
 
 o o 
 
 000 
 
 o 000 
 
 00 o 
 
 000 
 
 But the (igurate numbers of any order may alfo he 
 
 found without computing thofe of the preceding orders; 
 
 which is done by taking the fucceflive produifts of as 
 
 many of the terms of the arithmeticals 1,2,^, 4, 5, &c. 
 
 in their natural order, as there are units in the number 
 
 which denominates the order of figurates required, and 
 
 dividing thofe produfls always by the firll produft. 
 
 Thus the triangular numbers are found by dividing the 
 
 produfts 1X2, 2X3, 3 X 4, 4 X 5, &c. each by the 
 
 firft produift I X 2 ; the firft pyramids by dividing the 
 
 products 1X2X3, 2X3X4, 3X4X5, &c. by the 
 
 firft I X 2 X 3. And, in general, the figurate numbers 
 
 of any order n, are found by fubftituting fucceffively 
 
 J, 2, 3, 4, 5, 5:c. inftead of .v in this general exprefiion 
 
 X . X + J . x + 2 . X + ^ . Sec. . r a 
 
 ; ; where the radtors in 
 
 I . z . 3 . 4 . &c. 
 
 the numerator and denominator are fuppofed to be mul- 
 tiplied together, and to be continued till the number in 
 each be lefs by i than that which exprefTes the order of 
 the figurates required. 
 
 FILTER (See En^ycl.) It is well known that vef- 
 fcls made of a particular kind of porous ftone are em- 
 ployed as filtering bafins for freeing water, intended to 
 be drunk, from various kinds of impurity. In fea voy- 
 ages fuch filtering bafins mud be highly ufeful ; and 
 they are frequently found ufeful at land where no water 
 can be had but from ftagnant pools, or fprings flowing 
 through clay. The ftone, however, of which they are 
 made is not every where to be found ; and therefore 
 different perfons have endeavoured to employ the art of 
 the potter to fupply their place. 
 
 In the year 1790 a patent was granted to a female 
 potter, for her invention of the following compofition 
 for this purpofe; viz. four equal parts, out of nine equal 
 parts, of tobacco pipe clay ; and five equal parts, out 
 of nine equal parts, of coarfe fea, river, drift, or pit 
 fand ; thefe two materials, in the above proportions, 
 are fufficient for the purpofe of making fraall bafins, 
 and other veffels, to contain a quantity not exceeding 
 one gallon of water, or other liquid. But the compo- 
 fition, when confined to thefe two materials, and in 
 thefe proportions, often flies or cracks in the fire, if 
 larger bafins, or other veffels, are attempted to be made 
 with it. She, therefore, in the fecond inftance, com- 
 pofes her filtering bafins of equal parts of tobacco-pipe 
 clay and coarfe fea, river, drift, or pit fand ; in the 
 third inftance, of three equal parts, out of nine equal 
 parts, of tobacco-pipe clay; one equal part, out of nine 
 equal parts, of Stourbridge clay, or clay from the fur- 
 face of coal mines, or any other clay of the fame quah. 
 ty ; one equal part, out of nine equal parts, of Windfor, 
 
 < J
 
 V I L 
 
 C 6s 
 
 or other loam, of the fiime quality with WIndfor loam ; 
 'and tour equal parts, out of nine equal parts, of coarfe 
 »iver, fea, drift, or pit fand. Or, in the fourtli in- 
 fiance, of four equal parts, out of eight equal parts, of 
 tobacco-pipe clay ; three equal parts, out of eight e- 
 qual parts, of coarfe fea, river, drift, or pit fand ; and 
 one equal part, out of eight equal parts, of that burnt 
 j^round clay of which crucibles are made. 
 
 If the lady who invented, or pretends to huve in- 
 vented, thefc bafuis, have a right to her patent, tar be 
 it from us to with our readers of any defcription to in- 
 croach upon it ; but as the nfe of the materials of which 
 her bafins are made was known to potters before file 
 vas born, they may certainly compound thtfe materials 
 in proportions different from hern, without doing her 
 any legal injury. As flie varies her own proportions 
 lo much, we think it probable that fome proportion 
 differing a little from tlicm all, may anfwer the purpofe 
 of filtering vefTels equally well ; and it is almoll need- 
 lefs to add, that with this precaution any potter may 
 make fuch veficls, for which lie would undoubtedly 
 have a great demand. 
 
 A patent has likewife been granted to Mr Jofliua 
 Collier of Southwark for a very ingenious contrivance 
 for filtering and fweetening water, od, and all other 
 liquids. Of this contrivance, which combines the ap- 
 plication of machinery with the antifeptic ))roperlies of 
 charcoal (See Chemistry n° 34. Supplement), we (hall 
 give a detailed account. 
 
 Fiih-oil is one of the liquids which he had it parti- 
 cularly in view to free from all its impurities in fmell, 
 tafte, and colour ; and the chemical procefs employed 
 by him for this purpofe, confills in pouring a quantity 
 of any fptcies of filh-oil, or a mixture of different forts 
 of fi(li-oiI, into any convenient vefFel, which is to be 
 heated to the temperature of 110 or £20 degrees of 
 Fahrenheit's icale, and then adding of caullic mineral 
 alkali, of the fpeciric gravity commonly defcribed as 
 1.25, or of fuch ftrength that a phial containing loco 
 grains of diftilled water will contain i2jo grains of 
 tliefe lees, a quantity equal to four parts of the too by 
 weight of the quantity of oil; the mixture is then to 
 be agitated, and left to (land a fulTicient time for the 
 falts and fediments to fubfide ; it is then drawn oiF into 
 another veflel, containing a fufficient quantity of frefit 
 burnt charcoal, finely powdered, or any other fubllance 
 poirciring antileptic properties, in a powdered or di- 
 vided Hate, with an addition of a fmall proportion of 
 diluted fulphuric acid, tufficient only to decompofe the 
 imall quantity of faponaceous matter Itill fulpendcd in 
 the oil, wliich appears by the oil becon)ing clear at the 
 furface : the contents of this veffel are alfo agitated, and 
 the coaly faline and aqueous particles left to fubiide ; 
 after which the oil is pafTed tiirough proper (trainers, 
 herein after deicribed, and is thereby rendered perfedt- 
 ly tranfparent and fit for ufe. 
 
 The principle of the improved flrainers, or filtering 
 macliines, confifts in the means applied to combine hy- 
 drollatic pre(rure, which increafts according to the per- 
 pendicular height of the fluid, with the mode of filter- 
 ing /^^r iifcetifum, thereby procuring the new and pecu- 
 liar advantage that the fluid and its fediment take op- 
 pofite diredjons. A great advantage attending this 
 invention is, that the dimenfions of the chamber in 
 which the fediment is received, may be varied, while the 
 
 I ] F I L 
 
 filtering furface remains the fame. To adapt the ma- F'l'"''. 
 chines not only to the purpofe of families, work-houfes, ' 
 
 hofpitals, public charities, the navy, or the merchant 
 fervlce, but alfo to all the purpofes of oil-men, of dillil- 
 le>s, of the laboratory, the brewery, &c. chambers '.f 
 various capacities muH be provided for the fediment 
 and precipitated matter. With refpeft to the oil-trade, 
 the (pace required is very great, efpecially for fperina- 
 ceti, or Brafil bottoms. In the vaiions purpofes of 
 the laboratory, no limits can be fixed, but all dimen- 
 fions will be occafionally required : in diftllleries and 
 breweries they may be ("mailer in proportion ; and in 
 that defigned for water and for domeftic ufe, a very 
 (mall chamber will be fuiBcIent. When water is to be 
 fwectened, or freed from any putrid or noxious par- 
 tides, it pafies, in its way to tlie filtering cliambtr, 
 through an iron-box, or cylinder, containing charcoal 
 finely powdered, or any other antifeptic fubttance info- 
 luble in water, the water being forced Into it by hy- 
 droftatic prefTure, through a tube of any fufficleiit 
 height. This box has two apertures to receive and de- • 
 liver the fluid, and thefc are opened and doled by cocks, 
 or fcrews, or any other method u(ed for fuch purpofes ; 
 and being affixed to the machine by other fcrews, may 
 be eafily detached from the fame. Thus, whtnever 
 the charcoal begins to lofe its antifeptic properties, the 
 box is removed and heated till it is red hot ; by which 
 means the foreign matter efcapes through the fmall ai 
 pertures ; after which the box is cooled, and the char- 
 coal becomes fweet, pure, and equally fit for ufe as at 
 firlt, though the procels be ever lb often repeated. 
 
 Another part of the inventiofl confitts In filtering 
 machines in the form of lliUs, in which charcoal may 
 be repeatedly burned after any fluid fubffances have 
 pafTcd through it, for the purpofe of freeing them ei- 
 ther f.oni putrid or noxious particies,.or of difcharging 
 their colouring matter ; which filtering ilills are fo con- 
 trived, that the fluid may pafs through in any quanti- 
 ty, without difplacing the charcoal : the part of the 
 fluid remaining Interfperfed among the charcoal, may 
 be driven over by heat, and be employed for many in- 
 ferior purpoies of the arts or manufactures. Lallly, 
 the heat may be raifed fo as to purify the charcoal, as 
 has been before de(cribed in the machines for water. 
 The flue of thofe (tills is fo cofifliructed that water may 
 be emphjyed to coi»l them without the lols of time re- 
 quifitc tor their gradually parting with their heat to 
 the furrounding fitmofphere, fo as to be fit for a fubfe- 
 quent operation. 
 
 But it was not merely to the purifving of oils arul 
 various liquids that Mr Collier turned his attention. 
 To his filtering apparatus are aliached indrumenls for 
 afceitaiiiing the comparative qualities of oils, which de- 
 pend in part on the principle or llieir fpecific gravities } 
 fpermaceti oil, contralled with other fi(h oils, being as 
 87 J to 920. For this purpofe, a g'ais veffel of any 
 convenient fnape is made ufe of, furniihed with a 
 bubble alio of gljfs, and a thermometer. If the oil is 
 pure, this bubble finks, when the mercury riles to a 
 certain (tandard, by the application of the hand, or 
 any other heat to the veflel containing the oil. If t'le 
 fpermaceti oil is impure, the bubble will (till float, 
 though it is of the temperature required ; and the de- 
 gree of impure, or foreign matter, will be (hewn by the 
 flate of the thermometer at which the babble finks. 
 
 4 N 3 To
 
 Filter. 
 
 Plate 
 XXIII. 
 
 F I L [6s 
 
 To determine what tendency oils iiftd for burning 
 have to congeal in cold weather, a freezing mixture is 
 put in a phial cf thin glais, or any other convenient 
 vefTel; into this a thermometer is immerfed, and a fingle 
 drop of the oil, under experiment, fuffered to fall on 
 the outfide of the veiTcl, where it immediately con- 
 geals: as the cold produced by the mixture gradually 
 ccafes, it is eafy to obfcrve by the thermometer at what 
 point of tempi-rature the oil becomes fluid, and runs 
 down the fide of the glaf?. 
 
 A iliDrt defcviption of this apparatus will make its 
 principles plain to every reader. A (lig. i.) is the 
 cillern into which the water or otlicr liquor to be fil- 
 tered is put. B D is a tube opening into the bottom 
 of the ciftern A, and bent along the bottom of the ma- 
 chine conveying the fluid into CCC the filtering cham- 
 ber, which is covered with leather bound down round 
 its circular rim, and through which leather the water is 
 percolated. DD, The bafon rifing above the level of 
 the chamber and receiving the filtered liquor. E, The 
 fpout by which it runs oti into a pitcher or other veffcl. 
 F, Another fpout furnilhed with a cock to draw off the 
 foul v/ater from the chamber when neceffaiy. GGG, 
 The air tube, which begins above the level of the cham- 
 ber, is covered with a button, which faves the leather 
 from being cut, and has a fmall lateral aperture for the 
 air to be carried off. This pipe paOTes along the bot- 
 tom and up the fide, and rifing above the level of the 
 ■water in the ciftern, is there clofed, except a fmall late- 
 ral aperture through which the sir efcapes. H, A 
 guard or rim with crofs bars put over the leather to 
 keep it from being forced up by the water. It is faf- 
 tened down by means of two notches on oppofite fides 
 of the guard, by which it locks into two ftaples rivet- 
 ted into the bottom of the bafon. I, The lid Aiding 
 down to cover the water from dulf , and fufpended at 
 pleafure by means of KK, two fprlngs on each tube 
 for that purpofe. I.MNO, A cylindrical box contain- 
 ing charcoal, which is connefted with the above by 
 means of the tube P, and a continuation of the tube B. 
 LM, The water tube B continued below the charcoal 
 apparatus, fo that the fluid may pafs through the fame 
 into the cylinder, from whence it enters the chambers 
 at P, fo as to be filtered through the leather as before 
 defcribed. RR, Collars which may be unfcrewed at 
 pleafure, fo as to detach the charcoal apparatus when- 
 ever the charcoal requires to be purified by heat. SS, 
 Two cocks to direft the fluid through the charcoal cy- 
 linder, or immediately into the filtering chamber. 
 
 Fig. 2. A, A tub or cillern containing the oil to be 
 filtered, and fupplying a tube of fufficient height for 
 the hydroftatic prefFure to operate. BB, A main tube 
 of wood, tin, leather, or cloth, to which anv number of 
 bags, of the fize and fiiape of corn facks, or any CC, 
 convenient fize or fhape may be connected. Thefe are 
 bound to DDD, ftraight double iron bars, furniflied 
 with a hinge at one end and a fcrew at the other, by 
 opening which the bags may be emptied. F, A trough 
 underneath, made to receive the filtered oil from the 
 i-eceivers EEP2. 
 
 Fig. 3. A, A funnel callc or ciftern, into which the 
 fluid is put which palFes down. B, A tube fitted into 
 the fame, through which it enters. C, An iron ftill, 
 or ftill of any other fubftance capable of fuftaining heat, 
 full of finely powdered and fiftcd charcoal, through 
 
 30 
 
 40 
 
 20 
 
 200 
 
 630 
 
 2 ] FIR 
 
 the head of wlitch the fluid pafTes into any receiver, 
 D, A fire-place of any conftruAion to drive over the ' 
 fluid remaining interfperfed among the charcoal, and 
 alfo to purify the charcoal by ?n increafe of temperature 
 when required. E, A cock to let water into the flues 
 to cool the apparatus fur a fubfequcnt operation. 
 
 Fig. 4. The trial glafs with its tliermometer. 
 
 FIRE. See that article Enrycl. and C.iLORic and 
 Combustion, CnRMisTRr-Inilex in this Siippl. 
 
 Exliiifiion of FikE is fometimes a matter of fo much 
 confequcncc, that every thing which promifes to be ef- 
 ftrtual for that purpofe is worthy of attention. In the 
 nineteenth number of Mr Nicholfon's Journal of Phiio- 
 fophy, Cliemillry, and the Arts, we have the following 
 compofition for extinguifliing fire, invented by M. Von 
 Aken. 
 
 Burnt alum .... pounds 
 
 Green vitriol powdered ... 
 
 Cinabrcfe or red ochre in powder 
 
 Potter's clay, or other clay, alio powdered 
 
 Water 
 
 With 40 meafures of this mixture an artificial fire 
 was extinguifhed under the dlreftion of the inventor 
 by three pcrfons, which would have required the labour 
 of 20 men and 1500 meafures of common water. Sig. 
 Fabbroni was commiflioncd to examine the value of 
 this invention, and found in his comparative trials with 
 engines of equal power, worked by the fame number of 
 men, that the mixture extinguifhed the materials in 
 combuftion in one fixth part lefs time, and three eighths 
 lefs of fluid than when common water was ufed. He ob- 
 ferved, as might indeed have been imagined from the na- 
 ture of the-Tnaterial, that the flam.e difappeared where- 
 ever the mixture fell, and that the faline, metallic, and 
 earthy matters, formed an impenetrable lute round the 
 hot combulbble matter, which prevented the acccfs of 
 the air, and confequently the renewal of the deflrutlive 
 procefs. 
 
 This recipe, Mr Nicholfon informs us, is taken from 
 N" 85. of Giornak Lflterario dl Napoll, in which it was 
 inferted in the form of a letter from Sig. Fabbroni to 
 Sig. D. Luigi Targioni of Naples ; and the author of 
 the letter cftimates the price of the compofition at about 
 one halfpenny per pound. 
 
 The reafon afligned by Mr Nicholfon for giving this- 
 abridged account a phce in his valuable work, will be 
 admitted by him and the public as a fufficient reafon for 
 our adopting it into our's. It is, that fuch inventions 
 are worthy of the attention of philofophers and econo- 
 mifts, even though in the firll applications they may 
 prove lefs advantageous than their inventors may be 
 difpofed to think. It is fcarcely probable that this 
 praftice in the large way, with an engine throwing up- 
 wards cf 2ro gallons (value about I>.3, los.) each mi- 
 nute, would be thought of or adopted, or that a fuf- 
 ficient ftore of the materials would be kept in readi- 
 nefs ; fince at this ote the expenditure for an hour 
 would demand a provifion to the amount of L. 210 
 fterling. But in country places the procefs, or fome 
 variation of it, might be applied with fufficient profit 
 in the refult ; more efpecially if it be confidered that 
 common fait or alum, or fuch faline matter as can be 
 had and mixed with the water, together vi'ith clay, 
 chalk, or lime, ochreous earth or common mud, or even 
 thefe laft without any fait, may anfwer the purpofe of 
 
 the 
 
 Pire.
 
 F I R 
 
 Tie. the lute- with more or Icfs efFefl, and cxtinguini an ac- 
 —w—^ tiJental fire with much greater fpeed and certainty than 
 tleai' water would do. 
 
 FiRE-Dalh arc meteors, of which fome account has 
 hecn given in tlie EncyclopitJia, as well as of various 
 liypothrtVs which have been frarred rtfpefling tlieir na- 
 ture and their crigin. Since that article was puhliilied, 
 a new. and very firigular hypothecs has been Iratntd by 
 Profcfl'oi' Chladni of Wittenberg, who maintains it by 
 arguments, which, however fanciful, are yet worthy of 
 PW/.-lf.'f the reader's notice *. 
 
 'osjaiid?" He fuppofcs thnt fire-balls, inftead of being collec- 
 tions of the cloiSlrical fluid floating in the higheil re- 
 gions of our atmofphere, are mafiVs of very deufe mat- 
 ter formed in far dillant parts of fpace, and fubieAed 
 to fimilar laws with the planets and comets. He en- 
 deavours to prove that their component parts mull be 
 denfe and heavy ; becaufe their rourfe fhews, in fo ap- 
 parent a manner, the efFcfts of gravity ; and becaufe 
 their mafs, though it didends to a monflrous (iy.e, re- 
 tains fiilficient confiftency and weight to continue au 
 exceedingly rapid movement thrcugh a very large fpace, 
 without being decompofed or diitolved, notwithlland- 
 ing the refiftance of the atmofphere. It fceir.s to him 
 probable, that this fubftance is by the effcA of fire re- 
 duced to a tough fluid condition ; becaufe its form ap- 
 pears fometimes round and fometinies ekmgated, and 
 as its extending till it burils, as well as the burfling it- 
 felf, allows us to fuppofe a previous capability of ex- 
 tenfion by elaftic fluidity. At any rate, it appears to 
 be certain, that fuch denfe matter at fo great a height 
 is not collefted from particles to be found in our atmo- 
 fphere, or can be thrown together into large mafiVs by 
 any power with vi'hich we are acquainted ; that no 
 power with which we are acquainted is able to give 
 to fuch bodies fo rapid a projectile force in a diredflon 
 almoft parallel to the horizon ; that the matter does 
 not rife upwards from the earth, but exifts previoufly 
 in the celeftial regions, and muft have been conveyed 
 thence to our earth. In the opinion cf Dr Chladni, 
 the following is the only theory of this phenomenon 
 that agrees with all the accounts hitherto given, which 
 is not contrary to nature in any other refpeft, and 
 which befides feems to be confirmed by various mafles 
 found on the fpot where fire-balls fell. 
 
 As earthy, metallic, and other particles form the 
 principal component parts of our planets, among which 
 iron is the prevailing part, other planetary bodies may 
 therefore confitl of fimilar, or perhaps the fame com- 
 ponent parts, though combined and inodified in a very 
 different manner. There may alio be denfe matters ac- 
 cunmlated in fnialler mafles, without being in immediate 
 connexion with the larger planetary bodies difpcvfed 
 throughotit infinite fpace ; and which, being impelled 
 either by lome projefting power or attraction, continue 
 to move until they approach the earth or fiime other 
 body, when, being overcome by its attradlive force, 
 they immediately fall down. By their exceedingly 
 great velocity, ftill increafed by the attradlion of the 
 earth and the violent fridion in the atmofphere, a ftrong 
 eledriclty and heat muft neceflarily be excited ; by 
 which means they are reduced to a flaming and melted 
 condition, and great quantities of vapour and different 
 kinds of gafes are thus difengaged, which dilUnd the li- 
 quid mafs to a monftrous fize, till, by a ftill farther cs- 
 
 6i3 ] . F I R 
 
 panfion of thefe elaftic fluids, it muft at length buift. 
 Dr Cliladni thinks alfo, that the greater part of the 
 JhooUng Jiars, as they are called, are nothing tlfe than 
 fire-balls; which diflcr only from the latter in this, that 
 their peculiarly great velocity carries them paft the 
 earth at a greater diltance, fo that they arc not fo 
 ftrongly attracted by It as to fall down ; and theiefore, 
 in their pafllige through the high regions of the atmo- 
 fphere, occaiion only a tranfient elcArlc flafli, or aftuaU 
 ly take fire for a moment, and are again fpetdily extin- 
 guilheil, when they get to fuch a diftance from tlie earth 
 that the air becomes too much rarefied for the exift- 
 ence of fire. 
 
 The grounds on which Dr Chladni fupports this opi- 
 nion are various relations, well authenticated, of the mo- 
 tions of thofe meteors, and the phenomena which ac- 
 company their burfting. Befides thole mentioned In the 
 Ell r\ clop. tdia, he lays a particular ftrefs on the account 
 which he received from M. Baudin, Profeflbr of phl- 
 lofophy at Pan, of a remarkable fiery meteor fcen in 
 Grtfcony on the 24th of Jidy I "90. On the evening 
 of that day M. E;uidln was in the court cf the callle 
 of Marmes with a friecd, the atmofphere being pertcft- 
 ly clear, when they fuddeidy found ihemfelves liirround- 
 ed by a whitini light, whitli obfeured that of the full 
 moon, then flu'ning with great lullre. On looking up- 
 wards, they obferved, almoft in their zenith, a fire-ball 
 of a larger diameter than the moon, and with a tail 
 equal in length to five or fix times the diameter of the 
 body. The ball and the tail were of a pale white co- 
 lour, except the point of the latter, which was almoft 
 as red as blood. The dhtdion of this meteor was 
 from fouth to north. 
 
 " Scarcely (fays M. Baudin) had we looked at it 
 for two feconds when it divided ilfelf into feveral por- 
 tions of confiderable fize, which we faw fall in different 
 dlrecitions, and almoft with the fame appearance as the 
 burfling of a bomb. All thefe different fragments be- 
 came cxtingulflied in the air ; and fome ot them, in 
 falling, affumed that blood-red colour which I had ob- 
 ferved in the point of the tall. It Is not improbable 
 that all the reft may have affuined the fame colour ; but 
 I remarked only thofe which proceeded in a direction 
 towards Mormcs, aiid which were particularly expofed 
 to my view. 
 
 " About two minute^i and a half, or three minutes 
 after, we heard a dreadful clap of thunder, or rather 
 explofion, as if feveral large pieces of ordnance had beca 
 fired off together. The concufiion of the atmofphere 
 by this fliock was fo great, that we all thought an 
 earthquake had taken place, 'i'he windows fliook in 
 their frames, and fome of them, which probably were 
 laid to and not cloftly fnul"; were thrown open. We 
 were informed next day, that in fome of the houfes at 
 Houga, a fmail town about half a mile diftant from 
 Mormes, the kitchen uteiilils were thrown from the 
 flielves ; fo that the people concluded there had been 
 an earthquake. But as no movement was oblerved ia 
 the ground below our feet, I am inclined to think that 
 all thefe effefts were produced merely by the violent 
 concuffion of the atmofphere. 
 
 " We proceeded into the garden while the noife ftill 
 continued, and appeared to be in a perpendicular di- 
 reftion above us. Some time after, when it had ceafed, 
 we heard a hollow noife, which fecined to roll along- 
 
 the 
 
 Fire.
 
 T.>\ 
 
 FIR [ 654 ] FIR 
 
 the chain of tlic Pyrenees ir. echoes, for the diftance of one of them erer proceeded upwards. All of thsm 
 
 1 ; miles. It continued about four minutes, becoining have appeared under the form of a globular mafs, fome- *■ 
 
 gradually more remote, an(i;,:.vay9 weaker; and at the times a little extended in length, and highly luminous; 
 
 lame time we perceived a llrong fmell of fulphur. having behi'id it a tail, which, according to every np- 
 
 " While we were endeavouring to point out to fonie pearance, w.is compoled of flames and fnioke. All of 
 
 jierions prefent the place where the meteor had <llvidcd them burll aticr they were feen to move through a large 
 
 itielf, we obfervcd a fmall whitidi cloud, which arofe fpace, lometiineB over ftveral diftrida, with an explofion 
 
 perhaps from the vapour of it, and which concealed 
 irom us the three liars of the Great Bear, lying in the 
 ini'lJL- of thofe forming the femiciicle. With fome 
 <lifhculty, however, we could at lall diflinguiih thefe 
 ilars again behind the thin cloud. There arofe, at the 
 fame time, a frelh gentle breeze. 
 
 " From the time that elapfed between the burlling 
 /if the ball and the ex-plofion which followed, I was in- 
 
 wlucli (liook every thing around, In every inilance 
 where there has been an opportunity of obfervi.ig the 
 fragments that fell after they burft, and which I'ome- 
 times have iunk to the depth of feveral feet into the 
 earth, they were found to confili: of fcorious mafles, 
 which contained iron in a metallic or calcined ilate, 
 pure, or elle mixed with different kinds of earth and 
 fulphur. All the ancient and modern accounts, writ- 
 
 «lined to think that the meteor was at the height of ten partly by natiiralifts and partly by others, are fo 
 
 T.t leail feven or eight miles, and that it fell four miles effentially funilar, that the one feems to be only a re- 
 
 to' the north of Mormes. The latter part of my con- petition of the other. This conformity in accounts, 
 
 ■jefture was foon confirmed by an accoiiat which we re- the authors of which knew nothing of thole given by 
 
 ceived, that a great many ftones had fallen from the others, and wlio could have no interelf in fabricating 
 
 atmofphere at Jnliac, and in the neighbourhood of Bar- fnnilar tales, can fcarcely have arifen from accident or 
 
 botan. One of thefe places lies at the dittance of fiftion, and gives to the related fafts, however inexpli- 
 
 . about four miles to the north of Mormes, and the cable many of them may fecm, every degree of credi- 
 
 iither at about the diftance of five to the north-north- bdity. 
 
 •weft." 
 
 M. de Carrits Barbotan, the friend who was with 
 the Profeifor in the court and garden of Mormes when 
 the meteor firfl attrafted their attention, was at Juliac 
 
 In the third volume of Pallas's Travels, we have an 
 account of a mafs of iron difcovered by him in Siberia, 
 which Dr Chladni confiders as having been undoubted- 
 ly a fire-ball, or the fragment of a fire-ball. This pro- 
 
 two days afterwards, and confirmed to him the truth of blematical mafs was found between Krafnojarfk and A- 
 
 this circumftance. It appeared, likewife, from the ac- bekanflc in the high flate mountains, quite open and 
 
 count of feveral intelligent perfons, highly worthy of uncovered. It weighed 1603 pounds; had a very ir- 
 
 • credit, that the meteor burft at a little diftance from regular and fomewhat comprefi'ed figure like a rough 
 
 J;diac, and that the ftones which fell were found lying granite ; was covered externally with a ferruginous 
 
 :n a fpaee almoft circular, about two miles in diaineter. 
 They were of various iizes. Some were Jien to fall, 
 which, when found, weighed 18 or 20 pounds, and 
 which had funk into the earth from two to three feet. 
 
 kind of cruft ; and the iniide confifted of malleable iron, 
 brittle when heated, porous like a large fea fponge, 
 and having its intcrftices filled with a brittle hard vitri- 
 fied fubtlance of an amber yellow colour. This texture 
 
 M. de C. Barbaton tranfmitted one weighing 18 pounds and the vitrified fubifanee appeared uniformly through- 
 
 • to the Academy of Sciences at Paris; and M. Ijaudin out the whok mafs, and without any traces of flag or 
 
 was told, that fome were found which weighed even artificial fire. 
 
 50 pounds. He examined a fmall one, and found it Dr Chladni fhews, with a great deal of ingenuity, 
 
 very heavy in proportion to its fize : it was black on that this mafs neitiier originated by the wet method, 
 
 the outfide; of a greyifli colour in the infide, and inter- nor could have been produced by art, the burning of a 
 
 fpcrfed with a number of fmall fhining metallic par- foreft, by lightning, or by a volcanic eruption. It ap- 
 
 tides. On ftriking it with a piece of ftecl, it produced pears to him, therefore, in the higheft degree probable, 
 
 3 few fmall dark red fparks, not very lively. A mine- that it is of the fame nature with fire-balls, or, as they 
 
 ralogift, to whom a like piece of ftone from the fame have foraetimes been called, ^v'"i' dragons. The Tar- 
 
 itieteor was fhewn at Paris, defcribed it as a kind of tars, as we are informed by Pallas, confidered this mafs 
 
 grey flag mixed with calcareous fpar, the furface of as a facred relic which had dropped down from heaven ; 
 
 which exhibited vitrified blackifh calx of iron. The and this circumftance Dr Chladni confiders as no flight 
 
 Profeffor was told alfo, that- fome ftones were found to- confirmation of his opinion, which he fartuer fupports 
 
 tally vitrified. by the following reafonings : 
 
 Such (fays Dr Chladni) Is the account given by Bau- " i. As fire-balls confift of denfe and heavy fubftances, 
 
 tiln of this meteor ; the phenomena of which he endea- which, by their exceedingly quick movement, and the 
 
 vours to explain from accumulations in the upper parts friftlon thence excited by the atmofphere, become elec- 
 
 of the atmofphere. trie, are reduced to a ftate of ignition, and melted by 
 
 According to all the obferv^tions hitherto made with the heat, fo that they extend to a great fize, and burft; 
 -any accuracy on fire-balls, the height at which they it .thence follows, that in places where fragments, pro- 
 were firft perceived was always very confiderable, and duced by the burfting of a fire-ball, have been found, 
 by comparing the angles under which they were feen fubftances endowed with all thefe properties muft alfo 
 from different points, often 19 German miles, and even have been found. Iron, however, the principal compo- 
 more ; their velocity, for the moft part, feveral miles in nent part of all the malfes hitherto found (and he fpeaks 
 a fecond ; and their fize always very great, often a of many befides that of Pallas), pofTeffes all thefe pro- 
 quarter of a mile, and even more, in diameter. They perties in a very eminent degree. The weight and 
 were all feen to fall moftly in aa obhque direction ; iiot toughnefs of the principal component parts of fireballs, 
 
 which 
 
 rtr
 
 FIR . [ 655 ] FIR 
 
 wMcfi muft be very confiderable, fince, with the great- by what means they were brought 
 fil pofTible liillention, thcv retain confidence enough to 
 
 licy 
 proceed witli the iitmoil velocity through fuch :iii im- 
 menfe fpnce without t)ccotni>orition of tlieir mafs, and 
 without tlieir progrefs being obllrudtcd by the ret'iil- 
 aiice of the air, agree perfeiUv well with melted iron; 
 their dazzling white light has by mariv obfervcrs been 
 compared to that of melted iron ; iron alfo exhibits the 
 fame appearances of flaming, fniokiiig, and throwing 
 out fparks, and all thcfe phenomena are inoft beautiful 
 when they take place in vital air. Of the extenfion by 
 elailic fluids expanded by the heat, and of the contrac- 
 tion which follows from cold, traces may be difcovered 
 in the internal fpongy nature of the iron maffes which 
 Iiave been found, and in the globular depreflions of the 
 exterior hard cruft ; the latter of which gives us reafon 
 to fuppofe, that in thcfe places there have been air- 
 bubbles, which, on cooling, funk down. The inixture 
 of fiilphur found in various maffes, agrees alfo exceeding- 
 ly well with the phenomena of fireballs, and efpeciaily 
 with the great inflammability of fulphur in very thin 
 impure air ; for it is well known that fulphur in an air- 
 pump will take fire in air in which few other bodies 
 could do the fame. In regard to thofe mad'es in which 
 no fulphur was found, this may have arii'en from the 
 fulphur efcaping in vapour, fince fome time after the ap- 
 pearance of fire-balls a ftrong fmell of fulphur has been 
 perceived. The brittlenefs of the Siberian iron mafs 
 when heated, may arife from fome fmall remains of ful- 
 phur, which may perhaps be the caufe of the facility 
 with which fragments of this mafs, as well as of another 
 found at Aix-laChapelle, could be roafted. 
 
 " 2. The whole texture of the mafles betrayed evident 
 Cgns of fufion. This, however, cannot have been oc- 
 cafioned by any common, natural, or artificial fire; and 
 particularly for this reafon, becaufe iron fo malleable is 
 not fufible in fuch fire, and when it is fufed with the 
 addition of inflammable matters, lofes its malleability, 
 and becomes like common raw iron. The vitrified fub- 
 ftance in the Siberian mafs is equally incapable of be- 
 ing fuled in a common fire. The fire, then, muft have 
 been much ftronger than that produced by the com- 
 mon, natural, and artificial means ; or the fufion muft 
 have been effefled by the force of exceedingly ftrong 
 eleflrlclty ; or perhaps both caufes may have been com- 
 bined together. 
 
 " 3. It Is totally incoraprehenfible how, on the high 
 flate mountains, where the Siberian mafs was found, at 
 a confiderable diftance from the iron mines ; in the 
 chalky foil of the cxtenlive plains of America, where 
 for a hundred miles around there are no iron mines, 
 and not even fo much as a ftone to be found ; and at 
 Alx-la-Chapelle, where, as far as the author knows, 
 there are no iron works — fo many ferruginous particles 
 could be collefted in a fmall fpace as would be neccf-' 
 fary to form mafles of i6oo, 15,000, and 17,000, up 
 to ^^,600 pounds. This circuniftance flicws that thefe 
 mafles could as little have been fnfed by lightning as 
 by the burning of a foreft or of foflile coaL Thefe 
 mafles were found quite expofed and uncovered, and 
 not at any depth in the earth, where we can much 
 more readily admit fuch an accumulation of ferruginous 
 particles to have been melted by tlie effcdis of light- 
 ping. 
 
 *' Should it be ailied how fuch maffes originated, or 
 
 into fuch an infu- 
 latcd pofition ? this queftion would be the fante as if it " 
 were aflied how the planets originated. Whatever hy. 
 pothcfes «e may form, we mull either admit that the 
 planets, if we except the many revolutions v.hich they 
 may have undeigone, either on or neni- their furface, 
 have always been fince their firft formation, and ever 
 will be the fame ; or that Nature, atllng on created 
 matter, poffi fles the power to produce worlds and whole 
 fylfems, to deftroy them, and from their materials to 
 form new ones. For the latter opinion there are, in- 
 deed, more grounds than for the former, as alterr.allons 
 of deftruftion and creation are exhibited by all orgu- 
 nlfed and unorganlfed bodies on our earth; which gives 
 us reafon to fulpeft that Nature, to nhich greatnefs and 
 fmalhiefs, confideicd in general, are merely relative terms, 
 can produce more cfTefts of the fame kir.d on a larger 
 fcale. But many variations have been obferved on dif- 
 taut bodies, which, In fotnc meafure, render the laft 
 opinion probable. For example, the apjiearlng and to- 
 tal dlfappearing of certain flars, when they do [lot de- 
 pend upon periodical changes. If we now admit th;K 
 planetary bodies have ftarted into cxiftencc, we cannot 
 luppofe that fuch an event can liave otherwife taktrv 
 place, than by conjefturing that either particles of mat- 
 ter, which were before difperfed through infinite fpace 
 in a more foft and chaotic condition, have united to- 
 gether in large mafles by the power of attraftlon ; or 
 that new planetary bodies have been formed from the 
 fragments of much larger ones that have been brokeo 
 to pieces, either perhaps by fome external fhock, or 
 by an internal explofion. Let whichever of thefe hy- 
 pothefes be the truefl, it i;; not improbable, or at Icaft 
 not contrary to nature, if we fuppole that a large quan. 
 tity of fuch material particles, either on account of 
 their too great dillauce, or becaufe prevented by a 
 ftronger movement In another diredlion, may not have 
 united themfelves to the larger accumulating mafs of a 
 new world ; but have remained infulated, and, impelle.l 
 by foine fliock, have continued their courfe through In. 
 finite fpace, until they approached fo near to fome pla- 
 net as to be within the fphere of its attraflion, and 
 then by falling down to oecafion the phenomena before 
 mentioned." 
 
 WhetherChladiil be a philofopher of the French fchool 
 we know not; but fome parts of his th.'ory tend ftrong- 
 ly towards materialifm ; and the arguments by which 
 he attempts to prop thofe jiarts are peculiarly weak. 
 When he talks ui JValure producing worlds, he either 
 fubftitutes Nature for Nature's God, or utters jarTon 
 which has no meaning. In what fenfc the word Nature 
 is ufed by every philofjpher of a found mind, \vt have 
 elfewhere been at fome pains to fhew (fee River, 11" 1 16. 
 Eiicyc!.).; but how rbfurd would it be to fay, that the 
 fyftem of general laws, by which the Author and Go- 
 vernor of the unlverfe connefts together its variuus 
 parts, and regulates all their operations, poflefles, inde- 
 pendently of Him, " the power to produce worlds and 
 whole fyftems, to deftroy them, and from their mate- 
 rials to form new ones !"' 
 
 As Chladni admits, or talks as If he admitted, the 
 creation of matter, it would be wrong to impute to 
 him this abfurdlty ; but if by Nature he means God, 
 and he can confiftently mean nothing elfe, we beg leave 
 to afBrm, that it is dtrtttly lontrar^ to every notioi*- 
 
 whicii 
 
 rirc.
 
 Pirf, 
 
 FIR [ 6s6 
 
 which we can form of Nature in ihh fcnp, " to fiippofe 
 ' tliat a large quantity of mate-rial jjarticlfj, either on ac- 
 count of the dijlance, or bccaufe prevented by zjironger 
 movement in another diredlion, have not united tlicm- 
 fclves to the larger accumulating mafs of a new world, 
 but remained inful.ited, and impelled by fome fiiock, 
 have continued their courfe through infinite fpace, &c." 
 Is there any diftance to which God cannot reach, or 
 any movement fo (Irong as to refdl his power ? Our 
 author's language is indeed confufed, and probably his 
 ideas were not very clear. When he fpeaks of tlie par- 
 
 r I s 
 
 tides of matter being at firft dilperfed through iiifinite 
 fpace, and afterwards united by the power of attrac- 
 tion, he revives the queflion which was long ago dif- 
 cuffed between Newton and Bentley, and difeufFed in 
 fuch a manner as fliould have filenced for ever the bab- 
 blings of thofe who form worlds by attraftlon. 
 
 " The hypothefis (fays Newton) of matter's being 
 at firft evenly fpread through the heavens, is, in my opi- 
 nion, inconfiftent with tlie hypotliefis of innate gravity 
 ■without a fupernatural power to reconcile them ; and 
 therefore infers a Dtity. For if there be innate gravi- 
 ty, it is impoflible now for the matter of the earth, and 
 all the planets and liars, to fly up from them, and be- 
 come evenly fpread through all the heavens, without a 
 fupernatural power ; and ccrt;iinly that which can ntver 
 he hereafter without a fupernntural power, could never 
 be heretofore without the fame power." Dr Chladni, 
 indeed, does not fay that his particles of matter were 
 evenly difperfcd through infinite fpace ; but fuch muft 
 be his meaning, if he has any meaning : for matter urir 
 evenly difperfed muft, by an innate attradlion, be united 
 as foon as it exifts, and fo united as not to leave fmall 
 fragments of it to wander, we know not why, tiirovigh 
 the tracklefs void. Turn matter on all fides, make 
 it eternal or of late production, finite or infinite, there 
 can be no regular fyftem produced but by a voluntary 
 and meaning agent ; and tliertfore, if it be true that 
 fire-balls are maifes of deufe matter, coeval with the pij- 
 netary fyftem, exifting in the celeftial regions, and 
 thence conveyed to our earth, they muft have been 
 formed, and their motions imprefted upon them, by the 
 Author of Nature for fome wife purpofe, though by 
 us that purpofe mav never be difcovered. One thing 
 feems pretty clear, that wherever they may be formed, 
 the phenomena attending their burftiug, account fuffici- 
 ently for the notions of thunderbolts which have been 
 generally entertained in all ages, and iu every country. 
 
 Grcel-FiRE (fee IV'il.i-FiKf., Ertcycl.). In the fecond 
 volume of Mr N'Icholfou's Philofophical Journal, we 
 have the following receipt for making this compofition, 
 taken from fome manufcripts of Leonard de Vinci, '>vho 
 flourilhed in the end of the fifteenth and beginning of 
 the fixteenth centuries, and who appears to have advan- 
 ced far before his contemporaries in phyfical fclence. 
 Take the charcoal of willow, nitre, brandy, refin, fal- 
 phur, pitch, and camphor. Mix the whole together 
 over the fire, i'lunge a woollen cord in the mixture, 
 and form it into balls, which may afterwards be pro- 
 vided with fpikes. Thefe balls, being let on fire, are 
 thrown into the enemy's vefl'els. It is called the Greek 
 fire, and is a fingular compofition, for it burns even up- 
 on the water. Callinicus the architect taught this com- 
 pofition to the Romans (of Conftantinople), who de- 
 rived great advantage from it, particularly under the 
 
 emperor Leo, wlieii the Orientals attdeked Conflnnti'- 
 iiople. A great number of their vefleU were burned 
 by means of this compofition. 
 
 The compofition of the Greek fire thus given by 
 Vincini is found in nearly tlie fame words in fome of the 
 writings of Baptifta Porta; whence it appears tliat both 
 authors derived their information from the fame fource. 
 A compofition wliich burnt without acccfs to the at. 
 mofphere could not fail to fill the minds of our fore- 
 fathers with wonder; but the modern d:fcoveries in 
 chemiftry have diiclofed the fecret, by (liewing, that 
 the combuftioi) is carried on by means of the oxygen 
 contained in the nitre. 
 
 Rafant or Ra-zant Fire, is a fire from the artillery 
 and fmall arms, dircfted parallel to the horizon, or to 
 thofe parts of the works ol a place that are defended. 
 
 Runn'-ng Fnf^ is when ranks of men fire one after 
 anotlier ; or when the lines of an army arc drawn out 
 to fire on account of a viftory ; in which cafe each fqua- 
 dron or battalion takes the fire from that on its right, 
 from the right of the firft line to the left, and from the 
 left to the right of the fecond line, &c. , 
 
 FISHING, the art of catching fi(h. See Angling, 
 Fishery, and Fishing, &c. Encycl. 
 
 Chinefe FisHiNG. We venture to give this appella- 
 tion to lome very ingenious contrivances of the people 
 of China for catching in their lakes, not only fiOi, but 
 waterfowl. For the purpofe of catching fifii they have 
 trained a fpecies of pelican, refembling the common cor- 
 vorant, which they call the Leu-tze, or fidu'ng-bird. It 
 is brown, with a white throat, the body whitifti beneath, 
 and fpotted with brown ; the tail is rounded, the irides 
 blue, and the bill yellow. Sir George Staunton, who, 
 wiien the embaffy was proceeding on the fouthern 
 branch of the great canal, faw thofe birds employed, 
 tells U3, that on a large lake, clofe to the eaft i'lde of 
 the canal, are thoufands of fmall boats and rafts, built 
 entirely for this fpecies of fifliery. On each boat or 
 raft are ten or a dozen birds, which, at a fignal from 
 the owner, plunge into the water; and it is aftoiiifhing 
 to fee the enormous fize of fifli with v.-hioh they return, 
 graiped within their bills. They appeared to be fo well 
 trained, that it did not require either ring or cord about 
 their throats to prevent them from fwallowing any por- 
 tion of their prey, except what their mafter was pleafed 
 to return to them for encouragement and food. The 
 boat ufed by thefe filhermen is of a remarkable light 
 make, and is often carried to the lake, together with 
 the fifliing birds, by the men who are there to be fup- 
 porteJ by it. 
 
 Tlie fame author faw the fidiermen hufy on the great 
 lake Wee-chaung hee ; and he gives the following ac- 
 count of a very fingular method praftlfed by them for 
 catching the fifh of the lake without the aid of birds, 
 of net, or of hooks. 
 
 To one fide of a boat a flat board, painted white, 
 is fixed, at an angle of about 45 degrees, the edge in- 
 clining towards the water. On moonlight nights the 
 boat is fo placed that the painted board is turned to 
 the moon, from whence the rays of light ftriking on the 
 whitened furface, give to it the appearance of moving 
 water ; on which the fifti being tempted to leap as on 
 their element, the boatmen, rifing with a ftring the 
 board, turn the fifli into the boat. 
 
 Water-fowl are much fought after by the Chinefe 
 
 and
 
 F I S [ 657 J . )^' L A 
 
 Piftula. and are taken upon the fame lake by the following in- (lu.u)d ca»h time be inji-cltd through tlie duft into the 
 
 —^r~— genious device. Empty jars or gourds are fufFercd to nolV, and tht inlbiiment be nftrrwards replaced in the j^ 
 
 iloat about upon the water, that Inch objects may be- fame manner as before. Mr Wart- formerly ufid to 
 
 come familiar to the birds. The fillierman then wades cover the head of the flyle with a piece of diachylon 
 
 into the lake with one of thofe empty vefl'els upon his plaftcr fprcad on black filk, but has of late obviated 
 
 head, and walks ger.tly towards a bird ; and lifting up the neceirily for applying any plaftcr by blackening 
 
 his arm, draws it down below the furface f)f the water the head of the ftyle with fealii.g wax. 
 without any difturbance or giving alarm to the reft, " The effeft (fays he) produced by the flyle, when 
 
 fcveral of whom he treats in the fame manner, until li« introduced in the way aho\c mentioned, at firft gave 
 
 fills the bag he had brought to hold his prey. The me much furprife. It was employed with a view fimi- 
 
 contrivance itlelf is net fo (ingular, as it is that the fame lar to that with which Mr Pott recommends the intro- 
 
 exaftly ftiould have occurred in the new continent, as dudlion of a bougie ; viz. to open and dilate the naial 
 
 Ulloa afterts, to the natives of Carthagena, upon the dudt, and thus to eftablidi a paft'age, through which the 
 
 lake Cienega de Tefias. tears might afterwards be conveyed from the eye to the 
 
 FISTULA Lachrymalis Is adifeafc which, in all nofe. I expefled, however, that whilll the ftyle con- 
 its ftages, has been treated of in the article Surgery, tinued in the duft the obltrufiK.n would remain, and of 
 chap. xiv. Enrycl. A work, however, has been lately courfe that the watering of the eye, and the wcaknefs 
 publifhcd by James Ware furgeon, in which there is of the fight, would prove as troiiblefome as they had 
 the defcription of an operation for its cure confiderably been before the inftrumont was introduced. I did not 
 different from that moll commonly ufcd, and which, imagine that any cn'enlial benefit could refult from the 
 while it is fimple, the author's experience has afcertain- operation until the ftyle was removed, and the paliage 
 ed to be fuccefsful. thereby opened. It was an agreeable diiappointment 
 
 In the cure of this difeafe, which is very troublefome, to me to tind that the amendment was much more ex- 
 and not very uncommon, it is a well known practice to peditious. The watering of the eye almoft wholly 
 infert a metallic tube in the nafal duft of the lachrymal ceafed as foon as the ftyle was introduced ; and in pro- 
 canal : but the advantage derived from this operation portion as the patient amended in this refptft, his f'ght 
 is not at all times laftlng. Among other caufes of alfo became more ftrong and ufiful. The ftyle, there- 
 failure, Mr Ware notices the lodgment of infpiftated fore, feems to aft in a twofold capacity : tirft, it di- 
 uiucus in the cavity of the tube. To remedy this de- lates the ohftrufted pafl'sge ; and then, by an attrac- 
 feft, he recommends the following operation. tion fomewhat fimilar to that of a capillary tube, it 
 
 " If the difeafe has not occafioned an aperture in the guides the tears through the duft into the nofe. 
 lachrymal fac, or if this aperture be not litnated in a " The wound that 1 ufualty make into the fac, if 
 right line with the longitudinal direftion of the nafal the fupperative procefs has not formed a fuitable aper- 
 duft, a pundure ftiould be made into the fac, at a fmall ture in this part, is no larger than is juft fufficient to 
 diftance from the internal jundture of the palpebra;, and admit the end of the probe or ftyle ; and this, in gene- 
 nearly in a line drawn horizontally from this junfture ral, in a little time, becomes a fiftulous orifice, through 
 towards the nofe with a fpear-pointed lancet. The which the ftyle is pafTed without occafioning the fmallell 
 blunt end of a filver probe, ofa fize rather fmaller than degree of pain. The accumulation of matter in the la- 
 the probes that are commonly ufcd by furgeons, Ihould chrymal fac, which, previous to the operation, is often 
 then be introduced through the wound, and gently, copious, ufually abates foon after the operation has been 
 but fteadily, puftied on in the direftion of the nafal performed ; and, in about a week or ten days, the treat- 
 duft, with a force fufficient to overcome the obftruc- ment of the cafe becomes fo eafy, that the patient him- 
 tion in this canal, and until there is reafon to believe felf, or fome friend or ftrvant who is conftantiy with 
 that it has freely entered into the cavity of the nofe. him, is fully competent to do the whole that is necef- 
 The pofition of the probe, when thus introduced, will fary. It confifts folely in withdrawing the ftyle two or 
 be nearly perpendicular ; its fide will touch the upper three times in the week, occafionaliy injefting iome 
 edge of the orbit ; and the fpace between its bulbous warm water, and then replacing the inftrument in the 
 end in the nofe and the wound in the ft<in will ufually fame way in which it was done before, 
 be found, in a full-grown perfon, to be about an inch " It is not eafy to afcertain the exaft length of time 
 and a quarter, or an inch and three-eighths. The that the ftyle ftiould be continued in the duft. Some 
 probe is then to be withdrawn, and a filver ftyle, of a have worn it many years, and, not finding any inconve- 
 iize nearly fimilar to that of the probe, but rather fmal- nieiice from the inftrument, are ftill afraid and unwilling 
 ler, about an Inch and three-eighths in length, w^'th a to part from it. Others, on the contrary, have difufed 
 flat head, like that of a nail, but pla.vd obliquely, that it at the end of about a month or fix weeks, and have not 
 it may fit clofe on the Ikin, is to be introduced through had the fmalleft return of the obftruftion afterwards." 
 the duft, in place of the probe, and to be left conftant- The author relates fo many fuccefsful cafes of this 
 ly in it. For the firft day or two after the ftyle has operation, that we thought It our duty to record his 
 been introduced, it is fometimes advifable to wafh the method in this Supplementary volume of our general 
 eye with a weak faturnine lotion, in order to obviate repofitory of arts and fclcnces; for a fuccefsful praclicc, 
 any tendency to inflammation which may have been as well in furgery as in phyfic, muft reft on the bafis of 
 excited by the operation ; but this in general is fo experience. 
 
 flight, that our author has rarely had occafion to ufe Oblique or Second FLANK, or Fl.ins of /he 
 
 any apphcation to remove it. The ftyle ftiould be with- Curtain, is that part of the curtain from whence the 
 
 drawn once every day for about a week, and after- face of the oppofite baftlon can be feen, being cont.iin- 
 
 wards every fecond or third day. Some warm water ed between the lincG ral'ant and iichant, or the greatCT 
 SupPL. Vot. I. Part II. 4 O auJ 
 
 FiauU, 
 
 Fla k.
 
 F L O 
 
 [ 6: 
 
 Flank 
 
 n 
 
 Float inij. 
 
 and lefs lines of defence ; or the part of the uurtain be- 
 tween the flank and the point vvhcie the fichant line of 
 , defence terminates. 
 
 Cov^iccl, Lovi, or ReUrtti Fl/Ikk, is the platform of 
 the cafcniate, which lies hid in tlie ballion, and is other- 
 wife called the orillon. 
 
 Fkhiitit Flank, is that from whence a cannon play- 
 ing, fires direftly on the face of the oppofite baftion. 
 
 Rafant or Razant Flask, is the point trom whence 
 the line of defence begins, from the conjun6\ion of wliich 
 with the curtain the fliot only rafeth the face of the 
 next bailion, which happens when the f.tce cannot be 
 difcovered but from the flank alone. 
 
 FLIE or Fly, that part of the mariner's compafs 
 on which the thirty-two points of the wind are drawn, 
 and over which the needle is placed, and faftened under- 
 neath. 
 
 FLOATING Bodies are fuch as f-nim on the fur- 
 face of a fluid, of which the mofl Important are ihips, 
 and all kinds of velTcIs employed in war and in com- 
 merce. Every feaman knows of how much confequence 
 it is to determine the ilability of fuch veffcls, and the 
 pofitions which they afTume when they float freely and 
 at reft on the water. To accomplifli this, it is neced'ary 
 to flate the principles on which that (lability and thefe 
 pofitions depend ; and tin's has been done with fo much 
 ingenuity and fcience by George Atwood, Efq; 
 F. R. S. in the Philofophical Tranfaftions for the year 
 1796, that we are perfuaded a large clafs of our readers 
 will thank us for inferting an abilradl of his memoir in 
 this place. 
 
 A floating body is prefTed downwards by its own 
 •weight in a vertical line that pafTes through its centre 
 of gravity ; and it id fuilaincd by the upward prelfure 
 of a fluid, afting in a vertical line that paffes through 
 the centre of gravity of the immerfed part ; and unlefs 
 thefe two lines be coincident, fo that the two centres 
 of gravity may be in the fame vertical line, the folid 
 will revolve on an axis, till it gains a pofition in which 
 the equilibrium of floating will be permanent. Hence 
 it appears, thab it is neceifary, in the liiit place, to af- 
 certain the proportion of the part immerfed to the 
 whole ; for which purpofe the fpecific gravity of the 
 floating body mull be known ; and then it mull be de- 
 termined, by geometrical or analytical methods, in what 
 pofitions the folid can be placed on the furface of the 
 fluid, fo that the two centres of gravity already men- 
 tioned may be in the fame vertical line when a given 
 part of the folid is immerfed under the furface of the 
 fluid. When thefe preliminaries are fettled, fomething 
 ilill remains to be done. Pofitions may be afTumed in 
 whicii the circumflanecs jull recited concur, and yet 
 the folid will alTume fome other pofition in which it 
 will permanently float. If a cylinder, e.g. having its 
 fpecific gravity to that of the fluid on which it floats 
 as 3 to 4, and its axis 10 the diauicter of the bafe as 2 
 to I, be placed on the fluid with its axis vertical, it 
 will fink to a depth equal to a diameter and a half of 
 the bafe ; and while its axis is prcferved in a vertical 
 poiition by external force, the centres of gravity of 
 th: whole folid and of the immerfed part will remain in 
 the fame vertical line : but when the external force that 
 fuilained it is removed, it will decline from its upright 
 pofition, and will permanently float with its axis hori- 
 zontal. If the axis be fuppofed to be half of the dia- 
 
 8 ] FLO 
 
 meter of the bafe, and be placed vertically, the folid Floating, 
 will fink to the depth of three-eighths of its diameter ;^~""V— ^ 
 .nnd in that pofition it will float permanently. If the 
 axis be made to incline to the vertical line, the folid 
 will change its pofition until it ftttVs permanently with 
 the axis perpendicular to the horizon. 
 
 Whether, therefore, a folid floats permanently, or 
 overfets when placed on tlie furface of a fluid, fo that 
 the centre of gravity of the folid and that of the part 
 immerfed (hall be in the fame vertical line, it is faid to 
 be in a pofition of equilibrium ; and of this equilibrium 
 there are three fpceies, viz. the equilibrium of ftability, 
 in which the folid floats permanemly in a given pofi- 
 tion ; the equilibrium of inftability, in which the folid, 
 though the two centres of gravity already mentioned 
 are In the fame vertical line, fpontaneouily overfets, un- 
 lefs fupported by external force ; and the equilibrium 
 of indifference, or the infenfible equilibrium, in which 
 the folid refU on the fluid indllfcrent to motion, with- 
 out tendency to right itfclf when inclined, or to inchne 
 itfelf farther. 
 
 If a folid body floats permanently on the furface of 
 a fluid, and external force be applied to Incline it from 
 its pofition, the refiflance oppofed to this inclination Is 
 termed the ftability of floating. Among various float- 
 ing bodies, lome lofe their quiefcent pofition, and fome 
 gain it, after it has been interrupted, with greater fa- 
 cility and force than others. 
 
 Some (hips at fea (e.g.) yield to a given impulfe of 
 the wind, and fufier a greater inclination from the per- 
 pendicular than others. As this refiftance to heeling 
 or pitching, duly regulated, has been deemed of impor- 
 tance in the conftruclion of veflels, feveral eminent ma- 
 thematicians have inveftlgated rules for determining 
 the ftability of flilps from their known dimenfions and 
 weight, without recurring to aflual trial. To this 
 clafs we may refer Bouguer, Euler, Fred. Chapman, 
 and others ; who have hid down theorems for this pur- 
 pofe, founded on a fuppofitlon that the Inclinations of 
 fliips from their quiefcent pofitions are evanefcent, or, 
 in apradllcal fenfe, very fmall. 
 
 " But flilps at fea (fays onr ingenious author) are 
 known to heel through angles of ic°, 20°, or evcii 
 io" ; and therefore a doubt may arife how far the rules, 
 demonftrated on the exprefs condition that the angles 
 of inclination are of evanefcent magnitude, fhould be 
 admitted as praftically applicable in cafes where the 
 inclinations are fo great." — " If we admit that the 
 theory of ftr.tlcs can be applied with any effeft to the 
 praftice of naval architecture, it feems to be neceifary 
 that the rules, inveftlgated for determining the ftability 
 of veffcls, fliould be extended to thofe cafes in which 
 the angles of inclination are of any magnitude likely to 
 occur m the pradllce of navigation." 
 
 A folid body placed on the furface of a lighter fluid, 
 at the depth correfponding to the relative gravities,, 
 cannot change Its pofition by the combined adions of 
 its weight and the prelfure of the fluid, except by re- 
 volving on fome horizontal axis which palfes through 
 the centre of gravity : but as many axes maybe drawn 
 through this point of the floating body in a diredllon , 
 parallel to the horizon, and the motion of the folid rc- 
 fpedls one axis only, this axis mnft be determined by 
 the figure of the body and the particular nature of the - 
 cafe. When this axis of motion, as it is called, is de- 
 
 terminedj
 
 FLO 
 
 [ 6j 
 
 Tliitttiiig- tcriniiied, and tlie fpeciTic gravity of tilt foliil is known, 
 
 •"^ •' the pofitionB of pcimanent floating will be obtained, 
 
 full by findijig tlie feveial pofitions of equilibrium 
 tliiiiugh which the folid may be conceived to pafs, 
 while it revolves round the axis of motion ; and fecond- 
 ly, by determining in which of tliofe pofitions the c 
 quilibriuni is permanent, and in which of them it is 
 momentary and unliable " 
 
 Such as we have now briefly lilted are the general 
 principles on which are toundcd Mr Atwood's invef- 
 tigations for determining the pi.fitions aiTumed b) ho- 
 mogeneous bodies, flouting on a fluid lurtacc ; and al- 
 fo lor determining the liability of fliips and of otlia" 
 floating bodies. We cannot farther accompany him 
 in his ehicithition of them, in the problems to the folu- 
 tion of which they lead, and in the important practi- 
 cal purpofes of naval archileAure to which tliey are re- 
 ferred. The whole paper, comprehending no Icfs than 
 85 pages, is curious and valuable ; it abounds with a- 
 nalytical and geometrical dilquilltions of the mod ela- 
 borate kind ; and it ferves to enlarge our acquaintance 
 with a fubjeA that is not only highly interclling to the 
 fpeculative mathematician, but extremely ufetul in its 
 praftical application. 
 
 With this latter view,~the author feems to have di- 
 refted his attention to the vaiious objefts of inquiry 
 which this article comprehends. They are Inch as in- 
 timately relate to the tlieo;-y of naval architecture, fo 
 far as it depends on the pure laws of mechanics, and 
 they contribute to extend and improve this theory. 
 The union of thofe pnnciples that are deduced from 
 the laws of motion, with the knowledge which is de- 
 rived from obfervation and experience, cannot fail to 
 etlablifli the art of confl;rudling veffels on its true bafis, 
 and gradually to lead to farther improvements of the 
 greatcll importance and utility. To this purpofe, the 
 author obferves, that 
 
 " If the proportions and dimenfions adopted in the 
 conftruClion of individual veflels are obtained by exadl 
 geometrical menfurations, and calculations founded on 
 them, and obfervations are made on the performance of 
 thefe veflels at fea ; experiments of this kind, fufficient- 
 ly diverlified and extended, teem to be the proper 
 grounds on which theory may be eflfedlually applied in 
 developing and reducing to fyfl:em thofe intricate, fub- 
 til, and hitherto unperceived caufes, which contribute 
 to impart the greateft degree of excellence to veflels of 
 every fpecies and defcription. Since naval architefture 
 is reckoned amongil the pra£tical branches of fcienee, 
 every voyage may be confidered as an experiment, or 
 rather as a feries of experiments, from which ufeful 
 truths are to be inferred towards perfefting the art of 
 conllrufting veflels : but inferences of this kind, con- 
 fiftently with the preceding remark, cannot well be ob- 
 tained, except by acquiring a perfect knowledge of all 
 the proportions and dimenfions of each part of the 
 fliip ; and fecondly, by making and recording fufficient- 
 ly numerous obfervations on the qualities of the veflcl, 
 in all the varieties of fituation to which a fliip is ufual- 
 ly liable in the practice of navigation." 
 
 In the valuable mifcellany entitled the Philofophical 
 Magazine, there is a paper on this fubjeft by Mr John 
 George Englifli, teacher of mathematics and mechani- 
 cal philofophy ; which, as it is not long, and is eafily 
 underftood, we fliall take the liberty to tranfcribe. 
 
 9 ] FLO 
 
 •' Howfvpr cperoft and difficult the calculations ne- Ploi'inp. 
 ceifary to determine the liability of nautical velfels may, '""">"—' 
 in fume cafes, be, yet they all depend, fiys this author, 
 upon the four following funjile and obvious theorems, 
 accompanied with other well-known ftereometrical and 
 llatical principles. 
 
 " Theorem i. Every floating body difplaces a quan- 
 tity of the fluid in which it floats, cq' il to its own 
 weight: and confequently, the fpecUic gravity of 
 the fluid will be to thht of the floating body, as tlie 
 magnitude of the whole is to that of the part immer- 
 fed. * 
 
 " Theorem 2. Every floating body is imp-lied down- 
 ward by its own (.ilentlal power, aiiling in tlie dire£b\)n 
 of a vertical line pafliiig through the centre of gravity 
 of the whole ; and is impelled upward by the re aclion 
 of the fluid which fupports It, afting in the diredion 
 of a vertical line paffing through the centre of gravity 
 of the part Immerfed : therefore, unlefs thsife two linej 
 are coincident, the floating body thus impcHcd -mull 
 revolve round an axis, either in motion or at reft, until 
 the equilibrium is rellored. 
 
 " Theorem 3. If by any power whatever a veflcl be 
 deflefted from an upright politlon, the perpendicular 
 difliance between two vertical lines paffing tluough the 
 centres of gravity of the whole, and of the part immer- 
 fed refpeftively, will be as the ftabillty of the veflll, 
 and which will be politive, nothing, or negative, accor- 
 ding as the metacentre is above, coincident with, or 
 below, the centre of gravity of the vcflfel. 
 
 " Theorem 4. The common centre of gravity of any 
 fyfl:em of bodies being given in pofition, if any one of 
 thefe bodies be moved from one part of the fyllem to 
 another, the correfponding motion of the common 
 centre of gravity, elllmated in any given diredion, will 
 be to that of the aforefaid body, eflirr.ated in t hi- fame 
 diredion, as the weight of the body moved is to that 
 of the whole fyftem. 
 
 " Erom whence it is evident, that in order to afcer- 
 tain the liability of any veflcl, the pofition of the 
 centres of gravity of the whole, and of the part im- 
 merfed, mull be determined ; with which, and the di- 
 menfions of the veflisl, the line of floatation, and angle 
 of defltdion, the ft;ability or power either to right it- 
 feif or overturn, may be found. 
 
 " In fhips of war and mcrchandife, the calcul itions 
 neceflary for this purpofe become u.navoidably very o- 
 perofe and troublefome ; but they may be much facili- 
 tated by the experimental method pointed out in the 
 New Tranfadlons of the SvvedKh Academy of Scieii- 
 ces, firlt quarter of the year 17S7, page 48. 
 
 " In river and canal boats, the regularity and fim- 
 plicity of the form of the veflcl itfelf, together with the 
 compad difpofition and humogeneal quality of the 
 burden, render that method for them unneccfTary, and 
 make the requifite calculations become very eafy. Vef- 
 fels of this kind are generally of the fame tranfverf; 
 fedion throughout their whole length, except a fmall 
 part in prow and ftern, formed by fegmcnts of circles 
 or other fimple curves ; therefore a length may tafily 
 be afligned fuch, that any of the traniverfe fcdions be- 
 ing multiplied thereby, the produ6\ will be equal to 
 the whole folidity of the veflel. The form of the 
 fedion ABCD is for the moll part either redan- 
 gular, as in fig. I. trapezoidal as in fi^. 2. or mix- 
 
 Plate 
 
 4O 2 
 
 tilineal ^XVIIL
 
 FLO [ 660 ] FLO 
 
 Fl.-ating. tilinsal as in fi^. 3. in all which MM reprefents the line quadrants of two feet, or 24 inches radius each. Then 
 
 '•"-^ of floatation when upright, and £1< that when inclined the area of the two quadrants = 904-7808 fquare 
 
 at any angle MXE ; alfo G reprefents the centre of gra- inches, and the dittance of their centres of gravity from 
 
 vity of the whole v'eflcl, and R that of the part im- tlie bottom = 13-8177 inches very nearly; alfo the 
 
 merfed. , 
 
 " If the vcfTel be loaded quite up to the line AB, 
 and the tpecific gravity of the boat and burden be the 
 iame, then th^ point G is fimply the centre of gravity 
 of the fec\ion ABCD ; but if not, the centres of gra- 
 vity of the boat and burden muft be found ieparatcly, 
 and reduced to one by the common method, namely, by 
 dividing the fnm of the momenta by the fuin of weights, 
 or areas, which in this cafe are as the weights. The 
 point R is always the centre of gravity of the fedHon 
 MMCD, which, if confining of different figures, muft 
 alfo be found by dividing the fum of the momentary 
 the fum of the weights as common. Thefe two points 
 being found, the next thing ncceffary is to determine 
 the area of the two equal triangles MXE, MXF, their 
 centres of gravity 0, 0, and the perpendicular projeded 
 d-iftance 11 n of thefe points on the water line EF. This 
 being done, through R, and parallel to EF, draw RT 
 = a fourth proportional to the whole area MMCD, 
 either triangle MXE or MXF, and the diftance tin ; 
 through T, and at right angles to RT or EF, draw 
 TS meeting the vertical axis of the veflel in S the me- 
 tacentre ; alfo through the points G, B, and parallel to 
 ST, draw NGW and BV ; moreover through S, and 
 parallel to EF, draw WSV, meeting the two former in 
 V and W : then SW is as the ftability of the veflel, 
 which will be pofitive, nothing, or negative, according 
 as the point S is above, coincident with, or below, the 
 point G. If now we fuppofe W to reprefent the weight 
 cf the whole veffel and burden (which will be equal to 
 the feftion MMCD multiplied by the length of the 
 veflel 1, and P to reprefent the required weight applied 
 at the gunwale B to fuftain the veflel at the given 
 angle of inclination ; we flrall always have this propor- 
 tion : as VS : SW : : W : P ; which proportion is ge- 
 neral, whether SW be pofitive or negative; it muft 
 only, in the latter cafe, be fuppofed to aQ upward to 
 prevent an overturn. 
 
 " In the reftangular veflel, of given weight and di- 
 menfions, the whole proccfs is fo evident, that any far- 
 ther explanation would be unneceflary. In the trape- 
 zoidal vefl'el, after having found the points G and R, 
 let AD, BC be produced until they meet in K. Then, 
 fince the two feflions MMCD, EFDC are equal, the 
 two triangles MMK, EFK are alfo equal ; and there- 
 fore the reaangle EK X KF = KM X KM = KM^; 
 and fince the angle of inclination is fupjiofed to be 
 inown, the angles at E and F are given. Confequent- 
 ly, if a mean proportio 
 
 area of the included reftangle able = 1440 fquare 
 inches, and the altitude of its centre of gravity 12 
 inches ; in like manner, the area of the redangle AB 
 c d will be found = 5184 fquare inches, and the alti- 
 tude of its centre of gravity 48 inches : therefore we 
 fliall have 
 
 Momentum of 
 the two q'ja>^. 
 Moment, if the 7 
 reil.in. j hie 5 
 Moment, (if the? 
 redlan. ABti/ 5 
 
 i = 
 
 904-7808 X 13-8177 = HSOI-sSyOdoICi 
 1440- X '* = I7i8o' 
 
 5184- X 48 =248831- . 
 
 752S-7So8 27S&i3'y8iii.6oi6 
 
 " Now the fum of the momenta, divided by the fum 
 27861^-0^966016 
 of the areas, will give -^y.^s^g = 37'oo6 
 
 inches, the altitude of G, the centre of gravity of the 
 feftion ABCD above the bottom. In like manner, 
 the altitude of R, the centre of gravity of the feftion 
 
 123093-98966016 
 MMCD, will be foiind to be equal 36-780 8 
 
 = 24-934 inches ; and confequently their difl'erence, or 
 the value of GR = 12-072 inches, will be found. 
 
 Suppofe the veflel to heel 15^ and we Ihall have the 
 following proportion ; namely, As radius : tangent of 
 15 : : MX = 54 inches : 14-469 inches = ME or 
 MF ; and confequently the area of either triangle MXE 
 or MXF = 390-663 fquare inches. Therefore, by 
 theorem 4th, as 4936-7808 : 390-663 : : 72 = n n =: 
 4 AB : 5-6975 inches = RT ; and, again, as radius : 
 fme of 15° : : 12.072 = GR : 31245 inches = RN ; 
 confequently RT — RN = 5-6975 — 3-1245 =. 2"573 
 inches = SW, the ftability required. 
 
 " Moreover, as the fine of 15° : radius : : 5*6975 =: 
 RT : 22 013 = RS, to which, if we add 24-934, the 
 altitude of the point R, we ftiall have 46-947 for the 
 height of the metacentre, which taken from 72, the 
 whole altitude, there remains 25-053 ; from which, and 
 the half width = 54 inches, the diftance BS is found 
 =: ^9-529 inches very nearly, and the angle SBV := 
 8o°'- — 06' — 42"; from whence SV = 58-645 inches. 
 
 Again : Let us fuppofe the mean length of the vef- 
 fel to be 40 feet, or 480 inches, and we fliall have the 
 weight of the whole veflel equal to the area of the fec- 
 tion MMCD = 4936.7808 multiplied by 480 = 
 2369654-784 cubic inches of water, which weighs ex- 
 adly 85708 pounds avoiidupois, allowing the cubic 
 nal be found between the fines of foot to weigh 62.5 pounds 
 
 the angles zl E and F, wc fliall have the following pro 
 portions : 
 
 " As the mean proportional thus found : fine Z. £ : : 
 KM : KF, and as the faid mean proportional : fine 
 L.Y : : KM : KE; therefore ME, MF become known : 
 from whence the area of either triangle MXE or MXF, 
 the diftance n n, and all the other requifites, may be 
 found. 
 
 " In the mixtilineal feflion, let AB = 9 feet = ro8 
 inches, the whole depth = 6 feet = 72 inches, and 
 the altitude of MM the line of floatation 4 feet or 48 
 JBches ; alfo let the two curvelincar parts be circulai- 
 
 " And, finally, as SV ; SW (i.e.) as 58-645 : 2-573 
 : : 81:708 : 3760 +, the weight on the gunwale which 
 will fuftain the veffel at the given i.iclination. There- 
 fore a vefl'el of the above dimenfions, and weighing 38 
 tons, 5 cwts. 28 lbs. will require a weight of 1 ton, 
 13 cwts. 64 lbs. to make .her incline 15*. 
 
 " In this example, the defledling power has been fup- 
 pofed to ad perpendicularly on the gunwale at B ; but 
 if the vefl'el is navigated by fails, the centre velique 
 muft be found ; with which, and the angle of deflec- 
 tion, the projected diftance thereof on the line S'V may- 
 be obfdiiicd ; and then the power, calculated as above 
 
 peceflary
 
 I'lATE XX-VHL . 
 
 I-io-.l. 
 
 ItneHOHHiA 
 
 ^S- 
 
 Fi^. 
 
 .3
 
 FOR 
 
 [ 66i ] 
 
 FOR 
 
 necffTary to be applied at the projeilted point, will be 
 thnt part of tlie wind's force which caufes the vtlTel to 
 ■.heel. And converfely, if the weight and dimeiifions 
 of the vcflcl, the area and altitude of the fails, the di- 
 reftion and velocity of the wind be given, the angle of 
 dcfleflion may be found." 
 
 FLUENT, or Flowing Quantity, in the doc- 
 trine of fluxions, is the variable (juantity which is con- 
 sidered as increafing and decreafing ; or the fluent of 
 a given fluxion, is that quantity whofe fluxion being 
 taken, according to the rules of that doftrine, fhall be 
 the fame with the given fluxion. See Fluxions, £n- 
 eye/. 
 
 FLUIDS (Motion in). See Hydrostatics and 
 Resistance of Fluids, Encycl. and Motion in this 
 Supplement. 
 
 FOGEDAR, the military governor of a fubordinate 
 diilrift in India, who has fometimes the additionil of- 
 fice of coUefting the revenues. 
 
 FOLIATE, a name given by fonie to a curve of 
 the 2d order, cxprefTed by the equation x^-^y':=axy, 
 being one fpecies of defeftive hyperbolas, with one a- 
 fymptote, and confiding of two infinite legs crofling 
 each other, forming a fort of leaf. It is the 42d fpe- 
 cies of Newton's Lines of the 3d Order. 
 
 FORCER, in mechanics, is properly a pifton with- 
 out a valve. For, by drawing up fuch a pifton, the 
 air is drawn up, and the water follows ; then pufliing 
 the pifton down again, the water, being prevented from 
 defcending by the lower valve, is forced up to any 
 height above, by means of a fide branch between the 
 two. 
 
 FORDYCE (James, D. D.), fo well known to feri- 
 ous readers by his fermons to young women, and other 
 fpecimens of pulpit eloquence, was born at Aberdeen 
 in the year i^ao. His father was a man much e- 
 fteemed, and held, more than once, the ofRce of chief 
 inagiftrate in his native city ; and his mother was a wo- 
 man of good fenfe, amiable temper, and exemplary pie- 
 ty. This refpedtable pair had the lingular felicity of 
 tranfmittiug fuperior talents to almoft every individual 
 of a numerous family ; of one of which, viz. David For- 
 dyce, the reader will find fome account in the Encydo- 
 padia. 
 
 The fiibjeft of this memoir, who was their fourth 
 fon, acquired, as well as his brother, the rudiments of 
 claflical learning at the gramnier fchool of Aberdeen, 
 whence he was removed to the Mariichal college and u- 
 niveriity in the fame city. Having completed a regu- 
 lar courfe of ftudy both in philofophy and theology, 
 he was licenfed, when very young, according to the 
 forms of the church of Scotland, to be a preacher of 
 the gofpel ; and was foon afterwards preferred to the 
 place of" fecond minifler in the collegiate church of 
 Brechin in the county of Angus. After remaining 
 there for fome years, he received a prefentation to the 
 church of Alloa near vStirling ; and though the inhabi- 
 tants of that parifh were prepolTefTed in favour of ano- 
 ther minifter whom they knew, and prejudiced againft 
 Mr Fordyce whom they did not know ; fo narrow 
 mind.'d and totally dei^itute of tafte was his colleague 
 in Brechin, that he judged it expedient to hazard the 
 confequences of a removal. He was aware that he 
 entered on his new charge under a confiderable degree 
 cf popular odium ; but he thought it more probable 
 
 that he fhould be able to overcome that odium, than Vcrirjte, 
 conciliate the affeftions of a four fanatic. In this ex.^""'"""^ 
 peftatioii he was not deceived. The prejudices of the 
 good people in Alloa were very quickly removed, not 
 more by the able and impreflive maiimr in which he 
 conduced the public lervices of the Lord's day, than 
 by the amiable and condefcending fpirit with which he 
 performed the more private duties of viliting and ca- 
 techifing in the different diftrifts of his parilh ; duties 
 which, as they were wont to be performed by the 
 Scotch clergy, contributed much more than preaching 
 to the religious inftruftion of the lower claffes of the 
 people. 
 
 It was during his rcfidence at Alloa that Mr Fordyce 
 firft dillinguifhed himfelf as an author by the fuccefTive 
 publication of the three following fermons. The firft, 
 upon the eloquence of the pulpit, was annexed to " the 
 Art of Preaching" by his brother David ; the fecond, 
 upon the methods of promoting edification by public 
 inftitntions, was preached at the ordination of the Rev. 
 Mr Gibfon minifter of St Ninian's, a neighbouring 
 parifti, in the year 1754, and pubUftied, with the 
 charge and notes, in 1 755 ; and the third, upon the de- 
 lulive and perfecuting (pirit of popery, was preached 
 the fame year before the fynod of Stirling and Perth ; 
 and being publillud, came very quickly to a fecond e- 
 dition. But the fermon which moft ftrongly arreftcd 
 the attention, both of the audience before which it was 
 delivered, and of the public to which, in 1760, it was 
 given from the prefs, was that on the fo!/y, infamy, and 
 mifery of unlawful pleufure, preached before the Gene- 
 ral AlTembly of the Church of Scotland. The choice of 
 fuch a fubjeft, on fuch an occalion, excited the fnrprife 
 of all his hearers, and tempted the younger part of 
 them to fmile at the very reading of the text ; but this 
 unfeaionable mirth was foon converted into ferioufnefs. 
 The pifture exhibited in this fermon is the work of a 
 mailer j and we have been affured by a friend who 
 heard it preached, that the fpirit and elegance of the 
 compolition was fo feconded by the folemin'ty and ani- 
 mation with which it was delivered, that it made a verv 
 llriklng imprefllon, not only upon the more refpcdxable 
 part of the audience, but upon minds of noted levi- 
 ty : It raifed indeed its writer's fame as a pulpit ora- 
 tor to an unrivalled eminence among his brethren in 
 Scotland. 
 
 About this time, and we believe in confequence of 
 this fermon, Mr Fordyce received from the univerfity 
 of Glafgow a diploma, creating him Doftor in Divi- 
 nity ; and if there is yet any thing honourable in aca- 
 demical degrees, proftituted as they have long been bv 
 an undillinguifliing diftribulion, the honour could not 
 have been conferred with greater j^ropriety on any man 
 in the church to which he then belonged. 
 
 In that church he did not long remain. Soon after 
 the publication of this fmgular fermon, and his confe- 
 quent acquifition of academical honours, he accepted of 
 an invitation from a focicty of Protellant diftenters, 
 who had their place of meeting in MonkwcU-llreet, 
 London, to become colleague and fuccelfor to their 
 pallor, who was then old and infirm, and who died, in- 
 deed, in the fpace of a few months. This gave occa- 
 fiou to the Doftor to difplay iiis oratory once more- 
 both from the pulpit and the prefs in a fermon ou the 
 death of Dr Lawrence. He was now fo!e paftjor to 
 
 til*-
 
 FOR I eCu 1 FOR 
 
 VorA yre. tlic congregation of Monkwcll-ftre*'! | andpreschcd for tioned witli approbation three or foiii- of Mn ofenfionnl F»rdye% 
 
 ' many years with great jiowers of eloquence and fervour fermons ; but perhaps the fined fpeciiren of pulpit ora- *•'"■•""'»> 
 
 of piety, to an audience always crowded and often over- tory whieh ever fell from his pen, is the chan>e which """v"*" 
 
 flowing. he delivered at the ordination of his fucceifor in the 
 
 When a preacher obtains, with or without merit, mectirg of Monkwell-ftreet. It is indeed one of the 
 
 an uncommon fliare of popularity, a confidcrahle pro- mod vahiable difcuurfes of the kind that we have feeii, 
 
 portion of his liearers will ever confilt of tliofe, wlio and (hould be read with attention by every elero-yman 
 
 are guided in their choice rather by curiofily and fa- of cvtry denomination, who wiihes to difcharge his 
 
 (hioii, than by found judgment. The attachii.enls of duty with credit to himfelf and with advantage to his 
 
 fuch people are as capricious and variable as their people. 
 
 ininds ; and they change their preacher-as they change The effeft of Dr Fordyce's addreffes from the pul- 
 
 their drefs, not from their own tafte, for in general pit was much heightened, not only by an adtion and 
 
 they have none;, but from the defire of being where an elocution, which he ftudicd with care and praftifed 
 
 others are, of doing what others do and of admiring with fuccefs ; but by the figure of his perfon, which was 
 
 what others admire. Dr Fordyce appreciated julUy peculiarly dignified, and by the exprefllon of his coun- 
 
 the value of fvich mens approbation, and knew it even- tenance, which was animated at all times, but animated 
 
 tually by experience ; but he was more than coinpeu- moll of all when lighted up by the ardour of his ioul in 
 
 fated for the lois of hearers of this defcription by the thcfervice of God. By fome of his hearers, it was ob- 
 
 fteady adherence of otiiers, whofe efteem was moft de- fcrved that, on many occafions, he fecmed not merely 
 
 firable, becaufe it was grounded upon the diftates of a to fpeak. but to look convitfion to the heart. His eye, 
 
 found underllanding. indeed, was particularly bright and penetrating, and he 
 
 At laft, about Chriftmas 1782, when his health, had carefully attended to the effedt vihich an orator 
 
 which had long been declining, rendered it neccffary, in may often produce upon an audience by the judicious 
 
 his own opinion, and in the opinion of his phyfieians, to ufe of that little, but invaluable organ. 
 
 » difcontlnue his public fervices, he religned his charge With refpeCt to his theological fentiments, we are 
 
 in Monkwell-llreet, and retired to a villa in Hamplhire, affured (a) they were in no extreme, but liberal, ratio- 
 
 in the neighbourhood of the Earl of Bute, who ho- nal, and manly. He feems to have been untainted by 
 
 iioured him with ills friendfliip, and to whofe valuable that rage of innovation, which of late has fo completely 
 
 library he had free accefs. Afterwards he removed to disfigured the creed, as well religious as political, of 
 
 Bath, where having, with ChrKlian patience, fuffered the great body of Englilh diffenters. The confequence 
 
 much from an allhmatic complaint, to which he had was, that he lived on terms of friendfliip with men of 
 
 been fubjeft for fome yeav., on the ill of October very oppofite fentiments; with Price a republican and 
 
 1791^ he expired without a groan. Arian, and with Johnfon, who, though he hated- a 
 
 Were we to hazard an opinion of Dr Fordyce's in- Avhig and a Prefbyterian, refpedted talents and worth 
 
 tellcftual powers from fuch a perufat of his works as wherever he found them. 
 
 we muft acknowledge to have been hafty, we w'ould fay We (hall conclude this fliort flctcli of Dr Fordyce's 
 
 that he was a man of genius rather than of judgment ; life and charafter with the following hil of his workst 
 
 that his imagination was the predominant faculty cf of which fome have been tranflattd into feveral lan- 
 
 his mind ; and that he was better fitted, bv an addrefs guages. i. A Sermon and Charge, at the ordination 
 
 to the paffions, to enforce the practice of virtue, than, of the Rev. Mr Glbfon Miniller of St Ninian's, 1754. 
 
 by the exertions of his own underllanding, to vindicate 2. Another Ordination Sermon on the Eloquence of 
 
 fpeculative truth, or to deteft the fophlllry of error, the Pulpit, annexed to his brother's " Art of Preaeli- 
 
 From this remark, we cannot be fufpefted of a wilh to ing," 1754. 3. A Sermon on the Spirit of Popery, 
 
 leffen his charafter in the public elleeni ; for his talents, 1754. 4. A Sermon on the Folly, Infamy, and Mi- 
 
 as they appear to us, are furely of more value to a fery of Unlawful Pleafure, 176;. 5. A Sermon, on 
 
 preacher than thofe which are perhaps better adapted the Death of Dr Lawrence, 1760. 6. Sermons to 
 
 to literary or fcientific purfuits. In none of his works Young Women, 2 vols. 176;. 7. A Sermon on the 
 
 indeed do we perceive any evidence either of profound Charafter and Conduft of the Female Sex, 1776. 8. 
 
 fcience, or of various erudition ; though we doubt not Addreffes to Young Men, 2 vols. 1777. 9. A Charge 
 
 but thofe works are every thing which their author in- at the Ordination of the Rev. James Liiidfay, in 
 
 tended them to be. Of his fermons to young women, Monkwell-ilreet, 1783. 10. AddrelTes to the Deity, 
 
 which have attraftcd moll general notice, it would be 178;. 11. Poems, 1786. 12. A Dlfcourfe on Pain, 
 
 prefumptuous in us to give a charafter; for though we 1791. He alfo re-publllhed, with an additional charac- 
 
 fat down many years ago to read ihent^ we could not ter, " The Temple of Virtue, a Dream," written by 
 
 get througlrj and wc have never made a fecond at- his brother David. 
 
 tempt. As far as we can depend upon what we recol- FORMULA, a theorem or general rule or expref- 
 
 left of thefe far-tamed difcourfes, the cenfure palled on fion, for reiolving certain particular cafes of lome pro- 
 
 them by Mrs Wolftoncraft feems to be jull. Their au- blem, &c. So ^s + ■}</ is a general formula for the 
 
 thor, however, was certainly qualified to excel, and ac- greater of two quantities whole fum is s and difierence 
 
 tually did excel as a preacher. We have already men- J ; and is — id is the formula, or general value, for 
 
 the 
 
 (a) By his fucceffor in Monkwell-ilreet, to whofe fermon, preached on occafion of the Doftor's death, our 
 readers are indebted for every tiling valuable in this ihort memoir.
 
 F O R 
 
 [ ^^^3 1 
 
 FOR 
 
 the lefs quantity. Alfo '^ dx — x' ia the formuln, or 
 ' gc iicral value of the ordinate to a circle, wlu)f<; diame- 
 ter is d, and abfcils x. 
 
 FORSTZR (John Reinhoki, LL. D.) profefTor of 
 natural hiilovy in the miiverfity of Hailo, member of 
 the academy' of fciences at Berlin, and of other learned 
 focieties, was born at Dirfchaii, in VVtft Prufiia, in the 
 month of Odober 1729, and was formerly a Prottf- 
 tant clergyman at Dantzick. He had a nun:crous fa- 
 mily, and the emointnents of his oifice were iler.dcr. 
 He therefore quitted Dantzick, and went, firft to Ruf- 
 fia, and thence to England, in quell of a better fettle- 
 ment than his own country afforded. In the diflent- 
 ing academy at Warrington he was appointed tutor 
 in the modern lantjuages, with the occasional ofEce of 
 JecTturing in various brandies of natural hiitory. For 
 the firlt department hs was by no means well qualified; 
 his extraordinary knowledge of languages, ancient and 
 modern, being unaccompanied by a p-artlcle of fade ; 
 and his ufe of them being all barbarous, though fluent. 
 As a natural hiftorian, a critic, geographer, and anti- 
 quary, he ranked much higher ; but unfortunately 
 thefe were acquiiitlons of little value in his academical 
 department. 
 
 At length he obtained the appointment of natnrahft 
 2inA pljilofopher (if the woid may be fo uled) to the fe- 
 cond voyage of difcovery undertaken by Capt. Cook ; 
 and from 1772 to 1775 he accompanied that immortal 
 navigator round the world. On his return he refided 
 in London till the improper conduft of himfelf and 
 his fon made it expedient for them both to leave -the 
 kingdom. Fortunately he received an invitation to 
 Halle, where, for 18 years, he was a member of the 
 philofophical and medical faculties. Among his works 
 are : An Introduction to Mineralogy, or. An accu- 
 rate Claffificalion of Foflils and Minerals, Sic. London, 
 1768, 8vo. A Catalogue of the Animals of North 
 America, with ftiort Dire£lions for coUefting, prtler- 
 ving, and tranfporting all kinds of Natural Curiolities, 
 London, 1 771, 8vo. Obfervations made during a 
 Voyage round the World, on Phyfical Geograpliy, 
 &c. London, 1778. He was the author of a great 
 many produi^^ions in Englidi, Latin, or German, and 
 of feveral papers in the Philofophical 1'ranfactions. 
 He tranflated into Englifh, Bougainville's Voyage 
 round the World, and Kalm's, BofTu's, and Reidlel's 
 Travels. He was employed likewife, when in Er.g- 
 land, in the Critical Review ; and he wrote various 
 detached papers on different fubjetis, which have been 
 uiferted in foreign journals and the tranfatlions of 
 iea'-ned academies. 
 
 He died at Halle on the i6th of December 1798, 
 in the 70th year of his age. 
 
 FORSTER (George), the fon of the jjreceding, was 
 born at Dantzick, and accompanied his lather to Eng- 
 land when he was about twelve years of age. He was en- 
 tcicd a ftudent in the academy at Warrington, and loon 
 acquired a very perfeft ufe of the Engliih tongue. He 
 alfo diftinguifhed himfelf greatly by his attainments in 
 Icience and literature in general ; adding to an excellent 
 memory, quick parts and a fertile imagination. His 
 temper was mild and amiable; in which he much differed 
 from his father, one of the moft quarrelfome and irri- 
 table of men ; by which difpofition, joined to a total 
 want of prudence in common concerns, he lull alinoll all 
 
 the friends his talents had acquired him, and involved , ^°^^"- , 
 himfelf and family in perpetual difficulties. .' 
 
 The caie was very different with the fubjeft of this 
 memoir ; for when Dr Foriler was appointed naturalill 
 to Captain Cook, his foil, through the intereit of the 
 friends whom his good nature had made, was affociated 
 with him In his office. The voyage continued during 
 the fpace of three years ; and on their return the two 
 Foriters publiflied jointly a botanical work in Latin, 
 containing the chara<fters of a number of new genera of 
 plants, dilcovercd by them in their circumnavigation. 
 Thus far they atfed propeiiy in the Icrvice of govern- 
 ment .tor the advancement of fcience ; but in publifh- 
 ing another work their conduct v.'as not proper. 
 
 The f:i:her had tome under ai.' engagement not to 
 publill).feparately, from the authorifed narrative, any 
 account of the voyage ; and this engagement he and 
 his fon were determined to violate. An account of 
 the voyage, laerefore, Wcis pnblilhed in Englifh and 
 Genuaii by George; and the language, which is cor- 
 reft and elegant, was undoubtedly his ; but thofe who 
 knew both him and his father, are fatisfied that the 
 matter proceeded from the joint (lock of their obfer- 
 vations and refleftions. Several parts of th£ work, and 
 particularly the elaborate inveftigations relative to the 
 languages fpoken by the natives of the South Sea 
 Iflands, and the fpcculations concerning their fuccef- 
 five migrations, are thought to be ihongly iinprefled 
 with the geiuus of the elder Forfter. 
 
 That i work thus furrcptitioully ufhered into the 
 world was not patronifed by thofe with whom the au- 
 thors had fo ungratefully broken faith, could excite no 
 wonder, even though the pubhcation itftlf had been o- 
 therwiie unexceptionable ; but this was far from being 
 the cafe. It abounds with reflections injurious to the 
 government whofe fervants they had been, and not jull 
 to the navigators eiuployed on voyages of difcovtry. 
 The younger Forfter, too, h^d fomc time before puhlilh- 
 ed a book replete with factious feutinients ; and the 
 coldnefs with which he and his father were both treated 
 in confequence of luch condurt, determined them to 
 leave London. 
 
 We have already related all that we know of the fa- 
 ther, who was recommended to our notice only hy 
 his connection with the illuilrious Cook ; and of the 
 fon, there is a fhort account in the Monthly Maga- 
 zine, by Charles Pougens, fraught with thofe impi- 
 ous and feditious refleCfions which fo frequently dif- 
 grace a mifcellany, which would otherwife be highly 
 valuable. According to this author, George Forfter 
 was delirous to fettle in France. Avaricious of glory, 
 and an idolater of liberty, Paris was the city moft fuit- 
 able to his talle and character of any in Europe. Not- 
 withilanding this, he was foon conftraiiied to leave it : 
 the intereft of his family demanded this facriiice ; for a 
 learned man, who fails round the world, may enrich 
 his memory, but he will not better his fortune. He 
 was accordingly obliged to accept the place of profcf. 
 for of natural hiftory in the univerfity of Caffcl. But 
 his factious fpirit accompanied him whithcrfoever he 
 went. It is well known, tl^at the petty princes of 
 Germany have long been in the pradlice of hiring out 
 their troops to more opulent fovereigns engaged in 
 war. This praftice, which wc are not difpofed to de- 
 fend, not only fcaiidalized our Cofhiopolite, but fo ir- 
 ritated
 
 FOR 
 
 [ 664 ] 
 
 F O S 
 
 ForlVer. rrtated his temper and offended his pride, becairfe, for- 
 
 " — V- ' footh, the Prince of Hefle-Caffel would not by him be 
 
 perfiiaded to veh'iiquiih it, tliat he did every thing in 
 his power, we are told, to withdraw hiinlclf from a fi- 
 tuatioii fo unfuitahle to a thinking being. Every thing 
 in his power ! Did the Prince retain him in the uni- 
 verfity contrary to his inchnalion ? Tlie univerfity of 
 CafTel mull be contemptible indeed, if the prelcftions 
 of fuch a man as George Forfter were of fuch confe- 
 quence to it. 
 
 He got away, however ; and the fcnate of Poland 
 having offered him a chair in the univerfity of Wilna, 
 Forfter accepted of the invitation. But although this 
 office was verv lucrative, and the enlightened patriots 
 •of that country did not negleft to procure him all the 
 literary fuccours of which he ftood in need, he could 
 not be long happy in a femi-barbarous nation, in which 
 liberty was fuffered to expire under the intrigues of Ruf- 
 ■fia and Pruffia. 
 
 On this, with wonderful confiftency, the man who 
 could not endure the defpotifm of HefTe, or even the 
 ariftocracy of England, accepted of the propofitions of 
 that friend to liberty Catharine IT. ; who, jealous of 
 f^very fpecies of glory, wifhed to fignalize her reign, by 
 procuring to the Ruffian nation the honour of underta- 
 king, after the example of England and France, a new 
 -voyage of difcovery round the world. Unfortunately 
 for the progrefs of knowledge, the war with the Otto- 
 man Porte occafioned the mifcarriage of this ufeful pro- 
 jeft. 
 
 But Forfter could not long remain In obfcurity. The 
 different pubhcations with which he occafionally enrich- 
 ed natural hiftory and literature, encreafed his reputa- 
 tion. The Eleftor of Mentz accordingly appointed 
 him prefident of the univerfity of the fame name ; and 
 he was difcharging the fuuftions of his new office when 
 the French troops took poffeflion of the capital. This 
 philofophical traveller, who had ftudied fociety under 
 all the various afpefts arifing from different degrees of 
 civilization ; who had viewed man fimple and happy at 
 Otaheite ; — an eater of human flefli in New Zealand, 
 corrupted by commerce in England, depraved in France 
 tiy luxury and atheifm, in Brabant by fuperftition, and 
 • 1 Poland by anarchy ; — beheld with wild cnthufiafm 
 the dawnings of the French revolution, and was the 
 firft, fays M. Pougens, to promulgate republicanifm in 
 Germany. 
 
 The Mayencois, who had formed themfelves into a 
 rational convention, fent him to Paris, in order to fo- 
 licit their reunion with the French republic. But, in 
 the courfe of his miffion, the city of Mentz was be- 
 fieged and retaken by the Pruffian troops. This event 
 occafioned the lofs of all his property ; and what was 
 ftill more difaftrous, that of his numerous manufcripts, 
 which fell into the hands of the Prince of Pruffia. 
 
 Our biographer, after condufting bis hero through 
 thefe fcenes of public life, proceeds to give us a view 
 of his domeftic habits and private principles. He tells 
 us, that he formed a connection (whether a marriage or 
 not, the ftudied ambiguity of his language leaves rather 
 uncertain) with a young woman named There/a Hayne, 
 who, by the illumination of French philofophy, had di- 
 vefted herfelf of all the prejudices which, we truff, the 
 ladies of this country ftQl confider as their honour, as 
 
 they are certainly the guardians of domeftic peace. 
 
 Mifs Hayne was indignant at the very name of duly. 
 With Eloifa (he had taken it into her liead that i. 
 
 Love, free as air, at fight of human ties. 
 Spreads his light wings, and in a moment dies. 
 
 She was frank enough, however, fays our author, to 
 acknowledge the errors of her imagination ; and from 
 this expreffion, and his caUing her afterwards Forfter's 
 wife, we are led to fuppofe that flie was adually mar- 
 ried to him. But their union, of wiiatever kind, was 
 of fliort duration. Though the lady is faid to have 
 been paffionately attached to celebrated names, the name 
 of George Forfter was not fufiicient to tatisfy her. He 
 foon ccafed, we are informed, to pleafe her ; (he there- 
 fore transferred her affedtions to another ; and, as was 
 very natural for a woman who'was indignant at the 
 name of duty, fhe proved falie to lier luifbaud's bed. 
 Forfter, however, pretended to be fuch a friend to the 
 modern rights of men and women, that he defended the 
 charafter of his Thercfa againft crowds who condemn- 
 ed her conduct. Nay, we are told, that he confidered 
 himlelf, and every other hufband who ceafes to pleafe, 
 as the adulterer of nature. He therefore laboured llre- 
 nuoufly to obtain a divorce, to enable Therefa Hayne 
 to efpoufe the man whom (he preferred to himfelf. 
 Strange, however, to tell, the prejudices even of this 
 Cofmopolite were too ftrong for his principles. While 
 he was endeavouring to procure the divorce, he made 
 preparations at the fame time, by the ftudy of the ori- 
 ental languages, to undertake a journey to Thibet and 
 Indoftan, in order to remove from that part of the 
 world, in which both his heart and his perfon had ex- 
 perienced fo fevere a fhock. But the chagrin occafion- 
 ed by his misfortunes, joined to a fcorbutic affedtion, to 
 which he had been long fubjeft, and which he had con- 
 trafted at fea during the voyage of circumnavigation, 
 abridged his life, and prevented him frem realifing this 
 double projeft. He died at Paris, at the age of 39, 
 on the 13th of February 1792. 
 
 This is a ftrange tale; but we truft it will aot prove 
 ufelefs. The latter part of it at leaft (hows, that when 
 men diveft themfelves of the principles of religion, they 
 foon degenerate from the dignity of philofophers to the 
 level of mere fenfualifts ; and that the woman who can, 
 in defiance of decorum and honour, transfer her affec- 
 tions and her perfon from man to man, ranks no higher 
 in the fcale of being than a female brute of more than 
 common fagacity. It ftiews likewife, that the contempt 
 of our modern fages for thofe partial attachments which 
 unite individuals in one family, is a mere pretence; that 
 the diftates of nature will be heard ; and the laws of 
 nature's God obeyed. George Forfter, though he was 
 fuch a zealous advocate for liberty and equahty, as to 
 vindicate the adultery of his wife ; yet felt fo fenfibly 
 the wound which her infidelity inflifted on his honour, 
 that he could not furvive it, but periftied, in confequence, 
 in the flower of his age. 
 
 Royal FORT, is one whofe line of defence is at 
 leaft 26 fathoms long. 
 
 Star Fort, is a fconce or redoubt, conftituted by re- 
 entering and faliant angles, having commonly from five 
 to eight points, and the fides flanking each other. 
 
 FOSSIL-Meal, otherwife called lac lune, mineral 
 
 argaric.
 
 / r:kiicaiH. 
 
 F O U [ 6(^5 ] F R A 
 
 argaric, and ffuhr, h, according to M. Fabbroni, a mix- on the fame river, and joining to Tombudoo on the Fnuljhj, 
 ed earth, which exiialea an argillaceous odour, and weft. 
 
 throws out a light whitifh fmoke when fpriokled with The kingdom of the Foulahs, fituated between the 
 
 water. It is abundant in Tufcany, where it is em- upper part of the Gambia river and the coall of Sierra 
 ployed for cleaning plate. It does not efFervefce with Lcona, and along the Rio Grande, is governed by a 
 acids; is infufible in the fire, in which it lofss an eighth Maiionietan fovereign ; but the bulk of the people ap- 
 part of its weight, though it becomes fcarcely diminifh- pear to be Pagans. From the circumftances of their 
 ed in bulk ; and, according to the analylis made by M. long iiair, their lips, and comparatively light colour, 
 Fabbroni, confills of the following component parts: Major Rennel is decidedly of opinion, that the Fou. 
 yiliceous earth 55;, magnelia ly, water 14, argil 12, lab's are the Leucaethiops of Ptolemy ajul Pliny. The 
 lime 3, iron I. ^Vitll this earth, which is found near former, as he obferves, places the Leucxthiops in the 
 Calleldelpiano in the territories of Sienna, M. Fabbro- iituation occupied by the Foulahs; and by the name 
 
 which he gave them, he evidently meant to defcribe a 
 people lefs black than the generality of the Ethiopians. 
 Hence it may be gathered that this nation had been 
 traded with, and that fome notices refpefting it had 
 been communicated to Ptolemy. It may alfo be re- 
 marked, that the navigation of Hanno terminated on 
 this coaft ; and as this was alio the term of Ptolemy's 
 
 ni compofed bricks, which, either baked or unbaked, 
 floated in water. Hence he infers, that the floating 
 bricks, which Pliny mentions as peculiar to Maflilua 
 and Calento, two cities in Spain, mud have been made 
 of foffil meal. Bricks made of that fubllance refill wa- 
 ter exceedingly well, an4 unite perfe&ly with lime ; 
 they are fubjeft to no alteration either by heat or cold; 
 
 and about a twentieth part of argil may be added with knowledge, it may julUy be fufpefted that this part of 
 
 advantage to their compofition, without depriving them the coaft was dtfcribed from Carthaginian materi.ils. 
 of the property of floating. M. Fabbroni tried their Thofe who have perufed the Journal of MelTrs Watt 
 
 refiftance, and found it very little inferior to that of and Winterbottom through the Foulah country in 1794, 
 
 common bricks ; but it is much greater in proportion and recolleft how flattering a pi£ture they give of the 
 
 to their lightnefs. One of thefe bricks, feven inches urbanity and holpitality ot the Foulah's, will be grati- 
 
 in length, four and a half in breadth, and one inch fied on finding that this nation was known and dillin 
 
 eight lines in thicknefs, weighed only i4jth ounces; 
 whereas a common brick weighed 5 pounds 6|ths oun- 
 ces. 
 
 Bricks of foflil-meal may be of important benefit in 
 the conftruflion of reverberating furnaces ; as they are 
 fuch bad conductors of heat, that a perfon may bring 
 one half of them to a red heat, while the other is held 
 
 guilhed from the rcll of the Ethiopians at a remote pe- 
 riod of antiquity. 
 
 The contraft between the Moorifh and Negro cha- 
 rafters is as great as that between the nature of their 
 refpettive countries, or between their form and com- 
 plexion. The Moors appear to poflefs the vices of the 
 Arabs without their virtues ; and to avail themfelves of 
 
 in the hand. They may be employed alfo for buildings an intolerant religion, to opprels ftrangers : whilll the 
 that require to be light; for conftrudling cooking places Negroes, and efpecially the Mandingas, unable to com- 
 
 on board flilps ; and alfo floating batteries, the parapets 
 of which, if made of thefe bricks, would be proof againit 
 red hot bullets ; and, laftly, for conftrudling powder 
 magazines. 
 
 FOULAHS, or FooLAHs, a people in Africa, in- 
 habiting a country on the confines of the great defert 
 (fee Sahara in this StippL), along the parallel of nine 
 degrees north. They partake much of the negro form 
 and complexion ; but have neither the jetty colour, 
 thick lips, nor crifped hair of the negroes. They have 
 alfo a language dillinft from the Mandinga, which is 
 the prevailing one in this quarter. The Foulahs occu- 
 py, at leail: as fovereigns, feveral provinces or kingdoms, 
 interfperfcd throughout the traft comprehended be- 
 tween the mountainous border of the country of Sierra 
 Leona on the weft, and that of Tombuftoo on the eaft; 
 as alfo a large traft on the lower part of the Senegal 
 river; and thefe provinces are infulated from each other 
 in a vei-y remarkable manner. Their religion is Maho- 
 
 prehend a doiflrine that fubftitutes opinion or belief for 
 the focial duties, are content to remain in their humble 
 ftate of ignorance. The hofpitality fliewn by thefe 
 good people to Mr Park, a dellitute and forlorn llran- 
 ger, raifes them very high in the fcale of humanity : 
 and I know of no fitter title, fays Mr Rennel, to con- 
 fer on them than that of the Hindoos of Africa; at the 
 fame time, by no means intending to degrade the Ma- 
 homedans of India by a comparifon with tlie African 
 Moors. — See Major Kennels Geographical Iltujlrations of 
 Mr Park's jfourney, and of North Aj'rica at large, print- 
 ed for the African AflTociation. 
 
 FRANCAIS (Port dks), the name given by Pe- 
 roufe to a bay, or rather harbour, which he undoubted- 
 ly difcovercd on the north-weft coaft of America. It 
 is fituated, according to him, in 58° ■>,']' N. Lat. and 
 in i_^9° 50' W. Long, from Paris. When the two fri- 
 gates which he coramanded approached it, as they were 
 itretching along the coaft from fouth to north, he per. 
 
 medanifm ; but with a great mixture of Paganifm, and ceived from his fliip a great reef of rocks, behind wliich 
 
 with lefs intolerance than is pradtifed by the Moors. the fea was very calm. This reef appeared to be about 
 
 The principal of the Foulah ilates is that within Si- three or tour hundred toiles in length from ealt to weft, 
 
 erra Leona; and of which Teemboo is the capital. The and to be terminated, at about two cables length, by 
 
 next in order appears to be that bordering on the fouth the point of the continent, leaving a pretty large opeii- 
 
 of the Senegal river, and on the Jaloffs ; this is pro- iiig; fo that Nature feemed to have made, at the extrc- 
 
 perly named Siratik. Others of lefs note are Bondou, mity of America, a harbour like that of Toulon, only 
 
 with Foota-Torra adjacent to it, lying between the ri- more vaft in her defigns and in her means : this new 
 
 vers Gambia and Faleme; Foola-doo and Brooko along harbour was three or four leagues deep, 
 
 the upper part of the Senegal river ; Waflela beyond Some officers, who had been difpatched in boats to 
 
 the upper part of the Niger; and Maffina lower down reconnoitre this harbour, gave a report of it extremely 
 
 SuppL. Vol. I. Part II. ^P favouratlc ;
 
 F R A [ 666 ] F R A 
 
 Francais. favourable; and on the 3d of July 1 7^6, the two fri- advantage of the morning tide; finally, the eafterly Pranc»;i 
 
 *~~v^— ' gates entered it, and anchored ntar it;; mouth in three winds, which are contrary, appeared to him to be more » - 
 
 fathoms and a half, rocky bottom. The bay, however, frequent than thofe from the weil, and the vail height 
 
 was qnickly founckd, and much better anchoring^ ground of the furrounding mountains never permits the land 
 
 difcovered at an ifland in the middle of it, where the breezes, or thofe from the north, to penetrate into the 
 
 Ihips might ride in 20 fathoms water with muddy bot- road. 
 
 torn. This ground was taken pofrcfiion of, an obfer- As this port poffeffes great advantages, M. Peronfe 
 
 vatory evened on the ifland, which was only a muiket thought it a duty incumbent on him to make its in- 
 
 fhot from the fliips, and a fettlement formed for their conveniences alfo known. It feeined to him that this 
 
 ftav in the harbour. From a repor: made by one of anchorage is not convenient for thofe (hips which are 
 
 the officers who had penetrated towards the bottom of fent out at a venture for trafficking in flcins ; fuch (hips 
 
 the bay, Peroufe had conceived the idea of finding per- ought to anchor in a great many bays, and always 
 
 haps a channel by which he might proceed into the in- make the fliorteil (lay poffible in any of them ; becaufe 
 
 terior of America ; but he was dilappointed. The the Indians have always difpofcd of their whole (lock 
 
 bottom of the bay, indeed, according to iiim, is one of in the firft week, and all lo(t time is prejudicial to the 
 
 the moft extraordinary places in the world. It is a interefts of the owners : but a nation which (hould form 
 
 bafon of water, of a depth in the middle that could not the projeft of eftabliffiing factories fimilar to thofe of 
 
 be fathomed, bordered by peaked mountains of an ex- the Englifh in Hiidfon's Bay, could not make choice 
 
 ccfiive height, covered with (now, Avithout a blade of of a place more proper for fuch a fettlement. A fimple 
 
 grafs upon this immenfe coUeftion of rocks, condemned battery of four heavy cannon, placed upon the point of 
 
 by Nature to perpetual ilenlity. " I never (fays he) the continent, would be fully adequate to the defence 
 
 faw a breath of air ruftle the furface of this water; it is of fo narrow an entrance, which is alfo made fo difficult 
 
 never troubled but by the fall of enormous pieces of ice, by the currents. This battery could not be turned or 
 
 which continually detach themfclves from five different taken by land, becaufe the fea always breaks witli Ulch 
 
 glaciers, and which in falling make a noife that refounds violence upon the coail, that to diferabark is impoffible. 
 
 far in the mountains. The air is in this place fo very The fort, the magazines, and all the fettlements for 
 
 calm, and the filence fo profound, that the mere voice commerce, fliould be railed upon Cenotaph Ifland (a)j 
 
 of a man may be heard half a league off, as well as the the circumference of which is nearly a league : it is ca- 
 
 noife of fome fea birds which lay their eggs in the ca- pable of being cultivated, and there is plenty of wood 
 
 vities of thefe rocks." and water. The fliips not having their cargo to feek, 
 
 It was at the extremity of this bay that he was in but being certain of having it coUecledto a fingle point, 
 
 hopes of finding a paffage into the interior of America, would not be expofed to any delay : fome buoys, placed 
 
 He imagined that it might terminate in a great river, for the internal navigation of the bay, would make it ex- 
 
 of which the courfe might lie between two mountains ; tremely fafe and eafy. The fettlement would form pilots, 
 
 and that tliis river might take its fource in the great who, better verfed than we are in the fet and ftrength 
 
 lakes to the northward of Canada. Two channels of the current at particular times of tide, would enfure 
 
 were indeed found, ftretching, the one to the call, and the entrance and departure of the fliips. Finally, conti- 
 
 the other to the weft ; but both were very foon termi- nues the author, our traffic for otters flcins has been {o 
 
 nated by immenfe glaciers. very confiderable, that I may fairly prefume there could 
 
 In Port des Fratgais the variation of the compafs not, in any part of America, be a greater quantity of 
 
 is 28'' eaft, and the dip of the needle 74"^. The fea them collefted. 
 
 fifes there feven feet and a half at full and change of The climate of this coaft feemed to Peroufe much 
 the moon, when it is high water at one o'clock. The milder than that of Hudfon's Bay in the fame latitude. 
 fea breezes, or perhaps other caufes, aft fo powerfully Pines were meafured of fix feet diameter, and 140 high ; 
 upon the current of the channel, that M. Peroufe faw while thofe of the fame fpecies at Prince of Wales's 
 the flood come in there like the moft rapid river ; while, Fort and Fort York, are of a dimenfion fcarce fufficient 
 in other circumftances, at the fame period of the moon, for ftudding fail-booms. Vegetation is alfo very vigo- 
 it may be ftemmed by a boat. In this channel he loft rous during three or four months of the year ; and our 
 two (hallops and twenty men. In his different excur- author thinks, that Ruffian corn, as well as many com- 
 fions, he found the high water mark to be about ly feet mon plants, irifght thrive exceedingly at Port des Fran- 
 above the furface of the fea. Thefe tides are probably gais, where was found great abundance of celery, lu- 
 incident to the bad feafon. When the winds blow pine, the wild pea, yarrow, and andive. Among thefe 
 with violence from the fouthward, the channel muft be pot herbs were feen almolt all thofe of the meadows 
 iniprafticable, and at all times the currents render the and mountains of France ; fuch as the angeh'ca, the 
 entrance difficult; the going out of it alfo requires a buttercup, the violet, and many fpecies of grafs pro- 
 combination of circumftance,;, whicli may retard the de- per for fodder. The woods abound in gooieberries, 
 parture of a veffel many weeks; there is no getting un- rafpberries, and ftrawberries; clufters of elder trees, the 
 dtr way but at the top of high water ; the breeze from dwarf willow, different fpecies of briar which grow in 
 the weft to the north-weft does not often rife till to- the ftade, the gum poplar tree, the poplar, the fallow, 
 ward eleven o'clock, which does not permit the taking the horn-beam ; and, finally, fuperb pines, fit for the- 
 
 mafts. 
 
 (a) This name vras given to the ifland in the bay from the monument erefted on it to the memory of theit. 
 unfortunate companions.
 
 F R A [ 667 ] F R A 
 
 PfjnMls. mftfts of our largeft rtiips. Not any of the vegetable continually agitated by fear or revenge ; prone to an. Franciii. 
 ■' V 'produftions of this country are unknown in Europe, ger, and cafily irritated, they arc continually attacking '~~"v~~~ 
 M. de Martiniere, in his different excurfions, met with each other dagger in liand. Expofed in the winter to 
 only three plants which he thought new ; and it is perifli for want, bccaufe the chafe cannot be fuccefsful, 
 well known, that a botanill might do the fame in the they live during the fuinmer in the grealell abundance, 
 vicinity of Paris. as they can catch in Icfs than an hour a fuflicient quan- 
 
 Thc rivers were filled with trout and falmon ; and tity of filh for the fupport of their family; they re- 
 as the Indians fold thefe filh to the French in greater main idle during the left of the day, which they pafs 
 quantities than they could' confume, they had very little at play, to which they are as much addifted as fome of 
 filhing in the bay, and tiiat only with the line. They the inhabitants in pur great cities. This gaming is 
 caught fome ling, a fingle thornbaek, fome plaice, ^f- the great fource of their quarrels. If to all thci'e de- 
 taai or fa'itans, of which fome were more than ico ftrudtive vices they (llould unfortunately add a know- 
 pounds in weight (b), and a fifh refembling the whi- ledge of the ufe of any inebriating liquor, M. Peroufe 
 ting, but a little larger, which abounds on the coad of does not hefitate to pronounce, that this colony would 
 Provence, where it is known by the name oi poor priejl. be entirely annihilated." 
 
 Peroufe calls tiiefe fifh capelans. In the woods they Like all other favagcs, they arc incorrigible thieves ; 
 met with bears, martens, and fquirrels ; but they faw and when they adumed a mild and placid nppearance, 
 no great variety of birds, though the individuals were the Frenchmen were fure that tiiey had Itolen fome- 
 very numerous. , thing. Iron, of which they appeared to know the ufe, 
 
 " If tiie animal and vegetable produftions of this and of courfe the value, moll excited their cupidity ; 
 country refemble thofe of a great many others, its ap- and when our navigators were engaged in carefiing a 
 peaiance (fays our author) can be compared to no- child, the father was fure to feize the opportunity of 
 thing. The views which it prefents are more frightful taking up, and concealing under his (kin-garment, every 
 than thofe of the Alps and the Pyrenees ; but at the thing of that metal which lay within his reach, and was 
 fame time fo pifturefque, that they would dcfervethe not too heavy to be carried off. 
 
 vifits of the curious, were they not at the extremity of M. RoUin, furgeon major of one of the frigates, thus 
 the world. The primitive mountains of granite or defcribes thefe people. " They have very little fimi- 
 fchiftus, perpetually covered with fnow, upon whicl) larity to the Californians ; they are taller, ftouter, of 
 are neither trees nor plants, have their foundation in a more agreeable figure, and greater vivacity of exprel- 
 the fea, and form upon the fhore a kind of quay ; their fion : they are alfo much their fuperiors in courage and 
 Hope is fo rapid,- that after the firll two or three hun- fenfe. They have rather a low forehead, but more 
 dred toifes, the wild goats cannot climb them ; and all open than that of the Southern Americans; their eyes are 
 the gullies which feparate them are immenfe glaciers, black and very animated ; their eyebrows much fuller ; 
 of which the tops cannot be difcerned, wliile the bafe their nofe of the ufual fize, and well formed, except 
 is wafhed by the fea. At a cable's length from the being a little widened at the extremity ; their lips thin- 
 land there is no bottom at lefs than 160 fathoms. The ner ; their mouth moderately large; their teeth fine 
 fides of the harbour are formed by fecondary moun- and very even ; their chin and ears very regular. 
 tains, the elevation of which does not exceed from 800 " The women alfo have an equal advantage over 
 to 900 toifes ; they are covered with pines, and over- thofe of the preceding tribes ; they have much more 
 fpread with verdure, and the fnow is only feen on their mildnefs in their features and grace in their limbs. — 
 fummits : they appeared to be entirely formed of fchif- Their countenance would be even very agreeable, if, 
 tus, which is in the commencement of a ftate of decom- in order to fet it off, they did not make ufe of a ilrai ge 
 pofition ; they are extremely difficult to climb, but not cuflora of wearing in the lower lip an elli])tiial piece of 
 altogether inacceffible. wood, lightly grooved on its circumference and both 
 
 " Nature aifigns inhabitants to fo frightful a country, its fides, and which is commonly half an inch thick, 
 who as widely differ from the people of civilized conn- two in diameter, and three in length, 
 tries as the fcenc which has juft been defcribed differs " This fingular ornament, Ijefides being a great defor. 
 from our cultivated plains ; as rude and barbarous as niity, is the caufe of a very troublefonie as well as dif- 
 their foil is rocky and barren, they inhabit this land gulling involuntary flow of faliva. This appendage is 
 only to deflroy its population : at war with all the ani- peculiar to the women ; and female childrtn are made 
 mals, they defpife the vegetable fubflances that grow to undergo tlie.pieparatoiy operations from the time of 
 around them. I have teen (fays our author) women their birth. For this purpofe, the lower lip is pierced 
 and children eat fome rafpberries and ilrawberries ; but with a kind of pin of copper or gold, which is eitlier 
 thefe are undoubtedly viands far too infipid for men, left in the opening, or its place fupplied with a ring of 
 who live upon the earth like vultures in the air, or the fame material, till the period of puberty. The aper- 
 vvolves and tigei-s in the forefts. ture is then gradually enlarged, by fubflituting firll a, 
 
 " Their arts are fomewhat advanced, and in this re- fmall piece of wood of the form mentioned above, then 
 fpe£l civilization has made confiderable progrefs ; but a larger one ; and fo on, increafing its fize by degrees 
 that which foftens their ferocity, and polifhes their till it reaches the dimenfions jull ftated. 
 manners, is yet in its infancy. The mode of life they " This extraordinary cuftom (hews the great power 
 purfue excluding all kind of fubordination, they are of dilatation in the lip, and may encourage medical prac- 
 
 4 P 2 titioners 
 
 (b) This is a flat fifh, longer and not fo fquare as the turbet. Its back is covered with fmali fcalcs ; and 
 tbofe which are taken in Europe are much lefs than the fletans of Fort des Fran9ais.
 
 Franca'is 
 
 II 
 Fri(5lion. 
 
 F R I [ 668 ] F R I 
 
 titioners in their attempts to remedy deformities of this nics, Se^. II. § 8.) is taken from Fergufon ; but it FiiAin. 
 part by the ufe of the knife. lias been fliewn by Mr Vince, that the experiments from '~~"v~~~ 
 
 I '' The general colour of thefe people Is olive, a fain- which his conclufions were drawn were not properly 
 ter tinge of which is app.irent in their nails, which they ' inftituted. That eminent mathematician and philofo- 
 fuffer to grow very long ; the hue of the flcin, however, pher therefore entered upon the inveftigation of the 
 varies in different individuals, and in various parts of iubjeft anew, and endeavoured, by a fet of experiments,, 
 the fame individual, according to their expofure to the to determine the following queftions : 
 aftion of the air and fun. i. Whether friftion be a uniformly retarding force ? 
 
 •' Their hair is, in general, neither fo coarfe nor black 2. The quantity of friftion ? 
 
 as that of the South Americans. Gliefnut coloured hair 3. Whether the friftion varies in proportion to the 
 is by no means unfrequent among them. Their beard preffure or weight ? 
 
 is alfo fuller, and their armpits and parts of fex better 4. Whether the fridion be the fame on whichever 
 provided with hair. of its furfaces a body moves ? 
 
 " The perfect evennefs of their teeth led me at firft i. With refpefl to the lirft of thefe queftions, the 
 
 to fufpeft that it was the efTedk of art ; but after an author truly obferves, that if friftion be a uniform force, 
 attentive and minute examination, I could perceive no the difference between it and the given force of the 
 wearing away of the enamel, and 1 faw that this regu- moving power employed to overcome it muft alfo be 
 larity is natural. 'I'hey tattoo and paint their face and uniform ; and that therefore the moving power, if it 
 body, and bore their ears and the cartilage of their nofe. be a body defcending by its own weight, muft defcend 
 " Some writers have imagined, that the cultom of with a uniformly accelerated velocity, juft as when 
 painting the face and body, fo generally adopted by there was no friftion. The fpaces defcribed from the 
 the Africans, Americans, and Weft Indians, is only in- beginning of the motion will indeed be diminlftied in 
 tended as a prefervative againft noxious infefts. I any given time on account of the friftion ; but ftill 
 think, however, that I am warranted in aflerting its fole they muft be to each other as the fquares of the times 
 end to be ornament. I found it to prevail among the employed. See Dynamics in this Supplement. 
 
 2. A plane was therefore adjufted parallel to the ho- 
 rizon, at the extremity of which was placed a pulley, 
 which could be elevated or deprefted, in order to render 
 the ftring which connefted the body and the moving 
 force parallel to the plane. A fcale accurately divided 
 
 inhabitants of Eafter Ifland and the natives of Fort ties 
 Frangaisy without obferving among them either veno- 
 mous infefts or reptiles. Befides, I remarked that they 
 wore paint only when they paid us a vifit ; for they 
 made no ufe of it when in their own lioufes." 
 
 M. Peroufe himfelf fpeaks not fo favourably of the was placed by the fide of the pulley perpendicular to 
 
 women as M. Rollin. " They are (he fays) the moft the horizon, by the fide of which the moving force de- 
 
 difgufting of any on the earth, covered with ftinking fcended ; upon the fcale was placed a moveable ftage, 
 
 fkins, which are frequently untanned ; and yet they which could be adjufted to the fpace through which 
 
 failed not to excite defircs in fome petfons, in faft of the moving force defcended in any given time ; which 
 
 no fniall confequence : they at firft ftarted many diffi- time was meafured by a well-regulated pendulum clock 
 
 culties, giving alfurances by their geftures that they vibrating feconds. Every thing being thus prepared, 
 
 ran the rilk of their lives ; but being overcome by pre- the following experiments were made to afcertain the 
 
 fcnts, they had no objeftion to the fun being a witnefs, law of friftion. 
 
 and abfohitely refufed to retire into the wood." There 3. Exp. i. A body was placed upon the horizontal 
 can be no doubt that this planet is the god of thefe plane, and a moving force applied, which, from repeat- 
 people, (ince they frequently addreffed themfelves to it ed trials, was found to defcend 52^ inches in 4" ; for ■ 
 in their prayers ; but our voyagers faw neither temple by the beat of the clock, and the found of the moving 
 nor pvicft, nor the leaft trace of public worftiip at ftatcd force when it arrived at the ftage, the fpace could be 
 times. They bum their dead. very accurately adjufted to the time: The ftage was 
 FRE'GATES Fran^aise Brtji de, the name given then removed to that point to which the moving force 
 by La Peroufe to a dangerous reef of funken rocks would defcend in 3", upon fuppofition that the fpaces 
 which he difcovered in the Pacific ocean. On the defcribed by the moving power were as the fquares of 
 north-weft extremity of this reef they perceived an iflet the times ; and the fpace was found to agree very ac- 
 or fplit rock from 20 to 25 fathoms in height and about curately with the time : the ftage was then removed 
 50 toifes in diameter. From this idet tfie reef extends to that point to which the moving force ought to de- 
 more than four leagues to the fouth-eaft; and upon the fcend in 2", upon the fame fuppofition, and the defcent 
 extremity of the point in that dire6tion, the frigates was found to agree exaftly with the time : laftly, the 
 had almoft ftruck before the breakers were obferved. ftage was adjufted to that point to which the moving 
 This was during a fine clear night and fmooth fea. force ought to defcend in 1", upon the fame fuppofi- 
 With great propriety, the Commodore returned in the tion, and the fpace was obferved to agree with the 
 morning to afcertain the geographical fituation of this time. Now, in order to find whether a difference in 
 Vnknown rock ; and he eftimated the iflet to be in 23° the time of defcent could be obferved by removing the 
 
 45' N. Lat. and 168° 10' W. Long, from Paris. 
 
 FRICTION, in mechanics, is a fubjeft of great im- 
 portance both to the praftical engineer and to the fpe- 
 culative philofopher. It is thereiore our duty to cor. 
 
 ftage a little above and below the pofitions which cor- 
 reiponded to the above times, the experiment was tried, 
 and the defcent was always found too foon in the for- 
 mer, and too late in the latter cafe ; by which the au- 
 
 reft, in this Supplement, the miftakes into which we thor was affured, that the fpaces firft mentioned corre- 
 fell when treating of that fubjeft in the Encyclopedia, fponded exaftly to the times. And, for the greater 
 What we have there taught of friftion (fee Mecma- certainty, each defcent was repeated eight or ten times; 
 
 and
 
 F R I 
 
 [ 669 1 
 
 F R I 
 
 periment, where M = 7, W =; 25J, S = 4tt fcet, 
 / = 4 ; hence F = 7 — 75^^^ = 6.417 ; con- 
 
 frquently the friftion was to the weiglit of the rubbing 
 body as 6.4167 to 25.75. -^'"^ ^^'^ great accuracy of 
 determining the fiiflion by this method is manifeft from 
 hence, that if an error of one inc!i had been made in the 
 defcent (and experiments carefully made may always 
 determine the fpace to a much greater exaftr.cfs), it 
 would not have affefted the conclufion (jajidl-^i P^f' "f 
 the whole. 
 
 5. We come, in the next place, to determine whether 
 friiflion, cirUris paribus, varies in proportion to the 
 weight or prelTure. Now if the whole quantity of the 
 friiiion of a body, meafurcd by a weight without iner- 
 tia equivalent to the fri&ion drawing the body back- 
 wards, increafes in proportion to its weight, it is mani- 
 . adjufttd to the fpace correfponding to 2", upon the f^ft that the retardation of the velocity of the body 
 fame fuppofition, and it was found to agree with the ariling from the friaion will not be altered ; for the re- 
 
 Ftifl!on. and every caution ul'ed in this experiment was alfo made 
 ■"■ V ' ufe of in all the following. 
 
 Exp. 2. A fecond body was laid upon the horizontal 
 plane, and a moving force applied which de{cendcd4i| 
 inches in 3" ; the tlage was then adjullcd to the fpace cor- 
 refponding to 2", upon fuppofition that the fpaces de- 
 fcended through were as tiie fquarcs of the timet;, and it 
 was found to agree accurately with the time ; the ftage 
 was then adjufted to the fpace correfponding to 1 ', 
 upon the fame fuppofition, and it was found to agree 
 with the time. 
 
 Exp. 3. A third body was laid upon the horizontal 
 plane, and a moving force applied, which defcended 59^ 
 inches in 4'' ; the ftage was then adjufted to the fpace cor- 
 refponding to 3", upon fuppofition that the fpaces de- 
 fcended through were as the fquaresof the times, and it 
 was found to agree with the time ; the llage was then 
 
 Friflio 
 
 time ; the ftage was then adjufted to the fpace corre- 
 fponding to 1", and was found to agree with the time. 
 
 Exp. 4. A fourth body was then taken and laid upon 
 the horizontal plane, and a moving force applied, which 
 defcended 55 inches in 4" ; the ftage was then adjufted 
 to the fpace through which it ought to defccnd in 3", 
 upon fuppofition that the fpaces defcended through 
 were as the fquares of the times, and it was found to 
 agree with the time ; the ftage was then adjufted to 
 the fpace correfponding to 2", upon the fame fuppofi- 
 tion, and was found to agree with the time ; laftly, the 
 ftage was adjufted to the fpace correfponding to i", and 
 it was found to agree exaftly with the time. 
 
 Befides thefe experiments, a great number of others 
 were made with hard bodies, or thofe whole parts fo 
 firmly cohered as not to be moved Inter fe by the fric- 
 tion ; and, in each experiment, bodies of very diflerent 
 degrees of fridtion were chofen, and the refults all 
 agreed with thofe related above; we may therefore con- 
 clude, that the fr'iiiion of hard bodies in motion u a uni- 
 formly retarding force. 
 
 But to determine whether the fame was true for bo- 
 dies when covered with cloth, woollen, S:c. experiments 
 were made in order to afcertain it ; when it was found, 
 in aU cafes, that the retarding force increafed with the 
 velocity ; but, upon covering bodies with paper, the 
 
 Quantity of frid'tion 
 
 tardation vanes as ,^= — -r -— - ; hence, if a 
 
 (^antity or matter 
 
 body be put in motion upon the horizontal plane by 
 any moving force, if both the weight of the body and 
 the moving force be increafed in the fame ratio, the ac- 
 celeration arifing from that moving force will remain 
 the fame, becaul'e the accelerative force varies as the 
 moving force divided by the whole quantity of matter, 
 and both are increafed in the fame ratio ; and if the 
 quantity of friftion increafes alfo as the weight, then 
 the retardation arifing from the friftion will, from what 
 has been faid, remain the lame, and therefore the whole- 
 acceleration of the body will not be altered ; confe- 
 quently the body ought, upon this fuppofition, ftill to 
 dcfcribe the iame fpace in the fame time. Hence, by 
 oblerving the fpaces defcribed in the fame time, when 
 both the body and the moving force are increafed in 
 the fame ratio, we may determine vihether the friftion 
 increafes in proportion to the weight. The following 
 experiments were therefore made in order to afcertain 
 this matter : 
 
 Exp. I. A body weighing looz. by a moving force of 
 40/,. defcribed in 2" a fpace of 51 inches; by loading the 
 body with 10 oz. and the moving force with 40Z. it 
 defcribed 56 inches in 2" ; and by loading the body 
 
 confequences were found to agree with thofe related ^F'r^7l'r.^'^-°V ^.nd the movmg.force with 4 oz. it 
 
 above. 
 
 4. Having proved that the retarding force of all hard 
 bodies arifing from friftion is uniform, the quantity of 
 friftion, confidered as equivalent to a weight without 
 inertia drawing the body on the horizontal plane back- 
 wards, or ading contrary to the moving force, may be 
 immediattly deduced from the foregoing experiments. 
 For let M =: the moving force expreffed by its weight; 
 F := the friftion ; W =: the weight of the body upon 
 the horizontal plane ; S =: the ipace through which - 
 the moving force defcended in the time / exprelfed in 
 feconds ; r :: i6jV feet; then the whole accelerative 
 
 M— F 
 force (the force of gravity being unity) will be >, , ^ir ; . 
 
 hence, by the laws of uniformly accelerated motions, 
 
 M — F ^ , o r .If n/r Mx W X S 
 
 — — — - X r r=: S, confequently F = M 2_: 
 
 M-fW ' 1 / r^ • 
 
 To exemplify this, let us take the cafe of the laft ex- 
 
 defcribed dx, inches in 2". 
 
 Exp. 2: A body, whofe weight was 16 oz. by a mo- 
 ving force of 5 oz. defcribed a fpace of 49 inches in 
 3['; and by loading the body with 64 oz. and the mo. 
 ving force with 20 oz. the fpace defcribed in the fam.e 
 time was 64 inches. 
 
 Eyp. 3. A body weighing 6 oz. by a moving force of 
 2-J oz. defcribed 28 inches in 2''; and by loading the ■ 
 body with 24 oz. and the moving force with looz. the 
 fpace defcribed in the fame time was 54 inches. 
 
 Exp. 4. A body weighing 8 oz. by a moving force of 
 4 oz. defcribed 3 3-J- inches in 2"; and by loading the 
 body with 8 oz. and the moving force with 4 oz. the 
 fpace defcribed in the fame time was 47 inches. 
 
 Exp. J. A body whofe weight was 9 oz. by a moving 
 force of 4 J ox. defcribed 48 inches in 2' ; and by loading; 
 the body with 9 oz. and the moving force with 44 oz.> ■ 
 t!'.< fpace defcribed in the fame time was 60 inches. 
 
 Exp. 6. A body weighing 10 oz. by a moving force cfi 
 
 3 oz. .
 
 P R I 
 
 [ 670 ] 
 
 F R I 
 
 Triiilion. ^ az, dcfcribed 20 inclies in 2' j by loa^liiig the body 
 » with I o oz. and llie moving force with 3 oz. the fpace 
 
 defcrlbcd in the fame timo was 3 1 inches ; and by load- 
 ing the body again with 30 oz. and the moving (orce 
 with 9 oz. tlie Ipace dcfcribed was 34 incites in i'. 
 
 From thele experiments, and many others which it 
 is not necefl'ary here to relate, it appears, that the fpace 
 defcribed is always increafed by increafnig the weight 
 of the body and the accelerative force in the fame ra- 
 tio ; and as the acceleration arifnig from the moving 
 force continued the fame, it is manifeft, that the retar- 
 dation arifing from the fridion muft have been diminidi- 
 ed, for the whole aixclerative force muft have been in- 
 creafed on account of the increafe of the fpace deloribcd 
 in the fame time ; and hence (as the retardation from 
 
 . Qiiantity of friftion\ 
 
 friction vanes as 7^-^ r — j 1 the quantity of 
 
 Quantity or matter/ ^ -^ ■' 
 
 Jridlon hicreaps in a lefs ratio than the quantity of matter 
 
 or lueight of the body. 
 
 6. We come now to the lail thing which it was pro- 
 pofed to determine, that is, whether the friftlon varies 
 by varying the furface on which the body moves. Let 
 us call two of the furfaccs A and a, the former being 
 the greater, and the latter the lefs. Now the weight 
 on every given part of a is as much greater than the 
 weight on an equal part of A, as A is greater than a ; 
 if therefore the fridion was i.u proportion to the weight, 
 caterij paribus, it is inanifeft, that the fridion on a 
 would be equal to the fridion on A, the whole fridion 
 being, upon fucJi a luppofition, as the weight on any 
 given part of each furface multiplied into the number 
 of fuch parts or into the whole area, which produds, 
 from the proportion above, are equal. But frum the 
 laft experiments it has been proved, tli-at the fridion 
 on any given furface increafes in a lefs ratio than the 
 weight ; confcquently the fridion on any given part of 
 a has a lefs ratio to the fridion on an equal part of A 
 than A has to a, and hence the fridion on a is lefs 
 than the fridion on A, that is, the fmallell furface has 
 always the leaft fridion. 
 
 As tlus conclufion is contrary to the generally re- 
 ceived opinion, Mr Vince thought it proper to confirm 
 it by a fet of experiments made with different bodies of 
 exadly the fame degree of roughnefs on their two fur- 
 faces. 
 
 Exp. I. A body was taken whofe flat furface was to 
 its edge as 22 : 9, and with the fame moving force the 
 body dcfcribed on its flat fide 33^ inches in 2", and on 
 its edge 47 inches in the fame time. 
 
 Exp. 2. A fecond body was taken whofe flat furface 
 was to its edge as 32 : 3, and with the fame moving 
 force it dcfcribed on its flat fide 32 inches in 2", and 
 on its edge it dcfcribed 374- inches in the fame time. 
 
 Exp. 3. He took another body and covered one of 
 its furfaces, whofe length was 9 inches, with a fine 
 rough paper, and by applying a moving force, it dc- 
 fcribed 25 inches in 2" ; he then took off fome paper 
 from the middle, leaving only -j-tlis of an inch at the 
 two ends, and with the fame moving force it dcfcribed 
 40 inches in the fame time. 
 
 Exp. 4. Another body was taken which had one of 
 Its furfaces, whofe length was 9 inches, covered with a 
 line rough paper, and by applying a moving force it 
 dcfcribed 42 inches in 2" ; fome of the paper was then 
 taken off from the middle, leaving only i|. inches at 
 
 the two ends, and with the fame moving force it dc- 
 fcribed 54. inches in 2" ; he then took off more jiaper, 
 leaviiig only J of an incli at the two ends, and the body 
 then defcnbcd, by the fame moving force, 60 inches in 
 the lame time. 
 
 In the two laft experiments the paper which was ta- 
 ken ofl the furface was laid on the body, that its weight 
 might not be altered, 
 
 Exp. 5. A body w-as taken whofe flat furface w.is to 
 its edge as 30 : 17 ; the flat fide was laid upon the iio- 
 rizontal plane, a moving force was applied, and the 
 Itage was fixed in order to flop the moving force, in 
 coiilequence of which the body would then go on with 
 the velocity acquirifd jntil the fridion had detlroyed 
 all its motion ; when it appeared from a mean of 12 
 trials tliat the body moved, after Its acceleration ccafed, 
 5f inches before it flopped. The edqc was then ap- 
 plied, aud the moving force defcended through the 
 fame fpace ; and it was found, from a mean of the fame 
 nunibcr of trials, that the fpace dcfcribed was j-j inches 
 before the body lofl all its motion, after it ceafed to be 
 accelerated. 
 
 E.\p. 6. Another body was then taken whofe flat 
 furface was to its edge as 60 : 19, and by proceeding 
 as before, on the fiat furface it dcfcribed, at a mean of 
 12 trials, 5-5 inches, and on the edge 6ij inches, be- 
 fore it flopped, after the acceleration ceafed. 
 
 Exp. 7. Another body was taken whofe flat furface 
 was to its edge as 26 : 3, and the fpaces dcfcribed on 
 thefe two furfaces, after the acceleration ended, were, 
 at a mean of ten trials, 4^ and 7^5- inches refpedively. 
 
 From all thefe different experiments it appears, that 
 the fmallcfl furface had always the leafl fridion, which 
 agrees with the confequence deduced from the confide- 
 lation that the fridion does not increafe in fo great a 
 ratio as theweight ; we may therefore conclude, that 
 the Jri3ion of a body does not continue the fame when 
 it has different furfaces applied to the plane on ivhich it 
 moves, but that the Jmallefl furface tudl have the leajl fric- 
 tion. 
 
 To the experiments inflituted by Mr Fergufon and 
 others, from which conclnlions have been drawn fo dif- 
 ferent from theie, oar author makes the following ob- 
 jedions : It was their object to find what moving force 
 would _;//// put a body at rcll in motion ; and having, as 
 they thought, found it, they thence concluded, that 
 the accelerative force was then equal to the fridion. 
 But it is manifeft, as Mr Vince oblerves, that any force 
 which will put a body in motion ninil be ^rM/^r than 
 the force which oppoles its motion, otherwife it could 
 not overcome it ; and hence, if there were no other ob- 
 jedion than this, it is evident, that the fridion could 
 not be very accurately obtained : but there is another 
 objedion which totally deftroys the experiment io far 
 as it tends to fliew the quantity of fritfion, which is 
 the ftrong cohefion of the body to the plane when it 
 lies at reft ; and this is confirmed by the following ex- 
 periments. I/?, A body of 12} oz. was laid upon an 
 horizontal plane, and then loaded with a weight of 
 8 lb. and fuch a moving force was applied as would, 
 when the body was juft put in motion, continue that 
 motion without any acceleration ; in which cafe the 
 fridion muft be juft equal to the accelerative force. 
 The body was then flopped, when it appeared that the 
 fame moving force which had kept the body in motion be- 
 fore.
 
 F R I [ 671 ] F R I 
 
 priili^', fore, would tiot/H/ it in motion, and it was found nc- pofc of producing artificial cold. Some of tliefe nilx- Fiigorlfic. 
 
 Frig- TiHc. ccfTary to take off 4I oz. from the body before the tuies arc enumerated under the title Cold (Enryc/.), ' " ' •' 
 lame moving force viould put it in motion ; it appears and a much more accurate hll of them is given, togc- 
 thercfore, that this body, when laid upon the plane, ther with the principle upon which they produce their 
 at reft, acquired a very ftrong cohefion to it. 2Jly, efieft, in the article Chemistry, n° 282. (Suppl.). 
 A body whofe weight was i6 oz. was laid at reft upon There is one mixture, however, not mentioned in that 
 the horizontal plane, and it was found that a moving lift, which was employed by Seguin, and feems, on 
 force of 6 oz. would jull put it in motion ; but that a many accounts, to be the moft eligible that has vet 
 moving force of 4 oz. luoulil, when it was juft put in been propofcd. Confidering the muriats (fee Chi-- 
 motion, continue that motion without any acceleration, mistr Y-Zn^/t.-c. Siipjil.) as a clafs of fnlts beft fuited for 
 and therefore the ncctlerative force muft then have been the purpofe, he gave the decided preference to muriat 
 equal to the friction, and not when the moving force ot of lime in cryftals ; and his method was to mix the 
 60Z. was applied. cryftals, previoully pulvcrifed, with an equal weight of 
 
 From thefe experiments, therefore, ft appears how uncompreffed fnovv. 
 very confiderable the cohefion was in proportion to the ]5y means of this mixture Mr W. H. Prpys junior, 
 
 fridlion when the body was in motion ; it being, in the of the London Philofopliical Society, with the atjiftance 
 latter cafe, almoft -yd, and in the former it was found to of fomc friends, froze, on the 8th of February 1700, 
 be very nearly equal to the whole fridlion. All the 56 lbs. averdupoife of mercury into a folid maf^. The 
 conclufious therefore deduced from the experiments, mercury was put into a ftrong bladder and well fecured 
 which have been iaftltuted to determine the friftion at the mouth, the temperature of the laboratory at the 
 from the force ueceflary to put a body in motion, have time being -|. 33°. A mixture confifting of muriat of 
 manifeftly been totally falfe ; as fuch experiments only lime 2 lb. at -|- 33", and the fame weight of fnovv at 
 Ihew the refiftance which arifes from the cohefion and + 32" gave — 42° (a). Tire mercury was put as 
 friftion conjointly. gently as poffible into this mixture (to prevent a rup- 
 
 Our author concludes this part of his fubjeft with ture of the bladder), by means of a cloth held at the 
 the following remark upon n° 5 : " It appears from all four corners. When the cold mixture had robbed the 
 the experiments (fays he) which I have made, that the mercury of fo much of its heat as to have its own tem- 
 
 proportion of the increale of the frjftion to the increafe perature thereby raifed from 42^ to -I- e, another 
 
 of the weight was different in all the different bodies mixture, the fame in every refpeft as the laft, was 
 which were made ufe of; no general rule therefore can made, which gave, on trial with the thermometer, 
 be ettablifhed to determine this for all bodies, and the — 43". The mercury was now received into the cloth, 
 experiments which I have hitherto made have not been and put gently into this new mixture, where it was left 
 fufficient to determine it for the fame body." to be cooled (till lower than before. 
 
 He then proceeds to cftablifh a theory upon the In the mean time five pounds of muriat of lime, iji a 
 principles which he has deduced from his experiments, large pail made of tinned iron, and japanned inlide and 
 That theory is comprehended in five propofitions, of outlide, was placed in a coolinp- mixture in an earthen- 
 which the objecl of the firll: is " to find the time of ware pan. The mixture in the pan, which coufifted of 
 defcent, and the number of revolutions made by a cy- 4lb. of mnriat of lime and a b'ke quantity of fnow, of 
 linder rolling down an inclined plane in confequence of the fame temperature as the former, in one hour redu- 
 its friftion. ced the 5 lb. of muriat in the pail to — 15°. The mix- 
 
 II. " To determine the fpace through which a body, ture was then emptied out of the earthen pan, and four 
 projetled on an horizontal plane with a given velocity large corks, at proper dillances, placed on its bottom, 
 will move before it ftcps, or before its motion becomes to ferve as refts for the japanued pail which was now 
 uniform. put into the pan. The corks anfwered the purpofe of 
 
 III. " To find the centre of friftion. infulating the inner veffel, while the exterior one kept 
 
 IV. " To determine, from the given velocity with off the furroundiiig almofphere, and prcferved the air 
 which a body begins to revolve about the centre of its between the two at a low temperature. 
 
 bafe, the number of revolutions which that body will To the 5 lb. of muriat of lime which had been cool- 
 
 make before all its motion be deftroyed. ed, as already noticed, to — if, and which ftill re- 
 
 V. " To find the nature of the curve defcribed by mained in the metallic veffel, was now added fnow, un- 
 any point of a body affefted by friftion when it de- compreffed and free from moifture, at the ufual tcm- 
 fcends down any inclined plane." perature of + 32°. In lefs than three minutes the mix- 
 To give the folutions of thefe problems, with the co- ture gave a temperature of — 62° : a degree of cold 
 
 roUaries deduced from them, would fwell this article to which perhaps was never before produced in this coun- 
 
 ttvj little purpofe ; for they would be unintelligible to try, being 94" below the freezing point of water. 
 
 the mere mechanic, and the mathematician will either The mercury, which, by immerlion in the fecond 
 
 folve them for himfelf, or have recourfe to the original cooling mixture to which it was expofed, was by this 
 
 memoir, where he will find folutions at once elegant and time reduced to — 30", was now, by the means em- 
 
 perfpicuous. ployed before, cautioufly put into the laft- made mixture 
 
 FRIGORIFIC Mixtures, are thofe which expe- of the temperature of — 62°. A hoop with net-work 
 
 rience has taught philofophers to employ for the pur- faftened to its upper edge, and of fuch a breadth in the 
 
 nm 
 
 (a) The thermometer made ufe of in this experiment was filled with tinged alcohol, and acturately divided 
 according to Fahrenheit's fcale.
 
 F R I 
 
 [ 672 ] 
 
 r u E 
 
 Frliioriric. rim that the net-work, when loaded with the bladder 
 
 ■' 1/ ' of mercury, could not reach its lower edge, was at the 
 
 bottom of the mixture, to prevent the bladder from 
 
 •coming in contaa with the velTel ; by which means the 
 
 mercury was fufpcnded in tlio middle of the mixture. 
 
 As foon as the bladder was fafely depofitedon the net- 
 
 opportunity offers, he and his friends mean to make Vim 
 fome experiments with that view, and to communicate II 
 the refidt of them to the editor of the valuable mifcel- , 
 lany * from which we have taken this account of his * 77,, f^,-. 
 experiment on mercury. lif-fhU-al 
 
 FRIO, a fm,ill ifland on the coaft of the Brazils, fi-'V^"!'"* 
 
 work, the vcH'cls wtie carefully covered over with a tuated in 32° 2' fouth lat. and 41° 31' 45" weft Ion. 
 
 cloth, to impede the paffage of heat from the furround- 
 ing atmofphere into the freezing materials. The con- 
 ■denfatioB of moilhire from the atmofphere by the agen- 
 cy of fo low a temperature was greater than could have 
 l)een expefted : it floated like Ream over the veffcls. 
 End, but for tlie interpofed covering, would have given 
 the mixture more temperature than was defirable. 
 
 The land of Frio is high, with a hollow in the middle, 
 which gives it, at a dillance, the refemblaiice of two fe- 
 parate iflands. The paffage between the ifland and the 
 continent is about a mile broad, and fecraed to Sir E- 
 rafmus Gower to be clear from flioals. 
 
 FROST, as is well known in Scotland, is particu- 
 larly dellruftive to the bloffom of fruit trees ; and the 
 
 .■\fter -one hour and forty minutes they found, by following method of fecuring fuch trees from being da- 
 means of a fearcher introduced for the purpofe, that maged by early frofts may be acceptable to many of 
 the mercury was fohd and fixed. The temperature of our readers. A rope is to be interwoven among the 
 
 ■the mixture at this time was — 46, that is, 16° higher 
 than when the mercury was put into it. 
 
 Our young phllofophers having negleftcd to fling 
 the hoop and net-work in fuch a manner as might 
 have enabled them to lift it out of the mixture at once, 
 ■with the bladder and its contents, were obliged to turn 
 out the Vi4iole contents of the pail into a large evapora- 
 ting capfule made of iron. This was not effefted with- 
 out the mercury ftriking againll its bottom and bcmg 
 
 branches of the tree, and one end of it brought down 
 fo as to be immerfed in a bucket of water. The rope, 
 it is faid, will aft as a condudlor, and convey the ef- 
 fefts of the froft from the tree to the water. This idea 
 is not new ; for the following paflage may be found in 
 Colerus : " If you dig a trench around the root of a 
 tree, and fill it with water, or keep the roots moid till 
 it has bloomed, it will not be injured by the froll. Or, 
 in fpring, fufpend a veflel filled with water from the 
 
 fraftured. though it received a confiderable increafe ot tree. If you vi-ifli to preferve the bloom from being 
 
 temperature from the capfule. The frafture was fimi- hurt by the froft, place a velfel of water below it, and 
 
 lar to that of zinc, but with parts more cubical. The the froft will fall into it." Phihfoph'cal Magazine, n" 11. 
 
 larger pieces were kept for fome minutes before fufion FUEL, whatever is proper to burn, or make a fire, 
 
 took place, v/hile others were twifted and bent into va- either for warming a room or drefling victuals. The 
 
 rious forms, to the no fmall gratification and furprife of fuel moft generally ufed in Great Britain is pitcoal, 
 
 thofe who never witneffed or expefted to fee fuch an which is a very expenfive article ; and that expence is 
 
 effeft produced on fo fufible a metal. greatly increafed by the wafte of coal occafioned by the 
 
 In experiments of the kind here defcribed, all the injudicious manner in which fires in open chimneys are 
 
 exterior veflels ftiould be of earthen-ware or wood, commonly managed. The enormous wafte of fuel in 
 
 which being bad conduftors of heat, prevent the ingre- London, for inftance, may be eftimated by the vaft dark 
 
 dients from receiving heat from the atmofphere and cloud which continually hangs over that great metro- 
 
 furrounding objeds with the fame facility that they polis, and frequently overfliadows the whole country 
 
 would through metals; and, for a fimilar reafon, the far and wide; for this denfe cloud is certainly compofed 
 
 interior veflels are beft of metal, that they may allow almoft entirely of unconfumed coal, which has efcaped 
 
 the heat to pafs more readily from the fubftance to be by the chimneys, and continues to fail about in the air, 
 
 cooled into the frigorific mixture employed for that till, having loft the heat which gave it volatility, it falls 
 
 purpofe. in a dry fliower of extremely fine black duft to the 
 
 Muriat of lime is certainly the moft powerful, and ground, obfcuring the atmofphere in its defcent, and 
 
 at the fame time the moft economical fubftance that frequently changing the brighteft day into more than 
 
 can be employed for producing artificial cold ; for its Egyptian darknefs. 
 
 firft coft is a mere trifle, being a refiduum from many " 1 never (fays Court Rumford) view from a dii- 
 
 chemical procefl"es, as the diftdlation of pure ammonia, tance, as I come into town, this black cloud whicli 
 
 &c. and often thrown away : bcfides, it may be repeat- hangs over London, without wiftiing to be able to com- 
 
 edlv ufed for fimihr experiments, nothing being ne- pute the immenfe number of chaldrons of coals of which 
 
 ceffary for this purpofe but filtration and evaporation it is compofed ; for could this be afcertained, I am per- 
 
 to bring it to its Crft ftate. The evaporation fliould be fuaded fo ftriking a faft would awaken the curiofity, 
 
 carried on till the folution becomes as thick as a ftrong and excite the aftonifliment of afl ranks of the inhabi- 
 
 fyrup, and upon cooling the whole will be cryftallifed : tants ; and perhaps turn their minds to an objeft of eco- 
 
 jt niuft then be powdered, put up in dry bottles, well nomy to which they have hitherto paid little attention." 
 
 corked, and covered with bladder or cement to pre- The objeft to which the benevolent author more 
 
 vent li'quefaftion ; which otherwife would foon take particularly wiflies to direft the piibhc attention, is the 
 
 place, owing to the great affinity the muriat has for lighting of a coal fire, in which more wood ihould be 
 
 moifture. employed than is commonly ufed, and fewer coals ; and 
 
 The powerful effefts produced by the frigorific mix- as foon as the fire burns bright, and the coals are well 
 
 ture of muriat of lime and fnow, prefent a wide field lighted, and not before, more coals fliould be added to 
 
 for experinmts to determinethe poflibility of fixing increafe the fire to its proper fize. 
 
 fome of the gafes by intenfe cold. And we are hap- Kindling balls, compofed of equal parts of coal, — 
 
 DV to be informed by Mr Pepys, that, as foon as an charcoal, — and clay, tlis two former reduced to a fine 
 
 ^^ powder.
 
 F U L [ (^^73 ] _ F U L 
 
 powder, well mixed and kneaded together, with the tiotis, wliioli arc not unimportant, will be intelligible to 
 
 clay nioillened with water, and then formed into balls every reader who has peiufed that article in this Sup- 
 
 ' of the fize of hens eggs, and thoroughly dried, might plemtnt. 
 
 be nfed with great advantage inllead of wood for kin- The afperilies with which the furface of wool is every 
 
 dling fires. Thefe kindling balls may be made fo in- where furronnded, and the difpofition which it has to 
 
 flammable as to take tire in an inllant and with the afTunie a progrellive motion towards the root, render 
 
 fmalleil fpark, by dipping them in a ftrong folution of the Ipinniiig of wool, and making it into cloth, difti- 
 
 nitre, and then drying them again ; and they would nei- cult operations. In order to fpin wool, and afterwards 
 
 ther be expenfive nor liable to be fpoilcd by long keep- 
 ing. Perhaps a quantity ot pure charcoal, reduced to 
 a verv tine powder, and mixed with the lolutiou of nitre 
 in which they are dipped, would render them Hill more 
 inflammable. 
 
 The Count thinks that the fires which are made in 
 the open chimneys of elegant apartments might he great- 
 ly improved by preparing the fuel ; tor nothing (fays 
 he) was ever more dirty, inelegant, and dilgulling, than 
 a common coal iire. 
 
 more cleanly, and in all rcfpeCts a pleafanter fire, than 
 can be made with crude coals ; and, he believes, would 
 not be more expenfive fuel. In Flanders, and in feveral 
 parts of Germany, and particularly in the duciiies of 
 Juliers and Bergen, where coals are ufed as fuel, the 
 coals are always prepared before they are ufed, by 
 
 ly, in that which is combined with the flame and fmoke 
 which rife from the fire, and which, if means are not 
 found to flop it, goes off immediately by the chimney 
 and is loft — and the radiant heat which is fent off from 
 the fire in all diretlions in right lines: — It is therefore 
 reafonable to conclude, that the particles of clay, which 
 
 Fulling, 
 Fulmiiia- 
 
 to weave it, we are obliged *to cover its fibres with a 
 coating of oil, which, filling the cavities, renders the 
 afperities lels tenfible ; in the lame way as oil, when rub- 
 bed over the lurtace of a very fine file, renders it ftill 
 lefs rough. When the piice of cloth is linilhed, it mull 
 be cleanfed from this oil ; which, befides giving it a 
 difagreeable fniell, would caule it to foil whatever it 
 came in contadl with, and would prevent its taking the 
 colour which is intended to be given to it by the dyer. 
 To deprive it of the oil, it is carried to tlic fulling-mill, 
 
 Fire balls, of the fize of goofe eggs, compofed of where it is beat with hammers in a trough full of wa- 
 coal and charcoal in powder, mixed up with a due pro- ter, in which fome clay has been mixed ; the clay corn- 
 portion of wet clay, and well dried, would make a much bines with the oil, which it feparates from the cloth, and 
 
 both together are walhed away by the frelh water which 
 is brought to it by the machine ; thus, after a certain 
 time, the oil is entirely wafhed out of the cloth. 
 
 But the fcouring of the cloth is not the only ohjetl 
 in fulling it ; the alternate prelTure given by the mallets 
 to the piece of chjth, occafions, elpecially when the 
 
 pounding them to a powder, and mixing them up with fcouring is pretty far advanced, an effeft analogous to. 
 
 an equal weight of clay, and a fufHcient quantity of that which is produced upon hats by the hands of the 
 
 water to form the whole into a mafs, which is kneaded hatter ; the fibres of wool which compofe one of the 
 
 together and formed into cakes ; which cakes are after- threads, whether of the warp or the woof, alfume a pro. 
 
 wards well dried and kept in a dry place for ufe. And grefilve movement, introduce themtelves among thofe of 
 
 it has been found, by long experience, that the expence the threads nearcll to them, then into thofe which fol- 
 
 attending this preparation is amply repaid by the im- low ; and thus, by degrees, all the threads, both of the 
 
 provement of the fuel. The coals, thus mixed with warp and the woof, become felted together. The cloth, 
 
 clay, not only burn longer, but give much more heat after having, by the above means, become fliortentd iu 
 
 than when they are burnt iu their crude (late. all its dimenfions, partakes both of the nature of cloth 
 
 It will doubtlefs appear extraordinary to thofe vcho and of that of felt ; it may be cut without being fubjeft 
 
 have not confidered the fubjeiA with fome attention, to ravel, and, on that account, we are not obliged to 
 
 that the quantity of heat produced in the combuftion hem the edges of the pieces of which clothes are made, 
 
 of any given quantity of coals (hould be increafed by Laftly, As the threads of the warp and thofe of the 
 
 mixing the coals with clay, which is certainly an incom- woof are no longer fo dillinit and feparated from each 
 
 buftible body ; but the phenomenon may be explained other, the cloth, which has acquired a greater degi-ee 
 
 in a fatisfaftory manner. of thickaefs, forms a warmer clothing. Knit woriled 
 
 The heat generated in the combuftion of any fmall alfo is, by fulling, rendered lels apt to run, in cafe u 
 
 particle of coal CNift ing under two dillinft forms, name- ftitch fhould drop in it. 
 
 FULMINATING Gold.") See Chemistry, %//.- 
 Fulminating Si/-ver. y nos 849 and «jO. 
 
 Mr Berthollet, the inventor of fulminating filver, ha- 
 ving contented himlelf with a general and concile de- 
 fcription of this fubjcA, many pratlical chemills have 
 failed in their attempts to prepare it ; and others, form- 
 are furrounded on all iides by the flame, arreft a part at iug their opinions from the fpecimens which they had 
 leaft of the combined heat, and prevent its efcape ; and made, have been expofed to great danger ; as will appear 
 this combined heat, fo arretted, heating the clay red hot, from the following relation : 
 
 is retained in it, and being changed by this operation to An ounce of fine filver was dilTolved in the courfe of 
 
 radiant heat, is afterwards emitted, and may be directed eight hours in an ounce of pure nitrous acid, of the 
 and employed to ufeful purpofes. In the compofition London Pharmacopoeia, diluted previoufly with three 
 of fire-balls, the Count thinks it probable that a certain ounces of diftilled water in a glafs matrafs. The (olu- 
 proportion of chaff, of ftraw cut very fine, or even of tion being poured off, the refiduary black powder and 
 faw-duft, might be employed with great advantage. the matrafs were walhed with fcven or eight ounces of 
 
 FULLING OF WOOLLEN CLOTHS (fee the method warm diftilled water, and this was added to the folution. 
 of performing the operation under the article Fulling, The black powder, being gold, was rejedled ; fome 
 Encycl.) depends, like Felting, fo entirely upon the gold being thus feparable from any filver of commerce, 
 ftrufture of wool and hair, that the following obferva- To the foregoing diluted folution, pure lime-water 
 SupPL. Vol. I. Part II. 4 Q„ prepared
 
 V U L 
 
 Fu'raina- prepared with diftilled water was added gradually; for 
 ^"g:- the folution ought not to be poui-ed into the lime water. 
 • When about thirty pints of lime-water had been expend- 
 
 ed, and the precipitate had fubllded, more lirae water 
 was added, by iiicceffive pints, as long as it caufcd any 
 precipitation. For it wns deemed titter that the preci- 
 pitation (hould not be pcrfefted, than that an excefs of 
 lijTie-water fhould be ufed;^the earthy pellicle of the ex- 
 ceffive lime-water being apt to mix with the precipitate. 
 The clear liquor being poured away, the precipitate 
 was poured off, and waflied into a filter. 
 
 When the filine liquor had drained from it, two oun- 
 ces of diflilled water were poured on the magma ; and 
 when this water had palTed, fredi portions were fuccef- 
 lively added and palTcd, until the whole quantity of wa- 
 ter thus expended in wafhing away the nitrous calcare- 
 ous fait amounted to a quart. 
 
 The filter being then unfolded, to let the magma of 
 oxide of filver fpread on the flattened paper, it was pla- 
 ced on a chalk-ilone to accelerate the exnccation, and 
 was gradually dried in the open air; a cap of paper be- 
 ing placed loofely over it to fxcltide the duft. 
 
 When the weather fervcd, the cap was removed, to 
 expofe the ox-de to the rays of the liui ; although this 
 was not deemed neceffary ; and exfiCLation was promo- 
 ted by cutting the oxide into thin llices. When per- 
 feftly dry it weighed i oz. 4 dwts- and about one-fifth 
 of it was confidered as oxygen. 
 
 When aqua ammoniae purs of any pharmacopoeia is 
 ufed with this oxide, either in the fmall quantity wliich 
 blackens it completely, or in a greater quantity, the 
 black matter which fubfides, and which has been repre- 
 fented by fyftematic writers as the fulminating com- 
 pound, has no fuch property, any farther than may be 
 ovfing to the matter depofited from the alkaline folution 
 during the exficcation. 
 
 The alkaline liquor containing the fulminating filver 
 ought to be poured off from the infoluble powder, and 
 expofed in a (hallow veffel to the air. In confequence 
 of the exhalation, black fhining cryftals form on the 
 furface only, and foon join to form a pellicle. As this 
 pellicle adheres a little to the fides of the veffel, or 
 maintains its figure, the liquor may be poured off by a 
 gentle inclination of the veffel. 
 
 This liquor will yield another pellicle in the fame 
 way; but the third or fourth pellicle will be paler than 
 the former, and weaker in the explofion. The firft 
 pellicles, when flowly dried, explode by the touch of a 
 feather, or by their being heated to about 96°. 
 
 The quantity of water in the ordinary aqua ammonix 
 purK renders it lefs aftive in the folution of the oxide, 
 and is an impediment to the fpeedy formation and fe- 
 paration of the fulminating filver; and an experimenter 
 who has often ufed twenty grains of the oxide to pro- 
 duce fucceflive pellicles of fulminating filver, which may 
 be feparately exploded with fafety, and who has per- 
 ceived that the pellicles never explode whilft wet, if they 
 be not heated, would, in all probability, refolve on the 
 following improvement, and expofe himfelf to the uu- 
 forefeen danger of it. 
 
 Diflilled water was impregnated with as much pure 
 
 ammoniac as it could eafily retain under the ordinary 
 
 temperature of the air. A quantity of this ilrong am- 
 
 - moniacal liquor, equal in bulk to a quarter of an ounce 
 
 of water, was placed in a fmall bottle, and 24 grains of 
 
 C 674 T 
 
 F U S 
 
 the oxide of filver, ground to fine powder, wfre added. 
 The bottle, being almoft filled, was corked, to prevent 
 the formation of tiiat film which ufually appeared in 
 confequence of the exhalation of the ammoniac in other 
 experiments. 
 
 During the folution of the oxide, bubbles of the ga- 
 feous kind arofe from it, and the folution acquired a 
 blue colour. As no film appeared, the bottle was agi- 
 tated three or four tiines in the courfe of as many hours, 
 in order to promote the folution of a fmall quantity of 
 blackened oxide which remained at the bottom. The 
 experimenter confidering this as an ample provifion for 
 twenty different charges, to be exploded in different 
 circumflances, in the prefence of the fociety, intended 
 to pour off the folution into as many fmall veffels, and 
 to weigh the refiduary black powder, after allowing two 
 hours more for the folution. 
 
 On the fixth hour he took his ufual precaution of 
 wearing fpe£tacles; and obferving that a fmall quantity 
 of black powder flill remained undiffolved, and that no 
 film was yet formed at the furface, he took the bottle 
 by the neck to fliake it; knowing that it might explode 
 by the heat of his hand, if he were to grafp it, and that 
 the explofion in this circumilance might wound him 
 dangevoufly. 
 
 In the inflant of fhaking, It exploded with a report 
 that flunned him. The bottle was blown into frag- 
 ments fo fmall as to appear like glafs coarfcly powder- 
 ed. The hand which held it was impreflfed as by the 
 blow of a great hammer, and loft the fenfe of feeling 
 for fome feconds ; and about 52 fmall grains of glafs 
 were lodged, many of them deeply, in the Ikin of the 
 palm and fingers. The liquor ftained his whole drefs, 
 and every part of the fliin that it touched. Thus it 
 appeared that fulminating filver may be made which 
 will explode even when cold and wet, by the mere di- 
 flurbance of the arrangement of its parts, in the aque- 
 ous fluid. 
 
 In fubfequent experiments, privately and carefully 
 condufled, it feemed that the property of exploding in 
 the cold liquor, by mere commotion, depended on the 
 unufual quantity or poximity of the explofive molecules 
 in a given bulk of the liquor. And the flat bottoms, 
 as well as the fides, of the thick veffels of glafs or pot- 
 ters-ware, whether they flood on boards or iron plates, 
 were always beaten to fmall fragments. 
 
 This aflorded a curious inftance of the pofiible equi- 
 librium between the powers tending to retain the ca- 
 loric and thofe which effeft the expulfion of it ; and 
 experiments and confiderations of this kind feemed to 
 promife a true folution of the phenomena of Rupert's 
 drops. 
 
 FUNCTION, a term ufed in analytics for an alge- 
 braical expreffion, anyhow compounded of a certain 
 letter or quantity with other quantities or numbers ; 
 and the expreffion is faid to be a funtlion of that letter 
 or quantity. Thus a — 4*, or ax -j- 3*% 
 or 2x — a V a' — x', or x'^, or c'^, is each of them a 
 fundllon of the quantity x. 
 
 FURD-v-HucKEEcuT, in Bengal, fignifies a paper 
 of dcfcription. 
 
 FuRD-y-Sonual, paper of requeft. 
 
 FUST, in architefture, the fhaft of a column, or the 
 part comprehended between the bafe and the capital, 
 called alfo the naked.
 
 GAL 
 
 [ (^75 I 
 
 GAL 
 
 G. 
 
 Gagufdi. /^ AGUEDI, a tree peculiar to Lamalmon, in ASyT- 
 ^ » V_T liiiia, is thus defcribed by Mr Bruce. Tiie leaves 
 
 are long, and broader as they approach the end. The 
 point ii obtufe ; they are of a dead green, not unlike 
 the willow, and placed alternately one above the other 
 on the ilalk. The calyx is compofed of many broad 
 fcales lying one above the other, which operates by the 
 preffure upon one another, and keeps the calyx (liut 
 before the flower arrives at perfeftion. The flower is 
 monopetaluus, or made of one leaf; it is divided at the 
 top into four fegmeiits ; where thefe end, it is covered 
 with a tuft of down, reftinbling hair, and this is the 
 cafe at the top alfo. When tlie flower is young and 
 unripe, they are laid regularly fo as to incloie one ano- 
 ther in a circle. As they grow old and expand, they 
 ieein to lofe their regular form, and become more con- 
 
 fiifcd, till at lad, when arrived at its full perfection, Oijincd;. 
 they range tliemfelves parallel to the lips of the calyx, ' ' \i' ^ 
 and perpendicular to the (lamina, in the lame order as 
 a rofe. Tlie common receptacle of the flower is ob- 
 long, and very capacious, of a yellow colour, and co- 
 vered with fmail leaves like hair. The (lile is plain, 
 fimplc, and upright, and covered at the bottom with ii 
 tuft of down, and is below the common receptacle of 
 the flower. 
 
 Our author fays that he has obferved, in the middle 
 of a very hot day, that the flowers unbend themfclvcs 
 more, the calyx ieems to expand, and the whole flower 
 to turn itfelf towards the fun in the fame manner as 
 does the lunflower. When the branch is cut, the flower 
 dries as it were inilantaneoufly, io that it feems to con- 
 tain very little humidity. 
 
 GALVANISM. 
 
 ■Galvanifm 
 improperly 
 
 called ii/ii- 
 
 Difcovery 
 
 •f galva. 
 ■ ifm. 
 
 Dbjea of 
 \ LhU article, 
 
 GALVANISM Is the name now commonly given to 
 the influence difcovered nearly eight years ago by 
 the celebrated Galvani, profcfTor of anatomy at Bologna, 
 and which, by him and fome other authors, has been 
 called animal ele3ricily. We prefer the former name, 
 becaufe we think it by no means proved that the phe- 
 nomena difcovered by Galvani depend either upon the 
 electric fluid, or upon any law of animal lite. While 
 that is the cafe, it is furely better to diilinguifli a new 
 branch of fcience by the name of the inventor, than to 
 give it an appellation which probably may, and in our 
 opinion certainy does, lead to an erroneous theory. 
 
 M. Galvani was engaged in a fet of experiments, the 
 objeft of which was to demonflrate, if poffible, the de- 
 pendence of mufcular motion upon eleftricity. In the 
 courfe of this invefligation, he had met with feveral new 
 and ftriking appearances which were certainly eledlrical j 
 foon after which, a fortunate accident led to the difco- 
 very of the phenomena which conditute the chief fubjeft 
 of this article. The ftrong refemblance which thefe 
 bore to the eleftrical fails which he had before obfer- 
 ved, led almoft irrefillibly to the conclufion that they 
 all dejiended upon the fame caufe. This opinion he 
 immediately adopted ; and his fubfequent experiments 
 and reafonings were naturally directed to (upport it. 
 The fplehdor of his difcovery dazzled the imat^inations 
 of thofe who profecuted the enquiry; and tor fome time 
 his theory, in fo far at leafl as it attributed the whole 
 to the agency of the eleftric fluid, was fanilioned by 
 univerfal approbation. Of late, however, this opinion 
 has rather loft ground ; and there are now many philo- 
 fophers who confider the phenomena as totally uncon- 
 Hcdted with eledlricity. 
 
 We propofe, in the^yfr/? place, to enumerate the chief 
 fads which have been afcertained on the lubjeft ; we 
 fhall then enquire, whether or not the caufe of the ap- 
 pearances be the eleftric fluid ; and, ihiriHy, we fliall ex- 
 amine how far it has been proved that this caufe is ne- 
 ceflarily connedled with animal life. 
 
 Whilll Galvani was one day employed in diffefting a 
 frog, in a room where fome of his iriends were amuling 
 themfelves with ekftrical experiments, one of them ha. 
 
 ving happened to draw a fpark from the condudor at 
 the fame time that the profeflbr touched one of the 
 nerves of the animal, its whole body was inilantly Ihaken 
 by a violent convullion. Alloniflied at the phenomenon, 
 and at firft imagining that it might be owing to his ha- 
 ving wounded the nerve, he pricked it with the point 
 of his knife, to afFure himfelf whether or not this was 
 the cafe, but no motion of the frog's body was produ- 
 ced. He now touched the nerve with the inllrument 
 as at firft, and direfted a fpark to b.e taken ut the fame 
 time from the machine, on_whieh the contradions were 
 renewed. Upon a third trial, the animal remained mo- 
 tionlefs ; but obferving that he held his knife by the 
 handle, which was made of ivory, he changed it for a me- 
 tallic one, and immediately the movements took place, 
 which never was the cafe when he ufed an electric fub- 
 ftance. 
 
 After having made a great many fimilar experiments 
 with the eleflrical machine, he refolved to profecute the 
 fubjeft with atmofjjheric eledricity. With this view- 
 he raifed a conduftor on the roof of his houfe, from 
 which he brought an iron wire into his room. To this 
 he attached metal condutlors, connedled with the nerves 
 of the animals deftined to be the fubjeils of his experi- 
 ments; and to their legs he faftened wires which reach- 
 ed the floor. Thefe experiments were not confined to 
 trogs alone. Different animals, both of cold and warm 
 blood, were fubjctled to them; and in all of them con- 
 fiderable movements were excited whenever it lightned. 
 Thefe preceded thunder, and corrcfponded with its in- 
 tenfity and repetition ; and even when no lightning ap- 
 peared, tlie movements took place when any ftormy 
 cloud pafTed over the apparatus. That al! thefe appear- 
 ances were produced by the cledric fluid was obvious. 
 
 Having i'oon after this fufpended fome frogs from the 
 iron palilades which furrounded his garden, by means 
 of metallic hooks fixed in the f'pines of their backs, he 
 obferve<l tliat their mufcles coutraded frequently and 
 involuntarily as if from a fliock of eledliicity. Not 
 doubting that the contraftions depended on the electric 
 fluid, he at firft fufptdled that they were connecled 
 with changes in the Hate of the atmofpliere. He fooa 
 4 Qj2 found.
 
 676 
 
 GALVANISM. 
 
 found, however, that this was not the cafe; and having 
 varied, in many different ways, the circumllances in 
 wlilch the fi'ogo were placed, he at hngth diCcovtreJ 
 that he could produce the movements at plc.ilure by 
 touching the animals with two different metals, which, 
 at the fame time, toudied one another either immediate- 
 ly or by the intervention of iome other fubltance capa- 
 ble of conducting eleflricity. 
 
 All the experiments that have yet been made may 
 be reduced to the following, which will give thc-olher- 
 wife uninformed reader a preciie notion of the fubjert. 
 
 Lay bare about an inch of a great nerve, leading to 
 any limb or nnifcle. Let that end of the bared part 
 which is farthell from the limb be in clofe contact with 
 a bit of zinc. Touch the zinc with a bit of filver, 
 while another part of the filver touches, either the 
 naked nerve, if not dry, or, whether it be dry" or not, 
 the limb or mufcle to which it leads. Violent con- 
 tractions are produced in the limb or mufcle, but not 
 in any mufcle on the other fide of the zinc. 
 
 Or, touch the bared nerve with a piece of zinc, and 
 
 touch, with a piece of filver, either the bared nerve, or 
 
 the limb ; no convullion is obferved, till the zinc and 
 
 4 filver are alfo made to touch each other. 
 
 Has e'^pa. A faft fo new, illuftrated by many experiments and 
 
 ged much m^ch ingenious reafonincT, which Proftflbr Galvani 
 
 attention ^"°" publilhed, could not fail to attraCl the attention of 
 
 phyfiologifts all over Europe ; and the refult of a vail 
 
 number of experiments, equally cruel and furprifing, 
 
 has been from time to time laid before the public by 
 
 Valli, Fowler, Monro, Volta, Humboldt, and others. 
 
 Frogs, unhappily for themfelves, have been found the 
 moft convenient fubjefts for thefe experiments, as they 
 retain their mufcnlar irritability and fufceptlbility of the 
 galvanic influence very long. Many hours after they 
 have been decapitated, or have had their brain and 
 fpinal marrow deftroyed, ftrong convuliions can be pro- 
 duced in them by the application, of the metals. A 
 leg feparated from the body will often continue capa- 
 ble of excitement for feversl days. Nay, very diftindl 
 movements have been produced in frogs pretty far ad- 
 vanced in the procefs of putrcfaftion. Different kinds 
 of fifhes, and many other animals both of cold and 
 warm blood, have been fubjedtd to iimilar experiments, 
 and have exhibited the farre phenomena; but the warm 
 blooded animals loie their fuiceptibility of galvanifm, as 
 J of every other Itimulus, very foon after death. 
 The metals. Almoil any two metals will produce the movements; 
 but, it is beheved, the moil powerful are the following, 
 in the order in which they are here placed : i. Zinc ; 
 3. Tin ; 3. Lead; in conjundion with, 1. Gold; 2. Sil- 
 ver; 3. Molybdena; 4. Steel; 5. Copper. Upon this 
 point, however, authors are not perfectly ac;reed. 
 ^^ The procefs by which thefe fmgular phenomena are 
 
 ■produced, confifts in effefting, by the ufe of the exci- 
 ting apparatus, a mutual communication between any 
 two points of contact, more or lefs diilant from one 
 
 ■ inftitute. 
 
 another, in a fyftem of nerrous and ir.ufcular organ?. 
 The fphere of this mutual communication may be re- 
 garded as a complete circle, divided into two ])artF. g 
 That part of it which confills of the organs of the Animal ai)d 
 animal under the experiment, has been called l/je ani- excitatory 
 nidi arc ; that which is formed by the galvanic inftru- ^"■** 
 ment» has been called the excilatory arc. The latter 
 ufually confdls of more pieces than one ; of which fome 
 are named Jhiys, braces, &c. others communicalors, from 
 their refpeftive ufes. - 
 
 A very numerous train of experiments on galvanifm Esperi- 
 has been made by a committee of the Pbyfical andMathe- nientsof 
 matical Chfs of the National Inllltute of France; an d '„ L?.'!'*'" 
 as their report comprehends a valt number of the moil 
 important iaCts which are yet known on the fubjefl, 
 we (hall preient our readers with the fuhilance of it (a). 
 
 The immenfe mafs of matter which refulted from the 
 experiments of the committee, is, in their report, pre- 
 fented, not in the order in which the experiments were 
 made, but in a fort of claffiucation, by means of which 
 a more diftinft knowledge of the fubjeft is obtained at 
 one view. The fafts are arranged under thefe fix heads. 
 I/?, Refult s of the different combinations and difpofi- 
 tions of the parts of the animal arc. 2dy Account of 
 what has been obferved of the nature and the different 
 difpofitions of the excilatary arc. ^J, Circumftances not 
 entering into the conipofition of the galvanic circle, 
 which, neverthelefs, by their influence, modify, alter, 
 or entirely prevent the fucccfs of the experiments. 4M, 
 Means propofed for varying, diminifliing, or reftoring 
 the fenfibillty to galvanifm. 5//1, Attempts to compare 
 the phenomena of galvanifm with thofe of eledlricity. 
 6th, Additional experiments, performed by M. Hum- 
 boldt, in the prefence of the members of the committee; 
 which have a reference to feveral of the proofs ftated in 
 the foregoing articles. g 
 
 L To the number of twenty experiments were made On the ani. 
 on the animal arc. The firft feven of thefe were di- "'al arc. 
 refled to afcertain the relations between the nerves and 
 thofe mufclcs over which they are diilributed. In the 
 lad thirteen, the nerves vv?re cut afunder, or fubjedled 
 to ligatures ; the feftlon or ligature being always be- 
 tween the extremities of the arc. Nerves'taken from 
 different animals, or from different parts of the fame 
 animal, and joined in one and the fame arc, were among 
 the particular fubjefts of thefe experiments ; as were 
 alfo the folitary nerve, and the folitary mufcle, included 
 between the extremities of the excitatory arc. There 
 were interpofed, too, in the courfe of thele experiments, 
 portions of nerves, and of mufclcs, diilindl from thofe 
 parts. And, in fome of the experiments, the animal 
 was without the f!<in and the epidermis. 
 
 The following are inferences which have been deduced 
 from thefe experiments : 
 
 1. The animal arc nay confifl: either of nerves and j^f^fj'jj^ 
 mufclcs together, or of nerves alone, without mufcles(B). 
 
 2. Nerves are, therefore, the effential part of the a- 
 
 nimal 
 
 (a) The members of the committee were, M. M. Coulomb, Sabbat ier, Pelletan, Charles, Fourcroy, Vauquelin, 
 Guyton, alias Morveau, and Halle. M. M. Venturi, De Modene, and M. Humboldt, affifted in the experiment. 
 
 (b) We are flrongly inclined to doubt the truth of this propoiition. Dr Fowler was at firft led to think that 
 contraftions could be excited in a limb without the metals having any communication with it, except through 
 the medium of the nerve. Recollefting, however, that a very fmall quantity of raoifture ferves as a conduftor 
 of galvanifm, he fufpefted, and our opinion perfetlly coincides with his, that in every cafe where contradions 
 
 are
 
 GALVANISM. 677 
 
 nimal arc ; for the mufcles are always more gr kfs in- tion, the prefcnce of the galvanic iiifliience, are always 
 
 terftfted by the nerves ; and are, confequently, in part, thofc in wliich the Dtrves of a complete animal arc have 
 
 a nervous organ. their ultimate termination. 
 
 3. All the parts of the animal arc mud be either From this it follows, that- the mufclts affcftcd by 
 mutually continuous, or at leall contiguous to one ano- galvanifm are always thofe corrcfponding to that ex- 
 ther. But even contiguity is fufficient to enable the tremity of the arc whicii is the moft remote from the 
 galvanic phrenomena to take place. origin ot the nerves of which it is compofed. 
 
 4. The feclion or ligature of a nerve interrupts not S. When all the nerves of the animal arc originate 
 the galvanic phenomena, if the parts which are cut a- towards one of its extremities, then only thofe mufcles 
 fundcr or bound up ftill remain in clofe contiguity to which correfpond with the oppofite extremity are fuf- 
 one another. ceptible of galvanic eonvulfions. 
 
 5. No diveriity of the parts forming the animal arc, 9 When an animal arc confills of more than one 
 though thcfe be taken from dtft'erent parts of the fame fyflem of diilerent nerves, which have all their origin 
 animal, or even from dlflerent animals, will have power about the middle of the arc, then will the mufcles of 
 to impair its galvanic fufceptlbility, provided only that thefe fcveral fyftems of nerves be moved alike at both 
 thefe parts be ilill mutually contiguous. the extremities of the arc. 
 
 6. if the integrity or galvanic fulccptibility of the 10. It feems likewife to appear, froni a variety of 
 animal arc be fnfpended by the feparation of any of its thefe experiments, that the opinion of thofe is inadmif. 
 parts to fome diflance from one another, it inay be fible, who aferibe the phxnomena of galvanifm to the 
 reftored by the intcrpofitlon of fome fubitances, not of concurrence of two dlflerent and reciprocally corre- 
 an animal nature, between the divided parts. Metallic fponding Influences, one belonging to the nerve, the 
 fubflances are in particular fit for this ufe. But tlie other to the m.ufele, and who compare the relations 
 mutual contiguity of all the fubflances entering into between the nerve and the mufcle, in thefe phasnome.- 
 the conipofition of the arc muft ever be carefully pre- na, to thofe between the interior and the exterior coat- 
 ferved. Mr Humboldt difcovered that a bit of freih ing of the Lcydcn phial. 
 
 niorelle [Helvella mitra Linn.) will fupply the place of 11. It appears, lallly, that the covering of the epl- 
 
 a part of the nerve. dermis, in the entire animal body, afts as an obflacle 
 
 7. The mufcular organs which Indicate, by contrac- to the declfive difplny of the effedts of galvanifm ; and 
 
 that, 
 
 are produced in a limb without any apparent communication between the metals and the mufcles, except through 
 the medium of a nerve, the communication is in fatt completed by the moifture upon the furface of the nerve. 
 In this cafe, the animal arc may be confidered as confilling of three pieces, difpofcd In the following order ; the 
 nerve, the mufcle, and the water adhering to the inrface of the nerve. The latter, indeed, ouglit rather to 
 be confulered as a part of the excitatory arc. " When a nerve (fays Dr Fowler), which for fome time has 
 been detached from furrounding parts, Is either carefully wiped quite dry with a piece of fine muflln, or (led 
 this fliould be thought to injure its flrudure) fufTered to remain fufpended till its mollluie has evaporated, 
 no contradllons can be excited in the mufcles, to which it Is diftrlbuted, by touching It alone with any two 
 metals in contaft with each other ; but if it be again molftened with a few drops of water, contractions In- 
 ftantly take place. And, in this way, by alternately drying and moillening the nerve, contradtions may at 
 pleafure be alternately fufpended and renewed for a confiderable time. It may, Indeed, be contended, that the 
 moiflure foftened, and thus rcilored elaftlelty and free expanfion to the dried cellular membrane furrounding the 
 fibres, of which the trunk of a nerve Is compofed; and thus, by removing conilralnt, gave free play to their 
 organization. 
 
 " But from obferving, that in every other inftance where contractions are produced by the mutual contaft of 
 the metals, a condufting fubllance is interpofed between them "and the mufcles as well as between them and 
 the nerve ; I think it would be unphllofophlcal not to allow, that, in the inftance in queflion, the moilhire, ad- 
 hering to the furface of the nerve, formed that requifite communication between the metals and the mufcles." 
 We know of no accurate experiment by which it has ever been fliewn, that cr.ntracilons can be produced In a 
 linrb without a communication being ettabliflied between the metals and nerve, and again between the mufcles 
 and the metals, either dlrettly, or through fome medium capable of condudllng galvanifm. 
 
 To remove the only objedf Ion which can be made to Dr Fowler's experiment, and of which we have feen that he 
 was himfelf aware, namely, that tlie nerve while dry is incapable of performing Its funftions, we repeated it in 
 the following manner: A fmall, but vigorous and lively, .-male frog was decapitated, and the fclatic nerve being- 
 laid bare from the knee upwards, was cut through where It paffes out of the pelvis. Fifteen minutes after the 
 head was cut off, the nerve having been cautionfly feparated from the furrounding j)arts, and coated with tinfoil 
 in the ufual manner, a filver probe was apiilled to It and its coating, without any other communication with the 
 mufcles, and ftrong contradtlons took jilace in the leg. The nerve was now very carefully dried with a piece 
 of fine linen, and the probe was applied as before to the tinfoil and the nerve ; no movement whatever took 
 place. Things remaining precifely in this fituation, one end of the probe being flill in contaft with the nerve 
 and its coating, the other end was applied to the mufcles of the thigh, and the leg immediately contracted as 
 ftrongly as ever. Upon molftening the nerve, the contraftions were again produced by applying the probe to 
 the nerve and tinfoil alone. We find from this experiment, which we have fcveral times repeated with the 
 utmotl care, and with the fame refult, that the dry nerve retained its functions completely. This appears to us 
 perfectly decifive of the quellion.
 
 10 
 
 Evpcri. 
 lllCllt^ on 
 
 678 G A L V A 
 
 that, though from its extreme tenuity, it may not al- 
 together prevent thefe efFedls, yet it cannot but very 
 matei ially dlminifli them. 
 
 II. The Excitatory /ire is ufually formed of three 
 different pieces, made of different metals. Of thefe, 
 the cxcita- one mud be in contaft with the nerve ; the other mull 
 tory arc. touch the muiclc ; and the tiu'vd mull form the mean 
 of communication between thefe two. This arrange- 
 ment, though not indifpenfably neceffary, is at leaft the 
 ■moft convenient. 
 
 In refpcdl to the excitatory arc, the committee exa- 
 TTiined, ift, The application of metallic fubftances to 
 form it : in refpeft to which they endeavoured to af- 
 certain the number and the diverfity of the pieces of 
 jnetal of which this arc may be compofed ; the metal- 
 lic mixtures or alloys which are capable of being em- 
 ployed for this ufe ; the particular degree of the fric- 
 tion of one metal upon another, which is favourable to 
 the exhibition of the phenomena ; the different ftales, 
 in refpeft to galvanifm, of metals differently minerali- 
 zed. 2dly, The effefts of the ule of carbonic fubftan- 
 ces in forming the excitatory arc. jdly, The effcCls 
 in the fame formation, of bodies, which are either non- 
 conduftors, or elfe very imperfeft conduflors of elec- 
 tricity, fuch as jet, afphaltus, fulphur, arhber, fealing- 
 wax, diamond, &c. 4thly, The conlequences of the 
 interpofition of water, and of fubftances moiilened with 
 water, between the diffeient parts of the excitatory 
 arc. In forming their excitatory arcs, too, they made 
 themfelves the chord of the arc ; they introduced into 
 it animal fubftances which had loft their vitality ; they 
 rubbed the fuppoiters with the dry fingers, fo as to 
 nark them with nothing but the traces of the perfpi- 
 ration from the flcin. They made, likewife, fome ex- 
 periments for the purpofe of afcertaiin'ng the relations 
 between, on the one hand, the extent and magnitude 
 of the furfaces of the parts compofing the arc,' and, on 
 the other, the eftetls produced by its energy. From 
 
 N I S M. 
 
 their experiments they have alfo drawn fome inferences 
 concerning the relative efficiencies of the feveral con- 
 ftitucnt parts of the exciting arc. It is impolhble for 
 us here to rcl.ite in detail all this train of experiments. 
 The following corollaries exprefs the fubllance of thofc 
 general truths, which their authors were led to infer 
 from them. j, 
 
 1. The excitatoi-y arc poffeffes the greateft power of Infercncej, 
 galvanifm, when it is compofed of at leaft three diftinit 
 
 pieces ; each of a peculiar nature : the metals, water, 
 and huinid fubftances, carbonaceous matters, and ani- 
 mal fubftances, ftripped of the epidermis, being the 
 only materials out of which thefe pieces may be form- 
 ed. 
 
 2. Neverthelefs the excitatory arc appears to be not 
 deftitute of exciting energy, even when it confifts but 
 of one piece or of feveral pieces, all of one proper fub- 
 ftance (c). In general it muft be owned, identity of 
 nature in the conftituent pieces, and particularly in the 
 fupports forming the extremities of the arc, diminifhes, 
 in a very feniible manner, its galvanic energy. 
 
 3. The Highteft diffeience of nature induced upon 
 the parts, whether by any feeble alloy, or by fritlion 
 with extraneous fubftances, is at any time fufficient to 
 communicate to the excitatory arc that full power iii 
 which the identity of its compofition may have made 
 it defedtive. 
 
 4. As the animal arc is fufceptible of being in part - 
 made up of metallic fubftances, or fuch others as are 
 adapted to enter into the compofition of the excitatory 
 arc ; fo, on the other hand, the excitatory arc admits 
 of being in part formed of thofe fubftances which are 
 the proper components ot the animal arc. 
 
 5. The energies of both the excitatory and the ani- 
 mal arcs are alike fufpended by the feparation of their 
 component parts, or at leaft by the feparation of thefe 
 parts to a certain dlftance. 
 
 6. Even the fmalleil degree of moifture is fufficient 
 
 to 
 
 (c) We do not think it has ever been proved, that one piece of metal, or feveral pieces of the fame metal, 
 are capable of forming the excitatory arc. It is admitted on all hands, that the flighteft alloy communicates 
 ' galvanic energy to a piece of metal ; that is, renders it capable of forming the excitatory arc. It is alfo known, 
 that the metallic oxides are much lefs perfeft conductors of galvanifm than their correfponding reguli, to make 
 ufe of an antiquated expreffion. It appears to us, that in all cafes where one metal appears to act, more efpeci- 
 ally where frittion with the fingers, or breathing on a piece of metal formerly inert, give it galvanic powers ; in 
 all thefe cafes, we think it probable that a flight degree- of oxidation, produced in fome part of the furface of 
 the metal, gives it aftivity by deftroying the homogeneity of its nature. We do not find that this circumftance 
 has been in general fuificiently attended to. Dr Wells having difcovcred that charcoal afls powerfully as an 
 exciter when applied along with a metal, found that by friftion it alfo can be rendered capable of afting fing-y. 
 What change is thus produced in it we can only conjecture ; but that it is fomething which deftroys the iden- 
 tity of its ftrufture, rendering it in fome meafure a heterogeneous fubftance, muft be admitted. 
 
 Candour forces us to acknowledge, that in one of Mr Humboldt's experiments, it feenis very difficult to point 
 out any want of homogeneity in the exciting arc. He put into a china cup fome mercury exaitly purified ; 
 he placed the whole near a warm ftove, in order that the entire mafs might affume an equal temperature : the 
 furface was clear without the appeaiance of oxidation, humidity, or duft. A thigh of a frog, prepared in fuch 
 a manner that a crural nerve and a bundle of mufcular fibres of the fame length hung down feparately, was 
 fufpended by two filken threads above the mercury. When the nerve alone touched the furface of the metal, 
 no irritation was manifefted ; but as foon as the mu-fcular bundle and the nerve touched the mercury together, 
 they i'cU into convulfions fo briik, that the flcin was extended as in an attack of tetanus. This is by far the 
 jnoft decifive experiment which has been tried on the fame fide of the queftion ; but as it muft be admitted, tliat 
 in raoft cafes two metals arc abloluttly neceffary, and that a fingle metal often derives aflivity from circum- 
 flances fo ilight, that we could not a priori have expefted that they were capable of producing any change ; we 
 feel ourfelves compelled to conclude, that in M. Humboldt's experiment fome iimilar very flight circumftance 
 had efcapcd unoblerved ; perhaps fome gilding, or ornaments with metallic colours, in a ftate of oxidation.
 
 II 
 Ejperi- 
 nientB rela- 
 ling to cir- 
 
 cuniftaDces 
 different 
 from the 
 ires. 
 
 GALVANISM. SjCf 
 
 to join the parts of the excitatory arc, and to deter- mencement of the mutual contacft, or of its cefTition. 
 
 mine their effefts upon the animal arc. But when the frog is fatigued, the cfFefls are diffe- 
 
 7. The influence upon the Hate of the atmofphere, rent. Thcfe fucceffive experiments hkewile affedl the 
 and of furronnding circumftances, upon the fuccefs of rcfults of one another, by means even of tlieir fiicctf- 
 the experiments of galvanilm, is, confequcntly, very finn folely. And they are alfo natui.illy fubjecft to be 
 great. In order, therefore, to perform thcfe experi- influenced by the nature of the media anildil which 
 ments with due accuracy, the Hate of the hygrometer, they are performed ; fuch as common air, water, an e- 
 and of other meteorological inftruments, muil be vigi- leftrical atmofphere. The following arc the inferences 
 lantly infpefted during their progrefs ; and the influence which have been deduced from this clafs of thefe expe- 
 
 'of the perfons making the experiment upon the fphcrc viments. 
 
 within which it is made, mull likewife be carefully at- 1. In many cafes the galvanic energy is excited by Irifercncej, 
 
 tended to. excrcife, is exhaufted by continued motion, is renova- 
 
 8. The experiments which were made to afcertain ted by reft. 
 
 the nature of the animal arc, together with thofe made 2. The multiplicity of the caufes by which the ex- 
 
 upon the excitatory arc, with a view to the comparifon pcriments of galvanifm are liable to be influenced to 
 
 of the effefls of the flefh of animals, with or without fuccefs or failure, is fo great, that we cannot, as yet, 
 
 the epidermis, and of the different effefls of this epi- be too cautious in either rejefling or believing thefe ac- 
 
 dermis, when it is wet and when it is dry, appear to counts which we hear of the fuccefs of any fuch cxpe- 
 
 fuggeft to us, that the epidermis is one of thofe fub- riments ; unlets when we are able accurately to aiipre- 
 
 ftances which diminifh or interrupt the efficacy of the ciate all the influencing circumftances. 
 
 excitatory arc. The epidermis is, as well as the hairs 3. This is remarkably confirmed by a faft, which 
 
 and bridles of animal bodies, among the number of the committee have related in their paper, and which 
 
 thofe lubilances which deferve the appellation of idlo- refpefls the continuation of the galvanic fpafm. 
 
 eleilrics. The communicator being fupported by the hand, 
 
 9. Examine the fubftances which are fit for the forma- and reding, feemingly, without change of pofition, dill 
 tion of the excitatoryarc, and you will find that the great- upon the fame point of contaft, there is known to take 
 er part of thofe which have been fuccefsfully put to this place a real change in the galvanic contaft, although 
 ufe are fubdances capable of afting as conduftors of the the communicator have remained thus apparently mo- 
 eledlrical fluid ; but that the fubdances which interrupt tionlefs. 
 
 the operation of galvanifm are generally fuch as are well From this. It may be farther inferred, that the fmal- 
 
 known alfo to redd the tranfmiffion of eleiSricity. left poflible change in the relative fituations of the 
 
 10. Laftly, it appears, that the galvanic energy de- parts of the galvanic circle and the excitatory arc, is 
 pends, not only upon the nature and arrangement of capable ot producing an effeft upon t'le fufceptible a- 
 the component parts of the excitatory arc, but on their nimal, and of occafioning miftakes in regard to the fuc- 
 extent too, and on the magnitudes of their tranfmitting eels of the experiment, if the utmod care be not ta- 
 furfaces. ken to notice and eftiraate every variation that can hap- 
 
 III. The committee appear to have ufed no lefs pen. 
 
 care and difcernment in experiments upon thofe cir- 4. The truth of the foregoing propofition is farther 
 
 cumdances which, though different from the ftrufture confirmed by the experiments upon the manner in 
 
 of the galvanic circle and its two conftituent arcs, have, which the galvanic movements are affeCied by the ad- 
 
 however, a dec'ifive injluence upon the exhibition of the vancing or the withdrawing of the communicator. For 
 
 phitnometia of galvanifm. Some curious obfervations thefe experiments fully evince the necellity for the moft 
 
 were made on the differences in the ftate of the parts vigilant obfervation of every movement in the procels of 
 
 expofed to the galvanic aftion. It was afcertained, an experiment, not only colleClively, but in their fuc- 
 
 that frogs frefh from the ditches did by no means ex- ceffion, and at the different periods of the operation, 
 
 hibit the fame phaenomena as thofe which had been 5. It fhould feem that there are, in the formation of 
 
 during fome days preferved in the houfe ; nor did the the excitatory arc, independently of its modes of ading 
 
 limbs of animals, when recently dripped ot the flcin, in the galvanic nperdtions, certain enervating, and ccr- 
 
 prefent the fame appearances as after they liad been tain exciting difpofitions ; of v/liich fome not only 
 
 fubjefted to a variety of galvanic experiments ; nor augment or diminifh the energy in the prcfcnt indance, 
 
 were the fame effefts to be produced upon the parts of but, befides, difpofe the animal to a greater or a fmaller 
 
 animal bodies which, after a certain number of trials, fufceptibility, under fubftquent experiments. 
 
 had been left for a while at red, and then taken up a- 6. In order to accuracy of experiment, and to tiic 
 
 gain, as upon thofe which had been fubje6ted to one correft afcertaining of the effefts of an experiment, it 
 
 continued train of experiments. The committee next is of great importance to know the precife ilate of the 
 
 examined the variations in the fuccefs of the experi- animal, the manner in which it has been preferved and 
 
 ments upon a drong lively frog, which may be pro- fuftained to the j)refent moment, the ftate of the at- 
 
 duced by varying the mode in which the communicator mofphere, particularly as it is indicated by the hygro- 
 
 iis carried from the one/(/^j5ortfr to the other : when the meter, by the barometer, the thermometer, and t!ie 
 
 communicator is brought into contaft with the fup- elcftrometer. 
 
 porter, or is withdrawn from aflual contaft with it ; 7. It were to be wifhed, that in making a ftatement 
 
 ■when the communicator is brought flowly, or when it is of experiments of different forts, thefe fhould be ar- 
 
 brought rapidly, into contaft with ihe fuJ>J>orter ; the ranged in the order of their efficacy, and that there 
 
 tffcfts are nearly the fame : and a fmart convulfion is, might thus be formed a galvanic fcale, which dioulj 
 
 in all thefe cafes, produced at. tke moment of the com- help us to determine the precilV degree of the galvanic 
 
 fufceptibilitJ^
 
 68o 
 
 GALVANISM. 
 
 fufceptibility of any animal in this or that prticular 3. One of the moft remarkable cimngtfii not confintnl 
 
 ftate or pofition, fhould dirc<5l us in fiibjefting every to the organs of rcfpirdt ion, confulB in the alterations 
 
 fiieh animal only to experiments fiiitable to its particu- protluci-cl on the galvanic fufceptibility. In that re- 
 
 lar fufceptibility ; fiiould enable us to eftimate, from fpedt the various cafes of aiphyxla Jiifer greatly one 
 
 the efficacy or mejfficacy of our experiments, the galvanic from another. 
 
 value of the circuniftances in which we every day find 4. The Hate of tlie irritability of the mufcles, when 
 
 ourfelves, and fliuukl enable us to judge when the fuc- examined by means of bodies, the miclianic.il aiftion of 
 
 14 
 Enperi- 
 
 n^ents on 
 the galva- 
 nic fufcep- 
 tibility of 
 animal bo" 
 (lies, &c. 
 
 15 
 
 Refledioni 
 
 cefs or mifcarriage of an experiment can afford room 
 for certain conclufions abfolutely negative or affirma 
 tive. 
 
 IV. In their experiments upon the means of -varying, 
 dimini/hirig, and renewing the fufceptibility of animal bo- 
 dies to the influence of galvanifm, the committee exa- 
 
 which caules the mufcles to contra<-\ by irritating them, 
 is far from always correfponding to tlie ftate of their 
 galvanic fufceptibility. 
 
 5. Laflly, the caufes of fuffocalion or afphyxia, do 
 not adt upon all parts of the mufcular fyllem in the 
 fame manner ; but the heart is very often found in a 
 mined, ift, the influence of eledtricity upon that fuf- ftate extremely different from that of the other mufcles. i5 
 ceptibillty ; 2d, the effeffs of the mufcular organs, and V. The comparifon Lciiveen the phenomena of gal'va-(^"'^P"i- 
 
 of certain liquors, luch as alcohol, the oxygenated mu- nifin and ihof of cLaricily is perhaps one of the moft '?' "'^ '''* 
 riatic acid, the fohitions of potafli and opium, upon the intercfling olijedls of attention ill tiie whule body of,,fj,alva '^* 
 galvanic properties ; 3d, and at the medical fchool of animal phyfiology. It is well known that Galvani was nilm with 
 Paris they made a number of experiments, in order to accidentally led to his difcovery by obferving the mo- ''"'fi^ "f '- 
 afcertain what new modifications the galvanic energy tions of feme frogs, at a certain diftance from an elcc-'' "y* 
 xiadergoes in various cafes of fufTocation or afphyxia. trical machine dilcharging fparks. The committee frona 
 Thefe laft-mentioned experiments were made upon hot- the inftitute made, therefore, fome attempts to afcer- 
 blooded animals, of which fome were reduced into the tain the relations between electricity and galvanifm. 
 ftate of afphyxia by fubmerfion, fome by ftrangulation. Having firfl paid due attention to tfie fufceptibility of 
 fome by the attion of gafes, while others were killed animals toward the influence of eleftricity, they then 
 in vacuo by the dileharge of the eleftric fpark. In that fought to difcover to what precife degree animals di- 
 fuffocation which was produced by fulphurated hydro- vetted of the natural covering of the epidermis were 
 genous gas, by carbonic vapours, and by fubmerfion, in liable to be affetled by the variations of the electrical 
 which the animal was fufpended by the hinder feet, the fluid in the atmofphere around them. Next, comparing 
 galvanic fufceptibility was entirely deftroyed. The gal- the fufceptibility of electricity with the fufceptibihty 
 vanic fufceptibility was only fufpended by fuRocatlon of galvanifm, they perceived that quantities of the elec- 
 produced by the pure carbonic acid confined under trical fluid, fuch as are flill capable of being very accu- 
 mercury. It was diminifhed. but not deftroyed, in rately meafured by the electrometer, are, however, of- 
 thofe cafes of fuffocation, which were occafioned by ten too weak to aiit upon a frog that retains the inoll 
 fulphurated hydrogenous gas that )iad loft a portion of perfect fentlbility to all the energy of galvanifm. The 
 its fulphur, by gas ammoniac, gas azote, or fuch gafes members of the committee purpofe to profecute farther 
 as had been exhaufled of their pure air by refpiratioii ; their experiments upon this part of the fubjcCt. ,, 
 
 and the fame thing was found to take place in animals VI. The following are the general refults of the ex-Refiilt> of 
 which had perifhed by total fubmerfion. But the gal- perimenls made by M. Humboldt in the prefence off'"'" ^"P"- 
 vanic fufceptibility furvived unaltered in fuftocatioiis the committee : ^'"Th'irt 
 
 brought on by fubmerfion in mercury, by pure livdro- i. There is nc truth in the affertion of certain phy- 
 
 genous gas, by carbonated hydrogenous gas, by oxy- fiologifts, that the experiments of galvanifm fail when 
 genated muriatic acid, by fulphureous acid ; as alfo tried upon the lieart and thofc other mufcles of which 
 when the fuffocation was occafioned by ftrangulation, the contractions depend not upon volition ; for thefe 
 by the abftraClion of the air in the air-pump, or by organs have been found to be actually fubjeC^ to the 
 difcharges from an electrical battery. The refults of influence of galvanifm (d). 
 
 the experiments at the medical fchool fuggefled the 2. The elfcCts of galvanifm are liable to be inter- 
 
 following reflections : rupted by the conflriction of a nerve, whenever both 
 
 I. Though it be true that all cafes of fuffocation re- the nerve and the conlfriiting ligature are enveloped in 
 femble one another in the privation of refpirable air, the flefh of the animal body (t). 
 
 and in the fufpenfion of the functions of rcfpiration, :^. The powers of the exciting arc may be renova- 
 
 and of the circulation of the blood ; yet, in their other ted or deftroyed, even though its iupporters remain the 
 circumftances, they are fubjeCt to great differences, a- fame, and although the extremities of the arc be un- 
 changed. Only the relations of the intermediate mat- 
 ters require to be altered. 
 
 4. There are atmofpheres of galvanifm. 
 
 5. There are fubltances which, though in an emi- 
 nent manner conductors of electricity, yet interrupt the 
 
 rifing from diverfity of nature in the fubftances by 
 which they are occafioned. 
 
 2. Of thefe caufes, fome appear to adt with a more 
 thorough efficacy, penetrating at once all parts of the 
 nervous and nmfcular fy items. Others again feein to 
 
 aft but fuperficially, producing only pulmonary af- motions of galvanifm. 
 phyxia, with its immediate efteCts. M. Humboldt had performed alfo other experiments 
 
 which. 
 
 (d) This was demonftrated fix years ago by Dr Fowler. 
 
 (e) Dr Valli made this obfervation foon after the difcovery of galvanifm.
 
 GALVANISM. 
 
 68t 
 
 which, when he ntteniptccl to repeat them before the 
 committee, couhi not be brought to iuccecd, on ac- 
 count, as was fuppofed, of the feafon of the yeiir. 
 
 Such are the principal rcfults of this valuable train 
 of experiments upon galvanifm. From them our read- 
 ers will perceive that this interelling lubjeil is Hill ve- 
 ry imperfeilly underllood, and will form fume idea of 
 the importance of the difcoveries whicli a diligent pro- 
 fccution of it promilcs to the philofophcr and the phy- 
 fician. 
 
 The efFefts of galvanifm upon fome of the organs of 
 fenfe are no lefs Ihlkiug than thole which we have feen 
 it capable of producing upon the mufcles. 
 
 If the upper and under furfaces of the tongue be 
 coated with two different metals, and theie be brought 
 into contadt with each other, a peculiar feufation, re- 
 fcmbliug talle, is produced in the tongue the moment 
 that the metals toucii each other. With the greater 
 number of metals this fenfation is fcarccly perceptible ; 
 but with zinc and gold, zinc and filver, or zinc and 
 niolybdena, it is very ftrong and difagreeable. Dr 
 Fowler thinks it is flrongell with /.inc and gold ; to us 
 I'l app'-'ars a good deal llronger with zinc and filver. It 
 is feiifibly (Ironger when the zinc is applied to the up- 
 per, and the filver to the under furface of the tongue, 
 than when this order is inverted. 'I'he fenfation is moft 
 diftindt when the tongue is of the ordinary temperature, 
 and the metals of the fame temperature with the tongue. 
 Any confiderable increafe or diminution of heat in ei- 
 ther greatly lefTens the effect. Mr Subfir of Berlin, in 
 Iiis Theorii des Plaijers, p. 155, (publiihed in 1767) 
 takes notice of the difagreeable lafte produced by fil- 
 ver and lead in contaft upon the tongue. This is the 
 firil inllance of galvanifm that had been made public. 
 
 To enfure complete fuccefs to the experiment, the 
 metals ought to be allowed to remain fome time in con- 
 taft with the tongue before they are made to touch 
 each other, that the tafte of the metals themfelves may 
 not be confounded with the fenfation produced by thcir 
 mere contafl. Whatever has a tendency to blunt the 
 fenfibility of the tongue, as opium, alcohol, acids, and 
 the like, diminilhes the cffeA of the metals. 
 
 It is difficult to defciihe the fenfation thus produced 
 accurately. It has been called fuhacid ; but we think 
 it more nearly refemViles the effcft produced by allow- 
 ing a grain or two of nitre to lie upon the tongue for 
 fome time, than any other tafte with which we are ac- 
 quainted. Joined to this, there is evidently a metallic 
 tafte, which varies with the metal employed ; but we 
 are inclined to confider this as the ordinary effedl of 
 the metals upon the tongue, which cannot be perfectly 
 diftinguiihed from that occafioned by their mutual con- 
 taft. 
 
 This tafte can alfo he produced by applying one of 
 the metals to the tongue, and the other to any part of 
 the Schneiderian membrane. Profeffor Robifon has 
 made many experiments of this kind, the refult of which 
 is contained in a letter to Dr Fowler. " I find (fays 
 he), that if a piece of zinc be applied to the tongue, 
 and be in contaft with a piece of filver which touches 
 any part of the lining of the mouth, noftrils, tar, ure- 
 thra, or anus, the fenfation refembling tafte is felt on 
 the tongue. If the experiment be inverted, by apply- 
 ing the filver to the tongue, the irritation produced by 
 the zinc is not fenfible, except in the mouth and tlie 
 
 SupPL. Vol. I. Part II. 
 
 urethra, and is very (light. 1 find the irritation by 
 the zinc ftrongcft when the contaft is very flight, and 
 confined to a narrow fpace, and when the contaft of 
 the filver is very extcnfive, as when the tongue is a|)- 
 plledto the cavity of a filver fpoon. When the zinc 
 touches in an exlenfive furface, the irritation produced 
 by a narrow contaft of the filver is very dilliuft, eipe- 
 cially on the upper fide of the tongue, and along its 
 margin. This irritation feems to be mere pungency, 
 without nnv lefemblanee to tafte, and it leaves a lafting 
 imprcdlon lil.e that n<ade by cauftic alkali. 
 
 " When a rod of ziuc, and one of filver, are applied 
 to the roof of the mouth, as far back as pofiible, the ir- 
 ritations produced by bringing their outer ends into 
 contaft are very llrong, and that by the zinc refemblcs 
 tafte in the fame nianueras when applied to the tongue." 
 
 M. Vulta found, that when a tin cup, filled with an 
 alkaline liquor, is held in one or both hands previoufly 
 moiftened with water, if the point of the tongue is dip- 
 ped in the liquor, an acid tafte is perceived. This is 
 at firft dillinft and pretty ftrong, but gradually yields 
 to the alkaline tafte of the liquor. Tiie acid tafte is 
 ftill more remarkable, when, inllead of an alkaline li- 
 quor, an inlipid mucilage is made ule of. The fame 
 philofopher found, that when 3 cup made of tin, or, 
 what is better, of zinc, was filled with water, and pla- 
 ced upon a filver fupport, if the point of the tongue 
 was applied to the water, it was found quite infipid, 
 till he laid hold of the filver fupport, with the hand 
 well moiftened, when a very diftinft and very ftrong 
 acid tafte was immediately perceived. 
 
 If one of the tnetals be applied to the tongue, and 
 the other to the ball of the eye, a pale luminous flafii 
 is perceived when they are brought into contaft with 
 each other, and the fenfation refembling tafte is at the 
 fame time produced in the tongue. A flalh is, in like 
 manner, produced when one ot the metals is applied to 
 the eye, and the other to any part of the palate, fauces, 
 or infide of the cheek. This experiment requires a 
 good deal of attention in the performance ; care muft 
 be taken not to prefs the piece of metal againft the ball 
 of the eye, left a flafh ftiould be produced by the mere . 
 mechanical preffure. It fliuuld be cautioufly introdu- 
 ced between the eye-lirls, till it juft touch any part of 
 the ball; and it lliould be allowed to remain in that fi- 
 tuation for fome time before it is brought into contaft 
 with the other piece of irxtal, that the paits may be fo 
 far accuftomed to it as to admit of the lenfations pro- 
 duced being properly attended to. The experiment fuc- 
 ceeds very well with tin and filver ; but the flafii is more 
 bright when zinc and gold are ufed. The piece of 
 metal which is applied to the ball of the eye muft be 
 finely pohlhed, otherwife the mechanical irritation is 
 fometimes fo great as to prevent the flafii from being 
 perceived. Dr Robifon has obferved, that the bn'ght- 
 nefs of the llaffi correfponds with the extent of contaft 
 of the metal with the tongue, palate, fauces, or cheek. 
 
 If a piece of one of the metals be placed as high up 
 as poffible between the gums and the upper lip, and 
 the other in a fimilar fituation with refpeC^ to the un- 
 der lip, a very vivid flafti of light is obferved at the 
 moment that they are brought into contaft, and ano- 
 ther at the inftant of their feparation. While they re- 
 main in contaft, no flafti is obferved. 
 
 When a rod of filver is thruft as far as poffible up 
 4 R one
 
 682 GALVANISM. 
 
 one of the noftrils, and llien brought into contaift with tation would produce, might not be altributtj to the 
 
 a piece of zinc placed upon the tongue, a very ftrong idiofyncrilis of the veflels. This painful operation was 
 
 flarti of light is produced in the correfponding eye at fcarcely commenced on the wound, by the application 
 
 the inllant of contaft. We have fometimes imagined of zinc and lilver, before the ferous humour was dif- 
 
 that the flafh in this experiment was produced before charged in abundance ; its colour became vifiLly dark 
 
 the metals aftually touciicd ; but in this we may have in a tew feconds, and left on the parts of the Mix where 
 
 been deceived. it palfed traces of a brown inflamed red. This humour 
 
 The following cuiions experiment was firll made by having defcendcd towards the pit of the llomacli, and 
 
 Profelfor Robifon : " Put a plate ot zinc into one cheek, ftopped there, caufed a rednels of more tlun an inch 
 
 and a plate of filver (a crown piece) into the other, in fnrfacc. Tiic humour, when traced along the epi- 
 
 at a little dillance from each other. Apply the cheeks dernu's, left llains, which, after having been walhed, ap- 
 
 to them as extenfively as poffible. Thrult in a rod of peared of a bluidi red. Tlie iullamed places having 
 
 zinc between the zinc and the cheek, and a rod of fil- been imprudently vvaflied witli cold water, increafed fo 
 
 ver between the filver and the other cheek. Bring much in coluur and extent, that M. Humboldt, as well 
 
 their outer ends flowly into contadl, and a fmart con- as his phjlician Dr Schalleru, who allifted at thefe ex- 
 
 vulllve twitch will be felt in the parts of the gums fitu- periments, entertained fome apprehenhon for the confe- 
 
 ated between them, accompanied by bright flafhes in quences. 
 
 the eyes. And thefe will be dilllnftl; perceived before Having now taken notice of the principal fadls that 
 
 contaft, and a fecond time on feparating the ends of are hitherto known in galvanifm, we proceed to confi- 
 
 the rods, or when they have again attained what may der fome of the leading opinions on the fubjeft. ,„ 
 
 be called the Jinking dijlance. If the rods be alternated, The firft writers upon the dilcovery of Galvani feem Pheu ime- 
 
 no effett whatever is produced." — The flaflies produ- almoft univcrfally to have taken it for granted, that the"!'"' K^'™- 
 
 • nil'iii (up- 
 
 m e- 
 
 ced in this la(l experiment are rather more vivid than phenomena depend on the eletlric fluid ; and leaving this" j^"j"P' 
 
 any which we have been able to excite by the other me- very important qucflion behind them, proceeded to ex-(uit from . 
 
 thods. The convidfive twitches are very dillinft, and plain how this fluid produces fucli effefts. The celebra-leiftricitj-j 
 
 lomewhat painful, but quite different from the fenfa- ted difcoverer of this influence himfelfconfiders a mufcle 
 
 tion .produced by an eleftric fhock. If the edges of as the perfeft prototype of a Leyden phial. When a 
 
 the tongue be allowed to touch the plates of metal in mufcle contracts upon a conneftion being formed, by 
 
 the cheeks, the fenfation refembling tafte is felt very means of one or more metals between its external fur- 
 
 ftrongly ; but this does not in the leail impair the o- face and the nerve which penetrates it, M. Galvani 
 
 ther effedls of the experiment. contends, that, previoufly to this effcft, the inner and 
 
 No method has yet, we believe, been difcovered of outer parts of the mufcle contain different quantities of 
 
 applying the galvanic influence fo as to alTedl the fenfes the eleAric fluid ; that the nerve is confequently in the 
 
 of fmelling or hearing. We have tried many experi- fame Rate, with refpedl to that fluid, as the internal fub- 
 
 ments with this view, chiefly on the organs of fmelling, ftance of the mufcle ; and that, upon the application of 
 
 but hitherto without any fuccefs (f). Neither has the one or more metals between its outer furface and the 
 
 fenfe of touch been aff"eftcd by it, unlefs, indeed, the nerve, an cleftrical difcharge takes place, which is the 
 
 following experiment be confidered in that view : Let caufe of the contradioT* of the mufcle. Thus the nerve 
 
 a fmall portion of the cuticle be removed from any part is fuppofed to perform the oflice of the wire connefted 
 
 of the body by a (harp knife, and carry tlie inciflou to with the internal furface of the phial; and the excita- 
 
 fuch a depth that the blood (hall jufl begin to ooze tory arc is confidered merely as a condudlor. 
 from the cutis vera. Let a piece of zinc be applied This theory appears to us jufl as incapable of ex- 
 
 here, and a piece of filver to the tongue; when they are plaining the phenomena of galvanifm as it is inconfitlent 
 
 brought into contaft, a very fmart irritation will be felt with the known laws which regulate the motions of the 
 
 at the wound. eledric fluid. We fhall not confider it minutely ; for 
 
 Some very lingular fafts of this kind have been dif- we hope it will foon appear highly probable, if not cer- 
 covered by M. Humboldt, who had the rtfolution to tain, that the eleftric fluid has no ihare in the produc- 
 make himfelf the fubjeft of many wcU-devifed experi- tion of the phenomena in queftion. If this be the cafe, 
 ments. One of the molt remarkable of thefe is the fol- all the different modifications of that theory muft of 
 lowing : He caufed two bliftering plafters lobe applied courfe fall to the ground. At prefent we (hall content 
 on the deltoid mufcle of both his own fhoulders. When onrfelvcs with adiing the following queftions : 
 the left' bliiler was opened, a liquor flowed out, which i. How is it poffible for tlie eledlric fluid to be ^on--j.|,;5'^ 
 left no other appearance on the fliin than a flight varnifli, denfcd in a mufcle, which is wholly furrounded by fub-fuion ill 
 which difappeared by walhing. The wound was after- (lances capable of conducting that fluid ? founded, 
 wards left to dry up : this precaiition was neceflary, in 2. If we fuppofe there is fome non-defcript non-con- 
 order that the acrid humour which the galvanic irri- dufting fubftance placed between the external and in- 
 ternal 
 
 (f) ProfeiTor Robifon has long ago obferved, that the flavour of a pinch of fnuff taken from a b«>x made of 
 tin-plate, which has been long in ufe, fo that the tin coating is removed in many places, is extremely difTerent 
 from that of fnuff when taken from a new box, or a box lined with tin-foil. The fame difference is obferved 
 when we rub a piece of pure tin, or of pure iron and a half worn tinned plate, with the finger. Alfo, if we 
 rub a call (leel razor, and a common table knife confiding of iron and (leel welded together. This is furely 
 owing to a caufe of the fame kind.
 
 G A L V 
 
 tenial parta of a mufcle, which may admit of the one 
 being pofitlvely, and tlie other negatively eltftrilied at 
 the fame time — how comes it to pafs that a dii'charge 
 does not take place, and a confcqiient conti-aition en- 
 fue, when am' rubllance whatever, capable of conduc- 
 ting the eleiftric fluid, is interpofed between the nerve 
 and the external lurtace of the mufele ? I'or example, 
 when the nerve and mul'cle arc laid bare, and the ani- 
 mal thrown into water; or when the nerve is cut 
 througli, and the end applied to the external furface of 
 the mnicles. 
 
 3. How does it happen, when one difeharge aftnal- 
 ly takes place, in coiiltqiienee of the application of 
 the excitatory arc, that the balance is not inllantly re- 
 It ore d? That this does not happen, appears by the 
 fame mufcle and nerve heing capalile of producing many 
 hundreds of fmiilar, and equally llrong difchargcs, with- 
 out any apparent means of the equilibrium being again 
 dillurbed. 
 
 We have never feen any anfwcrs to thefe quellions 
 which appeared to us at all fatisfaftory ; and till we 
 have feen them anfwered, we mull be excufed for dilbe- 
 lieving M. Galvani's theory. 
 
 One of the earlieil writers, and one of the moR af- 
 Cduoiis inveftigators of the phenomena of galvanifm, 
 is Dr Valli. He differs in opinion from Galvaui upon 
 feveral points ; but agrees with him in thinking eleAri- 
 city and galvanifm the fame. Let us confider the proofs 
 by which he fupports this doftrine. 
 
 " I have alfertcd (fays he), that the nervous fluid is 
 jj the fame with eleftricity, and with good reafon ; for 
 roofs Iiy " Snbflances which conduft eledlricity are conduftors 
 hich Villi likewife of the nervous fluid. 
 
 ideavtiiiis ,, S,|l,(lauces which are not condudtors of eledlricity 
 "" do not conduft the nervous fluid. 
 
 " Non-conduftlng bodies, which acquire by heat the 
 property of condufting electricity, preierve it likewife 
 for the nervous fluid. 
 
 " Cold, at a certain degree, renders water a non-con- 
 duftor of eleftricity as well as of the nervous fluid. 
 
 " Tlie velocity of the nervous fluid is, as far as we 
 can calculate, the fame with that of eleftricity. 
 
 " The obllacles which the nerves, under certain cir- 
 cumllances, oppofe to eleftricity, they prefent likewife 
 to the nervous fluid. 
 
 " Attradlion is a property of the eledlric fluid, and 
 this attraftion has been difcovered in the nervous fluid. 
 " We here fee the greatefl. analogy between thefe 
 fluids ; nay, I may even add, the chavadters of their 
 identity." 
 
 That there is a confiderable analogy between fonie 
 of the eftedls of the eledlric fluid and fome of the phe- 
 nomena of galvanifm, we readily admit ; but that " the 
 charadlers of their identity" are anywhere to be found, 
 we abfolutely deny. In the above paflage, Dr Valli 
 confiders it as certain that the nervous fluid is the caufe 
 of the phenomena difcovered by Galvani. But it has 
 never been demonftrated irrefragably, that any fuch 
 thing as a nervous fluid exifts, and dill lefs that this is 
 the fame with the influence difcovered by Galvani. 
 ; 1 That bodies are, in general, condudlors or non-con- 
 
 ! and dudlors of galvanifm, according as they are condudlors 
 I or non-condudlors of eledlricity, we believe to be true ; 
 
 but this rule is by no means without exception, as it 
 j certainly would be, if galvanifm and eleftricity were the 
 
 A N I S iVT. 
 
 fame. There is an experiment of Dr Fowler's, which 
 feems to (hew that water is a more powerful conduc- 
 tor of galvanifm than mercury ; thougli the reverie i$ 
 generally allmved as to eledtricity. 
 
 It the abdomen of a frog be filled with water, and a 
 filver probe pafled through it fo as to touch the fciatic 
 nerves, no contratlions are jjroduccd ; neither do they 
 appear when the probe is touclied above the furfnce of 
 the water with a piece of zinc. But if the zinc be ap- 
 plied to the probe at the furface of the water, contrac- 
 tions are produced as \igorous as if both tlic metals 
 touched the nerve. Here the water ferves as a con- 
 ducting medium between the net ves and the point where 
 the metals touch each other: but if the abdomen be 
 hlled with mercury iuHcad of water, no contradtions 
 are produced by applying the filver probe to the nerves, 
 and touching the probe.vvith the zinc at the furface of 
 the mercury. We do not fee how this experiment can 
 be accounted for, except by allowing that wuter is a 
 more p6werful condudlor of galvanifm than mercury. 
 
 If this experiment fliould be thought inconcKilive, we 
 have the authority of M. Humboldt, and of the comnu't- 
 tee of the National Inllitute of France, for faying that 
 there are fubllances which, though in an eminent manner 
 condudtors of cledtricity, yet interrupt the motions of 
 galvanifm. Tliis is certainly fnflicicnt to take away all 
 weight from Dr Valli's two firil reafons for conlidei ing 
 thefe two fluids as the fame, vi/. that all condudtors of 
 eledlricity are likewife condudtors of galvanifm ; and 
 that all bodies which do not condudt the former are 
 alfo non-condudtors of the latter. Thefe two aie by 
 far the molt important of his reafons ; and if they were 
 true in their full extent, they would certainly fheW a 
 very fl;riking analogy, though they would by no means 
 deferve the appellation of " charadters of identity." 
 
 As to the Dodlor's two next propofitions, which re- 
 gard the effects of heat and cold in rendeiiug bodies 
 condudtors or non-condudtors, they are, in fadt, only 
 branches of the two firft ; and as we have feen that thefe 
 are not univerfally true, we might admit that thcv are 
 corredt in this particular, without weakening our argu- 
 ment. For this reafon we fliall nut confider them mi- 
 nutely ; but we may obferve that Dr Fowler's cxperi. 
 ments fliew that boiling h ater, and water cooled down 
 to the freezing point, both conduct tin's influence as 
 well as water at the ordinary temperature of the atino- 
 fphere. If any change in the conducting power takes 
 place beyond tijefe points, it may with greater piubiibi- 
 lity be atcribcd to tiie changes of foim uhich tlie water 
 undergoes, tlian to the increafe or diminution of its 
 temperature. 
 
 We confefs ourfelves perfedtly ignorant of any data 
 upon which Dr Valli could found a calculation, the re- 
 full of which could (hew that the velocity of the ner- 
 vous fluid is the fame with that of eledlricity. Suppcjfe 
 we (hould take it into our heads to affert that the velo- 
 city of galvanifm is the fame with that of light, we ap- 
 prehend our author could not cahly demonilrate the 
 contrary. Neither, in all probability, would he confider 
 this affertion of ours as a fuificient proof that galvanilni 
 and light are the fame. 
 
 With regard to the next propofition, that " the ob- 
 ftacles which the nerves, under certain circumflances, 
 oppofe to eledlricity, they prefent likewife to the ner- 
 vous fluid ;" we may remark, that any obftacle which 
 4 R 2 deftroy* 
 
 683
 
 684 
 
 GALVANISM. 
 
 deftroys the funftions of a nerve completely, will pre- 
 vent the mufcles which are fupplied by that nerve from 
 contratling upon tlie apj)lii.';ition of any llimiiliis what- 
 ever (g). . It does not, however, by any means follow, 
 that the paffage of either the galvanic or the eletlric 
 fluid is prevented. The nervff. may ilill be very good 
 conduttors of both, though the itiufcle is deprived of all 
 power of contraftirg. That there are obllacles, how- 
 ever, which the nerves, under certain circumflanccs, pre- 
 fent to the palTage of eleftricity, but which they do 
 not under the fame circumltances prelent to galvanihn, 
 we think abundantly demonftratcd by Dr Valli's own 
 a-; experiments. 
 Inconfiftent << J have frequently obferved (fays he) that the legs, 
 with his ^f ^yhjch the nerves had been tied at a certain dillance 
 liments ' from the mufcles, did not feel the a£lion of a certain 
 quantity of artificial eleftricity, altliough they were vio- 
 lently convulfed by exciting that which was inherent 
 and peculiar to them." What then was the canfe of 
 the difference obferved in thefe cafes between the effects 
 of galvanifm and eletlncity ? Was it, that the quantity 
 or degree of tlie former exceeded that of the latter ? 
 Be it fo. 
 
 Dr Valli informs us, that in his experiments,' an elec- 
 tric charge which could flafh through a thicknefs of 
 air equal to .035 of an inch, produced no movement 
 in the leg of a frog of which the crural nerve was tied, 
 while the other leg, of which the nei-ve was left free, 
 underwent confiderable movements. 
 
 That the influence difcovered by Galvani can pafs 
 through an exceeding thin plate of air, is certain, as it 
 is tranfmitted from link to link of a chain, where no 
 confiderable force is ufed to bring the links into con- 
 taft. Dr Robiion's experiment, too, in which the 
 flaflies of light are dillindtly obferved before the rods 
 of filver and zinc touch each other, is another proof of 
 the fame faft ; and, if we be not deceived, the fame 
 thing takes place when a rod of fdver thruft up the 
 noftril is applied to a piece of zinc in contaft with the 
 tongue. But that it will only pafs through an exceed- 
 ing thin plate of air, any man may convince himfelf by 
 an experiment firft tried by Dr Fowler, which is eafdy 
 repeated. If a flick of fealing-wax be coated with tin- 
 foil, it will be found a very good conduftor ; but if, 
 with a (harp pen-knife, an almoil imperceptible divifion 
 be made acrofs the tinfoil, even this interruption of 
 continuity In the conduftor will be found fufficient ef- 
 feilually to bar'the paffage of galvanifm. 
 
 We find, then, that a quantity of the elefkric fluid 
 which can pafs through a plate of air of the thicknefs 
 of .0J5 of an inch, is obftrufted by a ligature upon a 
 nerve, while the galvanic influence pafies readily along 
 a nerve included in a ligature, but is obltrufted com- 
 pletely by making an almoft imperceptible divifion in 
 a good conduftor. The plate of air in this cafe fiirely 
 is not near .035 of an inch in thicknefs. It refults in- 
 contellibly, from a comparifon of tliefe two experi- 
 ments, that there is, between thefe two agents, fome 
 other difference befides the mere degree of intenfity. 
 We come now to the lafl reafou which our author 
 
 afligns for his belief that galvanifm, or, as he clioofea. 
 to call it, the nervous Jlu'id, is the fame with eleftricity. 
 It will lie found a very important one. That propertv 
 by wliich bodies charged with the eleftric fluid attrait 
 or repel other bodies, according as tiiey are in the fame 
 or the oppofite Rate of eleftricity from themfelves, is fo 
 llriking, and at tlie fame time fo univerfal, that it has 
 been very properly adopted as the meafurc of this fluid. 
 If it were true, then, that the galvanic influence pot- 
 ftffed the fame properties of attraftion and repuHion as 
 the eleftric fluid, this circumilance would certainly in- 
 creafe the ar»alogy between them very much. As we 
 have already feen, however, that they differ in other ef- 
 fential points, even if it were true that they agreed in 
 this, it could conftitute no proof of their identit)'. But 
 if, on the other hand, we fliould find that this affcr- 
 tion of our author is founded on error, and that the 
 galvanic influence pofleffes in no degree whatever thofe 
 properties of attraftion and rtpullion which have al- 
 ways been juftly confidered as eflential charafteriflics of 
 the eleftric fluid, we fliall then be fully juflitied in af- 
 ferting, that thefe two agents, however much they may 
 refemble each other in fome lefsi, important particulars, 
 arc in their nature totally diflinft and iniconnedted. 14 
 
 Let us examine the proofs by which Dr Valli's af- ^"^ ""'' 
 f.rtion is fupported. He tells us, that lie obferved the, , , 
 hairs 01 a moufe, attached to tiie nerves of trogs, by lecaricftv. 
 the tinfoil with which he furrounded them, alternately 
 attrafted and repelled by each other, whenever another 
 metal was fo applied as to excite contraftions in the 
 frogs. We are very far from meaning to infinuate that 
 Dr Valli did not fee, or think he faw, what he thus de- 
 fcribes ; but that the motion of the hairs mnfl have 
 arifen from fome caufe, diflPerent from that to which he 
 afcribed it, cannot admit of a doubt ; for haiis, in fuch 
 a flate of eleftricity as he fuppofes, never attraft, but 
 always repel each other. 
 
 Dr Fowler, who has paid particular attention to this 
 part of his fubjeft, has many times repeated this expe- 
 riment, both in the manner defcribcd by Dr Valli and 
 with every variation in the difpoiition of the hairs which 
 he could devife : but whether they were placed on the 
 metals, the nerves, or the mufcles, or upon all at the 
 fame time, he has never in any inftance been able to ob- 
 ferve them agitated in the flightefl degree. He has 
 made fimilar experiments upon a dog, and upon a large 
 and lively fl<ate, by difpoilng, in the lame way that Valli 
 did the hairs of a moufe, flakes of the finefl flax, fwan- 
 down, and gold leaf ; but although the contraftions 
 produced in the flote, by the contaft of the metals, 
 were fo flrong as to make the animal bound from the 
 table, not the leall appearance of eleftricity was indica- 
 ted. He next fufpended from a flick of glafs, fixed in 
 the ceiling of a clofe room, fome threads, five feet in 
 length, of the flax tifed in the former experiment ; and 
 brought fome frogs recently killed, and infulated upon 
 glafs, as near to them as poffible without touching ; 
 but the threads were in nowife affedlcd by the contrac- 
 tions produced in the frogs. 
 
 In a v:"ry ingenious paper upon galvanifm by Dr 
 
 Wells, 
 
 (g) We do not here mean that contraction which mufcles are fufceptible of long after death, upon having their 
 fibres mechanically irritated, which is produced by what phyfiologifts have called the vis infita, and which is per- 
 feftly known to our cooks, as it was to their predecefTors in the Roman kitchens, as the foundation of the art of 
 crimping. We at prefent confine ourfelves to contraftion produced through the medium of the nerves.
 
 «5 
 
 1 the 
 
 me full 
 
 GALVANISM 
 
 Vv'clk, wlifch is puliliditd in the London Pliilofopliical 
 
 68' 
 
 TianfaiStions for 1795, lliat gentleman maintains the 
 "opinion, that tlie influence difcovered by Galvaiii is c- 
 k'tlrical. He admits, that it is not attended witli thofe 
 appearances of attraiSion and repnllion which are held 
 to be the tells of the prefence of tkilricity ; but he 
 contends, that " neither ought li^ns of 3ttra(Sion and 
 repulfion to be in this cafe prefented on the luppofition 
 that the Inlluence is electrical ; fincc it is neceffary, for 
 the exhibition of fuch appearances, that bodies, alter be- 
 coming' eleftrical, (hould remain fo during fome fcniible 
 portion of tune; it being well known, lor example, that 
 the paOiige of the charge of a Leyden phial, from one 
 of its furfaces to the other, does not affeft the moll de- 
 licate electrometer, fufpendcd from a wire, or other lub- 
 (lance, which forms the communication between them." 
 That the charge of a I-cyden phial does not, in paf- 
 ■ fing along a wire, affcft an eleftrometer, is certain ; and 
 it is equally true, that we have no means of ap-plvingau 
 tleftrometcr to a quantity of galvanifm in a tlaie of 
 rell in a body. It this mfluence ever exilts in fuch a 
 Hate, we have no tell by which we can difcover its pre- 
 fence ; and it is only from the eftefts which it produces 
 in tranftu that we know of its cxiftence. But the elec- 
 tric fluid, in palling from hnk to link of a ciiain, feii- 
 iibly affetls an electrometer ; and in Dr Fowler's expe- 
 riment Willi the ikate, for example, as more than one 
 piece of metal is employed as an exciter, the fluid, in 
 palling from one piece to another, (hould have alfefted 
 the light fubftances which were placed upon them. 
 This appears to us a fufficient anfvver to the objeftion 
 ftarted by Dr Wells : but the fame orieftlon having 
 lieen lately made to us by a gentleman from whom we 
 (hall always receive every fiiggelbon with uncommon 
 delerence, we thought it worth while to try the follow- 
 ing experiment : 
 
 Three hours after a frog had been decapitated, it 
 fliewed llrong figns of galvanic fufceptibihty. One, of 
 the fciatic nerves being coated with tinfuil in the ufual 
 manner, the leg was laid upon a plate of zinc. A gen- 
 tleman was defired to lay hold of the nerve and its coat- 
 ing with the fingers of one hand, which had been pre- 
 vioully dipped in water, while with the other hand, alfo 
 wet, he held the end of a fmall brafs chain about two 
 inches in length. Another gentleman now took hold 
 of the other end of the chain, and, with a filver probe, 
 held in his other hand, touched the plate of zinc The 
 influence being thus made to pafs through the chain, 
 the leg contrafted vigoroufly ; but a very fenfible elec- 
 trometer, held fo near to the chain as almoll to touch 
 it, was neither attracted nor repelled. In perfornu"ng 
 thi.i experiment, it was neceffary to have the hands wet, 
 as the dry cuticle tends much to obllruiif the jjalfngc of 
 galvanifm ; but the utmoft care was taken that the i lunn 
 thonld be perfeftly dry, otherwife the influence mifht 
 have been tranfmitted by the molihire upon its furface 
 without paffing through the chain itfclf. 
 
 To avoid the polubility of this happening, the expe- 
 riment was varied in the following manner : The frog's 
 leg was laid upon a plate of zinc, and the nerve upon a 
 plate of filver. A gentleman now took a lilver probe, 
 and one end of the brafs chain in contaft with it, in 
 one hand ; and in the other hand he held the other end 
 of the chain in contaft with a rod of zinc. He now 
 touched the filver plate with the rod of filv«r, and the 
 
 zinc plate with the rod of zinc. As the influence was 
 not now to be made to pafs through liis body, there 
 was no neteflity for his hands being wet ; the whole ex- 
 citatory arc was therefore made completely dry. In 
 this way very llrong contradtlons ^erc txcited in the 
 leg, and ftill the electrometer was not affefted in the 
 InialUll degree when brought near the chain. 
 
 It is proper to oblcrve, that Dr Valli, in his affertioii 
 that attraction Is a jiroperty of galvanilm, does not rclt 
 entirely upon his own obfervation : a committee of the 
 Academy of Sciences at Paris performed the following 
 experiment along with hln: : " They placed a prepa- 
 red frog in a velicl which contained the elcftroineter of 
 M. Coulomb, charged negatively and pofitlvely by turns. 
 In both cafes, in exciting the animal in the common 
 way, the ball of the electrometer was attradud." It 
 appears to us that Dr Valli and the committee have 
 been deceived by the fridtion produced by the motion 
 of the animsls under their experiments having excited 
 fo much electricity as to affect the elcdtiximeter. The 
 firft time wc tried the exptriment abovementioned with 
 the brals chain, we were iilmoll milled by a fimllar clr- 
 cumllance. Inllead of an artificial electrometer, which 
 we happened not to have at hand, we made ufe of .1 
 very long and flender human hair ; and we found that 
 it was ftrongly attracted by the chain. Upon an at- 
 tentive examination, however, we found that this did 
 not arife from the aftlon of the influence paffing thro' 
 the chain, but from the (late of the hair itfelf, which 
 was fo highly eledlrical as to be Ibongly attraCtcd bv 
 every conducing fubllance which it approached. Upon 
 fubftitutiiig another hair, which fliewed no mark of be- 
 ing cither policively or negatively elcCliiiiLd, it was nei- 
 ther attracted nor repilled by the chain. From the a- 
 bove, or fome fimilar circumllance, it is probable (hat 
 Dr Valll's miftake has originated ; but we are confident, 
 that whoever will repeat the experiment with fufficient 
 attention, will find the rtfult prccilely as we have de- 
 fcrlbed it. 
 
 Perhaps it may ftill be fald, that although we have 
 never been able to dllcover atli action and repulfion as 
 properties of galvanifm, this mayarlfe from our not be- 
 ing able to accumulate this influence in fufficient qnan- ,_ 
 lity. To this reafoning. If reafoning it can be called, Dem.mftra. 
 
 we oppofe the following confiderations, which Hate a ''""i that 
 
 f elcClrlclty and galva- 
 irrcconcileable with the 
 
 diffiniilarlty In the phenomena of elcClrlcltv and ealva-''"^ l''^^"" 
 • - * . „ , . . .. . ; . p _ mena of 
 
 nifm, that feems' abfolutcly u rcconciieaoie wuu me ]yj,j|,j^j 
 identity of the caufe. andofelec- 
 
 Nothlng is more completely ellabllfhed in the fciencetricityre- 
 of cleftrlcity than this, th;;t all ihofe ajjpearances which 
 
 fult not 
 from the 
 
 viQ ciM allraflions, reputfions, (ihjlrud'wiis, and acfiiwuln-(^^^^^-^^f^ 
 t'lon of ehdric Jlmd, are pieclfcly fimilar to what would 
 be the appearances, if electricity were a fluid, whole 
 particles repel each other, and attract the panicles of 
 other matter, according to a certain law (See Elec- 
 tricity, SuppL). Of all thofe phenomena, the moil 
 remarkable is the accumulation of elcClric energy (to 
 give it no more definite name), by means of thin idlo- 
 eleClrics, coated with non-eleClrics ; fuch, namely, as 
 are exhibited by the Leyden phul, th',' condenfer, the 
 doubler, &c. 
 
 If the phenomena of galvanifm are produced by the 
 paffage of eleClric fluid from one extremity of the ex- 
 citatory arc to the other, this paffage will be regulated 
 by the known laws of clcClricity. It may therefore be 
 
 accumulat-ed
 
 6S6 
 
 GALVANISM. 
 
 accumulated fin trai.fttu) by means of an apparatus fi- 
 milar to the con'ted pane, or to the coiidenfer. Piofef- 
 for Robifon, with this view, made the following expe- 
 riments : 
 
 1. He made a prrt of the conduftor to his conden- 
 fei", or colleftor of atmofpheric cleftritity, conlift of a 
 long glafs rod, on one fide of which was faltcncd 
 (with varnifli) a very narrow flip of tinfoil; there was 
 a fine point at one end of this rod, and a gold leaf 
 electrometer at the other. This apparatus was in- 
 fulated at one end of a room ig feet long, having a 
 window in the middle of each fide. A fmall eledlric 
 machine was placed at the other end. On a dry day, 
 with a gentle breeze in a direftion acrofs the room, 
 both windows were opened a little way, fo that there 
 was a continual ftream of air acrofs the room. The 
 machine was worked ; and after a fhort time had elap- 
 fed, the eleftionieter began to diverge, gradually open- 
 ed, and at lall Ihuck the conducing (lips on each lide, 
 and then collapfcd, and again began to diverge. The 
 windows were fliut ; and immediately, without working 
 the machine, the eleftronietcr diverged rapidly, and 
 touched the fides of the phial every minute and half. 
 This continued fo long, that there feemed to be no end 
 to it. The Profeflcir now made a cut acrofs the tin- 
 foil with a very (harp knife ; the eleftrometer now di- 
 verged very feebly, and 7I minutes elapfed before it 
 touched the fides. He pafltd the knife a fecond time 
 through the cut. This widened it (though fcarcely 
 fenlible to the eye), becaufe the knife had been blunt- 
 ed by the glafs in the firfl operation. All divergency 
 of the eleftrometer was now at an end ; and although 
 the machine was worked till the electric imcll was ien- 
 fible at the door to a perfon who happened to come in 
 at this time, no tendency to divergence was obforved. 
 (N. B. the top of the electrometer had no conducting 
 fubllance about it, except the (lip of tinfoil). 
 
 The cut, being examined with a microfcope furnifh- 
 ed with a micrometer, was tMo'-'^ of an inch. It was 
 now filled up, by binding over it another flip of tin- 
 foil. A plate of talc, whofe tliicknefs did not exceed 
 the 900th of an inch, was coated on one fide in a circle 
 of l4- inch diameter. The electrometer was removed, 
 and the coated fide of the talc was put into clofc con- 
 tact with the flip of tinfoil on the glafs rod. A (tand 
 of tin, whofe top was a plate of i4 inch diameter, 
 fmeared over with mercury, was placed in contact with 
 the other fide of the talc, and they were preffed into 
 Very clofe and continuous contact. 
 
 The machine being now worked, the coated taic re- 
 ceived a charge in about 5 minutes fufKcient to give a 
 very fmart fliock : ar.d this was repeated with great re- 
 gularity every five or fix minutes. The windows were 
 now thrown open, and the room cleared ot its for- 
 mer contents of air, till none of thofe prelent could 
 perceive any eleftric fmell. The machine was now 
 worked again. But after half an hour, only a very 
 faint twitch was felt ; but enough to (hew that an ac- 
 
 cumulation was taking place. The windows were lur* 
 half fliut. After working the machine about five mi- 
 nutes, a faint tw itch was obtained ; after a quarter of 
 an hour more, there was a moderate (hock. 
 
 In tins (late of things, the apparatus was examined 
 as a condcni'er, by firft taking out the (harp point by 
 an infulating handle, and then removing the tin (land. 
 Examined in this way,- it appeared plainly that, even 
 when all the windows were open, the accumuLition be- 
 gan almoil as foon as the machine was worked. Nay, 
 it was found, on another day equally favourable, that 
 a plate of talc t^Jo ^'^ t&§5 of an inch thick, took a 
 charge, although a cut of ^-J^ vvide did not allow the 
 electricity to fly acrofs it. This is perfectly' fimilar to 
 all our experiments on coated gla(s. The thicknefs 
 which admits an accumulation is ahrioft incomparably 
 greater than the diftance to which a fpark will fly, or 
 a concufTion is producible, in the fame iutenfity of e- 
 IcCtricity. 
 
 2. The above defcribed apparatus was infulated, and 
 a wire connected with each end. To one wire was join- 
 ed a thin plate of lac, coated on the fide next the wire; 
 and to the other a piece of moid leather covered with 
 tin-foil. Thefe plates were rubbed together by means 
 of infulating handles. The plate of coated talc quickly 
 took a charge. 
 
 The fame plate of talc, and afterwards another plate 
 not more than half as thick, was now made part of the 
 excitatory arc, and fometimes part of the animal arc. 
 Sometimes plates of varnifli, incomparably thinner than 
 either of thefe, were employed. But all ProfefTor Ro- 
 biloii's attempt; to produce an accumulation of galvanic 
 energy in this way were fruitlefs. The fecond form of 
 the cleCtrical experiment was adopted, as having a I'onie- 
 what greater relemblance to -the ("uppol'ed procedure of 
 galvaniim; but the well-infoimed eleCtrician will eafily 
 perceive, that the firil form is far more delicate and de- 
 cilive. 
 
 The internal procedure in the elcCtric and galvanic 
 convulllons is therefore fo different, nay, oppofite, that 
 we cannot bring ourfelves to think that the appearances 
 are operations of the fame agent (h). 
 
 We have now gone over all the points of refemblance 
 which, in Dr Valli's opinion, conflitute the characters 
 of the identity of galvanifm and eleCtricity. We think 
 that, without going farther, we might fafely rtit our 
 affertion, that thefe two agents are perfectly diftinCi and 
 unconnected with each other. But there are feveral 
 other circumdances which merit attention. jg 
 
 No electrical phenomenon can take place between Far'her 
 two bodies, unlefs thefe bodies be in oppofite Hates of'^p"'"'""" 
 electricity with regard to each other. Now, how si'^'.^.^cTy*' 
 we to account for the accumulation of eleCtricity in any^^j g„lva. 
 body, or part of a body, furrouiided on all hands bynifm. 
 conducting fubflances ? The experiments of Galvani 
 fucceed equally well, \\liether the fubjeCls of them be 
 iuiulated or furrounded by conductors ; whether per- 
 formed in the drielt air or under water (i) ; whether, 
 
 by 
 
 (h) What if it were called mrta//orfa/OT, which tianflates exactly metallic irritation, or metallegerfifm, from 
 finctKKov, and tyip'^ic extkatio. 
 
 ( I ) Dr Fowler mentions an exception to this. " When the feparated leg of a frog was held under water, 
 and formed part of the circuit through which this influence had to pals in order to excite another leg, it never 
 contracted ; although it did, and llrongly, when held above the furface." In this cafe it is plain, that the frog's 
 
 leg
 
 GALVANISM. 
 
 687 
 
 by means of an cle<51rical machine, wc cbai-gi- the ani- 
 mal and the metals, till every part of tlK-m Ihongly nlfcct 
 tilt cleAromtter, or whether we revcrfc the experiment 
 and eliftrify them iiegcitively, iliU no change is produ- 
 ced in the force or frequency of the aftious excited by 
 the application of the metals. Is there any elcclrieal 
 tx])erimeiit which could continue to give the lame refult 
 i i fuch oppolite circumilances ? or is there any poflibi- 
 lity of accounting fur it confillently with the knuwii laws 
 of the clcftr.'c fluid : 
 
 The writers on this ful)jeft who adopt the elcAric 
 theory, inftcad of attempting to explain how the eleftric 
 fluid can be condcnfed in a body furrounded by con- 
 ducting fubftances, have recourfc to the analogy of the 
 gymnotus, torpedo, and other fifties of the fanif.- kind. 
 Plere, fay they, we have in faft the eiedric fluid accu- 
 mulated in fuch a fituation, and tliere is no reafouing 
 againft facts. We anfivcr, that tliefe animals arc all 
 fiirninied with organs of a very peculiar ftrudiire, which 
 may polfibly be licted for the purpofe ol fuch a con- 
 deiifation. Befidcs, we apprehend it has never been in- 
 contellibly proved that thefe fingiilar animals derive 
 their powers from the eleitric fluid. Without wiltiing 
 to enter into this qiieftion, wliich is foreign to our [ire- 
 fcnt ful)jecf, we may remark that Mr Wallh difcovend, 
 that the fhock of the torpedo would not pafs through a 
 fmall bral's chain ; a circumltance in which it differs re- 
 markably both from eleftricity and from the influence 
 difcovered by Galvaui. 
 
 It were worth while to try Profeffor Robifon's me- 
 thods of accumulation in the examination of the con- 
 vulllons occalioned by the torpedo. The Profeffor fui- 
 pefts that the popular horror at the lamprey, and the 
 accounts of cramps and pains produced by it, have their 
 fource in fonie iiniilar powers of that anijiinl. 
 
 Dr Valli's realoning on this part of the fnhjeft is 
 very curious. He takes it for granted that the gym- 
 notus owes its influence to the eledric fluid. Then, 
 though the gymnotus gives fhocks and emits fpiirks, 
 while the torpedo only gives fhocks without emitting 
 fparks, he fays it would be abfurd to affert that the tor- 
 pedo derives its influence from a caufc different from the 
 gymnotus. Again, though the influence difcovered by 
 Galvani neither gives ftiocks nor emits fparks, it would 
 ftiU be abfurd to maintain that it is not the fame as the 
 electric fluid, and as the influence of the gyirtnotus and 
 torpedo. TodifTent from any part of this very logical 
 dedu6tion, he declares would be contrary to the hm's of 
 phdofophifuig I Rifiim leneatis ? 
 
 Afraid, probably, that his readers might be tempted to 
 offend againft thefe new laws, he proceeds to llreiigtheu 
 them by the analogy of animals and vegetables retaining 
 an uniform temperature in mei/ia, warmer or colder than 
 their own bodies; from which he argues that they may 
 alio have a power of accumnlatiiig eleilricity, ai..* re- 
 
 taining it in a particular part, tiiough their whole bo- 
 dies are conductors. But the cafes are in no refpeft 
 fimilar. Neither animals nor vegetables accumulate ca- 
 loric in any particular part of their bodies in preference 
 to any other part. They have no power of rclainitig 
 caloric in their bodies more flrongly than any other 
 bodies do ; for if they are placi.d in a medium colder 
 than themiclves, they are continually imparting caloric , 
 to that medium. Neither is there the fmallcll: proof, 
 from any experiments yet piibliflied, that when placed 
 in a medium warmer than themfelves, they do not con- 
 tinually abforb caloric from it. The exillence of a fri- 
 gorific power in animals appears to us exceedingly pro- 
 blematical ; but if it were proved to exift, it would by 
 no means demonllrate that animals or vegetables have a 
 faculty of declining to ablorb caloric from bodies warmer 
 than themfelves. It is readily admitted, that animals 
 and vegetables have a power, within certain limits, of 
 jirefcrijng their teuiperature higher than that of the 
 furrounding medium ; nor is there any thing furprifing 
 in this, as the cnloric, which they are continually recei- 
 ving by the dccompofition of oxygenous gas, is dlfllpa- 
 ted flowly. But if we fhould allow that animals have 
 a flmiiar faculty of generating the electric fluid ; from 
 the nature of that fluid it mull be continually commu- 
 nicated, not only to every part of the bodies of the ani- 
 mals tbemiclves, the whole of which are condu<Elors, but 
 to every conducting fubftance contiguous to them : 
 and this mull take place, not flowly, like the difTipation 
 of caloric, but inftantaneoufly, fo as to render any fenfi- 
 ble accumulation impofTihle. ^ 
 
 Galvanifm differs from electricity in nothing more DiflVrcnce 
 remarkably than in the mode of its excitement and dif-in their 
 charsre. To pioduce the phrnomena difcovered bv Gal-". "^^ ^*' 
 vani, no operation at all limilar to the friCtion of an e- ' 
 
 lettric upon a conducting fubflancc is neceffary ( k ). 
 The nerves and mufeles have only to he laid bare, and 
 a communication formed between them by means of the 
 excitatory arc, when the contractions immediately enfue. 
 In the cafe of electricity, a fingle difcharge having re- 
 flored the equilibrium, no farther effects can be produced 
 till this has been again deftroyed by fome means capable 
 of producing a condenfation in one quarter and a com- 
 parative rarefaction in another. The faCt is very dif- 
 ferent with regard to galvanilni ; for with it the num- 
 ber of (hocks which may be given appears to be inii- 
 nitc. Nay, they frequently becon'ie llronger in propor- 
 tion as tliey have been longer continued : this influence 
 diifering extremely in this particular, too, from the elec- 
 tric fluid, which, beiides being itftlf exhaufted, never 
 fails in a remarkable manner to cxhaull the contraCtile 
 power of the mufeles. -^ 
 
 The permanence of the eftecls of galvanifm is flHlAnd inthe 
 more ftriking in the experiments upon the organ of ''"'.^''o" of- 
 talk'. Vv^ien the metals are applied to the tongue, thcr '^"^ '^" 
 
 fenfation 
 
 leg had in faCt formed no part of the circuit through which the influence pafTed ; the influence had been tranf- 
 niitted by the water in which the leg was held. 
 
 (k) It is true, as we have noticed above, that galvanic energy is fomctimes communicated to a conducting 
 fubftance by rubbing it upon fome other fubllance ; but this has no refemblance to the excitement of eleCtricity 
 by friction. The galvanic energy is communicated in this cafe to a cmJuHing fubllance, and it fucceeds as rea- 
 dily when both the bodies are of this clafs as when one of them is an idio-eleClric. But no elcCtric phenomenon 
 lias ever been produced by the friCtion of two conducting bodies upon each other ; one of them mull be an idio- 
 electric, and it is in this one that the excitement takes place.
 
 688 G A L V A 
 
 fenfation produced ia not fudden and tranfient j but fo 
 long as the metals are in contact with the tonjrue and 
 with each other, lo long decs the talle continue ; and, 
 after fome time, it becomes iiitutFerably difagreeable. 
 M. Volta, who adopts the electric theory with various 
 niodifications, feniible of the permanence of the efFeft, 
 in his curious experiments abovemeutioned fuppofes, 
 that a ftream of cledlricity pafles from the tin cup to 
 the liquor, from this to the tongue of the pei-fon making 
 the experiment, then through his body, and returns 
 through ^he water upon his hands to the cup ; and thus 
 he fuppofes the fluid to move perpetually in a circle. 
 It is laiely unlieceflary for us to obferve, that the fup- 
 pofition of a itream of eleAricity continually moving in 
 a circle in this manner, is wholly inconfiftent with the 
 laws which appear in every cafe to regulate the motions 
 of that Huid. The fame obfervation applies to the man- 
 ner in which he explains moll of the other phenomena 
 of galvanifm. 
 
 The eleftric fluid cannot be put in motion but by 
 deflroying the equilibrium to which it perpetually 
 tends ; but whenever this is deftroyed, all that is requi- 
 red to produce a dilcharge is, that a fingle condufting 
 fubllance be placed between the two points in which 
 it is unequally dillributed. _ Here again there is a very 
 wide diftintlion between this fluid and the influence 
 difcovered by Galvani. M. Volta divides all conduc- 
 tors of galvanifm into two clafles ; ill, Dry conduftors, 
 comprehending metals, pyrites, fome other minerals, 
 and charcoal ; and, 2d, Moilf conduftors. He alFerts, 
 that it is ablolutely neceflfary, in order to the produc- 
 tion of the phenomena, that two rtinduftors of the 
 firft clafs touch each other immediately on one hand, 
 while at their other extremities they touch con- 
 duftors of the fecond chifs. Whethei" this be admitted 
 or not, we have already llatt:d our opinion that the ac- 
 tion of two different lubllances is abfolutely nccef- 
 fary in order to excite contraftions : and although it is 
 contended by fome writers that a fingle piece of metal 
 has fometimes been found fufflcient, yet even they mufl 
 allow that, in by far the greater number of cafes, it has 
 been found neceflar^' to make ufe of two metals, and 
 that the efFedl is even heighened in general by em- 
 ploying three. In the whole fcience of electricity, we 
 
 N I S M. 
 
 do not know a fingle faft which bfars the flightcft a- 
 nalogy to this. Never in a lingle inllance has it been 
 found, tliat the effedts of a Leydeii phial have been in- 
 creafed by uliiig a conductor formed of two or more 
 metals in procuring the difcharge. 
 
 Before leaving the fubji-ft of corduftors, we may 
 take notice of a very curious and important faft men- 
 tioned by Dr Valli. " Amougft men," favs he, " there 
 arc fome individuals who are good conductors, others 
 who are lefs fo ; and fome again who appear to be al- 
 moft non-condu('^ors. I was one day carrying on, with 
 three of my friends, fome experiments upon frogs. A 
 frog was put in water, and we each by turn eflayed its 
 power. Two of us excited ftrong convulfions, the 
 third only feeble ones, and the fourth none at all. This 
 experiment was repeated frequently with th." fame re- 
 fult. This is not the only example I could adduce of 
 the reality of this fa<S, but 1 do not tliink it ncceffary 
 to dwell any longer upon it." We have met with one 
 individual who is not fenfil>le of any peculiar fenfation 
 wlien the metals are applied to his tongue. Thiii 
 feems in fome meafure to corroborate Dr Valli's obfer- 
 vation. It is apprehended, however, that all men are 
 equally good condutlors of eleflricity. 
 
 There is ftill another very marked dillinftion be- 
 tween the effedls of galvanifm and eleftricity. No 
 fliock at all refembling that produced by the eleftrlc- 
 fluid has ever been felt by any perfon whofe body waj 
 made a part of the chain conducing the galvanic in- 
 fluence, while a very fmall quantity of the electric fluid is 
 immediately felt (i-). In Dr Robifon's experiment with 
 the plates of zinc and filver in the cheeks, there is no 
 doubt a convuUive twitch diftinftly felt in the gums ; 
 but, as we have already obfcrved, the ItnFation thus 
 produced is qnite different from that which is felt from 
 an eleftric fiiock (m) 
 
 There is an experiment related by Dr Valli, which 
 feems to fliew that nothing like an eleclric (hock is 
 felt, even when this influence is tranfmitted through a 
 nerve, fo as to excite convulfions. Having laid bare 
 the nerves of a fowl's wing, without ciittirg them, and 
 without killing the fowl, upon applying the metais 
 very fraart movements were produced, but the animal 
 remained perfeftly tranquil. Nor was this owing to the 
 
 fowl 
 
 it 
 
 Sonic ni 
 nun-con 
 dt:<5tors ( 
 galvaaiC 
 
 (l) There is an exception to this rule which ought to be taken notice of. M. Cotugno informs us, that 
 when he was one day employed in diffefting a live moufe, he received a fenfible (hock from the animal. But 
 as neither he nor any other perfon has ever been fimilarly aflccled ?n any other inllancc, it feems pretty certain 
 that he was deceived into the belief of a fliock from the fenfation produced by the ftruggles of the animal he 
 diflefted. 
 
 (m) " No o!ie (fays M. Ilumboldt) can fpeak more decidedly on this fubjeft than myfelf, having made fe- 
 veral experiments on my own perfon, the feat of which, in fome inftances, was the focket of a tooth which I 
 had caufed to be extracted ; in others, certain wounds whic^i I made in my hand ; and in others, the excoria- 
 tions produced by four bliftering plafters:" The following is the refult of thefe painful experiments. The 
 galvanic irritation is always painful, and the more fo in proportion as the irritated part is more injured and the 
 time of irritation more prolonged. The firll ftrokes are felt but flightly ; the five or fix following are much 
 more fenfible, and even fcarcely to be endured, until the irritated nerve becomes infenfible from continued (li- 
 mulus. The fenfation does not at all refemble that which is caufed by the eleftric commotion and the eleftric 
 bath ; it is a peculiar kind of pain, which is neither iharp, pungent, penetrating, nor by intermiffions, like that 
 which is caufed by the eleftric fluid. We may diftinguifli a violent ftroke, a regular preflTure, accompanied by 
 an unintermitting glow, which is incomparably more adlive when the wound is covered with a plate of filver 
 and irritated by a rod of zinc, than when the plate of zinc is placed on the wound, and the filver pincers are 
 yfed to eftablifh the communication.
 
 GALVANISM. 
 
 fowl being jn ^ (late of infenftbllity ; for when tlie might be tranfmitted by tli« water upon its furfacc 
 
 nerves were pricked or irritated it fcr«amed violently, witliout palTuig througli its body. 
 
 But all animals fhew figns of great uneafinefs from an There is an experiment mentioned by Dr Fowler, 
 
 eleitric thock. which (hews a ftriking diflVrence between eledlricity 
 
 In general, it muft be confeiTed, that animals under and galvanifm. It was inllituted with a view to afeer- 
 
 fxpcrinients of this kind feem reftlefs and uncafy. tiiin the efTcds of the latter upon the hlood-veflels. 
 
 The great diftinclion of which we fpeak at prefent, The Doflor relates it as foHows : " Having laid bare 
 
 confills in tins, that the eledric fluid produces a fliock and feparated from furrounding parts and from each 
 
 and uneafy fenfation when any part of the body is in- other, the crural artery and nerve in the thigh of a full 
 
 trodnced into the conducting chain; while the influence grown frog, I cut out the whole of the nerve between 
 
 difcovered by Galvani, on the contary, when merely tiie pelvis and the knee ; I then infiauated beneath 
 
 tranfmitt'^d through the body in this iii<inner, gives no the artery a thin plate of fealing wax, fpread upon pa- 
 
 (hock, nor any fenfation whatever, infonuich tiiat we per, and broad enougli to keep a large portion of the 
 
 are not fenfible of its palTage. If this influence be artery completely apart from the reft of the thigh, 
 
 made to atl diretlly on a nerve, there is, no doubt, fome The blood ftill continued to flow through the whole 
 
 kind of irritation produced, as appears from the cft'oft courfe of the artery In an uniliminiflicd llrcam. The 
 
 of the metals upon the tongue, the eye, and other ner- artery, thus partially infnlated, was touched with fdver 
 
 vous parts ; but ftill tiiis aftion bears no analogy to and zinc, which were then brought into contaft with 
 
 that of tiie eleftric fluid. As the application of the each other; but no contraiilion whatever was produced 
 
 metals to the organs of fcnfe, produces in each organ in any mufcle of the limb. 1 his experiment was fre- 
 
 689 
 
 the peculiar fenfation for which it is conftrucled, as 
 taftd in the tongue, light in the eye, &c. fo when 
 nerves intended merely for mufcular motion are fubjedl- 
 ed to the aftion of galvanifm, the elFed produced is 
 motion in the mufcles on which they are diihibuted. 
 
 If this view of the matter be juft, it will explain why 
 no fliock is felt when the human body is made a part 
 of the conducting chain. - In that cafe the influence 
 
 quently repeated upon feveral diflferent frogs, both in 
 whom the nerve was, and in whom it was nor divided. 
 The refult was uniformly the fame. But vivid con- 
 traftions were produced in the whole limb when an 
 eleftric fpark, or even a full llrcam of the aura was paf- 
 fed into the artery." 
 
 Before taking leave of this branch of our fubjcft, 
 it may be proper to take notice of one fatt, which may 
 
 does not, in all probability, aft direftly upon any nerve ; be thought to militate againft the doftrine we have en- 
 and we fee that this influence poirdTcs no power, like deavoured to etlablilli. It is faid that a frog, exhauil- 
 the eleftrlc fluid, of producing a convullive fliock, td and brought near to a charged eleftrophorus, has 
 when merely paffed through any part of the body ; but been found to refume its fnfccptibility. We think this 
 it has this peculiar property, when palTed direftly facl may be accounted for witliout admitting any con- 
 through a nerve, it excites that nerve to perform the nettlon between galvanifm and eledtriclty, merely by 
 funftion for which it was intended by nature. To fuppofing that the irritability of the mufcles, which 
 this it will no doubt be objedted, that contraftions may had been exhaufted, was reftored by the application of 
 be excited in different parts of a frog without*tiny di- a moderate ftimulus, (the eleftrlc fluid), of a kind dif- 
 vifion being made in its fl<In ; and here it may be fup- fercnt from thole by which it had been exhaufted. 
 pofed that the influence is not made to pafs direftly Such of our readers as are acquainted with the writ- 
 through a nerve. But it ought to be recoUedled that iugs of modern phyliologifts on the fubjeft of riiufcular 
 the (kin of thefe animals is abundantly fupplied with irritability, will know that fafts of this kind are very 
 nerves, wlwfe trunks communicate at difl'ercnt places common. Thus it has been found by M Humboldt, 
 
 with thofe which fupply the mufcles ; and that the 
 rontratlions are always ftrong and eaiily excited, in 
 proportion as they are applied near to the couric of any 
 of the nerves which go to the mufcles. But though 
 we had no doubt thac the influence might be tranfmit- 
 ted through the bodies of thefe animals, as well as 
 
 that the oxygenated muriatic acid has often rtllored 
 irritability. To this explanation it will no doubt be 
 objeftcd, that the application of other ftiniuli, as alco- 
 hol and a folutlon of potafli, inftcad of reftoririg, total- 
 ly deftroy the fufccptibility of galvanifm. SufpeAing, 
 that although thefe fubftances in a concentrated ftate 
 
 through the human body, without any contraftions deftroy the fufccptibility, yet that when fuflficiently di- 
 
 being produced, we have thought it worth while to luted, they might be found to have the oppofite effeft, 
 afcertaln the faft by the following experiment. " we tried the following experiment, which conlirmed our 
 
 A frog was prepared in the ufual manner by coat- conjefturc. 
 
 ing its fciatic nerve with tinfoil, and laying the leg A frog, 57 hours after it had been decapitated, had 
 
 lipon a plate of zinc. Another frog, in a very vigo- ceafed for above an hour to be capable of excitement 
 
 rous ftate, had its fore legs and cheft attached to a rod by the application of the mttals in any way that could 
 
 of filver, and its pofterlor extremities to a rod of zinc, be devlfed. A few drojjs of alcohol bcinu- diluted with 
 
 The filver rod was applied to the tinfoil and nerve of about a teafpoonful of water, the nerve and the 
 
 tbe prepared frog, and the zinc rod to the plate of mufcles which had been laid bare, as well as the whole 
 
 ainc upon which the leg was laid. Immediately very fliin of the animal, were wet with it. Upon the ap- 
 
 ilrong contraftione took place In the leg ; but no mo- plication of an excitatory arc, compofed of four pieces, 
 
 tion, nor the flighteft mark, of uneafinefs, appeared in gold, zinc, fdver, and tinfoil, a few very flight contrac- 
 
 the other frog through the body of which the Influ- ti<jns of the toes were diftlniiiy obferved. After this, 
 
 ence muft have palfed. It is neceflTary in this experi- no means that we could think of produced the fmalleil 
 
 ment to dry the body of the frog which is to ferve as excitement. Alcohol was now applied in a more coii- 
 
 & conduflor very carefully, otherwife the influence centratcd ftate, but without any efFed. The fame 
 
 SupPL. Vol. I. Partll. 4S four
 
 690 G A L V 
 
 four pieces of metal which produced the contraftions 
 of the toes, had been ufcd before the diluted alcohdl 
 was ai.plied, but without efi'eiil. We liave not tried 
 the application of potafh much diluted. 
 
 From what has been faid, we think we arc fully 
 warranted in faying, that although feme of the pheno- 
 mena difcovered by Galvani bear a llriking rcfemblance 
 to fome of thofe produced by the elcdric fluid ; yet 
 there are others, and thtfe not the lead iuiporlant, 
 which differ fo widely from any effefts which have 
 ever been feen to arifc from that fluid, that they mull 
 derive their origin from fome other caufe. Our read- 
 ers may probably think that we have dedicated too 
 much time to this queftion ; but as we conceive it to 
 be the moft important point which can be difcufled on 
 this fubjcd, we thought it worth while to confider it 
 at fome length; and we were the more convinced of the 
 iiccefTity of doing fo, from this confideration, that there 
 are ftill fome writers of high authority who maintain 
 
 A N I S M. 
 
 nuity of philoFopliers will one day be able to difcover 
 fome tcft of its prefence in inanimate matter, there 
 feems no reafon to doubt. 
 
 We have made many experiments with a view to 
 difcover fuoh a tcft, but hitherto without the fnallelt 
 fuccefs. In the trials we have already made, oiu- views 
 have been chiefly confined to the ditcovery of fome che- 
 mical cffcfts of this influence upon inanimate matter. 
 M. Volta and other writers, having confidertd the fen- 
 fation produced by it upon the tongue as fimilar to that 
 occafioned by acids, we were not without hopes that it 
 would be found to refemble that clals of fuhftances in 
 fome of its other properties. We have therefore tranf- 
 mitted it through liquids tinged with the moll delicate 
 vegetable colours ; but no change in thefe colours has 
 been effefted by the tranfmiffion of many galvanic ihocks. 
 We have alfo tried, in the fame way, alkaline liquors, 
 without any effeft. We next diflblved in water difle- 
 rent neutral falts, and other compound bodies, of which 
 
 3* 
 The galva- 
 nic influ- 
 ence pro- 
 bably fo- 
 reign from 
 animals. 
 
 fame. 
 
 The next queftion that occurs to us with regard to 
 the nature of galvanifm is, whether or not it depends 
 upon any law of animal life ? To us it appears rather 
 more probable, that the influence which incites the 
 mufcles of animals to contraft in the experiments of 
 Galvani, is fomething quite foreign to the animals them- 
 felves; as much fo as the eleftric fluid of the Leyden 
 phial is to the animal which receives a fhock from it, 
 
 the hypothcfis, that galvanifm and eleftricity are the the parts are held together by the vv^akell affinities ; 
 
 but no change has been obferved to be produced in 
 them by the tranfmiffion of this influence. Our want 
 of fuccefs, liowever, fliall not deter us from continuing 
 our efforts ; we fliall vary the nature of our experiments 
 in every way that (hall occur to us as likely to be attend- 
 ed with advantage ; and if we fliould ultimately fail, 
 we truft that others will be more fortunate. Every 
 new faft which is difcovered upon the fubjefl tends to 
 facilitate this inveftigation, by furnifhing us with new. 
 in both cafes the body of the animal ading as a mere guides to dired the courfe of our experiments, 
 condudor. Upon this queftion, however, we confefs Dr Fowler is of opinion, that this influence, what- d^ Powkr 
 
 that we have neither fads nor arguments to adduce fuf- ever it may be, is not derived from the metals alone, hfOtates on 
 ficient to warrant our drawing any certain condufion. but that the animals at leaft contribute to its produc-'h's point, 
 It will doubtlefs be aflced, if this influence be fome- tion, as well as indicate its_ prefence ; and he_ feems to 
 thing foreign to the bodies of animals, why do we ne- have been led to adopt this theory chiefly from two 
 ver find it aSing anywhere but in their bodies ? why confidcrations, neither of which appears to us to have 
 is it not, like the eleaWc fluid, capable of being made much weight. They are tiie following : The necelTity 
 
 of a communication between the metals and the mufcles, 
 as well as between the metals and the nerves ; and the 
 obfervation, that animals have a more complete con- 
 troul over its effefts than one would expeCl them to 
 have over an influence wholly external to tiiem. But 
 the communication between the metals and the mufcles 
 may be neceflary to the contraction of the latter, tho' 
 not to the produftion of galvanifm; which, however,, 
 for want of any obvious efFedl, is not obferved. That 
 animals have fome controul over the effefts of galva- 
 nifm uponlhemfelvcs, may be very true ; but this cir- 
 cumftance does not appear to us capable of proving any 
 
 evident to the fenfes by its effefts upon inanimate mat- 
 ter ? The only anfwer which we are in a condition to 
 give to this queftion is, that it may very poffibly be 
 capable of producing important efi'efts upon inanimate 
 matter, nay, thefe effefts may be tlie fubjcft of our 
 daily obfervation ; but for want of our being fufBcient- 
 ly acquainted wnth galvanifm to point out the relation 
 between thefe effefts and their caufe, the effefts them- 
 felves are either not explained at all, or afcribed per- 
 haps to fome other power, with which they have no 
 conneftion. In like manner, the eleftric fluid has doubt- 
 lefs been producing moft important effefts from the _ _ _ _ 
 beginning of time ; but, prior to the difcovery of that thing, as they have a controul over the efi'efts of other 
 fluid, thefe were either not explained at all, or confi- ftimuli in the fame way. Thus, an animal of any refo- 
 
 dered as originating from fome caufe which, in faft, 
 had no (hare in their produftion. 
 
 The great difficulty Is to obtain fome teft by which 
 we may deleft the galvanic influence when aftually pre- 
 fent In inanimate matter. Hitherto we have no fuch 
 
 lution can bear, without betraying any uneafy fenfation, 
 a blow which, inflifted unexpeftcdly, would have pro- 
 duced a convulfive.ftart. The will does not in any de- 
 gree controul the effects produced by galvanifm upon 
 our fenfes of tafte, feeing &c. ; that is, the fenfations 
 
 ttft ; nor fliould we know that fuch an Influence exifts, are produced, though we may have refolution not to 
 
 but fur the effefts which it produces upon the bodies 
 of animals through the medium of their nerves. If we 
 had any means of afcertaining its exiftence, either in a 
 feparate ftate, or conjoined with inanimate matter, the 
 fcience would- make a rapid progrei's, as it would be 
 eafy to diverfify experiments fo as to difcover its na- 
 ture and effefts. To deleft It in a feparate ftate is, in 
 all probability, impoffiblej but that the Zealand inge- 
 
 betray them. But, fays Dr Fowler, the will is not able 
 to controul the etfefls of eleftricity, when the eleftrlci- 
 ty Is othervvlfe fuEciently ftrong to excite mufcles to 
 contraftion. This argument may tend to fliew, that 
 galvanifm differs from eleftricity ; but as it muft be ad- 
 mitted, that we can refift the contraftions naturally 
 produced by the application of other foreign ftimuli, it 
 by no means proves that aniinals have any power of 
 
 preventing
 
 G A L V A NM S M. 
 
 prevontiiig the excitement or tranfmifTiDn of galvanifiti. 
 BcfiJes, though we cannot prevent an invohintary con- 
 tradion of our mufcks from taking place wlien an elec- 
 tric (hock of confiderable (Irength is padVd through 
 them, yet any man may with his hand draw fparks 
 from the prime conductor of an eletlric machine with- 
 out Ihrinking, though even thele fparks would, if he 
 were off his guard, produce a convulfive Hart. 
 
 If t'le galvanic inilutiice exifted ready formed in the 
 mufcles or uerves of animals, the only thing requifitc to 
 the production of the contrai;t;ons would be to make a 
 communication helwcen the nerves and mufcles, by 
 means of any fingle (ubllance capable of conducting 
 this influence ; as water, for example : but the revcrfe 
 is known to be true. It may be faid, however, that, 
 although there is no proof that any influence naturally 
 refides in the nerves or mnlcles capable of producing 
 the effefts mentioned by M. Galvani, thefe fubftances 
 may ftill, by fbme power, independent of the properties 
 they poll'eis in common with dead matter, contrihule to 
 the excitement of the influence, wliich is fo well known 
 to exift in them after a certain application of metals. 
 Upon this part of the fubjedl, the obfervatioiis of Dr 
 Wells will be found to merit confiderable attention. 
 
 " It is known (fays that gentleman), that if a 
 mufcle and its nerve be covered with two pieces of 
 the fame metal, no motion will take place upon con- 
 neffing thofe pieces by means of one or more dill'erent 
 metals. After making this experiment one day, I ac- 
 cidentally applied the metal I had ufed as the connec- 
 tor, and which I ilill held in one hand, to the coating 
 of the mufcle only, while with the other hand I touch- 
 eii the funilar coating of the nerve, and was furprifed 
 to find that the mufcle was immediately thrown into 
 contradion. Having produced motions in this way 
 fufHciently often to place the fadl beyond doubt, I 
 next began to confider its relations to other fafts for- 
 merly known. I very loon perceived, that the imme- 
 diate exciting caufe of thefe motions could not be de- 
 rived from the aftion of the metals upon the mufcle 
 and nerve to which they were applied ; otherwife it 
 mufl; have been admitted, that my body and a metal 
 formed together a better conduftor of the exciting in- 
 fluence than a metal alone ; the contrary of which I had 
 known, from many experiments, to be the cafe. The 
 only fource, therefore, to which it could poflibly be 
 referred, was the action of the metals upon my own bo- 
 dy. It then occurred to me, that a proper opportuni- 
 ty now offered itfelf of determining whether animals 
 contribute to the produftion of this influence by means 
 of any other property than their moifture. With this 
 view I employed various moifl fubftances, in which 
 there could be no fufpicion of life to conftitute, with 
 one or more metals, different from that of the coatings 
 of the mufcle and nerve, a connecting medium between 
 thefe coatings, and found that they produced the fame 
 effeft as my body. A fingle drop of water was even 
 fufBcient for this purpofe ; though, in general, the 
 greater the quantity of the moilfure which was ufed, 
 the more readily and powerfully were contradtions of 
 the mufcle excited. But if the mutual operation of 
 metals and moifture be fully adequate to the excite- 
 ment of an influence capable of occafioning mufcles to 
 coiitraft, it follows, as an immediate confequence, that 
 
 691 
 
 35 
 
 animals atl by their moifture alone in giving origin to 
 the fame influence in M. Galvani's experiments, unlefs 
 we are to admit more caufes of an cfTcil than wh»t are 
 fufficient for its produftion." We do not quote the 
 above realoning as pcrfeiltly conclulive, for it by no 
 means appears to us to be fo ; but it certainly gives 
 fome probability to the opinion, that galvanifm is, as 
 M. Volta fuppofes, the relult of the attion of two dry 
 conductors, which touch each other inunedlately o« 
 one hand, wliiie at their other extremities they touch 
 conduftors of what he calls the fecond clafs, (that is, 
 moifture, for all tlic conductors of the fecond claf s con- 
 tain water), and that the bodies of animals act merely 
 as moifture. 
 
 One of M. Humboldt's experi'ments related above, 
 appears to us to Itrengthen the conclullon, that trie in- 
 fluence difcovered by Galvani is fomethiiig perfectly 
 foreign to the bodies of animals. Can it be fuppofed 
 that any fubftance which naturally refides in our bo- 
 dies, fliould, in a few feconds after it is put in motion, 
 convert the fimple fcrous difcharge of a blifter into a 
 dark coloured fluid, of a nature fo acrid as to irritate 
 and violently inflame the fl<in wherever it touches it ? 
 We do not fay that this is impclliblc, for we are too 
 little acquainted with the laws of tecretion to fay with 
 certainty what may, or what may not, produce fuch a 
 change ; but we know no llmllar alteratii n produced, 
 in a fc-jj feconds, by a mere change of aftion in the vef- 
 fels themfelves. 
 
 We fliall not undertake to determine the nature ofxhc crufe 
 the caufe which produces fuch aftonilhing effeds. We"i.ic'i pro- 
 think it is certainly not the electric fluid, and prob.ibly ^""^ '.'^= 
 fomething which refides or is formed in the excitatory r V '""^ ' 
 arc ; but we conliUer our knowledge of galvanifm aski,„wn. 
 ftill in its infancy, and our ftock of fatts as infinitely 
 too fmall to admic of our forming a jufl theory on the 
 fubjedt. Fortunately, however, the dilcovery of Gal- 
 vani has attracted fo much the attention of philofo- 
 phers in every part of Europe, that new fadts may be 
 expedted to come to light every day ; and we hope the 
 time is not very diftant, when thefe may be fo claffed, 
 as to entitle the fubjedt to be ranked among the fciences. 
 See Torpedo in this Suppl. 
 
 While this article was in the prefs, we were favour- 
 ed by a friend with an account of fome German differ- 
 tations on the fubjedt, which we are obliged to infert 
 in this irregular manner. 
 
 Mr Crevc, furgeon in Wurtzburg, had an opportu- 
 nity of obferving the galvanic irritation on the kg of 
 a boy, which had been amputated far above the knee 
 ill the hofpital of that city. Immediately after the am- 
 putation, Mr Creve laid bare the crural nei-ve (knie- 
 kehlnerven), and furrounded it with a flip of tinfoil. 
 He touched at once the tinfoil and the nerve with a 
 French crownpiece. In that inftant the moll violent 
 convulfions took place in the leg both above and be- 
 low the knee. The remainder of the thighbone bent 
 with force toward the calf ; the foot was more bent 
 than extended. All thefe motions were made with 
 much force and rapidity. None were produced when 
 the tinfoil was taken away, or when a flee] pincer was 
 ufed in place of a piece of filver, or when the tin or 
 filver was covered with blood : but they were renew- 
 4 S 2 ed
 
 692 
 
 GALVANISM. 
 
 ed wheo tJiefe obrtacles were reoinved. Thefe phcno- 
 tnena contiiiurd till 38 minutes after the a;nputation, 
 when the limb became cnld. 
 
 Dr Chriftopher Heinrich PfafF {in Dif-rtalioTie dc 
 EJ'dr'ic'iialf Anmali, Stutgardt, 1793: fee alfo Gren's 
 jfournal der Phyfik, T. viii. p. 196, &c.) has clafTed 
 the phenomena in a very orderly and perfpicuous man- 
 ner ; and the refult of the numerous experiments made 
 by himfelf and others, correfponds very nearly with our 
 inferences in the preceding pages. 
 
 • I. Phenomena of mufcuhir conlraShn. 
 
 The general form of his experiments is the fame 
 \yith that which we have placed at the beginning of 
 this article ; but the following varieties were obferved : 
 
 The nerve being coated with tinfoil, it was aUvays 
 obferved that the contraftions were ftronger when the 
 filvi r firft touched thu mulcle, and then the coating. 
 If it touelied the coating firll, the efFccls were always, 
 and vjry fcnfihly, weaker. 
 
 They were ftill ftronger when the filver did not 
 touch the mufcle at all, but only the nerve and its 
 coat'iig. 
 
 When the contraftions were weaker at the begin- 
 ning, thev alfo ceafed fooner. 
 
 No contraftion enfued from touching the coating 
 only, or the nerve only, or the mufcle only, with the 
 filver. 
 
 Continuing the contaiS did not occafion any repeti- 
 tion of the contraftions, except in foire cafes, where 
 the filver was drawn along different parts of the coat- 
 ing, while its other end remained in contaft with the 
 nerve. 
 
 The conlraAions took place only in the mufcles to 
 which the nerve led. 
 
 Their ftreiigth and duration were greater when the 
 furfaces of contafl: were greater, and when the two 
 metals touched each other in points or fharp edges. 
 
 A ligature, with a filk thread below the coating 
 (that is, between the coating and the mufcle, or part 
 of the nerve touched by the filver), prevented all con- 
 traftion ; but not if the ligature was between the coat- 
 ing and the brain. If the nerve was cut through be- 
 
 nerve, or the mufcle, or even dips prstty deep in the 
 water. 
 
 No fuch thing happens in oil ; or, at bed, the con- 
 tractions are very flight. 
 
 Dr Pfaff could not produce contraftions without 
 employing two metals, or a metal and charcoal. 
 
 A vei-y thin covering of mufcular fiedi on the nerv« 
 did not altogether prevent the contraftions, and in 
 many cafes did not fenfibly diminifli them. 
 
 If a piece of lilver be laid on the mufcles of the 
 breaft or belly, and be brought into contaft with the 
 tin-coating on the lumbal region, only the mufrles of 
 the breaft or belly are affefted, but not thofe of tlie , 
 legs. 
 
 Dr Pfaff fays, that the involuntary mufcles are not 
 affefted by galvanifm ; and refers for convincing proofs 
 to a dlftertation by Dr Ludwig, fhewing that tiie heart 
 is not furniflied with nerveg, [Scrtptor. nturolog. minor, 
 Jeka. vol. 2.). 
 
 1 1 . Irritation of the Organs of Seife. 
 
 Here Dr Pfaff 's diffcrtation contains nothing re- 
 markable. 
 
 III. ConjeBures as to the Caufe, 
 
 Dr Pfaff ufes the fame arguments that we have cm- 
 ployed to refute the opinion of a (imilan'ty between ths 
 animal organs and the Leyden phial, and the opinion 
 that eleftricity is the agent. He mentions the opinion 
 of thofe who maintain that the agent is a fluid put into 
 motion by means of its relation to the metals only, in 
 their adiion on each other, and who coniider the ani- 
 mal as merely ferving as a conduflor; and alfo ferving, 
 by its irritability, to give us the information of the pre- 
 tence of fuch a fluid, in the fame manner as another 
 kind of irritation, fomewhat analogous to it, indicates 
 the prefence and agency of the eledfric fluid. It may 
 therefore be called tlie Metallic Irritation ; a term 
 which will fufficiently diftinguifti it. 
 
 But Dr Pfaff feenis rather to think that the agent 
 refides in the animal, and that the metals are the con- 
 duftors {See a dlftertation, entitled, Farther Contri- 
 I'Utions to the Knoni'ltdye of minimal Eledricity, in Gren's 
 
 low the coating, and the parts feparated a quarter of Journal der Phyfik, T. viii. p. .^77.). This fluid he 
 
 an inch, no contraftion followed by touching the coat 
 ing and the nerve or mufcle : but it took place, if the 
 parts were brought into contact ; or even if a piece 
 of any other nerve was put between the parts. 
 
 If a confiderable part of a bared nerve was infulated 
 and coated, partly with tinfoil and partly with filver, 
 contraclions were produced in the mufcle to which it 
 led whenever the two metals were brought into con- 
 tad. 
 
 If one crural nerve be coated with tin, and the o- 
 ther with filver, contraftionf are produced in both legs 
 by bringing the metals into contaft. 
 
 If the nerve be dry under the coatings or when the 
 jfilver touches it, or in both places, we have no contrac- 
 
 conceives to be intimately blended with ^t principle of 
 life ; nav, perhaps, ti> be the fame. He mentions a 
 thought of Profeffor Kielmayer, " that it may refemble 
 the magnetic fluid in its manner of afting, giving con- 
 nection to the diftant particles of a nerve, as we oblerve 
 a magnet give an inftantancous conneiflion to each of a 
 parcel of iron filings ; all of which it would arrange iu 
 a certain precife manner, if they were fufficiently move- 
 able, bv giving momentary polarity to each." This 
 fomewhat refembles Newton's hypothetical whim read 
 to the Royal Society, defcribing what may be done by 
 means of an aether (See Birched Hijlory of the Royal 
 Societv). 
 
 But all this is vague conjefture, and merits little at- 
 tention. This will be better bellowed on an obferva- 
 tion of M. Humboldt of Jena, " that a bit of frefti rai)- 
 
 tions ; but thev begin as foon as we moillen the nei-ve. 
 
 Dr Pfaff infers from thefe phenomena, that the 
 
 nerve alone is fubjeft to the irritation produced by the relle (the Hehella mitra of Linna;iis) may be fubftituted 
 
 two metals. for a bit of nerve in the animal arc in thefe experiments." 
 
 If the prepared frog be immcrfed in water, fo that This is the only vegetTible fubftance yet difcovered to 
 
 the coating touches the water, contraftlons are pro- have this property. If the nerve be laid on the mo- 
 
 duced by touching the coating above water with the relle, we have only to touch the niorelle with the zinc, 
 
 ilver, while another part of the filver touches the and the mufcular contiaftions immediately follow. 
 
 GARDECAUT-
 
 GAR 
 
 [ 69 
 
 Ginlecaut, GARDECAUT, or Guard du Cord, in a watch, 
 Uarde... jg (1,^^ which Ao^s the fiifce when wound up, anfi for 
 *■""* that end is driven up by the fpring. Some c;iU it 
 
 Guard Click ; others Guard du Gut. 
 
 GARDEN (Francis), better known to the public 
 by the title of Lord Card.njlone, was born at Edin- 
 burgh June 24th, in the year 1721. His father was 
 Alexander Garden of Troup ; an opulent landhidder 
 in Aberdeenfhire ; his mother was Jane, daughter of 
 Sir Francis Grant of CuUen, &.C.I. 
 
 After palTing through the ufual courfe of liberal 
 education at the fchool and the univerfity, he betook 
 hinifelf to the iludy of law for his profcffion. In the 
 year 1744. he was admitted a member of the Faculty of 
 Advocates, and called to the Scottiih bar. 
 
 In his praftice as an advocate lie foon began to be 
 dift!nE;ui(hed, bv a ftrong, native rcftitnde of under- 
 ftanding ; by that vivacity of a])prehenlion and imagi- 
 nation which is commonly denominated Genius ; by 
 manly candour in argument, often more perfuafive than 
 fubtlety and fophiftical artifice ; by powers which, with 
 diligence, might eafdy attain to the Iiigheft eminence 
 of the profeflion. But the fame ftrength, opcnnels, 
 and ardour of mind, which diltinguilhed him lo advan- 
 tageoufly among the pleaders at the bar, tended to 
 give him a fondnefs for the gay enjoyments of convi- 
 vial intercourfe, which was unfavouiable to his progrefs 
 in juridical erudition. Shining in the focial and con- 
 vivial circle, he became Icfs folicitoufly ambitious tliaii 
 he might otherwife have been, of the charafler of an 
 eloquent advocate, or of a profound and learned law- 
 yer. The vivacity of his genius was avcrfe from au- 
 llere and plodding ftudy, while it was captivated by the 
 fafcinations of polite learning and of the fine arts. Nor 
 • did he always efcape tliofe excefles in the purfuit of 
 pkafure into which the temptations of opening lire are 
 apt occafionally to feduce the moft liberal and ingenu- 
 ous youth. But his cheerful conviviality, his wit, hu- 
 mour, tafte, good-nature, and benevolence of heart, ren- 
 dered him the delight of all his acquaintance. He be- 
 came his Majeftv's Solicitor July ^d, 1764. 
 
 At length the worth of his charadter, and his abi- 
 lities as a lawyer, recommended him to the office of a 
 Judge in the Courts of Seffion and Judiciary, the fu- 
 preme judicature, civil and criminal, for Scotland. His 
 place in the Court of Seffion he continued to oceuj-y 
 till his death ; but had, fome years before, refigned the 
 office of a Commiffioner of Judiciary, and in rtcom- 
 pence got a penfion of 2ic!. per annum. Char difccrn- 
 ment, ftrong good feiife, conicieiitlous honefty, and ami- 
 able benevolence, remarkably diftinguiihed all his opi- 
 nions and conduft as a judge. 
 
 We not unfrequently fee the gay young men of the 
 prefent age, to turn, as they advance towards middle life, 
 from the headlong purfuit of pleafure to a fordid and 
 contrafted lelfifhnefs, which excludes even thofe tew 
 good qualities that fcemed to accompany their fuft 
 thoughtlefs days. Their life is divided between lentu- 
 ality and that anxious inii.7.Mn« avarice and ambition 
 whofe ultimate oh'ytSl is, to provide gratifications to 
 fenfuality and pride. The kindling liglit of reftitude, 
 and the fiid fparks of generous humanity, arc extin- 
 guidied in their breads as foon as thofe ebullitions of 
 youthful paffion and inexperience are over, by which 
 the ufeful efficiency of their caily good qualities wa« 
 
 3 ] GAR 
 
 prevented. Hardly have they become tolerably well GarJea. 
 acquainted with mankind, when the milk of human • ■' 
 kinduefs is turned into gall and venom in their hearts. 
 
 It was far otherwife with Lord Gardcnilone. As 
 he advanced in years, humanity, tafte, public fpirit, be- 
 came ftill more and more eminently the predominant 
 principles in his mind, — He pitied ilie condition of the 
 peafantry, deprelfcd rather by their ignorance of the 
 moft ftviltul modes of labour, and by their remotenefs 
 from the fphere of improvement, than by any tyranny 
 or extortion of tlieir landlords. He admired, protec- 
 ted, and cultivated the polite arts He was the ardent 
 votary of political liberty, and friendly to every thing 
 that promifed a fealible amelioration of public econo- 
 my, and the principles of government. 
 
 In tiie year 1762 he purchafed the eftate of John- 
 fton, in the county of Kincardine. Within a few years 
 after he bcgjn to attempt a plan of the moft liberal im- 
 provemeut of the value of this eftate, by an extenfion 
 of the village of Laurencekirk, adjoining. He offered. 
 Icafes of fuiall farms, and of ground for building upon, 
 which were to laft for the term of one hundred years ; 
 and of which the conditions were extremely inviting to 
 the labourers and tradefmeu of the furrounding coun- 
 try. Thefe offers were eagerly liftened to. More deli- 
 rous to make the attempt beneficial to the country than 
 to derive profit from it to himfelf, he was induced, 
 within a few years, to reduce his ground-rents to one- 
 half of the orio iual rate. — Weavers, joiners, flioeniakers, 
 and other arlilans in a confiderable number, reforted to 
 fettle in the rifing village. His Lorddiip's earneftnefs 
 for the fuccefs of his projedf, and to promote the pro- 
 fperity of the good people whom he had received under 
 his protedtion, led him to engage in feveral uaderta- 
 kings ; by the failure of which he incurred confiderable 
 lofics. Projefts of a printfield, and of manufaftures of 
 linen and of ftuckings, attempted with fangulne liopes 
 in the new village, and chiefly at his Lordfhlp's riiic 
 and cxpence, mifgave in fuch a manner as might well 
 have finally difgufted a man of lefs fteady and ardent 
 philanthropy with every fuch engagement. But the 
 village ftill continued to advance. It grew up under 
 his Lordfhip's eye, and was the favourite objetl of his 
 care. In the year 1779 he procured it to be eredled 
 into a burgh of barony ; having a magiftracy, an annual 
 fair, and a weekly market. He provived in it a good 
 inn for the reception of travellers ; and vi'ith an un- 
 common attention to the entertainment of the gucfts 
 who might refort to it, furniflied this inn with a libra- 
 ry of books for their amiifement. He invited an artlft 
 for drawing, from the continent, to fettle at Laurence- 
 kirk. He had the pleafure of feeing a confiderable li- 
 nen manufacture at length fixed in it. i\ bleachfisld 
 was alio eflablifhed as a natural counterpart to the li- 
 nen mannfatture. Before his Lordfhip's death, he faw 
 his plan of improving the condition of the labourers, 
 by the formation of a new village at Laurencekirk, 
 crowned with fuccefs beyond his moft fangulne hopes. 
 He has acknowledged, with an amiable franknefs, in 
 a memoir concerning this village, •' That he had 
 tried, in fome meature, a variety of the pleafures 
 which mankind purfue ; but never rehftied any fo much 
 as the pleafure arifing from the progrefs of his vil. 
 lage." 
 
 In th« year 1785, upon tLe death of liis elder bro- 
 
 therj.
 
 GAR 
 
 [ 694 ] 
 
 GAR 
 
 Carden. tlier, Alexander Gavclen of Tioup, M, P. for Aberdeeii- 
 ' ihire. Lord Gardenllonc fuccecded to the pofTcflion of 
 the family cftates, which were very conriderablc. Un- 
 til this time his LorcKhip's income had never been more 
 than adequate to the liberal expencc into which his 
 rank, and the gencrofity of his nature, uuavuid;ibly led 
 liim. But the addition of a fortune of about three 
 thonfand pounds a-year to his former revenue, gave him 
 the power of performing many aAs of beneficence with 
 which he could not before gratify his good heart. It 
 was happy, likewife, that his fuccefiion to this ample 
 income, at a period when the vigour of his conftitution 
 was rapidly yielding to the infirmities of old age, ena- 
 bled him to feck relief, by a partial celfation from buli- 
 iiefs, by travel, and by other means, which could not 
 have been eafdy compatible with the previous ilate of 
 his fortune. 
 
 In the month of Sept. 1786, he fet out from Lon- 
 don for Dover, and pafled over into France. After vi- 
 fiting Paris, he proceeded to Provence, and fpent the 
 winter months in the genial climate of Hieres. In the 
 fpring of 1787 he returned northwards, vifiting Ge- 
 neva, Switzerland, the Netherlands, and the Dutch pro- 
 vinces, and paffing through Germany into Italy. With 
 a fond curiofiiy, attentive alike to tiie wonders of na- 
 ture, to the noble monuments of the arts, and to the 
 awful remains of ancient grandeur, with which Italy 
 abounds, he vilited all its great cities, and furveyed almoll 
 every remarkable and famous Icene that it exhibits. 
 
 His firft objedl, in tliefe travels, was to obtain the 
 reftoration of his declining health by the influence of a 
 milder climate, by gentle, continued, and varied exer- 
 cife ; by that pleating exhilaration of the temper and 
 fpirits, which is the bell medicine to health, and is moll 
 fuccefsfully produced by frequeiit change of place, and 
 of the objeils of attention. But the curiolkies of na- 
 ture and art, in thole countries through which he tra- 
 velled, could not fail to atti'adl, in a powerful manner, 
 the curiofity of a mind cultivated and ingenious as his. 
 He, whofe breall glowed with the mod ardent philan- 
 thropy, could not view the varied works and manners 
 of a diverfity of nations of his fellow men, without be- 
 ing decly interelled by all thofe circumllanccs which 
 might appear to mark their fortunes as happy or 
 wretched. He eagerly collefted fpecimens of tlie Ipars, 
 the fliells, the ftrata 01 rocks, and the veins of metals, 
 in the feveral countries through which he pafled. He 
 amaffed alio cameos, medals, and paintings. He en- 
 quired into fcience, literature, and local inftitiitions. 
 He wrote down his obfervations, from time to time ; 
 not indeed with the minute care of a pedant, or the 
 ollentatious labour of a man travelling with a defr^n to 
 publifh an account of his travels, but fmiply to aid me- 
 mory and imagination in the future remembrance of ob- 
 jeAs ufeful or agreeable. 
 
 After an abience of about three years he returned 
 to his native country. The lall years were fpent in 
 the difcharge of the duties ot his office as a judge ; in 
 focial intercourfe with his friends, among whom was 
 the venerable Lord Mouboddo, and others of the moil 
 refpeftable charaiAers that our country has to boaft of; 
 
 the induftry of his dependants, and in lending his aid 
 to every rational attempt at the Improvement of public ^ 
 economy and public virtue. 
 
 St Bernai'd'i Well, in the neighbourhood of Edin- 
 burgh, had been, long fince, diilinguiihcd fur the me- 
 dicinal virtues of its waters. But various circumflan- 
 ces had alio concurred of late to throw it into iiegleA. 
 Yet its waters being (Irongly mineralized by a iulphu- 
 rated hydrogenous gas, were, by this means, nnquel- 
 tionably qualified to operate, with highly beneficial et- 
 fedts, in the cure of various difeafes. Tlie qualities ot 
 this mineral water falling under Lord Gardendoue's 
 notice, he was induced to purchafe the property of the 
 well, to diredl it to be cleared from furroiuiding ob- 
 ftacles, which contaminated the virtues of the water, or 
 made it inacceflible ; to creel a beautiful and commo- 
 dious edifice over it ; and to app_^oint proper perlons to 
 diilribute the water, for a very trivial compenlation, to 
 the public. The well lies at a diftance from Ediu- 
 bugh, which is very convenient for a funuiier morn- 
 ing's walk. Within the few years which have pafled 
 fince Lord Gardenftone's benevolent care brought it 
 into notice, it has attrafted many of the inhabitants of 
 that city to vifit in the mornings of fpring and fummer. 
 And, undoubtedly, the agreeable exercife to which they 
 have thus been allured, and the falutary efFeds of the 
 water, have contributed, in no mean degree, to difpel 
 difeafe, and to confirm, or re-eftabh(li health. Such 
 monuments are worthy to preferve the memory of a 
 patriotic and a good man ! 
 
 As an amufemcnt for the lad two or three years of 
 his life, when his Increafing infirmities precluded him 
 from more adlive exercife, and from mingling fo fre- 
 quently in the fociety of his friends as was .agreeable 
 to his focial and convivial temper, he bethought him- 
 felf of revifing fonie of ihe jeux d'tfprii, and light fugi- 
 tive pieces, in which he had indulged ihe gaiety of his 
 fancy in his earlier days ; and a fmall volume of poems 
 was publilhed, in which the bell pieces are, upon good 
 authority, afcribed to Lord Gardenftone. He revifed 
 alfo the memorandums which he had made upon his 
 travels, and permitted them to be fent to prefs. The 
 two former voluiues were publilhed one after another 
 while his Lordfliip was yet alive ; the third after his 
 death. They met with a very favourable reception in 
 the world, and were honoured with the high approba- 
 tion of the mod refpedable writers of periodical criti- 
 ccfm. They convey much agreeible information, and 
 belpeak an elegant, enlightened, and amiable mind. 
 The lad volume is filled chietly with memorandums of 
 his Lorddiip's travels in Italy ; and contains many in- 
 tereding criticilms upon fome of the nobled proiiuc- 
 tions of the fine arts of painting and fculpture. 
 
 His Lorddiip's health had long been declining; and 
 he died a bachelor on the 22d of July 1793, lainented 
 by his relations and friends, by his tenants and humble 
 dependants, and by all true patriots and good men to 
 whom his merits and virtues were known. 
 
 Such is the account of Lord Gardenftone's life, 
 which was prefixed to the third volume of his travel- 
 ling memorandums ; and though it was no doubt an 
 
 G.irdfB. 
 
 in the performance of a thoufand generous offices of cffufion of fond frienddiip, we beheve that the praife 
 benevolence and humanity; in cherilhing thofe fine arts, which it beftows on his Lorddiip is not much exagge- 
 of which he was an eminent admirer and judge ; and rated. In the latter years of his life, it mud indeed be 
 above all, in promoting the comfort, and encouraging confeffed, that be contraded intimacies with men un- 
 
 worthy
 
 GEO [ 69s ] GEO 
 
 worthy of his regard ; and that his attachment to li- between the geocentric place and the Crft point of 
 
 btrty made him form expeftations from tJie French re- Arits. 
 
 vohition, which even the events which he faw ought to GEOMETRICAL Method of the Ancients. 
 have reprcffed. But his mind «"as by that time weak- The ancients eftabh'fhed the hijjher parts of tlicir gco- 
 encd by difeafe ; and it would be very iiniud to bahuice metry on the faine principles as the elements of that 
 the iniprudcncies of one or two years againit liie meri- fcicnce, by demonftrations of the fame kind: and they 
 torious arti')ns of a whole life. Befides his travelling were careful not to fuppofe any thing done, till l)y a 
 memorandums and his poems, his Lordfhip piiMilhcd previous ])roblem they had (hewn that it could be done 
 y1 LefUr to the Inhabitants of Lmintuehirk, the mod va- by aftiially ptrfurming it. Much lefs did they fuppofe 
 luable, in our opinion, of all his publication? ; for it any thing to be done that cannot be conceived ; fuch 
 contains perhaps the molt falutary advices which were as a line or feries to be aiftuallv continued to infinity, 
 ever ottered to the itdiabitauts of a manufafturing town, or a magnitude diminiflied till it become infinitely lefs 
 for the regul ition of their coiidudt towards eacti other, than what it is. The elements into wtiich they refol- 
 That the people of Laurencekirk have followed thefe ved magnitudes were finite, and fuch as might be con- 
 advices, it would give us plcafnre to learn on good au- ceived to be real. Unbounded liberties have of late 
 thority. been introduced ; by which geometry, which ought to 
 
 GAS. See that article, Enctcl. and Cufmistry- be perfeftly clear, is filled wi'.li myfterics. 
 Index in this Supplement. We have introduced the word GfOMEtuc^L Solution of a problem, is when the 
 
 here, to notice fome experiments made bv Piofeifor problem is direftly refolvcd according to the ftrict rules 
 
 Jacquin of Vienna, at the defire of Dr Chladiii, on the and principles of geomet''v, and by lines that are truly 
 
 different gafes as the vehicle of founds. A glats bell geometrical. This expreffion is ufed in contradillinc- 
 
 was fnrnilhed with a metallic ftopper cemented to a tion to an arithmetical, or a mechanical, or inllrumcntal 
 
 neck at the top ; and in the bore of this cock, within folution, the problem being refolved only by a ruler 
 
 the glafs, a fniall flute or pewter (etain) about fix inches and compalTes. 
 
 in length was fixed. The glafs being then placed on Tiie fame term is likewife ufed in oppofition to all 
 
 the fhelf of the pneumatic veflel, and filled with any indirect and inadequate kinds of folutions, as by ap- 
 
 particular kind of gas, a bladder alio filled with the proximation, infinite feries, Sec. So we have no geo- 
 
 fame gas, and provided with a cock, was adapted to the metrical way of finding the quadrature of the circle, 
 
 external aperture of the cock belonging to the bell- the duplicature of the cube, or two mean proportionals, 
 
 glafs. In this difpofition of the apparatus, the flute though there are mechanical ways, and others, by in- 
 
 was made to found by gently prefling the bladder. Com- finite feries, Sec. 
 
 parative experiments were made with atmofpheric air, GEORGIUM Sipus (fee Astronom Y-/n</f.r, £"»- 
 
 oxygen, hydrogen, carbonic acid, and nitrous gas. The cycl.) has no fewer than fix fatellites revolving round it, 
 
 intenfity of the found did not vary; but when compa- all difcovered by Dr Herfcliel. Of the two which he 
 
 red with that produced by atmofpheric air, the oxygen firft difcovered, one was found to revolve in 8 days 
 
 ga"! gave a found half a tone lower; azotic gas, prcpa- 17 h. I m. 17 fee. at the diflance of 33" from its pri- 
 
 red by different methods, conflantly gave a found half iViary ; and the other in 13 d. 1 1 h. 5 m. 1,5 fee. at the 
 
 a tone lower ; hydrogen gas gave nine or eleven tones dillance of 44'',23. The planes of their orbits form 
 
 higher; carbonic acid gas gave one-third lower, and ni- fuch large angles with that of the planet itfelf, and 
 
 trous gas alfo very nearly a third lower. A mixture of confequently of the ecliptic, as to be almoft perpendi- 
 
 oxygen gas and azot, in the proportions of the atmo- cular to it. To this remarkable departure from the 
 
 fpheric air, afforded the tone of this lafl; that is to fay, analogy of the old planets, another flill more Angular 
 
 it was half a tone higher than each of the component has been lately announced. They move in a retrograde 
 
 parts alone. When the two gafes were not uniforndy direftion ! The new fatellites revolve as follows, the 
 
 mixed, the found was abominably hard). Chladni in- periodical times being inferred from their greatell elon- 
 
 Geometri- 
 cal, 
 Georgium. 
 
 tends to give a fuller account of thefe intereiling expe- 
 riments. — Journal de Phyfique, Vol. IV. N. S. p. 57. 
 
 GAZONS, in fortification, turfs, or pieces of frefh 
 earth covered with grafs, cut in form of a wedge, about 
 a foot long, and half a foot thick, to line or face the 
 outfide of works made of earth, to keep them up, and 
 prevent their moulderinji. 
 
 gations : The interior fatellite in 5 d. 2 1 h. 25 m. at 
 the dittance of 25', 5. A fatellite intermediate between 
 the two old ones in 10 d. 23 h. 4 m. at the dillance of 
 38", 57. The nearefl exterior fatellite at about double 
 the dillance of the farthell old one, and confequently 
 its periodical time 38 d. 1 h. 49 m. And the mod dif- 
 tant fatellite full four times as far from its primary as 
 
 GEOCENTRIC place or a planet, is the place the old fecond fatellite. Whence it will take at leatl 
 
 where it appears to us from the earth ; or it is a point 107 d. l6h. 40 m. co complete its revolution. Whe- 
 
 in the ecliptic, to which a planet, feen from the earth, thcr the motions of tliefe four be direft or retrograde, 
 
 is referred. is, we fuppofe, not yet determined. 
 
 GtocENTRic Latitude of a Pliinet, is its latitude as fecn From fome obfervations of the Dotlor, with an ex- 
 
 from the earth, or the inclination of a line conneAing cellent feven-feet telefcope, certain appearances, refem- 
 
 the planet and the earth to the plane of the earth's (or bling that of two rings furrounding tlie planet, and 
 
 true) ecliptic: Or it is the angle which the faid line crofliug each other at right angles, were feen on feveral 
 
 ( con nefting the planet arkd the earth) makes with a line different days. They were not altered in pofition by 
 
 drawn to meet a perpendicular let fall from the planet turning the fpeculum in its cell ; but (fays Mr Nicliol- 
 
 to the plane of the ecliptic. fon) there is little doubt that they were optical decep- 
 
 Gf.ocEHTRic Longitude of a Planet, is the didance tions, becaufe they kept their pofition vvith refpett to 
 
 jncalured on the ecliptic, in the order of the %ns, the tube, after the relative pofition of the parallel had 
 
 been
 
 G E R 
 
 [ Oij6 i 
 
 G E R 
 
 Gnsrd. befn much changed by the earth's rotation, and be- 
 —~\~—' oaiil'e tht'y did not uppear with larger telcfcopes applied 
 during tfie coiirfe of ten years. The di(!c ,of the Geor- 
 gium Sidus 1$ flattened. It therefore revolves with con- 
 siderable rapidity on it3 axis. From the very faint light 
 of the fatelh'tes, they are obi'evvcd to dilappcar in thole 
 piirts of their orbits \vhieh brin^- them iipparently near- 
 eH. the pljnet. Tliit does not arife from an atmofphere; 
 for the ctfcft is the fame, whether the fatellite be with- 
 •in or beyond the planet. 
 
 GERARD (Alexander, D. D), was the eldeft fon 
 of tlfc reverend Gilbert Gerard minifter of Chapel-Ga- 
 rioch, in the county of Aberdeen. He was boru on 
 the 2 2d of February 172S, and received the firll rudi- 
 ments of his education at the parilh fchool of Foveran 
 in the fame county. 
 
 It may perhaps be proper to inform our Englifli 
 Tcaders, that in every parilh in Scotland there is a fchool 
 , where, for very fmall fees, the youth of the parifli are 
 
 not only taught to read the Englilh language, to write', 
 and to perform the elementary operations of arithmetic, 
 but are alfo iuftrutled in the Greek and Latin lan- 
 guages. Of thefe fchools, many of the mailers were, 
 about fixty years ago, eminent for claflical learning ; 
 and it feems that Mr Forbes, the mafter of the fchool 
 of Foveran, pofleflcd fuch fame as a teacher, that Mr 
 Gerard judged it more expedient to commit his fon to 
 his care than to have4iim educated at the Ichool of his 
 •own parifh, and under his own immediate infpeftion. 
 The attainments which that fon afterwards made in li- 
 terature, evince that his judgment was corretl, and that 
 the fchoolmafter of Foveran deferved the fame which 
 he enjoyed. 
 
 Young Gerard, however, did not remain long at Fo- 
 ijeran. His father died when he was but ten years old ; 
 and his mother removing foon afterwards with her fa- 
 mily to Aberdeen, he was of courfe put to the gram- 
 mar fchool in that city : but fo folid was the founda- 
 tion which had been already laid, that in two years 
 time he was deemed fit for the univerfity, and was ac- 
 cordingly entered a ftudent in Marifchal college. Such 
 rapid progrefs fupplies the place of that teftimony which 
 we have not been able to procure, refpedting his early 
 attachment to literature. 
 
 After completing the ufual academical courfe of four 
 -year? in the lludy of Greek, Latin, mathematics, and 
 philofophy, he was admitted to the degree of mailer of 
 arts; and immediately afterwards commenced the fludy 
 of theology, which he profccuted in the univerfities of 
 Aberdeen and Edinburgh. In 1748, when he had little 
 more than completed his 20th year, he was licenled to 
 preach in the church of Scotland, and two years after- 
 wards was chofen afliilant to Mr David Fordyce pro- 
 feflbr of philofophy in the Marifchal college and uni- 
 verfity of Aberdeen. In this capacity he performed 
 the duties of the abfent profelfor till the 7th of July 
 1752, when he was appointed fucceflbr to Mr Fordyce, 
 who had been drowned on the coail of Holland, as has 
 been already related in the Encyclopaedia. 
 
 At that period it was the prattice in the Marifchal 
 college, as it continued to be in the King's, for the 
 fame prufedor to carry forward a clafs of Undents for 
 three fucceffive years through all the different branches 
 of philofophy which were taught in the college. Thefe 
 were, Logic, Omtology, Pneumatics, Morals, 
 
 Politics, and Naturai, Phii,oso»h?; nnd^M"' Ge» 
 rard carried one clah through this extcnfive courfe. " 
 Mathematics and the Greek language were taught 
 by leparatc profelTors. 
 
 About the year 1754, a very material alteration was 
 made in the rji\ler of teaching philofophy in the univer- 
 fity of Aberdeen ; and in the Marifchal college each 
 profell'or was reft rifted to one department of Iclence. 
 The principal and profefTors in that college, julUy ob- 
 ferving that the public is interefted in every thlug whicli 
 relates io education, thought it incumbent upon them 
 to lay before that public the reafons which had deter- 
 mined them to deviate from the arrangement which 
 they had hitherto obfervcd ; and they employed Pro- 
 felVor Gerard to draw up thefe reafons. This talk he 
 performed in a fmall pamphlet, which, being printed by 
 the appointment of the college, appears to have given 
 very general fatisfaftion. 
 
 This, indeed, it could hardly fail to do ; for the Ju- 
 dicious author points out very clearly the inconveniences 
 of the old, and the advantages of the new plan of aca- 
 demical lludy. Having obferved that the philofophy 
 which had fo long kept polFefiion of the fchools, coa- 
 filled, in a great meafure, of verbal lubtlcties and theo- 
 ries ill-grounded, though ingenioufly devifed, he pro- 
 ceeds to contrail it with the philofophy of Bacon and 
 Locke, and to fliow of how little value the former is 
 when compared with the latter. He then enters on a 
 brief examination of the fcholaillc logic, and proves, to 
 the conviftlon of every impartial judge, that the art of 
 fyllogifing, though a proper enough introduftion to a 
 philofophy which was built on general principles, either 
 taken for granted, or founded on very narrow and in- 
 adequate obfervation, is by no means fitted to aflifl the 
 mind in the cultivation of that fcience which is dedu- 
 ced by induftlon from particular fafts. " The only 
 bafis of philofophy (fays he) is now acknowledged tu 
 be an accurate and extenfive hiftory of nature, exhibit- 
 ing an exaft view of the various phenomena, for which 
 philofophy is to account, and on which it is to found 
 its reafonlngs. This being the reformed ftate of philo- 
 fophy, great inconveniences mull be found in profecu- 
 ting the fcholaftic order of the fciences. The iludent 
 muil make a tranlition at once from words and langua- 
 ges to philofophy, without being previoufly introduced 
 to the knowledge of fafts, the fole foundation of, and 
 preparation for it ; he mull be hurried at the firll into 
 the raoll abftrufe, difficult, and fubtle parts of it ; he 
 mull be put upon examining the nature, foundation, and 
 difi'erent kinds of evidence and reafoning, before be is 
 acquainted with any fpecimens of thefe kinds by which 
 they may be illuflrated. And in proportion as phllo. 
 fophy Is more improved, and more thoroughly reform- 
 ed, thefe inconveniences mull become nvore fenlible. 
 
 " The view if thefe (continues he) induced the maf- 
 ters of the Marifchal college to think of altering the hi- 
 iherto received order ; and after the moil mature deli- 
 beration, made them at lafl refolve, that their Undents 
 fliould, after being inflrufted in languages and claflical 
 learning, be made acquainted with the elements of hif- 
 tory, natural and civil, of geography and chronology, 
 accompanied with the elements of mathematics; that 
 they fhould then proceed to natural philofophy ; and, 
 lalt of all, to morals, politics, logic, and metaphyfics." 
 
 In vindicating this arrangement, he labours with 
 
 great
 
 G E R [ 697 ] 
 
 {»reat earneftnefs, and we tliink with complete fuccefs, 
 ' to Ihe-vi' tlie propriety of miking logic the lall bnincli 
 of academioal lliidy. " All fclences (fays he), all de- 
 partments of knowledge whatever, mull be premifed as 
 a ground-work to genuine logic. Hiltory has one 
 kind of evidence, mathematics another, nacursl philofo- 
 phy one ftill different, the philufophy of human nature 
 another dillinft from all thefe ; the fubordinate branches 
 of thefe feveral parts have ilill minuter peculiarities in 
 the evidence appropriated to them. An unprejudiced 
 mind will in each of thefe be convinced by that Ipecies 
 of argument which is peculiar to it, though it does not 
 relleft how it comes to bt convinced. j3y being con- 
 verfant in them, one is prepared for tlie Ihidy o{ logic ; 
 for they fupply him with a fund of materials ; in them 
 the dilrercnt kinds of evidence and argument are ex- 
 emplified ; from them only thofe illuftrations can be ta- 
 ken, without which its rules and precepts muft be un- 
 intelligible. 
 
 " All juft conclufions concerning the works of na- 
 tiire muft be founded on an induttion of particulars. 
 And as in natural phllofophy thefe particulars are fup- 
 j)lied by obfervations and experiments on nntural bodies ; 
 i"o in logic, the particulars, of which an induction muft 
 be made, are to be learned only from the body of arts 
 and Jciences. Thefe are the fubjeits on which obferva- 
 tions muft be made, in order to lay down rules tor in 
 
 G E R 
 
 and correfts In's talle, perceives the principles on which 
 he has founded all his judgments, though he did not in ' 
 the mean time think of them, and gains additional fe- 
 curity againft hi.< judging wrong. This may illuftrate 
 what has been faid of the place wliich logic ought to hold 
 ainong the feiences. The obfervations made in it, both 
 concerning the metiiods of invention and of probation, 
 are founded on, and deduced from, the feveral feiences 
 in which thefe methods are ufed. Neither the obfer- 
 vations theinfclves, nor the reafons on which thev are 
 built, can be fully comprehended by one abfolutely ig- 
 norant of thefe feiences. In Undying the particular 
 feiences, reafon will fpontaneouily exert itfelf : if the 
 proper and natural method of reafoning is ufed, the 
 mind will, by the native force of its faculties, perceive 
 the evidence, and he convinced by it, though it does 
 not refledl hoiv this comes to pafs, nor explicitly confi- 
 der according to what general rules the underllanding is 
 exerted. By afterwards ftudying thefe rules, one will 
 be farther fitted for profecuting the feveral feiences ; 
 the knowledge of the grounds and laws of evidence will 
 give him the fecurity of rtfledion, againft employing 
 wrong methods of proof and improper kinds of evi- 
 dence, additional to that of injlhia and nntural genius. 
 And thus logic will greatly contribute to improvement 
 in knowledge ; and more fo, when it is ufed as a re-oieiu 
 of the method taken in the profecution of fcicnce, of 
 
 Gerard. 
 
 veftigating and proving the truths of which they are the foundations gone upon, and of the general rules 
 
 that have been obferved, than when it is apjiiied as an 
 introduBion to the elements of fcience ; for in the for- 
 mer cafe, its rules can be perfettly underftood, fuffici- 
 ently illuilrated, and put in praftice as they are learned, 
 w^hich in the latter is quite impoflible." 
 
 Having thus vindicated the new arrangement with 
 refpett to the place which it affigns to the ftudy of lo- 
 gic, he proceeds to inquire in what order the other 
 Iciences fhould fucceed each other. " Ethics (fays he) 
 or moral philofophy is founded as well as logic on pneu- 
 matics, and muft therefore come after it. The conftitu- 
 tion of man, and his feveral adive powers, muft be ex- 
 
 made ; juft as the genuine performances of any art 
 are what muft be confidered and obferved in laying 
 down the rules of that art. No folid precept can be 
 formed in logic, except by examining arts and feiences, 
 and attending to the method of reafoning ufed in them, 
 and to the evidence that accompanies it. In propor- 
 tion as they are cultivated, and no farther, logic may 
 be improved. And what is true of the invention of lo- 
 gic, is true likewife of the ftudy of it. It can be un- 
 de.ftood no farther, than the feveral feiences which it 
 reviews and criticifes are previoufly underftood. Ac- 
 cordingly we find, that all the fyftems of logic which 
 
 have not been compiled from a careful review and ex- plained, before his bufinefs, his duty, and his happintfs, 
 amination of the feveral feiences, confilt more of inge- 
 nious iubtleties than of ufeful precepts alTifting to the 
 mind in the various parts of knowledge. And when 
 
 logic lias been learned before the other feiences, the 
 fubftantial parts of it have been fcarce attended to, or 
 made any ufe of, in the profecution of them ; nor fo 
 much as underftood, but in as far as the mind was gra- 
 dually opened, and brought to recoUeft them in its 
 progreis through the feiences. 
 
 " Logic is precifely the fame to philofophy that 
 works of criticiim are to poetry. The rules of criti- 
 cifm are formed by an accurate fcrutiny and examina- 
 tion of the beft works of poetry. To one w!io had 
 never read a poeni, thefe rules would be obfcure and 
 ufelefs ; he could not comprehend them, far leis would 
 lie be able to form a judgment of their jullnefs, and of this, we ought to comply as much as poflible with the 
 
 can be difcovered. Jurifprudence and politics, taking 
 a more complex view of man than morals, by confidtr- 
 irg his various ftates, as well as his nature and ]K)wers, 
 cannot, with any propriety, be introduced till morals 
 have iirft been ftudied. 
 
 " It only remains then to determine whether natural 
 philofophy or pi)e\imatology ought, in the order of 
 teaching, to have the preference. And many confide- 
 rations feem to require that the former fhould be flu- 
 died firft. If it were not, pneuniatology wouM be too 
 tar disjoined from the practical feiences founded on it ; 
 one of which, logic, ought, as we have foen, to be 
 taught laft of all. Belides, \Ve ought always to be- 
 gin with the eafieft and moft obvious fulijefts, and to 
 proceed gradually to the moft diflicult ; and in order to 
 
 the reafons on which they are founded. If one perufes 
 the beft poetical performances, he will acquire fonie de- 
 gree of tafte, though he has never proftlfedly ftudied 
 the rules of criticlfm ; and he wdl, at the fame time, 
 lay in materials, and obtain a flock of examples, which 
 ir.ay render thefe rules iiitelligible to him, and enable 
 liim to judge whether they are juft or not. And by 
 afterwards ftudying thefe rules, he improves, refines, 
 SUPPL. VoL.I. Part II. 
 
 natural openings and progrefs of the human mind. 
 Now it is evident, that the mind receives fii ft of all im- 
 prefTions and ideas of thofe fenlible ihitrgs with which 
 )t is furrounded. It is not till after it has exercifed its 
 faculties about them that it reflefts on its own opera- 
 tions, or acquires perceptions of them. We are from 
 our carlieft infancy accuftomed to obforve external 
 things, though often trauliently and inattentively ; they 
 4T lie
 
 G E R 
 
 [ 698 1 
 
 G E R 
 
 Gerard, lie always in our view, they force ihcmftlves upon us, 
 "■^V— ' and we cannot avoid regarding them more or lefs. But 
 we I'eldom attend to the operations of our minds in our 
 earlier years ; it is late before we acquire dillintt no- 
 tions of them, or can eafily and readily make them the 
 obiefts of our contemplation. Farther, external fenfa- 
 tion, by which bodies are perceived, is a more palpable 
 kind of evidence than internal, from which all our 
 knowledge of fpirits Is derived ; it ftrikes and afFefts us 
 more. The philofophy of fpirits, as well as that of 
 
 foundation to moral virtue ; for virtue mud have beea Gerarrf. 
 praflilcd upon fome ileady principle from the eailicll —— »-— 
 period of human ioclety ; and the mod eminent pro- 
 ttll'or will lind fufiicieut room for the difplay of all his 
 learning and ingenuity in illuftrating the principle which 
 his own judgment has led him to adopt. 
 
 Of this profcffor Gerard was fuJly fenfible ; and 
 whilll he was confcientioufly difcharging his duty to 
 his pupils, he ncglefted no opportunity of improving 
 himfclf. He was member of a literary focicty at 
 
 bodies, is founded folely on experiments and obferva- Aberdeen, of which the refpcdability will not be 
 tions ; but in the latter it is much eafier to make thefe ^ - - - 
 
 than in the former : we can put bodies in any htuatiou 
 that we pleafe, and obferve at leifure their effefts on 
 one another : but the phenomena of the mind are of a 
 lefs conltant nature ; we muft catch them in an inilar.t, 
 and be content to glean them up, by obferving their 
 effefts as they accidentally difcover themfelves in the 
 feveral circumftances of life. The reafonings alfo by 
 which conclufions are deduced concerning mind are of 
 a more abilrufe and difficult nature than thofe employ- 
 ed in the fcience of bodies ; the ideas about which they 
 are converfunt are apter to be confounded v/ith one a- 
 nother, and are with greater difficulty kept ditlinft. 
 
 On all thefe accounts, natural philofophy muft be to tone 
 
 queftioned, when it is known that it confifted of fucll 
 men as the late Dotlors Blackwel, Gregory, Rcid, and 
 Campbell, with Dr Beattie, and many others of per- 
 haps equal talents, though not known to the world as 
 authors (b). This fociety met regularly during the 
 winter, we believe once every forti.ight ; the members, 
 communicated their lentiments with the utmoft free- 
 dom ; every novel npuiion was fuve to be canvaffcd on 
 all fides with impartiality ; the underftandings of the 
 members were thus mutually whetted ; and hence orI« 
 ginated Reid's Inquiry into the Human Mind, Grego- 
 ry's Compiirutive View, Gerard's EJfay on Gtnius, Beat- 
 tie's Ejliiy on Truth, and Campbell's Philofophy of Rhe- 
 
 young minds eafier than pneum.atology, and confequent 
 ly (hould be taught firft." 
 
 For this long digreffion, if fuch it (hall be deemed, 
 we are pcrfuaded that thofe who retain any attachment 
 to the place where their minds were firfl imbued with 
 the principles of fcience, will think no apology requi- 
 fite, when they are informed, that the plan of edu- 
 cation, which is here fo ably defended, was about the 
 fame period adopted by both colleges in the univerfity 
 of Aberdeen ; that the writer of this article had his 
 .own education in the King's college ; and that in the 
 profperity of that college he ftill feels himfclf deeply 
 interefted. Let it be remembered, too, that the pub- 
 lication from which this extradt has been made, fur- 
 nifhes a proof of profeifor Gerard's abilities, and of the 
 
 On the jth of September 1759,- Mr Gerard was or- 
 dained a minifter of the Church of Scotland ; on the 
 nth of June 1760, he was appointed profeffor of di- 
 vinity in the Marifchal College, and minifter of the 
 Grayfriars church in Aberdeen ; and at the fame time, 
 as we fuppofe, created doftor in divinity. 
 
 On the 18th of June 1771 he rellgned his profeffor- 
 (hip in Marifchal College, together with his churclt- 
 living, and was preferred to the theological chair in 
 the univerfity of King's Coll€;re, then become vacant 
 by the death of proteflbr Lumifden. In that ftation 
 he continued, profecuting his ftudies, beloved by his 
 colleagues, and revered by his pupils, till his birth-day 
 I79i ; when, having juft completed his 67th year, he 
 died without a groan. His death was occafioned by a 
 
 eftimatio'n in which he was held by his colleagues at a fchirrous tumor, which began to appear on his fac 
 
 T(ery early period of life; and then furely the digref- hi the year 1794, but without confining hira to the 
 
 fion will not be thought impertinent. houfe, or, except for a very few weeks, interrupting 
 
 He was now profelfor of moral philofophy and logic, his ufual puriuits. It impaired, however, his l-.ealth, 
 
 and of thefe fcienccs alone: but though hh plan of e- and gradually undermined his conftitution. Of this 
 
 ducalion in the Marifchal College ftiews the order in he was very foon fenfible ; but he faw his diffolutioa 
 
 which his leftures were arranged, we have not been approaching with the utmoft compofure and refignation, 
 
 able to learn on what foundation he built his fyftem of and preferved to all about him fo much of that equani- 
 
 ethics. As Hutchefon's Moral Philofophy was then mity and placidnefs of temper which had marked the 
 
 much read and admired, it will not detraft from Mr 
 Gerard's merits to fuppofe, that, with his predeceffor 
 Mr Fordycc, he was an advocate for the moral fenfe of 
 that author ; for there are but three or four founda- 
 tions on which a fyftem of ethics can be raifed ; and it 
 may bedoubted whether there be one of them which is 
 not as old as the age of Plato. ' It would indeed be ri- 
 diculous in any modern (a) to aim at giving a neiu 
 
 whole courfe of his life, that of him may truly be faid,. 
 
 Multls illi multos annos precantibus- 
 Diri carcinomatis veneno contabult, 
 Nexibufque vitx paulatim refolutis, 
 E terris, meliora iperans, emigravit. 
 
 Were we to hazard an opinion of Dr Gerard's intel- 
 le£lual powers, from having attentively peruftd his 
 
 works, 
 
 (a) The friends of Mr Godwin, who affcd to call his Political Juftlce the new philofophy, will, of courfe, 
 think this a rafti affertion ; but were it worth while, it would be no very difficult talk to produce, from the 
 atheiftical writers of anticnt Greece, fomething fimilar even to his wildeft paradoxes. Dr Gerard was too well 
 acquainted with the fubjedt, and too warm a friend to genuine virtue, to pretend to novelty in moral fcience. 
 
 (b) Such as ProfeiTor Thomas Gordon, who read leftures in the King's College for (>% or 64 years, and 
 whofe learning was equalled only by his virtues.
 
 G R R [ Cog 
 
 Gerart!. ivoiki, we would fay that he polTefTcd great reftitude 
 - V ■ of judgment, rather than any remarkable vigour of 
 mind ; that he was capable, by intenfe Itndy, of be- 
 coming matter of almoll-aiiy fiibic(ft, though pi rhaps he 
 had not the imagination reqiiifite for making dilcoveiies 
 in fcience ; and that his attainments were folid rather 
 than brilliant. What he knew, he knew thoroughly ; 
 but to us his knowledge feems to have been the reward 
 of labour. 
 
 By one, to whom he was well known, and who 
 Dr 5;.'/- himfelf (lands high in the republic of letters*, we are 
 '• affiired that he had improved his memory to luch a de- 
 
 gree, that, in little more than an hour, he could get 
 by heart any fermon of ordinary length ; though tar 
 from availing hiraUlf of this talent, as many would 
 have done, he compoled with care all the fermons that 
 he preached. In early lite he made it a rule not to 
 ftudy after fupper ; and frum that rule he never deviat- 
 ed, but amufed himfeli after that time, either with the 
 converfation of his family, or with any light reading 
 that came in his way ; and he was generally in bed bv 
 half pall eleven. He feenis not to have approved of 
 early more than of late ftudy ; for though, for a few 
 years, when as profelTor of philolophy he had various 
 fciences to teach, he rofe regularly, during winter, at 
 five in the morning, he difcontinued that practice as 
 foon as he had it in his power, and did not enter upon 
 ferious lludy till after breakfaft, generally about ten 
 o'clock. He was indeed very laborious through the 
 day, and could with difficulty be perfuaded to take 
 any bodily exercife ; but being remarkably temperate 
 in eating and drinking, he enjoyed very good health, 
 which was only occalionally interrupted by thofe Ito- 
 niach complaints, to which men of fedentary lives are 
 often fubjett. 
 
 The fruits of this inceflant ftudy were, befides the 
 leftures which he read to his different clafTes, i^, .Vn 
 EJj'ay on Tajie, to which, in 1756, was adjudged the 
 gold medal by the Philofophical Society of Edinburgh 
 (See Societies, Encycl.), which had propofed tafte as 
 the fubjedt for a prize. Of this eflay there has been 
 a fecond, and a third edition ; of which the laft, which 
 was publilhed in 1780, is confiderably enlarged and 
 improved, td, Dijfertations on the Genius and Eviden- 
 ces of ChriJUanity, publilhed in 1766. 3</, An FJJliy on 
 Gf^iuj-, publilhed in 1774. ^//j, Two volumes of i^fr- 
 mons ; of which the firft was publilhed in 1780, and 
 the fecond in 1782. j/A, A part of his theological 
 courfe, entitled The Pajloral Care, which was publilh- 
 ed in 1 799 by his fon Dr Gilbert Gerard, who fuc- 
 ceeded him as profeffbr of divinity in the King's col- 
 lege and univerlity of Aberdeen. Befides thefe works 
 Dr Gerard publilhed many tingle fermons, which were 
 preached on occaiional fulijefts. 
 
 Of this amiable and refpettable inftruAor of youth, 
 
 we have been favoured with the following character, 
 
 7 '''^^^^" ^y * '"^^ °f talents and virtue f , who was firtt 
 
 ^'oidA- '"^ pupil and afterwards his friend ; and though it 
 
 «n. made part ot a funeral fermon, we believe that, by 
 
 thofe who were nioft intimately acquainted with Dr 
 
 Gerard, the panegyric which it contains will not be 
 
 deemed extravagant. 
 
 " In domeftic life, his conduft was amiable and ex- 
 emplary. He poflefled, in a high degree, that kindnefs 
 of heart and affability of manner which interefted him 
 
 G E R 
 
 at all times in the happinefs of hij dependants, prefer, 
 vcd good humour in his houfe, and endeared him to his ' 
 family. He knew how to thick improprieties with- 
 out hardincfs, and when and how to indulge without 
 impairing his authority. His natural good Itnfe, ftea- 
 dinels, and prudence, prevented him from being thrown 
 into confulion by the advcrfe incidents of life ; and e- 
 nabled him, in preiring emergencies, to adopt wile 
 mealuns, and to aamiiiifter falutaiy counfel. His ten- 
 der fympathy loothtd the troubled hour of forrow ; 
 his rational and friendy advice guided his family thro' 
 the perplexities of life, and he feelingly rejoiced in all 
 their innocent eiijoymejits. His attachments were not 
 confined to his family or his relatives; he was fufcep- 
 tible of warm friendlhip. In felc<iting the ohjetts of it 
 lie was cautious, always preferring tiiofe whole merits 
 entitled them to confidence ard regard. His attach- 
 ment, flowly formed, was not to be fhnkcu by every 
 oblique inlinuation, or by every idle report to the pre- 
 judice of his friend. Steady in his profeflioMS of re- 
 gard, he was capable of conliderable and difiiitercfted 
 exertions to ferve thofe whom he really citeemed. To 
 his judicious advice they had ready accDS ; and his bell 
 efforts to promote their go(jd tliry could always com- 
 mand. As a member of fociety, his houfe was ever 
 the feat of hofpilality, and his door was always open 
 to the ftranger. In entertaining his friends, he equal- 
 ly avoided the extrpvagancc and oftentation which did 
 not become his character or tuit his foitune, and the 
 rigid economy wl^ich marks the conduft of thofe who 
 give with a reluftant and fparing hand. He neither 
 anxioufly couited, nor aflcCtedly (hunned lcan:ed con- 
 verlation. While he never obtruded upon conipmy 
 fubjeCts which, by the ditplay of fuperior knowledge 
 or abilities, vyere calculiited to gratify his own vanity 
 at the expence of hurting others, he always ftudied, as 
 far as propriety would admit, to adapt lifs converfa- 
 tion to the temper and inclinations of his alfucfates. 
 To pleafe the young, and to promote their harmlefs 
 feftivity, was ever his delight ; with chcerfulncfs he de- 
 fcended to their trivial amufements, and in his prefence 
 they felt no reftraints but thofe which virtue and de- 
 cency iinpofe. Though he often left for a little ftu- 
 dies in which lie was keenly engas::ed, to enjoy the con- 
 verfation of a friend, he never liiffered his love of fo- 
 ciety, one of his ilrongeft paflions, to induce him to 
 facrifice any important literary purfuit, or to negleCl 
 any neceftary buiinefs. 
 
 " As a clergyman, the ofEce which he held for feve- 
 ral years in Marifchal college rendered it his duty to be 
 a daily preacher, and g?.ve him a feat in the ecclefuiftical 
 courts. But the unavoidable labour of preparing pre- 
 ledions tor his theological pupils, did not prevent his 
 unremitting attention to his public exhibitions in the 
 pulpit. Thefe were marked by that dillinclnefs of 
 arrangement, that juftnefs of reafoning, and that accu- 
 racy of compofition, which effedtually fccured the ap- 
 probation of the ableft judges ; while by their plain- 
 nefs and fimplicity, they failed not of promoting the 
 edification of the meanetl capacities. To the low arts 
 of acquiring popularity he never ftooped : But his 
 prudence, his good fenfe, his exemplary condud, and 
 his minifterial diligence, eftabliflied his refpedability 
 and ufefulnefs, and procured him the full confidence 
 and efteeni of his colleagues Poffefling more than or. 
 4 T 2 dinary 
 
 O'rard.
 
 G E R [ 700 ] G E R 
 
 CerarJ. dinsrv excrllence, envy never led him to depreciate tlie tion, he enjoined no duty which he was unwilling to Gtrmia*. 
 
 "■~^' merits of other preachi.rs. Though one ot tlie bell of excmphfy in his own conduct. Hence that ilridt re- ^ """• 
 
 judges, he was always one of the moll candid hearers, gard to the minifterial charafter which he uniformly " 
 
 When by his tranilatiou to the univerfity of King's diljilayed, and hence his uncommon pundtuahty in at- 
 
 collegc he was releaied from the labour of conitant tending the public ordinances of religion." 
 
 preaching, far from fhewing any averGon to dilcharge GERMINATION, among botanifts, is a vei-y in- 
 
 the mod public minlltcrial duties, he was always obe- terelling iubjitt, on which the late difcoveries in che- 
 
 dient to prcfliyterial appointments ; and while health mlftry have thrown much light fmce the article Ger- 
 
 and ftrength remained, willing to obhge his clerical mination was publifhed in the Encydopedia. In the 
 
 friends by appearing in their pulpits. Nor in private year 179^, Mr Humboldt difcovered that fimple me- 
 
 llfe did he ever lofe fight of the charafter of a clergy- tallic iubltances are unfavourable to the gerrtiination of 
 
 man. Having iu a pulilication ably defended its re- plants, and that metallic oxides favour it in proportion 
 
 fpedlability, in oppcfition to the icotfs and fneers and to their degree of oxidation. This difcovery induced 
 
 fophifms of modern fceptics ; he conlidered it as his him to fearch for a lubftance with which oxygen might 
 
 honour, in his life and converfation, to difplay its dig- be to weakly combined as to be eafily feparatcd, and 
 
 nity and importance ; and to fliew that the j{ravity of a he made choice ot oxigenated muriatic acid gas mix- 
 
 Chriftian paftor is perfectly confiftent with the good ed with water. CrefTes {^lepiaium fati'vum) in the oxy- 
 
 bleeding of a gentleman, and with the cheerfuhieis, af- genated muriatic acid fliewed germs at the end of fix 
 
 fability, and eafe of an agreeable companion. hours, and in common water at the end of 32 hours. 
 
 " As a man of letters, his attainnunts were far above The aCtion of the firft fluid on the vegetable fibres ia 
 
 thofe at which the generality of Iludents arrive. In announced by an enormous quantity of air bubbles 
 
 itis literary purfuits, he had all the advantages of a w liich cover the feeds, a plienomenon not exliibiled 
 
 ' iudgment uncommonly clear and dillinft; aided, from by water till at the end of trom 30 to 45 minutes, 
 his earlicll years, by the molt indefatigable and perfc- Thefe experiments, announced in Humboldt's Flora 
 vcrinf ihidy. The well-earned reputation with which, Subterranca Fribergenjis, and in his Aphoiifms on the 
 before he was promoted to the theological chair, he chemical phyliology of Plants, have been repeated by 
 laucrht in Mariichal college different fcicnces, incon- others (a). They were made at a temperature of from 
 teftibly proves that his powers, not confined to one fub- 12 to 15 Reaumur. In the fummer of 1796, Hum- 
 jeft, juftly entitled him to eminence in feveral branches boldt began a new feries of experiments, and found 
 of literature. His publications, feveral of which have that by joining the ilinmlus of caloric to that of oxy- 
 been tranflated Into other languages, promife fair to ex- gen he was enabled ftill more to accelerate the pro- 
 tend his fame, and to hand it down to generations yet grefs of vegetation. He took the feeds of garden 
 unborn ; and his imremltting labours promifed ftill a far- ciefTes i^lepldium fativum), peas [pifum falivum), French 
 ther contribution to the general ilock of learning. heans [phafeolis 'vulgaris), garden [cuuce (/lUluca fati- 
 " As a profeiTor of divinity, he will be long and grate- , ■z'rt^, mignonette (rf/ti/a oi/orfl/a) ; equal quantities of 
 fully rcuiembered by his numerous pupils. This was which were thrown into pure water and the oxygena- 
 hls peculiar department, and in this he flione. Pofief- ted muriatic acid at a temperature of SS^ F. CrefTes 
 img large ftores of theological knowledge, he was ju- exhibited germs in three hours in the oxigenated mu- 
 diclous in feledting his fubjetls, happy and fuccefstul riatic acid, while none were feen In water till the end 
 in his manner of communicating inflruftion. He had of 26 hours. In the muriatic, nitric (b), or fulphuric 
 the merit of introducing a new, and in many rel'pedts a acid, pure or mixed with water, there was no germ at 
 better plan of theological education, than thole on all : the oxygen feemed there to be too intimately unlt- 
 which it had been formerly conduced. Liberal, but ed with bales of azot or fulphur, to be difengaged by 
 iidt loofe, in his fentiments, his great aim was, not to the affinities prefcnted by the fibres of the vegetable, 
 impofe by his authority upon his pupils any favourite The author announces, that his difcoveries may one 
 fvllem of opinions ; but to imprefs them with a fenfe day be of great benefit in the cultivation of plants, 
 of the Importance of the niinillerial office, to teach them His experiments have been repeated with great induf- 
 the proper manner of difcharging all its duties, and to try and /.eal by feveral diltinguilhed philolophers. Pro- 
 enable them, by the knowledge of 'Scripture, to forma ftflor Polil at Drefden cauftd to germinate In oxyge- 
 jufl and impartial judgment on controverted fobjecTts. nated muriatic acid the feed of a new kind of eiipljorbia 
 Solicitous for their Improvement, he was ever ready to taken from Bocconi's coUedlion of dried plants, no or 
 encourage rifing merit by his warmell approbation ; and 120 years old. Jacquin and Vaiider Scliott at Vienna 
 rcluftant to damp even unfuccefsful efforts of genius threw into oxygenated muriatic acid all the old leeds 
 by deferved cenfure. Having a conllant eye to what which had been kept 20 or 30 years at the botanical 
 is praftically ufeful, rather than to unedifying fpecula- garden, every attempt to produce vegetation in which 
 
 had 
 
 (a) See Uflar's Fragments of Phytology, Plenck's Phyfiology, Vllldenow's Dendrology, and Dinionnaire de 
 Fhyfique par Gehler. 
 
 (b) The nitric acid, however, diluted with a great deal of water, accelerates germination alfo, according to 
 the experiments of CandoUe, a young naturallfl, who has applied with great fuccefs to vegetable phyfiology. 
 This phenomena is the more interefting, as chemiftry affords other analogies of the oxygenated muriatic acitJ 
 and the nitric acid. ProfefTor Pfafs at Kiel, by purfuing Humboldt's experiments, has found that frogs luftoca- 
 ted in oxygenated muriatic acid gas increafe in irritability, while thofe which perifh in carbonic acid gas are left 
 feniible of galvanifm.
 
 G H E r 7or ] G H E 
 
 hnd l)eon fruitlefs, :in(l the greater part of tlieiu were Briquas ami Eremas, whom they confider as tribes of Chsyfi;- 
 llimiilated witli fiioccfs. f^ven" the hardcit Icids yield- CalFrcs. ^'*'- 
 
 J ed to this agent. Among thole which gernilinitcJ \\''ith refpeft to fuch charafteriftics as are not ori- ''~~' 
 
 were the yeUow bondiic or nitkar tree {^guilandina giual and derived from nature, as the form of their 
 hnJuc), the pigeon cytifus or pigeon pea (cyli/us ca- dreis, weapons, inllrunients of nnifie, foiidnefs for liiint- 
 j/jn), the dodonea angujlifolia, the climbin;; miinufa (wt- ing and dancing, and the h'ke, the GlieyfTiquas do not 
 nofa fcandeiis), and new kinds of the hamea. — There differ from the iurrounding nations, except in having- 
 are now {hewn at Vienna very valuable plants which adopted a particular colour for tlieir ornaments. All 
 Ere entirely owing to the oxygenated muriatic acid, the ornaments of the Ghcviriqiias are white, and com- 
 and'which are at prefent from hve to eight inches in pufcd of the bonis of a fliecp's leg or foot, to which 
 
 they give a dazzling whitenefs by proctffes peculiar to 
 themftlves. Thus, as they fabricate their own neck- 
 laces and other articles ot luxury, and have no occafiou 
 to purchafe the materials, they have no dependence ou 
 the colonies with rcfpect to trade, except for a few ne- 
 ceflary articles, which they want in common witli o- 
 ther favages. Accordingly this nation is lefs known 
 and lels viiitcd than any otlier. 
 
 Tlie women are well made, lively, and always ready 
 
 lieight. Humboldt eauled to germinate the chtjla ro- 
 fea, the feeds of which had been brought from the Ba- 
 hama iflands by Buofe, and which before had refitted 
 every eftort to make them vegetate. For tliis pur- 
 pofe he employed a new procefs, which feems likely to 
 be much eafier tor gardeners who have not an oppor- 
 tunity of procuring oxigenated mftiiatic acid: He 
 formed a patte by mixing the feeds with the biack 
 oxide of manganefe, and then poured over it tlie nm- 
 
 riatic acid diluted with water. Tinee cubic inches of to laugh or dance : yet, with all the gaiety of their dif- 
 
 water were mixed with half a cubic inch of the mu- pofition, they have the refcrvednefs of manners to which 
 
 riatic acid. The vefiel which contains this mixture polilhed nations give the names of inodelly and deco- 
 
 mu(l be covered, but not clofely fhut ; elfe it might rum, and which, in fo warm a climate, and with lucli 
 
 leadily buril. At the temperature ot 95" the muriatic ardent conftitutions, appears to be a virtue of no cafy 
 
 acid becomes ftrongly oxidated ; the oxigenated muria- attainment. 
 
 tic gas which is difengaged paffcs through the feeds; Our author fays that he no where met with a nation 
 
 and it is during this paifage that irritation of the vege- fo truly geneious. Thougii he had nothing to give in 
 
 table nbrfs takes place. — Ph'tlofopbical Miigtiz'we. exchange, yet during two diiys that lie llaid with thenj, 
 
 GESCHE EL AuBE, or GiR GiR,a fpecies of grafs he had bowls ot miik brouglit to him as prefents, night 
 
 growing plentifully near Ras el Feel on the borders of and morning, from every hut. The chief even obliged 
 
 Abyflinia. It begins, fays Mr Bruce, to fhoot in the him to accept a lamb ; and though our traveller's al- 
 
 end of April, when it firll feels the iuimidity of the air. teiidjints were not dcllitute of provifions, he would give 
 
 It advances then fpeedily to its full height, which is them alfo feveral fhccp with which to regale theuilclves; 
 
 about 3 feet 4 inches. It is ripe in the beginning of a degree of generosity of which a proper tftimate can 
 
 May, and decays, if not deftroyed by fire, very foon af- be formed only by thofe who know foincthing of favage 
 
 terwards. manneTs and favage penury. 
 
 The leaf is long, pointed, narrow, and of a feeble The practice of femi-callration prevails among the 
 
 texture. The ftuck from which it flioots produces 
 leaves in great abundance, which foon turn yellow and 
 fall to the ground. The goats, the orily cattle thefe 
 miferable people have, are very fond of it, and for it a- 
 batidon all other food while it is within their reach. 
 On the leaves of loine plants our author faw a very 
 
 Gheyffiquas, and among them only of all the Hulten- 
 tot tribes ; and it prevails in all their hordes without 
 exception. Our author convinced himl'clf of this faC> 
 by his own eyes ; for the men were fo compbifant, 
 that, if he had chol'en, he might have iiifpe(;ted the 
 whole horde. Many travellers liave written ujjon the 
 
 fmail glutinous juice, like to what we fee upon the fubjeft ot this vvhimhcal operation ; but they do not 
 
 leaves of the lime or the plane, but in much lefs quan- agree either as to its origin, the motives that lead to 
 
 tity ; this is of the tade of fugar. , its invention, or the nations by whom it is pradlifed. 
 
 From the root of the branch arifes a number of ftaiks, Kolben, who fays that it commonly conlifts in the ex- 
 fomctimes two, but never, as far as he had feen, more traCtion of the left tefticle, rejirefents it as a religious 
 than three. The flower and feed are defended by a ceremony, a general and facrccl law, with all the Hot- 
 wonderful perfeftion and quantity-cf fmall parts. The tentots indilcriminately ; but this is unqueftionubly 
 head, when in its maturity, is of a purplifh brov.n. falfe. (Sec Hottentots, /.'nrjit/. ) Others attribute 
 
 This fpecies of grafs was one of the acquifitions of it to the dellre of the GheyfTupias to render themfelv.-s 
 
 our author's travels. It was not before known in Eu- more fleet in ruiiiiiiig, an effcCl which it furtly is nut 
 
 rope, nor when he publiflied his liook had the feed 
 jiroduced a plant any where but in the garden of the 
 French king. 
 
 GHEV,SSiQI.TAS, a nation of Hottentots wliich 
 inhabits a diftrift of South Africa bordering on the 
 country of C:ifrraria. M. Vaill.mt vilittd a horde of 
 
 calculated to produce ; and fonie have laid that its in- 
 tention is to prevent the too abundant propagation of 
 the fpecies. Vet Kolben, though he I'cems inclined to 
 this laft opinion, affirms that twins are not the Icfi 
 common on account of tlie operation. According to 
 thofe whom M. Vaillant qiiellioned on the fubjirct, it 
 
 this people at no great dilfance from Orange river, as is merely a mark of ditlintlion, wliich tlicir anccilors, 
 
 he was returning from his hilt African excurlion to the being at war with the neighbouring nations, invented 
 
 Cape, and was fhewn by them a chain of mountains to for the purpofe of knowing one anotlier ; but, as he 
 
 the eaft, which extending to a diltance was loft in the himfeif admits, this is a very improbable account of tiie 
 
 north, and which, inhabited by their principal tribes, matter, as they would furely have adopted, like the 
 
 feparatcd them from the Caffics, or at lead from the Loangccs, Pomboes, and Corar!a::tins, marks of di{lir.c« 
 
 tioa
 
 G H I [7 
 
 Chiicii p. lion move eafily difcerned. Be this as it may, the ope- 
 • ration among the Ghtyfiiquas ii peiformed by the fa- 
 ther, commonly at the birth of the child, though fome- 
 times not till he has compltttJ his third year. 
 
 GHIRGONG, the capital o( ^fam in Hindoftan, is, 
 Pennaat't acc"'"'li'ig t^> Mr Pennant, fituated in latitude 26" ^o' 
 yuiu of north. He does not (late its longitude. It has four 
 HiniaHjn. gates, and the city is cncompaflcd with a bound hedge 
 of bamboos. The Rajah's palace is furrounded by a 
 caufey, planted on each fide with a clofe hedge of 
 bamboos, which ferves inftead of a wall. On the out- 
 fide there is a ditch, which is always full of water. 
 The Rajah's feat is adorned with lattice work and car- 
 ving. Within and without have been placed plates of 
 brafs, fo well poliflied, that when the rays of the iun 
 ftrike upon them they fliine like mirrors. It is an af- 
 certained fa£l, that 3000 carpenters and 12,000 la- 
 bourers were conftantly employed in this work during 
 two years before it was tiniflied. 
 
 The Afiatic Refearchcs fpeak much of the wealth of 
 Afam, and of the plenty and excellency of its natural 
 productions, and that it abounds in all metals but tin. 
 Gold is found in every part of the country by wafhing 
 the fand of the rivers, and is one of the fources of re- 
 venue ; 12,000, fome fay 20,000 people, are employed 
 in that work, each of whom has from the Rajah cer- 
 tain wages. Its gum lac is excellent, and it is very 
 produdlive of filk. 
 
 Among the fruits which this country produces are 
 mangoes, plantains, jacks, oranges, citnms, limes, pine 
 apples, and pniiiala, a fpecies of tamarind, which has 
 fuch an excellent flavour, that every perion who taftes 
 it prefers it to the plum. There are alfo cocoa nut 
 trees, pepper vines, and areca trees. The fugar cane 
 excels in foftnefs and fwettnefs, and is of three colours, 
 red, black, and white. There is ginger free from fibres, 
 and betel vines. The ftrength of vegetation and fer 
 tility of the foil are fuch, that whatever feed is fown 
 or flips planted they always thrive. The environs of 
 Ghirgong fiirnifh fmall apricots, yams, and pomegra- 
 nates ; but as thefe articles are wild, and not aflifted by 
 cultivation and engrattmcnt, they are very indifferent. 
 The principal crop in this country confills in rice and 
 lentiles. Wheat and barley are never fown ; lignunn 
 aloes is alfo a produftion of this country. The filks 
 are excellent, and refemble thofe of China, but they 
 manufadilure vei-y few tno'e than are required for ufe. 
 They arc fuccefsful in embroidering with flowers and 
 in weaving velvet. — One of their great forcfts is inha- 
 bited by abundance of elephants : 6 or 700 may be ta- 
 ken in a year, but they are neglefted by the natives, 
 who have neither horfcs, camels, nor affes, fuch as are 
 brought from other countries. 
 
 According to our author, " the people of Afam are 
 a bafe unprincipled nation, and have no fixed religion. 
 They follow noiule but that of their own inclination, 
 and make their own vicious minds the teft of the pro- 
 . pricty of their aftions. They do not adopt any mode 
 of worftiip praftifed cither by heathens or Mahomc- 
 dans, nor do they concur with any of the known fefts 
 which prevail among mankind ; unlike the pagans of 
 Hindoftan, they do not rejeft viftuals which have been 
 drefled by Moflems, and they abftain from no fleflr ex- 
 cept human. They even eat animals that have died a 
 natural death." 
 
 02 ] 
 
 G I B 
 
 On this palTage, one of the ableft of our literary j.itir- 
 nalills oblerves, tiiat in jultice to the people of Afam, 
 we murt remark, that the above account, cxtracleii 
 from the memoirs of Mir Jumla's expedition into that 
 country, was compofed by a rigid Maliomedar, at the 
 court of that fanatical tyrant Aurengzebe. The au- 
 thor and his mailer faw, in the Ahnnefe, only idola- 
 ters ; and, in idolaters, the meanell of mankind. Their 
 diet, though lefs reftrifted than that of the Hindoos of 
 Bengal, is by no means promltcuous; and their reli- 
 gion does not in any way difi^er from that of Hindof- 
 tan, — as might eafily be proved by their coins, infcrib- 
 edwith the names of Hindoo deities. 
 
 GIBBON (Edward, Efq.). the celebrated hiSorian 
 of the Decline and Fall ot the Roman Empire, was 
 born at Putney in the county of Surrey on the ;7th of 
 April 17^7. He was the firft child of the marriage of 
 Edward Gibbon, Efq; and Judith Porten, the youngefl 
 daughter of a merchant ot Ijondon. 
 
 The family of Gibbon appears to be ancient and ho- 
 nourable ; and our aut-iior delights to trace his pcdigice 
 from John Gibbon architcfl to King Edward III. who 
 poflefled lands in the hundred and parilh of Rolvenden, 
 -in the diftritt which is now called the Weald of Kent. 
 In that dillridt the elder branch of the family ilill ad- 
 heres to its native foil, without much increafe or dimi- 
 nution of property ; but the fortunes of the younger 
 branch, from which fprung the fubjeft of this memoir, 
 were flud:uating. It is not, however, with his family, 
 but with himfelf, that we are <roncerned. 
 
 So feeble was his conllitution, and fo precarious his 
 life during hischildifh years, that at the baptifm of each 
 of his brothers (and they were five in number) his fa- 
 ther's prudence lucceffivcly repeated the name of Ed- 
 ward, that, in cafe of the death of the eldeil fon, this 
 patronyniick appellation might Hill bejjcipetuated in the 
 family. His brotliers and a filler were all fnatched away 
 in their infancy ; and, in terms of afteciionate gratitude, 
 he attributes his own prelervatioii to the more than ma- 
 ternal care of a maiden aunt, his mother's eldeil fifter. 
 " Many anxious and folitary days (fays he) did that 
 dear and excelleiv. woman confume in the patient trial 
 of every mode of relief and amufement. Many wake- 
 ful nights did flie fit by my bed-fide in trembling expec- 
 tation that each hour would be my lall. Suffice it to fay, 
 that while every praAitioner from Sloane and Ward to 
 the Chevalier Taylor was fucceflivcly fummoned to tor- 
 ture or relieve me, the care of my mind was too fre- 
 quently negletlcd for that of my health. Compaffioii 
 always fuggeftcd an excufe for the indulgei.ce of the 
 mailer, or the idltnefs of the pupil ; and the chain of 
 my education was broken as often as I was called from 
 the fchool of learning to the bed of ficknefs." 
 
 His education feems indeed to have been far from 
 fyflematical. At the age of feven he was delivered in- 
 to the hands of Mr John Kirby, who exerciied about 
 eighteen months the office of his doraeflic tutor, and of 
 v/hom he writes in terms of refpeft. This man had 
 been an indigent curate in Cumberland, and when for- 
 ced by diftrefs to leave his native country, he was in- 
 troduced by his learning and his virtue to the family of 
 Mr Gibbon, from whom he might have found at lead 
 a temporary ftielter, had not an aft of indifcretion again 
 driven him into the world. One day reading prayers 
 in the parifh church, he moft unluckily forgot the name 
 
 of
 
 GIB [7 
 
 of King George ; and his patron, a loyal fubjeft, chf. 
 mifTcd him with fome reluctance and a dectnt reward. 
 As our author dtfcribes his anceftors as hL-rcditary" To- 
 ries, and fonie of them as Jacobites, wc think, it not im- 
 probable that Mr Kirby may have been accuftomed to 
 oinit the name of the King when reading prayers in the 
 family ; for ollicrwife he wonld have pronounced it me- 
 chanically in the church. 
 
 Be this as it may, our author, upon the difniifllon of 
 Jiis tutor, was feiu to Kingfton upon i hames, to a 
 fjchool of fevcnty boys kept by DrWuoddefon and his 
 afliftants. Hedoisnot reprtfcnt hinifelf either as happy 
 or as having made great progrcfs at that fchool. The 
 want of llrength a- 1 activity difquahTied him for the 
 fports of the held ; his companions reviled him for the 
 fms of his Tory anceftors ; and his iludics were fre- 
 quently interrupted by ficknefs. After a real or no- 
 minal refidence of near two years at Kingllon, he was 
 finally recalled (Dec. 1747) by the death of his niother. 
 By this time he was well acquainted with Pope's Ho- 
 mer, the Arabian Nights Entertainments, Dryden's 
 Virgil, and a tranflation of Ovid's Metamorphofes ; and 
 the entertainment which he received from theic books 
 gave him a talle for defultorv reading. 
 
 After living a year with his maternal aunt, during 
 ■which period he read many books on religious fubjetts 
 too deep for the comprehenfion of a boy, he was in Ja- 
 nuary 1749 entered in Wellminiler fchool, of which 
 Dr John NlchoU was at that time head matter. " There 
 (fays he) in the fpace of two years, interrupted by dan- 
 ger and debility, I painfully climbed into the third 
 form; and my riper age was left to acquire the beauties 
 of the Latin and the rudiments of the Greek tongue. 
 Inftead of aiidacioufly mingling in the fports, the quar- 
 rels, and the connexions of our little world, I was itill 
 cheiidied at home under the maternal wing of my aunt, 
 who now lived in CoUege-ilree t ; and my removal from 
 Weftminfter long preceded the approach of manhood." 
 
 He was firil carried to Bath for the recovery of his 
 health; then to Winchefter, where he lived in the houfe 
 of a phyfician ; then to Bath again, where lie read with 
 a clergyman fome odes of Horace and fome cpifodes of 
 Virgil; after which an unfucccfsful trial was made to re- 
 new his attendance at Weftminfler fchool. " It might 
 now be apprehended (fays he) that I fhould continue 
 for life an illiterate cripple; but as I approached my 
 fixteenth year, Natuie difplayed in my favour her my- 
 llerious energies: my conftitution was fortified and fixed; 
 and my difordcr* Inftead of growing with my growth, 
 and ftrenglhening with my ftrength, nioft wonderfully 
 vaniftied." In confequence of this he was carried to 
 Oxford ; and before he had accompliftied his fifteenth 
 year, was, on April ;. 175c, matriculated a gentleman 
 commoner of Magdalen college. 
 
 For the honour of that celebrated nniverfity, we 
 would fain hope that the account which Mr Gibbon 
 gives of Magdalen college is greatly exaggerated. He 
 reprcfents his tutors as totally regardlefs of his morals 
 or his ftudies. Speaking of the firft and beft of them, 
 for he had two, he fays, " No plan of ftudy was recom- 
 mended for my ufe ; no exercifcs were prefcribed for his 
 infpedlion ; and, at the moft precious feafon of youth, 
 
 03 ] GIB 
 
 whole days and weeks were fuffered to elapfe without Olbbon. 
 labour or amufemcnt, without advice or account." We """"V""" 
 fhall make no other remark on this paffage, than that 
 from gentlemen, who mull have been contemixirary 
 with Mr Gibbon at Magdalen, we have received differ, 
 ent accounts of the college ; and it is furely a very fin- 
 gular circuniftance, that at this period of idlenels, our 
 author lliould have become enamoured of Sir John 
 Marfliam's Canon Chronicus, and have conceived the 
 idea of writing an EJjay on ihc age of S^J'Jlr'is. Such, 
 however, was the cafe. Not only was the elTay plan- 
 ned, but pait of it was written ; and though he never 
 finilhed it, he declares, thai his folulion ot fome difli- 
 culties in chronulc>gy was not devoid of ingenuity ; but 
 he goes on to vilify Oxford. " It might at leaft be tx- 
 pet^ed (fays he), that an ccclefiaftical fchool Ihould in- 
 culcate the orthodox principles of religion. But our 
 venerable mother had contrived to unite the oppofite 
 extremes of bigotry and indilfcrcnce : an heietic, or un- 
 believer, was a monller in her eyes ; but ^i\^ vi\is altuays, 
 or oftrn, o\- fumet'imes (a), remifs in the fpiritual educa- 
 tion of her own children. Without a fingle ledure, 
 either public or private, either Chriftian or Proteftant, 
 without any academical fubfcriplion, without any E- 
 pifcopal confirmation, I was led by the dim light of my 
 catecliifm to grope my way to the ehapel and commu- 
 nion table, where I was admitted without a queftion, 
 how far, or by what means, 1 might be qualified to re- 
 ceive the facrament. Such almoft incredible negleA 
 was prodiLftive of the worft mifchiefs. From my child- 
 hood I had been fond of religious difputation ; nor had 
 the elaftic fpring been totally broken by the weight ot 
 the atniofphtre of Oxford. The blind adiivity of idlenefs 
 urged me to advance without armour into the dangei- 
 ous mazes of controverfy; and, at the age of fixteen, 1 be- 
 wildered myfelf in the errors (.f the church of Rome." 
 Thus anxious is our author to account for his recon- 
 ciliation to the Romifti church by the negligence of the 
 tutors of his college. This event took place on the 8th 
 of June 1753, when, at the feet of a priell in Eondon, he 
 folemnly, though privately, abjured the errors of herefy. 
 An elaborate controverfial epiiUe, approved by his direc- 
 tor, and addrcfled to his father, announced and juftified 
 .the ftep he had taken ; and the old gentleman, in the firlt 
 fally of paflion, divulging the fecret, the gates of Mag- 
 dalen college were fluit againft the convert. It was ne- 
 ctflary therefore to form a new plan of education ; and 
 our young Catholic, by the advice of Mr Eliot (after- 
 wards Lord Eliot), was fettled, on the 30th of June,, 
 under the roof and tuition of Mr PaviUiard, a Calvinill 
 miniiler at Laufanne in Switzerland. 
 
 He reprefents his fituation there as at firfl extremely 
 uncomfortable. He could not avoid eontrafting a fmail 
 chamber, ill contrived and ill furniflied, with his elegant 
 apartment in Magdalen college ; and M. PaviUiard be- 
 ing entrufted with the management of his expences, he 
 felt himfelf degraded from the rank of gentleman com- 
 moner to that of a fchool-boy. He began, however, 
 gradually to be reconciled to his fate ; and his love of 
 reading returned, which, he fays, had been chilled by 
 the air of Oxford. He rapidly acquired the French 
 language ; and of his tutor he fays, " My obligations 
 
 to 
 
 (a) Surely altvayt t^ni fometlmes are words of very, different import : why are they ufed then, in this fentence, 
 as fynonymous ?
 
 GIB [ 704 
 
 ■CiMion. ta the leiTons of Mr Pavilliard fjratJtudc wiU not fiifiVr 
 " ' '•~~~ mt to foiget. He was endued with a clear head and a 
 warm heart ; his innate benevolence had afTnagcd the 
 fpirit of the church ; he wis rational, becanfe he was 
 moderate : in the courfe of his lludies, he had acquired 
 « jiift, though fuperficial knowledge of mod branches 
 of literature ; bv long practice he was billed in the arts 
 of teaching ; and he laboured with alUduoiis patience to 
 ■know the charafter, gain the aifeftion, and open the 
 mind of his Englifh pupil." 
 
 Under the tuition of this amifible preceptor he dc- 
 fcribes his progrefs in the French and Latin cla'Tirs, in 
 hillory, geography, logic, and inetaphyfics, aa nncom- 
 nioiily rapid; and he allows to thejame man a hand- 
 ■fome fliare of the honour of reclaiming him from the 
 errors of popery. The various difcriminating articles 
 ijf the Romifh creed difappeared like a dream ; and, af- 
 ter a full conviftion, on Clirillmas day 175^, he recei- 
 ved the facramcnt in the church of Laufanne. Thus 
 had our author communicated with three different io- 
 cieties of Chriflians before the completion of his eigh- 
 teenth year; and as fuch changes from church to church 
 are always dangerous, we need not wonder that, in a 
 mind fo ill-fnrniihed as Mr Gibbon's then was /or the- 
 ■ological inveftigations, they paved the way for his laft 
 change to Deifni. At prefent, however, he fufpenJed 
 his religious inquiries, acquicfcing (as he fays) with im- 
 plicit belief in the tenets and myftcrits which are adopt- 
 <d by the general confent of Catholics and Protcllants. 
 He continued to profecute his ftudies with ardour. 
 Under Mr Pavilliard he learned the Greek alphabet, 
 the grammar, and the pronunciation of the language 
 according to the French accent, and foon made himfelf 
 mafler of the works of Homer, Herodotus, and Xeno- 
 phon. During two winters he attended the private lec- 
 tures of M. de Traytorrens, wlio explained the elements 
 of algebra and geometry as far as the conic feftions of 
 the Marquis de l'H6pital ; but in mathematics he was 
 content (he fays) to receive the paffive imprefGon of his 
 profeffor's leftures, without any aftive exercife of his 
 own powers. In the writings of Grotius and Puffen- 
 dorf he ftudied the duties of a man, the rights of a ci- 
 tizen, the theory of jullice, and the laws of peace and 
 war, which have had fome influence on the practice of 
 modern Europe. •' Locke's treatife on government 
 (fays he) inilrufted me in whig principles, which are 
 founded rather in reafon than experience ; but my de- 
 light was in the frequent perufal of Montefquieu, whofe 
 energy of ftyle and boldnefs of hypothcfis were power- 
 ful to awaken and ftimulate the genius of the age " 
 
 We have been thus minute in our account of Mr 
 Gibbon's ftudies, becaufe it furnifhes perhaps the mull 
 ufefuLleflbn which can be drawn from the whole hiftory 
 of his life. His education had been rendered irregular, 
 and had been often interrupted by ill-health and a fee- 
 ble conftitution ; but as foon as he was able, and had an 
 opportunity, he applied with ardour to the cultivation 
 of letters, and his works bear witnefs that his labour 
 was crowned with fuccefs. " This part of his ftory 
 
 •J GIB 
 
 In the year 1757 Voltaire arrived at Lufaime, and 
 our young lludent's defn e to fee the man who was at ' 
 once a poet, an hiftorian, and, as he deemed himfelf, the 
 prince of philofophcrs, was ardent, and eafilv giatified. 
 He was leceived by the vain and arrogant Frenchman 
 with civility as an EnglKh youth, but could not boail 
 of any peculiar notice or dillinftion. " The higheil 
 gratification (fays he) which I received from Voltaire's 
 residence at Laufanne, was the uncommo:i circnmllance 
 of hearing a great poet declaim his own produiitions en 
 the itage. His declamation was fafliioned to the pomp 
 and cadence of the old ftage ; and he exprefted the en- 
 thufiafm of poetry rather than the feelings of Nature." 
 
 About this time Mr Gibbon became enamoured of 
 Madcmoifelle Sufan Curchod, the daughter of the nii- 
 niller of Crafle, in the mountains which feparatc the 
 Pays de Vaud from the county of Burgundy. In terms 
 of rapture he defcribes this lady as poffeffcd of every ac- 
 coniplifhment which could adorn her fex. She liflcned 
 to the voice of truth and paffion ; her parents honour- 
 ably encouraged the coiineilion ; and our author indul- 
 ged in the dream of felicity : but on bis return to Eng- 
 land, he diicovered that his father would not hear of this 
 llrange connection, and that without his confent he 
 was deftitute and helpleis. " After a painful Itrugglc 
 (fays he) I yielded to my fate. 1 fighed as a lover, I 
 obeyed as a fon, and my wound was infenfibly healed 
 by time, abfence, and tlie habits of a new life." The 
 lady confoled herfelf by giving her hand to M. Neckar, 
 then a rich banker of Paris, afterwards the minifter, 
 and at latl one of the deftroyers of the French mo- 
 narchy. 
 
 In the fpring of the year 1 758 our author was recal- 
 led to England. On his arrival in London he haftened 
 to the houfe of his aunt, Mrs Porten, who had been the 
 guardian of his tender years ; for though his father was 
 in town awaiting his arrival, he knew not how he fhonld 
 be received by a parent who had parted with him m 
 anger, and given him a ftepmother in his abfence. His 
 reception was more agreeable than he expected. His 
 father received him as a man and a friend ; and the 
 manners of Mrs Gibbon were fuch, that, after fome re- 
 ferve on his fide, (be and he eahly adopted the tender 
 names and genuine charafters of mother and fon ; and, 
 by the indulgence of thefe parents, he was left at liberty 
 to coufult his own tnfte or reafon in the choice of place, 
 of company, and of amufements. In London he had 
 few acquaintances, and hardly any friends ; and being 
 accuftomed to a very fmall focicty at Laulanne, he pre- 
 ferred the retirement of the country to the bultle of 
 that over-grown metropolis, where he found hardly any 
 entertainment but in the theatres. 
 
 Before he left Laufanne he had begim a work on the 
 fludy of ancient literature, which was fuggeiled by the 
 defire of jullifying and praifing the objetl of a favourite 
 purAiit. " In France (fays he), to which my ideas 
 were confined, the learning and language of Greece and 
 Rome were negletled by a philofophic age. The guar- 
 dian of thofe ftudies, the Academy of Infcriptions, was 
 
 therefore (to ufe the words of Johnfon) well deferves degraded to the loweft rank among the three royal fo- 
 to be remembered. It may afford ufeful admonition cieties of Paris : The new appellation oi Erudits was* 
 
 See Li 
 
 and powerful encouragement to men whofe abilities have 
 been made, for a time, ufelcfs, and who, having loft one 
 part of life in idlenefs, are tempted to throw away the 
 remaiTider in defpah-." 
 
 contemptuoufly applied to the lucceffors of Lipfius and D.feeun 
 Cafaubon ; and I was provoked to hear », that the e\- PritimiM' , 
 ercife of the memory, their I'ole merit, had been fuper-/'"' ^S ' 
 feded by the nobler faculties of the imagination and the^,g^„,/jf, 
 
 judgment ^,v.
 
 G I h 
 
 [ 705 ) 
 
 G I 15 
 
 jui!giTi<nt. I wns ambitious of proving by my own cx- 
 ' amijlc, as well as by rny precepts, that all the taculties 
 of the mind inav be exercifed and dilplaycd by the Itu- 
 dy of ancient literature." TUis laudable ambition con- 
 tinued ; and in his fatlier's houfe at Beriton in Hamp- 
 {hirc he Ijnillied his Effa'i fur I' Elude <li la Lita-jture 4 
 which, after being reviled by Mallet the poet and Dr 
 Maty of the Britilh mnl'eum, was, in 1761, publilhed 
 in a fmall i:mo volume. 
 
 The fubjefts of lade, critieifm, and phllofophy, which 
 in this work came imder our young author's confider- 
 ation, ciHild hardly promite much novelty of remark. 
 Some foimcr obfcrvations, however, he appears to have 
 placed in a new and plcafing" puint of view ; advancing, 
 moreover, fome insjenions conjectures, and dilplaying no 
 inconfiderable erudition. Yet, by hia own account, he 
 was at this time almoft a Granger to tlw writers of 
 Greece ; and when he quotes them, it is probable that 
 the quotations are given at fecond hand. To this ef- 
 fav was preiixed a dedication to his father in the Eng- 
 lifii language, which exhibits the author himfelf in a 
 very amiable light ; but if his reputation had de]>ended 
 folely upon this youthful attempt, the name of Gibbon 
 would have been loll in oblivion. Yet he feems, even 
 in his riper years, to have been delighted with it him- 
 felf, and to have confidered its merits as equal to thofe 
 of his later prodiiAions ; but Milton, it is faid, prefer- 
 red the Paradife Regained to the Paradife Loll. 
 
 Before the publication of this eflay, the author, at his 
 own delire, had been appointed a captain in the South 
 Hampfliire militia, in which he fervcd upwards of two 
 years. At firft, the company of ruftic and illiterate of- 
 ficers, and the buftle of a military life, were extremely 
 difagreeable to him, as they interrupted his lludies ; but 
 he admits, that his military ferviccs, his bloodlefs and 
 inglorious campaigns, as he calls them, were, on the 
 tvhole, beiieficial, as they brought him acquainted with 
 Engliili manners, EngKfh parties, and Englifii prin- 
 ciples, to which his f 01 eign education and referved tem- 
 per had hitherto kept him an entire Ilranger. In the 
 cainp and in quarters he had even found leifure, after 
 the iirft ieven or eight months of his fcrviee, to read a 
 great deal of Greek, and to plan difTercnt hillorical 
 works, to the compofition of which he feems to have 
 thought that he was born with an innate propenfity. 
 He always talks of himielf as a philofophcr ; but furely 
 a more unphilolophica! pcrlualion than this has feldom 
 been admitted. 
 
 At the end of the war he went again abroad, and 
 reached Paris on the 28th of January 1763, only 36 
 days after the difbanding of the militia in which he had 
 borne the commiffion of a captain. In that metropolis 
 lie llaid not long. He viliteil palaces, churches, gar- 
 dens, and theatres, and was introduced to D'Aletnbert 
 and Diderot, then confidered as at the head of French 
 fclence. From Paris he proceeded to Switzerland, and 
 once more took up his rcfidencc at his favourite Lau- 
 fanne. Voltaire's impieties had forced hiin from that 
 town to his own caitle at Feiney, where our author 
 once vilited him, without (he fays) courting his more 
 Tntimate acquaintance. 
 
 The fociety in which Mr Gibbon moft delighted du- 
 ring his fecond refidence at Laufanne was a very liiigu- 
 kir one. " It confitled of fifteen or twenty immarricd 
 •ladies of genteel families ; the eldeft perhaps about 
 
 SoppL. Vol. I. Parr-II. 
 
 twenty, all agrfcable, Jivcral handfome, »rd two or CHitor. 
 three of exquilite beatity. At each other's hoiifes — — v^ 
 they affeiiibled almoil every day, without the controul, 
 or even the prelencc of a mother or an aunt ; they were 
 trailed to their own prudence, among a crowd of young 
 men of every nation in Europe. They laughed, they 
 fung, they danced, they played at cards, they afted co- 
 medies ; but in the midll of this carelcfs gjletv, thev 
 refpedid themfelves, and were refpefted by tlie men; 
 the invifible line between liberty and licentlonlnefs was 
 never traufgrcffed by a geilure, a word, or a hxik, and 
 their virgin chaftity wus never (uliied by the breath of 
 fcandal or fufpicion." 
 
 We readily agree with onr author that this fingidar 
 inftitutioji was expreflive of the innocent bm]Jicity of 
 Sv.-Ifs mannero ; and we only reg:-et that he had not the 
 fame refpcft for the ladies of his own country as for 
 thofe frolic females of Switzerland. He would not, in 
 that cafe, have llained fome of his moll brilliant pages 
 with obfcene ribaldry. 
 
 AVe Ihall not follow hliti in his ramble through Italy, 
 or repeat his remarks on the towns which he vilited. It 
 is fufficient, in fuch a (lictch as this, to inform our rea- 
 ders, that it was at Rome on the 1 ^th of Oilober 176,), 
 as he fat mufing amidit the ruliia of the Capitol, that 
 the idea of his great work firft. ilarted into bis mind. 
 But his original plan was circumfcribed to the decay of 
 the city rather than of the empire. 
 
 From carrying even this contradled plan Into execu- 
 tion he was for fome years diverted. On the 25th of 
 June 1765 he arrived troni Italy at his father's houfe in 
 Hanipfhire, and found that he had filial duties to per- 
 form which interrupted his ftudles and dillurbed his 
 quiet. His father had Involved himielf in dihieiilties 
 from which he could be extricated only by fellinor or 
 mortgaging part of his ellate ; and to fuch fale or 
 mortgage our author cheerfully confented. He regrets 
 on this occafioii that he had not " embraced the lucra- 
 tive purfults of the law or of trade, the chances of civil 
 ofSce or India adventure, or even the fat flunib^rs if 
 the church ;" and it is to be hoped that, when he 
 thought even aijlumbning i« the church, be had flill 
 fome taith in revealed religion. He wafted fome time 
 in planning a hiltory of the revolutions of Switzerland, 
 and even wrote part of it In the French language, which, 
 by the advice of friends, he however fupprelfcd. We 
 rcxt find him engaged with a friend In a Journal en- 
 titled Memoires Litvraires de la Grande Brefagne, of 
 which two volumes for the years 1767 and 1768 were 
 piibllflied, and a third almcft completed, when his friend, 
 a native of Switzerland, was engaged, through his in- 
 tereft, as travelling governor to Sir Richard Woriley, 
 and the Journal was, of courfe, abandoned. He then 
 entered the lilts with Warburton ; whofe Interpretation 
 of the fixth book of the .(Eneld he attacked with great 
 petulance and with much iuccels. The bilhop of Glo- 
 celler was by this time in a ftate of great mental decay, 
 which was peculiarly unfortunate for our author; for 
 had his Lordftilp enjoyed his prliline vigour, he would 
 [irobably liave given Mr Gibbon fuch a chaftifement ai 
 might have made him more modefl afterwards wlirn 
 writing the liiftory of the Decline and Fall of the Ro- 
 man Empire. 
 
 To that great work he now fat down ferioully ; and 
 
 the hlftory which he gives^ of his preparatory ftudies 
 
 4 U fufficicntiy
 
 GIB r 706 ] GIB 
 
 Gibbon. fufHciently accounts for the inaccuracy of his quotations, he cannot readily find, an opportunity to infiilt tlie Gibbon. 
 ^'~'^~~' Through the darknefs of the middle ages he explored Chriflian religion. Such, inceed, is his eagerncfs in ~~"v~" 
 his way in the annals and antiquities of Italy by the the caufe, that he ftoops to the moft defpicablc pun, or 
 learned Muratori and other moderns ; and feems to ac- to the moll awkward perverfion of language, for the 
 knowledge that, from the beginninc; to the end of his pleafure of turning the fcripture into ribaldry, or call- 
 work, he frequently contented himfclf with authorities irig Jefus an impoftor. 
 
 furnilhed at fecond lumd. Yet of the Chrillian religion has Mr Gibbon liimfelf 
 At lull, in 1776. the firft volume of his hiftory was obferved, that it "contains a pure, benevolent, and uni. 
 • publiftied by Cadell the booklellcr and Strahan the verfal fyllem of ethics, adapted to every duty and every 
 printer ; and the iuccefs of It far furpafied his expefta- condition of life." Such an acknowledgment, and from 
 tion. The encomiums lavifhed on it bv Dr Robot tfon fuch a writer, too, ought to have due weight with a cer- 
 and Mr Hume in letters to the author, and the fulfome tain clafs of readers, and of authors likewife, and lead 
 compliments which thofe three eminent hiftuvlans paid them ferionfly to eonlldcr, how far it is confiftent with 
 to each other, are melancholy fpecimens of littered little- the character of good citizens, to endeavour, by fly in- 
 nefs and vanity. The fecond and third volumes appear- iinuations, oblique hint£, indecent fneer, and profane ri- 
 ed in 1781 ; the fourth, fifth, and fixth in 1787 ; and dicule, to weaken the influence of in pure and hne-vo/ent 
 Mr Gibbon's fame was eftablilhed as a hiftorian. The a fyftem as that of Chrillianity, acknowledgd to bead- 
 work was admired both by natives and by foreigners, mirably calculated for promoting the happinefs of indi- 
 and tranilated into feveral of the languages of Europe, viduals, and the weltare of focitty. 
 
 Dr Zimmerman reprefents the author as excelling per- Mr Hayley, in his poetical Effay on Hiftory, after 
 
 haps Hume and Robertfon, who were hiilorians of the a fplendid panegyric on the arduous labours of his 
 
 firil rank. All the dignity (he adds), all the charms friend, laments the irreligious fpiric by which he was. 
 
 of hiftoric ilyle, are united in Gibbon : his periods are aftuated. 
 
 melody ititlf, and all his thoughts have nerve and vi- _, . , r 1,1 • ji 
 
 ,i rr,, . •.- u ji ^ i 1-1 Thmk not my verle means bundlv to engage 
 
 gour. 1 his praile, however, muit not be admitted ■, „ ■, r r ■, c , °° 
 
 *>..,. ^f -r, -. ■ J 1 rr n- J In ralh defence of thy protaner page ! 
 
 without exception, tew writers, indeed, were poilelled ™, , , , - • ■ l .1^ r 1 
 
 cr i 1.1. L-;i • Ti r Though keen her Ipcrit, her attachment tond, 
 
 or uich popular talents as our hiltonan. Iheacutenels t, r P ■ r • • 1 -c- • j.-l- . l j 
 
 c I,- ^ ,- J .1. r .-r. c-L- ■ 1 Baf^ fervice cannot iuit with tnendihips bond ; 
 
 or his penetration, and the tertility 01 his genius, have „rr T-.irj.i,» 
 , r >j 11 J jr 1 r/rjTj Too firm from Duty s lacred path to turn, 
 
 been ieldom equalled, and icarcely ever lurpaiied. He r,, , , ,_ n. •- 1. r j 
 
 r ■ • u r 1 r r •. 'ii .i. a ■ a- one breathes an honeit ugh or deep concern, 
 
 leizes, with lingular lelicity, on all the molt intereltmg « , • • ,^ • i_ l- -u 
 
 tr a. jr. .■ J /i. r u u irn, -.u .u And pities Genius, v/hen his wild career 
 
 tacts and lituations; and thele he embellilhes with the _. f^— . , , ^ 
 
 n 1 • rr j 1 r ,i 1 tt- Gives I'aith a wound, or Innocence a tear, 
 
 utmoli luxuriance ot tancy and elegance 01 ityle. His tt ■■,■ 1 r ir j- • 1 -ij 
 ., r„ ju- Li •! Humility herielt divinely mild, 
 
 periods are tull and harmonious; his language is al- „,,.■',.., ,' , , „ ,.,, 
 
 '^ 11 1 r 1 • r 1 j-ii- -,1. J ,_ Sublime religion s meek and raodelt child, 
 
 ways well cholen, and is rrequently diitinguilhed by a t -i 1 , 1 r c r> r ■ u n •>- 
 
 -^ , V 1 1 J • TT- • 1 Like the dumb Ion or Crcelus, m the (true, 
 
 new and peculiarly happy adaptation. His epithets, ,tti c /r -dj i.- r .u > r 1 rr 
 
 ■^ i , '^'^^r , , , . . 1 • Where lorce affad'd his father's facred life, 
 
 too, are in general beatiiiiu! ano happy ; but he is ra- t> 1 ,-, j • u cr 1 j . 
 
 ^, ' r *j r .1 rpi -r ,1 1- r n- Breaks iilencc, and With filial duty warm, 
 
 ther too tond ot them. J. he ufiiionn Itatelinels 01 his t>-., i_ -Li/jr />■ 
 
 j.r.- r ^- ■ ^ I.- J c BiQS thee revere her parent s hallowed torm (b) ! 
 
 diction lometimes imparts to his narrative a degree of ^ ^ ' 
 
 obfcurlty, unlefs he defcends to the miferable expedient The part of the hiftory which gave fuch offence to 
 
 of a note, to explain the minuter circumftances. His his own friend, as well as to the friends of the Chriftian 
 
 ftyle, on the whole, is much too artificial ; and this gives religion in general, was the account which our hiftoriaa 
 
 a degree of monotony to bis periods, which extends, we has given of the progreis and eftablifhment of Chriftia- 
 
 bad almoft laid, to the turn of his thoughts. nity in the two laft chapters of his firft volume ; in whicli 
 
 A more ferious objeftion is his attack upon Chrifti- he endeavours to prove, that the wonderful triumph of 
 
 anity ; the Icofe and difrefpeftful manner in which he that religion over all the ellablillied religions of the 
 
 mentions many points of morality regarded as important earth, was not owing to any miraculous atteftations to 
 
 on the principles of natural relig(m ; and the indecent its truth, but to five fecondary caufes which he enume- 
 
 allufions and exprcflioiis which too often occur in the rates; and that Chiiftianity, of courfe, could not be of 
 
 work. . divine origin. Several anfwers appeared on this occa- 
 
 An attack upon Chriftianity is not cenfurable merely fion, written, as we may naturally fuppofe, with diffe- 
 
 as fuch ; it may proceed from the purett and moft vir- rent degrees of temper and ability (c). 
 tuous motives : but, in that cafe, the attack will never One of them only, Mr Davis, who had undertaken 
 
 be carried on in an infidious manner, and with improper to point out- various inikances of miireprefentation, in- 
 
 weapons, and Chriftianity itfclf, fo far from dreading, accuracy, and even plagiarifm in his account, did our 
 
 will invite every mode of fair and candid difcuftion. hiftorian condelcend particularly to anfwer, and that in 
 
 Our hiftorian, it muft be cunfcficd, often makes, wheu a tone of proud contempt and confident fuperiority. To 
 
 this 
 
 (b) Herodotus relates, that a Perfian foldier, at the ftorming of Sardis, was preparing to kill Croefus, whofe 
 perlon he did not know, and who, giving up all as loft, neglefted to defend his own life. A fon of the unforlu. 
 Date monarch, who had been dumb from his infancv, and who never fpoke afterward, found utterance in that 
 trying moment, and preferved his father by exclaiming, ' O kill not Crosfus 1' 
 
 (c) Dr Chelfum, Dr Randolph, Dr Watfou (bilTiop of LlandafT), Lord Hailes, Dr White, Mr Apthorpe, 
 Mr Davis, and Mr Taylor,, the author of ' The Letters of Ben Mordecai.'
 
 GIB [ 707 ] . . GIB 
 
 this Mr Davij replied ; and it is but jufticc to obferve, deared Swifs friend. I^aufannc had now loft much of OibboD, 
 that liis reply bears evident marks of learning, judgment, its attradlion ; the French revolution had crowded it ' '^ "'^'. 
 and critical acumen, and that he has convicted our ;ui- with unfortunate emigrants, who could not be cheerful 
 thor of fonietimes quoting inaccurately to ferve a pur- themfelves or excite the cheerfulnefs of others ; and tlie 
 j)ofe. At his other anfwerers Mr Gibbon merely glati- demons of democracy had begun to jioifon the minds 
 ced, treating Dr Watfon, however, with particular re- of the fober citizens with princfijles which Mr Gibbon 
 fpeft ; but his pofthunious memoirs fhew how much he had always held in abhorrence. Speaking of thefe j^rin- 
 felt tt\e attacks made on him by Lord Hailes, Dr ciplcs and their efFcfts in Switzerland, he adds, " 1 beg 
 
 White of Oxford, and Mr Taylor. To Dr Prieftley , ' " '^ - - ^ . . 
 
 who, in his Hjlory of ihe Curruj>tinns of Chriflinnily, 
 threw down his gauiit,lets at once to Bidiop tlurd and 
 the hillorian of the Roman empire, and who prefeiiud 
 the latter with a copy of liis book, declaring at the 
 fame time, that he lent It not as a gift but as a chal- 
 Uiige ; he wrote in fuch terms as produced a corre- 
 fpondence, which certainly added not to the honour of 
 the diffenting divine. 
 
 At the bet;innin;j of the memorable conteft between 
 Great Britain and America, our author was returned, 
 by the interelt of Mr Eliot ('now Lord Eliot), for the 
 
 leave to fubl'cribe my affent to Mr Burke's creed on 
 the revolution of France. I admire his eloquence, I 
 approve his politics, I adore his chivalry, and I can al- 
 moft excufe his reverence for church cftablidiments. 
 While the ariftocracy of Berne protefts the hiipjunefs, 
 it is fuperfluous to inquire whether it be founiled in the 
 rights of men : the economy of the (late is liberallv fup- 
 plied without the aid of taxes ; and the magiftrates iniifl 
 reiiiii with prudence and equity, fince they are unarmed 
 in the midll of an armed nation." 
 
 It was againft the benehcent and mild government 
 of Berne that the emiflaries of France contrived to ex- 
 borough of Liilveavd, and fupported, with many a (in- cite the difcontents of the people, by inllilling into 
 cere and fdent vote, the rights, though not, perhaps, their limple and untutored minds their own wild no- 
 thc intereft, of the mother country. " After a fleet- tions of liberty and equality. From the eReds of this 
 ing illulivt hope, prudence cundemned me (fays he) lo Gallic frenzy, which began to be very vilible fo early 
 acquicfce in the humble (lation of a mute. I was not as the beginning of the year 1792, Mr Gibbon refol- 
 armed by Nature and education with the intrepid ener- ved to take flulter in England, and to abandon, for 
 gy of mind and voice. fome time at lead, what he called his paradiie at Lau- 
 
 ,-. „ . , ,. fanne. Dilficulties intervened, and forced him to po(l- 
 
 y incmtem jlrcbitus, et natiim rebus ajicmUs. u-. r„ 1. 1 jr .u 
 
 J r 1 A pone his journey trom week to week, and trom month 
 
 Timidity was fortified by pride ; and even the fuccefs to month ; but on receiving the accounts of Lady Shet- 
 
 of my pen dikouraged the trial of my voice." (ield's death, he hallened to adminiller confolation to 
 
 That pen, however, was nfcful to the miniftry whom his friend, and arrived fafe in London in the beginning 
 
 lie could not fupport by his eloquence in the houfe. of June 1793. 
 
 At the requeft of the Lord Chancellor and Vifcount He continued in good health and fpirits through the 
 
 Weymouth, then fecretary of ilate, he vindicated, in a whole of the fummer ; but his condilution had fullered 
 
 very able manner, againft the French manifcllo, the much from repeated attacks of the gout, and from an 
 
 juftice of the Britifli arms ; and his Memoire jfu/lifcat'f incipient dropiy in his ancles. The fwehing of his 
 
 was delivered as a ftate paper to the courts of Europe, ancles, however, fubiided ; but it was only in confe- 
 
 He was rewarded for this fervice with the place of one quence of the water flowing to another place: and be- 
 
 of the lords commlflTioners of trade and plantations; and ing repeatedly tapped for a hydrocele, he at laft funk un- 
 
 kept it, till the board was aboliflied by Mr Burke's re- der it, and died at his lodgings in St James's ftreet,' 
 
 form JjiU. For accepting this place he was fevercly, London, on the 1 6th of January 1794. 
 
 but moft unjuftly, blamed by fome of the leaders of the To draw a character at once general and juft of this 
 
 oppofition, as if he had defcrted a party in which he 
 bad never enlifted, and to the principles of which he was 
 rendered inimical both by family pi-epofrefTion and by 
 his own judgment. 
 
 On the dow nfal of Lord North's adminiftration, Mr 
 Gibbon was of courfe in the oppofition deprived of an 
 
 extraordinary man, would be dJlhcult perhaps to one 
 who had enjoyed the pleaiure of his acquaintiince, and 
 miifl be im.poliilile to thofe to whom his perfon was a 
 ftranger. Of the extent of his erudition there can be 
 but one opinion ; but various opinions may be held re- 
 fpefling the accuracy of his knowledge. Lord Shefiield, 
 
 office, without the falary of which he could not conve- who knew him well, and lovid him much, alfures us, 
 
 niently fupport the expence of living in London. The that his converfation was ftiU more captivating than his 
 
 coalition was indeed foon formed, and his friends were writings : but this could not rcfult from the brilliancy 
 
 again in power ; but having nothing to give him imme- of his W"it ; for of wit he declares himfelf that he had 
 
 diately, they could not detain hiin in parliament or even none. His memory was capacious and retentive, his 
 
 in England. He was -tired of the buftle of the metro- penetration uncommon, and his colloquial eloquence 
 
 polls, and fighed once more for the retirement of Laii- ready and elegant i fo that he could illuftrate almott 
 
 ianne, at which he arrived before the overthrow of the any topic of converfation from the copious (lores of his 
 
 coalition miniftry, and where he lived happily till the own mind. From his piivate corrclpondence, and a 
 
 laft years of his life. It was in this retreat that he journal not written for the public eye, lie appi is to 
 
 wrote the fourth, fitth, and fixth volumes of his hiftory ; 
 and he left it only for a year to fupcrintend the publi- 
 cation of thefe volumes in London. This great work 
 being concluded, he returned to the banks of the Leman 
 lake, but found his enjoyments damped by the diftrefs. 
 
 have been a dutiful fon, a loyal fubjeft, and an alFec- 
 tionate and (leady friend ; but it is difficult to reconcile 
 with fo much moral and political worth his unfaii and 
 unmanly fnters at the religion of his country. 
 
 GIBRALTAR is a fortrefs of immenfe ftrength, 
 
 and foon afterwards by the death, of his oldeft and of which a very full account has been given in the En- 
 
 4 U 2 cycluptedia.
 
 GIB [70 
 
 Gitraltar. cydopitdia. Nothing, howevti, is in that article faid of 
 • the natural hiltory ot tlie mountain on ul.ich the for- 
 
 trefs is built, tliough, lo men of fcience, that fubjcci 
 mud be as interefting as a detail of fiegef. This clefe6t 
 we are enabled to iupply by means of Miijor Imrie's 
 mineralogical dcfcription of Gibraltar, whicli is pubhili- 
 ed in the f.inrtli volume of thcTranfactions of the Royal 
 Society of Edinburgh ; and, we are perfuuded, the fol- 
 lowing abftraft of that elegant memoir will afford ra- 
 tional entertainment to many of our readers. 
 
 " The form of this mountain is oblong ; its fummit a 
 {harp craggy ridge ; its direction is nearly from north 
 ^o fouth ; and its greatefl length, in that direiSiion, falls 
 ■»ery little fliort of three iniks. Its breadth varies with 
 the indentations of the fliore, but it nowhere exceeds 
 three quarters of a mile. The lire of it': ridge is undu- 
 lated, and the two extremes are fomewhat higher than 
 its centre. 
 
 " Tlit fonimit of the Sugar Loaf, which is the point 
 of its greateft ckvotion towards the foutli, is 14^9 feet; 
 the Reck. Mort;ir, which is the iiightd point to the 
 noith, is '■J5C'; and the Signal Honfe, which is nearly 
 the central point between thefe two, is 1276 feet above 
 the level of the fen. The wefitrn fide of the mountain 
 is a feries of rugge<l dopes, i;ittfrfpe> fed with abrupt pre- 
 cipices. Its northern extrerriiy is perfeftly perpcndi. 
 cular, except towards the north-weft, where what are 
 called the Lines intervert. and a narrow pafiage of flat 
 grourd that leads to the illhmus, and is entirely cover- 
 cd with fortification. The eaftern ilde of the moun- 
 tain moftly conhlls of a range of precipices; but a bank 
 of fand, rifmg from the Mediterranean in a rapid accli- 
 vity, covers a third of its perpendicular height. Its 
 fouthern extremity fall?, in a rapid flope from the fum- 
 mit of the Sugar Loaf, into a rocky fiat of confiderable 
 extent, called Windmill Hill. 
 
 " The principal mafs of the mountain rock confifts 
 of a grey, denfe (what is generally called primary) mar- 
 ble ; the different beds of which are to be examined in 
 a face of 1350 feet of perpendicular height, which it 
 yrefents to Spain in a conical form. Thefe beds, or 
 firata, are of various thickncfs, from 20 to upwards of 
 40 feet, dipping in a direftion from eaft to weft, nearly 
 at an angle of 35 degrees. In fome parts of the foFid 
 Hiafs of this rock are found teftaceous bodies entirely 
 iranfrauted into the confUtuent matter of the rock, and 
 their interior hollows filled up with calcareous fpar ; but 
 thefe do not occur often in its conipofition, and its beds 
 4re not feparated by any intermediate ftrata. 
 
 " The cave? of Gibraltar are many, and fome of them 
 of great extent. That which mod defervcs attention 
 and examination is called St Michael's Cave, which is 
 fituated upon the fouthern part of the mountain, almoft 
 equaHy diflant from the Signal Towtr and the Sugar 
 Loaf. Its entrance is icoo feet above the level of the 
 fta : This entrance is formed by a rapid flope of earth, 
 which has fallen into it at various periods, and which 
 leads to a fpacious hall, incruftcd with fpar, and appa- 
 rently fupported in the centre by a large maffy flalaili- 
 tical pillar. To thi« fiicceeds a long feries of caves of 
 difficult accefs. In thefe cavernous recefies, the forma- 
 tion and procefs of ftalaflites is to be traced, from the 
 flimfy quilt-like cone, fufpended from the roof, to the 
 vobufl. trunk of a pillar, three feet in dimeter, which 
 
 8 ] GIB 
 
 rifcs from the floor, and fecins intended by Nature to Gibraltar. 
 fujjport the roof from which it oiiginated. >— — v— ^ 
 
 " The only inhabitants of thele caves are bats, fome 
 of which are of a large fize. The foil, in general, upon 
 the mountain of Gibraltar is But thinly fown ; and in 
 many parts that tliin covering has been waHied off by 
 the heavy autumnal rains, which have left tlie fuperfi- 
 cies of the rock, for a confiderable extent, bare and 
 open to iiifpeftion. In thofe fituations, an obferving 
 eye may trace ihe effeiSs of the flow, but ccniRant, de- 
 compofition of the rock, caufed by its expofure to the 
 air, and the corrofion of fea-falts, which, in the heavy 
 gales of eafterly winds, are depofited with the fpray on 
 every part of the mountain. Thofe uncovered parts of 
 the mountain rock alfo expofe to the eye a phenomenon 
 worthy of fome attention, as it tends clearly to demon- 
 ftrate, that, however high the furface of this rock may 
 now be elevated above the level of the fea, it has once 
 been the bed of agitated waters. This phenomenon is 
 to be obferved in many parts of the rock, and is con- 
 ftantly found in the beds of torrents. It confilfs of pot- 
 like holes, of various lizes, hollowed out of the folid 
 rock, and formed apparently by the attrition of gravel 
 or pebbles, fet in motion by the rajiidity of rivers or 
 currents in the fea. 
 
 " L'pon the weft fide of the mountain, towards its 
 bafe, fome ftrata occur, which are heterogenial to the 
 mountain rock ; the firll, or higheil, forms the fegment 
 of a circle ; its convex fide is towards the mountain, 
 and it Hopes alfo in that dircdlion. This ftratum con- 
 fifts of a number of thin beds ; the outward one, being 
 the thinneft, is in a ilate of decompofition, and is moul- 
 dering down into a blackifh brown or ferruginous co- 
 loured earth. The beds, inferior to this, progrefTively 
 increafe in breadth to i 7 inches, where the flratification 
 refls upon a rock of an argillaceous nature. 
 
 " This laft bed, which is 17 inches thick, confifts of 
 quartz of a blackifh blue colour, in the fepta or cracks 
 of which are found fine quartz cryftals, colourlels, and 
 perfciftly tranfparent. Thcie cryftals are compofed of 
 18 planes, difpofed in hexangular columns, terminated 
 at both extremities by hexangular pyramids. The lar- 
 geil of thofe that Major Imrie faw did not exceed one- 
 fourth of an inch in length : They, in general, adhere 
 to the rock by the fides of the column, but are detach- 
 ed without difficulty. Their great degree of tranfparen- 
 cy has obtained them the name of Gibraltar diamotids" 
 
 Much has been faid of the foffd bones found in the 
 rock of Gibraltar ; and the general idea which exifts 
 concerning them is, that they are found in a petrified 
 ftate, and enclofed in the folid calcareous rock ; but 
 this, fays Major Imrie, is a miftake, which could arife 
 only from inaccurate obfervation and falfe defcription. 
 
 " In the perpendicular fitTures of the rock, and in 
 fome f/f the caverns of the mountain (all of which afford, 
 evident proofs of their former communication with the 
 furface), a calcareous concretion is found, of a reddifh 
 brown ferruginous colour, with an earthy frafture, and 
 confiderable induration, cnclofing the bones of various- 
 animals, fome of which have the appearance of being 
 human. Thefe bones are of various fizes, and lie in all 
 direA ions, intermixed with fhells of fnails, fragments of 
 the calcareous rock, and particles of fpar ; all of which 
 materials are ftill to be feen in their natural uncombined 
 
 flates,
 
 G I B 
 
 [ 709 ] 
 
 G 1 B 
 
 litiral'ar. ftates, partially fcattered over tlie furface of the moun- 
 """< ' tcin. Thefe having been fwept, by heavy rains at dif- 
 ferent periods, from the furf;ice into the fituauons above 
 defcribed, and having remained for a long feries of years 
 in thijfe places oF reft, expofcd to the permeating aAion 
 of water, liave become invcloped in, and cemented by, 
 the calcareous matter which It depofits. 
 
 " The bones. In this conipofition, have not the fmalleft 
 appearance of being petiifitd ; and if they have under- 
 gone any change, it is more like tliat of calcination than 
 that of petrlfaclicn, as the mod folid parts of them ge- 
 nerally admit of being cut and fcraped down with the 
 fame eafe as chalk, 
 
 " Bones combined in fnch concretions are not peculiar 
 to Gibraltar : they arc found in fuch large quanthies 
 in the country of Dalmatia, and upon its coafts in the 
 iflands of Cherfo and Ofcro, that fonie naturalifts have 
 been induced to go fo far as to atlerl, that there has 
 been a regular ftratum of fuch matter in that country, 
 and that its prefent broken and interrupted appearance 
 has been caufed by earthquakes, or other convullions, 
 experienced in that part of the globe. But, of late 
 years, a traveller (Abbe Alberto Fortis) has given a 
 nu'nute defcription of the concretion in which the bones 
 are found in that country : And by his account it ap- 
 pears, that with regard to fituation, compofition, and 
 colour, it is pcrfeftly fimilar to that fourd at Gibraltar. 
 By his defcription, it alfo appears that the two moun- 
 tain rucks of Gibraltar and Dalmatia conlill of the fame 
 fpecies of calcareous ftone ; from which it is to be pre- 
 fumed, that the concretions in both have been formed 
 in the fame manner and about the fame periods. 
 
 " Perhaps if the fiffures and caves of the rock of Dal- 
 matia were flill more minutely examined, their former 
 eommunicatlons with the furface might yet be traced, 
 as in thofe defcribed above ; and, in that cafe, there 
 would be at Icaft a ftrong probability, that the materials 
 of the concretions of that country have been brought 
 together by the fame accidental caufc which has pro- 
 bably collttted thofe found in the caverns of Gibraltar. 
 Major Imrie traced, in Gibraltar, this concretion, from 
 the lowed part of a deep perpendicular fiffure, up to 
 the furface of the mountain. As it approached to the 
 furface, the concretion became lefs (irmly combined, 
 and, when it had no covering of the calcareous rock, a 
 fmall degree of adheilon only remained, which was evi- 
 dently produced by the argillaceous earth, in its com- 
 pofition, having been moifteued by rain and baked by 
 the fun. 
 
 " The depth at which thefe materials had been pene- 
 trated by that proportion of ftalaiSitical matter, capable 
 of giving to the concretion its greateft adhcfion and fo- 
 lidity, he found to vary according to its fituation, and 
 to the quantity of matter to be combined. In fiffures, 
 narrow and contracted, he found the concretion pofief- 
 flng a great degree of hardnefs at fix feet from the fur- 
 face ; but in other fituations more extended :-and where 
 a larger quantity of the materials' had been accumula- 
 ted, he found it had not gained its greateil degree of 
 adhefion at double that depth. In one of the caves, 
 •where the rnafs of concretion is of confulersible fiae, he 
 perceived it to be divided into different beds, each bed 
 being covered with a cruil of the ftalnditical fpar, from 
 nne inch to an inch and a half in thickncfs ; which feems 
 to indicate, that the materials have been carried ia at 
 
 various periods, and that thcfe periods have been very Gibraltsi. 
 remote from each other. '■■ 'v ■■' 
 
 " At Rofia Bay, upon the well fide of Gibraltar, this 
 concretion is found in what has evidently been a cavern, 
 originally formed by huge unfhapcly malles of the rock, 
 which have tumbled in together. The fifl'urc, or ca- 
 vern formed by the difruption and fubfidencc of thofe 
 maffes, has been entirely filled up v.ith the concretion, 
 and is now expofcd to full view by the oittward mafs 
 having dropped down in confequcnce of the encroach- 
 ments of the fea. It is to this fpot that ftrangcrs are 
 generally led to examine the phenomenon ; and the 
 compofition, having here attained to its greatell degree , 
 
 of hardnefs and folidity, the hafty obferver, fcein-r the 
 bones inclofed in what has fo little the appearance of 
 having been a vacuity, examines no further, but imme- 
 diately adojjts the idea of their being incafed in the fo- 
 lid rock. The communication from this former chafm 
 to the furface from which it has received the materials 
 of the concretion, is flill to be traced in the face of the 
 rock, but its opening is at prefent covered by the bafe 
 of the line wall of the garrifon. Here bones arc found 
 that are apparently human ; and thofe of them that ap- 
 pear to be of the legs, arms, and vertebrx of the back, 
 are fcattered antong others of various kinds and iizes, 
 even down to the fmalleft bones of fmall birds. Major 
 Imrie found here the complete jaw-bone of a (hecp ; it 
 contained its full complem.ent of teeth, the enamel of 
 which was perfeft, and its whitenefs and luilre in no 
 degree impaired. In the hollow parts of fome of the 
 large bones was contained a luinute cryftallization of 
 pure and colourlefs calcareous fpar ; but, in mofl, the 
 interior part confillcd of a iparry crnfl of a rtddifh co- 
 lour, fcarcely in any degree tranfparent. 
 
 "At the northern extremity of the mountain, the con- 
 cretion is generally found in perpendicular fiffures. The 
 miners there, employed upon the fortilications in exca- 
 vating one of thofe fiffures, found, at a great depth from. 
 the furface, two fl<ulls, which v/ere fuppolVd to be hi;- 
 man ; but, to the Major, one of them, if not both, ap- 
 peared to be too fmall for the liuman fpecies. The bone 
 of each was perfcdly firm and fohd ; from which it is 
 to be preiunied, that they were iu a Hate of maturity 
 before they were inclofed in the concretion,. Had they 
 appertained to '/cry young children, . perhaps the bone 
 would have been more porous, and of a lefs firm tex- 
 ture. The prob.ibility is, that they belonged to a fpe- 
 cies of monkey, which flill continues to inhabit, in con- 
 fiderable numbers, thofe parts of the rock which are to • 
 us inaccelTible. 
 
 "Tliis concretion varies, in its compofition, according 
 to the fituation in which it is found. At the extremity 
 of Princes Lines, high iu the rock which looks towards 
 Sp.iin, it is found to confill only of a reddlfh calcareous . 
 earth, and the bones of fmall bitds cemented thereby. 
 The rock around this fpot i.'i inhabited by a number of 
 hawks, that, in the breeding feafon, nellle here and rear 
 their young; the bones in this concretion are probably 
 the remains of the food of thofe birds. At the bafe of 
 the rock, below King's Lines, the conci'etion confifts of 
 pebbles of the prevailing calcareous rock. In this con- 
 cretion, at a very confidcrable depth under the furface, 
 was found the under parts of a glafs bottle, uncom- 
 monly fhaped, and of great thicknefs j the colour of the 
 glafs was of a dark green." 
 
 Majpri-
 
 G I R [71 
 
 Gibraltar. Major Imrle makes an apology for giving fo minute 
 « a defcriplion of tliefc fi.fril boiiLS ; but, in our opinion, 
 the public is indebted to him for bellowing fo much at- 
 tention oil a fubjeft which ;ill miifl; admit to be curious, 
 and which, from the ftrange intcrences drawn from fimi- 
 lar phenomena by modern philofophers, has become im- 
 portant as well as curious. 
 
 We cannot difmifs this article without noticing the 
 fubterraneous galleries conftrufted in the rock not only 
 for the protedlion of the men during a fiege, but alfo 
 for placing cannon, to annoy the enemy, in fituations 
 inaccclfible but by fuch means. The idea of forming 
 ' thefe galleries was conceived by the late Lord Heath- 
 field when governor, and by him, in fome meafure, car- 
 ried into execution ; though the plan was not com- 
 pleted till lately by General O'Hara. Of thefe gal- 
 leries we have in the Monthly Mngazine for April 1 798 
 an animated account, which we fliall infert in the wri- 
 ter's own words. 
 
 " The fubterraneous galleries are very extenfive, 
 pierce the rock in feveral places and in various direc- 
 tions, and at various degrees of elevation ; all of them 
 have a communication with each other, cither by flights 
 of fteps cut in the rock, or by wooden (lairs where the 
 palTages are required to be very perpendicular. 
 
 " The centinelsmay now be relieved during a fiege 
 from one poft to another in pcrfecl fafety ; whereas, pre- 
 vioudy to the conllrutling of thefe galleries, a vail num- 
 ber of men were killed by the Spaniards while march- 
 ing to their feveral llatio.is. The width of thelc gal- 
 leries is about twelve feet, their height about fourteen. 
 The rock is broken through in various places, both for 
 the purppfe of giving light and for placing the guns to' 
 bear on the enemy. In different parts there are fpaci- 
 ous recefTes, capable of accommodating a confiderable 
 number of men. To thefe recefles they give names, 
 fuch as St Patrick's Chamber, St George's Hall, &c. 
 The whole of thefe fingular (Iruclures have been form- 
 ed out of the folid rock by blalling with gunpowder. 
 Through the pohtenefs of an officer on duty, a place 
 called Smart's Refervoir was opened for our infpeftion, 
 ■which is a great curiofity, and not generally permitted 
 to be (liewn. It is a fpriiig at a confiderable depth in 
 the body of the rock, and is above 700 ieet above the 
 level of the fea ; we defcended into the cavern that con- 
 tains it by a rope ladder, and with the aid of lighted 
 candles proceeded through a narrow paTage over cryllal- 
 lized protuberances of the rock till we came to a hollow, 
 which appears to have been opened by fome convulfion 
 of Nature. Hert, from a bed of gems, arifes the filu- 
 tary fount, clear as the brilliant of the eaft, and cold as 
 the icicle. We hailed the nymph of the grot, and, pro- 
 ftrating ourfelves, quaffed h\ gcan neclar trom her fparry 
 urn. When reftored to the light of day, we obtained, 
 through the medium of the fame gentleman, the key of 
 St George's Hall, at which we arrived by a very intri- 
 cate and gloomy path to the fpacious excavation, which 
 is upwards of an hundred feet in length, its height near- 
 ly the fame. It is formed in a femicircular part of 
 the rock ; fpacious apertures arc broken through, where 
 cannons of a very large calibre command the iilhir.us, 
 the Spanilh lines, and a great part of the bay. The 
 top of the rock is pierced through, fo as to introduce 
 fufficient light to enable you to view every part of it. 
 It appears almoft incredible that fo large an excavation 
 could be formed by gunpowder, without blowing up 
 
 o ] G L A 
 
 the whole of that part of the rock, and ftill more fo, 
 that they fliould be able to dircft the operations of fuch 
 an Inftruiiient, fo as to render it fubfervient to the pur- 
 pofe of elegance. We found in the hall a table, pla- 
 ced, I fuppofe, for the conveniency of thofe who are 
 traverfing the rock. The cloth was fpread, the wine 
 went round, and we made the vaulted roof refound with 
 the accents of mirth and the fongs of conviviality." 
 
 Thefe excavations are indeed very extraordinary 
 works ; but as the whole rock abounds with caverns, 
 we wilh that our author had inquired more particularly 
 than he fcems to have done, whether St Georo-e's Hall 
 be wholly the work of art. From one of the pafTages 
 which we have ext rafted from Major Imrie's memoir, 
 we are led to think that it is not, or at leall, that the 
 concretion removed had not acquired the confillence of 
 the more folid parts of the rock. If this was the cafe, 
 much of the wonder will vanish, fuice the pick-axe and 
 chifel were probably employed to give elegance to the 
 vault, and even, in fome degree, to direft the operation 
 of the gunpowder. 
 
 GIMBOLS, are the brafs rings by which a fea- 
 compafs is lufpendcd in its box that ufually ftands in 
 the binacle. 
 
 GIRT, in timber-meafuring, is the circumference of 
 a tree, though fome ufe this word for the quarter or 
 4th part of the circumference only, on account of the 
 great ufe that is made of it ; for the fquare of this 4th 
 part is efteemed and ufed as equal to the area of the 
 fedlion of the tree ; which fquare therefore multiplied 
 by the length of the tree, i.i accounted the folid con- 
 tent. This content, however, is always about one- 
 fourth part lefs than the true quantity ; being nearly 
 ecjual to what this will be after tlie tree is hewed 
 fquare in the ufual way : fo that it feems intended to 
 make an allowance for the fquaring of the tree. 
 
 Girt Line, Is a line on the common or carpenter's 
 Aiding rule, employed in calling up the contents of 
 trees by means of their girt. 
 
 GLASS Etching, or Engraving upon, is in the ar- 
 ticle Chfmistry {Encycl.) fald to be a new art ; and 
 as that acid which diffolves fillceous earth, and alfo 
 glafs, was firlt difcovered in the year 1771 by Scheele, 
 one mi^ht naturally Imagine that the art of etching 
 with it upon glais could not be older. By many o- 
 thers, as well as by us. It has indeed been noticed as a 
 new invention -, yet ProfelTor Beckmann, whofe labo- 
 rious refearches have brought m.any things to light, 
 has proved, that fo early as the year 1670 the art of 
 etching upon glafs was difcovered by Henry Schwan- 
 hard, fon of George Schwanhard,- who was a cele- 
 brated glafs cutter, patronized by the Emperor Ferdi- 
 nand in. about the middle of the lail century. At 
 the time of his death, 1667, the father pracllfed his art 
 at Prague and Ratifbon. Whether the fon followed 
 the fame bufinefs at the fame towns, or removed to 
 Nuremberg, is not very evident from the profefTor's 
 hlflory ; but in the year above-mentioned, lome aqua 
 regia (nilio muriatic acid) having accidentally fallen 
 on his fpeftacles, he was furprifed to find the glals 
 corroded by it, and become quite foft. He thus found 
 hImfcK In poffeffion of a liquid by which he could etch 
 writing and figures upon plates of glafs. 
 
 Such Is our information ; but if It be admitted (afld 
 It would difplay unreafonable fceptlcifm to queillon it), 
 Schwanhard muft either have improved the nitro-muriatic 
 
 acid
 
 G L O [7 
 
 OhO, acid by fome means or otiier unknown to us, or have 
 , fi.aonv (.,,„(^,n.(l hJs etchings to fon^e particular kinds of glafs ; 
 "' °"' , fur ihe Jfiioric is tlie only acid, with which wc are ac- 
 "^ ^([uainted, that corrodes all glafs. (See Chemistry- 
 Jihicx in this Supplemeiit). M. Beckmann indeed Teems 
 to think that he had difcovercd the fluoric acid ilfelf ; 
 for in the year 1725 there appeared in a periodical 
 work the following receipt for making a powerful acid, 
 by which figures of every kind tan be etched upon glale. 
 " When the fpirltus nilri per dijlilhilionem has pal- 
 fed into the recljjientj.ply it with a (Iroiig lire, and 
 when well dephlegmated, pour it, as it corrodes ordi- 
 nary glafs, into a Wcldenburg flalk. Then throw in- 
 to it a pulverifed green BoheniiHu ennerald, othcrwife 
 called hffphorus (which, when reduced to powder, and 
 heated, emits in the dark a green light), and place it in 
 warm land for 24 hours. Take a piece ot glafs well 
 cleaned, and freed from all greafe by means of a ley ; 
 put a border of wax round it, about an inch in height, 
 and cover it all over with the above acid. The longer 
 you let it Hand fo much the better ; and at the end of 
 fome time the glafs will be corroded, and the figures 
 which have been traced out with fulphur and vaniilh 
 will appear as if raifed above the pane of glals." 
 
 That the Bohemian emerald or btfphorus mention- 
 ed in this receipt is green fparry fluor, cannot, fays the 
 profelfor, be doubted ; and he fecms to have as little 
 doubt of the receipt itfelf having pafled from Schwan- 
 hard and his fcholars to the periodical work of 1725, 
 from which it has been lately inferted in the Qikono- 
 mifche Encyclopedie of Krunitz. This fuppoiition 
 certainly acquires a confiderable degree of probability 
 from the fimilavity of Schwanhard's method of etching 
 to that which is here recommended, and which is ' io 
 different from what is now followed. At prefent, the 
 glafs is covered with a varnifli either of ilinglafs dit- 
 folved in water, or of turpentine oil mixed with a little 
 white lead, through which the figures to be etched are 
 traced as on copper ; but Schwanhard, when he had 
 drawn his figures, covered them with varnilh, and then 
 by his liquid corroded the glafs around them. His fi- 
 gures, therefore, when the varnilh was removed, re- 
 mained fmooth and clear, appearing vailed from a dim or 
 dark ground ; and M. Beckmann, who perfuaded (onic 
 ingenious artills to make trial of this antient method 
 of etching, declares, that fuch figures have a much bet- 
 tcr effeft than thofe which are cut into the glafs. 
 
 Before concluding this article, it may be worth while 
 juft to mention a propofal which has been lately made 
 to employ glafs inllead of copper for throwing off 
 prints in the rolling prefs. That it is polfible to ufe, 
 glafs plates of great thicknefs for this purpofe, it would 
 be rafh to deny ; but the fuperiorlty of fuch plates to 
 thofe of copper we cannot conceive. It not broken 
 in pieces in the rolling prefs, they would doubtlels lall 
 longer ; but the expence of tliem at firll would pro- 
 bably be greater, and the engraving on thcin could not 
 be fo fine. 
 
 GLOSSOCOMMON, in mechanics, is a name gi- 
 ven by Heron to a machine compoled of divers dented 
 wheels with pinions> ferving to raife huge weights. 
 
 II ] G O L 
 
 GLUCINA (a\ a peculiar earth difcovered by Glucina, 
 Vauquclin in the beryl and the emerald. Its gerieral Gold^ 
 properties are as follows : 1. It is white ; 2. Infipid ; *^"^ 
 3. Infoluble in water; 4. Adhcfivc to the tongue; 5. 
 Infulibh; ; 6. Soluble in the fixed alkalis ; 7. Infoluble 
 in ammoniac ; 8. Soluble in the carbonat of ammo- 
 niac ; 9. Soluble in almoll every one of the acids (ex- 
 cept the carbonic and ph ifphoric acids), and forming 
 falls of a faccharine talle ; lo.-Fufible with borax into 
 a tranfparent glafs; 11. Abfurbs one fourth of its 
 wciglit of carbonic acid; 12. Decompofes the alumi- 
 nous falls; 13. Is not preeipitable by well faturated 
 hydro-fulphurets. 
 
 The fpecific charafters of glucina, which are united 
 in none of the other known earths, are : 1. Its falts arc 
 faccharine, and flightly aftringent ; 2. It is very fo- 
 luble in the fulphuvic acid by cxcefs ; 3. It decompofes 
 the aluminous falls ; 4. It is foluble in the carbonat 
 of ammoniac ; 5. Is coirpletely precipitated from its 
 folutions by ammoniac ; 6. Its affinity for the acids is 
 intermediate between magntfia and aluminc. 
 
 One hundred parts of bery-l contain 1 6 of glucina; 
 but for the bell tnethcd of analyzing the beryl, and of 
 courfe obtaining the earth, we mult refer our readers 
 to the article Mineralogy in this Supplement; and 
 fiiall conclude this fhort article with a valuable and ju- 
 dicious remark of Vauquehn's. 
 
 " It almoft always happens (fays this able chemift), 
 in the fciences of ubfcrvation, and even in the fpecu- 
 lative fciences, that a body, a principle, or a property, 
 formerly unknown, though it may often have been 
 ufed, or even held in the hands, and referred to other 
 fimple fpccies, may, when once difcovered, be after- ' 
 wares found in a great variety of fituations, and be ap- 
 plied to many ufcful puipoles. Chemiltry affords ma- 
 ny recent examples of this truth. Klaproth had no 
 fooner difcovered the difi'erent fubftances with which 
 he has enriched the Icicnce, but they were found in va- 
 rious other bodies ; and if I may reter to my own pro- 
 ceffes, it will be feen, that after I had determined the 
 characters of chiome, firlt found in the native red lead, 
 I eafily recognized it in the emerald and \he ruby. 
 The fame has happened with regard to the earth of 
 the beryl. I have likewife detected it in the emerald ; 
 in which, neverthelefs, it wan overlooked both by Kla- 
 proth and myfclf in our firtt analyfis : fo difficult it is 
 to be aware of the prefence of a new fubilance, parti- 
 cularly when it poffeffes fome piopeities refembling 
 thole already known !" 
 
 GOLD, the moft perfeft of all the metals. See 
 CHiiMisTRV-Z/ir/fx in this Supphmeiit. 
 
 It has been a very common opinion among metallur- 
 gilfs, that tin has the property of deltroying the dufti- 
 lity of gold, on being melted with it even in very fmall 
 quantities ; and Dr Lewis adds, that even the vapours 
 which arife from tin in the fire, make gold fo brittle, 
 that it flies in pieces under the hammer. This opi- 
 nion was controverted by Stanefby Alchorne, Efq ; of 
 his Majefty's mint, who made a fet of experiments, 
 which, in his opinion, aulhorife a very dilferciit conclu- 
 fion, viz. that though tin, like other inferior metals, 
 
 will 
 
 (a) This name was given to the earth of beryl by the editors of the Annales de Ch'tmk. Its moft charaifle. 
 riftic property being that it forms falts of a faccharine tafte, they gave it a name derived from >.Auxaiv4', to rendsr 
 fweet. According to this etymology, fhould not the name be Cljcina ?
 
 'Oil}. 
 
 tfthe A:j- 
 {iemy of Sci- 
 . tnces at Pa- 
 th for ([': 
 
 G O L [71 
 
 will contaminate gold in proportion to the quantity 
 mixed with it, yet there does not appear in tin any 
 thing fpecifically ininnical to that precious metal. 
 
 As we hnve elfcwhere (fee Chkmistry, n'" 1091, Uc. 
 Encycl.) enuinerated thefe experiments, and admitted 
 the conclufion drawn from them, it becomes our duty, 
 in this place, to flate what has been urged againll that 
 coficluficn. 
 
 M. '^I'illet, being in his own mind perfuaded that tin 
 renders gold fo biitde that it cannot be reduced to thin 
 leave."., and far lels be made to pafs through the wire- 
 plate but by virtue of repeated annealing, and peculiar 
 treaunent, which gold of the ufual duttility does not 
 require, determined, from refpecl to M. Alchorne, to 
 repi-at his experiments. 
 
 His lirlt experiment* confided in mixing 24 grains 
 of fine gold with one of tin which contained no arfe- 
 ■ nic. He wrapped the grain of tin in the 24 grains of 
 gold reduced to a very thia leaf, and placed the whole 
 upon a piece of charcoal, fo hollowed out as to fupport 
 the mixed metal during fulicn. He even Iprinkled a 
 finall quantity of calcined borax upon the metal, in or- 
 der that the fufion might be more fudden, that the 
 metal might flow together, and the tin unite with the 
 gold, without allowing time for it to become calcined. 
 This alloy was fpeedily fufed by the enameller's lamp, 
 and reduced into a fmall button without any lofs of 
 weight. It was then flattene<l carefully beneath the 
 liammer; but, notwithftanding his utmoft precaution in 
 this refpeiA, it cracked, and at lall broke into three 
 pieces, its thickuefs then being a quarter of a line or 
 thereabouts. He repeated this experiment with a 
 double quantity as well of pure gold as of tin, and the 
 relult was the fame. 
 
 He next alloyed 4 ounces of gold, of the finenefs of 
 2 2 carats, with i gros 24 grains of tin deprived of ar- 
 fenic, or, in other words, with 4 pennyweights of tin ; 
 and thefe two metals being reduced into finall pieces, 
 were mixed together, put into a crucible, and urged 
 by the ftrong heat of a forge with two pair of bellows. 
 When their tufion appeared to be complete, he poured 
 the metal into a fmall ingot mould proportioned to the 
 quantity. 
 
 The ingot thus obtained had loft fcarcely ajiy thing 
 cf the weight of the two metals that compofed it ; 
 which was a proof that the tin had united and incor- 
 porated with the four ounces of gold. But on attempt- 
 ing to bend the ingot, which was about fix inches 
 long, and not more than two or three lines thick, he 
 remarked, contrary to the nature of gold of 22 carats, 
 th:it it was rigid, and would have required a confider- 
 abie effort to give it anv degree of curvature, or bring 
 it to the liexibility it wr>uld have poffctred if no tin had 
 entered into its compofition. Not fatisfied, however, 
 with the inferci ce naturally flowing from this circum- 
 Itance, he proceedeo to the proper teft by hammering, 
 particularly with the edge of the hammer, in order 
 that the bar might be lengthened, and by that means 
 fnbmittcd to the ppoft decifive proof. He did not ob- 
 ferve, during the continuation cf this procefs, till the 
 bar was reduced to about two-thirds of its firfl thick- 
 nefs, that its edges were cracked, or exhibited much 
 of the appearance of britllcnefs ; but as he was appre- 
 henfjve that this accident might happen by too long 
 hammering, he dividetj the bar by cutting off the part 
 
 2 ] G O X 
 
 which had been hammered out. This part was placed 
 in the midll of lighted charcoal, in order that, by a ~" 
 moderate annealing, it might recover the flate of mal- 
 leability it pofllfled before it was hammered. But when 
 he went to take it out of the fire, where it had under- 
 gone no grealir heat than a cherry-red, he found it di- 
 vided into two parts. After having fuffcred thefe to 
 cool, he forged them again. They were extended witli 
 confiderable eafe, though with fome cracks at the edges; 
 btit tliey did not yet fa'isfy the whole of his entjuiries. 
 He therefore annealed one of the two lad mentioned 
 pieces a fecond time, and referved the other in its hard- 
 hammered ilate to be pafTed between the laminating 
 rollers. The annealed part, vihich might have the 
 tliicknefs of about a fhilling, broke in the hre, though 
 the heat was very gentle, into four or five portions. 
 Tlie longed of thefe portions, which bed refilled the 
 aftion of the lire, bent and twided itfelf, and (hewed, 
 by this date of drongcontraftion in diderent directions, 
 that it had tended to break and become divided into 
 fmall portions, firailar to thofe which liad already fepa- 
 rated from it. 
 
 Satisfied by this experiment that the piece of the 
 mixed ingot which he had kept in its hammer-harden- 
 ed flate would not bear annealing, he determined to 
 extend it ilill more between the rollers, fetting them 
 up very gradually, in order that the fraclure, if it Ihould 
 take place, might be principally owing to the britllc- 
 nefs of the material, and not to the force of corapref- 
 fion to which it was fubjeded. By this management 
 he fucceeded in extending the metal to doable its 
 length notwithdanding its hardnefs, and rendering it as 
 tliin as ilrong paper ; though the edges were cracked 
 through their whole length like the teeth of a faw. 
 But this accident is not at all furpriling, when it is 
 confidered that gold, thoi:gh alloyed finiply with cop- 
 per, whatever may be the caufe, does not poffefs its 
 ufual duclility,particuiar!y when it is laminated very thin, 
 without repeated annealing as the metal becoraec hard. 
 
 Aware that the fraClure of the pieces of gold might 
 be attributed to an incomplete fufion, or imequal mix- 
 ture of the two metals, he melted the whole ingot over 
 again with the utmod precaution ; but in vain. The 
 metal was as brittle as formerly, and would not bear 
 anneahng. 
 
 He next fufed fix ounces of pure gold of 24 carats 
 with 2 gros, or 6 penny-weights of tin, taking every 
 polTible precaution to have the metals completely mix- 
 ed. When the whole was in perfe<S fufion, he poured 
 the mi)iture into an ingot mould, and obtained an in- 
 got rather longer and cleaner than the two former. 
 As foon as it was cold he forged one of its extremities 
 with the edge of the hammer. It was lengthened 
 without any perceptible crack ; and when it was re- 
 duced to the tliicknefs of one line, or thereabouts, he 
 cut it off for ftparate treatment. By moderate anneal- 
 ing it maintained its integrity ; and, with the excep- 
 tion of a few tracks, it pafTed the laminating rollers 
 without breaking. As he was fearful, neverthelcfs, 
 that It might break in fome part if he continued to la- 
 minate it, he gave it a flight annealing. It had fcarce- 
 ly acquired a cherry-redncfs between the charcoal, be- 
 fore it broke into five or fix parts, fome of which were 
 fimply bended or twided, and others flat as they quit- 
 ted the rollers. Among the annealed pieces of this 
 
 extremity
 
 G O L . I^ 7 
 
 Ofild. extremity of the ingot, there was oiio fuffirlciitly long, 
 ""-^r— though a little curled, which he hiniinuted a fccotnl 
 time, witii the determinaliou of rendering it very thin 
 without the leaft annealing. It acquired at leall double 
 the length it had at (irll without breaking; and, if we 
 except the two fides of this plate which were cracked, 
 the body, or main piece, was entire. It was fpongy, 
 and might be conhdered as if formed out of an ingot 
 of common gold containing no tin, but not poirelling 
 the whole of its natural ductility. 
 
 " It follows, fays INI. Tillet, from thefe experiments, 
 that gold, whether fine or alloyed, when pcrfedlly fufed 
 with a finall portion of the lined tin, acquires rigidity 
 and hardnefs by the mixture ; that it lofts fomewhat of 
 its dillniguilhing colour ; and that it may, indeed, by 
 careful management, be extended to a certain degree 
 by the hammer, or ftill better by the rollers ; but tlxat, 
 as it cannot be annealed without danger of breaking, it 
 is by this defedl deprived of t lie effential advantage of 
 recovering its original foftnefs after it has been ilrong- 
 ly hammer-hardened. It is not but by careful majiage- 
 ment in the ufe of the hammer, and by frequent an- 
 nealing, that artifts enjployed on works of gold and fil- 
 ver fucceed in obtaining them without cracks, and 
 liringing them to a llate of perfeClion, without being 
 obliged to have recourfe to folder to repair the defecfts 
 which exceflive hardnefs under the hammer would oc- 
 cafion. How much, therefore, ought gold-woi kers, 
 who continually have this metal in tiieir hands, to be 
 attentive to prevent the introduction of tin in their 
 vvorkfliops, and never to employ fuch compounds of 
 gold as are fubjeft to break, or even to warp, while 
 annealing? The expence of refining, which they would 
 pay for depurating fuch compounds, would be of lefs 
 confcquence to them than the lofs of time required for 
 the careful management of fuch gold contaminated by 
 tin, even if they did fucceed in ufing it, and were not 
 often forced to abandon, after much labour, a work 
 nearly finilhed. 
 
 " If it be allowable (continues our author) to form 
 conjeflures on the caufe of the fraflure of plates of gold 
 containing tin, when fubjefted to the annealing heat, it 
 may be prefumed, fince tin very fpeedily melts, while 
 gold requires a ftrong heat for its fufion, that the parts 
 of the tin intermixed in a fort of proportional equality 
 with thofe of the gold, tend to feparate by a fpeedy tu- 
 fion and at a very gentle degree of heat ; that they re- 
 main without confiftence between the parts of the gold, 
 while the latter prcferve tlx whole of their folidity, and 
 do not lofe it even by the annealing heat : whence it 
 feems, that the parts of the precious metal, when igni- 
 ted among the coals, having no longer the folid con- 
 nexion f(n-med by the tin, but, on the contrary, having 
 an infinite number of fmall cavities occupied by parti- 
 cles of that metal In fufion, muft tend to difum'on ; 
 whereas the fame accident does not take place in the 
 pieces which have refiiled the annealing, and have been 
 laminated after cooling, becaufe the particles of tin 
 have become folid by cooling, and have recovered their 
 original ftate of union with the gold. 
 
 " This frafture of the compound does not take place 
 with an alloy of gold and copper, for an oppofite rea- 
 fon to that which has here been explained ; namely, 
 becaufe thefe two metals require nearly the fame heat 
 for their fufion. The effeft of annealing being there- 
 
 SuFPL. Vofc. I. Part II. 
 
 13 ] G O L 
 
 fore equal upon both, the metals, notwilliftandi'ng this OVd, 
 treatment, preferve their natural c onfillejice, even tho' '^'' ""' 
 the heat be carried near the point of fufion." ' 
 
 Got.n-Lcaf. .See GoU-Lfaf i^Encyc!.), where a full 
 account is given from Dr Lewis of the procefs of gold- 
 beating. In that article we have fald that giild-lcaf 
 ought to be prepared from the fineft gold ; but Mi- Ni- 
 cholfon, who in all probability kiiows iiitich more of the 
 matter than the author from wliom our account was co- 
 pied, allures us tliat this is a miltake, and that pure gold 
 is too ductile to be worked between the goidbeater'.i 
 llvin. The newert fl<ins will work the fineft gold, and 
 make the thinnell leaf, becaufe tluy are the fnioothelh 
 Old flvins, being rough or foul, require coarfer gold. 
 The finer the gold, the more dutlile ; infi)inuch that 
 pure gold, when driven out by the hammer, is too foft 
 to force itfelf over the irregularities, but would pafs 
 round them, and by that means become divlrled into 
 narrow flips. The finelt gold for this purpofc has three 
 grains of alloy in the ounce, and the coarftft twel'j 
 grains. In general, the alloy is fix grains,, or one- 
 eightieth part. That which is called pale-gold c>n. 
 tains three pennyweights oj filver in the ounce. The 
 alloy of leaf-gold is iiJver, or copper, or both, and the 
 colour is produced of various tints accordingly. Two 
 ounces and two pennyweights of gold is delivered bv 
 the mailer to the workman, who, it extraordinary flcii- 
 ful, returns two tluHiland leaves, or eighty books of 
 gold, together with one ounce and fix pennyweights of 
 wafte cuttings. Hence one book weighs 4.8 grains ; 
 and as the leaves meafure 3.3 inches in the fide, the 
 thicknefs of the leaf is one two hundred and eighty-two 
 thoufandth part of an inch. 
 
 The yellow metal called Dutch gold is fine brafs. It 
 is faid to be made from copperplates, by cementation 
 with calamine, without fubfequent fufion. Its thick- 
 nefs, compared with that of leaf gold, proved as 19 to 
 4, and under equal lurfaces it is oonfiderably more than 
 twice as heavy as the gold. NicholJ'on's Journal., vol, 
 lit. 
 
 GOLDONI (Charles), was born at Venice in the 
 year 1707. He gave early indications of his humour- 
 ous character, as well as his invincible projienfity to 
 thofe ftudies which have rendeied his name innnortal. 
 His father, perceiving that the darling amufemeiit of 
 his fon was dramatic performances, had a fmall theatre 
 erefted in his own houfe, in which Goldoni, while yet 
 an infant, amukd hinifelf with three or four of his com- 
 panions, by acting comedies. Before he was lent to 
 fchool, his genius prompted him to become an author. 
 In the feventh and eighth years of his age, ere he had 
 fcarcely learned to read corredly, all his time was de- 
 voted to the perufing comic writers, among whom was 
 Cicogmni, a Florentine, little known in the dramatic 
 commonwealth. After having well ftiulied thefe, he 
 ventured to Iketch out the plan of a comedy, which 
 needed more than one eye-witnefs of the greatefl pro- 
 bity to verify its being the produftion of a child. 
 
 After having finifiied his grammatical iludics at Ve- 
 nice, and his rhetorical ftudies at the Jefuit's college in 
 Perugia, he was fent to a board ing-fchool at Rimini 
 to ftudy philofophy. The impulfe of nature, how- 
 ever, fuperfeded with him the ftudy of Ariftotle's 
 works, fo much in vogue in thofe times. He frequent- 
 ed the theatres with uncommon curiofity; and parting 
 4 X gradually
 
 G O L 
 
 [ 7'4 1 
 
 G O I. 
 
 Oolduni. giradually from the pit to the ftac^e, entered into a fa- 
 '■ ' » miliar acquaintance with the aftors. When the fea- 
 fon of comic performances was over, and the adtors 
 were to remove to Cliiozza, young Goldoni made his 
 efcape in their company. This was the firft f^nh he 
 committed, which, a'.-cordinjr to his own coiifelTion, 
 drew a great many others ailcr it. His father had in- 
 tended him to be a phyfician, like himfelf : the young 
 nKi;i, however, was wliolly averfe to the ftudy. He 
 piopofed afterwards to make him an advocate, and lent 
 him to be a praftitinr.er in Moden.i. An horrid cere- 
 mony of ecclefiallical jurifdidiion, at which he was pre- 
 fent, infpired him with a melancholy turn, and he de- 
 termined to become a capuchin. 
 
 His father, perceiving the whimfical, inconflant hu- 
 mour of his fon, feigned to fecond this propofal, and 
 promifed to go and prefent him to the guardian of 
 the capuchins in Venice, in the hope that, after forre 
 ftay in that extenfive and merry city, his melancholy 
 fit would ceafe. The fcheme fuccceded ; for the young 
 man, indulging in all Itie fi;{hion;:blc diifipation of the 
 place, was tuitd of his foclifh refolution. It was how- 
 ever neceflary for him to be fettled in fome employ- 
 ment ; and he w.is prevailed upon by his mother, after 
 the death of his father, to cxercife the profefBon of a 
 .lawyer in Venice. By a fudden reverie of fortune he 
 M^as compelled to quit at o ice both the bar and Ve- 
 nice. He then went to Milan, where he was employ- 
 ed by the refident of Venice in the capacity of fecre- 
 tary ; where becoming acquainted with the manager of 
 the theatre, he wrote a farce, entitled // Gondoliere Ve- 
 aeziano, the Venetian Gondolier; which was the firft 
 comic produftion of his that was performed ami print- 
 ed. Soine time after, Goldoni broke with the Vene- 
 tian refident, and removed to Verona. 
 
 There was in this pl.-.ce, at that lime, the company 
 of comedians of tlic theatre of St Samuel of Venice, 
 and among them the famous aftor Co/all, an old ac- 
 quaintance of Goldoni, who introduced him to the ma- 
 nager. He began therefore to work for the theatre, 
 and became infenfibly united to the company, for which 
 he compofcd feveral pieces. Having removed along 
 ■with them to Genoa, he was for the firft time feized 
 ■with an ardent paflion for a lady, who foon afterwards 
 became his wife. He returned with the company to 
 Venice, where he difplayed, for the firft time, the 
 powers of his genius, and executed his plan of reform- 
 iTicr the Italian ttagc. He wrote the Momolo, Courti- 
 fan, the Squamkrer, and other pieces, which obtained 
 univerfal admiration. 
 
 Feeling a ftrong inclination to refide fome time in 
 Tufcany, he repaired to Florence and Pifa, where he 
 
 ber of new pieces for the theatre of St Luca, a fcpi- GoUioni, 
 
 rate edition of thtfe was publilhed, under the title of \r— J 
 
 The New Comic Theatre : among thefe was the Te- 
 rence, called by the author his favifurlte, and judged to 
 be the maller-pieee of his works. He made another 
 journey to Parma, on the invitation of Duke Philip, 
 and from thence he palTed to Rome. He had com- 
 pofed 59 other pieces 10 late as the year 1761, five of 
 which were defigned for the particular ufe of Marque 
 Albergati Capacelli, and confequently adapted to the 
 theatre of a private company. Here ends the literary 
 life of Golcjoni in Italy. 
 
 Through the channel of the French Ambaffador in 
 Venice, he had received a letter from Mr Zenu/.zi, the 
 fitft adtor iu the Italian theatre at Paris, containing a 
 propofal for an engagement of two years in that city. 
 He accordingly repaired to Paris, where he found a 
 fcleit and numerous company of excellent performers 
 in the Italian theatre. They were, however, charge- 
 able with the fame faults which he had correfted in 
 Italy ; and the French fuppoited, and even applauded 
 in the Italians, what they would have reprobated on 
 their own ftage. Goldoni wiihtd to extend even to 
 thai country his plan of retormation. without confider- 
 ing the extreme difficulty of the undertaking. Scurri- 
 lities and jf (Is, which are ever accompanied by actions, 
 geftures, and motions, are the fame in all countries, and 
 almoft perfeftly underflood even in a foreign tongue : 
 while the beauties of fentiment and dialogue, and o- 
 tlier things which lead to the underftanding of charac- 
 ters and intrigues, require a familiar acquaintance with 
 the tongue ot the ■writer. 
 
 The fiift attempt of Goldoni towards his wiftied-for 
 reform, was the piece called The Father for Lome ; and 
 its bad fuccefs was a fufficient warning to him to defift 
 from his undertaking. He continued, during the re- 
 mainder of his engagement, to produce pieces agree- 
 able to the general taile, and publiflied twenty-four co- 
 medies ; among vi'hich The Love of Zel'mJa and Lindor 
 is reputed the beft. 
 
 The term of two years being expired, Goldoni was 
 preparing to return to Italy, when a lady, reader to 
 the dauphinefs, mother to the late king, introduced 
 him at court, in the capacity of Italian matter to the 
 princefies, aunts to the king. He did not live in the 
 court, but reforted there at each fummons, in a poft- 
 chaife feiit to him for the purpofe. Thefe journeys 
 were the caufe of a diforder in the eyes, which afflifted 
 him the reft of his life ; fir being accuftomed to read 
 while in the chaife, he loft his Gght on a fudden, and 
 in fpite of the moft potent remedies, he could never af- 
 terwards recover it entirely. For about fix months 
 
 Vixote The Footman of Tivo Mafiers, and The Son of lodgings were provided him in the chateau of VcrfalUes. 
 
 Harlequin lojl and found again. He returned to Ve- 
 nice, and fet about executing more and more his fa- 
 vourite fcheme of reform. He was now attached to 
 the theatre of St Angelo, and employed himfelf in 
 writing both for the company and for his own pur- 
 pofes. The conftant toils he underwent in thefe en- 
 gagements impaired his health. He wrote, in the 
 courfe of twelve months, fixteen new comedies, be- 
 fides forty-two pieces for the theatre ; among thefe 
 many are confidered as the beft of his produftions. 
 The firft edition of his works was publiftied in 1753, 
 in iO vols. 8vo. As he wrote afterwards a great num- 
 
 The death, however, of the dauphin, changed the face 
 of affairs. Goldoni loft his lodgings, and only, at the 
 end of three years, received a bounty of lOO louis in a 
 gold box, and the grant of a penfion of four thoufand 
 livres a-year. This fettlement would not have been 
 fufficient for him, if he had rot gained, by other means, 
 farther funis. He wrote now and then comedies for 
 the theatres of Italy and Portugal ; and, during thefe 
 occupations, was defirous to fhew to the French that 
 he merited a high rank among their dramatic wi-iters. . 
 For this purpofe, he neglefted nothing which could be 
 of ufe to render himfelf mafter of the French language. 
 
 He
 
 GOO 
 
 e 7 
 
 Giil.'oni, lie lioanl, fpolce, and converfcd fo much In it, Uiat, in 
 0"O<i Hi>p« his 621I year, he ventured to write a comedy in l'" reach, 
 ^—-^r— anj jq ii;,ve it reprclVsited in the court theatre, on tha 
 occiifion of the marriage of the kin;;. 
 
 This piece was the Buut-ru Biinfa'ifmit ; and it met 
 uith fo great fuccefs, that the aullior received a boun- 
 ty of 150 loiiis from the king, another gratification 
 from the performers, and confiderable funis from the 
 bookfelltrs who pubhfhed it. He publidicd, foon after, 
 another comedy in French, called JJAvire FrJIueux. 
 After the death of Louis XV. Goldoni was appointed 
 Italian teacher to the Princefs Clotihle, the prefent 
 princefs of Piedmont ; and after her niairlage he at- 
 tended the late unfortunate Princefs Elizabeth in the 
 fame capacity. 
 
 The approach 'ji" old age obliged him to quit Ver- 
 failles, and to live in I'aris, the air of which, Itls fliarp, 
 was better adapted to his conlUtution. The lail work 
 of Goldoni was The Volpeni, written after his retire- 
 ment from court ; from which time he bade a lading a- 
 dieu to writing. Unfortunately for him, he lived to fee 
 liis penfions cut off at the revolution, like others, and 
 lie fpent his lail days in poverty and diilrefs. He died 
 in 1792, at a crifis when, according to the cxpreflion 
 of a deputy in the Convention, the French nation was 
 ready to repay him every debt of gratitude. 
 
 Goldoni is on a par with the grcateft comic poets of 
 modern times, with regard to dramatic talents, and is 
 thought fuperior to them all with regard to the ferti- 
 lity of his genius. His works were printed at Leg- 
 korn in I7>>b — 91, in 31 vols. 8vo. He has been ge- 
 nerally called the Molicrcof Italy; and Voltaire, in 
 one of his letters to Marquis Albergati, ilyles him The 
 Painter of Nature. Goldoni is one of thofe authors 
 whole writings will be relirtied in the moll remote 
 countries, and by the lateft pofterity. 
 
 GOOD-HOPE, or Cape of Good Hope, was fa- 
 ken by the Biitifh on 17th Auguft 179A with very little 
 difficulty. At this we need not be much furprifed, if 
 to the difcontent which muil have prevailed among the 
 planters and townlmen with the new order of things, 
 be added the manners of the people. M. Vaillant, 
 who was at the Cape during the lail war, when the 
 garrifon expected to be every day attacked by a Bri- 
 tiih fquadron, and when the people were not ahfolute- 
 ly difgulled with their own government, reprefents 
 them, however, as rendered fo completely frivolous by 
 imitating the manners of their French allies, that, 
 though the place was llrongly fortified, it could hardly 
 be expetted to hold out long againft a vigorous and 
 well condudled fiege. 
 
 " The females of the Cape (fays he), when I faw 
 them for the firil time, had really excited my allonilli- 
 ment by their drefs and their elegance ; but I admired 
 in them, above all, that modefiy and relerve peculiar to 
 the Dutch manners, which nothing as yet had cor- 
 rupted. 
 
 " In the courfe of fix months, a great change had ta- 
 ken place. It was no longer the Frencli modes that 
 they copied ; it was a caricature of the French. Plumes, 
 feathers, ribbons, and tawdry ornaments heaped toge- 
 ther, without taile, on every head, gave to the prettied 
 figures a grotefque air, which often provoked a fmile 
 when they appeared. This mania had extended to 
 
 «5 ] ^'' O O 
 
 the neighbo\irIn» plantations, where the women could ''"^i! II'>|>« 
 fcarcely be known. A mode of drefs entirely new -— v— ^ 
 was everywhere introduced ; but fo fantaflical, that it 
 woiilil have been difficult to determine from what coun- 
 try it had been imported." 
 
 At that lime a French and a Swifs regiment were iu 
 the garrilon ; and though the town was occupied orly 
 with warlike preparations, and though an attack from 
 the Biit.th fleet was every moment expedled, tlie 
 French officers !iad already introduced a talle for plea- 
 fure. Employed in the morning at their exercife, the 
 French foidiera in the evening acted plavs. A part of 
 the barracks was transformed into a tlieatre ; and as 
 women capable of performing female characlers could 
 not be found in the town, they afligiied thcfe parts to 
 fomc of their comrades, whofe youth, delicate features, 
 and frefhnefs of complexion, fcenied bell calculated to 
 favour the deception. Thefe heroines, of a new kind, 
 heightened the curiol'ity of the fpedlalors, and render- 
 ed the entertainment ib'll more lively and intereilliVT. 
 
 To add to the general jjleafure, ladies of the fir(l 
 rank confidered it as incumbent on lliem to lend to the 
 military adors and ailrefles, their iaccs, jewels, rich 
 dreffes, and mod valuable orn.Tnients. But fomc of 
 them had caufe to repent of their condelcenfion ; lor 
 it happened more than once that the Countefs of Al- 
 maviva having left in pledge at the futlling-houfe her 
 borrowed decorations, the owner, to recover them, wa» 
 obliged to dilcharge not only the bill due for brandy 
 and tobacco, but all the other delns of the heroine. 
 
 Duung the intoxication and giddinefs occaiioned by 
 thefe amulements. Love alfo did not fail to aft his 
 part ; and certain little intrigues were, from time to 
 time, brought to light, which gave employment to the 
 tongue of fcandal, and introduced unhapplnefs into fa- 
 milies. Hymen, it is true, amidd thefe adventures, 
 fometimes intervened to repair the follies of his bro- 
 ther ; and many marriages, which redored every thing 
 to order, were the refuit of his negotiations ; but the 
 complaints, though difled, did not lefs exid. The 
 watchfulnefs of the mother was alert. The hulhand, 
 by fo much the more iecretly irrifated as he faw hlm- 
 felf obliged to conceal hisjtaloufy. curfed in his heart 
 both adtors and theatre ; while the matronly part of 
 the community, Icl's on the relerve, declaimed with bit- 
 ternefs againd the licentloufnefs that prevailed, whicii 
 they wholly imputed to this mode of theatrical enter- 
 tainment. At lad, to the great mortification of the 
 young, but to the high fatlsfatllon of the eld women 
 and hufbands, the theatre was on a fudden fhut up. 
 The caufe that .rifeifted this was altogether foreign to 
 the complaints that were made, and of a nature that it 
 was impoffible to forcfce. Two of the French adors, 
 who, it mud be remembered, were officers in the army, 
 thought proper to imitate the paper money of the 
 company, and to put their forged notes in circulation. 
 The forgery was deteiled, and traced to its authors ; 
 the two theatrical heroes were baniihed from the Cai)e; 
 and the company, alhamed of the advtntuie, dared nei- 
 ther feck others to fupply the vacant ])laces, nor re- 
 fume their flage entertainments. 
 
 Intoxicating as were thefe pleafures, government 
 
 meanwhile had not been inattentive to the dann-. r 
 
 which threatened the colony. As they daily expedited 
 
 4X2 to
 
 GOO [71 
 
 Good Hope to be attacked by the Britifh fleet, they had increafed 
 '~"~v-~-' the mt-ans of defence, and ordered difFcrei-t works and 
 Dew fi_:rtitications to be conllnidUd. 
 
 At full, the buiinefs was c;irricd on with a£livity 
 ard ardciir ; becaufe the inhabitants, inftigated by tlicir 
 private intcreit, which was then confidcred as involved 
 with that of the pubh'c, had voluntarily offered their 
 fervices, and iningkd with the workmen. Young and 
 old, foldiers and magiflrates, lailors and planters, all 
 fohcited the honour of co-operating for the general 
 good and coininon fafety. To behold this heteroge- 
 neous multitude — fome loaded with pick-axes, andfotne 
 with fpades, or other fimilar impleinents — inarching 
 out in the morning from the town, and proceeding in 
 high fpirits to the new fortitications, was a fight truly 
 admirable. 
 
 But this patriotic fervo.-ir was of nn long conti- 
 nuance. Under pretence of fparing their ftrength, and 
 tliat they might not weary themfclves to no purpofn;, 
 they foon caufed their flaves to follow them with the 
 tools and iulfruments. In a little time they contented 
 themftlves with fending their flaves only ; and at lall 
 thefe fubftitules themfclvcs, in imitation of their maf- 
 ters, or perhaps by their fccret orders, gave over going 
 alfo. Their enthufiafm, in fliorl, from the lirlt mo- 
 ment of its breaking out till the period when it was 
 thus entirely cooled, had been the afiair of fomething 
 lefs than a fortnight. 
 
 This tailc for frivolity which, almoft twenty years 
 ago, was introduced among the Dutch in Cape-town 
 by their good friends the French, fpread rapidly thro' 
 the planters, who are thus defcribcd by M. Vaillant, 
 ■who certainly had the bell opportunities of knowing 
 them. 
 
 The planters of the Cape may be divided into three 
 claffes ; thofe who rtfide in the vicinity of the Cape, 
 ■within a diilance of five or fix leagues ; thofe who live 
 farther off in the interior parts of the colony ; and 
 laftly, thofe who, mort dillant (fill, are found at the 
 extremity of the frontiers among the Hottentots. 
 
 The firft, who are opulent proprietors, and have 
 handfome country houfes, may be likened to what was 
 formerly called in France petits ft'ignturs terriers, and 
 differ extremely from the other planters in eaf-. and 
 luxury, and particularly in their manners, which are 
 haughty and difdainful. Such is the refult of wealth. 
 The fecond, fimple, kind, hofpitable, are cultivators, 
 who live upon the fruits of their labour. Here we have 
 an example of the good effeiits of mediocrity. The 
 !ail, poor enough, yet too indolent to derive fubfiftence 
 from the foil, have no other rcfource than the produce 
 of fome ciiltle, which they feed as they can. Like 
 the Beduln Arabs, they think much of the trouble of 
 driving them from canton to canton, and from one 
 pallurage to another. This wandering life prevents 
 them from bm'hling any fettled habitations. When 
 their flocks oblige them to fojourn for a while in the 
 fame place, they conllrutt, in halfc, a rude kind of 
 hut, which they cover with matts, after the manner of 
 the Hottentots, whofe cuftoms thty have adopted, and 
 from whom they in no refpeft differ, but in-their com- 
 plexion and features. And here the evil is, that there 
 is no precife fituation in focial hfe to which theie mi- 
 ferable beings belong. 
 
 Thtfc fluggifli tribes are held in horror by their in- 
 
 6 ] GOO 
 
 dullrious neighbours, who dread their approach, and GnoH Hope 
 remove as far from them as they can ; becaufe, having '■~"~v~-~* 
 no property of their own, they fteal without fcruple 
 that of others, and, when iii-want of paflurage for their 
 cattle, condudl them fecretly to the firlt cultivated 
 piece of ground that comes in their way. They flat- 
 ter thcmfclves they (hall not be difcovered, and they 
 remain tdl every thing is devoured. If detedted in 
 their thefts, fquabbles and contentions enfue, and af- 
 terwards a liiit at law, in which recourfe is had to the 
 niagillrate, and which commonly terminates in making 
 three men enemies, the robber, the perlon robbed, and 
 the judge. 
 
 Nothing can be fo mean and cringing as the conduft 
 cf the firll defcription of planters, when they have any 
 thing to tranfaft with the principal officers of the com- 
 pany, who may have fome influence over their lot; and 
 nothing fb abfurdly vain and fo fuperlatively infolent 
 as their behaviour to perfons-from whom they have no- 
 thing to hope and nothing to fear. Proud of their 
 wealth, fpoilcd by reliding near a town, from whence 
 they have imbibed only a luxury that has corrupted, 
 and vices that have degraded them, it is particularly to- 
 wards itrangers that they exercife their furly and piti- 
 ful arrogance. Though neighbours to the plantcra 
 who inhabit the interior of the country, you muft not 
 fuppofe they regard them as brethren ; on the contrary, 
 in the true fpirit of contempt, they have given them 
 the name of Rauw-boer, a word anfwering to the low- 
 eft defcription of clown. Accordingly, when thefe 
 honeft cultivators come to the town upon any kind of 
 bufmefs, they never flop by the way at the houfes of 
 the gentry of whom we are fpeaking ; they know too 
 well the infulting manner in which they would be re- 
 ceived. One might fuppofe them to be two inimical 
 nations always at war, and of whom fome individual* 
 only met at diltant intervals, upon bufinefs that related: 
 to their mutual intereifs. 
 
 What is the more difgufting in the infolence of thefs 
 Africans is, that the majority of them are defcended 
 from that corrupt race of men, taken from prifons and 
 hofpitals, whom the Dutch company, defirous of form- 
 ing a fettlement at the Cape, fent thither to begin, nt 
 their rifk and pearl, the population of the country. 
 This (hameful emigiation, of which the period is not 
 fo remote but tliat many circumftances of it are re- 
 membered, ought to render particularly modeft thofe 
 who are in the moll dillant manner related to it. Oi». 
 the contrary, it is this very idea that mod; contributes 
 to their arrogance; as if they flattered themfelves that, 
 under the guife of fupcrcilioiis manners, they could 
 hide the abjtftnefs of their origin. If a flrauger ar- 
 rives at the Cape with the delign of remaining and 
 fettling tiiere, they conceive him to be driven from his 
 country by the lame wretched circumflances which 
 formerly baiiilhed their fathers, and they treat hinv 
 witii the mofl fovereign contempt. 
 
 This melancholy failing is the more to be lamgaited 
 as the contagion has fpread through almoil every rell- 
 dence about the Cape, which is in reality a very charm- 
 ing canton. Embelliihed by cultivation, by. its nume- 
 rous vineyards and pleafant country houfes, it every- 
 where exhibits fo varied and delicious a profpedl, that^ 
 were it occupied by other inhabitants, it would excite 
 no fenfations but thofe of pkafure. 
 
 A3
 
 GOO 
 
 [ 7 
 
 Good FTop" As we advance into the country, the planters ai'C a 
 
 '^'~-^ I'ort of fai-rticrs f and conllitiite, by their mamiers, cuf- 
 
 toiiis, and occupations, a clafs by tlicinlelves, perfectly 
 dillinct from wiiat we have beer delcribin^r. Situated 
 farther from the Cape, and, of confequence, not ha- 
 fiiu'' the fame opportunities for diipofinj;; of ti\eir com- 
 modities, they are lefs rich than the firft. We fee a- 
 mong them none of thofe agreeable country houfcs, 
 which, placed at different dillances from the town, em- 
 bellilh the country as we pafs, and aflVvd fuch ciiarni- 
 hvr prufpedts. Their habitation, which is about tlie 
 fize of a large coach-honfe, is covered with thatch, and 
 divided into tliree rooms by mer.ns of two partitions, 
 wiu'ch reach only to a certain height. The middle a- 
 j>artment, in which is the entrance to the houfe, ferves 
 iit once both as a parlour and eating-room. It is there 
 that the famllv reiide during the day, and that they 
 receive their tea and other viiitors. Of the two other 
 rooms, one forms a chamber for the male children, and 
 the other for the females, with the father and mother. 
 At the hack of the middle apartment is a farther room 
 fcrving for a kitchen. The reit ot the building con- 
 iilU of barns and ilables. 
 
 Such is the dillribution which is generally followed 
 in the interior plantations of the colony ; but nearer to 
 the frontiers, where there does not prevail the lame 
 eafe of circnmftances, the liabitations are much lefs 
 commodious. They are merely a barn, confiding of a 
 fingle room, without any divifion, in whicii the whole 
 family live together, without feparating either day or 
 night. They fleep upon Ihecp flcins, which ferve 
 them alfo for coviii'ing. 
 
 The drefs of thefe planters is fimple and rnflic. That 
 of the men confifts of a cheek Ihirt, a waidcoat with 
 flceves, a large pair of trowfcrs, and a hat half unloop- 
 ed. The women have a petticoat, a jacket iitted ru 
 their Ihnpe, and a little round bonnet of muflin. Un- 
 lefs upon extraordinary occafions, neither fex wear 
 (lockings. During a part of tlie year, the women e- 
 ven walk with their feet quite naked. The occupa- 
 tions of the men require tliat theirs Ihould have lome 
 covering; and this covering they make from a piece of 
 the hide of an ox, applied and fliaped to the foot fooii 
 after the animal is killed, and while the hide is yet 
 frtfh. Thefe fandals are the only article of their drefs 
 which they make themfelves ; the reft is the bulinefs of 
 the women, who cut out and prepare their »vholc ward- 
 robe. Though the equipment we have mentioned con- 
 llitute the every-day drefs of the planier, he has, how- 
 ever, a coat of handfome blue cloth, which he wears 
 upon days of gala and ceremony. He has then alio 
 (tockiiigs and (hoes, and is dreffed exadtly like an Eu- 
 ropean. But this finery never makes its appearance 
 but when he goes to the Cape ; and then, indeed, is 
 nut put on till he arrives at the entrance ot the tov/n. 
 
 It is commonly in thefe journeys that tliey purchafe 
 inch things as they may want to relit their wardrobe, 
 'I'here is, at the Cape, as well as in Paris and London, 
 a fpecies of old- clothes-men, who deal in commodities 
 of tiiis fort ; and who, from their enormous profits, and 
 the extortion they praclife, they have obtained the 
 name of Ca^fe Smoufe, or Cape Jews. Thefe traffick- 
 ers contrive at all times to IcU their goods at a dear 
 rate ; but they vary their price in proportion as their 
 ilock is great or Imall : of cuurfe they bear no fined 
 
 17 '! GOO 
 
 price J and the planter who comes from the dtfcrt, and Good Hope 
 who can undentand but little of this faidnaiion, is lure """^ ' 
 to be duped. 
 
 On the other hand, the regular fliopkeeper, who 
 knows the probity of thcle farmers, and how pundtual 
 they are in the payment of their debts, exerts every ef- 
 fort to prevail on them to open an account with him. 
 He tempts ihem by the pretended clieap price and ex- 
 ctlient quality of his (lufl.s, and offers to remit the pay- 
 ment till their next journey in the following year. It 
 is feldom that thefe pecjple, fimple and unexperienced 
 as they are, perceive the craft that is prcfented to them 
 under' this guile of kindnefs and civility. If they fuf- 
 fer themlelves to be prevailed upon, they are (hackled 
 for life. Upon their return, there are new purcliafes 
 to be made upon the fame conditions ; and thus, year 
 after year, always in debt, always buying without 
 prompt payment, they become the prey of an extor- 
 tioner, who raifcs to lii.i.fclf a foitune out of their 
 weaknela. 
 
 It is true, thefe buyeis, after being thus duped at 
 the Cape, commonly return home only to make dupes 
 of others. The cunning that has been employed to 
 deceive them, they employ in their turn to tempt the 
 Hottentots who are in thtir fervice. The remnants of 
 (luff, or the frippery garments which they bring back, 
 are fold to thele uniortunate fervants with fo great a 
 profit, that commonly the wages of a year are inade- 
 quale to the payment ; and they find themfelves, like 
 their mailers, in debt for the year that is to come. In 
 the end, therefore, it is tlie poor Hottentot that pays 
 for the extortion at the Cape. 
 
 Cuilom has rendered the planters infenfible to the 
 want of fruit and pnlfe, though the foil is admirably 
 adapted to the cultivation of both. Tlie facility witli 
 which they rear their cattle makes up for this priva- 
 tion, as their flocks afford tliem plenty of provilion. 
 The chief food is mutton ; and tiicir tables are loaded 
 with luch protufion as to difgull one at the fight. 
 
 From this mode of living, cattle are in the colonies, 
 as in other places, not only a ultful objctl, but an ar- 
 ticle of the firft neccCity. Tlie planter undertake* 
 himfelf the care o; watching over his flocks. Every 
 evening, when they return from the field, he (lands at 
 his door, with a (lick in his hand, and counts them over 
 one by one, in order to be furc that none of them are 
 inilTing. 
 
 People who have no other employment than a little 
 agriculture, and the fuperintendance of a flock, muft 
 have long intervals of idiencfs. It is thus with thii 
 planters, particularly thofe who live in the interior parts 
 ot the country, and who being unable, on account of 
 tlieir dillance fi'om the Cape, to difpofe of their corn, 
 never raife mine than is fuBicicnt for their own con- 
 luiiiption. From the profound inatlion in which they 
 live, one would iuppole their fu^renie felicity to confilt 
 in doing nothing. They fometimes, however, vitlt 
 each otlier ; and upon thcle occafions the day is fijcnt 
 in fmoking, and drinking tea, and in telling, or liften- 
 ing to tales of romance, that are equal neither in merit 
 nor morality to the ftory of Blue-beard. 
 
 As every man always carries with him, wherever he 
 goes, both a pipe, and a tobacco-pouch made of the 
 (Icin of the fea-calf, he is fure in thefe vifits to have on* 
 fource of amufcment. When any one of the company) 
 
 is-
 
 G O N [7 
 
 Hi'itA Hope Js defirous of lighting his pipe, he takes out his pouch, 
 and, having filled, pafFes it to the rcll. This is 2 civi- 
 lity that is never omitted. However numerous may 
 ' Ije tlie party, every body fmokes : the cotiiequencc of 
 which is a cloud, tiiat, rifing at tirfl; to the upper part 
 <if the room, inoreafes, by decrees, till it fills the whole 
 lioufe, and becomes at lall fo tliick tluit it is impoflible 
 for the fmokers to iec one another. 
 
 When a fti-anper travelling through tlie co\intry is 
 received by the mafttr of a houfe, he indantly bcoomes 
 a mtiiiber of the family. Accullomed to a domeilic 
 lite, the planters delight in the ties of affinity, and con- 
 fider in the light of a relative every pcrfon whom they 
 love. Upon entering a honfe, the form of falucation is, 
 to fliake hands full with the mailer, and then with eve- 
 ry male perfon in the comjiany arrived at years of ma- 
 turity. If there happens to be any one whom we do 
 not like, the hand is refuted to him ; and this r<rfulal, of 
 lo common a teftimony of friendllu'p, is looked upon as 
 a formal declaration that the vifitor confiders him as 
 his enemy. It is not the fam.e with the females in the 
 company. They are all embraced cne after another ; 
 and to make an exception would be a fignal aflroiit. 
 Old or young, all mull he killed. It is a benefice with 
 ahe duties attached to it. 
 
 At whatever time of the day you enter the houfc of 
 a planter, you are fure to find the kettle and tea-things 
 upon the table. This praftice is univerfal. The inha- 
 bitant;; never drink pure water. If a ftranger prefents 
 liimfelf, it is tea they otFer him for refrelliment. This is 
 their common liquor in the interval of meals, and in one 
 feafon of the year, when it often happens that they have 
 neither beer nor wine« is their only beverage. 
 
 If a ftranger arrives at dinner-time before the clotii is 
 taken away, he lliakes hands, embraces, and immediately 
 feats himfelf at the table. If he wiflies to pafs the 
 night, he ftavs without ceremony, fmokes, drinks tea, 
 alks the news, gives them all he knows in his turn ; 
 and the next day, the kiffing and fhaking hands being 
 repeated, he goes on his way, to perform elfewhere the 
 fame ceremony.' To offer money on thefe occaiions 
 would be regarded as an iniult. 
 
 Thefe parlicnbis of a people, whofe condition it is 
 to be hoped that the gtnerofity of the Britifh charac- 
 ter, and the mildnefs of the Britilli governinent, will 
 gradually meliorate, cannot but be acceptable to many 
 of our readers. Wc fhall, therefore, make no apology 
 for the length of this article. 
 
 GOMASHTEH, in the language of Bengal, one 
 cent. 
 
 GONIOMETRY, a method of meafuring angles, 
 fo called by M. de Lagny, who gave feveral papers on 
 this method in the Memoirs of the Royal Acad, anno 
 1724, 1725, '729' M. de Lagny's method of gonio- 
 tnetry confifts in meafuring the anglse.with a pair of 
 compaifes, and that wijhout any fcale whatever, except 
 an imdivided iemicirclt. Thus, having any angle drawn 
 upon paper to be mcafured, produce one of the fides 
 of the angle backwards behind the angular point; then 
 with a pair of fine compaifes dcfcribe a pretty large 
 femicircle from the angidar point as a centre, cutting 
 the fides of the jTopofed angle, which will intercept a 
 part of the femicircle. Take then this intercepted part 
 very exaflly between the points of the compafies, and 
 turn them fucceflively over upon the arc of the fenii- 
 
 :79 s 
 
 18 ] G li A 
 
 circle, to find how often it is contained in it, after wliich 
 there is commonly fon.e remainder: then take this re- 
 mainder in the eomj)alfes, and, in like manner, find how 
 often it is contained in the laft of the integral parts of v 
 the firft arc, with again fonie remainder : find, in like 
 manner, how olten this lad remainder is contained in 
 the former ; and fo on continually, till the remainder 
 become too iimll to be taken and applied as a ineafnre. 
 By this means he obtains a feries of quotients, or frac- 
 tional parts, one of another, which being properly redu- 
 ced into one fraclion, give the ratio of the firll arc to 
 the femicircU, or of the propofed angle to two right an- 
 gles, or i3o degrees, and confequently that angle itfelf 
 in degrees and minutes. 
 
 We have given this account of goniometry from Dr 
 Huttoii, and frankly acknowledge that we had never 
 thought of it till we pcrnfed his excellent Diftiouary of 
 Mathematics and Philolopiiy. To have omitted the 
 method when pointed out to us would have bten wrong ; 
 though we midake much if mathematicians in general 
 ■will net look upon it as a method of very Utile value. 
 
 GOTHIC Architecture. See Gcihic Akchiiec- 
 ruRE in this Suppl. and Roor, Enrycl. 
 
 GOUVERNANTE, the Spanilh name of a plant 
 which the Indians of California ufe in decoClion as a 
 fudorific drink for the cure of the venerial difeafe. It 
 is thus defcribed in the third volume (Englifh tranQa- 
 tion) of Perouft's Voyage round the World. 
 
 Calyx quadrified, egg-fliaped, of the lame fize with 
 the corolla ; placed beneath the fruit, deciduous. Co. 
 rolla pcilypctalous ; petals four, fmall, entire, cgg-ilia- 
 ped, fixed upon the receptacle, titamina, eight, fixed 
 to the receptacle, of the fame length as the corolla : 
 threads channelled, concave on the one fide, and con. 
 vex on the other ; wings veiled, anthers liinple. Piftil, 
 g'.rm oblong, cnvcrtd, with five angles, and five cells; 
 leeds oblong ; pcricarpium covered with fine hairs. 
 
 This plant is a Ifirub of middle fize ; the branches 
 are angular and knotty, and covered with an adhcfive 
 varnifh ; the lateral branches are alternate, and placed 
 very near to each other : the leaves are fmall, petiola. 
 ted, bilobed, oppofite, imooth on the upper fide, the 
 under fide indiilifiClly veined ; the blolfoms are axillary, 
 fometimes terminating, pedunculated, folitary, but fome. 
 times in pairs. 
 
 From this defcriptlon, the gouvernante appears to 
 be a new fpecies of daphne. 
 
 GRAVIMETER, the name given by citizen Guy- 
 ton (Morveau) to an indrument of glafs, ci/ndru&ed 
 in all refpeCls on the principle of NichoUon's Hydro- 
 meter, deticribed in the article Hydrostatics, 11° 18. 
 EiHytl. It is therefore needlefs to give a delcription 
 of tills indrument here ; as every artift in glafs, who has 
 feen Nicholfon's hydrometer, or underftands our de- 
 fcriptlon of it, may conftruci the gravimeter of Mor. 
 veau ; and every man who has made himfelt mafter of 
 our article Specific Gravity, may apply the gravimeter 
 to every purpofe to which it is applicable. It may juit 
 be proper to obferve, that Morveau, having at firft load- 
 ed the fmall fcale or baion G (Plate 240, fig. 9. En- 
 cycl.) with a bulb of glafs containing a iufficient quan- 
 tity of mercury, found it expedient afterwards to lub- 
 ftitute in the place of this bulb a fmall mafs of folid 
 glafs, brought to the proper form and weight by grind- 
 ing. For 4 minute account of this iuftrument, if any 
 
 of
 
 ORE 
 
 t 7 
 
 of our reaclers can be fiippofed to reqmre a nimvitc :ic- 
 cnintofit, we mull refer to the thirJ nuniher of Ni- 
 cholfon's Journiil cf Philofnphy, Chcmllry, ami the Arts. 
 
 GREEN, though one of the feven tnigiiKil or prif- 
 mntic colour.s, is among dxtrs a compound of blue and 
 vellow. Of the European methods of dyeing </rten, 
 and of the principles on which thefe methods hit 
 founded, a fufficient account will be found in the En- 
 cyclopfdia, under the articks CoiouR-Making and Dyk- 
 ing, and, in this Supplement, under An'tmal and Vegetable 
 SvBSTyiNCES ; but it may be worth while, in this place, 
 to infert the method praftifcd at Aftracan, in giving to 
 cotton yarn that beautiful green colour for which the 
 oriental cotton is fo juftly admired. 
 
 The principal dye is the blue, which is employed 
 both for cotton and filk. To prepare it, the indigo 
 or blue dye-ftuff is finely pounded, and dilfolved in wa- 
 t«r by a gentle heat in large earthen jars, feven of 
 which ftand in brick-work ever tlie lire-place, at the 
 •iiUance of about an ell and a half trom eich other. 
 Abotit two poimds are put into each vtfFel. Five 
 pounds of foda finely ponudtd, together with two 
 pounds of pure lime and one pound of clarified honey, 
 are added to er.ch ; when thefe ingrcd:ents have been 
 well mixed, the .fire is ttrengthened ; and when the 
 whole begins to boil, the dye is ftirred carefully round 
 in all the velTels, that every thing may be completely 
 diffolved and mixed. After the firft boiling the fire 
 is flackened, and the dye is fuffered to ftand over a 
 gentle heat, while it is conlinuaily ftirred round : this 
 is continued even after the furnace is cooled, till a 
 thick fcum arifes in the neck of each jar, and foon af- 
 ter difappears. The dye is then allowed to ftand two 
 days, until the whole is incorporated, and the dye 
 thickens. 
 
 The dyers affert, that with this dye they can pro- 
 duce three (hades of blue, and that, as the dyeing par- 
 ticles gradually diminifli, they can dye alfo a green ,-;o- 
 lour by the addition of yellow. 
 
 When a manufaflurer gives cotton yarn to a blue 
 dyer, he firft boils it at home in a lej of foda [iaia- 
 inr), tlicn dries it, wafnes it, and dries it again. The 
 blue dyer lays this yarn to fteep in pure water, prelfes 
 out the fuperfluous water with the hands, and then im- 
 niediately begins to dip it in the blue jar, often wring- 
 ing it till it is completely penetrated by the dye. This 
 firft tint is generally given to yarn in fuch jars as have 
 had their colouring matter partly exhaufted. It is then 
 dried, rinfed, and again dried ; after which, it is put in- 
 to the fre/h blue dye, properly faturated; and, after the 
 colour has been fuiliciently heightened, it is dried for the 
 laft time. 
 
 For a yellow dye, the dyers of Aftracan employ 
 partly faw-wort, brought from Rullia, and partly the 
 leaves of the ii/Iar beige or Jumach. The procefs Is as 
 follows : The yarn is firft boiled for an hour in a ftrong 
 ley of foda ; it is then dried, afterwards rinfed and laid 
 ■wet to fteep for twelve hours in a folutlon of alum 
 Mi/ith warm water. When it has be{n dried in the air, 
 it is laid to foak feveral times in troughs with the dye 
 which has been boiled thick in kettles from the above- 
 mentioned plants, till it has acquired the wiftitd-for co- 
 lour, care being taken to dry it each time it is foaked. 
 It is then rinfed in running water, and dried for the 
 laft time. 
 
 19 1 G R H 
 
 On this yellow colour a green is often dyed. After Oregory^ 
 the yarn has been dyed yellow^ it is given out to the *— — \r~--* 
 blue dyer, who immediately dips it in the blue jars, the 
 dye of which has been already partly exhaufted ; and 
 if the green colour is not then fufricicntly high, the o- 
 pcration is repeated, the yarn being dried each time. 
 See Neue Nord'ifehe Beprage, by Profcficr Pallas ; or 
 i'hihjiiph'ienl Mng.i-zinc. u 3. 
 
 CiKEGORY (David), was a fon of the Rev. John 
 Gregory, minifter of Drumoak, in the county of Aber- 
 deen, and elder brother to Mr James Gregory, the in- 
 ventor of the moll common refiefting tclefcope. He 
 was born about the year 1627 or 1628 ; and though 
 he poftcfred all the genius of the other branches of his 
 family, he was educated by his father for trade, and 
 ftrved an apprenticertu'p to a mercantile houle in Hol- 
 land. Having a llronger pafiion, however, for know, 
 ledge than tor money, he abandoned trade in 1655; 
 and returiu'ng to his own coiuitry, he fucceedcd, upon 
 the death of an elder brother, to the eftate of Kinar- 
 dle, fituated about forty miles north from Aberdeen, 
 where he lived many years, and where thirty-two child- 
 ren were born to him by two wives. Of thefe, three 
 fons made a confpicaous figure in the republic of let- 
 ters, being all profcft'ors of mathematics at the fame- 
 time in three of the Britifti univerfitles, viz. David at 
 Oxford, James at Edinburgh, and Charles at St An- 
 drews. 
 
 Mr Gregory, the fubjeft of this memoir, while he 
 Kved at Kinardie, was a jell among the neighbouring 
 gentlemen for his ignorance of what was doing about 
 his own farm, but an onicle in matters of learning and 
 philofophy, and paiticularly in medicine, which he had 
 ftudied for his amufement, and began to pratlife among 
 his poor neighbours. He acquired fuch a reputation 
 in that fcience, that he was employed by the nobility 
 and gentlemen of that county, but took, no fees. His 
 hours of iludy were lingular. Being much occupied 
 through the day with thofe who applied to him as a 
 ph)fician, he went early to bed, role about two or 
 tliree in the morning, and, after applying to his ftudies- 
 fiU' fome hours, went to bed again and (]ept an hour 
 or two before breakfaft. 
 
 He was the firft man in that country who had a ba-- 
 rometer ; and having paid great attention to the chan. 
 ges in it, and the correfponding changes in the wea-- 
 ther, he was once in danger of being tried by the pref- 
 bytery for witchcraft or conjuration. A deputation 
 of that body waited upon him to enquire into the 
 ground of certain reports that had come to their eais ; 
 but he fatisned them fo tar as to prevent the profccutloii 
 of a man known to be fo eKtcnlively ufeful by his know- 
 ledge of inc<licinc-. 
 
 About the beginning of this century he removed with 1 
 his family to Aberdeen, and In the time of Oneea. 
 Anne's war employed his thoughts upon an improve- 
 ment in artillery, in order to make the ftiot of great 
 guns more deftructive to the enemy, and executed a 
 model of the engine he had conceived. Dr Reld in- 
 forms us, that he converled with a clock-maker in A- 
 berdeen who had been employed in making this model ; 
 but having made many different pieces by dire'ifllon 
 without knowing their intention, or how they were fo 
 be put together, he could give no account of the 
 whole. After making fomc experiments with this mo- 
 
 del,.
 
 
 G R T [72 
 
 del, wliich fatufied him, the old gentleman was fo fan- 
 guine in the hope of being ufcfiil to the allies in the 
 war againll Fiance, that he fet about preparing a field 
 equipage with a view to make a campaign in Flanders, 
 and in the mean time fent his model to his fon the Sa- 
 vilian protefTor, that he might have his and Sir H'aac 
 Newton's opinion of it. His fon (hewed it to New- 
 ton, wilhont leiting Ijim know that his own father was 
 the inventor. Sir Ifaac was much difpleafed with it, 
 ■faying, that if it had tended as much to the prefevva- 
 tion of mankind as to their deftrudlion, the inventor 
 would have deferved a great reward ; but as it was con- 
 trived folely for deftruftion, and would foon be known 
 by the enemy, he rather deferved to be punidied, and 
 urged the profeflor very ftrongly to deftroy it, and if 
 poffible to fupprefs the invention. It is probable the 
 profeflor followed this advice. He died foon .after, 
 and the model was never found. 
 
 If this be a juil account of the matter, and Dr 
 Reid's veracity is unqueftionable, we cannot help 
 thinking that Newton's ufual fagacity had, on that 
 occahon, forfaken him. Were the implements of war 
 much more dellruftive than they are, it by no means 
 follows that more men would be killed in battle than 
 at prefent. Muflcets and cannons are furely more de- 
 ftruftive weapons than javelines and bows and arrows ; 
 and yet it is a well known ia&, that fince the inven- 
 tion of gunpowder battles arc not half fo bloody as 
 they were befoie that period. The oppofite armies 
 now feldoni come to clofe quarters, a few rounds of 
 mufl<etry and artillery commonly decide the fate of 
 the day ; and had Mr Gregory's improvement been 
 carried into efleft, ftiU fewer rounds would have decid- 
 ed it than at prefent, and the carnage would confe- 
 quently have been lefs. 
 
 When the rebellion broke out in 1 71 5, the old gentle- 
 man went a fecond time to Holland, and returned 
 when it was over to Aberdeen, where he died about 
 1720, aged 93, leaving behind hin^ a hiftory of his 
 •own time and countiy, which was never publiihed. 
 
 Gregory (Dr David). In addition to the ac- 
 count given in the EncyclopicJia of tills enrinent inathe- 
 matician, it may be proper to add, that he was a 
 mod intimate and confidential friend of Sir Ifaac New- 
 ton, and was intrufted with a nianufeript copy of the 
 Principia, for the purpofe of making obfervations on 
 it. Of thefe Newton availed hinifelf in the fecond 
 edition, they having come too late for his firft publica- 
 tion, which was exceedingly hurried by Dr Halley, 
 from fears that Newton's backwardnefs would not let 
 it appear at all. There is a complete copy of thefe 
 obfervations preferved in the library of the univerfity 
 of Edinburgh, prelented to it by Dr James Gregory, 
 the prefent profeflor of the pradice of medicine. Tliele 
 contain many fnblime mathematical dilcuiTions, many 
 valuable commentaries on the Pnncip'ia, and many in- 
 terefting anecdotes. There are in it fome paragraphs 
 in the handwriting of Huyghens relative to his The- 
 ory of Light, It would appear that this work of 
 confidential friendfliip was the foundation of that fyf- 
 tem of phyfical and mathematical allronomy which has 
 ralfed Dr Gregory to great eminence in the republic 
 of letters. 
 
 GRINDING, in Cutlery, a well-known operation, 
 
 ] G R I 
 
 by which edgetooh are (harpened. As commotrlv O indinif, 
 praAifed, the grinding of tools is attended witii great — v— ~^ 
 inconvcnlency, arifing from the production or develope. 
 ment of heat by fridion. The faft of fpavks flying 
 from a dry grindllone when a piece of iron or ileel is 
 applied to its furfice during the rotation, has been feen 
 by every one. Tlie heat produced duruig this procefs 
 is fuch that the fteel very foon becomes ignited, and 
 hard tools are very frequently fotteued and ipoiled, for 
 want of care during the .grinding. When a cylindri- 
 cal Itone is partly inimerfed in a trough of water, the 
 rotation muil be moderate and the work flow, other- 
 wife the water would foon he thrown off by the cen- 
 trifugal force ; and when this fluid is applied by a cock 
 from above, the quantity is too fniall to preferve the 
 requifite low temperature. It is even found, tiiat the 
 point of a hard tool, ground under a confiderable mafs 
 of water, will be foftened, if it be not held lo as to 
 meet the ftream ; fparks being frequently afforded even 
 under the water. 
 
 To find a remedy for this, Mr Nicholfon was led, 
 by fome accounts which he received of German cut- 
 lery, to make the following experiment. He procured 
 a Newcaftle grindllone of a fine grit and ten inches in 
 diatoeter, and alfo a block of mahogany to be ufed 
 with emery on its face. Both the ft:one and the wood- 
 en block were mounted on an axis, to be occafionally 
 applied between the centres of a ftrong lathe. In tin's 
 fituation both were turned truly cylindrical, a.nd of the 
 fame diameter. The face of the wood was grooved 
 obliquely in oppofite direclions, to afford a lodgement 
 for the emery. Tlie face of the (lone was left fmooth, 
 and there was a trough of proper fize applied beneath 
 the ftone to hold water. The grindflone was then 
 ufed with water, and the wooden cylinder was faced 
 with emery and oil. The inftirument ground was a 
 file, out of which it was propofed to grind all thtf 
 teeth. The rotation was produced by the mechaiiifm 
 of the lathe ; the velocity being fuch as to turn the 
 grinding apparatus about five revolutions in a fecond. 
 The (lone operated but flowly, and the water from the 
 trough was foon exhaufled, with inconvenience to the 
 workman, who could fcarccly be defended from it but 
 by flackening the vehjcity. The emery cylinder cut 
 rather fafter. But notvvithfl;anding the friction was 
 made to operate fucceflively and by quick changes on 
 the whole furface of the file, it foon became too much 
 heated to be held ivith any convenience ; and when a 
 cloth was ufed to defend the hand, the work not only 
 became awkward, but the heat increa(ed to fuch a de- 
 gree that the oil began to be decompofed, and einitted 
 an empyreumatic fmc]l. The flone was then fuffertd 
 to dry, and the file tried upon its face. , It ahnoil im- 
 mediately became blue, and foon afterwards red-hot. 
 Both the cylinders v^'ere then covered with tallow, by 
 applying the end of a candle to each while revolving, 
 and emery was fprinkled upon the cylinder of wood. 
 The fame tool was then applied to the grindllone in 
 rapid motion. At the firft^ inflant the fritlion was 
 fcaicely perceptiUe ; but very fpeedily afterwards the 
 zone of tallow preffed by the tool became fufed, and 
 the ftone cut very fall. The tool was fcarcely at all 
 heated for a long time ; and when it began to feel 
 warm, its temperature was immediately lowered by re- 
 moving
 
 G R O [7 
 
 moving It to a new zone of the cylinder. The fame 
 lifFeA took place when the experiment w.is repeated 
 with the wooden cyh'iuier. 
 
 It is Dot diiliciilt t) explain this t>y the modera doc- 
 trine of he;it. Whe!i oil was uitd upon tlie wooden 
 cvliiider, tlie heat developed by the ftiilion was em- 
 ployed ill rviilin;^ the temperature ot the tool and of the 
 fluid oil : lint when tallow was fubltituted indead of 
 the oil, the greateft part of the heat was employed in 
 fiifing this confiilent body. From the increafed capa- 
 city of the ta!lo«, when melted, this heat was abforb- 
 ed, and became latent, inftead of being employed to 
 raife the tempei'ature : and whenever, by contiuuinjj 
 the proeefs, the tallow already melted be^^an to grow 
 hot, together with the tool, it was eafy to rednce the 
 temperature again by employing the beat on another 
 zone of confillent tallow. He ufed thefe two cylinders, 
 with much fatiafaftion, in a confiderable quantity of 
 wor'n. 
 
 This promlfes to be a valuable difeovcry ; and the 
 public is obliged to the i}\genious author of the Philo- 
 fophical Journal for being at fo much pains on this, as 
 well as on other occafions, to render hiu fc^ence fubfcr- 
 vient to the ufeful arts. 
 
 GROSE (Francis, Efq; F.A.S. ) was born, we be- 
 lieve, in ty;?!. He was the fon of Mr Frawcis Grofe 
 of Riclimond, jeweller, who fdled up the coronation 
 crown of George II. and died 1769. 13y his father 
 }ie was left an independent fortune, which he was not 
 of a difpofition to add to, or even to preferve. He 
 early entered into the Surrey nu'litia, of which he be- 
 c.ime adjutant and paymaiter ; but fo much had dillipa- 
 tion taken poffedion of him, that in a fituation which 
 above all others required attention, he was fo carelefs as 
 to have for fome time (as he uled pleafantly to tell) 
 only two books of accounts, viz. his right and left 
 hand yiockcts. In the one he received, and from the 
 other paid ; and this too with a want of circumfpec- 
 tion which may be readily fuppofed from fuch a mode 
 of book-keeping. His lofes on this occafion roufed 
 his latent talents. With a good claffical education 
 he united a fine taile for drawing ; and encouraged by 
 his friends, as well as prompted by his fituation, he 
 undertook the work from wfiich he derived both pro- 
 fit and reputation ; we mean, his Views of Antiqui- 
 ties ill England and Wales, which he firll began to 
 publifh in numbers in the year 177^, and finilhcd in 
 the year 1776. The next year he added two more 
 volumes to his EnglilTi Views, in which he included 
 i!ie iflands of Guernfey and Jerfey, wliich were com- 
 pleted in 1787. This work anfwered his moft fan- 
 (,'iiine expeftations ; and, from the time he began it to 
 the end of his life, he continued without interraifiion 
 to piiblilh various works (a lift of whicli we fubjoin), 
 generally to the advantage of his literary reputation, 
 and almoll always to the benefit of his finances. His 
 wit and good humour were the abundant fource of fa- 
 (isfaflion to himfelf, and entertainment to his friends. 
 He vifited almoll every part of the kingdom, and was 
 \vell received wherever he went. In the fummer of 
 17S9 he fet out on a tonr in Scotland; tlie refult of 
 which he began to communicate to the public in 1790 
 ill numbers. Before he had concluded tin's work, he 
 proceeded to Ireland, intending to furnilli that king- 
 /iom witii views and defcriptions of her antiquities^ in 
 
 Soppi. Vol. I. Part II. 
 
 21 J G R O 
 
 the fame manner h; had executed tliofe o-f Great Bri- 
 tain ; but foon after his arrival in Dobliii, being at the " 
 boufe of Mr Home there, he fudilcnly was feized at 
 table with an apoplectic fit, on the 6th May 1791, 
 and died immediately. He was interred in Dublin. 
 
 '• Jlis literary hiltory (fays a friend), relpedtable a.; 
 it is, was exceeded by his good humour, conviviality, 
 and friendihip. Living much abroad, and in the be'.l 
 company at home, he had the eaficll habits of adapt- 
 ing himleli' to all tempers; and, being a man of gene- 
 ral knowledge, perpetually drew out fome converfatioii 
 that was either ufetul to himfelf or agreeable to the 
 party. He could obferve upon moll things with prc- 
 cifion and judgment ; but his natural tendency was to 
 humour, in which he excelled both by the fcieftion of 
 anecdotes and his nnnner of telling them : it may be 
 faiil, too, that his figure rather alliilcd him, which wai 
 in facl the very title-page to a joke. He had neither 
 the pride nor malignity of authorfhlp : he filt the in. 
 dependency of his own talents, a.id rtus fa;isfied witli 
 them, without d.;grading otiiers. His friendfliips were 
 of the fame ca.l ; conilant and fincere, overlooking 
 fome faults, and feeking out greater virtues. He had 
 a good beart ; and, ab.iting tliofe little indifcretions na- 
 tural to moil men, could do no wrong." 
 
 He married at Canterbury, and refided there fome 
 years, much beloved and refpedled for his wit and vi- 
 vacity ; " which (another friend obferves), thougii 
 he poficfled in an extreir.e degree, was but little tinc- 
 tured with the caullic Ipirit io prevalent among ipiriis 
 of that clafs. His humour was of that nature which 
 exhilarates and enlivens, without leaving beliind it a 
 lling ; and tbougl. perhaps none poflelTed more than 
 himlelf the faculty of " ietting the table in a roar," it 
 was never at the expenc-:: of virtue or good manners. 
 Of him indeed may be faij in the words of Sha.ke- 
 fpeare. 
 
 Cri>rc. 
 
 a nieruer man. 
 
 Within the limits of ijecoraing mirth, 
 I never fpent an hour's talk withal : 
 His ey<; begets occaGon for his wit ; 
 And every objcCl that the one doth catcii, 
 Tlie other turns to a mirth-moving jeft. 
 
 " Of the moft carelefs, open, and artlefs difpofition. 
 he was otten (particularly in the early part of his life) 
 the prey of the deligning ; and has more than once (it 
 is believed) cmbarralTed himfelf by too implicit confi- 
 dence in the probity of others. A tale of dillrefs never 
 failed to draw commiferatioii from his heart ; and often 
 has the tear been dilcovered gliding down that cheek 
 which a moment before was flullied with jocularity." 
 
 He was father of Daniel Grofe, Efq; captain of the 
 royal regiment of artillery (who, after fcveral cam- 
 paigns in America, was appointed in 1 790 deputy go- 
 vernor of the new fettlemcnt at Botany Bay), and fome 
 other children. 
 
 His works are as follow : 
 
 1. The Antiquities of England and Wales, 8 vol.",. 
 4to and Svo. 2. The Antiquities of Scotlnnd, 2 
 vols. 4to and 8vo. 3. The Antiquities of Ireland, i 
 vols. 4to and 8vo, 4. A Treatile on sncicnt Armour 
 and Weapons, 410, 1785. 5. A Clafiical DiAionaiy 
 of tlie Vulgar Tongue, 8vo, 1785. 6. Military An- 
 tiquities ; being a Hiftt^ry of the Eng'.ifli Army frotn 
 4 Y tht
 
 G U I 
 
 [ 722 ] 
 
 GUN 
 
 ■Plate 
 XX IX. 
 
 Giierite, the Conqiieft to the prefent time, 2 vols 410, 1786, 
 Guillotine, j^gg, ^_ The Hiftory of Dover Caillc, by the Rev. 
 ' AVilh'am Datitll, 410, I7K6. 8. A Provincial Glof- 
 
 fary, with a CoUeftion of local Proverbs and popular 
 Superftitions, 8vo, 1788. g- Rules for drawing Ca- 
 ricatures, 8vo, 1788. ic. Supplement to the Trcatife 
 on Ancient Armcur and Weapons, 4to, 1789. II. 
 A Guide to Health, Beauty, Honour, and Riches ; 
 being a coUedlion of humorous Advcrtifements, point- 
 ing out the Means to obtain thofe bkffiiigs ; with a 
 fuitable introduftory Preface, 8vo. 12. The Olio ; be- 
 ing a Colleftion of EfTays in 8vo, 179^- 
 
 GUERITE, in Fortification, a centry-box ; being 
 a fniall tower of wood, or ftone, ufually placed on the 
 point of a baftion, or on the ant;les of the fn.'ulder, to 
 hold a centinel, who is to take care of the ditch, and 
 watch againfl: a furprife. 
 
 GUILLOTINE, a new term introduced into the 
 languages of Europe by the mourr.ful effefts of fa;iati- 
 cilm in the holy caufe of liberty. Our readers are not 
 ignorant that this is the name given by the National 
 Afftmbly of France to the engine of decapitation, which 
 thofe ufurpers of the legiflative authority decreed to be 
 the fole puni(hment of thofe condemned to death for 
 their crimes. This decree was ilTucd on March 20th 
 
 We do not imagine that the viorld will derire much 
 ufeful inftrufllon from a minute dcfcription of this ter- 
 rible inftrument of public juftice; and therefore con- 
 tent ourfelves with giving two figures of it, fufiiciently 
 expreffive of its conftruftion. It is only the revival of 
 an inftrument ufed in former times. The earlieft ac- 
 counts that we have of it is, that it was ufed in the ba- 
 rony of Halyfax in Yorkihire. It was alfo fet up in 
 Scotland; but we have no certain information that it iias 
 ever been ufed ; and it ie ftili lliewn as a fort of curiofity 
 hy the name of the Mayden. See Maiden^ Evcycl. 
 
 Eratofthenes could not think of abetter way of hand- 
 ing down his name to future ages than by burning the 
 temple of Diana at Ephefus ; Dr Guillotin, phyiician 
 at Lyons, and member of the felf-named National Af- 
 fembly of France, thought himfclf honoured by the de- 
 cree which alFociated- his name with this inftrument of 
 popular vengeance. It was indeed propofed by him 
 as an inftrument of mercy, in a ftudied harangue, filled 
 with that fentimental ftang of philanthropy, which 
 cofts fo little, promifss fo much, and has now corrupt- 
 ed all the languages of Europe. His invention is in- 
 deed one of the moft expenfive fpecimensof Gallic phi- 
 lanthropy, whofe tender mercies are cruel ; and was ac- 
 cordingly received with loud applanfes, both from the 
 houfe and from the galleries. To proceed, however, 
 with impofing dignity, it was referred to the confidera- 
 tion of a committee, with injunflions to afit the opinion 
 of able furgeon", of its efficiency. Mr Louis, a celebra- 
 ted furgeon of Paris, declared it well fitted for the talli, in 
 a long pedantic diffcrtation ; in which he takes occniion 
 to deliver, with academic coldnefs, a theory of the ojie- 
 ratlon of cutting inftruments; and fays that he had 
 examined the edge of the guillotine, and other fuch 
 inftruments, with a microfcope, and had difcovered 
 that the fineft edges were toothed like a faw. M. Guil- 
 lotin, he faid, had therefore with great judgment made 
 t!ie axe of his engine of death with a (loping edge, by 
 which means il glijpiit d'une fagon itifimlmint plus douce. 
 
 This diftertation was fo much to the tafte of the hu. 
 mane legtflature, that they rew?rded Mr Louis with 
 2000 livres, and publiilKd it in the Paris Journ?ls. As 
 to the inventor, he reaped all the benefit from it which i. 
 he fo kindly intended for the n:itIon, by the trial of it 
 on his own perfon, when he fell under the difpleafure 
 of Robefpierre. 
 
 We acknowledge, that in as far as this inftrument 
 lefTens the duration of the horrid conflift with the king 
 of terrors, and probably diminiflies the corporeal fuffer- 
 ance, it may be called merciful (alas ! the day!) ; but 
 we queftion much, whether the dreadful agitation of foul 
 is not rather increafcd by the long train of preparatory 
 operations. The hands of the convidl are tied i)ehind 
 his back : he is then ftretched ;dong on his face on a 
 ftrong filank, and his precife pofition adjufted to the in- 
 ftrument. When faftened to the plank, it is pudied 
 forward into its place under tl c fatal edge, his neck ad- 
 jufted to the block, and a bafl^et placed juft before his 
 eyes (for the face of Louis XVI. was not covered) to 
 receive his head. This muft employ a good deal of 
 time, and every moment is terrible. 
 
 The conftrudlion has received many alterations and 
 refinements ; and has at laft been made fo compendious 
 and portable, as to become part of the travelling equi- 
 page of a commiflioner from the National Affembly, 
 fent on a provincial or fpecial vifitation. Thus did the 
 fovereign people become terrible in majefty. So fen- 
 fible was the affembly of the advantages of this awful 
 impreflfion, or fo intoxicated with the enjoyment of ine- 
 fiftible power, that they have thought their coins orna- 
 mented by this attribute of their fupremacy : and as 
 Jupiter is diftinguiihed by his thunderbolt, fo the ma- 
 jefty of the people is diftingulihcd by the no Icfs fatal 
 axe. We have feen a piece often fous, ftruck at Mcntz 
 in 1793, and iffued as current money, at the very time 
 that they were planting the tree of liberty in that ilhi- 
 minated city by the hands of Cuftine and his troops. 
 The device is the fafces and axe of ancient Rome» 
 crowned with a red cap, and furrounded by a laurel 
 wreath. The infcription is, Refublique Frangotfe, I793t 
 an. 2d. Fully imprefTed with the fame fentimentSj 
 Lequinio, the fentimental novellift of France, whom 
 Mercier compares with the tender, the heart- touching 
 Sterne — Lequinio, now commiflionc"j,fent by the Na- 
 tional Afl'embly to regenerate Normandy and Brittany, 
 writes to his ma.fters, that " he is very fuccefsful in con- 
 verfions from fuperftition to found reafon." He oppofes 
 to the Bible and the relifls of the faints the conftitu- 
 tion and the guillotine. " And you would wonder (fays 
 he) at my fuccefs — The wife (but they are few) give 
 up their prejudices at once : but the multitude, tiie ftu- 
 pid worftiippers of Notre Dame, look at our lady the 
 guillotine; are filent, becomes ferious, and their doubts 
 vanidi ; — they are converted. This is your lalarum-r- 
 in hoc Jigno •uinces." 
 
 GULA, GuEOLE, or GoLA, in Architefture, a 
 wavy member whofe contour relembles the letter S, 
 commonly called an Ogee. 
 
 GUNPOWDER, as. we have obferved in the Ency- 
 clopicdia under the word Gu.s, has been known in the 
 eail, and particularly in China, from a period of very 
 remote antiquity. No man, however, feeras to bav8 
 fufpefted that the knowledge of it was conveyed from 
 th* eail. into Europe ; but all have agreed to allow the 
 
 merits
 
 GUN 
 
 [ 723 ] 
 
 GUN 
 
 der. 
 
 * Tranfic- 
 tions of the 
 Hoy a I Trijh 
 Academy, 
 
 * 
 
 merits of tlie invention both to friar Bacon and to 
 Bartholomew Scluvartz. This generally received opi- 
 nion has been lately controverted by citizen I,:iiiglcs, 
 who, ill a memoir read in the French national iniUtute, 
 contends, that the knowledge of gunpowder was con- 
 veyed to lis from the Arabs, on the return of the Cru- 
 faders to Europe. He affures us that the Arabs made 
 ufe of it in 690 iit the fiege of Mecca ; and he adds, 
 that they derived it from the Indians, among whom 
 it mull hive been known in the remotcll ages, fnice 
 their facred books (the Vcdam) forbid the uie of it in 
 war. 
 
 It is indeed extremely probable, that the compofi- 
 tion of gunpowder vva;. known in India at a very early 
 period; for in whatever country nature forms nitre in 
 the greateil plenty, there its dellngrating quality is 
 moll likelv to be firll obfervcd ; and a few experiments 
 founded on that obfervation, will lead to tlie compofi- 
 tion which produces fucli fudden and violent cffcdls. 
 *' Nitre (fays Sir George Staunton) is the natural 
 and daily produce of China and India; and there accor- 
 dingly the knowledge of gunpovv'der feems to be co- 
 eval with that of the moll diilant hilloric events. A- 
 mong the Chinefe, it has been applied at all times to 
 uleful purpofes ; fueh as blaftmg rocks, and removing 
 great obllruCiions, aud to thofe of amufemcnt in ma- 
 king a vail variety of tire-works. It was alfo ufed as 
 a defence by undermining the probable paffage of the 
 enemy, and blowing him up. But its force had not 
 been direfled through llrong metallic tubes as it was 
 by Europtans foon after they had difcovered it. And 
 though, in imitation of Europe, it has been introduced 
 into the armies of the Ea(l, other modes of warfare are 
 fomttimes dill preferred to it." ' 
 
 Of gunpowder manufaftured by thofe who have 
 manufadured it fo long, it is defirable to know the 
 compofition and the qualities. It was therefore na- 
 tural for the Hon. George Napier, when fuperintend- 
 ing the royal laboratory at Woolwich, and making ex- 
 periments upon fo neceffary an implement of modern 
 war, to procure fome Chinefe powder from Canton. 
 
 This he did ; and analyzing two ounces of it, he 
 found, after repeating the operation fix times, that the 
 mean refult gave the following proportions *. Nitre 
 I oz. 10 dwts. charcoal 6 dwts. fulphur 3 dwts. 14 
 grs. Here is a deficiency in weight of ten grains, 
 which M. Napier fuppofes the confequence of fome de- 
 fe£l in his procefs ; but as M. Baume, a French che- 
 miil, made a variety of experiments to obtain a total fe- 
 paration of the fulphur from the charcoal of gunpovs'- 
 der, and was never able to effeft it, one fourteenth part 
 remaining united, three grains inuft be dedufted from the 
 charcoal and added to the fulphur to give the accu- 
 rate proportion of the ingredients; which by turning to 
 the article Gunpowder, Encycl. the reader will per- 
 ceive differs fomewhat from the proportion of the fame 
 ingredients in the gunpowder of Europe. This Chi- 
 nefe powder was ufually large-grained, and not ftrong, 
 but very durable. It had been made many years when 
 our author got it ; yet there was no vifible fymptom of 
 decay, the grain being hard, well coloured, and though 
 angular, it was even-fized, and in perfeft prefervation. 
 
 When we confider the operations in which gunpow- 
 der is employed, it is obvious that it mud be an objeft 
 of importance to afcertain its explofive force ; and yet 
 
 there is fcarccly a fubjeft concerning which the moft Gnnpov.' 
 ajiprovcd writers have fo much differed. Mr Robins, '^"' 
 who lias done more towards perfefting the art of gun- ' 
 nery than any other individual, Hates tiie explofive foice 
 oi gunpowder to be 1000 times greater than the mean 
 preffure of the atinofphere; while tlie celebrated Daniel 
 Barnouilli determines it to be not lefs than 10,000 times 
 this piclTure. Such a didereiice of opinion led Count 
 Rumtord to purfue a courfc of experiments, of which 
 fome were publiilied in the Tranladtions of the Royal 
 Society for the year 1781, and the remainder in the 
 Tranfailions of the fame Society for I 797; with the 
 view principally of determining the initial expanfive 
 force of gunpowder. By one of thefe experiments, it 
 appeared, that calculating even on Mr Robins's own 
 principles, the force of gunpowder, initead of being 
 1000 times, mull at leaft be 1308 times greater than 
 the mean pred'ure of the atmofphcre. From this ex- 
 periment, the Count thought himfelf warianted in con- 
 cluding that the principles affumed by Mr Robins were 
 erroneous, and that his mode of afcertaiiiing the force 
 of gunpowder Qould never fatisfadorily dttermine it. 
 Defpairing of fuccefs in that way, he refolved to make 
 an attempt for afcertaining this force by adlual niea- 
 furement ; and after many uiifuccefsful experiments, he 
 was at length led to conclude, that this force was at 
 leaft yo,ooo times greater than the mean prefuire of the 
 atmofpiiire. 
 
 Mr Robins apprehends that the force of fired gun- 
 powder confifts in the aftion of a permanently elaliic 
 fluid, fimilar in many refpefts to common atmofpheri- 
 cal air ; and this opinion has been very generally re- 
 ceived : but Count Rumford thinks, that though the 
 permanently elaftic fluids, generated in the coinbulUou 
 of gunpowder, aflift in producing the eficfts which re- 
 fult from its explofion, its enormous force, allowing it 
 to be 50,00: times greater than the mean preflure of 
 the almofphere, cannot be explained, without fuppofing 
 that it arifes principally from the elafticity of the a- 
 queous vapour generated from the powder in its com- 
 buftion. 
 
 " The brilliant difcoveries of modern chemids (fays 
 he) have taught us, that both the conflituent parts of 
 which water is compofed, and e\en water itfelf, cxllt In 
 the materials which are combined to make g-unpowder ; 
 and there is much reafon to believe that water is ac- 
 tually formed, as well as difengaged, in its combuftion. 
 M. Lavoifier, I know, imagined that the force of fired 
 gunpowder depends in a great ineafure upon the ex- 
 panfive force of uncombined caloric, fupjiofed to be let 
 loofe in great abundance during the combullion or de- 
 flagration of the powder: but it is not only dangerous 
 to admit the aftion of an agent whofe exillence is not 
 yet clearly demonftrated ; but it appears to me that 
 this fuppofition is quite unneceffary, the elailic force 
 of the heated aqueous vapour, whofe exillence can 
 hardly be doubted, being quite fufficient to account for 
 all the phenomena. It is well kn(!wn that the elafti- 
 city of aqueous vapour is incomparably more augment- 
 ed by any given augmentation of temperature tlun that 
 of any permanently elailic fluid whatever ; and thofe 
 who are acquainted with the amazing force of fteam, 
 when heated only to a few degrees above the boiling 
 point, can eafily perceive that its elafticity muft be al. 
 moft infinite when greatly condenied and heated to the 
 4 Y 2 temperature
 
 dcr. 
 
 G U N [ -: 
 
 Gunpow- temperntiirf of red-Iuit iron ; and this heat it mmt cer- 
 tainly acquiif in the txpli)fiiiii of gunpowder. But if 
 the force of fired giw'.povvdcr ■ariins frincij>n//y from the 
 I'laftic force of heated a<7Ufcus vapour, a cannon is no- 
 thing riiore thin a ■JItainvuglne upon a peculiar coii- 
 Jlruttion ; and upon detenniniiig the ratio of the elaf- 
 tlcity of this vapour rt) its deuiity, and to Its tempera- 
 ture, a law will be found to obtain very different from 
 that afTumed by Mr Robins in his Treatife on Gun- 
 nery." 
 
 In order to meaTin-e the elaftlc force of fired gu?i- 
 powder, Count Rumford adopted a new plan ; and, in- 
 ftead of caufingj the generated elallic fluid to aft on a 
 moveable body through a determined fpace, which he 
 ])ad found to be inefFeftual to bis purpofe, he contrived 
 an apparatus in which this fluid fnoi.ld be made to art, 
 " by a determined furface, agriinft n weigbt, vvhieli, by 
 being increaled at pleafure, fliould at iait be fucl\ as 
 would jufl be able to confine it, and which in th:it cafe 
 would jidl counterbalance and conftquently iinr.fure the 
 elafb'c force." 
 
 Having fucceeded in fetting fire to the powder, 
 without any communication with the external air, " by 
 cauling the heat employed for that purpofe to pals 
 through the folid fob Ranee of the barrel, it only re- 
 mained to apply fuch a weight to an opening made in 
 the barrel, as the whole force of the generated elailic 
 fluid fhould not be able to lift, or difplace." Many 
 j)r€cautions werj? necrlfary. A folivd block of very hard 
 Itone, Four feet four inches fquare, was placed upon a 
 bed of folid mafonry, whicli defcended fjx feet belo«r 
 the furface of the earth. Upon this block of ftone, 
 which ferved as a bafe to the whole machinery, was 
 placed the fmall barrel, in which the explofions were 
 made, with its opening direftly upwards, This open- 
 ing was clofed by a folid hemiiphere of hardened Ifeel, 
 on which th-. weight to be overcome by the expk.llon 
 was laid. Having charged the barrel with lo grains 
 of powder, its whole contents being about 28 grains, 
 and a 24 pounder, weighing 808 i lbs. avoirdupois, be- 
 ing placed on its cafcabel fo as by its weight to con- 
 fine the generated elaflic flu'd, a heated iron ball was 
 applied to the end of the vent tube (a fmall folid pro- 
 jection from the centre of the bottom of the barrel). 
 In a few moments the powder took lire, though the 
 cxplolijn made a very feeble report ; and when the 
 weight was railed, the confined elallic vapour rudied 
 out of the barrel. The flight t fl'ecl produced by tliis 
 explolion induced fume of the attendants on this occa- 
 fion to undervalue the importance of this experiment, 
 and to form a very inadequate idea of the real force of 
 the elaftic fluid that had been thus almofl infenfibly 
 idifcharged. In a fecond experiment, the barrel was 
 filled with powder, and the fame weight laid on as be- 
 fore. The barrel was made of the bell hammered iron, 
 and uncommonly flrong. The charge of powder a- 
 mounted to little mure than Vo''' °^ s cubic inch, wllich 
 is not fo much as would be required to load a Imall 
 pocket-piftol, and rot onttcnth part of the quantity fre- 
 quently ufed for tlie charge of a common mulket. Yet 
 this inconfidtrable quantity of powder, when fet on fire, 
 exploded with a force that burll the barrel, and witii a 
 loud report that alarmed the whole neighbourhood. 
 
 The author proceeds to make an eflimate, from the 
 known flrength of iron, and the area of the frailure of 
 
 4 ] GUN 
 
 the barrtl in the preceding experiment, of the real force Gurpow- 
 employed t>y the elallic vapour to bnrft it ; and he com- ^"■ 
 putes that it muil have been tquvii to the preffurc of a •""" 
 weight of 41 2529108.; whici), by another computation, 
 he found to be 51004 limes greater tliau the mean 
 preffure of the atmofpliere. By another procefs, he in- 
 vefligates the llrengtii of the iron of which the barnl 
 was made ; and he thence finds that the force required 
 to burft it was equal to the preffure of a weight of 
 4Io624t1''s. Tills weight, reduced into atmofpheres, 
 gives 54750 atmofpheres for tlie raeafure of the force 
 exerted by the elafiic fluid in the prefent inflance. This 
 force mufl be conliderably lefs than the initial force of 
 tiie elaflic fluid ir.'uerated in the combulliou of gun- 
 powder, before it hds begun to expand; " for it is more 
 than proii.ible (fays Count Rumford) that tiie barrel 
 was in fart burfl before the generated elaflic fluid had 
 cKerted all its force, or that this fluid would have been 
 able to have burfl a barrel Riil flvonger than that ul'ed 
 ill the experiment." 
 
 After having fliewn the extreme force of fired gun- 
 powder, the Count adverts to an objcrtion which may 
 be made againil his deduftions. How dots it happen 
 that fire-arms and artillery of all kinds, which certainly 
 a;e not calculated to wltiiffand fo enormous a force, are 
 not always burff when they are ufed .' Inflead of an- 
 fwering this quellion, by afliing how it happened that 
 the extremely llrong baiiel ufed in his expeiiment could 
 be buift by the force of gunpowder, if this force be not 
 in fart much greater than it has ever been fuppoied ti> 
 be, he proceeds to fhew that the combulliou of gun- 
 powder, inltead of being inflantaneous, as Mr Robins's 
 theory fnppofes, is much lefs rapid than has hitherto 
 been apprehended ; an obfervation which, if cllabliflied, 
 is certainly fufficient to anfwer the objcrtion. 
 
 He remarks, that it is a well-known fadt that, on the 
 difeb.)rge of fire-arms of all kinds, there is always a 
 coiiliderablc quantity of unconfumed grains of gunpow- 
 der blown out of them; and what is very remarkable, as 
 it leads dirertly to a difcovery of the caufe of this effert, 
 thefe unconfumed grains are not merely blown out of the 
 muzzles of fire-arms, but come out alfo by their vents or 
 touch-holes, wiiere the fire enters to inflame the charge, 
 as many peifons who have had the misfoitune to fland 
 with their faces near the touch-hole ot a mufket, when 
 it has been difciiarged, have found to their coil. 
 
 It appears extremely improbable to our author, i£ 
 not ablolutely impoffible, that a grain of gunpowder ac- 
 tually in the chamber of the piece, and completely fur- 
 rounded by flame, fhould, by the action of that very 
 flame, be blown out of it witiiout being at the fame 
 time fet on fire. And, if this be true, he confiders it 
 as a moll decifive proof, not only that the combuflion- 
 of gunpowder is lefs rapid than it has generally been 
 thought to be, but that a grain of gunpowder adually 
 on fire, and burning with the utmoll violence over the 
 whole of its furface, may be projefted with luch a velo- 
 city into a C(ild atmofpbcje, as to extinguifli the fire,, and' 
 fufter the remains of the grain to fall to th*; ground un»- 
 changed, and as inflammable as before. 
 
 Tliis extraordinary fart was afcertained beyond all 
 poffibility of doubt by the Count's experiments. Ha- 
 ving procured from a powdermill in the neighbourhood: 
 of the city of Munich a quantity of gunpowder, all of 
 tlie fame mafsj but formed into grains of very different 
 
 li/es,
 
 GUN [7 
 
 euTOW. fues, fo'Tie as fmnll as the grains of the fined Battel 
 der.' powder, he placed a number of vertical fcreers of very 
 ^"~^' tiiin p:i[icr, one behind another, at the dilhiiice of 1 2 
 inches fri)m eachotlier; and loading a comiiKin inulket 
 npeatedly with this ])Owrier, fometimes without and 
 fi/meliints v.ith a %vad, he tired it againfl the f>)reinoil 
 I'oricn, and obferved t}ie quantity and eflefts of the un- 
 i:onfumed graii.s of powder which impinged againlt it. 
 Tlie fcreens were lo contrived, by means of double 
 frames united by hinges, that the paper could be chan- 
 jred with very little trouble, and it was actually chan- 
 ged after every experiment. 
 
 The diftance from the muzzle of the gun to the firft 
 fereen was not always the fame ; in fome of the expe- 
 riments it was only 8 feet, in others it was lo, and in 
 iome I 2 feet. 
 
 The charge of powder was varied in a great number 
 fVf different ways; but the moR intevelting experiments 
 were made with one fiugte large grain of powder, pro- 
 ptlled by fmallcr and larger charges of very fine grain- 
 ed powder. 
 
 Thefe large grains never failed to reach the forcen ; 
 and though they fometimes appeared to have been bro- 
 ken into feveral pieces by the force of the explofion, 
 yet they frequently reached the fereen entire ; and 
 fometimes pafted through all the fcreens (five in num- 
 ber) without being broken. 
 
 When they were propelled by large charges, and 
 confequently with great velocity, they were feldum on 
 iire when they arrived at the tirft. fereen"; which was 
 evident, not only from their not fetting fire to the pa- 
 per (which they fometimes did), but alfo fnnn their 
 being found (licking in a loft board, againft whicli t!iey 
 flrnck, after having paffed through all the five fcreens ; 
 or leaving vifible marks of their having been impinged 
 againit it, and being broken to pieces and difperled by 
 the blow. Thefe pieces were often found lying on the 
 ground ; and from their forms and dimenfions, as well 
 as from other appearances, it was often quite evident 
 that the little globe of powder had been on fire, and 
 that its diameter had been diminilhed by the conibuf- 
 tion before the fire was put out, on the globe being 
 prcjefted into the cold atmofphere. 
 
 Th.1t thefe globes or large grains of powder were al- 
 ways fet on fire bv the combultion of tlie charge, can 
 hardly be doubted. Tin's certainly happened in many 
 of the experiments; for they arrived at the ("creens on 
 fire^ and fet lire to the paper ; and in the experiments 
 in which they were projefted with fiiiall velocities, 
 they were often feen to pafs through the air on tire ; 
 and when this was the cafe, no ve.lige was to be 
 found. They fometimes paffed on fire through feve- 
 ral of the foremoft fcreens without fetting them on lire, 
 and fet fire to one or more of the hindmolt, and then 
 nvcnt on and impinged againll the board which was 
 placed at the diftance of twelve inches behind the laft 
 fereen. 
 
 The Count then proceeds to mention another expe- 
 riment, in which the progreffive combullion of gun- 
 powder was fhewn in a manner ilill more flriking, and 
 not lefs conckifive. 
 
 A fmall piece of red hot iron being dropped down 
 into the chambei- of a common horfe pillol, and the 
 piftol being elevated to an angle of about 4; degrees, 
 upon dropping down into its barrel one of the fmaU 
 
 25 ] GUN 
 
 globes of powder (of the fize of a pea), it took fire, and Oanpov*. 
 was projedfed into the atmofphere by the clallic fluid ^ ^ "' . 
 generated in its own combullion, leaving a very lieauti- ' 
 
 ful train of light behind it, and difappcaring all at once 
 like a falling liar. 'I'his amuling ex['ri irr-eiit v.-as re- 
 peated very often, and with globes of drffcrciit lizes. 
 When very fmall ones were ufcd fmgiv, tiiey were com- 
 monly confiimed entirely before thev came out of the 
 barrel of the pillol ; but when feveral of them were 
 tiled together, fome, if not all of -them, were common- 
 ly projedled into the atmoiyjherc on tire. 
 
 As the (lownefs of the combullion of gunpowder is 
 undoubtedly the caufe which has prevented its enor- 
 mous and almoll incredible force from being difcover- 
 ed, our author deduces, as an evident confequcuce, that 
 the readi,*ft way to increale its e.^Tefts, isi to contrive 
 matters fo as to accelerate its inflammation and com- 
 buftion. This may be done in various ways ; but, in 
 his opinion, the moil limpje and moll effetlual manner 
 of doing it would be to let tire to the charge of pow- 
 , <ler, by fhooting (through a fmall opening) the flame 
 ot n fmalier charge into the midll of it. 
 
 He contrived an inllruinent on this principle for 
 firing cannon three or four years ago; and it was found, 
 on repeated trials, to be iifeful, convenient in pradtice, 
 and not liable to accidents. It likewife fiipericdes the 
 neceffity of ufing jiriming, of vent tubes, port-fires, and 
 matches ; and uii that account lie imagined it might be 
 (if ule in the Britiih navy, but it does not appear to 
 have been received into pratlice. 
 
 Another infallible method of increafing. verv confi- * 
 derably the elTeft of gunpowder in fire-arms of all I'oris 
 and dimenlions, would be to caufe the bullet to fit the 
 bore exaflly, or without windage, in that part of the 
 bore at leall where the bullet rells on the charge ; for 
 when the bullet does not completely clofe the opening 
 of the chamber, not ouly much of the elaflic fluid, ge- 
 nerated in the firft moment of the copibuftion of the 
 charge, efcapes by the tide of the bullet ; but what is 
 of Hill greater impm-tance, a coufiderablc part of the 
 unconfumed powder is blown out of the chamber along 
 with it in a llate of aftual combnilron, and, getting be- 
 fore the bullet, continues to burn on as it palTes through 
 the whole length of the borej by which the motion cf 
 the bullet is mtich impeded. 
 
 The lofs of force which arifes from this caufe, is in 
 fome cafes almolt incredible; and it is by no means dif- 
 ficult to contrive matters fo as to render it very appa- 
 rent, and alfo to prevent it. 
 
 If a common hovie-pillol be fired with a loofe baU, 
 and fo fmall a charge of powder that the ball fliall not 
 be' able lo penetrate a deal board fo deep as to Hick in, 
 it when fired againll it from tlie diftance of fi.x feet ; 
 the fame ball, difcharged from the iame piftol with the 
 fame charge of powder,, may be made to pafs quiie 
 through one deal board, and bury itfelf in a fecond 
 placed behind il, merely by preventing the lofs of force 
 which ariics from wliat is called windage, as he found 
 more than once by adual experiment. 
 
 The Count has in his poffeflion 3 muil<et, from 
 which, with a common charge of powder, he liros two 
 bullets at once with the fair.e velocity that a fin"-!e bul- 
 let is difeharj^ed from a muiket on the common con- 
 ftruftion with the fame quantity of powder. And,, 
 what renders the experiment ttill more llriking, the 
 
 dimieicp.
 
 ■ler. 
 
 GUN [7 
 
 di'amfter of the bore of his mud^ct i.'! exa<i^!y the fame 
 as that of a common mullcet, cKctpt only in that part 
 of It where it joins the chamber, in which part it is 
 juft io much contraded, that the bullet, which is next 
 to the powder, may llick fall in it. He adds, that 
 though the bullets are of the common fize, and arc con- 
 fequcntly coDfidcrably lefs in diameter than the bore, 
 means are ufed which cifeftually prevent the lofs of 
 force by windage; and to this laft ci.cumftance he 
 concludes, it is doubtlefs owing, in a great meafure, 
 that the charge' appears to exeit fo great a force in 
 propelling the bullets. 
 
 That the conical form of the lower part of the bore 
 where it unites with the chamber has a confiderable 
 (hare in producing this extraordinary effeft, is, how- 
 ever, very certain, as he has found by experiments made 
 with a view merely to afcertain that fa<tl. 
 
 At the clofe of the Count's laft memoir, we have a 
 computation, defigned to (hew that the force of the e- 
 laftic fluid generated in the combuftion of gunpowder, 
 enormous as it is, may be fatisfaftorily explained on the 
 fuppolition that it depends folcly on the elafticity of 
 watery vapour, or fteam. Fronri experiments made in 
 France in the year 1790, it appears that the elailicity 
 of (learn is doubled by every addition of temperature 
 equal to 30° of Fahrenheit's thermotreter. As the 
 heat generated in the combuftion of gunpowder can- 
 not be lefs than that of redhol iron, it may be fup- 
 pofed equal to looo*^ of Fahrenheit's fcaie : — but the 
 elallic force of iteam is juil equal to the mean prelTure 
 of the atmofphere, when its temperature is equal to 
 that of boiling water, or to 212° of Fahrenheit's ther- 
 mometer ; confequently 2 1 2^+ 30'' = 240'^ '."."ill repre- 
 fent the temperature, when its elailicity will be equal 
 'to the prefliire of two atmofpheres ; and, purluing the 
 calculation, at 602", or 2° above the heat of boiling 
 linfeed oil, its elafticity will be equal to the preffure of 
 8192 atmofpheres, or above eight times greater than 
 the utmoft force of the fluid generated in the combuf- 
 tion of gunpowder, according to Mr Rohins's compu- 
 tation : but the heat in this cafe is much greater than 
 that of 602° of Fahrenheit ; and therefore the elafticity 
 of the fteam generated from the water contained in the 
 powder muft be much greater than the preffure of 8192 
 atmofpheres. At 722^ the elafticity will be equal to 
 the prelTure of 13 !, 072 atmofpheres ; and this tempe- 
 rature is lefs than the heat of iron, which is vilibly red- 
 hot in day-light, by 3C5°:— but the flame of gunpow- 
 der has been found to melt brafs, which requires a heat 
 equal to that of 3807'-' of Fahrenheit ; 2730'' above 
 the heat of red hot iron, or 3S05' higher than the tem- 
 perature which gives to fteam an elailicity equal to the 
 prelTure of 1^1,072 atmofpheres. That there is in 
 gunpowder water fifficient for iupplying the neccifary 
 quantity of fteam, the author has very fatisfaclorily e- 
 vinced ; but we muft not pin-fue his curious inveftiga- 
 tions any farther. Thofe who want a fuller account 
 of them, will find it either in the original men)oirs 
 themfelves, or in a very accurate abridgment of thcfe 
 memoirs in the firll volume of NichoHou's Journal of 
 Natural Philojophy, &c. 
 
 We cannot conclude this article without mentioning 
 a new kind of gunpowder, invented fome years ago in 
 France, in which the marine acid is fubftituted, in 
 equal quantity, for nitre. Dr Hutton tried fome of 
 
 26 ] GUT 
 
 this new powder which «as made at Woolwich, and 
 found it of about double the ftrengtli of the ordinary 
 fort ; but it is not likely to come into common and ge- 
 
 neral ule, for the pieparation of the acid is diflicult and 
 expenlive (See C-HtMisTRY-Zn/i-A- in this Su/pL), and 
 the pov.der which is made of it catches fne- and ex- 
 plodes from the fmalleft degree of heat, and without 
 the aid of a fpark. It is to this circuniftance, how. 
 ever, that its fuperior ftrength fcems to be in a great 
 meafure owing. 
 
 GUNTER's Chain. See Geometry, £iuyt/o/>a- 
 dia. Part II. chap. I. 
 
 CUT-TIE, a dangerous difeafe to which oxen and 
 male calves are rendered liable by an improper mode of 
 caftration. In lome places, and particularly in liere- 
 fordihire, the breeders ot cattle, when they cailraie 
 their calves, open the fcro/wiii, take hold of the tefticlcs 
 with their teeth, and tear them out with violence ; by 
 which means all the vcifels thereto belonging are rup- 
 tured. The To/j (Icferentia, entering by the holes of 
 the tranfverfe and oblique mufcles into the abdomen, 
 pafs over the ureters in acute angles; at which turning, 
 by their great length and claftic force, the peritoneum 
 is ruptured ; th» 'vqj'a dtfereutia are fevered from the 
 tefticles, and, fpringing back, form a kind of bow from 
 the urethra, where they are united, over the ureters, to 
 the tranfverfe and oblique mufcles, and there again unite, 
 where they firft entered the abdomen ; the part of the 
 gut that is tied is the jejunum, at its turning from 
 the left fide to the right, and again from the righ.t to 
 the left, forming right angles under the kidney, and at. 
 tached to the dnplicature of the peritoneum, to which 
 it was united, where the rupture happened. There the 
 bow of the gut hangs over the bow of the vafa deft- 
 rentia, which, by a fudden motion, or turn of the beait, 
 form a hitch or tie of the ftring round the bow of the 
 gut (filled with air), fimilar to what a carter makes en 
 his cart line. This caufes a ftoppage in the bowels, 
 and brings on a mortification, which, in two days, or 
 four at moft, proves fatal : And to this accident is the 
 beaft, when caftrated as above, liable from the day that 
 he was caftrated till the time of his being (laughtcred. 
 
 The fymptoms of the gut-tie are the fame as thcfe 
 of an incurable colic, voiiulus, or mortification of the 
 bowels. The beall affeAed with this complaint will 
 kick at its belly, lie down, and groan ; it has alio a to- 
 tal ftuppage in its bowels (except blood and mucus, 
 which it will void in large quantities), and a violent 
 fever, &c. To diftinguilh with certainty the gut-tie 
 from the colic, &c. the hand and arm of the operator 
 muft be oiled, and introduced into the anus, through the 
 reftuni, beyond the os pubis, turning the hand down to 
 the tranfverfe and oblique mulcles, where the veilels of 
 the tefticles enter the abdomen. There the ftring will 
 be found united to the mufcles, and is eafily traced to 
 the ftriclure by tl;e hand, without pain to the beaft. 
 
 From the general view of the agriculture of the coun. 
 ty of Hereford, drawn up by Mr Clark of Builth, Bre. 
 conlhire, we learn that Mr Harris farmer at Wickton, 
 near Leominfter, had been uncommonly fuccefsful in 
 the cure of the gut-tie. That gentleman informs us, 
 that he had cut cattle for this difeafe from the age of 
 three months to that of nine years ; ajid as it is a mat- 
 ter of great importance, we (hall ftate his method of 
 operating in his own words. 
 
 ««The
 
 H A R [7 
 
 " The only method of cure (fays lie) that can be 
 ■' fafcly ventured upon is, to make a perpendicular incifion, 
 tour inches under the third vertebra of the loins, on 
 the left fide, over the paunch or ftomach, and introduce 
 the arm to find the pan affcfted ; if poffiMe, keep the 
 beaft (landing by the help of proper aflitlauts. The 
 knife I make ufe of to fevcre tiie ftring is in the form 
 of a large fifh-hook, with an edge on the concave 
 tide ; It is fixed to a v'ng, which fits the middle finger, 
 which finger crooks round the back of the knife, the 
 end of the thumb being placed on its edge. The in- 
 ftrument, by being thus iield in the hand, is fecured 
 from wounding the furroanding intellines ; with it I 
 divide the ftring or ilrings, and bring out one or both, 
 as circumftances require. Here it is to be obferved, 
 that great care mull be taken by the operator not to 
 wound or divide the ureters, which would be certain 
 death. I then few up the divided lips of the perito- 
 neum very clofe, with a furgeon's needle threaded with 
 ftrong thread, eight or ten double, fufiiciently waxed ; 
 1 alfo few up the fl<in, leaving a vacancy at the top 
 and bottom of the wound fufiiciently wide to introduce 
 a tent of furgeon's tow, fpread with common digelliye 
 and traumatic baliam ; covering the incifion with a pla- 
 fter made of the whites of eggs and wheat flour. The 
 wound, thus treated, and drcffcd every day, will be 
 
 27 ] H A R 
 
 well in a fortnight. Tiie medicine I give to remove Gut-tie, 
 the ftoppage in the three ftomachs occalioned by the ^^'- 
 tie, and to carry off the fever, is four ounces of Glau- ' 
 ber's fait, two oiinc-es of cream of tartar, and one ounce 
 of tcnna, infufed in two pounds of boding water, adding 
 half a pound ot olive-oil, and working it off with plen. 
 ty of gnitl, mixed with a large quantity of iiifufion of 
 mallows and eldir-bark. J adminiller the gruel and 
 infufion for at lead two or three days ; by wliich time 
 the beaft will be well, will eat his provender, and chew 
 the cud, and will forever be relieved, and remain fafe 
 from this fatal dlforder. 
 
 " The following fimple and eafy method of caftra- 
 tion will efteftually prevent the gut-tie. Open the 
 fcrotum, loofen out the ttfticlcs, and tie the feveral vef- 
 fels with a waxed thread or filk ; or fear them with a 
 * hot iron, to prevent their bleeding, as in the common 
 way of cutting colts. This method can never difplace 
 the veffels of the teftlcles, bladder, kidneys, or intef- 
 tines ; all of which remain covered or attached to the 
 peritoneum, or lining of the abdomen of the beaft, 
 which renders it inipoinbie that there ftiould ever be 
 a ftriiAnre or tie on the gut«" 
 
 GUZ, an Indian meaiure, varying in different places, 
 but which may be reckoned about an Euglifn yard. 
 The guz of Akbar was 41 fingers. 
 
 H. 
 
 HANCES, Ranches, Haunches, or Hanfes, In ar- 
 chitecture, are certain fmall intermediate parts of 
 arches between the key or crown and tlie Ipring at the 
 bottom, being perhaps about one-third of the arch, and 
 fituated nearer the bottom tlian the top or crown ; and 
 are othervvife called the Jpandrels. See Arch in this 
 Supplement. 
 
 HANSPIKE, or Handspec, a lever or piece of 
 ftrong wood, for raifing by the hand great weights, 
 ivc. It Is five or fix feet long, cut thin and crooked at 
 the lower end, that it may get the eafjer between things 
 that are to be feparated, or under any thing that is to 
 be ralfed. It is better than s. crow of Iron, becaufe its 
 length allows a better poife. 
 
 Harriot (Thomas) was a very eminent mathe- 
 matician of the 16th and 17th centuries, of whom fome 
 account has been given in the Encyclopaedia Britannica. 
 In that article it has been fhewn, that Des Cartes had 
 fcen fome improvements of Harriot's in algebra, and 
 pnbliftied them to the world as his own ; but this piece 
 of plagiarlfm has been more completely proved in the 
 Aftronomical Ephemeris for the year 1788, by Dr 
 Zache, aftronomer to the Duke of Saxe-Gotha ; who 
 likewife fhews that Harriot was an aftronomer as well 
 as an algebraift. 
 
 " I here prcfent to the world (fays the Doftor) a 
 fhort account of fome valuable and curious manufcripts, 
 which I found in the year 1784 at the feat of the earl 
 of Egremont, at Petworth in SufTex, 
 
 " A predeceflbr of the family of lord Egremont, Harriot. 
 viz. that noble earl of Northumberland, named Henry '—- y— "^ 
 Percy, was not only a generous favourer of all good 
 learning, but alfo a patron and Ma.'ccnas of the learned 
 men of his age. Thomas Harriot, the author of the 
 faid manulcripts, Robert Hues (jwell known by his 
 Treatife upon the Globes), and Walter Warner, all 
 three eminent mathematicians, who were known to the 
 earl, received from him yearly penfions ; fo that when 
 the earl was committed prifoner to the Tower of Lon- 
 don in the year 1606, our author, with Hues and War- 
 ner, were his conllant companions ; and were ufually 
 called the earl of Northumberland's three Magi. 
 
 " Thomas Harriot Is a known and celebrated mathe- 
 matician among the learned of all nations, by his excel- 
 lent work, Artis Analyt'itie PrciKK, ad equaitones al^e- 
 iraicns nova expcditala ij' gcticrali mdbodo, rcjol-vendm, 
 TraSalus pnjlbumns t Eondon i6')i : dedicated to Hen- 
 ry earl of Northumberland ; publiflied after liis death 
 by Walter Warner. It is remarkable, that the fame 
 and the honour of this truly great man were conftantly 
 attacked by the French mathematicians, who could not 
 endure that Harriot fiiould in any way dlmlnifti the 
 fame of their Vieta and Des Cartes, efpecially the lat- 
 ter, who was openly accufed of plaglarifm from our au- 
 thor. 
 
 " Des Cartes publilhed his Geometry fix years after 
 Harriot's work appeared, viz. In the year 1637. Sir 
 Charles Cavcndlft), then ambaffador at the French court 
 
 a:.
 
 I-I A R 
 
 'Haricot, at Paris, obfcrvcd to the famous geometiician Rover, 
 —-~\'~—' x't^, tViat thtfe i.iipvovcmcnts in anaiyfis liad been alreadv 
 ir.ade thife iix years in England, snd ilicwed hiin af- 
 terwrtids Harriot's Arth /Inulyt'ue Praxis; wliicli, as 
 Rovcrval was looking over, at every pa^c he cried oat, 
 Otti ■' ohI! il I' a 1114 J 2~i's ! yes ! he has frcr. il ! Yin C.i.xes 
 liad alfo been in England before Harriot's death, and had 
 heard of his new impicveme'.ts and inventions in analyfis. 
 " Now all this relates to Harriot the celebrated 
 fmalyil ; but it has not hitherto been known that Har- 
 riot wuG an eminent aftronomtr, both theoretical and 
 pratlical, which firll appears by thefe manufcn'pts; 
 anioiig which, the mod remarkable are 199 oblerva- 
 tions of the fun's fpots, with their drawings, calcula- 
 tions, and determination of the fun's rotation about his 
 axis. There is the greatell probability that Harriot 
 wa; the f.ril difcoverer of thefe fpots, even beiore cither 
 ■Galileo or Scheiner. The earlieil intelligence we have 
 of tl'.e hrft difcovered folar Ipots is of one Joh. Fabi i- 
 cius Phryfius, who in the year f6i 1 pubLlhcd at Wit- 
 temberg a finall treatife, m titled, De ALicu,'is in So/e ob- 
 ftrvatis £5f appareiUe ecri/m cum Sou- conver/iona narnxtio. 
 Oalileo, who is commonly accounted the nril difcoverer 
 of the folar fpots, publiflied his book, fjloria e Dimon- 
 j1r,rz.iom interne alle Machie Solare e hro accidents, at 
 Rome in the year 1613. His firft obfervation in this 
 work is dated June 2d 1612. Angelo de Filiis, the 
 , editor of Galileo's work, who wrote the dedication and 
 
 preface to it, mentions, page 3. that Galileo had not 
 only difcovered thefe fpots in the month of April in the 
 year loil, at Rome, in the Quirinal Garden, but had 
 fhewn them feveral months beiore (mo/// ni'ft innim%i) 
 to his friends in Florence ; and that the obfervations 
 of the diiguifed Apellcs (the Jefuit Scheiner, a pre- 
 tender to thii riift difcovery) were not later than the 
 month of Odober in -the fame year; by which the 
 epoch of 'hi; difcovery was fixed to the beginning of 
 the year 1611. But a paffage in the firft letter of Ga- 
 lileo's wor'ns, pa. II. give« a more precife term to this 
 difcovery. Galileo there fays in plain terms, that he 
 had obferved the fpots in the fun 18 months before. 
 The date of this letter is May 24. 1612; which brings 
 the true epoch of this difcovery to the month of Novem- 
 ber 1610. However, Galileo's iiiil produced obferva- 
 tions are only from June 2. 1612, and thofe of father 
 Scheiner of the month of Oftober in the fame year. 
 But now it appears from Harriot's manufcripts, that 
 his firll obfer'-ations of thefe fpots are of Dec. 8. 1610. 
 It is not likely that Harriot could have this notice 
 from Galileo, for I do not find this mathematician's 
 name ever quoted in Harriot's papers : But I find him 
 quoting book i. chap. 2. of Jofeph a Colla's Natural 
 tind MorrJ Hijlory of the IVeJl Indies ; in which he re- 
 lates, that in Peru there are fpots to be feen in the fun 
 ■ivhtch are not feen in Europe : and hence it is pro- 
 bable, that Harriot took the hint of looking for fuch 
 fpots. Befides, it is not unlikely, that living with fo 
 munificent a patron, Harriot got from Holland the new 
 inverted telefcopes much fooner than they could reach 
 Galileo, who at that time lived at Venice. H.irriot's 
 very careful and exaft c:bfervations of thefe fpots, fliew 
 alfo that he was in pofl'efGon of the bell and mod im- 
 proved .telefcopes of that time ; for it appears he had 
 (otne with magnifying powers of 10, 20, and 30 times. 
 At iesll there are no earlier obfervations of tlie folar 
 
 [ 72S ] l-I A R 
 
 fpots extant ti-.sn his; they run frem Decetnber 8. 1 
 1610, till January lii. 1613. 1 compared ihe corre.^ 
 fpondiiig ones with thefe ciblerved by Galileo, beiween 
 which 1 found an ex?ft agreement. Had Haniot had 
 any notion about Gaiiieo'G discoveries, he certainly 
 would have a'lo known fnmethiiig about the phalcs of 
 Venus and Mercury, and clpecially about the finguiar 
 (hape of Saturn, firll dlf..-overed by Galileo ; but I find 
 not a word in all his papers concerning the particular 
 figure of that planet. 
 
 " I found likewife (continues Dr Zach) anmng the 
 papers of Harriot a large fet of obiervHtious on the fa- 
 tellites of Jupiter, with drawings of them, their pofi- 
 tions, and calculations ot their revolutions and pern.ils. 
 iiis firft obfervation of thofe difcovered fatellites, I fi.id 
 to be of January 16. 1610; aud they go till Februaiy 
 26. 1612. Galileo preteud-3 to have difcovered them 
 Jjnuary "j. t6io; fo th^t it is not improb.ible that 
 Harriot was likewife the firll dilcovcrer oi thefe attend- 
 ants of Jupiter. 
 
 " Among his other obfervations of the moon, of e- 
 clipfes, of the planet Mars, of foldices, of refrattion, of 
 the declination of the needle, &c. there are remarkable 
 ones of the comet of 1607, and the latter comet (for 
 there were two) of 1618. They were all obiervcd 
 with a crofs-ilaff, by meafuring their dillances from 
 fixed dars ; whence thefe oblervations are the more va- 
 luable, as comets had before been but grofsly obferved. 
 Kepler himielf obferved tiie comet of 1607 only with 
 the naked eye, pointing out its place by a coarfe elli- 
 mation, without the aid of an inllrument ; and the, ele- 
 ments of their orbits could, in defeft of better obferva- 
 tions, be only calculated by them. The oblervations of 
 the comet of the year 1607 are of the more importance, 
 even now for modern aitroiioray, as this is the fame 
 comet that fulfilled DrHailey 's preditlion of its return 
 in the year I7s9- That preJittion was only grounded 
 upon tlie elements afforded him by thefe coarfe obleivar 
 tions ; for which reafon he only afGgned the term, of its 
 return fo the fpace of a year. The very intricate cal- 
 culations of the perturbations of this comet, afterwards 
 made by M. Cljiraut, reduced the limits to a month's 
 fpace. But a greater light may now be thrown upon 
 this matter by the more accurate obfervations on ths 
 comet by Mr Harriot. In the month of October 
 1785, when I converfed upon the fubject of Harriot's 
 papers, and ef'xcially on this comet, with the celebra- 
 ted mathematician M. de la Grange, direftor of the 
 Royal Academy of Sciences at Berlin, he then fnggeli- 
 ed to me an idea, which, if brought into execution, will 
 clear up an important point in aftronomy. It is w-ell 
 known to aftronomers how difficult a matter it is to de- 
 termine the mafs, or quantity of matter, in the planet 
 Saturn ; and how little fatisfadlory the notions of it are 
 that have hitherto been formed. The whole theory of 
 the perturbations of comets depending upgn this uncer- 
 tain datum, feveral attempts and trials have been madi? 
 toA'ards a more exae^ deterntination of it by the moit 
 eminent geometricians of this age, and particularly by 
 la Grange himfelf ; but never having been fatisfied with 
 the few aud uncertain data heretofore obtained for the 
 refolution of this problem, he thought that Harriot's 
 obfervations on the comet of 1607, and the modern 
 ones of the fame comet in 1759, would fugged a way 
 of refolving the problem a fofieriori; that of determiniiu; 
 
 by
 
 HAS [72 
 
 Hoffc'.^aift by tliem the elements of its eUIpfia. Tlie retarJatfon 
 **~~v-— of the comet, compared to its period, may clearly be 
 laid to tlie account of the altradlion and perturbation it 
 has fufFcred in the region of Jupiter uuj Saturn ; and 
 as the part of it belonging to J-ipiter is very well known, 
 the reniaiuder mull be the (hare which is doe to Saturn ; 
 whence the mafs of the latter may be inferred. In 
 confequence of thit. conhderation, I liave alr«\dy begun 
 to reduce moR of Harriot's obfcrvations of this comet, 
 in order to calculate by them the true elements of its 
 orbit on an tlli'ptical hypothefis, to complete M. de la 
 'Grange's idea upon thi:; matter. 
 
 " I forbear to mention here any more of Harriot's 
 analytical papers, which I found in a very great num- 
 ber. They contain feveral elegant folutions of qua- 
 dratic, cubic, and biquadratic equations ;' with fome 
 other folutions and loca genmetrica, that (hew his eminent 
 qualifications, and will ferve to vindicate them againll 
 the attacks of feveral Fiench writers, who refule him 
 the juilice due to his fl'.iil arid accompliilimeiits, merely to 
 fave Des Cartes's honour, who yet, by fume impartial 
 men of his own nation, was accufed of public plagiarifm." 
 HASSELQUIST (Frederick) was born in the 
 province of Ealt Gothland in 1-22, ajid ftudied medi- 
 cine and botany in the univerfity of Upfal. Linn;"eus 
 liad in his leiilurcs reprefented the extraordinary merits 
 and great celebrity which a young ftudent might ob- 
 tain by travelling through Palelline, a:id by inquiring 
 into and defcribing the natural hiHory of that country, 
 which was till then unknown, and had become of the 
 greateft Importance to interpret the bible, and to un- 
 derftand eaftern philology, Haffelqulll was fired with 
 ambition to accompllfli an objcft fo important in itfelf, 
 and fo warmly rtcmnmended by hh beloved mailer. 
 There being no fund arlfmg from the liberality of the 
 crown, private colleftions were made, which poured in 
 v^ry copioudy, efpecially from the native country of 
 the young traveller. All the faculties of the univerfity 
 of Upfal alfo granted him a (lipend. 
 
 Thus protedled, he commenced his journey in the 
 fummer of 1 749. By the interference of Lagerllroem, 
 he had a free paffage to Smyrna in one of the Swedilh 
 Eaft Indlamen. He arrived there at the conclufion of 
 the year, and was received in the moil friendly manner 
 by Mr A. Rydel, the Swedifh conful. In the begin- 
 ning of 1750 he fet out for Egypt, and remained nine 
 months at Cairo the capital. Hence he fent to Lin- 
 naeus, and to the learned focletles of his country, fome 
 fpecimens of his refearches. They were publiflied In 
 the pnbllc papers, and met with the greatcfl. approba- 
 tion ; and upon the propofitlon of Dean Baeck and Dr 
 Wargentin, fecrctary of the Royal Academy of Scien- 
 ces, a coUeftlon of upwards of 10,000 dollars In copper 
 money was made for the continuance of the travels of 
 young Haflelquift. CounfiUors Lagerftroem and Nor- 
 dencrantz were the mod adllve in ralfing fubfcriptions 
 at Stockholm and Golhenburgh. In the fpring of 
 I 75t, he repali-cd to his deftlnation, and palled through 
 Jaffa to Jerufalem, Jericho, &c. He returned after- 
 wards through Rhodus and Scio to Smyrna. Thus he 
 fulfilled all the expeftations of his country, but he was 
 not to reap the reward of his toils. The burning heat 
 SuppL. Vol. I. Part II. 
 
 9 1 HAT 
 
 of the Tandy defcits of Arabia had affecled his lungs ; H»r. 
 he reached Smyrna in a Hate of illnefs, in which he '' "*'"" 
 langulihed for fome time, and died February 9. 1752, 
 in the 3^ th year of his age. 
 
 The fruits of his travels were, however, preferved 
 througli the llbeialily of a great princefs. He had been 
 obliged to contradl debts. The Turks, therefore, feized 
 U])oii all his c ollections, and tiireatened to expofe them 
 to public fale. The Swedilh coiiful prevented it. He 
 fent, W'ith the intell'gence of the unliapp) cxic of his 
 countryman, an acc<uint of the dillreires under which he 
 died ; — and at the reprefentalion of Dean Baeck, Queen 
 Loulla Ulrica granted the fum of 14,000 dollars in cop- 
 per fpecie to redeem all his coUeftions. They arrived af- 
 terwards in good prefervation at Stockholm ; confilling 
 of a great quantity of antiques, Arabian maiiufcrlpts, 
 {hells, birds, ferpents, infedls, 6ic. and were kept in the 
 cabinets at Uhichfdale and Drottninghohn. Tlie fpeci- 
 mens of the natural curiofities of thefe mufeums iielng 
 double or treble In nuuiber, Linnius obtained fome of 
 them, and publifhed the voyage ot his ill-fated friend, 
 and honoured his memory with a plant wiileh he called 
 from his name HaJ'elqiiiJlia. Hasss lquista, Etuycl. 
 
 HAT-MAKING is a mechanical proctfs, which Is de- 
 tailed in the 'Encyclopedia from the bell Infurmatioa 
 that could then be obtained. We have lately learned, 
 however, that our detail Is fometlmes defeftive, and 
 fometimes erroneous; and it is our duty to fupply thofe 
 defefts, and to correft thofe errors. But, ftrangers as 
 we are to the bufinefs of hat-making, we fliould not 
 perhaps have fufpedled, that we had been milled by the 
 perfons whom we conlulted, had we not been informed 
 by a very intelligent writer in NIcholfon's Plulofopiiical 
 journal, that the account of the manufaftiiring of hats, 
 which Is given In the Encyclopsd'ta, is far from the 
 truth. This ii.forraatlon induced us to look through 
 the Journal itfelf for a more accurate account of ihe 
 procefs; well convinced, that the liberal minded author 
 of that work would not have pointed out our iniflakes 
 without making us welcome to avail ourfc-lves of his 
 aid to corredl them. Our readers will therefore be in- 
 debted only to Mr Nicholfon and his correfpondent for 
 whatever inltruclion they may derive from this article ; 
 and as we wifii not to deck ourlelves in borrowed 
 plumes, we fnall communicate that iiiilniiliun In the 
 words of its author. 
 
 Having vifitcd the manufadlory of Mcflrs CoUInfons, 
 hatters in Gravel-lane, Soutiiwark, Mr Nicholfon gives 
 the following account ot their procedure : 
 
 " The materials tor making hats are rabbits fur cut 
 off from the Hiin, after the hairs have been plucked out, 
 together with wool and beaver. The two former arc 
 mixed in various proportions, and of different qualities, 
 according to the value of the article intended to be made; 
 and the latter our author believes to be unlverfally ufcd 
 for facing the finer articles, and never for the body or 
 main fluff. Experience has (hewn, that thefe materials 
 cannot be evenly, and well felted together, unlefs all the 
 fibres be firll feparated, or put into the fame ftate with 
 regard to each other. This is the oKjift of the firll 
 procels, called iowitig. The material, without any pre- 
 vious preparation (a), is laid upon a platform of wood, 
 4 Z or 
 
 (a) Some writers mention a partial wetting of the fur while on the (kin, by lightly fmearing it with a folu- 
 tion of nitrate of mercury to give it a curl. Melirs CoUinfons do not ufe it, nor any other preparation.
 
 HAT [ 730 ] HAT 
 
 Hat. or of vvii;, fomcvvhat more thui four ft et fqiiare, calkd " When tlie batt is fiifficiently bowed, it is ready for Hat. 
 
 ""* a hurdle, whitb is fixed agi.iiiil tlic wall of tlie work- hrrJen'rng j which tcnn denotes the firll comtnencement > — 
 
 {hop, and is enh'ghtcned by a finall window, :ind fepa- of felting. The prepared material being evenly difpo- 
 ratcd by two fide p.trtitions from other hurdles wl.'irli fed on the hurdle, is lirlt prefi'ej dowrt -by the convex 
 occupy the rell of the fpace along the wall. The hurdle, fide of the bafket, then covered with a cloth, and prefleJ 
 if of wood, is made of deal planks, not quite three fucceffively in its various parts by the hands of the 
 inches wide, difpofed parallel to the wall, and at the Workman. The preffure is gentle, and the hands arc 
 dldance of one-fortieth or one-fiftieth of an inch from very flightly moved back "and forwards at the fame time 
 each other, for the purpoCe of fuffeiing the duft, and through a fpace of perhaps a quarter of an inch, to fa- 
 other impurities of the ftuff, to pafs through ; a pur- vour the hardening or entangling of the fibres (See 
 pole ilill more efledually anfwered by the hurdle of Felting in this Supf-I.) In a very fhort time, indeed, 
 vire. the ftuff acquires luflicient firmnefs to bear careful 
 
 " The workman Is provided with a bow, a bow-pin, a handling. The cloth is then taken off, and a ilicct of 
 Lafket, and fcveral cloths. The bow is a pole of yellow paper, with its corners doubled in, fo as to give it a tri- 
 dtal wood, between feven and eight feet long, to which angular outline, is laid upon the batt, which lail is fold- 
 are fixed two bridges, fomewhat like that v.hich re- ed over the paper as it lies, and its edges, meeting one 
 ceives the hair in the bow of the violin (b). Over over the other, form a conical cap. The joining is foon 
 thefe is flretched a catgut, about one-twelfth part of an rrade good by preffure with the hands on the cloth. 
 Inch in thieknefs. The howpin is a ftick with a knob. Another batt, ready hardened, is in the next place laid 
 and is ufed for plucking tiie bow-ltring. The bafket is- on the hurdle, and the cap here mentioned placed upon 
 a fquare piece of ozier work, confiding of open flrait it, with the joining downwards. This laft batt being 
 bars with no crofTmg or interweaving) Its length acrofs alfo folded up, v.'illconfequently have its place ofjunfllon 
 the bars may be about two feet, and its breadth cigh- diametrically oppofne to that of the inner felt, which it 
 teen inches. The fides into which the bars are fixed ''mull therefore greatly tend to flrengtlien. The prin- 
 are (lightly bended into a circular curve, fo that the cipal part of the hat is thus put together, and now re- 
 tafket may be fet upright on one of thefe edges near quires to be worked with the hands a confiderable time 
 the right hand end of the hurdle, where it U'fually upon the hurdle, the cloth being alfo occalionaily fprink- 
 fiands. The cloths are linen. Befidcs thefe implements, led with clear water. During the whole of this ope- 
 ihe workman is alfo provided with brown paper. ration, which is called iafonin^ (c), the article becomes 
 
 " The tcu'ing commeiices by (hovelling the material firmer and firmer, and contrafts in its dimenlions. It 
 
 towards the right hand partition with the bafket ; upon may cafily be underftood, that the chief ufe of the pa- 
 
 which, the workman holding the bow horizontally in per is to prevent the fides from felting together. 
 
 his left hand, and the bow-pin in his right, lightly " The bafoning is followed by a (lill more effeftiial 
 
 places the bow-ftring, and gives it a pluck with the pin. continuation of the felting, called luorl'mg (d). This is 
 
 The firing, in its return, ftrikes part of the fur, and done in another fliop, at an apparatus called a battery, 
 
 raufes it to rife, and fly partly acrofs the hurdle In a confifting of a keltic (containing water (lightly acidula- 
 
 light open form. By repeated ftrokcs, the whole is thus ted with fulphuric acid, to which, for beaver hats, a 
 
 fuhjeftcd to the bow ; and this beating is repeated till quantity oEtihe grounds of beer ij added, or elfe plain 
 
 all the original clota or maffes of the filaments are per- water for rinfing out), and eight p/aiih of wood joined 
 
 feftly opened and obliterated. The quantity thus treat- together in the form of a frufluni of a pyramid, and 
 
 ed at once is called a iati, and never exceeds half the meeting in the kettle at the middle. The outer or 
 
 fpantlty required to make one hat. upper edge of each plank is about two feet broad, and 
 
 rifes 
 
 (p) Mr Nicholfon's correfpondent, who is himfelf a hatter, fays that the bow is bed made of afli ; that it is 
 compofed of the fit'ng or handle ; that the bridge at the finallcr end, or that which is neareft the window in the 
 aft of bowing, is called the coii ; and that the other bridge, which is nearer to the workman's hand, is called the 
 breech. 
 
 (c) Mr Nicholfon's correfpondent fays, that after bowing, and previous to the bafoning, a hardening Jh'm, 
 that is, a large piece of (I<iu, about four feet long and three feet broad, of leather alumed or half tanned, is preffed 
 tipon the bat, to bring it by an eafier gradation to a compaft appearance ; after which it is bafoned, being ftlU 
 kept upon the hurdle. This operation, the bafoning, derives its name from the procefs or mode of luorking,, 
 lieing the fame as that praclifed upon a wool hat after bowing ; the lall being done- upon a piece of call metal, 
 four feet acrofs, of a circular fhape, called a bjfon : the joining of each batt is made good here by (hufHing the 
 hand, that is, by rubbing the edge of each batt folded over the other to excite the progrefTive motion of each of 
 the filaments in felting, and to join the two together. Many journeymen, to hurry this work, ufe a quantity of 
 vitriol (fulphuric acid), and then, to make the nap rife and flow, they kill the vitriol, atid open the body again 
 by throwing in a handful or two of oatmeal ; by this means they get a great many made, though, at the fame 
 tjme, they leave them quite grainy from the want of labour. This, in handling the dry grey hat when made,, 
 may be in part difeovered ; but in part only. 
 
 (d) The intelligent writer who has been fo often quoted, fays, 'that Before this operation Ts begun, the hat is 
 dipped into the boiling kettle, and allowed to lie upon the plank until cold again ; this is c<&eAfoal:mg, that is,, 
 being perfeftly faturated with the hot liquor : if they are put in too haflily in this (late, for they are then only 
 bowed and bafoned, they would bu'rft from the edges, each 'batt not Being fufficieutly felted into the other*
 
 HAT [ 731 J 
 
 Haf. rifts a little neve than two feet and a half above the be done 
 
 "~v ground ; ainl tat (lope towards the kettle is conilder- 
 
 ably rapid, fo that the whole battery is little more than 
 fix feet in Jirmcter, The qiumlitj- of fnlphuric acid 
 added to the hmior is not fufEeient to give a four taRc, 
 but only renders It rou^h to the toiigne. In this li- 
 quor, heated rather higher than unpractifed hands could 
 bear, the article is dipped from time to time, and then 
 worked on the planks with a roller, and alfo by folding 
 or rolling it up, and opening it again ; in all which, a 
 certain degree of care is at firll necefTary, to prevent 
 the fides from felting together ', of which, in the more 
 advanced llages of the operation, there is no danger. 
 The iniperfectifjiis of the work now prefent themfelves 
 to the eye of the workman, who picks out knots and 
 other Irird fubttances with a bodkin, and adds more felt 
 upon all fuch parts as require Itrcngthcuing. This 
 added felt is patted down with a wet brufli, and foon 
 incorporates with the left. Tlie beaver is laid on to- 
 wards the conclufion of this kind of working. Mr 
 Nicholfon could not diltintlly learn why the beer 
 grounds were ufed with beaver-hats. Some workmen 
 laid, that by rendering the liquor more tenacious, the 
 hat was enabled to hold a greater quantity of it for a 
 longer time ; but others faid, that the mere acid and 
 water would not adhere to the beaver facing, but would 
 toll off immediately \v,lien the article was laid on the 
 plank. It is probable, as he oblerves, that the manu- 
 fafturers who now follow the clLiblilhed pradticc, may 
 not have tried what are the inconveniences this addition 
 is calculated to remove." 
 
 Our author's corrcipondent, however, affigns feveral 
 reafons for the addition ot thofe dregs, which, he fays, 
 ought to be thick, and the foureft that can be got. 
 I. Vitriol (fidphuric acid) would harden the hat too 
 much, which is kept mellow by the dregs. 2. The 
 dregs are faid by the workmen tcf hold or till the body, 
 whilft a little vitriol cleanfes it of the dirt, &c. that 
 may be on the rabbit or other wools. 3. Another ad- 
 vantage attending the ufe of dregs, whether of beer, 
 porter, or wine, is, that as the boiling of the dyeing 
 does not draw out much of the mucilage from each hat 
 when it comes to be iliffened, the diegs form a body 
 within the hat, fufiiciently ftrong or retentive to keep 
 the glue from coming througli amongfl the nap. 4. 
 Vitriol (fulphuric acid) alone purges or weakens the 
 goods too much ; con^fequently half of the -quantity 
 does better with the addition ol dregs, as it allows the 
 body to be made cloier by more work. 
 
 Of thefe four reafons for the ufe of dregs, the laft 
 alone appears to us perfpicuous or at all fatisfacfory. 
 But be this as it may, acid of fome kind gives a rough- 
 nefs to the furface ot the hair, which facilitates the me- 
 chanical aftion of felting ; and Mr CoUinfon informed 
 Mr Nicholfon, that in a procefs, crded carolling, they 
 make ufe of nitrous acid. In this operation, the ma- 
 terial is put into a mixture of the nitrous and fulphuric 
 acids in water, and kept in the digelling heat of a ftove 
 all-night ; by which means the hair acquires a ruddy 
 or yellow colour, and loies part of its itrenglh. 
 
 *' It mufl. be remembered, that our hat ftill pcfflefTcs 
 the form of a cone, and that the whole of the feveral 
 ac!iions it has undergone have only converted it into a 
 foil flexible felt, capable of being extended, though with 
 fome difficulty, in every direiSion. The next thing to 
 
 to 
 
 H A 1' 
 
 vc It the iorra required \;y the wfarer. 
 
 K»t 
 
 this purpofe, the workman turns up the edge or ' 
 to the dipth of about an inch and a half, and then 
 
 For 
 rim to 
 
 rctarns the point back again through the centre or axi» 
 of llie cap, fo far as not to take out this fold, but to 
 produce another inner fold of the fame depth. The 
 point being returned back again in the fame manner, 
 produces a third fold ; and thus the workman proceeds, 
 until the whole has acquired the appearance of a fiat 
 circular piece, confilling of a number of concentric un- 
 dulations or folds, with the point in the centre. This 
 is laid upon the plank, where the workman, keepinij 
 the piece wet with the liquor, pulls out the point witli 
 his fingers, and prcfil's It down with his hand, at the 
 fame lime turning It round on its centre In coniad wi:h 
 the plank, till he has, by this means, rubbed out a flat 
 portion equal to the intended crown of the hat. In 
 the next place, he takes a block, to the crown of whicU 
 he apphca the fl;'t central portion of the felt, and by 
 forcing a firing down the fides of the block, he caufcs 
 the next part to affume the figure of the crown, v,'liich 
 he continues to wtt and work, until it has properly dif- 
 pofed itfelf round the block. The rim now appears 
 like a flounced or puckered appendage round the edge 
 of tlie crown ; but the block being fct upright on the 
 plank, the requifite figure is foon given by \yorkIng, 
 rul'bing, and extending this part. Water only is ufed 
 in this operation of ialliioning or blocking ; at the con- 
 clufioa of which it Is preffid out by the blunt' edge Qf 
 a copper Implement for that purpofe. 
 
 " Previous to the dyeing, the nap of the hat Is raffed 
 or loofened out with a wire bruf.i, or carding inftru- 
 ment. The fibres are too rotten after the dyeing to 
 bear this operation. The dyeing materials are logwood, 
 and a mixture of the fulphates of iron and of copper, 
 known 111 the market by the names of green copperas 
 and blue vitriol. As the time of Mr Ccilinfon was limit- 
 ed, and my attention, fays Mr Nicholfon, was more par- 
 ticularly direftcd to the mechanical proceCes, I did not 
 go into the dye-houfe ; but I have no doubt that the 
 hats are boiled with the logwood, and afterwards i;n- 
 merfed in the faline folutlon. I particularly allied whe- 
 ther gi;lls were ufed, and was anlwered in the negative. 
 " The dyed hats are. In the next place, taken to the 
 fliffening fiiop. One workman, alTifisd by a boy, does 
 this part of the bufinefs. He has two veffels, or boil- 
 ers, the one containing the grounds of (Irong beer, 
 which cofts feven fiiilllngs per barrel, and the other vcf- 
 fel containing melted glue, a little thinner than it is 
 ufed by carpenters. Our author particularly afiied, 
 whether this laft folution contuincd any other ingre- 
 dient befides glue, and wasafTured that It did not* The 
 beer grounds are applied in the Infide of the crown tu 
 prevent the glue from coming through to the face, and 
 alio, as he fuppofes, to give the requifite firmnefs at a 
 lels e>;pence than could be produced by ghie alone. If 
 the glue were to pals through the hat in different places, 
 it might, he imagines, be -iiore difficult to produce an 
 even glels upon the face in the fuhfequent finilhing. 
 The glue itiffening Is applied after the beer grounds 
 are dried, and then only upon the lowtr face of the 
 flap, aiid the infide of the crown. For this purpofe 
 the hat is put into another hat, called a fllfFeniug hit, 
 the crown of which is notched, or flit open In various 
 dircdlous. Theft are then placed in a hole in a deal 
 4 Z 2 board,
 
 Hat. 
 
 HAT [ 73^ ] HAT 
 
 board, which fupports the flap, and the glue is apph'ed to ftate Mr Dunnage's method of making wafer proof Hat; 
 ' with a brufh. /jj/j , in imitation of beaver, for which, in November """"v— 
 " The dry hat, after this operation, is very rigid, and I 794, he obtained a patent. It is as follows : Let a 
 its figure irregular. The laft drefling is given by the (hag be woven, of fuch count in the reed, and cut over 
 application of moifture and heat, and the ufe of llie fuch fized wire, as will give the luUs to be manufadlu- 
 brudi and a hot iron, fomewhat in the fiiape of that ufed red from it that degree of richnefs, or appearance of 
 by tailors, but Ihorter and broader on the face. The fur, which may be thought neceflary. The materials 
 hat being foftened by expolure to lleam, is drawn upon of which this (hag may be compofcd are various, and' 
 a block, to which it is fecurely applied by the former fliould be accommodated to different kinds of hats, ac- 
 method of foicing 3 firing down from the crown to cording to the degree of beauty and durability to be 
 the commencement of the rim. The judgment of the given them, and the price at which they are defigned 
 workman is employed in moiftening, brufliing, and iron- to be fold ; that is to fay, filk, mohair, or any other 
 ing the hat, in order to give and preferve the proper hair that is capable of being fpun into .an end fine e- 
 figure. When the rim of the hat is not intended to nough for the purpofe, cotton, inkle, wool, or a mix- 
 be of an equal width throughout, it is cut by means of ture of any, or all the above materials, as may fuit the 
 a wooden, or perhaps metallic pattern ; but as no fuch different purpofes of the manufaftnrer. Thofe anfwer 
 hats are now in falhion, Mr Nicholfon faw only the bed (fays our author), which are made with two 
 tool for cutting them round. The contrivance is very poles, either of Bergam, piedmont, or Organzine filk, 
 ingenious and fimple. A number of notches are made rifuig alternately, in a reed of about nine hundred count 
 in one edge of a flat piece of wood for the purpofe of to eighteen inches wide, v/ith tiiree (hoots over each 
 inferting the point of a knife, and from one fide or wire. This method of weaving dlGributes the filk. 
 edge of this piece of wood there proceeds a flraight (as it may be put fingle into the harnefs), and pre- 
 handle, which lies parallel to the notched fide, forming vents any ribby appearance which it might have if the 
 an angle fomewhat like that of a carpenter's fquare. filk were pafTcd double, and tlse whole of the pole tut 
 When the legs of this angle are apphed to the outfide over each wire. This may be made either on a two 
 of the crown, and the board lies flat on the rim of the or four thread ground of haid filk, fhot with fine cot- 
 hat, the notched edge will lie nearly in the direction of ton, which he thinks preferable for (lioot, to filk, inkle, 
 the radius, or line pointing to the centre of the hat. or any other material, as it forms both a clofe and fine 
 A knife being therefore inferted in one of the notches, texture. An inferior kind of liats may be made from- 
 it is eafy to draw it round by leaning the tool againft any of tlie before-mentioned materials, and with cheap- 
 the crown, and it will cut the border very regular and er filk. This fhag fliould be ftretched on a frame, 
 true. This cut is made before the hat is quite finiflied, fuch as dyers ufe to rack cloth ; then (having previ* 
 and is not carried entirely through ; fo that one of the oufly fet the pile upright with a comb, to prevent its 
 laft operations confifts in tearing off- the redundant being injured or ftuck together), go over the ground- 
 part, which by that means leaves an edging of beaver with thin fize, laid, on with a foft brufli. For black, 
 round the external face of the flap. When the hat is or dark colours, common fize will do ; with white, or 
 completely finifhed, the crown is tied up in gauze pa- any light colour, ufe ifinglafs, or a fize made from white 
 per, which is neatly ironed down. It is then lead-y for kid leather. Thefe, or gum, or any other mucilagi- 
 the fubfequent operations of lining," &c. nous matter, which, without altering the colour, will 
 Our author concludes his valuable memoir on the prevent oil from getting through the ground fo as to 
 fabrication of hats, with fome obfervations on the pro- injure the pile, will anfwer the purpofe. Take care 
 bable gain or lofs of employing machinery in the ma- not to apply more of any material, as a preparation, 
 nufafture. Thefe obfervations, as they are ftated in than may be fuUy faturated with oil or varnifh, fo that 
 the oritrinal paper, we recommend to the ferious atten- water will not difcharge it from the ground. The 
 tion of every judicious hat-maker, who carries on his fize, or other glutinous matter, being dry, the pile 
 bufinefs on a large fcale ; for he will find them not the mud be teefeled, or carded with a fine card, till the 
 reveries of a rafh fpeculatift, but the cool rcfleftions of filk is completely taken out of the twift or throwing, 
 a real pliilofopher, who is at the fame time no ftranger when it will lofe its coarfe fhaggy look, and afTume the 
 to the arts of life. They fuggeft the following fubjefts appearance of a very fine fur. It mult now be once 
 of inquiry : Whether carding, which is rapidly and me- more fet upright with a comb, and you may proceed 
 chanically done, be inferior to bowing, which does not to lay on your water-pioof material ; this too may be 
 promlfe much facility for mechanical operation ? Whe- varied according to circumftances. For black, or any 
 ther a fucceffion of batts or cardlngs might be thrown dark colour, linfeed oil well boiled with the ufual 
 round a fluted cone, which rapidly revolving, in con- driers, and thickened with a fmall quantity of any 
 taft with three or more cylinder.s, might perform the good drying colour, will do ; for white, or very fine 
 hardening, and even the working, with much more colours, poppy or nut oil, or copal or other varnifhes, 
 precifion and fpeed than they are now done by hand ? may be ufed. In this particular the nianufaclurer muft 
 Whether blocking or fliap'!;ig be not an (.peration ex- judge what will befl; anfwer his purpofe, taking care 
 tremely well calculated for the operation of one or more never to ufe any thing that will dry hard, or be fubjed 
 machines? Whether loofe weaving and fubfequent felt- to crack. Mr Dunnage has found good drying lin- 
 ing might not produce a lighter, cheaper, and ft;ronger feed oil preferable to any other thing which he has 
 article ? And how far the mechanical feking, which is uftd, and, with the precaution of laying on very little 
 not confined merely to the hairs of animals, might be the firfl; time, it will not injure the fineft colours. When 
 applied to this art ? the firfl; coat of oil is dry, go over it a fecond and 
 Before we difmifs this fubjeft, it may be worth while a third time, if aecefiary, till you are convinced the 
 
 pores 
 
 1
 
 HAT [7 
 
 H^t. pores of the ground are fully clofed up, anil tlic (tuff 
 — v—"' ren>lered impervious to wattr. It (liould now iLiud 
 fcveral days, till the fmcU is fufficiently gone off; and 
 before it is taken from the frame, (huuld be gone over 
 v.itii fome ox-gall or lime-water, to take off the grtnfi- 
 nefs, which would othcrwife prevent tlie llllfeuing from 
 adhering to the oil. The material being now ready to 
 be formed into hats, (hould be cut into proper Ihapcs 
 for that purpofc. The crown fliould be made up over 
 a block, with needle and fitk, the oiled fide outwards. 
 The fearas fliould then be rubbed with a piece of hard 
 wood, bone, or ivory, to make them lie flat, and the 
 edges of the (luff pared off very near the ftitchcs, that 
 no joint may.appear on the right fide. The fcams 
 liiould then be carefully gone over with the prepared 
 oil, till every crevice or hole made by the needle is 
 completely lilled up, and the crown rendered perfectly 
 water-proof. The crown may then be turned and (lifl- 
 ened, by (licking Hnen, leather, paper, or any other 
 material that may be found to anfwer the purpole, to 
 the inner or painted iide, till it acquires about the fame 
 degree of lliffnefs, or refillance to the I ouch, as a good 
 beaver. The mucilaginous matter which he ufed to 
 attach the lliffening to the crown, and the upper and 
 under parts of the brim to each other, was compofed 
 of one pound of gum-arabic or fenega, one pound of 
 ftarch, and a half a pound of glue, boiled up with as 
 much water as reduced the whole to the conlillence of 
 a thick pafte. A greater or lefs proportion of any of 
 thefe ingredients may be ufed, and other glutinous and 
 adbefive fubftances may anfwer the fame purpo{es ; or 
 drying-oils may be made ufe of, inflead of this or other 
 mucilage ; or any of the refmous gums diffolved in 
 oil or fpirits ; only it (hould be obferved, in this cafe, 
 the hats will require more time in the preparation, as 
 the oily matter, unltfs expofed to the air, will not rea- 
 dily dry ; but he found by experience that the above 
 mentioned compofition does not dry hard or brittle, 
 but retains that pleafant flexibility which is agreeable 
 to the touch, while it communicates to the other mate- 
 rials a fufiicient degree of elailicity. Before the brim 
 is perfeftly dry, care fhould be taken to form a neck 
 or rifing rouijfl the hole where it is to be attached to 
 the crown, by notching it round with a pair of fcif- 
 fars, and then forcing it over a block fomething larger 
 than you have made thq hole, fo that the uncut (tuft" 
 may turn up, under the lower edge of the crown, about 
 a quarter of an inch. Before you join the crown and 
 brim together, go over the outlide of the neck of the 
 brim, and the infide of the crown, as high as the neck 
 will come (which ihould be about half an inch), with 
 the prepared oil ; and when they are nearfy dry, fo as 
 to adhere to the finger on touching them, put the crown 
 over the neck of the brim, and let them be fewed 
 ftrongly together, taking care to few down as little of 
 the pile as poffible, and ufing the iame precaution of 
 oiling, where the needle has been through, as was ob- 
 ferved in making up the crown. The hat is now rea- 
 dy for dreffmg ; which operation may be performed 
 over a block, with a hot iron, brufli, &c. in the fame 
 Bianner as thofe commonly called felts. When putting 
 in the lining, be very careful to let the needle only take 
 hold of the under furface of the brim ; for fliould it 
 perforate the upper one, the water will find its way 
 through, and tlie hat be of no value. Though we 
 
 33 ] HAW 
 
 have already declared how little we are acquainted with Hiwfo'np. 
 the operation of hat-making, we cannot help fuggefting • - 
 
 the inquiry, whethi r thcfe water-proof hats might no; 
 be improved both in ftrcngtii and beauty, by a (light 
 felting before the application of the (Izl- by tlie bru(h. 
 Such of them as are conipoled of wool or h.iir, or con- 
 tain a mixture of thefe materials, are unquellionably 
 fufceptible of felting. 
 
 HAWKINS (Sir John), was the youngeft fon of a 
 man who, though defcended from Sir John Hawkins 
 the memorable admiral and treafurcr of tiie navy in the 
 reign of Queen Elizabeth, followed at fivft the occupa- 
 tion of a houfe-carpenter, which he afterwards exchan- 
 ged for the profeffion of a furveyor and builder. He was 
 born in the city of London on the 3cth day of March 
 1719; and after having been lent tirft to one fchool, 
 and afterwards to a fecond, where lie acquired a toler- 
 able knowledge of Lttin, lie went through a regular 
 courfe of architeilure an<l perfpeclive, in order to fit 
 him for his father's profefri.jii of a furveyor. He was, 
 however, porfuaded, by a near relation, to abandon the 
 profeflion of his firtl choice, and to embrace that of the 
 law ; and was accordingly articled to Mr John .Scott an 
 attorney and iolicitor in great prailice. In this litua- 
 tion his time was too fully employed in the ailual dif- 
 patch of bufinefs to permit him, without fome extra- 
 ordinary means, to acquire the neceifary knowledge of 
 his profeffion by reading and (ludy ; befides that, his 
 mafter is fald to have been more anxious to render him 
 a good copying clerk, by fcrupulous attention to his . 
 hand-v.-riting, than to qualify him by inRrutlion to con- 
 duft bufinefs. To remedy this inciniveiiience, therefore, 
 he abridged himfelf of his rell, and rifing at four iii the 
 morning, found opportunity of reading all the neceifary 
 and mofl eminent law writers, and the works of our 
 mod celebrated authors on the fubjeiils of verfe and 
 profe. By thefe means, before the expiration of his 
 tlerkfhip, he had rendered himfelf a very able lawyer, 
 and had acquired a love for literature in general, but 
 particularly for poetry and the polite arts ; and the bet- 
 ter to facilitate his improvement, he occafionally fur- 
 nifhed to the Univerfal Spectator, the WcllminlU-r Jour- 
 n.il, the Gentlenvin's Magazine, and other periodical 
 publications of the time, eifays and difqulfitioiis on fe- 
 veral iubjefts. The ilr(l of thefe is believed to have 
 been an Eflay on Swearing ; but the exadl time of its 
 appearance, and the paper in which it was infertcd, are 
 both unknown. It was, however, re publiflied fome 
 years before his death (without his knowledge till he 
 faw it in print) in one of tlie newlpajrers. His next 
 produftion was an liflay on Ihnefty, inferted in the 
 Gentleman's Magazine forMsrch 1739 ' ''"'^ which oc- 
 calioned a controverfy, continued through the Maga- 
 zines for feveral fucceeding months, between him ami 
 a Mr Calamy, a deicendant of the celebrated Dr Ed- 
 mund Calamy, then a fellow-clerk with liim. 
 
 About the year 1741, a club having been inllltuted 
 by feveral amateurs of mufic, under the name of the 
 Madrigal Society, to meet eveiy Wednefday evening, 
 and his clerkfhip being now out, he became a member 
 of it, and continued fo many years. ~ Purfuing his In- 
 clination for mufic ftill farther, he became alfo a member 
 of the Academy of Ancient Mufic, which ufed to meet 
 every Thurfday evening at the Crown and Anchor in 
 the Strand, but fines removed to Freemafons Hall; 
 
 and
 
 HAW [73 
 
 THiwlvins. and of this he cominutd a mcmbtr till u few years be- 
 »'■""" fore its vemoval. 
 
 Impelled bj' his own tafte for poetiy, and excited to 
 it by his friend Foiler Webb's exainnle, who liad con- 
 tributed to the Gentleman's Magazine many very ele- 
 gant poetical compofitions, he had, before this time, 
 hiiiifelt beeoiTie an nccafional contributor in the fame 
 kind, as well to thnt as to fome other publications. 
 The earlieft of his produftions of this IjJtcies, now 
 known, is fuppofcd to be a copy of verfcs " I'o Mr 
 Ceinge Stanley, occafioned by lookiiig over fome Com- 
 ppfitions of his lately publifhcd," which bears date 19th 
 Ftbrnary 1740, and was infcrted in the Daily Adverti- 
 fer for February 21. 1741 ; but, about the year 1742, 
 he propofed to Mr Stanley the projeft of publifliing, in 
 co.ijunftion with him, fix cantatas for a voice and in 
 ibruments, the words to be furniflied by himfeif, and the 
 iidiilc by Mr Stanley. The propofal was accepted, the_ 
 publication was. to l:e at their joint expeiice, and for 
 their mutual beneiit ; and accordingly, in 174:, fix 
 cantatas were thus publiihcd, the five firll written by 
 Mr Hawkins, the fixth and laft by Foftcr Webb ; and 
 tliefe having fucceeded beyond the moft fanguine ex- 
 ptftations of tlicir authors, a fecond let of lix mure, 
 written wholly by himfeif, was in like manner pnblifh- 
 cd a few months after, and fucceeded equally well. 
 
 As thefe compofitions, by being frequently perform- 
 ed at Vauxhall, Raiielagh, and other public places, and 
 at many.private concerts, had become favourite enter- 
 tainments, many perfons, finding the author a!fo a mo- 
 dell well-informed young man of unexceptionable mo- 
 rals, were become dcfirous of his acquaintance. Among 
 thefe was Mr Hare of Limehoufe, a brewer, who being 
 himfeif a mufical man, and having met him at Mr Stan- 
 ley's at mufical parties, gave him an invitation to his 
 houfe ; and, to forward him in his profeffion, introdu-, 
 ced him to a friend of his, Peter Storer of Highgate, 
 Efq; which proved the means of making his fortune. 
 
 In the winter of the year 1749, Doftor, then Mr 
 Johnfon, was induced to iuftitute a club to meet every 
 Tuffday eveniog at the Kind's Head, in Ivy lane, near 
 St Pud's. It confided only of mnc perfons; and Mr 
 Hawkins was one of the firll members About this 
 time, as it is fuppofed, finding his father's houfe, where 
 he had hitherto rtlided, too fmall for the dilpatch of his 
 buiinefj, now very much increafing, he, in conjundtion 
 with Dr Munrkley, a phyfieian with whom he had con- 
 tracted an intimacy, took a houle in Clements- lane, 
 Lombard- flrcet. The ground floor was occupied by 
 him ar, an office, and the firll floor by the Dodlor as 
 his apartment. Here he continued till the beginning of 
 ^753' ^vhen, on occafion of his marriage with Sidney, 
 the youngeft of Mr Stoier's daughters, who brought 
 him a confiderable fortune, he took a houfe in Auftin 
 Friars, near Broad-ftreet, fl.ill continuing to follow his 
 profeiTion of an attorney. 
 
 Having received, on the death of Peter Storer, Efq; 
 his wife's brother, in 1739, a very '^'g^ addition to her 
 
 4 1 
 
 H A W 
 
 fortune, he quitted bufiiiefs to Mr Claris, aftef\rard3 Al- H^vtAirn. 
 dermaii Clark, who had a Ihort time before completed '"■*%—»' 
 his clerklhip under him, difpofed of his houfe in Aallin 
 Friars, and purcliaftd a houf;; at Twickenham. S.jon 
 afterwards he bougiit the Icafe of one in Hatton-ftrect, 
 Ijondon, for a town relidcnce. 
 
 From a very early period of his life he had entertain- 
 ed a llrong love for the amufement of angling ; and his 
 aifeftion for it, together with the vicinity of the river 
 Thames, was undoubtedly his motive to a refidence a', 
 this village. He had been long acquainted with Wal- 
 ton's Complete Angler; and had, by obfervation and 
 experience, become himfeif a very able proficient in the 
 art. Hearing, about this time, that Mr Mofes Browne 
 propofed to publiih a new edition of that work, and 
 being himfeif in poffeflion Qf fome material particulars 
 refpcfting Walton, he, by letter, made Mr Browne an 
 offer ,of writing, for his intended edition, Walton's 
 Life. To this propofal no anfwer was returned, at 
 leall for fome time; from which circumilance Mr Haw- 
 kins concluded, as any one reafonably would, that his 
 offer was net accepted ; and, therefore, having alio 
 learnt that Mr Browne meant not to publiih the lext as 
 the author left it, but to modernize it, in order to file 
 off the rufl, as hf called it, he wrote again to tell Mr 
 Browne that he underflood his intention was to fophif- 
 ticate the text, and that therefore he, Mr Hawkins, 
 would himfeif publifh a correct edition. Such an edi- 
 tion, in 1760, he accordingly pnblidied in otlavo wlt!)i 
 notes, adding to it a Life of Walton by himfeif, a Lire 
 of Cotton, the author of the fecond part, by the weli- 
 known Mr Oldys ; and a fet of cuts defigned by Wale, 
 and engraved by Ryland. 
 
 His propenfity to mufic, manifefled by his becoming 
 a member and frequenter of the feveral mufical focieties 
 before mentioned, and alio by a regular concert at his 
 houfe in Auftin Friars, had led him, at the time that 
 he was endeavouring to get together a good library of 
 books, to be particularly folicitous for collecting the 
 work^ of fome of the befl mufical compofers ; and, a- 
 mong other acquifitions, it was his fingular good for- 
 tune to become poffeffcd by purchafe of feveral of the 
 rnofl fcarce and valuable theoretical treatifes on the 
 fcience any where extant, which had formerly been 
 collected by Dr Pepufch. With this flock of erudition, 
 therefore, he, about this time, at the initance of fome 
 friends, fet about procuring materials for a work then 
 very much wanted, a Hiflory of the Science and Prattice 
 of Mufic, which he afterwards publifhed. 
 
 At the recommendation of the well-known Paul 
 Whitehead, to the Duke of Newcaflle, then Lord-lieu- 
 tenant for Middlefex, his name was, in 1 761, inferred 
 in the couiiniffion of the peace for that county ; and 
 having, by the proper ftudies, and a fedulous attend- 
 ance at the fellions, qualified himfeif for the office, he 
 became »n attive and uleful magitlrate in the coun- 
 ty (a). Obferving, as he bad frequent occalion to do 
 in the courfe of his duty, the bad flate of highways, 
 
 and 
 
 (a) When he firft began to aft, he formed a refolution of taking no fees, not even the legal and authcrifed 
 ones, and purfued this method for fome time, till he found that it was a temptation to litigation, and that every 
 triilin'r ale-houfe quarrel produced an application for a waiTant. To check this, therefore, he altered his mode, 
 anil received his due fees, but kept them feparately in a puife ; and at the end of every lummer, before he left: 
 the conutry for the winter, delivered the whole amount to the clergyman of the pari-Oi, to be by him diftribiited 
 among fuch of the poor as he judged fit.
 
 HAW [ 735 ] HAW 
 
 Hiwkins. and the j-rreat Jcfeft in the laws for amending and Moorlields in 1769, the inagiftiates of Middlefcx, and Hawltim.^ 
 
 ""-"v ' kcep'ng them in repiiir, he fet himfelf to revife the for- he at their head, with a party of guards, attended to ' 
 
 mer Itatutes, and drew an att of parhament confolida- oppofe them ; but the mob, on feeing them prepared, 
 ting all the former ones, and adding fuch other rcgiila- thought it prudent to difperfe. In tlufe and other in- 
 tions as were neceflarv. His fentirnenls on this fub- Ihnces, and particularly in his condiid as chairman, ha- 
 jed he publilhed in Oiflavo, in 17^.3, under the title of ving given fufiicient proof of his aiilivity, refohuion, a- 
 " Obfervations on the St;ite of Highways, and on the bilities, integrity, and loyalty, he, on tlie 23d of Ofto-^ 
 Laws for amending and keeping them in Repair;" ber 1772, received from his majefty the honour of 
 
 knighthood. 
 
 In 1773, Dr Johrfon and Mr Stevens publifhcd. In 
 10 vols Svo, their hrfl joint edition of Shakefpcare, to 
 ■which Sir John Hawkins contributed fuch notes as are 
 diilinguiflied by his name, as he afterwards did a few mofe 
 on the republication of it in 1778. An addrefs to the 
 king from the county of Middlefex, on occafion of the 
 American war, having, in 1774, been judged expedient, 
 and at his inllance voted, he drew up fucii an addrefs. 
 
 fubjoining to them the di aught of the acl before men- 
 tioned ; which bill being afterwards introduced into 
 parliament, paffed into a law, and is that under which 
 all the highway s in England are at this time kept re- 
 paired. Of this bill, it is but juftice to add, that, in the 
 experience of more than thirty years, it has never re- 
 quired a Angle amendment. 
 
 Johnfon, and Sir Jofhua, then Mr Reynolds, had. In 
 the winter of this year (176?) projected the ellabh'di- 
 
 ment of a club to meet every Monday evening at the - and, together with two of his brethren, had, in the month 
 
 Turk's Head, in Gerard-iheet ; and, at Johnion's foil- of Oftober in that year, the honour of prefenting it. ^ 
 citation, Mr Hawkins became one of the fird members. After fixteen years labour, he, in 1776, pubhTned, in 
 
 An event of confiderable importance engaged him, in five volumes quarto, his General Hiilory of the Science 
 
 Ihe year 1764, to ftand forth as the champion of the and Praftice of Mufic ; which, in coxlfequence of per- 
 
 county of Middlefex, againft a claim then for the firft miffion obtained in 1773, he dedicated to the king, and 
 
 time fet up, and fo enormous In its amount asjuftly to prefented it to him at Buckingham Houfe on the 14th 
 
 excite refiflance. The city of London finding "it necef- of November 1776, whei) he was honoured with an au- 
 
 !fary_ to rebuild the gaol of Newgate, the expence of dience of confiderable length both from the king and 
 
 •which, according to their own eilimates, would amount queen. 
 
 to L.4c.,ooo, had this year applied to parliament, by a Nut long after this publication, that is to fay in No- 
 bill brought into the Houfe of Commons, in which, on vember 1777, he was induced, by an attemjit to rob his 
 a fucgeilion that the county prifoners removed to New- houfe, which, though unfuccefsful, was made threr dif- 
 gate" lor a few days previous to their trials at the Old ferent nights with the interval of one or two only be- 
 Bailey, were as two to one to tlie London prifoners tween each attempt, to quit his houfe in Hatton-llreet ;. 
 conftantly confined there, they endeavoured to throw and, after a temporary refidence for a fliort time in St 
 the burthen of two-thirds of the expence on the county, James's Place, he took a leafe of one, formerly iiiliab' 
 
 while they themfelves propofed to contribute one-third 
 only. This attempt the magiftrates for Middlefex 
 thought it their duty to oppofe ; and accordingly a vi- 
 gorous oppoCtion to it was commenced and fupjiorted 
 under the conduft of Mr Hawkins, who drew a petition 
 againft the bill, and a cafe of the county, which was 
 printed and diftributed amongft the members of both 
 houfes of parhament. It was the fubjeft of a day's con 
 
 ted by the famous Admiral Vernon, in the flreet leading- 
 up to Queen Square, Weftminiler, and removed thither.. 
 By this removal he became a conllant attendant on 
 divine worfiiip at the parifli-church of St Margaret, 
 Weltminifter ; and having learnt, in December 177*1, 
 tliat the furveyor to the board of ordnance was, in de- 
 fiance of n provifo in the leafe under which they claim- 
 ed, carrying up a building at the eaft end of the church. 
 
 verfation in the Houfe of Lords ; and produced fuch which was likely to obfcure the beautiful painted glafs 
 an effeft in the Houfe of Commons, that the city, by 
 its own m.embers, moved for leave to withdraw the bill. 
 The fuccefs of this oppofition, and the abilities and fpi- 
 rit with which it was condutled, naturally attraded to- 
 wards Mr Hawkins the attention of his ftllow-magif- 
 trates ; and the chairman of the quarter fefnons dying 
 not long after, he was, on the 19th day of September 
 1 76 J, elefted his fuccefTor. 
 
 In the year 1771 he quitted Twickenham, and fold 
 
 window over tlje altar there. Sir John Hawkins, with 
 the concurrence of I'ome of the principal inliabitairts, 
 wrote to the iurveyor, and compelled hiui to takedown 
 two feet of the wall, which he had already carried up 
 above the lilt of the window, and to flope ofl the roof 
 of his building in fuch a manner, as that it is not only 
 no injury, but, on the contrary, a defence to the win- 
 dow. 
 
 In the montli of December 17S3, Dr Johnfon ha- 
 in 
 
 his houfe there to Mr Valllant ; and in the fummer of ving difcovered in himfelf fymptoms of a dropfy, fent 
 
 the next year, for the purpofe of obtaining, by fearches for Sir John Hawkins, and telling him the precarious 
 
 in the Bodleian and other libraries, farther mnterials ftate of his health, declared his delire of making a will, 
 
 for his hiilory of mufic, he made a journey to O.xford, and requefted him to be one of his executors. Sir John 
 
 carrying with him an engraver from London, to make accepted the office; inftrufted the Dofcor how to make 
 
 drawings from the portraits in the mufic fehool. his will; and on his death undertook to be his biogra- 
 
 On occafion of aftual tumults or expefled dillurban- pher, and the guardian of his fame, by publiihing a 
 
 ces, he had more than once been called into fervice of complete edition of his works. 
 
 great perfonal danger. When the riots at Brentford Not three months after the commencement of this 
 
 had arifcn, during the time of the Middlefex eleftion in undertaking, he met with the feverell.lofs of alnioft any 
 
 the year 1768, he and fome of his brethren attended to that a literary man can fuftain, (hort of that of his 
 
 fupprefs them ; and, in confequence of an expefted rio- friends or relations, in the dedruftion, by fire, of his II- 
 
 itous aiTembiy of the journeymen Sgitalfield weavers in brary ;, coiififling of a numerous and well-chofen co!. 
 
 Udliua
 
 HAW { 7,^ 
 
 Hawl.li >. lecVion of books, anci'nt and modern, Id many langua- 
 ''~~^>^~~~' gcE, and on moft fiibjccts, which it had been the bufi- 
 ncfs of above 30 years at iiUervlils to get together. 
 Of thi^ lofs, great as it was in pecuniary value, and 
 ccmprifing in books, prints, and drawings, many ar- 
 t icier that could never be replaced, he was never heard 
 in the fnialleil degree to complain ; but having found a 
 temporary rcteplitin in a large hoiife in Orchard-ftrcet, 
 Weftminfter, he continued there a fliort time, and then 
 tooli a houfe in the Broad Sanduary, Weftminlter. 
 
 This event, for a (hort time, put a ilop to the pro- 
 grefs of his literary purfuits. As foon, however, as he 
 could fufiiciently colleft his thoughts, he recommenced 
 his office of biographer of Johnfon ; and completed his 
 intention by publiihing, in 1787, the life and works, 
 in eleven volumes odlavo, which he dedicated to the 
 king. 
 
 With this produftion he terminated his literary la- 
 bours ; and having for many years been more particu- 
 larly fedulous in his attention to the duties of religion, 
 and accLiftomed to fpend all his leifure from other ne- 
 ceflfary concerns in theological and devotional ftudles, 
 he now more clofely addidled himfelf to them, and let 
 himfelf to prepare for that event, which he favv could 
 be at no great diftance ; and the better to accomplifh 
 this end, in the montli of May lySS, he, by a will and 
 other proper inftiuments, m.ade fuch an arrangement of 
 his affairs as he meant fhould take plpce after his deceafe. 
 In this manner he fpent his time till about the begin- 
 ning of May 17S9, when, finding his appetite fail him in 
 a greater degree than ufual, he had rtcourfe, as he had 
 fometimes had before on the fame occafjon, to the wa- 
 ters of the Iflington Spa. Thefe he drank for a few 
 mornings; but on tlic 14th of that month, while he 
 was there, he was, it is fuppofed, fcized with a paraly- 
 tic affeftion, as, on his returning to the carriage which 
 waited for him, his fervants perceived a vifible alteration 
 in his face. On his arrival at home, he went to ted, 
 but got up a few hours after, intending to receive an old 
 friend, from whom he expefted a vilit in the evening. 
 At dinner, however, his diforder returning, lie was led 
 tip to bed, from which he never rofe, on the 21 ft of 
 the fame month, about two in the morning, dying of 
 an apoplexy. He was interred on the 28th in the 
 cloifters of Weftminller Abbey, in the north walk near 
 the eaftern door into the church, under a ftone, con- 
 taining, by his exprefs injundions, no more than the ini- 
 tials of his name, the date of his death, and his age ; 
 leaving behind him a high reputation for abilities and 
 integrity, united with the utU-carnt character of an 
 aftive and refolute maglllrate, an affeclionate hufb.md 
 and father, a firm and zealous friend, a loyal fubjetl, 
 and a fincere Chiillian. 
 
 Such is the character of him in the Biographical 
 Diftionary, v^hich we have neither iight no inclina- 
 tion to controvert. With none of his works are we 
 acquainted but his edition of IVahon's Complete Angler, 
 and his Life of Johnfm. The former is a very plea- 
 fing book ; and in the latter are colkfled many inte- 
 refting anecdotes of literature and literary men ; but 
 they are not well arranged, and the ftyle of the com- 
 pofition is coarfe and flovenly. Sir John, we doubt 
 not, was a man of worth, and his refledions on the fen- 
 timental flang of Sterne and others, fhevv that he had 
 
 6 "J H E A 
 
 fuccefsfuUy Iludicd human nature ; but he cei'tainly was Tteat. 
 not a man of general tafte. •— y— • 
 
 HEAT. See in this Supplement, CiieSiistry, 
 Part 1. chap. v. where we have endeavoured to cilablKK 
 the modern doftrine refpecfting Cti/oric or latent heat. 
 In n°-309, Szc. of that article, we have given an ac- 
 count of Count Rumlbrd's ingenious eKperiments, in- 
 ftituted with a view to determine whether or not ca- 
 loric be a fubllance, and have ftated our reafons for 
 diffenting from his opinion. It has been fuggefted to 
 us, however, by a friend, to whofe judgment we are 
 inclined to pay great deference, that it would be pro- 
 per, in this place, to give the Count s arguments at 
 full length, and in hi» own words ; and the propriety of 
 this is the more apparent, that in the fnpplementary 
 article El-ectricity, we have hinted our own lufpi- 
 cions of the non-exiftence of an eledncal jla'id. The 
 Count then reafons from his experiments in the follow- 
 ing words : 
 
 " By meditaiting on the refults of all thefe experi- 
 ments, we are naturally brought to that great quellion 
 which has fo often been the fubjedl of fpeculation a- 
 raong phllofophers, namely, What is h.°at ? — Is there 
 any fuch thing as an igneous fluid ? — Is there any thing 
 that can with propriety be called caloric ? 
 
 " We have feen that a very confiderable quantity of 
 heat may be excited in the fridlion of two metallic fur- 
 faces, and given off in a conftaut ftream or flux in all 
 diredions, without interruption or intermldion, and 
 without any figns of diminution or exhauftion. 
 
 " From whence came the heat which was continual- 
 ly given off in this manner in the foregoing experiments? 
 Was it furnlfhed by the fmall particles of metal detach- 
 ed from tlie larger folld mafles on their being rubbed 
 together ? This, as we liave already feen, could not pof- 
 fibly have been the cafe. 
 
 " Was it furnlfhed by the air? This could not have 
 been the cafe ; for in three of thefe experiments, the 
 machinery being kept immevfed in water, the accefs of 
 the air of the atnioiphere was completely prevented. 
 
 " Was it furnlfhed by the water which furrounded 
 the machinery ? That this could not have Ijcen the cafe 
 is evident ; frfl, becaufe this water was contiiiually re- 
 cei-ving heat from the machinery, and could not at the 
 fame time be giving to and receiving heat from the fame 
 body ; and, fecondly, becaufe tliere was no chemical de- 
 compofition of any part of this water. Had any fuch 
 decompofition taken place (which indeed could not rea- 
 fonably have been expefted), one of its-compound elaf- 
 tic fluids (molt probably Inflammable air) mull at the 
 fame time have been fet at hberty, and, in making its 
 efcape Into the atmofphere, would have been detefted ; 
 but though I frequently examined the water tu fee if 
 any air bubbles rofe up through it, and had even made 
 preparations for catching them, in c/ider to examine 
 them if any fliould appear, I could perceive none ; nor 
 was there any fign of decompofition of any kind what- 
 ever, or other chemical procefs going on in the water. 
 
 " Is it poffible the heat could have been fupplled by 
 means of the iron bar to the end of which the blunt 
 fteel borer was fixed ? or by the fmall neck of gun-me- 
 tal by which the hollow cylinder was united to the 
 cannon ? Thefe fuppofitions appear more improbable 
 even than either of thofe before mentioned ; for heat was 
 
 continually
 
 H E L 
 
 Heal, continually ffoing off or out of the viachinsry, by both 
 *^''' '"°' tlicfe lull paffaE^cs, during tlie whole time the experiment 
 
 • lalted. 
 
 " And, in reafoning on this fubiei"t, we mud not 
 forget to confider that moll remarkable circiimllance, 
 that the fotirce of the heat generated by frlftion in 
 thefe experiments appeared evidently to be inexhauftible. 
 " It is hardlv necedarv to add, that anv thing «hich 
 
 [ 737 ] 
 
 H E L 
 
 as to give inftant notice of tlie approach of vcfftls to Mdem- 
 any part of it. >— -v~~ ~ 
 
 In the Encydopttlia, it is faid that peaches are the 
 only European fruits which thrive in 8t Helena ; but 
 this appears to be a miftake Several furts of fruit 
 trees imported into the idand lia<I been deilroyec' by a 
 particular infeft ; but enconragrnient hns bteii given 
 for the cultivation of thofe which that mifchievmis ani- 
 
 any infidc.tid body or fyftem of bodies can continue to mnl is known to fpare, fuch as the apple, for example. 
 
 furnifli iL'ithoril limitation, cannot pofTibly be a vhiltri.il 
 fu''flance ; and it appears to me to be extremely dlfJi- 
 cult, if not quite impoflible, to form any diftinfl idea 
 of any thing capable of being excited and communica- 
 ted in the manner the heat was excited and communi. 
 Gated in thcfe experiments, except it be motion. 
 
 " But althourrh the mechanifni of heat fiiould in faft 
 
 with ail the varieties of which it is fufceptlhle. The 
 plantain and banana, or the two fpecies of the mu/a, 
 thrive alfo rem.-rkably well. The ground is fertile, 
 and in favourable feafons produces, in fome inftances, 
 double crops within the year. Plantations, however, 
 of cotton, indigo, or canes, were not found to aiifwer : 
 though fome good coft'ee has been produced in it. A 
 
 be one of thofe myfteries of nature whirli are beyond botanic garden has been. ellabllQied near the governor's 
 
 the reach of human intelligence, this ought by no country houfe. 7\n Inlelligeiit gardener has been fent 
 
 means to difcourage us, or even lelTen our ardour, in to take care of it by the company ; and a vaft variety 
 
 our attempts to invetllgate the laws of Its opentions. of trees, ))l?.jits, and flowers of dilTeicnt, and fometimes 
 
 How far can we advance In any of the paths which oppoiite climates, are already collefted in it. The fur- 
 
 fcience has opened to us, before we find ourfelves en- rounding fea abounds in efculent fifn ; and feventy dlfi'e- 
 
 veloped in thofe thick mifts which on every fide bound rent fpecies, including turtle, have been caught upon the 
 
 the horizon of the human iiUelleit ? But how ample coads. Whales are fctu in great nur.ibers playing round 
 
 and Interefting is the field that is given us to explore I 
 " Nobody, furelv, in his fober fenfes has ever pre- 
 tended to nnderftand the mechanifni of gravitation ; and 
 vet what fublime difcoveries was our immortal Newton 
 enabled to make, merely by the invefilgatlon of the 
 laws of its adlion ! The eflefts produced in the world 
 
 the Ifland, where it is fuppofed the fouLhern whale fifh- 
 ery might be carried on to great uatlouiJ advantage. 
 
 The country is chiefly cultivated by blacks. Per- 
 fons of thiit colour were brought in a ftate of flavcry to 
 it by its firil European feftlers ; and it leldom hai)i'en3 
 that white njen will fubmit to common work v\here 
 
 by the agency of heat are probably jti/l as ex/eii/lve there are black Hives to whom it may be transferred, 
 and quite as important, as thofe which are owing to the Thefe were for a long lime under the unllmiud do. 
 
 tendency of the particles of matter towards each other ; 
 and there is no doubt but Its operations are in all cafes 
 determined by laws equally immutable." 
 
 HELENA, or St Hflena. In addition to the 
 account of this ifland in the Ejicydoptilia, the following 
 
 minion of their owners, until a n-prefentatlon of the a- 
 bufes made of that power induced the India Company 
 to place them under the immediate proteftloii of the. 
 magillracy, and to enatt various regulations in their fa- 
 vour ; which have contributed to render tiiem, in a 
 
 particulars from Sir George Staunton deferve a place great degree, confortable and fecure. Thefe regula- 
 in this Supplement, becaufe lome of them are important tlons may have hurt, at firfi, the feelings of the own- 
 in themfelves, while others correiS one or two mift.ikes ers of flaves, but not tl)eir real luterell ; for it appears, 
 into wdilch we had fallen, by adopting, implicitly, the that before their introduflion there was a lofs, upon an 
 narrative of Forfter. average, of about ten in a hundred flaves every year, to 
 The circumference of St Helena meafures fomewhat be fupphed at a very heavy expence ; whereas, under 
 
 lefs than twenty-eight miles. Along the whole coaft 
 to leeward, or to the northward, fliips may anchor in 
 perfeft fecurity in all feafons of the year, but the bank 
 fhelves fo abruptly afterwards, that the anchorage, be- 
 ing in deep water, is infecure. The tide fcldom rifes 
 above three feet and a half; but the furge of the fea is 
 
 the prefent fyllem, they naturally increafe. All future 
 importation of flaves into the ifland is prohibited. 
 
 Befides the blacks in a ftate of flavery, tlii-re are 
 fome who are free. '1 he labour of thefe tending to 
 dimlnifli the value of that of flaves, the free blacks be- 
 came once obnoxious to fome Have owners ; who hsd 
 
 fometimes tremendous ; and feveral accidents happened fufficient influence, in a grand jury, to prefent them as 
 
 in approaching or quitting the fliore, until a wharf was without vlfib'e means of gaining a livelihood, and liable 
 
 erefted lately, which renders the arrival there, and de- to become burdenfonie to the community ; but upon 
 
 parture from it, perfeflly fafe. In the immediate neigh- examination, it appeared that all free blacks of a<-e to 
 
 bourhcod of the ifland, ftorms are little known, thun- work were aftually employed ; that not one of them had 
 
 der is rarely heard, and lightning is feldom. perceived. been tried for a crime for feveral years, nor had any of 
 
 The tteep eminences which intervene between the them been upon the parlfli. They are now by the hu- 
 
 valleys, that are the chief feats of population, render mane interpofition of the company placed under the 
 
 the communication from one part of this little fpot to immediate proteiSlon of the government, and put near- 
 
 another flow and difiicult. Planters on the windward ly upon a footing with the other free inhabitants, who, 
 
 fide of the ifland confider a journey to the leeward, or when accufed of crimes, have the privilege of a jury, as 
 
 feat of government, as a ferious undertaking. Several well as in civil caufes. 
 
 of them take that opportunity of paying their refpefts The principal fettlement of St Helena has the pe- 
 
 to the governor, which is called there fometimes " go- culiar advantage of uniting the flicltcr of a leeward fi- 
 
 ing to court." There are St Helena planters who tuation with the coolnefs of windward gales. The 
 
 have not travelled fo far. At prefent, by order of the fouth-eaft wind blows conllantly down the valley, ren- 
 
 governor, there are fignals fo placed all over the ifland, dering a refidence in it pleafant as well as healthy, 
 
 SuppL. Vol. I. Part II. 5 A The
 
 Hcllcold 
 
 II 
 Hinzuan. 
 
 HEN [ 738 ] H I N 
 
 The country is fo fertile, and the climate fo congenial them, and receivtd from them an additional brightnefs. Hinzuan. 
 to the human feelings, that perhaps it would -be dif- Next to this dlftant 1 anije of hills was another tier, part ' - 
 ficult to fi:ul out a fpot where perl'ons, nrU having ac- of which appeared charmingly verdant, and part rather 
 nu'red a relidi for the enjoyments of tlie world, or al- barren ; but the contrail of colours changed even this 
 ready advanced in life, and furfeited with them, could nakednefs into a beauty : nearer llill were innumerable 
 have a better chance of protrafting their days in eafe, mountain?, or rather cliffs, which brought down their 
 health, and comfort. verdure and fertility quite to the beach ; fo that every 
 
 HELICOID Parabola, or the Parabolic S/iral, {hade of green, the fwecteft of colours, was difplaycd 
 is a curve ariling from the fuppofition that the common at one view by land and by water. But nothing Con- 
 or Apol!oiiiaM parabola is bent or twifted, till the axis daced more to the variety of this enchanting prc.fpeft, 
 come into the periphery of a circle, the ordinates ftill than the many rows of palm trees, efpecially the tall 
 retaining their places and [)erpeiidicular pofitions with and graceful Arecas, on the (hores, in the valleys, and 
 refpeft to the circle, nil tliefc lines Hill remaining in on the ridges of hills, where one might almoil fuppofe 
 the fame plane them to have been planted regularly by defign. A 
 
 HELISPHERICAL Line, is the Rhumb line in more beautiful appearance can fcarce be conceived, 
 Naviration ; beinff fo called, becaufe on the globe it than fuch a number of elegant palms in fuch a fitua- 
 winds round the pole helically or fpirally, coming ftill tion, with luxuriant tops, like verdant plumes, placed 
 nearer and nearer to it. at jull intervals, and fhowing between them part of the 
 
 HENIOCHAS, or Heniochus, a northern con- remoter landfcape, while they left the reft to be fup- 
 Ilellation, the fame as Auriga, which fee Eiicycl. plied by the beholder's imagination. The town of 
 
 HERSCHEL, the name by which the French, and Alatfamiido lay on our left, remarkable at a dift.mce for 
 nioft other European nations, call the new planet dif- the tower of the principal mofque, which was built by 
 covered bv Dr Herfchel in the year 1781. Its mark Halimah, a queen of the iilanJ, from whom the pre- 
 or character is W. The Italians call it Ouranos, or U- feut king is defcended : a little on our right was a fmall 
 
 town, called Banlani. Neither the territory of Nice, 
 with its olives, date trees, and cyprefTes, nor the iflesof 
 Hieres, with their delightful orange groves, appeared fo 
 charming to me as the view from the road oi Hinzuan." 
 Sir William Jones, fpeaking of the inhabitants, takes 
 notice of the Lords, Dukes, and Princes, of whom wc 
 have made mention after Major Rooke. " The frigate. 
 
 rania ; but the Eiighra, the Georgian Planet, or Geor- 
 gi'jm Sidus. 
 
 HETERODROMUS Vectis, or Lever, in Me- 
 chanics, a lever in which the fulcrum, or point of fnf- 
 penfion, is between the weight and the power ; being the 
 fame as what is otherwife called a lever of the full kind. 
 
 HINZUAN, the proper name of one of the Como- 
 
 ra iflands, which by different writers of dift'erent na- (fays he) was prefently furrounded with canoes, and 
 tions has been called Auzuame, /lijuan, Ju.nnny, and the deck foon crowded with natives of all ranks, from 
 Johanna, and which is defcribed in the Eiicyclopitdia the high born chief, who waflied linen, to the half. 
 ■ under the name of St Joanna. In that article, it is naked (lave, who only paddled. Moil of them had let- 
 cbferved, that an anonymous writer has cenfurcd the ters of recommendation from Englifhmen, which none 
 defcriptions of this ifland given by the Abbe Reynal of them were able to read, though they fpoke Englifh 
 and Major Rooke, as being not only exaggerated, but intelligibly ; and fome appeared vain of tides, which 
 erroneous ; neither the country bfing fo piclurefquc as our countrymen gave them in play, according to their 
 the former reprefents it, nor the inhabitants meriting fuppofed llations : we had Lords, Dukes, and Princes, 
 the refpeftable charafler given of them by the latter. on board, foliciting our cuilom, and importuning us for 
 There was not perhaps much propriety in admitting prefents. In faft, they were too fenfible to be proud 
 into fuch a work as the Encyclopedia Britannica, the of empty founds, but jnllly imagined, that thofe ridi- 
 anonvroous cenfure of defeiiptions, authenticated by the culous titles would ferve as marks of diftinftion, and, 
 name's of refpeflable authai's ; but the befl repaiation . by attrading notice, procure for them fomething fub- 
 which we can make to thofe authors is, to infonn our' ftantial." He fpeaks with great rcfped of the king,, 
 readers, that their defcriptions of Hinzuan are confirm- whofe name wat Ahmed, as well as of feveral chiefs 
 cd by Sir William Jones, whofe teftimony, we believe, whom he faw, and feems to have met. with no man of 
 ro man will controvert. That accomplilhed fcholar, rank on the ifland whofe charafter was contemptible, 
 who vifited the iHand on his voyage to India, thus de- but Selim the king's eldeft fon. For the behaviour of 
 fcribes its appearance from the bay in which the fhip that prince, the old fovereign made the bell apology 
 rode at anchor. that he could, while he privately affured the interpre- 
 " Before us was a vaft amphitheatre, of which you ter, that he was much difpleafed with it, and would 
 mav form a general notion by pifturing in your minds not fail to exprefs his difpleafure. He concluded his 
 a multitude of hills infinitely varied in fize and figure, converfation with a long harangue on the advantage 
 and then fuppofing them to be thrown together, with which the Englifh might derive fromfending a fhip e- 
 a kind of artlefs fymmetry, in all imaginable pofitions. very year from Bombay to trade with his fubjefts, and oa 
 The back ground was a feries of mountains, one of the wonderful cheapnefs of their commodities, efpecial- 
 •which is pointed, near half a mile perpendicularly high ly of their cowries. Ridiculous as this idea might 
 from the level of the fea, and little more than three feem, it fhowed (fays Sir William) an enlargement of 
 miles from the fhore : all of them richly clothed with mind, a defire of promoting the interefl of his people* 
 wood, chiefly fruit trees, of an exquifite verdure. I and a fenfe of the benefits arifing from trade, which 
 had i^een many a* mountain of ftupendous height in could hardly have been expefted from a petty African 
 Wales and Swifierland, but never faw one before, round chief, and which, if he had been fovereign of Yemen, 
 the bofom of which the clouds were almofl continually might have been expanded into rational projeds pro- 
 rolling, whiles it green furamit rofe flourifhing above portioned to the extent of his doaiinions.
 
 H I N [7 
 
 HiT'i'"!' The maftcr of the frigate learned from one of the 
 ^-"~v— "^ chiefs a few curious circumilance;". concerning the go- 
 vernment of Hin^uaii ; wliicli he found to be a mo- 
 narchy h'mited by an ariilncracy. The king, he was 
 told, had no power of making war by liis own authori- 
 ty ; but if the afTembly of nobles, who v/ere fiopi time 
 to time convened by bim, refolved on a war with any 
 of the neighbouring illands, they defrayed the charges 
 of it by vohmtary contributions ; in return for which, 
 they claimed as their own all the booty and captives 
 that might be taken. The hope of gain or the want 
 of (laves is ufually the real motive for lueli eiTterprife:;, 
 and ollenlible pretexts are ealily found ; at that very 
 time, lie underllood they meditated a war, becaiife they 
 wanted hands for the following harvelt. Their fleet 
 confilled of lixtecii or feventeen fmall vefFels, which 
 they manned with about two thoufand five hundred 
 idanders, armed with miilkets and cutlafTes, or with 
 bows and arrows. Near two years before they had 
 polfeired themfelves of two towns in Mayata, which 
 they Hill kept and garrifoned. The ordinary expences 
 of the government were defrayed by a tax from two 
 hundred villages; but the. three principal towns were 
 exempt from all taxes, except that they paid annually 
 to the chief Mufti a fortieth part of the value of all 
 their moveable property ; and from that payment nei- 
 ther the king nor the nobles claimed an exemption. 
 The kingly authority, by the principles of their confti- 
 tution, was confidered as elective, though the line of 
 fuccefiion had not in faft been altered iince the lirll e- 
 lection of a fultan. 
 
 Sir William Jones concludes his remarks on this 
 ifland with fome reflections ; of which, though they may 
 be confidered as digrelTive, we are perfuadcd our readers 
 will approve of our extending the circulation. 
 
 " We have lately heard of civil commotions in Hin- 
 ^uan, which, we may venture to pronounce, were not 
 excited by any cruelly or viuJence of i\hnied, but were 
 probably occafioned by the inlolence of an oligarchy 
 naturally lioflile to king and people. That the moun- 
 tains in the Comara ifiands contain diamonds, and the 
 precious metals, which are ftudioufly concealed by the 
 policy of the feveral governments, may be true, though 
 I have no reafon to believe it, and have only heard it 
 afferted without evidence ; but I hope, that neither an 
 expetlation of fuch trcafures, nor of any other advan- 
 tage, will ever induce an European power to violate 
 the firfl principles of juftice by aifuming the fovereigu- 
 ty of Hinxumi, which cannot anfwer a better purpole 
 than that of fupplying our fleets with feafonable re- 
 frefhment ; and although the natives have an intereft 
 rri receiving us witii apparent cordiality, yet if we wifli 
 their attachment to be unfeigned and their dealings 
 jufl, we mull fet them an example of flrift honelly in 
 the performance of our engagements. In truth, our 
 nation is not cordially loved by the inhabitants of Hin- 
 ^uan, who, as it commonly happens, form a general o- 
 pinion from a few inllances of violence or breach of 
 faith. Not many years ago an European, who had 
 been hofpitably received and liberally fupported at 
 Matjamudo, behaved rudely to a young married wo- 
 man, who, being of lov/ degree, was walking veiled 
 thiough a llreet in the evening ; her hufband ran to 
 proteft her, and refented the rudenels, probably with 
 menaces, poiTibly with aftual force ; and the European 
 is faid to have given him a mortal wound with a knife 
 
 39 ] H I R 
 
 or bayonet, which he brought, after th;; fcufHe, from 
 his lodging. This foul murder, which the law of na- 
 ture would have jultified the magillrate in puniliiingi 
 with death, was reported to the king, who told the 
 governor ( [ ufe the very words of Alwi, a coufin of the 
 king's), that "it would be wifcr to hu(h it up." Al- 
 wi mentioned a civil cafe of his own, wliich ought not 
 to be concealed. When he was on the coall of Afri. 
 ca in the dominions of a very favage prince, a fmall 
 European veflfel was wrecked ; and the prince not onlv 
 ieized all that could be favcd from the wreck, but 
 claimed the captaip and the crew as his Haves, and 
 treated them with ferocious iiifolcnce. Alwi alfured 
 me, that, when he heard of tlie accident, he haltened 
 to the prince, fell prolhate before him, and by tears 
 and importunity prevailed on liim to give the Euro- 
 peans their liberty ; that he fupported them at his ow[i 
 expence, enabled them to build another velfel, in which 
 they failed to H'wx,iinn, and departed thence for Europe 
 or India : he Ihewtd me the captain's promifTory notes 
 for fums, which to an African trader muft be a coii- 
 fiderable objeCl, but which uere no price for liberty, 
 fafety, and, perhaps, life, which his good, though dif- 
 intereffed, ofliees had procured. ( I lamented that, in 
 my fituatioii, it was whully out of my power to afiill 
 Alwi in obtaining juftice ; but he urged me to deliver 
 an Arabic letter from him, inclofing the notes, to the 
 governor general, who, as he faid, knew him well ; and 
 I complied with his requcil. Since it is poflible, that 
 a fubitaiuial defence may be made by the perfon thus 
 acculed of injuftice, I will not name either him or the 
 veifel which he had commanded ; but, if he be living, and 
 if this paper Ihonld fall into bis hands, he may be induced 
 to refletl how highly it imports our national honour, 
 that a people, whom we call favage, but who admini- 
 Iter to our convenience, may have no jiill caufe to re- 
 proach us with a violation of our contrads." 
 
 HIPS, in architetlure, are thofe pieces of timber 
 placed at the corners of a roof. Thefe are much longer 
 than the rafters, becaufe of their oblique polition. liip 
 means alfo the angle formed by two pails of the roof, 
 when it rifes outwards. 
 
 Hip-Roof, called alio Italian roof, is one In which two 
 parts of the roof meet in an angle, rifing outwards : the 
 fame angle being called a valley, when it finks inwards. 
 
 HIRCUS, in attronomy, a fixed ilar of the firft mag- 
 nitude, the fame with capdla. 
 
 HiRCUs is alio uled by lome writers for a comet, en- 
 compaCTed as it were with a mane, leemingly rough and 
 hairy. 
 
 HIRUDO. See Encycl. A new fpccies of this in- 
 fedt was difcovcrcd in the South Sea by Le Martiniere, 
 naturalilt in Perouie's voyage of difcovery. He found 
 it buried about half an inch in a Ihark's liver, but could 
 not conceive iiow it had got thither. It was lomething 
 more than an inch long, of a whitifli colour, and com- 
 pofed of feveral rings fimilar tt) thul'e of the ticnia. The 
 (uperior part of its head was furnilhed with four fmall 
 ciliated mamillae, by which it took its food ; under eacl» 
 mamiUa on both fides was a fmall oblong pouch, in the 
 form of a cup ; and in the form of its injlrumenta ciba- 
 li.i, it very nearly rcfembles the animal which has been 
 luppofed to be the cauie of meafles in fwine. Both thefe 
 fpecics are referable to the genus hirudo, the cliaradters 
 of which, as given by Linmeus, Itand (f.'vs Mnrtinieic) 
 in need of reformation. 
 
 5 A 2 ' HIRUNDO 
 
 Hiiiziian
 
 HIS [ 740 ] HIS 
 
 Hirunilo, HIRUNDO EscuLEKTA (fee HiRVuDO, £ncyc/, the old government of France paid to the charaflcr and Hifpaniolj, 
 . P"" n° 3.), IS thus defcribed iji the Trunfadlons of the Ba- rank of thofe perfons whom it had placed over its fo- — ~v— ' 
 tavian Society In tie IJland oj Java, vol. iii. ; and the reign itttkmcnts, iecund to the inhabitants of Hifpa- 
 defcription confirms the iagacious coiijtfture of Mr La- niola a very coi.fiderable (hare of happinefs. In fpitc 
 tham refpeding the fize of the biid, which the reader of wiiat our rctllefs innovators call political evils, figns 
 will find in our article referred to. of profpcrity were everywhere vilible; their towns were 
 " The hiruudo efcnltiita is of a blackifli grey colour, opulent, their markets plentiful, their commerce exttn- 
 inclining a little to green ; but on the back to the tail, five, and their cultivation increafing. 
 as well as on the belly, this blacklih colotn- gradually Such was, in 1788, the ftate of the French colony, 
 changes into a moufe colour. The whole length ot the in the ifland of St Domingo; but in that eventful rear, 
 bird from the bill to the tail is about four inches and a the flame, which had burft forth in Europe, fpread it- 
 half, and its height from the bill to the extremity of felf to the Weft Indies. An affociation had been form- 
 the middle toe three inches and a quarter. The diftance ed in France upon principles fomewhat fimllar to thofe 
 from the tip of the one wing to that of the other, when of our fociety ior the abolition of the flave trade ; but 
 extended, is ten inches and a quarter. The largcfl that afTociation, which called itfelf Amis des Ncirs, had 
 feathers of the wings are about four inches in length, much more dangerous defigns than ours. Avowing 
 The head is flat ; but, on account of the thicknefs of its deteflation of every kind of flavery,as well as of the 
 the feathers, appears round, and to be of a large Irze in African trade, and condemning thofe abettors of liber- 
 proportion to the reft, of the body. The bill is broad, ty who dared to declare themlelvM poffcfrors of men, 
 and ends in a fliarp extremity, bent downwards in the its members kept up an intimate and clandtftine con- 
 form of an awl. The width of it is increafed by a na- neftion with thofe rich mulattoes who refided in France 
 ked piece of ftin, fomewhat like parchment, which, for their education, and laboured to convince them that 
 when the bill is ftiut, lies folded together; but which, neither their colour nor their^f;; ;'ouj- lirth fhoild make 
 when the bill opens, is confiderably extended, and en- any civil or political diftinftion between ihem and the 
 ablcs the bird to catch with greater eafe, while on wing, whites who were born in wedlock. To co-operate, 
 the infefts that ferve it for food. The eyes are black, as it were, with thefe faftious «nd falfe dodlrincs, the 
 and of a confiderable fize. The tongue, which is not National Affembly ilTued its famous declaration, ia 
 forked, is fliaped like an arrow. The ears are flat, which it was maintained that all mankind are born, and 
 round, naked fpots, with fmall oblong openings, and are continue free, and equal in their rights. The confe- 
 entirely concealed under the feathers of the head. The quence of this was fuch as might have been expedted. 
 neck is very fliort, as well as the legs and the bones of The mulattoes of Hifpaniola, inftrufted in the French 
 the wings. The thighs are wholly covered with fea- philofophy of the rights of man, broke out into rtbel- 
 thers ; and the very tender lower parts of the legs, and lion; but not afting in concert, they were qiu'ckly over- 
 the feet thtrafelvcs, are covered with a fl^in like black powered. 
 
 parchment. Each foot has four toes, three of which The fpirit, however, which had been excited aniong 
 are before and one turned backwards. They are all de- them, ftill continued to ferment ; and the National At- 
 tached from each other to the roots ; and the middle fembly of France, taking tlie ifate of the ifland into fo- 
 one, together vv'ith the claw, is fully as long as the lower lemn confideratiou, decreed, by a grtat majority, that 
 part of the leg. Each toe is furniflied with a black, its intention had never been to intermeddle with the in- 
 fharp, crooked claw of a confiderable length, by which ternal affairs of the colony ; that their internal legifla- 
 the animal can with great facility attach itfelf to crags tion was entirely their own ; and that the legiflature of 
 and recks. The tail is fully as long as the body toge- the mother country would make no innovation, direftly 
 ther with the neck and the head. When expanded it or indireftly, in the fyftem of commerce in which the 
 lias the form of a wedge, and ccnfifts of len large fea- colonies were already concerned. However grateful 
 thtrs. The four firft on each fide are long ; and, when this declaration might be to the whites of St Domingo, 
 the tail is clofed, extend almoil an inch beyond the reft, and in the then ftate of things however wife in itfelf, it 
 The other feathers decreafe towards the middle of the occafioncd difcontent and renionftrances on the pait of 
 tail, and are equal to about the length of the body." the factious friends of the negroes. They regarded it 
 
 There is a variety of this fpecies of hirundo, with a 
 fpeckled breaft, and white fpots on the tail feathers ; 
 and this, though lefs numerous than the other, and in- 
 deed not found at all in Java, appears to have been the 
 only hirundo cfculenta known to Linnaeus. For an ac- 
 
 a« an unwarrantable fanftion of the A fricaa traffic, and 
 a confcfiion that the planters of Hilpaniola were not 
 colonifts, but an independent people. 
 
 The colonifts thcmfclvts, indeed, or rather their re- 
 prefcntatives, feem to have thought that by this decree 
 
 count of the eatable nefts of thefe birds, and the manner they were rendered independent; for in their general, 
 
 of collefting them, fee Cap and Button in this Sup- affembly they palled an aft debarring the king's dele- 
 
 plement. ' g^te, the governor-general, from negativing any of 
 
 HISPANIOLA, or St Domingo, the largeft of their future afts. '^"--- -■-'-' ' ^— '■■ — 
 
 This violent meafure was far from 
 
 the Antilles or Caribbee iflands, has been defcribed, as 
 it exifted prior to the French revolution, in the Eiicy- 
 clop<edia. Previous to the year 1789 the government 
 of the French part of the ifland was adminiltered by an 
 officer called the Intendant, and a Governor-General, 
 both nominated by the crown, and inverted with autho' 
 
 giving univerfal fatisfadtion. The. wellern parifhes re- 
 called their delegates, while thofe of Cape Francois re- 
 nounced their obedience to the whole afi'cmbly, and pe- 
 titioned the governor to diffolve it. 
 
 During thtfe diffenfions, the commander of a ftiip of 
 the hne, which lay in the harbour of Port-au-Prince, 
 
 rity for three years. Their powers were in foir.e cafes gave a fumptuous entertainment to the friends of the 
 diflinft, and in others united; but though thefe powers governor ; on which account the feamen, who declared 
 were extenCve and almoft abfolute, the attention which themfelves in the intereft of the affembly, thought fit to 
 
 mutiny ;
 
 H I S 
 
 Hlfpanlnli nnUi'iiy ; and the aficnibly, in return, voffcl thtir thanks 
 ^—"v—-' to the mutineers. Some of their partisans, ftiy.ing at 
 the fame time a powder magazine, the governor dechi- 
 red them adherents to traitors, and called on all oiFicers, 
 civil and milltaiy, to bring thtm to punlflimcnt. This 
 was tlie fignal for civil inlurrecSion ; armed troops took 
 the field on both fides ; and war ftcmed inevitable, when 
 the allembly rcfolved to repair in a body to France, and 
 jullify their paft condiitt. 
 
 In the niran time the jl-.his Jis Noirs contrived to ex- 
 cite the people of colour to reliellion. They initiated 
 in the dottrine of equality and the rights of man cue 
 James Oge, then reliding in Paris in iome degree of 
 afHuence. They perfuaded him to go to St Domingo, 
 put himfelf at the head of his people, and deliver them 
 from the oppreffion of the whites; and in order to evade 
 the notice of government, thty undertook to procure 
 for him arms and ammunition in America. He em- 
 barked accordingly, July 1790, for New England with 
 money and letters of credit ; but notwithllanding the 
 caution of the ylm'u Jes Nt'lrs, his defigiis were difco- 
 vered by the French government, and his portrait was 
 fent out before him to St Domingo. He landed on the 
 ijland in Otlober, and fix weeks afterwards published a 
 manifefto, declaring his intention cf taking up aims., it 
 the privileges of whites were not granted to all perfoiii 
 ivhhout diflinRlon. He was joined by about 200 men 
 of colour ; and this little army of ruffians not only maf- 
 facred the whites wherever they fell in with them in 
 fmall numbers, but, by a fllll more uujuftifiable mode of 
 conduft, took vengeance on thofe of their own colour 
 who refufed to join their rebellious ftandard. They 
 were, however, foon overpowered by the regular troops; 
 and their leader, after difclofing, it is faid, fome impor- 
 tant fecrets, fufl'ered the piminiment due to his treafon. 
 While tliefe things were going or. in the illand, the 
 members of the Colonial AlTenibly arrived at Paris, 
 where they were received by the reprefenLatives cf the 
 French people with marked fyniptcms of averfion. 7'he 
 refolutions conipofing their famous decree were pro- 
 nounced improper ; their vote cf thanks to the muti- 
 neers was declared criminal ; they weie themfelves ptr. 
 fcnaily anefted ; orders were given for a new afiembly 
 to be called ; and the king was requcfted to augment 
 the naval and military force then at St Domingo. 
 
 The National Aflembly of France having decreed 
 that every perfon twenty-five years eld and upwards, 
 poflefling piopirty, or having rciided two years in t)ie 
 colony and paid taxes, (hculd be permitted to vote in 
 the formation of the colonial aflembly, the people ot co- 
 lour very naturally concluded that this privilege was con- 
 ferred u['on them. Siich, however, we believe, wrs not 
 the meaning of the National AfTenibly ; but Gregoire, 
 wiih the other friends of the ntgroes, at lall prcvaikd, 
 and nadattoes born of free parents were pronounced to 
 be not only worthy of chooung their repiefentatives, 
 but alfo eligible themfelves to ftals in the colonial af- 
 lemblies. This decree facrificed at once all the whites 
 in the ifland to the people of colour ; and the indlgna- 
 tio'i which filled the minds of both the royal and the 
 republican parties feemed to have wnited them in one 
 common caufe. They refolved to rejeft the civic oath ; 
 to confifcate the French property in the harbour, on 
 Avhich they aflually laid an embargo ; to pull down the 
 national colours, and to hoift the Britilh ftandard in their 
 ftead. The mulattoes in the mean time colkfted in ar- 
 
 [ 741 ] 
 
 H I S 
 
 med bodies, and waited with anxious cxpeftation to fee Ilifpiniila. 
 what nuafures the colonial affembly would adopt. « 
 
 During thefe difienfions, the negro Haves, into whofe 
 minds had been feduloully inltllled an opinion that their 
 rights were equal to thofe of their mailers, refolved to 
 recover their freedom. On the morning of the 23d of 
 Anguft 1791, the town of the Cajie was alarmed by a 
 contufed report that the (laves in the adjoining parilhes 
 had revolted ; and the tidings were foon confirmed by 
 the arrival ot thole who had narrowly efcaptd the mai- 
 facre. The rebellion had broken out in the parifli of 
 Acul, nine miles from the city, where the whites had 
 been bu'.ehered without diftinclion ; and now the rebels 
 proceeded from parifli to paiilh, murdering the men, 
 and ravifliing the unfortunate women who fell into their 
 hands. In a Ihort time the fword was accompanied 
 with fire, and the cane-fields blazed in every direftion. 
 The citizens now flew to arms, and the command of the 
 national troops was given to the governor, whiUl the 
 women and children were put aboard the fliips in the 
 harbour for fafety. In the firil aftion the rebels were 
 repulfed ; but their numbers rapidly increafing, the go- 
 vernor judged it expedient to adt folely on the defeufive. 
 In the fpace of two months it was computed that up- 
 wards of 2C00 white perfons perifiied ; and of the in- 
 furgcnts, who confifted as well of nadattoes as of ne- 
 groes, not fewer than lo.oco died by famine and the 
 fword, and hundreds by the hands of the executioner. 
 
 When intelligence of thefe dreadful proceedings reach- 
 ed Paris, the Affembly began to be convinced that its 
 equalifing principles had been carried too far ; and the 
 famous decree, which put the people of colour on the 
 fame footing with the whites, was repealed. 'Three 
 commllT.cncrs were likewife fent to the colony to refiore 
 peace between the whites and the mulattoes ; but two 
 cf thtm being men of bad charafler, and none of them 
 poflefling abilities for the arduous tafl< of extinguifliing 
 the flames of a civil war, they returned to France with- 
 out accomplifhing in any degree the objeA of their 
 milhon. 
 
 In the mean time the Anus ihs Koirs in tlie mother 
 countiy had once more gained the afcendant in the Na- 
 tional Aflembly ; and three new commlfTioners, San- 
 ihonax, Polvcrel, and Allhaud, with 60CO choCen men 
 from the national guards, were embarked for St Do- 
 mingo. It was ftrongly fufpccicd that the objeft of 
 thefe ccmmlfiioners was to procure unqualified freedom 
 for all the blacks in the ifland; but they folcmnly fwore 
 that their fole purpofe was to eflablifli the rights of the- 
 mulattoes, as decreed by the lav/ which had been lately 
 repealed. The whites therefore expedltd that a colo- 
 nial aflembly would be convoked ; but inllead of this 
 the coramlflioners nominated twelve perfons, of whom 
 fix had been members of the laft aflembly, and fix were 
 mulattoes, Une Comm'ijficn IiHenneil'uhe., with authority 
 to raife contributions on the Inhabitants, the application 
 of which, however, they refcrved to themfelves. The 
 governor finding that the commifiioners ufurped all au- 
 thority, complained that he was but a cypher in public 
 affairs ; his complaint was anfwered by an arred upon 
 his perfon, and he was fent a flate prifoner to France. 
 
 The tyranny of the commiffioners did not flop here. 
 They overawed the members of the commifTion htterme- 
 d'laire, by arrefting four of their number ; and difagree- 
 ing among themfelves, Santhonax and Polverel dlfmiffed 
 Ailhaud from their councils. War was by this time 
 
 declared
 
 H O L [74 
 
 ■H'{, aiiiiJa declared between the mother country and Great Britain, 
 *"""■ and prudence compelled the government of Fiance to 
 take fome care of the injured colony. Galbaud, there- 
 fore, a man of fair charafler, was appointed governor, 
 and ordered to put the ilLiiid in a Hate ot defence againtt 
 foreign invalion ; but poifeillng Weil India property, 
 V. hich It (eems was a legal dilqualitication for the office 
 of governor, tl\e commifTioncrs diiregarded his authori- 
 ty, and took up arms againft him. Finding theinfelves 
 likclv to he worlled, they offered topurchale the aid of 
 the rebel regroes, by the offer of a pardon for their paft 
 condudx, freedom in future, and the plunder of the ca- 
 jital. Two of the negro chiefs, more honourable than 
 the French comniifTioners, fpurned at the bafe propofal; 
 but a third, after the governor had fled to the fliips, en- 
 tered the town with 3000 revolted negroes, and began 
 an indifcriminate niaftacre. The miierable iniiabitants 
 fled to the fliore, but their retreat was ftopped by a 
 party of mulattoes ; and for two days the flaughter was 
 iuceffant. The town was half coufumed by fire ; and 
 the commifiioners, tenilied at the work of their own 
 ■hands, fled for proteAion to a fliip of the line, and 
 thence iflTued a manifefto, which, while it tried to exte- 
 nuate, evinced a confcioufiiels of their guilt. 
 
 Thus was loft the fineft iflaiid in the Well Indies^; 
 an ifland which produced alone as much fugar as all the 
 •Eritilh Weft India poffefllons united ; not to mention 
 the coffee and indigo, which were in immenfe quanti- 
 ties cultivated in Hifpaniola. Had it not been for the 
 rtftlefs machinations of the ^mis des Nvirs, it does not 
 E])pear that fo general a revolt would have taken place 
 CTnong the flaves ; for though the fpirit of republica- 
 iiifnl had found its way into the ifland, the republicans 
 i lined with the royalifts to keep the negroes in proper 
 fuhjeftion. The unfuccefsful attem.pt which, at the 
 vcqucft-of the more refpeftable part of the inhabitants, 
 the Britifii government made to fubdue the execrable 
 tommifiioners and their adherents, is frefli in the me- 
 emovy of all our readers, End need not here be detail- 
 ed at length. SuflSce it to fay, that after prodigies of 
 valour, our troops were compelled, rather by difeafe 
 than by the fwords of the enemy, to abandon the ifland. 
 Touffaint L'Ouverture, a black chief, converted it into 
 an independent republic, and continued to govern it un- 
 difturbcd, till the preliminaries of peace were figned be- 
 tween Britain and France in 1801. Immediately after 
 that event, Bonaparte dilpatched a fleet from Brefl:, 
 with the permiffion of our government, carrying a con- 
 fidcrable army under the command ot general Le Clerc. 
 Touffaint at firft refufed to fubmit. tJeveral. bloody ac- 
 tions were fought between the French troops and the 
 blacks, in which the former were unitormdy fuccefsful. 
 The open country was foon abandoned by the negroes : 
 feveral of Tonffaint's generals fubmitted ; and at lail he 
 himfelf was prevailed upon, by the addrefs and the mag- 
 nificent promifes of Le Clerc, not only to throw down 
 his arms, but to put himfelf into the power of the French 
 general. For fome days thefe promifes were religioufly 
 obferved ; but a pretence was foon found for breaking 
 them. Touffaint was ftript of his immenfe property, 
 and fent prifoner to France. Thus was the colony re- 
 covered to France in a ftill fliorter time tlian it had been 
 loft. Since that event, nothing has tranfpired concern- 
 ing the ftate of the ifland, or the regulations which the 
 French find it neceffary to make. But it is obvious, that 
 a confiderable period muft elapfe before it can be refto- 
 
 2 1 H O O 
 
 reil to that ftate of profpcrity which it formerly enjoy- 
 ed. 
 
 HOLLOW, in architefture, a concave moulding, 
 about a quarter of a circle, by fome called a cafement, 
 by others an abacus. 
 
 HoLLOirT'jiver, in fortincation, is a rounding made 
 of the remainder of two brnures, to join the cunain to 
 tiie crillon, where the imall Ihot are played, that they 
 may not be fo much expof'ed to the view of the enemv. 
 
 HOM0DR0MUt> Vectis, or Lever, in mecha- 
 UKs, is a lever in vyhich the weigiit and power are both 
 on the fame fide of the fulcrum as in the lever of the 
 2d and 3d kind ; being fo called, becaufe here the weight 
 and power move both in the fame dircdfion, whereas 
 in the heterodromus they move in oppohte diretfions. 
 
 HOOKE (Dr Robert) is laid, in the account of 
 him which is publilhed in the Encyclopicdia, to have laid 
 claim to the inventions of others, and to have boafted 
 ot many of his own, which he never communicated. 
 We will not prefume to fay that this charge is entirely 
 groundlefs ; but we know that it has been greatly ex- 
 aggerated, and that many ditcoveries undoubtedly made 
 by him have been claimed by others. Of this the 
 reader will find one confpicuous proof under the article 
 Watch (^Encycl.) ; and perliaps the following hiilory 
 of the inventions to which he laid claim may furnifh 
 another. It would be harfh to charge him with falfity 
 in any of them ; that is to fay, to imagine tliat he ei- 
 ther ttole them from others, or did not think, at leaft, 
 that he was an inventor. And, with refpedt to many 
 of them, the priority of his claim is beyond difpute. 
 
 1656, Barometer, a weather glafs. 
 
 1657, ^ fcapement, for maintaining the vibration of 
 a pendulum. — And not long after, the regulating or 
 balance fpring for watches. 
 
 1658, The double barrelled air-pump The co- 
 nical pendulum. — His firft employment of the coni- 
 cal pendulum was no lefs ingenious and fcientific than 
 it was original. He employed it to reprelent the 
 mutual gravitation of the planets ; a fact which he 
 had moll fyftematically announced. He had fnewri 
 that a force, perfectly analogous to gravity on this 
 earth, opci'ated on the furface of the moon and of Ju- 
 piter. Confidering the numerous round pits on the 
 furface of the moon, lurrounded with a fort of wall, 
 and having a little eiriinence in the middle, as the pro- 
 duttion of volcanoes, he inferred, that the ejedled mat- 
 ter fell bapk again to the moon, as fuch matter falls 
 back again to the earth. He faw Jupiter furrounded 
 with an atmofphere, which accompanied him ; and there- 
 fore prefled on him, as our air preffes on the earth : — 
 He inferred, that it was the fame kind of power that 
 maintained the fun and other planets in a round form. 
 He inferred a force to the fun from the circulation round 
 him, and he called it a gravitation ; and taid that it was 
 not the earth which defcribed the elhpfe, but tlie centre 
 of gravity of the earth and moon. He therefore made 
 a conical pendulum, whofe tendency to a vertical pofi- 
 tion reprefcnted the gravitation to the fun, and which 
 was projedted at right angles to the vertical plane ; and 
 Ihewed experimentally, how the different proportions of 
 the projetlile and centripetal tendencies produced vari- 
 ous degrees of eccentricity in the orbit. He then add- 
 ed another pendulum, defcribing a cone round the firil, 
 while this defcribed a cone round the vertical line, in 
 order to fee what point between them defcribed tke 
 
 elliplc.
 
 H O O 
 
 [ 743 ] 
 
 H O R 
 
 ellipfe. The refults of the experiment were intricate 
 ' and unfntisfaftory ; but the thouglit was ingenious. 
 He candidly acknowledged, that he had not.difcovered 
 the true law of gravitation which would produce the 
 (kfcviption of an ellipfe rmmd ihe focus, owing to his 
 want of due mathematical knowledge ; and therefore 
 left this inveftigation to his fuperiors. Sir Ifaac New- 
 ton was the happy man who made the difcovery, after 
 }iaving entertained the fame notions of the forces which 
 connefted the bodies of the folar fyftem, before he had 
 any acquaintance with Dr Hooke, or knew of his fpe- 
 culations. 
 
 1 660, The engine for cutting clock and watch wheels. 
 —The chief phenomena of capillary attraftion. — The 
 freezing of water at a fixed temperature. 
 
 1663, The method of fupplying air to a diving bell. 
 — The number of vibrations made by a mufical chord. 
 
 1664, His Micrographia was, by the council of the 
 Royal Society, ordered to be printed; but in that work 
 arc many juft notions refpefting refpiratlon, the com- 
 pofition of the atmofphere, and the nature of light, 
 which were afterwards attributed as difcoveries to Ma- 
 yow and others, who, though we are far from fnppo- 
 Jlng that they ftole their difcoveries from Dr Hooke, 
 were certainly anticipated by him. 
 
 1666, A quadrant by rcfleftlon. 
 
 1667, The marine barometer. — The gage for found- 
 ing unfathomable depths. 
 
 1665, The meafurement of a degree of the meridi- 
 an, with a view to determine the figure of the earth, 
 by means of a zenith feftor. 
 
 1669, The faft of the confervatio virhim vivarum, 
 and that in all the productions and extlnftinns of mo- 
 tion, the accumulated forces were as the fquares of the 
 final or initial velocities. This doftrine he announces 
 in all its generality and importance, deducing from it 
 all the confequences which John Bernoulli values lilm- 
 felf fo highly upon, and which are the chief fafts ad- 
 duced by Leibnitz in fupport of his dodlrinc of the 
 foices of bodies in motion. But Hooke was perfeftly 
 aware of their entire correfpondence with the Carteiian, 
 or common doftrlne, and was one of the firft in apply- 
 ing the celebrated 39th propofitlon of Newton's Prin- 
 clpla to his former pofitlons on this fubjeft, as a mathe- 
 matical dcmonftration of them. 
 
 1673, That the catenaria was the beit form of an 
 arch. 
 
 1674, Steam engine on Ncwcomen's principle. 
 1679, That the air was the fole fource cf heat in 
 
 burning : That combuillon is the folution of the inflam- 
 mable vapour in air ; and that in this folution the air 
 
 1680, He firft obferved the fccondary vibrations of H-irne. 
 claftlc bodies, and their connexion with harmonic founds. • 
 A glafs containing water, and excited by a fiddlelUck, 
 threw the water into undulations, which were fquare, 
 licxagonal, oftagonal, 3ic. fliewing that it made vibra- 
 tions fubordlnatc to the total vibration ; and that the 
 fundamental found was accompanied by its oftave, its 
 twelfth, &c. 
 
 1681, He exhibited mufical tones by means of tooth- 
 ed wheels, whirled round and rubbed with a quill, which 
 dropped from tooth to tooth, and produced tones pro- 
 portlontd to the frequency of the cracks or fnaps. 
 
 1684, He read a paper before the Royal Society, 
 in which he affirms, that fome years before that period, 
 he had propofed a method of diicourfing at a diftance, 
 not by found, but by fight. He then proceeds to de- 
 fcrlbe a very accurate and complete telegraph, equal, 
 perhaps, in all refpefis to tlujfe now in uie. But ioine 
 years previous to 1684, M. Amontans had not invent- 
 ed his telegraph ; fo that, tliough the Marquis of Wor- 
 cefttr unqueftlonably gave the firft hint of this inftru- 
 ment, Dr Hooke appears to have firft brought it to 
 perfeftlon. See Telegraph, Encycl. ; and a book, 
 publlfhed 1726, entitled Philofephical Experiments and 
 Obfervallons of the late eminent Dr Robert Hooke. 
 
 We are indebted to him for many other difcoveries 
 of le.Ter note ; fuch as the wheel barometer, the uni- 
 verfal joint, the manometer, fcrew divided quadrant, 
 telefcoplc fights for ailronomical inftruments, reprtfent- 
 atlon of a mufcular fibre by a chain of bladders, expe- 
 riments fhewlng the Inflefllon of light, and its attrac- 
 tion for folid bodies, the curvlllneal path of light thro' 
 the atmofphere. 
 
 HORNE (George, D. D,), late Lord Bifhop of 
 Nurvvich, was a man of fuch amiable dirpofitions, pri- 
 mitive piety, and exemplary morals, that we wifli it 
 were in our power to do juftlce to his charadler. His 
 life, It is true, has been already written, at confiderable 
 length, by two authors, pofTcfltd of cniditiou and of 
 unquefllonable integrity ; but meie erudition is by no 
 means lufScient to fit a man for difcharging the duties 
 of a biographer. It was not the learning of Johnfoii, 
 but his fagacity, and Intimate acquaintance with human 
 nature, that placed him fo far above his contemporaries, 
 in this department of literature. 
 
 Of Bifliop Home's biographers, one poiTcffed, in- 
 deed, the great advantage of having lived In habits of 
 intimacy with him from his boyifti years. In the au- 
 thenticity of his narrative, therefore, the fulleft confi- 
 dence may be placed : and that narrative we Ihall faith- 
 fully follow ; referving, however, to ourfelves the llber- 
 
 gives out its heat and light. That nitre explodes and _ty of fomctimes making refleftlons on the various inci- 
 
 caufes bodies to burn without air, becaufe it confifts 
 of this air, accompanied by its heat and light in a con- 
 denfed or folld ftate ; and air fupports flame, becaufe 
 it contains the fame ingredients that gunpowder doth, 
 that is, a nitrous fplrlt : That this air dlflblves fonie- 
 thlng in the blood while it is expofed to It in the huigs 
 in a very expanded furface, and when faturated with It, 
 oan no longer fupport life nor flame ; but in the aft 
 of folution, it produces animal heat : That the arterial 
 and venal blood differ on account of this fomethlng be- 
 ing wanting in one of them. In ihort, the fundamen- 
 tal doftrines of modern chemiftry are fyffematlcally de- 
 livered by Dr Hooke in his Micrographia, publinicd in 
 1664, and his Lampas, publiflieJ in 1677. 
 
 dents recorded, widely different from thofe of the au- 
 thor. 
 
 George Home was, in 1730, born at Otham in Kent, 
 a village near Maidflone, giving the name to a parKh, 
 of which his father was the re6tor. He was the fe- 
 cond of four fons ; of whom the eldeft died in very- 
 early life, and the youngeft, who Is ftill alive, fucceeded 
 his father both in the reftory of Otham and in that of 
 Breda in the county of Suflex. He had iikewife three 
 fifters, of whofe fortunes we know nothing. 
 
 Mr Home, the father of the family, was of a tem- 
 per fo remarkably avcrfe from giving pain or trouble' 
 upoti any occafion, that he ufed to awake his fo;i" 
 George, when an infant, by playing upon a flute, that- 
 
 the.-
 
 H O R 
 
 Hirne, 
 
 tlic cliange from deeping to awaking might be gradual 
 and pleafant. Having been for fome vears a tutor at 
 Oxford, be took upon himfelf the early part of the 
 claiTical education of this ftjvourite fon ; an office of 
 which lie was well qualified to difcharge the duties. 
 Uunder fuch an inftrnftor, the fubjecl of this memoir 
 led a very pleafant life, and made a rapid progrefs in 
 the Greek and Latin languages. By the perfuafion of 
 a friend, however, he was, at the age of thirteen, placed 
 in the fchool of Maidftone, \'.::n under the care of a 
 Mr Bye, eminent for bis knowledge of ancient litera- 
 ture. And remaining with this gentleman two years, 
 he added much to his ilock of learning ; and, among 
 other things, a little elementary knowledge of the He- 
 brew tongue, which Mr Bye taught on the plan of 
 Buxtorf. Though Dr Home afterwards rejefled that 
 plan, he readily admitted, that the knowledge of it was 
 of great advantage to him. 
 
 At the age of fifteen, he was removed from Maid- 
 ftone fchool to Univerfity college Oxford, where his fa- 
 ther bad happily obtained for him a fcholarfhip. At 
 college his iludies were, in general, the lame with thofe 
 of other virtuous and ingenious youths; while the vi- 
 vacity of his converfation, and the propriety of his con- 
 duft, endeared him to all whofe regard was creditable. 
 About the time of his taking his bachelor's degree, he 
 was chofen a fellow of Magdalen College ; and foon af- 
 terwards, if not before, commenced author. 
 
 The hiftory of his authorfliip is curious, and we fhall 
 give it at fome length. While he was deeply engaged 
 in the ftudy of oratory, poetry, and every branch of 
 polite literature, he was initiated by his faithful fi iend 
 Mr Jones in the niyfleries of Hutchinfonianifm ; but 
 Mr Jones was not his preceptor. Indeed that gentle- 
 man informs us, that when he firft communicated to 
 Mr Home the novelties with which his own mind was 
 filled, he found his friend very little inclined to confidcr 
 them ; and had the mortification to fee, that he was 
 himfelf lofing ground in Mr Home's efteem, even for 
 making the attempt to convert him. At this we are 
 not to be much furpiifed. Mr Home, though, by 
 his biographer's account, no deep Newtonian, faw, or 
 thought he faw, the neceffity of a vdcuitm to the pof- 
 fibility of mutton ; and as we believe that every man, 
 who knows the meaning of the woixls motiou and vacu- 
 um, and whofe mind is not biaffed in favour of a fyftem, 
 fees the fame thing, it was not to be fuppofed, that a 
 youth of found judgment would haftily relinquifh fo 
 natural a notion. By Mr Home, however, it was at 
 length relinqniflied. Mr Jones introduced him to Mr 
 George Watfon, a fellow of Univerfity college, whom 
 he reprefents as a man of very fuperior atcomplidiments; 
 and by Mr Watfon Mr Home was made a Hutchinfo- 
 nian of fuch zeal, that at the age of nineteen, he impli- 
 citly adopted the wild opinion of the author of that fyf- 
 tem, that Newton and Clarke had fcn-nied the defign of 
 bringing the Heathen jfuplur, or Stoical anima inutu/i, 
 into the place of the God of the univerfe. With fuch 
 a conviction imprcffed upon his mind, it is not wonder, 
 ful that he fliould endeavour to difcredit the fyflem of 
 Newton. This he attempted, by puhlifhing a parallel 
 between that fyftem and the Heathen dodlrines in the 
 Somnium Scipionis of Cicero. That publication, which 
 was anonymous, we have never feen ; but Mr Jones him- 
 felf admits it to have been exceptionable ; and the ami- 
 
 r 744 1 
 
 H O R 
 
 able author Teems to have been of the fame ojiinion, for Horne, 
 he never republilhed it, nor, we believe, replied to the '■~~v~-< 
 anfwers which it provoked. 
 
 H- did not, ho« ever, dofcrt the caufe, but piiblillied, 
 foon afterwards, a mild and ferious pamphlet, which he 
 called A Fair, Candid, end Impariiiil State of the Cafe 
 let-ween Sir Ifaac Ne-wton ami Mr Hiitcbinfon. Even 
 of this pamphlet we have not been able to procure a 
 fight ; but Mr Jones affures us, that the author al- 
 lows to Sir Ifaac the great merit of having fettled 
 laws and rules in natural philofophy, and of having 
 meafuredybrrrx as a mathematician with fovereign (kill ; 
 whilft he claims for Mr Hutchiufon the difcovery of 
 the true phyfiological caufes, by which, under the 
 power of the Creator, the natural world is moved and 
 direfted. 
 
 If this be a fair view of tiiejiate of the cafe, it allows 
 to Newton more than ever Newton claimed, or has 
 been claimed for him by his fondeft admirers ; for the 
 laws and rules, which he fo faithfully followed in the 
 ftudy of philofophy, were not fettled by him, but by 
 the illuftrious Bacon. With refpe£l to the true caufes 
 here mentioned, we have repeatedly had occafion, du- 
 ring the courfe of this Work, to declare our opinion, 
 that all men are equally ignorant of them, if they be 
 confidered as any thing diitincl from the general laws 
 by which the operations of nature are carried on. To 
 the difcovery of other phyfiological caufes, Newton, in 
 bis greateft work, made indeed no pretenfion ; but it 
 may be worth while, and can hardly be confidered as 
 a digreffion, to confidcr what are the pretenfions of 
 Huchinfon, to which Meffrs Home and Jones gave 
 fo decided a preference. 
 
 Mr Hutchinfon himfelf writes fo obfcurely, that we 
 dare not venture to tranflate his language into common 
 Englifli, left we fliould undefignedly mifreprcfent his 
 meaning ; but according to Mr Jones, who has ftudied 
 his works with care, his dillinguilhing doftriue in phi- 
 lofophy is, that " The forces, of which the Newtonians 
 treat, are not the forces of nature ; but that the world 
 is carried on by the a6lion ot the elements on one ano- 
 ther, and all under God." What is here meant by 
 the elements, we are taught by another eminent dif- 
 ciple of that fchool. " The great agents in nature, 
 which carry on all its operations, arc certainly (fays 
 Mr Parkhurft) ihc fluid of the heavens; or, in other 
 words, the fire at the orb of the fun, the light ilTuing 
 from it, and the fpirit or grofs air co-nllantly fupport- 
 ing, and concurring to the actions of the other two." 
 (See Cherubim in this Su^phrnent). Mr-Horne adopt- 
 ed this (yftem in preference to the Newtonian ; becaufe, 
 fays his biographer, " It appeared to him nothing bet- 
 ter than raving, to give active powers to matter, fup- 
 pofing it capable of acting where it is not ; and to af- 
 firm, at the fame time, that all matter is inert, that is, 
 inaftive ; and that the Deity cannot act but where he 
 is prefcnt, becaufe his power cannot be but where his 
 fuhfJnce is." 
 
 That much impious aiTogance has been betrayed, 
 not by Newtonians only, but by philofophers of every 
 fchool, when treating of the modus operandi of the 
 Deity, we feel not ourfelves inclined to controvert ; but 
 we never knew a well-informed Newtonian, who fpoke 
 of the aftive powers of matter but in a metaphorical 
 fenfe ; and fuch language is ufed, and muft be ufed, bv 
 
 the
 
 O R 
 
 Such was the fyftem of Heme. 
 
 H O R [ 745 ^ H 
 
 the followers of Hutchinfon. Mr Jones fpeaks of the ratc!y, many are valuable, 
 
 ' atTion of the elements; and Mr Parkhurft calls the fluid Hutthinfon when adopted by Mr Home. It was then 
 
 of the heavens, which, according to him, confiils of fire, but very little known; it could be ftudied oidy through 
 
 light, ami air, agenis ; but it would furely be uncandid the meilium of Htbrew literature, not generally culti- 
 
 to accufc tlicfe two pious men of aiihnalirtg the ele- vated ; and that lllcraturc, to the cultivation of wi)ich 
 
 ments, though we know that ailion and ntiivily, in the Mr Hutchii.lon had given a new and a better tiun, is 
 
 literal fenfe of the words, can be predicated only of In itlelf of the utmofl importance. Let it be obfirvcd, 
 
 living beings. With refpedl to giving aftive powers to too, that the HuUhinlonians have, for ^he moll part, 
 
 matter, therefore, the followers of Hutchinfon rave juft been men of devout minds, zealous in the caufe of 
 
 as much as thofe of Newton ; and we fee not the ra 
 ving of either in any other light than as the necelTary 
 coufvijiuence of the poverty of language. 
 
 But the Newtonian makes matter aft upon matter 
 at a dillance ! No ; the genuine Newtonian does not 
 make matter aS (in the proper fenfe of the word) at 
 
 minds, zealous lu tne caule 
 Ciiriftianity, and untainted by Arlanifm, Socinlanifni, 
 and the other hercfies which have fo often divided the 
 church of Chrlft : -and when all thefe clrciimftances 
 are taken into confideration, It will not be deemed a 
 proof of any defeft in Mr Home's undcrftandiiig, that 
 in early life he adopted the 'who/e of a fyftem, of which 
 
 all; but he believes, that God has fo conllituted mat- fome of the parts contain fo much that is good; efpe 
 
 ter, that the motions of different mafles of it are afFeft- dally when it is remembered, that at Jirjf vttio the a- 
 
 ed by each other at a dillance ; and the Hntchinfonlan gency of the celeftial fluid appears fo plauiible, that for 
 
 holds the very fame thing. As tills celelb'al fluid o? 
 Ma' Parkhurft's conlills partly of air, we know, by the 
 tell of experiment, that it is elallic. The particles of 
 which It is compefed are therefore diftant from each 
 other ; and yet they refill compreffion. How does the 
 Hutehinfcnian account for this faft ? Perhaps he will 
 fay, that as matter is in itfelf equally indifterent to mo- 
 tion and reft, God has fo conftituted the particles of 
 
 a time it feems to have impolcd upon the mind of New- 
 ton lilmfelf. 
 
 But the truth Is, that Mr florne was at no period 
 of his life a thorough-paced Hutcliinfoniari. It is con- 
 feffed by Mr Jones, " that Mr Hutchinfon and his ad- 
 mirers laid too great a (Irefs on the evidence of He- 
 brew etymology ; and that fome of them carried the 
 matter fo far, as to adopt a mode of fpeaking, which 
 
 this fluid, that though they poffefs no innate power or had a nearer refemblance to cant and jargon than to 
 
 adllvity of their own, they are affefted by each other found fenie and fober learning. Of this (continues he) 
 
 at a diflance, In confequenee of his fiat at the creation. Mr Home was very foon aware; and he was In fii 
 
 This we believe to be the only folution of the difficulty little danger of following the example, that he iifed to 
 
 which can be given by man ; but It is the very anfwer 
 given by the Newtonians to thofe who objeft to them 
 the abfurdity of fuppofing matter, to be affefled by mat- 
 ter at a dillance. That the motions of the heavenly 
 bodies are affedled by the prefence of each other is a 
 faft, fay they, which appears incontrovertible. " We 
 
 difplay the foibles of fuch perfons with that mirth and 
 good humour," which he poflefled in a more excjuiiite 
 degree than mofl men. This feems to be complete 
 evidence that he was never a friend to the etymologi- 
 cal part of the fyftem ; and the prefent writer can at- 
 teil, tliat, In the year 1786, he teemed by his conver. 
 
 have afcertained with precilion the laws by which thefe fatlon to have loft much of his convidlion of the agency 
 
 motions are regulated; and without troubling ourfelves of the celeftial fluid. He continued. Indeed, to fludy 
 
 with the true phyfiological caufes, have demonftrated the Hebrew Scriptures on the plan of Mr Hutchinfon, 
 
 the agreement of the phenomena with the laws. The unincumbered with the Malbretic points, or with rab- 
 
 interpofition of this celeftial fluid removes not a fingle binical interpretations ; and the fruits of his ftudies are 
 
 dlfliculty with which our dodlrine is fuppofed to be in the hands of the religious public, in works which, 
 
 clogged. To have recourfe to it can therefore ferve no by that public, will be elleenicd as long as their Ian- 
 
 purpofe, even were the phenomena conllftent with the guage is undeiftood. 
 
 nature of an elaftlc fluid confldered as a phyfieal caufe; Hitherto Mr Home was a layman, 'but he intereft- 
 but this is not the cafe. It is demonftrable (fee Astro- ed himfelf in every thing connedled with religion, as 
 NOMY and Dynamics In this Suppl.) that the motions much as the moft zealous dignitary of the church; ami 
 of the heavenly bodies are not confiilent with the me- coniidering the naturalisation of ^the Jews as a meafure 
 chanifm of an elaftic fluid, confldered as the caufe of at leaft indecent in a Chriftian country, he publifhed, 
 thefe motions; and therefore, whether there be fuch a in an evening paper, a feries of letters on that fubjeft, 
 fluid or not dilTufed through the folar fyftem, we can. both when the Jew bill was depending, and af"ttr it had 
 not allow that It is the great agent in nature by which paffed the hoiife. The letters were anonymous ; but 
 all its operations are carried on." they atlracled much notice, and many groundlefs con- 
 Such might be the reafoning of a well-informed New- jeftures were made refpeiling their author. To the 
 Ionian In this controverfy ; and it appears fo conchifive real author, the meafure which they oppofed was fo 
 
 againft the objeftions of Hutchinfon to the Newtonian 
 forces, as well as againft the agents which he has fub- 
 ftltuted In their ftead, that fome of our readers may be 
 dlfpofed to call in queftion the foundnefs of that man's 
 anderftandiug who could become a Hutchlnfonian fo 
 zealous as Mr Home. But to thefe gentlemen vre beg 
 
 very obnoxious, that he refufed to dine at the table of 
 a friend, only becaufe the fon-in-law of Mr Pelham was 
 to be there. And he was not much more friendly to 
 the marriage-aft than to the Jew-bill. If he conflder- 
 ed the one as difgraceful to religion, he probably 
 thought that the other, with Its numerous claufcs, might 
 
 leave to reply, that the foundeft and moft upright mind be made a fnare for virtue 
 
 is not proof agalnfl the influence of a fyftem, efpeclally The time nowr approached when he was to take holy 
 
 if that fyftem has novelty to recommend it, and at the orders, which to him was a very ferious affair; and 
 
 fame time confifts of parts, of which, when taken fepa- when he gave an account of his ordination to an inti- 
 
 Suppt. Vot. I. Part IT. 5 B mate
 
 H O R 
 
 Home, mate friend, he concluded tlie letter with the following 
 ' » rtik'^tioiis, which, even in an abiliaft like this, it would 
 
 be unpsrdouable to omit : 
 
 " May he, who ordered Peter three times to feed 
 h:s lambs, f\se me grace, knowledge, and flcill, to watch 
 and attend to the flock which he purchafed upon the 
 crofs, and to give rell to thofe who are under the bur- 
 den of iiu and forrow. It hatli plcaftd God to call 
 jue to the n:iiililry in very troublefome iimes indeed, 
 ■when a lion and a bear have broken into tlie fold, and 
 are making havoc among the flieep. With a firm, 
 though humble confidence, do I purpofe to go forth ; 
 not in my own ftrength, b\it in the (Irength of the Lord 
 God; and may he profper the work of ray hands!" 
 This was in the year 1753, when the pious aMthor was 
 hardly 23 years of age ; and he had not been many 
 monihs in orders, when one of the moft celebrated 
 preachers in the metropolis pronounced, that " George. 
 Home was, without exception, the bell preacher in 
 England." 
 
 In the year I7i;6, he was again involved in contro- 
 verfy. A pamphlet had been publidied at Oxford, 
 fiippofed by Mr Kennicott, who afterwards gained fuch 
 fame as a colleftor of Hebrew mannfcripts, entitled A 
 fi'orJ to the Hulchwfonians, in which Mr Home was 
 perfonally ilrnck at. To this work our author replied 
 in a fmall traft, called --Jn Apology for certain Gentlemen 
 in the Uiiiverpty of Oxford, Afperfed in a late Anonymous 
 Pamphlet ; and whatever may be thought of the quef- 
 ticn at iffue, all men nnift admire the temper with which 
 the apologift conduced himfelf under very great provo- 
 cation. 
 
 But it was not about Hutchinfonlanifm alone that 
 thefe two illuftrious men were doomed to ditfer. Mr 
 Home took a decided part againft Mr Kennicott 's pro- 
 pofal for collating the text of the Hebrew bible, with 
 fuch manufcripts as could be found, for the purpofe of 
 reforming the text, and preparing it for a new tranflation 
 into the Englidi language; and in the year 1760, he 
 publllhed J Fieiv of Mr Ker.nicott's Method of Cor- 
 reffing the Hebre-ui Text, with three ^leries formed 
 thereon, and humbly fubmitted to the Chrifiian world. 
 That his alarm was on this occafion too great, experi- 
 ence has (hewn ; but that it was not groundlefs, is evi- 
 dent from the View, in which the reader will find a- 
 bove 20 inflances from Mr Kennicott's difTertations 
 (fee Kennicott, Encycl), to (hew what an inunda- 
 tion of licentious criticifra was breaking in upon the 
 facred text. Indeed there is reafon to believe, that this 
 tract, together with another on the fame fide of the 
 queftion by Dr Rutherford of Cambridge, contributed 
 to reprefs the coUeftor's ra(hnefs, and to make the 
 Bible of Dr Kennicott the valuable work which we 
 find it. Be this as it may, fuch was the moderation of 
 the Drs Kennicott and Home, that though their ac- 
 quaintance commenced in hoftility, they at length con- 
 traded for each other a friend(hip, which lailed to the 
 end of their lives, and ftill fubfifts between their fami- 
 lies. 
 
 In what year Mr Home was admitted to the degree 
 of D. D. and when he was chofen prefident of his col- 
 lege, Mr Jones has not informed us ; but, if our me- 
 mory does not deceive us, he had obtained both thefe 
 preferments when, in the year 1772, he gave to the 
 public a fmall work, 8vo, entitled Cortfiderations on the 
 
 I 746 1 
 
 tt O R 
 
 Life and Death of St John the Baplljl. This trafl was 
 the fubllance of a courfe of fernions, which he had^ 
 many years before, in conformity to an eftabli(hed cuf- 
 tdin at Magdalen College, preached before the univerfity 
 of Oxford. -Mr Jones, fpeaking of it, fays, that "he 
 is perfuaded there was no other man of his time, Avhofe 
 (ancy as a writer was bright enough, whofe (kill as an 
 interpreter was deep enough, and whofe heart as a mo- 
 ndift W3S pure enough, to have made him the author of 
 that little work.' By moft readers this ftrain of pa- 
 negyric will be thought extravagant, and of courfe it 
 will defeat its own purpofe ; but the work is cci rainly 
 a work of merit. 
 
 In the year 1776, when the author was vice-chan- 
 cellor, was publi(hed. In two volumes 410, Dr Home's 
 Commentary on the Pfalms. It is a work of which 
 very difiFtrent opinions have been formed, though it was 
 the refult of the labour of twenty years. That it will 
 always be a favourite companion of the devout Cliriftlan, 
 we are as much inclined to believe as ?4r Jones ; but we 
 cannot, without belying our own judgment, fay that it 
 appears to us calculated to produce much general good 
 in an age like the prefent. Granting it to be true, which 
 Ave believe will not be granted without fome exceptions, 
 that Clarke, and Hoadley, and Hare, and Middleton, 
 and Warburton, and Sherlock, and South, and Wil- 
 liam Law, and Edmund Law, had turned the public 
 attention, of which they had got the entire command, 
 too much to the letter of the Bible to the negleft of the 
 Jpirit of it ; fhouid not Dr Home, after the example of 
 St Paul, have let in the light gradually upon fuch weak 
 organs as thofe of the public thus difeaTed, rather than 
 pour it upon them at once in a flood of fplendor. The 
 apoflle " fed his Corinthian converts with milk and not 
 with meat'" when he found them unable to bear the 
 latter food ; and there is reafon to fufpeft that the car- 
 nal followers of Warburton, and Sherlock, and South, 
 were unable to bear, at once, fuch ftrong meat, as that 
 which m?kes the fifteenth pfalm a portrait of our Sa- 
 viour. Indeed, we think it not improbable that the 
 mind of Sherlock would have recoiled with horror from 
 the very conception of tlie poJftbiUly of Jefus Chrift 
 " fwearing to his neighbour and difa])pointIng him," 
 though that conception mull have paffed through a mind 
 which was certainly as pure as his. The commentary, 
 however, though truth thus compels us to fay that, in 
 our opinion, it is far from perfeft, is certainly a work 
 of great learning, great genius, and fervent piety, and 
 fuch as the devout Chrillian will perufe again and again 
 with much advantage. 
 
 Dr Home's next work was of a different kind, and, 
 we think, of a fuperior order. In the year 1776 was 
 publilhed a letter of Dr Adam Smith's, giving an ac- 
 count of the death of Mr David Hume. The objeft of 
 the author was to fliew that Mr Hume, notwithftand- 
 ing his fceptical principles, had died with the utmoft 
 compofure, and that in his life, as well as at his death, 
 he had coudufled himfelf as became one of the wifeft 
 and bed men that ever exifted. The letter is very much 
 laboured, and yet does no honour either to the author or 
 hisfrlend. It could not reprefent Mr Hume as fupporting 
 himfelf under the gradual decay of nature with the hopes 
 of a happy immortality ; but it might have reprefented 
 him as taking refuge, with other infidels, in the eternal 
 fleep of death, This,thoughbutagloomyprofpeft, would 
 
 not 
 
 Home,
 
 H O R [ 747 3 H O R 
 
 lii-mf. not have been childiih ; but the hero of the talc is ex- bury, to whom their reh'gious and poh'ticnl principles Home. 
 
 — Y""" hibited as talking like a fchool-boy of his conferences were well known ; and he continued his affillance after ' '" """ 
 
 with Charon, and his rcluiAance to go into the Stygian he was biihop of Norwich. Indeed the whole bench 
 
 ferry-boat, and as confoling himfelf with the thought (liewed, on this occafion, a zeal for the interells of true 
 
 of leaving all his triends, and his brotlier's family in religion every way becoming their charadler of Chrif- 
 
 particular, in great proiperity ! ! ! The abfurdities of tian bifliops ; and after l)r Home was removed to a 
 
 this letter did not efcape the watchful and penetrating better world, the Scotcli Epifcopalians found among his 
 
 eye of Dr Home ; and as he could not miftake its ob- iui-vivinjj brethren friends as zealous and aftive as he. 
 
 Dr Home, though a very handfome man, was not 
 naturally of a Ilrong conlHuition ; and from the difad- 
 vantage of being uncouiiaonly ncar-fighted, he had not 
 been able to incresfe its ftrength by tlie pra6\ice of any 
 
 jedl, he held it up to the contempt and fcorn of the re. 
 ligious world in A Letter to Adam Smith, L. L, D. on 
 the Life, Death, and Philofophy of his Friend David 
 Hume, £fq; bj one of the People called Chriflians. The 
 
 rcafoning of this little traft is clear and conclufive, while athletic exercife. The only aniufcment in which he 
 its keen, though good humoured wit is inimitable ; and took delight was agreeable converfation ; and his life 
 it was, fome years afterwards, followed by a feries of was therefove what is called fedentary. The confe- 
 Letters on Lifidelity, compofed on the fame plan, and quence of this was, that the iniirmities of age came fall 
 with much of the fame ipirit. This fniall volume, to upon him ; and when the dcfign was formed of making 
 the fecond edition of which the letter to Dr Smith was him a bifliop, he felt himfelf little inclined lo undert'ike 
 prefixed, is better calculated than alinoll any other with the charge of fo weighty an office. He was, however, 
 which we are acquainted, to giiaid the minds of youth prevailed upon t(< accept of the fee of Norwich ; but he 
 againrt the inlidious Itrokcs ot infidel ridicule, tiie only enjoyed his new dignity for a very fiiort period, if he 
 dangerous weapon which iafuielity has to wield. can with truth be faid to have enjoyed it at all. Hlsi 
 When the letters on infidelity were publi(hed, their health declined rapidly; and, in the autumn of 1791, 
 author had for fome time been Dean of Canterbury, he fufierid, while on the road from Norwich to Batli, 
 whire he was beloved by the chapter and almoll adored a paralytic llroke, tlie efFefts of which lie never reco- 
 by the citizens. He was a very frequent preacher in vered. He lingered a month or two, with fuch appa- 
 the cathedral and raeiropohtieal cliurcii, whtre the rent changes in the Hate of his health as fometimes gave 
 writer of this fhort llcetch has lillcned to him with de- delnfive hopes to his family, till the 17th of January 
 light, and leen thoulands ot people of very various de- '79^. when he died in the 62d year of his age, with 
 fcriptions bang with rapture on his lips. As a preacher thofe hopes wliich can be excited only by the confciouf- 
 indeed he excelled ; and notwithftanding the ihortiicfs nefs of a well fpent life, and by a firm truit in the pro- 
 of his fight, which deprived him of fome of the graces of mifes of the gofpcl. 
 
 a pulpit orator, fuch were the excellence of his matter. In this (hort Ikelch of the life of bifliop Home we 
 
 the fimple elegance of his Ityle, and the fwectnefs of have taken the liberty to cxprefs our diilent from fome 
 
 his voice, tliat, when at the primary vifitation ot the pre- ot his opinions, and to Hate the reafons on which that 
 
 fent arclibilhop, he preached his admirable fermon on the difient refts. By himielf we know that this part of our 
 
 Duty of Contending for the Faith, the attention of more condudl would have been applauded; but it is poffible 
 
 than 2000 people was fo completely fixed, that the that by fome of his friends it may be deemed difrefpect- 
 
 fmalleft: noife was not to be heard through the whole ful to his memory. To thefe gentlemen we beg leave 
 
 crowded choir. Of the importance of preaching, and to obferve, that if Johnfon made the praife of Kyrly 
 
 of the proper mode of performing that duty, he had Pope's Man of Rofs, really more folid by making it 
 
 very juft notions ; and though he never had himfelf a more credible, it will be diflicult to perfuade us that we 
 
 parociiial cure of fouls, it was the defire and pleafure of have done any injury to Dr Home's fame by avoiding 
 
 his life to make himfelf ufeful in the pulpit wherever he the extravagant panegyric of thofe who feem to have 
 
 was, whether in town or in the moft, oblcure corner of confidered him as a man exempted from error. He 
 
 the country. Four or five volumes of his fermons have was firft induced to favour the Hutchinfonians hecaufe 
 
 been publllhed fince his death. he thought he perceived danger to religion in the New- 
 
 In the year 1787 he publifhed, under the name of an tonian doctrines of attradlion and repulfion ; and we very 
 
 undergraduate ot the univerfity of Oxford, a letter to Dr readily admit that many Newtonians, not underllanding 
 
 Prieftiey, in which he made that oracle of Socinianifin the dodfrines of their mailer, have expreffed themfeWes 
 
 almoll as ridiculous as, in the letter to Dr Smith, he in fuch a manner as could not render a religious man 
 
 had formerly made the hero of modern fcepticifm. partial to their fyftem. But from the dangers of mif- 
 
 The merits of Dr Home, which had made him pre- take, no fyftem, whether religious or philotophical, was 
 
 fident of Magdalen College, a king's ciiaplain, and dean ever free ; and the atheillical purpofes which the agency 
 
 of Canterbury, railed iiim, we think, in. the year 1790, of ethers and cclcilial fluids has lately been made to 
 
 to the fee ot Norwich ; and he had foon an upportuni- ferve, muft induce every man of piety to paufe before 
 
 ty of ihewing that he had not loll fight of his fpiritual he admit fuch agency. Dr Home lived to witnefs fome 
 
 character in the fplendour of the peer of parliament, of its pernicious effefts ; and we have rcafon to believe 
 
 The Scotch Epifcopalians had for fojne time been foil- that they made a due imprelfion on .his mind ; but he 
 
 citing the legillature to repeal certain penal laws of un- fpent his latter years, as indeed he had fpent the greater 
 
 common feverity, under wliicli they had groaned for part of his life, in nobler purfi;its tlian the ftudy of hu- 
 
 * See upwards of forty years ; but they found it a work of man fcience ; he fpent them in the proper employments 
 
 Scotch no little diHiculty to make the equity of tlicir claim ge- of a Chrillian, a clergyman, and a billiop. lis faith 
 
 kpiscoPA- nerally underllood*. In removing this difficulty no man was founded on a rock : and it was that Pennine faith 
 
 J.IANSII1 ' „. ,. . I IV r ,, 11 1 I , , r 1 , ■ '' 
 
 this ^iipfle 
 
 was more aflitUng to them than the Dean of Canter- 
 
 which workcth by love ; for 
 5^i 
 
 thous 
 
 his pteierments 
 were
 
 H O R 
 
 [ 748 ] 
 
 H O U 
 
 Horogra- were rich, his charity kept pace with them ; and it and one horn ; let another hold his tongue faft in one Houelitom 
 
 has been proved that, notwithftanding his proper ceo 
 nomy, he hoarded not one (liilling of his annual in- 
 come. This was an elevation of chara^ner above all li. 
 tcrary, above all philofophleal fame. The author of 
 this article had tht honour to be known to Dr Home, 
 to enjoy, if he miftook not, a (liare in his friendfhip; 
 
 hand, putting the cane down his throat with the other. 
 Be cartful not to let the animal get the knob of the cane 
 between his grinders : obferve alfo to put the cane far 
 enough down ; the whole length will not injure. You 
 will find the obllacle at the entrance of the paunch : 
 pufh the cane hard, and when you perceive a fmell to 
 
 and to correfpond with him regularly for many years ; come from the paunch, and the animal's body to fink, 
 
 and there is not one of his rational admirers who more 
 fully admits the truth of the charadlcr given of him by 
 Dr Thurlow late bifhop of Durham when fucceeding 
 him in the office of proftor in the Univerfity. " As to 
 the laft proftor (fald he) I fhall fpeak of him but in few 
 words, for the truth of which I can appeal to all that 
 are here prefent. If ever virtue itfelf was vifible and 
 dwelt upon earth, it was in the perfon who this day 
 lays down his office." 
 
 Soon after he was advanced to the prefidentihip of 
 
 the cure is performed, and Nature will aft for itfelf." 
 
 This method, we doubt not, will prove fuccefsful ; 
 but might not the purpofe be as well, if not better, ef- 
 fefted, by uhng, inllead of the cane and knob, a piece 
 of thick lliff rope, which, in many places of Scotland, 
 is employed to force down turnips or potatoes when 
 they ftick in the throat of a bullock ? 
 
 HOUGHTON ( — ) is a man to whom the 
 
 fcience of geography is fo much indebted, that we are 
 almoft aftianied to confefs that we know not his Chrif- 
 
 Magdalen college, this great and good man married the tian name, the place where he was born, or the age at 
 
 only daughter of Philip Burton, Efq; a gentleman of which he died. He had been a captain in the 6Qth re- 
 
 confiderable fortune. By this lady he had three daugh- giment, and in the year 1779 had acled under General 
 
 ters, of whom the eldeft was married to a clergyinan a Rooke as fort-major in -the ifland of Goree. Hearing, 
 
 fliort time before the death of her father, and the two fome time in the year 1789, or perhaps earlier, that the 
 
 younger were, in 1796, refiding with Mrs Home in African affociation wilhed to penetrate to the Niger by 
 
 Hertfordfhire. the way of Gambia, he expreifed his willingnefs to un- 
 
 HOROGRAPHY, the art of making or conflruft- dertake the execution of their plan. For this tafli he 
 
 ing dials ; called alfo dialing, horologiography, gnomo- was peculiarly fitted. A natural intrepidity of charac- 
 
 liica, fciatherica, photofciatherica. Sec. ter which feemed inaccelllble to fear, and an cafy Row 
 
 HOROPTER, in optics, is a right line drawn of conftitutional good humour, which even the roughed 
 
 through the point where the two optic axes meet, pa- accidents of life were not able to fubdue, formed him 
 
 rallel to that which joins the centres of the two eyes, for exploring the country of relentlefs favages ; whilft 
 
 or the two pupils 
 
 HORSE-Shoe, in fortification, is a work fometimes 
 of a round, fometimes of an oval figure, inclofed with a 
 parapet, raifed in the ditch of a marrtiy place, or in low 
 grounds ; fometimes alfo to cover a gate ; or to ferve as 
 a lodgment for foldiers, to prevent furpriles, or relieve 
 an over-tedious defence. 
 
 HOVEN is a word of the fame import with raj- 
 fedjfivellc-d, tumefied. It is particularly applied to black 
 cattle and flieep, when from eating too voracioufly of 
 clover, or any other fucculent food, they become fwol- 
 len. Such cattle are, in the language of the farmer, 
 called 
 
 HogEN-Cattle ; and the beaft, whether bullock or 
 flieep, which is huven, when left without relief, dies in 
 half an hour. The caufe of the difeafe is the extra- 
 quantity of air taken down with that kind of food, 
 which, in its paffage from the paunch upwards, forces 
 the broad leaves of the clover before it, till they clofe 
 
 the darknefs of his complexion was fuch, that he fcarce- 
 ly differed in appearance from the Moors of Barbary,. 
 whofe drefs in travelling he intended to affume. 
 
 His inftruftions from the affocintion were, to afcer- 
 tain the courfe, and, if pofiible, the rife and termination 
 of the Niger; and after vifiting the cities of Tombuc- 
 Too andHoussA (fee thefe articles in this Supplement), 
 to return by the way of the defart, or by any other 
 route which the circumftances of his fituation at the 
 time might recommend to his choice. 
 
 Having left England on the 16th of Oflober 1790, 
 he arrived at the entrance of the Gambia on the 10th 
 of November, and was kindly received by the king of 
 Barra, who remembered the vifit which the major had proceeJingf, 
 formerly paid him from the ifland of Goree ; and vihooftbe Afri'- 
 now, in return for a fmall prefent of the value of 20s. '^7" ^ff"''"^ 
 cheerfully tendered j^teAion and affiftance as far as'"""' 
 his dominion or influence extended. 
 
 An offer from the mailer of an Englifh vefTel em- 
 
 up the paffage at the entrance of the paunch, and pre- ployed in the trade of the river, enabled the Major, and 
 
 vent the wind from going upwards in its regular courfe 
 The ufual method of rehef is to flab the animal in the 
 paunch ; an operation which is always dangerous, and 
 has often proved fatal. It was therefore, with good 
 reafon, that the Society for the Encouragement of Arts, 
 Manufactures, and Commerce, voted a bounty of fifty 
 guineas to'Mr Richard Eagar of Graflham farm, near 
 
 the interpreter he had engaged on the coail, to proceed 
 to Junkiconda ; where he purchafed from the natives a 
 hcrfe and live alTes, and prepared to pafs with the mer- 
 chandife which conftitutcd his travelling fund, to Me- 
 dina, the capital of the fmall kingdom of Woolli. 
 
 Fortunately for him, a few words, accidentally drop- 
 ped by a negro woman in the Mandingo language, of 
 
 Guildford^ for making public a very fimple method which he had hallily acquired a fuperficial knowledge, . 
 
 praftifed by him for the cure of hovfn-cattle. It is excited fufpicions of danger; and gave him intimation 
 
 this; " let the grazier or farmer have always ready of a confpiracy which the negro millrefl'es of the tra- 
 
 fmooth knobs of wood, of different fizes, fixed to the ders, who feared that the Major's expedition portended 
 
 end of a flexible cane, which for oxen (liould be at leaft the ruin of their commerce, had formed againll his life, 
 
 fix feet long, and for (heep three feet. When a beaft Afraid, therefore, of travelling by the cuitomary route, 
 
 k hoven, let one perfon take hold of him by the noftril lie availed himfelf of the opportunity wliich the dry fea. 
 
 foD
 
 H O U 
 
 [ 7 
 
 KoiigJiKri' fon and the tide of clil) afforded of fwimming liis horfe 
 ^- /~~" apid his afffs acrofs the ftream ; and having by thofe 
 means avoiJid the parties who were fent for liis dcftruc- 
 tlon, he proceeded with much difficulty on the fouthern 
 fide of the river, to that dittrift of Cantor which is op- 
 pofite to the kingdom of Woolh'. There he repiiffed 
 the Gambia, and fet a meffenger to inform the king 
 of his arrival, and to requell a guard for his proteftion. 
 An cfcort, commanded by the king's fon, was imme- 
 diately difpatchrtd ; and the Major, whofe intended pre- 
 fent had been announced, was kindly received, and hol- 
 j>itably entertained at Medina. 
 
 The town is funated at the diftance of about 900 
 miles by water from the entrance of the Gambia ; and 
 the country adjacent abounds in corn and cattle, and, 
 generally fpeaking, in ail things that are renuifite for 
 , the fupport, or eflential to the comfort of life. Two 
 different fefls of religion dilUnguifh rather than divide 
 the people; the one is compoltd of the profeffors of the 
 Mahomedan faith, who are called Bulhreens; the other, 
 and, it is faid, the more numerous, con'ills of thole 
 who, denying the miffion of the prophet, avow theni- 
 felves deiils, and from their cuftom of drinking with 
 freedom the liquors of vvliieh he prohibited the u!e, are 
 denominated Sonikees or drinking men. 
 
 In a letter from Major Houghton to his wife, which 
 a feaman preferved from the wreck of a veflel in which 
 the difpatches to the fociety were loft, the Major in- 
 dulged the refleftions that naturally arofe from his pad 
 and prefent fituations. A bilious fever had attacked 
 him foon after his arrival in the Gambia; but his health 
 was now unimpaired — a confpiracy had affailed his life ; 
 but the danger was paffcd — the journey from Junki- 
 conda had expofed him to innumerable hardfliips ; but 
 he was now in poffelTion of every gratihcation which 
 the kindnefs of the king or the hofpitality of the people 
 could enable him to enjoy. Delighted with the healthi- 
 nefs of the country, the abundance of the game, the fe- 
 curity with wjiich lie made his excurfions on horfeback, 
 and, above all, with the advantages that would attend 
 the erection of a fort on the falubrious and beautiful 
 • hill of Fatetenda, where the Engliih once had a fattory, 
 he exprcffes his carneil hope that his wife will hereafter 
 accompany him to a place in which an income of ten 
 pounds a-ycar will fupport them in affluence ; and that 
 (he will participate with him in the pleafure of rajn'dly 
 acquiring that vail wealth which he imagines its com- 
 merce will afford. 
 
 While, in this manner, jie indulged the dream of fu- 
 ture profperity, and with ftill more ample fatisfatfion 
 contemplated the eclat of the difcoveries for which he 
 was preparing, but in tlie purfuit of which he was re- 
 tarded by the abfence of the native merchant, for 
 whofe company he had engaged, he found himfelf fud- 
 denly involved in unexpefted and irrefillible misfortune. 
 A fire, the progrefs of which was accelerated by the 
 bamboo roofs of the buildings, confumed with fuch ra- 
 pidity the houfe in which he lived, and with it the 
 greateft part of Medina, that feveral of the articles of 
 merchandize, to which he trufted for the expences of 
 his journey, were deflroyed ; and to add to his afflic- 
 tion, his faithlefs interpreter, who had made an ineffec- 
 tual attempt on his goods, difappeared with his horfe 
 and three of his affes ; a trade gun which he had pur- 
 chafed on the river foon afterwards burll in his hands, 
 
 49 ] H O U 
 
 and wounded hiii in the face and arm : and though theHr.ughton. 
 hofpitable kindnefs of the people of the neighbouring ■~~V ■■' 
 town of Banaconda, who cheerfully opened their 
 houfes to more than a thoufand families, whofe tene- 
 ments the flames had confumed, was anxioiifly exerted 
 for his relief; yet the lofs of his goods, and the confe- 
 qutnt diminution of his travelling fund, were evils 
 which no kindnefs could remove. 
 
 It was in this iituation that, wearied with the fruit- 
 lefs hope of the return of the native trader, with whom 
 he had contrafted for his j(j\irney, he refolved to avail 
 himfelf of the company of another flave merchant, who 
 was lately arrived from the fouth, and was now on hi* 
 way to his farm on the frontier of the kingdom of 
 Bambouk. Accordingly, on the evening of the 8th 
 of May, he proceeded by moon light and on foot, with 
 his two affes, which the lervants of the flave merchant 
 oSered to drive with their own, aid which carried the 
 wreck of his fortune ; and journeying by a north-cad 
 courfe, arrived on the lifih day at the uninhabited fron- 
 tier which feparates the kingdoms of Woolli and Bon- 
 dou. 
 
 He had now paffed the former limit of European 
 difcovery ; and while he remarked with pleafure the 
 numerous and extenfive population of this unvifited 
 country, he obferved, that the long black hair and 
 copper complexion of the inhabitants announced their 
 Arab original. They are a branch of that numerous 
 tribe which, under the ap])ellation of Foolies, have over- 
 fpread a confiderable part of Senegambia ; and theit* 
 religious diftinftions are fimilar to thofe which prevaiL 
 in the kingdom of Woolli. 
 
 A journey of 150 miles, which was often interrupt- 
 ed by tlie engagements of his companion who traded 
 in every town, conduclcd him to the banks of the Fa. 
 Icme, the fouth-weftern foundary of the kingdom of 
 Bambouk. Its ftream was exhaufted by the advanced 
 ftate of the dry ftafon, and its bed exhibited an ap- 
 pearance of flate intermixed with gravel. 
 
 Bambouk is inhabited by a nation, whofe woclly 
 hair and fable complexions bcf])cak them of the negro 
 race, but whofe character feems to be varied in proper, 
 tion as the country rifes from the plains of its wcllern 
 divifion to the highlands of the eaft. Diftinguilhed 
 into feAs, like the people of Woolli and Bondou, by 
 the different tenets of Mahumedans and Deifts, they 
 are equally at peace with each other, and mutually to- 
 lerate the refpedtive opinions they condemn. 
 
 Agriculture and pafturage, as in the negro ftates. 
 on the- coaft of »the Atlantic, are their chief occupa- 
 tions; but the progreis which they have made in the ma- 
 nufacturing arts, is fuch as enables them to fmelt their 
 iron ore, and to furnifti the feveral inftruments of huf- 
 bandry and war. Cloth of cotton, on the other hand, 
 which in this part of Africa feems to be the univerfal 
 wear, they appear to weave by a difficult and laborious 
 procefs ; and to thefe two circumllanccs it is probably 
 owing, that with them the meafnre of value is not, as 
 on the coaft, a bar of iron, but a piece of cloth. 
 
 The common vegetable food of the irdiabitants ap- 
 pears to confift of rice ; their animal, of beef or mut- 
 ton. A liquor, prepared from fomented honey, fup- 
 plies the want of wine, and furnifhes the means of thofe. 
 feftive entertainments that conftitute the luxury of the 
 court of Bambouk. 
 
 Qn.
 
 H O U [ 75 
 
 H.uij 'ticnn. On tlu- Major's arrival at the banks of the river Fa- 
 * letr.c, he found that the war which had lately fubfiftcd 
 betweirti the kings of Bundoii and Banibouk was tcr- 
 ininatcd by the ct-flion to the former of the conqucibs 
 Jic hail made in the low land part of the dominions of 
 the latter ; and that the king of Bondou had taken up 
 his rcfidcnce in the territory which he had thus ob- 
 tained. 
 
 The Major haftened to pay his refpc£ls to the vic- 
 torions prince, and to offer a iimilar prcfent to that 
 which the kings of Barra and Woolli had cheerfully 
 accepted ; but to his great difappointment an ungra- 
 cious reception, a fullen permiffion to Iea%'e the prefent, 
 and a ftern command to repair to the frontier town 
 from which he came, were followed by an intimation 
 that he (houhi hear again from the king. According- 
 ly, on the next day, the king's fon, accompanied by an 
 armed attendance, entered the houfe in which the Ma- 
 jor had taken up his temporary dwelling, and demand- 
 ed a fight of all the articles he had brought. From 
 thcfc the prince felefted whatever conmiodities w^re 
 beft calculated to gratify his avarice, or pleafe his eye ; 
 ;md, to the Major's great difappointment, took from 
 him the blue coat in which he hoped to make his ap- 
 pearance on the day of his introduction to the Sultan 
 <){ Tombuftoo. Happily, however, a variety of ar- 
 ticles were fuccefsfuUy concealed, and others of inferior 
 value were not confidered as fufficiently attraftive. 
 
 The Major now waited with impatience for the per- 
 formance of the promife which the flave merchant, with 
 whom he had travelled from the Gambia, had made of 
 proceeding with him to Tombuftoo ; but as the mei"- 
 cliant was obliged to fpcnd a few days at his rice farm 
 on the banks of the Falenie, the Major accepted an in- 
 vitation to the hofpitality of his roof. There he ob- 
 ferved, with extreme regret, that the apprehenfion of a 
 fcarcity of grain had alarmed his friend ; and that, 
 dreading the confequences of leaving his family in fo 
 perilous a feafon to the chances of the market, he had 
 iJetermined on collefting, before his departure, a fuf- 
 (icient fupply for their fnpport. This argument for 
 delay was too forcible to be oppofed ; and therefore 
 the Major refoived to employ the interval in vifiting 
 the king of Bambouk, who rcfided in the town of Fer- 
 banna, on the eaftcm fide of the Serra Coles, or river of 
 Gold. Unfortunately, however, by a miltake of his 
 guide, he loft his way in one of the vaft woods of the 
 country ; and asj;he rainy feafon, which commenced 
 with the new moon on the 4th of July, and was intro-* 
 duced with awellerly wind, was now fet in, the ground 
 on which he paffed the night was deluged with rain, 
 while all the llcy exhibited that continued blaze of 
 lightning, which in thofe latitudes often accompanies 
 tiie tornado. Diftreffed by the fever, wliich began to 
 affail him, the Major continued his route at the break 
 of day, and waded with difficulty through the river 
 Serra Coles, which was fwelled by the floods, and 
 on the banks of which the alligators were baf]<ing in 
 the temporary fun-{hine. 
 
 Scarcely had he reached Ferbanna when his fever 
 rofe to a height that rendered him delirious ; but the 
 (Irength of his conftitution, and the kindnefs of the ne- 
 gro family to which his guide had condufted him, fur- 
 mounted the dangerous difeafe ; and in the friendly re- 
 ception which was given him y the king of Banibouk 
 
 50 '] 
 
 H O U 
 
 he foon forgot the hardfhips of his journey. The king Hout;IitP», 
 informed him, that the loH'cs he had lately fuftained in'~*~v— ' 
 tlic contefl with the armies of Bondou, aroie from his 
 liaving exhaulled his ammunition ; for, as the French 
 traders, who iormerly kipplied his troops, had aban- 
 doned the fort of St Joleph, and, either from the diy- 
 nels of the lail feafon, or trom other caufcs, had defert- 
 ed the navigation of the upper part of the Senegal, he 
 had no means of repienifliing his I'ores ; whereas his e- 
 nemy, the king of Bondou, continued to receive from 
 the Dritin-., through the channel of his agents on the 
 Gambia, a conftant and adequate fupply. 
 
 Major Houghton availed himfelf of the opportunity 
 which this coifverlatlon afforded, to (uggell to the 
 king the advantage of encouraging the Britilh to open 
 a trade by the way of his dominions to the popidotis 
 cities on the banks of the Niger. 
 
 Such was the ftatc of the negociation, when all bufi- 
 nefs was fufpended by the arrival of the annual prefeuts 
 of Mead, which the people of Bambouk, at that feafou 
 of the year, are accuftomed to fend to their king; and 
 which are always followed by an intemperate fellival of 
 feveral fucceffive days. 
 
 In the interim, the Major received, and gladly ac- 
 cepted, the propofal of an old and refpeftable merchant 
 of Bambouk ; who offered to condnft him on horfe- 
 back to TombuAoo, and to attend him back to the 
 Gambia. A premium of L. 125, to be paid on the 
 Major's return to the Britifli faftory at Junkiconda, 
 was fixed by agreement as the merchant's future re. 
 ward. It was further determined that the Major 
 fliould be furniflied with a horfe in exchange for his 
 two affes ; and (liould convert into gold dull, as the 
 mod portable fund, the Icanty remains of the goods he 
 had brought from Gicat Biitaiu. 
 
 This plan was much approved by the king, to whona 
 the merchant was perlonally known; and who gave to the 
 Major at parting, as a mark of his tfteem, and a pledge 
 of his future friendlhip, a prefent of a purfe of gold. 
 With an account ofthcfe preparations the Major clofed 
 his laft difpatch, of the 24th July 1791 ; and the A- 
 frican alTuciation entertained for fome time fanguine • 
 hopes of his reaching TombuiSoo. Alas ! thefe hopes 
 were blafted. Mr Park, who fucceeded him in the ar- 
 duous talk of exploring^ that favage country, learned, 
 that having reached Jarra (See that article in this 
 Supplement), he there met with fome Moors who were 
 travelling to Tilheet (a place by the fait pits in the 
 Great Defart, ten days jougiey to the northward^ to 
 purchafe fait ; and that the Major, at the expence of 
 fome tobacco and a mufl<et, engaged them to convey 
 him hither. It is impoHible {fays Mr Park) to form 
 any other opinion on this determination, than that the 
 Moors intentionally deceived him with a view to rob, 
 and leave him in the Defart. At the end of two days 
 he fufpedled their treachery, and infilled on returning 
 to Jarra. Finding him perfill in this determination, 
 the Moors robbed him of every thing which he pofTeis- 
 fd, and went off with their camels. Being thus defert- 
 ed, he returned to a watering place, in polfcirion of the 
 Moors, called Farra ; and being by thefe unfeehng 
 wretches refufed food, which he had not tailed for iome 
 days, he funk at lall under his mistortunes. Whether 
 he aftually died of hunger, or was murdered uutright 
 by the favage Mahometans, Mr Park could uot learn ; 
 
 but
 
 H O U . [ 75 
 
 Houffa. but lie was fhevvn at a diftance the fpot in the woods 
 ^~~N to which his body was dragged, and where it was left 
 a prey to corruption. 
 
 Thus perillied, in the prime of h'fe, Major Houghton, 
 Z man whofe travels enlarged the limits of European 
 difcovery, and whufe accounts of the places which he 
 ■vilited were llrongly confirmed by the intelligence whicli 
 the Britifli coiiful at Tunis coUeifled from the Barbary 
 merchants. 
 
 HOUSSA, the capital of an African empire, on tlie 
 banks of tlie Niger, is a city which has excited mucii 
 ruriofity among men of fcience, fmce it was firft men- 
 tioned to a committee of the African Affociation about 
 the year 179c. The perfon from whom they received 
 their information was an Arab, of the name of Shabeiii ; 
 who faid that the population of Houlfa, where he had 
 jefided two years, was equalled only (fo far as his know- 
 ledge extended) by that of London and Cairo: and, 
 in his rude unlettered way, he defcribed the govern- 
 ment as monarchical, yet not unlimited ; itsjufticeas 
 fevere, but direfted by written laws ; and the rights of 
 landed property as guarded by the inftitutions of cer- 
 tain hereditary ofScers, whofe funftions appear to be fi- 
 milar to thofe of the Canongoes of Hindoftan (fee Ca- 
 >J0NG0ES inthh Svf pi.); and whofe important and com- 
 plicated duties imply an unufual degree of civilization 
 and refinement. For the probity of the merchants of 
 Houffa, the Arab exprefled the higheft refpeft ; but re- 
 marked, with indignation, that the women were admit- 
 ted to fociety, and that the honour of the hufoand was 
 often infecure. Of their written alphabet, he knew no 
 more than that it is perfectly different from the Arabic 
 and the Hebrew charafters ; but he reprefented the art 
 fif writing as common in Houffa. And when he de- 
 fcribed the manner in which their pottery is made, he 
 gave, unknowingly to himfelf, a reprefentatlon of the 
 ancient Grecian wheel. In paffmg to Houffa fiom 
 Tombuftoo, in which laft city he had refided feven 
 years, he found the banks of the Niger more numerouf- 
 Iv peopled than thofe of the Nile, from Alexandria to 
 Cairo; and his mind was obvioudy impreffed with higher 
 ideas of the wealth and grandeur of the empire of 
 Houffa, than of thofe of any kingdom which he had 
 feeii, England alone excepted. 
 
 The exirtence of the city of Houffa, and of the em- 
 pire thus defcribed by Sbabeni, was ftrongly confirmed 
 by letters which the committee received from his Majef- 
 ty's confuls at Tunis and Morocco ; and it has been 
 put beyond all poffibility of doubt by Mr Park, who re- 
 ceived from various perfons fuch concurring accounts of 
 it, as could not be the offspring of deliberate falfehood. 
 From a well-informed ffiereeff, who had vifited Houffa, 
 and lived fome years at Tombuftoo, he learned that the 
 former of thefc cities was the largeft that the fiiereeff had 
 ever feen ; and by comparing this man's account of its 
 population with that of various other cities, of which 
 Mr Park had feen one or two, we can hardly efli- 
 mate the inhabitants of Houffa at a lefs number than 
 JOO,oco. Many merchants, with whom our traveller 
 eonverfed, reprefented Houffa as larger, and more po- 
 pulous, than Tombuftoo, and the trade, police, and 
 government, as nearly the fame in both. In that cafe, 
 the king of Houffa and chief officers of Aate muff be 
 Moors, and zealots for the Mahometan religion ; but 
 they cannot be fo intolerant as the fovercign of Tom- 
 
 I ] H O U 
 
 buAuo and his minifters ; for in Houff;i, Mr Park was 
 told that the Negroes are in greater proportion to the 
 Moors than in Tombuftoo, and that they have like- 1 
 wife U)me Ihare in the government. According to ac- 
 counts derived from Barbary merchants, the people of 
 Houffa have the art of tempering their iron with more 
 than Eiu'opean {kill; and their files, in particular, arc 
 much fuperior to thofe of Great Britain and France. 
 The confuls at Tunis and Morocco affured the com- 
 mittee of the African Affociation, that at botli thefe 
 courts the eunuchs of the feraglio are brought from 
 Houffa. 
 
 To thofe who may ftill entertain doubts of fo much 
 refinement being to be found in the interior parts of a 
 country, confidered as peculiarly fnvage, we (hall only 
 obferve, in the woids of the committee of affociation, 
 that it is by no means " impoffible that the Carthagi- 
 nians, who do not appear to have perifhed with their 
 cities, may have retired to the foulhcrn parts of Afri- 
 ca ; and though loft to the Uefart, may have carried 
 with them to the new regions which they occupy fomt- 
 portion of thofe arts and fciences, and of that commer- 
 cial knowledge, for which the inhabitants of Carthage 
 were once fo eminently famed. In Major Rennel'slall 
 map of North Africa, Houffa is placed in l6'- and about 
 20' N. Lat. and 4" 30' E. Long. 
 
 HOUZOUANAS, are a wandering people, wlio 
 inhabit that part of Africa, which, in a direftion from 
 eall to weft, extends from Caffraria to the country of 
 the Greater Nimiquas (See Nimiqjjas in this Suppl.) 
 According to the map prefixed to Vaillant's new 
 travels, the diftritt occupied by the Houzouanas lies 
 between 16" and 29° eaft longitude. Of Its breadth 
 from fouth to north we are ignorant, but it begins at 
 the 23d parallel, aud ftretches northward piubably a 
 great way. 
 
 M. Vaillant is Inclined to believe, that the Houzoua- 
 nas are the original Hem of the various nations, inhablt- 
 ing at prefent the fouthern part of Africa, and that 
 from them all the tribes of the eaftern and weftern 
 Hottentots are defcended. The people themfelves know 
 nothing of their origin ; but to the queftions that are 
 put to them on the fubjeft, they always reply, th?t 
 they inliabit the country which was inhabited by their 
 anceftors. At the Cape M. Vaillant reccired the fol- 
 lowing account of them, which, though he does not 
 warrant its authenticity, has much the appearance of 
 being authentic. 
 
 When the Europeans firft eftabliflied themfelves at 
 the Cape, the Houzouanas inhabited the country of 
 Camdebo, the fuovvy mountains, and the diftrift that 
 feparates thefe mountains from Caffraria. Become 
 neiglibours to the colony, in confequence of its extend- 
 ing itfelf towards them, they at firft lived on peaceable 
 terms with the planters ; and, as they difplaycd more 
 intelh'gence and greater aftivity than the Hottentots, 
 they were even employed In preference to affift in culti- 
 vating the land and in forming the fettlement. This good 
 underllanding and harmony were, however, foon inter- 
 rupted by that multitude of lawlefs banditti fent from 
 Holland to people the country. 
 
 Thofe worthlefs profligates wifhed to enjoy the fruit* 
 of the land without the trouble of tilling it. Educa. 
 ted, befides, with all the prejudices of the whiles, they 
 imagined that men of s diflctcat colour were boru only 
 
 to 
 
 Houflb, 
 Huuzou. 
 
 anas. 
 /-—'
 
 H O U [ y 
 
 to he tlieir flavea. They accoidingly fubji.£lcd them 
 to bondage, condemned tlicm to the moft laborious fev- 
 " vices, and repaid tl)ofe ferviccs with harlh and fevere 
 treatment. The Houzouanas, inccnfed at fuch arbitra- 
 ry aiul tyrannical conduit, refiifed any longer to work 
 for them, and letlred to the dcldes of their mountains. 
 The planters took up arms and purfued them ; they 
 malfacred them without pity, and feized on their cnttle 
 and their country. Thofe who efcaped their atrocities 
 betook themfelves to fliglit, and removed to the land 
 which they now occupy ; but, on quitting their former 
 polfcflions, they fwore, in their own name and that of 
 their pollerity, to exterminate thofe European monflers, 
 to be revenged againft whom they had fo many incite- 
 ments. And thus, if tradition be true, was a peaceful 
 and induftrious nation rendered warlike, vindictive, and 
 ferocious. 
 
 This hatred has been perpetuated from generation to 
 generation, though the Houzouanas of the prefent day 
 are ignorant of the original caufe of it. Bred up with 
 an invincible avedion to the planters, they know only 
 that they are animated to plunder and deftroy them ; 
 but it is only by a vague fentiment of deteftation, with 
 the fource of wliich they are unacquainted; and which, 
 though it renders them cruel towards the planters, does 
 not prevent them from btiBg good, kind, and humane, 
 towards each other. 
 
 The Houzouanas, being known only by their incur- 
 fions and plundering, are in the colonies often confound- 
 ed with the Bofhmtn, and dillinguilhcd by the lame ap- 
 pellation. Sometimes, however, from their tawny co- 
 lour, they are called Chincfe Hottentots; and, by means 
 of this double denomination, ill informed travellers may 
 cafily be led into an error, of which the conlequence 
 mull be, that their narratives will be replete with ab- 
 furdity and falfehoods. 
 
 Their real name, and the only one which they give 
 themfelves, is that of Honzouana ; and they have no- 
 thing in common with the Boftimen, who are not a 
 diftindl people, but a mere coUeAion of fugitives and 
 free-booters. The Houzouanas form no alliances but 
 among themfelves. Being almoft aUvays at war with 
 the furrounding nations, they never mix with them ; 
 and, if they confent at any time to admit a ftranger in- 
 to their hordes, it is only after a long acquaintance, a 
 fort of apprenticelhip, during which he has given proofs 
 of his fidelity, and etlablilhed his courage. Such in- 
 deed are their courage and predatory habits, that they 
 are the dread of all the furrounding tribes ; and the 
 Hottentots who accompanied M. Vaillant trembled at 
 the very thojght of entering the Houzouana territo- 
 ries. Nay, after they had lived many days among 
 them, and had experienced their iidtlity, they conti- 
 nued under tl-e daily appreheniion of being maffacred 
 by them. Yet one of their own countrymen, who had 
 lived long among the Houzouanas, gave fuch a charac- 
 ter of that people as ihould have banilhtd thofe idle 
 fears. 
 
 " The Houzouanas (faid he), are by no means what 
 you fuppofe them to be, murderers by profefTion. If 
 they foraetimes ihed blood, it is not from a third of 
 carnage, but to make juft reprifals that they take up 
 arms. Attacked and perfecuted by furrounding na- 
 tions, they have found themfelves reduced to the ne- 
 
 ^. ] H O U 
 
 ceffity of flying to inaccefilble places among the b.trrcp nmi7Mv 
 mountains, where no other people could cxiil. , "' ' '*'• ^ 
 
 " If they find antelopes and damans to kill ; if the * 
 nymphs of ants are abundant ■; or if their good fortune 
 brings them plenty of loculls — they remain within the 
 precindts of their rocks ; but if the provifions neceflary 
 to fubfillence fail, the nations in their neighbourhood 
 muft fuffer. From the fummits of their mountains, 
 they furvey at a dillanoe the countries around ; and it 
 they obferve cattle, they make an incurfion to carry 
 them off, or flaughter them upon the fpot, according 
 to circumftances; but though they rob, they never kill, 
 except to defend their lives, or b.y way of retaliation to 
 revenge an anciejit injury. 
 
 " It happens fometimcs, however, that after very fa- 
 tiguing expeditions they return without booty ; either 
 becaufe the objeAs of their attack have ilifippeared, or 
 becaufe they have been repulfed and beaten. In fuch 
 cafes, the women, exafperated by hunger and the la- 
 mentation of their children crying for food, become al- 
 molt furious with paffion. Reproaches, infult, and 
 threats, are employed ; they wifh to feparate from fuch 
 daftardly men, to quit hufbands deftitute of courage, 
 and to- feek others who will be more anxious to pro- 
 cure provifion for them and their children. In fliort, 
 having exhaufted whatever rage and defpair could fug- 
 geft, they pull off their fmall apron of modefly, and beat 
 their hufbands about the head with it till their arms are 
 weary of the exercife. 
 
 '• Of all the affronts which they can offer, this is the 
 motl infulting. Unable to vvithlland it, the men in 
 their turn become furious. They put on their war- 
 cap, a fort of helmet made with the fkin that covers 
 the neck of the hysena, the long hair of which forms a 
 crefl that floats over the head, and fctting out like 
 madmen, never return till they have I'ucceedtd in carry- 
 ing off fome cattle. 
 
 " When they come back, their wives go to meet 
 them, and extol their courage amidfl the fondefl ca- 
 reffes. In a word, nothing is then thought of but 
 mirth and jollity ; and, till fimilar fcents are recalled by 
 fimilar wants, pall evils are forgotten." 
 
 Such was the charafter given of this formidable 
 people to M. Vaillant at his firft interview with them ; 
 and during the long excurfions which he made in their 
 company, they did not belie it in a liugle inllance. In 
 many refpefts they appeared to refemble the Arabs, 
 who, being alfo wanderers, and hke them brave and 
 addidled to rapine, adhere with unalterable lidclity to 
 thtir engagements, and defend, even to the laft drop of 
 their blood, the traveller who civilly piirthales their 
 fervices, and puts himfclf under their proteftion. In 
 our author's opinion, if it be at all prafticable to tra- 
 verfe from fouth to north the whole of Africa, it could 
 only be under the conduft of the Houzouanas ; and he 
 really thinks that fifty men of their temperate, brave, 
 and uidefatigable nation, would be fufficient to protect 
 an enterpriling European through that long and ha- 
 zardous journey. 
 
 Yet thefe people, fo fuperior both in body and mind 
 to the other natives of South Africa, are but of low 
 rtature ; and a perfon five feet four inches in height is 
 accounted among them very tall j but in their little bo- 
 dies, perfedly well proportioned, are united, with fur- 
 
 prifing
 
 H O U [ 753 1 H O U 
 
 prituig llrength and agility, a certain air of afTiirance, Aftive and nimble by nature, the Houzouanae cnn- Hoiiziu- 
 
 boldnefs, and haughtinefs, which awes the beholder, fuler it as aniufement to climb mountains, and the moil " '^*- 
 
 'and with which our author was greatly plealed. Of elevated peaks; and they condutted M. Vaillant, his ^ iT— ' 
 
 all the favage races, he faw none that appeared to be fervants and cattle, over precipices, and thron"h defiles 
 endowed with fo active a mind, and fo hardy a conftitu- which he and his Hottentots would have deemed abfo- 
 tion. lutely impalTable. The only arms of this people arc 
 Their head, though it exhibits the principal charac- bows and arrows, in the nfe of which they are very ex- 
 teriftics of that of the Hottentot, is, however, rounder pert. Tlie arrows, wliich arc uncommonly (liort are 
 towards the chin. They are alfo not fo black in com- carried on tiie ihoulder in a quiver, about i8 inches in 
 plodon ; but have the lead colour cjf the Malays, dif- length, and four in diameter, made of the bark of the 
 tinguifiied at the Cape by the name of boiigtiincf. aloe, and covered with the (kin of a large fpecies of li- 
 Their hair, more woolly, is fo (hort, that he imagined zard, which thtfe wand*:rers find in all their rivers par- 
 at firft their heads to have been fhaved. The nofe too licularly on the banks of Orange and Fi(h River. 
 is dill flatter than that of the Hottentots ; or, rather, Nodurnal fires are a peculiar language underftood 
 they feem altogether deftitute of a nofe ; what they and employed by almoft all favage nations. None how- 
 have conlifting only of two broad nollrils which pro- ever, Inve carried this art fo far as the Houzouana? 
 jeft at mod but five or lix lines. From this confirma- bccanfe none have fo much need of underllandina- and 
 tion of the nofe, a Houzouana, when feen in profile, is bringing it to perfedtion. If it be necefTary to announce 
 the reverfe of handfome, and confiderably refemblei an a defeat or a viftory, an arrival or departure, a fuccefs- 
 ape. When beheld in front, he prefents, on the firil ful plundering expedition, or the Want of ainilance .in 
 view, an extraordinary appearance, as half the face feems a word, any intelligence whatever, they are able, eith'T 
 to be forehead. The features, however, are fo expref- by the number of their fires or tlie maimer in which they 
 five, and the eyes fo large and lively, that, notwith- arrange them, to make it known in an inftant. They 
 ilanding this fingularity of look, the countenance is to- are even fo fagacious as to vary their fires from time to 
 lerably agreeable. time, left their enemies (lionid become acquainted with- 
 As the heat of the climate in which he lives renders their lignals, and treacheroully employ them in their 
 clothing unnecelTary, he continues during the whole turn to furprife them. 
 
 year almoft entirely naked, having no other covering Our aiithor fays, that he is unacquainted wilh the 
 
 than a very f mall jackal fl<in faftened round his loins principles of tbefe fignals, invented with fo much inn-e- 
 
 by two thongs, the extremities of which hang down to unity. He did not requeft Information ; bccanfe he 
 
 his knees. Hardened by this conftant habit of naked- very rationally inferred that his requcll would not have 
 
 nefs, he becomes fo uifenfible to the variations of the been granted ; but he obferved, that three fires kiiulied 
 
 atmofphere, that when he removes from the burning at the diftance of twenty paces from each other fo as 
 
 fands of the level country to the fnow and hoar-froft of to form an equilateral triangle, were the fignal for rally- 
 
 his mountains, he feems indifferent to and not even to iug. 
 
 feel the cold. Among the phyfical qualities w hich, in M. Vaillant's 
 His hut in nowife refembles that of the Hottentot, opinion, prove that the Houzouanas are a dillina na- 
 It appears as it cut vertically through the middle; fo tion, he mentions tlie enormous natural rump of the 
 tha.' the hut of a Hottentot would make two of thofe women, as a deformity which diftinguilhes them, from 
 of the Houzouanas. During their emigrations, they every other people, favage or polilhed, which he had 
 leave them ftanding, in order that, if any other horde ever known. " I have feveral times (fays he) had oc- 
 of the fame nation pafs that way, they may make ufe cafion to remark, that, among the female Hottentots in 
 of them. When on a journey, they have nothing to general, as they advance in age, the inferior part of the 
 repofe on but a mat fuipended from two fticks, and back fwells out, and acquires a fize which it greatly- 
 placed in an inclined pofition. They often even deep exceeds the proportion it bore in infancy with the other 
 on the bare ground. A projeding rock is then futfi- parts of the bovly. The Houzouana womiyi, haviHg 
 csent to fhelter them; for every thing is fulled to a in their figure fome refemblance to the Hottentots, and 
 people whofe conftitutions are proof againft the fevereft appearing therefore to be of the fame race, one might 
 fatigue. If, however, they ftop anywhere to fojourn be induced to believe that their projeftion behind is 
 tor a while, and find materials proper for conftructing only the Hottentot rump more fwelled and extended, 
 huts, they then form a kraal ; but they abandon it on I obferved, however, tliat among the former this fin- 
 their departure, as Is the cafe with all the huts which gularlty was an excrefcence of (low growth, and in fome 
 they ereft. meafure an infirmity of old age ; whereas among the 
 This cuftom of labouring for others of their tribe latter it is a natural deformity, an original charatterif- 
 announces a focial charafter and a benevolent difpofi- tic of their race. The Houzouana mothers wear on 
 tion. They are indeed not only affedlionate huft)ands their reins, like our nn'ners, a flcln which covers tills 
 and good fathers, but excellent companions. When protuberance of the pofteriors ; but which, being thin 
 they inhabit a kraal, there Is no fuch tiling among thetiT and pliable, yields to the quivering of the flelh, and be- 
 as private property ; whatever they poffefs is in com- comes agitated in the fame manner. When on a jour- 
 mon. If two hordes of the fame nation meet, the re- ney, or when they have children too young to follow 
 ception is on both fides friendly ; they afford each o- them, they place them upon their rump, j faw one of 
 tlier mutual proteflion, and confer reciprocal obliga- tlicfe women run in this manner with a cliild, about 
 tions. In (hort, they treat one another as brethren, ihrL-e years of age, that ftood eredl on its feet at her 
 though perhaps they are perfeft ftrangers, and have back, like a footboy behind a cavriaTc." 
 never feen each other before. If one half of what our traveller fays of the aftlvity 
 SoppL. Vol. I. Part II.. ^C and
 
 HUN 
 
 [ 7 
 
 hi/}, ofln. 
 Vintlon:, 
 
 and enterprifing fpivit of this fiiigulav people be true, 
 might not the African AfTociation fend a fecond Hough- 
 ton, or fecond Park, to mal^e difcoverics i.i llial unex- 
 plored couvtry, under the protection of the Hou/.uua- 
 iias? We do not indeed thi'ik that it would be pofTible 
 to travcrfe tiie whole extent of Afnca from fouth to 
 north, biit Vaillant penetrated farther in tlr.it dircftiun 
 than any one had done before him; and it apjiears that 
 with his intrepid Houzouanas he might have penetrated 
 much farther. 
 
 HUNGARY-WATER, is fpirit of wine dillilled up- 
 on rofcmary, and which therefore contains its oily and 
 ftrong-fcented elTence (fee Pharmacy, n° 365. Encycl.) 
 To be really good, fays ProfcflTor Beckmant., the fpirit 
 of wine ought to be very ftrong, and the rofemary frefli; 
 and if that be the cafe, the leaves arc as proper as the 
 flowers, which, according to the prtfcriptiuu of fome, 
 fticuld only be taken. It is likevife neceffary tliat the 
 fpirit of wine be diftilled feveral times upon the rofe- 
 mary ; but that procefs is too trotiblefome and expen- 
 five to admit of this water being difpdfed of at the low 
 price it is ufually fold for; and it is certain that the 
 greater part of it is nothing elfe than common brandy 
 united with the efience of rofemary in the fimpleft man- 
 ner. In general, it is only mixed with a few drops of 
 the oil. For a long time part, this article has been 
 brought to us principally from France, where it is pre- 
 pared, particularly at Beaucaiiv, Montpelier, and other 
 phces in Languedoc, in which that plant grows in 
 great abundance. 
 
 The name Hungary 'water feems to fignify. that this 
 v/ater, fo celebrated for its medicinal virtues, is an Hun- 
 garian invention ; and we read in many books, that the 
 receipt for preparing it was given to a queen of Hun- 
 gary by a hermit ; or, as others fay, by an angel, who 
 appeared to her in a garden, all entrance to which was 
 fhut, in the form of a herm.it or a youth. Some call 
 the queen St Ifabella; but thofe who pretend to be beft 
 acquainted with the circumftance affirm, that Elizabeth, 
 wife of Charles Robert king of Hungary, and daugh- 
 ter of Uladiflaus II. king of Poland, v^ho died in 1380 
 or 13S1, was the inventrefs. By often wafhing with this 
 fpirit of rofemary, when in the 7Ctli year of her age, 
 flie was cured, as we are told, of the gout and an uni- 
 vcrfal lamenels ; fo that (he not only lived to pafs 80, 
 but became fo lively and beautiful, that (he was courted 
 
 54 ] . HUN 
 
 by the king of Poland, who was then a widower, and Hunttr. 
 who wifiicd to make her his fecond wife. ' y^- 
 
 The Profeflor juiUy coiifidtrs this llory as a ridicu- 
 lous fable (a). " It appears to me (fays he) m.oil pro- 
 bable, that the French name I'eau de la rcinc d' Hojigrle, 
 was chofen by thofe who, in latter times, prepared fpi- 
 rit of rofemary for fale, in order to give greater confe- 
 quence and credit to their commodity ; as various me- 
 dicines, fome years ago, were extolled in the gazettes 
 under the title of Pompadour, though the celebrated 
 lady, from whofe name they derived their importance, 
 certainly neither ever faw them nor ufed them." 
 
 HUNTER (John), the celebrated furgeon, was the 
 youngell child ot John Hunter of Kilbride, in the coun- 
 ty of Lanark. He was born on the 14th of July 1728, 
 at Long Calderwood, a fmall ellate belonging to the 
 family ; and lofing his father when he was about ten 
 years of age, he was perhaps too much indulged by his 
 mother. One confequence of this was, that at thegram- 
 mar-fciiocl he made no progrtfs in learning ; and he 
 may be faid to have been almoll totally illiterate when, 
 in September 1748, he arrived in London. His bro- 
 ther, Dr William Hunter, of whom an account is gi- 
 ven in the Encyclopitdia, was then the mofl, celebrated 
 teacher of anatomy, and John had exprefled a defire ta 
 affill him in his refearches. The Doctor, who was very 
 defirous to ferve him, and anxious to form fome opi- 
 nion of his talents for anatomy, gave him an arm to 
 diffeft for the mufcles, with the neceffary diredtions 
 how it was to be done ; and he found the performance 
 fuch as greatly exceeded his expeftation. 
 
 His iiril elTay in anatomy having thus gained him 
 fome credit, Mr Hunter was now employed in a dilTec- 
 tion of a more difficult nature ; this was an arm in 
 which all the arteries were injected, and thefe, as well 
 as the niufcles, were to be expofed and prelerved. The 
 manner in which this was performed, gave Dr Hunter 
 fo much fatisfattion, that he did not fcruple to fay 
 that his brother would become a good anatomiil, -.nd 
 that he fhould not want for employment. From this 
 period we may confider Mr Hunter as having ferioully 
 ei gaged in anatomy ; and under the indruftions ot Dr 
 Hunter, and his affillaat Mr Symonds, he had every 
 opportunity bf improvement, as all the dilTeftions at 
 this time carried on in London were confined to that 
 fchool. 
 
 In 
 
 (a) It was firft puhlI{hed.to the world in 1659 in a poilhumous work of John Prevot, who fays, that in the 
 beginning of a very old breviary, he faw 3 remedy for the gout, written by the queen's own hand, in the follow- 
 ing words : 
 
 " I Elizabeth, queen of Hungary, being very Infirm and much troubled with the gout in the 72d year of my 
 age, ufed for a year tin's receipt, given to me by an ancient hermit, whom I never faw before nor fince ; and was 
 not only cured, but recovered my ftrength, and appeared to all fo remarkably beautiful, that the king of Poland 
 aflvcd me In marriage, he being a widower and I a widow. I, however, refufed him for the love of my Lord Je- 
 fus Chrift, from one of v/hofe angels, I believe, I received the remedy. The receipt is as follows : 
 
 " ^. Take of aqua vltx, four times dillilled, three parts, and of the tops and flowers of rofemary two parts ; 
 put thefe together in a clofe vcifel, let them fland in a gentle heat 50 hours, and then dlftil them. Take 
 one dram of this in the morning once every week, either in your food or drink, and let your face and the 
 difeafed limb be waflied with it every morning. 
 
 " It renovates the ilrengtli, brightens the fpirils, purities the marrow and nerves, reftores and preferves the 
 fight, and prolongs life." Thus far from the Breviary. Then follows a confirmation which Prevot gives from 
 Ills own experience.
 
 HUN [ 7 
 
 Hunrer. In t!ie fummer 17+9, Mr Chefclden, at the rcqucft 
 '"'»'' ' of Dr Hunter, perniitttd him to attend at Chellea Hol- 
 ,pital ; and he there learned the firtt rudiments ot lur- 
 gery. 
 
 The following winter he was fo far advanced in the 
 knowledge of human anatomy, ai to inllruct the pupils 
 in diffcCtiun, to wliDm Dr Hunter had very little time 
 to pay attention. This oiHce, therefore, fell almolt en- 
 tirely upon him, and was his conftant employment du- 
 ring the winter leafon. 
 
 In tlie fummer months of 1750, Mr Hunter attend- 
 ed tlie hofpital at Chelfea ; in 1751, he became a pu- 
 pil at St Bartholomew's, and in the winter was preient 
 at operjtions occatioi ally, whenever any thing extraor- 
 dinary occurred. The following fummer he went to 
 kColland; and in 1 7113 entered, it is difficult to con- 
 ceive for what reafon, as a gentleman commoner at St 
 Mary-hall, Oxford. In 1754 ^^ became a fingeon's 
 pupil at St George's hofpital, where he continued du- 
 ring the fummer months j .nd in 1756 was appointed 
 houfe-furgeon. 
 
 In the winter 17 j5. Dr Hunter admitted him to 
 a partnirdiip in his Icdtures, and a certain portion of 
 the courfe was allotted to Jiim ; befldes which, he gave 
 ledlures when the DoClor was called away to attend his 
 patients. Making anatomical preparations was at this, 
 time a new art, and very little known ; every prepara- 
 tion, therefore, that was fkilfuUy made, became an ob- 
 jedl; of admiration ; many were wanting for the uie of 
 the ledfures ; and the Doftor being l.imf.lf an enthii- 
 iiall for the art, left no means untried to infufe into his 
 lirother a love for his favourite purfuits. How well 
 lie fucceeded, the colleftion afterwards made by Mr 
 Hunter will fuflSciently evince. 
 
 Anatomy feems to have been a purinit for- which 
 Mr Hunter's mind was peculiarly fitted, and he applied 
 to it with an ardour iiid perfeverance of which tliere is 
 hardly an example. His labours were fo uleful to his 
 brother's collection, and fo gratifying to his difpofition, 
 that al'-hough in many other rcipcAs they did not agree, 
 this fimple fie kept them together for many years. 
 
 Mr Hunter worked for ten years on human anato- 
 my ; during which period he made himfelf mafter of 
 what was already kriovvn, as well as made fome addi- 
 tion to that knowledge. He traced the ramifications 
 of the olfaiStory nerves upon the membranes of the nofe, 
 and difcovcred the courfe of forae of the branches of 
 the fifth pair of nerves. In the gravid uterus, he tra- 
 ced the arteries of the uterus to their termination in 
 the placenta. He was alfo the firft who difcovcred the 
 exittence of the lymphittic veflels in birds. 
 
 Many parts of the human body being fo complex, that 
 their ftructure could not be underftood, nor their ufes 
 afcertained, Mr Hunter was led to examine fimilar parts 
 in other animals, in v\'hich the flrufture was more 
 fimple, and more within the reach of inveftigation ; this 
 carried him into a wide field, and laid the foundation 
 of his colleftion in comparative anatomy. 
 
 In this new line of purfuit, this adtive inquirer be- 
 gan with the more common animals, and preferved fuch 
 parts as appeared by their analogy, or in fome other 
 way, to elucidate the human economy. It was not his 
 intention to niuke difFedlions of particular animals, but 
 to inftitute an inquiry into the various organizations 
 
 5.J ] HUN 
 
 by which the functions of life are performed, that he Himtrr. 
 might thereby acquire fome knowledge of general pria- ""~^"'~' 
 ciples. 
 
 So eagerly did Mr Hunter attach himfelf to conipa- 
 rative anatomy, that he fought by every means in his 
 power the opportunities of profeeuting it with advan- 
 tage. He applied to the keeper of wrid bc.ills in liie 
 Power for the bodies of thole wiiieh died there ; and 
 he made fimilar avplications to the men who Ihowed 
 wild beaiU. He purcliifed all rare animals which canie 
 in his way ; and thefe, with fuch others as were pre- 
 fentcd to him by his friends, he entrulled to the fhow- 
 nien to keep till they died, the better to encourage 
 them to affill him in his Idhours. 
 
 His health was fo much impaired by exceflive atten- 
 tion to his purfuits, that in the year 1760 he was ad- 
 vifed to go abroad, having complaints in his brcalt 
 which threatened to be conlumptive. In Oclobei- of 
 that year, Mr Adair, infpettor-general of hofpitak, ap- 
 pointed him a furgcon on the Half; and iii ti'.e follow- 
 ing fpring he went w-ith the ariny to Bcllifie, leaving 
 Mr Hewfon to affiR his brother during his ablenee. 
 
 Mr Hunter ferved, while the war continued, as fe- 
 nlor furgeon on the ilaff, both in Bcllifie and Portugal, 
 till the year 1763 ; and in that period acquired his 
 knowledge of gun-fhot wounds. On his return to Eng- 
 land he fettled in London ; where, not finding the emo- 
 luments from his half-pay and private pradtlce fufficient 
 to fupport him, he tauglit practical anatomy and ope- 
 rative furgery for feveral winters. He returned alio, 
 with unabated ardour, to comparative anatomy ; and 
 as his experiments could not be carried on in a large 
 town, he purchafed lor that purpofe, about two miiei 
 from London, a piece of ground near Bronipton, at a 
 place called Earl's Court, on which he built a houfe. 
 In the courfe of his inquiries, this excellent anatomill , 
 afcertained the changes which animal and vegetable 
 fubllances undergo in the flomach when afted on by 
 the gallric juice ; he difcovered, by means of feeding 
 young animals with madder (which tinges growing 
 bones red), the mode in which a bone retains its fliape 
 during its growth ; and explained the procefs of exfo- 
 liation, by which a dead piece of bone is feparated from 
 the living. 
 
 His fondnefs tor animals made him keep feveral of 
 different kinds in his houfe, which, by atltntion,he i-en- 
 dered familiar with him, :><id anuifed himfelf Cy obfer- 
 viug their peculiar habits and infllnCts ; but this fami- 
 liarity was attended with confiderable rilk, and fome- 
 times led him into fituations of danger, of which the 
 following is a remarkable inftance : 
 
 Two leopaids, which were kept chained in an out- 
 houfc, had broken from their confinement, and got in- 
 to the yard among fome dogs, which they immediately 
 attacked ; the howling this produced alarmed the whole 
 neighbourhood ; Mr Hunter ran into the yard to fee 
 what was the matter, and found one of them getting 
 up the wall to make his efcape, the other fnrrounded 
 by the dogs; he immediately laid hold of them both, 
 and carried them back to their den ; but as loon as they 
 were fecured, and he had time to refleft upon the rifk 
 of his own lituation, he wa^ fo much agitated, that he 
 was in danger of fainting. 
 
 On the fifth of February 1767, he was chofen a fel- 
 5 C 2 low
 
 HUN 
 
 Hunter. 
 
 low of the Royal Society. His defire for improvement 
 ill thoic branches of knowledge which miglit aifill in 
 his rtiearchts, leil him at this time to projiofe to Dr 
 George Fordyce and Mr Cumniing, an eminent me- 
 chanic, that they (lioiild adjourn from the meetings of 
 the Royal Society to fonie coffee-hoiife, and dii'cufs fuch 
 fubjefts as were coniiei'tcd with fcicnce. Tliis plan 
 was no founer eftabh'du'd, than they found their num- 
 bers iricreafcd ; they were joined by Sir Jofepli Banks, 
 Dr Solander, Dr Maikelyne, Sir Geora^e Shuckbnre;]), 
 Sir Harry Englefitld, Sir Charles Blagden, Dr Noothe, 
 Mr Ramfden, Mr W,att of Birmingham, and many 
 others. At thefe meetings difcoveries and improve- 
 ments in different branches of philofophy were the ob- 
 jcfts of their confidcration ; and the works of the mem- 
 bers were read over and criticilcd before they were 
 given to the pnblic. It was in this year that, by an 
 exertion in dancing, after the mufcles of the leg were 
 fatigued, he broke his tejido achillis. This accident, 
 and the confiuement in coiifcquence of it, led him to 
 pay attention to the fubjcA of broken tendons, and to 
 make a feries of "experiments to afcertain the mode of 
 their union. 
 
 In the year 176S Mr Hunter became a member of 
 the corporation of furgeons ; and in the year following, 
 through his brother's intereft, he was clefted one of 
 the fui'geon's of St George's hofpital. In May 1771, 
 bis Treatile on the Natural Hiilory of the Teeth was 
 publifhed ; and in July of the fame year he married 
 iilifs Home, the cldeft daughter of Mr Home, furgcon 
 to Burgovne's regiment of light liorfe. The expence 
 of his purfuits had been fo great, that it was not till 
 feveral years after his firll engagement with this lady 
 that his affairs could be fufficiently arranged to admit 
 of his marrying. 
 
 Though after his marriage his private pratfice and 
 profeflional charadler advanced rapidly, and though his 
 family began to incrcafe, he Hill devoted m.uch of his 
 time to the forming of his colleftion, which, as it daily 
 became larger, was alfo attended with greater expence. 
 The whole fuit of the belt: rooms in his houfe were oc- 
 cupied by his preparations ; and he dedicated his morn- 
 ings, from funrife to eight o'clock (the hour for brcak- 
 falt), entirely to his purfuits. To thefe he added fuch 
 parts of the day as were not engaged in attending his 
 patients. 
 
 The knowledjre he derived from his favourite ftudies 
 he conftantly applied to the improvement ot the art of 
 furgery, and omitted no opportunity of examining mor- 
 bid bodies ; from which he made a colleftion of fafts 
 which are invaluable, as they tend to explain the real 
 caufes of fymptoms, which, during life, could not be 
 exadlly afccrtained, the judgment of the praftitioner 
 being too frequently miflcd by theoretical opinions, and 
 delufive fenfations of the patients. 
 
 In the praftice of furgery, where cafes occurred in 
 which the operations proved inadequate to their inten- 
 tion, he always inveftigated, with uncommon care, the 
 caufes of that want of fuccefs ; and in this way de- 
 teflcd many fallacies, as well as made fome important 
 difcoveries, in the healing art. Jie detected the caufe 
 of failure, common to all the operations in uie for the 
 radical cure of the hydrocele, and was enabled to pro- 
 pofe a mode of operating, in which that event can with 
 certainty be avoided. He afcertained, by experiments 
 
 [ 756 ] 
 
 HUN 
 
 and obfervations, tliat expofure to atmofpherlcal air 
 iuiiply, can neither produce nor incrcafe infl.nnmation. 
 He difcovered in the blood io many phenomena con- 
 iieded with life, and not to be referred to any other 
 cauie, that he confidered it as alive in its fluid ftate. 
 He improved the operation for the fillula lachrymalis, 
 by removing a circular portion of the os unguis inftead 
 <)t breaking it down with the point of a trochar. He 
 alio dilcovered that the gaftric juice liad a power when 
 the ftomach was dead of diffolving it ; and gave to the 
 Royal Society a paper on this fubjeft, which is publifh- 
 ed in the Philofophical Tranfaftions. 
 
 In the winter 1773, he formed a plan of giving a 
 courfe of leClures on the theory and principles of fur- 
 gery, with a view of laying before the public his own 
 opinions upon that fubjeft. For two vv'inters he read 
 his le&iires gralis to the pupils of St George's Hofpi. 
 tal ; and in 1775, gave a courfe for money upon the 
 fame terms as the other teachers in the different branches 
 ot medicine and furgery. But giving lectures was al- 
 ways particularly unpleafant to him ; fo that the de- 
 fire of lubmitting his opinions to the world, and learn- 
 ing their general ellimation, were fcarcely fuflieient to 
 overcome his natural diflike^o fpeaking in public. He 
 never gave the firft lefture of his courfe without taking 
 30 drops of laudanum to take off the effefts of his un- 
 eafinefs. 
 
 Comparative anatomy may be confidered as the pur- 
 fuit in which Mr Hunter was conftantly employed. No 
 opportunity eicaped him. In the year 177;^, at the 
 requeft of his friend Mr Walffi, he differed the torpe- 
 do, and laid before the Royal Society an account of 
 its eledrical organs. A young elephant, which had 
 been prefented to the Queen by Sir Robert Barker, 
 died, and the body was given to Dr Hunter, which af- 
 forded Mr Hunter an opportunity of examining the 
 ftrufture of that animal by affilling his brother in the 
 diffettion ; fjnce that time two oth<:r elephants died ia 
 the Queen's menagerie, both ot which came under Mr 
 Hunter's examination. In 1774, he publifhed in the 
 Philofophical Tranfiiftions an account of certain re- 
 ceptacles of air in birds, which communicate with the 
 lungs, and are lodged both among the flelhy parts and 
 hollow bones ot thefe animals ; and a paper on the GiL- 
 laroo trout, commonly called in Ireland the GixzanJ- 
 trout. 
 
 In 1775, feveral animals of that fpecies, called the 
 gymnolus eiedricus of Surinam, were brought alive to this 
 country, and by their eletlrical properties excited very 
 much the pubu'c attention. Mr Wallh, defirous of 
 purfuing his invtftigations of animal eletiricity, made a 
 number of experiments on the living animals ; and to 
 give his friend Mr Hunter an opportunity of examining 
 them, purchafed thofe that died. An anatomical ac- 
 count of their elettrical organs was drawn up by Mr 
 Hiinter, and publifhed in the Philofophical Tranfacr 
 tions. In the fame volume there is a paper of his, con- 
 taining experiments on animals and vegetables refpedt- 
 ing their power of producing heat. 
 
 In the courfe of his purfuits, Mr Hunter met with 
 many parts of animals where natural appearances could 
 not be prcferved, and others, in which the minuter vef- 
 fels could not be dillintlly feen when kept in fpirits; 
 it was therefore neceffary to have them drawn, either 
 at the moraentj or before they were put into bottles. 
 
 Tlie 
 
 'h, 
 
 untcr.
 
 HUN 
 
 [ 757 ] 
 
 HUN 
 
 Hiiintr- The expcncc of employing profcfTcd drai!ghtfmen, the 
 
 "— V~~ difficulty of procuring tliem, aiul the difadvaritnge whicli 
 
 they laboured under in being ignorant of the fubicCl 
 
 they were to reprcfcnt, made him dtilrous of having an 
 
 able perfon in his houfe entirelv hir tliat purpole. 
 
 With this view he engaged an ingenious young artill 
 to live with him for ten years ; his time to be wholly 
 employed as a draughtfman, and in making anatomical 
 preparations. This gentleman, whofe name v.is Bell, 
 foon became a very good pradtical anatomift, and from 
 that knowledge was enabled to give a fpirited and ac- 
 curate refemblance of the fubjefts he drew, fucb as is 
 rarely to be met with in reprefentations of anatomical 
 fubjcfts. By his labours Mr Hunter's coUeflion is 
 enriched with a confiderable number of very valuable 
 drawings, and a great variety of curious and delicate 
 anatomical preparations. 
 
 In January 1776, Mr Hunter was appointed fur- 
 geon extraordinary to his Majefty ; and in the fpring 
 he gave to the Royal Society a paper on the bell mode 
 of recovering drowneil perfons. 
 
 In the atitumn he was taken extremely ill ; and the 
 nature of his complaints made his friends, as well as 
 himfelf, confider his life to be in danger. When he 
 reflefted upon his own fituation, that all his fortune 
 had been expended in his purfuits, and that his family 
 
 appeared to himfelf unliniflied. Hisobfcrvations oh the Hurttr. 
 Mufcular Aftion of the BlocxI-vefTels were laid before ~~~v~— 
 the Royal Society in 1780, and yet he delayed publKh- 
 ing them till his Obfervations on the Blood and Iiitlam- 
 mation were arranged ; and they make part of the vo- 
 liune. which was publ.ifhtd alter his deatli. 
 
 In 17S3, he was chofeii into the Royal Socl<-ty of 
 Medicine and the Royal Academy of Surgery in Paris ; 
 and tiie fame year the leaie of the honfe which he oc- 
 cupied in Jermyn-ftreet having expired, he piirchafed 
 the leafe of a large houfe on tlic call-fide of Leicefler- 
 fquare, and the whole lot of ground adjoining to Caftle- 
 ftreet, on which there was another houle. In the niid» 
 die fpace between the two houfts, he erected, at the ex- 
 pence ot L.3000, a building fc:r his coUeftion ; though, 
 unfortunately for his family, the leafe did not extend be- 
 yond 24 years. 
 
 In tlie building formed for the collection there was 
 a room fifty-two feet lo.ng by twenty-eight feet wide, 
 lighted hom the top, and having a gallery all round, 
 for containing his preparations. Under this were two 
 apartments; one for his ieflures, and the other, with no 
 particular dellination at firft, but afterwards made ufe 
 of for weekly meetings of medical friends during the 
 winter. To this building the houfe in Caftle-ftreet was 
 entirely fnbfervient ; and the rooms in it were ufed for 
 
 had no provifion but what fliould arife from the fale of the diHerent branches of human and comparative ana- 
 his colledliou, he became very folicitous to give it its tomy. 
 
 full value, by leaving it in a ftate of arrangement. This 
 he accomplilhed with the aifiilance of Mr Bell and his 
 brother.in-law Mr Home. 
 
 In 1778, he publUhed the fecond part of his Treatife 
 on the Teeth, in which their difeafes, and the mode of 
 treatmet;t are conlidcred. This rendered his work up- 
 on that fubjetl complete. He publlllied alio in the 
 Phllofophical Tranfadlions a paper on the Hcatof Aui- 
 mals and Vegetables. In 1779, lie publlHied his account 
 ot the Free Martin in the Phllolophical Tranfaftions ; 
 and in 1 78c, he laid before the Royal Society an ac- 
 count of a woman who had the fmail pox during preg- 
 nancy, where the difeafe fcemed to have been -cemmuni- 
 cated to the foetus. 
 
 In \J'U, he was elefted a fellow of the Royal So- 
 ciety of Sciences and Belles Lettres at Gotteaburg. 
 And in 1782, he gave the Royal Society a paper on 
 the Organ of Hearing in Fifli. Befides the papers 
 which he prefented- to that learned body, he read fix 
 Croonion lectures upon the fubjeft of Mulcular Aftion, 
 for the years 1776, 1778, 1779, 178c, 1781, and 
 1 7S2. In thcfe Ititures he colledted all his obfervations, 
 upon mufcles; refptrting their powers and effefts, and 
 the ftimull by which they are affe<!;ted ; and to thefe 
 he added Comparative Obfervations upon the moving 
 Powers of Plants. 
 
 Thefe kftures were not publiflied in the Philofophi- 
 
 • About this period Mr Hunter may be confidered as 
 at the height of his chirurgical career ; his mind and 
 body were both in their full vigour. His hands were 
 capable ot performing whatever was fuggcfted by his 
 mind ; and his judgment was matured by former expe- 
 rience. Some inltancea of his extraordinary flvill may 
 very properly be mentioned. 
 
 He removed a tumor from the fide of the liead and 
 neck of a patient at St George's Hofpital, as large as 
 the head to which it was attached ; and by bringing the 
 cut edges of the ilcin together, the whole was nearly 
 healed by the firft intention, 
 
 He dilTeCted out a tumor on the neck, which one of 
 the bell operating furgeons iu this country had decla- 
 red, rather too llrongly, that no one but a fool or a 
 madman would attempt ; and the patient got perfeftly 
 well. 
 
 He difcovCred a new mode of performing the opera- 
 ticm for the pojjlitea! anenrifni, by taking up the fe- 
 moral artery on the anterior part of the tliigli, without 
 doing any thing to the tumor in the ham. The lafety^ 
 and efficacy of this mode have bc^n confirmed by many 
 fubfequent trials; and it muft be allowed to ftaiid very 
 high among the modern improvements in furgery. 
 
 If we confider Mr Hunter at this period of his life, it 
 will afford us a Itrong pitture of the turn of his mind, 
 of his defire to acquire knowledge, and his unremittinij 
 
 cal Tranfattions, for they were withdrawn as foon as affiduity in profecuting whatever was the objefit of his. 
 read, not being confidered by the author as complete attention. 
 
 differtations, but rather as materials for fome future 
 publication. 
 
 It is much to be regretted (fays Mr Home) that Mr 
 Hunter was fo tardy in giving his obfervations to the 
 public ; but fuch was his turn for invelligation, and fo 
 extenfive the fcale upon which he inftituted his inqui- 
 rie,<;, that he always tound fomcthing more to be acconi- 
 pliTned, and was unwilling to publilh any thing wliicU 
 
 He was engaged in a very extenfive private praiTiice; 
 he was furge'on to St George's Hofpital ; he was giving 
 a very long courie of lectures in the winter ; he was car- 
 rying on his inquiries in comparative anatomy ; had a 
 fchool of pradllcal human anatomy in his houfe ; and 
 was always employed in fome experiments refpeiSing the 
 animal economy. 
 
 He was always foliciou s for fome improvement in- 
 
 Bii dicall
 
 HUN C 758 
 
 Hunt:!", medical education ; and, wit!) the afHOancff of Dr For- 
 •■''-v~~ ()yce, inllitiited a irinlical focifty, which he allowed to 
 mf <~t ill hisli'fture rootnr,, and ot which he was d^ofeii one 
 of the patrons This tucicty, called the Lyceum Mcdicum 
 IiontllncnO-, under his aulpicts and thofe ol Dr Fordyce, 
 has acquired coplidcrablc reputation, both fror!\ the 
 mimbcrs aud merits ot its members. 
 
 In the year I7^'6, in coniequence of the death of Mr 
 Middletnn, Mr Hunter was appointed deputy furt^eon- 
 gcneral to the army. He now pubh'lhcd his work up- 
 on the Venereal Difeafe, which had been long expect- 
 ed by the public ; and; if we may judge from tlie rrpid 
 fale of the firll edition, thele expetlalions have not been 
 diiappointed 
 fervptions on ce 
 
 ] n u N 
 
 unfurmountaMe d'fficiltles ; but thefe proved to \v.n Hunter. 
 only an incitement, and the contrivances he made uf,; — v — - 
 ot totring the diffceut opeiaticnis of thefe indefatigable 
 animals to view were almoit without end. 
 
 Earl's Court to Mr Hunter was a retirement from 
 the fatigues of liis profefiion ; but in no rcfpeift a le- 
 treat from his labours; there, on the contrary, they were 
 carried on with lefs interruption, aud with an unwearied 
 perfeveKiiice. From the year 1772 till his deatii, he 
 made it his cnttom to fleep thire during the autumn 
 months, coming to town only during the hours of bu- 
 hncis in the forenoon, and returning to ih'nner. 
 
 It was there he carried on his experiments on di. 
 He alfo publiflied a work entitled, Ob- geftion, on txi'oliation, on the tranfplanting of teeth in- 
 ertain Parts ot the Animal Economy, to the combs of cocks, and all his other invtlligations 
 In this work he has collected f.'veral of his papers in- on the animal economy, as well in health as in difeafe. 
 I'erted in the Philofophical IVanfattions, which related The common bee was not alone the fubjcct of his ob- 
 t(> that fiiVyeft, having permiffion from the prefident fervation, but the wafp, hornet, and the lefs known 
 and council of the Royal Society to reprint them ; there kinds of bees, were alfo objefts of his attention. It was 
 are alfo Obfervatiorjs upon fome other parts of the Ani- there he made the feries of preparations of the external 
 nial Economy, which had not before been publiflied. and internal changes of the filk * orni ; alfo a feries <pf 
 This work met with a very ready fak. the incubation of the egg, with a very valuable fct of 
 
 In the year 1787, he gave a paper to the Royal So- drawings of the whole feries! The growth of vegetables 
 ciety, containing an Experiment to determine the Effedt was alfo a favourite fubjeft of inquiry, and one on which 
 of extirpating one Ovarium on the Number of Young; he was always engaged in making experiments. 
 a paper in which the wolf, jackall, and dog, are proved The colleftion of comparative anatomy which Mr 
 
 to be of the fam.e fpecies ; and a third upon the Ana- Hunter has left, and which may be co'nfi'dered as the 
 tomy of the Whale Tribe. Thefe papers procured him great objeft of his life, mufl: be allowed to be a proof 
 the honour of receiving Sir John Copley's annual gold of talents, afliduity, and labour, which cannot be con- 
 medal, given as a mark of dillinguiihed abilities. templated without furprife and admiration. It remains 
 His collcdlion, wh'.ch had been the great objeft of an unequivocal tell of his perfeveranre and abilities, and 
 his life, both as a purfuit aud an amnfcment, was now an honour to the country in whofe fchools he was edu- 
 brought into a (late of arrangement; and gave him at cated, and by the patronage of which he was enabled 
 length the fatisfaftion of flv-'wing to the public a feries on fo extenfive a fcale to carry on his purfuits. In this 
 of anatomical fads formed into a fyftem, by which the collection we find an attempt to expofe to view the gra- 
 economy of animal life was illullratcd. He Ikevved it dations of Nature, from the moll iimple ftate in which 
 to his friends and acquaintances twice a-year, in Odto- life is found to exift, up to the molt perfedt and moil 
 ber to medical gentlemen, and in May to noblemen and complex of the animal creatior ■ — man himfclf. 
 gentlemen, who were only in town during the fpring. By the powers of his art, this collector has been ena- 
 This cuflora he continued to his death. bled fo to expofe, and preferve in fpirits or in 3 dried 
 Upon the death of Mr Adair, which happened in the ftate, the different parts of animal bodies intended for 
 year 1792, Mr Hunter was appointed infpcctor-gcneral fimilar ufes, that the various links of the chain of per- 
 of hofpitals, and iurgcon-gencral to the army. He was fettion are readily followed and may be clearly under- 
 alfo elected a member of the Royal College of Surgeons ftood. 
 
 in Ireland. In the year 1791, he was fo much enga- This colleftion of anatomical fads is arranged ac- 
 
 ged in the duties ot his office, as furgeon -general to the cording to the fubjetts they ^re intended to illultrate, 
 army, and his private praiitice, that he had little time which are placed in the following order : Fir//, Parts 
 
 to bellow upon his fcientifical objefts ; but his leifure 
 time, fmall as it was, he wholly devoted to them. 
 
 In 1792, he was cletted an honorary member of the 
 Chirurgo-Phyfical Society of Edinburgh, and was cho- 
 fen one of the viee-prelidents of the Veterinary College, 
 then firil eilablilhed in Eondon. He publiihed in the 
 
 conftrudted for motion. Secondly, Parts effcntial to ani. 
 mals refpetliiig tlieir own internal economy. Thirdly, 
 Parts iuperadded tor purpofes connected with externa! 
 objects. Fourthly, Parts for the propagation of the 
 fpecies and maintenance or fupport of the young. 
 
 Mr Hunter was a very healthy man for the firlt forty 
 
 TranfaCl:ions ot the Society for the Improvement of me- years of his life | and, if we except an inflammation of 
 
 dical and chirurgical Knowledge, ot which lociety he 
 was one of the original members and a zealous promo- 
 ter, three papers on the following fubjeCts : Upon the 
 Treatment of Inflamed Veins, on Introfulception, and 
 on a Mode of conveying Food into the Stomach in 
 Cafes of Paralyfis of the Gi^lophagus. 
 
 He finiflied his Oblervations on the Economy of Bees, 
 and prefented them to the Royal Society. Thefe ob- 
 fervations were made at Earl's Court, and had engaged 
 his attention for many y^ears ; every inquiry into the 
 sconomy of thefe infefts had been attended by almoll 
 
 his Jungs in the year 1759, occalioncd m.oll probably 
 by his attention to anatomical purfuits, he had no com- 
 plaint of any confequence durnig that period. In the 
 ipring of 1769, in his forty firlt year, he had a regular 
 fit ot the gout, which returned the three following 
 fprings, but not the fourth; and in the ipring of 1773> 
 having met with fomething which very iorcibly affected 
 his mind, he was attacked at ten o'clock in the forenoon 
 with a pain in the flomach, attended with all the fymp- 
 toms oi angina peiloris. In the liie of him prefixed to 
 his Treatife on the Blood, Injlammation, and Gun-Shot 
 
 Wounds,
 
 HUN [7 
 
 Kur.ter. Wounds, tlic reader will find one of the mod compli'tc 
 '""~v~~ hiftories of that fiiTenfe upon record. Suffice it, in tliis 
 j)lace, to fay, that for twenty years he was fiibjeft to 
 ir^'quent and feverc attacks of it, which however did 
 not, till a fliort time before his death, either impair his 
 iiidgtntnt or render him incapable of perforniin;^ opera- 
 tions in fiirgery. " In autumn 179C (fiys Mr Home), 
 ai^d in the fpring and autumn 1791, he had mure fevere 
 attacks tliau during the other j)eriods of the year, but 
 of not more than a few hours duration : in the liegiu- 
 iiing of Oitoberi792, one, at which I was prefent, 
 was fo violent tliat I thought he would have died. On 
 October the i6lh, 1793, when iu h'l iifual Hate of 
 health, he we.it to St George's Hufpiiil, and meeting 
 with fome things which irritated his mind, and not be- 
 ing perfe'lly mailer of the circumftances, he withheld 
 ■ his fentimcnts ; in which Itate of rcftraint he went into 
 the next room, and'turniiig round to Dr Iloberifou, one 
 of the phylicians ot the hofpital, he gave a deep gToan 
 and dropt down dead; being then in his 65th year, the 
 fame age at which his brother Dr Hunter had died." 
 
 It is a curious circumllance, tiiat the firft attack of 
 
 thefe complaints was produced by an afTcfiion of the 
 
 mind, and every future return of anj' coniequence arofe 
 
 h fro!n the fame caufe ; and although bodily exercile, or 
 
 ■ dillention of the ftomach, brouglit on (lighter afTeftions, 
 
 it ftill required the mind to be affefted to render them 
 
 fevere ; and as his mind was irritated by trifles, thefe 
 
 produced the moft violent effefts on the <lifeafe. His 
 
 coachman being beyond his time, or a fervaut not at- 
 
 I tending to his diredions, brought on the fpafms, while 
 
 a real misfortune produced no effeft. 
 
 Mr Hunter was of a (hort ftature, uncommonly ^rong 
 and afclve, vciy compaelly made, and capable of great 
 bodily exertion. His countenance was animated, open, 
 and in the latter part of his life deeply imprelfed with 
 thought fulnefs. When his print was Ihewn to Lavater, 
 he faid, " That man thinks tor himfelf." In his youth 
 he was cheerful in his difpofition, and entered into 
 youthful follies like others of the fame age ; but wine 
 never agreed with his ftomach ; fo that after fome tinTt 
 he left it off altogether, and for the laft twenty years 
 drank nothing but water. 
 
 His temper was very warm and impatient, readily 
 provoked, and, when irritated, not ealily foothed. His 
 difpofition was candid, and fieC from referve, even to a 
 fault. He hated deceit ; and as he was above every 
 kind of arliiic«, he detetled it in others, and too open- 
 ly avowed his fentiments. His mind was uncommi'uly 
 aftive ; it was naturally foniitd for invelligation, and 
 that turn difplayed itfelf on the moll trivial occafiour., 
 and always with mathematical exaclnefs. What is cu- 
 rious, it fatigued him to be long in a mixed company 
 which did not admit of coimecled converfatiou ; more 
 particularly during the lall tea years of his life. 
 
 He required lefs relaxation than moft other men ; 
 feidom flteping more than four hours in the night, but 
 almoll always nearly an hour after dinner ; this, pro- 
 bably, arofe from the natural turn of his mind being fo 
 nmch adapted to his own occupations, that thev were 
 in reality hii araufement, and therefore did not fatigue. 
 In private praiftice he was liberal, fcrupuloufly honell 
 iu faying what was really his opinion of the cafe, and 
 I'cady upon all occafions to acknowledge his ignorance, 
 vhenever there was any thing which he did not undcr- 
 lland. 
 
 59 ] IT Y D 
 
 In convcrfation, he fpokc too freely, and fomctiires Hunters 
 harfldy, of his contemporaries; but if he did not dojullice II 
 
 to their undoubted merits, it arofe not from er>vy, but "l'<^™"'<=" 
 from his thorough convidtion that furgen- was as yet In . 
 
 its infancy, and he himleU a novice in liis own art ; and 
 his anxiety to have it carried to perfiflion, made him 
 think memly ai.d ill of every one whole exertions in that 
 refpi-6t did not eejual his own. 
 
 HUN'l'ERS, in fortification, denote ju'cces of 
 timber, about fix inches fijuare, placed at the lower 
 end ot" the platform, next to the |)arapet, to prevent 
 the wheels of the gun-carriages from damaging the pa- 
 rapet. 
 
 HVDROGRAPHICAL Chart.c or Maps, more 
 ufually called feacharts, are projeftions of I'ome part of 
 the fea, or coail, for the ufe of navigation. In tliefe 
 are laid down all the rhumbs or points of the compafs, 
 the m'eridians, parallels, &c. with the ccafts, capes, 
 illands, rocks, (lioals-, (hallows, &c. in their proper places, 
 and jiropcrtions. 
 
 HYDROMETER, is an inftrument, of which fo 
 much has been faid in the Encycl. under that title, and 
 in the article SrKciric Gravity, that we certainly (hould 
 not again introduce it in this place, but to guard our 
 readers againil error, when lludying the works of the 
 French chemilh. Thefe gentlemen, who are fo ftror..-. 
 ly attached to every thing which is new, as to believe 
 that their anceflors have for ages been wandering in 
 the mazes of ignorance, refer very frequentlv to the 
 peft-liqueur of Baume ; and as that inftrument has ne- 
 ver been generally ufed in this country, it becomes our 
 duty to defcribe its conftruftion. 
 
 Inftead of adojiting the fimpler method of immediate 
 numerical reference to the dcnlity of water exprefitd by 
 unity, as is done in all modern tables of fpecilic gravi- 
 ty, he had recourfe to a procefs fimilar to that of gra- 
 duating the Hems of tliermometcrs from two fixed 
 points. The firft of thefe points was obtained by im- 
 merfing his inftrument, which is the common areome- 
 ter, confifting of a ball, ftcm, and counterpoife, in pure' 
 water. At th.it point uf the Warn which was interfeiled- 
 by the furface of the fluid, he marked a^ro, or the com- 
 mencement of his graduations. In the next place, he ' 
 provided a number of folutions of pur..' dry common 
 fait In water : thefe foliitions contained refpeftively 
 one, two, three, four, &c. pounds of the fait ; and in 
 each fohuiou the quantity of water was fuch, as to 
 make up the weight eqirl to one hundred pounds in 
 the wliole ; fi) that in the folution c(Hitaining one 
 pound of fait, there were ninety-nine pounds of water ; 
 in the filution containing two pounds of fait, there 
 were iiincty-eigU» jjounds of water, and fo of the reft. 
 Tlie inftrument was then plunged in the firft folulion, 
 in which of courfe it floated with a larger poitiou of 
 the fteni above the fluid, than when pure water was 
 ufed. The fluid, by the interfeftlou of its furface up- ' 
 on the (lem, indicated the place for making his firft 
 degree ; the fame operation repeated, with the fluid 
 conSaluIng two pounds of fait, indicated the mark f<..r 
 the fecond degree ; the folution of three pounds afl^ord- 
 ed the third degree ; and in this manner his enumera- 
 tion was carried as far as fifteen degrees. The firft 
 fifteen degrees afterwards, applied with the conipaflTes 
 repeatedly along the ftem, ferving to extend the gradua- 
 tion as far as eighty degrees, if required. 
 
 This inftrumciTt, which is-applicable to the admea- 
 
 furemcaf
 
 H Y D 
 
 furement of denfities exceeding that of pure water, is 
 commonly diftinguirtied by the name of the Hydrome- 
 ter for falls. 
 
 The hydrcimeter far fpirits is conflni£led upon the 
 fame principle ; but in this the couiiterpoife is fo ad- 
 jutted, that mofl part of the item rifes above the fluid 
 whca imnierfcd in pure water, and the graduations to 
 cxprefs inferior denfities are contiaucd upwards. A 
 folution often parts by weight of fait in ninety pans 
 i)f pure water, affords the firft point, or zero, upon the 
 1km ; and the mark indicated by pure water is called 
 
 [ 760 ] 
 
 H Y G 
 
 weighed, when brought to a red heat, 175 grains, and, Hy^rom*. i 
 when faturatcd witii water, 247 : it had therefore im- '■"■ 
 bibed, between complete drynefs and the point of com- '""^ "' 
 plete moillure, 72 grains of water. Lowitz fulpended 
 a round thiti plate of this flate at the end of a very de- 
 licate balance, faftcned within a wooden frame, and fuf- 
 pended at the other aim a chain of filver wire, the end 
 of which was made fall to a Aiding nut that moved up 
 and down in a fmall groove on the edge of one fide ot 
 the frame. He determined, by trial, the polition of 
 the nut when the balance was in equilibrio and when it 
 
 the tenth degree ; whence, by equal divilions, the re- had ten degrees of over-weight, and divided the fpace 
 
 niaining degrees are continued upwards upon the ftem 
 a<! far as the fiftieth degree. 
 
 Thefe experiments, in both cafes, are made at the 
 tenth degree of Reaumur, which anfwers very nearly 
 to fifty-five of Fahrenheit. 
 
 HYDRUS, or Water Serpent, one of the new 
 fouthern conflellations, including only ten ftars. 
 
 HYGROMETER, is an inftrument of fo much 
 importance to the meteorologift, that it becomes us to 
 
 between thefe two points into ten equal parts, adding 
 fuch a number more of thefe parts as might be necef- 
 fary. When the (lone was fufpendcd from the one arm 
 of the balance, and at the other a weight equal to 175 
 grains, or the weight of the flone when perfectly dry, 
 the nut in the groove fhewed the excefs of weight in 
 grains when it and the chain were fo adjulled that the 
 balance flood in equilibrio. A particular apparatus on 
 the fame principles ss a vernier, applied to the nut, 
 
 give fome account of every improvement of it which fhewed the excefs of weight to ten parts of a grain 
 
 has fallen under our notice. In the Encyclopedia, the Lowitz remarked that this hygrometer in continued 
 
 principles upon which hygrometers are conftructed have wet weather gave a moifture of more than j 5 grains. 
 
 been clearly flated, and the defefts of each kind of hy 
 gromcter pointed out. 
 
 Inflead of hairs or cat-gut, of which hygrometers 
 of the firfl kind are commonly made, Caffebois, a Be 
 nedidine monk at Mentz, propofed to make fuch hy 
 gromcters of the gut of a filk-worm. When that in 
 
 and in a continued heat of 113 degrees of Fahrenheit 
 only 1 1- degree of moiflure. 
 
 The hygrometer thus invented bv Lowitz was, hovir. 
 ever, attended with this fault, that it never threw off 
 the moillure in the fame degree as the atmofphere be- 
 came drier. It was alfo fometimes very deceitful, and 
 
 fed is ready to fpin, there are found in it two vefTels announced moillure when it ought to have indicated 
 proceedincr from the head to the ftomach, to which that drynefs had again begun to take place in the at- 
 
 they adhere, and then bend towards the back, where ~ -i"-' "t" -J -' <"- - - ' '^' '•^ ' 
 
 they form a great many folds. The part of thefe vef- 
 I'els next the ftomach is of a cylindric form, and about 
 a line in diameter. Thefe velTcls contain a gummy fort 
 of matter from which the worm fpins its filk ; and, 
 thour-h they are exceedingly tender, means have been 
 deviled to extraifl them from the infecl, and to prepare 
 them for the above purpofe. When the worm is a- 
 bout to fpin, it is thrown into vinegar, and fuffered to 
 remain there twenty-four hours ; during which time 
 
 mofphere. To avoid thefe inconveniences, M. Hoch- 
 heimer propofes the following method : 
 
 I. Take a fquarc bar of fleel about two lines in 
 thicknefs, and from ten to twelve inches in length, and 
 form it into a kind of balance, one arni. of which ends 
 in a fcrew. On this fcrew let there be fcrewed a lead- 
 en bullet of a proper weight, inftead of the common 
 weights that are lufpcnded. 2. Take a glals plate 
 »(" out ten inches long, and feven inches in breadth, de- 
 Itroy its polifh on both fides, free it .from all moillure 
 
 the vinegar is abforbed into the body of the infeft, and by rubbing it over with warm alhes, fufpend it at the 
 
 coagulates its juices. The worm being then opened, other end of the balance, and bring the balance into 
 
 both the veffels, which have now acquired ftrength, are equilibrium by fcrewing up or down the leaden bullet, 
 
 extraded ; and, on account of their pliability, are ca- 3. Mark now the place to which the leaden bullet is 
 
 pable of confiderable extenfion. That they may not, brought by the fcrew, as accurately as poffible, for the 
 
 however, become too weak, they are ftretched only point of the greatcft drynefs. 4. Then take away the 
 
 to the lenn-th of about fifteen or tweiity inches. It glafs plate from the balance, dip it completely in water, 
 
 is obvious that they mufl be kept fufficiently extended give it a (liake that the drops may run off from it, and 
 
 till they are completely dry. Before they attain to wipe them carefully from the edge. 5. Apply the 
 
 that ftate, thev mud be freed, by means of the nail of glals- plate thus moiflened again to the balance, and 
 
 the finger, from a flimy fubftance which adheres to bring the latter into equilibrium by f-rewing the leaden' 
 
 them. Such a thread will fuftain a weight of fix bullet. Mark then the ^dace at whicli the bullet Hands 
 
 pounds without breaking, and may be ufed for an as the highell degree of moifture. 6. This apparatus 
 
 )iv 'Urometer in the fame manner as cat-gut ; but we is to be fufpendcd in a fmall box of well dried wood. 
 
 confefs that we do not clearly perceive its fuperio- 
 rity. 
 
 To an improvement of the hygrometer conftrufted 
 on the third principle, ftated in the Encydopxdia, M. 
 Hochheimer was led in the following manner : 
 
 Mr Lowitz found at Dmitriewfk in Aftracan, on 
 the banks of the Wolga, a thin bluifh kind of flate 
 
 which attraded moifture remarkably foon, but again fmall holes on all the four fides, to give a free palTage 
 iruffcred it as foon to efcape. A plate of this flate to the air ; and to prevent moifture from penetrating 
 
 into 
 
 fufiiciently large to fuftcr the glafs plate to move up 
 and down. An opening m\ill be made in the lid, ex- 
 adly of fuch a fize as to allow the tongue of the ba- 
 lance to move freely. Parallel to the tongue apply a 
 graduated circle, divided into a number of degrees at 
 plcafure from the highefl point of drynefs to the high- 
 etl degree of moifture. The box mufl be pierced with
 
 HYP 
 
 C 76f 1 
 
 HYP 
 
 Jtyiftni*- intc) the woo4 by rain, when it may be rfquiilte to ex- 
 '"■• pofe it at n window, it mull either be lackcrcJ or 
 ^"" '"—"^ painted. To fave it at all times from rain, it may bt 
 covered, however, with a fort of roof fitted to it in the 
 rioft convenient manner. 15nt all thefe external appen- 
 dages may be improved or altered as may be found nc- 
 ceiTarv. 
 
 HYPEftBOLA Deficient, is a curve having only 
 
 one afymptotf, thoufjh two hyperbolic legs runnhig eiit Mrpnn»- 
 inlinitely bvtiie fide of the afymptote, but con'nay ways, . ' *'"' ^ 
 
 HYPOTRACHELION, in Architeduie, is ulcd * 
 for a little frize in the Tiifcan and Doric capital, be- 
 tween the aftragal and annulets ; called alfo tlie cokrin 
 and gorgcrin. The word is applied by fome aiithois 
 in a more general fonfc, to the neck of any column, or 
 that part of its capital below the allragal. 
 
 I. 
 
 Jaco'inf. JACOBINS, in the language of the prefent day, i:) 
 •— V— — ' "^ the name aflumed, at the beginning of the French 
 revolution, by a party in Paris, which was outrageouf- 
 ly democratical, and fanatically impious. This party, 
 which conlilled of members of the National Alfembly, 
 and of others maintaining the fr.me opinions and purtu- 
 ing the fame objtds, formed itfelf into a club, and held 
 its meetings in the hall belonging to the Jacobin friars, 
 ■where meafures were fecretly concerted for exciting in- 
 furreflions, and over-awing at once the legiflature and 
 the king. The name o^ 'Jacobin, though it was derived 
 from the hall where the club fit 11 met, has fince been 
 extended to all who are enemies to monarchy, arifto- 
 cracy, and the Chriftian religion ; and who would have 
 tvery man to be his own prieii and his own lawgiver. 
 Hence it is, that we have Jacobins in Great Britain and 
 Ireland, as well as in France. 
 
 Of the proceedings of the French Jacobins, fome ac- 
 count has been given in the Eiicyclopailia, under the ti- 
 tle Revolution ; and the fiibjeft will be refumed in 
 this Supphmtiit under the fame title. The purpoie of the 
 prefent article is to trace the principles of the feft from 
 their fo'urce ; for thefe principles are not of yellerday. 
 
 " At its very firft appearance (fays the Abbe Bar- 
 ruel), this feft counted 300,000 adepts ; and it was 
 fupported by two millions of men, fcattered through 
 France, armed with torches and pikes, and all the fire- 
 brands of the revolution." Such a wide fpread con- 
 fpiracy could not be formed in an inftant ; and indeed 
 tin's able writer has completely proved, that this feift, 
 with all its confpiracies, is in itfelf no other than " the 
 coalition of a triple feft, of a triple conlpiracy, in which, 
 long before the revolution, the overthrow of the altar, 
 the ruin of the throne, and the diflblution of all civil 
 fociety, had been debated and determined." 
 
 It is known to every fcholar, that there have been 
 in all ages and countries men of letters and pretenders to 
 letters, who have endeavoured to fignalize themfelves in- 
 dividually by writing againft the religion of their coun- 
 try ; but it was referved for the philofophills (a) of 
 France to enter into a combination for the expreis pur- 
 pofe of eradicating from the human heart every religi- 
 ous fentiment. The man to whom this idea firil ocur- 
 
 SuppL. Vol. I. Part II. 
 
 red was Voltaire ; who, daring to be jealous of his God, Jacol)in! 
 and being weary, as he faid himfelf, of hearing people ' v 
 repeat that twelve men were fufficient to eftablilh Clirif- 
 tianity, refolved to prove that one might be fufficient to 
 overthrow it. Full of this project, he fwore, before the 
 year 1730, to dedicate his life to its accomplilhment ; 
 and for fome time he flattered himfelf th?t he (hould 
 enjoy alone the glory of dellroying the Chrlilian reli- 
 gion. He found, however, that alTociates would be ne. 
 ceffary ; and from the numerous tribe of his admirers 
 and difciples, he cliofe D'Alembert and Diderot as the 
 moft proper perfons to co-operate with him in his de- 
 iigns. How admirably they were qualified to aft the 
 part affigned them, may be conceived fnfm the life of 
 DiDEP.OT in this Suppltmeiit. But Voltaire was not fa- 
 tisfied with their aid alone. 
 
 He connived to embark in the fame caufe Frederic 
 II. of Prufiia, who wifhed to be thought a philofopher, 
 and w ho of courfe deemed it expedient to talk and write 
 againll a religion which he had never Ifudied, and into 
 the evidence of which he had probably never deigned to 
 inquire. This royal adept was one ot the moft zealous 
 of Voltaire's coadjutors, till he difcovered that the phi- 
 lofophifts were waging war with the throne as well as 
 with the altar. Tliis indeed was not originally Vol- 
 taire's intention. He was vain ; he loved to be careffed 
 by the great ; and, in one word, he was, from natural 
 difpofition, an arlllocrate and admirer of royaky : But 
 when he found that almoll every fiJvereign but Ficde- 
 ric, difapproved of his impious projedis as foon aj- /; 
 pcrcel-ved their iffiie, he determined to oppofe all the go- 
 vernments on eyrth, rather than forfeit the glory, witk 
 which he had flattered himfelf, of vanquifiiing Chriil 
 and his apoftles in the field ot controverfy. 
 
 He now fet himfelf, with D'Alembert and Diderot, 
 to excite univerfal difcontent with the eftablifhcd order 
 of things. This was an employment entirely Ailted to 
 the.ir difpofition ; for not being in any fenfe ^reat them- 
 felves (b), they wilhed to pull all men down to their 
 own level. How cfFeftually they contrived to convert 
 the Er.cyclopeclli into an engine to fcrvc their purpofcs, 
 has been Ibewn already ; but it was not their only nor 
 their moft powerful engine ; they formed fccret focie- 
 5 D ties. 
 
 (a) This term was invented by Abbe Barruel, and we have adopted it, as denoting fomething very different 
 from the meaning of the woxA philofopher. 
 
 (b) We do not by this mean to infinuate that D'Alembert was not a man of fcience. He was perhaps the 
 only man of fcience in that gang ; but he was a mafter of no fciei.cc but nrallitmatics ; and his birth being ob- 
 
 Icure,
 
 J A C [7 
 
 jacobins. tifg^ a.Tjmed new names, and employed an Enigmatical 
 ' language. Thus, Frederic is called Luc : D'Alcmbert, 
 
 Protagrras, and fr.metimes Bertrand ; Voltai.e, Raton; 
 and Diderot, Pla:on, or i;s anagram Tonphi ; while the 
 geneial term for the cont; irators is Cjcoii^;. In their 
 fecrct meetings they profcfled to cek'oi-ate the myllerics 
 of Mythra ; and their great object, as they profelTcd to 
 cne another, was to confou.id the wretch, niL-aning j — 
 C — . Voltaire propofcd to tftabliih a col luy of philo- 
 fophiftf at Cleves, vho. proiefttd by the king of Pnif- 
 fia, might publifh their opinions without dread or dan- 
 ger ; and Frederic was diipofed to take them under his 
 protcftion, till he dilcovered that their opinions were 
 anarchical, as well as impious, when he threw them off, 
 and even wrote againft tbem. 
 
 They contrived, however, to engage the minifters of 
 the court of France in their favour, by pretending to 
 have nothing in view but the enlargement of fcience, in 
 works which fpoke indeed refpectfully of revelation, 
 while every difcovery which they brought forward was 
 meant to undermine its very foundation. When the 
 throne was to be attacked, and even when barefaced a- 
 theifm was to be promulgated, a number of impious and 
 licentious pamphlets were difperfed, for fome time none 
 knew how, from a fecret focicty formed at the Hotel 
 d'Holbach at Paris. Thefe were fold for trifles, or dif- 
 tributed gratis to fchoolmafters, and others who were 
 likely to ciixulate their contents. D'Alembert, Dide- 
 rot, and Condorcet, who was now aflociated with the 
 other confpirators, flattered the ambition of every man 
 among the great, and efpecially of the Duke d'Orleans, 
 the richell fubjeft in Europe, and a prince of the blood 
 of France. The fini and the 'aft of thefe three adepts 
 had, by their mathematical knowledge, got fuch an af- 
 cendancy in the Royal Academy of Sciences, that they 
 could admit or exclude candidates as they knew them to 
 be friendly or inimical to the projefts of the confpira- 
 tors ; and they had contrived, by matchlefs addrefs and 
 unwearied perievcrance, to fill almoft all the feminaries 
 ©f education with men of their own principles. 
 
 Thus was the public mind in France completely cor- 
 rupted, when the mafon lodges, over which the infa- 
 mous Orleans p'-efided, were vifited by a delegation from 
 the German illuminati ; and nothing more was neceffa- 
 ry to produce the fett oi yacoLins, by whofe intrigues 
 and influence, France, as M. Barrupl exprefles himfelf, 
 has become a prey to every crime. It was by the ma- 
 chinations of this feft that its foil was flained with the 
 blood of its pontiflFs and priefts, its rich men and nobles; 
 with the blood of every clafs of its citizens, without re- 
 gard to rank, age, or fex. Thefe difciples of Voltaire 
 were the men who, after having made the unfortunate 
 Louis, his queen, and fifter, drink, to the very dregs, 
 the cup of outrage and ignominy during a long confine- 
 ment, folemnly murdered them on a fcaffold, proudly 
 menacing all the fovereigns of the earth with a fimilar 
 fate. Yet think not, indignant reader, that the ways 
 of Providence are unequal. The nations of Europe 
 were ripe for challifement ; and that chaftiftment thefe 
 villains were employed to inflict : but their own punifh- 
 ment did not linger. Voltaire died in a^jonies of de- 
 
 62 ] JAG 
 
 rponding remorfe, which can be exceeded only by the 
 torments of the damned. There is reafon to believe 
 that the end of D'Alembert and Diderot very much re- 
 femblcd that of their leader ; while the more hardened 
 adept, Condorcet, became his own executioner ; and 
 the other chiefs of the rebellion have regularly inflifted 
 vengeance on each other, every alteration of the French 
 conllitution (and thefe alterations have beert many) be- 
 ing followed by the execution of thofe by whom the 
 government was previoufly adminil^ered. 
 
 JAGHIIIE, aflignment made in Bengal by an Im- 
 perial grant upon the revenue of any diltric^, to defray 
 civil or military charges, pcnfions, gratuities, Sec. 
 
 JAGHIREDER, the holder of a Jaghire. 
 
 St JAGO, the largcrt and moft populous of the Cape 
 de Verde Iflands, of which fome account has been gi- 
 ven in the Encyclopj:dia, is reprefented by Sir George 
 Staunton as liable to long and excefTive droughts, for 
 which no philofophical caufe can be affigntd. When 
 the embafly to China touched at it in the latter end of 
 1792, it was in a ftate of abfolute famine. Little or no 
 rain had fallen for about three years before. The rivers 
 were almoll all entirely dry. The furface of the earth 
 was, in general, naked of any herbage. The greatelb 
 pai-t of the cattle had perillicd, not lefs through drought 
 than want of food. Of the inhabitants many had mi- 
 grated, and many were famiflied to death. Nor was this 
 calamity peculiar to St Jago. All the iflands of Cape 
 de Verde were faid to have experienced the fame long 
 drought, and to be confequently in a ftate of fimilar de- 
 folation. Yet the frequent fliowers which were obfer- 
 ved by the firft navigators who touched at St Jago, in- 
 duced them to give to the ifland the name of Pluiualis ^ 
 and no change had been obferved in the fteady current 
 of wind, blowing from the eaft, which is common to 
 tropical climites. 
 
 " What were the uncommon circumftances (fays Sir 
 George) that took place in the atmofphere of tl^at part 
 of Africa to which the Cape de Verde iflands He conti. 
 guous, or in the vaft expanle of continent extending to 
 the eaft behind it, and from which this direful effeft 
 muft have proceeded, as they happened where no man of 
 fcience exifted to obferve or to record them, will there- 
 fore remain unknown ; nor is theory bold enough to 
 fupply the place of obfervation. Whatever was* the 
 caufe which thus arrefted the bountiful hand of Nature, 
 by drawing away the fources of fertihty, it was obfer- 
 vable, that fome few trees and plants perfevercd to flou- 
 rifh with a luxuriance, indicating that they ftiU could, 
 extradl from the arid earth whatever portion of humi- 
 dity it was neceflary to derive from thence for the pur- 
 pofe of vegetable life, though it was denied to others." 
 
 Btfide the trees of the palm kind, which are often 
 found verdant amidft burning lands, nothing, for ex- 
 ample, could be more rich in flavour, or abound more 
 with milky, though corrofive juice, than the afclepias- 
 gigantea (fee Asclepias, Encycl.), growing plenti- 
 fully, about feveral feet high, without culture, indeed,, 
 but undifturbed, it being of no avail to cut it down ia 
 favour of plants that would be ufefnl, but required the 
 aid of more moifture from the atmofphere. The jatro- 
 ^^^ pha. 
 
 fcure, if not fpurious, and abftraft mathematics not furnifhing ready accefs to the great, his ideasj when compa. 
 red with Voltaire's, were grovelling, and (as M. Barruel fays) he was afraid to be feen.
 
 JAG r 1<^^ ] . J A L 
 
 pha ciirc39, or phyfic nut tree, wliich tlie French Wtd who received them with the mod cordial hofpitality in Jil"T«- 
 
 Indians, with fomc propriety, call lo'is immortel, and 
 plant, on that account, in the boundaries of their cftatfs, 
 appeared as if its perpetuity was not to be aficfted by 
 any drought. Fotne indigo plants were ftill cultivated 
 with luccefs in (haded vales, togetiier with a few tot- 
 ton flirubs. Tludughont the country fome of thofe 
 fpecies of the mimofa, or fenrillve plant, which grow 
 
 his lioufe, and treated them with every fj>«cies of tropi- 
 c<il fruits from his garden, lying on each file the river. 
 He had been a navigator ; and informed them that 
 the ifle of Brava, one of the Cape de Verde's, was a 
 filter and later place for flii])s to call at for water and 
 provifioiis than the ifland of St Jago ; that it had three 
 haibours: one called Puerto I'urno on the call fide of 
 
 into the fize of trees, were moll common, and did not the ifland, from which veffels mull warp, or be towed 
 
 appear to languifh. In particidar fpots the annona, or out by boats ; the Puerto Fajendago to the wert ; and 
 
 fugar apple tree, was in perfed verdure. The boradus, the Puerto Ferreo to the fouth, which was the bed for 
 
 or great fan palm, lifted, in a few places, its lofty head large (hips, and into which runs a fniall river. In an- 
 
 and fpreading leaves with undiminiflied beauty. In a other of the Cape de Verde idands, called San Vicente, 
 
 Viottom, about a mile and a half liehind the town of he obferved that there was alfo a large harbour on the 
 
 Praya, was dill growing, in a healthy (late, what may north end, but that fredi water vs-as at fome dillance 
 
 be calk'd for fiye a phenomenon in vegetation, a tree from it : and there was likewife a good port at )V)na- 
 
 known to botanills by the name of adaufonia, and in vida. This information of the haibours in the ifle of 
 
 Englifli called mnnlry bread tree. The natives of St Brava was confirmed by accounts given by others to 
 
 Jago call it LaVifun ; others, baobab. Its trunk niea- Sir Erafmus Gower, who recommends to make a trial 
 
 Aired at the bafe no Itfs than j6 feet in girth ; but it 
 foon divided into two great branches, one rifing perpen- 
 dicularly, and meafuring 4^ feet in lircnmferencc ; that 
 of the other was about 26. By it dood another of the 
 fame fpecies, whnfe fingle trunk, of _^8 feet girth, at- 
 trafled little notice from the vicinity of its huge com- 
 panion. 
 
 of them. 
 
 JALOFFS, or Yai.offs, are an aftive, powerful, 
 and warlike jjeople, inhabiting great ])art of that liaft 
 of Africa which lies between the Senegal and the Man- 
 dingo dates on the (}ambia (See MandingOes in this 
 Supp/ement). Their nofes, fays Mr Park, are not fo 
 much dcprcfTed, nor their lips fo protuberant, as thofe 
 
 But the annual produce of agriculture was fcarcely of the generality of Africans ; and though their d<in is 
 
 to be found. The plains and lields, formerly prodnc- of the deeped black, they are confidered by the white 
 
 tive of corn, fugarcanes, or plaiutains, nouriflied by re- traders as the mod fightly negroes in that part of the 
 
 gular falls of rain, now bore little le'mblance of ve-geta- continent where they live. They are divided into le- 
 
 tion. Yet in the fmall number of plants which fiirvi- veral independent dates or kingdoms, which are frc- 
 
 ved the drought, were fome which, from the fpecimens quently at war with their neighbours or with each o- 
 
 fent to Europe, were found to have been hitherto un- ther. In their manners, fupcrHitions, and governnn?nt, 
 
 known. Vegetation quickly, indeeel, revived wherever, they have a greater refemblance to the Maudingoes than 
 
 through the foil, any moidiire could be conveyed. to any other nation ; but excel them in the maiiufac- 
 
 Sir George reprefents Praya, the refidence of the ture of cotton cloth, fpinning the wool to a finer tincad, 
 
 Portuguele Viceroy, as a hamlet rather than a town. It weaving it in a broader loom, and dyeing it of a better 
 
 conlids of about 100 very fmall dwellings, one (lory colour. They make very good foap, by boiling ground 
 
 high, fcattered on each fide of the plain, which extend- nuts in water, and then adding a lev of wood aflies. 
 
 ed near a mile in length, and about the third of a mile They likewife maiiufadlnre excellent iron, which they 
 
 in breadth ; and fell off, all around, to the neighbour, carry to Bondou to barter for fait. Their language is 
 
 ing valleys and to the fea. Not being commanded by faid to be copious and fignificant, and is often learned 
 
 any neighbouring eminence, it was a fituation capable by Europeans trading to Senegal. From the names of 
 
 of defence ; the fort, however, or battery, was almod their numerals, as given by Mr Park, it would appear 
 
 in ruins ; and the few guns mounted on it were raodly that their numeration proceeds by Jives, as ours does 
 
 honey-combed, and placed on carriages which fcarcely by tens. 
 held together. Our author relates the event of a religious war, which, 
 
 A party belonging to the embaffy eroded the coun- as it difplays a generofity of charader very uncommon 
 
 try to the ruins of St Jago, the former capital of the among lavages, will afford pleafure to the minds of 
 
 idand, fituatcd in the bottom of a vale, through which many of our readers. Almami Abdulkader, foverei-Tii 
 
 ran a dream, then both fmall and duggifh. On each of a Maliomedan kingdom called Foota Torra, fent to 
 
 fide of that dream are the remains of dwellings of con- Darnel, a king of the JalolTs, an imperions medage, 
 
 fiderable folidity and fize ; and the fragments of glafs commanding him and his fubjefts to embrace indantly 
 
 hidres, dill hanging from the ceilings of fome of the the faith of the prophet. The ambadador having got 
 
 principal apartments, denote the elegance or riches that admidion to the prefence of Darnel, ordered fome Bufli- 
 
 wcre once difplayed in this now deferted place. Not reens (».<•. Mahomedan negroes) who accompanied him, 
 
 above half a dozen families remain in it at prefent ; the to prefent the emblems of his milTion. Two knives 
 
 red abandoned it, or peridied. Here was dill, how- were accordingly laid before the Jalod prince, and the 
 
 ever, an attempt at a dight manufaftory of dripped cot- ambadador explained himfelf as follows : 
 ton flips, the fame as are made in the other parts of the " With this knife (faid he) Abdulkader will coiide- 
 
 idand, for the ufe of the Africans on the main, who pay fcend to fltave the head of Darnel, if Darnel will eni- 
 
 for them in daves, elejihants teeth, and that gum which brace the Maliomedan faith ; and with this other knife 
 
 is generally called arable. Abdulkader will cut the throat of Damel, if Damel re- 
 
 Amidd the ruins of St Jago, the party found a Por- fufes to embrace it: Take your choice," — Damel coolly 
 
 tugucfe, to whom one of them was recommended, and told the ambadador that lie had no choice to make : 
 
 5 D 2 he
 
 m 
 
 JAR 
 
 Jaloffs, lie neitlitT cliofe to have liis head fhaved, nor his throat 
 ■1''*- cut. And-wkh this aiiiwiT the ambaflador was civilly 
 
 * • dil'mlfr d. 
 
 AbdulkaJer took hie meafures accordingly ; and with 
 a powerful army iavaded Darnel's country. The inha- 
 bitants of the towns and villages filled up their wells, 
 deilroyed their provifions, carried oil" thtir eft'efts, and 
 abandoned their dwellinfvs, as he approached. By this 
 means he was led on from place to place, until he had 
 advanced three days journey into the country of the 
 JalofFs. He had, indeed, met with no oppofition ; but 
 his army had fuffered fo much from the icarcity of wa- 
 ter, that feveral of his men died by the way. This in- 
 duced him to dlrc(il hi;; march towarls a watering place 
 in the woods, where his men, having cjuenclicd their 
 thirft, and being overcome with fatigue, lay down care- 
 lefsly to deep among the hnfhcs. In this fituation they 
 were attacl ed by Darnel before day-break, and com- 
 pletely routed. Many of them were trampled to death 
 ;is they lay adeep by the JalofFs horfes ; others were 
 killed in attempting to make their efcape ; and a ftill 
 greater number were taken prifoners. Among the lat- 
 ter was Abdulkader him.felf. This ambitious, or ra- 
 ther frantic prince, who, but a month before, had fent 
 the threatening meflfage to Darnel, was now himfelt led 
 into his prefence as a miferable captive. The behavi- 
 our of Darnel, on this occafion, is never mentioned by 
 
 • The hiJ!o. the fmging men* but in terms of the higheft approba- 
 Tj/itnsoftlje tion ; and it was, indeed, fo extraordinary in an Afri- 
 """"-'■ can prince, that the reader may find it difficult to give 
 
 credit to the recital. When his royal prifoner was 
 brought before him in irons, and thrown upon the 
 ground, the m.agnanimous Darnel, inftead of fetting his 
 toot upon his neck, and ilabbing him with his fpear, 
 according to the cuftom in fuch cafes, addrcfied lilm as 
 follows : " Abdulkader, anfwer me this queftion. If 
 the chance of war had placed me in your fituation, and 
 you in mine, how would you have treated me ?" " I 
 would have ihruft my ipcar into your heart (returned 
 Abdulkader «ith great firmnefs) ; and I know that a 
 iimilar fate awaits me." " Not fo (fald Dame!) ; my 
 Ipear is indeed red with the blood of your fubjefts kill- 
 ed in battle, and I could now give it a deeper ftain, by 
 dipping it in your own ; but this would not build up 
 my towns, nor bring to life the thoufands who fell in 
 the woods. I will not therefore kill you in cold blood, 
 but I will retain you as my flave, until I perceive that 
 your prefence in your own kingdom will be no longer 
 dangerous to your neighbours ; and then I will confi- 
 der of the proper way of difpofing of you." Abdul- 
 kader was accordingly retained, and worked as a flave 
 for three months ; at the end of which period, Damel 
 liflened to the folicitations of the inhabitants of Foota 
 Torra, and rcftored lo them their king. Strange as 
 this dory may appear, Mr Park has no doubt ot the 
 truth of It. It was told to him at Malacotta by 'the 
 negroes ; it was afterwards related to him by the Eu- 
 ropeans on the Gambia ; by fome of the French at 
 Goree ; and confirmed by nine flaves, who were taken 
 prifoners along with Abdulkader by the watering place 
 in the woods, and carried in the fame fhip with him to 
 the Weil Indies. — Such generofity as this reflefts ho- 
 nour on human nature. 
 
 JARRA, is a town of confiderable extent in the 
 Moorifli kingdom of Ludamar in Africa. The houfes 
 
 [ 764 ] 
 
 I C E 
 
 are built of clay and Hone intermixed, a kind of wall Hilt, 
 very common in many parts of Scotland, where clay is 'f'heufe. 
 made to iupply the ]>lacc of mortar. The greater part ' 
 of the inhabitants of Jarra are Negroes from the bor- 
 ders of the fouthern ilates, who prefer, fays Mr Park, 
 a precarious protcftion under the Moors, which they 
 purchafe by a tribute, to the being continually expofed 
 to their predatory hollillties. The tribute which they 
 pay is confiderable ; and they manifcll the moll unli- 
 mited obedience and fubmiflion to their Moorifli fupe- 
 riors : by whom they are, in return, treated with the 
 utmoft indignity and contempt. The Moors in this, 
 and the other dates adjoining the country of the Ne- 
 groes, referable in their perfons the Mulattoes of the 
 Well Indies, and feem to be a mixed race between the 
 Moors, properly fo called, of the north, and the Ne- 
 groes of the fouth ; pofTcfling many of the worft qua- 
 lities of both nations. Jarra is fituated in 15° 5' N. 
 Lat. and 6" 48' E. Long. 
 
 IBIS. Under the generic name Tantalus (En- 
 cycL), we have dtfcribed, after Mr Bruce, a bird which 
 he found in Abyffinia, and concluded to be the facred 
 ibis of ancient Egypt. M. Vaillant, during his lalt 
 travels in Africa, found, in fome lakes near the ele- 
 phants river, a bird very different from Mr Bruce's, 
 which he confidered as belonging to the fame fpecies ; 
 and which he defcribes thus : It is three feet in height. 
 Its head and throat, which are extremely bare, are co- 
 vered with a flvln of the brighteft red, terminated by a 
 band of a beautiful orange, which feparates the naked 
 part from that covered with feathers. The upper part 
 of the wings, having broad ftripes of a fine violet co- 
 lour, agreeably (haded, is bordered by a white band of 
 feathers, the thick and filky beards of which, feparated 
 from each other, have a perfeft refemblance to a rich 
 fringe. The quills of the wings and tall are of a green- 
 
 light 
 
 in a more 
 
 i(h black, which, as it receives the 
 or Icfs oblique direction, affuines the appearance of 
 violet or purple. The rcU of the plumage is of a beau- 
 tiful white. The bill, which is long and fomewhat 
 crooked, is yellow ; as are the feet. This bird belongs 
 to the genus of the ibis, of which we are already ac- 
 quainted with feveral fpeclcs. 
 
 ICE-Hot'sc. See that article, Encychpsdia. Pro- 
 feffor Beckmann, in the third volume of his Hiftory of 
 Inventions, has proved clearly that the ancients were 
 well acquainted with what ferved the purpofe of ice- 
 houfes. 
 
 " The art (fays he) of preferving fnow for cooling 
 liquors during the fummer, in warm countries, was 
 known in the earliefl ages. This praftice is mention- 
 ed by Solomon *, and proofs of it are fo numerous in « Pfcveris. 
 the works of the Greeks and the Romans, that it isxiv. 15. 
 unnecefTary for me to quote them, efpecially as they 
 have been colledled by others. How the repofitorfes 
 for keeping it were conftrufted, we are not exprefsly 
 told ; but it is probable that the fnow was preferved in 
 pits Or trenches. 
 
 '*' When Alexander the Great befieged the city of 
 Petra, he caufed 30 trenches to be dug, and filled witlt J 
 
 fnow, which was covered with oak branches ; and which " 
 
 kept in that manner for a long" time. Plutaicli fays^ 
 that a covering of chaff and coarfe cloth is fiifficient ; 
 and at prefent a like method Is purfued in Portugal. 
 Where the fnow has been colledled in ^ deep gulph, 
 
 foBife
 
 Ichnogra. 
 
 Jobb. 
 
 J E B [ 765 ] J E B 
 
 fome grafs or green fods, covered with dung from the James Torkington, reftor of Little Stukelcy, in Hun- 
 
 flieep pens, is thrown over it ; and under tbefe it is fo tingdonlhire, and of lady Dorothy Shcrard, daughter^ 
 
 ^ well preftrved, that the wliole fummer through it is of Philij), fecond earl of Ilarborough. 
 fent the djftance of 60 Spanifh miles to Lifbon. Early in the year 17()i;, Mr Jehb, together with 
 
 "When the ancients, therefore, wiihed to have cooling the Rev. Robert Thorpe, fellow of Pctcrhoufe, and 
 
 liquors, they either drank the melted fnow, or jiut fome the Rev. George WooUlon, fellow of Sidney college, 
 
 of it in their wine, or they placed jars filled with wine jiubliihed, in a fniall ([unrto, a comment on thofe parts of 
 
 in the fnow, and fuffered it to cool there as long as they Sir Ifaac Newton's Principia which more immediately 
 
 thought proper. That ice was alfo prefcrved for the relate to the fyftem of the world. The title of the joint 
 
 like purpofe, is probable from the teftimony of various work of thefe able and judicious ]>liilofophers was, 
 
 authors ; but it appears not to have been ufed fo much " Excerpta quasdam e Newtoni principiis philofophia; 
 
 in warm countries as in the northern. Even at -prefent naturalis, cum notis variorum." A work, of which 
 
 fnow is employed in Italy, Spain, and Portugal ; but in the univerfity of Cambridge continues to bear teflimo- 
 
 Perfia ice. I have never any where found an account ny to the excellence, by the general ufe of it in the 
 
 of Grecian or Roman ice-houfes. By the writers on fourfe of academical education, 
 agriculture they are not mentioned." Mr Chappelow profcHbr of Arabic, dying on the 
 
 ICHNOGRAPHY, in architefture, is a tranfverfe 14th of January 1768, Mr Jtbb offered himiclf a can- 
 or horizontal feftion of a building, exhibiting the plot didate for the vacant chair; but it was given to Dr 
 of the whole edifice, and of the feveral rooms and apart- Hallifax, afterwards bifhop of Gloucefter ; a man of de- 
 ments in auy ftory ; together with the thicknefs of the ferved celebrity, of whom we regret that it was not in 
 walls and partitions ; the dimenfions of the doors, win- our power to give a biographical (ketch. 
 dows, and chimneys ; the projeftures of the columns and On July 10. i 769, Mr Jebb was inllituted to the vica- 
 
 piers, with every thing vifible in fuch a fe<5tion. 
 
 JEBB (John), was born in Soulhampton-ftreet, Co- 
 vent Garden, London, on the 16th of February 1736. 
 
 rage of Flixton, near Bungay, in Suffolk, on the prcfen- 
 tation of William Adair, Eiq. of Flixton-hall ; and on 
 the 4th of April 1770, was inftituted to the united 
 
 He was the eldell fon of the Rev. John Jebb, dean of reftories of Momersfield and St Crofs, paridies conti- 
 
 Cafhel, in the kingdom of Ireland. He received the guous to Flixton, upon the fame prefentation : being 
 
 elements of his education in different fchools, and was alfo, in the fummer of the fame year, nominated chap- 
 
 admitted, July 7. 1753, penfioner in- the uiu'verfity lain to Robert earl of Harborough. In confequence 
 
 of Dublin, whence he removed, November the 9th of the accefiion of thefe preferments, though not con- 
 
 I 754, to St Peter's college in Cambridge, where he was fiderable in themfelves, he refigned, fome time in the 
 
 likewife a penfioner. In January 1757 he proceeded tothe month of Oftober 1771, the reclory of Ovington, 
 
 degree of B. A. and his place in the diftribution of acade- which he had received from the univerfity; and Mr 
 
 mical honours was, on that occafion, fecond wrangler, the Shecpflianks, fellow of St John's college, was elcfted in 
 
 late eminent mathematician Dr Waring being the firil. his place. 
 
 In 1758 he obtained the fecond prize of fifteen gui- Dr Hallifax fucceeding to the prefcfforfliip of civil 
 
 neas, annually given by the univerfity to the authors law, in the month of Ottober 1 770, upon the death of 
 
 of the bed compofitions in Latin profe, being fenior Dr Ridlington, Mr Jebb once more folicited that of A- 
 
 or middle bachelors of arts. Dr Roberts, afterwards rabic, which Dr Hallifax then vacated: but he had by this 
 
 provoft of Eton college, obtained the firft. 
 
 In the month of June 1760, Mr Jebb was ad- 
 mitted probationer fellow of St Peter's college, and 
 proceeded to the degree of Mailer of Arts at the com- 
 mencement in the fame year ; and on the fird of July 
 1761, was confirmed fellow by Dr 
 of Ely. 
 
 On the 6th of June 1762, he was ordained dea- fign Mr Jtbb t 
 
 time difplayed fuch an innovating fpirit in religion, that 
 the univerfity gave the vacant profefforfhip to Mr Cra- 
 ven, a man rcfpefted even by Mr Jebb and his friends. - 
 Early in the year 1771, a defign was formed of ap- • 
 plying to parliament for relief in the matter of fub-- 
 Mav.-lon, biihop fcription to the liturgy, and thirty-nine articles of' the- 
 Church of England ; and in the profecution of this de- 
 
 a very aftlve part. He attended 
 
 con at Bugden by Dr John Green, bifliop of Lin- different meetings of the difcortcnted clergy, iield at the 
 
 coin ; and on the 25tli of September, 1763, he was Feathers tavern, London, affilled in the drawing up of 
 
 admitted by the fame biihop into prieft's orders. their petition, and wrote their circular letter, which 
 
 On the 22d of Auguft, 1764, Mr Jebb was col- gave to the public an account of their aims. He bu- 
 
 lated by Dr Matthias Mawfon, bifhop of Ely, to the fied himfclf at the fame time in making various at- 
 
 fmall vicarage of Gamlingay, near Potton, in Bedford- tempts to bring about what he called a reformation of 
 
 fliire, upon the recommendation of Dr Law, mafter of the univerfity of Cambridge : but finding them fruit- 
 
 Pcterhoufe. On the 17th of the following Otlober, lefs, h.e retired, on the 25th of June 1772, to Bunga\-, 
 
 lie was eleftcd by the univerfity Into the redtory of O- where he lludied French and Italian, and proceeded in 
 
 vington, near Watton, in Norfolk, after a competition a plan of {ome political or conJUtut'wnal hdures. 
 
 with the Rev. Henry Turner, then fellow of St John's He had by this time ceafed to re;:d vhe prayers of 
 
 college, afterwards vicar of Burwell, in Cambridgefliire. the church, though he ftill continued to preach occa- 
 
 Upon cafting up the votes, there appeared to be for fionally ; and the Archdeacon of Suffolk, holding, this 
 
 Mr Jebb 91, for Mr Turner 73 ; and accordingly he year, his ufual vifitation of fome neighbouring parilhes 
 
 was inftituted into the fame the 13th of December fol. in the church of Flixton, Mr Jebb preached fuch a 
 
 lowu'g. fermon againtl fubfcriijtlon, as drew upon himfclf a 
 
 On the 29th of the fame month, (December 1764) public rebuke from the Archdeacon, in the prefence of: 
 
 Mr Jebb married AnnCt eldeft daughter of the Rev. the clergy. "Much altercation, (fays he) enfued j-. 
 
 ani 
 
 Jel'b.
 
 J E B [ 7C6 ] J E B 
 
 ~}M\ and for fome days I expefted a funimons tn Norwich ; which are cfTcntial to the dignity and to the liapp'ncrs J«''fc.. 
 
 —■,-~— jjut (lave heard no more of if. / aileri thus, luilh a of human nature." Could Dr Jebb have fovcfecu all — — \r-~ 
 
 view to call the attention of the Norwich clergy to our the mifchitfs which have flowed from this iuftitution ; 
 
 caufe ; and have in part fuccecded " could he liave forefien the wonderful fpawn of fac- 
 
 He afled much nore honourably than thi.;, when, tious focieties which have fpriuig from it as. from a 
 
 in 1775, he rell^nied all his preferments in the church ; parent llock, our veneration for genius ar.d lcariiirj»- 
 
 which furely he ought not to have retained one day will not permit us to believe, that he would have ne- 
 
 after his confcicnce would not permit him to read the girded the (Indies of his profeffion for thi fake of ta- 
 
 prayer<; of the liturgy. He now rtfolved to become a king the lead in party politics. 
 
 jjhvfician ; and after attending St Bartholomew's hof- Dr Pelit, one of the ph\f!cian3 of St Bartholj- 
 
 pital In London for fi.x months, as the pupil of Dr mew's hufpital, dying the 26th of May, Dr Jebb ofTer- 
 
 William Pitcairn, he received, im the 18th of March ed himfelf a candidate to fucceed to that appointment. 
 
 1777, a diploma of Dodfor of Phytic from the univer- The election came on the 23d of June ; when Dr Budd, 
 
 fity of St Andrews!! He did not, however, com- his antagonid, fucceeded by a great majority, 
 
 mence praftice till the 5th of February 1778 ; and even The oppofulon which was made to his eleftion at 
 
 then he continued to attend the leftures of Dr Hun-' St Bartholomew's, followed him in the winter, wLen 
 
 ter, Mr John Hunter, and Dr Higglus. On the i8th he offered himfelf at St Thomas's hofpital in the bo- 
 
 of February 1779 he was elcfted a fellow of the Royal rough. Indeed he relinquilhed his pretenfions there 
 
 Society. fooner than in the former plsce ; but for no other rea- 
 
 Dr Jebb, at the breaking out of the American war, ion than bccaufe he found that all his political prin- 
 
 liad fliewn himfelf at Cambridge a warm pariizan of ciples were likely to be again objedled to him, and to 
 
 the revolting colonies ; and of courfe a keen advocate hazard his fuccefs, 
 
 In the year 1783 he concurred with others in form- 
 ing " the focicty for promoting the knowledg of the 
 fcriptures," which met firfl: on the 2Cth of September 
 in that year, and whofe meetings continued to be held. 
 
 for what he called, and, we doubt not, thought, the 
 civil liberties of mankind. He now fignallzed him- 
 felf by " An addrefs to the Freeholders of MIddlefex," 
 affembkd at Free mafon's tavern In Great Queen-ftreet, 
 
 on Monday, December the 20th 1779, for the purpofe 'and, for ought we know to the contrary, are ftill held 
 
 of ellablifliing meetings to maintain and lupport tt>e at EfTex-houfe. The flcetch of their plan was chieriy 
 
 freedom of cleftion. Upon this occafion, he commu- written by Dr Jebb : and their objeft was to propa- 
 
 nicated to James Townfend, Efq. chainiian of that gate the doftrines of Unltarlanlfm, for which he was as 
 
 meeting, the above addrefs, under the lignature of great a zealot as for civil liberty. 
 
 " Salus Publica;" prefuming, that if the fentiments His health now began to decline; b'lt during his 
 
 appeared to be founded in reafoii, they w'ould not be confinement, he ftndied the Saxon langnage, the An- 
 
 the lefs regarded on account of tlieir being fuggelled glo Saxon laws, Englidi hiilory and antiquities, -Altha 
 
 by an unknown individual." view to examine into our criminal code, and p.irticular 
 
 This addrefs was immediately printed, and very points of liberty. The vigour of his rr.ind was llill 
 
 foon paffed through three editions, each being enlarged equal to the furnilhing himfelf vsiih this frefli {lore of 
 
 by the addition of frelh matter; and In 1782, followed knowledge ; he forefriw the advantage of fucii an ac- 
 
 the fourth edition corrected, which alfo bore our au- quifition In the invi (ligation of the legal rights of Eng- 
 
 thor's name in the title page. 
 
 About the end of February 1780, Dr Jebb was ap- 
 pointed by the committee of the county of Hunting- 
 don, one of tlif Ir deputies, to attend a meeting In Lon- 
 don of reprefentatlves from certain other petitioning 
 counties, in order to concert meafures for the more ef- 
 
 IKhmen, and had detigned to have employed it In the 
 fupport of fome great conftltutional qnellions, which 
 he conlidered as effcntlal to the freedom of his country. 
 But as the year began to dawn, it was very ob- 
 fervable to many of his friends that, according to ..'very 
 appearance, and without fume very great and fiigular 
 
 feftual reform of the prefent conftitution of the houfe effort of nature, his increafed debility would defeat 
 of commons. Soon afterwards he became one of tlie every exertion of the mod judicious medical affidance, 
 mod aftive members of " the fociety for conditntional and terminate the remaining fparks of human life. 
 
 information ;" of which the objeft, according to their 
 own account, was to diffufe throghout th-.- kingdom, 
 as univerfally as pofilble, a knowledge of the great prin- 
 ciples of conditntional freedom, particularly inch as re- 
 fpeft the eleflion and duration of the reprclentativebody. 
 "With this vlew(fav thevi, conftltutional trafts. Intend- 
 ed for the extenlion of this knowledge, and to communi- 
 cate it to perfons of all ranks, are printed and diftri- 
 buted gratis, at the expence of the fociety. EfTays, 
 a^id extrafts from various authors, calculated to pro 
 mote the fame deGgn, arc alfo publldied under the dl 
 
 In this enfeebled date, his mind was adive. His 
 " Thoughts on Prifons" were printed and circulated 
 in the county of Suffolk In 1785, by his much valued 
 friend Mr Lofft ; and there Is fufficlent reafon for con- 
 cluding that this little traft had cffeft on the delibera- 
 tions of the jnltlces at Ipfwich and Bury, then en- 
 gaged in ereftliig a new gaol for the divlfion of Ipf- 
 wich, and a new houfe of correAion for that of Bury. 
 
 The good effcfts of this very excellent traft, it 
 was apprehended, would be extended by a more general 
 publication. In this hope Dr Jebb revifed and cor- 
 
 veftion of the fociety, in feveral of the newfpapers ; refted It with his dying hand : and his furviving friend 
 
 and It is the wifh of the fociety to extend this know- 
 ledge throughout every part of the united kingdoms, 
 and to convince men of all ranks, that it is their inte- 
 reft, as well as their duty, to fupport a free conditu- 
 tion, and to ii^iiitajn and affert thofe common rights, 
 
 publlfhed it foon after his death, adding thereto " an 
 abftradt of felonies created by d?tute and other articles 
 relative to the penal law. 
 
 He continued to linger till May the 2d 1786, when, 
 about 8 o'clock in the evening, he breathed his laft, 
 
 leaving
 
 leaving Iiehind 1 in, among men (if clilRrent pjrfu.ilioiis, InipofTible to take them, fro n their woiKl..'ifiiI agilitv, Jirlioa, 
 
 very differeut charafters. By the (li'.rcnlers lie is fcl- and their evading all piirfuit by bounding into the thick- ^ J " 'cf- 
 
 dom mentioned but as the Great yel/b ; h)' churchmen, ell cover they c:in lind." * 
 
 his abilities are univerfnUy allowed, whilll regret is ex- That the Canadian, as well as the Siberian Jerboa, 
 
 pveiled that thoy were fo often employed In luppjrt of flee^js through the winter, feenis evident from a fpecimen 
 
 fiftii)^ and herefy. His moral cliaracler has never having been found, towards the end of May, inclofed 
 
 been afperfed. in a bull of clay, about tlij llze of a cricket ball, nearly 
 
 Jli^FFERSONIA, a new plant lately difcovered in an inch in thi-oknefs, perfeftly fmooth within, and about 
 
 Georgia by Dr Brickcl of Savannah, and fo named by twenty inches under ground. It was given to the G<- 
 
 him in compliment to the vice preiident of the United neval ; who proceeds thus : 
 
 States. In the Monfh'y .tft^rizinr for July 179S we " How long it had been under ground it is impofTi- 
 have the following defcription of it ; ble to fay ; but as I never could obferve thefe animsU 
 Jeffersonia pentendria monogynia. in any parts of the country after the beginning of Sep- 
 Cjlyx, below, compofed of five ihort oval imbricated ten:iber, I conceive they l;iy themfclves up fome time in 
 leaves ; corolla, monophyllous, funnel-fliiiped ou the re- that month, or beginning *>f Oflober, when the f.-f)ft be- 
 ceptacle, fvib-pentangular, bearing the filnnients near the comes lliarp ; nor did I ever fee them again before the 
 bafe, its margin hypocrateriform, divided into five round laft week in May, or beginning ot June. From their 
 durts nearly equal ; ftvle, pitiform, (horter than the pe- being enveloped in balls ot clay, witho it any appearance 
 tal, but longer than the llamens ^Jfi^ma, quadripid ; ,in- of foo I, I conceive they deep during the winter, and 
 thcrs, ereft, linear, fagittated ; fru':!, two univalved, ca- remain for that term without fuftenance. As foon as , 
 rinated, polvfpermous capfules, united at the bafe, open- I conveyed this fpecimen to my hou'V, I depofited it, as 
 ing on their tops and contiguous fides, having flat feeds, it was, in a fmall chip box, in fome cotton, waiting with 
 with a marginal wing. great anxiety for its waking; but that not taking pi: ee at 
 Only one fpecies is as yet difcovered, ycffcrfoma Jem- the feafon they generally appear, I kept it until I found 
 pervireus. It Is a (hrub with round polllheil twining it begin to fmell : I then ftuffed it, and preferved it in 
 items, which climb up on bndies and fmall trees ; tlie its torpid pofition. I am led to believe, its not recover- 
 petioles fliort, oppofite ; leaves oblong, narrow, entire, ing from that Hate arofe from the heat of mv room du- 
 evergreen, acute ; flowers axillary, yellow, having a fweet ring the time it was in the box, a fire having been con- 
 odour. The woods are full ot this delightful (hrub, ftantly burning in the Hove, and which. In all probabi- 
 which Is covered with bloflbms for many months In the lity, was too great for refpiration. I am led to this 
 year. conception from my experience of the fnow bird of that 
 JERBOA, fee Mas, Encycl, where defcrlptlons are country, which always expires in a few days (after be- 
 glven ofthejaculus or common jerboa, and of the Ara- ing caught, although it feeds perfedUy well) if expofetl 
 bian, Egyptian, and Siberian jerboas. A variety of to the heat of a room with a fire or Itove ; but being 
 this animal has lately been found in Canada by Major- nourlllied with fnow, and kept in a cold room or palfHge, 
 general Davles, F. R. S. and L. S. who fays It belongs will live to the middle of fummer." 
 to Schreber's genus of Dipus, and may be thus cliarac- JETTE, the border made round the ftilts under a 
 terifed : Dipus Canadensis palm'is lelrnilaBylls, planus pier, In certain old bridges, being the fame with flarling ; 
 pentiiihidvlis, cautLt anmilutJ uiiciique fitosa, corpcre Ion- confiiling of a ftrong framing of timber tilled with Hones,. 
 giore. The truth, however, feems to be, that it Is only chalk, &c. to preferve the four.datiuns of the piers from 
 a variety, If Indeed a variety, of the Siberian jerboa, injut'y. 
 
 The beautiful figure Indeed given by General Davles JILLIFREE is a town on the northern bank of 
 
 of the Canadian jerboa differs in fome relpeCts from our the river Gambia, oppofite to James's Ifiand, where the 
 
 figure of the SIberlcus. Its ears lie fiat and farther Englifh had formerly a fmall fort. The kingdom of 
 
 down the neck ; its belly Is not fo large ; Its toes are Barra, in which it. Is iituated, produces great plenty of 
 
 longer ; and it has no brufli at the end of the tale ; but the neceffaries of life ; but the chief trade of the Inliabi- 
 
 tlie habits of the two animals leem to be the fame. This tants Is in fait, which they carry up the river in canoes ; 
 
 will be apparent from the following extrafts of the Ge- and, in return, bring down Indian corn, cotton cloths, 
 
 neral's letter to the LInnean Society : elephants teeth, fmall quantities of Gold dufl, &c. " The 
 
 '* The firft I was fo fortumte to catch was taken in number of canoes and people conflantly employed in 
 
 a large field near the falls of Montmorenci, and by its this trade, make the king of Barra (fays Mr Park) 
 
 having ilrayed too far from the flilrts of the wood, more formidable to Europeans than any other chieftain 
 
 allowed myfelf, with the affiftance of three other gen- on the river, and have encouraged him to eflablifh thofe 
 
 tiemen, to furround it, and after an hour's hard chafe exorbitant duties, which traders of all nations are ob- 
 
 to get It unhurt, though not before It was thoroughly llged to pay at entry, amounting nearly to L. 20 on 
 
 fatigued ; which might in a great meafure accelerate its every veffel, great and fmall. Thefe duties, or cuHoms, 
 
 death. are generally collefted in perfon by the alkaid or gover- 
 
 " During the time the anin.al remained In Its ufual nor of Jillifree, who is attended by a numerous train of 
 
 vigour, its agility was incredible for fo fmall a creature, noify and troublcfome dependants, who, by their fre- 
 
 It always took progreflive leaps of from three to four, quent intercourfe with the Engliih, have acquired a 
 
 and fometlmes of five yards, although feldom above iz fmattering of our language, and beg for every iblng 
 
 or 14 Inches from the furface of the grafs ; but I have which they fancy with fuch earneflnels, that tr-.dcrs, in 
 
 frequently obferved others in fhrubby places an ' in the order to get quit of them, arc frequently obliged to 
 
 woods, amongft plantj, where they chiefly refide, leap grant the!.' requefts. I>at, 
 confiderably higher. When found in fuch places, it is weft from Greenwich. 
 
 16'. Long. 16° ic 
 ILLUMINATI
 
 ILL [ .7S8 ] ILL 
 
 ILLUMINATI 13 the name w'liich wa^ afTumed liy time a fworn enemy to the Jcfiiits, 'pd fotmdfj this I'luiilnwi 
 
 a fecret fsci.ty or order, fuunded, on tlie firft of May lodge with no other view than to form a party for him- ^— v"— ' 
 
 1776, fcy Dr Adam Wciihaiipt profeffor of canon Lnv fclf againll tliefe fatliers, who after the fnpj)rf:flion of 
 
 . in t,}ie univeifitv of Ingolfladt. The real ohjeft of this their order had been continued in their offices of public 
 
 on'.cr «sa, by ciandelllne artri, to overturn every govern-, teachers at the uniiierfity of Ingolibdt ; and this opi- 
 
 mcnt and every relio-Ion ; to bring the fciences of civil nion tin- illnminees were at pains to propajr.ite. His 
 
 life into contempt ; and to reduce uiiuikind to that ima- charafter, too, was at this ti.ne fuch as to remove every 
 
 t(!nary (tate of Nature wlien they lived independent of fafpicion from the p djlic mind. A feeming alTidnity 
 
 each other on the fpontaneous produftioas of the earth, in In'i duty, and a great (liew of zeal and erudition in 
 
 Its'avcwed objt 61, however, was very difl'erent. It pro- expounding the lawa, eafily inidec} people to believe 
 
 fcfied to diffui'e from fecret focietics, as from fo many tli.it his whole time and talents were engroflfed with the 
 
 centres, the light of fcience over the world ; to propa- ftudy of them ■; and if we are to credit his own account, 
 
 CMte the pureft principles of virtue ; and to re inflate Incrolftadt had never wltneffed a profcfTor fo well calcu- 
 
 mankind in the happinefs which they enjoyed during lated to add new luilre to its univeriity. , 
 
 the n-olden age fabled by the poets. Such an objecit This fecms, indeed, to have been the general opinion Art if th« 
 
 was well adapted to make a Seep iinpreifion on the in- as* well as his own ; for, fome time after the foundation '°''"'^'''' 
 
 geiiuons minds of youth; and to young men alone of his order, he applied himfelf with fuch diligence and 
 
 Wcifhaupt at fird addreffed birafelf. apparent candour to the duties of his ofiice, that he was 
 
 It will naturally occur to the reader, that the means chofen what Abbe Barruel's tranflator calls superior 
 of attaininc- this o-lorious objcft fhould have been made of the univerfity. This new dignity only added to his 
 as public ab poflihle ; and that the veil of fecrecy thrown hypocrify, and furnithed him with frelh tneans of carry- 
 over the proceedings of the order was calculated to ex- ing on his dark defigns. He converted his houfe intu 
 cite fufpicion, and to keep even yomig men of virtue and one of thofc boarding honfes where young men, perpe- 
 ■faeacity at a diftance. In any other country than Ger- tually under the eye of their matters, are fuppofed to 
 many fecrecy might perhaps have had this effeft ; but be better pceferved than anywhere elfe from the dangers 
 various circumftances confpired there to make it operate which threaten them at that age. He folicited fathers 
 with a powerful attraflion. and mothers to entruft their children to his care ; and. 
 
 Ever Cnce free mafonry had acquired fuch reputa- counterbalancing in fecret the leflbns which he was ob- 
 
 tion throughout Europe, a multitude of petty fecret llged to give in public, he fent home his pupils well 
 
 focleties had been foriried in the univerfities of Ger- difpofed to continue the fame career of fedudion which 
 
 many, each having its lodi;e, its malter, its myfteries, he himfelf carried on at Ingolibdt, Atrocloully im. 
 
 all inodelled on thofe founded by mafons coming from pious, w,e fee him (fays M. Barrnel), in the tirll year 
 
 England and Scotland (a). Before the foundation of of his illumiuifm, aping the God of Chrillianlty, and or- 
 
 Wellhanpt's order, thefe lodges, we believe, were in dering /Ijax, in the following terms, to propagate the 
 
 general harmlefs ; or if they were produftive of any doftrines of his new gofpel : " Did nut Chrill fend his 
 
 evil, it was only by giving the youth of the univerfities apollles to preach his gofpel to the univerfe ? You that 
 
 a tafte for fecrecy and mifticifm. Of this Welfliaupt are my Peter, why (liould you remain iille at home •' Go 
 
 availed himfelf; and as foon as he had conceived the out- then and preach." 
 
 lines of his plan, and digeded part of his fyftem, he ini- Thefe preachers had yet received no particular defig- 
 
 tiated two of his own pupils, to whom he gave the names nation ; for when his full adepts were initiated, he was 
 
 of AjAX and Tiberius, alTuming that of Spartacus far from having completed the code of his order. He 
 
 to himfelf. Thefe two difciples fuon vying with their knew that years and experience were necefTary to per- 
 
 mafter in impiety (for it will be feen by and bye that he feft that gradual fylleni of initiations and trials which, 
 
 was moll Impious), he judged them worthy of being ad- according to the plan he had conceived, his novices 
 
 mitted to his mvlleries, and conferred on them the high- were to undergo ; but he could not endure the idea of 
 
 eft degree which he had as yet invented. He called facrificing years to mere theoretic projefts ; and he 
 
 them y^«o/'7i';to, denominated this monftrousaflbciation, flattered himfelf with the hopes of fupplying the defi- 
 
 THE ORDER OF ILLUMINATI, or'^LL uM IN EES, and in- cicncics of his incomplete code by prov;iional regula- 
 
 •ftalled himfelf general of the order. tions and private inftruitioHS, and of acquiring afibciates 
 
 When public report fpread the news in Germany of who would receive his new gofpel implicitly, and co- < 
 
 this new order having been founded in the univerfity of operate with him in all his views. ^ ' 
 
 Inf^olftadt by Wellhaupt. it was generally fuppofed to At length, however, the code was completed, andThelud 
 
 be one of thole little college-lodges which could not in- the fed divided into two grand clalfes ; and each of thefe ciivule^ m. 
 
 •tereft the adepts after they had iiniihed their ftudies. again fubdivlded Into lefler degrees, proportionate to the""* " 
 
 Many even thought that Weifhaupt, who was at that progrefs of the adepts. 
 
 The 
 
 (a) Such, we are fony to fay, is the cafe ftill. In a letter, dated the loth of May 1799, which we received 
 from a o-entleman of learning and honour then refiding in Upper Saxony, is the following account of the univer. 
 fitv of Tera : " This univerfity contains from two to three thoufand ft'idents, who are almoll all republicans, 
 and go about the country in republican uniforms. They are all formed into clubs or fecret focieties ; and the 
 quarrel of one member of a club is taken up by all. The confequenee is, that the number of duels among the 
 different clubs is inconceivable. The weapon is generally the fabre, and the duei;often ends in the death of one 
 of the combatants." Yet gentlemen of Great Britain fend their fons to Germany to be educated !
 
 lUiiminati 
 
 The "Myf- 
 teriei. 
 
 6 
 
 The re- 
 cruiter, 
 
 7 
 
 ro pry in- 
 
 tlie cha- 
 adlcrs of 
 U men. 
 
 ILL [ 769 1 ILL 
 
 " Ths Jirjl clafa is that of Preparation. It con- Tlic priTons to be excluded were all Aich as would Hlumir.ati. 
 
 tmiis tour degrees, viz. thofe of Novice, ot Mincrvnl, of expofe the order to fulpicion or reproach. All iiiJif- v 
 
 Minor J/!um:/!ce, or Illmnmaliis Minor, and of Major creet talkers, all who were proved violent, and dliricull to 
 liluiniiue, or JUuminiitus Mojor. To this clafs belong be managed, all addifled to driinkennefs, and all Pagans, 
 liktvvife fimie intermediary degrees, borrowed from tree- Jews, and Jcfuits, were to be rejected. As the palron- 
 nuilbnry, as means of propagation. Of the mafonic age ot princes would tend much to enrich and ftrengthcii 
 degrees, the code of the illuminilti admits the firft three the fociety, it was agreed to adrrit them to the inferior 
 without nny alteration ; but it adapts more particularly degrees, but they were never to be initiated into the 
 to the views of the left the degree of iSfo/c/j A'n(i,'/i/, and grand niylteries ; they were never to rife beyond the 
 
 llyles it the degree of Dirc&ing Illuminee, or lUuminalui degree of Scotch knight. g 
 
 Jirigens. The perfons to be iclefled were young men of alll'e'forn 
 
 The fecond clafs is that of the Mysteries, which ftations, from eighteen to thirty ; but particularly thofe '"'' V"''' '"'' 
 are fubdivided into the leJJ'er zwA greater myjhries. The whofe education was not completed, and conlVquently ' '<"'"<='■> 
 leffer comprehend the prieflhood, and adniiniftration of whofe habits were not formed. " Seek me out (fays 
 the fed, or the degrees of^»-iiy?j, and of ?-(;5^fn/i or^Wn^w. Weifhaupt in his diredlions to the infinuator) tlie dex- 
 in the greater myjlerics are comprehended the two terous and dalbing youths. We mull; have adepts who are 
 degrees of Mugus or philofopher, and of the Man-hing. infinuating, intriguing, full of refuurce, bold and enter- 
 The eleS of the latter compofe the council and degree of prifing ; they mult alfo be flexible and traflablc, obedi- 
 Areopagites. ent, docile, and fociable " In another place he fays, 
 " In all thefe clafles, and in every degree (fays the " Above all things pay attention to the figure, and feledt 
 Abbe Barruell, there is an ofTice of the utmolt confe- the well made men and handfome young fellows. They 
 quence, and which is common to all the brethren. It are generally of engaging manners and nice feelings. 
 is that which is occupied by him who is known in the When properly formed, they are the betl adapted for ne- 
 code by the appellation of Recruiter, or Brother Itifi- gociations ; for firll appearances prepofTefs in their fa- 
 nuator. This (continues our author) is not a term of vour. It is true, they have not the depth that men of 
 my invention : it is really to be found in the code, and more gloomy countenances often have. They are not 
 is the denomination of that illuminee, whofe employ- the perfons to he enlnijlcd luith a revolt, or the care vfJUr- 
 ment is to entice members into the fed." ring up the people; but it is for that very reafon we mull 
 As the whole ftrength of the order depended upon know how to choofe our agents. 1 am particularly I'ond 
 the vigilant and fuccefsful exercife of this office, fome of thofe men whofe very foul is painted in their eyes, 
 brethren were carefully inftrufted for it, who might af- whofe foreheads are high, and whofe countenances arc 
 ter«'ards vifit the different towns, provinces, and king- open. Above all, examine well the eyes, for they are 
 doms, in order to propagate the doctrines of ijluminifm. the very mirrors of the heart and foul. Obferve the 
 Weifhaupt propofed to leleft as his apoftlcs either weak look, the gait, the voice. Every external appearance 
 men, who would implicitly obey his orders, or men of leads us to dillinguilh thofe who are fit for our fchool." 
 abilities, who would improve the office by artifices of Though young men were preferred, yet perfons of 
 their own. It was, however, a duty which every brother all ages were to be admitted if their charafter accorded 
 was obliged to exercife once or twice in his life, under with the principles of the order. The inlinuator was 
 the penalty of being for ever condemned to the lower defired to feek out thofe who were diftinguifhed by their 
 degrees. power, riches, or leariu'ng. " Spare no pains (faySTob^fe- 
 To Simulate the ardour of the brother infmuator, he Weifhaupt), fpare nothing in the acquifition of fuch duced by 
 was appointed fuperior over every novice whom he adepts. If heaven refufe its fuccour, conjure hell. whatever 
 (hould convert. To affift his judsment, he was inftruft- t^,.„ r r ai meaiiaj 
 «d in three important points concerning the defcription fl^^eref, nequeas fuperos, Achevonta moveta." 
 of men whom he ought to feleft for converfion, the Perfons were to be fingled out from thofe profeflions 
 means which he ought to employ for enticing them to which give men influence over others, or put them in 
 enter the order, and the arts which he ought to ftudy to the molt favourable fituation for dlfTemioiatijig any pe- 
 form their charafter. ^ culiar opinions. With this view, fchoolmaflers, and fu- 
 To enable the recruiter to determine whom he ought perintendants of ecclefiaflic feminaries, were to be fought 
 to fele£l for converfion, he was to infinuate hiinfelf into after with much care. Bookfellers, poll-maflers, and 
 all companies ; he was to pry into the character of all the fecretaries of poft-ofTices, were alfo to be felefted. 
 whom he fhould meet with, whether friends, relations, Thofe profeffions which accuflomed men to fpeak and 
 ftrangers, or enemies ; he was to write down all his re- argue, as that of counfellors and attorneys, and even 
 marks regularly every day ; to point out their ftrong phyficians, were alfo to be courted. " They are worth 
 and weak fides, their paffions and prejudices, their in- having (fays Weifliaupt), but they are fometimes real 
 timacies, their interefls, and their fortune. This journal devils, fo difncult are they to be led ; they are, how- 
 was to be tranfmitted twice every month to the fupe- ever, worth having when they can be gained over." 
 riors; by which means the order would learn who were Every exertion was to be made to gain the oflTicers of a 
 friendly or hoftile to their views, and who were the in- prince, whether prefiding over provinces or attending 
 dividuals to whom they ought to direft their arts of fe- him rn his councils. " He that has done this, has done 
 duftion (b). more than if he had engaged the prince hJmfelf." 
 SuppL. Vol. I. Part II. rE There 
 
 (b) As a fpecimen of the journals kept by the infmuators, and of the charadlers which the illurainees fclcfled 
 
 for
 
 Illuminati. 
 
 'Huminavi, 
 
 lO 
 
 And their 
 characters 
 tranfmitted 
 to the fupe- 
 riors. 
 
 ILL [ 770 ] ILL 
 
 There was alfo another defcription of men of whom with them, the Inruniator was firft to afcertain hi's opi- 
 
 Weilliaupt very wifely judged that they would be ad- nions upon iome leading points, by propofing to him to -~-v— ~^ 
 
 mirably fitted for the diffuffion of his doctrines. Thefe write a diifertation upon certain quellions. Should the 
 
 were the difappointed and diffatislied. " SeleiJt thofe anfvvcrs not pleafe the infinuator, he was to relinquilh 
 
 in particular (fays he) who have met with misfortunes, his prey ; but (hould tliey be fatisfactory, the candidate 
 
 not from accidents, but from fame injullice ; that is to was to be admitted to the firft degree. 
 
 fay, in other words, the difcontented ; for fuch men are When the fcleiSed viftim was young, and had not im- And youn* 
 
 to be called into the bofom of illuminifm as into their bibed any of thofe opinions which correfpondcd with men, 
 
 proper afylum. the principles of the fcct, a different method was to ba 
 
 When the infinuator has made choice of his viftim, followed. " Let your firft care (fays the legillator to 
 
 he is required to draw from his diary a view of his cha- his inlinuators) be to gain the affection, the confidence, 
 
 raCter, ojjinions, principles, and connefiions. This he and the eiteem of thofe whom yon are to entice into the 
 
 is to tranfmit to the fuperiors for their exatnination, and order. Let your whole condudt be fuch, that they fhall 
 
 that they may compare it with the diai ies which they furmife fomething more in you than you wifh to fliew ; 
 
 have already received, perhaps from different infinuators. hint that you belong to fome fecret and powerful fo- 
 
 When the choice of this infinuator is approved, the fu- ciety ; excite by degrees, and not at once, a willi in 
 
 periors determine which of the iiifinuators will be btft your candidate to belong to a fimilar fociety. Certain 
 
 qualified to perform the tjflc of feducing their candidate, arguments and certain books, which the infinuator mud 
 
 Two different methods were recommended ; one of have, will greatly contribute to laife fuch a wifh ; fuch, 
 
 which was to be employed in enticing men who were for example, are thofe wliich treat of the union and 
 
 fomewhat advanced in life or diftinguifhed by fcience ; ftrength of affociations." 
 
 the other was to be ufed in feducing young men whofe Every infinuator muft be provided with books of this 
 
 charafter was not formed. fort. But that their fuccefs might not depend folely 
 
 Properme- With men of knowledge, who had already imbibed upon books, Weifhaupt gave to his difciples a fpecimen 
 
 thods of le- the principles of modern philofophifm (for no true phi- of the artifices which tlicy might employ. The infi. 
 
 ducing men iyfop],ers ^.gre to be attempted), the infinuator was to nuator might begin by obferving, tliat a child in the 
 
 of know- gffm^g ^1,5 character of a philofopher well acquainted cradle, abandoned to itfclf, is entirely helplefs; and that 
 
 ' ^'' with the myfteries of ancient times. He was to defcant it is by the afiiflance of otiiers that it acquires ftrength ; 
 
 upon the importance of the fecret doiStrines tranfmitted and that princes owe their greatnefs and their power to 
 
 by tradition, to quote the gymnofopliifts of India, the the union of their fubjctts. Then the infinuator might 
 
 priefts of Ifis in Egypt, and thofe of Eleufis, with touch on the importance of knowing mankind, and the 
 
 the Pythagorean fchool in Greece. He was to learn , arts of governing them ; that one man of parts might 
 
 by heart certain paffages from Ifocrates, Cicei-o, and eafily lead hundreds, even thonfands, if he but knew his 
 
 Seneca, that he might have them ready upon all occa- advantages. He was next to dwell upon the defeats of 
 
 fions. He was to throw out hiiits, that thefe fecret civil fociety ; to mention how little relief a man can ob- 
 
 dodrines explained the difficult queftions concerning tain even fnwn his bell friends ; and how very neceffary 
 
 the origin and order of the univerfe, the Providence of it is for individuals to fupport one another in thefe days : 
 
 God, the nature of the foul, its immortality and future to add, that men would triumph even over heaven were 
 
 deftination ; he was to infpire them with the belief that they but united. He was to adduce as examples, the 
 
 the knowledge of thefe things would render life mure influence of the freemafons and of the Jefuits. He was 
 
 agreeable and pain more fupportable, and would enlarge to affert, that all the great events wliich take place in the 
 
 their ideas of the majefty of God: he was then to declare world depend upon hidden caufes, which thefe focietie* 
 
 that he had been iin'tiated into thefe myfteries. If the powerfully infiuence. He was to awake in the bread 
 
 candidate expreffed any curiofity to be made acquainted of his pupil the defire of reigning in fecret ; of prepa- 
 
 ring 
 
 for propagating their principles, we fiiall give the character of Zwack, denominated Cato, as it is defcribed in the 
 tablet of his infinuator Ajax (Maffcnhaufen). 
 
 «' Francis Xaverius Zwack was fon of Pliilip Zwack, commiffary of the Chamhre de Comptes, and was born al 
 Ratilbon ; at the time of his initiation (29th May 1776) he was twenty ytars of age, and had finilhed his col- 
 lege education. _ . - . . 
 
 " He was then about five feet high ; his perfon emaciated with debauchery ; his conftitution bordering on me- 
 lancholy ; his eyes of a dirty grey, weak and languifiiing ; his complexion pale and fallow ; his health weak, and 
 much hurt by frequent difordcrs ; his nofe long,' crooked and hooked ; his hair light brown ; gait precipitate ; 
 his eyes always caft towards the ground ; under the nofe, and on each fide of the mouth, a mole. 
 
 " His heart tender and philanthropic in an extaordinary degree ; but ftoic when in a melancholy mood; other- 
 wife a true friend, circumfpeCt, reftrved, extremely fecret ; often fpeaking advanlageoufiy of himfelf ; envious of 
 other people's pcrfedions ; voluptuous; eiKleavouring to improve himfelf ; little calculated for numerous affem- 
 blies ; choleric and violent, but eafily appeafed ; willingly giving his private opinions when one^ has the precaution 
 to praife him, though contradicting him ; a lover of novelties. On religion and confcience widely differing from 
 ■* the received ideas ; and thinking piecifely as he ought, to become a good member of the order. 
 
 " His predominant paffions are, pride, love of glory, probity ; he is eafily provoked ; has an extraordinary 
 propenfity for myfteries ; a perpetual cuitom of fpeaking of himfelf and of his own perfedtions ; he is alfo a per- 
 fect mafter in the arts of diffimulatlon ; a proper perfon to be received into the order, as applying himfelf parti- 
 cularly to the ftudy of the human heart." Such is the charafter of the beloved difciple of Weilhaupt, tlie in- 
 comparable Cato, and a leader of the feet of the illuminees !
 
 I t L 
 
 Period of 
 the novi- 
 ciate. 
 
 I'liiminati. ring in his clofet a new coiiftitution for the worldi and 
 of governing thofe who think they govern others. 
 
 After thcfe, or other artifices of the fame kind, have 
 been employed, if the candidate be inlpired with an ar- 
 dour to be initiated, and give fatisfaclory aiifwers to the 
 queftions propoltil to liini, he is inimedijtely admitted 
 a novice. But (honld lie rejetl all means of feduCtion, 
 let him take heed to imfclf ; " for the vengeance of fe- 
 cret foeleties is not a common veiijreance; it is the hid- 
 den file of wrath. It is irreconcileable ; and fcarcely 
 ever does it ceafe the purfuit of its victims until it has 
 feen them immolated." 
 
 The period of the noviciate varied according to the 
 age of the new convert to iihimimfm. At firll it con- 
 tinued three years for thofe under 1 8 years of age, 
 two years for thofe between iH and 24, and one year 
 for thofe who were near 33; but it was afterwards 
 fhortened. 
 
 The novice was not acquainted with any of the or- 
 der except his infinuator, under vvhofe direttion he 
 remained during his noviciate. The firlt leifons which 
 he was taught refpected the inviolable nature of the fc- 
 crecy which every illuniiiiee was obliged to obferve. 
 He was told that hlcnce and fecrecy were the very foul 
 of the order ; that ingeimoufnefs was a virtue only with 
 refpeCl to his fuperiors ; and that dillrull and referve 
 were fundamental principles. He was enjoined never 
 to fpeak of any circumllance relating to the order, con- 
 cerning his own admiffion, or the degree which he had 
 received, not even before brethren, without the ftrong- 
 eft necefTity ; and was required to fign a declaration to 
 this purpofe. 
 _ Tie novice was next taught the diAionary of the or- 
 
 geotjraphy, der, its geography, calendar, and cypher. To prevent 
 calendar, the poffibllity of difcovery, every illuminee received a 
 amiLyi lev ^^^^^ name, which was charafteriftic of his difpoiitions, 
 j^^_ or of the fervices which were expetled of him. Thus 
 
 Weifhaupt, as we have obferved, was called Spartactis, 
 becanfe he pretended to wage war agaiiill thofe opprcf- 
 fors who had reduced mankind to flavery ; and Zwack, 
 as we have feen, was named Calo, becaufe he had writ- 
 ten a diflsrtation In favour of fuiclde, and had once de- 
 termined to commit that crime. 
 
 According to the new geography of the order, Ba- 
 varia was called Achaia ; Munich was called Athens; 
 Vienna was named Rome ; Wi:rtzburg was denomina- 
 ted Carthage ; and Iiigolfladt, the fountain of the or- 
 der, was called Ephefus, and by the profound adepts 
 Ekufts. The novice had alfo to learn the Perllan ca- 
 lendar, which the order had adopted. Their era began 
 A. D. 6^0. The months received new names : May 
 \i2ii ciWclA Adarpahafcht ; June, Chardad ; July, Ther- 
 meh ; Auguft, Merdedmeh ; and {o on. The cypher 
 coiififted of numbers which correfponded to the letters 
 of the alphabet, in this order a, b, c, d, anfwering to the 
 numbers 12, 11, 10, 9. 
 
 The novice had next to ftudy the Jlatuter nf the illu- 
 tninees, which he was afTured contained nothing injurious 
 to the ftate, to religion, or to good morals. He was 
 next defired to a^ply himfelf to acquire the morality of 
 the order; which he was to do, not by reading the gof- 
 pels, but by perufing Epidfetus, Seneca, and Antoni- 
 nus, and by iludying the .works of the modern fo- 
 philts Weiland, Melners, and Helvetius, &c. The flu- 
 dy of man was alfo recommended as the moft intereft- 
 
 i 77« ] 
 
 J L L 
 
 15 
 
 Di<5lhjimty, 
 
 ing of all the fciencea. He was taught this ftudy not H'um'natl. 
 
 merely as a fcience, but as an art. A mo U! of a jour- '— >r~-^ 
 
 nal was given him, and he was required to infert in it 
 
 oblervations upon the charafter of every pcrfon that iio 
 
 happened to meet with. To quicken his diligence, the 
 
 inllnuator *occafi()n.illy examined his iournal. In the 
 
 mean time, the inlinuator was v.'atching him as a ccnti- 
 
 ncl, and noting down regularly oblervations upon the 
 
 defects and merits of his pupil, which he always fcnt to 
 
 his fuperiors. iS 
 
 The great objeft of the hifinuator was to entangle the Novice o. 
 
 novice, and to bind him IndlfTolublv to the order. With .' '^'^ , '° 
 .,.. , -11 , -..,.-,. drawnm 
 
 this view he required the novice to draw a faiuiful pic-D^,, ch». ' 
 
 ture of himfelf, under the pretence that he would thusrader. 
 
 know himfelf better. He defired him to write down his 
 
 name, his age, his country, his refidence, and his era- 
 
 ployment ; to give a lilt of the books in his library ; to 
 
 Hate his revenue ; to enumerate his friends and enemies, 
 
 and the caufe of his enmities. He was alfo to give a 
 
 fimilar account of his father and mother, his brothers 
 
 and fillers, and to be very careful in pointing out their 
 
 paflions and prejudices, their (Irong and weak fides. 
 
 In the mean time, the Infinuator w:is occupied in 
 drawing up a new (latemcnt of every thing he had been 
 able to difcover of the char.ifter and conducf of the no- 
 vice. This ilatement was tranfmitted to the fuperiors, 
 compared with the former. If the novice was approved, 
 he was then admitted to the fecond degree, upon his an- 
 fwering, in a fatisfaftory manner, 24 grand quellions, 
 which might enable the order to judge of his principles 
 and the credit to which he was entitled, and would fix 
 him down by Hronger ties to the authoiity of the fu- 
 periors. The detellable princijdes of the illuminees 
 now begin to appear, as will be evident from the fol- 
 lowing queilions which we have felefted : 
 
 Have you ferioufly reflected on the importance of the 
 ftep you take, in binding yourfelf by engagements that 
 are unknown to you i' fclhoiild you ever difcover in the 
 order any thing wicked or unjuft to be done, what part 17 
 would you take ? Do you, moreover, grant tiie power Pfwerct 
 of life and death to our order or fociety i' Are you',''^^'' 
 difpofed, upon all occafions, to give the preference to chimed by 
 men of our order over all other men ? Do you fubjeCtth.: fociety. 
 yourfelf to a Hind obedience, •without any rejlritiion tuhat- 
 joeiier ? 
 
 The novice having thus furrendered hJs confcience, 
 his will, and his life, to the devotion of the confplrators, 
 and thus fubfcribed, with his own hand, and confirmed 
 by his oath, a refolutioa to become the mod abjeCl 
 flave, was now deemed qualified to afcend to the fecond 
 degree, called Minerval. 
 
 In the dead hour of midnight he was coiidufted to a 
 retired apartment, wliere two of the order wei'e waiting ,15 
 to receive him. The fuperior, or his delegate, appear- .-idmidion 
 ed Handing in a fevere and threatening pollure; he held'" ''"-" ''^*. 
 a glimmering lamp in his hand, and a naked fword lay*'"' *] 
 before him. The novice was afked, whether he Hill per- 
 fifted in his intention of adhering to the order? Upon 
 anfwering in the affirmative, he was ordered into a dark 
 i-oom, there to meditate In filence on his refolutlon. On 
 his return, he was ftrlAly and repeatedly queilioned if f 
 
 he was determined to give implicit obedience to all the 
 laws of the order ? The infinuator became f(;curity for 
 his pupil, and then requefted for him the proteftion of 
 th^ order, which the fuperior granted with great folcm- 
 5 E 2 nity,
 
 I L L 
 
 [ 772 ] 
 
 1 L L 
 
 Mincfrvp.l 
 academy ; 
 
 10 
 Its library. 
 
 JUuminaii. tiity, proteding tliat nothing would be found there iiurt- 
 *—W~-^ fill to reh'glon, to morals, or to the itate. Having thus 
 faid, the iuperior takes up the nakeJ fword, and point- 
 ing it at the heart of the novice, threatens him with (lie 
 fatal cotifcquenccs of betraying the fccrets of the order. 
 The ni)viee again takes an oath, by wl.ich he binds 
 liinifelf, in the mod unhmited manner, to ferve the or- 
 der witli his life, honour, and ellatc, and to obferve an 
 inviolable obedience and fidelity to all his fupcriors. 
 He is tiien admitted a Miuerval, and henceforth is al- 
 lowed to attend the academy of the feiit. 
 
 The Minerval academy was conipolcd of lo, J 2, or 
 15 Minervals, and placed under the diredtion of a ma- 
 jor Ilkmiinee. It met twice every month In an inner 
 apartment, feparated from the other rooms of the man- 
 fion by an antichamber ; the door of which was to be 
 fhut with care during the meeting, and ftrongly fecu- 
 rcd by bolts. At tlie commencement of every meet- 
 ing, the prefident read and commented upon fome fe- 
 htl pafTages of the Bible, Seneca, Epictetus, Marcus 
 Aurclius, or Confucius ; evidently with a view of dimi- 
 nKhing the reverence for the facred writings, by thus 
 pl?.cing them on a level with the heathen moralifts. 
 Then each brother was ailced what books he had read 
 fince laft meeting, what obfervations he had made, and 
 what fervices he had performed for promoting the fuc- 
 cefs of the order ? 
 
 To each Minerval academy a library belonged. This 
 was formed by the contributions of the brethren, by 
 prefents of hooks, and by another method very extra- 
 ordinary. All Illuminees afting as librarians, or keep- 
 ers of archives, were admonifhed tojhal fuch books or 
 manufcripts as might be ufeful to the order. At one 
 time, fending a lllf of the books which he willied to be 
 embezzled from the library of the C^rmes, Weiihaupt 
 fays, " All thefe wouKl be of much greater ufe if they 
 were in our hands. What do thofe rafcals do with all 
 thefe books ? 
 
 Every brother at his admiffion was required to declare 
 to what art or fcience he meant chiefly to apply ; and 
 it was expelled that he fhould afterwards every year 
 give an account of the difcoveries or improvements 
 which he had made. All the other brethren who were 
 occupied in the fame ftudies, were defired to give him 
 every poffible aflillance. Thus a kind of academy was 
 formed, to which tliofewho could not ferve it by their 
 talents might give pecuniary contributions. That this 
 academy might have the appearance of a literary focie- 
 ty, prizes were annually diltributcd ; the bell difcourfe 
 vas publifhed, and the profits fent to the coffers of the 
 order. 
 
 Every month the prefident was to take a review of the 
 faults which he had obferved in his pupils, and examine 
 them concerning thofe which they might have been con- 
 fcious of in themfelves ; and it would be an unpardon- 
 able negleft, fay the ftatutes, fhould any pupil pretend 
 that, during the fpace of a whole mouth, he had re- 
 marked nothing i-eprehenfible. 
 
 It is impofGble to read thefe rules without admiring 
 them. Vv'ere men but half as anxious, attentive, and 
 c.-eful, to render themfelves good citizens and good 
 men, as thefe men were to render themfelves fuccelsful 
 confpirators, what a blelfed world (liould we fee! 
 
 The Minerval was rigoroufly fcrutinized, whether he 
 ruir~iUurui was ready to fubmit to every torture, or even to com- 
 nee. 
 
 Admiffio: 
 to the dt 
 pree of mi 
 
 mit fuicide, rather than give any information agalnft the Illuminafi. 
 order. Suicide was reckoned not only innocent, but ho- '— v-^ 
 nom'able, and was alto repreiented as a peculiar i'pecies 
 of voluptuoufnefs. In order to difcover the fentiments 
 of the Minervals upon thi^ fubjeci, they were required 
 to write a diflcitation upon the charatter and death of 
 Cato, or any hmilar fubjecil. They were alio delired 
 to difcufs the favourite doctrine of Weilhaupt, that the 
 end fancllfies the means; a principle of the moft perni- 
 cious tendency, which would reader calumny, afTafrma- 
 tlon, fcdition, and trealon, laudable and excellent. Next, 
 they were called upon to compofe a diffcrtation, by which 
 their opinions concerning kings and priefts might be af- 
 certained. If they performed all thtl'e tall<s with the 
 fpirit of an infidel, and the defperate firmnels of a con- 
 ipirator, they were then judged worthy of being pro- 
 moted to the degree of minor illuminee. 
 
 The minor illuminees held meetings fimilar to thofe 
 of the Minerval academy. It was neceffary that the 
 preiident fhould be one who was raifed to the degree of 
 prieft, and initiated in the myfleries ; but he was re- 
 quired to perfuade his pupils, that beyond the degree 
 which he had attained there were no myfteries to be 
 difcloled. ' The minor illuminees were to be fo trained, ^^ ^^ ;;_ 
 that they might look upon themfelves as the foundersluminccs 
 of the order; that by this powerful motive they might 'rained for 
 be animated to diligence and exertion. With this view, '^^ degree 
 hints were fcattered rather than precepts enjoined. It 
 was infinuated, that the world was not fo delightful as 
 it ought ; that the happinefs for which man was made 
 is prevented by the misfortunes of fome, and the crimes 
 of others ; that the wicked have power over the good ; 
 that partial infurre<Stion is uielefs ; and that peace, con- 
 tentment, and lafety, might be eafily obtained by me^ns 
 drawn fioai the grcateft degree of force of which hu- 
 man nature is capable. Such views, it is added, actua- 
 ting a lecret iociety, would not only be innocent, but 
 moft worthy of the wiie and wcU-dllpoied. 
 
 Weilhaupt had formed, with peculiar care, a code 
 for this degree, which was intitled, I njl ructions for form- 
 ing ufeful Labourers in lUum'tnfm. Thele intlruCfions 
 difcover an aftonifhing knowledge of human nature, and 
 are drawn up with a degree of fyftematic cooliiels which 
 perhaps no confpirator before him ever exhibited. He 
 lays down rules, by which the charaiJter of almoft any 
 perion may be afcertained. He recommends to the 
 minor illuminees, to attend to the condudl of any per- 
 fon entrufted to their care, at two periods ; when he is 
 tempted to be what he ought not to be, and when, re- 
 moved from the influence of every external temptation, 
 he follows the diftates of his inclination. They were 
 to itudy the peculiar habits and ruling paffions ot each; 
 to kindle his ardour by defcanting on the dignity of the 
 order, and tiie utility of its labours ; to intule a fpirit 
 of obfervation, by afking queftions, and applauding the 
 wifdora of the anfwers ; to correft the failings of their 
 pupil, by fpeakiiig of them as if t'hey were not his, 
 and thus making him judge in his own caufe ; to in- 
 ftruft and advife, not by tedious declamation, but by 
 fometimes dropping a few words to the purpofe, when 
 the mind fliould be in a proper ftate to receive them. 
 Above all, they were diretled to avail themfelves of 
 thole moments when they obferved a ])iipil difcontented 
 with the world. " It is then (fays Weilhaupt) you 
 muft. prels the fweliing heart, flimulate the feufibility, 
 
 and
 
 Ilhjmmati. 
 
 23 
 Scotch no- 
 
 14 
 Candidates 
 for higher 
 degrees 
 fubmit to 
 new trials. 
 
 ILL [ 773 1 ILL 
 
 and demonftrate how necelTaiy fecret focietics are for difcovcrcJ by the following queries : " When he finds ' 
 
 the attainment of a better order of things." himlelf with different parties, which docs he adopt;'' 
 
 Having pafTed with applaiife tiirough the ftates of the ftrongell or the weakeft ; the wittiell or the mod 
 
 probation already defcribed, the minor illuminee is Ihipid .' Or does he form a third ? Is he conltant and 
 
 pron-oted to the rank of major illuminee, or Scotch tirm in fpite of all obftacles ? How is he to be 'gained ? 
 
 novice. As major illuminee, he is encompalTed witli by jjraife, by flattery, or low courtfliip ; by women, 
 
 more rigid chains; and as Scotch novice, he is dif- money, or the entreaties of his friends ? Does, he love 
 
 patched as a mifllonary into mafonic lodges, to convert fatire ; and on what does he cxerclfe that talent ; on re- 
 
 the brethren to illuminifni. _ _ ligion, iiypocrify, intolerance, government, minillers. 
 
 The candidate for this degree is ftrlftly examined, in monks ?" &c. 
 order to difcover what opinions he now entertains con- All thefe queftions are to be anfwered and illnrtratcd 
 
 cerning the objeft of the fociety ; the motives that by faCls. It is neceflary to obferve that the fcruta- 
 
 prompted him to join it ; whether he is difpofed ftill to tors alio give in written anfwers to all thefe quellions. 
 
 co-operate with the reft of the brethren in accomplifh- When the candidate has thus given a minute hiftory of 
 
 ing the grand objeft ; and whether he be a member of his life, and revealed all his fecrets, his foibles, his er- 
 
 any other fociety ; and what are the duties which it re- rors, his vices, and his crimes, Wcifliaupt triumphantly 
 
 quires. , exclaims, " Now I hold him ; I defy him to hurt us ; 
 
 The fertile genius of Weidiaupt is not exhaufted ; he if he (hould wifh to betray us, we have alfo his )e- 
 
 has ftill ill refeive artifices more profound, and bonds crets." 
 
 more powerful ; his refources keep pace with the pro- The adept is next introduced into a dark apartment, 
 
 grefs of his fchemes. He now lays a fnare for his pu- wliere he folemnly fwears to keep fecret whatever he 
 
 pils, from which he hopes none can efcape, and there- may learn from the order. He then delivers up the 
 
 fore he flatters himfelf they are his for ever. He de- hiftory of his life, fealed, when it is read to the lodge, 
 
 mands of every candidate for higher degrees, to write, and compared with the charafter drawn of him by the 
 
 llluminali. 
 
 as a proof of confidence, a minute and faithful account 
 of his whole life, without any referve or diirimulation. 
 Referve or diffimulation would indeed be vain ; for the 
 rooft fecret circumlfances of his life are already well 
 known to the adepts, by means of innumerable fpies, 
 ■who, by the appointment of the fupeiiors, have, un- 
 known to him, been watching and Icrutinizing all his 
 aftions and words, his temper, pafTions, and opinions. 
 Now is prefented to the candidate the code of the 
 
 brother fcrutators. A corner of the veil is now lifted 
 up, ftill, however, with extreme caution. Nothing ap- 
 pears palpable but the pureft principles and moft ge- 
 nerous defigns. At the fame time many things are 
 darkly luggefted, which are incompatible with purity 
 and geneiofity ; for while the utmoil care is employed 
 to deceive the undcrftanding, nothing is neglefted that 
 can tend fecretly to corrupt the heart. A number of 
 queftions are afl<ed ; the evident intention of which is 
 
 brother fcrutator, called by the order the no/ce te ipfum to make the adept difcontented with the prefent moral 
 
 government of the world, and to excite the de!h-c of 
 attempting a great revolution. After anfwcring thefe 
 queftions, the fecretary opens the code of the lodge ; 
 and hiving informed the young illuminee that the oh- 
 jeft of the order is to difluie the pure truth, and to 
 make virtue triumph, he proceeds to fliow that this 
 is to be accompliflied by freeing men from their prcju- 
 their underftandin^s. 
 
 (know thyfelf ). This is a catechifm, containing from 
 a thoufaud to fifteen hundred queftions, concerning his 
 perfon, his health, his education, his opinions, his in. 
 clinations, his habits, his pafTions, his prejudices, and 
 even his weaknefles. Q_ueftions are alfo propofed re- 
 fpetling his acquaintances, his relations, fiiends, and 
 enemies. The candidate is required to enumerate his 
 
 favourite colours, to defcribe his language, the nature dices, and enlightening their underftandings. " To 
 
 of his converfation, his gait and geftures. Nothing, in attain this, (continues the fecretary), we muft trace 
 
 (hort, is omitttd that can tend to diftinguifli his eharac- the origin of all fciences, we mult reward opprefled ta. 
 
 ter as an individual, or as a member of fociety. Upon lents, we muft undertake the education of youth ; and, 
 
 many qualities in bis charaftcr, thirty, forty, or fome- forming an indiffjluble league among the moft powerful 
 
 times near a hundred queftions are propol'ed. The geniufes, we muft boldly, though with prudence, com- 
 
 following fpecimcn will enable the reader to judge what bate fuperftition, incredulity ,and folly ; and at length 
 
 aftoniihing care Weilhaupt employed to difcriminate form our people to true, juft, and uniform principles on 
 
 charafters. _ _ all fubjedts." The fecretary adds, that in attempting- 
 
 Is his ga'it flow, quick, or firm ? Are his fteps long, to diveft vice of its power, that the virtuous may be re- 
 
 (hort, dragging, lazy, or flcipping J Is his language re- warded even in this world, the order is counteraded by 
 
 gular, diforderly, or interrupted ? In fpeaking, does he princes and priejh, and the political conjlitutioin of na- 
 
 agitate his hands, his head, or his body with vivacity ? tions ; that, however, it was not intended to excite re- 
 
 Does he clofe upon the perfon he is fpeaking to ? Does volutions and oppol^ force by force, but merely to 
 
 he hold him by the arm, clothes, or button-hole .' Is bind the hands of the protcftors of diforder, and to 
 
 he a great talker, or is he taciturn ? If fo, why ? Is it govern without appearing to command ; that the pow- 
 
 through prudence, ignorance, rcfpcft, or floth ? &c. ers of the earth muft be cncompaflTed with a legion of 
 
 Concerning his education, he is qucftioned to whom indefatigable men, all directing their labours towards 
 
 does he owe it ? Has he always been under the eyes of the improvement of human riature. Were there but 
 
 his parents? How has he been brought up ? Has he a certain number of fuch men in every country, eacii 
 
 any efteem for his matters .' Has he travelled, and in might form two others. " Let thefe (fays he) only 
 
 ■what countries ? be united, and nothiiig will be impoffible to our order." 
 
 By thefe queftions his temper and difpofitions might All this is very fpecious ; it is well contrived to fafei- 
 
 be accurately known. His leading paffions would be nate the imagination of the young, and the lieart of 
 
 the
 
 ILL [ 774 ] ILL 
 
 ir.i.mlrati. tlie generous aiul benevolent, while, under nil this pre- feft, anil a philofophy more elevated ? And, in the l!luminm), 
 
 ^-—y—' tended regard to virtue aud to the happinefs of mankind, mean time, is it not adviiable to difleminatc the truth *» "^ 
 
 is concealed a nioll fornud;ible confpiracy againft the in fecret focietics ? 
 
 peace of the world. Should the anfwers given to thefe queftions accord 
 
 After this addiefs Is delivered, the major illuminee with the fentiments of the order, on tlic day fixed for 
 
 is prefented with the codes of the infinuator and fcni- the initiation, the candidate is blindfolded, and, along 
 
 tator ; for he mud now infpeft the pupils of the infi- with his introducer, is put into a carriage, the win- 
 
 nuators, and mult exercife the office of fcrutator while dows of which are darkened. After many windings 
 
 I 
 
 The degree 
 of Scotch 
 knight. 
 
 prefiding over the Minerval academies. 
 
 The next degree, which is that of Scotch knight, 
 is both intermediate and ftatlonary. It is ftatlonary 
 
 and turnings, which it would be impolfible for the 
 adept to trace back, he is conduilcd to the porch of 
 the temple of the myflcries. His guide ftrlps him of 
 
 for thofe who are not fufficiently imbued with the the mafonic infignia which he wore as a knight, re 
 principles of the order, and intermediate for thofe who moves the bandnge from his eyes, and prefents him 
 
 have Imbibed the true fplrit of illumlnlfm. The Scotch 
 knights were appointed the diredlors of all the prepa- 
 ratory degi-ecs, and to watch over the Interefts of the 
 order within their dillrldl. They were to (ludy plans 
 for increafing the revenues of the order, and to endea- 
 vour to promote to public offices of confidence, of 
 
 with a drawn fword ; and then having llriclly enjoined 
 him not to advance a Hep till he is called, leaves hira 
 to his meditations. At length he hears a voice eK- 
 claimlng-, " Come, enter, unhappy fugitive; the fa- 
 thers wait for you ; enter, and (hut the door after you." 
 He advances Into the temple, where he fees a throne 
 
 power and wealth, as many of the adepts as poffible ; with a rich canopy rifing above it, and before it, lying 
 
 and to llrlve to acquire an abfolute fway in the ma- upon a table, a crown, a fceptre, a fword, fome pieces 
 
 fonic lodges. They were to procure the management of gold, and precious jewels, interlaid with chains. 
 
 of the mafonic funds ; and while they were to perfuade At the foot of the table, on a fcarlet cufhion, lie a 
 
 the brethren that theie were expended according to white robe, a girdle, and the limple ornaments of the 
 
 their own orders, they were to employ them for pro- facerdotal order. The candidate is required to make 
 
 moting the views of the order. Thus one office of the his choice of the attributes of royalty, or of the white 
 
 Scotch knights was to embezzle the money that was robe. If he choofe the white robe, which he knows it 
 
 entruiled to them. In order to dliFufe truth, and to make is expefted he fliould do, the hierophant, or inftruClor, 
 
 virtue triumph. thus addreffes him : " Health and happinefs to your 
 
 After paffuig with applaufe through this long and great and noble foul. Such was the choice we expeclied 
 
 tedious probation, the jdept is introduced to the clafs from you. But Hop ; it is not permitted you to in- 
 
 of the myileries. He is not yet, however, made ac- veft yourfelf with that robe, until you have heard to 
 
 quainted with the whole fecrets of the focicty ; he mull what we now deRine you." The candidate is then or- 
 
 ftlU fubmit to new trials; his curiofity muil be farther dered to fit down ; the book of the myiteries is opco- 
 
 exclted, his imagination muft be kept longer uppn the ed, and the whole brethren lllten in filence to the voice 
 
 flretch, and his principles of depravity be rendered of the hieroph int. 
 
 more violent and inveterate before the vail be entirely 
 withdrawn, which will dilcovcr to him Weifhaupt and 
 Ills infernal crew, plotting the dcftrucllon of the laws, 
 fciences, and religion of mankind. The degree of 
 epopt or prieft, to which the adept was next raifed, 
 opened to view, however, fo great a part of the myf- 
 teries, that the reader will be fully prejiared to expcdl 
 
 •27 
 
 The exordium is long and pompous ; much artifice Ii'^^ru'Sioni 
 iaconcealtd in it, and much eloquence dllplayed. JtRifvi!.!!, to 
 tx]'. mates on the luolime and generous views or the lo- 
 ciety ; evidently with the dciire of lulling aileep the 
 fufpicion of the candidate, of exciting him to admira- 
 tion, and of infpiring him with enthufialm. The hie- 
 rophant then proceeds to unveil the myfterics. He 
 
 76 
 
 Prepar.i- 
 tions for 
 the prieft. 
 hood. 
 
 the fecrets which remain to be unfolded in the other launches ont into a fplendid delcription of the original 
 
 degrees. flate of mankind ; w hen health was their ordinary ilatc. 
 
 Before being admitted to the degree of epopt, the when meat, and drink, and fiielter, were their only 
 
 adept was required to give a written anfwer to ten pre- wants. At that period (fays he) men enjoyed the 
 
 liminary queltlons. The infinuatlons againft the efta- moft ineillmable bleffings, «j«a/;Vy ijnJ ///^r/j' ; they cn- 
 
 blllhed order of the world, which had formerly been joyed them to their utnioft extent ; but when the wan- 
 
 flightly mentioned, increale now to an indirecf propo- dering life ceafcd, and property darted Into exiilence ; 
 
 fal to attempt a complete revolution. The candidate 
 is afl<ed, whether he thinks the- woild has arrived at 
 that happy Hate which was intended by nature? Whe- 
 ther civil afioclations and rcliirion attain the ends for 
 
 when arts and fciences began to flourllh ; when a dil- 
 tinftion of ranks and civil alfoclations were eilablilhed, 
 " liberty was ruined in its foundation, and cquahty dii- 
 appeared. The world then ccafed to be a great fami- 
 
 ■which they were defigned ? Whether the fciences are ly, to be a fiiigle empire ; the great bond of nature was 
 conducive to real happinefs ? or whether they are not rent afunder." Wants now increafed, and the weak 
 
 merely the offspring of the unnatural ftate in which men 
 live, and the crude inventions of crazy brains ? It is then 
 propofed as a queftlon, whether there did not in an- 
 tient times exifl an order of things more fimple and 
 happy ? What are the beft means for reftoring man- 
 kind to that ftate of felicity ? Should it be by public 
 
 imprudently fnbmltted to the wife or the ftrong, that 
 they might be protefted. As the fubmiffion of one 
 perf'on to another ariles from wants, It ceafes when the 
 wants no longer exift. Thus the power of a father is 
 at an end when the child has acquired his ftrength. 
 Every man, having attained to years of difcretion. 
 
 meafures, by violent revolutions, or by any means that may govern himfelf ; when a whole nation, therefore, 
 luQuld enfure fuccefs ? Would it not be proper, with is arrived at that period, there can exift no farther plea 
 this view, to preach to mankind a religion more per-i for keeping it in wardfliip. 
 
 Such
 
 [ 77 
 
 I L L 
 
 UlumTati. Such a flate as that of civil focicty, Ij then repie- 
 **""* fiiited ;is incompatible with the pradice ot" virtue. 
 
 " With the divifion of the s^'obe, and of its Hates, be- 
 nevolence (fays the hIeroi>hai]t ) was reftiained within 
 certain limits, beyond which it could no longer be ex- 
 tended. Pati'iotifm was deemed a virtue ; and ho was 
 Jlvlcd a patriot who, partial towards his couiitryinen, 
 and unjull to others, was blind to the merits of llran- 
 tjers, and believed the very vices of his own country to 
 be perfedions. We really beheld (continues be) pa- 
 triiitilm generating localilm, the confined fpirit ot fa- 
 milies, and even egoifm. Dirsiinifh, rejcft that love of 
 country, and mankind will once more learn to know 
 and love each other as men. Partiality being call afide, 
 a union of hearts will once more appear, which will ex- 
 pand itfclf over the globe." 
 
 Thefe unpiiilolopiiical declamations, enth.unaftically 
 pronounced, at length make the proiylete excl.\;m, in 
 uiiifon with his mailer, " Are fuch then the confe- 
 qucnces of the inftitution of Hates, and of civil fociety ? 
 O folly ! Oh people ! that you did not forefee the fate 
 that aAvaited you ; that you fhould youvfelves have fe- 
 c<*ndcd your defi>ots in degrading human nature to fer- 
 vitude, and even to the condition ot the brute !" 
 
 Having wrought up the profclyte to this pilch of 
 frenzy, and enumerated all the evils 'which, aceording 
 to Wcifliairpt, arile from political alTociation, the hie- 
 rophant comes to reveal the means by which the grie- 
 vances of the human race may be rcdrefled. " Provi- 
 dence (he fays) has tranfmitted the means to us of fe- 
 cretly meditating, and at length operating, the falva- 
 tion of human kind. Thefe means are the fecret 
 fchools of pin'lofophy. Thefe lehools have been in all 
 ages the archives of nature, and uf the rights of man, 
 Thefe fchools fiiall one day retrieve the fall of human 
 nature, and princes and nations shall disappiar 
 FROM THE FACE OF THE EARTH ; and that without any 
 violence. Human nature fhali form one great family, 
 and the earth fhall berome the habitation of the man 
 ot reafoii. Reafr.n Jloall be the only book of laws, the fole 
 code of man. This is one o{ out gram! my /It net. Attend 
 to the demonftration of it ; and learn how it has been 
 tranfmitted down lo us." 
 
 This pretended demonftration m^kcs part of the fame 
 fophillical harangue ; and coufitts in panegyrics on the 
 dignity of human nature ; in a bafelefs morality ; and 
 in a fcandalous perverlion of the ChrJftian Scriptures, 
 with a blafphemous account of the miniftiy of the Sa- 
 viour of the world. 
 
 " What ftrange 1)lindnefs (continues the hitrophant) 
 can have induced men to imagine, that human nature 
 was always to be governed as it has hitherto been ? 
 Where is the being who has condemned men, the bell, 
 the wifeft, and the nioft enlightened men, to perpetual 
 flavery ? Why ihould human nature be bereft of its 
 moft perfeft attribute, that of governing itfclf ? W'tiy 
 arc thofe perfons to be always led who are capable of 
 conducing ihemfelves I Is it then impoffible for man- 
 kind, or at leaft the greater part of them, to come to 
 majority ? Are we then fallen fo low as not even to feel 
 our chains, as to hug them, and not cherilh the flatter- 
 ing hope of being able to break them, and recover our 
 liberty ? No ; let us own that it is not impoffible to 
 
 attain UNIVERSAL INDEPENDENCE." 
 
 The principal means which Weifliaupt offers to his 
 
 75 ] ILL 
 
 adepts for the conquell of this land of promife, is to Uluminati. 
 dimiiiifli the wants of the people ; and accordingly the ' " ••' 
 code denounces eternal war with everi- fneeics of com-Tu ^-t 
 merce. Jrlence the liiero])hant proceeds to inform the„tescnc- 
 candidate, that he who wilhts to fnbjctf nations toniii;sro 
 his yoke, need but to create wants, which he alone can ^°'"'""^«' 
 latisfy. " Confer (fays he) upon the mercantile tribe 
 fome rank or fome authority in the government, and 
 you will have created perhaps the moft formidable, the 
 moft defpotic ot all powers. He, on the contrary, who 
 wilhes to render mankind free, teaches them how to 
 refrain from the acquilition of things which they can- 
 not aflord : he enlightens them, he infufes into them 
 bold and inflexible manners. If you cannot dilTufc, at 
 the fame inibint, this degree of light among all men, 
 at lead begin by enlightening yourfelf, and by render- 
 ing yourfelf better. The mode of difl"ufing univerfal 
 light is, not to proclaim it at once to the whole world, 
 but to begin wiih yourfelf; then turn to your next 
 neighbour : you too can enlighten a third and a fourth : 
 let tliefe in the fame manner extend and multiply the 
 number of the children of light, until numbers and force 
 fhall throw poivsr into your hands. You will foon ac- 
 quire lufficierit force to bind the hands of your opponents, 
 to fuljugitte them, and to ftifle wiekedncls in the em- 
 bryo ;" /'. e, you will foon be able to llifle every prin- 
 ciple of law, of governmciit, of civil or political fociety, 
 wliofe very inftitution, in the eyes of an illuminee, is 
 the germ of all the vices and misfortunes of human na- 
 ture. 
 
 The hierophant, continuing to iiififl on the neceffity xiieir'mo- 
 of enlightening the people to open'.te the grand revo-ralitj ; 
 lutioEi, feeins to be apprehenfive that the candidate 
 may not yet clearly conceive the real plan of this re- 
 volution, which is in future lo be the fole objeft of all 
 his inilruftions. Let your inftrudions and lights be 
 univerfally diffufed; fo fliall youreiijjer mutual fecurity 
 univerfal ; and fecurity and inJJruSion iiii// enable us to 
 live •without prime or government, I'he inftrudion 
 which is to accomphlh this great end, is inftrudion in 
 morality, arid morality atone ; for " true morality is no- 
 thing elfe than the art of teaching men tojhaie o^' their 
 ivanijhip, to attain the age of manhood ; and thus to 
 need neither princes nor g'jvernments. The morali- 
 ty which is to perform this miracle, is not a morality 
 of vain fiibtlelies". It is not that morality whicii, de- 
 grading man, renders hirei carcltfs of the goods of this 
 woild, forbids him the enjoyment of the innocent plea- 
 fures of life, and infpircs him with the hatred of his- 
 neighbour. Above all, it niuft not be that morality 
 which, adding to the miferies of the miferable, throws 
 them into a ftate of puhllanimity and defpair, by the 
 threats of hell and the fear of devils. It mull be a divine 
 dotiriue, fuch as Jefus iaught to his difciples, and off 
 which he gave the real interpretation in his fecret con- 
 ferences." 
 
 The impious hierophant then proceeds, with match- . 3° 
 lefs blafphemy, to rejirefent the Redeemer of mankindpi," j^^^, ^j 
 as teaching, like the Grecian fophifts, an exoteric andchiift. 
 an efoteric doe'f rine. He defcribes him as the grand 
 mafter of the illuminees ; and afBrms, that the objed of 
 his feeret, which is loft to the world in general, has 
 been preferved in their myfteries. It was " to rein- 
 ftate mankind in their original equality and l;- 
 BEiiTY, and to prepare the means. Tliis explains in 
 
 what
 
 I L L 
 
 [ 776 1 
 
 I L L 
 
 I'lum'pa'i. what fcnfe Clirift was the Sai<iour and Redeemer nf the 
 ' luorld. The dotlrhie of original fin, of the fall of 
 
 rnan, and of bis regeneration, can now be uiidcrllood. 
 The (late of pure nature, of fallen or corrupt nature, 
 and the Aate of grace, will ro longer be a problem. 
 Mauki:id, in quitting their Hate of Dn»inal liberty, jell 
 from the llate of nature, and loj} their dignity. In their 
 civil fociciy, under their governments, they no longer 
 live in the ftate ot pure nature, but in that of fallen 
 and corrupt nature. If the moderating of their paffions, 
 and the diminution of their wants, reinltatc them in 
 their primitive dignity, that will really conifltute their 
 redemption and their Jlate of groee. It is to this point 
 that morality, and the moit perfeft of all morality, that 
 of Jefus, leads mankind. When at length this doiSlrine 
 fliall prevail throughout the world, the reign of the 
 good and of the elcft fliall be cftablifhed." 
 
 This language (as M. Barruel obferves) is furely 
 not enigmatical ; and the profelyte who has heard it 
 ,, without fhuddering, may flatter himfelf with being 
 Prepaiato- worthy of this Antichriftian pricfthood. He is led 
 r>' litej to back to the porch, where he is inveiled with a white 
 tunic and broad fcarlet belt of filk. The fleeves of 
 the tunic, which are wide, are tied in the middle and 
 at the extremities with ribbons likewife of fcarlet ; and 
 the candidate is recalled into the temple of myftevies. 
 He is met by one of the brethren, who does not per- 
 mit him to advance till he has declared " whether he 
 perfectly underftands the difcourfe which has been read 
 to him ; whether he has any doubts concerning the doc- 
 trines taught in it ; whether his heart is penetrated 
 with tlie fanftity of the principles of the order ; whe- 
 ther he is fenfible of the call, feels the ftrength of 
 mind, the fervent will, a«id all the difintereftednefs re- 
 quifne to labour at the grand undertaking ; whether he 
 is ready to make a facrilice of his 'will, and to fuffer 
 himfelf to be led by the moft excellent fuperiors of the or- 
 
 InUianonto The rites of thepreceding degree were in impious de- 
 thc Ffiell- rifion of the facram.ent of the Lord's fupper ; thofe of 
 ° the prefent are an atrocious mimicry of facerdotal ordi- 
 
 nation ; at which, as every one knows, the Lord's fup- 
 per is likewife celebrated. A curtain is drawn, and an 
 altar appears with a crucifix upon' it. On the altar is a 
 bible ; and the ritual of the order lies on a reading defli, 
 with a cenfer and a phial full of oil befide it. The 
 dean, or'prefident, who afts the part of a bifhop, blefles 
 the candidate, cuts hair from the crown of his head, 
 anoints him, clothes him in the vcftments of the prieft- 
 hood, and pronounces prayers after the fafhion of the 
 order. He prefents him with a cap, faying, " Cover 
 thyfelf with this cap ; it is more precious than the 
 royal diadem." The mock communion is then diftri- 
 buted ; and it confifts of milk and honey, which the 
 dean gives to the profelyte, faying, " This is that 
 which nature gives to man. Refledl how happy he 
 would ftill have been, if the defire of fuperfiuities had 
 not, by depriving him of a tafte for fuch fimple food, 
 multiplied his wants, and poifoned the balm of life " 
 The ceremonies are terminated by delivering to the 
 epopt that part of the code which relates to his new 
 degree. 
 
 Among the inflrudlionG which it contains, the fol- 
 lowing are more particularly worthy of notice. The 
 epopt, fays the code, " will take care that the wri- 
 
 Duticsof 
 the prieft 
 or cpopt. 
 
 tings of the members of the order fliall be cried up, and Uluniinati. ^ 
 that the trumpet of fame fliall be founded in their ho- ^•""'v •■ •* ' 
 nour. He will alfo find means of hindering the review- 
 ers from cafiing any fufficions on the writers of tiie fe6t." 
 He is likewife inllrufted to liribe the common people 
 into the intevells of the order, and to corrupt their 
 minds, hv getting pofleffion of fchools and other fcmi- 
 naries of learning. But " if it be neceiTary for us to 
 be mailers of the ordinary fchools (lays the impious le- 
 giflator), of how much more importance will it be to 
 gain over the EcclfJt.ijTtc feniinaries and their fuperiors ! 
 With them we gain over the chief part of the country ; 
 we acquire the fupport of the greatefl enemies to innovation ; 
 and the grand point of all is, that through the clergy 
 we become tnajhrs of the middle and hiver clnffes of the 
 people." _ 34 
 
 From the degree of epopt or pneft are chcfen the Qiialifica- 
 regents or prince-illuminees. On making this choice, fays """^ '^'"' 
 the code, three things of the utm,oft confcquence are to /reglnr,' 
 be obferved. " i/?. The greatell referve is neceflary 
 with refpecf to this degree : 2dly, Thofe who are ad- 
 mitted into it, muft be as much as pofrible_/)-« men, and 
 independent of princes : ^dly. They muft have clearly ma- 
 nifclled their hatred of the general coti/liiulion, or the flf- 
 tual flaie of mankind ; and have fliewn how evidently 
 they wifli for a change in the government cf the •world." 
 If thele requifites be found in an epopt who afpires to 
 the degree of regent, fix preliminary queftions are put 
 to him ; of which the obvious meaning is to difcover, 
 whether he deems it lawful and proper to teach fubjefts 
 to throw off the authority of their fovereigns, or, in 
 other words, to deftroy every king, minifter, law, ma- 
 giftrate, and public authority on earth. 
 
 When thefe queftions are anfwered to the fatisfac- 
 tion of his examiner, he is informed, " that a«, in fu- 
 ture, he is to be entrutted with papers belonging to the 
 order of far greater importance than any which he has 
 yet had in his poffeflion, it is neceffary that the order 
 fliould have farther fecurities. He is therefore com- 
 manded to make his nvill, and infert a claufe with re- 
 fpeft to any private papers which he may leave, in 
 cafe of fudden death. He is to get a formal or juridi- 
 cal receipt for that part of his will from his family, or 
 from the public magiftrate ; and he is to take their 
 promifes in writing, that they are to fulfil his inten- , 
 tions." This precaution being taken, and the day fix-Admiffioc 
 ed for his inauguration, he is admitted into an ante- to this de- 
 chamber hung with black, where he fees a fl<cleton,S''«^. 
 elevated two fteps, with a crown and fword lying at 
 its feet. Having given up the written difpofitions, &c. 
 refpefting his papers, his hands are loaded with chains 
 as if he were a flave, and be is left to his meditations. 
 A dialogue then takes place between his introducer and 
 the provincial, who is feated on a throne in a faloon ad- 
 joining. It is in a voice loud enough to be heard by 
 the candidate, and confifts of various queftions and 
 anfwers ; of which the following may ferve for a fpeci- 
 luen : 
 
 Prov. Who has reduced him to this ftate of fla-^ 
 very ? • 
 
 Mf. by the Introd. SociExy, Governments, the 
 Sciences, and falfe Religion. 
 
 Prov. And he wifties to caft off this yoke, to be- 
 come a feditious man and 3 rebel .' 
 
 Jnf. No; he wiflies to unite with us, to join in
 
 I L L 
 
 tlluminati oUR FIGHTS against the CONSTlTUTinN OF cn- 
 
 *■■"»' ' VERNMENTS, the comiptioii of morals, and the prota- 
 natioii of religion. He wilhcs, througli our means, to 
 become pevvERFUL, that he may attain the grand ul- 
 timatum. 
 
 Prov. Is he fuperior io prejiiilices ? Does he prefer 
 the general inlerejl of the univcrje to that of more limited 
 ajfociations ? 
 
 Anf. Such have been his promifes. 
 
 Prov. At\< him, whether the flveleton which is be- 
 fore him be that of a iing, a nobleman, or a heggar ? 
 
 i-lnf. He cannot tell ; all that he fees is, that this 
 flceleton was a man like iis ; and the characler of man 
 is all that he attends to. 
 
 After a great deal of infidious mummery like this, 
 the cpopt is admitted to the degree of prince ; but be- 
 fore his invelliture with the iiilignia of that order, he 
 is exhorted to be free, i. e. to be a man, and a man 
 who knows how to govern hlmflf ; a man who knows 
 his duty, and his imprefcrlplible rights ; a man who 
 ferves the univerfe alone ; whofe actions are folcly direft- 
 ed to ihe general ben ftl of the world and of human na- 
 ture. " Every thing elfe (fays the provincial) is injus- 
 tice." A long panegyric is then made on the hap- 
 pincfs which will be experienced by mankind, when 
 every father of a family ihall be fovercign in his tran- 
 quil cot ! when he that wilhes to invade thefe facred 
 rights (liall not find an afylum on the face of the earth ! 
 when idlenefs Ihall be no longer fuffcred ; and when the 
 36 clod of ufeful fcie'ices Jl.iall be cnjljirle ( c ) ! 
 
 Sign of the The fign of this degree confilK'd in extending out 
 ^&''^^- (lie arms to a brother with the hands open ; xXxe. gripe 
 was to feize the brother by the two elbows, as it were 
 to prevent him from falling ; and the "word was re- 
 demption ! The epopt was rnvelled with his princi- 
 pality by receiving a buckler, boots, a cloak, and a 
 hat ; and on receiving the boots, he was defired to fear 
 no road which might lead to the propagation or dif- 
 covery of happinefs. Thus decorated, the prince illu- 
 iTiinee received the fraternal embrace, and heard the in- 
 llruflions for his new degree. 
 
 One would think that the adept had now arrived at 
 the very acme of profanenefs and treafonable confpi- 
 racy. He has been initiated in myfteries which bnr- 
 Icfque Chriftianity and its Divine Author, and at the 
 fame time vow vengeance againll all government, all 
 law, and all fcience : yet Weidiaupt, in a letter to Ca- 
 to Zwack, his incomparable man, fays, that he has com- 
 pofed four degrees above that of regent, or prince-il- 
 luminee ; with refpeft even to the lotuejl of which, his 
 degree of pried will be found no more than child's 
 play. " The ritual of thefe degrees, (fays he), I 
 never fuffer to go out of my hands. It is of too fe- 
 
 SuppL. Vol. I. Part II. 
 
 C 777 ] 
 
 I L L 
 
 rious an Import ; it Is the key of the ancient and mo- Illui-.inati. 
 dern, the religious and political, hiilory of the uiii- """^ ' 
 verfe." 
 
 This caution of the cliief confpirator has deprived 
 us of the power to give fo particular an" account of 
 thefe degrees as we have done of the preceding ; but 
 the Abbe Barrucl atfures us that they were reduced to 
 two, viz. that of Magi;s, and that of the Man-king ; 
 and that thefe two conllituted tlie greater myste- 
 ries. When the adept was admitted to the degree of 
 magus, he was illuminized only In philofophy and reli- 
 gion ; when to that of man ling, new lights were given 
 him refpedling property, and every fpeeies of political 
 affociation. The Abbe quotes a palTagc from the Cri- 
 tical hi/lory of all the t/egrees of illiiminifm, written by a 
 man of honour, who had paffed through them all, which 
 will give the reader a fulKeient idea of the ohjtd of 
 thefe lafl degrees. 37 
 
 " With refpecl to the two degrees of magus and of ^W^^*^^' "' 
 man king (fays this writer), there is no reception, that ^^ '^ 
 is to fay, there are no ceremonies of initiation. Even a^j mm- 
 the ele6t are not permitted to tranferibc thefe decrees ; king, 
 they only hear them read, and that is the rcafon why 
 I do not publilh them in this work. The firll is that 
 of Magus, called alfo philofopher. It contains the 
 fundamental principles of Sijinozifm. Here even' thing 
 is material ; God and the world are but one and the 
 fame tiling : all religions are inconfiftent, chimerical, 
 and the invention of ambitious men." 
 
 That this is the doftrine of Spinoza, and that Spi- 
 noza was an alheift, is moll certain ; but though no- 
 thing can be rjjcntialh worfe than atheifm, we are Itron^- 
 ly inclined to fufpcd that, at the initiation of the Ma- 
 gus, expreffions mud have been ufed more Jhoriirg at 
 lea/} to the car than the philofophic jargon of the apof- 
 tate Jew. It is long fince the philofophy of Spinoza 
 was in Germany recommended from the prefs (fee Spi- 
 noza, Encycl.) ; it is but very lately that a profelTor in 
 the univerfity of Jena publifhed a book, in which he 
 teaches that there is no God, and that we abfurdly give 
 that title to the relations of Katurj (d) ; and fomething 
 approaching fo near to atheilm had been communicated 
 to the adept when he was admitted to the prieithood, 
 that we are perluaded Weilhaupt muil have alluded to 
 language at leall different from that in which Spinoza 
 taught his dark doctrines, and that language, accompa- 
 nied perhajis with impious and audacious geilures, when 
 he faid that, compared with his higher myileries, his 
 degree of priell was but child's play. 
 
 What gives fome degree of probability to this con- 
 
 jetlure, if it be nothing more, is the following fatl related 
 
 by the Abbs Barruel. During the Frencii revolution 
 
 (fays that able and well-informed writer), a comedian 
 
 j F appeared 
 
 (c) This will naturally furprife our readers ; but it could not furprife him to whom it was addreffed ; for 
 when candidate for the priefthood, he had been alked, " Do the feiences which men cultivate, furnilh them 
 with real lights ? Are they conducive to real happinefs ? Are they not, on the contrary, the offspring of num- 
 berlefs wants, and of the unnatural ftate in which men live ? Are they not the crude inventions of crazy brains I" 
 There were, however, to be academies for the cultivation of fuch feiences as fuited the dellgns^f the order. 
 Each academy was to confift of nine epopts, of whom feven were to prefide refpeftively over fo many depart- 
 ments of fcience, whilft the other two were to ofiiciate as fecretarics. One of the departments included the 
 occult feiences, to which belonged the art of raifmg the feals of the letters of all who belonged not to the order, 
 and of fecuring their own letters againft fimilar praftices ! I 
 
 (d) We learned this from the letter already quoted in note (a).
 
 lliumiimti. 
 
 Atht'iQn 
 »ail 
 
 DJvagifjn . 
 
 •See 
 I'oig's tit- 
 itrj on tbs 
 Savage 
 State. 
 
 ILL [ 778 ] ILL 
 
 appeared (e), drefled in the facevdotal robes of the il that thofe barbarians regenerated manki'nd : but the re- Ulumfnatf. 
 
 liimi;iees, and perfonally defying Almighty God. " No ! generation was not complete ; for the Goths and Van- '~~»'~~^ 
 
 (faid the impious wretch) tlioii dolt not cxill. If thou dah could not pveleive themfclves from the contagion 
 
 haft power over the thunderbolts, grr.fp them ; aim them of civil life; and their fall from favagifm to fcience 
 
 at tlic m;ia who dares fet thee at defiance in the face of drew from Weilhaupt's hierophants the mod piteous 
 
 thy altar.i. But no ! I blafpheme thee, and I ftlll live, lamentations ! ^^ 
 
 No! thou dolt not exift." It will be feen by and bye, The lall fecret communicated to the moll favoured The laft fe- 
 
 that the chiefs of the revolution, and even numbers of adepts was the novelty of the order. Hitherto their '^'■^"'f'*^5 
 
 their tools, were ilhiminized ; and is it improbable that zeal had been inflamed, and their refpedt demanded to^ * 
 
 this bhilphemer, who was arrayed in the infiguia of the an inftitution pretended to be of the highelt antiquity, 
 
 epopts, made ufe of the language and geltures of the The honour ot initituting the myfterits had been fuc- 
 
 higher mytteries ? Whether it be or not, M. Barruel ceffively attributed to the children of the Patriarchs, to 
 
 ha? proved, even from the writings of Weifhaupt him- ancient philofophers, even to Chrift himfelf, and to the 
 
 felf, that the magi were at lead atheifts of the fchool of founders of the mafonic lodges (fee Masonry in this 
 
 Spinoza. Suppl.). But now the time is come when the adept, 
 
 " The fccond degree of the grand mylleries, called initiated in the higher myfteries, is fuppofed to be fuf- 
 
 the Alan-king, teaches (according to the author of the ficiently enthufiaftic in his admiration of the order, to 
 
 Critical Hiilory), that every inhabitant of the country be entrufted with the hiftory of its origin. Here ther* 
 
 or town, every father of a family, is fovereign, as men they inform him, that this fecret focicty, which has fo 
 
 formerly were in the times of the patriarchal life, to artfullv led him from myftery to myllery ; which has, 
 
 which mankind is once more to be ( arried back ; that with fuch perfevering induftry, rooted from his heart 
 
 in confequence all authority and all magillracy mufl be every principle of religion, all love of his country, and 
 
 deftroyed." affection for his family ; all pretentions to property, to 
 
 I'his may appear to be nothing more than what the the exchifive right to riches, or to the fruits of the 
 
 adept has been already taught in the lefFcr myfteries ; earth ; — this fociety, which has taken io much pains to 
 
 and it is in fact nothing inore than that to which he demonftrate the tyranny and defpotifm of all laws hu- 
 
 muft have feen tliefc myfteries tending ; but the reader man and divine, and of every government, whether mo- 
 
 underftands not the language of the illuminees, if he narchical, ariltocratical, or republican ; which has de- 
 
 fuppofes that, by the patriarchal flate, they mean fuch clared him free, and taught him that he has no fove- 
 
 a flate as that of the patriarchs of the Old Teftament. reign on earth or in heaven ; no rights to refpedt in o- 
 
 No ! their patriarchal flate is the fancied favage ilate of thers, but thofe of perfett equality, of favage liberty, 
 
 the atheiftical philofophers of Greece and Rome, when and of the moil abfolute independence ; that this fo- 
 
 mankir.d had neither property nor fixed habitation, ciety is not the offspring of an ignorant and fuperfli- 
 
 1'his is evident from one of the difcourfes of the hiero- tious antiquity, but of modern philofophy ; in one 
 
 phant ; in which he tells the adept, tliat it would have word, that the true father of illaminifm is no other 
 
 been happy for man " had he known how to prefcrve than Adam Weifhaupt, known in the fociety by the 
 
 himfelf in the primitive flate in which Nature had pla- name of Spartacl's ! This important fecret, however, 
 
 ccd him ! But foon the unhappy germ developed itfelf remained a myllery even to the greater part of the magi 
 
 in bis heart, and reft and happinefs difappeared. As and the man-kings, being revealed only to the grand 
 
 families multiplied, the neceffary means of fubiiflence council of areopagites, and to a few other adepts of dif- 
 
 began to fail. The Noma/h or roaming life ceafed ; pro- tinguilhed merit. 4r 
 
 perty began ; men chofe Jixett habitaticns ; agriculture So zealoully was the order bent upon propagating Prop far 
 
 krought them together; liberty was ruined i,n its its execrable principles through the whole world, that*^"^^ " * 
 
 rouNDATiuNS, AND EQjjALiTY Di SApp EA s ED." fome of the chiefs had planned an order of female a- ' 
 
 To reilore that liberty and equality, therefore, which depts, in fnbfVrviency to tlfe defigns of the men. " It 
 IS the ultimate objedt of the order, and conflitutcs the will be of great fervice, (fays Calo Zwack), it will 
 Man-king, all property mufl be aboliflied, every houfe procure us both information and money, and will fuit 
 burnt, as well the cottage of the ptafant as the palace charmingly the tafte of fome of our trueil members, 
 of the prince ; and mankmd mufl once more inhabit who are lovers of the fcx." An affeflbr of the Impe- 
 voods and caverns without clothes and without fire, rial chamber at Wetzlar, of the name of Diltfurt, but 
 and fally out occafionally to encounter their fellow- known among the illuminees by that of Minos, ex- 
 brutes, and to fearcb for food among the wild herbs of preffed even tiis defpair of ever bringing men to the 
 the defart. According to Mochus the Phenician, and grand objeft of the order without the fupport of fe- 
 the Greek philofophers of this hopeful fchool, this was male adepts ; and he makes an offer of his own wife 
 the original itate of man * ; and to this flate it was the and his four daughters-in-law to be firfl initiated, 
 object of Wcifliaupt and his adepts to reduce man again. This order was to be fubdivided into two clafTes, each 
 Hence we hear them lavifhing the molt rapturous enco- forming a feparate fociety, and having different fe- 
 miums on the Goths and Vandals who over-ran the crets. The firfl was to be compofed of virtuous- wo- 
 Roman empire, annihilated the arts, put a flop to agri- men ; the fecond of the wild, the giddy, and the volup- 
 culture, and burnt the towns and villages of civilized tuous. The brethren were to conduft the firfl, by- 
 Europe ! It was thus, according to the illuminees, promoting the reading of good books ;. and to train the 
 
 fecond 
 
 (e) He does not fay where this appearance was made j but the circumflances related lead us to fuppofe that 
 it was iu a church.
 
 I L L 
 
 r.tuminsti, fccond iot\\c :w\.%oi ft-creily gratifyiiif; their pajjlons. The 
 ^-—Y'— jvjf'e of an adept Hiiined Ptolemy Magus was to prclide 
 over one of the clad'es ; which (fays Minos) will be- 
 come, tmder her management and his, a very pretty fo- 
 ciety. " Voii mult contrive pretty degrees, anj dreffes, 
 and ornaments, and elegant and decent rituals. No man 
 niuft be admitted. This will make them more keen, 
 and they will go much farther than if we were prefent, 
 or than if they thought that we knew of their proceed- 
 ings. Leave them to the fcope of their own fancies, 
 and they will foon invent mylleries which will put us 
 to the blufh, and myfteries which we can never equal. 
 They will be our great apoftles. Reflcft on the re- 
 fpeft, nay, the awe and terror, infpired by the female 
 myftics of antiquity. Ptolemy's wife irmft diredt them, 
 and file will be inilrufted by Ptolemy ; and my ilep- 
 daughters will confult with me. We mull always be 
 at hand to prevent the introduAion of any improper 
 queilioii. We muft prepare themes for their difcuf- 
 (ion : thus we fiiall confets them, and infpire thein with 
 our fentiments. No man, however, mull come near 
 them. This will fire their roving fancies, and we inay 
 expedl rare mylleries I" 
 Reie^ed ^"' notwithftanding all the plans and zeal of this 
 
 by Sparta- profligate wretch and others of the fraternity, it does 
 tifi. not appear that the General Spartacus ever confented 
 
 to the eflablifliment of the fittcrhood. He fupplied, 
 however, the want of fuch an inltitution, by fecret in- 
 ftruelions to the regents, on the means of making the 
 influence of women over men fubfervient to the order, 
 without entruiling theni with any of the fecrets. " The 
 fair fex (fays he) having the greateft part of the world 
 at their difpofal, no ftudy is more worthy the adept 
 than the art of Jlattery, in order to gain them. They 
 are all more or lefs led by vanity, curiolity, pleafure, or 
 the love of novelty. It is on that fide, therefore, they 
 are to be attacked, and by that to be rendered fubfer- 
 yient to the order." That Weilhaupt's fagacity had 
 not on this occafion forfaken him, is very evident; fince 
 it has been proved that the German fair, who were the 
 correfpoudents of the illuminees, welcomed the French 
 « Dr R,,!,;. invaders of their native country *. Nay, fo lately as 
 fon's/'roo/jthe winter of 1798, our correfpondent in Saxony heard 
 t/a Con/'iii- feveral of thefe illuminized ladies exprefs a wifli that the 
 riicy. French might invade and conquer England ; for then, 
 
 faid they, tea and coffl'e •would be cheaper ! 
 
 It is not enough for the founder of a feft of confpi- 
 rators to have fixed the precife objciit of his plots. His 
 accomplices mull form but one body, animated by one 
 fpirit ; its members muft be moved by the fame laws, 
 under the infpedlion and government of the fame chiefs. 
 A full account of the government of Weifliaupt's or- 
 der will be found in the valuable work of Abbe Bar- 
 ruel ; our limits permit us to give only fuch a general 
 view of it as may put our readers on their guard againll 
 
 tthe fecret maci^iinations of thefe execrable villains, wiiofc" 
 lodges are now recruiting, under different denomina- 
 tions, in every country in Europe. 
 
 Wherever illuminifm has gained a footing, as the 
 means of fubordinatiou, there is a general divifion of 
 command as well as of locality. The candidates and no- 
 vices are each under the diveftion of his own iufinuator, 
 who introduces him into the Minerval lodges ; each 71//- 
 nerval lodge has a fuperior from among the preparatory 
 clafs, under the infpeftion of the intermediary clafs. So 
 
 t 779 1 
 
 I L L 
 
 Subordina- 
 tion of the 
 illuniincef. 
 
 many lodges conftitutc a ditlrifl, under the direflion of Ulun ina'i. 
 a fuperior, whom the order calls dean. The dean is """""^ ' 
 fubjefteJ to the provincial, who has the infpeclion and 
 command of all tiie lodges and deaneries of the province. 
 Next in order comes the national fuperior, who has full 
 power over all within his nation, provincials, deans, lod- 
 ges, &:c. Then comes the ftipreine council of the or- 
 der, or ihe areopagitet, over wiiich prefides the general 
 of illuniirifm. Thus has the order formed within itfclf 
 a fupreme tribunal, to whole inquifition all nations are 
 to he fubjeftcd. The areopigites, confiltirig of twelve 
 fathers of the order, with the general at tiicir head, 
 form the centre of commuiu'ealiou with all the national 
 fuperiors on earth ; each national is the centre of one 
 particular nation ; the provincial, of one province ; the 
 titan, of the lodges within his deanery ; the Jtlirierval 
 irafler, of his academy ; the venerable, of his mafonic 
 lodge ; and the injinuator or recruiter, of his novices and 
 candidates. 
 
 The higher degrees (fays Weiflraupt in o»ie of hisTheir 
 infl;ruftions to the regents) mull always be hidden from"" d- of 
 the lower. The fimple illuminee therefore corrcfponds'-'"^'"'! °''' 
 with his immediate fuperior, knowing perhaps no other ' 
 
 member of the order ; the latter, with his dean ; and 
 thus gradually afcendiiig to the national fuperiors, who 
 alone are acquainted with the reCdence of the areopa- 
 gites, as they again are with the names anij refidence 
 of the general. Any member, however, of the inferior 
 degrees, may occafionally correfpoud with his unknown 
 fuperiors, by addreffing his letters i^iilms licet ; and in 
 thcte letters he may mention whatever he thinks con- 
 ducive to the advancement of the order. If he be a 
 novice, he may in thefe letters inform his fuperiors 
 how his infl.ruttor behaves to him, or may draw the 
 eharadler of any perfon whatever. When the letter of 
 any adept contains fecrets, or complaints which he 
 choofes to conceal from his immediate fuperior, he di- 
 redts it Soli or Prima ; and then it can be opened only 
 by the provincial, the national fuperior, the areopagiles, 
 or the general, according to the rank of the writer, 
 which is by fome contrivance unknown to M. Barrucl, 
 indicated on the outfide of the letter. The provincial 
 opens the letters of the minor and major illuminees 
 which are direfted Soli ; the ^ibiis Ucets of the epopts; 
 and the Primes of the novices ; but he cannot open 
 either the Prima of the minerval, the Soli of the Scotch 
 knight, or the ^libns licet of the regent. He can only 
 form a conjefture as to the perfons who open his own 
 letters, and thofe which he is not permitted to open 
 himfelf. 
 
 When it is confidered, that by one of Weifhaupt's . ^K . 
 n , . ., , . •' , , ..f,'^. ^ .\nd of ei- 
 
 itatutes, the provincial has in each chapter or dillncty;„„ ;„,_ 
 
 a confidential epopt, who is his fecret cerfor or _/5^ji ;portance to 
 that thefe fpies are to infinuate themfelves into all com- their order, 
 panics, and coUeft anecdotes of fecret hiftury; that the 
 hitlorian of the province is to infert thefe anecdotes in- 
 to a journal kept for that purpole ; and that the pro- 
 vincials are obliged to forward the contents of thefe 
 journals to the high luperiorsof the i>rder - fome notion 
 may be formed of the influence of the general and are- 
 opagites in every coimtiy into which illuminilm hat 
 found its way. " 1 he means of acquiring an afeen- 
 dency over men (fays Weifliaupt), are incalculable. 
 Who could enumerate them all ? They mull vary with 
 t(»e dirpoClion of the times. At one period, it is a 
 i F 2 tafte
 
 I L L 
 
 [ 780 1 
 
 I L L 
 
 - 46 
 
 I?y every 
 means, 
 good or 
 bad. 
 
 lllumlna'i. tafte for the marvellous that is to be wrought upon. 
 
 *~~~v~— ^ At another, the lure of fecret focifties is to be held 
 out. For this reafon, it is very proper to make your 
 interiors believe, without telling them the real ftate of 
 the caie, that all other fecret focieties, particularly that 
 of Freemafonry, are fecretly diretled by us. Or clie, and 
 IT IS REALLY THE FACT IN SOME STATES, THAT PO- 
 TENT MONARCHS ARE GOVEKNtD BY OUR OKDER. 
 
 When any thing remarkable or important comes to 
 pafs, hint that it originated iviih our order. Should 
 any peri'on by his merit acquire a great reputation, let 
 it be generally underrtood that he is one of us. 
 
 " If our order cannot eftablilh itielf in any particu- 
 lar place, with all the forms and regular progrefs of 
 our degrees, fame other form mujl be ajj'umcd. Always 
 have the ohjeSl in view; that is the eflential point. No 
 matter what the cloak be, provided yon hicceed ; a cloak, 
 however, is always necejjiiry, for in fecrecy our Jlrenqlh 
 lies. The inferior, lodges of freemasonry are 
 
 THE MOST CONVENIENT CLOAKS for OUr GRAND OB- 
 JECT", becaufe the world is already familiarifed with 
 the idea, that nothing of itnportance, or worthy of their 
 attention, can fpring from tnafonry." No artifice, how- 
 ever, is to be left untried. " You may attend large 
 and commercial towns during the times of fairs in c'if- 
 ferent characters ; as a merchant, an officer, an ahbl. 
 Everywhere you will perfonate an extraordinary man, 
 having important bufinefs on your hands ; but all this 
 muft be done with a great deal of art and caution, left 
 you fhould have the appearance of an adventurer. You 
 may write your orders with a chymical preparation of 
 ink, which difappears after a certain time. Never lole 
 fight of the military fchools, of the academies, printing 
 preffes, librariei, cathedral chapters, or any public efiablijh- 
 mcnts that can influence education, or government. Let 
 our regents perpetually attend to the various means, 
 and form plans, for making us masters of all thefe 
 eflalliflmients . When an author fets forth principles 
 true in themfelves, but which do not as yet fuit our 
 general plan of education for the world, or principles, the 
 publication of which is premature ; every effort muft 
 be made to gain over the author ; but fhould all our at- 
 tempts fail, and we fhould prove unable to entice him 
 into the order, let him be difcredited by every pofpble 
 means " 
 
 Of their methods of difcreditiug authors, one has 
 come to our knowledge, which muft be incercfting 
 to fome of our readers. Dr Robifon's work, entitled 
 Proofs of a Confpiracy, Sic. which firft unmafl<ed thefe 
 hypocrites in this country, found its way into Ger- 
 many, and was tranflated into the German language, 
 and expofed to fale at the Leijific fairs. The illumi- 
 nees, under the difguife of merchants and abbes, attend- 
 ed, and bought up the whole imprefiion, which they 
 committed to the flames. A fccond edition was pub- 
 liflied, and it fhared the fame fate (f). This was a 
 more compendious way of anfwering the learned author 
 than that which has been adopted by the Jacobin jour- 
 nalifts in London ; but perhaps it may convince the 
 readers of thefe journals, that the Doftor has not fo far 
 
 miftaken the fenfe of the writings af Philo and SpartO' llUimiiisti. 
 cus, as their illnminifed maftcrs wilh them to believe. v " ■ ' 
 
 When thete arts of diffemlnating the diforganifing 
 and impious principles of the order are duly conlidcred, 
 and when it is remembered that its cmiiTaries dare not 
 difobey a fingle injunction of the high fuperiors, without 
 expofing themfelves to poiion, or to the daggers of a 
 tlioufand unfcen affaffins, no man can be furprifcd to learn 
 that the illuminees contributed greatly to the French 47 
 revolution. The philofophers of France had indeed pre- liluniinifrti 
 pared the public mind for embracing readily the doc-' ''' 
 
 tvines of illumir.ilm ; and fo early as I 782, Philo and 
 Spartacus had formed the plan of illumiiiizing that na- 
 tion ; but they were afraid of the vivacity and caprice 
 of the people, and extended not their attempts, at that 
 time, beyond Strafbourg. Already, however, tliere ex- 
 ifted tome adepts in the very heart of the kingdom; anil 
 the Marquis de Mirabeau, when ambaffador at the court 
 of Berlin, was initiated at Bruniwick by a difciple of 
 Philo Knigge's. On his return to France he began to in- 
 troduce the new myfleries among his mafonic brethren. 
 
 The llate of free mafonry was at that time peculiarly „ 
 
 adapted to the views of the confpirators. The French By means- 
 had engrafted on the old and innocent Britilh mafonry •'' free ma» 
 a number of degrees, gradually rifing above each other, '"°T* 
 to the very mylteries of illuminifm itfelfc(fee Maso.nry 
 in this Suppl.) Thefe were called the philofophical de- 
 grees, and comprehended the knights of the fun, the high- 
 er Roficrucians, and the knights Kadeflo. At the head 
 of all thefe focieties, whether ancient or modern, were 
 three lodges at Paris, remarkable for the authority 
 which they exercifed over the reft of the order, and 
 Phih'p of Orleans was the grand-mailer. So early as 
 the year 17S7, France contained 282 towns, in which, 
 were to be found regular lodges, under the diredion 
 of that execrable wretch. He increaled their number 
 by ijitroducing to the mafonic myfteries the loweft of 
 the rabble, as well as thole French guards whom he 
 dellined to the fubfequent attack of the baltile, and to 
 the ftorming of the palace of his near relation and royal 
 mafter. In every country town and village lodges were 
 opened for aflembling the workmen and pealantry, in 
 hopes of heating their im.aginations with the fophiifica- 
 ted ideas of equality and liberty, and the rights of man; 
 and it was then that Mirabeau invited a deputation 
 from the order of Weiflianpt, which very quickly difFu- 
 fed the light of illuminifm through the whole kingdom. 
 Inftead of Spartacus Weithaupt, Calo Zuack, and Philo 
 Knigge, we find wielding the firebrands of revolution 
 in the capital of Fiance, Philip of Orleans, Mirabeau, 
 Sxeyes, and Condorcel. The day of general infurrec- 
 tion was fixed by thefe miicreants for the 14th of July 
 1789. At the fame hour, and in all parts of Frmice, 
 the cries of equality and liberty refouuded from the lod- 
 ges. The Jacobin clubs were formed; and hence fprung 
 the revolution, with aD its horrors of ai;ieifm, murder, 
 and mair.icre ! 
 
 In fupport (if this account of the illuminees we have 
 not loaded our margin with authorities ; becaufe our 
 detail has been taken wholly from the valuable works 
 
 of 
 
 (a) This information was communicated to us by a gentleman of charafter, who was at Leipfic when the 
 two imprefTions of the book were thus difpofed of. The Abbe Barruel's work has no doubt been anfwered in 
 the fame way, though we cannot fay fo upon the fame authority.
 
 ILL 
 
 [ 78 
 
 40 
 
 RefliiMioiis 
 on the fmi- 
 damcnia! 
 
 Illumin ti. of Al)l)c Biirrucl and Dr Robifon, to which wi. refer 
 ' V our rcadtis for much curious informatidii that our li- 
 mits do not permit us to give. We cannot, however, 
 conchide the article, without making fome remarks on 
 that fp'.cions principle by which the conlpirators have 
 dehided nuiiibers, who abhor their impieties, and wi o 
 would not g>) all their length even in rebellion ; we 
 mean tlie nuxini, " tha* it is our duty to love all men 
 with an equal degree of affedion, and that any paitial 
 regard for our country, or our children, is unjull." 
 
 I'hat this maxim is falfe, every C/jri/Jinti knows, bc- 
 caiife he is enjoined to " do good indeed unto all men, 
 but mqre efpec'wlly to them who are of the houfehold of 
 faith ;" becaufe he is told, that " if any man provide not 
 for his o-zvii, and cipecially for thofe of his ovmi honfe, 
 he hath denied the faith, and is worfe than an inlidel ;" 
 becaufe his divine mailer. Immediately after refolving 
 all duty into the love of God and man, delivers a pa- 
 rable, to fhew that we neither can nor ought to love 
 all men equally; and becaufe the fume Uivine Perfoii 
 hdd one difciple whom he loved more than the relt. 
 But we wifh tliofe phUofopljcrs who talk perpetually ot 
 the mccban'ij'm of the human mind, and at the fan;e time 
 affeft to have wo partial fondnels for any individual, bnt 
 to love all with the fame degree of rational affection, 
 to confider well whether fuch philanthropy be confid- 
 ent with what they call (very improperly indeed) me- 
 chan'ij'm. If tlfis mechanifm be (as one of them fays it 
 is) nothing more than attraClkn and rcpulfion, we know 
 that it cannot extend with equal force ov^r the whole 
 world; becaufe the force of attraction and repuUion 
 varies with the dillance. If by this abfurd phrafe, 
 they mean a fet of in/lir.Sive propenfitics, or feelings, 
 ve know that among favagcs, who are more governed 
 by indinfl than civilized men, philanthropy is a feeling 
 or prop^nfity of a very limited range. If they believe 
 all our paffions to originate in felf love, then Is It cer- 
 tain that our philanthropy mnft be progrefTive ; em- 
 bracing firft, and with Itrongelt ardour, our relations, 
 our friends, and onr neighbours ; then extending gra- 
 dually through the fociety to which we belong ; then 
 grafping our country ; and lad of all the whole human 
 race. Perhaps they may fay that reafon teaches us to 
 love all men equally, becaufe fuch equal love would 
 contribute mod to the fum of human happinefs. This 
 fome of them indeed have aftually fiid; but it is what 
 no man of rcfleftlou can pofTibly believe. Would the 
 fum of human happinefs be Increafed, were a man to 
 pay no greater attmtion to the education of his own 
 children than to the education of the children of dran- 
 gcrs ? were he to do nothing more for his aged and 
 helplefs parents than for any other old perfon what- 
 ever ? or, were he to negleft the poor in his nelglibour- 
 hood, that he might relieve thofe at the diHance of 
 1000 miles? Thefe quedlons are too abfurd to merit a 
 fcrlous anfwer. 
 
 When a man, therefore, boads of his unlverfal bene- 
 volence, declaring himfelf readv, without fee or re- 
 ward, to facrilice every thing dear to him for the bene- 
 fit of ftrangers whom he never faw ; and when he con- 
 demns, in the cant phrafe of faiftlon, that narrow po- 
 licy which does not confider the whole human race as 
 one great family — we may fafely conclude him to be 
 cither a confumraate hypocrite, who loves none but 
 iimftlf, or a philofophical fanatic, who is at once a 
 
 I ] IMP 
 
 drangcr to his duty and to the workings of his own I'l.niJnati 
 heart. , " r a 
 
 ir I • ^ f • r 1 r 1 Impel l^Ct. 
 
 It this concluiion requirr any iartner prooi, we have 
 It In the conduct of Weiduuipt and his areopagitcs. jo 
 In the hand-writing of Calu his incoinpnralle iiiiiii, was''"^""! 'ifi- 
 found the defcription of 3 drong box, which, if fcrced'"'' 'j'^'^r 
 open, would blow up and Jejhoy its cnnlcnls ; feveral||,J juy^jj. 
 receipts for procuring abort iou ; a conipofitlon which i.tes. 
 LUnili or I'liis when fpurted In the face ; lea for procu- 
 ring abortion; lierbo' qut bultnt (jiial'ilalcm iLlaleream ; 
 a method tor filling a bed-chamber with pijlikulial va- 
 pours ; how to take off Impreffioiis of feals, fo as to ufe 
 them afterwards as feals ; a receipt ad excilanJum furo- 
 rem uterinum ; and a differtation on filicide. Would 
 genuine [ih'ldnthropills have occafion for fuch receipts 
 as thefe I No ! the order which ufed them was founded 
 i 1 the mud confummate villaiiy, a. id by the moll de- 
 tedable hypocrite. The incclluoiis Weidiaupt feduced 
 the widow of his brother, and folicited jioHoii and the 
 dagger to murder tl.c woman whom he had fondly 
 preffed in his arms. " Execrable hypocrite (fays M. 
 Barruel), he Implored, he conjured both art and friend- 
 fliip, to dedroy the innocent viflim, the child, whofc 
 hirth mud betray the morals of his father. The fcan- 
 dal from which he dirinks. Is not that of his crime : it 
 Is the fcaudal v.'hich, publilhing the depravity of his 
 heart, would deprive him of that authority by which, 
 under the cloak of virtue, be plunged youth into vice 
 and error. 1 am on the eve, (fays he) of lofmg that re- 
 putation which ga-ve me fo great authority ever our people : 
 Aly Jifler in law is with child. I -will hazard a defperate 
 blow, for I neither tan nor will lofe my honour.^' Such 
 is the benevolence of thofe who, banidiing from their 
 minds all partial affedion for their children and their 
 country, profefs themfelves to be members of one great 
 family, the family of the woild ! 
 
 IMAGINARY Quantities, or Impnjfthk ^anti- 
 ties, in algebra, are the even roots of negative quanti- 
 ties ; which expreffions are Imaginary, or Impoffible, er 
 oppofed to real quantities; as y** — aa, or ■'^ — a*, 
 &c. For as every even power of any quantity what- 
 ever, whether polltive or negative, is ncceffarily podtive, 
 or having the fign -f-, becaufe + by -|-, or — by — , 
 give fqually -f ; hence It follows that every even power, 
 as the fquare for Indance, which is negative, or having 
 the f gu — , has no pofllble root ; and therefore the 
 even roots ot fuch powers or quantities are faid to be 
 Impoldble or imaginary. The mixt expreffions avlfing 
 from Iinngiiiary quantities joined to real ones, are alio 
 imaginary ; zs a — t/ — aa, or b -^ \/ — aa. 
 
 I.yi.iaiMjRv Roots of an equation, are thofe roots or 
 values of the unknown quantity, which contain fome 
 imaginary quantity. Thus the roots of the equation 
 x.v -f- aa — o, are the two imaginary quantities -\- */ — aa 
 and — */ •- oa, or -J- a\/ — I and — ay' — i. 
 
 IMPACT, the fimple or fingle adb'on of one body 
 upon another to put It In motion- Point of impa£l is 
 the place or point where a body afts. 
 
 IMPERFECT Number, is that vvliofe aliquot 
 parts, taken all together, do not make a fum that is 
 equal to the number Itfelf, but either exceed It, or fall 
 diort of it ; being an abundant number in the former 
 cafe, and a defcftive number In the latter. Thus, 12 is 
 an abundant imperfeft number, becaufe the fum of all 
 its aliquot parts, I, 2, 3, 4, 6, makes 16, whish exceeds 
 
 the
 
 IMP [ 78: 
 
 lirpril tlie ndn.bcr i 7. And 10 is a defeif^ivc inipcrfeA numhcr, 
 ^ 1' Ijecaufc its aliquot paits, 1, 2, j, taken all together, 
 . " ' make only H, which is Icis than the number 10 itfilh 
 
 IMPOST, in architeflure, a c;iplt,il or plinth, to a 
 piilir, (ir piliifter, or pier, th.it fupports an arch, &c. 
 Di«l cot IMKULSK^N, is the term employed in the Ian- 
 liiiiulio. guage of mechanical philofophy, for expreffing a fup- 
 pofed peculiar exertion of the powers of body, by 
 which a moving body changes the motion of another 
 body by hitting or llriking it. The plaineft cafe of 
 this aflion is when a body in motion hits another body 
 at reft, and puts it in motion by the ftroke. The body 
 thus put in motion is faid to be impllled by the o- 
 ther : and this way of producing motion is called im- 
 pulsion, to diftinguifli it from PREssiON, thrusting, 
 or PROTRUSION, by which we pufli a body from its 
 place without ftriking. The term has been gradually 
 extended to every change of motion occalioned by the 
 , colliiion of bodies. 
 
 Kiftory of When fpeculative men began to colkft into general 
 it- claffes, the obfcrvatlons made during the continual ex- 
 
 ertions of our own perfonal powers on external bodies, 
 in order to gain the purpofcs we had in view, it could not 
 be long before they remarked, that as we, by the flrength 
 of our arm, can move a body, can ftop or any how change 
 its motion; fo a body already in motion produces efTedts 
 of the fame kind in anotlier body, by hitting it. Such 
 obfervations were almoft as early and as interefting as 
 the other ; and the attention was Very forcibly turned to 
 the general fafts which obtained in this way of produ- 
 cing motion ; that is, to the expifcation of the gencial 
 laws of impulfion. We do not find, however, in what 
 remains of the phyfical fcience of the ancients, that 
 they had proceeded far in this clafTiiication. While 
 mechanics, or the fcience of machines, had acquired 
 fome form, and hid been the fubjeft of fuccefsful ma- 
 thematical difcuffion, we do not find that any thing fi- 
 ^milar had been done in the fcience of impulfe. Yet the 
 artillery of ancient times was very ingenious and power- 
 ful. But although Vegetius, and Ammianus Marcelli- 
 nus, and Hero, defcribe the mechanifm of thefe engines 
 with great care, and frequently with mathematical (Icill, 
 ■we fee no attempts to afcertain with prccifion the force 
 of the tm'flile weapon, or to ftate the efficacy of the 
 battering ram, by meafures of the momentum, and com- 
 parifon of it with the refiltance oppnied to it. The 
 engineers were contented with very vague notions on 
 thefe points. 
 
 Ariftotle, in his 2oth Mechanical Queftion, and Ga- 
 len in fome occafional obfervations, are the only au- 
 thors of antiquity whom we recoUei't as treating the 
 force of impulfe as a quantity fufceptible of meafure. 
 Their obfervations are extremely vague and trivial, 
 chiefly diredled, however, to the difcrimination of the 
 force of impulfe from that of preifure. 
 
 In more modern times, great additions had already 
 been made to the afliflance we had derived from the 
 impulfive efficacy of bodies in motion. Water-mills 
 and wind-mills had been invented, and had been applied 
 to fuch a variety of purpofes, that the engineers were 
 fall acquiring more diftinft notions of the foixe oi im- 
 pulfe. Naval conftruftions was changed in fuch a man- 
 tier, that there hardly remained any thing of the ancient 
 rigging. The oblique aftion of wind and water were 
 
 i ] IMP 
 
 now found even more eficflive than thedircif\) and fti'pa Intpu^non, 
 could now fail with almoit any wind. All thefe things ^— •^ -* 
 fixed the attention of the engineers and of the fpecu- 
 latill on the numberlefs modifications of the force of 
 impiille. 
 
 lint it foon appeared that this was a refined branch 
 of knowledge, and required a more profound ftudy than 
 any other department of the fcience of motion. At 
 tlie fame time, it was equally clear, that it was alfo of 
 fuperior importance. Mills worked by cattle, or bv 
 mens hands, were everywhere giving place to wind and 
 water mills ; and a ihip alone appeared to every intelli- 
 gent mechanician to be the greatcil effort of human in- 
 vention, and moft defevving his careful iludy. All 
 thefe improvements in the arts of liic derived their effi- 
 cacy from the impulle of bodies. The laws of impul- 
 fion, therefore, became the objefts of ftudy to all wha 
 pretended to philofophical fcience. But this is a branch 
 of ftudy wholly new, and derives little aflillance from 
 the mechanical fcience already acquired ; for that was 
 confined to the determination of the circumftaiices 
 which regulated the equilibrium of forces, either in their 
 coiribined aftion on bodies in free fpace, or by the in- 
 tervention of machines. But in the produiStion of mo- 
 tion by impulfe, the equilibrium is not fuppofed to ob- 
 tain ; and therefore its rules will not folve the moft im- 
 portant queftion, " What will be the precife motion ?" 
 
 Galileo, to whom we are indebted for the firft dif- 
 coveries in the dotlrine of free motions, was alfo the 
 firft who attempted to bring impulfion within the pale 
 ot mathematical difci^flion. This he attempted, by en- 
 deavouring to ftate what is the force or energy of a 
 body in motion. The very obfcurc refleftions of A- 
 rillotle on this fubjett only ferved to make the ftudy ■• 
 
 more intricate and abftruic. Galileo's refledtions on it 
 .-jre void of that luminous perfpicuity which is fecn in 
 all his other writings, and do not appear to have fatis- 
 fied his own mind. He has recourfe to an experiment, 
 in order to dilcover what preilure was excited by im- 
 pulfion. A weight was made to fall on the fcale of a 
 balance, the other a^m of which was loaded with a con- 
 fiderable weight ; and the force of the blow was efti- 
 mated by the weight which the blow could thus ftart 
 from the ground. The reiults had a certain regularity, 
 by which lome analogy was obferved between the 
 weights thus ftarted and the velocity of the impulfe ; 
 but the anomalies were great, and the analogy was lin- 
 gular and puzzling; it led to many intricate difcuflions, 
 and fcience advanced but flowly. 
 
 At laft the three eminent mathematicians, Dr Wal-Laws of 
 lis, yir Chriftopher Wrenn, and Huyghens, about the impulfion 
 fame time, and unknown to each other, difcoveredj^'^""''^''^'' 
 the fimple and beautiful laws of collifion, and commu- \y^^„j^ ^J^ 
 iiicated them to the Royal Society of London in 1668 Huyghens 
 (Phil. Tranf. n° 43—46.). Sir Chriftoplier Wrenn 
 alfo invented a beautiful method of dcmonftrating the 
 doctrine by experimen-t. The bodies which were made 
 to ftrike each other were fufpended by threads of equal 
 length, fo as to touch each other when at reft. When 
 removed from this their vertical fituation, and then let 
 go, they ftruck when arrived at the loweft points of 
 their refpeftive circles, and their velocities were propor- 
 tional to the chords of the arches through which they 
 had defcended. Their velocities, after the ftroke, were 
 
 uitafuredj..
 
 I IVl P 
 
 Impulfioii. meafurec^, in like manner, by the chords of their arches 
 '— — V 'of afcent. The experiments correfponded preciltly 
 with the theoretical duttrine. 
 
 In the mean time, this i'libjeft had keenly occupied 
 the attention of phllofophtrs, who found it to be ot a 
 very abftrnfe nature ; or, which is nearer the truth, 
 they indulged in great refinement in prolecuting the 
 ftudy. The fnft attempts to meafure the impullive 
 force of bodies, by letting it in oppofition to prefTures, 
 which had long been mcafured by weights, gave rife to 
 fome very reiined refleftions on the nature of thefe two 
 kinds of forces. Ariilotle had faid that they were 
 things altogether difparate. If fo, there can be no pro- 
 portion between them. Yet the analogy obfervcd in 
 the experiments above mentioned of Galileo, fliewed that 
 impulfe could be gradually augumented, till it exceed 
 any preffure. This iniiicates iamenefs in kind, accord- 
 ing to Euclid himfelf. A curious experiment of Ga- 
 lileo's, in which the impulfe of a vein of water was fet 
 in equilibrio with a weight, feemed not only to eftablilh 
 this identity beyond a doubt, but even to (liew the 
 origin of preflure itfelf. The weight in one fcale is 
 fuftained as long as the ftream of water continues to 
 llrike the other fcale. In this experiment, therefore, 
 preflure is equivalent to continual impulfe. But conti- 
 nual impulfe is not conceivable : we muft confider the 
 impulfe of the ftream as X.\\e fuccejji've impulfe of the dif- 
 ferent particles of water, at intervals which are altoge- 
 ther indiilinguifliable. 
 
 From thefe confiderations were deduced two vei-y mo- 
 mentous doftrines : i. That preflure is nothing but 
 repeated impulle ; 2. That although prefl'ure and im- 
 pulfe are the fame in kind, they are incomparable in 
 magnitude. The inipulie is equal to the weight of a 
 column ot water, whufe length is the height neceffary 
 for communicating the velocity. Now this is incelfaut ; 
 and the weight is fuftained during any the fmallcft mo- 
 ment of time, by the impulfe, not of the whole column, 
 but of the infenfible portion of it which is then making 
 its ftroke. Impulfe, therefore, is infinitely greater than 
 prefl'ure. 
 
 Theie abftrufe fpecnlatlons have a charm for certain 
 ingenious fpeculative minds ; and when indulged, will 
 lead them very far. Accordingly, it was not long before 
 fome of the moft ingenious philofophers of Europe 
 taught that impulfe was the fole origin of preft^ine. 
 There is but one moving power (faid they) in mecha- 
 nical nature : This is impulfe. — Nihil movilur (fays 
 Euler) nijt a contigeo et moto. Moreover, having been 
 long and familiarly converfant with the aftions of ani- 
 mals, and the adtions of moving bodies, and conceiving, 
 with fufficient diftindlnefs, that impenetrable bodies 
 cannot move without moving thofe with which they are 
 furrounded and in contad, they imagined that they 
 fully underftood how all this difplacen)ent of bodies is 
 carried on ; and therefore they maintained, that any 
 motion is fully explained when it is Ihewn to be a cafe 
 of impulfion; But they law many cafes of motion 
 where this impulfion co\dd not be exhibited to the fenfes. 
 Thus, the fall of heavy bodies, the mutual approach 
 or recefs of magnetic and eleftric bodies, exhibited no 
 fuch operation. But even here their experience helped 
 them to an explanation. Air is an invifible (ubftance, 
 and its very exillence was for a long time kiiovvfn to us 
 ©nly by means of its impulfe. As we fee that prelTures 
 
 [ 783 ] 
 
 IMP 
 
 are generated by the impulfe of water and of air, may Impulfior. 
 there not be fluids Hill more fubtle than air, by whofe * 
 
 invifible inipulie bodies are made to fall, and magnets 
 are nude to approach or avoid each other ? The impof. 
 iibility of this cannot be demonftrated, and tli.: laws of 
 impulfe had not as yet been fo far invelligated as to 
 fliew that they were incompatible with thofe produc- 
 tions of motion. It was therefore an open tield for dif- 
 cuflion ; and the philofophers, without farther hefita- 
 tion, adopted, as a firft truth, that all motion what- 
 ever IS PRODUCED BY IMPULSION. The buliiiefs of 
 the philofopher, therefore (fay they), is to inveftigate 
 what combination of invifible impulfions is competent to 
 the produdion of any obferved motion ; fuch as the fall 
 of a heavy body, the elliptical motion of a planet, or 
 the polarity of a magnetic needle. The curious difpo- 
 fition of iron-filings round a magnet encouraged this 
 kind of fpeculation : It looks fo like a ftream of fluid ; 
 but it is a number of quiefcent fragments of iron. This 
 does not hinder us from fuppojhig luch a ftream, not of 
 iron-filings, but of a magnetic fluid, which will arrange 
 (fay the atomifts) thofe fragments, juft as we fee the 
 flote-grafs in a brook arranged by a ftream of water. 
 Fluids, therefore, moving in ftrearas, vortices, and a 
 thoufand different ways, have been fuppofcd, in order 
 to explain, that is, to bring under a general known 
 law of mechanical Nature, all thofe cafes of the pro- 
 duftion of motion where impulfion is not obferved by 
 the fenfes. 
 
 As we have gradually become better acquainted with 
 the laws of the production of motion by impulfion, we 
 have been able to explode many of thofe profl"ercd ex. 
 planations, by fliewing that the genuine refults of the 
 luppofed invifible motions, that i», the impulfions which 
 they would produce, are very unlike the motions which 
 we attempt to explain. It has been flicwn that the vor- 
 tices fu[>pofed by Des Cartes, or by Leibnitz, or by 
 Hnygliens, cannot exill ; and they have been given up. 
 But it is aiifwered to all thofe demonllrations of futili- 
 ty, that ilill the axiom remains. Motion is produced 
 only by impulfe ; but we have not yet difeovered all 
 the polfibilities of impulfion; and we muft not defpair of 
 dilcovering that preeife fet of invilible motions, and con- 
 fequent impulfions, of which the phenomena before us- 
 is the neceftary refult. 
 
 But this is by no means fufficient authority for de-rhrapplU 
 ferting the rule of philofophi/.ing, fo prudently and ju- cation of 
 dicioufly recommended by Sir Kaac Newton ; namely,''''- F'"- 
 not to admit as the caufe of phenomenon any tliinrr"^''' , ' * 
 tnat IS not Jeen to operate in its production. I he pru- 
 dence of this reftridtion is evident ; and it has alfo been 
 fufiieiently (hewn (Philosophy, Eiicycl. n'-' 4.S. &c.), 
 that truephilofophieal explanation, or extenfiou of know- 
 ledge, is unattainable, if this rule be not (tridtly adhered 
 to. We therefore require a cogent reafon for a prac- 
 tice that opens the door to every abfurdity, and that 
 cannot give us the knowledge wluch we are in queft 
 of. What, then, is the reafim that always induces phi- 
 lofophers to have recourfe to impulfion for the expla- 
 nation ot a phenomenon, and to reft fatisfied in every, 
 cafe where it can be clearly proved that the phenome- 
 non is really a calc of impulfion ? We fay that we in- 
 quire into the reafon why a body falls, and that we will 
 be latislied it it can be ihewn ua that it has received % 
 Dumber of impulfions downwavd. Do we inquire whjf 
 
 at
 
 IMP [ 784 ] IMP 
 
 Iinpiiinon, a body in motion puts another body in motion by hit- more exaltod rank, may perceive the operations of mind Itnpuinnn, 
 '■ " V ■ ' ting it? ASid if we do, have we difcovered the reafon ? as clearly as we perceive thofe of matter, while thty 
 
 We believe that none of the philofophers, who have re- 
 courfe to invifible impelh'njr fluids, ever afl{ a reafon for 
 motion by iinpidfion. Indeed they flioulJ not, other- 
 wifi.- it would eeafe to hi a full principle of explanation. 
 Othf.- philofophers, indeed (namely, fuch as alk no rea- 
 fon fur the weight of a body, but the fiat of the Al- 
 mighty), require an explanation of motion by im- 
 pulfe, and think that, in almoil every cafe, they have 
 found it out 
 
 are equally ignorant with ourlelves of the caufes wliicii 
 conned the conjoined events in either of tliofe opera- 
 tions. But " known unto Goo, and to Him alone, 
 are all His works!" |, 
 
 To accompliih this purpofe, we direfted the reader's vVe Warn 
 attention to what palfes in his own mind when he tiiinkstlie cxift- 
 011 the mechanical phenomena of Nature ; on what ln.-"="""°f 
 calls body ; on the perceptions which brin^ it into his -j/.^iiy u- 
 view, and which give him all the notions that he can nicars of 
 If the philofophers adc no reafon for this produflion form of its diftinguilhing, its charaeteriilic properties. touLh. 
 of motion, they muft (that it may ferve as a principle How does he learn that there is matter in a particular 
 of expla:;ation) fay that impulfivenefs is an original pro- place? He has more than one mean of information; 
 perty of matter, either contingent or eflential. Accord- and each of thefe informs him of peculiar qualities of 
 ino-ly, \.e believe that this, or fomething like this, has the thing which he calls inntL-r. Many appearances 
 been affumed as a principle by the greater part of me- fuggell to his mind the prefence of a body. Shew a 
 chanicians. It has been affumed, as we have obferved monkey or a; kitten (and even fometimes a human in- 
 in the article Dynamics, 6'«/>/j/. that a iiwj'ing body fant) a mirror, and it will inilantly grope round it to 
 pofTeffes the power of producing- motion in another body find a companion. Why does the creature grope about 
 by hitting It ; and they call it the impulsive force f o ? It is not contented with the lirll indication of 
 of moving bodies — the force in herent ;«<; mow/i^ /-6'(/)'. matter, and nothing will latisfy it but_ touching or 
 The reader will have obferved, in our manner of treat- grafping what is behind the mirror. It is by our fenfe 
 ing that article, and alio in feveral pafTa'ges of different of touch alone that we get the irrefillible conviftion 
 articles of the Encydnfadia BtUmnka, that we do not that matter or body is perceived by us, and it never 
 confiJer this atfuniption as very clearly authorifed by fails to give us the perception ; nay, we have the per- 
 obfervation, or dedncible by abftraft reafoning, from the cepti>)n even in fome cafes where the experienced phi- 
 firft principles of philofophy. There is no branch of lofopher thinks himfelf obliged to doubt of its truth, 
 natural philofophy on which fo many ingenious differta- Some fenfations, arifing from fpafm, cannot be diitiii- 
 tions have been written ; and perhaps there is none that guilhed from the feeling of touch ; and the patient in- 
 has been more fuccefsfully profecuted : Yet this is the fifts that fomething preffes on the difeafed part, while 
 only part of the fcience of motion that has given rife to the phyfician knows that it is only a nervous affcftion. 
 a ferlous difpute ; a difpute that has divided, and Itill Every perfon will think that a cobweb touches his face 
 
 when an eleftrified body is brought near it, and will 
 try to wipe it off with his hand. But the modern phi- 
 lofopher fees good reafon for afferting, that in this in- 
 ilance our feeling gives us very inaccurate, if not erro- 
 neons, infcjrniation. He (hews that the fad, of which 
 our feeling tiuly informs us, is the bending of the iinall 
 hairs or down which grow on the face, and that thefe 
 only have been touched ; and the followers of Epinus 
 deny that even this has been demonlliated. 
 
 divides, the mechanicians of Europe 
 
 Some may think it prefumptuous in us, in a Work 
 of this kind, which oidy aims at collcding and exhihit- 
 ing in one \it:\v the exi/Iing fcience of Europe, to pre- 
 tend to give new dotlrines, or to decide a queltion 
 which has called forth all the powers of a Leibnitz, a 
 Bernoulli, a Jurin, a M'Eaurin, &c. But we make 
 no fuch pretenfions ; we only hope that, by feparating 
 the queltion from others with which it has, in every 
 inllance, been complicated, anil by confidering it apart. 
 
 The philofopher adopts this mode of perception as Tlie cscite- 
 
 fuch notions may be formed. In perfed conformity to unquelfionable, and allows that, and that alone, to be ment of 
 the principles adopted by all parties, that the myftery, matter, which invariably produces this fenfation by <^'^"-^gj',';'^^J'i^j' 
 
 vvhic'h has gradually gathered like a cloud, may be dif- 
 pelled, and all caufc of difference taken away. We ap- 
 
 vhieh invariably produces this fenfation by con-'"" 
 tiguity. But engaged in Ipeeulations which fix iiis at-L th»"fecl. 
 tcntion on the external object, he negletts and over-i„^, of ex- 
 
 prehend that this requires no very extenfive knowledge, looks the inffrument of information, and its manner of treed pref:. 
 ftrid attention to the conceptions which producing the elfea, juft as the allronomer overlooks '""=• 
 
 but merely a 
 
 we form of the aftions of bodies on each other, and a 
 precifion in the ufe of the terms employed in the dif- 
 , cuflion. 
 
 Inquiry in- We truft that our philofophical readers perceive and 
 to its truth. approve of our anxiety to ellablifh (in the article Dy- 
 namics, Suppl.) the leading principles of mechanical 
 philofophy, from which we are to reafon in future on 
 acknowledged facts, or laws of human thought. It 
 is not fo much the queftion, What is the effence of ma- 
 terial Nature, fr>)ni which all the appearances in the 
 univerfe uroceed? as it is. What do we know of it? how 
 
 the telefcope, and the union and decuffation of the 
 rays of lig'it which form tlie piduie by which he per- 
 ceives tiie fatellite of Jupiter travel acrols his dilk. 'J'he 
 pliilofopher finds it convenient to gencralifc the iin- 
 menfe variety of touches which he feels from external 
 bodies, and to confider them as the operations of one 
 and the fame dilcriininating quality, a pROPEaTY inhe- 
 rent in the external fubllance body : and he gives it a 
 name, by which he can excite the fame notion in the 
 minds of his hearers. It is worth while to attend to 
 what has bcjin done in this matter, becaufe it gives much 
 
 do we co'me by this knowledge ? and what ufe can we information concerning the firft principles of mecha- 
 make of it ? The taenia knows nothing of the folar nifm. An exquifite painting has fometi'mes fuch an ap- 
 fyilem, and man is ignorant of the caufc of impulfive- pearance of prominence, that one is difpofed to draw 
 nefs. 'other intelligent creatures may have fenfes, of the finger along it, and we cxped to feel fome rough- 
 which this is the proper objetl ; and others, of a Hill nefs, fome obflrutiion, fomething that prevents the fin. 
 
 ger 
 
 \
 
 IMP [7 
 
 Impulfion. ger from going over the place, rerhnps we doubt, and 
 
 ^— n( want to be affuied. Wc picl'n a little cloicr ; but tctl 
 
 no obftrud^ion ; and we dcUft. 'I'iie very full appear- 
 ance, therefore, which this indicating quality, viewed as 
 the properly of external matter, has in our conceptions, 
 is that of a 1 obftrudion, an obllacle, to the exertion of 
 one of our nutur.il powers. The power exerted on this 
 occalion is familiarly and iiyhuttl-vely known by the 
 name of pressure. This is the name of our own ex- 
 ertion, our own adion ; and, in this inftance, and (we 
 think, in this alone, the word is uled purely, primitive- 
 ly, and without figure. When we fay that a Hone 
 pred'es on the ground, we fpeak figniatively, as truly 
 as when we fay that the candkilick Ibnds, and the 
 fnuffers lie, on the table. It is a perfonification, autho- 
 rifcd by the fimilarity of the cfled.s and appearances. 
 Further, when wt fpeak of our pvelfure on any thing, 
 with the intention of being precife in our communica- 
 tion, we fpeak only of what obtains in the touching 
 parts of the linger and the thing prelTed, paying no at- 
 tention to the long train of intermediate exertions of 
 the mind on the nerves, the nerves on the mufcular 
 fibre, the fibre on the articulated machine, and the ma- 
 chine on the touching part of the finger. And thus 
 the exertion of the fentient and adive being is attribu- 
 ted to the particles of lifelefs inattive matter at the ex- 
 tremity of the finger, and tliefe are faid to prefs imme- 
 diately on the touching parts of the external body. 
 And, laftly, as this our exertion is unqnellionably the 
 perceived employment of a faculty in us, which we call 
 force, power, Jlrcngth, dillinguiiliing it from every other 
 faculty by thefe names ; we fay (but figuratively), that 
 force or power is exerted at the tips of the fingers, and 
 g we call it the force of pressure. 
 And pref- By far the greatell part of our aftions on external 
 fure i~ co:i bodies is with the intention of putting them out of 
 ccivcd or [},(,ir prefent fituations ; and we can hardly feparate tlie 
 a'Jmoft' ' tbought of exerted prefiure from the thought of mo- 
 every [.rn- tion produced by it. Therefore, almoll at its firft ap- 
 diidinn of pearance in the mind, preffure comes before us as a Mo- 
 niution. VI NG POWER. Nay, we apprehend, that the more we 
 fpeculate, and the more we aim at precifion in our con- 
 ceptions, we fhall be the more ready to grant that we 
 have no clear conception of any otlier moving power. No 
 man will contend that he has any conception at all of 
 the power exerted by the mind in moving the body. It 
 is of importance to refleft on the manner in which 
 this notion is extended to alj other produftions of mo- 
 tion. We think that this will fliew, that in every cafe 
 Q we fuppofe preffure to be exerted. 
 
 Examiua- The philofopher proceeds in his fpeculations, and 
 *'°" °f 't^^ obferves that one man can prefs on another, andean 
 pufh him out of his place, in the fame way as he re- 
 moves any other body ; and he cannot obferve any dif- 
 ference in his own exertions and lenfations in the two 
 cafes. But the man who is pulhed has the fame feel- 
 ings of touch and preffure. By withdrawing from the 
 preffure, he alfo withdraws from the fenfation; by with- 
 llanding or refilling it, he feels the preffure of the other 
 man ; and what he feels is the fame with what he feels 
 ■when he prelfes on the other perfon, or on any piece of 
 matter. The fame fenfations of touch are excited. He 
 attributes them to the prefiure of the other perfon. 
 Therefore he attributes the fame fenfations to the coun- 
 ter preffure of any other body that excites them. Far- 
 SUPPL. Vol. I. Part II, 
 
 inllanc<;& (if 
 this perccp 
 tion. 
 
 R5 1 IMP 
 
 thcr, he can refiil to fuch a degree that he is not puili- '"'i'^'f'""-^ 
 ed from his place. In this cafe, the greatell preffure is 
 exerted, and is felt by both. Each feehi that the more 
 he relids, the greater is the mutual preffure. And each 
 feels that, unlels he nol only do not rejift, hut alfo •witb- 
 dratv himfcif horn {\v: pnlTure of the other, he will be 
 preffed, and the other will ftel counter preli'urt, the 
 fame In kind with what is produced by his refitlance, 
 though lefs in degree. jq 
 
 All thefe things are diflinftly and invariably felt ; They are 
 but they require attention, in order to be lubjefts of generally 
 recollcdion and after-confidcration. From tins, and *>'""''**• 
 no other fources, arc derived all our notions of corpo- 
 real preffure, of counter preffure, of adion, readion, 
 oi rejyjatice, and of ina^/ivity or inertia. Our notions 
 of moving power, of the mobility of matter, and of the 
 ntcifiuy of this power to produce motion in matter, 
 have the fame origin. Our notions alfo of the refill- 
 ance of inanimate matter, indicated by the expendi- 
 ture of adual preffure, are formed from the fame pre- 
 mifes : the countcr-preffure, or what at leall produces 
 the fame feelings in the perfon who is the mover. Is 
 confidered as the property of dead matter ; becaufe we 
 feel, that ifa'f do not exert real force, we are dilplaced 
 by the fame preffure that would dilplace a lifclefs body 
 of the fame bulk. 
 
 Thefe dircd inferences are confirmed as we extend yr^ ^j,. 
 our acquaintance with things around us. We can cx-fir^f many 
 ert our force in bending a fpring, and we feci its coun- r''^''''"'^*- 
 ter-preffure, precifely fimilar to that of another man. 
 We feel that we mufl continue this preffure, in order 
 to keep it bent ; and that as we withdraw our pnfTure, 
 the fpring follows our hand. Hill producing fimilar feel- 
 ings in our organs of touch, and requiring fimilar exer- 
 tions of our flrength to keep it in any ftate of tenfion, 
 Thefe phenomena are interpreted as indications of pref- 
 fures adualiy exerted by the fpring, and quite different 
 from v/hat we {Ik^uIJ feel from its mere reliilance to be- 
 ing moved. This adion refembles our own exertion in 
 every particular; it produces all the effeds of preffure ; 
 it will fqueeze in the foft flexible parts of our body 
 with which we ad on it ; it will coniprefs any foft bo- 
 dy, jufl as we do ourfelves ; It will put bodies in mo- 
 tion. Farther, we can fct the adion of one fpring in 
 oppofition to that of another, and obferve that each is 
 bent by bending the other; and we fee that their touch- 
 ing parts exert preffure, for they will comprcfs any ioft 
 body placed between them. 
 
 Thus, then, in all thofe cafes, we have the fame no- 
 tion of the power immediately exerted between the 
 two bodies, animated or inanimated. It is always pref- 
 fure. If indeed we begin to fpeculate about the moJut 
 operandi in any one of thefe inftances, we find that we 
 mufl Ilop fiiort. How our prefiure excites the feeling 
 of preffure in the other perfon, or how it produces mo- 
 tion, eludes even conjedure — So it is — Nay,, how our 
 intention and volition caufes our h'nib to exert this pref- 
 fure, or how the fpilnglnefs of a fpring produces fimi- 
 lar effeds, remains equally hid from our ken. Unwea- 
 ried fl^udy has greatly advanced our knowledge of thefe 
 fubjeds in one refped. It has pointed out to us a train 
 of operations, whicii go on in our animal frame before 
 the oftenfible preffure is produced ; we have difcovered 
 fomething of their kind, and of the order in which they 
 proceed ; we have gone farther, and have difcovered, in 
 5 G fome
 
 I M P 
 
 r 786 ] 
 
 I M P 
 
 ImpulGon. Come of the prtnfures exerted by lifcltfs matter, fimilar 
 ^"""^'"■"^ trains of intervening operations. In the cafe of a ipring, 
 we have difcovered that there is a certain combination 
 of the properties of all its parts neceifary for the vifible 
 exertion. But what is the principle which thus makes 
 them cooperate, we cannot tell, any more than in our 
 own exertions of prelTure. Such being tlie origin of 
 our notions on thefe fubjcds, it is no wonder that all 
 our langnajTe is alfo derived from it. Force, power, pref- 
 furre, action, re-adion, refinance, impullion, are, with- 
 out any exception, words immediately expreflive of our 
 own exertions, and applied metaphorically to the phe- 
 nomena of matter and motion. 
 
 Laftlv, when we fee a body in motion difplace another 
 body by hitting it, and endeavour to form a notion of 
 the way in which this motion is immediately produced, 
 fixing our attention on what paffes in the very intlant 
 of the change, we find ourfclves iiill obliged to fuppofe 
 the thing we call preffure. We can have no other con- 
 ception of it ; and there is no violence in this a6l of tlie 
 imagination. For we know, that if we are jollied from 
 our place, and forcibly driven againft another perfon, 
 we put that perfon in motion without any intention or 
 aiftion of our own ; and we experience, in doing this, 
 that the very fame feelings of touch and preffure are ex- 
 cited as in the inlbnces of the fame motions produced 
 by exerted preffion. We alio fee, that when a body 
 Itrikes another, and puts it in motion, it makes an impref- 
 lion or dimple in it if foft, or breaks it if brittle ; and, 
 in (liort, produces every effeft of preffure. A ball of 
 foft clay makes a dimple in the ball of foft clay which 
 it difplaces, and is dimpled by it. Springy bodies com- 
 prefs each other in their collilions, and refile from each 
 other. In fliort, in every cafe of this clafs, mutual 
 jjreffure, indicated by all its ordinary effefts, appears to 
 be the intermedium by which the changes of motion 
 are immediately produced ; and the previous motion of 
 the ftriking body feems to be only the method of pro- 
 ducing this preffure. 
 
 From this copious induflion of particulars, and care- 
 ful attention to the circumilances of each, we thmk it 
 diQlna no-pjgjn^ [j^^j preffure is the only clear notion that a mind, 
 tion of a ^^^ familiar with fcrupalous difcuffion, forms of moving 
 power ; and therefore that it is veiy Angular to think of 
 excluding it from the liil, and faying that impulfion is 
 the only power in nature, and the fource of all preffure. 
 It may perhaps be faid, that the mutual immediate 
 adlion to which the vulgar, and many philofophers, 
 have erroneoufly given the metaphorical name preffure, 
 is indeed the real caufe of motion, or change of mo- 
 tion ; but ftill it is now properly called impulfion, be- 
 caufe it h occafioned only by the previous motion cf 
 the impelling body. We conceive clearly (they may 
 fay) how this previous motion produces the impulfion. 
 Since matter k impenetrable, we fee clearly that a fo- 
 lid body, or a folid particle, cannot 'proceed without 
 difplacing the bodies with which it comes into contaft ; 
 we have notions of this as clear as thole of geometry ; 
 whereas, how preffure is produced, is inconceivable by 
 us. If we prefs a ball ever fo ftrongly againfl another, 
 and remove the obflacle which prevented its motion, it 
 will not move an inch, unlefs we continue^ to follow it, 
 and prefs it forward ; but we fee a moving body pro- 
 duee comprefGon, bend fprings, make pits in foft bo- 
 
 71 
 
 PrelTare is 
 the only 
 
 moving 
 j,i/wer. 
 
 dies, and produce all the effefts of rsol animal pvtfTure. Impulfion. 
 Impulfe, therefore, is the true caufe of motion, and the » 
 
 folicilation of gravity is nothing but the repeated im- 
 pulfe of an invilible fluid. 
 
 But, in the iirfl place, let it be obferved, that both 
 parties profeis to explain the phenomena of mechanical 
 nature, that is, to make them enfier conceived by the 
 mind. Now it may be granted, that could we have any 
 previous conviftion of a fluid continually flowing to- 
 ward the centre of the earth, we could have fome no- 
 tion of the produdlion of a downward motion of bodies, 
 but not more explanation than we have without it, be. 
 caufe impuUivcnels is as little underflood by us as pref- 
 fure. 
 
 But there arethoufands of inffances of moving forces j_ 
 where we cannot conceive how they can be produced Many pref- 
 by the impulfe of a body already in motion. There ap- fures are 
 pear to be many moving powers in nature, independent jncxijlica^ie 
 of, and inexplicable by, any previous motion ; thefe ^^j, 
 may be brought into adfion, or occafions may be afford- 
 ed for their attion, in a variety of ways. The mere 
 will of an animal brings fome of them into adtion in 
 the internal procedure of mufcular motion ; mere vi- 
 cinity brings into action powers which are almoll irre- 
 fiftible, and which produce moll violent motions. Thus 
 a little aquafortis poured on powdered chalk contained 
 in a bombfliell, will burll it, throwing the fragments to 
 a great diftance. A fpark of fire brings them into ac- 
 tion in a mafs of gunpowder, or other combuifibles. 
 And here it deferves remark, that the greater the mafs 
 is to which the fpark is applied, the more violent is the 
 motion produced. It would be jufl the contrary, if 
 the motion were produced by impulfe. For in all cafes 
 of impulfion, the velocity is inverfely proportional to 
 the matter that is moved. When a fpring is bent, and 
 the two ends are kept together by a thread, a preffure 
 is excited, which continues to aft as long as the thread 
 remains entii-e. What contrivance of impelling fluid 
 will explain this, or give us any conception of the total 
 ceflation of this preffure, when the thread is broken, and 
 the fpring regains its quiefcent form ? 14 
 
 We can explain, in a moll intelligible manner, why .All pref. 
 the hardell preffure produces no feniible motion in the f"'^' ''^ 
 cafe referred to above. We can conceive, with luffi- "^^J'^ f^n, 
 cient diilindncfs, a tube filled with fteel wires, coiled fibU nio- 
 up like cork fcrews, and comprcffed together into ^^t\\ uon. 
 of their natural length. A tube of 10 inches long will 
 contain 100 of then>. While in this ftate, compreffed 
 by a plug, we can fuppofe each of the fprings to be 
 tied with a thread. Snppofe now that the thread of 
 the fpring next the piilon is burnt or cut ; it will prefs 
 on the piilon, and force it out, accelerating its motion 
 till it has advanced one inch ; after this, the piilon 
 will proceed with a uniform motion. It is plain that 
 the velocity will be moderate, perhaps hardly fenf.blc, 
 becaufe the preffure afted on it during a very fliort time. 
 But if two fprings have been let at liberty at the fame 
 inflant, the preffure on the piilon will be continued 
 through a fpace of two inches, and the final velocity, 
 will be greater, becaufe the fame (not a double) prel- 
 fure will be exerted through a double fpace. Unbending 
 four fprings at once, Vi'ill give the piflon a double veloci- 
 ty (See Dynamics, ^(//'/>/. n° 95.) Now the effeftofthe 
 motion of the fecoad fpring is to keep the preffure of the 
 
 firit
 
 IMP [ 7S 
 
 Trnpiiinon. fird in a<^i"on during a longer time, I))' following it, and 
 • keeping it in a ilatc of compreflion. There is nothing 
 iiippoiVd of this kind in the cale of ftrong prtHure h1- 
 luded to ; and therefore no motion is produced when 
 the obftucle is removed, except what the inlenlible com- 
 pielTion produces by accelerating the body aUiiig an iii- 
 fenlible Ipace. If all the icO fpriiigs are difengaged at 
 once, the pillon will be accelerated throngh 100 inches, 
 ^nd will acquire ten times the velocity that one fpring 
 can communicate. [N. B. The force expended in mo- 
 ving the fprings themfelvcs is not confidcrcd here). 
 
 It is In this way only that the previous motion of 
 
 the impelling body aiAs in producmg a c-onliderable 
 
 motion. The wliole procefs will be minutely conlider- 
 
 15' ed by and bye. 
 
 Imcii'.fionis w^ may now adc, liow it is fo clear a point, that a 
 
 ■no- more j-^]jj i-^oj^. ji, nunion mufl diiplace other bodies .'' This 
 
 clearly con. ^ . . ' r 1 ir 
 
 ^jn,g,( tl-jn iecms to be the very point in i|uettion, Is the aitirma- 
 
 prcffure. live deduced from our notion of folidity ? What is our 
 notion of folidity, and wlience is it derived .'' We ap- 
 prehend that even tliis primary notion is derived from 
 prelfure. It is by handling a thing, and tinding that 
 we cannot put our hand Into the place where it is with- 
 out dilpljicing it, that we know that it is material. All 
 this is indicated to us by the feeling excited by our 
 preffure. We feel tiiis property always as an obtlacle; 
 and therefore fay, that by this property it refills our 
 preflure. Nay, tiiere are cafes where even the philo- 
 fopher prefers tin's quality to impulhvenefs as a tell of 
 matter. To convince another that the jar out of which 
 he has poured the water that filletl it is not empty, but 
 full of matter, he dips the mouth of the jar into water, 
 and Ihows, that although he prefs it down till the fur- 
 rounding water is above the bottom of it, the water 
 has hardly gotten half an inch into the jar ; there is 
 fomething there which keeps it out ; there is matter in 
 it. He then opens a hole in the bottom of the jar ; 
 the water immediately rifes on the infide of the jar, and 
 fills it. He fays that the preffure of the water has 
 driven the matter out by the hole ; and he cotijiims the 
 materiality of what is expelled by holding a feather 
 Shove the hole. It is agitated, Ihewing that the ex- 
 pelled thing has impulhvenefs, another property (he 
 fays) of matter : what filled the jar was air, and air in 
 motion is wind. The philofopher can exhibit foine 
 new cafes, where fomething like impulhvenefs appears. 
 A tlender magnet may be fet on one end, the fouth 
 pole, for inftance, and will Hand in that tottering fitua- 
 tion. If a perfon l-iing the north pole of a powerful 
 magnet haltlly near the upper end, it will be thrown 
 down, jull as it may be blown down by a puff of wind ; 
 therefore (fays the philofoplier) there may be appear- 
 ances of impnlfion, and I may imagine that there is 
 impelling matter ; but notiiing but matter excludes all 
 other matter from its place : this property, therefore, 
 is the fiirell tell of its prcfence. 
 
 Thus we fee, that our notion of folidity or impene- 
 trability (a name Hill indicating an obflacle to pref- 
 fure), gives us no clearer conception of the produc- 
 tions of motion by impulfion than preffure does ; for 
 it is the fame, or indicated by the fame fenfations. 
 The quellion now feems to be reduced to this — Since 
 tran»fufing the llrongcll preffure of a quiefcent body does not pro- 
 inherent j^^j,g [„(,[j(,p Qr excite that kind of preffure which is 
 lorce or in , . . . ,- r • ,•,.,. 
 
 hereiitmo- ^"^ immediate caule 01 motion, while a body in mo- 
 tion. 
 
 i6 
 
 Motion 
 does not 
 impel by 
 
 7 ] IMP 
 
 tion, exciting but a very moderate prcfTuie 'aR may be lmf\\\(\<^a. 
 feen by the trifling conipre//ion or dim])ling), ))roduces a * 
 
 very ccuiliileiable motion, how is the previous motion 
 coiuliK-ive to this purpole ? Tiic aniwer ufiially given is 
 this: A body in motion (by whatever caiite) perieverca 
 in tiiat motion by the inherent force ; when It an Ives at 
 anotiicr body, it cannot proceed without dilplacing 
 that body. The nature of the Inherent force is Inch, 
 that none of it Is loll, and that a portion of it piifles 
 into the other body, and the two bodies inllantly pro. 
 ceed with the fame quantity of motion that was In the 
 Impelling body alone. ThI:. Is an exadl enough narra- 
 tive of the general faCl, but it gives no great explanit- 
 tinn of it. If the impelling body perfeveres in its mo- 
 tion by means of Its inherent force, that loirc is ex- 
 erted in performing its office, and can do no more. 
 The Impelled body feems as much to poffel's an Inherent: 
 force ( for the fame markj and evidences of preffure 
 on both fides are obferved in the colliluju. If both 
 bodies are foft or conipreflible, both are dyr.plcd or 
 compvelfcd. We are as much entitled, therefore, to 
 fay, that part of the force by which It perfeveres at 
 reft, pafits Into the other body. But the rcll, or qulef- 
 cence of a body. Is always the fame ; yet what pafTcu 
 into the impelling body Is different, according to its 
 previous velocity. We can form no conception how 
 the half of the Inherent force of the impelling 'lody is 
 expended by every particle, pr.ffes through the points of 
 conti'd, and is diflributed among the particles of the 
 impelled body ; nay, we cannot concflve this halving, 
 or any other partition of the force. Is It a thing yi/i 
 generis, made up of Its parts, which can be detached 
 from each other, as the- particles of fait may be, and 
 really are, when a quantity of frelh water Is put into 
 contacl with a quantity ot brine ? We have no clear 
 conception of this ; aud therefore this is no ehicldation 
 of the matter, although it may be an exadt llatement 
 of the vlfible faft. j^ 
 
 Let us take the fimplell pofTible cafe, and fuppofe This in- 
 only two particles of matter, one of which is at reft, ™'''=' *''- 
 and the other moves up to It at the rate of two feet'"'"""'" 
 per fecond. The event Is fuppoled to be as follows : In 
 the Inllant of contadl, the two particles proceed with 
 half ot the foruer vdoeity. Now this Inllant of time, 
 and this pieclfe point of fpace, In which the contadt is 
 made, is not a part of either the time or ([lace before 
 collihon, or of iholc after collilion ; it Is the boundary 
 between Ijoth ; It Is the lall Inllant of tlie former time, 
 and the full Inllant of the latter time ; it belongs to 
 both, and may be fald to be in both. What is the Hate 
 or condition ot the impelling particle in this inllant ? la 
 virtue of the previous motion, it has the determination, 
 or the force, or the power, to move at tlic rate of tw(t 
 feet per fecond ; but, in virtue of the motion after col- 
 lllion, it has the determination or power of moving at 
 the rate of one foot per fecond. In one and the lame 
 inllant, therefore. It has two determinations, or only 
 one of them, or neltlier of them. And It may, In like 
 manner, be fald of the Impelled body, that. In that In- 
 Raiit, it was both at reft, and moving at the rate of one 
 foot per fecond. This feems Inconceivable or abfurd. iS 
 
 It Is not perhaps very clear and demonfliable, nor 'mpiilfive. 
 is It intuitively certain, that the moving body or par-" . """' 
 ticle mull difplace the other at all. All that we know property of 
 is, that matter is moveable, and that caufes of thismatter. 
 4 G 2 motion
 
 IMP 
 
 Impulfion. motion exift in nature. When they have produced 
 ' this motion, they have performed their xhCh, and the 
 
 inorlon is their complete efFeft : the particle continues 
 in this condition for ever, unlcls it he changed hy fome 
 caufe ; hut we do not fee any thing in this condition 
 that enables us to fay what caufes are competent to 
 this change, and what are not. Is it cither intuitive 
 or denionilr:ible, that the mere exij/ctice of another par- 
 tide is not a fufficient or adequate caufe ? Is it certain 
 that the arrival at another particle is an adequate cauie i 
 or can we prove that this will not Itop it altogether ? 
 The only conclufion that we can draw with any confi- 
 dence is, that " two particles, or two equal bodies, 
 meeting with equal velocities, in oppofite directions, will 
 flop." But our only reafon for this conclufion is, that 
 we cannot affign an adequate reaton why either (hould 
 prevail. But this form of argument never carries lumi- 
 nous conviction, nor does it even give a decifion at all, 
 unlefs a number of cafes can be fpecified which include 
 every poJpUe refuh. This can hardly be affirmed in the 
 ip prefent cafe. 
 But an ob- We apprehend that the next cafe, in point of fim- 
 ferved faft. p];^;^^.^ has ftill lefs intuitive or dedudtive evidence; 
 namely', when bodies meet in oppofite direftions with 
 equal quantities of motion. It is by no means eafy, if 
 it be at all poffible, to fhew that they mult ftop. The 
 proof proceeds on fome notion of the manner in which 
 the impulfion, exerted on one particle, or on a few of 
 each body, namely, thofe which come into contaft, is 
 diftributed among all the particles. A material atom 
 is moved only when a moving force atts on it, and 
 each atom gets a motion precifely commenfurate to the 
 force which aftuates it. Novi', it is fo far from being 
 clear, how a force impreffed on one particle of a iolid 
 body occafions an equal portion of itfcU to pafs into 
 every particle of that body, and impel it forward in 
 the fame direftion, that the very authors who aflume 
 the prefent propofition as an elementary truth, claim 
 no finall honour for having determined with precifion 
 the moving forces that are exerted on each particle, and 
 the circumftances that are neceffary for producing an 
 equal progref[ive motion in each. It was by no means 
 an eafy problem to lliew, that the motion of the body 
 (eftimated by an average taken of the motions of every 
 particle) is precifely that which is announced by this 
 propofition. We mud alfo confider how this inveiliga- 
 tion is condufted. It is by affuming, that whatever 
 force connefts a particle a with a particle h, or what- 
 ever force a exerts on b, the panicle h exerts an equal 
 force on a in the oppofite direflion — Surely no logi- 
 cian will fay that this is an intuitive truth. The con- 
 trary is mofl diltinCtly conceivable. It was a difcovery 
 of the aftronomeis, that every defleftion toward the 
 fun is accompanied by an equal cefleilion of the fun. 
 It was a difcfjvery, that a piece of iron attrads a load- 
 ftone ; and it was a difcovery (and we dare not yet af- 
 firm it to be without exception), that every aftion of 
 bodies is accompanied by an equal and contrary re-ac- 
 tion. But this is by no means a firft principle. It is 
 the expreflion of a moil generally obferved faOrt, a fum 
 total of knowledge. When received on this authority, 
 it is fully competent to folve every cafe of impulfion, in- 
 dependent of all obfcure and illogical dodriries of force 
 inherent in moving bodies, of force of inertia, of com- 
 munication of motion, &c. 
 
 C 7S8 ] 
 
 I M P 
 
 The impofllbility of conceiving the detachment of ImpulCoi 
 part of the force inherent in A, and transferring this ' ' v - 
 part into B, and the fimilar impoflibility of conceiving 
 the imparting to B fiime of the motion that was in A, 
 (liould make us rcjetl any propofition involving fuch 
 conceptions, and rcfufe its admithon as an elementary 
 truth. Much more Ihould we rcjed a propofition that 
 obliges us to fuppcfe that a particle of matter has two 
 determinations, forces, motions, or call them by any o- 
 ther name, in one and the fame inftant. One of thefe 
 neceflarily excludes the other. Indeed this was fo evi- 
 dent, even to the mofl eminent partizans of the doc- 
 trine of the transfufion of inherent force, and others 
 confequent on it, that they found themiclves obliged to 
 deny that there was fuch a thing in the world as a 
 perfeftly hard body, in which the motion mull be in- 
 llantaneoully changed into another, differing from it 
 by any fcnfible quantity. The exillence of perfectly 
 hard bodies is pofiiivcly denied by the cekbrated ma- 
 thematician of Balle, John Bernoulli, in his DilTerta- 
 tion on the Communication of Motion, which contend- 
 ed for the prize given by the Academy of Sciences at 
 Paris 1710. His reafon for this rejedion is fingular, 
 and fomevvhat amufing. " In the collifion of perfedly 
 hard bodies, the confervatio •virlum vivarum, demonflra- 
 ted by the moll eminent mathematician (Mr Leibnitz), 
 to be a law of nature, would be broken without any 
 cfFed being produced. He does not obferve,' that it 
 is as completely broken by elallic bodies in the in- 
 flant of greatell compreflion. A Britilh philofopher, 
 nullius addidus jurare In verba mag'ijlri, alked. What 
 will be the caie of two encountering atoms of mat- 
 ter ? Without calling thein hard, we mull conceive 
 that they acquire their changes of motion in the in- 
 flant of mutual contad, and that they acquire them 
 totally', being ^ij-j^oi, indivifil)le. No anfwer has been 
 given, or indeed can be given, but what implies the 
 fame difficulty. From all that has been laid, we mufl 
 conclude, that this branch of mechanical philofophy 
 is not put, by thofe philofiiphcrs, into the condition of 
 an elementary foundation of clear and demonflrative 
 fcience ; that the transfufion, or transference, either of 
 force or inotion, is not a thing of which we have a dif- 
 tind conception ; and that it necelfarily leads us into 
 very untenable dodrines. Far lefs does it fcem fafe for 
 us to confide fo much in its clearnefs and certainty, as 
 to affirm, that impulfion is the fole moving force in me- 
 chanical nature, and the fource of what we call preffure. 
 
 All this difficulty and obicuiity has arifen from our 
 arrogant notion, that we are competent judges of firfl 
 pr'wc'tples ; whereas we mull acknowledge, that we can 
 only perceive fuch as are properly related or accomino- 
 dated to our intelletlual powers: thefe powers, being 
 fpecific and peculiar, cannot judge of principles of the 
 firll clafs, but of thofe only that are fuitably compound- 
 ed. We can never know or comprehend any eflential 
 property of matter — we can only know the relative 
 properties oi fuch matter as we fee. ,g 
 
 Therefore let us quit entirely the barren and tracklefs Therefore 
 fields of abltradion, and refl fatisfied with contemplating to be learn-' 
 'what the Author of Nature has exhiliited to our view,*^?,""'?^ '"' 
 and fuch as he has been pleafed in his wifdom to exhi-„jtyfj_ 
 bit it. We grant that there are no bodies open to 
 our infpedion which are perfedly hard, receiving finite 
 changes of motion in an inftant. It has not pleafed 
 
 God 
 
 i
 
 IMP t 7S9 1 IMP 
 
 Inipiilfiop. God to put any fuch within our reach. When God of its applicabih'ty tb the purpofcs intended. His ap- fmrulficii, 
 
 '"~'v~— cre;iti:d iniittcr, it wss with llie purpofe of toiir.iiig a i-lfcatioii to the piodudiou of motion by the coliifioii *— — y 
 
 beautiful nnivcrfe of tliis matter. He therefore gave of bodies, is peculiarly fatisfatlory. But as the work is 
 
 it prcpoties which fitted it for this purpofe. It is this written ci)ie(ly with the view of gaining the approba- 
 
 niatter only that he has expofed to the wondering view tion of ptilons will iulliuCk'd in natural philofopliy, it 
 
 of man. Thanks to liis bounty, he has alfo given us can hardly be called an elementary work, or be employed 
 
 properties of mind, by which this adaptation, when for the inltruttion of pcrfons entering on the Ikudy. 
 
 perceived by us, becomes a fource of dignified pkaiure We fliall attempt to explain this important law of mc- 
 
 to the ohferver. — A Newton, to whom " Jo-vis omnia chanilm in a way that will give our readers a diftindl 
 
 plcna,^' a Daniel Bernoulli, were rapt almolt into eefla- notion (and, we apprehend, a jull one) of the procc- 
 
 cy by a fmgle atom, v\hen they obfervtd liow its pro- dure of Nature in all the cafes of impulfion ihnt <we can 
 
 pertics, and only fuch propcities, fitted it for making obj'crve. We hope to do this, by conhdeiiiig the 
 
 part of a worhl, which changes of motion produced by moving bodies in a 
 
 TT -1 J r 1 . J certain fcries of familiar ealVs, where the procedure of 
 
 Unwearied, and from day to day, . , ,■,,. r,, , ,■ , , ^ t" •"-"->^""- »^' 
 
 01 ,j -. V^ , ' V, \ nature nia\ be diltinitly oblervcd, and where it is imi- 
 
 bhould Its Creator's power diiplay. f ,„i • j i r n ,,.,'■ 
 
 ■^ '^ ' formly conceived by every fpeaator; and whicii wrtl 
 
 Let the unhappy La Place confider thefe properties, gradually lead the mind to thofe cafes where the proce- 
 
 which cnfure the permanency of the folar lyltem oure is not oblerved with diflii'itnels : but the linu'iarity 
 
 tlnoiigh ages of ages, as prools of fatabfm, ai> qnah'lics to the former cafe is concluded by fo lair analogy, that 
 
 tilential to matter. But this Gallic torch effaces the we imagine no perfon will controvert it. We ihall be- 
 
 bloom of life from the uuiverie, the expreilion of the gin by attending to the manner in which two magnets 
 
 Supreme Mind which fliiues from within; and it fprcads in motion affedt each other's motions ; a phenonieiioii. 
 
 over the coiuitenance of Nature the ghallly palcnefs of that is familiarly known in the general, althougli, per- 
 
 univerfa! death. But let us Britons rather follow the haps, few perlons have attended to it minutely. 
 
 example of our illuftrious countryman, and folace our- Let us, therefore, fuppofe two magnets, A and B Plate xxib; 
 
 (lig. I.) equal in weight (in the firll inftancc). Let V 
 
 tiiera be made to float on water, by placing them on^''^""f''V 
 r ) T 1 1 1 ,^.,°. [loii or tne 
 
 pieces ot coik. Let them be placed with their north nu.tuul ac 
 poles touching each other. Let A be held fall, and lct<i' " "' 
 B be at liberty to move. We know that it will gradual- ""^"^ts- 
 
 »t 
 
 Movi'ig 
 pnwef- ^f"? 
 rihe^ent it 
 ill matte-. 
 Newton's 
 cor):dure 
 imjj-nved 
 by Ecfco- 
 *ich. 
 
 felves with every difcovery wliich tends to quicken our 
 perception of Nature's uw/mfl/tJ charms. Let us iillen 
 to the coiijefturcs of him who had already difcovered 
 fo many, and who endeavoured to remove the veil which 
 concealed the reft. 
 
 Newton, in his maturity of judgment, after having ly recede from A, with a motion that would continual, 
 
 colieiled much information from his unwearied expe- ly accelerate, were it not for the rcfiilance of the water, 
 
 riments in magnctifm, in cheniiltry, in optics, S;c. iaid, What is the inference drawn from this appearance ? 
 
 that " he Itrongly fulpedled, that, in the fame man- Surely this, that either a moving power, inherent in 
 
 ner as the bodies of the folar fyftem were connefted A, repels B, or that B avoids A, by an cvalive power 
 
 by gravitation, fo the particles of fiiblunary bodies inherent in itfelf. It is immaterial for our purpofe 
 
 were conneded together, and affctied each other, by which opinion we adopt. Let us fay that A repels B. 
 
 means of forces wliich afted at fmall, and, in many This admits more concife language than the other If 
 
 cafes, infenfible diftaiices ; producing the phenomena vve prevent this motion of B by means of a very flen- 
 
 of coheiion, in all its forms of hardnefs, elallicity, der ipring applied to its remote end, we fliall obierve 
 
 dnflility, foftnefs, fluidity, by which tlicir mechanical that the Ipring is bent back a little, juft as if we were 
 
 aftions on each other were modified and regulated." pufliing away the magnet gently with tiie finger; and we 
 
 Father Bofcovich, one of the firfl mathe.iiaticians of obierve, that the bending of the fpring is fo much the 
 
 Europe, was the firll who gave this conjedture of New- greater as B is nearer to A. We can judge of the in- 
 
 ton's the attention that it fo highly dcierved. Other tenlity of the force by which B is adtuated, by the 
 
 bending of the fpring.— This force is equal to the nveight 
 
 writers indeed, fuch as Kcill, Freind, Boerhaave, &;c. 
 took occafional notice of it, and even made fomc ufc of 
 it in their attempts io explain fome complicated phe- 
 nomena of natore. But they were fo carelefs in their 
 employment of Newton's conjedture, fo completely ne- 
 
 of any body that will bend the fpring to the fame de- 
 gree. I'his force is analogous, therefore, to the weight, 
 ■' e prellure of gravity, and we may call it a preflure, 
 -■ meafure it by grains weight. Every force that 
 
 til 
 and 
 
 gledled his cautious manner of proceeding, indulged can bend a fpring will move a body. 'I'his is a welL 
 lo wantonly in hypothetical affumptions, and reafoned known fadl. Therefore it is next to certain, that it is 
 
 fo falfely from them, that they brought his conjedture 
 into difcredit. Bofcovich, on the contrary, copied 
 Newton with care, and fecured his progrefs as he 
 advanced by the aid of geometry ; eilablifliing a fet 
 of uncontrovertible pn^politions, which muff be the in- 
 evitable refults of the premifes adopted by him. He 
 then proceeded to compare thefe with the phenomena 
 of nature ; and he fhews that the coincidence is as com- 
 
 this force which caufes B to recede from A ; nay, if 
 we compare the motion of B with v.\aX. JJjoulil refult 
 from the adfion of a force having this very intenfity, 
 and varying in the fame manner by a change of dif- 
 tance from A, taking in the diminution which the re- 
 fiftance of the water mull occalion, we fhall find the 
 motions precifely the fame. All this can be difcovered 
 by Dynamics, n° 95, &c. Therefore we mult 
 
 plete as can be defired. All this is done in his Theoria elude that this, and no other, is the caufe of the recefs 
 Philofophia Naluralis, firfl pubhflied at Vienna in 1759. of B. 
 
 We have given a very fhort account of it in the article If, inftead of placing B in contaft with A, we place 
 
 BoscoviCH, Suppl.; but it hardly goes beyond the it at a diflance from it, and pufli it toward A with an. 
 enunciation of the general principles, and the indication initial velocity, fomewliat lefs than it would have ac- 
 quired
 
 70 
 
 IMP [ 
 
 Inipulfior. quirtil in tliat place by I'tf reciiTs from A, we fliall 
 » iind that it will appvoatli A with a niolioii gradually 
 
 retarded, till it Hop 'at a fmall diftance from A ; and 
 will now recede from it again with an accelerated nio- 
 tion. In (hort, we fliall tind that its whole motion to 
 and from A is precifely the fame with what refults from 
 a fmiilar computation by n° 93 of Dynamics. 
 
 The whole of this phenomenon is conceived by every 
 beholder, who has not imbibed fome peculiar theory ot 
 a llreani of impelling fluid, ad the indication and tfiedl 
 of a repulhvc force exerted by A on B, or of a quality 
 of B, by which it recedes from A. 
 
 If now B he held fall, and A be fet at liberty, it is 
 obferved to be repelled bv B, or to recede from B, in 
 the fame manner, and with the fame force. 
 . Thus, the two magnets appear to affeft each other's 
 motions, and are thought, and faid, by all to repel each 
 other. The iffeft appears curious, but excites no far- 
 ther thought in moft minds : it is only the fpeculatift 
 that begins to fufpeft that he has not conceived it pro- 
 perly. 
 
 Now, let us fuppofe that B is afloat on the furface 
 of the water, and at reft ; and that A is pufhed to- 
 waids it, by a Ihigle ftroke, caufing it to move fo mo- 
 derately that it fliall not ftrike B, bivt have its motion 
 delhoytd by the repullion before it reaches it ; and let 
 us farther fuppofe, that the initial velocity of A was 
 exactly nieafured— the faci will be as follows. As foon 
 as A comes within a certain diftance of B, its motion 
 begins to be affeded ; it gra-dually diminiflies, and 
 at length it ceafes entirely, and r\ remains ever after 
 perfectly ftill. But it is alfo obferved, that in the in- 
 flartt that A flackens its motion, B begins to move ; 
 tliat it gradually accelerates in its motion, and at laft 
 acquires the initial velocity of A, with wlu'cli it pro- 
 ceeds, till the refiliance of the water brings it to reft ; 
 perhaps at a confiderable diftance from A. This ex- 
 periment is very anuifmg, and the initial velocity of A 
 nay be increafed in each fucceeding tiial, till at laft it 
 ftrikes B. Even then the general appearance remains 
 the fame : A is brought to reft and remains at reft, 
 neither refding nor advancing forward ; and B moves 
 otF with the initial velocity of A. What we wiflt to 
 be particularly noticed is, that as long as the initial ve- 
 locity of A is lefs than a certain quantity (depending 
 on the ftrength of the magnets), the motion is com- 
 municated to B, or, to exprefs it more cautioufly, mo- 
 tion is produced in B, without any thing happening 
 that can get the name of impulfion with propriety. 
 In the ordinary conceptions and language ot mankind, 
 impulfe always fuppofes aftual contatl ; and impulfion 
 is equivalent to a blow or a ftroke. Both ot thefe 
 are indeed metaphorical terms, as well as inipulllou. 
 Perhaps the word " to hit," exprefles this particular 
 cafe more purely, and it is perhaps without any/igure, 
 and is the appropriate word. We do not fpeak at 
 prefent of the conception and language of philofo- 
 phers, but of perfons taking an unconcerned view of 
 things, without any intention of fpecniating farther a- 
 bout the matter. 
 
 Appearances perfeftly fimilar are obferved in elec- 
 trified bodies. If we hang two equal bunches of very 
 light downy feathers by two equal linen threads, fo as 
 to hang clofe by each other like pendulums without 
 
 o ] IMP 
 
 toucliing, and If, after having eleArined them fo that !MV-.HiiiB, 
 they repel each other to tome diftance, we draw one of — — v"— ^ 
 them, which we (hall call A, -conliderably afide from 
 the perpendicular, and then let it go to fwing like a 
 pendulum j we ihall obferve, that inftead of accelerating 
 till it reach the loweft point of its vibration, its motion 
 will be retarded; it will Hop entirely when its thread is 
 perpendicular, and will remain at reft. In the mean 
 time, the other bunch B will acquire motion, wliich will 
 gradually increafe till it equal the motion of A in its 
 maxiniUiTi (late ; and with this it would proceed for 
 ever, were it not rifing like a pendulum in the arch of 
 a circle. The general faft is the fame as in the cale 
 of the magnets. The moving body is brought to rtft, 
 in which ftate It continues, and the qnielcent body 
 moves oiF with an uhinuile velocity, equal to the initial 
 velocity of the other ; and all this tiajijiens without con- 
 tact or impullion, but is prod'iced by the. mutual re- 
 pulfion of the elettrified bodies. 
 
 If this general fa<5l be compared with what happens 
 in the collifion of two billiard balls, it will be found 
 perfedlly fuiiilar in every refpeft, but that of the con- 
 tail and the impulfion, properly fo called. The im- 
 pelling ball Is brought to reft, and remains at reft ; and 
 the impelled ball moves off with the velocity of the im- 
 pelling ball. 
 
 This being the cafe, it is plain that 'we may derive 
 fome information from the motion of the magnets, that 
 muft greatly atTift us in our conceptions of what pafles 
 in the rapid, if not inftantaneous, production of motion 
 in a billiard ball, by hitting it with another. In the 
 cafe of the magnets, we perceive, and can dilcrlminate, 
 a progrefiive train of changes, which terminate in a fi- 
 nal change, perfeftly iiinilar to the ciiaiige in the im- 
 pulfion of the billiard ball. This will jullify a very 
 minute attention to, and ftatement of, all the circum- 
 llances. ji 
 
 Let us attend to the procefs of this operation, and Firft cafe, 
 the produftlon of motion In the magnet originally at A movii^j 
 reft, and the abolition of it in the one originally In mo-^""'^!,'' ^ 
 tlon ; and let us riffleft on what paflVs in our minds 
 when we try to explain it to ourfelves. Tlic trials men- 
 tioned at firft, when one magnet was held faft, Ihew us 
 that each magnet repels or avoids the other, and tiiat 
 this action is found to be equal on both tides, produ- 
 cing equal compreffion of the Ipring employed for ai- 
 certainlng the Intentity of this repuliion when the di- 
 ftances are the fame. This is the faft. It is no lefs a 
 faft, that equal moving forces,- fuch as equal preflfures 
 muft be fuppofed to be, produce equal changes of mo- 
 tion In their own dlredtlon. Thereioie, as ioon as A 
 comes to fuch a diftance from B that the mutual aftion 
 takes place, both magnets are aftefted, and equally af- 
 fefted ; that is, equal changes of motion are produced 
 on each, but in oppofite direftions. The motion of 
 A is diminifhed, perhaps -r§ijth part In tV^'' "^ ^ ^^' 
 cond, and (let it be carefully remembered) while A 
 paffes over a certain fpace, fuppole the loth of an inch. 
 During this I'mall portion of time, B acquires as much 
 motion as A lofes. This is not the motion loft by A. 
 This Is inconceivable ; for motion Is not a thing, but 
 a condition. But it is an equal degree of motion. B 
 has paffed over a fmall fpace during this time, perhaps 
 the 50th part of an inch, with an almoft Imperceptible 
 
 motion. 
 
 I
 
 I M p 
 
 [ 79' ] 
 
 1 M P 
 
 14 
 rhry ac- 
 Rui'C a 
 common 
 irciucity > 
 
 Irtijiv.lfinn motion, that is gradiiHlly act'okrated from notliiiiff. 
 •—'^ Since A is n\oving fallcr tlian B, it mull ilill gain upon 
 
 it ; and thertiore the mutual ivpulllou will incixale ; 
 and In the next loth of a fecond this force will take 
 another and greater portion of A's original velocity from 
 it, and will add a greater velocity to that already acqui- 
 red by B. And thus, in every fuccetd![ig minute por- 
 tion of time, the motion rif A will be more and more 
 diminilhed, and that of B as much incrcafed, by the 
 equal, though continually increaling, fiinultaneons rc- 
 pulfions aftiiig in oppofite direflions. It is evident, 
 that it is poffible that the velocity of A may be fo 
 much diminilhtd, and that of B fo much increafcd, that 
 the rcinainiiig velocity of A (liall be jnll equal to the 
 acquired velocity of B. Till tliis happens, the diilances 
 of the magnets have been continually diininilhing ; for 
 A has been moving faller than B, and gaining on it. 
 It tlie operation ot the mutual repullions could be (top- 
 ped at this inllaut, both magnets would move forward 
 tor ever with equal velocities. 
 
 It is of particular importance to know what this 
 cominou velocity is. This is determined by our previ- 
 ous knowledge, that the magnets repel or avoid each 
 other with equal forces. Thcie forces may vary by a 
 variation of diitance ; but the force atling on A is al- 
 ways equal and oppofite to the force afting at the fame 
 time on B. This is the uncontroverted faft (the autho- 
 rity for which (tiall foou be confidered). Thefe equal 
 forces mull therefore produce equal and oppolile chan- 
 ges of motion. The motion acquired by B is equal to 
 that loft by A. But the magnets being fuppofed equal, 
 and moving with equal velocities, they have equal quan- 
 tities of motion. Therefore the motion acquired bv B, 
 or that loft by A, is equal to what remains in A ; that 
 is, A has lod half of its motion, and tin refoie half of 
 its velocity ; or the common velocity is half of the pri- 
 mitive velocity of A. 
 
 It was for the fake of a fomevvhat eafier difcnflfion 
 that we fuppofed the magnets to be of equal weights. 
 But it is almoft equally eafy to afccrtaiu what this com- 
 mon velocity will be in any other proportion of the 
 quantities of matter in A and B. It is a matter of uu- 
 excepted experience, that whatever be the weight or 
 ftrength of two magnets, their aitions on each other are 
 always equal. Therefore the fimultaneous force muft 
 always produce equal changes of morion in the two bo- 
 dies. But the change of motion is expre Jed by the pro- 
 duct of the quantity of matter and the change of velocity. 
 Therefore let A and B reprefent the quantities of mat- 
 ter in the magnets ; and let a be the primitive velocity 
 of A, and X the velocity v/hlch obtains when both are 
 moving with one velocity. The velocity loit by A is 
 a — X. Therefore we mutt have B .x = A X a — k, 
 = Art — Ax; andAa = Ax + B.v, = A -f B X -v, 
 
 Namtly, x ^""^ '^ — a , -n' "^^'^ comn.bn velochy is therefore ob- 
 tained by dividing the primitive quantity of motion by the 
 fum of the quantities of matter. 
 
 AX_a 
 ' A + li 
 
 This may be conceived more compendioufly in an- 
 other way. Since B acquires as much motion as A 
 lofes, the whole quantity of motion, is the fame as be- 
 fore : Therefore the common velocity muft be had by 
 dividing this quantity of motion by the whole quantity 
 of matter. But wc wifhed to make the reader keep his 
 
 attention fixed on the fteps of procedure, and fee the Impvilfion. 
 connection ot eacli witli the caufes. ■' ' ' 
 
 We (hall lind that this piriod of the wliole procefs, 
 namely, the moment when both bodies liave acquired a 
 common velocity, and the jirccife magnitude of this ve- 
 locity, are points of peculiar importance in the dodtrine 
 ot inipulUon; indeed they almoll comprehend the whole 
 of it. 
 
 But this is a ftate that cannot fcoiitinue for a moment |j,„ (j,;, 
 in the example before us. The repulfivc or evafive docs not 
 forces are ItiU afting on both magnets, and ftill dimi- continue, 
 ni(h the motion of A, and equally increafe the motion ^"'^ ''*' 
 of B. Therefore the velocity of A, in the very next J"p°"j° j' 
 moment, muft be lefs than that of B ; and B has, dii- 
 ring this moment, gained on A, or has removed farther 
 from it. This continues ; A is ftill retarded, and B is 
 accelerated ; and therefore gains more and more upon 
 A, or leparatcs farther and farther from it. This muft 
 continue as long as the mutual rcpulfions are fuppofed 
 to act. If we hippofe that the fnJMe atliou of thefe 
 forces is limited to lome determinate diftance, the mu- 
 tual action will ceafe when B has got to that diftance 
 beh)re A. We may call it the in.iclive diJJance. After 
 this, A and B will proceed with the velocities which 
 they have at that inliant. Let us inquire into thefe fi- 
 nal velocities; and thus coniplcte our acquaintance with 
 the procefs. 
 
 We fee (and It Is important) that the magnets are'i-hf,"^,,^. 
 in their ftate of greateit proximity at the inftant of their nun vtlo- 
 moving with a common velocity, and that after this ci'y 's at- 
 
 they gradually feparate, till they are aaaiii at their in-'!""T'',f' . 
 ix- j-A i> ■ 1 ■ 1- -I ■ ,-,■ ""•■ inl'i'"t 
 
 active diitance. During this feparation they attain dil-(,f neaicft 
 
 tances from each other equal to wliat they had during ai'pmatti. 
 the period of their mutual approach. At thefe diftau- 
 ces the re])uirions are tlie fame as before, aiid aCt in the 
 fame direction. Therefore, in each moment of fepara- 
 tion, and at each diitance, A fullains the fame diminu- 
 tion, and B gets the fame augmentation of its motion,^ 
 as when they were at the fame diftance in the period of 
 their mutual approach. The fums total, therefore, of 
 thefe equal augmentations and diminutions muft be e- 
 qual to the augmentation and diminution during the ap- 
 jjroach. Therefore the whole diminution of A's mo- 
 tion muft be double of the diminution fultaincd during 
 the approach ; and the whole augmentation of B's mo- 
 lion muft. In like manner, be double of that acquired 
 during the approach of A. Hence we eafily fee, that 
 when the magnets arc fuppofed equal, A muft he 
 brought to reft ; for in the period of approach it h::d 
 loft half of its velocity. It muft now have loft the 
 whole. For fimilar reafons B muft finally acquire the 
 primitive velocity of A ; for in the inftant of greateft 
 proximity, it had acquired the half of it. 
 
 Thus we fee that the equal mutual repnlHons arc pre- Repulfion 
 cifely adequate to the production of the changes of mo- is a caule 
 tion that are really obfervcd; and muft therefore be ad- ^''"^1"^'^ '" 
 
 mitted as the immediate caufes of thefe chan.res. '^j"^*!^" 
 
 . o ved eltccl. 
 
 It IS equally eafy to afcertain the final velocities 19 
 when the magnets are of unequal fizes ; for the equal I- E"^"^* 
 ty of their mutual repuHions Is not aft"eCtcd by any In-"'''" '*" 
 equahty ot their magnitudes. I heir feparations, and areiir.c<iuaL 
 the changes of motion during thefe feparations, will be 
 the fame with their approaches and the correfponding 
 changes of motion ; and the whole change on each will 
 be double of the change fuftained at the inftant of 
 
 greateft
 
 IMP 
 
 [ 7 
 
 Impulflon. greatefl proximity and common velocity. Hence we 
 learn that the final velocity of B is 2 k, or . and 
 
 the final velocity of A is 
 
 i. — B Xa „ , 
 — ror the pn- 
 
 A + B ^ 
 
 mitive velocity of A being a, and the common vcloci- 
 
 ty, in the inllant of nearefl approach being. , the 
 
 lofs of velocity is a 
 
 Aa 
 
 _ A a + B a — Aa 
 A+B' A + B 
 
 _ Therefore the final Idfs of velocity is 
 
 3° 
 II. Cafe 
 
 A+B 
 
 and the remaining final velocity is a — 
 
 A a + Ba — 2 B a 
 
 aITb" 
 
 A- 
 2Ba 
 A+B' 
 
 B 
 
 BXa 
 
 A + B 
 
 Let us, in the next place, fee what will be the refult 
 
 Both niag. ^yjjgn j,oth of the mag lets are in motion at the begin- 
 
 .;™ •'„„„. nincr of their mutual attion. And, firft, let both move 
 cion in one o t a . • i i_ i ■ 
 
 direflion. in one diredion. Let A, moving vvitli the velocity a, 
 
 overtake B, moving in the fame Jiieftion with the ve- 
 locity b, lefs than a. Moreover, let the velocities a and 
 i be fuch, that their differences a — l> h fomewhat lefs 
 than the fum of tlic velocities x and ,3, which the mu- 
 tual repulfions of the magnets would generate in them, 
 if the magnets were placed in contact, and allowed to 
 recede from each other till they get beyond their afting 
 diftance. 
 
 Tiiefe things being premifed, let the magnets be fet 
 in motion in the fame diredion with the above-men- 
 tioned velocities a and I/. The magnet A mull gain on 
 B, and at laft come fo near it, that the mutiia! repul- 
 fions begin to aft on both. It is plain, that the mo- 
 tion of A will be diinlnilhed, and that of B increafed, 
 by equal quantities, during every minute portion of the 
 time of their mutual aclion. It is ?lfo evident, that 
 the velocity of A may be fo much diminiflied, and that 
 of B fo much increafed, that they fliall be rendered 
 equal. Alio this will happen before the magnets touch 
 one another ; bccaufe the original difference of their 
 quantities of motion has been fuppofed lefs than the 
 motion which the repuHive forces are able to generate 
 or extinguifh, by acting on them through the whole 
 diflance which gives otcafion to their aftion. There- 
 fore the difference of the velocities is lefs than the fum 
 of the velocity », which the mutual repulfion can take 
 from A, and the velocity p, which it can give at the 
 fame time to B. The magnets will gradually approach, 
 and the mutual repull'ions, and confequent diminution 
 of A's, and augmentation of B's motion, will gradually 
 increafe, till the fum of ^ and ;? is juft equal to the dif- 
 ference of a and i; that is, till the bodies are moving 
 with one velocity. If the mutual repulfions were anni- 
 hilated at this inllatit, the bodies would move forward 
 with this common velocity. What this is wc determiii£ 
 with great facility, as we did in the former cafe : Be- 
 caufe the repulfions produce equal and oppofite chan- 
 ges of motion in the magnets, as much is taken from 
 AXa as is added to B X i ; and the fum of AXa, 
 and B X i, is equal to the fum of A X .■<: and B X x, or 
 
 Afl + B* 
 
 A + BXx=AXa + BX^, andx = --^ ^ jj . 
 
 92 ] IMP 
 
 Therefore the esmmnn velocity is had by JiviJitig the fum <if Impulfioo, 
 ths primitive quantities of motion by the fum of the quantities ~~v— J 
 
 of matter. r> • , r Co:„mon 
 
 But the rcpullive forces continue to act as in the for- velotiiy — 
 mer cafe. The motion of A is Hill more diniini(bed,/V .; + BA 
 and that of B augmented: Therefore the velocity of B --i + B 
 mull now exceed the velocity of A, and the magnets""' ''^^ 
 mull feparate. Reafoning in the fame way as in the ,/,„ ,„ .' 
 former cale, it is evident that the mutual action does rhe change 
 not ceafe till the magnets have feparated to their inac-is doubled 
 tive diftance from each other, and that the whole change''' '•*'■'*• 
 of motion in each is double of the change that it had 
 fuflained when they were in their grcatcll proximi- 
 ty, and moving with a common velocity. Thefe 
 coufideratioiis enable us to afcertain the final ftate of 
 
 . A a + A i 
 each. The common velocity is — ^ — , „ • 1 here- 
 
 A + B 
 
 fore the chanje made on the velocity of A, at the in- 
 
 n r n ... Aa + Bi 
 
 Itant or greatell proximity, IS a — '-— — , or := 
 
 and the final velocity of A is a — 
 
 In like manner, the change produced 
 
 2 B X a — 1^ 
 
 A + B 
 
 1 1- c -D • Aa+Bi , 
 on the velocity of B is r= — ^ r~T>~' — p, or = + 
 
 Ax a — b 
 
 A + B 
 
 the final velocity 
 
 of B is ^ + 
 
 A + B ' 
 
 2 A Xa -^Yq n,ay alfo obtain the final velocity 
 
 A+B ^ _ ' 
 
 of each, by taking its initial velocity from twice the 
 common velocity. 
 
 If, in this example of two magnets in motion, we 
 fuppofe them of equal weight, we fliall linC that tiiey 
 will finally proceed with exchanged velocities. For 
 
 2 B X a — A . 
 
 when A = B, it is plain that a — 
 
 a — iXa — b, = a — a + i, 
 2 A X a — b - 
 
 .^+B 
 = b : and b + 
 
 is=i+lXa — i, = i+a — b,=a. 
 
 This cafe is eafily fubjefted to experiment, and will be 
 found fully confirmed, u we take into account the re- 
 tardations occafioned by the refillance of the water to 
 the motions. ^i 
 
 Let us, in the next place, fuppofe the magnets to bexTaunefs 
 moving in oppofite diietlions with the velocities a andmoving in 
 b ; and (in order that the magnets may not llrike each"rP';'f"<= <i'- 
 other) let the fum of a and b be lefs than the fum of « *■ 
 and iL, which the repulfions of the magnets would pro- 
 duce by repelling them from contact to their inactive 
 diftance. 
 
 As foon as the magnets arrive at their aftiiig diftance, 
 their mutual and equal repulfions immediately begin to 
 diminilh both of their motions; and in any minute por- 
 tion of the period of their approach, equal quantities of 
 motion are taken from each. It is evident, that if the 
 primitive quantities of motion have been equal ; that 
 is, if A and B have been moving with velocities reci- 
 procally proportional to their quantities of matter, then, 
 when the motion of one of them has been annihilated 
 by their mutual repulfion, the motion of the other will 
 ^ be
 
 I M P 
 
 Iihpulfion. be Jeftroyed at ihe fame time, and both will be brought 
 ^""^ to reft. Were the repulfiuns aiiiiiliilatcd at this iiiilaiit, 
 they would remain at rcll. But becaufe thofe forces 
 continue their acliuns, the magnets will feparate again, 
 regaiiiiiig, at every dillance, tlic velocity wiu'ch they had, 
 when at that dillance, during their mutual approach ; 
 and when they liave readied their inaflive dillance, they 
 will have regaiiicd each its original momentum and ve- 
 locity, but in the oppofite dircttion. This needs no 
 farther comment ; but mull be kept in mind, becaufe 
 this cafe has a pvccifc counterpart in the collifion of fo- 
 lid bodies, meeting each other in oppoiite diredlions 
 whli equal momenfj. But if the momentum of one 
 exceed that of the other, thus, if A X <? be greater than 
 B X i, then, when the magnet B is brought to reft, A 
 has ftiU a momentum remaining equal to A a — B ^. 
 Having- therefore a certain velocity, while B has none, 
 it mull approach Hill nearer to B, and a ftill greater re- 
 pulfion will be exerted on B than if A had alfo been 
 ^ brought to reft, but ftill repelling B. Since B is now 
 
 acquiring motion in the diredlioM oppoiite to its former 
 motion, and A is ftill lohng motion, a time mull come 
 when the motion of A is fo much diminilhed, and that 
 of B fo much augmented, that they are moving with a 
 wk' common velocity in the diretlion of A's primitive nio- 
 
 o ". tion. The reafoning employed in the foregoing exam- 
 
 ples fliew us, that, in the prefent cafe alfo, this Hate of 
 common velocity is alfo the ftate of the greateft proxi- 
 mity, and that the magnets leparate again, till they at- 
 tain their diftance of inadlion, and that the total change 
 in each is double of what it vVas in their ftate of grcat- 
 31 eft proximity. 
 Common To find this common velocity, recoUedl, that when 
 
 ■velocity z: the momentum of B was extinguilhed, that of A was 
 i\a-~Bb i^jll — A a — B i. From what has been already fald 
 ^"t*'^ on the other cales, we know that when the common 
 chanB-^is velocity obtains, the whole momenta are ftill equal to 
 doubled by A a — B 6. Therefore the common velocity x muft be 
 the fubfe- _ Aa—B6 
 quent fepa- — 
 ration. 
 
 [ 793 3 
 
 I M P 
 
 The motions which obtain in the inftant of greateft rurulfiott. 
 
 proximity are precifciy frniilar to what «rr obferved \n ^""-^ 
 
 the collifion of unelaftic bodies. Their common ve. 
 
 A a -I- B * 
 
 locify after collifion is always r= 
 Ka—Bh 
 
 or = 
 
 A -J. B 
 
 according as the bodies were moving in 
 
 A + B 
 
 the fame or in oppofite diredlions. The final motions 
 of the magnets are alfo jdecifely fimilar to what are oh- 
 ftr-ved in tlie collifion of perfeilly elallic bodies. Wo 
 took the inftance of magnets, becaufe the objeft is fa- 
 miliar ; but we can fuhllitnte, in imagination, an ab- 
 ftradt repuliive force in place of imgnetilni, and we can 
 aftign it any intenfity, and any law and hmits of action 
 we pleafe. We can imagine it fo powerful, that al- 
 though its aftion be limited to a very fmall, and even 
 infenfible diftance, it ftiall always reduce the meeting 
 bodies to a common velocity before they coine into ac- 
 tual contadl ; and therefore without any real impulfion, 
 as impulfion is commonly conceived. 
 
 There are fome farther general obfervations that may 
 be made on thofe motions which are of importance. 
 " I. We fee that the changes of motion, and confe-Tu r^L 
 quently the aCtioas, are dependent on the relative mo- ^e- are prc- 
 tions only, whatever the abfolute motions may be: ForP'Ttional 
 changes are always as a — b when the bodies are mo- '"''"^ "■''*■ 
 ving in one diredlion, and as a -4- 3 when they are mo 
 
 viHg in oppoiite diredions 
 motion. 
 
 Now az±zb\% the relative 
 
 tive nio- 
 linii. 
 
 2. The change of velocity in each of the two bodies And^tci- 
 is inverfely as its quantity of matter, oris proportional |.ru.ally as 
 to the quantity of matter in the other body. Thet*'« <iui">''- 
 changes in A and B are ^ y-a^^b ^^^ 
 
 Ax 
 
 -ties ul nut- 
 ler. 
 
 A -f B A -f B 
 
 The changing forces being equal on both fides, pro. 
 ^duce equal changes in tl;e quantities of motion ; and 
 therefore produce changes of velocity that are iiiv.ifciy 
 as the quantities of matter. 
 
 3. During the whole procefs, the fum of the moraen- CoKiER- 
 ta, or quantities of motion, remains the fame, if the v.irio nio- 
 bodies are moving in one direiftion ; if they are moving "enio. 
 , and the final velocity will in oppofite dirtdlions, it is the difference of momenta """• 
 
 that remains the fame; for in every inftant of the pro- 
 The final motion of A will be ^^}^ ''9"^^ changes of momentum are made in oppofite 
 
 direftions. When the motions are in the fame direc- 
 
 A -I- B 
 The velocity loft by A muft therefore be a — 
 Aa — B* 
 
 B Xa -f ^ 
 
 A + BT"' ~ A - H B 
 
 , 2 B Xa -f- * 
 
 be a m — 
 
 A -f. B 
 
 in the fame diredlion as at firft, if a be greater than 
 
 1— T — , otherwife it will be in the oppofite direClion. 
 
 A -f. B ^^ 
 
 In like manner, the change of velocity in B is ^ -f- 
 
 . p » becaufe the former velocity b is dcftroyed, 
 End the new velocity is —^ — -— _ — in the oppofite di- 
 
 A -f. B 
 
 .1.1 
 
 The char- 
 ges of mo- 
 tion in the 
 magnets 
 
 reftion 
 
 of Bis = * — 
 
 This is = — ;; — ^"w— > ^^^ '•''^' ^"^^ velocity 
 
 _A_+B 
 
 3 A X a +_b 
 A -f. B 
 
 Thus we have fticwn, in the cafe of magnets afting 
 on each other by repuUive torcep, or actuated by for- 
 are fmiilir ces equivalent to repulfive forces, how changes of mo- 
 tion are produced, which have a great refemblance to 
 thofe which are feen in tlie collifion of folid boditiS. 
 Suppu. Vol. 1. Part II. 
 
 to thofe in 
 the colli- 
 fion of bo- 
 dies. 
 
 [ions, 
 tion, as much is taken from the one as is added to the 
 other J and therefore thifum remains unchanged. When 
 the motions are in oppofite diredions, equal quantities 
 are taken from both ; and therefore the difflrence re- 
 mains unchanged. This is called the conservatio 
 MOMENTOR.UM ; and it is ufually enunciated by faying, 
 that the quantity of motion, eftimated in one direction, 
 is not changed by the equal and oppofite adions of the 
 bodies. This is a particular cafe of a general law af- 
 firmed by Des Cartes, that the quantity of motion in 
 the univerfe remains always the fame when eftimated in 
 any one diredion. 
 
 4. When the whole procefs is completed, the fum CoNytii- 
 of the produds made by multiplying each body by thevAno vi- 
 fquare of its final velocity, is equal to the fum of the""-''" ^i. 
 produds made by multiplying each body into the fquarc ^aR""- 
 of its initial velocity. For when the procefs is com- 
 pleted, the two bodies are at the fame diftance from 
 each other as when the mutual adion began. There- 
 5 H fore,
 
 I M P 
 
 C 794 ] 
 
 I M P 
 
 Irnpulfion. fore, dcrlrc^ the jiroccfs, each body lias paflcd over an 
 ' yr~-— ' eq,j;J fpaee, and in every fimllar point it has been aft- 
 ed on' by an equal force (altliough this force be dlfTe- 
 rent. in different points of tliis fpace ). Therefore, in 
 every inftant, the fiinullaneoiis produfts of the quantity 
 of matter by the momentary variation of the iquare of 
 the velocity are equal on both fiJcs ; and thereiove the 
 products of the quantity of matter by the whole change 
 of the fquare of the velocity are alio equal on both fides. 
 See PynamiCS, SuJ>J>/. n° 95. and I 10. where mv — 
 
 •LL; and therefore m-wv — fs, and ct X V^ — 11% or of cxprtflin 
 
 are equal and oppofite ;" and the application is made 'mpulfion. 
 by means of the " 39th propofition of the firfl book of *'^~"v~— 
 Newton's Piimip'id." Our principle, which is the fame 
 with Sir Ifaac Newton's fecond law of motion, is really 
 an axiom of human thought. The propofition is the 
 confequence logically drawn from this axiom ; and the 
 law of magnet ifra is an obfcrved faft. We hope to 
 (hew, by- and bye, that this propofition, which is our 
 n'^gj.ofDvNAMics, is found to obtain m every inltance 
 that has been or can be given of the confervatio virium 
 nd that this confervatio is only another way 
 
 Thefe two 
 theorems 
 are not 
 principles 
 
 bi 
 
 n Xf' — V" r: //s- Now, fiote thefe changes are in 
 oppofite directions, as much is added to one produfl as 
 is taken from the other, and the fum of the produfts 
 of the quantities of matter by the fquares of the final 
 velocities, is equal to the fum of the produfts of the 
 fame quantities of matter by the fquares of the initial 
 velocities. 
 
 This is a particular cafe of the famous conservatio 
 viRiHM viVARUM, claimed as a mighty dii'covery by 
 the partisans of Leibnitz, and sfcribed to him ; but 
 ut general he has no claim whatever to tlie difcovery. It was 
 U&i. communicated to the Royal Society ot London In 1668 
 
 by Huyghens, as cue of the general laws of irnpulfion, 
 obtaining in what he calls hard bodies. Several of the 
 Leibnitzian fchool, indeed, extended it farther than 
 Huyghei;s had done ; fome of them indeed very lately. 
 The obfervation of this generd law was foon applied to 
 many excellent purpofes in the folution of -very intricate 
 problems ; becaufe it often faved the trouble of tracing 
 the intermediate fteps of a complicated procefs. Af- 
 fured that thefe produfts wtre invariable, the mathema- 
 tician found it an eafy matter to itale what conditions 
 of the quelUou infured this equably of produfts ; and 
 tiius. the problem was fc'lved. In this manner Daniel 
 Bernoulli gives moH elegant foliitions of fome, other- 
 wife alnioft intraftable, problems in Hydraulics. For 
 fuch reafons, as a mighty aid in mechanical inveftlga- 
 tiou, the difcovery of Kuyghens is extremely valuable. 
 Jts merit in this refpetl isptrfeftly fimilar (though per- 
 haps fomewhat greater) to Des Cartes's obfeivation of 
 the confervatio nicmentorum. It is alfo like the obfer- 
 vation or difcovery of Maupertuis, which he ealls the 
 law offmaUeJl anion (indeed it is the fame under a dif- 
 ferent afpeft), or La Grange's law of virtual velocities, 
 or D'Alembert's law of eqi:ilibrium of action ; — all of 
 thefe are general fafts, laws by which the changes of 
 motion are ohferved to proceed. But their authors 
 have vaunted them as principles, as caufes, from which 
 to conclude effefts ; whereas they are really induftions 
 from particular inftances. We muft alfo obfcrve, that 
 * this law of confervatio virium vivarum was not deduced 
 
 either by Huyghens or any of the Leibnitzian fchool, 
 by reafoning from more general principles. It was an 
 expifcation of famenefs In events, diverfified by other 
 clrcumRances. We do not recolleft any author who 
 has given what can be called a demonftration of it, de- 
 ducing it from principles or laws ftill more general. We 
 apprehend that the prefent cafe of Its truth has been 
 fo demonllrated by us. The principle Is, that " a mo- 
 ving force Is to be meafured by the change of motion 
 produced by it :" And the law to which this principle 
 it applied is, that " the mutual repulfions of magnets 
 
 g the propofition. Having done this, we 
 (liall not think ourlclves chargeable with vanity when we 
 fay, that we have given the firft demonftration of this 
 famous law. We cannot refufe ourfeives fome fatisfac- 
 tion at having done this; becaufe it has been fo highly 
 efteemed, chiefly for the fupport derived from It for the 
 Leibnitzian meafuremeiit of the force of moving bodies 
 by the fquare of the velocity which It communicates ; 
 whereas it Is the logical confequence of the force being 
 proportional to the fimple velocity. We have only taken 
 a weapon out of the hands of a plunderer, and reftored 
 It to its lawful owner, Sir Ifaac Newton. I\lott ita cer- 
 iandl cupldus, quam propter amorem: For we muft lay, 
 
 7u pater et rerum inventor, tu patria nobis 
 Suppeditas precepta, tuifque ex, inclute, chartis 
 Floriferis ut apes infaltibus omnia libant. 
 Omnia nos illdem depafclmur aurea dlila 
 Aurea, perpeluu femper dignlUfma vita. 
 
 We truft that our reader will not think that this mi- 
 nute difcuffion of the mutual aftions of magnets or 
 other repelling bodies, iu which we have engaged him, 
 has been thrown away, fince It has enabled us to appre- 
 hend clearly a cafe of two fuch general laws as the con- 
 feivatlo momentorum, and the confervatio virium vivarum. 
 
 5. In the moment of greatclt vicinity and common ^;^ ^];^^ 
 
 velocity, there is a certain determinate lofs of the ii/- loft in the 
 
 res viva, or products of the matter by the fquare colliCon of 
 
 of the velocity; and this lofs is proportional to the""^!^'*'' 
 r r 1 1 • fpL • .bodies, 
 
 fquare or the relative motion. 1 tie vtres viv<s, at 
 
 the commencement of the mutual aftion, are =1 A fl^ 
 
 -f- Bi^ (I.) In the moment of greateft proximity, 
 
 the quantity of matter A -t- B is moving with the 
 
 , . Aa + BA 
 
 common velocity — a"IZ~R — ' 
 
 therefore the vires viv£ 
 
 « ,, A 
 
 = A -f B X 
 
 B 
 
 A 
 
 Br- 
 
 A 4- B 
 A» g' -}- B' ^' -f. A B X z g 3 
 A -f"B 
 
 A -f B 
 
 (11.) 
 
 I. X A -f B = A^«' + B' i^ -}- AB X a^ -f f-. 
 II. X Ar+T3 = A'a"-f- B^^^-f ABX lab. 
 Difference 
 
 Lofs of vis viva = 
 
 AB 
 A -t-B 
 
 ABXa — A'. 
 
 X a — b^, a quantity 
 
 that Is proportional to a — i% the fquare of the rela- 
 tive velocity a — b. 
 
 Had the bodies been moving In oppofite direftions, 
 then (II.) XA -f B would have been A' a^ -f- B' b^ 
 — AB y.la b, and the difference from A a* -}- B i* 
 X A -f B would have been = AB X a -|- is propor- 
 tional to the fquare of the relative velocity a-^b. 
 
 Such
 
 I'hylical 
 taiiff of 
 
 this lulV. 
 
 IMP [ 795 ] IMP 
 
 Such is the faft ; and we fliall find it of importance with its motion when their mut^ial repulfion is th« Irrr""^''"- 
 in the great dibate about the force of moving bodies. 
 I,et us ip(]uire into the phylical or mechanical caufe of it. 
 In the moment of common velocity, the bodies are nearer 
 to each other than they are at tlie beginning and at the 
 
 end of tlieir mutual aftion. Therefore (ulien they are 
 moving in one dircClion) the body A, which follows, has 
 
 greatcll ; namely, at the moment of their gre.::eft vici- 
 nity. It has continued thf fami' durin:; the whole pro- 
 cefs : For we have already feen, that the film or diffe- 
 rence of the momenta, or A n z^- B b, remained always 
 
 the fame ; coiifequently 
 
 A a: 
 
 V,b 
 
 -, or X, the motion 
 
 been retarded through a fpace which is greater than the of the centre, remains always the fime. Thereft.re the 
 
 fpace along which the preceding body B has been accele- propolition is demon ftrated. It is, indeed, :: truth much 
 
 rated. But, becaufc the llmultaneous forces afling on ^^^y^. general than appears in the prefent inllance. If 
 
 the bodies along thele unequal fpaces are always equal, ,„y, „umler of bodies be nwcing with imy vclnrilifs, and in 
 
 the area which meafures the diminution of the fquare of ^tiy direBioiis, the motion of )he centre of pofition is not 
 
 A's velocity (Dynamics, n" 9;.) mull exceed the a- offdted by their mutual, equal, and opl"fite, atlions on each 
 
 rea which expreifes the augmentation of the fquare of other. 
 
 B's velocity, and there mull be a lofs gf vires yii^a. -,. During the whole motion, the motion of the ho-TKcmo- 
 
 Now, we learned above, that the mutual aftion is the dies relative to each other, is to the motion of one of'""^.'" >■<:- 
 
 fame when the relative velocity is the fame ; and there- them, relative to the centre of poUtion, as the fum of the '^"'"' '" 
 
 fore the approximation, which is tlie occafion of this bodies is to the other body : For when they wt 
 
 aftion, mull be the fame. And it is dcmonllrated in 
 
 Dynamics, n' 97. that the area, whofe abfciffa is the 
 
 fpace defcribed, and ordinates the lorces, exprcfles the 
 
 fquare of the generated or extlnguilhed velocity. This 
 
 is evidently the relative velocity of the bodies, becaufe 
 
 they arc brought to a common velocity in the inlhuit 
 
 of greatcll proximity ; that is, their relative velocity is 
 
 deftroyed. 
 
 6. During the whole procefs, the common centre of 
 pofition or gravity (a) is moving uniformly with the 
 
 . AartBi 
 velocity 
 
 A+B 
 
 39 
 The mo 
 tion of the 
 cominon 
 centre of 
 gravity is 
 
 not chan- „ , . , ^ , - c . , 
 
 Bcd by the pofition is the average or the motion or every particle 
 
 mutual ac- of matter in both bodies. A rt is the fum of the mo- 
 tion, tions of every particle of matter in A, and B 3 is the 
 fum of the motions of every particle in B, before the 
 mutual adlions began. Therefore A a -j- B i is the 
 whole motions when the bodies are moving in the fame 
 direction with their different velocities. The number 
 of particles is A -|- B : Therefore, if the whole mo- 
 tions be equally divided among all the particles, the ve- 
 
 A <: + B i ^ . . 
 velocity of each mull be — 1{ — . — n~ • This is the ave- 
 
 40 
 
 ■ the centre, 
 
 ■ aic rccipro- 
 
 viiig with a common velocity, this velocity was the cally as the 
 fame with that of the centre ; and they are then at rcft,'>o''i<='- 
 relative to each other, and relative to the centre. And 
 becaufe their dillances from the centre are inverfely as 
 
 the bodies, their changes of diilance, that is, their mo- 
 tions relative to the centre, are in the fame proportion ; 
 and the fum of their motions relative to the centre is 
 the fame with their motions relative to coch other. 
 Therefore A-f- B:A = a — b \ motion of B relative to 
 the centre. Indeed we faw, that in their mutual adlion. 
 
 Fcjr the motion of the centre of the change of B's motion was r= 
 
 change of A's motion was = 
 
 A-Aa — b 
 
 and the 
 
 A + B ^, 
 
 Hence we learn, that while the centre moves unl-TIit; Imdies 
 formly, the bodies approach it, and then recede from it, 1^1 ^"^'e 
 with velocities reciprocally proportional to their quanti-T" ' 'f 
 ties of matter. This will be found a very ufetul corol-dve vclnci- 
 lary. We may alfo fee that their final velocity of mu-ty which 
 tual reccfs is equal to that of their fi.ll approach, or, 'heyap- 
 their relative motions are the fame in quantity after thc'"^''* ' 
 atlioii is over as before it began, but in oppotite direc- 
 tions. 
 
 All jhefe general fads, which are dillinftly appre- 
 ciable, and very perceivable, in this example of mag. 
 nets, or elcdlrified bodies, are equally appreciable in all 
 cafes of mutual repulfions, however ftrong thefe may 
 be ; and although the fpace through which they are e-c- 
 crted fhould be fo fmall as to elude obfervation, and 
 though the whole procefs fhould be completed in an iii- 
 ienfible moment ot time. 
 
 It fcarcely needs any comment to make it clear that An mtcr- 
 the very fame changes of motion mud take place, if apofeil 
 folid body A (hould come up to another folid body B, '■'"'"^' ''■■" 
 at reft, or moving more flowly in the fame '^i'''ccl''>"i efr-<ft with 
 
 A -t- B 
 
 rage motion, or the motion of the centre of pofition, 
 deduced from the notion we wifli to imprefs of the cha- 
 rafter of this centre, as the index of the pofition and 
 motion of any alTemblage of matter. This velocity 
 may be deduced more eafily from its geometrical pro- 
 perty. It is a point fo lituated between A and B, that 
 its diilance from each is reciprocally proportional to the 
 quantities of matter in A and B, as is well known of 
 the centre of gravity. It is equally plain, that when 
 tlie bodies are moving in oppofite directions, the ave- 
 
 Aa — '&b 
 rage velocity .v mud be = — ^— , „ ■ . Thus we fee, 
 
 that the motion of the centre of pofition, before the or moving in the oppofite direction ; provided that there the mutual 
 magnets have begun to aft on each other, is the fame be a fpring iiiterpofed between tliem, which may hinder lepulfions, 
 
 5 H 2 A 
 
 (a) Seethe article Position in this Supplement ; where it will be demonftrated, that the centre of gravity (de- 
 termined in the ufual manner) is the point by whofe fituation and motion we eftimate with the greateil propriety 
 the fituation and motion of the afTemblage, of which it is the centre : it is therefore called the centre of posi- 
 tion. The reader is only dclired at prefent to recoUeft, that the centre of gravity, or pofition of two bodies, is 
 fituated in the line joining their centres; and that its diilance from each is inverfely as their quantitie^ of matter; 
 and that the diilance and motion of the centre is the medium or averarje of all the diftancts or motions.
 
 IMP [ 796 1 IMP 
 
 Impuirion. A from ftriking B; for, as foon ns A touches the tioii of that motion; it may be the obftacle of a Impulfioxr, 
 
 ' fpriiig, it begins to prefs it againtl B, and, therefore, quiefccnt body — it will give it motion ; or, it may be '~~-v' ^ 
 
 to comprefs the fpring. It cannot carry the fpring be- the ahllruftlon by a body moving more flowly away tliaii 
 
 fore it, without the fpring's pufhiiig B before it. Pref- the fpring is prcfTcd forward — it will accelerate that 
 
 fure on B is required for this purpoi'e. This is fupplicd nK)tion. Thus, in all thefe cafes, we cannot help dil- 
 
 by that natural power which we call elafticity, which is tlngulfhlng the immediate caufe of thefe changes of 
 
 inherent in the fpring, whether it be in motion or at reft 
 It is not in aaloii, but in rapacity, fticulty, capahillly, power, 
 or by whatever name we may choofe to exprefs the pof- 
 ftffion. The occafion required for its exertion is compref- 
 fion. This is furniflied by the motion of A ; for A can- 
 not advance without comprefiing it. This inherent force 
 
 motion from the fuppofed force of a moving body. 
 Nay, the procefs of motion is fimilar, even when we 
 fuppofe that the fpring is not a thing external to the 
 body, although attached to it ; but that the whole bo- 
 dy, or both bodies, are fpringy, elaftic, and therefore 
 comprefTible. As foon as the bodies come into fen- 44 
 of the fpring is known to afl with perfect equality at both fible contadl, compreflion mujl begin ; for we may fup- '"*^™^' 
 ends, in oppofite direiSions. It exerts equal and oppo- pofe the bodies to be two balls, which will therefore chanue 
 fite preiTures on A and on B ; it diminillies the motion couch only in one point. The mutual prefiure, which through 
 of A, and equally augments the motion of B (if both is neceffary in order to produce the retardation of A,'''^f"''" 
 are moving tliat way). A is retarded, and B is accele- and the acceleration of B, is exerted only on the fore- ^'u l"! 
 rated ; A is dill moving fader than B ; and therefore moft particle of A, and the hindmoll particle B ; but 
 the compreffion and the confequent reaftion of the no atom of matter can be put in motion, or have its 
 fpring increafes, and ftillmore retards A and accelerates motion any way changed, unlefs it be adled on by aji 
 B. After fome time, both bodies, with the fpring com- adequate force. The force urging any individual par- 
 prefTed between them, are moving with equal velocities; tide, muft be precifely competent to the produftion of 
 the fpring, however, is ftrongly reaftiag on both, and the very change of motion which obtains in that par- 
 muft now caufe them to feparate ; dill retarding A, tide. Except the two particles which come into con- 
 ami accelerating B —They mud feparate more and more, tadt in the collifion, all the other particles are imnie- 
 till the fpring regain its quiefcent form, and its elaftic diately aftuated by the forces which council them with 
 reaflion ceafe entirely. During its reftitntion, its pref- each other; and the force afting on anyone is general- 
 Aires are the fame as during its compreffion, therefore, ly compounded of m.any forces which connect that par- 
 the whole change produced on each of the bodies muft tide with thofe adjoining. Therefore, when A over- 
 be double of what it was when the fpring was in its ftate takes B, the foremoft particle of A is immediately re- 
 of greateft compreflion, and the bodies were moving tarded — the particles behind it would move fonvard, if 
 with a common velocity. In diort, the whole procefs their mutual connedlion were dilTolved in that inftant ; 
 in this example mufli be precifely finiilar to that of the but, this remaining, they only approach nearer to the 
 magnets in every circumdance relating to the changes foremoft flriking particles, and thus make a compref- 
 of motion in A and B. The common velocity muft be fion, which gives occafion for the inherent elafticity to 
 h aziz'R b . exert itfelf, and, by its reaftion, retard the following 
 
 = ~X+ B"' '^''^ ''"^^ velocity of A muft be = a partides. Thus each Itratum (lo to conceive it), con- 
 tinuing in motion, makes a compreflion, which occa- 
 fions the elafticity to reaft, and, by reafting, to retard 
 the ftratiini immediately behind it. This happens in 
 fucceflion : the compreillon and eladic reaction begin in 
 the anterior dratuni, and take place in fucceflion back- 
 
 2 B a =±3^ >i. fTj ni ii^A azizl 
 
 ., anothat ot B muft be =: bA- 
 
 A-fB A-f B 
 
 The motion of the common centre muft be unaJTefted 
 by the aftion of the fpring, and the motion of each bo- 
 dy, relative to the centre, muft be reciprocally as its ward, and the whole body gets into a ftate of compref 
 ., quantity of matter, &c. &c. fion. Things happen in the fame manner in B, but in 
 The chan- We apprehend that this procefs can fcarcely be call- the contrary dire<:tion, the foremoft drata being" the 
 gesofmo- ed impulfion ; A has not ftruck B. The changes of laft which are comprefled. All this is done in an in- 
 tion are motion can fcarcely be afcribed to forces inherent in A ftant (as we commonly, but inaccurately fpeak), that 
 by the in- °^ ^' ■" confequence of their being in motion. Any is, in a very fmall and infenfible moment of time ; but 
 berent fur- peiftin, not already warped by a theory, will (we in this moment there is the fame gradual compreflion, 
 ces which think) afcribe them to a force inherent in the fpring; increafe of mutual action, greateft compreflion, com- 
 conneLl 'ne;p],g^j.nj j„ ^^ whetlier at reft or in motion, and only mon velocity, fubfequent reftitution, and final fepara- 
 ' requiring a continued compreflion as the proper oppor- tion, as in the cafe of bodies with a flender fpring in- 
 tunity for its continued exertion. This fpring may be terpofed, or even in the cafe of the mutually repelling 
 fuppofed to make a part of B, or of A, or of both ; magnets. In all the cafes, the changes of motion are 
 and then, indeed, the force may be faid to be inherent produced by the elafticity or the repullion, and not by 
 in either, or in both. But it is not the peculiar force the transfufion of the force of motion. The changing 
 inherent in motion, or in moving bodies only — it is the force is indeed inherent in the bodies, but not becaufe 
 force of elajlicily, inherent in part of the body, but re- they are in motion ; the ufe of the motion is to give 
 jquiring a continued fom/>r^on for the produAion of a occafion, by continued compreflion, for the continued 
 continued reprejfion. The effeft of this reavElion is mo- operation of the inherent elafticity. The whole pro- 
 dified by the very occafion of the compreflion. This cefs may be very diftinftly viewed, by making ufe of 
 may be the elafticity of another fpring. In this cafe it bodies of fmall firmnefs, fuch as foot-balls, or blown 
 will only comprefs that fpring. — It may be the advance bladders. If blown bladders are ufed, each loaded with 
 of a body in motion j the rcaftion produces n retarda- fand, or fomething that will require more force, and" 
 
 confequently
 
 I M P 
 
 [ 797 ] 
 
 IMP 
 
 ent fituations, and ftill colicrc, it I's plain, tliat wlicn a Implilfion. 
 body has been dimpled by comjmlDoii, the particles' ^ ■' 
 have nothing to bring them back to tluir fn (l (itiiation 
 wlicn the comprcfling fincc is removed : the \itmo(l 
 elailicity to be expcfled, is that wliicii will ncit extend 
 to one (hift of iituation ; theitfore, the rcftitutioii is 
 altogether infeiifiblc. This is the cafe wiih all foft bo- 
 dies, fuch as clay — the fame quality is manifcUcd in all 
 dudlile bodies, fuch as lead, foft iron and ftctl, foft 
 copper, foft gold. 
 
 4ft 
 
 hnpuirion. confequently more compreffion to impel It forward ; we 
 ' ■«■""' {Jjall obfcrve the conipreinoii of both to he very confider- 
 
 able, and that a very fenliblc time ehipfts during the 
 
 procels of collifion. This may even be obferved very 
 
 dillinftly in a foot-ball, which is always feen to reft a 
 
 little on the toe Ifefore it flies off by tiie ilroke. When 
 
 one foot-ball is ftrongly driven againtl another, they 
 
 plainly adhere together for fome time, and tlien the 
 
 ilricken ball flies off. 
 
 If we return to the example of the two balls with 
 
 the fpring interiiofed, we may make fome farther ufcful Now let one of thefe bodies (bike another. The com-riTca of 
 
 obfervations. When the fpring is in its ftate of gveateft preffion, or the Aiding of the particles over each olher,iiiii colli. 
 
 compreflion, and the balls are moving with a common requires force, or mutual prefPure This being aceom-''"''' 
 
 velocity, we can fiippofe that the fpring is arretted in panied by a rcaaion perfedly equal, muft operate, du- 
 
 that fituation by a catch. It is evident that the two ring the compreflion, precifely as the equal repulfive 
 
 bodies will now proceed in contaft with this velocity, forces did. It will take as much momentum from A as 
 ... , , , A a=!=B l> 't gives to B ; fo that A a t+= B i will remain invari- 
 
 vhich we have fliewn to be = "^ + B' ' ' ^^^Y ''"-' '""■"e. 3"'^ a common velocity will at laft ob- 
 
 Now, in the conftitution of fuch maffes of tanirible t.-,„ " — " * o^i rr 
 
 .. u »u .. •• rr u- o.- . "> = — A — I — u — • 1 lie compreliion can proceed no 
 
 matter as we have the opportunity or iubjectmg to our I\ ■^^^ H ' i- >. -.u nv. 
 
 experiments, we find a (late of aggregation which very farther, and the two bodies muft now proceed in con- 
 much refembles this. Some bodies are almoft perfettly taft with this velocity. 
 
 elaftic, that is, when their fliape is changed by external And thus we fee, that in the cafe of comprefribli?, 
 
 prefTure ; and that preffure is removed, they recover but unelaftic bodies, the changes of motion are pro^ 
 
 their former (hape completely, and they recover it w ith duccd by the cohefive forces inherent in the bodies ; 
 
 great promptitude. Glafs, ivoi7, hard fteel, are of this but not inherent in them becaufe they are in motion.' 
 
 kind. But mod bodies either do not recover it com- We fee clearly in this way, how the pendulum ufed by 
 
 pletely, or they recover it very flowly— fome hardly Robins and his followers gave a true meafure of the 
 
 45 
 Nature of 
 imperfedt 
 elafticity. 
 
 recover it at all. A rod of iron will, when confiderably 
 bent, not nearly recover its (liape ; a rod of lead flill 
 lefs ; and a rod ot fott clay will hardly recover Tt in any 
 degree. Thefe, however, are but gradations of one and 
 the fame quality : if the quiefcent form of a body is 
 very little diilinbed, it will recover it again. Thus, a 
 common foft iron wire of N° 6. and 1 1 inches long, 
 if twifted once round, will return completely to its ori- 
 ginal form, and will allow this to be repeated for ever ; 
 
 velocity of the ball. All the while that it was pene- 
 trating into the pendulum, overcoming the cohefion as 
 it went in, this cohefion was acting equally in i)oth direc- 
 tions. While the fibre was breaking, it was pulling 
 botii ways ; it was holding back the ball which was 
 breaking it, and it was pulling forward the parts to 
 which it ftill adiiered; and when it broke at \A\, it had 
 produced equal effeds on the ball and on the pendo- 
 oppofite direftions. By fuch a procefs, the 
 
 urn in 
 but if it be twilled i^^ turns, it will untwift only i: and pendnlum was gradually accelerated, and acquired its. 
 in this new form, it will twiil and uutuill one turn as utmolt velocity u lien the ball had ceafed to penetrate:. 
 
 often as we pleafe. Even a rod of foft clay. Tot'' of an 
 inch in diameter, and 7 feet long, will bear one twill as 
 often as we pleafe ; but if twided 4 times, will untwill it- 
 felf only one turn, and will do this as often as we choofe. 
 In fhort, it appears that the particles of bodies, ufual- 
 ly called unelaltic, will admit a fmall change of diftance 
 or fituation, and will recover it again, exhibiting perfeC'l 
 elafticity, in oppofition to very fmall forces ; but if 
 they are forced too far from this fituation, they have 
 no tendency to return to it completely, but find inter- 
 mediate fituations, in which they have the very fame 
 connexions with the furrounding p.u'ticles ; and in this 
 new fituation, they can again exhibit the lame pcrfett 
 flafticity, in oppolition to very fmall forces. Mr Cou- 
 lomb conceives luch bodies to confiil of clailic particles : 
 they manifell perfedl elafticity, fo long as the forces 
 employed to change their (hape do not remove the 
 particles from their prefent coutafts ; but if they are 
 removed from thefe, they Hide on to other fituations, 
 where they again exhibit the fame appearances. To 
 underfland this fully, the reader may confult the article 
 BoscoviCH of this Supplement — The faft is fufficient 
 for our prefent purpofe. Now, In this variable confti- 
 tution, where the particles may take a thoufand difler- 
 
 Tlierefore, this 
 
 A 
 
 s velocity muft be = -2 
 
 ' A -f peiid'". 
 
 What fhould we now expcft to happen in the col-f 
 lilion^ of bodies ; .Such bodies as exhibit perfedt e- 
 lafticity, when examined by bending, or other fit 
 trials, lliould have their motions changed precifely like 
 tlic magnets, or Iiodics which repel or avoid each 
 other at fcniible diftances. Bodies which exhibit no 
 elafticity whatever, fliould continue in contadt after 
 colulion. I'he common velocity in thefe fiiould he 
 Aa==B/^ 
 
 ^\ -iTli""' ■^'"■" P'^''''^'^'y el^l^'c bodies (lioul 1 fiiftain 
 changes of motion which are precifely double of the 
 changes lidbiiied by unelaftic bodies, and fuould fepa- 
 rate after collifion with a relative velocity of re^-efs or 
 leparation, precifely equal to their relative velocity of 
 mutual approach. And bodies polfefling imperfeit cla- 
 iVicity, Ihoiild fuftain changes of motion which differ 
 from the changes on unelaftic bodies, precifely in pro- 
 portion to the degree of elafticity which they are ino-wn 
 to poffefs. And, laftly. If the changes of motion which . 
 obtain in the collifion of bodies, are precifely thofe 
 which would refult front the operation of thofc Inherent 
 
 forcco
 
 Imriilfio 
 
 I M P 
 
 forces of tlnfticity and cohtfioii, no other forcu 
 
 WHAIEVHR CONCURS IN THtlR. PRODUCTION: For 
 
 we know that thole forces iln opernte the coUifion ; 
 we fee the comprefiion and rtllitutlon wliich are their 
 iffeftive caufes, and their inimcch'ate efTcds, If ai,y 
 other force were fiiperuddec), vie ihoukl lee its cfTcCts 
 alio, and the motions would bt diifereiit fro[:i what they 
 
 Now the fiCt is, that lue have never /ten a body ihul 
 is not, in fame degree, compreffihle. It has not pleated 
 the Almighty Creator to nialte any fuch here below. 
 Affjredly He has not found Inch to be of ufe for the 
 purpofes He had in view in this onr fubhiniry world 
 
 [ 79S ] IMP 
 
 tions, //; ail eiifes that n'e can olfirve and mtafure Tt'itb Iinpu'Gon. 
 ocniracy. All thele things can be afcertaintd with ~~~» 
 great precilion Vjy means ol the collifion of pcndnlous 
 bodies in the way pointed out by Sir Chriilopher Wren 
 (a method attributed by the French to their country- 
 man Mariotte, but really invented by Wren, and exhi- 
 bited to the Royal Society of London the week after 
 he communicated his theory of impulsion). 4? 
 
 We mull alio infer from thefe fafts, that the a£tionsF'"'^''fi''e 
 of bodies on each other are mutual, equal, and oppofite. ^^° "' 
 
 This is really an inference from the phenomena, and oi equjl I'c^ 
 not an original or fivll principle of reafoning. The ti' n auJre- 
 contrary is conceivable, and therefore not abUird. In aiit'on' 
 
 AVe know of no body that is perfeftly unchangeable m the fame way that we can conceive a magnet repelling 
 
 its fliape and dimenfions. It is therefore no lofs what- iron, without imagining that t'he iron repel:; the magnet, 
 
 ever to us, although we Ihoidd not be able to fay a pri- vVe may conceive a golden ball capable of impelling a 
 
 ori what their motions will.be in collifion. We cannot leaden ball before it, without conceiving that the leaden 
 
 even fairly guefs them, by reafoning from what we ob- ball will impel the golden ball. We do not tind this 
 
 ferve in other bodies : For it is jult as likely liiat their eafy indeed; becaufe the contrary is fo familiar, that the 
 
 motions may refemble thofe of perfeflly elallic bo- one idea initantly brings the other along with it. We 
 
 dies as thofe of unelallic bodies i for we find that bodies apprehend It to be impoiTible to demor.llrate, that a 
 
 of the moit extreme hardncfs are generally highly elaltic. leaden ball will not ftop as foon as it hits the golden 
 
 * Diamond, cryllal, agate, quartz, and fuch like, are the ball, or -vice -ucrfa. But all om- experience (hews ua, 
 
 tnolt: elaftic bodies we know. Philofophers, however, that the preffures exerted in contaft are mutual, equal, 
 
 rather think that the motions of perfeftly hard bodies and oppofite. The fame thing is obferved in the forces 
 
 will refemble thofe of unelallic bodies ; becaufe elallici- which conneft the parts of bodies. A quantity of fand 
 
 ty fuppofes comprefrion. We do not pretend to fay or water balanced in a fcale will remain in equilibrlo in 
 
 with confidence, what would be the motion of a fingle whatever way it is flirred about ; its parts always exert 
 
 atom of matter (which canHot admit of comprefiion) the fame prelfure on the feale : fo does a body fufpend- 
 
 which is hit by another in motion. We fee all the par- gd by a llring or relling on the fcale, by whatever 
 
 tides of terrellrial matter connedled with each other by points it is fupported. This could not be if the particles 
 
 certain modifications of the general force of cbhefion, did not exert mutual and equal forces ; nor could the 
 
 fo as to produce various forms of aggregation ; fuch as phenomena called impulfions be what they are, if the 
 
 aerial fluidity, liquid fluidity, rigidity, foftnels, dufti- prcffures occafioned between the particles by the com- 
 
 lity, firmnefs or hardnefs ; all of which are combined prcflions and dilatations were not mutual and equal. 
 
 with more or lefs elafticity. Thele tangible forms re- This law of aftion and reaftion mull be admitted as 
 
 full from certain pofitive properties of the material univerfal, though contingent, like gravity. Doubtlcfs 
 
 atoms of which the particles are compofed ; and, in all ft refults from the properties which it has pleafcd the 
 
 the cafes which come under our obfervation, thefe pro- great Artiil to give to the matter of which He has 
 
 perties produce prefTurcs of one kind or another ; all of formed this world. There is one way iu which we can 
 
 which are moving forces. Tlx'y are inherent in the conceive, mod dillinftly, how this may be a univerfal 
 
 particles and atoms : therefore when fuch atoms are in property of matter. If we grant the reality of ar.rac- 
 
 motion, thefe forces are in a condition which affords tions and repulfions e dijlantl, and fuppofe that every 
 
 occafion for a continuation of this preflure that is com- primary atom of matter is precifely fimilar to every 
 
 petent to the production of motion In another particle, other atom in all its properties, and that this affem- 
 
 Bat what would be the event of the meetin_g of atoms bUige of properties conllilutes it a material atom; it fol- 
 
 divefted of fuch forces, we profefs not to know, or even lows, that every atom exerts the fame attradions and 
 
 47 to conceive. repulfions, or .has the fame uniting and evafive tendencies, 
 
 The obfer- The fail alfo is, that all the changes of motion, com- and then the law of attlon and equal readion follows of 
 
 ved (fFt-a^ monly called impulfions, r^chjch have been obferved, are cotirfe. This is furely the very notion that any perfon 
 
 of collifu^ T)recifely fuch as have been defcribed. Unelallic bodies Jg difpofed to entertain of the matter. And if mecha- 
 are pcrtect- 1 J ^ j, , ,. » 
 
 ly conform- ,. o • i .1 1 \ , Jlf^ '^ . Vr n*al t'^''' 
 
 able to the proceed :n contad with the velocity ^ _^ _-jj- rer- 
 
 t7o°'"'now f«;flly elaftic bodies feparate after collifion, and each 
 
 e'lUbl'ilied. fuilains double of the change that is fuilained by an un- 
 elaftic body. Bodies of imjierfeft elallicity difler troin 
 the two fimple cafes, precifely in the proportion of the 
 elafticity difcoverable by other trials. The mutual ac- 
 tions are obferved to be in the proportion of their rela- 
 tive motions, whatever the real motions may be. For _ 
 
 not onlv-are the changes of progreffive motion exadlly of the rotation of the earth round its axis, and its rcvo- 
 in this proportion, but the compreflions and changes of lution round the fun, it is plain that all our experiments 
 figure, which we confider as the immediate occafions of and obfervations are on relative motions only. Now, 
 thefe adioss, ai'c alfo obferved to be in the fame proper- we not only find that the aftions of two. bodies fubjec- 
 
 t«<l 
 
 rce and mobility are the qualities which dillin- 
 guifli what is material from mind or other immaterial 
 fubllances, the law of equal and contrary reaction feems 
 neaily allied to the-clafs of firft principles. 
 
 Of all the phenomena that indicate this perfeft equa- 
 lity of attion and rea£lion, the moft fufceptible of ac- 
 curate examination is the famenefs or equality of adfion 
 when the relative motions are equal. Now there is no 
 phenomenon more certain than this. In confequencc
 
 IMP [7 
 
 • Impulfion. ted to experiment are equal when tJie relative motions 
 ' ' V are equal, but we find that all our meafures of aftioii 
 on a fingle body are proportional to the apparent mo- 
 tioiTs which they produce. It reqviires prtcifely the 
 i'ame force to impel a ball eailward, weftward, fouth, 
 ■i>r north, at 12, or ^, or 6, or 9 o'clock : yet the veal 
 riiotions are immenfely difterent in all thcfe cafes, and 
 it is only the relative niotioiis that have the proportions 
 which we obferve. Another very important point de- 
 duclble from our experiments is, that the hmt: prrffure 
 produces the fame change of motion, whatever may be 
 the velocity. We know this by obferving, that when 
 ibe mutual dimpling or compreffion is- the fame, the 
 ohange of motion is the fame, whatever be the hour of 
 the day. This could not be if it required a greater 
 preffure to change the velocity loocoo into looooi, 
 than to change the velocity i irtto the velocity 2. Yet 
 this is one of Leibnitz's great metaphyseal arguments 
 for proving that the force accumulated, and now inhe- 
 rent, in a moving body, is proportional to the fquare of 
 its velocity. We beg that this may be kept in remem- 
 brance. 
 
 It muft be granted, that what we have already faid 
 on the fubjeft of impulfion may be called an explana- 
 tion ; lor it deduces the phenomena from general and 
 unquciUonable principles, and from acknowledged laws 
 of Nature. The only principle ufed is, that a moving 
 force is indicated, characterifed, and meafured, by the 
 motion which it produces. It is an acknowledged law 
 of Nature, that prelTures are moving forces ; aUo, that 
 moving forces appear in cafes where we obferve neither 
 preflures nor impuhions, and which we call repulfions 
 or evafive tendencies ; that thefe are mutual and equal : 
 and we have (liewn, how a certain fet of changes of 
 motion refult from them, and have ftated dilUnftly the 
 whole procefs : v/e lliewed, that thefe phenomena are 
 Jimllar to thofe of common impulfion ; and we then 
 Ihewed in what manner the motion of a body j^ives oc- 
 caftnn to the exertion of various movinjf forces, called 
 ettii'luity, cohtfwn, &c. and that this excicion muft pro- 
 duce motions fimilar to thole produced by repulfions 
 e dijhmti ; and, laftly, we inferred, from the perfect 
 iameTiels of thofe reiults with the aclnal phenomena of 
 impulfion, that thofe corpufcular forces are the i:r.me- 
 diate and onlj caufes of the changes called impuliions, 
 and commonly afcribed to a peculiar force inherent in a 
 ^^ moving body. 
 Why dies From a colleflive view of the whole, we think it clear, 
 the |>hiiolo- fjjjf ^Ijj. opinion that impulfion is the fole caufe of mo- 
 toexplam ''°" '* unwarranted. We fee that the phenomena of 
 gravitation, inipulfion are brought about by the immediate operation 
 &c by im- of prefiure ; and we fee numberlefs inftances of preflure, 
 pulfion . Jp which -we cannot find the fmalleil trace of impulfion. 
 It is therefore a moil violent and imwarranted opinion, 
 which afcribes to repeated unperceivtd impulfions all 
 thofe folicitations to motion by which, or in eonfe- 
 quence of which, the motions of bodies are affefted by 
 diftant bodies, or bear an evident relation to the fitua- 
 tion and ditlance of other bodies ; as in the examples 
 of planetary defleftion, teiTeftrial gravitation, magnetical 
 and cleftrical deflexions, and the like. There is nothing 
 in the phenomenon of the prclTure of gravity that feenis 
 to make impulfion more necefiary or more probable than 
 in the prefiure of elafticity, whether that of a fpring or 
 of au expanfiv« fluid. Tiie adjnifiion of an unpciceived 
 
 99 ] IMP 
 
 fluid to cfFcA thofe impulfions is quite unwarranted, ImpiiIGon. 
 
 and the explanation is therefore unpiiilofophical, even "— v~— ' 
 
 although we fhould perceive intnilively that an atom in 
 
 motion will put another into motion by hitting it. Wc 
 
 apprehend that this cannot be nfliimcl with any clear 
 
 perception of its truth. ^o 
 
 On the whole, therefore, we muft afcribe that con-Impuiron 
 
 tented acquielcer,ce in the explanations of gravitation," '^P)'"''" 
 J ., ' .^ r. ■ 1 ,,- , (■ • to be bctitr 
 
 and other attractions and repul ions, by means 01 nn- , „„„ , 
 
 pulle (it the acquielcence be not prctendtd J, to the ire- and nioie 
 quency and familiarity of impullion, and perhaps to faniilinr. 
 the perfonal lliare and interell we have in this mode of 
 producing motion. Wc know tliat it is always objedl- 
 ed that nothing is explained, when wc fay tiiat A re- 
 pels B, or that B avoids A ; but we muft fay in return, 
 that nothing is explained, when we fay that A impels 
 B by hitting it, or that B flies away from the ftroke. 
 Why ihould it not be allowed to ufc the term repelh'nj; 
 power, when it is allowed to ufe the terra impelling; 
 power, the force of impulfe, inertia ? All tliL-fe terms 
 only cxprefs phenomena. Does the word body exprefs 
 any more ? ji 
 
 The maxim, that a body cannot aft -where it is not. It N not 
 any more than luhen it is not, is a quaint and lively ^•''•l'"i''^"* 
 preiTion, and therefore has confiderable cffeft : It may 
 be granted ; for we apprehend that we underftand fo 
 little about when and luhere, that we cannot denioiiftratc 
 the affirmative or negative in either cafe, and that they 
 are on a par with refpeit to our knowledge of them. 
 We can have no doubt, however, of the faft, that our 
 mind can be affedled by an external objeft that is mere- 
 ly recollected. And we apprehend, that we know no- 
 thing of the difference between body and mind but what 
 we have learned by experience. Body, lor any thing 
 tiiat we afTuredly know to the contrary, may alTetl, or 
 be affcfted b\, a diftant body, as well as mind may be. 
 It is therefore wortli while to pay iome farther atten- 
 tion to the phenomena, in order to fee whether this ex- 
 perience is fo unlverfal and uncxpefted as is believed. 
 As Mr Cotes, and many of Newton's difcipks, are ac- 
 culed of explaining many piienomena by altraftiou and 
 rcpulfion wiiich their opponents aflirm to be cales of 
 impulfion ; it is not iiiipoliii)le but that ordinary obfer- 
 ver*, who have no preconceived theories, may imagine 
 impulfions to obtain in ealcs where a more accurate in- 
 fpeCtion would convince them that no impullion has 
 happened. ^j 
 
 When we kick away a foot-ball, we confider it as a Ei-.cji,iiy in. 
 fort of folid contiiuious body; yet we know that it '""["^ f-JP'- 
 muft be filled with compreffed air. It may noi be '''i- ]| ,',,'J|inn 
 poffible to have it of its round fliape witiiout being fo inliances of 
 filled: but we know that, in this condition, it wonlda !oot-ball. 
 not fly away from our foot by the ftroke ; we fiiould 
 only force in the fide which ue kick, and the flaccid 
 (kin would lie at our feet. But when it is filled with 
 ftrongly comprtifed air, we can form to ourfeives 
 a pretty diftintt notion how it is made to move off. 
 Our foot prefi'cs on a part of the ikin : this com- 
 prciTes the air againft the anteiior part of the b.ag, and 
 forces it away. If we refleet more ferionfly on the 
 procefs, we can Hill conceive it clearly enough, by 
 thinking on a row of aereal particles, reaching from the 
 part ftruck by the foot to the anterior part, t ich to.'v.h- 
 ing the other, and therefore forcing tlie anterior part 
 forward. The air is conceived to confilt of a number 
 
 of
 
 Innuir::) 
 
 IMP [8 
 
 of l:t'ile fphcrales in contaft, cr.ch of » hich is com- 
 prefTible ; and we tliink the cpci-alion illuilrated by 
 fiippofuiq tach to be like a little vcficlc or bladder. 
 1 his wc believe to be the ufual way of conceiving the 
 conrtitu!it)ii of cxpanfive fluids : But this will not agree 
 at all uiili the known properties of air ; for it can be 
 Hrictly dvinonftrated, that if fiicli a collection of elalb'c 
 vetiele.s be coniprefled into the half of their ordinary 
 bidk, every veficlc will be changed from a fphere into 
 a jieifedt cube, touching the adjoining cubes in every 
 poi.it ot Its fix fides, and ftrongly prefied again!! them. 
 It can alfo be dtmonftrated, that if a leaden cube of 
 one iiich be included in the box, and placed with its 
 lidcs parallel to the fides of the box, and the compref. 
 lion be then made, all the little cubic veficles will ac- 
 i|uire the fame pofition. If the box be now turned up- 
 fidc dovvn, it can be denionflrated that the weight of 
 this leaden cube will not be fuffieient for overcoming 
 the relilLuice of the comprefied cubes. This compref- 
 ftd nials will not be fluid, but will require a very con- 
 lider.ible force to prefs the leaden cube through it, juft 
 I's we find fuch a force neceflary for moving a body 
 through melted g'afs : the particles no longer (lide on 
 each other like uncomprefled fpherules ; each will re- 
 quire about half of the comprcfling force, in order to 
 overcome the friction, or obllruilion like friction, pro- 
 duced in (liding along the furface of the contiguous 
 cubes. But we know that air remains perfeftly fluid, 
 although vallly more compreffed than this. This, there- 
 fore, cannot be like the conftitution or furm of air. 
 Moreover, it is well known that air has been made ten 
 times denfer than its ordinary Hate, and is then perfett- 
 ly fluid. It has alio been made a hundred times rarer, and 
 it Hill remains perfectly fluid. In this ftate its particles 
 muft be ten tiines farther removed from each other than in 
 the former fl;ate, of a thoufand times greater denfity. Yet 
 we know that this rare air is compreffed with a force equal 
 to the weight of a fl;ratum of mercury -jd of -an inch in 
 thicknefs, and that if -J-d of this prelTure be removed, 
 it will expand till it is [50 times rarer than common 
 air ; that is, there is fome force which puflies the 
 particles ilill farther from each other. This force evi- 
 dently extends beyond the tenth particle of air that is 
 made ten times denfer than common air. Therefore 
 the elaib'city of air does not arife from the contadl of 
 panicles, which are elaftic like blown up bladders, but 
 from fome force^ which extends beyond the adjoining 
 particles. There is no greater reafon, therefore, for 
 fuppufmg, that the particles of air touch each other, 
 than for fuppofing that the two magnets touch each 
 other becaufe they repel. A row of magnets floating 
 on quickfilver, and placed with their fimilar poles front- 
 ing each other, and very near, will tend to feparate, 
 and they require to be held in by a ftop put at each 
 ' end of the canal ; and if ojie ftop be gradually with- 
 
 drawn the magnets will all feparate, and exhibit the 
 general mechanical effefts of a row of aerial particles 
 feparating by the removal of preffure. Therej feems, 
 therefore, to be the fame necefGty for the operation of 
 an intervening impelling fluid for producing this fepa- 
 ration or eluiticity of the aereal mafs, as for feparating 
 the magnets. 
 !■! very The rtfult of thefe remarks feems to be, that the 
 
 ■doubtfal. impullion of a foot-ball is not brought about in the 
 way that is commonly imagined, by the excitement of 
 
 CO ] IMP 
 
 corporeal prefl'nre at the points of conta£^ of the two ImpuKton. 
 foot balls. For we fee it almoft denionflrated, that the -^-v— — ' 
 progrtflive motion of tli.: anterior part of one of the 
 balls has been produced withuut contart, or, at leafl., 
 by the iriUrvinlioii ot repulfions afting at a dillance.^ — 
 May not this obtain, even in tiie points in which we 
 fuppofe the two balls aclually to touch, in the uol of 
 impulfion ? ^, 
 
 But farther — Every perfon has obferved the brilliant Ma. ] cafei 
 dew-drops lying on the leaves of plants. Every perfou^'^ '"'■'"'"1 
 acquainted with Newton's optical dilcoveries, mull ije'"'"^'-'- 
 convinced that the dew-drop is not in mathematicjl 
 conta6\ with the leaf; if it were, it could have no bril- 
 liancy. Mofl: pcrfons have obferved the rain drops of 
 a fuinmer fhower fall on the furface of water, and 
 roll about for a few feconds, exhibiting the greatefl^ 
 brilliancy. They cannot, therefore, be in mathema- 
 tical contaft with the water. There inuft be a fmall 
 diftancc between them, and therefore fome force which 
 keeps them afunder, and carries the weight, that is, 
 counteracts the downward preffure of the rain-drop. 
 We know that fome infctts with long legs can run 
 about on the furface of water ; and if we lift them care- 
 fully, and fet them on ghls, their feet do not wet it. 
 Put a little fplrit of wine into this water, and make it 
 lukewarm, and the infcdt infl;antly finks up to the 
 belly, and cannot move about as before : Its feet will 
 now wet a glafs. A well-poliflied fleel needle, even of 
 confiderable fize, if perfeftly clean and dry, will float 
 on water without being wetted : It is obferved to make 
 a confiderable, depreflTion on the iurtace of the water, 
 jull as a heavy bar of iron would make when laid on a 
 feather-bed — the needle difplaces a quantity of water 
 equal to itfelf in weight, yet does not touch it, for it 
 is not wetted. If it be previoufly wetted, it will not 
 difplace any water, and will not float. There is fome- 
 thlng, therefore, which keeps the water at a diflance 
 from the feet of the infect, and from the needle, exert- 
 ing a certain upward prelTure on them. The prelTure 
 and the reaction are indeed very fmall ; but they would 
 produce a very fenlible motion if continued fuiliciently 
 long in proper circumilances. Here would be a pro- 
 duction of motion, which moft perfons would call an 
 impulfion — yet there would be no ilroke, no contact, 
 and therefore no true impulfion. 
 
 We now beg the reader to attend minutely to New- 
 ton's famous experiment with the object glafliis of long 
 telefcopes, which we have mentioned circumftantially 
 in the article Optics, Encycl. n" 63 — 68. ., 
 
 When the upper glafs is very thin and light, no co-Very re- 
 lour appears at the point of contaft : but bv pref- m^'kable 
 fing it down with fuffieient force, we fhall have a black "'*^ ."' """ 
 or unrefleAing fpot in the middle, furrounded by a fil-fjifeiy 
 very ring, and then by a feries of rings of various co- feeming te- 
 lours, according to the diilance between the parts oftouch. 
 the glafles where the colours appear. Newtun has 
 counted ^o of thefe rings. He Ihews, by a careful 
 computation from the known figure of the glaflfes, that 
 the differences between the dillances which exhibit 
 thefe colours are all precifely equal, and that each is 
 about -j-j-'oj of an inch. Therefore, fuppofing that the 
 glafles are in mathematical contadt where the unreflcft- 
 ing fpot appears, making one continuous mafs of glafs, 
 their diftance at the outefmoft ring mult not be leis 
 than ygl^ of an inch, or ^\^ of an inch. Therefore, 
 
 whca
 
 IMP ' [ 8or ] IMP 
 
 Itnpnifion. when one glafs carries the other, witllout any appear- llrornr a prcfTure. We then cut out of it, witli a la Initiulfion. 
 
 '^"■V"— ance of colour at the middle, we mud conclude liiat pi.lary's hollow drill, a piece ot } of an inch in diaine- ^~~Y~~— ' 
 there is a rcpnlfion exerted between the ncarcll puits, ter, and perfectly round, and we fquee/od it on the 
 at a diftanee not lefs than .-J-^ of an inch, fuffieient other l)y a meafured prefl'ure, till we produced a tolour- 
 for fupportinjr the upper glafs. It requires an inereafe lei's fpot of nearly ^ih of an inch in diameter, with a 
 of prelTurc to produce the firll appearance of colour; lilveiy margin. Compuuiig from this, we thought 
 and when the prelTure is dill more increaled, new co- ourfelves warranted to lay, that not lefs tiian 8oo pound* 
 lours appear in the middle, and the colour formerly are neeed'ary for producing a black fpot of one inch 
 there is now leen in a furrounding ring; thefe multi- fquare ! ,g 
 ply continually, by new ones fpreadirig trom a central Now, what is the confcquence of all this in the doc-Andmajr 
 i'pot. A great preffiire at lall prodnci.'3 tlie unrellcdl- trine of impiilfion i Suiely this : — If a lump of this'"'!"'""''" 
 ing fpot in the centre, whicli, unlike to all the colour- glafs llrike another lump, and put it in motion, and jf!'""""'"" 
 ed fpots which had emerged in fucceffion, is Iharply the mutnul prelFure in the act of coUifiun do not ex- 
 dtlined, and never round, but rag.;cd, and it is imme- ceed 700 pounds on the fquare inch, the motion has 
 diately furronndcd by a bright tilvcry reflection. The been produced without mathematical contaft, and the 
 (hape of this fpot utpends on the figure of the fur- produClion can no more be called impulfe than the 
 faees ; for, on turning the upper lens a little round its motion ot the magnet in our liril experiment. The 
 axis, the inequalities of the edge of the fpot turn, in changes of motion have been the ojieration of moving 
 fome degree, with it. This fcemlngly trifling remark forces, limilar to the force of magnctifm ; and if a 
 will be found important by the mc(;hanieiau : A Hill ft^ream of truly impelling fluid be neceflary ft)r pro- 
 farther inereafe of prefigure enlarges the unreflecting ducing the motion of the magnet, it is equally necef- 
 tpot, and the dinienfions of all tile rings— ^\'hen the lary tor producing the motion of the piece of glafs. 
 prelTure is gradually witf.drawn, the rings Ihrink in their It ma) be faid here, that we cannot compare imptdfc 
 dimenlions, the unreflecting foot difappears firtl, and and prcifure. A flight blow will fplit a diamond which 
 each ring in luccelTion contracts into a ipot, and va- could fupport a houfe. A flight IJow may therefore 
 niflies. Here we have, by the way, an explanation of be enough tor exciting all thepreh'ure neceflary for pro- 
 the brilliancy of dewdrups : they come fo near, per- diicing matlKmalical contact. We mufl here a|;peal to 
 haps, tl;at the neareit pouit reflects the filvery appear- what every man feels on this occahon. We doubt ex- 
 ance — but tiiey do not touch ; the iiiltant ti.at they ceedingly whether any pcrfon will think that, when 
 toilch a wetted part, making one mafs ot tranfparent one piece of ghifs gives another a gentle blow, and 
 matter, all brilliancy is gone. puts it into motion, with the velocity of a few inches 
 
 Theyrciel Here then are incontellible proofs of a force, be its per fecond, a blow which he diilinCtly hears, there has 
 
 eacii otter; origin what it may, which keeps the glaffes afunder, been exerted a prefi'ure at all approaching to 800 
 
 and even cauies them to fcparate ; which manifelts it- pounds per fquare inch.— -We have fufpended a pair of 
 
 felf by withftanding preflure ; and therefore is, Itlelf, a lenlcs, by an apparatus fo Heady and firm, that they 
 
 preifure, or equivalent to a prefTure — It varies in its in- could touch only at the centres of each furface ; and, 
 
 teniity by a change of diftanee ; lytit we have not been having placed ourfclves properly, we could fee, with 
 
 able to alcertaiii by what hiw. It trull not be mea- lufliclent diltintlnefs, the momentary appearaiice of the 
 
 furtd by the iimple variation of the external prefTure ; coloured fpot at the inftant of colliilon. We faw this, 
 
 for (ince we fee that, even before any colour appears with the fullefl confidence that it was of no coiifider- 
 
 ' in the centre, the weight of tlie upper lens is fupport- able breadth in a moderate Itioke, and that it was very 
 ed, we mufl conclude that the glafles are exerting at fenfibly broader when the ftroke was niore violent. \Vc 
 lead an equal force all around the circumference of the did not trull our own eye alone, but fl:ewed it to per- 
 outcrmoft ring. It is evident, that the computation of fons ignorant of philofophy, and even to children, often 
 the whole force, exerted over all the coloured furface, without telling them what to look for, but afking them 
 mud be difl'iculL, even on the iimpleil hypothefis con- what they faw. From all the int\ rmation that we 
 cerning the law ot repulfion : we can only fay that it could gather, none of the prefTures came near to what 
 increales by a diminution of didance. It is very eafy mod have been necefTary for producing the black fpot. 
 to compute the inereafe of external prefTure, which This could not be miltaken : for allliough the outer 
 would fuffice if the repelling force were equal at all rings are but faint, there are five or lix near the centre 
 dirtances; or if it varied according to any fingle power * which are abundantly vivid for aflectiug the eye by the 
 ot the diftanccs. We have tried the invei fe iimple, momentary flalh. Bcfides, tlie dimenfions of the lenlts, 
 •duplicate, aud triplicate ratio; but the fait deviated and the weight of the metal cells in which thev were 
 widrly from them all. The repuliion does not change fixed, were fuch as mutt have cauled them to Iplit be- 
 nearly fo much as in the finiple inverfe ratio of the fore the black fpot could be produced in the centre, 
 dlftances, if the glafles be fuppofed to touch in tlie Tkefe things being maturely confidercd, we imagine , 
 whole furface of the unreflecting fpot. But we found, that few perfons will now doubt the juftiee of our af-jjiniy"^ 
 that if we luppofe them feparated, thou^jh at a didance fertion, that in all thefe examples, the motions have beenfo, even in 
 equal to forty times the difference of didance i*t which produced without mathematical (or rather geometrical) v'''"' 
 
 the colours change, that is, i4i of an inch, the pref- contadl And we imagine alfo, that few will refufe'*''"''"' 
 
 fures employed in the experiment accord pretty well granting that this is not peculiar to glafs, but obtains 
 
 with a repulfion inverlely as the dillance, but dill with alfo in the collifion of other bodies. We have not ' 
 
 n very confiderable deviation in the great pred'ures. In thought of any method for putting this beyond doubt; 
 
 'he courfe of a number of experiments with a favour, but we have better reafons than mere likelihood for 
 
 fte pair of lenfes, we broke the uppermofl hy too being of this opinion. Every one acquainted with the 
 SUPPL. Vol. I. Part II, 5 I Newtonian
 
 1 
 
 I IVI P 
 
 •[ 
 
 Impulfion. Newtonian dilcoveries in optics, knows that this cu- 
 * » rious appearance of the coloured rings is the confe- 
 quence of the aftion of traniparent bodies on the rays 
 of hght, by which thefe are bent alide from their rec- 
 tilineal courfe, anJ that this defleftion takes place at a 
 dillance from the diaphanous body ; a dillance which 
 the fagacity of the great phiiofopher has tnablcd us to 
 meafure. Now, it is known that metals and other c>paque 
 bodies produce the very fame dcfleftions of the rays, 
 bending them toward themftrlves at one dillance, and 
 from them at other diftances; in fhort, attradling or re- 
 pelling them as the dillance varies. Nothing but pre- 
 pofTeffion can hinder a perlon from afcribing limilar ef- 
 fects to fimilar caufcs, and, therefore, thinking it al- 
 mofl certain that this mutual repuHioH is not peculiar 
 to glafs, but common to all folid bodies. 
 
 To all this we may fiirely add the celebrated expe- 
 riment of Mr Huyghens ; in which it is evident, that a 
 fmooth plate of metal attrafls another, even although 
 there be a filk fibre interpoftd between them. (See 
 Fhil. Tranf. n°S6. ) Is it not highly probable, that 
 at 3 fmaller dillance the bodies repel each other ? For 
 we obfervf, that metals, as well as tranfparent bodies, 
 attraft the rays at one dillance and repel them at an- 
 57 other. 
 ImjulGon Surely our readers will now grant, that the produc- 
 
 ".° ° ?"tion of m.otion by impnlfion, as ditlinjjuifhed from the 
 miliar as IS ^. * ,, ^ . . r r -t i 
 
 believed, produftioa by action e dijianli, is not lo lamuiar a phe- 
 nomenon as was imagined, and that it may even be iiiid 
 to be rare in comparifon : for the inftances of mode- 
 rate impulfes are numberlcfs. The claim of this mode 
 of explaining difficult phenomena by impulfion, has 
 therefore loft much of its force ; and we fee much lefs 
 reafon for calling in the aid of invifible fluids, in order 
 to explain the aftion of gravity, inagnetifm, and electri- 
 
 Stillgreater But we have flill more important information from 
 doubts. Ob-tlie optical difcovery of Newton. Let the reader turn 
 again to Optics, Eiuycl. n" 65, and read the account 
 of the phenomena exhibited by the foap-bubble. The 
 bubble is thinner and thinner as we approach the very 
 uppermoft point of it. It alfo exhibits numerous rings, 
 which vary in their colour, in the fame order as in the 
 fpace between the lenfes. Thefe rings come to view in 
 the fame manner. Firll, a coloured fpot appears in 
 the fummit of the bubble ; this becomes a ring, and is 
 fucceeded by another fpot, as the bubble grows thin- 
 ner in that part, by the gradual fubfiding of the wa- 
 tery filir. At laft a black fpot appears at top, well 
 defined, but of irregular (hape, furrour.ded by a filvery 
 ring. This fpot, when viewed very narrowly, is ob- 
 ferved to retleft a very minute portion of light, \\\ih- 
 o\it fef'arcting the diflertntly cclorific rays of which it 
 confitls; but it contains them all, as may be proved by 
 viewing it through a prilm. After fome little time 
 the bubble burfts. 
 
 Surely we mull infer from this, that there is a certain 
 thicknefs of the tranfparent plate which renders it unfit 
 for tlie vivid rcflettion of light. Does it not legitir 
 maiely follow from this, that the unreflecling ipot be- 
 tween the lenfes ceafes to entitle us to fay, that they 
 are in contaft in that place ? All that we can conclude 
 from its appearance is, that the dillance ftil! between 
 the glalTes is too fmall to fit the place for the vivid re- 
 flexion of light. This conclufion is indifputable. Were 
 
 fervatlons 
 on a foap 
 bubble. 
 
 802 1 .IMP 
 
 it refufed, we are furniflied with an inconteftible proof Impulfi..n, 
 by the fame bountiful hand. Newton afcribed the co- " " » ■ ' 
 lours to the reflection of the plate of air between the 
 glaffes, and expetted the celTation of them when the air 
 is removed. His friend Mr Boyle had lately invented 
 a commodious air pump. The trial was made, and 
 young Newton found himfelf miftaken ; for the colours 
 ftill appeared, and he even thought them more brilliant. 
 He then tried the effedl of water, expefting that this 
 would diminifh their luftre. So it did ; and he found 
 that the dinienfions of the rings were dimiiu'ihed in the 
 proportion of 4 to 3 ; namely, the proportion of the 
 refractions of glals and water. By this time Newton 
 had difcovcred the curious mechanical relation between 
 bodies and the rays of light ; and his mind was wholly 
 abforbed by the difcovery, and by the revolution he 
 was about to make In the mathematical doftrines of 
 optics. Unfortunately for us, he did not, at that time, 
 attend to the mighty influence which the difcovery 
 would have on the whole of mechanical philofophy, and 
 therefore occupied hin.felf only with fuch phtnomena 
 as fuited his prclcnt purpofe. A moft importaiit phe- 
 nomenon palled unnoticed. In repeating i-^ir Itaac 
 Newton's experiments, we found that the diameters of 
 the rings decreafed in the proportion of 4. to 3 only in 
 certain circumftances. "When the upper lenfe wa& 
 prefled on the other by a heavy metal ring, fo as to 
 produce three or four coloured rings, we found that 
 when water got between them, fometimes no colours 
 whatever appeaj'ed; fometimes there was a ring or two, 
 and the diameters were diminilhed in a much greater 
 proportion than Newton had afiigned. Well afl^ured 
 of the extreme nicety of all his proceedings, we were 
 much puzzled with this difcrepancy, and mentioned 
 it to a moll refpeclable and intelligent friend, the late 
 Dr Reid of the nniverfity of Glalgow, a mathematician 
 and naturalill ot the firft rank. He thought it not im- 
 probable that the glallea- feparated from each other, 
 lifting up the weight, by attradling the water into the 
 interilice, in the latre manner that we oblerve wood to 
 fwell with moillure. We immediately got an apparatus 
 which comprcffed the glalRs by means of four Icrews ; 
 and now we law Newton's proportion moft ftiiflly ob- 
 ferved. But in profecuting the experiment, we found 
 that the introduction of the water al'ways effaced a 
 very fmaU fpot. This happened after precautions had 
 been taken to prevent all feparation of the glailes. 
 As the profKirtion of 4 to 3 has a relation to retraCbve 
 power, although we have not been able to deduce it as 
 a necelfary confequence, we ncverthelels confidercd it 
 as a fufiicient proof that the diftances ot the glaifcs had 
 not chciiged by introducing the water between them. 
 Therefore we think curlelves well entitled to conclude, 
 that the dilappearance of the black tpot was not owing 
 to a feparation of the glaflts, which admits the water 
 into the empty fpace ; and we afiirm, that before the 
 entry of the water, there was room for it in the place 
 which reflefted no light ; that is, that although the glafies 
 were prefled together with a very great force, they were 
 not ill contaft. 
 
 It deferves remark, that in endeavouring to pi'O'iuce f^jj|jjj.jj^ 
 the black fpot, when water is between the glailes, we 
 found great and unaccountable anomalies. Sometimes 
 a moderate increaie of preflure produced it, and fome- 
 time3,:we were not able to produce it by any preflure. 
 
 Several
 
 I 
 
 I M P 
 
 Inipuinan. Se»fral lenfes were broken in tlie tr'al 
 
 >— "\ ^ll\lnk that the thickiicfs which givts the filvciy ie(h i-- 
 
 tioii is mucli greater than the Hyooth part of an inch, 
 and that it is not the lame in all glailVs. But we were 
 interrupted in tliefe experiments, and indeed in all aiJtive 
 puriuits, by h id health, which has never permitted their 
 renewal. I'he Aibjed is of great importance to the cu- 
 rious mechanicians, and we earnelUy recommend it to 
 their attention. 'Inhere is fomething very remarkable 
 in the abrupt fenfation of the coloured refleeiion. At 
 a certain tliicknels all colours are rtflcAed, without re- 
 paration, producing the whiteiiefs of filver. The Imall 
 ell diminution of it hinders the vivid refltftion of all 
 colours, and then there feems to iueceed a thicknels 
 which equally reiietts a (mall propoition ui all without 
 feparation. 'The fine rt polilh, that can be given to glals 
 in the tool of the artill. leaves inegularities which dc- 
 callon the irregular ragged figure ot the ipot. It is 
 worth trying, whether fmoiilliing the furtaces (both) by 
 a foftening heat will remove this rnggcdnefs. 11 it rio^s, 
 without deftroying the iharp Icrniination, it will prove 
 the abrupt palfage irom (J/c to notiejfe. 
 
 The lait remark to be made on this important expe- 
 riment in optics is, that the diilance between the glailes 
 which is unfit for vivid refleiiion, cannot be determined 
 by means of the other nieafurable intervals. It may be 
 equal to many of thtm taken tugelher. The fame mult 
 be granted with refped to the thicknefs of the black 
 fpot on the top of the foap bubble. We attempted to 
 meafure this thicknefs by letting a drop (of a known 
 weight) of fpirit of turpentine Iprtad on the furface of 
 Vater. As it flowly enlarged in lurtace, it decreafed 
 in thicknefs, and produced, in regular order, feveral of 
 the more compounded colours of the Newtonian (erics. 
 But hefme it came to the 20th ring from the centre, it 
 became very irie^inlar and (potty. 
 
 The inference to be drawn from this combination of 
 
 ncit pr..vctl the two optical facts is remarkable and important. It 
 '• is. lliat we have no authority (or aflirming that the 
 changes of motion by the colhdon of bodies is brought 
 about by abfolute cor.tacl; in a..y inllance whatever. 
 The glafles are not in contatl where there is vivid re- 
 flection ; and vv'e have no proof that they are in contaft 
 in the black fpot, however great the comprefiion may 
 be. 
 
 It is hardly necefiary now to fay, that all attempts 
 to explain gravitation, or magnctiim, or eledtricity, or 
 any fuch apparent aftion at a diilance by the impuHions 
 
 P ''.'"?""" of an unleen fluid, are futile in the greateft degree. 
 * Impuliion, by ablolute contaft, is (o far from being a 
 familiar phenomenon, that it may JLiftly be quellioiied 
 whether we have ever oblerved a (ingle inftance of it. 
 The fuppofition of an invifible impelling fluid is not 
 more gratuitous than it is u(clc(3 ; becaufe we have no 
 proof that a particle of this fluid does or can come into 
 contaft with the body which we fuppofe impelled by 
 It, and therefore it can give no explanation ot an action 
 6( that is apparently e iliftanti. 
 
 Butimpul- The general inference from the whole feems to be, 
 
 Son may be jjj^j^ inllead of explaining preffure by impulfe, we muft 
 
 bv onf- "Ot only derive all impnlle from preffure, but muft alfo 
 ■ alcribe all preflure to aftion from a diftance ; that is, 
 to properties of matter by which its particles are moved 
 without geometrical contaft. 
 
 This colie6tion of tacls confpires> with many appear- 
 
 [ K03 J I M P 
 
 We are led to anceg of fluid and folid bodies, to prove that even the Jmii""ifiii, 
 pai tiilcs of lolid, or h.nfil.ly ciiiitiiuiouo bodies, are not ""*"' "' ' ' 
 in contaft, but arc held in their refpective lituations by 
 the bahiiice of forces which we are accullomcd to call 
 attrattionii and rcpulfiuns. The fluidity of water under 
 very llroug compiefiions (A'liich have been known td 
 compreCs it .j'jth ot its bulk), is as iiiconhftent with the 
 (ujipotition of contatl as the fluidity of air is. The 
 (hrinkiiig of a body in all its dinienfmns by coid, nav, 
 even the bending o( any body, cannot be c(nicei\ed witji- 
 out allowing tliat/;m« of i:s ultimate unaltciabie atoms 
 change their dillaiiees from each other, 'l he phtno'. 
 mena of capillary attraction are alio inexplicable, with- 
 out admitting thai particles aft on others at a dillanct 
 from them. 1 he tormatioii ot water into drop,, the 
 coalefcence of oil under water into (pherical did]is, ot 
 into circular ("pots when on the furface, fliew the fame 
 thing, and are inexplicable by mere adhefion. In fliort, 
 all the appearances and mutual actions of tangible mat- 
 ter concur in (he\Ving, that the atonls of matter are en- 
 dowed with inherent forces, which caufe thcni to ap- 
 proach or to avoid each other. The opinion of Bof- 
 covich (erms to be well founded ; namely, that at all 
 fenlible dillanccs, the atoms of matter tend toward tai li 
 other with forces iiivirfely astlie fquavesof the diilauces, 
 and that, in the iiearelb approach, they avt.id each other 
 with ifiJiipii-aUe force; and, in the intermediate diflan- 
 ces, they approach or avoid each other with forces vary- 
 ing and alternating by every change of diilance. See 
 the article Boscovich, Suppl. 
 
 59 
 
 ■Coiitart 
 
 ulIiDo 
 
 60 
 Therefore 
 inipuirinn 
 cannot ex 
 
 nued i)ref 
 fure. 
 
 From all that has been faid, we learn that phyficalPh)ficat 
 or fenlible contad difl^ers from geometrical contact, hi '°"."'^' '^*' 
 the fame manner asphyfical folidity differs from that ofP'*'""=<'' 
 the mathematician. Euclid fpeaks of cones and cylin- 
 ders Handing on the fame bale, and between the (ame 
 parallels. Tliefe are not material folids, one of which 
 Would prefs the other out of its place. I'hyhcal con- 
 tact is indicated, immediately and directly, by our (enfe 
 ot touch ; that is, by exciting a preflure on onr org;m 
 of touch when it is brought fufliciently near. It is alfo 
 indicated by impultion ; which is the immediate e(fe6t of 
 the preffure occafioned by a futRrient approximation of 
 the body impelling to the body impelled. The impul- 
 fion is the completion of the fame jirocefs that we de- 
 (<Tibed in the example of the magnets ; but the extent 
 of fpace and of time in which it is ccmipleted is fo fm.iH 
 that it efcapes our obfervation. and we imagine it to 
 be by contact and in an iiiltant. We now lee that it 
 is fimilar to all other operations (if accelerating or re- 
 tarding forces, and that 110 change of velocity is inllan- 
 taneous ; but as a body, in palfing from one point 'if 
 fpacc to another, pafl'es through the intermedi'ate fpace; 
 fo, ill changing from one velocity to another, it ].afle» 
 through all the intermediate degrees without the imaW- 
 eii /alius. 
 
 And in this way is the whole doftrine of impulfion We thin 
 brought within the pale of dynamics, without the ad- avoid many 
 mifiion of any new principle of motion. It is mtrely "'"•^"rditie*. 
 the application of the general dottriues of dynamics to 
 cafes where every accelerating or retarding torce is op- 
 pofed by another that is equal and contrary. Wc have- 
 found that the opinion, that there is inherent in a mo. 
 ving body a peculiar force, by which it perfevcres iii 
 nrotion, and puts another in motion by /hiftinp into it, 
 5^2 i»
 
 IMP [ 804 ] IMP 
 
 lnipul6on. is as ufelefs as it is inconiulent with our notions of mo- we give over fpeaking of inertia as fomctliing diftiii. Iiupulfion. 
 " t ion and ot moving- forces. The impelietl body is nio- guifiiable from the aftivc forces or caufcs of motion **""> ^ 
 ved by the infuperable repuhion exerted by all atoms of which we find in bodies, and diftinguifh by the names 
 matter when brought fufHcieiitly near. The rctarda- of elallicity, cohefion, magnetiim, elcftricity, weight, 
 lion of the impelling body does not arife from an (nfr/i(7, &c. and which ])hilofophers have claflcd under one 
 or refilling (luggifhnefs of the body impelled, but be- name, accelerating or retarding force, according as its 
 caufe this body alfo repels any thing that is brought fuf- direftion chances to be the fame, or the oppofite to thtt 
 fitiently mar to it. We can have no doubt of the ex- of the motion under confidcration. To fuppole it a 
 illence of fuch canfes of motion, bprings, expanfive peculiar faculty by which a body maintains its condition 
 fluids, cohering fibres, exhibit fuch active powers, with- of motion or reft, is contrary to every conception that 
 out our being able to give them any other origin than we can annex to the words faculty, power, force. It 
 the FIAT of the Almighty, or to comprehend, in any is frivolous in the extreme to fay, ti.'at fnow has the fa- 
 manner whatever, how they relide in the material atom, culty of continuing white or cold ; or that it refills be- 
 But once we admit their exillence and agency, every ing mtlted becaufe it melts, or becaufe heat mull be em- 
 thing elfe is deduced in the moll fimple manner ima- ployed to melt it. 
 
 ginabk, without involving us in any thing incompre- The only argument that we know for giving thestroneefl: 
 heniible, or having any confequence that is inconfillent name force to the perfeverance of matter in its ftate of argument 
 with the appearances. Whereas both of thefe obllruc- motion (or rather for afcribiiig this perfeverance to the'°'' intrtia 
 tions to knowledge come in our way, when we fuppofe exertion of a peculiar faculty), which appears to de-'^J^j",^ '^""l" 
 any thing analogous to force inherent in a moving body ferve any attention, is one that we do not rccolieil t he joi-ce with 
 fokly becaufe it is in motion. It forces us to ufe the un- exprefs employment of for this purpofe, namely, the a previous 
 meaning language of force and motion paffing out of one compofition of a previous motion with the motion which '"""•«'• 
 body into another ; and to fpeak of force and velocity a known force would produce in the bodv at reft. We 
 as things capable of divifion and aftual feparation into know that if a body be moving eaftward'at the rate of 
 parts. The force of inertia is one of the bitter fruits four feet per fccond, and a force aft on it which would 
 of this mifconception of things. It is amufing to fee impel it from a (late of refl. at the rate of three feet per 
 how metaphyficians of eminence, fuch as D'Alembert, fecond to the fouth, the body will move at the rate of 
 endeavour to make its operations tally with acknow- five feet per fecond in the direftion E. ^6= 32' S. 
 ledged principleit. In liis celebrated work on dyna- We know alfo, that if a force aft on this body at reft, 
 mics, the moft elaborate of all his performances, he ex- fo as to give it a motion eaftward at the rate of four 
 plains how a body, whofe mafs is i, moving with the feet per fecond, and if another force aft on it at the 
 velocity 2, muft flop another body whofe mafs is 2, fame inftant, fo as to give it a motion to the fouth at 
 moving with the velocity i, in the following manner : the rate of three feet per fecond, the body will move at 
 He fuppofes the velocity 2 to confift of two parts, and the rate of five feet per fecond in the direftion E. 36" 
 that, in the inftant of collifion, one of the pans deftroys ^2' S. In this inftance, the body previoufly in motion 
 the motion of one half of the other body, and then the feems to pefTefs fomething equivalent to what is allow- 
 other part deftroys the motion of the other half. Thefe ed to be a moving force. Why therefore refufe it the 
 are words ; but in vain ftiall we attempt to accompany name ? The anfwer is eafy. The term force has been 
 them by clear conceptions. His dillinftion between applied, by all parties, to whatever produces a change 
 
 of motion, and is meafured by the change which accom- 
 panies its exertion. There is fome difference between 
 the parties about the way of cftimating this meafure ; 
 but all agree in making, not the motion, but the change 
 of motion, the bafis of the meafurement. Now we Anfwereu 
 
 the force of inertia and what he calls the aftive forces 
 of bodies, fuch as the force of bodies which ftrike 
 each other in oppofite direftions, is equally unfufcep- 
 ticle of clear conceptions. Aftive forces (fays he) ab- 
 forb a part of the motion ; but when inertia takes 
 
 part of the motion from the ftriking body, this motion iliewed, at great length, in the article Dynamics, that 
 paffes wholly into the body that is flricken, none of it the change of motion, in every cafe, is that motion 
 being abfurbed or really deftroyed. H e demo nftrates vvhich, when compounded with the former motion, 
 this by the equation AXa — x ■=. BX» — b, which conftitutes the new motion. Did we take the new 
 is a mere narration of fafts, but no deduftion from the motion itfelf as the charaften'ftic and meafure of the 
 nature of inertia, nor even any eftabliftinient of that na- changing force, it would be different in every different 
 ture by philofophical argument. And in attempting previous ftate of the body, and would neither agree 
 to give ftill clearer notions (being fenfilde that fome with our general notion of force, nor with the know- 
 great obfcurity ilill hangs aboi-t it), he fays, " Inertia ledge that we have of the aftual prefiures and other 
 therefore, and properly fpeaking, is the mean of com- moving forces that we know. The fole reafon why 
 municating motion from one body to another. Every the previous motion is equivalent with a force is, that 
 body refirts motion ; and it is by refilling that It receives the only mark or knowledge that we have of a moving 
 it ; and it receives precifely as much as It deftroys in force is the motion which it is conceived to produce, 
 the body which afts on it." Surely almoll every word The force Is equivalent with the previous motion, be- 
 of this fentence is doing violence to the common ufe of caufe ive know nothing of it but that motion ; and the 
 language. What can be more incomprehenfible than name that we give it, only marks fome external thing; to 
 that a body refifts motion only when it receives it.' which it has an obferved relation. We call It magnetlfm 
 Should a man be thought to refift being puftied out of or eleftriclty, becaufe we obferve that a magnet or an 
 his place when he aftually allows another to difplace eleftrified body gives occajion to its appearance. We 
 him, and not to refift when he firmly keeps his place ? never obferve the refiftance of inertia, except in cafes, 
 All thefe dilficulties and puzzling queftions vaniOi whea where we know, fr.o^.other cireuraft.aaces, that mo.ving 
 
 forces
 
 r M p 
 
 r 8 
 
 frnpuKi'T. forces inherent in bodlfs are really brought into aftion. 
 V Till.' iiKvtia of the ball which has been iriDVcd by a 
 
 ftroke of aiiothfr, is inferred from the diminntioji of 
 that other's motion. But this is occafioned precifely 
 in the f.ime way as the diminution of the motion of tlic 
 magnet A in the firil example ; an event which every 
 unprepolTtfitd perfon alcribes to the repnlfion ol li in 
 the oppofite.direftion, and not to its inertia. 
 
 We truft that our readers are not difpleafed with 
 this detail of the procedure of Nature in the phenome- 
 na of impulfion. It has been prolix ; becaufe we ap 
 prebend, that the too fynoptical manner in which the 
 laws of collihon have always been delivered, leaves the 
 inind in great obfcurity concerning the connexion of 
 • he events. General faiSts have been taken for philofo- 
 phical principles and elementary truths ; whereas they 
 were deduflions from the fnm total of our knowledge. 
 They were very proper logical prmciples for a lyuthe- 
 ticul difcuffion ; but their previous elLablilhment as ge- 
 neral fafts was necedary. We have eflablifhed the two 
 moft general fafts from which the relult of every colli- 
 fion may be deduced with the utmoli. eafe. The firft 
 is, that in the inftant of greatell conipreffion, the coni- 
 
 Art=t:Bi 
 movi velocity is =: . ^r — ; and we have ihewn that 
 
 this is applicable to the collillon of ijnelaftic bodies. 
 The fecond is, that the change in perteftly elallic bodies 
 is doiible of the change in unelaftic bodies. The conferva- 
 i'w momeiitortim, and the conjervatio inrium I'ivan/m, are 
 alfo general fafts ; or rather they are the fame mention- 
 ed with thofe above, confidered in another afpcft. They 
 nay all be ufed as the principles of a fynthetic treatife 
 of impulfion ; and they have been fo employed. Each 
 has its own advantages. 
 
 Mr Maupertuis gives a treatife on the Communica- 
 tion of Motion, that is, of impulfion or coUifion, which 
 has the appearance of being deduced from a new priii- 
 ciple, which he calls the principlk of smallest ac- 
 tion. He fuppofes tliat perftd: Wifdom will accom- 
 plifh every thing by the fmallefl expenditure of action; 
 and he chanced to obfcrve, in the equations eniplovcd 
 in the common dodirine of impidfion, a quantity which 
 is always a miiiimum. He chooles to tonfider this as 
 tiie expredion of the aftiou. 
 
 His principle or axiom, deduced from the perfeft 
 wifdom of God, is thus exprelTed : " When any change 
 bappens in nature, the quantity of aflion neceflary for 
 n is the fmalleft pofTible." And then he adds, 
 
 *' In mechanical changes, the quantity of aftion is the • 
 prodnft of the quantity of matter in the body by the 
 fpace paffed over, and by the velocity of the motion " 
 'i'his is evidently the meafure adopted long before by 
 l^eibnitz (fee Phi/. Tranf. vol. xliii. p. 42^, fkc), and 
 it is equivalent to m v" ; becaufe the fpace multiplied by 
 the velocity is as the fquare of either. We refer to 
 Dr Jurin's remarks on this paffage for proof lliat thij 
 is by no means a jult meafure of aiSlion ; and only ob- 
 ferve here, that we can form no other notion of veloci- 
 ty than that of a certain fpace defcribed in a given time. 
 The change produced is not the aftual defa'ij'tion of 
 a line, but the determination to that motion. It is in 
 this refpeft alone that the condition of the body is 
 changed ; and therefore the produdt m i>, and not ms-u, 
 is the proper meafure of the aflion. On the authority 
 ef this maxim of divine conduft, Maupertuis invefti- 
 
 «4 
 
 'Principle 
 rf fmalleft 
 action. 
 
 oj ] IMP 
 
 gates the refult , which will make this quantity a mini- Impulfion. 
 mum, and ad'eils that thefe mujl be tlic laws of col-*~~^" ' 
 liiion. Luckily this inveltigation is extremely fimple, 
 and very neat and perfpicuous ; and it gives very eafy 
 iolutions. For example, the uuelallic body A, movinjj 
 with the velocity a, overtakes the unelallic body B, 
 moving with the velocity h. Both move after the col- 
 lifion with the velocity x. This velocity is required. 
 To determine this, we mull make A Xu — »|' -|- B X 
 X — Z'l' a minimum ; or A «' — 2 A o x -^ A .\= -f B x* 
 — 2 B i K + B 4^ is a minimum. Therefore — zh.a x. 
 + 2 A .\- A + 2 B K .V — 2 B i .V =. o, or 2 A a -f- 2 B 3 
 
 , T> , Aa-f-Bi 
 
 = 2 A .■<: -|- 2 B A", and x = — v^ . „ ' ; as we hare 
 
 already fliewn it to be. 
 
 The amiable and worthy author grew more fond of 
 his theory, when he law what he imagined to be its in- 
 fluence extended to an immenfe variety of the opera- 
 tions of nature. Euler demonftrated, that the quan- 
 tity called anion by Maupertuis was a minimum in the 
 planetary motions, and iadeed in all curvilineal motions 
 in free fpace. But all the while, this principle of leatl 
 attion is a mere whim, and the formula which is fo p'- 
 nerally found a minimum has no jierceptlble connection 
 with the quantity of adion. In many cafes to which 
 Maupertuis has applied it, the conclulions are in direct 
 oppofition to any notion that we can form of the eco- 
 nomy of aftion. Nay, it is very difputable whether it 
 does not, on the contrary, exprels the greatell want of 
 economy ; namely, a minimum of effeft from a given 
 expenditure of power. In the cafe of impulfion, this 
 miaiuium is the inathtmalical refult of the equality and 
 oppofition of aftion and reaftion. Maupertuis might 
 have pleafed his fancy by faying, that it became the 
 infinite wifdom of God to make every primary atom 
 of matter alike ; and this would have aiifweied all his 
 
 There flill remains to be confidered a very material Enqu„y 
 circumlbmee in the doitrine of impulfion, which pro- into tfie dif- 
 duces certain modifications of the motions that are of"'''.'"''°" 
 mighty practical importance. We have contented our-? ""'lu,' 
 felves with merely ftating the moving force that isp„int tha: 
 brought into aftlun in the points of phyfical contaiTtpt ftrucli. 
 but have not explained how this produces the progref- 
 five motion of every particle of the impelled body, and 
 what motion it really does produce in the remote par- 
 ticles. A body, befides the general progrefSve motion 
 which it receives from the blow, is commonly obferved 
 to acquire alfo a motion of rotation, by which it whirls- 
 round an axis. It has not been ihewn, that when a 
 body has received an impidle by a blow in a particular 
 direClion on one point, it will proceed in that iliVeilion, 
 or in what direiSliou it will proceed. Experience flievvs 
 us, that this depends on circumflanccs not yet confider- 
 ed. The billiard player knows, that by a llroke in one 
 direftion he can make his antagonill's ball move in a 
 direftion extremely diflerent. 
 
 Thefe are queflions of great intricacy and difficulty, 
 and would employ volumes to treat them properly. 
 We have already enlarged this article till we fear that 
 we have exhaufled the reader's patience, and deviated 
 from the proportion of room juflly allowable to impul- 
 sion. We mull therefore limit our attention to fuch 
 things only as feem elementary, and indifpenfably ne- 
 ceflary
 
 46 
 AiSlioii of 
 bodies by 
 contaft is 
 
 (ui face. 
 
 IMP [806 
 
 trwpu l fi'in . ee/tary Tor a ufcful application of the Jodrir.e of im- 
 ' pulfion. 
 
 With refpeft to the direS'inn of the motion pioflucej 
 by impull'ion, the veiy example jiill now borrowed from 
 hiUiard playing, fliews that it is important, aid by no 
 means obvious. We are forry to f^v. that we have no- 
 thing; to ofTtr in iohition of tliis qiitllion that will be 
 received by all as demoiiilration. It is comprehended 
 m the following propofiiion, which we bring forward 
 merely as a m.itter of fart. 
 
 The dircdtion of the ftroke or preffure exerted by 
 two bodies in phylical coritaft, is always perpendicular 
 . to the touching furfnces. Of this truth we have a very 
 eular to the'^''^''"^^ and pretty example and proof by the billiard 
 touching table. If two balls A and B (fig. 2.) are laid on the 
 table in conta<3, and A. is, fmartly ftruck by a third ball 
 C in any dirciSion C c, fo that the line a A, which 
 joins the )X)int of contaA a with the centre A, may 
 make an obtufe angle with the line AB, joining the 
 centres of the two balls, the ball B will always fly off 
 in the dirctlion ABF. The preffure on B, which pro- 
 duces the impuUlon, is evidently exerted at the point 6 
 of contaA, and the direftion IjF is perpendicular to tiie 
 plane GiH, touching both balls in the point i. The 
 primary Rioke is at u, and ads in the direftion a A, 
 although C moved in the diredion C <;. Had A been 
 alone, it would have gone off in the direftion a A pro- 
 tluced. But tlic force acting in the dirtftion a A is 
 equivalent to the two forces ail and d A, of which 
 tl A preffts the bill on B at li, and produces the mo- 
 tion. In like maimer, another ball E, fo laid that ilie 
 is obtufe, will fly off in the direftion ED, which may 
 ^ven be oppofitc to Cc. Thefe are mattci.s of faft ; 
 not indeed precifely fo, becnufe billiard balls are rot 
 perfectly elaftic, relloring their figure with a prompti- 
 tude equal to that of their compreflion ; and alfo be- 
 cvufe there is a little friftion, by which the point a of 
 the ball A is dragged a little in the direction of C's mo- 
 tion. This may both give a twirl to A, and diminilh 
 its preffure on B. The general refult, however, is 
 abundantly agreeable to the dodrines now delivered. 
 But we widi to fliew on what propertic:; of tangible 
 matter this depends ; and although we dare not hope 
 for implicit belief, we expe<it fome credit in what we 
 (hall offer. 
 
 Pemondra- We have evident proof, that at a dittance which fs 
 «ion. not unmealureable by its minutenefs, and certainly far 
 
 exceeds the 900th part of an inch, bodies repel each 
 other with very great force. This diftance alfo far ex- 
 ceeds the. dillance between the particles, if thefe are 
 difcrete. Let inn (fig. <.) be the diftance at which a 
 particle repels nnotlicr, and let P be a particle fituated 
 at 3 lefs dillance than n n from the furfacc .'^C of a fo- 
 lidbody. With a radius FA, equal to m tt, defcribe a 
 fegraent of a i'phcre .^BC, and draw PB perpendicu- 
 lar to AC. It is plain that every particle of matter 
 in the fegment ABC repels the particle P, and that it 
 is not affeded by any more. Let D be any fuch par- 
 ticle. It repels P in the diredion DP. But there is 
 another particle J fimilarly fituated on the other fide of 
 PB. This v\Ill repel P with equal force in the direc- 
 tion ^P. Theiefore the two particles D and d will 
 produce a joint repulfion in the dlredion BP. The 
 like may be fald of every particle and its correfponding 
 mne an ihs wther fide of PB. Therefore the joint re. 
 
 1 T M* P 
 
 pulfion of all the matter in the fegment will have the linptilO'in. 
 diredion BP. It is j)laia, that the radius of curvature ^^~N 
 of every fenfible figure may be confidered as immenlely 
 great in comparifon of m n ; and therefore the propofi- 
 tion Is manifeft. 
 
 This is a propofiiion of very great importance to the 
 artift and the engineer, as well as to the philofopher. 
 In all the connections of engines and machines, the mu- 
 tual adion is regulated by this fad. Thr mutual pref- 
 fure at the cont;Ads of the teeth of wheels and pinions 
 depend fo much on it, that it is eafy to make them of 
 fuch a iTiape that they (hall produce no force wlntever 
 that is of any fervice; and it requires a nilUed attention 
 to their forms to obtain the fervice we want. Tills 
 will be confidered with fome care in the article Ma- 
 chine. 
 
 Having thus difcovered the d'lredion of tlie real Im- 
 piihion, and that it nny be very different from that of 
 the force exerted, we proceed to confjder what will be 
 the diredlon and velocity of the motion, and whether it 
 will be accompanied with any rotation. g_ 
 
 Our readers are acquainted with the elementary me- a ftroke, 
 chanical property of the centre of gravity. If a body whofe ac- 
 he fupported at this 
 upwards, and equ^i 
 
 tide of matter in it, it will not only remain at relt, butrfap.ifi- 
 will have no tendency to incline to either fide ; that Is,'i"n of fnlict 
 
 5 point by a force adin? vertically', "Pp' 
 to the united weight ot every psr-ji^^, ^^^,^^ 
 
 the upward force balances the weight of the whole ''°j^> > "V 
 body, and the mechanical momenta of all the heavy'" ' 
 
 elsuwith- 
 
 particles balance each other, like the weights in thction. 
 foales of a fteelyard. That this may be the cafe, we 
 know that if tlie weight of every particle he multiplied 
 into the horizontal lever by which it hangs (which Is a 
 line drawn from the particle ptrpendlculir to a vertical 
 plane paffing through the centre of gravity), the iuin 
 of all the produdo on one fide mutl be equal to the luin 
 of all the produfts on the other fide. Therefore, if 
 we fiippofe the particles all equal, and rcprcfent each 
 by unity, the luins of ;dl the pci pendlcubrs themfidvei 
 muft be equal. How is this balancing effected ? Every 
 particle tends downwards with a certain force. It mull 
 therefore be kept up by a force precifely equal and op- 
 pofite. This mull be propagated to the particle by 
 means of the connediug corpufcular forces. The force 
 propagated to any particle is equal and oppofite to the 
 force adiiig on that particle, which it balanced ; and if 
 not balanced, it would produce a motion equal and op- 
 pofite to that produced by the other force. Gravity 
 would caufe every particle to defcend equally; therefore 
 the force ^^'hich, by ading on one point, excites thole 
 balancing forces 011 each particle, would caule them to 
 move equally upwards. And fince this is true wratiy 
 altitude of tlie body, it follows, that a force ading in 
 anv diredlon through the centre of gravity, will caule 
 all the particles to move in that diredlon equally ; that 
 is, without rotation. 
 
 Hence we learn, that when the diredlon of the ftroke 
 given to any body paffes through the centre of gravity, 
 the body will move in that direction without any rota- 
 tion. If the quantity of matter, or number of equal 
 particles in the body, be ?;;, the moving power P will 
 imprefs on each particle an accelerating force f, equal 
 
 P 
 to the rath part of P. Thereforey= — , and P = mf. 
 
 Aa accelerating force is eftimated by the velocity f, 
 
 whick
 
 I -u P 
 
 r 8 
 
 Thi= U A". 
 reci l.viPUL' 
 
 Iniru'fi'-''" wtiich it f;enerates by ailing im;i"ormIy during fome 
 
 time /, or V =z ft, and /" = — , and P =: ;n -, and 
 
 P . .. ' 
 
 ■u =: — /. The fyinbol t may be omittcil, it wc reckon 
 m ' 
 
 every force by the velocity which it can produce in a 
 fecoiid. Thus may all forces be compared with gra- 
 vity, by talcing ;^2 feet for the mealure of gravity. 
 Then m v will exprels the number of pounds which 
 give a prcITure equal to the force under confideration. 
 Thus if the force can gene\;ite the velocity 48 feet 
 per fecond in too pounds of matter, by afting on it 
 uniformly during a fecond, its prelTure is equal to the 
 wciijht of 150 pounds. 
 
 When a body A, moving with the velocity a, over- 
 takes or tneets a body B, moving with the velocity b, 
 ar.d the line perpendicular to their touchlnir furfaees 
 paffes through the centres of both in the direction of 
 their motion, all the circumilances of the collilion are 
 determined by the rules already laid .down. This is 
 called DIRECT impulse; and it is this which adinits 
 the application of the fimple doflrines of impullion, de- 
 duced, as we have done it, from the ottion of accelera- 
 ting forces. All that was faid af the changes of mo- 
 tion produced in the magnets obtain here without any 
 farther modification. 
 
 We may jnft be allowed to take notice of a curious 
 obfervation of Mr Huyghens onthecollifion of perfect- 
 ly claftic bodies. Inftead of impelling the tlailic ball C 
 by the ftroke of the elaftic ball A, we may caufe /\ to 
 ftrike an intermediate ball B (alfo perfeAly elallic), 
 which is lying in cnntaft with C. In many cafes, the 
 ball B will not ftir fenlibly from its place, and C alone 
 will fly off. Nay, if a long row of equal billiard balls 
 lie in coiitaft, and one of the extreme balls be hit by 
 another ball in the direftion of the row, only the re- 
 mote ball of the row will fly off. All this is ealily fcen 
 and underilood, by confidering them as bodies mutually 
 repelling, and placed at the limits of their mutual ac- 
 tion. Or even fuppofnig them clalh'c balls, at a very 
 fmail diilance from each other : The ball employed to 
 ftiike the firil comes to rell, and the ftrikeu ball moves 
 cfF with its velocity : It ftrikes the fecond ball of the 
 row, and is brought to refl: : The fecond Ihikes the 
 third, and Is brought to reft : And this goes on in 
 fucceirion to the laft, which is the only one that can 
 fly off. The curious obfervation of Mr Huyghens is, 
 that a greater velocity will be communicated by a lar^e 
 ha!' to a irnall one, it we employ the intermedium of 
 another ball of a fizc between the tv.-o ; and that the 
 ■velocity will be the grcateft poffible when the interme- 
 diate ball is a mean proportional (geometrical^ between 
 the two. This is alfo eaiily deduced from the funilar 
 attention to the atliou of the accelerating forces, or 
 from the fuppolition of fucccfiive impulfes. From this 
 it alfo follows that u greater velocity will be produced 
 by the intervention of two, three, or more, mean pro- 
 portionals. 
 
 But the direiSion of the ftroke may not be the fame 
 with that of the motion. This is called oblkiue im- 
 pulse. The cafes of oblique collifions are extremely 
 different, according to the direftions of the motions; 
 and the refults are, in many of them, far from being 
 obvious. But we have not room for a particular treat- 
 tsent of tbem. W« fhall therefore avail ourfelvea of 
 
 Oil-.f 
 
 63 
 
 f Tm- 
 
 S^LSXON. 
 
 07 ] IMP 
 
 fome of the general faAs mentioned above, by means (mpiiHion, 
 of which we may reduce .ill the varieties to fome tafy "— v— ' 
 cafes. The molt fcrviceable general facts are: 1. That 
 the adlions of bodies on each other depend on their re- 
 lative motions ; and, 2. That the motion of the common 
 centre is not changed by the collilion. Thefe enable 
 us to reduce all to the cafe of a body in motion ftri- 
 kiug another at reft. We have only to determine their 
 relative motion by the propjlition in Dynamics, n''' 67. 
 and then to fuperadd the common inotiuu, which chan- 
 ges the relative into the true motions. Thus if two 
 bodies A and B (11^.4.) meet in I), difcrlbing the 
 lines AD, BD, the coUifiun is the fame as if B had re- 
 mained at rcll, and A hail come agaiult it will) the mo- 
 tion AB. In the mean time, the comnton centre of 
 pofition has defci ibcd CD. If the bodies arc unelallic, 
 they remain united, and proceed in the line CD priidii- 
 ced toward E, and their common velocity will be repre- 
 fented by DE, equal to CD, if AD and BD reprelent- 
 ed their initial velocities. If the bodies are elaftic, they 
 leparate again, and they feparate from the common 
 centre in the oppofite direc\io.i, and with the fame ve- 
 locities with which they approached it. Therefore 
 draw a E i parallel to ACB, and nike E <?, E i equal 
 to CA and CB, and then D c( and D A are the paths 
 and velocities of the bodies. All this is abundantly 
 plain, and is a neceffai-y deduftiou from the general 
 principle, that the motion of the centre is not affefteil 
 by any equal and oppijfite forces which connccl the 
 bodies of a fyftem. - 
 
 But this great fnnplicity is not fufficient for afcer- orien ac- 
 taining the relults of collifion which occur in many of comparieJ 
 the moft important cafes. It not only fuppofes that ^i' '''"■'• 
 AD aiid ED are exaftly proportional to the velocities '"'^' 
 of A and B, but alfo that they meet, fo that the plaui; 
 of mutual contail is perpcndiciilar to the line AB, ajul 
 that the ftroke on each is direiled to its centre. Thefe 
 cireumftances will not always be combined, tven in the 
 cale of fphciical bodies. The conlcqutnce will be, that 
 although the motion of the centre remains the fame, 
 that of the bodies may fometimes be difietent. We 
 mull therefore give a gencial propofition, v/hich will, 
 with a little tiouble, enable the reader to dttcruu'ne all 
 the motions wliich can take place, whether progreflTivc 
 or rotative. -g 
 
 Let the body A (fig. 5.), moving with the velocity General 
 V, in the dircdion AD, lliike the bocfy B at reft. Let ''■■eo"'". 
 F be the point of mutual contad, and /jFH a plane 
 touching both bodies in F. Draw -\FP jierpcndicu- 
 lar to this tangent plane, and through G, the centre 
 of pofition of B, draw PGC perpendicular to FP, and 
 GI parallel to FP. Let C, in the line FG, be the 
 fpoiiianeous centre of converfion (Rotatio>j, Encycl. 
 n°77. 8:c.), correfponding to the point of perculfiou 
 F. Join CF. Let the diredion cut the tangent plane 
 in H, and PF in A ; and let AH reprefent the velo- 
 city V. 
 
 The impulfe is made at the point F, in the diredion 
 AF or FP, and the centre of pofition of the body B 
 will advance in the diredion GI, parallel to FP, the di- 
 redion of the ttfedive impulfe. But becaufe this does 
 not pafs through the centre G, the body will advance,, 
 and will alfo turn round an axis pafling through G, 
 perpendicular to the plane of the lines GP, PF, and-. 
 the fpontaneous axis of cuaverfion will palj through^ 
 
 fome.
 
 1 M V 
 
 C 8c8 1 
 
 I M P 
 
 ♦mpuiri'ii, f(jn:je pgJnt C of tlit I'm; FG, and will alfo be perpen- 
 • diculaito the fame plane. All this has been deinonitra- 
 tcd in the articli; Rotation, n° 94, &c. Complete 
 the parallelogiam AFHE. It is plain, that the mo- 
 tion AH is equivalent to AE and AF. By the mo- 
 tion AE, A only Aides along the I'urface of B without 
 prefTinsT it, or canfing any teridency to motion in that 
 direction, except perhaps a little arifing from fritlion. 
 [t is by the motion AF alone that the jmpulfe is made. 
 
 AF 
 Therefore let •« be = V X -x-n ; and then AXv may 
 
 71 be called the efficient impulfe of the body A in the pre- 
 ■Efficient fg„t circunidancea, and v the efficient velocily. This will 
 velocity. j^^ diminillied by the coUihon. Let k be the unknown 
 velocity remaining in A after the coUifion, or rather in 
 the inftant of the greatelt compreflion and common mo- 
 tion of the touching points of A and B, elliniated fn 
 the direftion FP. The effcftlve momentum loft by A 
 miift therefore be A X i> — -v : but the fame muft be 
 gained by B, and its centre G mull move in the direc- 
 tion Gl, parallel to FP, with this momentum ; and 
 
 therefore with the velocity 
 
 :. That this 
 
 B 
 
 may be the cafe, the point of percufiion F muit )i.ld 
 with the velocity «, becaufe the bodies are in contact. 
 But becaufe C is the fpontaneous axis of Gonverfion,, 
 tvery particle is iegirnii/i-r to defcribe an arch of a circle 
 round this axis. Therefore F is beginning to move in 
 the diretlion F^', perpendicular to the momentai y ra- 
 dius vedlor CF. Let F^' be a very minute arch, de- 
 fciibedin a moment of time. Draw _§-_/" perpendicidar 
 to FP. Then F.yis the mistion F_;' reduced to tlie di- 
 rcclion FP, and will exprcfs the yielding of B in the 
 direftion of the impulfe, while G defciibes a fpace 
 
 equal to — 1 , and A defcrihes a fpace x. There- 
 
 'fore Yg will (xprefs x. Let P/> be the fptice defcribed in 
 the fame time that F^ is defcribed. DraVv^C, cutting 
 GK in the point L GI is the yielding of the body B to 
 
 A Xv — v 
 
 B 
 
 the impulfe, and muft therefore be equal to 
 
 The triangles F/g and CPF are limilar ; for the 
 angle CFP is the complement of Yfg to a right angle : 
 It is alfo the complement of PCF to a right angle. 
 Therefore F.g : F/ = FC : CP. But F^r : p p = 
 FC : CP ; beeaule the little arches F^, Fp have the 
 fane angle at C-w 'J'herefore Fp =:Ff, = x. It is 
 plain, th at CG ; Ct = GI : P/. Therefore CG : CP 
 A 
 
 Xd - 
 
 = ■u X 
 
 B 
 
 AxCP 
 
 BxCG 
 
 — : X, aid .V r: 
 
 A X •J' — X X CP 
 
 K X B X CG -f 
 X B xTg 
 = ^•X 
 
 BxCG 
 wherefore 
 X A X CP = ■» X A X CP, 
 
 A_><CP 
 "''^BxGG' 
 
 and 
 
 + AxCP = >uXAx CP, and 
 
 AxCP , , . 
 
 — 7-T^, — the velocity remam- 
 
 71 
 Unelaftic 
 fcodies may 
 f«j>arate. * 
 
 B X CG + A x CP 
 
 ing in A, tlllmated iii the direction FP. 
 
 And a, the velocity with which G will advance, is 
 
 C(^ 
 
 ^ ; for CF-.CG = Fp -.Gl, = X : u. It is evi- 
 dent that A will change its direftion by the collifion i 
 For in the inftant of greateft compreflion, it was readi- 
 
 ed on by a force = A X -y — x in the direftion FA. hiip'i^i'W^. 
 This mull be compounded with AxV, in the direction » 
 AH, in order to obtain the new motion of A ; or it 
 may be found by compounding x, which is retail. ed by 
 A, with FH, which has fuffered no change by the col- 
 lifion. The bodies will therefore teparaie, although 
 they be unelaftic : If they are cLilic, we muft doubic 
 thefe changes on each. If B was alfo in motion before 
 the collifion, the motion of A mull: be rtUiived into 
 two, one of v.hich is equal and parallel to the motion 
 of B : the other muft be employed as we have employ- 
 ed the motion AH. 
 
 Expreffions ftill mdre general may be obtained for .v 
 and u ; naniel\", by talcing the formuLi; for the centres 
 of confreifiim arid pcrcuiriuu (Rotation', n" 96, 99.) 
 
 //>r' y^. /■' -f B X CP' 
 '^^^ = Bl^GP' =^"'1 C P = Bx^GP ~' 
 
 where p ftands for a particle of matter, and r for its 
 diltance from an axis pafting through G perpendicul.ir- 
 ly to the plain of the lines GP and PF. In this way 
 
 A-./z-r'-f A-BGP' 
 
 we obtain *; = 
 
 + B 'fp r'- -f A-B-GP' 
 
 73 
 
 It is plain from this propofition, that the progrcflive change of 
 motion of the body depends, not only on the momen-i rtgrcQive 
 turn of the imptlling body, but alfo on the place where '"'""'°" 
 the other is ftruck : For even although the original mo-^^.j^^j^'^j^^ 
 mentum of A be the fame, and the obliquity of the(iire.':lion of 
 ftroke, making -v the fame, and the body (and confe-the effcc- 
 
 y-^ five ftr< ke 
 
 pr'^ alfo remain the fame, we fee that x and ; "'"'s 'hio' 
 u depend on the ratio of CP to CG. Now C and P''^^ "'""'" 
 are always on oppofite fides of G : Conlequently, by 
 removing the direi^lion FP of the impuKlon farther 
 from G, v\c diininifli CG and incrcafe CP ; and there- 
 
 ACP 
 
 fore increafe the value of .\- =r 1' - 
 
 and 
 
 BCG-hA-CF' 
 confequently diminifii the value of AX'!' — x, to which -• 
 
 B X u is equal. The greateft momentum of B is pr.)- J 
 
 duced when the direftion of the impulfe pafTes through ' 
 
 Cj, and no rotation is produce;}. Indeed we are led, 
 bv a fort of conmion fenfe, to expefi th:s. 7^ 
 
 This invelligation is by no means a piece of mere Imporranc* 
 fpecuhtive curiolity. It is the folulion of the greateft"' -'"^ 'lie* 
 problem in praftical mechanics. It is in this way tliat "^^^^ q^- 
 we muft proceed in computing the adlions ot the windj^c. 
 and water on tlie fails and hull of a (liip, Were it 
 not that many circuniibnces cOfiCur in dLtcrmining fe- 
 ver^lof tile preparatory fteps, it is evident that the talk 
 muft be almoft impraClicable. But'the prelFure and its 
 direftion are gfrierally determined by experiment, -with- 
 out the trouble of computation ; and we are feldom fo- 
 licitous about the fubfequent motion of the wind or 
 water. 
 
 There is another queftion in impuhion which is of in,|,„i"]^oD 
 the firft practical importance — namely, when the im-oii bodies 
 pulfe is exerted on the parts of a machine, where the=oiifi:'.ed 
 body ftruck is not at liberty to yield freely to the|°^l'"['^^^'^" 
 ftroke, but muft Aide along fomc folid path, or turn 
 round fome axis, or take fome other conftrained mo- 
 tion. The operations of moft engines depend on this. 
 The operation of wedges, axes, and many cutting and 
 piercing inftruraents, and the penetration of piles, im- 
 pelled
 
 » ('.rii-i.oTiivE,l'i-.v!rK XXIX. 
 
 Fio- 1 
 
 Vf^U. 
 
 1: 
 
 _T M r x^ L S I o X 
 
 Fio-.l. 
 
 i%.3 
 
 &;■--- 
 
 Fig. 4
 
 I 
 
 i 
 
 i
 
 IMP [ 8oy ] IMP 
 
 'tiipulfion. pelle.lby a rammer, are all afcertaincd by tlie fame doc- nothing in wliich tlie fcicntific knowli'dp^c of tlic en- Tiripi'do;). 
 
 *o*'v" trincs. But the particular applications can fcarccly bo gineer is of more eflltitiat fervice to him. An en- """V— ' 
 
 elucidated by any clairification that occurs to us, the gineer of great pradice, and a figacious combiniiiij 
 
 circumftances of the cal'e making fuch great dlflcrence mind, collefts his general obfcrvationj, and ftores them 
 
 in the refult, both in kind and degree. For example, up as rules of future pradice. But it is feldom that 
 
 in the fimpleft cafe that occurs, the driving of piles, the he poflttres them with that didinilni fs and confidence 
 
 penetration of the pile depends, in the full pl.ioe, on the that can enable him to communicate his !::iovvledge to 
 
 momentum of the rammer. If the mafs of the pile be others, or even fecure himfelf againft all millakes ; 
 
 neglefted, the penetration througli a uniformly relilliiig whereas a moderate acquaintance with ihefe efnn,nls of 
 
 fubllance will be as the fquare of the velocity of the real mechanics, may be applied with fafety on all occa 
 
 77 
 
 fions, becauie arithmetical computations, wlieu rightly 
 made, afford the mod certain of all refults. 
 
 There is a circumlLuice which greatly affefts the per- GnA'tnU 
 formance of machines which are aftuated hy impulfes,"f I <"'=r 
 namely, the yielding and b';nding of the parts. When^'.^ '^'^ 
 the moving power ads by repeated fmall impulfions, it jnj v'.^j. 
 may fometimes be entirely confumed, without produ-in. <>; :lii: 
 cing any effed whatever at the remote woiking point 'i"''"'''- 
 of the machine ; and the engineer, who founds iiis con- 
 
 rammer (Dynamics, Siippl. n" 95.), and its abfikite 
 quantity may be determined from a knowledge of the 
 proportion of the weight of the rammer to the lefiitancc 
 of the earth. But when we eonfider that we have to 
 put in motion the Vi-hole matter of the pile, we learn 
 that a gi'eat diminution of the effed mull take place. 
 We Hill can compute what this mull be, becaufe we 
 have the fame momentum, with a velocity dimiiiifhed in 
 a certain proportion of the fum of the matter in the 
 
 rammer and pile, to that in the rammer alone.— An- ftrudions on the elementary theories to be had in moft 
 
 other defalcation arifes from fridion, which continually treatifes of mechanics, will often be miferably difap- 
 
 increafes as the pile goes deeper ; — and a Hill greater pointed. In the ufual theories, even as delivered by 
 
 defalcation proceeds from the nature of the pile. If it writers of eminence, it is aiTerted, that the fm;i!!e(l im- 
 
 is a piece of very dry ftralght grained fir, it is very pulfe will ftart the grcatcft weight. But fince impulfe 
 
 ' elallic, and acquires almoft a double velocity from the is only a continued prtirnre, and requires time for th« 
 
 ftroke of a rammer of calf iron. If it is moill and foft, tranfmiflion of its efted through the parts of a yielding 
 
 efpecially if it is oak, or other timber of an undulated folid, it is plain that the motion of the impelling body 
 
 ■fibre, it does not acquire fo great velocity, and the pe- may be extinguifned before it has produced comprcl'- 
 
 jietration is very much diminilhed. It is probable thit fion enough tor exciting the forces which are to raife 
 
 a pile, headed with moift cork, could not be driven at the remote parts of a heavy body from the ground, 
 
 all. The writer of this article found a remarkable ef- What blow with a hammer could itart a feather bed ? 
 
 fed of the elafticity in the procefs of boring limeflone. Much ottener may we expcd, that a blow, given to 
 
 When the boring bit was made entirely of Heel, and one arm of a long lever, will be confumed in bending 
 
 tempered through its whole lengtii to a hard fpring the whole of its length, 'fo as to bring the remote end 
 
 temper, the workman bored three inches, in the fame into adion. Therefore great ilillncls, and pcrfed ela- 
 
 time that another bored two inches with a bit uiade of fticity, both in the moving parts and in the points of 
 
 foft iron ; and he would never ufe any but Heel bits, if fupport, are necelfary for tranfmitting the full, or even 
 
 they could be hindered from chipping by the hammer a confiderable part, of the power of the impelling body, 
 
 (which muH alfo be of tempered Heel throughout). Perhaps not the half of the blow given by the wipers 
 
 InipulGon 
 en ma- 
 shines. 
 
 This has hitherto baffled many attempts. A pretty large 
 round head, like a marlin fpike, has lucceeded beH : but 
 even this cracks after fome days ufe. The improvement 
 IS richly worth attention ; for the workman is delight- 
 ed by feeling the hammer rife in his hand after every 
 llroke, and fays that the work is not fo hard by half. 
 N. B, The Hone cutters at Lifton and Oporto ufe iron 
 mallets. 
 
 of a great forge or tilting mill to the (liank of the ham- 
 mer is tranlmitted in the proper inHant of tinv; to llse 
 hammer-head. The hammer, while it is tolled up by 
 the blow, is quivering as it flies. Should it reach the 
 fpring above it in the time of its downward vibration, 
 it will not be returned with fuch force as if it had hit 
 the fpring a moment before or after. A quaiter of an 
 inch will produce a great effed in fuch cafes. It is 
 
 The cafe of impulfion made on part of a machine found, that the minute impulles given to the pallets of 
 moveable round an axis has been conlidered In the ar- a clock or watch lofe much of their force by the im- 
 ticle Rotation, Encycl. n'^ 72; where x is Hiewn to perfed elaHicity of the pendulum or balance. We 
 
 be = <u X 
 
 A-CP' 
 
 But, in this formula, r de- 
 
 muH therefore make all the parts which tranfmit the 
 blow to the regulating mal's of matter as continuous, 
 hard, elaHic, and HifT, as {uuTible. The performance of 
 ruby pallets is very fenfihly weakened by putting oil on 
 the face of them, efpecially in the detached fcapements, 
 which ad partly by impulfe. A wheel of hard tem- 
 pered Heel, working on a dry ruby pallet, excels all 
 others. The iijtelligent engineer, feeing that, alter all 
 his care, much impullion is unavoidably loH, will avoid 
 In the pradical confideration of this queHion, the employing a tirll mover which ads in a fubfultory man. 
 
 //./-'-l-ACP' 
 notes the diftance of ^ from the point C, and not from 
 
 G. J pr^ in this formula, is B*CG-CP ; whereas, in 
 the formula for a free body, where r is the diHance of 
 
 a particle from G,J pr^ is = B-CG-QP. 
 
 reader will do well to eonfider the whole of that article 
 with attention. Many circumHances occur, which make 
 a proper choice of the point of impulfe, and the direc- 
 tion of the tangent plane, of the greateft confequence 
 to the good performance of the machine ; and there is 
 SufPi. Vol. I. Part II. 
 
 ner, and will fubHitute onu of continued prcffiire when 
 it is In his power. This Is one chief caufe of the great 
 fuperiority of overlhot water wheels above the underlhot. 
 We can now underdand how it happens that Gal- 
 lileo, Merfennus, and others, could compare the impulle 
 5 K given
 
 IMP 
 
 t 8io 1 
 
 I M P 
 
 Imp ilfion.. given by a falling body with the pTe/Tiirc of a weight 
 f^~~' in the oppofite fcale of a balance, and can fee the rea- 
 fon of the imnienfe dilFcre.ices, ytt accompanied by a 
 fovt of regnlarlty, in the refiilts of the txperiments. Ga- 
 liko, Mciftnnus, and Riecioli, found them to he proofs 
 that the forces of moving b'>dies are as their velocities; 
 btcaufe the heights fi oir. which the body fell were as the 
 fquares of the weights ilarted from the ground. Grave- 
 iande found the ftime thing as long as lie held the iame 
 opinion ; but when he adopted the Leibnitzian meafure, 
 he found many faults in the apparatus employed in his 
 former illuftrations, and altered it, till he obtained re- 
 ftilts agreeable to his new creed. But any one who ex- 
 amines with attention all that paffes in the bending of 
 the apparatus, and takes into account the mafs of mat- 
 ter which muft be difplactd betore the oppofite arm 
 rifes fo far as to detach the fpring which gives indica- 
 tion of the magnitude of the llroke, muft fee that the 
 agreement is purely accidental, and may be procured 
 for any theory we pleafe (fee GfavefanJe's Nat. Phil. 
 tranflated by Defaguiliers, vol. i. p. 241. &c.) The 
 propofition, n° 95, Dynamics, fuflices for explaining 
 every thing that can happen in fueh experiments. And 
 it will (hew us, that although the motion of impulfion 
 is produced by prefTure alone, yet impulfe is incompa- 
 rable with mere prefFure : It is not infinitely gi-eater, 
 but difparate. A weight (which is a preffure) bends 
 a fpiing to a certain degree, and will derange to a cer- 
 tain degree the fibres of a body on which it prefles, be- 
 fore it be balanced. The lame weight, falling on this 
 fpring from ihe. fmalleft height, will bend it farther, and 
 may crufh or fhiver to pieces the body which would have 
 carried it for ever. We fhall make fonie further remarks 
 on this fuhjeft, of great practical importance, under the 
 word Pekcussion. 
 
 CoNciu The method which we have purfued in confidering 
 
 jioN. the dottrines of impulfion, differs confiderably from that 
 
 which has generally been followed ; but we truil that 
 it will not be found the lefs inftriiftive. Although 
 the reader fiiould not adopt our decided opinion, that 
 we have no proof of pure impulfion ever being ob- 
 fervf d, and that all the phenomena which go by that 
 name are really the effefts of preffures, analogous to 
 gravity, he perceives that our opinion does not lead 
 to any general laws of impulfion that are different 
 from thofe which are acknowledged by all. We differ 
 only, by exhibiting the internal procedure by which 
 they are unquejiionably produced in a vaft number of 
 cafes, and which takes place in all that we have feen, 
 in fome degree. Our method has undoubtedly this ad- 
 vantage, that it requires no principle but one, namely, 
 that accelerating forces are to be eftimated by the ac- 
 celeration which they produce. Even this may be 
 confidered, not as a principle, but merely as a defini- 
 tion — We get rid of all the obfcurity and perplexity 
 that refult from the introdudlion of inertia, confidered 
 
 as a power - a power of doing nothing ; and we are Irijiultoni 
 freed from the unphilofophical fidlion (adopted by all the ""■"'" "^ 
 abettors of that doctrine, and even by mSny others) of 
 conceiving the fpace, in which motions are performed, 
 and bodies aft, to be carried along with the bodies in 
 it. — This turniflies, indeed, in fome cafes, a familiar 
 way of conceiving the thing, by fuppofing the experi- 
 ments to be made in a fiiip under fail, and by appeal- 
 ing to the taA, that all (mr experiments are made on 
 the furface of a globe that is moving with a very great 
 velocity. But it is an abfurdity in phllofophv, and, 
 when minutely or argunientatively uf«d, it does not 
 free us from one complication of aflion ; for, before we 
 can make ufe of this fubftitution, we muft demonftrate, 
 that the aftions depend on the relative motions only : 
 And this, vvlien dcmonftrated, obliges us to meafure 
 forces by the velocity which they produce. 
 
 As no part of mechanical philofophy has been fo 
 much debated about as impulfion, it will furely be a- 
 greeable to our readers to have a notice of the different 
 treatifes which have been publifhed on the fubjedl : 
 
 Galilei Opera, T. I. 957. II. 479, &c, 
 
 Jo. Walh'fii Traftatus de PercufEone. Oxon. 1669. 
 
 Chr. Hugenius de Motu Corporum ex Percuflione. 
 Op. II. 73. 
 Traite dela Percuflson des Corps, parMariotte, Op.I. T. 
 
 Hypothefis Phyfica Nova, qua phenomenorum cau- 
 fse ab unico quodam univerfali motu in noltro globo 
 fuppofito repetuntur. Audt. G. G. Lcibnitzjo. Mo- 
 guntice 1671. — Leibn. Op. T. II. p. II. 3. 
 
 Ejufdem Theoria Motus Abftrafti. Ibid, 35. 
 
 Hermann! Phoronomia. Amll. 1716. 
 
 DIfcours fur les Loix de la Communication de Mouve- 
 ment, par Jean Bernoulli, Paris, 1727. Jo. Bern. 
 Oper. III. 
 
 Dynamique de D'Alembert. 
 
 Euleri Theoria Corporum folidorum feu rigidorum, 
 J765. 
 
 Borelli (Alphons) de PercufTione. 
 
 See alfo M'Laurin's Fluxions, and his Account of 
 Newton's Philofophy, for his Dilfertation crowned by 
 the Acad, des Sciences at Paris. — Alfo Dr Jurin's ela- 
 borate differtations in the Phil. Tranf. N° 479 Alfo 
 
 Gravefande's Nat. Philofophy, where there is a mofk 
 laborious colleflion of experiments and reafonings ; all of 
 which receive a complete explanation by the 39th Prop. 
 Princip. Neutoni I. or our n°9 5. Dynamics. There are 
 alfo many very acute philofophical obfervations in Lam- 
 bert^ s Gedanken iiber die Grundlehren des Gleichgezuichts, 
 und der Beivegung. in the fecond part of his Gebrauch 
 der Mathematik. — Alfo, in the works of Kaeftner, 
 Hamberger, and Bufch. Mufchenbroeck alfo treats the 
 fubjeft at great length, hut not very judicioufly. We 
 do not know any work which treats it with fuch per- 
 fpicuous brevity as M'Laurin's Account of Newton's 
 Philofophy. 
 
 END OF THE FIRST VOLUME.
 
 DIRECTIONS FOR piacing ths PLATES. 
 
 PartL 
 
 Plate T. 
 
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 VI. 
 VII. 
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 XIX. : 
 
 ■ 398 
 
 Par- 
 
 rll. 
 
 
 Plate XX. 
 
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 - 4.64. 
 
 XXI. 7 
 
 
 
 XXII. J. 
 
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 ■ 548 
 
 XXIII. 3 
 
 
 
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 XXIX. 
 
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 80S 
 
 JEBinliurffTj : 
 
 FRINTED BT JOHN BROWN, ANCHOR CLOSE. 
 1802.
 
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